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Copper is a chemical element with the symbol Cu (from Latin: cuprum) and atomic number 29. It is a ductilemetal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish. It is used as a conductor of heat and electricity, a building material, and a constituent of various metal alloys.HP Pavilion DV4 Battery

The metal and its alloys have been used for thousands of years. In the Roman era, copper was principally mined on Cyprus, hence the origin of the name of the metal as ?yprium (metal of Cyprus), later shortened to ?uprum. Its compounds are commonly encountered as copper(II) salts,HP Pavilion DV4-1000 Battery

which often impart blue or green colors to minerals such as turquoise and have been widely used historically as pigments. Architectural structures built with copper corrode to give green verdigris (or patina).Decorative art prominently features copper, both by itself and as part of pigments.HP Pavilion DV4-1000EA Battery

Copper(II) ions are water-soluble, where they function at low concentration as bacteriostatic substances, fungicides, and wood preservatives. In sufficient amounts, they are poisonous to higher organisms; at lower concentrations it is an essential trace nutrient to all higher plant and animal life. The main areas where copper is found in animals are tissues, liver, muscle and bone.HP Pavilion DV4-1000ET Battery

Copper, silver and gold are in group 11 of the periodic table, and they share certain attributes: they have one s-orbital electron on top of a filled d-electron shell and are characterized by high ductility and electrical conductivity. The filled d-shells in these elements do not contribute much to the interatomic interactions, which are dominated by the s-electrons through metallic bonds.HP Pavilion DV4-1001 Battery

Contrary to metals with incomplete d-shells, metallic bonds in copper are lacking a covalentcharacter and are relatively weak. This explains the low hardness and high ductility of single crystals of copper.At the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress thereby increasing its hardness.HP Pavilion DV4-1001AX Battery

For this reason, copper is usually supplied in a fine-grainedpolycrystalline form, which has greater strength than monocrystalline forms.

The low hardness of copper partly explains its high electrical (59.6×106 S/m) and thus also high thermal conductivity, which are the second highest among pure metals at room temperature.HP Pavilion DV4-1001TU Battery

This is because the resistivity to electron transport in metals at room temperature mostly originates from scattering of electrons on thermal vibrations of the lattice, which are relatively weak for a soft metal. The maximum permissible current density of copper in open air is approximately 3.1×106 A/m2 of cross-sectional area, above which it begins to heat excessively.HP Pavilion DV4-1001TX Battery

As with other metals, if copper is placed against another metal, galvanic corrosion will occur.

Together with osmium (bluish), and gold (yellow), copper is one of only three elemental metals with a natural color other than gray or silver.[6] Pure copper is orange-red and acquires a reddishtarnish when exposed to air.HP Pavilion DV4-1002 Battery

The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells is such that it corresponds to orange light. The same mechanism accounts for the yellow color of gold.HP Pavilion DV4-1002AX Battery

Chemical

Copper forms a rich variety of compounds with oxidation states +1 and +2, which are often calledcuprous and cupric, respectively.It does not react with water, but it slowly reacts with atmospheric oxygen forming a layer of brown-black copper oxide.HP Pavilion DV4-1002TU Battery

In contrast to the oxidation of iron by wet air, this oxide layer stops the further, bulk corrosion. A green layer of verdigris (copper carbonate) can often be seen on old copper constructions, such as the Statue of Liberty, the largest copper statue in the world build using repoussé and chasing.HP Pavilion DV4-1002TX Battery

Hydrogen sulfides and sulfides react with copper to form various copper sulfides on the surface. In the latter case, the copper corrodes, as is seen when copper is exposed to air containing sulfur compounds. Oxygen-containing ammonia solutions give water-soluble complexes with copper,HP Pavilion DV4-1003AX Battery

as do oxygen and hydrochloric acid to form copper chlorides and acidified hydrogen peroxide to form copper(II) salts. Copper(II) chloride and copper comproportionate to form copper(I) chloride.

There are 29 isotopes of copper. 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper; they both have a spin of 3/2.HP Pavilion DV4-1003TU Battery

The other isotopes are radioactive, with the most stable being 67Cu with a half-lifeof 61.83 hours.Seven metastable isotopes have been characterized, with 68mCu the longest-lived with a half-life of 3.8 minutes. Isotopes with a mass number above 64 decay by ?-, whereas those with a mass number below 64 decay by ?+. 64Cu, which has a half-life of 12.7 hours, decays both ways.HP Pavilion DV4-1003TX Battery

62Cu and 64Cu have significant applications. 64Cu is a radiocontrast for X-ray imaging, and complexed with a chelate can be used for treating cancer. 62Cu is used in 62Cu-PTSM that is a radioactive tracer for positron emission tomography.HP Pavilion DV4-1004AX Battery

Occurrence

Copper can be found as either native copper or as part of minerals. Native copper is a polycrystal, with the largest described single crystal measuring 4.4×3.2×3.2 cm. The largest mass of elemental copper weighed 420 tonnes and was found in 1857 on the Keweenaw Peninsula inMichigan, US.HP Pavilion DV4-1004TU Battery

There are many examples of copper-containing minerals: chalcopyrite and chalcocite are copper sulfides, azurite and malachite are copper carbonates and cuprite is a copper oxide. Copper is present in the Earth's crust at a concentration of about 50 parts per million (ppm), and is also synthesized in massive stars.HP Pavilion DV4-1004TX Battery

Production

Most copper is mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits that contain 0.4 to 1.0% copper. Examples include Chuquicamata in Chile,Bingham Canyon Mine in Utah, United States and El Chino Mine in New Mexico, United States.HP Pavilion DV4-1005TX Battery

According to the British Geological Survey, in 2005, Chile was the top mine producer of copper with at least one-third world share followed by the United States, Indonesia and Peru. The amount of copper in use is increasing and the quantity available is barely sufficient to allow all countries to reach developed world levels of usage.HP Pavilion DV4-1006TX Battery

Reserves

Copper has been in use at least 10,000 years, but more than 95% of all copper ever mined andsmelted has been extracted since 1900. As with many natural resources, the total amount of copper on Earth is vast (around 1014 tons just in the top kilometer of Earth's crust, or about 5 million years worth at the current rate of extraction).HP Pavilion DV4-1007TX Battery

However, only a tiny fraction of these reserves is economically viable, given present-day prices and technologies. Various estimates of existing copper reserves available for mining vary from 25 years to 60 years, depending on core assumptions such as the growth rate.HP Pavilion DV4-1008TX Battery

Recycling is a major source of copper in the modern world. Because of these and other factors, the future of copper production and supply is the subject of much debate, including the concept of Peak copper, analogue to Peak Oil.

The price of copper has historically been unstable, and it quintupled from the 60-year low of US$0.60/lb (US$1.32/kg) in June 1999 to US$3.75 per pound (US$8.27/kg) in May 2006.HP Pavilion DV4-1009TX Battery

It dropped to US$2.40/lb (US$5.29/kg) in February 2007, then rebounded to US$3.50/lb (US$7.71/kg) in April 2007.[21] In February 2009, weakening global demand and a steep fall in commodity prices since the previous year's highs left copper prices at US$1.51/lb.HP Pavilion DV4-1010TX Battery

Methods

The concentration of copper in ores averages only 0.6%, and most commercial ores are sulfides, especially chalcopyrite (CuFeS2) and to a lesser extent chalcocite (Cu2S). These minerals are concentrated from crushed ores to the level of 10–15% copper by froth flotation or bioleaching.HP Pavilion DV4-1011TX Battery

Heating this material with silica in flash smelting removes much of the iron as slag. The process exploits the greater ease of converting iron sulfides into its oxides, which in turn react with the silica to form the silicate slag, which floats on top of the heated mass.HP Pavilion DV4-1012TX Battery

The resulting copper matte consisting of Cu2S is then roasted to convert all sulfides into oxides:

2 Cu2S + 3 O2 ? 2 Cu2O + 2 SO2

The cuprous oxide is converted to blister copper upon heating:HP Pavilion DV4-1013TX Battery

2 Cu2O ? 4 Cu + O2

This step exploits the relatively easy reduction of copper oxides to copper metal. Natural gas is blown across the blister to remove most of the remaining oxygen andelectrorefining is performed on the resulting material to produce pure copper:

Cu2+ + 2 e–? CuHP Pavilion DV4-1014NR Battery

Recycling

Copper, like aluminium, is 100% recyclable without any loss of quality whether in a raw state or contained in a manufactured product. In volume, copper is the third most recycled metal after iron and aluminium. It is estimated that 80% of the copper ever mined is still in use today.HP Pavilion DV4-1014TX Battery

According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of Copper in use in society is 35–55 kg. Much of this is in more-developed countries (140–300 kg per capita) rather than less-developed countries (30–40 kg per capita).HP Pavilion DV4-1015TX Battery

The process of recycling copper follows roughly the same steps as is used to extract copper, but requires fewer steps. High purity scrap copper is melted in a furnace and then reduced and cast into billets and ingots; lower purity scrap is refined by electroplating in a bath of sulfuric acid.HP Pavilion DV4-1015TX Battery

Binary compounds

As for other elements, the simplest compounds of copper are binary compounds, i.e. those containing only two elements. The principal ones are the oxides, sulfides and halides. Both cuprous and cupric oxides are known.HP Pavilion DV4-1016TX Battery

Among the numerous copper sulfides, important examples include copper(I) sulfide and copper(II) sulfide.

The cuprous halides with chlorine, bromine, and iodine are known, as are the cupric halides with fluorine, chlorine, and bromine. Attempts to prepare copper(II) iodide give cuprous iodide and iodine.HP Pavilion DV4-1017TX Battery

2 Cu2+ + 4 I? ? 2 CuI + I2

Coordination chemistry

Copper, like all metals, forms coordination complexes with ligands. In aqueous solution, copper(II) exists as [Cu(H2O)6]2+. This complex exhibits the fastest water exchange rate (speed of water ligands attaching and detaching) for any transition metal aquo complex.HP Pavilion DV4-1018TX Battery

Adding aqueoussodium hydroxide causes the precipitation of light blue solid copper(II) hydroxide. A simplified equation is:

Cu2+ + 2 OH? ? Cu(OH)2

Aqueous ammonia results in the same precipitate. Upon adding excess ammonia, the precipitate dissolves, formingtetraamminecopper(II):HP Pavilion DV4-1019TX Battery

Cu(H2O)4(OH)2 + 4 NH3 ? [Cu(H2O)2(NH3)4]2+ + 2 H2O + 2 OH?

Many other oxyanions form complexes; these include copper(II) acetate, copper(II) nitrate, and copper(II) carbonate. Copper(II) sulfate forms a blue crystalline pentahydrate, which is the most familiar copper compound in the laboratory. It is used in afungicide called the Bordeaux mixture.HP Pavilion DV4-1020TX Battery

Polyols, compounds containing more than one alcohol functional group, generally interact with cupric salts. For example, copper salts are used to test for reducing sugars. Specifically, usingBenedict's reagent and Fehling's solution the presence of the sugar is signaled by a color change from blue Cu(II) to reddish copper(I) oxide.HP Pavilion DV4-1020US Battery

Schweizer's reagent and related complexes with ethylenediamine and other aminesdissolve cellulose. Amino acids form very stable chelate complexes with copper(II). Many wet-chemical tests for copper ions exist, one involving potassium ferrocyanide, which gives a brown precipitate with copper(II) salts.HP Pavilion DV4-1021TX Battery

Organocopper chemistry

Compounds that contain a carbon-copper bond are known as organocopper compounds. They are very reactive towards oxygen to form copper(I) oxide and have many uses in chemistry.HP Pavilion DV4-1022TX Battery

They are synthesized by treating copper(I) compounds with Grignard reagents, terminal alkynes or organolithium reagents; in particular, the last reaction described produces a Gilman reagent. These can undergo substitution with alkyl halides to form coupling products; as such, they are important in the field of organic synthesis.HP Pavilion DV4-1023TX Battery

Copper(I) acetylide is highly shock-sensitive but is an intermediate in reactions such as the Cadiot-Chodkiewicz coupling  and theSonogashira coupling. Conjugate addition to enones and carbocupration of alkynes can also be achieved with organocopper compounds.HP Pavilion DV4-1024TX Battery

Copper(I) forms a variety of weak complexes with alkenes and carbon monoxide, especially in the presence of amine ligands.

Copper(III) and copper(IV)

Complexes of copper(III) are frequent intermediates in reactions of organocopper compounds. Dicopper oxo complexes also feature copper(III).HP Pavilion DV4-1025TX Battery

Fluoride ligands, being highly basic, stabilize metal ions in high oxidation states; indeed, representative copper(III) and copper(IV) complex are fluorides. These include K3CuF6 and Cs2CuF6. With di- and tripeptides, purple-colored complexes of copper(III) have been observed, this high oxidation state being stabilized by the deprotonatedamide ligands.HP Pavilion DV4-1026TX Battery

Copper occurs naturally as native copper and was known to some of the oldest civilizations on record. It has a history of use that is at least 10,000 years old, and estimates of its discovery place it at 9000 BC in the Middle East; a copper pendant was found in northern Iraq that dates to 8700 BC.HP Pavilion DV4-1027TX Battery

There is evidence that gold and iron were the only metals used by humans before copper. Copper smelting was invented locally in several different places. It was probably discovered independently in China before 2800 BC, in Central America perhaps around 600 AD, and in West Africa about the 9th or 10th century AD.HP Pavilion DV4-1028TX Battery

Investment casting was invented in 4500–4000 BC in Southeast Asia and carbon dating has established mining at Alderley Edge in Cheshire, UK at 2280 to 1890 BC. Ötzi the Iceman, a male dated from 3300–3200 BC, was found with an axe with a copper head 99.7% pure; high levels of arsenic in his hair suggest his involvement in copper smelting.HP Pavilion DV4-1028US Battery

Experience with copper has assisted the development of other metals; in particular, copper smelting led to the discovery of iron smelting. Production in the Old Copper Complex in Michigan and Wisconsin is dated between 6000 and 3000 BC.HP Pavilion DV4-1029TX Battery

Bronze Age

Alloying of copper with zinc or tin to make brass and bronze was practiced soon after the discovery of copper. Bronze artifacts from Sumerian cities and Egyptianartifacts of copper and bronze alloys date to 3000 BC. The Bronze Age was from 2500 BC to 600 BC when usage of bronze was widespread in Europe;HP Pavilion DV4-1030EE Battery

the transition between the Neolithic period and the Bronze Age is termed the Chalcolithic period (copper-stone), with copper tools being used with stone tools. Brass was known to the Greeks, but became a significant supplement to bronze during the Roman Empire.HP Pavilion DV4-1030EI Battery

Antiquity and Middle Ages

In Greece, copper was known by the name chalkos (??????). It was an important resource for the Romans, Greeks and other ancient peoples. In Roman times, it was known as aes Cyprium, aes being the generic Latin term for copper alloys and Cyprium from Cyprus, where much copper was mined.HP Pavilion DV4-1030EJ Battery

The phrase was simplified to cuprum, hence the English copper. Aphrodite and Venus represented copper in mythology and alchemy, due to its lustrous beauty, its ancient use in producing mirrors, and its association with Cyprus, which was sacred to the goddess.HP Pavilion DV4-1030EN Battery

The seven heavenly bodies known to the ancients were associated with the seven metals known in antiquity, and Venus was assigned to copper.

Britain's first use of brass occurred around the 3rd–2nd century BC. In North America, copper mining began with marginal workings by Native Americans.HP Pavilion DV4-1030TX Battery

Native copper is known to have been extracted from sites on Isle Royale with primitive stone tools between 800 and 1600.[49]Copper metallurgy was flourishing in South America, particularly in Peru around 1000 AD; it proceeded at a much slower rate on other continents.HP Pavilion DV4-1031TX Battery

Copper burial ornamentals from the 15th century have been uncovered, but the metal's commercial production did not start until the early 20th century.

The cultural role of copper has been important, particularly in currency. Romans in the 6th through 3rd centuries BC used copper lumps as money.HP Pavilion DV4-1032TX Battery

At first, the copper itself was valued, but gradually the shape and look of the copper became more important. Julius Caesar had his own coins made from brass, whileOctavianus Augustus Caesar's coins were made from Cu-Pb-Sn alloys. With an estimated annual output of around 15,000 t,HP Pavilion DV4-1033TX Battery

Roman copper mining and smelting activitiesreached a scale unsurpassed until the time of the Industrial Revolution; the provinces most intensely mined were those of Hispania, Cyprus and in Central Europe.

The gates of the Temple of Jerusalem used Corinthian bronze made by depletion gilding. It was most prevalent in Alexandria, where alchemy is thought to have begun.HP Pavilion DV4-1034TX Battery

In ancient India, copper was used in the holistic medical science Ayurveda for surgical instruments and other medical equipment. Ancient Egyptians (~2400 BC) used copper for sterilizing wounds and drinking water, and later on for headaches, burns, and itching.HP Pavilion DV4-1035LA Battery

The Baghdad Battery, with copper cylinders soldered to lead, dates back to 248 BC to AD 226 and resembles a galvanic cell, leading people to believe this was the first battery; the claim has not been verified.

Modern period

The Great Copper Mountain was a mine in Falun, Sweden, that operated from the 10th century to 1992.HP Pavilion DV4-1035TX Battery

It produced two thirds of Europe's copper demand in the 17th century and helped fund many of Sweden's wars during that time. It was referred to as the nation's treasury; Sweden had a copper backed currency.

The uses of copper in art were not limited to currency: it was used by Renaissance sculptors, in pre-photographic technology known as the daguerreotype, and the Statue of Liberty.HP Pavilion DV4-1036TX Battery

Copper plating and copper sheathing for ships' hulls was widespread; the ships of Christopher Columbus were among the earliest to have this feature. The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.HP Pavilion DV4-1037TX Battery

The German scientist Gottfried Osann invented powder metallurgy in 1830 while determining the metal's atomic mass; around then it was discovered that the amount and type of alloying element (e.g. tin) to copper would affect bell tones. Flash smelting was developed by Outokumpu in Finland and first applied atHarjavalta in 1949;HP Pavilion DV4-1038TX Battery

the energy-efficient process accounts for 50% of the world’s primary copper production.

The Intergovernmental Council of Copper Exporting Countries, formed in 1967 with Chile, Peru, Zaire and Zambia, played a similar role for copper as OPEC does for oil. It never achieved the same influence, particularly because the second-largest producer, the United States, was never a member; it was dissolved in 1988.HP Pavilion DV4-1039TX Battery

Applications

The major applications of copper are in electrical wires (60%), roofing and plumbing (20%) and industrial machinery (15%). Copper is mostly used as a metal, but when a higher hardness is required it is combined with other elements to make an alloy (5% of total use) such as brass and bronze.HP Pavilion DV4-1040EE Battery

A small part of copper supply is used in production of compounds for nutritional supplements and fungicides in agriculture. Machining of copper is possible, although it is usually necessary to use an alloy for intricate parts to get good machinability characteristics.HP Pavilion DV4-1040EI Battery

Electronics and related devices

The electrical properties of copper are exploited in copper wires and devices such aselectromagnets. Integrated circuits and printed circuit boards increasingly feature copper in place of aluminium because of its superior electrical conductivity (see Copper interconnectfor main article);HP Pavilion DV4-1040TX Battery

heat sinks and heat exchangers use copper as a result of its superior heat dissipation capacity to aluminium. Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens use copper, as do wave guides for microwave radiation.

Architecture and industry

Because of the waterproof nature of copper, it has been used as the roofing material of many buildings since ancient times.HP Pavilion DV4-1041TX Battery

The green color on these buildings is due to a long-term chemical reaction: copper is first oxidized to copper(II) oxide, then to cuprous and cupric sulfide and finally to copper(II) carbonate, also called verdigris, which is highly corrosion-resistant. The copper used in this application is phosphorus deoxidized copper (Cu-DHP).HP Pavilion DV4-1042TX Battery

Lightning rods use copper as a means to divert electric current throughout the ground instead of destroying the main structure.[64]Copper has excellent brazing and solderingproperties and can be welded; the best results are obtained with gas metal arc welding.HP Pavilion DV4-1043TX Battery

Copper in alloys

Numerous copper alloys exist, many with important uses. Brass is an alloy of copper and zinc and bronze usually refers to copper-tin alloys, but can refer to any alloy of copper such as aluminium bronze. Copper is one of the most important constituents ofcarat silver and gold alloys and carat solders used in the jewelry industry, modifying the color, hardness and melting point of the resulting alloys.HP Pavilion DV4-1044TX Battery

The alloy of copper and nickel, called cupronickel, is used in low-denomination statuary coins, often for the outer cladding. The US 5-cent coin called nickel consists of 75% copper and 25% nickel and has a homogeneous composition. The 90% copper/10% nickel alloy is remarkable by its resistance to corrosion and is used in various parts being exposed to seawater.HP Pavilion DV4-1045TX Battery

Alloys of copper with aluminium (about 7%) have a pleasant golden color and are used in decorations. Copper alloys with tin are part of lead-free solders.

Antimicrobial applications

Copper-alloy touch surfaces have natural intrinsic properties to destroy a wide range of microorganismsHP Pavilion DV4-1046TX Battery

(e.g., E. coli O157:H7,methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridium difficile, influenza A virus, adenovirus, andfungi). Some 355 copper alloys were proven to kill more than 99.9% of disease-causing bacteria within just two hours when cleaned regularly.HP Pavilion DV4-1047TX Battery

The United States Environmental Protection Agency (EPA) has approved the registrations of these copper alloys as “antimicrobial materials with public health benefits,"  which allows manufacturers to legally make claims as to the positive public health benefits of products made with registered antimicrobial copper alloys.HP Pavilion DV4-1048TX Battery

In addition, the EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, handrails, over-bed tables, sinks, faucets,door knobs, toilet hardware, computer keyboards, health club equipment, shopping cart handles, etc. (for a comprehensive list of products, see: Antimicrobial copper-alloy touch surfaces#Approved products).HP Pavilion DV4-1049TX Battery

Copper doorknobs are used by hospitals to reduce the transfer of disease, and Legionnaires' disease is suppressed by copper tubing in plumbing systems. Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil and in the subway transit system in Santiago,HP Pavilion DV4-1050 Battery

Chile, where copper-zinc alloy handrails will be installed in some 30 stations between 2011–2014.

Antibiofouling applications

Copper has long been used as a biostatic surface to line parts of ships to protect against barnacles and mussels. It was originally used pure, but has since been superseded by Muntz metal.HP Pavilion DV4-1050EE Battery

Bacteria will not grow on a copper surface because it is biostatic. Similarly, as discussed in copper alloys in aquaculture, copper alloys have become important netting materials in the aquaculture industry for the fact that they are antimicrobial and prevent biofouling even in extreme conditions and have strong structural and corrosion-resistant properties in marine environments.HP Pavilion DV4-1050EL Battery

Other uses

Copper compounds in liquid form are used as a wood preservative, particularly in treating original portion of structures during restoration of damage due to dry rot. Together with zinc, copper wires may be placed over non-conductive roofing materials to discourage the growth of moss.HP Pavilion DV4-1050EP Battery

Textile fibers use copper to create antimicrobial protective fabrics, as do ceramic glazes, stained glass and musical instruments. Electroplating commonly uses copper as a base for other metals such as nickel.

Copper is one of three metals, along with lead and silver, used in a museum materials testing procedure called the Oddy test. In this procedure, copper is used to detect chlorides, oxides, and sulfur compounds.HP Pavilion DV4-1050ER Battery

Copper is also commonly found in jewelry, and folklore states that copper bracelets relieve arthritis symptoms, though this is not proven.

Biological role

Copper proteins have diverse roles in biological electron transport and oxygen transportation, processes that exploit the easy interconversion of Cu(I) and Cu(II).HP Pavilion DV4-1050TX Battery

The biological role for copper commenced with the appearance of oxygen in earth's atmosphere. The protein hemocyanin is the oxygen carrier in most mollusks and some arthropods such as the horseshoe crab(Limulus polyphemus). Because hemocyanin is blue, these organisms have blue blood, not the red blood found in organisms that rely on hemoglobin for this purpose.HP Pavilion DV4-1051 Battery

Structurally related to hemocyanin are the laccases and tyrosinases. Instead of reversibly binding oxygen, these proteins hydroxylate substrates, illustrated by their role in the formation of lacquers.

Copper is also a component of other proteins associated with the processing of oxygen.HP Pavilion DV4-1051TX Battery

In cytochrome c oxidase, which is required for aerobic respiration, copper and iron cooperate in the reduction of oxygen. Copper is also found in many superoxide dismutases, proteins that detoxify superoxides, by converting it (by disproportionation) to oxygen and hydrogen peroxide:HP Pavilion DV4-1052 Battery

2 HO2 ? H2O2 + O2

Several copper proteins, such as the "blue copper proteins", do not interact directly with substrates, hence they are not enzymes. These proteins relay electrons by the process called electron transfer.HP Pavilion DV4-1052TX Battery

Dietary needs

Copper is an essential trace element in plants and animals, but not some microorganisms. The human body contains copper at a level of about 1.4 to 2.1 mg per kg of body mass. Stated differently, the RDA for copper in normal healthy adults is quoted as 0.97 mg/day and as 3.0 mg/day.HP Pavilion DV4-1053 Battery

Copper is absorbed in the gut, then transported to the liver bound to albumin. It enters the bloodstream via the plasma protein called ceruloplasmin, where its metabolism is controlled, and is excreted in bile.

Copper-based disorders

Because of its role in facilitating iron uptake, copper deficiency can produce anemia-like symptoms,HP Pavilion DV4-1053TX Battery

neutropenia, bone abnormalities, hypopigmentation, impaired growth, increased incidence of infections, osteoporosis, and abnormalities in glucose and cholesterol metabolism. Conversely, an accumulation of copper in body tissues causes Wilson's disease.HP Pavilion DV4-1054TX Battery

Severe deficiency can be found by testing for low plasma or serum copper levels, low ceruloplasmin, and low red blood cell superoxide dismutase levels; these are not sensitive to marginal copper status. The "cytochrome c oxidase activity of leucocytes and platelets" has been stated as another factor in deficiency, but the results have not been confirmed by replication.HP Pavilion DV4-1055TX Battery

Antimicrobial properties

Numerous antimicrobial efficacy studies have been conducted in the past 10 years regarding copper’s efficacy to destroy a wide range of bacteria, as well asinfluenza A virus, adenovirus, and fungi.HP Pavilion DV4-1070 Battery

Extensive EPA-sanctioned tests using Good Laboratory Practices have found that when cleaned regularly, some 355 different EPA-registered antimicrobial copper alloy surfaces:

  • Kill greater than 99.9% of Gram-negative and Gram-positive bacteria within two hours of exposure;
  • Deliver continuous and ongoing antibacterial action, remaining effective in killing greater than 99.9% of bacteria within two hours;HP Pavilion DV4-1070EF Battery
  • Kill greater than 99.9% of bacteria within two hours, and continue to kill 99% of bacteria even after repeated contamination;
  • Help inhibit the buildup and growth of bacteria within two hours of exposure between routine cleaning and sanitizing steps.HP Pavilion DV4-1070ER Battery
  • Testing demonstrates effective antibacterial activity against E. coli O157:H7, methicillin-resistant Staphylococcus aureus(MRSA), Staphylococcus Epidermidis,Enterobacter aerogenes, and Pseudomonas aeruginosa.

Several of the aforementioned bacteria are responsible for a large portion of the nearly two million hospital-acquired infections contracted each year in the United States.HP Pavilion DV4-1070ES Battery

Precautions

Gram quantities of various copper salts have been taken in suicide attempts and produced acute copper toxicity in humans, possibly due to redox cycling and the generation of reactive oxygen species that damage DNA. Corresponding amounts of copper salts (30 mg/kg) are toxic in animals.HP Pavilion DV4-1080EI Battery

A minimum dietary value for healthy growth in rabbits has been reported to be at least 3 ppm in the diet. However, higher concentrations of copper (100 ppm, 200 ppm, or 500 ppm) in the diet of rabbits may favorably influence feed conversion efficiency, growth rates, and carcass dressing percentages.HP Pavilion DV4-1080EO Battery

Chronic copper toxicity does not normally occur in humans because of transport systems that regulate absorption and excretion. Autosomal recessive mutations in copper transport proteins can disable these systems, leading to Wilson's disease with copper accumulation and cirrhosis of the liver in persons who have inherited two defective genes.HP Pavilion DV4-1080ES Battery

Electroplating is a plating process in which metal ions in a solution are moved by an electric field to coat an electrode. The process uses electrical current to reduce cations of a desired material from a solution and coat a conductive object with a thin layer of the material, such as a metal.HP Pavilion DV4-1090EO Battery

Electroplating is primarily used for depositing a layer of material to bestow a desired property (e.g., abrasion and wear resistance, corrosion protection, lubricity, aesthetic qualities, etc.) to a surface that otherwise lacks that property. Another application uses electroplating to build up thickness on undersized parts.HP Pavilion DV4-1090ES Battery

The process used in electroplating is called electrodeposition. It is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In one technique, the anode is made of the metal to be plated on the part. Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ionsthat permit the flow of electricity.HP Pavilion DV4-1100 Battery

A power supply supplies a direct current to the anode, oxidizing the metal atoms that comprise it and allowing them to dissolve in the solution. At the cathode, the dissolved metal ions in the electrolyte solution are reduced at the interface between the solution and the cathode, such that they "plate out" onto the cathode.HP Pavilion DV4-1100EA Battery

The rate at which the anode is dissolved is equal to the rate at which the cathode is plated, vis-a-vis the current flowing through the circuit. In this manner, the ions in the electrolyte bath are continuously replenished by the anode.

Other electroplating processes may use a non-consumable anode such as lead. In these techniques, ions of the metal to be plated must be periodically replenished in the bath as they are drawn out of the solution.HP Pavilion DV4-1101 Battery

The anode and cathode in the electroplating cell are both connected to an external supply of direct current — a battery or, more commonly, a rectifier. The anode is connected to the positive terminal of the supply, and the cathode (article to be plated) is connected to the negative terminal.HP Pavilion DV4-1101TU Battery

When the external power supply is switched on, the metal at the anode is oxidized from the zero valence state to form cations with a positive charge. These cations associate with the anions in the solution. The cations are reduced at the cathode to deposit in the metallic, zero valence state.HP Pavilion DV4-1101TX Battery

For example, in an acid solution, copper is oxidized at the anode to Cu2+ by losing two electrons. The Cu2+ associates with the anion SO42- in the solution to form copper sulfate. At the cathode, the Cu2+ is reduced to metallic copper by gaining two electrons. The result is the effective transfer of copper from the anode source to a plate covering the cathode.HP Pavilion DV4-1102 Battery

The plating is most commonly a single metallic element, not an alloy. However, some alloys can be electrodeposited, notably brassand solder.

Many plating baths include cyanides of other metals (e.g., potassium cyanide) in addition to cyanides of the metal to be deposited.HP Pavilion DV4-1102TU Battery

These free cyanides facilitate anode corrosion, help to maintain a constant metal ion level and contribute to conductivity. Additionally, non-metal chemicals such as carbonates and phosphates may be added to increase conductivity.

When plating is not desired on certain areas of the substrate, stop-offs are applied to prevent the bath from coming in contact with the substrate.HP Pavilion DV4-1102TX Battery

Typical stop-offs include tape, foil, lacquers, and waxes.

Initially, a special plating deposit called a "strike" or "flash" may be used to form a very thin (typically less than 0.1 micrometer thick) plating with high quality and good adherence to the substrate.HP Pavilion DV4-1103TU Battery

This serves as a foundation for subsequent plating processes. A strike uses a high current density and a bath with a low ion concentration. The process is slow, so more efficient plating processes are used once the desired strike thickness is obtained.

The striking method is also used in combination with the plating of different metals.HP Pavilion DV4-1103TX Battery

If it is desirable to plate one type of deposit onto a metal to improve corrosion resistance but this metal has inherently poor adhesion to the substrate, a strike can be first deposited that is compatible with both. One example of this situation is the poor adhesion of electrolytic nickel on zinc alloys, in which case a copper strike is used, which has good adherence to both.HP Pavilion DV4-1104TU Battery

Brush electroplating

A closely related process is brush electroplating, in which localized areas or entire items are plated using a brush saturated with plating solution.HP Pavilion DV4-1104TX Battery

The brush, typically a stainless steel body wrapped with a cloth material that both holds the plating solution and prevents direct contact with the item being plated, is connected to the positive side of a low voltage direct-current power source, and the item to be plated connected to the negative. HP Pavilion DV4-1105EF Battery

The operator dips the brush in plating solution then applies it to the item, moving the brush continually to get an even distribution of the plating material. Brush electroplating has several advantages over tank plating, including portability, ability to plate items that for some reason cannot be tank platedHP Pavilion DV4-1105EM Battery

(one application was the plating of portions of very large decorative support columns in a building restoration), low or no masking requirements, and comparatively low plating solution volume requirements. Disadvantages compared to tank plating can include greater operator involvement (tank plating can frequently be done with minimal attention), and inability to achieve as great a plate thickness.HP Pavilion DV4-1105TU Battery

Electroless deposition

Usually an electrolytic cell (consisting of two electrodes, electrolyte, and external source of current) is used for electrodeposition. In contrast, an electroless deposition process uses only one electrode and no external source of electric current.HP Pavilion DV4-1105TX Battery

However, the solution for the electroless process needs to contain a reducing agent so that the electrode reaction has the form:

In principle any water-based reducer can be used although the redox potential of the reducer half-cell must be high enough to overcome the energy barriers inherent in liquid chemistry.HP Pavilion DV4-1106EE Battery

Electroless nickel plating uses hypophosphite as the reducer while plating of other metals like silver, gold and copper typically use low molecular weight aldehydes.

A major benefit of this approach over electroplating is that power sources and plating baths are not needed, reducing the cost of production.HP Pavilion DV4-1106EM Battery

The technique can also plate diverse shapes and types of surface. The downside is that the plating process is usually slower and cannot create such thick plates of metal. As a consequence of these characteristics, electroless deposition is quite common in the decorative arts.HP Pavilion DV4-1106TX Battery

Cleanliness is essential to successful electroplating, since molecular layers of oil can prevent adhesion of the coating. ASTM B322 is a standard guide for cleaning metals prior to electroplating. Cleaning processes include solvent cleaning, hot alkaline detergent cleaning, electro-cleaning, and acid treatment etc.HP Pavilion DV4-1107TX Battery

The most common industrial test for cleanliness is the waterbreak test, in which the surface is thoroughly rinsed and held vertical. Hydrophobic contaminants such as oils cause the water to bead and break up, allowing the water to drain rapidly. Perfectly clean metal surfaces are hydrophilic and will retain an unbroken sheet of water that does not bead up or drain off.HP Pavilion DV4-1108TX Battery

ASTM F22 describes a version of this test. This test does not detect hydrophilic contaminants, but the electroplating process can displace these easily since the solutions are water-based. Surfactants such as soap reduce the sensitivity of the test and must be thoroughly rinsed off.HP Pavilion DV4-1109TX Battery

Electroplating changes the chemical, physical, and mechanical properties of the workpiece. An example of a chemical change is when nickel plating improves corrosion resistance. An example of a physical change is a change in the outward appearance.HP Pavilion DV4-1110EO Battery

An example of a mechanical change is a change in tensile strength or surfacehardness which is a required attribute in tooling industry.

Although it is not confirmed, the Parthian Battery may have been the first system used for electroplating.HP Pavilion DV4-1110TX Battery

Modern electrochemistry was invented by Italian chemist Luigi V. Brugnatelli in 1805. Brugnatelli used his colleague Alessandro Volta's invention of five years earlier, the voltaic pile, to facilitate the first electrodeposition. Brugnatelli's inventions were suppressed by the French Academy of Sciences and did not become used in general industry for the following thirty years.HP Pavilion DV4-1111TX Battery

By 1839, scientists in Britain and Russia had independently devised metal deposition processes similar to Brugnatelli's for the copper electroplating of printing press plates.

Boris Jacobi in Russia not only rediscovered galvanoplastics, but developed electrotyping andgalvanoplastic sculpture.HP Pavilion DV4-1112TX Battery

Galvanoplactics quickly came into fashion in Russia, with such people as inventor Peter Bagration, scientist Heinrich Lenz and science fiction author Vladimir Odoyevsky all contributing to further development of the technology. Among the most notorious cases of electroplating usage in mid-19th century Russia were gigantic galvanoplastic sculptures of St.HP Pavilion DV4-1113TX Battery

Isaac's Cathedral in Saint Petersburg and gold-electroplated dome of theCathedral of Christ the Saviour in Moscow, the tallest Orthodox church in the world.

Soon after, John Wright of Birmingham, England discovered that potassium cyanide was a suitableelectrolyte for gold and silver electroplating.HP Pavilion DV4-1114NR Battery

Wright's associates, George Elkington and Henry Elkington were awarded the first patents for electroplating in 1840. These two then founded the electroplating industry in Birmingham from where it spread around the world.

The Norddeutsche Affinerie in Hamburg was the first modern electroplating plant starting its production in 1876.HP Pavilion DV4-1114TX Battery

As the science of electrochemistry grew, its relationship to the electroplating process became understood and other types of non-decorative metal electroplating processes were developed. Commercial electroplating of nickel, brass, tin, and zinc were developed by the 1850s.HP Pavilion DV4-1115EF Battery

Electroplating baths and equipment based on the patents of the Elkingtons were scaled up to accommodate the plating of numerous large scale objects and for specific manufacturing and engineering applications.

The plating industry received a big boost from the advent of the development of electric generators in the late 19th century.HP Pavilion DV4-1115TX Battery

With the higher currents, available metal machine components, hardware, and automotive parts requiring corrosion protection and enhanced wear properties, along with better appearance, could be processed in bulk.

The two World Wars and the growing aviation industry gave impetus to further developments and refinements including such processes as hard chromium plating,HP Pavilion DV4-1116TX Battery

bronzealloy plating, sulfamate nickel plating, along with numerous other plating processes. Plating equipment evolved from manually operated tar-lined wooden tanks to automated equipment, capable of processing thousands of kilograms per hour of parts.HP Pavilion DV4-1117CA Battery

One of the American physicist Richard Feynman's first projects was to develop technology for electroplating metal onto plastic. Feynman developed the original idea of his friend into a successful invention, allowing his employer (and friend) to keep commercial promises he had made but could not have fulfilled otherwise.HP Pavilion DV4-1117TX Battery

Use

Electroplating is a useful process process. It is widely used in industry for coating metal objects with a thin layer of a different metal. The layer of metal deposited has some desired property, which metal of the object lacks. For example chromium plating is done on many objects such as car parts, bath taps, kitchen gas burners, wheel rims and many others.HP Pavilion DV4-1118CA Battery

Hull cell

The Hull cell is a type of test cell used to qualitatively check the condition of an electroplating bath. It allows for optimization for current density range, optimization of additive concentration, recognition of impurity effects and indication of macro-throwing power capability.HP Pavilion DV4-1118TX Battery

The Hull cell replicates the plating bath on a lab scale. It is filled with a sample of the plating solution, an appropriate anode which is connected to a rectifier. The "work" is replaced with a hull cell test panel that will be plated to show the "health" of the bath.

The Hull cell is a trapezoidal container that holds 267 ml of solution.HP Pavilion DV4-1119TX Battery

This shape allows one to place the test panel on an angle to the anode. As a result, the deposit is plated at different current densities which can be measured with a hull cell ruler. The solution volume allows for a quantitative optimization of additive concentration: 1 gram addition to 267 mL is equivalent to 0.5 oz/gal in the plating tank.HP Pavilion DV4-1120BR Battery

Erosion corrosion, also known as impingement damage, is the combined effect of corrosion and erosion caused by rapid flowing turbulent water. It is probably the second most common cause of copper tube failures behind Type 1 pitting which is also known as Cold Water Pitting of Copper Tube.HP Pavilion DV4-1120TX Battery

Copper water tubes

Copper tubes have been used to distribute drinking water within buildings for many years, and hundreds of miles are installed throughout Europe every year. The long life of copper when exposed to natural waters is a result of its thermodynamic stability,HP Pavilion DV4-1120US Battery

its high resistance to reacting with the environment, and the formation of insoluble corrosion products that insulate the metal from the environment. The corrosion rate of copper in most drinkable waters is less than 2.5 µm/year, at this rate a 15 mm tube with a wall thickness of 0.7 mm would last for about 280 years.HP Pavilion DV4-1121BR Battery

In some soft waters the general corrosion rate may increase to 12.5 µm/year, but even at this rate it would take over 50 years to perforate the same tube.

Occurrence

If the general water speed or the degree of local turbulence in an installation is high, the protective film that would normally be formed on a copper tube as a result of slight initial corrosion, may be torn off the surface locally,HP Pavilion DV4-1121CA Battery

permitting further corrosion to take place at that point. If this process continues it can produce deep localised attack of the type known as erosion-corrosion or impingement damage. The actual attack on the metal is by the corrosive action of the water to which it is exposed while the erosive factor is the mechanical removal of the corrosion product from the surface.HP Pavilion DV4-1121TX Battery

Impingement attack produces highly characteristic water-swept pits, which are often horseshoe shaped, or it can produce broader areas of attack. The leading edge of the pit is frequently undercut by the swirling action of the water. Usually, the surface of the metal within the pits or areas of attack is smooth and carries no substantial corrosion product.HP Pavilion DV4-1122TX Battery

Erosion-corrosion is known to occur in pumped-circulation hot water distribution systems, and even in cold water distribution systems, if the water velocities are too high. The factors influencing the attack include the chemical character of the water passing through the system,HP Pavilion DV4-1123LA Battery

the temperature, the average water velocity in the system and the presence of any local features likely to induce turbulence in the water stream.

It is unusual for the general water velocity in a system to be so high that impingement attack occurs throughout the whole of the copper pipework.HP Pavilion DV4-1123TX Battery

More commonly, the velocity is just sufficiently low for satisfactory protective films to be formed and to remain in position on most of the system, with impingement damage more likely to occur where there is an abrupt change in the direction of water flow giving rise to a high degree of turbulence, such as at tee pieces and elbow fittings.HP Pavilion DV4-1123US Battery

It is not generally realised how great an effect small obstructions can have on the flow pattern of water in a pipe-work system and the extent to which they can induce turbulence and cause corrosion-erosion. For example, it is most important, as far as possible, to ensure that copper tubes cut with a tube cutter are deburred before making the joint.HP Pavilion DV4-1124LA Battery

Also a gap between the tube end and the stop in the fitting, due to the tube not having been cut to the correct length and fully inserted into the socket of the fitting, can also induce turbulence in the water stream.

Recommendations

The rate of impingement attack on copper also depends to some extent on the temperature of the water.HP Pavilion DV4-1124NR Battery

The maximum velocities for fresh waters at different temperatures recommended in Sweden are given in the table below. These figures are for aerated waters of pH not less than about 7.

Recommended Maximum Water Velocities at Different Temperatures for Copper (m/s)HP Pavilion DV4-1124TX Battery

§ These velocities give a risk of impingement attack and are acceptable only for small bore connections to taps, flushing cisterns etc., through which water flow is intermittent.

BS 6700 gives the following maximum water velocities although it does note that these are currently under investigation and the velocities specified will be amended if the results of this investigation so require.HP Pavilion DV4-1125BR Battery

The minimum water speed at which copper pipes suffer impingement attack depends also to some extent on water composition. Aggressive waters that tend to be cupro-solvent are the most likely to give rise to impingement attack. Installations in large buildings where flow rates may be high and water is in continuous circulation are much more susceptible to attack than ordinary domestic installations.HP Pavilion DV4-1125LA Battery

A high mineral content or a pH below 7 is likely to increase the possibility of corrosion-erosion occurring while a positive Langelier Index and consequent tendency to deposit a calcium carbonate scale is generally beneficial. The presence or absence of colloidal organic matter is also probably of some importance.HP Pavilion DV4-1125NR Battery

Remedial measures for impingement attack include modifications to the system to reduce the average water velocity, e.g. by using larger diameter tubes or, if appropriate, to lower the pump speed, and/or to redesign the part of the installation concerned to eliminate the cause of local turbulence, e.g. by using slow or swept bends and tee fittings rather than elbows and square tees.HP Pavilion DV4-1125TX Battery

It is important to minimise the possibility of any local turbulence occurring by ensuring that the ends of tubes cut with a tube cutter are deburred and that the tubes are inserted fully to the stops in the fitting before the joints are made, as referred to earlier in this section.HP Pavilion DV4-1126LA Battery

In some cases, where the above approaches are not possible, the length of copper tube affected can sometimes be replaced by materials more resistant to corrosion-erosion, e.g. 90/10 copper-nickel (BS Designation CN102) using appropriate fittings, or stainless steel to BS 4127:1994.HP Pavilion DV4-1126TX Battery

Cold water pitting of copper tube occurs in only a minority of installations. Copper water tubes are usually guaranteed by the manufacturer against manufacturing defects for a period of 50 years. The vast majority of copper systems far exceed this time period but a small minority may fail after a comparatively short time.HP Pavilion DV4-1127LA Battery

The majority of failures seen are the result of poor installation or operation of the water system. The most common failure seen in the last 20 years is pitting corrosion in cold water tubes, also known as Type 1 pitting. These failures are usually the result of poor commissioning practice although a significant number are initiated by flux left in the bore after assembly of soldered joints.HP Pavilion DV4-1127TX Battery

Prior to about 1970 the most common cause of Type 1 pitting was carbon films left in the bore by the manufacturing process.

Research and manufacturing improvements in the 1960s virtually eliminated carbon as a cause of pitting with the introduction of a clause in the 1971 edition of BS 2871 requiring tube bores to be free of deleterious films.HP Pavilion DV4-1128TX Battery

Despite this, carbon is still regularly blamed for tube failures without proper investigation.

Copper water tubes

Copper tubes have been used to distribute potable water within building for many years and hundreds of miles are installed throughout Europe every year.HP Pavilion DV4-1129LA Battery

The long life of copper when exposed to natural waters is a result of its thermodynamic stability, its high resistance to reacting with the environment, and the formation of insoluble corrosion products that insulate the metal from the environment.HP Pavilion DV4-1129TX Battery

The corrosion rate of copper in most potable waters is less than 25 µm/year, at this rate a 15 mm tube with a wall thickness of 0.7 mm would last for about 280 years. In some soft waters the general corrosion rate may increase to 125 µm/year, but even at this rate it would take over 50 years to perforate the same tube.HP Pavilion DV4-1130BR Battery

Despite the reliability of copper and copper alloys, in some cold hard waters pits may form in the bore of a tube. If these pits form, failure times can be expected between 6 months and 2 years from initiation. The mechanism that leads to the pitting of copper in cold hard waters is complex,HP Pavilion DV4-1130TX Battery

it requires a water with a specific chemistry that is capable of supporting pit growth and a mechanism for the initiation of the pits.

The pits that penetrate the bore are usually covered in a hard pale green nodule of copper sulfate and copper hydroxide salts.HP Pavilion DV4-1131BR Battery

If the nodule is removed a hemispherical pit is revealed filled with coarse crystals of red cuprous oxide and green cuprous chloride. The pits are often referred to as Type 1 pits and the form of attack as Type 1 pitting.

The characteristics capable of supporting Type 1 pits were determined empirically by Lucey after examining the compositions of waters in which the pitting behaviour was known.HP Pavilion DV4-1131TX Battery

They should be cold, less than 30°C, hard or moderately hard, 170 to 300 mg/l carbonate hardness, and organically pure. Organically pure waters usually originate from deep wells, or boreholes. Surface waters from rivers or lakes contain naturally occurring organic compounds that inhibit the formation of Type 1 pits,HP Pavilion DV4-1132TX Battery

unless a deflocculation treatment has been carried out that removes organic material. Type 1 pitting is relatively uncommon in North America and this may be a result of the lower population density allowing a significant proportion of the potable water to be obtained from surface derived sources.HP Pavilion DV4-1133TX Battery

In addition to being cold hard and organically pure, the water needs a specific chemistry. The effect of the water chemistry can be empirically determined though use of the Pitting Propensity Rating (PPR) a number that takes into account the sulfate, chloride, nitrate and sodium ion concentrations of the water as well as its acidity or pH.HP Pavilion DV4-1134TX Battery

A water with a positive PPR has been shown to be capable of propagating Type 1 pits.

Initiation

Many waters in both the UK and Europe are capable of supporting Type 1 pitting but no problems will be experienced unless a pit is initiated in the wall of the tube.HP Pavilion DV4-1135BR Battery

When a copper tube is initially filled with a hard water salts deposit on the wall and the copper slowly reacts with the water producing a thin protective layer of mixed corrosion products and hardness scale. If any pitting of the tube is to occur then this film must be locally disrupted. There are three mechanisms that allow the disruption of the protective deposits.HP Pavilion DV4-1135EE Battery

The most well known, although now the least common, is the presence of carbon films on the bore. Stagnation and flux residues are the most common initiation mechanisms that have led to Type 1 pitting failures in the last ten years.

Carbon rilms

Copper tubes are made from the large billets of copper that are gradually worked and drawn down to the required size.HP Pavilion DV4-1135EI Battery

As the tubes are drawn they are heat treated to produce the correct mechanical properties. The organic oils and greases used to lubricate the tubes during the drawing processes are broken down during the heat treatment and gradually coat the tube with a film of carbon.HP Pavilion DV4-1135TX Battery

If the carbon is left in the bore of the tube then it disrupts the formation of the protective scale and allows the initiation of pits in the wall. The presence of deleterious films, such as carbon, has been prohibited by the British Standards in copper tubes since 1969.HP Pavilion DV4-1136BR Battery

All copper tubes for water service are treated, usually by grit blasting or acid pickling, to remove any films produced during manufacture with the result that Type 1 pitting initiated by carbon films is now very rare.

Stagnation

If water is left to stand in a tube for an extended period, the chemical characteristics of the water change as the mixed scale and corrosion products are deposited.HP Pavilion DV4-1136TX Battery

In addition any loose scale that is not well adhered to the wall will not be flushed away and air dissolved in the water will form bubbles, producing air pockets. These processes can lead to a number of problems mainly on horizontal tube runs. Particles of scale that do not adhere to the walls and are not washed away tend to fall into the bottom of the tube producing a coarse porous deposit.HP Pavilion DV4-1137TX Battery

Air pockets that develop in horizontal runs disrupt the formation of protective scales in two areas. The water lines at the sides and the air space at the top of the tube.

In each of the areas that the scale has been disrupted there is the possibility of the initiation of Type 1 pitting. Once pitting has initiated,HP Pavilion DV4-1138TX Battery

then even after the tube has been put back into service, the pit will continue to develop until the wall has perforated. This form of attack is often associated with the commissioning of a system. Once a system has been commissioned it should be either put immediately into service or drained down and dried by flushing with compressed air otherwise pitting may initiate.HP Pavilion DV4-1139TX Battery

If either of these options is not possible then the system should be flushed though regularly until it is put into use.

Flux

In plumbing systems fluxes are used to keep the mating surfaces clean during soldering operations. The fluxes often consist of corrosive chemicals such as ammonium chloride and zinc chloride in a binder such as petroleum jelly.HP Pavilion DV4-1140EK Battery

If too much flux is applied to the joint then the excess will melt and run down the bore of a vertical tube or pool in the bottom of a horizontal tube. Where the bore of the tube is covered in a layer of flux it may be locally protected from corrosion but at the edges of the flux pits often initiate.HP Pavilion DV4-1140GO Battery

If the tube is put into service in a water that supports Type 1 pitting then these pits will develop and eventually perforate the sides of the tube.

Recommendations

In most cases Type 1 pitting can be avoided by good working practices. Always use tubes that have been manufactured to BS EN 1057.HP Pavilion DV4-1140TX Battery

Tubes greater than 10 mm indiameter made to this standard will always be marked the number of the standard, the nominal size, wall thickness and temper of the tube, the manufacturer’s identification mark and the date of production at least every 600 mm. Tubes less than 10 mm in diameter will be similarly marked at each end.HP Pavilion DV4-1141TX Battery

Once a system has been commissioned it should be either put immediately into service or drained down and dried. If either of these options is not possible then the system should be flushed though regularly until it is put into use. It should not be left to stand for more than a week. At present stagnation is the most common cause of Type 1 pitting.HP Pavilion DV4-1142TX Battery

Flux should be used sparingly. A small quantity should be painted over the areas to be joined and any excess removed after the joint has been made. Some fluxes are marked as water-soluble but under some circumstances they are not removed before pitting has initiated.HP Pavilion DV4-1143GO Battery

Metal theft is the theft of metal items on a very large scale. These thefts usually increase when worldwide prices for scrap metal rise. In recent years, prices for metals have risen dramatically due to rapid industrialization in India and China. The metals most commonly stolen are copper, aluminium, brass, and bronze.HP Pavilion DV4-1143TX Battery

Other researchers have defined metal theft more specifically as "the theft of items for the value of their constituent metals." The defining characteristic of metal theft (besides being limited to items containing or made entirely from metal) is the motivation for the theft.HP Pavilion DV4-1144TX Battery

Whereas items are generally stolen for theirintrinsic value (e.g., stealing an iPod for its value as an iPod), items stolen in metal theft are stolen for their more or less extrinsic value as raw material or commodities. Items stolen in metal theft are ultimately scrapped, or recycled, to provide material for making new products.HP Pavilion DV4-1144US Battery

Motivations for theft

Scrap metal has drastically increased in price over recent years. In 2001, it sold for $77 a ton, increasing to $300/ton by 2004. In 2008, it hit nearly $500/ton. Some elected officials and law enforcement officials have concluded that many metal thefts are by drug addicts stealing metal in order to fund their addictions.HP Pavilion DV4-1145BR Battery

Some officials believe that most of these drug-related metal thefts are caused by methamphetamine users, however, this varies by the location the metal is being stolen. Regardless of the reason, developing nations such as China, India, and South Korea are ever-fueling the demand for it.HP Pavilion DV4-1145GO Battery

In the fourth quarter of 2008, however, world market prices for metals like copper, aluminium, and platinum dropped steeply. Although there is anecdotal evidence that this price decrease has led to fewer metal thefts, strong empirical research on the exact nature of relationship between commodity prices and metal thefts is still lacking.HP Pavilion DV4-1145TX Battery

Some have argued that the "genie is out of the bottle" now and drops in commodity prices will not result in corresponding drops in thefts. In fact, it is possible that thefts may actually increase to compensate for the loss in value.

Metal theft in South Africa is rampant, with an estimated of R5 billion per annum lost due to the theft.HP Pavilion DV4-1146TX Battery

The stolen metal ranges from copper cables, piping, bolts to manhole covers. The theft continuously disrupts and degrades services, such as the power supply provided by Eskom and the telecommunication services by Telkom. Eskom estimated that the theft has costed the company about R25 million per annum,HP Pavilion DV4-1147CL Battery

with incidents increasing from 446 incidents in 2005; 1,059 in 2007 and 1,914 in 2008. The theft has cost Telkom R863 million (April 2007 - January 2008 period). Despite the minimal copper reserve South Africa has, as much as 3000 tonnes of copper leave Cape Town harbour every month.HP Pavilion DV4-1147TX Battery

Aside from the economic impact, the theft also

The Non-Ferrous Crime Combatting Committee (NFCCC) has been formed specifically to combat this type of crime in the country.HP Pavilion DV4-1148TX Battery

In Australia, copper wiring, believed to be stolen from a variety of locations including rail tracks, power stations and scrap metal depots, was destined for the Asian black market.

From July to September 2005, a gang of thieves in Brunei dismantled and stole parts from more than 60 power substations in that country, including copper earthing cables and aluminum doors. It is apparently being sold as scrap metal.HP Pavilion DV4-1149TX Battery

The thefts are ongoing.In Quebec, during May 2006, thieves stole sections of copper roofing, gutters and wiring from four Quebec city churches, two being St. Charles de Limoilou and St. Francois d'Assise. The thieves were discovered in action on their third night, whereupon they fled.HP Pavilion DV4-1150BR Battery

High copper prices are believed to be the reason for the thefts. Repairs were expected to cost more than $40,000.[13]

In October 2010, a 400 pound bronze bell was stolen in Shelburne County, Nova Scotia. Thieves removed the bell from a monument in Roseway Cemetery.HP Pavilion DV4-1150EO Battery

The bell was part of the Roseway United Memorial Church, built in 1912, until it was demolished in 1993. It was recovered in a Halifax-area scrapyard October 6.

327 bronze markers stolen from Theresienstadt concentration camp cemetery in mid-April 2008, with 700 more stolen the next week.HP Pavilion DV4-1150EP Battery

A scrap metal dealer was arrested on April 18, 2008. He intended to melt them down for their copper.

In February 2006, near the German city of Weimar, thieves dismantled and carted away some 5 kilometres (3 mi) of disused rail track, causing at least 200,000 euros worth of damage.HP Pavilion DV4-1150ER Battery

In Haiti, after the 2010 Haiti earthquake, some looters were reported to be removing rebar from the concrete of collapsed buildings in order to sell it. Others hacked up downed power lines.

In Japan, there were 5,700 metal theft reported cases in 2007 in locations as far apart as Shizuoka, Hiroshima and Okinawa.HP Pavilion DV4-1150ES Battery

On the 11th of January, 2011 an ICE train derailed near the Dutch city of Zevenaar. The cause of the accident was the theft of 300 meters of copper cable. Nobody was harmed.

In 2001, thieves in Khabarovsk Krai stole electric and telephone lines leading to military bases there.[23] A small bridge was stolen in Russia in 2007, when a man chopped up its 5-meter span and hauled it away.HP Pavilion DV4-1150TX Battery

In Ukraine, statues, wires, sewage hatches, and even a museum-exhibit steam locomotive have been stolen for sale as scrap. In February 2004, thieves in western Ukraine dismantled and stole an 11 m long, one-tonne steel bridge that spanned the river Svalyavka.HP Pavilion DV4-1151TX Battery

In September 2009, smugglers attempted to make off with 25 tons of radioactive scrap metal from the Chernobyl Exclusion Zone. The Security Service of Ukraine caught them.

Significant rises in metal theft were observed during 2006-2007 in the UK,especially in North West England, where metal theft is still on the rise as of 2008.HP Pavilion DV4-1152TX Battery

Police Review have said that metal theft is now the fastest growing crime in the UK (for 2008) with the annual damage to industry estimated at £360m.

In the UK, the British Metals Recycling Association is working with authorities such as the Association of Chief Police Officers and the British Transport Police to halt the problem of metal being stolen from its members' sites and to identify stolen materials.HP Pavilion DV4-1153TX Battery

Roofs, manhole covers, statues etc. have all been increasingly targeted recently due to the rising cost of metal. Most of the time metal is sold for scrap but occasionally used by the thieves themselves. There have been many stories of metal theft;HP Pavilion DV4-1154TX Battery

a bronze statue of former Olympic champion Steve Ovett disappeared fromPreston Park in Brighton and church bells in Devon were stolen by thieves. A statue made by Henry Moore was stolen from a museum in 2006 and believed to have been melted down for scrap.HP Pavilion DV4-1155SE Battery

Churches, especially older churches, suffer as 'lead theft' from church (and other) roofs is on the rise, although some police do not take it seriously. In late 2011 the police began a number of crackdowns on metal theft, the largest in South Yorkshire resulting in at least 22 arrests and the seizure of amateur smelting equipment.HP Pavilion DV4-1155TX Battery

Cities across the United States have become targets for metal thieves. Manhole cover thefts have increased dramatically between 2007 and 2008, with Philadelphia as one of the hardest hit targets. Other cities dealing with this trend include Chicago, Greensboro, NC, and Long Beach, CA.HP Pavilion DV4-1156TX Battery

Copper wire thefts are also becoming increasingly common in the U.S. With copper prices at $3.70 a pound as of June 2007, compared to $0.60 a pound in 2002, people are increasingly stealing copper wire from telephone and power company assets.HP Pavilion DV4-1157TX Battery

Gangs have been created, a black market for copper wire has emerged, and men even have been killed in power plants while trying to obtain copper wire. Other sources of stolen copper include railroad signal lines, grounding bars at electric substations, and even a 3000 pound bell stolen from a Buddhist temple in Tacoma, Washington, which was later recovered.HP Pavilion DV4-1158TX Battery

For example, Georgia, like many other states, has seen enough copper crime that a special task force has been created to fight it. The Metro Atlanta Copper Task Force is led by the Atlanta Police Department and involves police and recyclers from surrounding metro areas, Georgia Power, and the Fulton County DA’s office.HP Pavilion DV4-1159TX Battery

Many states around the nation have passed – or are exploring – legislation to combat the problem. A new Georgia law took effect in July 2007 making it a crime to knowingly buy stolen metal. It allows prosecutors to prosecute for the actual cost of returning property to original conditions, as many of these thefts dramatically hurt the surrounding property value.HP Pavilion DV4-1160ES Battery

All in all, there is a nationwide movement towards education and cooperation between local prosecutors, police departments, and scrap metal dealers about problems of and solutions for metal theft.

In response to the growing concerns and the lack of hard numbers on these crimes in Indianapolis,HP Pavilion DV4-1160TX Battery

IN, the Indianapolis Metropolitan Police Department (IMPD) and the University of Indianapolis Community Research Center (CRC) began in 2008 a collaborative effort to collect data on metal thefts. The Indianapolis Metal Theft Project gathers and analyzes a wide variety of data to provide a clearer understanding of the incidence,HP Pavilion DV4-1161TX Battery

types, costs, and impacts of metal theft in Indianapolis in order to inform and implement strategies to reduce these crimes and their impacts.

The Department of Justice's Office of Community-Oriented Policing and the Center for Problem-Oriented Policing published its 58th problem-solving guide in 2010 directed towards Theft of Scrap Metal.HP Pavilion DV4-1162TX Battery

The author of the guide, Brandon Kooi, Ph.D., provides a review of the problem in the U.S. and internationally, followed by a number of suggested responses and what to consider in those responses.

The International Association of Property Crime Investigators presents the annual National Metal Theft Investigation Seminar uniting law enforcement and corporate security to share, learn and network to combat metal theft.HP Pavilion DV4-1163TX Battery

The Institute of Scrap Recycling Industries is one of the groups backing these educational efforts throughout the country. As the nation’s trade association for the scrap recycling industry, ISRI provides members and community leaders with resources that they can use when facing the issue.HP Pavilion DV4-1164TX Battery

They have also teamed with theNational Crime Prevention Council (known for McGruff the Crime Dog and the “Take a Bite Out of Crime” slogan) in an effort to team with law enforcement and crime prevention organizations to fight and solve this problem, and have established a theft alert system that these groups can use.HP Pavilion DV4-1165TX Battery

ISRI and the National Crime Prevention Council offer a number of tips for how to fight and prevent metal theft, including requiring photo ID and license plate information for every transaction, training employees on identifying stolen goods, and keeping good records that might be useful later.HP Pavilion DV4-1166CA Battery

In 2011, Officer Mandy Curfiss, a police officer on the reality television series Police Women of Cincinnati stated that theft of copper items for their copper content was common in Cincinnati.

Operation Tremor is a joint operation between British Transport Police,HP Pavilion DV4-1166TX Battery

Lancashire Constabulary and Network Rail to combat thieves who have been stealing copper boilers and piping and taking copper cables from train tracks, which can disable signalling equipment and safety devices. Some of the wire is used to carry information for automatic signalling and safety equipment .HP Pavilion DV4-1167TX Battery

The police circulated pictures of known thieves to scrap metal merchants and taxi drivers after a dramatic rise in thefts from railway property and homes. Part of the blame was put on the rise in price of copper which had tripled in the three years leading to 2006.

Equipment used in targeting offenders included CCTV and Automatic Number Plate Recognition (ANPR).HP Pavilion DV4-1168TX Battery

The operation launched in December 2006 highlights a growing problem which is affecting the whole national rail network.

Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore. This includes iron extraction fromiron ore, and copper extraction and other base metals from their ores.HP Pavilion DV4-1169TX Battery

Smelting uses heat and a chemical reducing agent to change the oxidation state of the metal ore; the reducing agent is commonly a source of carbon such as coke, or in earlier timescharcoal. The carbon or carbon monoxide derived from it removes oxygen from the ore to leave the metal.HP Pavilion DV4-1180BR Battery

The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide. As most ores are impure, it is often necessary to use flux, such as limestone, to remove the accompanying rock gangue as slag.

Plants for the electrolytic reduction of aluminium are also generally referred to as smelters. HP Pavilion DV4-1190BR Battery

These do not melt aluminum oxide but instead dissolve it in aluminum fluoride. They normally use carbon electrodes, and conversion of carbon to carbon dioxide provides an important part of deoxydation energy, rest of energy being provided by electricity, but novel smelter designs use electrodes that are not consumed in the process. The end product is molten aluminum.HP Pavilion DV4-1190EA Battery,HP Pavilion DV4-1190EJ Battery,HP Pavilion DV4-1190EL Battery,HP Pavilion DV4-1198ER Battery

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Wrought iron is an iron alloy with a very low carbon content, in comparison to steel, and has fibrous inclusions, known asslag. This is what gives it a "grain" resembling wood, which is visible when it is etched or bent to the point of failure. Wrought iron is tough, malleable, ductile and easily welded.HP Pavilion DV4-1199EA Battery

Historically, it was known as "commercially pure iron"; however, it no longer qualifies because current standards for commercially pure iron require a carbon content of less than 0.008 wt%.

Before the development of effective methods of steelmaking and the availability of large quantities of steel, wrought iron was the most common form of malleable iron.HP Pavilion DV4-1199EE Battery

A modest amount of wrought iron was used as a raw material for manufacturing of steel, which was mainly to produce swords, cutlery, chisels, axes and other edge tools as well as springs and files. Demand for wrought iron reached its peak in the 1860s with the adaptation of ironclad warships and railways, but then declined asmild steel became more available.HP Pavilion DV4-1199EF Battery

Before they came to be made of mild steel, items produced from wrought iron included rivets, nails, wire, chains, railway couplings, water and steam pipes, nuts, bolts, horseshoes, handrails, straps for timber roof trusses, and ornamental ironwork.[5]

Wrought iron is no longer produced on a commercial scale.HP Pavilion DV4-1199EO Battery

Many products described as wrought iron, such as guard rails,garden furniture[6] and gates, are made of mild steel.[7] They retain that description because they are wrought (worked) by hand.

Terminology

The word "wrought" is an archaic past tense form of the verb "to work," and so "wrought iron" literally means "worked iron".HP Pavilion DV4-1199EP Battery

Wrought iron is a general term for the commodity, but is also used more specifically for finished iron goods, as manufactured by a blacksmith or other smith. It was used in this narrower sense in British Customs records, such manufactured iron being subject to a higher rate of duty than what might be called "unwrought" iron.HP Pavilion DV4-1199ER Battery

Cast iron, unlike wrought iron, is brittle and cannot be worked either hot or cold. Cast iron can break if struck with a hammer.

In the 17th, 18th and 19th centuries, wrought iron went by a wide variety of terms according to its form, origin, or quality.HP Pavilion DV4-1199ES Battery

While the bloomery process produced wrought iron directly from ore, cast iron or pig iron were the starting materials used in thefinery forge and puddling furnace. Pig iron and cast iron have high carbon content which make them very brittle, but they have a lower melting point than iron or steel.HP Pavilion DV4-1199ET Battery

Cast and especially pig iron have excess slag which must be at least partially removed to produce quality wrought iron.

For several years after the introduction of Bessemer and open hearth steel there were different opinions as to what differentiated iron from steel, some thinking it was the chemical composition and others believing it was whether the iron heated sufficiently to melt and "fuse".HP Pavilion DV4-1200 CTO Battery

Fusion eventually became generally accepted as relatively more important than composition below a given low carbon concentration.[9] Another difference is that steel can be hardened by heat treating.

Form or shapes

  • Bar iron—iron in bars, which are the usual product of the finery forge, but not necessarily made by that process. These might be square or flat, and flat bars might be narrow or broad.HP Pavilion DV4-1200 Battery
  • Rod iron—cut from flat bar iron in a slitting mill to provide the raw material for nails.
  • Hoop iron—suitable for the hoops of barrels, made by passing rod iron through flat rolls.
  • Plate iron—sheets of iron suitable for use as boiler plate.HP Pavilion DV4-1201AU Battery
  • Blackplate—sheets of iron, perhaps thinner than plate iron, from the black rolling stage of tinplate production.
  • Voyage iron—narrow flat bar iron, made or cut into bars of a particular weight, a commodity for sale in Africa for the Atlantic slave trade.HP Pavilion DV4-1201TU Battery
  • The number of bars per ton gradually increased from 70 per ton in the 1660s to 75–80 per ton in 1685 and "near 92 to the ton" in 1731.
  • Charcoal Iron — Until the end of the eighteenth century, wrought iron was smelted from ore using charcoal, by the bloomery process.HP Pavilion DV4-1201TX Battery
  • Wrought iron was also produced from pig iron using a finery forge or from the industrial revolution in a Lancashire hearth. The resulting metal was highly variable, both in chemistry and slag content.
  • Puddled Iron — By the late eighteenth century there was a demand from pig iron, an impure form of cast iron, to be refined with coal as fuel.HP Pavilion DV4-1202AU Battery
  • This resulted in ‘puddled iron’, which contained less slag, sulfur and had a very low carbon content. The iron was kept separate from the fire in a reverberatory furnace to prevent harmful sulphur and phosphorus from entering the finished iron.HP Pavilion DV4-1202TU Battery
  • Puddled iron, although also variable in its properties, was generally more consistent than the earlier irons, and the method lent itself to the production of far greater quantities. By 1876, annual production of puddled iron in the UK alone was over 4 million tons.HP Pavilion DV4-1202TX Battery
  • Oregrounds iron—a particularly pure grade of bar iron made ultimately from iron ore from the Dannemora mine in Sweden. Its most important use was as the raw material for the cementation process of steelmaking.
  • Danks iron — originally iron imported to Great Britain from Gda?sk, but in the 18th century more probably the kind of iron (from eastern Sweden) that once came from Gda?sk.HP Pavilion DV4-1203AU Battery
  • Forest iron — iron from the English Forest of Dean, where haematite ore enabled tough iron to be produced.
  • Lukes iron — iron imported from Liège, whose Dutch name is "Luik."
  • Ames iron or amys iron — another variety of iron imported to England from northern Europe.HP Pavilion DV4-1203TU Battery
  • Its origin has been suggested to be Amiens, but it seems to have been imported from Flanders in the 15th century and Holland later, suggesting an origin in the Rhine valley. Its origins remain controversial.
  • Botolf iron or Boutall iron — from Bytów (Polish Pomerania) or Bytom (Polish Silesia).HP Pavilion DV4-1203TX Battery
  • Sable iron (or Old Sable) — iron bearing the mark (a sable) of the Demidov family of Russian ironmasters, one of the better brands of Russian iron.

Tough iron

Tough iron, also spelled "tuf", is not brittle and strong enough to be used for tools.

Blend iron

Blend iron is made using a mixture of different types of pig iron.HP Pavilion DV4-1204AU Battery

Best iron

Best iron is iron that had gone through several stages of piling and rolling, might reach the stage of being best iron (in the 19th century).

Marked bar iron

This is iron made by members of the Marked Bar Association and marked with the maker's brand mark as a sign of its quality.HP Pavilion DV4-1204TU Battery

Defects

Wrought iron is redshort if it contains sulfur in excess quantity. It has sufficient tenacity when cold, but cracks when bent or finished at a red heat. It is therefore useless for welding or forging.

Coldshort iron, also known as coldshear, colshire or bloodshot, contains excessive phosphorus.HP Pavilion DV4-1204TX Battery

It is very brittle when it is cold. It cracks if bent. It may, however, be worked at high temperature. Historically, coldshort iron was considered good enough for nails.

Nevertheless, phosphorus is not necessarily detrimental to iron. Ancient Indian smiths did not add lime to their furnaces;HP Pavilion DV4-1205AU Battery

the absence of CaO in the slag, and the deliberate use of wood with high phosphorus content during the smelting, induces a higher P content (> 0.1%, average 0.25%) than in modern iron. Analysis of the Iron Pillar of Delhi gives 0.10% in the slags for .18% in the iron itself, for a total P content of 0.28% in the metal and accounts for much of its corrosion resistance.HP Pavilion DV4-1205TU Battery

Furthermore, the presence of phosphorus (without carbon) produces a ductile iron suitable for wire drawing, for piano wire.

Wrought iron has been used for many centuries, and is the "iron" that is referred to throughout western history. The other form of iron, cast iron, was not introduced into Western Europe until the 15th century;HP Pavilion DV4-1205TX Battery

even then, due to its brittleness, it could only be used for a limited number of purposes. Throughout much of the Middle Ages iron was produced by the direct reduction of ore in manually operated bloomeries, although waterpower had begun to be employed by 1104.HP Pavilion DV4-1206TU Battery

The raw material produced by all indirect processes is pig iron. It has a high carbon content and as a consequence it is brittle and could not be used to make hardware. The osmond process was the first of the indirect processes, developed by 1203, but bloomery production continued in many places.HP Pavilion DV4-1206TX Battery

The process depended on the development of the blast furnace, of which medieval examples have been discovered at Lapphyttan, Sweden and in Germany.

The bloomery and osmond processes were gradually replaced from the 15th century by finery processes, of which there were two versions, the German and Walloon.HP Pavilion DV4-1207TU Battery

They were in turn replaced from the late 18th century by puddling, with certain variants such as the Swedish Lancashire process. These too are now obsolete, and wrought iron is no longer manufactured commercially.

Bloomery process

Wrought iron was originally produced by a variety of smelting processes, all described today as bloomeries. HP Pavilion DV4-1207TX Battery

Different forms of bloomery were used at different places and times. The bloomery was charged with charcoal and iron ore and then lit. Air was blown in through a tuyere to heat the bloomery to a temperature somewhat below the melting point of iron.HP Pavilion DV4-1208TU Battery

In the course of the smelt, slag would melt and run out, and carbon monoxide from the charcoal would reduce the ore to iron, which formed a spongy mass. The iron remained in the solid state. If the bloomery was allowed to become hot enough to melt the iron, carbon would dissolve into it and form pig or cast iron, but that was not the intention.HP Pavilion DV4-1208TX Battery

After smelting was complete, the bloom was removed, and the process could then be started again. It was thus a batch process, rather than a continuous one. The spongy mass contained iron and also silicate (slag) from the ore; this was iron bloom from which the technique got its name.HP Pavilion DV4-1209TU Battery

The bloom had to be forged mechanically to consolidate it and shape it into a bar, expelling slag in the process.

During the Middle Ages, water-power was applied to the process, probably initially for powering bellows, and only later to hammers for forging the blooms.HP Pavilion DV4-1209TX Battery

However, while it is certain that water-power was used, the details of this remain uncertain. This was the culmination of the direct process of ironmaking. It survived in Spain and southern France as Catalan Forges to the mid 19th century, in Austria as the stuckofento 1775, and near Garstang in England until about 1770;HP Pavilion DV4-1210EA Battery

it was still in use with hot blast in New York State in the 1880s.

Osmond process

Osmond iron consisted of balls of wrought iron, produced by melting pig iron and catching the droplets on a staff, which was spun in front of a blast of air so as to expose as much of it as possible to the air and oxidise its carbon content.HP Pavilion DV4-1210EF Battery

The resultant ball was often forged into bar iron in a hammer mill.

Finery process

In the 15th century, the blast furnace spread into what is now Belgium and was improved. From there, it spread via the Pays de Bray on the boundary of Normandy and then to the Weald in England.HP Pavilion DV4-1210EO Battery

With it, the finery forge spread. These remelted the pig iron and (in effect) burnt out the carbon, producing a bloom, which was then forged into a bar iron. If rod iron was required, a slitting mill was used.

The finery process existed in two slightly different forms. In Great Britain, France, and parts of Sweden, only the Walloon process was used.HP Pavilion DV4-1210ER Battery

This employed two different hearths, a finery hearth for fining the iron and a chafery hearth for reheating it in the course of drawing the bloom out into a bar. The finery always burnt charcoal, but the chafery could be fired with mineral coal, since its impurities would not harm the iron when it was in the solid state.HP Pavilion DV4-1210TU Battery

On the other hand, the German process, used in Germany, Russia, and most of Sweden used a single hearth for all stages.

The introduction of coke for use in the blast furnace by Abraham Darby in 1709 (or perhaps others a little earlier) initially had little effect on wrought iron production.HP Pavilion DV4-1210TX Battery

Only in the 1750s was coke pig iron used on any significant scale as the feedstock of finery forges. However, charcoal continued to be the fuel for the finery.

Potting and stamping

From the late 1750s, ironmasters began to develop processes for making bar iron without charcoal. There were a number of patented processes for this, which are referred to today as potting and stamping.HP Pavilion DV4-1211EA Battery

The earliest were developed by John Wood of Wednesbury and his brother Charles Wood of Low Mill at Egremont, patented in 1763.Another was developed for the Coalbrookdale Company by the Cranage brothers.[24] Another important one was that of John Wright and Joseph Jesson of West Bromwich.HP Pavilion DV4-1211TU Battery

Puddling process

A number of processes for making wrought iron without charcoal were devised as the Industrial Revolution began during the latter half of the 18th century. The most successful of these was puddling, using a puddling furnace (a variety of thereverberatory furnace). This was invented by Henry Cort in 1784.HP Pavilion DV4-1211TX Battery

It was later improved by others including Joseph Hall. In this type of furnace, the metal does not come into contact with the fuel, and so is not contaminated by impurities in it. The flame from the fire is reverberated or sent back down onto the metal on the fire bridge of the furnace.HP Pavilion DV4-1212LA Battery

Unless the raw material used is white cast iron, the pig iron or other raw material first had to be refined into refined ironor finers metal. This would be done in a refinery where raw coal is used to remove silicon and convert carbon from a graphitic form to a combined form.HP Pavilion DV4-1212TU Battery

This metal was placed into the hearth of the puddling furnace where it was melted. The hearth was lined with oxidizing agents such as haematite and iron oxide. This mixture is subjected to a strong current of air and stirred with long bars, called puddling bars or rabbles, through working doors.HP Pavilion DV4-1212TX Battery

The air, stirring, and "boiling" action of the metal help the oxidizing agents to oxidize the impurities and carbon out of the pig iron to their maximum capability. As the impurities oxidize, they form a molten slag while the retaining iron particles solidifiy into spongy wrought iron balls, called puddle balls.HP Pavilion DV4-1213LA Battery

Shingling

There is still some slag left in the puddle balls, so while they are still hot they must be shingled to remove the remaining slag and cinder. It may be achieved by forging the balls under a power hammer, or by squeezing the bloom in a machine. The material obtained at the end of shingling is known as bloom and it is still red-hot.HP Pavilion DV4-1213TU Battery

The blooms are not useful in this form, so they must be rolled into a final product.

Sometimes European ironworks would skip this step completely and roll the puddle balls. The only drawback to this is that the edges of the rough bars are not as well compressed. When the rough bar is reheated, the edges may separate and be lost into the furnace.HP Pavilion DV4-1213TX Battery

Rolling

The bloom is passed through grooved rollers and flat bars were produced. These bars of wrought iron were of poor quality, called muck bars or puddle bars. To improve the quality of wrought iron, these bars were cut up, piled and tied together by wires, a process known as faggoting or piling.HP Pavilion DV4-1214LA Battery

They were then reheated and rolled again in merchant rolls. This process may be repeated several times to get wrought iron of desired quality. Wrought iron that has been rolled multiple times is called merchant bar or merchant iron.

Lancashire process

The advantage of puddling was that it used coal, not charcoal as fuel. However this was little advantage in Sweden, which lacks coal.HP Pavilion DV4-1214TU Battery

Gustaf Ekman observed charcoal fineries at Ulverstone, which were quite different from any in Sweden. After his return to Sweden in the 1830s, he experimented and developed a process similar to puddling but using forewood and charcoal, which was widely adopted in the Bergslagen in the following decades.HP Pavilion DV4-1214TX Battery

The Aston process

In 1925, James Aston of the United States developed a process for manufacturing wrought iron quickly and economically. It involves taking molten steel from aBessemer converter and pouring it into cooler liquid slag. The temperature of the steel is about 1500 °C and the liquid slag is maintained at approximately 1200 °C.HP Pavilion DV4-1215EF Battery

The molten steel contains a large amount of dissolved gases so when the liquid steel hits the cooler surfaces of the liquid slag the gases are liberated. The molten steel then freezes to yield a spongy mass having a temperature of about 1370 °C.[27] This spongy mass must then be finished by being shingled and rolledas described under puddling (above).HP Pavilion DV4-1215TU Battery

Three to four tons can be converted per batch with this method.

Wrought iron as Pure Iron

Dr Gerry McDonnell in 2010 England, demonstrated by analysis that a wrought iron bloom, from a traditional smelt, could be worked into 99.7% pure iron with no evidence of carbon.HP Pavilion DV4-1215TX Battery

It was found that the stringers common to other wrought irons were not present thus making it very malleable for the smith to work hot and cold. A commercial source of pure iron is available and is used by smiths as an alternative to traditional wrought iron and other new generation ferrous metals.HP Pavilion DV4-1216TU Battery

The end of wrought iron

Steel began to replace iron for rails as soon as Bessemer production began (ca. 1860s). Iron remained dominant for structural applications until the 1880s because of problems with brittle steel, caused by high carbon, excess phosphorous or excessive temperature during rolling or too rapid rolling.HP Pavilion DV4-1216TX Battery

By 1890 steel had largely replaced iron for structural applications.

Sheet iron (Armco 99.97% pure iron) had good properties for use in appliances including being well suited for enameling and welding and being rust resistant.HP Pavilion DV4-1217LA Battery

In the 1960s the price of steel production was dropping due to recycling and even using the Aston process wrought iron production was a labor-intensive process. It has been estimated that the production of wrought iron costs approximately twice as much as the production of low carbon steel.HP Pavilion DV4-1217TX Battery

In the United States the last plant closed in 1969. The last in Great Britain (and the world) was the Atlas Ironworks of Thomas Walmsley Ltd in Bolton, which closed in 1973. Its equipment, of a type dating from the 1860s, was moved to the Blists Hill site of Ironbridge Gorge Museum for preservation.HP Pavilion DV4-1218TX Battery

Some wrought iron is still being produced for heritage restoration purposes, but only by recycling scrap.

Properties

The slag inclusions, or stringers, in wrought iron give it properties not found in other forms of ferrous metal. There are approximately 250,000 inclusions per square inch.HP Pavilion DV4-1219TX Battery

A fresh fracture shows a clear bluish color with a high silky luster and fibrous appearance.

Wrought iron lacks the carbon content necessary for hardening through heat treatment, but in areas where steel was uncommon or unknown, tools were sometimes cold-worked (hence cold iron) in order to harden them. An advantage of its low carbon content is its excellent weldability.HP Pavilion DV4-1220BR Battery

Furthermore, sheet wrought iron cannot bend as much as steel sheet metal (when cold worked). Wrought iron can be cast, however there is no engineering advantage as compared to cast iron; cast iron is much easier to produce and thus cheaper, so it is exclusively chosen over wrought iron.HP Pavilion DV4-1220TX Battery

Due to the variations in iron ore origin and iron manufacture, wrought iron can be inferior or superior in corrosion resistance compared to other iron alloys. There are many mechanisms behind this corrosion resistance. Chilton and Evans found that nickel enrichment bands reduce corrosion.HP Pavilion DV4-1220US Battery

They also found that in puddled and forged and piled the working over of the iron spread out copper, nickel and tin impurities, which produce electrochemical conditions that slow down corrosion. The slag inclusions have been shown to disperse corrosion in to an even film to resist pitting.HP Pavilion DV4-1221TX Battery

Another study has shown that slag inclusions are pathways to corrosion.Other studies show that sulfur impurities in the wrought iron decrease corrosion resistance, but phosphorus increase corrosion resistance. Environments with a high concentration of chlorine ions also decreases wrought iron's corrosion resistance.HP Pavilion DV4-1222LA Battery

Wrought iron may be welded in the same manner as mild steel, but the presence of oxide or inclusions will give defective results.[50]The material has a rough surface so it can hold platings and coatings better. For instance, a galvanic zinc finish is approximately 25–40% thicker than the same finish on steel.HP Pavilion DV4-1222NR Battery

In Table 1, the chemical composition of wrought iron is compared to that of pig iron and carbon steel. Although it appears that wrought iron and plain carbon steel have similar chemical compositions, this is deceiving. Most of the manganese, sulfur, phosphorus, and silicon are incorporated into the slag fibers present in the wrought iron, so wrought iron really is purer than plain carbon steel.HP Pavilion DV4-1222TX Battery

Amongst its other properties, wrought iron becomes soft at red heat, and can be easily forged and forge welded.[55] It can be used to form temporary magnets, but cannot be magnetized permanently,[56][57] and is ductile, malleable and tough.HP Pavilion DV4-1223LA Battery

The importance of ductility

For most purposes, ductility is a more important measure of the quality of wrought iron than tensile strength. In tensile testing, the best irons are able to undergo considerable elongation before failure. Higher tensile wrought iron is brittle.HP Pavilion DV4-1223TX Battery

Because of the large number of boiler explosions on steamboats, the U.S. Congress passed legislation in 1830 which approved funds for correcting the problem. The treasury awarded a $1500 contract to the Franklin Institute to conduct a study.HP Pavilion DV4-1224LA Battery

As part of the study Walter R. Johnson and Benjamin Reeves conducted strength tests on various boiler iron using a tester they had built in 1832 based on the design of one by Lagerhjelm in Sweden. Unfortunately, because of the misunderstanding of tensile strength and ductility, this work did little to reduce failures.HP Pavilion DV4-1224TX Battery

The importance of ductility was recognized by some very early in the development of tube boilers, such as Thurston's comment:

‘If made of such good iron as the makers claimed to have put into them “which worked like lead,” they would, as also claimed, when ruptured, open by tearing, and discharge their contents without producing the usual disastrous consequences of a boiler explosion.’HP Pavilion DV4-1225DX Battery

By the late 19 th century when metallurgy was able to better understand what properties and processes made good iron, it was being displaced by steel.

Applications

Wrought iron furniture has a long history, dating back to Roman times.HP Pavilion DV4-1225EE Battery

There are thirteenth century wrought iron gates in Westminster Abbey in London, and wrought iron furniture appeared to reach its peak popularity (in Britain) in the seventeenth century during the reign of William and Mary . However, cast iron and cheaper steel caused a gradual decline in wrought iron manufacture, with the last wrought ironworks in Britain closing in 1974.HP Pavilion DV4-1225LA Battery

It is also used to make home decor items such as baker's racks, wine racks, pot racks, etageres, table bases, desks, gates, beds, candle holders, curtain rods, bars and bar stools.

Zinc smelting is the process of converting zinc concentrates (ores that contain zinc) into pure zinc.HP Pavilion DV4-1225TX Battery

The most common zinc concentrate processed is zinc sulfide,[1] which is obtained by concentratingsphalerite using the froth flotation method. Secondary (recycled) zinc material, such as zinc oxide, is also processed with the zinc sulfide.[2] Approximately 30% of all zinc produced is from recycled sources.HP Pavilion DV4-1226TX Battery

There are two methods of smelting zinc: the pyrometallurgical process and the electrolysis process. Both methods are still used.[2][4] Both of these processes share the same first step: roasting.

Roasting is a process of oxidizing zinc sulfide concentrates at high temperatures into an impure zinc oxide, called "Zinc Calcine". The chemical reactions taking place during the process are:HP Pavilion DV4-1227LA Battery

Approximately 90% of zinc in concentrates are oxidized to zinc oxide, but at the roasting temperatures around 10% of the zinc reacts with the iron impurities of the zinc sulfide concentrates to form zinc ferrite. A byproduct of roasting is sulfur dioxide, which is further processed into sulfuric acid, a commodity.HP Pavilion DV4-1227TX Battery

The linked refinery flow sheet shows a schematic of Noranda's eastern Canadian zinc roasting operation[5]

The process of roasting varies based on the type of roaster used. There are three types of roasters: multiple-hearth, suspension, and fluidized-bed.HP Pavilion DV4-1227US Battery

Multiple-hearth roaster

In a multiple-hearth roaster, the concentrate drops through a series of 9 or more hearths stacked inside a brick-lined cylindrical column. As the feed concentrate drops through the furnace, it is first dried by the hot gases passing through the hearths and then oxidized to produce calcine.HP Pavilion DV4-1228CA Battery

The reactions are slow and can be sustained only by the addition of fuel. Multiple hearth roasters are unpressurized and operate at about 690 °C (1,270 °F). Operating time depends upon the composition of concentrate and the amount of the sulfur removal required. Multiple hearth roasters have the capability of producing a high-purity calcine.HP Pavilion DV4-1228LA Battery

Suspension roaster

In a suspension roaster, the concentrates are blown into a combustion chamber very similar to that of a pulverized coal furnace. The roaster consists of a refractory-lined cylindrical steel shell, with a large combustion space at the top and 2 to 4 hearths in the lower portion, similar to those of a multiple hearth furnace.HP Pavilion DV4-1228TX Battery

Additional grinding, beyond that required for a multiple hearth furnace, is normally required to ensure that heat transfer to the material is sufficiently rapid for the desulfurization and oxidation reactions to occur in the furnace chamber. Suspension roasters are unpressurized and operate at about 980 °C(1,800 °F).HP Pavilion DV4-1229LA Battery

Fluidized-bed roaster

In a fluidized-bed roaster, finely ground sulfide concentrates are suspended and oxidized in a feedstock bed supported on an air column. As in the suspension roaster, the reaction rates for desulfurization are more rapid than in the older multiple-hearth processes.HP Pavilion DV4-1229TX Battery

Fluidized-bed roasters operate under a pressure slightly lower than atmospheric and at temperatures averaging 1,000 °C (1,830 °F). In the fluidized-bed process, no additional fuel is required after ignition has been achieved. The major advantages of this roaster are greater throughput capacities, greater sulfur removal capabilities, and lower maintenance.HP Pavilion DV4-1230BR Battery

Electrolysis process

The electrolysis process, also known as the hydrometallurgical process, Roast-Leach-Electrowin (RLE) process, or electrolytic process, is more widely used than the pyrometallurgical processes.

The electrolysis process consists of 4 steps: leaching, purification, electrolysis, and melting and casting.HP Pavilion DV4-1230TX Battery

Leaching

The basic leaching chemical formula that drives this process is:

\mathrm{ZnO + SO_3 \rarr ZnSO_4}

This is achieved in practice though a process called double leaching. The calcine is first leached in a neutral or slightly acidic solution (of sulfuric acid) in order to leach the zinc out of the zinc oxide.HP Pavilion DV4-1231TX Battery

The remaining calcine is then leached in strong sulfuric acid to leach the rest of the zinc out of the zinc oxide and zinc ferrite. The result of this process is a solid and a liquid; the liquid contains the zinc and is often called leach product; the solid is called leach residue and contains precious metals (usually lead and silver) which are sold as a by-product.HP Pavilion DV4-1232TX Battery

There is also iron in the leach product from the strong acid leach, which is removed in an intermediate step, in the form of goethite, jarosite, and haematite. There is still cadmium, copper, arsenic, antimony, cobalt, germanium, nickel, andthallium in the leach product. Therefore it needs to be purified.HP Pavilion DV4-1233TX Battery

Purification

The purification process utilizes the cementation process to further purify the zinc. It uses zinc dust and steam to remove copper, cadmium, cobalt, and nickel, which would interfere with the electrolysis process. After purification, concentrations of these impurities are limited to less than 0.05 milligram per liter (4×10?7 pound per U.S. gallon).HP Pavilion DV4-1234TX Battery

Purification is usually conducted in large agitated tanks. The process takes place at temperatures ranging from 40 to 85 °C (104 to 185 °F), and pressures ranging from atmospheric to 2.4 atm (240 kPa) (absolute scale). The by-products are sold for further refining.HP Pavilion DV4-1235EE Battery

The zinc sulfate solution must be very pure for electrowinning to be at all efficient. Impurities can change the decomposition voltage enough to where the electrolysis cell produces largely hydrogen gas rather than zinc metal.[6]

Electrolysis

Zinc is extracted from the purified zinc sulfate solution by electrowinning, which is a specialized form of electrolysis.HP Pavilion DV4-1235EI Battery

The process works by passing an electric current through the solution in a series of cells. This causes the zinc to deposits on the cathodes (aluminium sheets) and oxygen to form at the anodes. Sulfuric acid is also formed in the process and reused in the leaching process.HP Pavilion DV4-1235TX Battery

Every 24 to 48 hours, each cell is shut down, the zinc-coated cathodes are removed and rinsed, and the zinc is mechanically stripped from the aluminium plates.

Electrolytic zinc smelters contain as many as several hundred cells. A portion of the electrical energy is converted into heat, which increases the temperature of the electrolyte.HP Pavilion DV4-1236TX Battery

Electrolytic cells operate at temperature ranges from 30 to 35 °C (86 to 95 °F) and at atmospheric pressure. A portion of the electrolyte is continuously circulated through the cooling towers both to cool and concentrate the electrolyte through evaporation of water. The cooled and concentrated electrolyte is then recycled to the cells.HP Pavilion DV4-1237TX Battery

This process accounts for approximately one-third of all the energy usage when smelting zinc.

There are two common processes for electrowinning the metal: the low current density process, and the Tainton high current density process.HP Pavilion DV4-1238TX Battery

The former uses a 10% sulfuric acid solution as the electrolyte, with current density of 270–325 amperes per square meter. The latter uses 22–28% sulfuric acid solution as the electrolyte with a current density of about 1,000 amperes per square metre.HP Pavilion DV4-1239TX Battery

The latter gives better purity and has higher production capacity per volume of electrolyte, but has the disadvantage of running hotter and being more corrosive to the vessel in which it is done. In either of the electrolytic processes, each metric ton of zinc production expends about 3,900 kW·h (14 GJ) of electric power.HP Pavilion DV4-1240TX Battery

Melting and casting

The final step is to melt the cathodes in an induction furnace. It is then either cast into pure zinc (99.995% pure) ingots or alloyed and cast into ingots.

Pyrometallurgical processes

There are also several pyrometallurgical processes that reduce zinc oxide using carbon, then distil the metallic zinc from the resulting mix in an atmosphere of carbon monoxide.HP Pavilion DV4-1241TX Battery

The major downfall of any of the pyrometallurgical process is that it is only 98% pure; a standard composition is 1.3% lead, 0.2% cadmium, 0.03% iron, and 98.5% zinc.  This may be pure enough for galvanization, but not enough for die casting alloys, which requires special high-grade zinc (99.995% pure).HP Pavilion DV4-1242TX Battery

In order to reach this purity the zinc must be refined.

The four types of commercial pyrometallurgical processes are the Belgian-type horizontal retort process, the New Jersey Zinc continuous vertical-retort process, theblast furnace process and the St. Joseph Minerals Corporation's (electrothermic) process.HP Pavilion DV4-1243TX Battery

St. Joseph Mineral Company (electrothermic) process

This process was developed by the St. Joseph Mineral Company in 1930, and is the only pyrometallurgical process still used in the US to smelt zinc. The advantage of this system is that it is able to smelt a wide variety of zinc-bearing materials, including electric arc furnace dust.HP Pavilion DV4-1244TX Battery

The disadvantage of this process is that it is less efficient than the electrolysis process.

The process begins with a downdraft sintering operation. The sinter, which is a mixture of roaster calcine and EAF calcine, is loaded onto a gate type conveyor and then combustions gases are pumped through the sinter. HP Pavilion DV4-1245BR Battery

The carbon in the combustion gases react with some the impurities, such as lead, cadmium, and halides. These impurities are driven off into filtration bags. The sinter after this process, called product sinter, usually has a composition of 48% zinc, 8% iron, 5% aluminium, 4% silicon, 2.5% calcium, and smaller quantities of magnesium, lead, and other metals.HP Pavilion DV4-1245TX Battery

The sinter product is then charged with coke into an electric retort furnace. A pair of graphite electrodes from the top and bottom furnace produce current flow through the mixture. The coke provides electrical resistance to the mixture in order to heat the mixture to 1,400 °C (2,550 °F) and produce carbon monoxide.HP Pavilion DV4-1246TX Battery

These conditions allow for the following chemical reaction to occur:

The zinc vapour and carbon dioxide pass to a vacuum condenser, where zinc is recovered by bubbling through a molten zinc bath. Over 95% of the zinc vapour leaving the retort is condensed to liquid zinc. The carbon dioxide is regenerated with carbon, and the carbon monoxide is recycled back to the retort furnace.HP Pavilion DV4-1247TX Battery

Blast furnace process

This process was developed by the Imperial Smelting Corporation at Avonmouth, England, in order to increase production, increase efficiency, and decrease labour and maintenance costs. L. J. Derham proposed using a spray of molten lead droplets to rapidly chill and absorb the zinc vapour, despite the high concentration of carbon dioxide.HP Pavilion DV4-1248TX Battery

The mixture is then cooled, where the zinc separates from the lead. The first plant using this design opened up in 1950. One of the advantages of this process is that it can co-produce lead bullion and copper dross. In 1990, it accounted for 12% of the world's zinc production.HP Pavilion DV4-1249TX Battery

The process starts by charging solid sinter and heated coke into the top of the blast furnace. Preheated air at 190 to 1,050 °C (370 to 1,920 °F) is blown into the bottom of the furnace. Zinc vapour and sulfides leave through the top and enter the condenser. Slag and lead collect at the bottom of the furnace and are tapped off regularly.HP Pavilion DV4-1250TX Battery

The zinc is scrubbed from the vapour in the condenser via liquid lead. The liquid zinc is separated from the lead in the cooling circuit. Approximately 5,000 metric tons (5,500 short tons) of lead are required each year for this process, however this process recovers 25% more lead from the starting ores than other processes.HP Pavilion DV4-1251TX Battery

New Jersey Zinc continuous vertical retort

The New Jersey Zinc process is no longer used to produce primary zinc in the U.S., Europe and Japan, however it still is used to treat secondary operations. This processes peaked in 1960, when 5% of the world production was done by this process.HP Pavilion DV4-1252TX Battery

A modified version of this process is still used at Huludao, China, which produced 65,000 metric tons per year.

This process begins by roasting concentrates that are mixed with coal and briquetted in two stages. The briquettes are then heated in an autogenous coker at 700 °C(1,292 °F) and then charged into the retort.HP Pavilion DV4-1253TX Battery

There are three reasons to briquette the calcine: to ensure free downward movement of the charge; to permit heat transfer across a practical size cross-section; to allow adequate porosity for the passage of reduced zinc vapour to the top of the retort. The reduced zinc vapour that is collected at the top of the retort is then condensed to a liquid.HP Pavilion DV4-1254TX Battery

Overpelt improved upon this design by using only one large condensation chamber, instead of many small ones, as it was originally designed. This allowed for the carbon monoxide to be recirculated into the furnaces for heating the retorts.HP Pavilion DV4-1255TX Battery

This process was licensed to the Imperial Smelting Company (ISC), in Avonmouth, England, which had a large vertical retort (VR) plant in production for many years. It was used until the mid 1970s when it was superseded by the company's Imperial Smelting Furnace (ISF) plant. The VR plant was demolished in 1975.HP Pavilion DV4-1256TX Battery

Belgian-type horizontal retort process

This process was the main process used in Britain from the mid-19th century until 1951. The process was very inefficient as it was designed as a small scale batch operation. Each retort only produced 40 kilograms (88 lb) so companies would put them together in banks and used one large gas burner to heat all of them.HP Pavilion DV4-1257TX Battery

The Belgian process requires redistillation to remove impurities of lead, cadmium, iron, copper, and arsenic.
Although some zinc artifacts appear to have been made during classical antiquity in Europe,  the first production of zinc in quantity seems to have been in Indiaand China.HP Pavilion DV4-1258TX Battery

In India, zinc was produced at Zawar from the 12th to the 18th centuries. The sphalerite ore found here was presumably converted to zinc oxide via roasting, although no archaeological evidence of this has been found. Smelting is thought to have been done in sealed cylindrical clay retorts which were packed with a mixture of roasted ore,HP Pavilion DV4-1259TX Battery

dolomite, and an organic material, perhaps cow dung, and then placed vertically in a furnace and heated to around 1100 °C. Carbon monoxideproduced by the charring of the organic material would have reduced the zinc oxide to zinc vapour, which then liquefied in a conical clay condenser at the bottom of the retort, dripping down into a collection vesselww.laptopbattery-pack.co.uk/hp-pavilion-dv4-1260tx-battery-13679.htm" title="HP PAVILION DV4-1260TX laptop battery">HP Pavilion DV4-1260TX Battery

Over the period 1400–1800, production is estimated to have been about 200 kg/day.[11] Zinc was also smelted in China from the mid-sixteenth century on.

Large-scale zinc production in Europe began with William Champion, who patented a zinc distillation process in 1738.HP Pavilion DV4-1265DX Battery

In Champion's process, zinc ore (in this case, the carbonate, ZnCO3) was sealed in large reduction pots with charcoal and heated in a furnace. The zinc vapor then descended through an iron condensing pipe until reaching a water-filled vessel at the bottom.HP Pavilion DV4-1272CM Battery

Champion set up his first zinc works in Bristol, England, but soon expanded to Warmley and by 1754 had built four zinc furnaces there. Although Champion succeeded in producing about 200 tons of zinc, his business plans were not successful and he was bankrupt by 1769.[14] However, zinc smelting continued in this area until 1880.HP Pavilion DV4-1275MX Battery

Early European zinc production also took place in Silesia, in Carinthia, and in Liège, Belgium. In the Carinthian process, used in works established in 1798 by Bergrath Dillinger, a wood-fueled furnace heated a large number of small vertical retorts, and zinc vapor then dropped through a ceramic pipe into a common condensation chamber below.HP Pavilion DV4-1280US Battery

This process was out of use by 1840. The Belgian and Silesian processes both used horizontal retorts. In Silesia, Johann Ruhberg built a furnace to distill zinc in 1799, at first using pots but later changing to flat-bottomed retorts called "muffles", attached to horizontal tubes bent downwards in which the zinc condensed.HP Pavilion DV4-1281US Battery

The Silesian process eventually merged with the Belgian process. This process, developed by Jean-Jacques Daniel Dony, was introduced 1805–1810, and used retorts with a cylindrical cross-section. Condensers were horizontal clay tubes extending from the ends of the retorts.HP Pavilion DV4-1282CM Battery

The merged "Belgo-Silesian" horizontal retort process was widely adopted in Europe by the third quarter of the 19th century, and later in the United States.

Experimental attempts to extract zinc via electrolysis begun in the 19th century, but the only commercially successful application before 1913 was a process,HP Pavilion DV4-1283CL Battery

used inGreat Britain and Austria, where zinc and chlorine were co-produced by electrolysis of an aqueous zinc chloride solution. The Anaconda Copper Company, atAnaconda, Montana, and the Consolidated Mining and Smelting Company, at Trail, British Columbia, both built successful electrolytic plants in 1915 using the currently used zinc sulfate process.HP Pavilion DV4-1287CL Battery

This method has continued to grow in importance and in 1975 accounted for 68% of world zinc production.

The continuous vertical retort process was introduced in 1929 by the New Jersey Zinc Company. This process used a retort with silicon carbide walls, around 9 meters high and with a cross section of 2 by 0.3 meters.HP Pavilion DV4-1290BR Battery

The walls of the retort were heated to 1300 °C and briquettes consisting of sintered zinc ore, coke, coal, and recycled material were fed into the top of the retort. Gaseous zinc was drawn off from the top of the column and, after a 20-hour journey through the retort, spent briquettes were removed from the bottom.HP Pavilion DV4-1290EL Battery

To condense the gaseous zinc, the company first used a simple brick chamber with carborundum baffles, but efficiency was poor. During the 1940s a condenser was developed which condensed the zinc vapor on a spray of liquid zinc droplets, thrown up by an electrical impeller.HP Pavilion DV4-1292CM Battery

The electrothermic process, developed by the St. Joseph's Lead Company, was somewhat similar. The first commercial plant using this process was built in 1930 at the present site of Josephtown, Pennsylvania. The electrothermic furnace was a steel cylinder around 15 meters high and 2 meters in diameter, lined with firebrick.HP Pavilion DV4-1299EE Battery

A mixture of sintered ore and coke was fed into the top of the furnace, and a current of 10,000–20,000 amperes, at a potential difference of 240 volts, was applied between carbon electrodes in the furnace, raising the temperature to 1200–1400 °C.HP Pavilion DV4-1300 CTO Battery

An efficient condenser was devised for this process from 1931–1936; it consisted of a bath of liquid zinc which the exhaust gases were drawn through by suction. The zinc content of the gas stream was absorbed into the liquid bath.

The blast-furnace process was developed starting in 1943 at Avonmouth, England by the Imperial Smelting Corporation. It uses a spray of molten lead droplets to condense the zinc vapor.HP Pavilion DV4-1301TU Battery

Nickel (  /?n?k?l/) is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrousmetal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile. Pure nickel shows a significant chemical activity, though larger pieces of the metal are slow to react with air at ambient conditions due to the formation of a protective oxide surface.HP Pavilion DV4-1301TX Battery

However, nickel is reactive with oxygen to the extent that native nickel is rare on Earth's surface, and is mostly confined to the interiors of larger nickel iron meteorites, which were protected from oxidation in space. Such native nickel is always found on Earth alloyed with iron,HP Pavilion DV4-1302TU Battery

in keeping with the element's origin as a major end-product of the nucleosynthesis process, along with iron, in supernovas. An iron-nickel alloy is thought to compose the Earth's core.

The use of nickel (as a natural meteoric nickel-iron alloy) has been traced as far back as 3500 BC.HP Pavilion DV4-1302TX Battery

Nickel was first isolated and classified as a chemical element in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. Its most important ore minerals are laterites, including limonite, garnierite, and pentlandite. Major production sites include Sudbury region in Canada (which is thought to be of meteoric origin), New Caledonia and Norilsk in Russia.HP Pavilion DV4-1303TU Battery

Because of nickel's slow rate of oxidation at room temperature, it is considered corrosion-resistant. Historically this has led to its use for plating metals such as iron and brass, to its use for chemical apparatus, and its use in certain alloys that will retain a high silvery polish, such as German silver.HP Pavilion DV4-1303TX Battery

About 6% of world nickel production is still used for corrosion-resistant pure-nickel plating. Nickel was once a common component of coins, but has largely been replaced by cheaper iron for this purpose, especially since the metal has proven to be a skin allergen for some people.HP Pavilion DV4-1304TU Battery

Nickel is one of the four elements that are ferromagnetic around room temperature. Alnico permanent magnets based partly on nickel are of intermediate strength between iron-based permanent magnets and rare earth magnets. The metal is chiefly valuable in the modern world for the alloys it forms; about 60% of world production is used in nickel-steels (particularlystainless steel). HP Pavilion DV4-1304TX Battery

Other common alloys, as well as some new superalloys, make up most of the remainder of world nickel use, with chemical uses for nickel compounds consuming less than 3% of production. As a compound, nickel has a number of niche chemical manufacturing uses, such as a catalyst for hydrogenation.HP Pavilion DV4-1305TU Battery

Enzymes of some microorganisms and plants contain nickel as an active center, which makes the metal an essential nutrient for them.

Atomic and physical properties

Nickel is a silvery-white metal with a slight golden tinge that takes a high polish.HP Pavilion DV4-1305TX Battery

It is one of only four elements that are magnetic at or near room temperature, the others being iron, cobalt and gadolinium. Its Curie temperature is 355 °C, meaning that bulk nickel is non-magnetic above this temperature. The unit cell of nickel is a face centered cube with the lattice parameter of 0.352 nm giving an atomic radius of 0.124 nm.HP Pavilion DV4-1306TU Battery

Nickel belongs to the transition metals and is hard and ductile.

The nickel atom has two electron configurations, [Ar] 4s2 3d8 and [Ar] 4s1 3d9, which are very close in energy, where the symbol [Ar] refers to the argon-like core structure. There is some disagreement as to which should be considered the lowest energy configuration.HP Pavilion DV4-1306TX Battery

Chemistry textbooks quote the electron configuration of nickel as [Ar] 4s2 3d8,[6] or equivalently as [Ar] 3d8 4s2.[7] This configuration agrees with the Madelung energy ordering rule, which predicts that 4s is filled before 3d. It is supported by the experimental fact that the lowest energy state of the nickel atom is a 4s2 3d8 energy level, specifically the 3d8(3F) 4s2 3F, J=4 level.HP Pavilion DV4-1307TU Battery

However each of these two configurations in fact gives rise to a set of states at different energies.[8] The two sets of energies overlap, and the average energy of states having configuration [Ar] 4s1 3d9 is in fact lower than the average energy of states having configuration [Ar] 4s2 3d8.HP Pavilion DV4-1307TX Battery

For this reason the research literature on atomic calculations quotes the ground state configuration of nickel as 4s1 3d9.

Naturally occurring nickel is composed of 5 stable isotopes; 58Ni, 60Ni, 61Ni, 62Ni and 64Ni with 58Ni being the most abundant (68.077% natural abundance).HP Pavilion DV4-1308TU Battery

62Ni is the "most stable" nuclide of all the existing elements, with binding energy greater than both 56Fe, often incorrectly cited as "most stable", and 58Fe.[9] 18 radioisotopes have been characterised with the most stable being 59Ni with a half-life of 76,000 years, 63Ni with a half-life of 100.1 years, and 56Ni with a half-life of 6.077 days.HP Pavilion DV4-1308TX Battery

All of the remaining radioactive isotopes have half-lives that are less than 60 hours and the majority of these have half-lives that are less than 30 seconds. This element also has 1 meta state.

Nickel-56 is produced by the silicon burning process and later set free in large quantities during type Ia supernovae.HP Pavilion DV4-1309TU Battery

Indeed, the shape of the light curve of these supernovae at intermediate to late-times corresponds to the decay via electron capture of nickel-56 to cobalt-56 and ultimately to iron-56. Nickel-59 is a long-lived cosmogenic radionuclide with a half-life of 76,000 years. 59Ni has found many applications in isotope geology.HP Pavilion DV4-1309TX Battery

59Ni has been used to date the terrestrial age of meteorites and to determine abundances of extraterrestrial dust in ice and sediment. Nickel-60 is the daughter product of the extinct radionuclide 60Fe, which decays with a half-life of 2.6 million years.HP Pavilion DV4-1310TU Battery

Because 60Fe has such a long half-life, its persistence in materials in the solar system at high enough concentrations may have generated observable variations in the isotopic composition of 60Ni. Therefore, the abundance of 60Ni present in extraterrestrial material may provide insight into the origin of the solar system and its early history.HP Pavilion DV4-1310TX Battery

Nickel-62 has the highest binding energy per nucleon of any isotope for any element (8.7946 Mev/nucleon).[12] Isotopes heavier than 62Ni cannot be formed by nuclear fusion without losing energy. Nickel-48, discovered in 1999, is the most proton-rich heavy element isotope known.HP Pavilion DV4-1311TU Battery

With 28 protons and 20 neutrons 48Ni is "double magic" (like 208Pb) and therefore unusually stable.

The isotopes of nickel range in atomic weight from 48 u (48Ni) to 78 u (78Ni). Nickel-78's half-life was recently measured to be 110 milliseconds and is believed to be an important isotope involved in supernova nucleosynthesis of elements heavier than iron.HP Pavilion DV4-1311TX Battery

On Earth, nickel occurs most often in combination with sulfur and iron in pentlandite, with sulfur in millerite, with arsenic in the mineral nickeline, and with arsenic andsulfur in nickel galena.[15] Nickel is commonly found in iron meteorites as the alloyskamacite and taenite.HP Pavilion DV4-1312TU Battery

The bulk of the nickel mined comes from two types of ore deposits. The first are lateriteswhere the principal ore minerals are nickeliferous limonite: (Fe, Ni)O(OH) and garnierite(a hydrous nickel silicate): (Ni, Mg)3Si2O5(OH)4. The second are magmatic sulfide deposits where the principal ore mineral is pentlandite: (Ni, Fe)9S8.HP Pavilion DV4-1312TX Battery

In terms of supply, the Sudbury region of Ontario, Canada, produces about 30% of the world's supply of nickel. The Sudbury Basin deposit is theorized to have been created by ameteorite impact event early in the geologic history of Earth. Russia contains about 40% of the world's known resources at the Norilsk deposit in Siberia.HP Pavilion DV4-1313DX Battery

The Russian mining company MMC Norilsk Nickel obtains the nickel and the associated palladium for world distribution. Other major deposits of nickel are found in New Caledonia, France, Australia, Cuba, and Indonesia. Deposits found in tropical areas typically consist of laterites,HP Pavilion DV4-1313TU Battery

which are produced by the intense weathering of ultramafic igneous rocks and the resulting secondary concentration of nickel bearing oxide and silicate minerals.

Based on geophysical evidence, most of the nickel on Earth is postulated to be concentrated in the Earth's core. Kamacite andtaenite are naturally occurring alloys of iron and nickel.HP Pavilion DV4-1313TX Battery

For kamacite the alloy is usually in the proportion of 90:10 to 95:5 although impurities such as cobalt or carbon may be present, while for taenite the nickel content is between 20% and 65%. Kamacite and taenite occur in nickel iron meteorites.[16]

The most common oxidation state of nickel is +2, but compounds of Ni0, Ni+, and Ni3+ are well known, and Ni4+ has been demonstrated.HP Pavilion DV4-1314TU Battery

Nickel(0)

Tetracarbonylnickel (Ni(CO)4), discovered by Ludwig Mond,  is a volatile liquid at room temperature. On heating, the complex decomposes back to nickel and carbon monoxide:HP Pavilion DV4-1314TX Battery

Ni(CO)4 Ni + 4 CO

This behavior is exploited in the Mond process for purifying nickel, as described above. The related nickel(0) complexbis(cyclooctadiene)nickel(0) is a useful catalyst in organonickel chemistry due to the easily displaced cod ligands.HP Pavilion DV4-1315TU Battery

xNickel(II)

Nickel(II) compounds are known with all common anions, i.e. the sulfide, sulfate, carbonate, hydroxide, carboxylates, and halides.Nickel(II) sulfate is produced in large quantities by dissolving nickel metal or oxides in sulfuric acid. It exists as both a hexa- and heptahydrates.[19] This compound is useful for electroplating nickel.HP Pavilion DV4-1315TU Battery

The four halogens form nickel compounds, all of which adopt octahedral geometries. Nickel(II) chloride is most common, and its behavior is illustrative of the other halides. Nickel(II) chloride is produced by dissolving nickel residues in hydrochloric acid.HP Pavilion DV4-1315TX Battery

The dichloride is usually encountered as the green hexahydrate, but it can be dehydrated to give the yellow anhydrous NiCl2. Some tetracoordinate nickel(II) complexes form both tetrahedral and square planar geometries. The tetrahedral complexes are paramagnetic and the square planar complexes are diamagnetic.HP Pavilion DV4-1316TU Battery

This equilibrium as well as the formation of octahedral complexes contrasts with the behavior of the divalent complexes of the heavier group 10 metals, palladium(II) and platinum(II), which tend to adopt only square-planar complexes.[17]

Nickelocene is known; it has an electron count of 20, making it relatively unstable.HP Pavilion DV4-1316TX Battery

Nickel(I), (III), and (IV)

For simple compounds, nickel(III) and nickel(IV) only occurs with fluoride and oxides. Nickel(III) oxide is used as the cathodein many rechargeable batteries, including nickel-cadmium, nickel-iron, nickel hydrogen, and nickel-metal hydride, and used by certain manufacturers in Li-ion batteries.HP Pavilion DV4-1317TU Battery

Because the ores of nickel are easily mistaken for ores of silver, understanding of this metal and its use dates to relatively recent times. However, the unintentional use of nickel is ancient, and can be traced back as far as 3500 BC. Bronzes from what is now Syria had contained up to 2% nickel.HP Pavilion DV4-1317TX Battery

Further, there are Chinese manuscripts suggesting that "white copper" (cupronickel, known as baitung) was used there between 1700 and 1400 BC. This Paktong white copper was exported to Britain as early as the 17th century, but the nickel content of this alloy was not discovered until 1822.HP Pavilion DV4-1318TU Battery

In medieval Germany, a red mineral was found in the Erzgebirge (Ore Mountains) that resembled copper ore. However, when miners were unable to extract any copper from it, they blamed a mischievous sprite of German mythology, Nickel (similar to Old Nick), for besetting the copper.HP Pavilion DV4-1318TX Battery

They called this ore Kupfernickel from the GermanKupfer for copper. This ore is now known to be nickeline or niccolite, a nickel arsenide. In 1751, Baron Axel Fredrik Cronstedt was attempting to extract copper from kupfernickel and obtained instead a white metal that he named after the spirit which had given its name to the mineral, nickel.HP Pavilion DV4-1319TU Battery

In modern German, Kupfernickel or Kupfer-Nickel designates the alloy cupronickel.

After its discovery, the only source for nickel was the rare Kupfernickel, but, from 1824 on, the nickel was obtained as byproduct of cobalt blue production.HP Pavilion DV4-1319TX Battery

The first large-scale producer of nickel was Norway, which exploited nickel-rich pyrrhotite from 1848 on. The introduction of nickel in steel production in 1889 increased the demand for nickel, and the nickel deposits of New Caledonia, which were discovered in 1865, provided most of the world's supply between 1875 and 1915.HP Pavilion DV4-1320CA Battery

The discovery of the large deposits in the Sudbury Basin, Canada in 1883, in Norilsk-Talnakh, Russia in 1920, and in the Merensky Reef, South Africa in 1924 made large-scale production of nickel possible.

Nickel has been a component of coins since the mid-19th century.HP Pavilion DV4-1320TX Battery

In the United States, the term "nickel" or "nick" was originally applied to the copper-nickel Flying Eagle cent, which replaced copper with 12% nickel 1857–58, then the Indian Head cent of the same alloy from 1859–1864. Still later in 1865, the term designated the three-cent nickel, with nickel increased to 25%.HP Pavilion DV4-1321TX Battery

In 1866, the five-cent shield nickel (25% nickel, 75% copper) appropriated the designation. Along with the alloy proportion, this term has been used to the present in the United States. Coins of nearly pure nickel were first used in 1881 in Switzerland, and more notably 99.9% nickel five-cent coins were struck in Canada (the world's largest nickel producer at the time) during non-war years from 1922–1981, and their metal content made these coins magnetic.HP Pavilion DV4-1322TX Battery

During the wartime period 1942–45, more or all nickel was removed from Canadian and U.S. coins, due to nickel's war-critical use in armor. Canada switched alloys again to plated steel during the Korean war, but was forced to stop making pure nickel "nickels" in 1981, reserving the pure 99.9% nickel alloy after 1968 only to its higher-value coins.HP Pavilion DV4-1322US Battery

Finally, in the 21st century, with rising nickel prices, most countries that formerly used nickel in their coins have abandoned the metal for cost reasons, and the U.S. five-cent coin remains one of the few in which the metal is still used, save for exterior plating.HP Pavilion DV4-1323TX Battery

In 2005, Russia was the largest producer of nickel with about one-fifth world share closely followed by Canada, Australia, and Indonesia, as reported by the British Geological Survey. A nickel deposit in western Turkey had been exploited, with this location being especially convenient for European smelters, steelmakers, and factories.HP Pavilion DV4-1324TX Battery

The one locality in the United States where nickel was commercially mined isRiddle, Oregon, where several square miles of nickel-bearing garnierite surface deposits are located. The mine closed in 1987. The Eagle mine project is a proposed new nickel mine in Michigan's upper peninsula.HP Pavilion DV4-1325TX Battery

Extraction and purification

Nickel is recovered through extractive metallurgy. Nickel is extracted from its ores by conventional roasting and reduction processes that yield a metal of greater than 75% purity. In many stainless steel applications, 75% pure nickel can be used without further purification, depending on the composition of the impurities.HP Pavilion DV4-1326TX Battery

Most sulfide ores have traditionally been processed using pyrometallurgical techniques to produce a matte for further refining. Recent advances in hydrometallurgyhave resulted in significant nickel purification using these processes.HP Pavilion DV4-1327TX Battery

Most sulfide deposits have traditionally been processed by concentration through a froth flotation process followed by pyrometallurgical extraction. In hydrometallurgical processes, nickel sulfide ores undergo flotation (differential flotation if Ni/Fe ratio is too low) and then smelted.HP Pavilion DV4-1328TX Battery

After producing the nickel matte, further processing is done via the Sherritt-Gordon process. First, copper is removed by addinghydrogen sulfide, leaving a concentrate of only cobalt and nickel. Then, solvent extraction is used to separate the cobalt and nickel, with the final nickel concentration greater than 99%.HP Pavilion DV4-1329TX Battery

Electrorefining

A second common form of further refining involves the leaching of the metal matte into a nickel salt solution, followed by the electro-winning of the nickel from solution by plating it onto a cathode as electrolytic nickel.HP Pavilion DV4-1330TX Battery

Purification of nickel oxides to obtain the purest metal is performed via the Mond process, which increases the nickel concentrate to greater than 99.99% purity. This process was patented by L. Mond and has been in industrial use since before the beginning of the 20th century.HP Pavilion DV4-1331TX Battery

In the process, nickel is reacted with carbon monoxide at around 40–80 °C to formnickel carbonyl in the presence of a sulfur catalyst. Iron gives iron pentacarbonyl too, but this reaction is slow. If necessary, it may be separated by distillation. Dicobalt octacarbonyl is also formed in this process, but it decomposes to tetracobalt dodecacarbonyl at the reaction temperature to give a non-volatile solid.HP Pavilion DV4-1332TX Battery

Nickel is re-obtained from the nickel carbonyl by one of two processes. It may be passed through a large chamber at high temperatures in which tens of thousands of nickel spheres, called pellets, are constantly stirred. It then decomposes depositing pure nickel onto the nickel spheres.HP Pavilion DV4-1365DX Battery

Alternatively, the nickel carbonyl may be decomposed in a smaller chamber at 230 °C to create fine nickel powder. The resultant carbon monoxide is re-circulated and reused through the process. The highly pure nickel produced by this process is known as "carbonyl nickel."HP Pavilion DV4-1400 CTO Battery

Metal value

The market price of nickel surged throughout 2006 and the early months of 2007; as of April 5, 2007, the metal was trading at 52,300 USD/tonne or 1.47 USD/oz. The price subsequently fell dramatically from these peaks, and as of 19 January 2009 the metal was trading at 10,880 USD/tonne.HP Pavilion DV4-1404TX Battery

The US nickel coin contains 0.04 oz (1.25 g) of nickel, which at the April 2007 price was worth 6.5 cents, along with 3.75 grams of copper worth about 3 cents, making the metal value over 9 cents. Since the face value of a nickel is 5 cents, this made it an attractive target for melting by people wanting to sell the metals at a profit.HP Pavilion DV4-1405TX Battery

However, the United States Mint, in anticipation of this practice, implemented new interim rules on December 14, 2006, subject to public comment for 30 days, which criminalize the melting and export of cents and nickels. Violators can be punished with a fine of up to $10,000 and/or imprisoned for a maximum of five years.HP Pavilion DV4-1406TX Battery

As of September 16, 2011, the melt value of a U.S. nickel is $0.0600409, which is 20% higher than the face value.

Applications

The fraction of global nickel production presently used for various applications is as follows: 60% for making nickel steels; 14% in nickel-copper alloys and nickel silver;HP Pavilion DV4-1407TX Battery

9% to make malleable nickel, nickel clad, Inconel, and other superalloys; 6% in plating; 3% for nickel cast irons; 3% in heat and electric resistance alloys, such as Nichrome; 2% for nickel brasses and bronzes; 3% in all other applications combined.HP Pavilion DV4-1408TX Battery

Nickel is used in many specific and recognizable industrial and consumer products, including stainless steel, alnico magnets, coinage, rechargeable batteries, electric guitar strings, microphone capsules, and special alloys. It is also used for plating and as a green tint in glass.HP Pavilion DV4-1409TX Battery

Nickel is preeminently an alloy metal, and its chief use is in the nickel steels and nickel cast irons, of which there are many varieties. It is also widely used in many other alloys, such as nickel brasses and bronzes, and alloys with copper, chromium, aluminium, lead, cobalt, silver, and gold (Inconel, Incoloy, Monel, Nimonic).HP Pavilion DV4-1413LA Battery

Because of its resistance to corrosion, nickel has been occasionally used historically as a substitute for decorative silver. Nickel was also occasionally used in some countries after 1859 as a cheap coinage metal (see above) but beginning the later years of the 20th century has largely replaced by cheaper stainless steel (i.e., iron) alloys, except notably in the United States.HP Pavilion DV4-1414LA Battery

Nickel is an excellent alloying agent for certain other precious metals, and so used in the so-called fire assay, as a collector of platinum group elements (PGE). As such, nickel is capable of full collection of all 6 PGE elements from ores, in addition to partial collection of gold.HP Pavilion DV4-1416LA Battery

High-throughput nickel mines may also engage in PGE recovery (primarily platinum and palladium); examples are Norilsk in Russia and the Sudbury Basin in Canada.

Nickel foam or nickel mesh is used in gas diffusion electrodes for alkaline fuel cells.HP Pavilion DV4-1425LA Battery

Nickel and its alloys are frequently used as catalysts for hydrogenation reactions. Raney nickel, a finely-divided nickel-aluminium alloy, is one common form, however related catalysts are also often used, including related 'Raney-type' catalysts.HP Pavilion DV4T Battery

Nickel is a naturally magnetostrictive material, meaning that, in the presence of a magnetic field, the material undergoes a small change in length.[42] In the case of nickel, this change in length is negative (contraction of the material), which is known as negative magnetostriction and is on the order of 50 ppm.HP Pavilion DV4T-1000 CTO Battery

Nickel is used as a binder in the cemented tungsten carbide or hardmetal industry and used in proportions of six to 12% by weight. Nickel can make the tungsten carbide magnetic and adds corrosion-resistant properties to the cemented tungsten carbide parts, although the hardnesses are lower than those of parts made of the binder cobalt.HP Pavilion DV4T-1100 CTO Battery

Biological role

Although not recognized until the 1970s, nickel plays important roles in the biology of microorganisms and plants.[44] In fact,urease (an enzyme that assists in the hydrolysis of urea) contains nickel. The NiFe-hydrogenases contain nickel in addition toiron-sulfur clusters.HP Pavilion DV4T-1200 CTO Battery

Such [NiFe]-hydrogenases characteristically oxidise H2. A nickel-tetrapyrrole coenzyme, Cofactor F430, is present in the methyl coenzyme M reductase, which powers methanogenic archaea. One of the carbon monoxide dehydrogenase enzymes consists of an Fe-Ni-S cluster.HP Pavilion DV4T-1200SE CTO Battery

Other nickel-containing enzymes include a rare bacterial class of superoxide dismutase[46] and glyoxalase I enzymes in bacteria and several parasitic eukaryotic trypanosomal parasites  (this enzyme in higher organisms, including yeast and mammals, uses divalent zinc, Zn2+).HP Pavilion DV4T-1300 CTO Battery

Toxicity

Exposure to nickel metal and soluble compounds should not exceed 0.05 mg/cm³ in nickel equivalents per 40-hour work-week. Nickel sulfide fume and dust are believed to be carcinogenic, and various other nickel compounds may be as well.HP Pavilion DV4T-1300SE CTO Battery

Nickel carbonyl, [Ni(CO)4], is an extremely toxic gas. The toxicity of metal carbonyls is a function of both the toxicity of the metal as well as the carbonyl's ability to give off highly toxic carbon monoxide gas, and this one is no exception; nickel carbonyl is also explosive in air.HP Pavilion DV4T-1400 CTO Battery

Sensitized individuals may show an allergy to nickel, affecting their skin, also known as dermatitis. Sensitivity to nickel may also be present in patients with pompholyx. Nickel is an important cause of contact allergy, partly due to its use in jewellery intended for pierced ears.HP Pavilion DV4Z Battery

Nickel allergies affecting pierced ears are often marked by itchy, red skin. Many earrings are now made nickel-free due to this problem. The amount of nickel allowed in products that come into contact with human skin is regulated by the European Union. In 2002, researchers found amounts of nickel being emitted by 1 and 2 Euro coins far in excess of those standards.HP Pavilion DV4Z-1000 CTO Battery

This is believed to be due to a galvanic reaction.

It was voted Allergen of the Year in 2008 by the American Contact Dermatitis Society.HP Pavilion DV4Z-1100 CTO Battery

Reports also showed that both the nickel-induced activation of hypoxia-inducible factor (HIF-1) and the up-regulation of hypoxia-inducible genes are due to depleted intracellular ascorbate levels. HP Pavilion DV4Z-1200 CTO Battery

The addition of ascorbate to the culture medium increased the intracellular ascorbate level and reversed both the metal-induced stabilization of HIF-1- and HIF-1?-dependent gene expression.HP Pavilion DV4 Battery,HP Pavilion DV4-1000 Battery,HP Pavilion DV4-1000EA Battery,HP Pavilion DV4-1000ET Battery,HP Pavilion DV4-1001 Battery,HP Pavilion DV4-1001AX Battery,HP Pavilion DV4-1001TU Battery,HP Pavilion DV4-1001TX Battery

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Cobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.HP Pavilion DV4-1199EA Battery

Cobalt-based blue pigments have been used since ancient times for jewelry and paints, and to impart a distinctive blue tint to glass, but the color was later thought by alchemists to be due to the known metal bismuth. Miners had long used the namekobold ore(German for goblin ore) for some of the blue-pigment producing minerals;HP Pavilion DV4-1199EE Battery

they were named because they were poor in known metals and gave poisonous arsenic-containing fumes upon smelting. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named for the kobold.HP Pavilion DV4-1199EF Battery

Nowadays, some cobalt is produced specifically from various metallic-lustered ores, for example cobaltite (CoAsS), but the main source of the element is as a by-product of copper and nickel mining. The copper belt in the Democratic Republic of the Congo and Zambia yields most of the cobalt metal mined worldwide.HP Pavilion DV4-1199EO Battery

Cobalt is used in the preparation of magnetic, wear-resistant and high-strength alloys. Cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) give a distinctive deep blue color to glass, smalt, ceramics, inks, paints and varnishes. Cobalt occurs naturally as only one stable isotope, cobalt-59.HP Pavilion DV4-1199EP Battery

Cobalt-60 is a commercially important radioisotope, used as aradioactive tracer and in the production of gamma rays.

Cobalt is the active center of coenzymes called cobalamins, the most common example of which is vitamin B12. As such it is an essential trace dietary mineral for all animals. Cobalt in inorganic form is also an active nutrient for bacteria, algae andfungi.HP Pavilion DV4-1199ER Battery

Cobalt is a ferromagnetic metal with a specific gravity of 8.9. Pure cobalt is not found in nature, but compounds of cobalt are common. Small amounts of it are found in most rocks, soil, plants and animals. The Curie temperature is 1115 °C[4] and the magnetic moment is 1.6–1.7 Bohr magnetons per atom.HP Pavilion DV4-1199ES Battery

In nature, it is frequently associated with nickel, and both are characteristic minor components of meteoric iron. Cobalt has arelative permeability two thirds that of iron.Metallic cobalt occurs as twocrystallographic structures: hcp and fcc. The ideal transition temperature between the hcp and fcc structures is 450 °C, but in practice, the energy difference is so small that random intergrowth of the two is common.HP Pavilion DV4-1199ET Battery

Cobalt is a weakly reducing metal that is protected from oxidation by a passivating oxide film. It is attacked by halogens and sulfur. Heating in oxygen produces Co3O4 which loses oxygen at 900 °C to give the monoxide CoO.HP Pavilion DV4-1200 CTO Battery

Common oxidation states of cobalt include +2 and +3, although compounds with oxidation states ranging from ?3 to +4 are also known. A common oxidation state for simple compounds is +2. Cobalt(II) salts form the red-pink [Co(H2O)6]2+ complex in aqueous solution. Addition of chloride gives the intensely blue [CoCl4]2?.HP Pavilion DV4-1200 Battery

Oxygen and chalcogen compounds

Several oxides of cobalt are known. Green cobalt(II) oxide (CoO) has rocksalt structure. It is readily oxidized with water and oxygen to brown cobalt(III) hydroxide (Co(OH)3). At temperatures of 600–700 °C, CoO oxidizes to the blue cobalt(II,III) oxide (Co3O4), which has a spinel structure.HP Pavilion DV4-1201AU Battery

Black cobalt(III) oxide (Co2O3) is also known.[11] Cobalt oxides areantiferromagnetic at low temperature: CoO (Neel temperature 291 K) and CHP Pavilion DV4-1201TU Battery

The principal chalcogenides of cobalt include the black cobalt(II) sulfides, CoS2, which adopts a pyrite-like structure, andCo2S3. Pentlandite (Co9S8) is metal-rich.HP Pavilion DV4-1201TX Battery

Halides

The four dihalides of cobalt(II) are known: cobalt(II) fluoride (CoF2, pink), cobalt(II) chloride (CoCl2, blue), cobalt(II) bromide (CoBr2, green), cobalt(II) iodide (CoI2, blue-black). These halides exist as anhydrous and hydrates. Whereas the anhydrous dichloride is blue, the hydrate is red.HP Pavilion DV4-1202AU Battery

The reduction potential for the reaction

Co3+ + e? ? Co2+

is +1.92 V, beyond that for chlorine to chloride, +1.36 V. As a consequence cobalt(III) and chloride would result in the cobalt(III) being reduced to cobalt(II).HP Pavilion DV4-1202TU Battery

Because the reduction potential for fluorine to fluoride is so high, +2.87 V, cobalt(III) fluoride is one of the few simple stable cobalt(III) compounds. Cobalt(III) fluoride, which is used in some fluorination reactions, reacts vigorously with water.HP Pavilion DV4-1202TX Battery

Coordination compounds

As for all metals, molecular compounds of cobalt are classified as coordination complexes, that is molecules or ions that contain cobalt linked to several ligands. The principles of electronegativity and hardness–softness of a series of ligands can be used to explain the usual oxidation state of the cobalt.HP Pavilion DV4-1203AU Battery

For example Co+3 complexes tend to have ammine ligands. As phosphorus is softer than nitrogen, phosphine ligands tend to feature the softer Co2+ and Co+, an example being tris(triphenylphosphine)cobalt(I) chloride ((P(C6H5)3)3CoCl). The more electronegative (and harder) oxide and fluoride can stabilize Co4+ derivatives, e.g.HP Pavilion DV4-1203TU Battery

caesium hexafluorocobaltate (Cs2CoF6) and potassium percobaltate (K3CoO4).

Alfred Werner, a Nobel-prize winning pioneer in coordination chemistry, worked with compounds of empirical formulaCoCl3(NH3)6. One of the isomers determined was cobalt(III) hexammine chloride.HP Pavilion DV4-1203TX Battery

This coordination complex, a "typical" Werner-type complex, consists of a central cobalt atom coordinated by six ammine ligands orthogonal to each other and three chloridecounteranions. Using chelating ethylenediamine ligands in place of ammonia gives tris(ethylenediamine)cobalt(III) chloride([Co(en)3]Cl),HP Pavilion DV4-1204AU Battery

which was one of the first coordination complexes that was resolved into optical isomers. The complex exists as both either right- or left-handed forms of a "three-bladed propeller". This complex was first isolated by Werner as yellow-gold needle-like crystals.HP Pavilion DV4-1204TU Battery

Organometallic compounds

Cobaltocene is a structural analog to ferrocene, where cobalt substitutes for iron. Cobaltocene is sensitive to oxidation, much more than ferrocene. Cobalt carbonyl (Co2(CO)8) is a catalyst in carbonylation reactions. Vitamin B12 (see below) is an organometallic compound found in nature and is the only vitamin to contain a metal atom.HP Pavilion DV4-1204TX Battery

59Co is the only stable cobalt isotope and the only isotope to exist in nature. 22 radioisotopes have been characterized with the most stable being 60Co with a half-life of 5.2714 years, 57Co with a half-life of 271.79 days, 56Co with a half-life of 77.27 days, and 58Co with a half-life of 70.86 days.HP Pavilion DV4-1205AU Battery

All of the remainingradioactive isotopes have half-lives that are shorter than 18 hours, and the majority of these are shorter than 1 second. This element also has 4 meta states, all of which have half-lives shorter than 15 minutes.

The isotopes of cobalt range in atomic weight from 50 u (50Co) to 73 u (73Co).HP Pavilion DV4-1205TU Battery

The primary decay mode for isotopes with atomic mass unit values less than that of the most abundant stable isotope, 59Co, is electron capture and the primary mode of decay for those of greater than 59 atomic mass units is beta decay. The primary decay products before 59Co are element 26 (iron) isotopes and the primary products after are element 28 (nickel) isotopes.HP Pavilion DV4-1205TX Battery

Cobalt compounds have been used for centuries to impart a rich blue color to glass, glazes and ceramics. Cobalt has been detected in Egyptian sculpture and Persian jewelry from the third millennium BC, in the ruins of Pompeii (destroyed in 79 AD), and in China dating from the Tang dynasty (618–907 AD) and the Ming dynasty (1368–1644 AD).HP Pavilion DV4-1206TU Battery

Cobalt has been used to color glass since the Bronze Age. The excavation of the Uluburun shipwreck yielded an ingot of blue glass, which was cast during the 14th century BC. Blue glass items from Egypt are colored with copper, iron, or cobalt. The oldest cobalt-colored glass was from the time of the Eighteenth dynasty in Egypt (1550–1292 BC).HP Pavilion DV4-1206TX Battery

The location where the cobalt compounds were obtained is unknown.

The word cobalt is derived from the German kobalt, from kobold meaning "goblin", a superstitious term used for the ore of cobalt by miners. The first attempts at smelting these ores to produce metals such as copper or nickel failed, yielding simply powder (cobalt(II) oxide) instead.HP Pavilion DV4-1207TU Battery

Also, because the primary ores of cobalt always contain arsenic, smelting the ore oxidized the arsenic content into the highly toxic and volatile arsenic oxide, which also decreased the reputation of the ore for the miners.

Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt circa 1735, showing it to be a new previously unknown element different from bismuth and other traditional metals, and calling it a new "semi-metal."HP Pavilion DV4-1207TX Battery

He was able to show that compounds of cobalt metal were the source of the blue color in glass, which previously had been attributed to thebismuth found with cobalt. Cobalt became the first metal to be discovered since the pre-historical period, during which all the known metals (iron, copper, silver, gold, zinc, mercury, tin, lead and bismuth) had no recorded discoverers.HP Pavilion DV4-1208TU Battery

During the 19th century, a significant part of the world's production of cobalt blue (a dye made with cobalt compounds and alumina) and smalt (cobalt glass powdered for use for pigment purposes in ceramics and painting) was carried out at the Norwegian Blaafarveværket.HP Pavilion DV4-1208TX Battery

The first mines for the production of smalt in the 16th to 18th century were located in Norway, Sweden, Saxony and Hungary. With the discovery of cobalt ore in New Caledonia in 1864 the mining of cobalt in Europe declined. With the discovery of ore deposits in Ontario,HP Pavilion DV4-1209TU Battery

Canada in 1904 and the discovery of even larger deposits in the Katanga Province in the Congo in 1914 the mining operations shifted again. With the Shaba conflict starting in the 1978 the main source for cobalt the copper mines of Katanga Province nearly stopped their production.HP Pavilion DV4-1209TX Battery

The impact on the world cobalt economy from this conflict was smaller than expected, because industry established effective ways for recycling cobalt materials and in some cases was able to change to cobalt-free alternatives.

In 1938, John Livingood and Glenn T. Seaborg discovered cobalt-60. This isotope was famously used at Columbia University in the 1950s to establish parityviolation in radioactive beta decay.HP Pavilion DV4-1210EA Battery

Occurrence

The stable form of cobalt is created in supernovas via the r-process. It comprises 0.0029% of the Earth's crust and is one of the first transition metal series.

Cobalt occurs in copper and nickel minerals and in combination with sulfur and arsenic in the sulfidic cobaltite (CoAsS), safflorite (CoAs2) and skutterudite (CoAs3) minerals.HP Pavilion DV4-1210EF Battery

The mineral cattierite is similar to pyrite and occurs together with vaesite in the copper deposits of the Katanga Province.[37] Upon contact with the atmosphere, weathering occurs and the sulfide minerals oxidize to form pink erythrite ("cobalt glance": Co3(AsO4)2·8H2O) and sphaerocobaltite (CoCO3).HP Pavilion DV4-1210EO Battery

Cobalt is not found as a native metal but is mainly obtained as a by-product of nickel and copper mining activities. The main ores of cobalt are cobaltite,erythrite, glaucodot and skutterudite.HP Pavilion DV4-1210ER Battery

Production

In 2005, the copper deposits in the Katanga Province (former Shaba province) of the Democratic Republic of the Congo were the top producer of cobalt with almost 40% world share, reports theBritish Geological Survey.[42] The political situation in the Congo influences the price of cobalt significantly.HP Pavilion DV4-1210TU Battery

The Mukondo Mountain project, operated by the Central African Mining and Exploration Company in Katanga, may be the richest cobalt reserve in the world. It is estimated to be able to produce about one third of total global production of cobalt in 2008.HP Pavilion DV4-1210TX Battery

In July 2009 CAMEC announced a long term agreement under which CAMEC would deliver its entire annual production of cobalt in concentrate from Mukondo Mountain to Zhejiang Galico Cobalt & Nickel Materials of China.

Several methods exist for the separation of cobalt from copper and nickel. They depend on the concentration of cobalt and the exact composition of the used ore.HP Pavilion DV4-1211EA Battery

One separation step involves froth flotation, in which surfactants bind to different ore components, leading to an enrichment of cobalt ores. Subsequent roasting converts the ores to the cobalt sulfate, whereas the copper and the iron are oxidized to the oxide. The leaching with water extracts the sulfate together with the arsenates.HP Pavilion DV4-1211TU Battery

The residues are further leached with sulfuric acid yielding a solution of copper sulfate. Cobalt can also be leached from the slag of the copper smelter.

The products of the above-mentioned processes are transformed into the cobalt oxide (Co3O4). This oxide is reduced to the metal by the aluminothermic reaction or reduction with carbon in a blast furnace.HP Pavilion DV4-1211TX Battery

Applications

The main application of cobalt is as the metal in alloys.

Alloys

Cobalt-based superalloys consume most of the produced cobalt. The temperature stability of these alloys makes them suitable for use in turbine blades for gasturbines and jet aircraft engines, though nickel-based single crystal alloys surpass them in this regard.HP Pavilion DV4-1212LA Battery

Cobalt-based alloys are also corrosion and wear-resistant. This makes them useful in the medical field, where cobalt is often used (along with titanium) for orthopedic implants that do not wear down over time. The development of the wear-resistant cobalt alloys started in the first decade of the 19th century with the stellite alloys, which are cobalt-chromium alloys with varying tungsten and carbon content.HP Pavilion DV4-1212TU Battery

The formation of chromium and tungsten carbides makes them very hard and wear resistant.[48] Special cobalt-chromium-molybdenumalloys like Vitallium are used for prosthetic parts such as hip and knee replacements.[49] Cobalt alloys are also used for dental prosthetics, where they are useful to avoid allergies to nickel.HP Pavilion DV4-1212TX Battery

Some high speed steels also use cobalt to increase heat and wear-resistance. The special alloys of aluminium, nickel, cobalt and iron, known as Alnico, and of samarium and cobalt (samarium-cobalt magnet) are used in permanent magnets. It is also alloyed with 95% platinum for jewelry purposes, yielding an alloy that is suitable for fine detailed casting and is also slightly magnetic.HP Pavilion DV4-1213LA Battery

Batteries

Lithium cobalt oxide (LiCoO2) is widely used in lithium ion battery cathodes. The material is composed of cobalt oxide layers in which the lithium is intercalated. During discharging the lithium intercalated between the layers is set free as lithium ion.HP Pavilion DV4-1213TU Battery

Nickel-cadmium  (NiCd) and nickel metal hydride (NiMH) batteries also contain significant amounts of cobalt; the cobalt improves the oxidation capabilities of nickel in the battery.

Catalysis

Several cobalt compounds are used in chemical reactions as oxidation catalysts.HP Pavilion DV4-1213TX Battery

Cobalt acetate is used for the conversion of xylene to terephthalic acid, the precursor to the bulk polymer polyethylene terephthalate. Typical catalysts are the cobalt carboxylates (known as cobalt soaps). They are also used in paints, varnishes, and inks as "drying agents" through the oxidation of drying oils.HP Pavilion DV4-1214LA Battery

The same carboxylates are used to improve the adhesion of the steel to rubber in steel-belted radial tires.

Cobalt-based catalysts are also important in reactions involving carbon monoxide. Steam reforming, useful in hydrogen production, uses cobalt oxide-base catalysts.HP Pavilion DV4-1214TU Battery

Cobalt is also a catalyst in the Fischer-Tropsch process, used in the hydrogenation of carbon monoxide into liquid fuels. The hydroformylation of alkenes often rely on cobalt octacarbonyl as the catalyst, although such processes have been partially displaced by more efficient iridium- and rhodium-based catalysts, e.g. the Cativa process.HP Pavilion DV4-1214TX Battery

The hydrodesulfurization of petroleum uses a catalyst derived from cobalt and molybdenum. This process helps to rid petroleum of sulfur impurities that interfere with the refining of liquid fuels.

Pigments and coloring

Before the 19th century, the predominant use of cobalt was as pigment. Since the Middle Ages, it has been involved in the production of smalt, a blue colored glass.HP Pavilion DV4-1215EF Battery

Smalt is produced by melting a mixture of the roasted mineralsmaltite, quartz and potassium carbonate, yielding a dark blue silicate glass which is ground after the production. Smalt was widely used for the coloration of glass and as pigment for paintings. In 1780, Sven Rinman discovered cobalt green and in 1802 Louis Jacques Thénard discovered cobalt blue.HP Pavilion DV4-1215TU Battery

The two varieties of cobalt blue, cobalt aluminate and cobalt green (a mixture of cobalt(II) oxide and zinc oxide), were used as pigments for paintings because of their superior stability.

Radioisotopes

Cobalt-60 (Co-60 or 60Co) is useful as a gamma ray source because it can be produced in predictable quantity and high activity by bombarding cobalt with neutrons.HP Pavilion DV4-1215TX Battery

It produces two gamma rays with energies of 1.17 and 1.33 MeV.

Its uses include external beam radiotherapy, sterilization of medical supplies and medical waste, radiation treatment of foods for sterilization (cold pasteurization), industrial radiography (e.g. weld integrity radiographs), density measurements (e.g. concrete density measurements), and tank fill height switches.HP Pavilion DV4-1216TU Battery

The metal has the unfortunate habit of producing a fine dust, causing problems withradiation protection. Cobalt from radiotherapy machines has been a serious hazard when not disposed of properly, and one of the worst radiation contamination accidents in North America occurred in 1984,HP Pavilion DV4-1216TX Battery

after a discarded radiotherapy unit containing cobalt-60 was mistakenly disassembled in a junkyard in Juarez, Mexico.

Cobalt-60 has a radioactive half-life of 5.27 years. This decrease in activity requires periodic replacement of the sources used in radiotherapy and is one reason why cobalt machines have been largely replaced by linear accelerators in modern radiation therapy.HP Pavilion DV4-1217LA Battery

Cobalt-57 (Co-57 or 57Co) is a cobalt radioisotope most often used in medical tests, as a radiolabel for vitamin B12 uptake, and for the Schilling test. Cobalt-57 is used as a source in Mössbauer spectroscopy and is one of several possible sources in X-ray fluorescence devices.HP Pavilion DV4-1217TX Battery

Nuclear weapon designs could intentionally incorporate 59Co, some of which would be activated in a nuclear explosion to produce 60Co. The 60Co, dispersed as nuclear fallout, creates what is sometimes called a cobalt bomb.HP Pavilion DV4-1218TX Battery

Other uses

Other uses of cobalt are in electroplating, owing to its attractive appearance, hardness and resistance to oxidation, and as ground coats for porcelainenamels.

Biological role

Cobalt is essential to all animals, including humans. It is a key constituent of cobalamin, also known as vitamin B12, which is the primary biological reservoir of cobalt as an "ultratrace" element.HP Pavilion DV4-1219TX Battery

Bacteria in the guts of ruminant animals convert cobalt salts into vitamin B12, a compound which can only be produced by bacteria. The minimum presence of cobalt in soils therefore markedly improves the health of grazing animals, and an uptake of 0.20 mg/kg a day is recommended.HP Pavilion DV4-1220BR Battery

Non-ruminant herbivores produce vitamin B12 from bacteria in their colons, from which the vitamin cannot be absorbed, and thus some of them ingest feces to obtain the nutrient. Animals that do not follow these methods of getting vitamin B12 from their own gastrointestinal bacteria must obtain the vitamin from animal products in their diet,HP Pavilion DV4-1220TX Battery

and they cannot benefit from ingesting simple cobalt salts.

The cobalamin-based proteins use corrin to hold the cobalt. Coenzyme B12 features a reactive C-Co bond, which participates in its reactions.HP Pavilion DV4-1220US Battery

In humans, B12 exists with two types of alkyl ligand: methyl and adenosyl. MeB12 promotes methyl (-CH3) group transfers. The adenosyl version of B12 catalyzes rearrangements in which a hydrogen atom is directly transferred between two adjacent atoms with concomitant exchange of the second substituent,HP Pavilion DV4-1221TX Battery

X, which may be a carbon atom with substituents, an oxygen atom of an alcohol, or an amine. Methylmalonyl coenzyme A mutase (MUT) converts MMl-CoA to Su-CoA, an important step in the extraction of energy from proteins and fats.

Although far less common than other metalloproteins (e.g. those of zinc and iron), cobaltoproteins are known aside from B12.HP Pavilion DV4-1222LA Battery

These proteins include methionine aminopeptidase 2 an enzyme that occurs in humans and other mammals which does not use the corrin ring of B12, but binds cobalt directly. Another non-corrin cobalt enzyme is nitrile hydratase, an enzyme in bacteria that are able to metabolizenitriles.HP Pavilion DV4-1222NR Battery

Precautions

Cobalt is an essential element for life in minute amounts. The LD50 value for soluble cobalt salts has been estimated to be between 150 and 500 mg/kg. Thus, for a 100 kg person the LD50 would be about 20 grams.HP Pavilion DV4-1222TX Battery

After nickel and chromium, cobalt is a major cause of contact dermatitis. In 1966, the addition of cobalt compounds to stabilize beer foam in Canada led tocardiomyopathy, which came to be known as beer drinker's cardiomyopathy.HP Pavilion DV4-1223LA Battery

Recovery from copper-cobalt sulfide concentrates

The ores are treated by a sulfatizing roast in a fluidized bed furnace to convert copper and cobalt sulfides into soluble oxides andiron into insoluble hematite. The calcine is subsequently leached with sulfuric acid from the spent copper recovery electrolyte. Oxide concentrates are introduced at this leaching step to maintain the acid balance in the circuit.HP Pavilion DV4-1223TX Battery

Iron and aluminum are removed from the leach solution by the addition of lime, and copper iselectrowon on copper cathodes. A part of the spent electrolyte enters the cobalt recovery circuit and is purified by the removal of iron, copper, nickel, and zincprior to the precipitation of cobalt as its hydroxide.HP Pavilion DV4-1224LA Battery

This is accomplished by the addition of more lime to raise the pH until the remaining copper precipitates. This copper is sent back to the copper circuit. As more lime is then added, a copper-cobaltite precipitates and is fed back to the leaching process.HP Pavilion DV4-1224TX Battery

Sodium hydrosulfide (NaHS) is added (along with some metallic cobalt as a catalyst) to precipitate nickel sulfide (NiS). Hydrogen sulfide (H2S) and sodium carbonate(Na2CO3) are then added to precipitate zinc sulfide (ZnS). Lime is then added to saturation to precipitate cobalt(II) hydroxide (Co(OH)2).HP Pavilion DV4-1225DX Battery

In the final stages, this cobalt hydroxide is redissolved and the metal is refined by electrolysis. The resulting cobalt cathodes are crushed and vacuum degassed to obtain a pure cobalt metal.

Recovery from nickel-cobalt sulfide concentrates (Sherritt process)

The Sherritt process is a hydrometallurgical process named for Sherritt Gordon Mines Ltd.HP Pavilion DV4-1225EE Battery

(now Sherritt International) of Sherridon and Lynn Lake Manitoba Canada, based on the older Forward process developed by Dr. Frank Forward for the recovery of copper and nickel form those same mines. Nickel sulfide concentrates can be treated by either roasting or flash smelting to produce matte from which nickel and cobalt can be recovered hydrometallurgically,HP Pavilion DV4-1225LA Battery

or they may be treated by anammonia solution pressure leach. The residue is removed. A feed of matte and sulfide concentrate containing approximately 0.4% cobalt and 30% sulfur is pressure leached at elevated temperature and pressure in an ammoniacal solution to produce a solution of nickel, copper and cobalt.HP Pavilion DV4-1225TX Battery

By boiling away the ammonia; copper is precipitated as a sulfide and sent to a smelter. Hydrogen sulfide is added to the autoclave to remove nickel sulfide and copper sulfide which is fed back to the leaching process. Air is then passed through the solution in the autoclave for oxyhydrolysis.HP Pavilion DV4-1226TX Battery

The solution is then reduced with hydrogen, again at high temperature and pressure, to precipitate nickel powder (>99%). The remaining solution (containing approximately equal proportions of nickel and cobalt sulfides), is then adjusted (to a lower temperature and pressure) to precipitate the mixed sulfides and the fluid is concentrated and crystallized into ammonium sulfate ((NH4)2SO4).HP Pavilion DV4-1227LA Battery

The mixed sulfides are pressure leached with air and sulfuric acid. Ammonia is then added to remove potassium and iron as jarosite (KFe3+3 (OH)6(SO4)2). More ammonia and air is added for oxidation. The solution is removed from the autoclave and sulfuric acid added to remove nickel as nickel(II) sulfate-ammonium sulfatehexahydrate?HP Pavilion DV4-1227TX Battery

((NiSO4)•((NH4)2SO4)•6H2O) which is then sent to have its nickel recovered. The solution is then further reduced with more sulfuric acid and cobalt metal powder is added to aid in the nucleation of precipitants (seeding). Addition of hydrogen gas to saturation precipitates cobalt powder with a purity of approximately 99.6%.HP Pavilion DV4-1227US Battery

Recovery from copper-cobalt oxide concentrates

The ore is comminuted and the cobalt rich oxides are separated by froth flotation. The cobalt-bearing concentrate is then mixed with lime and coal, and then meltedin a reducing atmosphere. Iron and lighter impurities float to the surface as solid dross or are expelled from the melt as gas.HP Pavilion DV4-1228CA Battery

The remaining liquid is composed of a heavier copper smelt containing approximately 5% cobalt that is processed for its copper and a lighter slag that is approximately 40% cobalt that is further refined by hydrometallurgical and electrolytic processing. Concentrations of cobalt oxide (Co3O4) may also be reduced by the aluminothermic reaction or with carbon in ablast furnace.HP Pavilion DV4-1228LA Battery

Recovery from laterite ores

Nickel-cobalt lateritic ores can be treated by either hydrometallurgical processes or pyrometallurgical processes, such as matte or ferronickel smelting, which require the entire ore to be melted and the metal values to be separated from the residual components of the ore. The hydrometallurgical process for laterite ore can use sulfuric acid or ammonia leach solutions.HP Pavilion DV4-1228TX Battery

Recovery from arsenide ores

Arsenic containing concentrates are roasted in a fluidized bed to remove 60% to 70% of the arsenic present as arsenic oxide (As2O5).HP Pavilion DV4-1229LA Battery

The roasted ores can be treated with hydrochloric acid and chlorine or with sulfuric acid to give a leach solution that can be purified by hydrometallurgical methods and from which cobalt can be recovered by electro refining or by carbonate precipitation.HP Pavilion DV4-1229TX Battery

If hydrochloric acid is used then cobalt may be extracted using alamine 336 in meta-xylene.Cobalt can be extracted also using Cyanex 272 {bis-(2,4,4-trimethylpentyl) phosphinic acid}. When Cobalt carbonate (CoCO3) is heated (calcined) above 400 °C it decomposes into carbon dioxide (CO2) and Cobalt(II) oxide (CoO) and can be refined as an oxide concentrate (see above).HP Pavilion DV4-1230BR Battery

Electro refining

If purifying by electrolysis, an aqueous sulfate solution at 50° to 70°C is usually used with a lead anode (corrosion products from which will not contaminate the cobalt oxy-hydroxide (CoOOH) electrolyte solution) and a stainless steel cathode which will allow for the easy removal of the deposited cobalt.HP Pavilion DV4-1230TX Battery

Electro refining in a chloride or sulfate medium at -0.3 V will make a cathode coating of 99.98% Cobalt.

Extractive metallurgy is the study of the processes used in the separation and concentration (benefaction) of raw materials.HP Pavilion DV4-1231TX Battery

The field is an applied science, covering all aspects of the physical and chemical processes used to produce mineral-containing and metallic materials, sometimes for direct use as a finished product, but more often in a form that requires further physical processing which is generally the subject of physical metallurgy, ceramics, and other disciplines within the broad field of materials science.HP Pavilion DV4-1232TX Battery

The field of extractive metallurgy encompasses many specialty sub-disciplines, each concerned with various physical and chemical processes that are steps in an overall process of producing a particular material. These specialties are generically grouped into the categories of mineral processing, hydrometallurgy,pyrometallurgy, and electrometallurgy.HP Pavilion DV4-1233TX Battery

The distinctions among these groups of sub-disciplines within extractive metallurgy is far from clear, and many commercially important metallurgical processes involve considerable overlap.

The theoretical basis of extractive metallurgy is underpinned by the more general sciences of physics, chemistry, and geology.HP Pavilion DV4-1234TX Battery

Additionally, the practice of extractive metallurgy nearly always involves contributions from other scientific fields such as analytical chemistry and mineralogy.

Mineral processing

Mineral processing involves the processes used to manipulate the particle size of solid raw materials and to separate valuable materials from materials of no value, referred to as gangue.HP Pavilion DV4-1235EE Battery

Usually, particle size reduction, also referred to as comminution, is required to permit efficient separation of the valuable materials from gangue. Separation processes take advantage of physical properties of the materials in order to separate them from each other.HP Pavilion DV4-1235EI Battery

These physical properties can include density, particle size and shape, electrical and magnetic properties, and surface properties. Since many size reduction and separation processes involve the use of water, solid-liquid separation processes are also a subject of mineral processing.HP Pavilion DV4-1235TX Battery

Hydrometallurgy

Hydrometallurgy is concerned with processes involving aqueous solutions to extract metals from ores. The most common hydrometallurgical process is leaching, which involves dissolution of the valuable metals into the aqueous solution.HP Pavilion DV4-1236TX Battery

After the solution is separated from the ore solids, the solution is often subjected to various processes of purification and concentration before the valuable metal is recovered either in its metallic state or as a chemical compound. The solution purification and concentration processes may include precipitation, distillation, adsorption, and solvent extraction.HP Pavilion DV4-1237TX Battery

The final recovery step may involve precipitation, cementation, or an electrometallurgical process. Sometimes, hydrometallurgical processes may be carried out directly on the ore material without any pretreatment steps. More often, the ore must be pretreated by various mineral processing steps, and sometimes by pyrometallurgical processes.HP Pavilion DV4-1238TX Battery

Pyrometallurgy

Pyrometallurgy involves high temperature processes where chemical reactions take place among gases, solids, and molten materials. Solids containing valuable metals are reacted to form intermediate compounds for further processing or converted into their elemental or metallic state.HP Pavilion DV4-1239TX Battery

Pyrometallurgical processes that involve gases and solids are typified by calcining and roastingoperations. Processes that produce molten products are collectively referred to as smelting operations. The energy required to sustain the high temperature pyrometallurgical processes may come entirely from the exothermic nature of the chemical reactions taking place,HP Pavilion DV4-1240TX Battery

usually oxidation reactions. Often, however, energy must be added to the process by combustion of fuel or, in the case of some smelting processes, by the direct application of electrical energy.

Ellingham Diagrams are a useful way of analysing the possible reactions, and so predicting their outcome.HP Pavilion DV4-1241TX Battery

Electrometallurgy

Electrometallurgy involves metallurgical processes that take place in some form of electrolytic cell. The most common types of electrometallurgical processes are electrowinning and electro-refining. Electrowinning is an electrolysis process used to recover metals in aqueous solution, usually as the result of an ore having undergone one or more hydrometallurgical processes.HP Pavilion DV4-1242TX Battery

The metal of interest is plated onto the cathode, while the anode is an inert electrical conductor. Electro-refining is used to dissolve an impure metallic anode (typically from a smelting process) and produce a high purity cathode. Fused salt electrolysis is another electrometallurgical process whereby the valuable metal has been dissolved into a molten salt which acts as the electrolyte,HP Pavilion DV4-1243TX Battery

and the valuable metal collects on the cathode of the cell. The fused salt electrolysis process is conducted at temperatures sufficient to keep both the electrolyte and the metal being produced in the molten state. The scope of electrometallurgy has significant overlap with the areas of hydrometallurgy and (in the case of fused salt electrolysis) pyrometallurgy.HP Pavilion DV4-1244TX Battery

Additionally, electrochemical phenomena play a considerable role in many mineral processing and hydrometallurgical processes.

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, theirintermetallic compounds, and their mixtures, which are called alloys. HP Pavilion DV4-1245BR Battery

It is also the technology of metals: the way in which science is applied to their practical use. Metallurgy is distinguished from the craft of metalworking.

Etymology and pronunciation

The word was originally (1593) an alchemist's term for the extraction of metals from minerals: the ending -urgy signifying a process, especially manufacturing: it was in this sense it was used by the 1797 Encyclopaedia Britannica.HP Pavilion DV4-1245TX Battery

In the late 19th century it was extended to the more general scientific study of metals and alloys and related processes. The roots are borrowed from Ancient Greek: ????????????, matallourgos, "worker in metal", from ????????, metallon, "metal" + ?????, ergon, "work". In English, the /me?tæl?d?i/ pronunciation is the more common one in the UK and Commonwealth.HP Pavilion DV4-1246TX Battery

The /?met?l?rd?i/ pronunciation is the more common one in the USA, and is the first-listed variant in various American dictionaries (e.g., Merriam-Webster Collegiate, American Heritage).

The first evidence of human metallurgy dates from the 5th and 6th millennium BC, and was found in the archaeological sites ofMajdanpek, Yarmovac and Plocnik all three in Serbia.HP Pavilion DV4-1247TX Battery

To date, the earliest copper smelting is found at the Belovode site,[2] these examples include a copper axe from 5,500BC belonging to the Vin?a culture.[3] Other signs of human metallurgy are found from the third millennium BC in places like Palmela (Portugal), Cortes de Navarra (Spain), and Stonehenge (United Kingdom).HP Pavilion DV4-1248TX Battery

However, as often happens with the study of prehistoric times, the ultimate beginnings cannot be clearly defined and new discoveries are continuous and ongoing.

Silver, copper, tin and meteoric iron can also be found native, allowing a limited amount of metalworking in early cultures.HP Pavilion DV4-1249TX Battery

Egyptian weapons made from meteoric iron in about 3000 B.C. were highly prized as "Daggers from Heaven".[4] However, by learning to get copper and tin by heating rocks and combining those two metals to make an alloy called bronze, the technology of metallurgy began about 3500 B.C. with the Bronze Age.HP Pavilion DV4-1250TX Battery

The extraction of iron from its ore into a workable metal is much more difficult. It appears to have been invented by theHittites in about 1200 B.C., beginning the Iron Age. The secret of extracting and working iron was a key factor in the success of the Philistines.HP Pavilion DV4-1251TX Battery

Historical developments in ferrous metallurgy can be found in a wide variety of past cultures and civilizations. This includes the ancient and medieval kingdoms and empires of the Middle East and Near East, ancient Iran, ancient Egypt, ancient Nubia, andAnatolia (Turkey),HP Pavilion DV4-1252TX Battery

Ancient Nok, Carthage, the Greeks and Romans of ancient Europe, medieval Europe, ancient and medieval China, ancient and medieval India, ancient and medieval Japan, amongst others. Many applications, practices, and devices associated or involved in metallurgy were established in ancient China,HP Pavilion DV4-1253TX Battery

such as the innovation of the blast furnace, cast iron, hydraulic-powered trip hammers, and double acting piston bellows.

A 16th century book by Georg Agricola called De re metallica describes the highly developed and complex processes of mining metal ores, metal extraction and metallurgy of the time. Agricola has been described as the "father of metallurgy".HP Pavilion DV4-1254TX Battery

Extraction

Extractive metallurgy is the practice of removing valuable metals from an ore and refining the extracted raw metals into a purer form. In order to convert a metal oxide or sulfide to a purer metal, the ore must be reduced physically, chemically, orelectrolytically.HP Pavilion DV4-1255TX Battery

Extractive metallurgists are interested in three primary streams: feed, concentrate (valuable metal oxide/sulfide), and tailings(waste). After mining, large pieces of the ore feed are broken through crushing and/or grinding in order to obtain particles small enough where each particle is either mostly valuable or mostly waste.HP Pavilion DV4-1256TX Battery

Concentrating the particles of value in a form supporting separation enables the desired metal to be removed from waste products.

Mining may not be necessary if the ore body and physical environment are conducive to leaching. Leaching dissolves minerals in an ore body and results in an enriched solution. The solution is collected and processed to extract valuable metals.HP Pavilion DV4-1257TX Battery

Ore bodies often contain more than one valuable metal. Tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal. That concentrate would then be processed to separate the valuable metals into individual constituents.HP Pavilion DV4-1258TX Battery

Alloys

Common engineering metals include aluminium, chromium, copper, iron, magnesium, nickel, titanium and zinc. These are most often used as alloys. Much effort has been placed on understanding the iron-carbon alloy system, which includes steels and cast irons.HP Pavilion DV4-1259TX Battery

Plain carbon steels are used in low cost, high strength applications where weight and corrosion are not a problem. Cast irons, including ductile iron are also part of the iron-carbon system.

Stainless steel or galvanized steel are used where resistance to corrosion is important. Aluminium alloys and magnesium alloys are used for applications where strength an

d lightness are required.HP Pavilion DV4-1260TX Battery

Copper-nickel alloys (such as Monel) are used in highly corrosive environments and for non-magnetic applications. Nickel-basedsuperalloys like Inconel are used in high temperature applications such as turbochargers, pressure vessel, and heat exchangers. For extremely high temperatures, single crystal alloys are used to minimize creep.HP Pavilion DV4-1265DX Battery

Production

In production engineering, metallurgy is concerned with the production of metallic components for use in consumer or engineering products. This involves the production of alloys, the shaping, the heat treatment and the surface treatment of the product.HP Pavilion DV4-1272CM Battery

The task of the metallurgist is to achieve balance between material properties such as cost, weight, strength, toughness, hardness, corrosion, fatigue resistance, and performance in temperature extremes. To achieve this goal, the operating environment must be carefully considered.HP Pavilion DV4-1275MX Battery

In a saltwater environment, ferrous metals and some aluminium alloys corrode quickly. Metals exposed to cold orcryogenic conditions may endure a ductile to brittle transition and lose their toughness, becoming more brittle and prone to cracking. Metals under continual cyclic loading can suffer from metal fatigue.HP Pavilion DV4-1280US Battery

Metals under constant stress at elevated temperatures can creep.

Cold working processes, where the product’s shape is altered by rolling, fabrication or other processes while the product is cold, can increase the strength of the product by a process called work hardening. Work hardening creates microscopic defects in the metal, which resist further changes of shape.HP Pavilion DV4-1281US Battery

Various forms of casting exist in industry and academia. These include sand casting, investment casting (also called the “lost wax process”), die casting andcontinuous casting.

Heat treatment

Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion.HP Pavilion DV4-1282CM Battery

Common heat treatment processes includeannealing, precipitation strengthening, quenching, and tempering . The annealingprocess softens the metal by heating it and then allowing it to cool very slowly, which gets rid of stresses in the metal and makes the grain structure large and soft-edged so that when the metal is hit or stressed it dents or perhaps bends, rather than breaking;HP Pavilion DV4-1283CL Battery

it is also easier to sand, grind, or cut annealed metal. Quenching is the process of cooling a high-carbon steel very quickly after you have heated it, thus "freezing" the steel's molecules in the very hard martensite form, which makes the metal harder. There is a balance between hardness and toughness in any steel,HP Pavilion DV4-1287CL Battery

where the harder it is, the less tough or impact-resistant it is, and the more impact-resistant it is, the less hard it is. Temperingrelieves stresses in the metal that were caused by the hardening process; tempering makes the metal less hard while making it better able to sustain impacts without breaking.HP Pavilion DV4-1290BR Battery

Often, mechanical and thermal treatments are combined in what is known as thermo-mechanical treatments for better properties and more efficient processing of materials. These processes are common to high alloy special steels, super alloys and titanium alloys.HP Pavilion DV4-1290EL Battery

Plating

Metallurgists study the microscopic and macroscopic properties using metallography, a technique invented by Henry Clifton Sorby. In metallography, an alloy of interest is ground flat and polished to a mirror finish. The sample can then be etched to reveal the microstructure and macrostructure of the metal.HP Pavilion DV4-1292CM Battery

The sample is then examined in an optical or electron microscope, and the image contrast provides details on the composition, mechanical properties, and processing history.

Crystallography, often using diffraction of x-rays or electrons, is another valuable tool available to the modern metallurgist.HP Pavilion DV4-1299EE Battery

Crystallography allows identification of unknown materials and reveals the crystal structure of the sample. Quantitative crystallography can be used to calculate the amount of phases present as well as the degree of strain to which a sample has been

Smelting is a form of extractive metallurgy; its main use is to produce a metal from its ore.HP Pavilion DV4-1300 CTO Battery

This includes iron extraction fromiron ore, and copper extraction and other base metals from their ores. Smelting uses heat and a chemical reducing agent to change the oxidation state of the metal ore; the reducing agent is commonly a source of carbon such as coke, or in earlier timescharcoal.HP Pavilion DV4-1301TU Battery

The carbon or carbon monoxide derived from it removes oxygen from the ore to leave the metal. The carbon is thus oxidized in two stages, producing first carbon monoxide and then carbon dioxide. As most ores are impure, it is often necessary to use flux, such as limestone, to remove the accompanying rock gangue as slag.HP Pavilion DV4-1301TX Battery

Plants for the electrolytic reduction of aluminium are also generally referred to as smelters. These do not melt aluminum oxide but instead dissolve it in aluminum fluoride. They normally use carbon electrodes, and conversion of carbon to carbon dioxide provides an important part of deoxydation energy,HP Pavilion DV4-1302TU Battery

rest of energy being provided by electricity, but novel smelter designs use electrodes that are not consumed in the process. The end product is molten aluminum.

Smelting involves more than just "melting the metal out of its ore".HP Pavilion DV4-1302TX Battery

Most ores are a chemical compound of the metal with other elements, such as oxygen (as anoxide), sulfur (as a sulfide) or carbon and oxygen together (as a carbonate). To produce the metal, these compounds have to undergo a chemical reaction. Smelting therefore consists of using suitable reducing substances that will combine with those oxidizing elements to free the metal.HP Pavilion DV4-1303TU Battery

Roasting

In the case of carbonates and sulfides, a process called "roasting" drives off the unwanted carbon or sulfur, leaving an oxide, which can be directly reduced. Roasting is usually carried out in an oxidizing environment. A few practical examples:HP Pavilion DV4-1303TX Battery

  • Malachite, a common ore of copper, is primarily copper carbonate (CuCO3). This mineral undergoes thermal decomposition to CuO and CO2 in several stages between 250°C and 350°C. The carbon dioxide is expelled into the atmosphere, leaving copper oxide which can be directly reduced to copper as shown below.HP Pavilion DV4-1304TU Battery
  • Galena, the most common mineral of lead, is primarily lead sulfide (PbS). The sulfide is oxidized to a sulfite (PbSO3) which thermally decomposes into lead oxide and sulfur dioxide gas. (PbO and SO2) The sulfur dioxide (like the carbon dioxide in the example above) is expelled, and the lead oxide is reduced as below.HP Pavilion DV4-1304TX Battery

Reduction

Reduction is the final, high-temperature step in smelting. It is here that the oxide becomes the elemental metal. A reducing environment, (often provided by carbon monoxide in an air-starved furnace) pulls the final oxygen atoms from the raw metal.HP Pavilion DV4-1305TU Battery

The required temperature varies over a very large range, both in absolute terms, and in terms of the melting point of the base metal. A few examples:

  • iron oxide becomes metallic iron at roughly 1250°C, almost 300 degrees below iron's melting point of 1538°C
  • mercuric oxide becomes vaporous mercury near 550°C, almost 600 degrees above mercury's melting point of -38°CHP Pavilion DV4-1305TX Battery

Fluxes

Fluxes are used in smelting for several purposes, chief among them catalyzing the desired reactions and chemically binding to unwanted impurities or reaction products. Calcium oxide, in the form of lime, was often used for this purpose, since it could react with the carbon dioxide sulfur dioxide produced during roasting and smelting to keep them out of the working environment.HP Pavilion DV4-1306TU Battery

Historically, the first smelting processes used carbon (in the form of charcoal) to reduce the oxides of tin (cassiterite, SnO2), copper (cuprite, CuO) and lead (Lead(II) oxide, PbO), and eventually iron (hematite, Fe2O3) In all these reactions the reducing agent was actually carbon monoxide, as the charcoal and oxides remained solid and therefore could not react directly with each other.HP Pavilion DV4-1306TX Battery

For copper and lead, important ores were actually the sulfides, chalcocite (CuS2) and galena (PbS); these first had to be converted to oxides by roasting them in air.

Silver was generally found in the form of sulfides mixed with galena; it was smelted together with lead and was afterwards separated from it by cupellation.HP Pavilion DV4-1307TU Battery

The primary source of mercury was the sulfide ore (cinnabar, HgS). This was roasted to produce the oxide HgO, which decomposed into oxygen and mercury, which both left the furnace as a (highly toxic) vapor, that was condensed in appropriate containers.

In the Old World, humans learned to smelt metals in prehistoric times, more than 8000 years ago.HP Pavilion DV4-1307TX Battery

The discovery and use of the "useful" metals — copper and bronze at first, then iron a few millennia later — had an enormous impact on human society. The impact was so pervasive that scholars traditionally divide ancient history into Stone Age, Bronze Age, and Iron Age.HP Pavilion DV4-1308TU Battery

In the Americas, pre-Inca civilizations of the central Andes in Peru had mastered the smelting of copper and silver at least six centuries before the first Europeans arrived in the 16th century.

Tin and lead

In the Old World, the first metals smelted were tin and lead. The earliest known cast lead beads were found in the Çatal Höyük site in Anatolia (Turkey), and dated from about 6500 BC, but the metal may have been known earlier.HP Pavilion DV4-1308TX Battery

Since the discovery happened several millennia before the invention of writing, we have no evidence about how it was made. However, tin and lead can be smelted by placing the ores in a wood fire, so it is possible that the discovery may have occurred by accident.HP Pavilion DV4-1309TU Battery

Although lead is a common metal, its discovery had relatively little impact in the ancient world. It is too soft to be used for weapons (except possibly as slingprojectiles) or for structural elements. However, being easy to cast and shape, it came to be extensively used in the classical world of Ancient Greece and Ancient Rome for piping and storage of water.HP Pavilion DV4-1309TX Battery

It was also used as a mortar in stone buildings, and as a writing material for commemorative plaques and curses.

Tin was much less common than lead and is only marginally harder, and had even less impact by itself.

Copper and bronze

After tin and lead, the next metal to be smelted appears to have been copper. How the discovery came about is a matter of much debate.HP Pavilion DV4-1310TU Battery

Campfires are about 200 °C short of the temperature needed for that, so it has been conjectured that the first smelting of copper may have been achieved in pottery kilns. The earliest known instances in Europe and the Near East were found in Iran, dated about 6000 BC.HP Pavilion DV4-1310TX Battery

The first smelted copper artifact was thought to be a mace head found in Can Hasan, Turkey and dated to 5000 BC. However, this now appears to be hammered native copper. The earliest current evidence of copper smelting, dating from between 5500 BC and 5000 BC, has been found in Plo?nik and Belovode, Serbia.HP Pavilion DV4-1311TU Battery

The development of copper smelting in the Andes, which is believed to have occurred independently of that in the Old World, may have occurred in the same way.

By combining copper with tin and/or arsenic in the right proportions one obtains bronze, an alloy which is significantly harder than copper.HP Pavilion DV4-1311TX Battery

The first copper/arsenic bronzes date of 4200 BC from Asia Minor. The Inca bronze alloys were also of this type. Arsenic is often an impurity in copper ores, so the discovery could have been made by accident; but eventually arsenic-bearing minerals were intentionally added during smelting.HP Pavilion DV4-1312TU Battery

Copper/tin bronzes, harder and more durable, were developed around 1500 BC or 3200 BC,also in Asia Minor.

The discovery of copper smelting and bronze manufacture had a significant impact on the history of the Old World.HP Pavilion DV4-1312TX Battery

The metal was hard enough to make weapons that were heavier, stronger, and more resistant to impact-related damage than their wood, bone, or stone equivalents. For several millennia, bronze was the material of choice for weapons such as swords, daggers, battle axes, and spear and arrow points, as well as protective gear such as shields, helmets, shin guards, and other body armor.HP Pavilion DV4-1313DX Battery

Bronze also supplanted stone, wood, and organic materials in all sorts of tools and household utensils, such as chisels, saws, adzes, nails, blade shears, knives,sewing needles and pins, jugs, cooking pots and cauldrons, mirrors, horse harnesses, and much more.HP Pavilion DV4-1313TU Battery

In turn, bronze tools brought about an increase in the quantity, quality, and complexity of manufactured products, from buildings to leather goods. Tin and copper also contributed to the establishment of trade networks spanning large areas of Europe and Asia, and had a major effect on the distribution of wealth among individuals and nations.HP Pavilion DV4-1313TX Battery

The process through which the smiths learned to produce copper/tin bronzes is once again a mystery. The first such bronzes were probably a lucky accident from tin contamination of copper ores, but by 2000 BC, we know that tin was being mined on purpose for the production of bronze.HP Pavilion DV4-1314TU Battery

This is amazing, given that tin is a semi-rare metal, and even a rich cassiterite ore only has 5% tin. Also, it takes special skills (or special instruments) to find it and to locate the richer lodes. But, whatever steps were taken to learn about tin, these were fully understood by 2000 BC.HP Pavilion DV4-1314TX Battery

Early iron smelting

The earliest evidence to date for the bloomery smelting of iron is found at Tell Hammeh, Jordan (see also external link), and dates to 930 BC (C14 dating). However, based on the archaeological record of iron artifacts,HP Pavilion DV4-1315TU Battery

it is clear that intentional reduction of iron metal from terrestrial ores (in the case of Hammeh a Haematite ore), must have started near the end of the Late Bronze Age (ca. 1600–1150 BC). Where and how iron smelting was discovered is widely debated, and remains uncertain due to the significant lack of production finds.HP Pavilion DV4-1315TX Battery

Nevertheless, there is some consensus  that iron technology originated in the Near East, perhaps in Eastern Anatolia.

In Ancient Egypt, somewhere between the Third Intermediate Period and 23rd Dynasty (ca. 1100–750 BC), there are indications of iron working.HP Pavilion DV4-1316TU Battery

Significantly though, no evidence for the smelting of iron from ore has been attested to Egypt in any period. There is a further possibility of iron smelting and working in West Africa by1200 BC. In addition, very early instances of carbon steel were found to be in production around 2000 years before the present in northwest Tanzania, based on complex preheating principles.HP Pavilion DV4-1316TX Battery

These discoveries are significant for the history of metallurgy.

Most early processes in Europe and Africa involved smelting iron ore in a bloomery, where the temperature is kept low enough so that the iron does not melt. This produces a spongy mass of iron called a bloom, which then has to be consolidated with a hammer.HP Pavilion DV4-1317TU Battery

Later iron smelting

From the medieval period, the process of direct reduction in bloomeries began to be replaced by an indirect process. In this, a blast furnace was used to make pig iron, which then had to undergo a further process to make forgeable bar iron.HP Pavilion DV4-1317TX Battery

Processes for the second stage include fining in a finery forge and, from theIndustrial Revolution, puddling. However both processes are now obsolete, and wrought iron is now hardly made. Instead, mild steel is produced from a bessemer converter or by other means.HP Pavilion DV4-1318TU Battery

Base metals

The ores of base metals are often sulfides. In recent centuries, reverberatory smelters (sometimes called cupolas) have been used. These keep the fuel and the charge being smelted separate. Traditionally these were used for carrying out the first step:HP Pavilion DV4-1318TX Battery

formation of two liquids, one an oxide slag containing most of the impurity elements, and the other a sulfide matte containing the valuable metal sulfide and some impurities. Such "reverb" furnaces are today about 40 m long, 3 m high and 10 m wide.HP Pavilion DV4-1319TU Battery

Fuel is burned at one end and the heat melts the dry sulfide concentrates (usually after partial roasting), which is fed through the openings in the roof of the furnace. The slag floats on top of the heavier matte, and is removed and discarded or recycled. The sulfide matte is then sent to the converter.HP Pavilion DV4-1319TX Battery

However the precise details of the process will vary from one furnace to another depending on the mineralogy of the orebody from which the concentrate origninates.

More recent furnaces have been designed based upon bath smelting, top jetting lance smelting, flash smelting and blast furnaces.HP Pavilion DV4-1320CA Battery

Some examples of bath smelters include, the noranda furnace, the teniente reactor, the vunyukov smelter and the SKS technology to name a few. Top jetting lance smelters include the mitsubishi smelting reactor. The flash smelters consist of over 50% of the worlds copper smelters.HP Pavilion DV4-1320TX Battery

There are many more varies smelters as well, including the kievset, Ausmelt, Isasmelt, Tamano, EAF, and BF.

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrousalloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy.HP Pavilion DV4-1321TX Battery

White cast ironis named after its white surface when fractured, due to its carbide impurities which allow cracks to pass straight through.Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.HP Pavilion DV4-1322TX Battery

Carbon (C) and silicon (Si) are the main alloying elements, with the amount ranging from 2.1 to 4 wt% and 1 to 3 wt%, respectively. Iron alloys with less carbon content are known as steel. While this technically makes these base alloys ternary Fe-C-Si alloys, the principle of cast iron solidification is understood from the binary iron-carbon phase diagram.HP Pavilion DV4-1322US Battery

Since the compositions of most cast irons are around the eutectic point of the iron-carbon system, the melting temperatures closely correlate, usually ranging from 1,150 to 1,200 °C (2,102 to 2,192 °F), which is about 300 °C (572 °F) lower than the melting point of pure iron.HP Pavilion DV4-1323TX Battery

Cast iron tends to be brittle, except for malleable cast irons. With its relatively low melting point, good fluidity,castability, excellent machinability, resistance to deformation and wear resistance, cast irons have become an engineering material with a wide range of applications and are used in pipes,HP Pavilion DV4-1324TX Battery

machines and automotive industry parts, such as cylinder heads (declining usage), cylinder blocks and gearbox cases (declining usage). It is resistant to destruction and weakening by oxidation (rust).

Cast iron is made by re-melting pig iron, often along with substantial quantities of scrap iron and scrap steel and taking various steps to remove undesirable contaminants.HP Pavilion DV4-1325TX Battery

Phosphorus and sulphur may be burnt out of the molten iron, but this also burns out the carbon, which must be replaced. Depending on the application, carbon and silicon content are adjusted to the desired levels, which may be anywhere from 2 to 3.5% and 1 to 3% respectively.HP Pavilion DV4-1326TX Battery

Other elements are then added to the melt before the final form is produced by casting.

Iron is sometimes melted in a special type of blast furnace known as a cupola, but more often melted in electric induction furnaces.After melting is complete, the molten iron is poured into a holding furnace or ladle.HP Pavilion DV4-1327TX Battery

Alloying elements

Cast iron's properties are changed by adding various alloying elements, or alloyants. Next to carbon, silicon is the most important alloyant because it forces carbon out of solution. Instead the carbon forms graphite which results in a softer iron, reduces shrinkage, lowers strength, and decreases density.HP Pavilion DV4-1328TX Battery

Sulfur, when added, forms iron sulfide, which prevents the formation of graphite and increases hardness. The problem with sulfur is that it makes molten cast iron sluggish, which causes short run defects. To counter the effects of sulfur, manganese is added because the two form into manganese sulfide instead of iron sulfide.HP Pavilion DV4-1329TX Battery

The manganese sulfide is lighter than the melt so it tends to float out of the melt and into the slag. The amount of manganese required to neutralize sulfur is 1.7×sulfur content+0.3%. If more than this amount of manganese is added, thenmanganese carbide forms, which increases hardness and chilling, except in grey iron, where up to 1% of manganese increases strength and density.HP Pavilion DV4-1330TX Battery

Nickel is one of the most common alloyants because it refines the pearlite and graphite structure, improves toughness, and evens out hardness differences between section thicknesses. Chromium is added in small amounts to the ladle to reduce free graphite, produce chill, and because it is a powerful carbide stabilizer; nickel is often added in conjunction.HP Pavilion DV4-1331TX Battery

A small amount of tin can be added as a substitute for 0.5% chromium. Copper is added in the ladle or in the furnace, on the order of 0.5 to 2.5%, to decrease chill, refine graphite, and increase fluidity. Molybdenum is added on the order of 0.3 to 1% to increase chill and refine the graphite and pearlite structure;HP Pavilion DV4-1332TX Battery

it is often added in conjunction with nickel, copper, and chromium to form high strength irons. Titanium is added as a degasser and deoxidizer, but it also increases fluidity. 0.15 to 0.5% vanadium are added to cast iron to stabilize cementite, increase hardness, and increase resistance to wear and heat. 0.1 to 0.3% zirconium helps to form graphite, deoxidize, and increase fluidity.HP Pavilion DV4-1365DX Battery

In malleable iron melts, bismuth is added, on the scale of 0.002 to 0.01%, to increase how much silicon can be added. In white iron, boron is added to aid in the production of malleable iron; it also reduces the coarsening effect of bismuth.[1]

Grey cast iron

Grey cast iron is characterized by its graphitic microstructure, which causes fractures of the material to have a grey appearance.HP Pavilion DV4-1400 CTO Battery

It is the most commonly used cast iron and the most widely used cast material based on weight. Most cast irons have a chemical composition of 2.5 to 4.0% carbon, 1 to 3% silicon, and the remainder is iron. Grey cast iron has less tensile strength and shock resistance than steel, but its compressive strength is comparable to low and medium carbon steel.HP Pavilion DV4-1404TX Battery

White cast iron

It is the iron that displays white fractured surface due to the presence of cementite. With a lower silicon content and faster cooling, the carbon in white cast ironprecipitates out of the melt as the metastable phase cementite, Fe3C, rather than graphite.HP Pavilion DV4-1405TX Battery

The cementite which precipitates from the melt forms as relatively large particles, usually in a eutectic mixture, where the other phase is austenite (which on cooling might transform to martensite). These eutectic carbides are much too large to provide precipitation hardeningHP Pavilion DV4-1406TX Battery

(as in some steels, where cementite precipitates might inhibit plastic deformation by impeding the movement of dislocationsthrough the ferrite matrix). Rather, they increase the bulk hardness of the cast iron simply by virtue of their own very high hardness and their substantial volume fraction, such that the bulk hardness can be approximated by a rule of mixtures.HP Pavilion DV4-1407TX Battery

In any case, they offer hardness at the expense of toughness. Since carbide makes up a large fraction of the material, white cast iron could reasonably be classified as a cermet. White iron is too brittle for use in many structural components, but with good hardness and abrasion resistance and relatively low cost,HP Pavilion DV4-1408TX Battery

it finds use in such applications as the wear surfaces (impeller and volute) of slurry pumps, shell liners and lifter bars in ball mills and autogenous grinding mills, balls and rings in coal pulverisers, and the teeth of a backhoe's digging bucket (although cast medium-carbon martensitic steel is more common for this application).HP Pavilion DV4-1409TX Battery

It is difficult to cool thick castings fast enough to solidify the melt as white cast iron all the way through. However, rapid cooling can be used to solidify a shell of white cast iron, after which the remainder cools more slowly to form a core of grey cast iron. The resulting casting, called a chilled casting, has the benefits of a hard surface and a somewhat tougher interior.HP Pavilion DV4-1413LA Battery

High-chromium white iron alloys allow massive castings (for example, a 10-tonne impeller) to be sand cast, i.e., a high cooling rate is not required, as well as providing impressive abrasion resistance.

Malleable cast iron

Malleable iron starts as a white iron casting that is then heat treated at about 900 °C (1,650 °F).HP Pavilion DV4-1414LA Battery

Graphite separates out much more slowly in this case, so thatsurface tension has time to form it into spheroidal particles rather than flakes. Due to their lower aspect ratio, spheroids are relatively short and far from one another, and have a lower cross section vis-a-vis a propagating crack or phonon.HP Pavilion DV4-1416LA Battery

They also have blunt boundaries, as opposed to flakes, which alleviates the stress concentration problems faced by grey cast iron. In general, the properties of malleable cast iron are more like mild steel. There is a limit to how large a part can be cast in malleable iron, since it is made from white cast iron.HP Pavilion DV4-1425LA Battery

Ductile cast iron

Because cast iron is comparatively brittle, it is not suitable for purposes where a sharp edge or flexibility is required. It is strong under compression, but not under tension. Cast Iron was first invented in China in the 4th century BC (see also: Du Shi) and poured into moulds to make ploughshares and pots as well as weapons and pagodas.HP Pavilion DV4T Battery

In the west, where it did not become available till the late 14th century, its earliest uses included cannon and shot. Henry VIII initiated the casting of cannon in England. Soon, English iron workers using blast furnaces developed the technique of producing cast iron cannons,HP Pavilion DV4T-1000 CTO Battery

which, while heavier than the prevailing bronze cannons, were much cheaper and enabled England to arm her navy better. The ironmasters of the Weald continued producing cast irons until the 1760s and armament was one of the main uses of irons after the Restoration.HP Pavilion DV4T-1100 CTO Battery

Cast iron pots were made at many English blast furnaces at the time. In 1707, Abraham Darby patented a method of making pots (and kettles) thinner and hence cheaper than his rivals could. This meant that his Coalbrookdale furnaces became dominant as suppliers of pots, an activity in which they were joined in the 1720s and 1730s by a small number of other coke-fired blast furnaces.HP Pavilion DV4T-1200 CTO Battery

The development of the steam engine by Thomas Newcomen provided further market for cast iron, since cast iron was considerably cheaper than the brass of which theengine cylinders were originally made. John Wilkinson was a great exponent of cast iron, who,HP Pavilion DV4T-1200SE CTO Battery

amongst other things, cast the cylinders for many of James Watt's improved steam engines until the establishment of the Soho Foundry in 1795.

Cast iron bridges

The use of cast iron for structural purposes began in the late 1770s, when Abraham Darby III built the Iron Bridge, although short beams had already been used, such as in the blast furnaces at Coalbrookdale.HP Pavilion DV4T-1300 CTO Battery

Other inventions followed, including one patented by Thomas Paine. Cast iron bridges became commonplace as the Industrial Revolution gathered pace. Thomas Telford adopted the material for his bridge upstream at Buildwas, and then for a canal trough aqueduct at Longdon-on-Tern on theShrewsbury Canal.HP Pavilion DV4T-1300SE CTO Battery

It was followed by the Chirk Aqueduct and the Pontcysyllte Aqueduct, both of which remain in use following the recent restorations. Cast iron beam bridges were used widely by the early railways, such as the Water Street Bridge at the Manchester terminus of the Liverpool and Manchester Railway.HP Pavilion DV4T-1400 CTO Battery

Problems arose when a new bridge carrying the Chester and Holyhead Railway across the River Dee in Chester collapsed in May 1847, less than a year after it was opened. The Dee bridge disaster was caused by excessive loading at the centre of the beam by a passing train, and many similar bridges had to be demolished and rebuilt, often in wrought iron.HP Pavilion DV4Z Battery

The bridge had been erroneously designed, being trussed with wrought iron straps, which were wrongly thought to reinforce the structure. The centres of the beams were put into bending, with the lower edge in tension, where cast iron, like masonry, is very weak.HP Pavilion DV4Z-1000 CTO Battery

The best way of using cast iron for bridge construction was by using arches, so that all the material is in compression. Cast iron, again like masonry, is very strong in compression. Wrought iron, like most other kinds of iron and indeed like most metals in general, is strong in tension, and also tough - resistant to fracturing.HP Pavilion DV4Z-1100 CTO Battery

The relationship between wrought iron and cast iron, for structural purposes, may be thought of as analogous to the relationship between wood and stone.

Nevertheless, cast iron continued to be used in inappropriate structural ways, until the Tay Rail Bridge disaster of 1879 cast serious doubt on the use of the material. HP Pavilion DV4Z-1200 CTO Battery

Crucial lugs for holding tie bars and struts in the Tay Bridge had been cast integral with the columns and they failed in the early stages of the accident. In addition, the bolt holes were also cast and not drilled, so that all the tension from the tie bars was placed on a corner, rather than being spread over the length of the hole.HP Pavilion DV4 Battery

The replacement bridge was built in wrought iron and steel.

Further bridge collapses occurred, however, culminating in the Norwood Junction rail accident of 1891. Thousands of cast iron rail underbridges were eventually replaced by steel equivalents.HP Pavilion DV4-1000 Battery

Cast iron columns enabled architects to build tall buildings without the enormously thick walls required to construct masonry buildings of any height. Such flexibility allowed tall buildings to have large windows. In urban centres like SoHo-Cast Iron Historic District in New York City,HP Pavilion DV4-1000EA Battery

manufacturing buildings and early department stores were built with cast iron columns to allow daylight to enter. Slender cast iron columns could also support the weight that would otherwise require thick masonry columns or piers, opening up floor spaces in factories, and sight lines in churches and auditoriums.HP Pavilion DV4-1000ET Battery

The historic Iron Building in Watervliet, New York, is a cast iron building.

Textile mills

Another important use was in textile mills. The air in the mills contained flammable fibres from the cotton, hemp, or wool being spun. As a result, textile mills had an alarming propensity to burn down.HP Pavilion DV4-1001 Battery

The solution was to build them completely of non-combustible materials, and it was found convenient to provide the building with an iron frame, largely of cast iron, replacing flammable wood. The first such building was at Ditherington in Shrewsbury, Shropshire.HP Pavilion DV4-1001AX Battery

Many other warehouses were built using cast iron columns and beams, although faulty designs, flawed beams or overloading sometimes caused building collapses and structural failures.HP Pavilion DV4-1001TU Battery

During the Industrial Revolution, cast iron was also widely used for frame and other fixed parts of machinery, including spinning and later weaving machines in textile mills. Cast iron became widely used, and many towns had foundries producing industrial and agricultural machinery.HP Pavilion DV4-1001TX Battery,HP Pavilion DV4-1002 Battery,HP Pavilion DV4-1002AX Battery,HP Pavilion DV4-1002TU Battery,HP Pavilion DV4-1002TX Battery,HP Pavilion DV4-1003AX Battery,HP Pavilion DV4-1003TU Battery,HP Pavilion DV4-1003TX Battery,HP Pavilion DV4-1004AX Battery,HP Pavilion DV4-1004TU Battery

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Iron is a chemical element with the symbol Fe (from Latin: ferrum) and atomic number 26. It is a metal in the first transition series. It is the most common element (by mass) forming the planet Earth as a whole, forming much of Earth'souter and inner core. It is the fourth most common element in the Earth's crust.HP Pavilion DV4 Battery

Iron's very common presence in rocky planets like Earth is due to its abundant production as a result of fusion in high-mass stars, where the production ofnickel-56 (which decays to iron) is the last nuclear fusion reaction that is exothermic. This allows radioactive nickel to become the last element to be produced before collapse of a supernova leads to events that scatters this precursorradionuclide of iron into space.HP Pavilion DV4-1000 Battery

Like other Group 8 elements, iron exists in a wide range of oxidation states, ?2 to + 6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen and water. Fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give iron oxides, also known as rust.HP Pavilion DV4-1000EA Battery

Unlike many other metals which form passivating oxide layers, iron oxides occupy more volume than iron metal, and thus iron oxides flake off and expose fresh surfaces for corrosion.

Iron metal has been used since ancient times, though lower-melting copper alloys were used first in history.HP Pavilion DV4-1000ET Battery

Pure iron is soft (softer than aluminium), but is unobtainable by smelting. The material is significantly hardened and strengthened by impurities from the smelting process, such as carbon. A certain proportion of carbon (between 0.2% and 2.1%) producessteel, which may be up to 1000 times harder than pure iron.HP Pavilion DV4-1001 Battery

Crude iron metal is produced in blast furnaces, where ore is reduced by coke to cast iron, which has a high carbon content. Further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and low carbon iron alloys with other metals (alloy steels) are by far the most common metals in industrial use, due to their great range of desirable properties.HP Pavilion DV4-1001AX Battery

Iron chemical compounds, which include ferrous and ferric compounds, have many uses. Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. It forms binary compounds with thehalogens and the chalcogens.HP Pavilion DV4-1001TU Battery

Among its organometallic compounds, ferrocene was the first sandwich compound discovered.

Iron plays an important role in biology, forming complexes with molecular oxygen in hemoglobin and myoglobin; these two compounds are common oxygen transport proteins in vertebrates.HP Pavilion DV4-1001TX Battery

Iron is also the metal used at the active site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants and animals.

Mechanical properties of iron and its alloys are evaluated using a variety of tests, such as the Brinell test, Rockwell test, or tensile strength tests, among others;HP Pavilion DV4-1002 Battery

the results on iron are so consistent that iron is often used to calibrate measurements or to relate the results of one test to another.Those measurements reveal that mechanical properties of iron crucially depend on purity: Purest research-purpose single crystals of iron are softer than aluminium.HP Pavilion DV4-1002AX Battery

Addition of only 10 parts per million of carbon doubles their strength.[1] The hardness increases rapidly with carbon content up to 0.2% and saturates at ~0.6%.[4] The purest industrially produced iron (about 99.99% purity) has a hardness of 20–30 Brinell.HP Pavilion DV4-1002TU Battery

Phase diagram and allotropes

Iron represents an example of allotropy in a metal. There are at least four allotropic forms of iron, known as ?, ?, ?, and ?; at very high pressures, some controversial experimental evidence exists for a phase ? stable at very high pressures and temperatures.HP Pavilion DV4-1002TX Battery

As molten iron cools down it crystallizes at 1538 °C into its ? allotrope, which has abody-centered cubic (bcc) crystal structure. As it cools further its crystal structurechanges to face-centered cubic (fcc) at 1394 °C, when it is known as ?-iron, oraustenite. At 912 °C the crystal structure again becomes bcc as ?-iron, or ferrite, is formed, and at 770 °C (the Curie point, Tc) iron becomes magnetic.HP Pavilion DV4-1003AX Battery

As the iron passes through the Curie temperature there is no change in crystalline structure, but there is a change in "domain structure", where each domain contains iron atoms with a particular electronic spin. In unmagnetized iron, all the electronic spins of the atoms within one domain are in the same direction; the neighboring domains point in various directions and thus cancel out.HP Pavilion DV4-1003TU Battery

In magnetized iron, the electronic spins of all the domains are aligned, so that the magnetic effects of neighboring domains reinforce each other. Although each domain contains billions of atoms, they are very small, about 10 micrometres across.HP Pavilion DV4-1003TX Battery

At pressures above approximately 10 GPa and temperatures of a few hundred kelvin or less, ?-iron changes into a hexagonal close-packed (hcp) structure, which is also known as ?-iron; the higher-temperature ?-phase also changes into ?-iron, but does so at higher pressure.HP Pavilion DV4-1004AX Battery

The ?-phase, if it exists, would appear at pressures of at least 50 GPa and temperatures of at least 1500 K; it has been thought to have an orthorhombic or a double hcp structure.

Iron is of greatest importance when mixed with certain other metals and with carbon to form steels.HP Pavilion DV4-1004TU Battery

There are many types of steels, all with different properties, and an understanding of the properties of the allotropes of iron is key to the manufacture of good quality steels.

?-iron, also known as ferrite, is the most stable form of iron at normal temperatures. It is a fairly soft metal that can dissolve only a small concentration of carbon (no more than 0.021% by mass at 910 °C).HP Pavilion DV4-1004TX Battery

Above 912 °C and up to 1400 °C ?-iron undergoes a phase transition from bcc to the fcc configuration of ?-iron, also called austenite. This is similarly soft and metallic but can dissolve considerably more carbon (as much as 2.04% by mass at 1146 °C). This form of iron is used in the type of stainless steel used for making cutlery, and hospital and food-service equipment.HP Pavilion DV4-1005TX Battery

The high-pressure phases of iron are important as endmember models for the solid parts of planetary cores. The inner core of the Earth is generally assumed to consist essentially of an iron-nickel alloy with ? (or ?) structure.

The melting point of iron is experimentally well constrained for pressures up to approximately 50 GPa. HP Pavilion DV4-1006TX Battery

For higher pressures, different studies placed the ?-?-liquid triple point at pressures differing by tens of gigapascals and yielded differences of more than 1000 K for the melting point. Generally speaking, molecular dynamics computer simulations of iron melting and shock wave experiments suggest higher melting points and a much steeper slope of the melting curve than static experiments carried out in diamond anvil cells.HP Pavilion DV4-1007TX Battery

Naturally occurring iron consists of four stable isotopes: 5.845% of 54Fe, 91.754% of 56Fe, 2.119% of 57Fe and 0.282% of 58Fe. Of these stable isotopes, only 57Fe has a nuclear spin (?1/2). The nuclide 54Fe is predicted to undergo double beta decay, but this process had never been observed experimentally for these nuclei, and only the lower limit on the half-life was established: t1/2>3.1×1022 years.HP Pavilion DV4-1008TX Battery

60Fe is an extinct radionuclide of long half-life (2.6 million years).[10] It is not found on Earth, but its ultimate decay product is forms part of the natural abundance of the stable nuclide nickel-60.

Much of the past work on measuring the isotopic composition of Fe has focused on determining 60Fe variations due to processes accompanying nucleosynthesis (i.e.,meteorite studies) and ore formation.HP Pavilion DV4-1009TX Battery

In the last decade however, advances in mass spectrometry technology have allowed the detection and quantification of minute, naturally occurring variations in the ratios of the stable isotopes of iron. Much of this work has been driven by the Earth and planetary science communities, although applications to biological and industrial systems are beginning to emerge.HP Pavilion DV4-1010TX Battery

The most abundant iron isotope 56Fe is of particular interest to nuclear scientists as it represents the most common endpoint of nucleosynthesis. It is often cited, falsely, as the isotope of highest binding energy, a distinction which actually belongs to nickel-62.HP Pavilion DV4-1011TX Battery

Since 56Ni is easily produced from lighter nuclei in thealpha process in nuclear reactions in supernovae (see silicon burning process), nickel-56 (14 alpha particles) is the endpoint of fusion chains inside extremely massive stars, since addition of another alpha particle would result in zinc-60, which requires a great deal more energy.HP Pavilion DV4-1012TX Battery

This nickel-56, which has a half-life of about 6 days, is therefore made in quantity in these stars, but soon decays by two successive positron emissions within supernova decay products in the supernova remnant gas cloud, first to radioactive cobalt-56, and then stable iron-56.HP Pavilion DV4-1013TX Battery

This last nuclide is therefore common in the universe, relative to other stable metals of approximately the same atomic weight.

In phases of the meteorites Semarkona and Chervony Kut a correlation between the concentration of 60Ni,HP Pavilion DV4-1014NR Battery

the daughter product of 60Fe, and the abundance of the stable iron isotopes could be found which is evidence for the existence of 60Fe at the time of formation of the solar system. Possibly the energy released by the decay of60Fe contributed, together with the energy released by decay of the radionuclide 26Al,HP Pavilion DV4-1014TX Battery

to the remelting and differentiation of asteroids after their formation 4.6 billion years ago . The abundance of 60Ni present in extraterrestrial material may also provide further insight into the origin of the solar systemand its early history.HP Pavilion DV4-1015TX Battery

Nuclei of iron atoms have some of the highest binding energies per nucleon, surpassed only by the nickel isotope 62Ni. This is formed by nuclear fusion in stars. Although a further tiny energy gain could be extracted by synthesizing 62Ni, conditions in stars are unsuitable for this process to be favored.HP Pavilion DV4-1015TX Battery

Elemental distribution on Earth greatly favors iron over nickel, and also presumably in supernova element production.

Iron-56 is the heaviest stable isotope produced by the alpha process in stellar nucleosynthesis; elements heavier than iron and nickel require a supernova for their formation.HP Pavilion DV4-1016TX Battery

Iron is the most abundant element in the core of red giants, and is the most abundant metal in iron meteorites and in the dense metal cores of planetssuch as Earth.

Nucleosynthesis

Iron is created by extremely large, extremely hot (over 2.5 billion kelvin) stars, through a process called the silicon burning process.HP Pavilion DV4-1017TX Battery

It is the heaviest stable element to be produced in this manner. The process starts with the second largest stable nucleus created by silicon burning: calcium. One stable nucleus of calcium fuses with one helium nucleus, creating unstable titanium. Before the titanium decays, it can fuse with another helium nucleus, creating unstable chromium.HP Pavilion DV4-1018TX Battery

Before the chromium decays, it can fuse with another helium nucleus, creating unstable iron. Before the iron decays, it can fuse with another helium nucleus, creating unstable nickel-56. Any further fusion of nickel-56 consumes energy instead of producing energy, so after the production of nickel-56, the star does not produce the energy necessary to keep the core from collapsing.HP Pavilion DV4-1019TX Battery

Eventually, the nickel-56 decays to unstable cobalt-56 which, in turn decays to stable iron-56 When the core of the star collapses, it creates a Supernova. Supernovas also create additional forms of stable iron via the r-process.

Planetary occurrence

Iron is the sixth most abundant element in the Universe, formed as the final step of nucleosynthesis, by silicon fusing in massive stars.HP Pavilion DV4-1020TX Battery

Metallic iron is rarely found on the surface of the earth because it tends to oxidize, but its oxides are pervasive and represent the primary ores. While it makes up about 5% of the Earth's crust, both the Earth's inner and outer core are believed to consist largely of an iron-nickel alloy constituting 35% of the mass of the Earth as a whole. HP Pavilion DV4-1020US Battery

Iron is consequently the most abundant element on Earth, but only the fourth most abundant element in the Earth's crust. Most of the iron in the crust is found combined with oxygen as iron oxide minerals such as hematite and magnetite. Large deposits of iron are found in banded iron formations.HP Pavilion DV4-1021TX Battery

These geological formations are a type of rock consisting of repeated thin layers of iron oxides, either magnetite (Fe3O4) or hematite (Fe2O3), alternating with bands of iron-poor shale and chert. The banded iron formations are common in the time between 3,700 million years ago and 1,800 million years ago.HP Pavilion DV4-1022TX Battery

About 1 in 20 meteorites consist of the unique iron-nickel minerals taenite (35–80% iron) and kamacite (90–95% iron). Although rare, iron meteorites are the main form of natural metallic iron on the Earth's surface. It was proven by Mössbauer spectroscopy that the red color of the surface of Mars is derived from an iron oxide-rich regolith.HP Pavilion DV4-1023TX Battery

In-use stocks in society

According to the International Resource Panel's Metal Stocks in Society report, the global per capita stock of iron in use in society is 2200kg. Much of this is in more-developed countries (7000–14000kg per capita) rather than less-developed countries (2000kg per capita).HP Pavilion DV4-1024TX Battery

Chemistry and compounds

Iron forms compounds mainly in the +2 and +3 oxidation states. Traditionally, iron(II) compounds are called ferrous, and iron(III) compounds ferric. Iron also occurs in higher oxidation states, an example being the purple potassium ferrate (K2FeO4) which contains iron in its +6 oxidation state.HP Pavilion DV4-1025TX Battery

Iron(IV) is a common intermediate in many in biochemical oxidation reactions. Numerousorganometallic compounds contain formal oxidation states of +1, 0, ?1, or even ?2. The oxidation states and other bonding properties are often assessed using the technique of Mössbauer spectroscopy.HP Pavilion DV4-1026TX Battery

There are also many mixed valence compounds that contain both iron(II) and iron(III) centers, such as magnetite and Prussian blue (Fe4(Fe[CN]6)3).[21] The latter is used as the traditional "blue" in blueprints.

The iron compounds produced on the largest scale in industry are iron(II) sulfate (FeSO4·7H2O) andiron(III) chloride (FeCl3).HP Pavilion DV4-1027TX Battery

The former is one of the most readily available sources of iron(II), but is less stable to aerial oxidation than Mohr's salt ((NH4)2Fe(SO4)2·6H2O). Iron(II) compounds tend to be oxidized to iron(III) compounds in the air.

Unlike many other metals, iron does not form amalgams with mercury. As a result, mercury is traded in standardized 76 pound flasks (34 kg) made of iron.HP Pavilion DV4-1028TX Battery

Binary compounds

Iron reacts with oxygen in the air to form various oxide and hydroxide compounds; the most common are iron(II,III) oxide (Fe3O4), and iron(III) oxide (Fe2O3). Iron(II) oxide also exists, though it is unstable at room temperature.HP Pavilion DV4-1028US Battery

These oxides are the principal ores for the production of iron (see bloomery and blast furnace). They are also used in the production of ferrites, usefulmagnetic storage media in computers, and pigments. The best known sulfide is iron pyrite (FeS2), also known as fool's gold owing to its golden luster.HP Pavilion DV4-1029TX Battery

The binary ferrous and ferric halides are well known, with the exception of ferric iodide. The ferrous halides typically arise from treating iron metal with the corresponding binary halogen acid to give the corresponding hydrated salts.HP Pavilion DV4-1030EE Battery

Fe + 2 HX ? FeX2 + H2

Iron reacts with fluorine, chlorine, and bromine to give the corresponding ferric halides, ferric chloride being the most common:

2 Fe + 3 X2 ? 2 FeX3 (X = F, Cl, Br) HP Pavilion DV4-1030EI Battery

Coordination and organometallic compounds

e complexes are known. The most famous example is Prussian blue, (Fe4(Fe[CN]6)3). Potassium ferricyanide andpotassium ferrocyanide are also known; the formation of Prussian blue upon reaction with iron(II) and iron(III) respectively forms the basis of a "wet" chemical test.HP Pavilion DV4-1030EJ Battery

Prussian blue is also used as an antidote for thallium and radioactive caesiumpoisoning. Prussian blue can be used in laundry bluing to correct the yellowish tint left by ferrous salts in water.

Several carbonyl compounds of iron are known. The premier iron(0) compound is iron pentacarbonyl, Fe(CO)5, which is used to produce carbonyl iron powder, a highly reactive form of metallic iron.HP Pavilion DV4-1030EN Battery

Thermolysis of iron pentacarbonyl gives the trinuclear cluster,triiron dodecacarbonyl. Collman's reagent, disodium tetracarbonylferrate, is a useful reagent for organic chemistry; it contains iron in the ?2 oxidation state. Cyclopentadienyliron dicarbonyl dimer contains iron in the rare +1 oxidation state.HP Pavilion DV4-1030TX Battery

Ferrocene is an extremely stable complex. The first sandwich compound, it contains an iron(II) center with two cyclopentadienyl ligands bonded through all ten carbon atoms. This arrangement was a shocking novelty when it was first discovered,[29] but the discovery of ferrocene has led to a new branch of organometallic chemistry.HP Pavilion DV4-1031TX Battery

Ferrocene itself can be used as the backbone of a ligand, e.g. dppf. Ferrocene can itself be oxidized to the ferrocenium cation (Fc+); the ferrocene/ferrocenium couple is often used as a reference in electrochemistry.

Wrought iron

Iron objects of great age are much rarer than objects made of gold or silver due to the ease of corrosion of iron.HP Pavilion DV4-1032TX Battery

Beads made of meteoric iron in 3500 B.C. or earlier were found in Gerzah, Egypt by G. A. Wainwright. The beads contain 7.5% nickel, which is a signature of meteoric origin since iron found in the Earth's crust has very little to no nickel content.HP Pavilion DV4-1033TX Battery

Meteoric iron was highly regarded due to its origin in the heavens and was often used to forge weapons and tools or whole specimens placed in churches. Items that were likely made of iron by Egyptians date from 2500 to 3000 BC. Iron had a distinct advantage over bronze in warfare implements.HP Pavilion DV4-1034TX Battery

It was much harder and more durable than bronze, although susceptible to rust. However, this is contested. Hittitologist Trevor Bryce argues that before advanced iron-working techniques were developed in Europe and India, cast-iron weapons used by early Mesopotamian armies had a tendency to shatter in combat, due to their high carbon content.HP Pavilion DV4-1035LA Battery

The first iron production started in the Middle Bronze Age but it took several centuries before iron displaced bronze. Samples ofsmelted iron from Asmar, Mesopotamia and Tall Chagar Bazaar in northern Syria were made sometime between 2700 and 3000 BC.HP Pavilion DV4-1035TX Battery

TheHittites appear to be the first to understand the production of iron from its ores and regard it highly in their society.[27] They began to smelt iron between 1500 and 1200 BC and the practice spread to the rest of the Near East after their empire fell in 1180 BC.HP Pavilion DV4-1036TX Battery

The subsequent period is called the Iron Age. Iron smelting, and thus the Iron Age, reached Europe two hundred years later and arrived in Zimbabwe, Africa by the 8th century.

Artifacts from smelted iron occur in India from 1800 to 1200 BC, and in the Levant from about 1500 BC (suggesting smelting inAnatolia or the Caucasus).HP Pavilion DV4-1037TX Battery

The Book of Genesis, fourth chapter, verse 22 contains the first mention of iron in the Old Testament of the Bible; "Tubal-cain, an instructor of every artificer in brass and iron." Other verses allude to iron mining (Job 28:2), iron used as a stylus (Job 19:24), furnace (Deuteronomy 4:20),HP Pavilion DV4-1038TX Battery

chariots (Joshua 17:16), nails (I Chron. 22:3), saws and axes (II Sam. 12:31), and cooking utensils (Ezekiel 4:3).[38] The metal is also mentioned in the New Testament, for example in Acts chapter 12 verse 10, "[Peter passed through] the iron gate that leadeth unto the city" of Antioch.[39] The Quran referred to Iron 1400 years ago.HP Pavilion DV4-1039TX Battery

Iron working was introduced to Greece in the late 11th century BC.[40] The spread of ironworking in Central and Western Europe is associated with Celtic expansion. According to Pliny the Elder, iron use was common in the Roman era.[32] The annual iron output of the Roman Empire is estimated at 84,750 t,  while the similarly populous Han China produced around 5,000 t.HP Pavilion DV4-1040EE Battery

During the Industrial Revolution in Britain, Henry Cort began refining iron from pig iron to wrought iron (or bar iron) using innovative production systems. In 1783 he patented the puddling process for refining iron ore. It was later improved by others including Joseph Hall.HP Pavilion DV4-1040EI Battery

Cast iron

Cast iron was first produced in China about 550 BC, but was hardly in Europe until the medieval period. During the medieval period, means were found in Europe of producing wrought iron from cast iron (in this context known as pig iron) using finery forges. For all these processes, charcoal was required as fuel.HP Pavilion DV4-1040TX Battery

Medieval blast furnaces were about 10 feet (3.0 m) tall and made of fireproof brick; forced air was usually provided by hand-operated bellows.[45] Modern blast furnaces have grown much bigger.

In 1709, Abraham Darby I established a coke-fired blast furnace to produce cast iron.HP Pavilion DV4-1041TX Battery

The ensuing availability of inexpensive iron was one of the factors leading to the Industrial Revolution. Toward the end of the 18th century, cast iron began to replace wrought iron for certain purposes, because it was cheaper. Carbon content in iron wasn't implicated as the reason for the differences in properties of wrought iron, cast iron and steel until the 18th century.HP Pavilion DV4-1042TX Battery

Since iron was becoming cheaper and more plentiful, it also became a major structural material following the building of the innovative first iron bridge in 1778.

Steel

Steel (with smaller carbon content than pig iron but more than wrought iron) was first produced in antiquity by using a bloomery.HP Pavilion DV4-1043TX Battery

Blacksmiths in Luristan in western Iran were making good steel by 1000 BC. Then improved versions, Wootz steel by India and Damascus steel by China were developed around 300 B.C. and 500 A.D. respectively. These methods were specialized, and so steel did not become a major commodity until the 1850s.HP Pavilion DV4-1044TX Battery

New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century AD. In the Industrial Revolution, new methods of producing bar iron without charcoal were devised and these were later applied to produce steel.HP Pavilion DV4-1045TX Battery

In the late 1850s, Henry Bessemer invented a new steelmaking process, involving blowing air through molten pig iron, to produce mild steel. This made steel much more economical, thereby leading to wrought iron no longer being produced.HP Pavilion DV4-1046TX Battery

Foundations of modern chemistry

Antoine Lavoisier used the reaction of water steam with metallic iron inside an incandescent iron tube to produce hydrogen in his experiments leading to the demonstration of the mass conservation. Anaerobic oxidation of iron at high temperature can be schematically represented by the following reactions:HP Pavilion DV4-1047TX Battery

Fe +    H2O ? FeO + H2

2 Fe + 3 H2O ? Fe2O3 + 3 H2

3 Fe + 4 H2O ? Fe3O4 + 4 H2

Recent discoveries

  • many enzymes use iron in the catalytic center
  • Nickel-56 is the natural end product of silicon burning in massive stars. However Nickel-56 decays to cobalt-56 and then to stable iron-56, ultimately making iron the most abundant heavy element produced by that nucleosynthesis.
  • superconductivity?HP Pavilion DV4-1049TX Battery
  • magnetic effect
  • ferrocene

Industrial production

The production of iron or steel is a process containing two main stages, unless the desired product is cast iron. The first stage is to produce pig iron in a blast furnace. Alternatively, it may be directly reduced. The second is to make wrought iron or steel from pig iron by a further process.HP Pavilion DV4-1050 Battery

For a few limited purposes like electromagnet cores, pure iron is produced by electrolysis of a ferrous sulfate solution

Blast furnace

Ninety percent of all mining of metallic ores is for the extraction of iron .HP Pavilion DV4-1050EE Battery

Industrially, iron production involves iron ores, principally hematite (nominally Fe2O3) and magnetite (Fe3O4) in a carbothermic reaction (reduction with carbon) in a blast furnace at temperatures of about 2000 °C. In a blast furnace, iron ore, carbon in the form of coke, and a flux such aslimestoneHP Pavilion DV4-1050EL Battery

(which is used to remove silicon dioxide impurities in the ore which would otherwise clog the furnace with solid material) are fed into the top of the furnace, while a massive blast of heated air, about 4 tons per ton of iron,[45] is forced into the furnace at the bottom.HP Pavilion DV4-1050EP Battery

2 C + O2 ? 2 CO

The carbon monoxide reduces the iron ore (in the chemical equation below, hematite) to molten iron, becoming carbon dioxide in the process:

Fe2O3 + 3 CO ? 2 Fe + 3 CO2

Some iron in the high-temperature lower region of the furnace reacts directly with the coke:HP Pavilion DV4-1050ER Battery

2 Fe2O3 + 3 C ? 4 Fe + 3 CO2

The flux is present to melt impurities in the ore, principally silicon dioxide sand and othersilicates. Common fluxes include limestone (principally calcium carbonate) and dolomite (calcium-magnesium carbonate). Other fluxes may be used depending on the impurities that need to be removed from the ore.HP Pavilion DV4-1050TX Battery

In the heat of the furnace the limestone flux decomposes tocalcium oxide (also known as quicklime):

CaCO3 ? CaO + CO2

Then calcium oxide combines with silicon dioxide to form a liquid slag.HP Pavilion DV4-1051 Battery

CaO + SiO2 ? CaSiO3

The slag melts in the heat of the furnace. In the bottom of the furnace, the molten slag floats on top of the denser molten iron, and apertures in the side of the furnace are opened to run off the iron and the slag separately. The iron, once cooled, is called pig iron, while the slag can be used as a material in road construction or to improve mineral-poor soils for agriculture.HP Pavilion DV4-1051TX Battery

In 2005, approximately 1,544 million metric tons of iron ore were produced worldwide. According to the British Geological Survey, China was the top producer of iron ore with at least one quarter world share, followed by Brazil, Australia and India.HP Pavilion DV4-1052 Battery

Direct iron reduction

Since coke is becoming more regulated due to environmental concerns, alternative methods of processing iron have been developed. One of them is known as direct iron reduction.HP Pavilion DV4-1052TX Battery

It reduces iron ore to a powder substance called sponge iron, which is suitable for steelmaking. There are two main reactions that go on in the direct reduction process:

Natural gas is partially oxidized (with heat and a catalyst):HP Pavilion DV4-1053 Battery

2 CH4 + O2 ? 2 CO + 4 H2

These gases are then treated with iron ore in a furnace, producing solid sponge iron:

Fe2O3 + CO + 2 H2 ? 2 Fe + CO2 + 2 H2O

Silica is removed by adding a flux, i.e. limestone, later.HP Pavilion DV4-1053TX Battery

Further processes

Pig iron is not pure iron, but has 4–5% carbon dissolved in it with small amounts of other impurities like sulfur, magnesium, phosphorus and manganese. As the carbon is the major impurity, the iron (pig iron) becomes brittle and hard.HP Pavilion DV4-1054TX Battery

This form of iron, also known as cast iron, is used to cast articles in foundries such as stoves, pipes, radiators, lamp-posts and rails.

Alternatively pig iron may be made into steel (with up to about 2% carbon) or wrought iron (commercially pure iron).HP Pavilion DV4-1055TX Battery

Various processes have been used for this, including finery forges, puddling furnaces, Bessemer converters, open hearth furnaces, basic oxygen furnaces, and electric arc furnaces. In all cases, the objective is to oxidize some or all of the carbon, together with other impurities. On the other hand, other metals may be added to make alloy steels.HP Pavilion DV4-1070 Battery

The hardness of the steel depends upon its carbon content: the higher the percentage of carbon, the greater the hardness and the lesser the malleability. The properties of the steel can also be changed by several methods.

Annealing involves the heating of a piece of steel to 700–800 °C for several hours and then gradual cooling. It makes the steel softer and more workable.HP Pavilion DV4-1070EE Battery

Steel may be hardened by cold working. The metal is bent or hammered into its final shape at a relatively cool temperature. Cold forging is the stamping of a piece of steel into shape by a heavy press. Wrenches are commonly made by cold forging.HP Pavilion DV4-1070EF Battery

Cold rolling, which involves making a thinner but harder sheet, and cold drawing, which makes a thinner but stronger wire, are two other methods of cold working. To harden the steel, it is heated to red-hot and then cooled by quenching it in the water. It becomes harder and more brittle.HP Pavilion DV4-1070ER Battery

If it is too hardened, it is then heated to a required temperature and allowed to cool. The steel thus formed is less brittle.

Heat treatment is another way to harden steel. The steel is heated red-hot, then cooled quickly. The iron carbide molecules are decomposed by the heat, but do not have time to reform.HP Pavilion DV4-1070ES Battery

Since the free carbon atoms are stuck, it makes the steel much harder and stronger than before.

Sometimes both toughness and hardness are desired. A process called case hardening may be used. Steel is heated to about 900 °C then plunged into Oil or Water. Carbon from the oil can diffuse into the steel, making the surface very hard.HP Pavilion DV4-1080EI Battery

The surface cools quickly, but the inside cools slowly, making an extremely hard surface and a durable, resistant inner layer.

Iron may be passivated by dipping it into a concentrated nitric acid solution. This forms a protective layer of oxide on the metal, protecting it from further corrosion.HP Pavilion DV4-1080EO Battery

Applications

Iron is the most widely used of all the metals, accounting for 95% of worldwide metal production. Its low cost and high strength make it indispensable in engineering applications such as the construction of machinery and machine tools,automobiles, the hulls of large ships, and structural components for buildings.HP Pavilion DV4-1080ES Battery

Since pure iron is quite soft, it is most commonly used in the form of steel.

Commercially available iron is classified based on purity and the abundance of additives. Pig iron has 3.5–4.5% carbon[49] and contains varying amounts of contaminants such as sulfur, silicon and phosphorus.HP Pavilion DV4-1090EO Battery

Pig iron is not a saleable product, but rather an intermediate step in the production of cast iron and steel from iron ore. Cast iron contains 2–4% carbon, 1–6% silicon, and small amounts of manganese. Contaminants present in pig iron that negatively affect material properties, such as sulfur and phosphorus, have been reduced to an acceptable level.HP Pavilion DV4-1090ES Battery

It has a melting point in the range of 1420–1470 K, which is lower than either of its two main components, and makes it the first product to be melted when carbon and iron are heated together. Its mechanical properties vary greatly, dependent upon the form carbon takes in the alloy.HP Pavilion DV4-1100 Battery

"White" cast irons contain their carbon in the form of cementite, or iron carbide. This hard, brittle compound dominates the mechanical properties of white cast irons, rendering them hard, but unresistant to shock. The broken surface of a white cast iron is full of fine facets of the broken carbide, a very pale, silvery, shiny material, hence the appellation.HP Pavilion DV4-1100EA Battery

In gray iron the carbon exists free as fine flakes of graphite, and also renders the material brittle due to the stress-raising nature of the sharp edged flakes of graphite. A newer variant of gray iron, referred to as ductile iron is specially treated with trace amounts of magnesium to alter the shape of graphite to spheroids, or nodules, vastly increasing the toughness and strength of the material.HP Pavilion DV4-1101 Battery

Wrought iron contains less than 0.25% carbon. It is a tough, malleable product, but not as fusible as pig iron. If honed to an edge, it loses it quickly. Wrought iron is characterized by the presence of fine fibers of slag entrapped in the metal. Wrought iron is more corrosion resistant than steel.HP Pavilion DV4-1101TU Battery

It has been almost completely replaced by mild steel for traditional "wrought iron" products and blacksmithing.

Mild steel corrodes more readily than wrought iron, but is cheaper and more widely available. Carbon steel contains 2.0% carbon or less, with small amounts ofmanganese, sulfur, phosphorus, and silicon.HP Pavilion DV4-1101TX Battery

Alloy steels contain varying amounts of carbon as well as other metals, such as chromium, vanadium, molybdenum, nickel,tungsten, etc. Their alloy content raises their cost, and so they are usually only employed for specialist uses. One common alloy steel, though, is stainless steel.HP Pavilion DV4-1102 Battery

Recent developments in ferrous metallurgy have produced a growing range of microalloyed steels, also termed 'HSLA' or high-strength, low alloy steels, containing tiny additions to produce high strengths and often spectacular toughness at minimal cost.HP Pavilion DV4-1102TU Battery

Apart from traditional applications, iron is also used for protection from ionizing radiation. Although it is lighter than another traditional protection material, lead, it is much stronger mechanically. The attenuation of radiation as a function of energy is shown in the graph.HP Pavilion DV4-1102TX Battery

The main disadvantage of iron and steel is that pure iron, and most of its alloys, suffer badly from rust if not protected in some way. Painting, galvanization,passivation, plastic coating and bluing are all used to protect iron from rust by excluding water and oxygen or by cathodic protection.HP Pavilion DV4-1103TU Battery

Of compounds

Although its metallurgical role is dominant in terms of amounts, iron compounds are pervasive in industry as well being used in many niche uses. Iron catalysts are traditionally used in the Haber-Bosch Process for the production of ammonia and the Fischer-Tropsch process for conversion of carbon monoxide to hydrocarbons for fuels and lubricants.HP Pavilion DV4-1103TX Battery

Powdered iron in an acidic solvent was used in the Bechamp reduction the reduction of nitrobenzene to aniline.

Iron(III) chloride finds use in water purification and sewage treatment, in the dyeing of cloth, as a coloring agent in paints, as an additive in animal feed, and as an etchant for copper in the manufacture of printed circuit boards.HP Pavilion DV4-1104TU Battery

It can also be dissolved in alcohol to form tincture of iron.[27] The other halides tend to be limited to laboratory uses.

Iron(II) sulfate is used as a precursor to other iron compounds. It is also used to reduce chromate in cement. It is used to fortify foods and treat iron deficiency anemia.HP Pavilion DV4-1104TX Battery

These are its main uses. Iron(III) sulfate is used in settling minute sewage particles in tank water. Iron(II) chloride is used as a reducing flocculating agent, in the formation of iron complexes and magnetic iron oxides, and as a reducing agent in organic synthesis.HP Pavilion DV4-1105EF Battery

Biological role

Iron is abundant in biology. Iron-proteins are found in all living organisms, ranging from the evolutionarily primitive archaea to humans. The color of blood is due to the hemoglobin, an iron-containing protein. As illustrated by hemoglobin, iron often is bound to cofactors, e.g. in hemes.HP Pavilion DV4-1105EM Battery

The iron-sulfur clusters are pervasive and include nitrogenase, the enzymes responsible for biological nitrogen fixation. Influential theories of evolution have invoked a role for iron sulfides, iron-sulfur world theory.

Iron is a necessary trace element found in nearly all living organisms.HP Pavilion DV4-1105TU Battery

Iron-containing enzymes and proteins, often containingheme prosthetic groups, participate in many biological oxidations and in transport. Examples of proteins found in higher organisms include hemoglobin, cytochrome (see high-valent iron), and catalase.HP Pavilion DV4-1105TX Battery

Bioinorganic compounds

The most famous bioinorganic compounds of iron are heme proteins: hemoglobin, myoglobin, and cytochrome P450. These compounds can transport gases, build enzymes, and be used in transferring electrons. Metalloproteins are a group of proteins with metal ioncofactors.HP Pavilion DV4-1106EE Battery

Some examples of iron metalloproteins are ferritin and rubredoxin. Many enzymes vital to life contain iron, such ascatalase, lipoxygenases, and IRE-BP.

Health and diet

Iron is pervasive, but particularly rich sources of dietary iron include red meat, lentils, beans, poultry, fish, leaf vegetables, tofu, chickpeas, black-eyed peas, blackstrap molasses, fortified bread, and fortified breakfast cerealsHP Pavilion DV4-1106EM Battery

Iron in low amounts is found in molasses, teff and farina. Iron in meat (heme iron) is more easily absorbed than iron in vegetables. Although some studies suggest that heme/hemoglobin from red meat has effects which may increase the likelihood of colorectal cancer, there is still some controversy,and even a few studies suggesting that there is not enough evidence to support such claims.HP Pavilion DV4-1106TX Battery

Iron provided by dietary supplements is often found as iron(II) fumarate, although iron sulfate is cheaper and is absorbed equally well. Elemental iron, or reduced iron, despite being absorbed at only one third to two thirds the efficiency (relative to iron sulfate),  is often added to foods such as breakfast cereals or enriched wheat flour.HP Pavilion DV4-1107TX Battery

Iron is most available to the body when chelated to amino acids and is also available for use as a common iron supplement. Often the amino acid chosen for this purpose is the cheapest and most common amino acid, glycine, leading to "iron glycinate" supplements.HP Pavilion DV4-1108TX Battery

The Recommended Dietary Allowance(RDA) for iron varies considerably based on age, gender, and source of dietary iron (heme-based iron has higher bioavailability). Infants may require iron supplements if they are bottle-fed cow's milk. Blood donors and pregnant women are at special risk of low iron levels and are often advised to supplement their iron intake.HP Pavilion DV4-1109TX Battery

Uptake and storage

In cells, iron storage is

carefully regulated; "free" iron ions do not exist as such. A major component of this regulation is the protein transferrin, which binds iron ions absorbed from the duodenum and carries it in the blood to cells.HP Pavilion DV4-1110EO Battery

In animals, plants, and fungi, iron is often the metal ion incorporated into the heme complex. Heme is an essential component of cytochrome proteins, which mediate redox reactions, and of oxygen carrier proteins such as hemoglobin, myoglobin, andleghemoglobin.HP Pavilion DV4-1110TX Battery

Inorganic iron also contributes to redox reactions in the iron-sulfur clusters of many enzymes, such as nitrogenase (involved in the synthesis ofammonia from nitrogen and hydrogen) and hydrogenase. Non-heme iron proteins include the enzymes methane monooxygenase (oxidizes methane to methanol), ribonucleotide reductase (reduces ribose to deoxyribose;HP Pavilion DV4-1111TX Battery

DNA biosynthesis), hemerythrins (oxygen transport and fixation in Marine invertebrates) and purple acid phosphatase(hydrolysis of phosphate esters).

Iron distribution is heavily regulated in mammals, partly because iron ions have a high potential for biological toxicity.HP Pavilion DV4-1112TX Battery

Iron acquisition poses a problem for aerobic organisms because ferric iron is poorly soluble near neutral pH. Thus, bacteria have evolved high-affinity sequesteringagents called siderophores.

Regulation of uptake

Iron uptake is tightly regulated by the human body, which has no regulated physiological means of excreting iron.HP Pavilion DV4-1113TX Battery

Only small amounts of iron are lost daily due to mucosal and skin epithelial cell sloughing, so control of iron levels is mostly by regulating uptake. Regulation of iron uptake is impaired in some people as a result of a genetic defect that maps to the HLA-H gene region on chromosome 6.HP Pavilion DV4-1114NR Battery

In these people, excessive iron intake can result in iron overload disorders, such ashemochromatosis. Many people have a genetic susceptibility to iron overload without realizing it or being aware of a family history of the problem. For this reason, it is advised that people do not take iron supplements unless they suffer from iron deficiency and have consulted a doctor.HP Pavilion DV4-1114TX Battery

Hemochromatosis is estimated to cause disease in between 0.3 and 0.8% of Caucasians.

MRI finds that iron accumulates in the hippocampus of the brains of those with Alzheimer's disease and in the substantia nigra of those with Parkinson disease.HP Pavilion DV4-1115EF Battery

Permeable reactive barriers

Zero-valent iron is the main reactive material for permeable reactive barriers.

Precautions

Large amounts of ingested iron can cause excessive levels of iron in the blood. High blood levels of free ferrous iron react with peroxides to producefree radicals,HP Pavilion DV4-1115TX Battery

which are highly reactive and can damage DNA, proteins, lipids, and other cellular components. Thus, iron toxicity occurs when there is free iron in the cell, which generally occurs when iron levels exceed the capacity of transferrin to bind the iron.HP Pavilion DV4-1116TX Battery

Damage to the cells of thegastrointestinal tract can also prevent them from regulating iron absorption leading to further increases in blood levels. Iron typically damages cells in the heart, liver and elsewhere, which can cause significant adverse effects, including coma, metabolic acidosis, shock, liver failure, coagulopathy,adult respiratory distress syndrome, long-term organ damage, and even death.HP Pavilion DV4-1117CA Battery

Humans experience iron toxicity above 20 milligrams of iron for every kilogram of mass, and 60 milligrams per kilogram is considered a lethal dose.  Overconsumption of iron, often the result of children eating large quantities of ferrous sulfate tablets intended for adult consumption, is one of the most common toxicological causes of death in children under six.HP Pavilion DV4-1117TX Battery

The Dietary Reference Intake (DRI) lists the Tolerable Upper Intake Level (UL) for adults as 45 mg/day. For children under fourteen years old the UL is 40 mg/day.

The medical management of iron toxicity is complicated, and can include use of a specific chelating agent called deferoxamine to bind and expel excess iron from the body.HP Pavilion DV4-1118CA Battery

Iron fertilization is the intentional introduction of iron to the upper ocean to stimulate a phytoplankton bloom. This is intended to enhance biological productivity, which can benefit the marine food chain and remove carbon dioxide from the atmosphere. Iron is a trace element necessary for photosynthesis in all plants.HP Pavilion DV4-1118TX Battery

It is highly insoluble in sea water and is often the limiting nutrient for phytoplankton growth. Large phytoplankton blooms can be created by supplying iron to iron-deficient ocean waters. A number of ocean labs, scientists and businesses are exploring fertilization as a means to sequester atmosphericcarbon dioxide in the deep ocean,HP Pavilion DV4-1119TX Battery

and to increase marine biological productivity which is likely in decline as a result ofclimate change. Since 1993, thirteen international research teams have completed ocean trials demonstrating that phytoplankton blooms can be stimulated by iron addition.HP Pavilion DV4-1120BR Battery

However, controversy remains over the effectiveness of atmospheric CO2 sequestration and ecological effects.[2] The most recent open ocean trial of ocean iron fertilization, dubbed LOHAFEX, was conducted from January to March 2009 in the South Atlantic.HP Pavilion DV4-1120TX Battery

Fertilization also occurs naturally when upwellings bring nutrient-rich water to the surface, as occurs when ocean currents meet an ocean bank or a sea mount. This form of fertilization produces the world's largest marine habitats. Fertilization can also occur when weather carries wind blown dust long distances over the ocean, or iron-rich minerals are carried into the ocean byglaciers, rivers and icebergs.HP Pavilion DV4-1120US Battery

Consideration of iron's importance to phytoplankton growth and photosynthesis dates back to the 1930s when English biologist Joseph Hart speculated that the ocean's great "desolate zones" (areas apparently rich in nutrients, but lacking in plankton activity or other sea life) might simply be iron deficient.HP Pavilion DV4-1120US Battery

Little further scientific discussion of this issue was recorded until the 1980s, when oceanographer John Martin renewed controversy on the topic with his marine water nutrient analyses. His studies indicated it was indeed a scarcity of iron micronutrients that was limiting phytoplankton growth and overall productivity in these "desolate" regions, which came to be called "High Nutrient, Low Chlorophyll" (HNLC) zones.HP Pavilion DV4-1121BR Battery

In an article in the scientific journal Nature (February 1988; 331 (6157): 570ff.), John Gribbin was the first scientist to publicly suggest that the upcoming greenhouse effect might be reduced by adding large amounts of soluble iron compounds to the oceans of the world as a fertilizer for the aquatic plants.HP Pavilion DV4-1121CA Battery

Martin's famous 1991 quip three years later at Woods Hole Oceanographic Institution, "Give me a half a tanker of iron and I will give you another ice age",[5][6]drove a decade of research whose findings suggested that iron deficiency was not merely impacting ocean ecosystems, it also offered a key to mitigating climate change as well.HP Pavilion DV4-1121TX Battery

Perhaps the most dramatic support for Martin's hypothesis was seen in the aftermath of the 1991 eruption of Mount Pinatubo in the Philippines.[citation needed]Environmental scientist Andrew Watson analyzed global data from that eruption and calculated that it deposited approximately 40,000 tons of iron dust into the oceans worldwide.HP Pavilion DV4-1122TX Battery

This single fertilization event generated an easily observed global decline in atmospheric CO2 and a parallel pulsed increase in oxygen levels.

Experiments

Martin hypothesized that increasing phytoplankton photosynthesis could slow or even reverse global warming by sequestering enormous volumes of CO2 in the sea. He died shortly thereafter during preparations for Ironex I,HP Pavilion DV4-1123LA Battery

a proof of concept research voyage, which was successfully carried out near the Galapagos Islands in 1993 by his colleagues at Moss Landing Marine Laboratories.

Despite widespread opposition to LOHAFEX, on 26 January 2009 the German Federal Ministry of Education and Research (BMBF) gave clearance for this fertilization experiment to commence.HP Pavilion DV4-1123TX Battery

The experiment was carried out in waters low in silicic acid which is likely to affect the efficacy of carbon sequestration. A 900 square kilometers (350 sq mi) portion of the southwest Atlantic Ocean was fertilized with iron sulfate. A large phytoplankton bloom was triggered, however this bloom did not contain diatoms because the fertilized location was already depleted in silicic acid, an essential nutrient for diatom growth.HP Pavilion DV4-1123US Battery

In the absence of diatoms, a relatively small amount of carbon was sequestered, because other phytoplankton are vulnerable to predation by zooplankton and do not sink rapidly upon death. These poor sequestration results have caused some to suggest that ocean iron fertilization is not an effective carbon mitigation strategy in general.HP Pavilion DV4-1124LA Battery

However, prior ocean fertilization experiments in high silica locations have observed much higher carbon sequestration rates because of diatom growth. LOHAFEX has just confirmed that the carbon sequestration potential depends strongly upon careful choice of location.HP Pavilion DV4-1124NR Battery

The maximum possible result from iron fertilization, assuming the most favourable conditions and disregarding practical considerations, is 0.29W/m2 of globally averaged negative forcing, which is almost sufficient to reverse the warming effect of about 1/6 of current levels of anthropogenic CO2 emissions.HP Pavilion DV4-1124TX Battery

It is notable, however, that the addition of silicic acid or choosing the proper location could, at least mathematically, eliminate and exceed all man made CO2. Further tests and experiments are required to test this theory and observe potential negative impact.HP Pavilion DV4-1125BR Battery

The role of iron

About 70% of the world's surface is covered in oceans, and the upper part of these (where light can penetrate) is inhabited by algae. In some oceans, the growth and reproduction of these algae is limited by the amount of iron in the seawater.HP Pavilion DV4-1125LA Battery

Iron is a vital micronutrient for phytoplankton growth and photosynthesis that has historically been delivered to the pelagic sea by dust storms from arid lands. This Aeolian dust contains 3–5% iron and its deposition has fallen nearly 25% in recent decades.HP Pavilion DV4-1125NR Battery

The Redfield ratio describes the relative atomic concentrations of critical nutrients in plankton biomass and is conventionally written "106 C: 16 N: 1 P." This expresses the fact that one atom of phosphorus and 16 of nitrogen are required to "fix" 106 carbon atoms (or 106 molecules of CO2).HP Pavilion DV4-1125TX Battery

Recent research has expanded this constant to "106 C: 16 N: 1 P: .001 Fe" signifying that in iron deficient conditions each atom of iron can fix 106,000 atoms of carbon,or on a mass basis, each kilogram of iron can fix 83,000 kg of carbon dioxide. The 2004 EIFEX experiment reported a carbon dioxide to iron export ratio of nearly 3000 to 1.HP Pavilion DV4-1126LA Battery

The atomic ratio would be approximately: "3000 C: 58,000 N: 3,600 P: 1 Fe".

Therefore small amounts of iron (measured by mass parts per trillion) in "desolate" HNLC zones can trigger large phytoplankton blooms. Recent marine trials suggest that one kilogram of fine iron particles may generate well over 100,000 kilograms of plankton biomass.HP Pavilion DV4-1126TX Battery

The size of the iron particles is critical, however, and particles of 0.5–1 micrometer or less seem to be ideal both in terms of sink rate and bioavailability. Particles this small are not only easier for cyanobacteriaand other phytoplankton to incorporate, the churning of surface waters keeps them in the euphotic or sunlit biologically active depths without sinking for long periods of time.HP Pavilion DV4-1127LA Battery

Carbon sequestration

Previous instances of biological carbon sequestration have triggered major climatic changes, such as theAzolla event. Plankton that generate calcium or silicon carbonate skeletons, such as diatoms,coccolithophores and foraminifera, account for most direct carbon sequestration.HP Pavilion DV4-1127TX Battery

When these organisms die their carbonate skeletons sink relatively quickly and form a major component of the carbon-rich deep sea precipitation known as marine snow. Marine snow also includes fish fecal pellets and other organic detritus, and can be seen steadily falling thousands of meters below active plankton blooms.HP Pavilion DV4-1128TX Battery

Of the carbon-rich biomass generated by plankton blooms, half (or more) is generally consumed by grazing organisms (zooplankton, krill, small fish, etc.) but 20 to 30% sinks below 200 meters (660 ft) into the colder water strata below the thermocline.HP Pavilion DV4-1129LA Battery

Much of this fixed carbon continues falling into the abyss, but a substantial percentage is redissolved and remineralized. At this depth, however, this carbon is now suspended in deep currents and effectively isolated from the atmosphere for centuries. (The surface to benthic cycling time for the ocean is approximately 4,000 years.)HP Pavilion DV4-1129TX Battery

Analysis and quantification

Evaluation of the biological effects and verification of the amount of carbon actually sequestered by any particular bloom requires a variety of measurements, including a combination of ship-borne and remote sampling, submarine filtration traps, tracking buoy spectroscopy and satellite telemetry.HP Pavilion DV4-1130BR Battery

Unpredictable ocean currents have been known to remove experimental iron patches from the pelagic zone, invalidating the experiment.

The potential of iron fertilization as a geoengineering technique to tackle global warming is illustrated by the following figures.HP Pavilion DV4-1130TX Battery

If phytoplankton converted all the nitrate and phosphate present in the surface mixed layer across the entire Antarctic circumpolar current into organic carbon, the resulting carbon dioxide deficit could be compensated by uptake from the atmosphere amounting to about 0.8 to 1.4 gigatonnes of carbon per year.HP Pavilion DV4-1131BR Battery

This quantity is comparable in magnitude to annual anthropogenic fossil fuels combustion of approximately 6 gigatonnes. It should be noted that the Antarctic circumpolar current region is only one of several in which iron fertilization could be conducted—the Galapagos islands area being another potentially suitable location.HP Pavilion DV4-1131TX Battery

Dimethyl sulfide and clouds

Some species of plankton produce dimethyl sulfide (DMS), a portion of which enters the atmosphere where it is oxidized by hydroxyl radicals (OH), atomic chlorine(Cl) and bromine monoxide (BrO) to form sulfate particles and ultimately clouds.HP Pavilion DV4-1132TX Battery

This may increase the albedo of the planet and so cause cooling. This is the basic tenet of the Gaia hypothesis and was presented in James Lovelock's first paper published on this topic.

During the Southern Ocean Iron Enrichment Experiments (SOFeX), DMS concentrations increased by a factor of four inside the fertilized patch.HP Pavilion DV4-1133TX Battery

Widescale iron fertilization of the Southern Ocean could lead to significant sulfur-triggered cooling in addition to that due to the increased CO2 uptake and that due to the ocean's albedo increase, however the amount of cooling by this particular effect is very uncertain.HP Pavilion DV4-1134TX Battery

Financial opportunities

Since the advent of the Kyoto Protocol, several countries and the European Union have established carbon offset markets which trade certified emission reduction credits (CERs) and other types of carbon credit instruments internationally.HP Pavilion DV4-1135BR Battery

In 2007 CERs sell for approximately €15–20/ton CO2e and European analysts project these prices will nearly double by 2012. Iron fertilization is relatively inexpensive compared to scrubbing, direct injection and other industrial approaches, and can theoretically sequester for less than €5/ton CO2, creating a substantial return.HP Pavilion DV4-1135EE Battery

In August, 2010, Russia established a minimum price of €10/ton for offsets to reduce uncertainty for offset providers. Scientists have reported a minimum 6–12% decline in global plankton production since 1980,A full-scale international plankton restoration program could regenerate approximately 3–5 billion tons of sequestration capacity worth €50-100 billion in carbon offset value.HP Pavilion DV4-1135EI Battery

Given this potential return on investment, carbon traders and offset customers are watching the progress of this technology with interest.

Multilateral reaction

The parties to the London Dumping Convention (Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter 1972) adopted a non-binding resolution in 2008 on fertilization (labeled LC-LP.1(2008)).HP Pavilion DV4-1135TX Battery

The resolution states that ocean fertilization activities, other than legitimate scientific research, "should be considered as contrary to the aims of the Convention and Protocol and do not currently qualify for any exemption from the definition of dumping".

An Assessment Framework for Scientific Research Involving Ocean Fertilization, regulating the dumping of wastes at sea (labeled LC-LP.2(2010)) was adopted by the Contracting Parties to the Convention in October 2010 (LC 32/LP 5).HP Pavilion DV4-1136BR Battery

Sequestration definitions

Carbon is not considered "sequestered" unless it settles to the ocean floor where it remains for eons. Most of the carbon that sinks beneath plankton blooms is dissolved and remineralized well above the seafloor and will eventually (days to centuries) return to the atmosphere, negating the original effect.HP Pavilion DV4-1136TX Battery

Advocates argue that modern climate scientists and Kyoto Protocol policy makers define sequestration in much shorter time frames. For example, they recognize trees and grasslands as important carbon sinks. Forest biomass only sequesters carbon for decades, but carbon that sinks below the marine thermocline (100–200 meters)HP Pavilion DV4-1137TX Battery

is effectively removed from the atmosphere for hundreds of years, whether it is remineralized or not. Since deep ocean currents take so long to resurface, their carbon content is effectively sequestered by the criterion in use today.

Debate

While many advocates of ocean iron fertilization see it as modern society's last best hope to slow global warming, some academics, deep greens and proponents of competing technologies cite a variety of concerns.HP Pavilion DV4-1138TX Battery

Precautionary principle

The precautionary principle (PP) states that if an action or policy has a suspected risk of causing harm, in the absence of scientific consensus, the burden of proofthat it is not harmful falls on those who would take the action. The side effects of large-scale iron fertilization are not yet known.HP Pavilion DV4-1139TX Battery

Creating phytoplankton blooms in naturally iron-poor areas of the ocean is like watering the desert: in effect it changes one type of ecosystem into another. Such large and rapid conversions have no precedent.

The argument can be applied in reverse, by considering emissions to be the action and remediation an attempt to partially offset the damage.HP Pavilion DV4-1140EK Battery

20th century phytoplankton decline

While advocates argue that iron addition would help to reverse a supposed decline in phytoplankton, this decline may not be real. One study reported a decline in ocean productivity comparing the 1979–1986 and 1997–2000 periods,[35] but two others found increases in phytoplankton.HP Pavilion DV4-1140GO Battery

Comparison to prior phytoplankton cycles

Fertilization advocates respond that similar algal blooms have occurred naturally for millions of years with no observed ill effects. The Azolla event occurred around 49 million years ago and accomplished what fertilization is intended to achieve (but on a larger scale).HP Pavilion DV4-1140TX Battery

Sequestration efficiency

Fertilization may sequester too little carbon per bloom, supporting the food chain rather than raining on the ocean floor, and thus require too many seeding voyages to be practical. A 2009 Indo-German team of scientists examined the potential of the south-western Atlantic to sequester significant amounts of carbon dioxide, but found few positive results.HP Pavilion DV4-1141TX Battery

The counter-argument to this is that the low sequestration estimates that emerged from some ocean trials are largely due to these factors:

  1. Data: none of the ocean trials had enough boat time to monitor their blooms for more than 27 days, confining their measurements to that period. Blooms generally last 60–90 days with the heaviest "precipitation" occurring during the last two months.HP Pavilion DV4-1142TX Battery
  2. Scale: most trials used less than 1,000 kilograms (2,200 lb) of iron and thus created small blooms that were quickly devoured by opportunistic zooplankton, krill, and fish that swarmed into the seeded region.HP Pavilion DV4-1143GO Battery

Some ocean trials reported positive results. IronEx II reported conversion of 1,000 kilograms (2,200 lb) to carbonaceous biomass equivalent to one hundred full-grownredwoods within two weeks. Eifex recorded fixation ratios of nearly 300,000 to 1.HP Pavilion DV4-1143TX Battery

Current estimates of the amount of iron required to restore all the lost plankton and sequester 3 gigatons/year of CO2 range widely, from approximately 2 hundred thousand tons/year to over 4 million tons/year. The latter scenario involves 16 supertanker loads of iron and a projected cost of approximately €20 billion ($27 billion).HP Pavilion DV4-1144TX Battery

Ecological issues

Critics are concerned that fertilization will create harmful algal blooms (HAB). The species that respond most strongly to fertilization vary by location and other factors and could possibly include species that cause red tides and other toxic phenomena.HP Pavilion DV4-1144US Battery

These factors affect only near-shore waters, although they show that increased phytoplankton populations are not universally benign.

Most species of phytoplankton are harmless or beneficial, given that they constitute the base of the marine food chain.HP Pavilion DV4-1145BR Battery

Fertilization increases phytoplankton only in the deep oceans (far from shore) where iron deficiency is the problem. Most coastal waters are replete with iron and adding more has no useful effect.

A 2010 study of iron fertilization in an oceanic high-nitrate, low-chlorophyll environment, however, found that fertilizedPseudo-nitzschia diatom spp.,HP Pavilion DV4-1145GO Battery

which are generally nontoxic in the open ocean, began producing toxic levels of domoic acid. Even short-lived blooms containing such toxins could have detrimental effects on marine food webs.

Deep water oxygen levels

When organic bloom detritus sinks into the abyss, a significant fraction will be devoured by bacteria, other microorganisms and deep sea animals which also consume oxygen.HP Pavilion DV4-1145TX Battery

A large enough bloom could render certain regions of the sea deep beneath it anoxic and threaten other benthic species.

The largest plankton replenishment projects under consideration are less than 10% the size of most natural wind-fed blooms.HP Pavilion DV4-1146TX Battery

In the wake of major dust storms, natural blooms have been studied since the beginning of the 20th century and no such deep water dieoffs have been reported.

Ecosystem effects

Depending upon the composition and timing of delivery, iron infusions could preferentially favor certain species and alter surface ecosystems to unknown effect.HP Pavilion DV4-1147CL Battery

Population explosions of jellyfish, disturbance of the food chain impacting whale populations or fisheries are potential risks.

A 2010 study shows that iron enrichment stimulates toxic diatom production in high-nitrate, low-chlorophyll areas  , which, the authors argue, raises "serious concerns over the net benefit and sustainability of large-scale iron fertilizations".HP Pavilion DV4-1147TX Battery

However, CO2-induced surface water heating and rising carbonic acidity are already shifting population distributions for phytoplankton, zooplankton and many other creatures. Optimal fertilization could potentially help restore lost/threatened ecosystem services.HP Pavilion DV4-1148TX Battery

Conclusion and further research

Critics and advocates generally agree that most questions on the impact, safety and efficacy of ocean iron fertilization can only be answered by much larger studies.HP Pavilion DV4-1149TX Battery

A statement published in Science in 2008 maintained that it would be premature to sell carbon offsets from the first generation of commercial-scale OIF experiments unless there is better demonstration that OIF effectively removes CO2, retains that carbon in the ocean for a quantifiable amount of time, and has acceptable and predictable environmental impacts.HP Pavilion DV4-1150BR Battery

One pilot project planned by Planktos, a U.S. company, was cancelled in 2008 for lack of funding. The company blamed environmental organizations for the failure.

Iron has a long and varied tradition in the mythology and folklore of the world.HP Pavilion DV4-1150EO Battery

As human blood smells of the iron which its cells contain, and blood in many traditions is equated with the life-force, so iron and minerals have been considered to be the blood or life-force of the Earth. This relationship is charted further in literature on geomancy, ley lines and songlines.HP Pavilion DV4-1150EP Battery

Fred Hoyle's observation of stellar formation champions iron as the core of celestial bodies.

In Plutarch's mystical writings, iron and lodestone is referred to as the 'bone' or 'core' of the gods. Symbolically, iron is the bone, the foundation or the mineral core of both blood and red ochre.HP Pavilion DV4-1150ER Battery

Cold iron is a poetic and archaic term for iron, referring to the fact that it feels cold to the touch. In modern usage the term has been most associated with folkloric beliefs that iron could ward off ghosts, fairies, witches, and/or other malevolent supernatural creatures.HP Pavilion DV4-1150ES Battery

Francis Grose's 1811 Dictionary of the Vulgar Tongue defines cold iron as "A sword, or any other weapon for cutting or stabbing." This usage often appears as "cold steel" in modern parlance.

"Cold iron" is sometimes asserted to repel, contain, or harm ghosts, fairies, witches, and/or other malevolent supernatural creatures. This belief continued into later superstitions in a number of forms:HP Pavilion DV4-1150TX Battery

  • Nailing an iron horseshoe to a door was said to repel evil spirits or later, to bring good luck.
  • Surrounding a cemetery with an iron fence was thought to contain the souls of the dead.
  • Burying an iron knife under the entrance to one's home was alleged to keep witches from entering.HP Pavilion DV4-1151TX Battery

In his story, Redgauntlet, the Scottish author Sir Walter Scott wrote, "Your wife's a witch, man; you should nail a horse-shoe on your chamber-door."

Rudyard Kipling's poem "Cold Iron", found in his 1910 collection of stories Rewards and Fairies, used the term poetically to mean 'weapon'.HP Pavilion DV4-1152TX Battery

Faeries and iron

Iron, particularly "Cold iron", was employed as a protective substance or charm against faeries. In various folklores, supernatural creatures are held to hold an aversion to iron or even be harmed by the touch of iron. Conversely, amongst Asian traditions, there are tales of ironworking fairies.HP Pavilion DV4-1153TX Battery

For luck

Horseshoes are considered a good luck charm in many cultures, including those of England, Denmark  and Estonia, and its shape, fabrication, placement and manner of sourcing are all important. A common tradition is that if a horseshoe is hung on a door with the two ends pointing up (as shown here) then good luck will occur.HP Pavilion DV4-1154TX Battery

However, if the two ends point downwards then bad luck will occur. Traditions do differ on this point, though. In some cultures, the horseshoe is hung points down (so the luck pours onto you); in others, it is hung points up (so the luck doesn't fall out); still in others it doesn't matter so long as the horseshoe has been used (not new), was found (not purchased), and can be touched.HP Pavilion DV4-1155SE Battery

In all traditions, luck is contained in the shoe and canpour out through the ends.

In some traditions, any good or bad luck achieved will only occur to the owner of the horseshoe, not the person who hangs it up. Therefore, if the horseshoe was stolen, borrowed or even just found then the owner, not the person who found or stole the horseshoe will get any good or bad luck.HP Pavilion DV4-1155TX Battery

Other traditions require that the horseshoe be found to be effective.

One reputed origin of the tradition of lucky horseshoes is the story of Saint Dunstan and the Devil. Dunstan, who would become the Archbishop of Canterbury in AD 959, was a blacksmith by trade.HP Pavilion DV4-1156TX Battery

The story relates that he once nailed a horseshoe to the Devil's hoof when he was asked to reshoe the Devil's horse. This caused the Devil great pain, and Dunstan only agreed to remove the shoe and release the Devil after the Devil promised never to enter a place where a horseshoe is hung over the door.HP Pavilion DV4-1157TX Battery

Another theory concerning the placing of horseshoes above doorways is to ward off Faeries; the theory being that supernatural beings are repelled by iron and as horseshoes were an easily available source of iron, they could be nailed above a door to prevent any unwanted, otherworldly guests.HP Pavilion DV4-1158TX Battery

Meteoric Iron in Tibet

Thogcha means 'sky-iron' in Tibetan. Meteoric iron was highly prized throughout the Himalayas where it was included in sophisticated polymetallic alloys for ritual implements such as the singing bowl (Jansen, 1992) and phurba (Müller-Ebeling, et al., 2002).HP Pavilion DV4-1159TX Battery

Beer (1999: p. 234) holds that:

"Meteoric iron or 'sky-iron' (Tib. gnam lcags) is the supreme substance for forging the physical representation of the vajra or other iron weapons, since it has already been tempered by the celestial gods in its passage across the heavens.HP Pavilion DV4-1160ES Battery

The indivisibility of form and emptiness is a perfect metaphor for the image of a meteorite or 'stone fallen from the sky', manifesting out of the voidness of space as a shooting star or fireball, and depositing a chunk of fused 'sky iron' on the earth below.HP Pavilion DV4-1160TX Battery

Many vajras held by deities as weapons are described as being forged from meteorite iron, and Tibet, with its high altitude, thin atmosphere and desolate landscape, received an abundance of meteorite fragments. Tibetan vajras were often cast from meteorite iron, and as an act of sympathetic magic a piece of the meteoric iron was often returned to its original site."HP Pavilion DV4-1161TX Battery

Blood and ochre

In many indigenous Australian Aboriginal peoples' traditions ochre and blood, both high in iron content and considered Maban, are applied to the bodies of dancers for ritual. As Lawlor (1991: p. 102-103) states:HP Pavilion DV4-1162TX Battery

In many Aboriginal rituals and ceremonies, red ochre is rubbed all over the naked bodies of the dancers. In secret, sacred male ceremonies, blood extracted from the veins of the participant's arms is exchanged and rubbed on their bodies. Red ochre is used in similar ways in less secret ceremonies.HP Pavilion DV4-1163TX Battery

Blood is also used to fasten the feathers of birds onto people's bodies. Bird feathers contain a protein that is highly magnetically sensitive.

Lawlor comments that blood employed in this fashion is held by these peoples to attune the dancers to the invisible energetic realm of the Dreamtime. HP Pavilion DV4-1164TX Battery

Lawlor then draws information from different disciplines charting a relationship between these invisible energetic realms and magnetic fields. Iron and magnetism having a marked relationship.HP Pavilion DV4-1165TX Battery

Songlines, magnetic fields and wayfinding

Lawlor (1991: p. 105) quotes the biophysicists F. A. Brown and F. H. Barnwell who have conducted research on the biological effects of the Earth's magnetic field (and particularly how it relates with directionality and wayfinding):HP Pavilion DV4-1166CA Battery

There remains no reasonable doubt that living systems are extraordinarily sensitive to magnetic fields. By extremely simple experiments it is shown that highly diverse plants and animals may have their orientation modified by artificial fields of the order of strength of the geo-magnetic field...HP Pavilion DV4-1166TX Battery

The nature of the response properties suggest that the organism is normally integrated with its geo-magnetic environment to a striking degree.

Lawlor then builds on this with citing research conducted on homing pigeons which has pinpointed a tiny crystal in their brain.HP Pavilion DV4-1167TX Battery

This crystal which is supersensitive to the Earth's magnetic fields or geomagnetic currents, works in tandem with the birds other wayfinding propensities. As Mathrani (2002) states:

Many animals have the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information.HP Pavilion DV4-1168TX Battery

Studies have shown that salamanders and frogs use magnetic fields for orientation when they have to find a way to escape from danger, such as from predators. Other animals that have been known to migrate via the detection of the Earth's magnetic field include sparrows, pigeons, bobolinks, yellow fin tuna fish, honeybees, and bacteria.HP Pavilion DV4-1169TX Battery

Magnetite has been found in the tissues of all these organisms.

Crystals of magnetite have been found in some bacteria (e.g., Magnetospirillum magnetotacticum) and in the brains of bees, of termites, of some birds (e.g., thepigeon), and of humans.HP Pavilion DV4-1180BR Battery

These crystals are thought to be involved in magnetoreception, the ability to sense the polarity or the inclination of the Earth's magnetic field, and to be involved in navigation. Also, chitons have teeth made of magnetite on their radula making them unique among animals. This means they have an exceptionally abrasive tongue with which to scrape food from rocks.HP Pavilion DV4-1190BR Battery

The study of biomagnetism began with the discoveries of Caltech paleoecologist Heinz Lowenstam in the 1960s.HP Pavilion DV4-1190EA Battery,HP Pavilion DV4-1190EJ Battery,HP Pavilion DV4-1190EL Battery,HP Pavilion DV4-1198ER Battery,HP Pavilion DV4-1199EA Battery

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Production

Approximately 4.4 million metric tons of marketable chromite ore were produced in 2000, and converted into ~3.3 million tons of ferro-chrome with an approximate market value of 2.5 billion United States dollars.HP Pavilion DV4-1254TX Battery

The largest producers of chromium ore have been South Africa (44%) India (18%),Kazakhstan (16%) Zimbabwe (5%), Finland (4%) Iran (4%) and Brazil (2%) with several other countries producing the rest of less than 10% of the world production.

The two main products of chromium ore refining are ferrochromium and metallic chromium.HP Pavilion DV4-1255TX Battery

For those products the ore smelter process differs considerably. For the production of ferrochromium, the chromite ore (FeCr2O4) is reduced in large scale in electric arc furnace or in smaller smelters with either aluminium or silicon in an aluminothermic reaction.HP Pavilion DV4-1256TX Battery

For the production of pure chromium, the iron has to be separated from the chromium in a two step roasting and leaching process. The chromite ore is heated with a mixture of calcium carbonateand sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms the stable Fe2O3.HP Pavilion DV4-1257TX Battery

The subsequent leaching at higher elevated temperatures dissolves the chromates and leaves the insoluble iron oxide. The chromate is converted by sulfuric acid into the dichromate.

4 FeCr2O4 + 8 Na2CO3 + 7 O2 ? 8 Na2CrO4 + 2 Fe2O3 + 8 CO2

2 Na2CrO4 + H2SO4 ? Na2Cr2O7 + Na2SO4 + H2O

The dichromate is converted to the chromium(III) oxide by reduction with carbon and then reduced in an aluminothermic reaction to chromium.HP Pavilion DV4-1258TX Battery

Na2Cr2O7 + 2 C ? Cr2O3 + Na2CO3 + CO

Cr2O3 + 2 Al ? Al2O3 + 2 Cr

Metallurgy

The strengthening effect of forming stable metal carbides at the grain boundaries and the strong increase in corrosion resistance made chromium an important alloying material for steel.HP Pavilion DV4-1259TX Battery

The high speed tool steels contain between 3 and 5% chromium. Stainless steel, the main corrosion-proof metal alloy, is formed when chromium is added to iron in sufficient concentrations, usually above 11%. For its formation, ferrochromium is added to the molten iron.HP Pavilion DV4-1260TX Battery

Also nickel-based alloys increase in strength due to the formation of discrete, stable metal carbide particles at the grain boundaries. For example, Inconel 718 contains 18.6% chromium. Because of the excellent high temperature properties of these nickel superalloys, they are used in jet engines and gas turbines in lieu of common structural materials.HP Pavilion DV4-1265DX Battery

The relative high hardness and corrosion resistance of unalloyed chromium makes it a good surface coating, being still the most "popular" metal coating with unparalleled combined durability. A thin layer of chromium is deposited on pretreated metallic surfaces by electroplating techniques.HP Pavilion DV4-1272CM Battery

There are two deposition methods: Thin, below 1 µm thickness, layers are deposited bychrome plating, and are used for decorative surfaces. If wear-resistant surfaces are needed then thicker chromium layers are deposited. Both methods normally use acidic chromate or dichromate solutions.HP Pavilion DV4-1275MX Battery

To prevent the energy consuming change in oxidation state, the use of Chromium(III) sulfate is under development, but for most applications, the established process is used.

In the chromate conversion coating process, the strong oxidative properties of chromates are used to deposit a protective oxide layer on metals like aluminium, zinc and cadmium.HP Pavilion DV4-1280US Battery

This passivation and the self healing properties by the chromate stored in the chromate conversion coating, which is able to migrate to local defects, are the benefits of this coating method.[31] Because of environmental and health regulations on chromates, alternative coating method are under development.HP Pavilion DV4-1281US Battery

Anodizing of aluminium is another electrochemical process, which does not lead to the deposition of chromium, but uses chromic acid as electrolyte in the solution. During anodization, an oxide layer is formed on the aluminium. The use of chromic acid, instead of the normally used sulfuric acid, leads to a slight difference of these oxide layers.HP Pavilion DV4-1282CM Battery

The high toxicity of Cr(VI) compounds, used in the established chromium electroplating process, and the strengthening of safety and environmental regulations demand a search for substitutes for chromium or at least a change to less toxic chromium(III) compounds.HP Pavilion DV4-1283CL Battery

Dye and pigment

The mineral crocoite (lead chromate PbCrO4) was used as a yellow pigment shortly after its discovery. After a synthesis method became available starting from the more abundant chromite, chrome yellow was, together with cadmium yellow, one of the most used yellow pigments.HP Pavilion DV4-1287CL Battery

The pigment does not photo degrade and has a strong color, and was used for school buses in the US and for Postal Service (for example Deutsche Post) in Europe. The use of chrome yellow declined due to environmental and safety concerns and was replaced by organic pigments or other lead-free alternatives.HP Pavilion DV4-1290BR Battery

Other pigments based on chromium are, for example, the bright red pigment chrome red, which is a basic lead chromate (PbCrO4·Pb(OH)2). Chrome green is a mixture of Prussian blue and chrome yellow, while the chrome oxide green is Chromium(III) oxide.HP Pavilion DV4-1290EL Battery

A red color is achieved by doping chromium(III) into the crystals of corundum, which are then called ruby. Therefore, chromium is used in producing synthetic rubies.[36]

Chromium oxides are also used as a green color in glassmaking and as a glaze in ceramics.HP Pavilion DV4-1292CM Battery

Wood preservative

Because of their toxicity, chromium(VI) salts are used for the preservation of wood. For example, chromated copper arsenate (CCA) is used in timber treatment to protect wood from decay fungi, wood attacking insects, including termites, and marine borers.HP Pavilion DV4-1299EE Battery

The formulations contain chromium based on the oxide CrO3 between 35.3% and 65.5%. In the United States, 65,300 metric tons of CCA solution have been used in 1996.[38]

Tanning

Chromium(III) salts, especially chrome alum and chromium(III) sulfate, are used in the tanning of leather.HP Pavilion DV4-1300 CTO Battery

The chromium(III) stabilizes the leather by cross linking the collagen fibers.  Chromium tanned leather can contain between 4 and 5% of chromium, which is tightly bound to the proteins. Although the form of chromium used for tanning is not the toxic hexavalent variety,HP Pavilion DV4-1301TU Battery

there remains interest in management of chromium in the tanning industry such as recovery and reuse, direct/indirect recycling, use of less chromium or "chrome-less" tanning are practised to better manage chromium in tanning.HP Pavilion DV4-1301TX Battery

Refractory material

The high heat resistivity and high melting point makes chromite and chromium(III) oxide a material for high temperature refractory applications, like blast furnaces, cement kilns, molds for the firing of bricks and as foundry sands for the casting of metals.HP Pavilion DV4-1302TU Battery

In these applications, the refractory materials are made from mixtures of chromite and magnesite. The use is declining because of the environmental regulations due to the possibility of the formation of chromium(VI).

Catalysts

Several chromium compounds are used as catalysts for processing hydrocarbons.HP Pavilion DV4-1302TX Battery

For example the Phillips catalysts for the production of polyethylene are mixtures of chromium and silicon dioxide or mixtures of chromium and titanium and aluminium oxide.[41] Fe-Cr mixed oxides are employed as high-temperature catalysts for thewater gas shift reaction. Copper chromite is a useful hydrogenation catalyst.HP Pavilion DV4-1303TU Battery

Other use

  • Chromium(IV) oxide (CrO2) is a magnetic compound. Its ideal shape anisotropy, which imparts high coercivity and remanent magnetization, made it a compound superior to the ?-Fe2O3. Chromium(IV) oxide is used to manufacture magnetic tape used in high-performance audio tape and standard audio cassettes.HP Pavilion DV4-1303TX Battery
  • Chromates can prevent corrosion of steel under wet conditions, and therefore chromates are added to drilling muds.
  • Chromium(III) oxide is a metal polish known as green rouge.HP Pavilion DV4-1304TU Battery
  • Chromic acid is a powerful oxidizing agent and is a useful compound for cleaning laboratory glassware of any trace of organic compounds. It is prepared in situ by dissolving potassium dichromate in concentrated sulfuric acid, which is then used to wash the apparatus.HP Pavilion DV4-1304TX Battery
  • Sodium dichromate is sometimes used because of its higher solubility (50 g/L versus 200 g/L respectively). Potassium dichromate is a chemical reagent, used in cleaning laboratory glassware and as a titrating agent. It is also used as a mordant (i.e., a fixing agent) for dyes in fabric.HP Pavilion DV4-1305TU Battery

Biological role

Chromium has no verified biological role and has been classified as not essential for mammals. (Cr(III) or Cr3+) occurs in trace amounts and appears to be benign. Chromium deficiency is controversial or is at least extremely rare.HP Pavilion DV4-1305TX Battery

It has been attributed to only three people on parenteral nutrition, which is when a patient is fed a liquid diet through intravenous drips. In contrast, hexavalent chromium (Cr(VI) or Cr6+) is very toxic and mutagenic when inhaled. Cr(VI) has not been established as a carcinogen when in solution, although it may cause allergic contact dermatitis (ACD).HP Pavilion DV4-1306TU Battery

Although no biological role for chromium has ever been demonstrated, dietary supplements for chromium include chromium(III) picolinate, chromium(III) polynicotinate, and related materials. The benefit of those supplements is still under investigation and is questioned by some studies.HP Pavilion DV4-1306TX Battery

The use of chromium-containing dietary supplements is controversial owing to the absence of any verified biological role, the expense of these supplements, and the complex effects of their use.  The popular dietary supplement chromium picolinate complex generates chromosome damage in hamster cells.HP Pavilion DV4-1307TU Battery

In the United States the dietary guidelines for daily chromium uptake were lowered from 50–200 µg for an adult to 35 µg (adult male) and to 25 µg (adult female).

Precautions

Water insoluble chromium(III) compounds and chromium metal are not considered a health hazard, while the toxicity and carcinogenic properties of chromium(VI) have been known for a long time.HP Pavilion DV4-1307TX Battery

Because of the specific transport mechanisms, only limited amounts of chromium(III) enter the cells. Several in vitro studies indicated that high concentrations of chromium(III) in the cell can lead to DNA damage.[57] Acute oral toxicity ranges between 1.5 and 3.3 mg/kg.HP Pavilion DV4-1308TU Battery

The proposed beneficial effects of chromium(III) and the use as dietary supplements yielded some controversial results, but recent reviews suggest that moderate uptake of chromium(III) through dietary supplements poses no risk.

The acute oral toxicity for chromium(VI) ranges between 50 and 150 µg/kg.HP Pavilion DV4-1308TX Battery

In the body, chromium(VI) is reduced by several mechanisms to chromium(III) already in the blood before it enters the cells. The chromium(III) is excreted from the body, whereas the chromate ion is transferred into the cell by a transport mechanism, by which also sulfate and phosphate ions enter the cell.HP Pavilion DV4-1309TU Battery

The acute toxicity of chromium(VI) is due to its strong oxidational properties. After it reaches the blood stream, it damages the kidneys, the liver and blood cells through oxidation reactions. Hemolysis, renal and liver failure are the results of these damages. Aggressive dialysis can improve the situation.HP Pavilion DV4-1309TX Battery

The carcinogenity of chromate dust is known for a long time, and in 1890 the first publication described the elevated cancer risk of workers in a chromate dye company. Three mechanisms have been proposed to describe the genotoxicity of chromium(VI).HP Pavilion DV4-1310TU Battery

The first mechanism includes highly reactive hydroxyl radicals and other reactive radicals which are by products of the reduction of chromium(VI) to chromium(III). The second process includes the direct binding of chromium(V), produced by reduction in the cell, and chromium(IV) compounds to the DNA.HP Pavilion DV4-1310TX Battery

The last mechanism attributed the genotoxicity to the binding to the DNA of the end product of the chromium(III) reduction.

Chromium salts (chromates) are also the cause of allergic reactions in some people. Chromates are often used to manufacture, amongst other things, leather products, paints, cement, mortar and anti-corrosives.HP Pavilion DV4-1311TU Battery

Contact with products containing chromates can lead to allergic contact dermatitis and irritant dermatitis, resulting in ulceration of the skin, sometimes referred to as "chrome ulcers". This condition is often found in workers that have been exposed to strong chromate solutions in electroplating, tanning and chrome-producing manufacturers.HP Pavilion DV4-1311TX Battery

Environmental issues

As chromium compounds were used in dyes and paints and the tanning of leather, these compounds are often found in soil and groundwater at abandoned industrial sites, now needing environmental cleanup and remediation per the treatment of brownfield land.HP Pavilion DV4-1312TU Battery

Primer paint containing hexavalent chromium is still widely used foraerospace and automobile refinishing applications.

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature (often in combination with iron), and in many minerals.HP Pavilion DV4-1312TX Battery

As a free element, manganese is a metal with important industrial metal alloy uses, particularly in stainless steels.

Historically, manganese is named for various black minerals (such as pyrolusite) from the same region of Magnesia in Greece which gave names to similar-sounding magnesia and magnetite, which are ores of different elements.HP Pavilion DV4-1313DX Battery

By the mid-18th century the Swedish chemist Carl Wilhelm Scheele used pyrolusite to produce chlorine. Scheele and others were aware that pyrolusite (now known to be manganese dioxide) contained a new element, but they were not able to isolate it.HP Pavilion DV4-1313TU Battery

Johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, by reducing the dioxide with carbon.

Manganese phosphating is used as a treatment for rust and corrosion prevention on steel. Depending on their oxidation state, manganese ions have various colors and are used industrially as pigments. HP Pavilion DV4-1313TX Battery

The permanganates of alkali and alkaline earth metals are powerful oxidizers. Manganese dioxide is used as the cathode (electron acceptor) material in standard and alkaline disposable dry cells and batteries.

Manganese(II) ions function as cofactors for a large variety of enzymes with many functions.HP Pavilion DV4-1314TU Battery

Manganese enzymes are particularly essential in detoxification of superoxide free radicals in organisms that must deal with elemental oxygen. Manganese also functions in the oxygen evolving complex of photosynthetic plants. The element is a required trace mineral for all known living organisms.HP Pavilion DV4-1314TX Battery

In larger amounts, and apparently with far greater activity by inhalation, manganese can cause apoisoning syndrome in mammals, with neurological damage which is sometimes irreversible.

Manganese is a silvery-gray metal resembling iron. It is hard and very brittle, difficult to fuse, but easy to oxidize.[1] Manganese metal and its common ions are paramagnetic.HP Pavilion DV4-1315TU Battery

Naturally occurring manganese is composed of 1 stable isotope, 55Mn. Eighteen radioisotopeshave been characterized with the most stable being 53Mn with a half-life of 3.7 million years, 54Mn with a half-life of 312.3 days, and 52Mn with a half-life of 5.591 days.HP Pavilion DV4-1315TX Battery

All of the remaining radioactive isotopes have half-lives that are less than 3 hours and the majority of these have half-lives that are less than 1 minute. This element also has 3 meta states.

Manganese is part of the iron group of elements, which are thought to be synthesized in large stars shortly before thesupernova explosion.?HP Pavilion DV4-1316TU Battery

53Mn decays to 53Cr with a half-life of 3.7 million years. Because of its relatively short half-life,53Mn occurs only in tiny amounts due to the action of cosmic rays on iron in rocks.  Manganese isotopic contents are typically combined with chromium isotopic contents and have found application in isotope geology and radiometric dating.HP Pavilion DV4-1316TX Battery

Mn–Cr isotopic ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn–Cr isotopic composition must result from in–situ decay of 53Mn in differentiated planetary bodies.HP Pavilion DV4-1317TU Battery

Hence 53Mn provides additional evidence for nucleosynthetic processes immediately before coalescence of the solar system.

The isotopes of manganese range in atomic weight from 46 u (46Mn) to 65 u (65Mn). The primary decay mode before the most abundant stable isotope, 55Mn, is electron capture and the primary mode after is beta decay.HP Pavilion DV4-1317TX Battery

Chemical properties

The most common oxidation states of manganese are +2, +3, +4, +6 and +7, though oxidation states from ?3 to +7 are observed. Mn2+ often competes with Mg2+ in biological systems.HP Pavilion DV4-1318TU Battery

Manganese compounds where manganese is in oxidation state +7, which are restricted to the unstable oxide Mn2O7 and compounds of the intensely purple permanganate anion MnO4?, are powerful oxidizing agents.  Compounds with oxidation states +5 (blue) and +6 (green) are strong oxidizing agents and are vulnerable todisproportionation.HP Pavilion DV4-1318TX Battery

The most stable oxidation state for manganese is +2, which has a pale pink color, and many manganese(II) compounds are known, such as manganese(II) sulfate (MnSO4) and manganese(II) chloride(MnCl2). This oxidation state is also seen in the mineral rhodochrosite, (manganese(II) carbonate).HP Pavilion DV4-1319TU Battery

The +2 oxidation state is the state used in living organisms for essential functions; other states are toxic for the human body. The +2 oxidation of Mn results from removal of the two 4s electrons, leaving a "high spin" ion in which all five of the 3d orbitals contain a single electron.HP Pavilion DV4-1319TX Battery

Absorption of visible light by this ion is accomplished only by a spin-forbidden transition in which one of the d electrons must pair with another, to give the atom a change in spin of two units. The unlikeliness of such a transition is seen in the uniformly pale and almost colorless nature of Mn(II) compounds relative to other oxidation states of manganese.HP Pavilion DV4-1320CA Battery

The +3 oxidation state is known in compounds like manganese(III) acetate, but these are quite powerfuloxidizing agents and also prone to disproportionation in solution to manganese(II) and manganese(IV). Solid compounds of manganese(III) are characterized by their preference for distorted octahedral coordination due to the Jahn-Teller effect and its strong purple-red color.HP Pavilion DV4-1320TX Battery

The oxidation state 5+ can be obtained if manganese dioxide is dissolved in molten sodium nitrite. Manganate (VI) salts can also be produced by dissolving Mn compounds, such as manganese dioxide, in molten alkali while exposed to air.

Permanganate (+7 oxidation state) compounds are purple, and can give glass a violet color. HP Pavilion DV4-1321TX Battery

Potassium permanganate, sodium permanganateand barium permanganate are all potent oxidizers. Potassium permanganate, also called Condy's crystals, is a commonly used laboratory reagent because of its oxidizing properties and finds use as a topical medicine (for example, in the treatment of fish diseases).HP Pavilion DV4-1322TX Battery

Solutions of potassium permanganate were among the first stains and fixatives to be used in the preparation of biological cells and tissues for electron microscopy.

The origin of the name manganese is complex. In ancient times, two black minerals from Magnesia in what is now modern Greece, were both called magnes from their place of origen, but were thought to differ in gender.HP Pavilion DV4-1322US Battery

The male magnes attracted iron, and was the iron ore we now know as lodestone or magnetite, and which probably gave us the term magnet. The female magnes ore did not attract iron, but was used to decolorize glass. This feminine magnes was later called magnesia, known now in modern times as pyrolusiteor manganese dioxide.HP Pavilion DV4-1323TX Battery

Neither this mineral nor manganese itself is magnetic. In the 16th century, manganese dioxide was called manganesum (note the two n's instead of one) by glassmakers, possibly as a corruption and concatenation of two words, since alchemists and glassmakers eventually had to differentiate a magnesia negra (the black ore) from magnesia alba HP Pavilion DV4-1324TX Battery

(a white ore, also from Magnesia, also useful in glassmaking). Michele Mercati called magnesia negra Manganesa, and finally the metal isolated from it became known as manganese (German: Mangan). The name magnesia eventually was then used to refer only to the white magnesia alba (magnesium oxide), which provided the name magnesium for that free element, when it was eventually isolated, much later.HP Pavilion DV4-1325TX Battery

Several oxides of manganese, for example manganese dioxide, are abundant in nature and due to color these oxides have been used as since the Stone Age. The cave paintings in Gargas contain manganese as pigments and these cave paintings are 30,000 to 24,000 years old.HP Pavilion DV4-1326TX Battery

Manganese compounds were used by Egyptian and Roman glassmakers, to either remove color from glass or add color to it. The use as glassmakers soap continued through the middle ages until modern times and is evident in 14th century glass from Venice.HP Pavilion DV4-1327TX Battery

Because of the use in glassmaking, manganese dioxide was available to alchemists, the first chemists, and was used for experiments. Ignatius Gottfried Kaim (1770) and Johann Glauber(17th century) discovered that manganese dioxide could be converted to permanganate, a useful laboratory reagent.HP Pavilion DV4-1328TX Battery

By the mid-18th century the Swedish chemist Carl Wilhelm Scheele used manganese dioxide to produce chlorine. First hydrochloric acid, or a mixture of dilutesulfuric acid and sodium chloride was reacted with manganese dioxide, later hydrochloric acid from the Leblanc process was used and the manganese dioxide was recycled by the Weldon process.HP Pavilion DV4-1329TX Battery

The production of chlorine and hypochlorite containing bleaching agents was a large consumer of manganese ores.

Scheele and other chemists were aware that manganese dioxide contained a new element, but they were not able to isolate it. Johan Gottlieb Gahn was the first to isolate an impure sample of manganese metal in 1774, by reducing the dioxide with carbon.HP Pavilion DV4-1330TX Battery

The manganese content of some iron ores used in Greece led to the speculations that the steel produced from that ore contains inadvertent amounts of manganese making the Spartan steel exceptionally hard. Around the beginning of the 19th century, manganese was used in steelmaking and several patents were granted.HP Pavilion DV4-1331TX Battery

In 1816, it was noted that adding manganese to iron made it harder, without making it any more brittle. In 1837, British academic James Couper noted an association between heavy exposures to manganese in mines with a form of Parkinson's Disease.HP Pavilion DV4-1332TX Battery

In 1912, manganese phosphating electrochemical conversion coatings for protecting firearms against rust and corrosion were patented in the United States, and have seen widespread use ever since.

The invention of the Leclanché cell in 1866 and the subsequent improvement of the batteries containing manganese dioxide as cathodic depolarizer increased the demand of manganese dioxide.HP Pavilion DV4-1365DX Battery

Until the introduction of the nickel-cadmium battery and lithium containing batteries, most batteries contained manganese. The zinc-carbon battery and the alkaline battery normally use industrially produced manganese dioxide, because natural occurring manganese dioxide contains impurities.HP Pavilion DV4-1400 CTO Battery

In the 20th century, manganese dioxide has seen wide commercial use as the chief cathodic material for commercial disposable dry cells and dry batteries of both the standard (zinc-carbon) and alkaline types.

Occurrence and production

Manganese makes up about 1000 ppm (0.1%) of the Earth's crust, making it the 12th most abundant element there.HP Pavilion DV4-1404TX Battery

Soil contains 7–9000 ppm of manganese with an average of 440 ppm.[19] Seawater has only 10 ppm manganese and the atmosphere contains 0.01 µg/m3.[19] Manganese occurs principally as pyrolusite (MnO2), braunite, (Mn2+Mn3+6)(SiO12),[20] psilomelane (Ba,H2O)2Mn5O10, and to a lesser extent as rhodochrosite (MnCO3).HP Pavilion DV4-1405TX Battery

The most important manganese ore is pyrolusite (MnO2). Other economically important manganese ores usually show a close spatial relation to the iron ores. Land-based resources are large but irregularly distributed. About 80% of the known world manganese resources are found in South Africa, other important manganese deposits are inUkraine, Australia, India, China, Gabon and Brazil.HP Pavilion DV4-1406TX Battery

In 1978 it was estimated that 500 billion tons ofmanganese nodules exist on the ocean floor.[22] Attempts to find economically viable methods of harvesting manganese nodules were abandoned in the 1970s.[23]

Manganese is mined in South Africa, Australia, China, Brazil, Gabon, Ukraine, India and Ghana and Kazakhstan.HP Pavilion DV4-1407TX Battery

US Import Sources (1998–2001): Manganese ore: Gabon, 70%; South Africa, 10%; Australia, 9%; Mexico, 5%; and other, 6%. Ferromanganese: South Africa, 47%; France, 22%; Mexico, 8%; Australia, 8%; and other, 15%. Manganese contained in all manganese imports: South Africa, 31%; Gabon, 21%; Australia, 13%; Mexico, 8%; and other, 27%.HP Pavilion DV4-1408TX Battery

For the production of ferromanganese, the manganese ore are mixed with iron ore and carbon and then reduced either in a blast furnace or in an electric arc furnace.The resulting ferromanganese has a manganese content of 30 to 80%. Pure manganese used for the production of non-iron alloys is produced by leachingmanganese ore with sulfuric acid and a subsequent electrowinning process.HP Pavilion DV4-1409TX Battery

Applications

Manganese has no satisfactory substitute in its major applications, which are related to metallurgical alloy use. In minor applications, (e.g., manganese phosphating), zinc and sometimes vanadium are viable substitutes.HP Pavilion DV4-1413LA Battery

In disposable battery manufacture, standard and alkaline cells using manganese will be generally replaced in the future with lithium battery technology.

Steel

Manganese is essential to iron and steel production by virtue of its sulfur-fixing, deoxidizing, and alloying properties.HP Pavilion DV4-1414LA Battery

Steelmaking, including its ironmaking component, has accounted for most manganese demand, presently in the range of 85% to 90% of the total demand. Among a variety of other uses, manganese is a key component of low-cost stainless steelformulations.HP Pavilion DV4-1416LA Battery

Small amounts of manganese improve the workability of steel at high temperatures, because it forms a high melting sulfide and therefore prevents the formation of a liquid iron sulfide at the grain boundaries. If the manganese content reaches 4% the embrittlement of the steel becomes a dominant feature.HP Pavilion DV4-1425LA Battery

The embrittlement decreases at higher manganese concentrations and reaches an acceptable level at 8%. Steel containing 8 to 15% of manganese can have a high tensile strength of up to 863 MPa. Steel with 12% manganese was used for the British steel helmets. This steel composition was discovered in 1882 by Robert Hadfield and is still known as Hadfield steel.HP Pavilion DV4T Battery

Aluminium alloys

The second large application for manganese is as alloying agent for aluminium. Aluminium with a manganese content of roughly 1.5% has an increased resistance against corrosion due to the formation of grains absorbing impurities which would lead to galvanic corrosion.HP Pavilion DV4T-1000 CTO Battery

The corrosion resistant aluminium alloy 3004 and 3104 with a manganese content of 0.8 to 1.5% are the alloy used for most of the beverage cans. Before year 2000, in excess of 1.6 million tonnes have been used of those alloys, with a content of 1% of manganese this amount would need 16,000 tonnes of manganese.HP Pavilion DV4T-1100 CTO Battery

Other uses

Methylcyclopentadienyl manganese tricarbonyl is used as an additive in unleaded gasoline to boost octane rating and reduce engine knocking. The manganese in this unusual organometallic compound is in the +1 oxidation state.HP Pavilion DV4T-1200 CTO Battery

Manganese(IV) oxide (manganese dioxide, MnO2) is used as a reagent in organic chemistry for the oxidation of benzylic alcohols (i.e. adjacent to an aromatic ring). Manganese dioxide has been used since antiquity to oxidatively neutralize the greenish tinge in glass caused by trace amounts of iron contamination.HP Pavilion DV4T-1200SE CTO Battery

MnO2 is also used in the manufacture of oxygen and chlorine, and in drying black paints. In some preparations it is a brown pigment that can be used to make paint and is a constituent of natural umber.

Manganese(IV) oxide was used in the original type of dry cell battery as an electron acceptor from zinc, and is the blackish material found when opening carbon–zinc type flashlight cells.HP Pavilion DV4T-1300 CTO Battery

The manganese dioxide is reduced to the manganese oxide-hydroxide MnO(OH) during discharging, preventing the formation of hydrogen at the anode of the battery.

MnO2 + H2O + e? ? MnO(OH) + OH?

The same material also functions in newer alkaline batteries (usually battery cells), which use the same basic reaction, but a different electrolyte mixture.HP Pavilion DV4T-1300SE CTO Battery

In 2002 more than 230,000 tons of manganese dioxide was used for this purpose.

The metal is very occasionally used in coins; until 2000 the only United States coin to use manganese was the "wartime" nickel from 1942–1945.HP Pavilion DV4T-1400 CTO Battery

An alloy of 75% copper and 25% nickel was traditionally used for the production of nickel coins. However, because of shortage of nickel metal during the war, it was substituted by more available silver and manganese, thus resulting in an alloy of 56% copper, 35% silver and 9% manganese.HP Pavilion DV4Z Battery

Since 2000, dollar coins, for example the Sacagawea dollar and the Presidential $1 Coins, are made from a brass containing 7% of manganese with a pure copper core. In both cases of nickel and dollar, the use of manganese in the coin was to duplicate the electromagnetic properties of a previous identically sized and valued coin, for vending purposes.HP Pavilion DV4Z-1000 CTO Battery

In the case of the later U.S. dollar coins, the manganese-alloy was an attempt to duplicated properties of the copper/nickel alloy used in the previous Susan B. Anthony dollar.

Manganese compounds have been used as pigments and for the coloring of ceramics and glass. The brown color of ceramic is sometimes based on manganese compounds.HP Pavilion DV4Z-1100 CTO Battery

In the glass industry manganese compounds are used for two effects. Manganese(III) reacts with iron(II). The reaction induces a strong green color in glass by forming less-colored iron(III) and slightly pink manganese(II), compensating the residual color of the iron(III). Larger amounts of manganese are used to produce pink colored glass.HP Pavilion DV4Z-1200 CTO Battery

Biological role

Manganese is an essential trace nutrient in all forms of life. The classes of enzymes that have manganese cofactors are very broad and include oxidoreductases, transferases, hydrolases, lyases,isomerases, ligases, lectins, and integrins.HP Pavilion DV4 Battery

The reverse transcriptases of many retroviruses (though notlentiviruses such as HIV) contain manganese. The best known manganese-containing polypeptides may bearginase, the diphtheria toxin, and Mn-containing superoxide dismutase (Mn-SOD).[HP Pavilion DV4-1000 Battery

Mn-SOD is the type of SOD present in eukaryotic mitochondria, and also in most bacteria (this fact is in keeping with the bacterial-origin theory of mitochondria). The Mn-SOD enzyme is probably one of the most ancient, for nearly all organisms living in the presence of oxygen use it to deal with the toxic effects of superoxide, formed from the 1-electron reduction of dioxygen.HP Pavilion DV4-1000EA Battery

Exceptions include a few kinds of bacteria such as Lactobacillus plantarum and related lactobacilli, which use a different non-enzymatic mechanism, involving manganese (Mn2+) ions complexed with polyphosphate directly for this task, indicating how this function possibly evolved in aerobic life.HP Pavilion DV4-1000ET Battery

The human body contains about 12 mg of manganese, which is stored mainly in the bones; in the tissue, it is mostly concentrated in the liver and kidneys. In the human brain the manganese is bound to manganese metalloproteins, most notably glutamine synthetase in astrocytes.HP Pavilion DV4-1001 Battery

Manganese is also important in photosynthetic oxygen evolution in chloroplasts in plants. The oxygen evolving complex (OEC) is a part of Photosystem II contained in the thylakoid membranes of chloroplasts; it is responsible for the terminal photooxidation of waterduring the light reactions of photosynthesis and has a metalloenzyme core containing four atoms of manganese.HP Pavilion DV4-1001AX Battery

For this reason, most broad-spectrum plant fertilizers contain manganese.

Precautions

Manganese compounds are less toxic than those of other widespread metals such as nickel and copper. However, exposure to manganese dusts and fumes should not exceed the ceiling value of 5 mg/m3 even for short periods because of its toxicity level.HP Pavilion DV4-1001TU Battery

Manganese poisoning has been linked to impaired motor skills and cognitive disorders.

The permanganate exhibits a higher toxicity than the manganese(II) compounds. The fatal dose is about 10 g, and several fatal intoxications have occurred. The strong oxidative effect leads to necrosis of the mucous membrane.HP Pavilion DV4-1001TX Battery

For example, the esophagus is affected if the permanganate is swallowed. Only a limited amount is absorbed by the intestines, but this small amount shows severe effects on the kidneys and on the liver.

In 2005, a study suggested a possible link between manganese inhalation and central nervous system toxicity in rats.HP Pavilion DV4-1002 Battery

It is hypothesized that long-term exposure to the naturally occurring manganese in shower water puts up to 8.7 million Americans at risk.

A form of neurodegeneration similar to Parkinson's Disease called "manganism" has been linked to manganese exposure amongst miners and smelters since the early 19th century.HP Pavilion DV4-1002AX Battery

Allegations of inhalation-induced manganism have been made regarding the welding industry. Manganese exposure in United States is regulated byOccupational Safety and Health Administration.

According to results from a 2010 study, higher levels of exposure to manganese in drinking water are associated with increased intellectual impairment and reduced intelligence quotients in school-age children.HP Pavilion DV4-1002TU Battery

Clinical toxicity

Manganism has occurred in persons employed in the production or processing of manganese alloys, patients receiving total parenteral nutrition, workers exposed to manganese-containing fungicides such as maneb, and abusers of drugs such as methcathinone made with potassium permanganate.HP Pavilion DV4-1002TX Battery

Excessive exposure may be confirmed by measurement of blood or urine manganese concentrations.

Chronic exposure to excessive Mn levels can lead to a variety of psychiatric and motor disturbances, termed manganism.HP Pavilion DV4-1003AX Battery

Generally, exposure to ambient Mn air concentrations in excess of 5 ?g Mn/m3 can lead to Mn-induced symptoms. Increased ferroportin protein expression in human embryonic kidney (HEK293) cells is associated with decreased intracellular Mn concentration and attenuated cytotoxicity,HP Pavilion DV4-1003TU Battery

characterized by the reversal of Mn-reduced glutamate uptake and diminishedlactate dehydrogenase (LDH) leakage.HP Pavilion DV4-1003TX Battery,HP Pavilion DV4-1004AX Battery,HP Pavilion DV4-1004TU Battery,HP Pavilion DV4-1004TX Battery,HP Pavilion DV4-1005TX Battery,HP Pavilion DV4-1006TX Battery

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6 décembre 2011 2 06 /12 /décembre /2011 02:30

Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature HP Pavilion DV4-1199EA Battery

. Andrés Manuel del Río discovered vanadium in 1801 by analyzing a new lead-bearing mineral he called "brown lead," and named the new element erythronium (Greek for "red") since, upon heating, most of its salts turned from their initial color to red. Four years later, however, he was convinced by other scientists that erythronium was identical to chromium.HP Pavilion DV4-1199EE Battery

The element was rediscovered in 1831 by Nils Gabriel Sefström, who named it vanadium after the Germanic goddess of beauty and fertility, Vanadís (Freyja). Both names were attributed to the wide range of colors found in vanadium compounds. Del Rio's lead mineral was later renamed vanadinite for its vanadium content.HP Pavilion DV4-1199EF Battery

The element occurs naturally in about 65 different minerals and in fossil fuel deposits. It is produced in China and Russia from steel smelter slag; other countries produce it either from the flue dust of heavy oil, or as a byproduct of uranium mining. It is mainly used to produce specialty steel alloys such as high speed tool steels.HP Pavilion DV4-1199EO Battery

The most important industrial vanadium compound, vanadium pentoxide, is used as a catalyst for the production of sulfuric acid.

Large amounts of vanadium ions are found in a few organisms, possibly as a toxin. The oxide and some other salts of vanadium have moderate toxicity.HP Pavilion DV4-1199EP Battery

Particularly in the ocean, vanadium is used by some life forms as an active center of enzymes, such as the vanadium bromoperoxidase of some ocean algae. Vanadium is probably a micronutrient in mammals, including humans, but its precise role in this regard is unknown.HP Pavilion DV4-1199ER Battery

Vanadium was originally discovered by Andrés Manuel del Río, a Spanish-born Mexican mineralogist, in 1801. Del Río extracted the element from a sample of Mexican "brown lead" ore, later named vanadinite. He found that its salts exhibit a wide variety of colors, and as a result he named the element panchromium (Greek: ????????? "all colors").HP Pavilion DV4-1199ES Battery

Later, Del Río renamed the element erythronium (Greek: ??????? "red") as most of its salts turned red upon heating. In 1805, the French chemistHippolyte Victor Collet-Descotils, backed by del Río's friend Baron Alexander von Humboldt, incorrectly declared that del Río's new element was only an impure sample of chromium.HP Pavilion DV4-1199ET Battery

Del Río accepted the Collet-Descotils' statement and retracted his claim.

In 1831, the Swedish chemist Nils Gabriel Sefström rediscovered the element in a new oxide he found while working with iron ores. Later that same year, Friedrich Wöhler confirmed del Río's earlier work.HP Pavilion DV4-1200 CTO Battery

Sefström chose a name beginning with V, which had not been assigned to any element yet. He called the element vanadium after Old Norse Vanadís (another name for theNorse Vanr goddess Freyja, whose facets include connections to beauty and fertility), because of the many beautifully coloredchemical compounds it produces.HP Pavilion DV4-1200 Battery

In 1831, the geologist George William Featherstonhaugh suggested that vanadium should be renamed "rionium" after del Río, but this suggestion was not followed.

The isolation of vanadium metal proved difficult. In 1831, Berzelius reported the production of the metal, but Henry Enfield Roscoe showed that Berzelius had in fact produced the nitride, vanadium nitride (VN).HP Pavilion DV4-1201AU Battery

Roscoe eventually produced the metal in 1867 by reduction of vanadium(II) chloride, VCl2, with hydrogen. In 1927, pure vanadium was produced by reducing vanadium pentoxide with calcium. The first large scale industrial use of vanadium in steels was found in the chassis of the Ford Model T, inspired by French race cars.HP Pavilion DV4-1201TU Battery

Vanadium steel allowed for reduced weight while simultaneously increasingtensile strength.

Characteristics

Vanadium is a hard, ductile, silver-gray metal. Some sources describe vanadium as "soft", perhaps because it is ductile, malleable and not brittle.HP Pavilion DV4-1201TX Battery

Vanadium is harder than most metals and steels (see Hardnesses of the elements (data page)and iron). It has good resistance to corrosion and it is stable against alkalis, sulfuric and hydrochloric acids.[10] It isoxidized in air at about 933 K (660 °C, 1220 °F), although an oxide layer forms even at room temperature.HP Pavilion DV4-1202AU Battery

Isotopes

Naturally occurring vanadium is composed of one stable isotope 51V and one radioactive isotope 50V. The latter has a half-lifeof 1.5×1017 years and a natural abundance 0.25%. 51V has a nuclear spin of 7/2 which is useful for NMR spectroscopy.HP Pavilion DV4-1202TU Battery

A number of 24 artificial radioisotopes have been characterized, ranging in mass number from 40 to 65. The most stable of these isotopes are 49V with a half-life of 330 days, and 48V with a half-life of 16.0 days. All of the remaining radioactiveisotopes have half-lives shorter than an hour, most of which are below 10 seconds.HP Pavilion DV4-1202TX Battery

At least 4 isotopes have metastable excited states. Electron capture is the main decay mode for isotopes lighter than the 51V. For the heavier ones, the most common mode is beta decay. The electron capture reactions lead to the formation of element 22 (titanium) isotopes, while for beta decay, it leads to element 24 (chromium) isotopes.HP Pavilion DV4-1203AU Battery

Chemistry and compounds

The chemistry of vanadium is noteworthy for the accessibility of the four adjacent oxidation states 2-4. In aqueous solution the colours are lilac V2+(aq), green V3+(aq), blue VO2+(aq) and, at high pH, yellow VO42-. Vanadium(II) compounds are reducing agents, and vanadium(V) compounds are oxidizing agents.HP Pavilion DV4-1203TU Battery

Vanadium(IV) compounds often exist as vanadyl derivatives which contain the VO2+ center.

Ammonium vanadate(V) (NH4VO3) can be successively reduced with elemental zinc to obtain the different colors of vanadium in these four oxidation states.HP Pavilion DV4-1203TX Battery

Lower oxidation states occur in compounds such as V(CO)6, [V(CO)6]? and substituted derivatives.

The vanadium redox battery utilizes these oxidation states; conversion of these oxidation states is illustrated by the reduction of a strongly acidic solution of a vanadium(V) compound with zinc dust.HP Pavilion DV4-1204AU Battery

The initial yellow color characteristic of the vanadate ion, VO3?

4, is replaced by the blue color of [VO(H2O)5]2+, followed by the green color of [V(H2O)6]3+ and then violet, due to [V(H2O)6]2+.HP Pavilion DV4-1204TU Battery

The most commercially important compound is vanadium pentoxide, which is used as a catalyst for the production of sulfuric acid.[10] This compound oxidizes sulfur dioxide (SO2) to the trioxide (SO3). In thisredox reaction, sulfur is oxidized from +4 to +6, and vanadium is reduced from +5 to +3:HP Pavilion DV4-1204TX Battery

V2O5 + 2 SO2 ? V2O3 + 2 SO3

The catalyst is regenerated by oxidation with air:

V2O3 + O2 ? V2O5

Oxy and oxo compounds

The oxyanion chemistry of vanadium(V) is complex. The vanadate ion, VO3?4, is present in dilute solutions at high pH. On acidification, HVO2?4 and H2VO?4 are formed, analogous to HPO2?4 and H2PO?4.HP Pavilion DV4-1205AU Battery

The acid dissociation constants for the vanadium and phosphorus series are remarkably similar. In more concentrated solutions many polyvanadates are formed. Chains, rings and clusters involving tetrahedral vanadium, analogous to the polyphosphates, are known.HP Pavilion DV4-1205TU Battery

In addition, clusters such as the decavanadates V10O4?28 and HV10O3?28, which predominate at pH 4–6, are formed in which there is a distorted octahedron of oxygen atoms around each vanadium atom.[10]

The correspondence between vanadate and phosphate chemistry can be attributed to the similarity in size and charge of phosphorus(V) and vanadium(V).HP Pavilion DV4-1205TX Battery

Orthovanadate VO3?4 is used in protein crystallography[13] to study the biochemistry of phosphate.[14]

Vanadium also forms various peroxo- complexes when treated with hydrogen peroxide. For instance, the yellow oxovanadium(V) ion VO+
2in acidic hydrogen peroxide solution forms the brick red peroxovanadium(V) ion, VO(O2)2+.HP Pavilion DV4-1206TU Battery

Halide compounds

All four halides are known for oxidation states +2 and +3, but the iodide is not known for V(IV) and VF5 is the only halide known for oxidation state 5. VCl4 may be used as a catalyst for polymerization of dienes.HP Pavilion DV4-1206TX Battery

Coordination compounds

Vanadium's early position in the transition metal series lead to three rather unusual features of the coordination chemistry of vanadium. Firstly, metallic vanadium has the electronic configuration [Ar]3d34s2, so compounds of vanadium are relatively electron-poor.HP Pavilion DV4-1207TU Battery

Consequently, most binary compounds are Lewis acids (electron pair acceptors); examples are all the halides forming octahedral adducts with the formula VXnL6?n (X = halide; L = other ligand). Secondly, the vanadium ion is rather large and can achieve coordination numbers higher than 6, as is the case in [V(CN)7]4?.HP Pavilion DV4-1207TX Battery

Thirdly, the vanadyl ion, VO2+, is featured in many complexes of vanadium(IV) such as vanadyl acetylacetonate (V(=O)(acac)2). In this complex, the vanadium is 5-coordinate, square pyramidal, meaning that a sixth ligand, such as pyridine, may be attached, though the association constant of this process is small.HP Pavilion DV4-1208TU Battery

Many 5-coordinate vanadyl complexes have a trigonal bypyramidal geometry, such as VOCl2(NMe3)2.

Organometallic compounds

Organometallic chemistry of vanadium is well developed, but organometallic compounds are of minor commercial significance.HP Pavilion DV4-1208TX Battery

Vanadocene dichloride is a versatile starting reagent and even finds minor applications in organic chemistry.[17] Vanadium carbonyl, V(CO)6, is a rare example of ametal carbonyl containing an unpaired electron, but which exists without dimerization.HP Pavilion DV4-1209TU Battery

The addition of an electron yields V(CO)?6 (isoelectronic with Cr(CO)6), which may be further reduced with sodium in liquid ammonia to yield V(CO)3?6 (isoelectronic with Fe(CO)5).

Occurrence

Metallic vanadium is not found in nature, but is known to exist in about 65 different minerals.HP Pavilion DV4-1209TX Battery

Economically significant examples include patronite (VS4), vanadinite (Pb5(VO4)3Cl), and carnotite (K2(UO2)2(VO4)2·3H2O). Much of the world's vanadium production is sourced from vanadium-bearing magnetite found in ultramafic gabbro bodies.HP Pavilion DV4-1210EA Battery

Vanadium is mined mostly in South Africa, north-western China, and eastern Russia. In 2010 these three countries mined more than 98% of the 56,000 tonnes of produced vanadium.

Vanadium is also present in bauxite and in fossil fuel deposits such as crude oil, coal, oil shale and tar sands.HP Pavilion DV4-1210EF Battery

In crude oil, concentrations up to 1200 ppm have been reported. When such oil products are burned, the traces of vanadium may initiate corrosionin motors and boilers. An estimated 110,000 tonnes of vanadium per year are released into the atmosphere by burning fossil fuels.HP Pavilion DV4-1210EO Battery

Vanadium has also been detected spectroscopically in light from the Sun and some other stars.

Production

Most vanadium is used as an alloy called ferrovanadium as an additive to improve steels.Ferrovanadium is produced directly by reducing a mixture of vanadium oxide, iron oxides and iron in an electric furnace.HP Pavilion DV4-1210ER Battery

Vanadium-bearing magnetite iron ore is the main source for the production of vanadium. The vanadium ends up in pig iron produced from vanadium bearing magnetite. During steel production, oxygen is blown into the pig iron, oxidizing the carbon and most of the other impurities, forming slag.HP Pavilion DV4-1210TU Battery

Depending on the used ore, the slag contains up to 25% of vanadium.

Vanadium metal is obtained via a multistep process that begins with the roasting of crushed ore with NaCl or Na2CO3 at about 850 °C to give sodium metavanadate (NaVO3). An aqueous extract of this solid is acidified to give "red cake", a polyvanadate salt, which is reduced with calcium metal.HP Pavilion DV4-1210TX Battery

As an alternative for small scale production, vanadium pentoxide is reduced with hydrogen or magnesium. Many other methods are also in use, in all of which vanadium is produced as a byproduct of other processes. Purification of vanadium is possible by the crystal bar process developed by Anton Eduard van Arkel and Jan Hendrik de Boer in 1925.HP Pavilion DV4-1211EA Battery

It involves the formation of the metal iodide, in this example vanadium(III) iodide, and the subsequent decomposition to yield pure metal.

2 V + 3 I2 2 VI3

Alloys

Approximately 85% of vanadium produced is used as ferrovanadium or as a steel additive.HP Pavilion DV4-1211TU Battery

The considerable increase of strength in steel containing small amounts of vanadium was discovered in the beginning of the 20th century. Vanadium forms stable nitrides and carbides, resulting in a significant increase in the strength of the steel.HP Pavilion DV4-1211TX Battery

From that time on vanadium steel was used for applications in axles, bicycle frames,crankshafts, gears, and other critical components. There are two groups of vanadium containing steel alloy groups. Vanadium high-carbon steel alloys contain 0.15% to 0.25% vanadium and high speed tool steels (HSS) have a vanadium content of 1% to 5%.HP Pavilion DV4-1212LA Battery

For high speed tool steels, a hardness above HRC 60 can be achieved. HSS steel is used in surgical instruments and tools.[28]

Vanadium stabilizes the beta form of titanium and increases the strength and temperature stability of titanium. Mixed with aluminium in titanium alloys it is used in jet engines and high-speed airframes.HP Pavilion DV4-1212TU Battery

One of the common alloys is Titanium 6AL-4V, a titanium alloy with 6% aluminium and 4% vanadium.

Other uses

Vanadium is compatible with iron and titanium, therefore vanadium foil is used in cladding titanium to steel.HP Pavilion DV4-1212TX Battery

The moderate thermal neutron-capture cross-section and the short half-life of the isotopes produced by neutron capture makes vanadium a suitable material for the inner structure of a fusion reactor. Several vanadium alloys show superconducting behavior. The first A15 phase superconductor was a vanadium compound, V3Si, which was discovered in 1952.HP Pavilion DV4-1213LA Battery

Vanadium-gallium tape is used in superconducting magnets (17.5 teslas or 175,000 gauss). The structure of the superconducting A15 phase of V3Ga is similar to that of the more common Nb3Sn and Nb3Ti.

The most common oxide of vanadium, vanadium pentoxide V2O5, is used as a catalyst in manufacturing sulfuric acid by the contact process and as an oxidizer in maleic anhydride production.HP Pavilion DV4-1213TU Battery

Vanadium pentoxide is also used in making ceramics. Another oxide of vanadium, vanadium dioxide VO2, is used in the production of glass coatings, which blocks infrared radiation (and not visible light) at a specific temperature. Vanadium oxide can be used to induce color centers in corundum to create simulated alexandrite jewelry, although alexandrite in nature is a chrysoberyl.HP Pavilion DV4-1213TX Battery

The possibility to use vanadium redox couples in both half-cells, thereby eliminating the problem of cross contamination by diffusion of ions across the membrane is the advantage of vanadium redox rechargeable batteries. Vanadate can be used for protecting steel against rust and corrosion by electrochemical conversion coating.HP Pavilion DV4-1214LA Battery

Lithium vanadium oxide has been proposed for use as a high energy density anode for lithium ion batteries, at 745 Wh/L when paired with a lithium cobalt oxide cathode. It has been proposed by some researchers that a small amount, 40 to 270 ppm, of vanadium in Wootz steel andDamascus steel, significantly improves the strength of the material, although it is unclear what the source of the vanadium was.HP Pavilion DV4-1214TU Battery

Biological role

Vanadium plays a very limited role in biology, and is more important in ocean environments than on land.

Bromoperoxidases in algae

Organobromine compounds in a number of species of marine algae are generated by the action of a vanadium dependentbromoperoxidase.HP Pavilion DV4-1214TX Battery

This is a haloperoxidase in algae which requires bromide and is an absolutely vanadium-dependent enzyme. Most organobromine compounds in the sea ultimately arise via the action of this vanadium bromoperoxidase.

Vanadium accumulation in tunicates and ascidians

German chemist Martin Henze discovered vanadium in the blood cells (or coelomic cells) of Ascidiacea (sea squirts) in 1911.HP Pavilion DV4-1215EF Battery

It is essential to ascidians and tunicates, where it is stored in the highly acidified vacuoles of certain blood cell types, designated vanadocytes. Vanabins (vanadium binding proteins) have been identified in the cytoplasm of such cells. The concentration of vanadium in their blood is up to 10 million times higher than the concentration of vanadium in the seawater around them.HP Pavilion DV4-1215TU Battery

Vanadium has been reported in high concentrations in holothurian (sea cucumber) blood, however other researchers have been unable to reproduce these results. There is no evidence that hemovanadin carries oxygen, in contrast to hemoglobin and hemocyanin, which may also be present in these organisms.HP Pavilion DV4-1215TX Battery

Nitrogen fixation

A vanadium nitrogenase is used by some nitrogen-fixing micro-organisms, such as Azotobacter. In this role vanadium replaces more common molybdenum or iron, and gives the nitrogenase slightly different properties.HP Pavilion DV4-1216TU Battery

Fungi

Several species of macrofungi, namely Amanita muscaria and related species, accumulate vanadium (up to 500 mg/kg in dry weight). Vanadium is present in the coordination complex, amavadin, in fungal fruit-bodies. However, the biological importance of the accumulation process is unknown.HP Pavilion DV4-1216TX Battery

Toxin functions or peroxidase enzyme functions have been suggested.

Mammals and birds

Rats and chickens are also known to require vanadium in very small amounts and deficiencies result in reduced growth and impairedreproduction.HP Pavilion DV4-1217LA Battery

Vanadium is a relatively controversial dietary supplement, primarily for increasing insulin sensitivity[55] andbody-building. Whether it works for the latter purpose has not been proven, and there is some evidence that athletes who take it are merely experiencing a placebo effect.HP Pavilion DV4-1217TX Battery

Vanadyl sulfate may improve glucose control in people with type 2 diabetes. In addition, decavanadate and oxovanadates are species that potentially have many biological activities and that have been successfully used as tools in the comprehension of several biochemical processes.HP Pavilion DV4-1218TX Battery

Safety

All vanadium compounds should be considered to be toxic. Tetravalent VOSO4 has been reported to be over 5 times more toxic than trivalent V2O3.HP Pavilion DV4-1219TX Battery

The Occupational Safety and Health Administration (OSHA) has set an exposure limit of 0.05 mg/m3 for vanadium pentoxide dust and 0.1 mg/m3 for vanadium pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week.HP Pavilion DV4-1220BR Battery

TheNational Institute for Occupational Safety and Health (NIOSH) has recommended that 35 mg/m3 of vanadium be considered immediately dangerous to life and health. This is the exposure level of a chemical that is likely to cause permanent health problems or death. HP Pavilion DV4-1220TX Battery

Vanadium compounds are poorly absorbed through the gastrointestinal system. Inhalation exposures to vanadium and vanadium compounds result primarily in adverse effects on the respiratory system. Quantitative data are, however, insufficient to derive a subchronic or chronic inhalation reference dose.HP Pavilion DV4-1220US Battery

Other effects have been reported after oral or inhalation exposures on blood parameters, on liver,[70] on neurological development in rats,[71] and other organs.[72]

There is little evidence that vanadium or vanadium compounds are reproductive toxins or teratogens.HP Pavilion DV4-1221TX Battery

Vanadium pentoxide was reported to be carcinogenic in male rats and male and female mice by inhalation in an NTP study,[66]although the interpretation of the results has recently been disputed.[73] Vanadium has not been classified as to carcinogenicity by the United States Environmental Protection Agency.HP Pavilion DV4-1222LA Battery

Vanadium traces in diesel fuels present a corrosion hazard; it is the main fuel component influencing high temperature corrosion. During combustion, it oxidizes and reacts with sodium and sulfur, yielding vanadate compounds with melting points down to 530 °C, which attack the passivation layer on steel, rendering it susceptible to corrosion.HP Pavilion DV4-1222NR Battery

The solid vanadium compounds also cause abrasion of engine components.

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point.HP Pavilion DV4-1222TX Battery

It is also odorless, tasteless, and malleable. The name of the element is derived from the Greek word "chr?ma" (?????), meaningcolour, because many of its compounds are intensely coloured. Chromium oxide was used by the Chinese in the Qin dynastyover 2,000 years ago to coat weapons such as bronze crossbow bolts and steel swords found at the Terracotta Army.HP Pavilion DV4-1223LA Battery

It later came to the attention of the west when it was discovered by Louis Nicolas Vauquelin in the mineral crocoite (lead(II) chromate) in 1797. Crocoite was used as a pigment, and after the discovery that the mineral chromite also contains chromium, this latter mineral was used to produce pigments as well.HP Pavilion DV4-1223TX Battery

Chromium was regarded with great interest because of its high corrosion resistance and hardness. A major development was the discovery that steel could be made highly resistant to corrosion and discoloration by adding chromium to form stainless steel.HP Pavilion DV4-1224LA Battery

This application, along with chrome plating (electroplating with chromium) are currently the highest-volume uses of the metal. Chromium and ferrochromium are produced from the single commercially viable ore, chromite, by silicothermic oraluminothermic reaction or by roasting and leaching processes.HP Pavilion DV4-1224TX Battery

Although trivalent chromium (Cr(III)) is required in trace amounts for sugar and lipid metabolism, few cases have been reported where its complete removal from the diet has caused chromium deficiency. In larger amounts and different forms chromium can be toxic and carcinogenic.HP Pavilion DV4-1225DX Battery

The most prominent example of toxic chromium is hexavalent chromium (Cr(VI)). Abandoned chromium production sites often require environmental cleanup.

Physical

Chromium is remarkable for its magnetic properties: it is the only elemental solid which shows antiferromagnetic ordering at room temperature (and below). Above 38 °C, it transforms into a paramagnetic state.HP Pavilion DV4-1225EE Battery

Passivation

Chromium metal left standing in air is passivated by oxygen, forming a thin protective oxide surface layer. This layer is aspinel structure only a few atoms thick. It is very dense, and prevents the diffusion of oxygen into the underlying material.HP Pavilion DV4-1225LA Battery

This barrier is in contrast to iron or plain carbon steels, where the oxygen migrates into the underlying material and causesrusting. The passivation can be enhanced by short contact with oxidizing acids like nitric acid. Passivated chromium is stable against acids. HP Pavilion DV4-1225TX Battery

The opposite effect can be achieved by treatment with a strong reducing reactant that destroys the protective oxide layer on the metal. Chromium metal treated in this way readily dissolves in weak acids.HP Pavilion DV4-1226TX Battery

Chromium, unlike metals such as iron and nickel, does not suffer from hydrogen embrittlement. However, it does suffer from nitrogen embrittlement, reacting with nitrogen from air and forming brittle nitrides at the high temperatures necessary to work the metal parts.HP Pavilion DV4-1227LA Battery

Occurrence

Chromium is the 21st most abundant element in Earth's crust with an average concentration of 100 ppm. Chromium compounds are found in the environment, due to erosion of chromium-containing rocks and can be distributed by volcanic eruptions.HP Pavilion DV4-1227TX Battery

The concentrations range in soil is between 1 and 3000 mg/kg, in sea water 5 to 800 µg/liter, and in rivers and lakes 26 µg/liter to 5.2 mg/liter.

Chromium is mined as chromite (FeCr2O4) ore.HP Pavilion DV4-1227US Battery

About two-fifths of the chromite ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia, and Turkey are also substantial producers. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan and southern Africa.HP Pavilion DV4-1228CA Battery

Although rare, deposits of native chromium exist. The Udachnaya Pipe in Russia produces samples of the native metal. This mine is a kimberlite pipe, rich in diamonds, and the reducing environment helped produce both elemental chromium and diamond.HP Pavilion DV4-1228LA Battery

The relation between Cr(III) and Cr(VI) strongly depends on pH and oxidative properties of the location, but in most cases, the Cr(III) is the dominating species,[7] although in some areas the ground water can contain up to 39 µg/liter of total chromium of which 30 µg/liter is present as Cr(VI).HP Pavilion DV4-1228TX Battery

Naturally occurring chromium is composed of three stable isotopes; 52Cr, 53Cr and 54Cr with 52Cr being the most abundant (83.789% natural abundance). 19 radioisotopeshave been characterized with the most stable being 50Cr with a half-life of (more than) 1.8×1017 years, and 51Cr with a half-life of 27.7 days.HP Pavilion DV4-1229LA Battery

All of the remainingradioactive isotopes have half-lives that are less than 24 hours and the majority of these have half-lives that are less than 1 minute. This element also has 2 meta states.

53Cr is the radiogenic decay product of 53Mn. Chromium isotopic contents are typically combined with manganese isotopic contents and have found application inisotope geology.HP Pavilion DV4-1229TX Battery

Mn-Cr isotope ratios reinforce the evidence from 26Al and 107Pd for the early history of the solar system. Variations in 53Cr/52Cr and Mn/Cr ratios from several meteorites indicate an initial 53Mn/55Mn ratio that suggests Mn-Cr isotopic composition must result from in-situ decay of 53Mn in differentiated planetary bodies.HP Pavilion DV4-1230BR Battery

Hence 53Cr provides additional evidence for nucleosynthetic processes immediately before coalescence of the solar system.

The isotopes of chromium range in atomic mass from 43 u (43Cr) to 67 u (67Cr). The primary decay mode before the most abundant stable isotope, 52Cr, is electron capture and the primary mode after is beta decay.HP Pavilion DV4-1230TX Battery

53Cr has been posited as a proxy for atmospheric oxygen concentration.

Chromium is a member of the transition metals, in group 6. Chromium(0) has an electronic configuration of 4s13d5, owing to the lower energy of the high spin configuration.HP Pavilion DV4-1231TX Battery

Chromium exhibits a wide range of possible oxidation states, where the +3 state is most stable energetically; the +3 and +6 states are most commonly observed in chromium compounds, whereas the +1, +4 and +5 states are rare.

A large number of chromium(III) compounds are known. HP Pavilion DV4-1232TX Battery

Chromium(III) can be obtained by dissolving elemental chromium in acids like hydrochloric acid or sulfuric acid. The Cr3+ ion has a similar radius (63 pm) to theAl3+ ion (radius 50 pm), so they can replace each other in some compounds, such as in chrome alum and alum.HP Pavilion DV4-1233TX Battery

When a trace amount of Cr3+ replaces Al3+ in corundum (aluminium oxide, Al2O3), the red-colored ruby is formed.

Chromium(III) ions tend to adopt octahedral molecular geometry, with six ligands. The colors of these solutions is determined by the ligands attached to the Cr centre.HP Pavilion DV4-1234TX Battery

HP Pavilion DV4-1235EE Battery

The commercially available chromium(III) chloride hydrate is the dark green complex [CrCl2(H2O)4]Cl, but two other forms are known: pale green [CrCl(H2O)5]Cl2, and the violet [Cr(H2O)6]Cl3. If water-free green chromium(III) chloride is dissolved in water then the green solution turns violet after some time, due to the substitution of water for chloride in the inner coordination sphere.HP Pavilion DV4-1235EI Battery

This kind of reaction is also observed in chrome alum solutions and other water-soluble chromium(III) salts. The reverse reaction may be induced by heating the solution.

Chromium(III) hydroxide (Cr(OH)3) is amphoteric, dissolving in acidic solutions to form [Cr(H2O)6]3+, and in basic solutions to form[Cr(OH)6]3?.HP Pavilion DV4-1235TX Battery

It is dehydrated by heating to form the green chromium(III) oxide (Cr2O3), which is the stable oxide with a crystal structure identical to that ofcorundum.[4]

Chromium(VI)

Chromium(VI) compounds are powerful oxidants at low or neutral pH. Most important are chromate anion (CrO2?
4) and dichromate (Cr2O72-) anions, which exist in equilibrium:HP Pavilion DV4-1236TX Battery

2 [CrO4]2- + 2 H+ [Cr2O7]2- + 2 H2O

Chromium(VI) halides are known also and include hexafluoride CrF6 and chromyl chloride (CrO2Cl2).[4]

Sodium chromate is produced industrially by the oxidative roasting of chromite ore with calcium or sodium carbonate. The dominant species is therefore, by the law of mass action, determined by the pH of the solution.HP Pavilion DV4-1237TX Battery

The change in equilibrium is visible by a change from yellow (chromate) to orange (dichromate), such as when an acid is added to a neutral solution of potassium chromate. At yet lower pH values, further condensation to more complex oxyanions of chromium is possible.HP Pavilion DV4-1238TX Battery

Chromium(VI) compounds in solution can be detected by adding an acidic hydrogen peroxide solution. The unstable dark blue chromium(VI) peroxide (CrO5) is formed, which can be stabilized as an ether adduct CrO5·OR2.

Chromic acid has the hypothetical formula H2CrO4.HP Pavilion DV4-1239TX Battery

It is a vaguely described chemical, despite many well-defined chromates and dichromates are known. The dark red chromium(VI) oxide CrO3, the acid anhydride of chromic acid, is sold industrially as "chromic acid".[4] It can be produced by mixing sulfuric acid with dichromate, and is a strong oxidizing agent.HP Pavilion DV4-1240TX Battery

In 2010, the Environmental Working Group studied the drinking water in 35 American cities. The study was the first nationwide analysis measuring the presence of the chemical in U.S. water systems. The study found measurable hexavalent chromium in the tap water of 31 of the cities sampled, with Norman, Oklahoma, at the top of list;HP Pavilion DV4-1241TX Battery

25 cities had levels that exceeded California's proposed limit.[20] Note: Concentrations of Cr VI in US municipal drinking water supplies reported by EWG are within likely, natural background levels for the areas tested and not necessarily indicative of industrial pollution (CalEPA Fact Sheet), as asserted by EWG. This factor was not taken into consideration in their report.HP Pavilion DV4-1242TX Battery

Chromium(IV) and chromium(V)

The oxidation state +5 is only realized in few compounds but are intermediates in many reactions involving oxidations by chromate. The only binary compound is the volatile chromium(V) fluoride (CrF5). This red solid has a melting point of 30 °C and a boiling point of 117 °C.HP Pavilion DV4-1243TX Battery

It can be synthesized by treating chromium metal with fluorine at 400 °C and 200 bar pressure. The peroxochromate(V) is another example of the +5 oxidation state. Potassium peroxochromate (K3[Cr(O2)4]) is made by reacting potassium chromate with hydrogen peroxide at low temperatures.HP Pavilion DV4-1244TX Battery

This red brown compound is stable at room temperature but decomposes spontaneously at 150–170 °C.

Compounds of chromium(IV) (in the +4 oxidation state) are slightly more common than those of chromium(V). The tetrahalides, CrF4, CrCl4, and CrBr4, can be produced by treating the trihalides (CrX3) with the corresponding halogen at elevated temperatures.HP Pavilion DV4-1245BR Battery

Such compounds are susceptible to disproportionation reactions and are not stable in water.

Chromium(I) and chromium(II)

Many chromium(II) compounds are known, including the water-stable chromium(II) chloride, CrCl2, which can be made by reduction of chromium(III) chloride with zinc. HP Pavilion DV4-1245TX Battery

The resulting bright blue solution is only stable at neutral pH.[4] Many chromous carboxylates are also known, most famously, the red chromous acetate (Cr2(O2CCH3)4), which features a quadruple bond. As verified by X-ray diffraction, a Cr-Cr quintuple bond (length 183.51(4) pm) has also been described.HP Pavilion DV4-1246TX Battery

Extremely bulky monodentate ligands stabilize this compound by shielding the quintuple bond from further reactions.

Chromium(0)

Many chromium(0) compounds are known. Most are derivatives of chromium hexacarbonyl or bis(benzene)chromium.HP Pavilion DV4-1247TX Battery

Weapons found in burial pits dating from the late 3rd century BC Qin Dynasty of the Terracotta Army near Xi'an, China have been analyzed by archaeologists. Although buried more than 2,000 years ago, the ancient bronze tips of crossbow bolts and swords found at the site showed no sign of corrosion, because the bronze was coated with chromium.HP Pavilion DV4-1248TX Battery

Chromium later came to the attention of westerners in the 18th century. On 26 July 1761, Johann Gottlob Lehmann found an orange-red mineral in the Beryozovskoye mines in the Ural Mountains which he named Siberian red lead. Though misidentified as a lead compound withselenium and iron components, the mineral was Crocoite (lead chromate) with a formula of PbCrO4.HP Pavilion DV4-1249TX Battery

In 1770, Peter Simon Pallas visited the same site as Lehmann and found a red lead mineral that had useful properties as a pigment inpaints. The use of Siberian red lead as a paint pigment developed rapidly. A bright yellow pigment made from crocoite also became fashionable.HP Pavilion DV4-1250TX Battery

In 1797, Louis Nicolas Vauquelin received samples of crocoite ore. He produced chromium trioxide (CrO3) by mixing crocoite withhydrochloric acid. In 1798, Vauquelin discovered that he could isolate metallic chromium by heating the oxide in a charcoal oven.He was also able to detect traces of chromium in precious gemstones, such as ruby or emerald.HP Pavilion DV4-1251TX Battery

During the 1800s, chromium was primarily used as a component of paints and in tanning salts. At first, crocoite from Russia was the main source, but in 1827, a larger chromite deposit was discovered near Baltimore, United States. This made the United states the largest producer of chromium products till 1848 when large deposits of chromite where found near Bursa, Turkey.HP Pavilion DV4-1252TX Battery

Chromium is also known for its luster when polished. It is used as a protective and decorative coating on car parts, plumbing fixtures, furniture parts and many other items, usually applied by electroplating. Chromium was used for electroplating as early as 1848, but this use only became widespread with the development of an improved process in 1924.HP Pavilion DV4-1253TX Battery

Metal alloys now account for 85% of the use of chromium. The remainder is used in the chemical industry and refractory and foundryindustries.

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Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant (including sea water, aqua regia and chlorine) transition metal with a silver color.

Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and named by Martin Heinrich Klaproth for theTitans of Greek mythology. HP Pavilion DV4 Battery

The element occurs within a number of mineral deposits, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere, and it is found in almost all living things, rocks, water bodies, and soils. The metal is extracted from its principal mineral ores via the Kroll process or the Hunter process. HP Pavilion DV4-1000 Battery

Its most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments.[4] Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and catalysts; and titanium trichloride(TiCl3), which is used as a catalyst in the production of polypropylene.HP Pavilion DV4-1000EA Battery

Titanium can be alloyed with iron, aluminium, vanadium, molybdenum, among other elements, to produce strong lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial process (chemicals and petro-chemicals,desalination plants, pulp, and paper), automotive, agri-food, medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications.HP Pavilion DV4-1000ET Battery

The two most useful properties of the metal form are corrosion resistance and the highest strength-to-weight ratio of any metal.[5] In its unalloyed condition, titanium is as strong as some steels, but 45% lighter.[6] There are two allotropicforms[7] and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant(73.8%).HP Pavilion DV4-1001 Battery

Titanium's properties are chemically and physically similar to zirconium, because both of them have the same number of valence electrons and are in the same group in the periodic table.

Physical properties

A metallic element, titanium is recognized for its high strength-to-weight ratio.HP Pavilion DV4-1001AX Battery

It is a strong metal with low densitythat is quite ductile (especially in an oxygen-free environment),[2] lustrous, and metallic-white in color.[9] The relatively high melting point (more than 1,650 °C or 3,000 °F) makes it useful as a refractory metal. It is paramagnetic and has fairly low electrical and thermal conductivity.HP Pavilion DV4-1001TU Battery

Commercial (99.2% pure) grades of titanium have ultimate tensile strength of about 63,000 psi (434 MPa), equal to that of common, low-grade steel alloys, but are 45% lighter.[6] Titanium is 60% more dense than aluminium, but more than twice as strong[6] as the most commonly used 6061-T6 aluminium alloy. HP Pavilion DV4-1001TX Battery

Certain titanium alloys (e.g., Beta C) achieve tensile strengths of over 200,000 psi (1,400 MPa).[10] However, titanium loses strength when heated above 430 °C (806 °F).[11]

It is fairly hard (although not as hard as some grades of heat-treated steel), non-magnetic and a poor conductor of heat and electricity. HP Pavilion DV4-1002 Battery

Machining requires precautions, as the material will soften and gall if sharp tools and proper cooling methods are not used. Like those made from steel, titanium structures have a fatigue limit which guarantees longevity in some applications. Titanium alloys specific stiffnesses are also usually not as good as other materials such as aluminium alloys and carbon fiber, so it is used less for structures which require high rigidity.HP Pavilion DV4-1002AX Battery

The metal is a dimorphic allotrope whose hexagonal alpha form changes into a body-centered cubic (lattice) ? form at 882 °C(1,620 °F).[11] The specific heat of the alpha form increases dramatically as it is heated to this transition temperature but then falls and remains fairly constant for the ? form regardless of temperature.HP Pavilion DV4-1002TU Battery

Similar to zirconium and hafnium, an additional omega phase exists, which is thermodynamically stable at high pressures, but is metastable at ambient pressures. This phase is usually hexagonal (ideal) or trigonal (distorted) and can be viewed as being due to a soft longitudinal acoustic phonon of the ? phase causing collapse of (111) planes of atoms.HP Pavilion DV4-1002TX Battery

Chemical properties

he most noted chemical property of titanium is its excellent resistance to corrosion; it is almost as resistant as platinum, capable of withstanding attack by dilute sulfuric acidand hydrochloric acid as well as chlorine gas, chloride solutions, and most organic acids.[3] However, it is soluble in concentrated acids.HP Pavilion DV4-1003AX Battery

The Pourbaix diagram in the image shows that titanium is actually thermodynamically a very reactive metal.

However, it is slow to react with water and air, because it forms a passive and protective oxide coating that protects it from further reaction.HP Pavilion DV4-1003TU Battery

When it first forms, this protective layer is only 1–2 nm thick but continues to slowly grow; reaching a thickness of 25 nm in four years.[15]

Titanium readily reacts with oxygen at 1,200 °C (2,190 °F) in air, and at 610 °C(1,130 °F) in pure oxygen, forming titanium dioxide.

HP Pavilion DV4-1003TX Battery

As a result, the metal cannot be melted in open air since it burns before the melting point is reached. Melting is only possible in an inert atmosphere or in a vacuum. At 550 °C (1,022 °F), it combines with chlorine.[3] It also reacts with the other halogens and absorbs hydrogen.HP Pavilion DV4-1004AX Battery

Titanium is one of the few elements that burns in pure nitrogen gas, reacting at 800 °C(1,470 °F) to form titanium nitride, which causes embrittlement.[16]

Experiments have shown that natural titanium becomes radioactive after it is bombarded with deuterons, emitting mainlypositrons and hard gamma rays.HP Pavilion DV4-1004TU Battery

Compounds

The +4 oxidation state dominates titanium chemistry,[17] but compounds in the +3 oxidation state are also common.[18] Because of this high oxidation state, many titanium compounds have a high degree of covalent bonding.HP Pavilion DV4-1004TX Battery

Star sapphires and rubies get their asterism from the titanium dioxide impurities present in them.[15]Titanates are compounds made with titanium dioxide. Barium titanate has piezoelectric properties, thus making it possible to use it as a transducer in the interconversion of sound and electricity.HP Pavilion DV4-1005TX Battery

Esters of titanium are formed by the reaction of alcohols and titanium tetrachloride and are used to waterprooffabrics.[7]

Titanium nitride (TiN), having a hardness equivalent to sapphire and carborundum (9.0 on the Mohs Scale),[19] is often used to coat cutting tools, such as drill bits.HP Pavilion DV4-1006TX Battery

It also finds use as a gold-colored decorative finish, and as a barrier metal in semiconductor fabrication.[21]

Titanium tetrachloride (titanium(IV) chloride, TiCl4, sometimes called "tickle"[22]) is a colorless liquid which is used as an intermediate in the manufacture of titanium dioxide for paint.HP Pavilion DV4-1007TX Battery

It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation.[24] Titanium also forms a lower chloride, titanium(III) chloride (TiCl3), which is used as a reducing agent.[25]

Titanocene dichloride is an important catalyst for carbon-carbon bond formation. Titanium isopropoxide is used for Sharpless epoxidation.HP Pavilion DV4-1008TX Battery

Other compounds include titanium bromide (used in metallurgy, superalloys, and high-temperature electrical wiring and coatings) and titanium carbide(found in high-temperature cutting tools and coatings).[4]

Occurrence

Titanium is always bonded to other elements in nature. It is the ninth-most abundant element in the Earth's crust (0.63% by mass)[27] and the seventh-most abundant metal.HP Pavilion DV4-1009TX Battery

It is present in most igneous rocks and insediments derived from them (as well as in living things and natural bodies of water).[2][3]Of the 801 types of igneous rocks analyzed by the United States Geological Survey, 784 contained titanium.[27] Its proportion in soils is approximately 0.5 to 1.5%.HP Pavilion DV4-1010TX Battery

It is widely distributed and occurs primarily in the minerals anatase, brookite, ilmenite, perovskite, rutile,titanite (sphene), as well in many iron ores.[15] Of these minerals, only rutile and ilmenite have any economic importance, yet even they are difficult to find in high concentrations.HP Pavilion DV4-1011TX Battery

Significant titanium-bearing ilmenite deposits exist in western Australia, Canada, China, India, Mozambique, New Zealand, Norway, and Ukraine.[15]Large quantities of rutile are also mined in North America and South Africa and help contribute to the annual production of 90,000 tonnes of the metal and 4.3 million tonnes of titanium dioxide.HP Pavilion DV4-1012TX Battery

Total reserves of titanium are estimated to exceed 600 million tonnes.[15]

Titanium is contained in meteorites and has been detected in the sun and in M-type stars;[3] the coolest type of star with a surface temperature of 3,200 °C (5,790 °F).[28] Rocks brought back from the moon during the Apollo 17 mission are composed of 12.1% TiO2.[3] It is also found in coal ash, plants, and even the human body.HP Pavilion DV4-1013TX Battery

Isotopes

Naturally occurring titanium is composed of 5 stable isotopes: 46Ti, 47Ti, 48Ti, 49Ti, and 50Ti, with 48Ti being the most abundant (73.8% natural abundance).HP Pavilion DV4-1014NR Battery

Elevenradioisotopes have been characterized, with the most stable being 44Ti with a half-life of 63 years, 45Ti with a half-life of 184.8 minutes, 51Ti with a half-life of 5.76 minutes, and 52Ti with a half-life of 1.7 minutes. All of the remaining radioactive isotopes have half-lives that are less than 33 seconds and the majority of these have half-lives that are less than half a second.HP Pavilion DV4-1014TX Battery

The isotopes of titanium range in atomic weight from 39.99 u (40Ti) to 57.966 u (58Ti). The primary decay mode before the most abundant stable isotope, 48Ti, iselectron capture and the primary mode after is beta emission. The primary decay products before 48Ti are element 21 (scandium) isotopes and the primary products after are element 23 (vanadium) isotopes.HP Pavilion DV4-1015TX Battery

Titanium was discovered included in a mineral in Cornwall, United Kingdom, in 1791 by amateur geologist and pastor William Gregor, then vicar of Creed parish.[29] He recognized the presence of a new element in ilmenite[4] when he found black sand by a stream in the nearbyparish of Manaccan and noticed the sand was attracted by a magnet.HP Pavilion DV4-1015TX Battery

Analysis of the sand determined the presence of two metal oxides;iron oxide (explaining the attraction to the magnet) and 45.25% of a white metallic oxide he could not identify.[27] Gregor, realizing that the unidentified oxide contained a metal that did not match the properties of any known element, reported his findings to the Royal Geological Society of Cornwall and in the German science journal Crell's Annalen.[HP Pavilion DV4-1016TX Battery

Around the same time, Franz-Joseph Müller von Reichenstein produced a similar substance, but could not identify it.[4] The oxide was independently rediscovered in 1795 by German chemist Martin Heinrich Klaproth in rutile from Hungary.[29] Klaproth found that it contained a new element and named it for the Titans of Greek mythology.HP Pavilion DV4-1017TX Battery

After hearing about Gregor's earlier discovery, he obtained a sample of manaccanite and confirmed it contained titanium.

The processes required to extract titanium from its various ores are laborious and costly; it is not possible to reduce in the normal manner, by heating in the presence of carbon, because that produces titanium carbide.HP Pavilion DV4-1018TX Battery

Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter at Rensselaer Polytechnic Institute by heating TiCl4with sodium at 700–800 °C in the Hunter process.[3] Titanium metal was not used outside the laboratory until 1932 when William Justin Kroll proved that it could be produced by reducing titanium tetrachloride (TiCl4) with calcium.HP Pavilion DV4-1019TX Battery

Eight years later he refined this process by using magnesium and even sodium in what became known as the Kroll process.[30]Although research continues into more efficient and cheaper processes (e.g., FFC Cambridge), the Kroll process is still used for commercial production.HP Pavilion DV4-1020TX Battery

Titanium of very high purity was made in small quantities when Anton Eduard van Arkel and Jan Hendrik de Boer discovered the iodide, or crystal bar, process in 1925, by reacting with iodine and decomposing the formed vapors over a hot filament to pure metal.HP Pavilion DV4-1020US Battery

In the 1950s and 1960s the Soviet Union pioneered the use of titanium in military and submarine applications (Alfa Class and Mike Class)[32] as part of programs related to the Cold War.[33] Starting in the early 1950s, titanium began to be used extensively for military aviation purposes, particularly in high-performance jets, starting with aircraft such as the F100 Super Sabre andLockheed A-12.HP Pavilion DV4-1021TX Battery

In the USA, the Department of Defense realized the strategic importance of the metal[34] and supported early efforts of commercialization.[35] Throughout the period of the Cold War, titanium was considered a Strategic Material by the U.S. government, and a large stockpile of titanium sponge was maintained by the Defense National Stockpile Center, which was finally depleted in 2005.HP Pavilion DV4-1022TX Battery

Today, the world's largest producer, Russian-based VSMPO-Avisma, is estimated to account for about 29% of the world market share.[37]

In 2006, the U.S. Defense Agency awarded $5.7 million to a two-company consortium to develop a new process for making titanium metal powder.HP Pavilion DV4-1023TX Battery

Under heat and pressure, the powder can be used to create strong, lightweight items ranging from armor plating to components for the aerospace, transportation, and chemical processing industries.HP Pavilion DV4-1024TX Battery

Production and fabrication

The processing of titanium metal occurs in 4 major steps:  reduction of titanium ore into "sponge", a porous form; melting of sponge, or sponge plus a master alloy to form an ingot; primary fabrication, where an ingot is converted into general mill products such as billet, bar, plate, sheet, strip, and tube; and secondary fabrication of finished shapes from mill products.HP Pavilion DV4-1025TX Battery

Titanium Sponge is only produced in 7 countries by 19 companies.

Because the metal reacts with oxygen at high temperatures it cannot be produced by reduction of its dioxide. Titanium metal is therefore produced commercially by the Kroll process, a complex and expensive batch process.HP Pavilion DV4-1026TX Battery

(The relatively high market value of titanium is mainly due to its processing, which sacrifices another expensive metal, magnesium. ) In the Kroll process, the oxide is first converted to chloride through carbochlorination, whereby chlorine gas is passed over red-hot rutile or ilmenite in the presence of carbon to make TiCl4.HP Pavilion DV4-1027TX Battery

This is condensed and purified by fractional distillation and then reduced with 800 °C molten magnesium in an argon atmosphere.

A more recently developed method, the FFC Cambridge process, may eventually replace the Kroll process. This method uses titanium dioxide powder (which is a refined form of rutile) as feedstock to make the end product which is either a powder or sponge.HP Pavilion DV4-1028TX Battery

If mixed oxide powders are used, the product is an alloy manufactured at a much lower cost than the conventional multi-step melting process. The FFC Cambridge process may render titanium a less rare and expensive material for the aerospace industry and the luxury goods market, and could be seen in many products currently manufactured using aluminium and specialist grades of steel.HP Pavilion DV4-1028US Battery

Common titanium alloys are made by reduction. For example, cuprotitanium (rutile with copper added is reduced), ferrocarbon titanium (ilmenite reduced with coke in an electric furnace), and manganotitanium (rutile with manganese or manganese oxides) are reduced.HP Pavilion DV4-1029TX Battery

2 FeTiO3 + 7 Cl2 + 6 C ? 2 TiCl4 + 2 FeCl3 + 6 CO (900 °C)
TiCl4 + 2 Mg ? 2 MgCl2 + Ti (1100 °C)

About 50 grades of titanium and titanium alloys are designated and currently used, although only a couple of dozen are readily available commercially.HP Pavilion DV4-1030EE Battery

The ASTM International recognizes 31 Grades of titanium metal and alloys, of which Grades 1 through 4 are commercially pure (unalloyed). These four are distinguished by their varying degrees of tensile strength, as a function of oxygen content, with Grade 1 being the most ductile (lowest tensile strength with an oxygen content of 0.18%), and Grade 4 the least (highest tensile strength with an oxygen content of 0.40%).HP Pavilion DV4-1030EI Battery

The remaining grades are alloys, each designed for specific purposes, be it ductility, strength, hardness, electrical resistivity, creep resistance, resistance to corrosion from specific media, or a combination thereof.HP Pavilion DV4-1030EJ Battery

The grades covered by ASTM and other alloys are also produced to meet Aerospace and Military specifications (SAE-AMS, MIL-T), ISO standards, and country-specific specifications, as well as proprietary end-user specifications for aerospace, military, medical, and industrial applications.HP Pavilion DV4-1030EN Battery

In terms of fabrication, all welding of titanium must be done in an inert atmosphere of argon or helium in order to shield it from contamination with atmospheric gases such as oxygen, nitrogen, or hydrogen. Contamination will cause a variety of conditions, such as embrittlement, which will reduce the integrity of the assembly welds and lead to joint failure.HP Pavilion DV4-1030TX Battery

Commercially pure flat product (sheet, plate) can be formed readily, but processing must take into account the fact that the metal has a "memory" and tends to spring back. This is especially true of certain high-strength alloys. Titanium cannot be soldered without first pre-plating it in a metal that is solderable.HP Pavilion DV4-1031TX Battery

The metal can be machined using the same equipment and via the same processes as stainless steel.[11]

Applications

Titanium is used in steel as an alloying element (ferro-titanium) to reduce grain size and as a deoxidizer, and in stainless steelto reduce carbon content.HP Pavilion DV4-1032TX Battery

Titanium is often alloyed with aluminium (to refine grain size), vanadium, copper (to harden), iron,manganese, molybdenum, and with other metals.[51] Applications for titanium mill products (sheet, plate, bar, wire, forgings, castings) can be found in industrial, aerospace, recreational, and emerging markets.HP Pavilion DV4-1033TX Battery

Powdered titanium is used in pyrotechnics as a source of bright-burning particles.

Pigments, additives and coatings

About 95% of titanium ore extracted from the Earth is destined for refinement into titanium dioxide (TiO2), an intensely white permanent pigment used in paints, paper, toothpaste, and plastics.HP Pavilion DV4-1034TX Battery

It is also used in cement, in gemstones, as an optical opacifier in paper,[53] and a strengthening agent in graphite composite fishing rods and golf clubs.

TiO2 powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and brilliant white color to the brown or gray chemicals that form the majority of household plastics.HP Pavilion DV4-1035LA Battery

In nature, this compound is found in the minerals anatase, brookite, and rutile.[2] Paint made with titanium dioxide does well in severe temperatures, is somewhat self-cleaning , and stands up to marine environments.[4] Pure titanium dioxide has a very high index of refraction and an optical dispersion higher than diamond.HP Pavilion DV4-1035TX Battery

In addition to being a very important pigment, titanium dioxide is also used in sunscreens due to its ability to protect skin by itself.[9] Recently, titanium oxide has been put to use in air purifiers (as a filter coating), or in film used to coat windows on buildings so that when titanium oxide becomes exposed to UV lightHP Pavilion DV4-1036TX Battery

(either solar or artificial) and moisture in the air, reactive redox species like hydroxyl radicals are produced so that they can purify the air or keep window surfaces clean.[54]

Aerospace and marine

Due to their high tensile strength to density ratio,[7] high corrosion resistance,[3] fatigue resistance, high crack resistance,[HP Pavilion DV4-1037TX Battery

and ability to withstand moderately high temperatures without creeping, titanium alloys are used in aircraft,armor plating, naval ships, spacecraft, and missiles. For these applications titanium alloyed with aluminium, vanadium, and other elements is used for a variety of components including critical structural parts,HP Pavilion DV4-1038TX Battery

fire walls, landing gear, exhaust ducts (helicopters), and hydraulic systems. In fact, about two thirds of all titanium metal produced is used in aircraft engines and frames.[56] The SR-71 "Blackbird" was one of the first aircraft to make extensive use of titanium within its structure, paving the way for its use in modern military and commercial aircraft.HP Pavilion DV4-1039TX Battery

An estimated 59 metric tons (130,000 pounds) are used in the Boeing 777, 45 in theBoeing 747, 18 in the Boeing 737, 32 in the Airbus A340, 18 in the Airbus A330, and 12 in the Airbus A320. The Airbus A380 may use 146 metric tons, including about 26 tons in the engines.HP Pavilion DV4-1040EE Battery

In engine applications, titanium is used for rotors, compressor blades, hydraulic system components, and nacelles. The titanium 6AL-4Valloy accounts for almost 50% of all alloys used in aircraft applications.[58]

Due to its high corrosion resistance to sea water, titanium is used to make propeller shafts and rigging and in the heat exchangers of desalination plants;HP Pavilion DV4-1040EI Battery

in heater-chillers for salt water aquariums, fishing line and leader, and for divers' knives. Titanium is used to manufacture the housings and other components of ocean-deployed surveillance and monitoring devices for scientific and military use. The former Soviet Union developed techniques for making submarines largely out of titanium.[HP Pavilion DV4-1040TX Battery

Industrial

Welded titanium pipe and process equipment (heat exchangers, tanks, process vessels, valves) are used in the chemical and petrochemical industries primarily for corrosion resistance. Specific alloys are used in downhole and nickel hydrometallurgyapplications due to their high strength (e. g.: titanium Beta C alloy), corrosion resistance, or combination of both.HP Pavilion DV4-1041TX Battery

The pulp and paper industry uses titanium in process equipment exposed to corrosive media such as sodium hypochlorite or wet chlorine gas (in the bleachery).[60] Other applications include: ultrasonic welding, wave soldering,[61] and sputtering targets.HP Pavilion DV4-1042TX Battery

Titanium tetrachloride (TiCl4), a colorless liquid, is important as an intermediate in the process of making TiO2 and is also used to produce the Ziegler-Natta catalyst, and is used to iridize glass and because it fumes strongly in moist air it is also used to make smoke screens.HP Pavilion DV4-1043TX Battery

Consumer and architectural

Titanium metal is used in automotive applications, particularly in automobile or motorcycle racing, where weight reduction is critical while maintaining high strength and rigidity.HP Pavilion DV4-1044TX Battery

The metal is generally too expensive to make it marketable to the general consumer market, other than high-end products, particularly for the racing/performance market. Late model Corvettes have been available with titanium exhausts.HP Pavilion DV4-1045TX Battery

Titanium is used in many sporting goods: tennis rackets, golf clubs, lacrosse stick shafts; cricket, hockey, lacrosse, and football helmet grills; and bicycle frames and components. Although not a mainstream material for bicycle production, titanium bikes have been used by race teams and adventure cyclists.HP Pavilion DV4-1046TX Battery

Titanium alloys are also used in spectacle frames.  This results in a rather expensive, but highly durable and long lasting frame which is light in weight and causes no skin allergies. Many backpackers use titanium equipment, including cookware, eating utensils, lanterns, and tent stakes.HP Pavilion DV4-1047TX Battery

Though slightly more expensive than traditional steel or aluminium alternatives, these titanium products can be significantly lighter without compromising strength. Titanium is also favored for use byfarriers, since it is lighter and more durable than steel when formed into horseshoes.HP Pavilion DV4-1048TX Battery

A titanium spork useful for backpackers. About 16 grams, lighter than a steel utensil but stronger than a plastic implement.

Titanium has occasionally been used in architectural applications: the 40 m (131 foot) memorial to Yuri Gagarin, the first man to travel in space, in Moscow, is made of titanium for the metal's attractive color and association with rocketry.HP Pavilion DV4-1049TX Battery

The Guggenheim Museum Bilbaoand the Cerritos Millennium Library were the first buildings in Europe and North America, respectively, to be sheathed in titanium panels.[56] Other construction uses of titanium sheathing include the Frederic C. Hamilton Building in Denver, Colorado and the 107 m (350 foot) Monument to the Conquerors of Space in Moscow.HP Pavilion DV4-1050 Battery

Because of its superior strength and light weight when compared to other metals traditionally used in firearms (steel, stainless steel, and aluminium), and advances in metalworking techniques, the use of titanium has become more widespread in the manufacture of firearms. Primary uses include pistol frames and revolver cylinders.

HP Pavilion DV4-1050EE Battery

HP Pavilion DV4-1050EL Battery

HP Pavilion DV4-1050EP Battery

HP Pavilion DV4-1050ER Battery

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For these same reasons, it is also used in the body of laptop computers (for example, in Apple's PowerBook line).

Some upmarket categories of tools made to be lightweight and corrosion-resistant, such as shovels and flashlights, are made of titanium or titanium alloys as well.HP Pavilion DV4-1051TX Battery

Jewelry

Because of its durability, titanium has become more popular for designer jewelry (particularly,titanium rings).[66] Its inertness makes it a good choice for those with allergies or those who will be wearing the jewelry in environments such as swimming pools.HP Pavilion DV4-1052 Battery

Titanium is also alloyed with gold to produce an alloy that can be marketed as 24-carat gold, as the 1% of alloyed Ti is insufficient to require a lesser mark. The resulting alloy is roughly the hardness of 14-carat gold and thus is more durable than a pure 24-carat gold item would be.HP Pavilion DV4-1052TX Battery

Titanium's durability, light weight, dent- and corrosion- resistance makes it useful in the production of watch cases.Some artists work with titanium to produce artworks such as sculptures, decorative objects and furniture.

The inertness and ability to be attractively colored makes titanium a popular metal for use in body piercing.HP Pavilion DV4-1053 Battery

Titanium may be anodized to produce various colors, which varies the thickness of the surface oxide layer and causes interference fringes.

Medical

Because it is biocompatible (non-toxic and is not rejected by the body), titanium is used in a gamut of medical applications including surgical implements and implants, such as hip balls and sockets (joint replacement) that can stay in place for up to 20 years.HP Pavilion DV4-1053TX Battery

The titanium is often alloyed with about 4% aluminium  or 6% Al and 4% vanadium.

Titanium has the inherent property to osseointegrate, enabling use in dental implants that can remain in place for over 30 years. This property is also useful for orthopedic implant applications.HP Pavilion DV4-1054TX Battery

These benefit from titanium's lower modulus of elasticity (Young's modulus) to more closely match that of the bone that such devices are intended to repair. As a result, skeletal loads are more evenly shared between bone and implant, leading to a lower incidence of bone degradation due to stress shielding and periprosthetic bone fractures which occur at the boundaries of orthopedic implants.HP Pavilion DV4-1055TX Battery

However, titanium alloys' stiffness is still more than twice that of bone so adjacent bone bears a greatly reduced load and may deteriorate.

Since titanium is non-ferromagnetic, patients with titanium implants can be safely examined with magnetic resonance imaging(convenient for long-term implants).HP Pavilion DV4-1070 Battery

Preparing titanium for implantation in the body involves subjecting it to a high-temperatureplasma arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized.

Titanium is also used for the surgical instruments used in image-guided surgery, as well as wheelchairs, crutches, and any other products where high strength and low weight are desirable.HP Pavilion DV4-1070EE Battery

Precautions

Titanium is non-toxic even in large doses and does not play any natural role inside the human body.An estimated quantity of 0.8 milligrams of titanium is ingested by humans each day, but most passes through without being absorbed.HP Pavilion DV4-1070EF Battery

It does, however, have a tendency to bio-accumulate in tissues that contain silica. An unknown mechanism in plants may use titanium to stimulate the production of carbohydrates and encourage growth. This may explain why most plants contain about 1 part per million (ppm) of titanium, food plants have about 2 ppm, and horsetail and nettle contain up to 80 ppm.HP Pavilion DV4-1070ER Battery

As a powder or in the form of metal shavings, titanium metal poses a significant fire hazard and, when heated in air, an explosion hazard. Water and carbon dioxide-based methods to extinguish fires are ineffective on burning titanium; Class D dry powder fire fighting agents must be used instead.HP Pavilion DV4-1070ES Battery

When used in the production or handling of chlorine, care must be taken to use titanium only in locations where it will not be exposed to dry chlorine gas which can result in a titanium/chlorine fire. A fire hazard exists even when titanium is used in wet chlorine due to possible unexpected drying brought about by extreme weather conditions.HP Pavilion DV4-1080EI Battery

Titanium can catch fire when a fresh, non-oxidized surface comes in contact with liquid oxygen. Such surfaces can appear when the oxidized surface is struck with a hard object, or when a mechanical strain causes the emergence of a crack. This poses the possible limitation for its use in liquid oxygen systems, such as those found in the aerospace industry.HP Pavilion DV4-1080EO Battery

Titanium rings are jewelry rings or bands which have been primarily constructed from titanium. The actual compositions of titanium can vary, such as "commercial pure" (99.2% titanium) or "aircraft grade" (primarily, 90% titanium, 6% aluminum, 4% vanadium),HP Pavilion DV4-1080ES Battery

and titanium rings are often crafted in combination with other materials, such as gemstones and traditional jewelry metals. Even with these variations in composition and materials, titanium rings are commonly referred to as such if they contain any amount of titanium.HP Pavilion DV4-1090EO Battery

Rings crafted from titanium are a modern phenomenon, becoming widely available on the market around the 1990s. Titanium rings offer several unique properties: they are biocompatible (hypoallergenic), lightweight, corrosion-resistant, and have the highest strength-to-weight ratio of any metal.HP Pavilion DV4-1090ES Battery

Titanium was discovered in Cornwall, England, in 1791 by William Gregor. It was also discovered around the same time by Hungarian mineralogist Franz-Joseph Müller von Reichenstein, and later in 1795 by German chemist Martin Heinrich Klaproth – the latter of which gave titanium its name, after the Titans of Greek mythology.HP Pavilion DV4-1100 Battery

However, it was not until after 1932 that commercial use for titanium became possible, due to methods established by William Justin Kroll. Kroll devised ways of reducing titanium tetrachloride (TiCl4) into its metal form.[3] His process is still used today for commercially-produced titanium.HP Pavilion DV4-Battery

The value of titanium rings can be very high. This is ostensibly because the process of extracting titanium from its various ores is laborious and costly.[2]Although it is indeed expensive as an engineering material, it is still cheaper than the jeweller's usual precious metals, even silver.HP Pavilion DV4-1101 Battery

It is unknown who first crafted titanium into a ring or other jewelry piece. Titanium started appearing on the open market in approximately the 1990s. Since 2000, availability of titanium rings has become large-scale, with most online and bricks-and-mortar jewelry stores likely to carry titanium-based rings as part of their inventory.HP Pavilion DV4-1101TU Battery

Many outlets now specialize exclusively in the design and sale of titanium rings.

Construction

Titanium rings are constructed using solid bars, tubes or sheets of titanium, which are cut into the desired shape and size of a ring. The metal can be machined using the same equipment and via the same engineering processes as stainless steel.HP Pavilion DV4-1101TX Battery

The usual jewelry-making techniques of rolling and soldering are not practical for titanium.

Properties

Titanium has become popular as a jewelry material due to its various unique properties. Titanium is biocompatible (often referred to as hypoallergenic), or non-toxic to the human body.HP Pavilion DV4-1102 Battery

Similarly, titanium rings will not react with wearers who suffer allergies to other jewelry materials.

It is highly resistant to most causes of corrosion, including sea water, aqua regia, chlorine (in water), and some acids. It is soluble in concentrated acids, however.HP Pavilion DV4-1102TU Battery

Titanium rings are therefore practical for those who regularly swim in the ocean or chlorinated pools, for example. This is in contrast to some traditional jewelry materials, such as silver, brass and bronze, which are prone to tarnishing and other manifestations of deterioration.HP Pavilion DV4-1102TX Battery

Titanium rings, depending on composition, have varying degrees of fatigue resistance and tensile strength. However, almost all well-known compositions feature higher fatigue resistance, as well as strength-to-weight ratios, than most – if not all - known metals.

Titanium rings are almost impossible to resize.HP Pavilion DV4-1103TU Battery

They are only slightly more difficult to cut off in case of emergency than for gold rings; titanium is comparable tosteel in its resistance to sawing.

Anodization

Anodization of titanium rings is the process whereby an oxide film is formed on the surface of the titanium via an electrolytic process to create color.HP Pavilion DV4-1103TX Battery

In the case of titanium rings, this process is performed after it is machined into shape. Oxidation changes the ordinary titanium color (generally silver, depending on composition and processing) and increases corrosion-resistance. The anodization process is extremely simple to carry out:HP Pavilion DV4-1104TU Battery

the piece is immersed in an electrolyte,cola is popularly used, and a DC voltage, around 100V, is applied. The voltage controls the thickness, and thus the colour, of the anodization.

Dyes are not necessary in the anodization of titanium. The color that results on a titanium ring depends on the thickness of the oxide coating, which is determined by the anodizing voltage.HP Pavilion DV4-1104TX Battery

The image to the left shows the color spectrum range that can be achieved via anodization. The colors, which are simply different wavelengths of light, arise from constructive interferencebetween the light reflected from the surface of the oxide layer and light reflected from the metal surface below.HP Pavilion DV4-1105EF Battery

Titanium compositions

Titanium can be alloyed with many other metals to enhance or alter titanium's properties. The most common alloy partners for titanium are aluminum, vanadium, iron, molybdenum and copper. Each alters titanium's properties for various purposes – for example, copper can be used to harden titanium.HP Pavilion DV4-1105EM Battery

One of the most common compositions for titanium rings is known as "aircraft grade" (also referred to as 6AL-4V or 6-4) titanium, because the composition is famous for its use in aircraft construction (however, it is also used for medical, marine and chemical processing purposes).HP Pavilion DV4-1105TU Battery

It is a blend of 6% aluminum, 4% vanadium and 90% titanium (as well as trace amounts of iron and oxygen; max 0.25% and 0.2% respectively), and is one of the strongest and most lightweight of other known compositions. Aircraft grade titanium is often used in crafting titanium rings due to its advantageous and suitable properties (compared with other titanium compositions), as well as its wide commercial availability.HP Pavilion DV4-1105TX Battery

Inlays

Inlays are the result of combining or joining two or more metals into one ring. It is not to be confused with alloying. The process of inlaying involves crushing the metals into channels, which are then trapped under pressure. On a ring, this usually results in metals sitting side-by-side on the surface – for example, a strip of gold running through the middle of an otherwise titanium ring.HP Pavilion DV4-1106EE Battery

The purpose of inlays are to enable the various metals within a titanium ring to be visibly distinguishable.

Classic

Titanium ring styles referred to as "classic" have generally been crafted into a simple oval or circle with a smooth, shiny finish. Besides ordinary machining, no external techniques or equipment are used in its production.HP Pavilion DV4-1106EM Battery

Mokume-gane

Mokume-gane gives titanium rings the appearance of wood-grain. It is a Japanese (also early Medieval European) forging technique that was applied to Samurai swords in the 17th century. It required great skill on the part of the smith; though modern process today, such as controlled atmospheres and temperature-controlled furnaces make the technique easier to achieve.HP Pavilion DV4-1106TX Battery

Titanium nitride (TiN) (sometimes known as “Tinite” or “TiNite” or “TiN”) is an extremely hard ceramic material, often used as a coating on titanium alloys, steel, carbide, and aluminium components to improve the substrate's surface properties.HP Pavilion DV4-1107TX Battery

Applied as a thin coating, TiN is used to harden and protect cutting and sliding surfaces, for decorative purposes (due to its gold appearance), and as a non-toxic exterior for medical implants. In most applications a coating of less than 5 micrometres (0.00020 in) is applied.HP Pavilion DV4-1108TX Battery

TiN will oxidize at 800 °C at normal atmosphere. It is chemically stable at room temperature and is attacked by hot concentrated acids.[1]

TiN has excellent infrared (IR) reflectivity properties, reflecting in a spectrum similar to elemental gold (Au), which gives it a yellowish color.HP Pavilion DV4-1109TX Battery

Depending on the

substrate material and surface finish, TiN will have a coefficient of friction ranging from 0.4 to 0.9 versus itself (non-lubricated). Typical formation has a crystal structure of NaCl-type with a roughly 1:1stoichiometry; however TiNx compounds with x ranging from 0.6 to 1.2 are thermodynamically stable.HP Pavilion DV4-1110EO Battery

A thin film of titanium nitride was chilled to near absolute zero converting it into the first known superinsulator, with resistance suddenly increased by a factor of 100,000.

A well-known use for TiN coating is for edge retention and corrosion resistance on machine tooling, such asdrill bits and milling cutters, often improving their lifetime by a factor of three or more.HP Pavilion DV4-1110TX Battery

Because of TiN's metallic gold color, it is used to coat costume jewelry and automotive trim for decorative purposes. TiN is also widely used as a top-layer coating, usually with nickel (Ni) or chromium (Cr) plated substrates, on consumer plumbing fixtures and door hardware.HP Pavilion DV4-1111TX Battery

As a coating it is used in aerospace and military applications and to protect the sliding surfaces ofsuspension forks of bicycles and motorcycles as well as the shock shafts of radio controlled cars. TiN is non-toxic, meets FDAguidelines and has seen use in medical devices such as scalpel blades and orthopedic bone saw blades where sharpness and edge retention are important.HP Pavilion DV4-1112TX Battery

TiN coatings have also been used in implanted prostheses (especially hip replacement implants) and other medical implants.

Though less visible, thin films of TiN are also used in microelectronics, where they serve as conductive barrier between the active device and the metal contacts used to operate it.HP Pavilion DV4-1113TX Battery

While the film blocks diffusion of metal into the silicon, it is conductive enough (30–70 ??·cm) to allow a good electrical connection. In this context, TiN is classified as a "barrier metal", even though it is clearly a ceramic from the perspective of chemistry or mechanical behavior.HP Pavilion DV4-1114NR Battery

Recent chip design in the 45 nm technology and beyond also makes use of TiN as a metal material for improved transistor performance. In combination withgate dielectrics (e.g. HfSiO) that have a higher permittivity compared to standard SiO2 the gate length can be scaled down with low leakage, higher drive current and same or better threshold voltage.HP Pavilion DV4-1114TX Battery

Due to their high biostability, TiN layers may also be used as electrodes in bioelectronic applications [7] like in intelligentimplants or in-vivo biosensors that have to withstand the severe corrosion caused by the body fluid. TiN electrodes have already been applied in the subretinal prothesis project [8] as well as in biomedical microelectromechanical systems (BioMEMS).HP Pavilion DV4-1115EF Battery

Fabrication

The most common methods of TiN thin film creation are physical vapor deposition (PVD, usually sputter deposition, cathodic arc deposition or electron beam heating) and chemical vapor deposition (CVD). In both methods, pure titanium is sublimated and reacted with nitrogen in a high-energy, vacuum environment.HP Pavilion DV4-1115TX Battery

TiN film may also be produced on Ti workpieces by reactive growth (for example, annealing) in a nitrogen atmosphere. PVD is preferred for steel parts because the deposition temperatures exceeds the austenitizing temperature of steel. TiN layers are also sputtered on a variety of higher melting point materials such asstainless steels, titanium and titanium alloys.HP Pavilion DV4-1116TX Battery

Its high Young's modulus (values between 450 and 590 GPa have been reported in the literature [11]) means that thick coatings tend to flake away, making them much less durable than thin ones. Titanium nitride coatings can also be deposited by thermal spraying whereas TiN powders are produced by nitridation of titanium with nitrogen or ammonia at 1200 °C.HP Pavilion DV4-1117CA Battery

Bulk ceramic objects can be fabricated by packing powdered metallic titanium into the desired shape, compressing it to the proper density, then igniting it in an atmosphere of pure nitrogen. The heat released by the chemical reaction between the metal and gas is sufficient to sinter the nitride reaction product into a hard, finished item. See powder metallurgy.HP Pavilion DV4-1117TX Battery

Other commercial variants

There are several commercially-used variants of TiN that have been developed in the past decade, such as titanium carbon nitride (TiCN), titanium aluminium nitride (TiAlN or AlTiN), and titanium aluminum carbon nitride, which may be used individually or in alternating layers with TiN.HP Pavilion DV4-1118CA Battery

These coatings offer similar or superior enhancements in corrosion resistance and hardness, and additional colors ranging from light gray to nearly black, to a dark iridescent bluish-purple depending on the exact process of application. These coatings are becoming common on sporting goods, particularly knives and handguns, where they are used for both cosmetic and functional reasons.HP Pavilion DV4-1118TX Battery

As a constituent in steel making

Titanium nitride is also produced intentionally within some steels by judicious addition of titanium to the alloy. TiN forms at very high temperatures because of its very low enthalpy of formation, and even nucleates directly from the melt in secondary steelmaking.HP Pavilion DV4-1119TX Battery

It forms discrete, micrometre-sized cubic particles at grain boundaries and triple points, and prevents grain growth by Ostwald ripening up to very highhomologous temperatures. Titanium nitride has the lowest solubility product of any metal nitride or carbide in austenite, a useful attribute in microalloyed steelformulas.HP Pavilion DV4-1120BR Battery

Titanium dioxide, also known as titanium(IV) oxide or titania, is the naturally occurring oxide of titanium, chemical formula TiO2. When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase.HP Pavilion DV4-1120TX Battery

It has a wide range of applications, from paint to sunscreen to food colouring. When used as a food colouring, it has E number E171.

Titanium dioxide occurs in nature as well-known minerals rutile, anatase and brookite, and additionally as two high pressure forms, a monoclinic baddeleyite-like form and an orthorhombic ?-PbO2-like form, both found recently at the Ries crater inBavaria.[HP Pavilion DV4-1120US Battery

The most common form is rutile,[3] which is also the equilibrium phase at all temperatures.[4] The metastableanatase and brookite phases both convert to rutile upon heating.[3][5] Rutile, anatase and brookite all contain six coordinated titanium.HP Pavilion DV4-1121BR Battery

Titanium dioxide has eight modifications – in addition to rutile, anatase and brookite there are three metastable forms produced synthetically (monoclinic, tetragonal and orthorombic), and five high pressure forms (?-PbO2-like, baddeleyite-like,cotunnite-like, orthorhombic OI, and cubic phases):HP Pavilion DV4-1121CA Battery

The cotunnite-type phase was claimed by L. Dubrovinsky and co-authors to be the hardest known oxide with the Vickers hardnessof 38 GPa and the bulk modulus of 431 GPa (i.e. close to diamond's value of 446 GPa) at atmospheric pressure.HP Pavilion DV4-1121TX Battery

However, later studies came to different conclusions with much lower values for both the hardness (7–20 GPa, which makes it softer than common oxides like corundum Al2O3 and rutile TiO2) [14] and bulk modulus (~300 GPa) .

The naturally occurring oxides can be mined and serve as a source for commercial titanium.HP Pavilion DV4-1122TX Battery

The metal can also be mined from other minerals such as ilmenite or leucoxene ores, or one of the purest forms, rutile beach sand. Star sapphires and rubiesget their asterism from rutile impurities present in them.[17]

Titanium dioxide (B) is found as a mineral in magmatic rocks and hydrothermal veins, as well as weathering rims onperovskite. TiO2also forms lamellae in other minerals.HP Pavilion DV4-1123LA Battery

Spectral lines from titanium oxide are prominent in class M stars, which are cool enough to allow molecules of this chemical to form.

Production

Crude titanium dioxide is purified via converting to titanium tetrachloride in the chloride process.HP Pavilion DV4-1123TX Battery

In this process, the crude ore (containing at least 70% TiO2) is reduced with carbon, oxidized with chlorine to give titanium tetrachloride; i.e., carbothermal chlorination. This titanium tetrachloride is distilled, and re-oxidized in a pure oxygen flame or plasma at 1500–2000 K to give pure titanium dioxide while also regenerating chlorine.HP Pavilion DV4-1123US Battery

Aluminium chloride is often added to the process as a rutile promotor; the product is mostly anatase in its absence.

Another widely used process utilizes ilmenite as the titanium dioxide source, which is digested in sulfuric acid. The by-product iron(II) sulfate is crystallized and filtered-off to yield only the titanium salt in the digestion solution, which is processed further to give pure titanium dioxide.HP Pavilion DV4-1124LA Battery

Another method for upgrading ilmenite is called the Becher Process. One method for the production of titanium dioxide with relevance to nanotechnology is solvothermal Synthesis of titanium dioxide.

Nanotubes

Anatase can be converted by hydrothermal synthesis to delaminated anatase inorganic nanotubes  and titanate nanoribbonswhich are of potential interest as catalytic supports and photocatalysts.HP Pavilion DV4-1124NR Battery

In the synthesis, anatase is mixed with 10 M sodium hydroxide and heated at 130 °C for 72 hours. The reaction product is washed with dilute hydrochloric acid and heated at 400 °C for another 15 hours. The yield of nanotubes is quantitative and the tubes have an outer diameter of 10 to 20 nm and an inner diameter of 5 to 8 nm and have a length of 1 ?m.HP Pavilion DV4-1124TX Battery

A higher reaction temperature (170 °C) and less reaction volume gives the corresponding nanowires.

Another process for synthesizing TiO2 is through Anodization in an electrolytic solution. When anodized in a 0.5 weight percent HF solution for 20 minutes, well-aligned titanium oxide nanotube arrays can be fabricated an average tube diameter of 60 nm and length of 250 nm.HP Pavilion DV4-1125BR Battery

Based on X-ray Diffraction, nanotubes grown through anodization are amorphous.

Titanium dioxide is the most widely used white pigment because of its brightness and very high refractive index (n = 2.7), in which it is surpassed only by a few other materials. Approximately 4 million tons of pigmentary TiO2 are consumed annually worldwide.HP Pavilion DV4-1125LA Battery

When deposited as a thin film, its refractive index and colour make it an excellent reflective optical coating for dielectric mirrors and some gemstones like "mystic fire topaz". TiO2 is also an effective opacifier in powder form, where it is employed as a pigment to provide whiteness and opacity to products such as paints, coatings, plastics, papers, inks, foods, medicines (i.e. pills and tablets) as well as most toothpastes.HP Pavilion DV4-1125NR Battery

In paint, it is often referred to offhandedly as "the perfect white", "the whitest white", or other similar terms. Opacity is improved by optimal sizing of the titanium dioxide particles.

In ceramic glazes titanium dioxide acts as an opacifier and seeds crystal formation.HP Pavilion DV4-1125TX Battery

Titanium dioxide is often used to whiten skimmed milk; this has been shown statistically to increase skimmed milk's palatability.[23]

Titanium dioxide is used to mark the white lines on the tennis courts of the All England Lawn Tennis and Croquet Club, best known as the venue for the annual grand slam tennis tournament The Championships, Wimbledon.HP Pavilion DV4-1126LA Battery

The exterior of the Saturn V rocket was painted with titanium dioxide; this later allowed astronomers to determine that J002E3 was the S-IVB stage from Apollo 12 and not an asteroid.

Sunscreen and UV absorber

In cosmetic and skin care products, titanium dioxide is used as a pigment, sunscreen and a thickener.HP Pavilion DV4-1126TX Battery

It is also used as a tattoo pigment and in styptic pencils. Titanium dioxide is produced in varying particle sizes, oil and water dispersible, and with varying coatings for the cosmetic industry. This pigment is used extensively in plastics and other applications for its UV resistant properties where it acts as a UV absorber, efficiently transforming destructive UV light energy into heat.HP Pavilion DV4-1127LA Battery

Titanium dioxide is found in almost every sunscreen with a physical blocker because of its high refractive index, its strong UV light absorbing capabilities and its resistance to discolouration under ultraviolet light. This advantage enhances its stability and ability to protect the skin from ultraviolet light.HP Pavilion DV4-1127TX Battery

Sunscreens designed for infants or people with sensitive skin are often based on titanium dioxide and/or zinc oxide, as these mineral UV blockers are believed to cause less skin irritation than other UV absorbing chemicals. The titanium dioxide particles used in sunscreens have to be coated with silica or alumina, because titanium dioxide creates radicals in the photocatalytic reaction.HP Pavilion DV4-1128TX Battery

These radicals are carcinogenic, and could damage the skin.

Photocatalyst

Titanium dioxide, particularly in the anatase form, is a photocatalyst under ultraviolet (UV) light. Recently it has been found that titanium dioxide, when spiked with nitrogen ions or doped with metal oxide like tungsten trioxide, is also a photocatalyst under either visible or UV light.HP Pavilion DV4-1129LA Battery

The strong oxidative potential of the positive holes oxidizes water to create hydroxyl radicals. It can also oxidize oxygen or organic materials directly. Titanium dioxide is thus added to paints, cements, windows, tiles, or other products for its sterilizing, deodorizing and anti-fouling properties and is used as a hydrolysis catalyst.HP Pavilion DV4-1129TX Battery

It is also used in dye-sensitized solar cells, which are a type of chemical solar cell (also known as a Graetzel cell).

The photocatalytic properties of titanium dioxide were discovered by Akira Fujishima in 1967 and published in 1972.  The process on the surface of the titanium dioxide was called the Honda-Fujishima effect.HP Pavilion DV4-1130BR Battery

Titanium dioxide has potential for use in energy production: as a photocatalyst, it can carry out hydrolysis; i.e., break water into hydrogen and oxygen. Were the hydrogen collected, it could be used as a fuel. The efficiency of this process can be greatly improved by doping the oxide with carbon.HP Pavilion DV4-1130TX Battery

Further efficiency and durability has been obtained by introducing disorder to the lattice structure of the surface layer of titanium dioxide nanocrystals, permitting infrared absorption.

Titanium dioxide can also produce electricity when in nanoparticle form. Research suggests that by using these nanoparticles to form the pixels of a screen, they generate electricity when transparent and under the influence of light.HP Pavilion DV4-1131BR Battery

If subjected to electricity on the other hand, the nanoparticles blacken, forming the basic characteristics of a LCD screen. According to creator Zoran Radivojevic, Nokia has already built a functional 200-by-200-pixel monochromatic screen which is energetically self-sufficient.HP Pavilion DV4-1131TX Battery

In 1995 Fujishima and his group discovered the superhydrophilicity phenomenon for titanium dioxide coated glass exposed to sun light.[26] This resulted in the development of self-cleaning glass and anti-fogging coatings.

TiO2 incorporated into outdoor building materials, such as paving stones in noxer blocks or paints, can substantially reduce concentrations of airborne pollutants such as volatile organic compounds and nitrogen oxides.HP Pavilion DV4-1132TX Battery

A photocatalytic cement that uses titanium dioxide as a primary component, produced by Italcementi Group, was included in Time's Top 50 Inventions of 2008.

TiO2 offers great potential as an industrial technology for detoxification or remediation of wastewater due to several factors.HP Pavilion DV4-1133TX Battery

  1. The process occurs under ambient conditions very slowly; direct UV light exposure increases the rate of reaction.
  2. The formation of photocyclized intermediate products, unlike direct photolysis techniques, is avoided.
  3. Oxidation of the substrates to CO2 is complete.HP Pavilion DV4-1134TX Battery
  1. The photocatalyst is inexpensive and has a high turnover.
  2. TiO2 can be supported on suitable reactor substrates.
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Electronic data storage medium

Researchers at the University of Tokyo, Japan have created a 25 terabyte titanium oxide-based disc.HP Pavilion DV4-1135BR Battery

Other applications

  • Titanium dioxide in solution or suspension can be used to cleave protein that contains the amino acid proline at the site where proline is present. This breakthrough in cost-effective protein splitting took place at Arizona State University in 2006.HP Pavilion DV4-1135EE Battery
  • Titanium dioxide is also used as a material in the memristor, a new electronic circuit element. It can be employed for solar energy conversion based on dye, polymer, or quantum dot sensitized nanocrystalline TiO2 solar cells using conjugated polymersas solid electrolytes.HP Pavilion DV4-1135EI Battery
  • Synthetic single crystals and films of TiO2 are used as a semiconductor,[35] and also in Bragg-stack style dielectric mirrorsdue to the high refractive index of TiO2 (2.5 – 2.9).

Health and safety

Titanium dioxide is incompatible with strong reducing agents and strong acids.HP Pavilion DV4-1135TX Battery

Violent or incandescent reactions occur with molten metals that are veryelectropositive, e.g. aluminium, calcium, magnesium, potassium, sodium, zinc and lithium.[39]

Titanium dioxide accounts for 70% of the total production volume of pigments worldwide. It is widely used to provide whiteness and opacity to products such as paints, plastics, papers, inks, foods, and toothpastes.HP Pavilion DV4-1136BR Battery

It is also used in cosmetic and skin care products, and it is present in almost every sunblock, where it helps protect the skin from ultraviolet light.

Many sunscreens use nanoparticle titanium dioxide (along with nanoparticle zinc oxide) which does get absorbed into the skin.[40][41] The effects on human health are not yet well understood.HP Pavilion DV4-1136TX Battery

Titanium dioxide dust, when inhaled, has been classified by the International Agency for Research on Cancer (IARC) as an IARC Group 2B carcinogen possibly carcinogenic to humans.HP Pavilion DV4-1137TX Battery

The findings of the IARC are based on the discovery that high concentrations of pigment-grade (powdered) and ultrafine titanium dioxide dust caused respiratory tract cancer in rats exposed by inhalation and intratracheal instillation.The series of biological events or steps that produce the rat lung cancersHP Pavilion DV4-1138TX Battery

(e.g. particle deposition, impaired lung clearance, cell injury, fibrosis, mutations and ultimately cancer) have also been seen in people working in dusty environments. Therefore, the observations of cancer in animals were considered, by IARC, as relevant to people doing jobs with exposures to titanium dioxide dust. HP Pavilion DV4-1139TX Battery

For example, titanium dioxide production workers may be exposed to high dust concentrations during packing, milling, site cleaning and maintenance, if there are insufficient dust control measures in place. However, the human studies conducted so far do not suggest an association between occupational exposure to titanium dioxide and an increased risk for cancer.HP Pavilion DV4-1140EK Battery

The safety of the use of nano-particle sized titanium dioxide, which can penetrate the body and reach internal organs, has been criticized.[45] Studies have also found that titanium dioxide nanoparticles cause genetic damage in mice.

Titanium alloys are metallic materials which contain a mixture of titanium and other chemical elements.HP Pavilion DV4-1140GO Battery

Such alloys have very high tensile strength and toughness(even at extreme temperatures), light weight, extraordinary corrosion resistance, and ability to withstand extreme temperatures. However, the high cost of both raw materials and processing limit their use to military applications, aircraft, spacecraft, medical devices,HP Pavilion DV4-1140TX Battery

connecting rods on expensive sports cars and some premiumsports equipment and consumer electronics. Auto manufacturers Porsche and Ferrari also use titanium alloys in engine components due to its durable properties in these high stress engine environments.HP Pavilion DV4-1141TX Battery

Although "commercially pure" titanium has acceptable mechanical properties and has been used for orthopedic and dental implants, for most applications titanium is alloyed with small amounts of aluminum and vanadium, typically 6% and 4% respectively, by weight.HP Pavilion DV4-1142TX Battery

This mixture has a solid solubility which varies dramatically with temperature, allowing it to undergo precipitation strengthening. This heat treatment process is carried out after the alloy has been worked into its final shape but before it is put to use, allowing much easier fabrication of a high-strength product.HP Pavilion DV4-1143GO Battery

Transition temperature

The crystal structure of titanium at ambient temperature and pressure is close-packed hexagonal ? phase with a c/a ratio of 1.587. At about 890°C, the titanium undergoes an allotropic transformation to a body-centred cubic ? phase which remains stable to the melting temperature.HP Pavilion DV4-1143TX Battery

Some alloying elements raise the alpha-to-beta transition temperature[1] (i.e. alpha stabilizers) while others lower the transition temperature (i.e. beta stabilizers). Aluminium, gallium, germanium, carbon,oxygen and nitrogen are alpha stabilizers.HP Pavilion DV4-1144TX Battery

HP Pavilion DV4-1150EP Battery

Molybdenum, vanadium, tantalum, niobium, manganese, iron, chromium, cobalt, nickel, copper and silicon are beta stabilizers.[2]

Categories

Titanium Alloys are generally classified into four main categories:

  • Alpha alloys which contain neutral alloying elements (such as tin) and/ or alpha stabilisers (such as aluminium or oxygen) only. These are not heat treatable.HP Pavilion DV4-1144US Battery
  • Near-alpha alloys contain small amount of ductile beta-phase. Besides alpha-phase stabilisers, near-alpha alloys are alloyed with 1-2% of beta phase stabilizers such as molybdenum, silicon or vanadium.
  • Alpha & Beta Alloys, which are metastable and generally include some combination of both alpha and beta stabilisers, and which can be heat treated.HP Pavilion DV4-1145BR Battery
  • Beta Alloys, which are metastable and which contain sufficient beta stabilisers (such as molybdenum, silicon and vanadium) to allow them to maintain the beta phase when quenched, and which can also be solution treated and aged to improve strength.HP Pavilion DV4-1145GO Battery

Properties

Generally, beta-phase titanium is stronger yet less ductile and alpha-phase titanium is more ductile. Alpha-beta-phase titanium has a mechanical property which is in between both.

Titanium dioxide dissolves in the metal at high temperatures, and its formation is very energetic.HP Pavilion DV4-1145TX Battery

These two factors mean that all titanium except the most carefully purified has a significant amount of dissolved oxygen, and so may be considered a Ti-O alloy. Oxide precipitates offer some strength (as discussed above), but are not very responsive to heat treatment and can substantially decrease the alloy's toughness.HP Pavilion DV4-1146TX Battery

Many alloys also contain titanium as a minor additive, but since alloys are usually categorized according to which element forms the majority of the material, these are not usually considered to be "titanium alloys" as such. See the sub-article on titanium applications.HP Pavilion DV4-1147CL Battery

Titanium alone is a strong, light metal. It is as strong as steel, but 45% lighter. It is also twice as strong as aluminium but only 60% heavier. Titanium is not easily corroded by sea water, and thus is used in propeller shafts, rigging and other parts of boats that are exposed to sea water.HP Pavilion DV4-1147TX Battery

Titanium and its alloys are used in airplanes, missiles and rockets where strength, low weight and resistance to high temperatures are important. Further, since titanium does not react within the human body, it and its alloys are used to create artificial hips, pins for setting bones, and for other biological implants. See Titanium#Orthopedic_implants.HP Pavilion DV4-1148TX Battery

Grades

The ASTM defines a number of alloy standards with a numbering scheme[4] for easy reference.

  • Grade 1-4 are unalloyed and considered commercially pure or "CP". Generally the tensile and yield strength goes up with grade number for these "pure" grades.HP Pavilion DV4-1149TX Battery
  • The difference in their physical properties is primarily due to the quantity of interstitial elements. They are used for corrosion resistance applications where cost and ease of fabrication and welding are important.
  • Grade 5, also known as Ti6Al4VTi-6Al-4V or Ti 6-4, is the most commonly used alloy.HP Pavilion DV4-1150BR Battery
  • It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium.[5] Grade 5 is used extensively in Aerospace, Medical, Marine, and Chemical Processing.[6] It is used for connecting rods in internal combustion engines.HP Pavilion DV4-1150EO Battery
  • It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti).[7] Among its many advantages, it is heat treatable.HP Pavilion DV4-1150ER Battery
  • This grade is an excellent combination of strength, corrosion resistance, weld and fabricability. In consequence, its uses are numerous such as for military aircraft or turbines. It is also used in surgical implants.[5] Generally, it is used in applications up to 400 degrees Celsius.HP Pavilion DV4-1150ES Battery

It has a density of roughly 4420 kg/m3, Young's modulus of 110 GPa, and tensile strength of 1000 MPa.[8] By comparison, annealed type 316 stainless steel has a density of 8000 kg/m3, modulus of 193 GPa, and tensile strength of only 570 MPa.[9] And tempered 6061 aluminium alloy has 2700 kg/m3, 69 GPa, and 310 MPa, respectively.HP Pavilion DV4-1150TX Battery

  • Grade 6 contains 5% aluminium and 2.5% tin. It is also known as Ti-5Al-2.5Sn. This alloy is used in airframes and jet engines due to its good weldability, stability and strength at elevated temperatures.
  • Grade 7 contains 0.12 to 0.25% palladium. This grade is similar to Grade 2. The small quantity of palladium added gives it enhanced crevice corrosion resistance at low temperatures and high pH.HP Pavilion DV4-1151TX Battery
  • Grade 7H contains 0.12 to 0.25% palladium. This grade has enhanced corrosion resistance.
  • Grade 9 contains 3.0% aluminium and 2.5% vanadium. This grade is a compromise between the ease of welding and manufacturing of the "pure" grades and the high strength of Grade 5. It is commonly used in aircraft tubing for hydraulics and in athletic equipment.HP Pavilion DV4-1152TX Battery
  • Grade 11 contains 0.12 to 0.25% palladium. This grade has enhanced corrosion resistance.
  • Grade 12 contains 0.3% molybdenum and 0.8% nickel.
  • Grades 1314, and 15 all contain 0.5% nickel and 0.05% ruthenium.
  • Grade 16 contains 0.04 to 0.08% palladium. This grade has enhanced corrosion resistance.HP Pavilion DV4-1153TX Battery
  • Grade 16H contains 0.04 to 0.08% palladium.
  • Grade 17 contains 0.04 to 0.08% palladium. This grade has enhanced corrosion resistance.
  • Grade 18 contains 3% aluminium, 2.5% vanadium and 0.04 to 0.08% palladium. This grade is identical to Grade 9 in terms of mechanical characteristics. The added palladium gives it increased corrosion resistance.HP Pavilion DV4-1154TX Battery
  • Grade 19 contains 3% aluminium, 8% vanadium, 6% chromium, 4% zirconium, and 4% molybdenum.
  • Grade 20 contains 3% aluminium, 8% vanadium, 6% chromium, 4% zirconium, 4% molybdenum and 0.04% to 0.08% palladium.HP Pavilion DV4-1155SE Battery
  • Grade 21 contains 15% molybdenum, 3% aluminium, 2.7% niobium, and 0.25% silicon.
  • Grade 23 contains 6% aluminium, 4% vanadium, 0.13% (maximum) Oxygen. Improved ductility and fracture toughness with some reduction in strength.HP Pavilion DV4-1155TX Battery
  • Grade 24 contains 6% aluminium, 4% vanadium and 0.04% to 0.08% palladium.
  • Grade 25 contains 6% aluminium, 4% vanadium and 0.3% to 0.8% nickel and 0.04% to 0.08% palladium.
  • Grades 2626H, and 27 all contain 0.08 to 0.14% ruthenium.HP Pavilion DV4-1156TX Battery
  • Grade 28 contains 3% aluminium, 2.5% vanadium and 0.08 to 0.14% ruthenium.
  • Grade 29 contains 6% aluminium, 4% vanadium and 0.08 to 0.14% ruthenium.
  • Grades 30 and 31 contain 0.3% cobalt and 0.05% palladium.

HP Pavilion DV4-1157TX Battery

  • Grade 32 contains 5% aluminium, 1% tin, 1% zirconium, 1% vanadium, and 0.8% molybdenum.
  • Grades 33 and 34 contain 0.4% nickel, 0.015% palladium, 0.025% ruthenium, and 0.15% chromium .[citation needed]
  • Grade 35 contains 4.5% aluminium, 2% molybdenum, 1.6% vanadium, 0.5% iron, and 0.3% silicon.
  • Grade 36 contains 45% niobium.

HP Pavilion DV4-1158TX Battery

  • Grade 37 contains 1.5% aluminium.
  • Grade 38 contains 4% aluminium, 2.5% vanadium, and 1.5% iron. This grade was developed in the 1990s for use as an armor plating. The iron reduces the amount of Vanadium needed as a beta stabilizer. Its mechanical properties are very similar to Grade 5, but has good cold workability similar to grade 9.HP Pavilion DV4-1159TX Battery

The Titanium Man ("Chelovek-Titan") is the name of two or more fictional characters, supervillains in the Marvel Comicsuniverse. The original Titanium Man first appeared in Tales of Suspense #69 (September 1965). He was created by Stan Leeand Don Heck.HP Pavilion DV4-1160ES Battery

Boris Bullski was born in Makeyevka, Ukrainian SSR, Soviet Union. According to the Black Widow, he was a KGB-member when he was a young man, and she was his combat instructor for a time. An ambitious official of the Communist Party of the Soviet Union, Boris Bullski was demoted after displeasing his superiors.HP Pavilion DV4-1160TX Battery

While working as an administrator of a Siberian labor camp, he commissioned the imprisoned scientists at the camp to build a suit of armor using the lab of Anton Vanko, the creator of the original Crimson Dynamo armor. Seeking to win back the Party's favor, Bullski conceived the idea of winning a propaganda victory against the West by defeating the Americansuperhero Iron Man.HP Pavilion DV4-1161TX Battery

He assigned the scientists to create a powerful suit of titanium armor based on the Iron Man technology, though the inferior resources available to the scientists meant that the armor was twice the size of Iron Man's. Bullski received permission to issue his challenge and Iron Man accepted, defeating Titanium Man in a battle before a worldwide television audience.HP Pavilion DV4-1162TX Battery

Undaunted, Bullski prepared for a rematch by having the suit redesigned and undergoing medical treatments that increased both his size and strength. Traveling to the United States, Bullski fought Iron Man in the skies above Washington, D.C.but was defeated. Withdrawing for retrieval by a Soviet submarine, he discovered that he had been abandoned on orders fromMoscow.HP Pavilion DV4-1163TX Battery

After working for the Vietnamese Communist scientist Half-Face (who increased his power yet again) for a while, he returned to the service of the Government of the Soviet Union, and was dispatched to the United States to retrieve the third Crimson Dynamo.HP Pavilion DV4-1164TX Battery

Finding the Dynamo at Cord Industries, a three-way battle between Titanium Man, Crimson Dynamo, and Iron Man began, during which Titanium Man killed Janice Cord with an electronic beam. Enraged, Iron Man soundly defeated Titanium Man, and left him in the murky depths of the Hudson River.HP Pavilion DV4-1165TX Battery

After the defeat, the two disgraced Soviet agents fled to Communist-controlled Vietnam, where they joined with Radioactive Man to form the Titanic Three. Though Bullski enjoyed working as a sanctioned agent once again, he longed to return to the Soviet Union, and devised a new plan to win his superiors' favor.HP Pavilion DV4-1166CA Battery

Adopting the alias of "The Other", he dispatched another former Soviet agent, the Unicorn, to destroy Iron Man. When the Unicorn failed, the Titanium Man went to destroy Iron Man himself, only to fail once more.

Despite his failures, Bullski was in favor with the Soviet government once more, and returned to the United States on a mission for the KGB.HP Pavilion DV4-1166TX Battery

By threatening the parents of a Soviet defector named Sergei, he forced the man to design technologically advanced armored suits that could be transformed into small card-like objects. Posing as "the Commander", Bullski used the suits to equip members of the Green Liberation Front (G.L.F.), an organization of disaffected Vietnam War veterans who felt ignored by their country.HP Pavilion DV4-1167TX Battery

With the suits, the G.L.F. robbed a New York City bank and the Federal Reserve Bank of New York;[1] though the members believed that they were simply acting as thieves, Bullski used the robberies as a cover for implanting a computer virus that would destroy American financial records, causing chaos in the economy of the United States.HP Pavilion DV4-1168TX Battery

Beta Ray Bill and Sif opposed the G.L.F. and the Commander, but when Sergei discovered that his parents were dead he exposed Bullski's true identity and the angry members of the G.L.F. turned on the Titanium Man. Teleporting away, he rematerialized in card form, which Sergei then simply tore and threw away.HP Pavilion DV4-1169TX Battery

Some time later, the new Crimson Dynamo was sent to the United States by the Soviet government to retrieve the remnants for reintegration.[3] The G.L.F. discovered the Crimson Dynamo's mission and attacked him, forcing him to seek assistance by reactivating the Titanium Man, who due to the incomplete nature of his reassembly was still missing body parts.HP Pavilion DV4-1180BR Battery

Enraged, Bullski slaughtered the members of the G.L.F., and was only stopped when the Dynamo lured him over the Atlantic Ocean and returned him to card form.[3] Bullski was later restored and continued to serve as Titanium Man, as a member of the Soviet Super-Soldiers[3] and later Remont-4, but felt increasingly despondent as the Soviet Union declined.HP Pavilion DV4-1190BR Battery

After an attack on a Stark Enterprises factory in Russia he was believed killed while battling Tony Stark, who was wearing Crimson Dynamo armor that was being controlled by Colonel General Valentin Shatalov, a former friend of Bullski.HP Pavilion DV4-1190EA Battery

Titanium Man II

The second Titanium Man was Kondrati Topolov, the mutant formerly known as Gremlin,[4] and served with the Soviet-era superhero group, the Soviet Super-Soldiers. The Gremlin was killed in combat with Iron Man during the first "Armor Wars" when the titanium in the suit exceeded its combustible temperature.HP Pavilion DV4-1190EJ Battery

Titanium Man III

The third Titanium Man's identity is the subject of some controversy. The first time this figure manifested itself, he attacked Stark Enterprises and Iron Man directly, apparently under orders of Stark-Fujikawa (possibly as a mercenary).HP Pavilion DV4-1190EL Battery

While he was shown to cherish Soviet paraphernalia and newspaper clippings featuring Boris Bullski, his identity was not firmly established.

Some time later, during a space mission to destroy an enormous asteroid that threatened to impact on Earth, a Titanium Man,HP Pavilion DV4-1198ER Battery

claiming to be this same person, stated his name was Andy Stockwell, and had never had a connection with the USSR. However, moments later it was revealed he was actually a member of "The Hammer", an international network of communist sleeper cells who wanted to destroy the United States.HP Pavilion DV4-1199EA Battery

He was lost in space, but being relatively close to Earth, may have returned under his own power.

In any case, a Titanium Man was contacted and hired, ostensibly through the Hammer again, to do a mercenary job for, of all people, Tony Stark in his effort to stop the superhuman registration bill.HP Pavilion DV4-1199EE Battery

It has been strongly suggested (outside of comics´ pages) that the third Titanium Man was indeed Boris Bullski, but against this speaks his apparent willingness to work for Tony Stark—under any set of circumstances—rather than kill him. His face was revealed to look nothing like Bullski's, and it is possible that there are multiple Titanium Men, or at least several people filling the role in turn.HP Pavilion DV4-1199EF Battery

Recently, the Titanium Man reappeared, this time in Russia, as a member of the rogue Soviet super-rebel group called Remont Six. He was knocked out by Darkstar, but was apparently not captured.

In the same period, another Titanium Man was seen being beaten down by Noh-Varr. The identity of this Titanium Man or the circumstances of the battle remain undisclosed.HP Pavilion DV4-1199EO Battery

Powers and abilities

The Titanium Men used green armor similar to that used by Iron Man and to that used by the Crimson Dynamo (their sometime compatriot). Neither suit of armor was as sophisticated as that used by Tony Stark as Iron Man, but some of its weapons were deceptively powerful,HP Pavilion DV4-1199EP Battery

and the first Titanium Man's physical strength seems to have been greater than that of Iron Man. He also boasted that his armor was made to last, not, like American technology, "with planned obsolescence" (although he had actually received several significant upgrades himself).HP Pavilion DV4-1199ER Battery

The suit of armor increases the wearer's physical strength to superhuman levels, and is in fact stronger than Iron Man. It was also able to fly at supersonic speeds (it can even reach escape velocity), shoot concussive force blasts from the hands, project constrictive force "rings", fire an electromagnetically paralytic beam from the helmet, and was resistant to conventional artillery.HP Pavilion DV4-1199ES Battery

Boris Bullski, the original Titanium Man, also possessed enhanced strength due to treatments given to him by the Soviet government to augment his physiology, making him grow into an 11-foot-tall giant. The Gremlin, being a dwarf who seldom exercised, was weaker than most people, but he possessed super-human intelligence, was capable of creating advanced devices and weapons, and was an accomplished genetic engineer.HP Pavilion DV4-1199ET Battery

Heroes Reborn — Iron Man

A Soviet Titanium Man, developed for the Russians by Victor von Doom, proved the better of the Iron Man prototype. Later, the same individual was shown, together with the Crimson Dynamo, as a free agent working for HYDRA.

This Titanium Man was physically similar to the original mainstream version.HP Pavilion DV4-1200 CTO Battery

Civil War: House of M

The second Titanium Man was seen as a member of the Soviet Super-Soldiers.

Ultimate Marvel

The Ultimate Marvel version of the Titanium Man is a shadowy figure featured in Ultimate Comics: Armor Wars. He is the one who hired a thief named "The Ghost" to steal a Stark Industries covert tech piece "Remnant 242".HP Pavilion DV4-1200 Battery

He sends his robots (the ARSENAL cyborgs) kidnapped Tony Stark and his cohort Justine Hammer to his base "Project Tomorrow", a former military area which specialized in Man/Machine fusion tech, were the Titanium Man is revealed to be Howard Stark Sr., the grandfather of Tony who was told he was dead in his grandson's youth.HP Pavilion DV4-1201AU Battery

The grandfather Stark's been trying to use his Grandson's armor tech to upgrade his rusted green, body armor to achieve immortality. Ghost give Stark Sr. "Remnant 242", where it's revealed to be an alternate version of Tony, found dead in a barren wasteland (Earth-242) during Tony's research with Reed Richards.HP Pavilion DV4-1201TU Battery

Tony explains that the head has advanced armor failsafes that kills technology, which sends out a massive pulse that kills Howard, Ghost, the ARSENAL drones, and unfortunately Justine.[9]

Television

  • Titanium Man appeared in the Iron Man animated series voiced by Gerard Maguire. In the series' first episode, he's shown as a powerful minion of the Mandarin and a creation of MODOK. Titanium Man does not make more appearances during the first season.HP Pavilion DV4-1202AU Battery
  • In one chapter of the second season, Titanium Man makes an alliance with Dark Aegis, but at the end he helps Iron Man and War Machine, sacrificing himself in order to stop Dark Aegis.
  • Titanium Man will appear in Iron Man: Armored Adventures. In this version, he is the armored identity of Justin Hammer (voiced by Michael Adamthwaite) who created the Titanium Man armor as part of Project Titanium.HP Pavilion DV4-1202TU Battery
  • In "Titanium vs. Iron," Justin Hammer dons the prototype Titanium Man armor (despite Mr. Fix's objection since the vibranium is needed to help perfect the armor) to ambush Iron Man in his stealth armor when Iron Man comes to delete the remaining data revolving around Project Titanium. HP Pavilion DV4-1202TX Battery
  • War Machine comes to Iron Man's aid only for Titanium Man to knock out War Machine. Titanium Man ends up chasing after Iron Man (who ends up carrying War Machine away) and ends up dropping War Machine. Iron Man has his armor do a proposal which spins Iron Man free and pick up War Machine.HP Pavilion DV4-1203AU Battery
  • When Titanium Man catches up, he destroys the stealth armor only to discover that Tony had bailed at the last minute. Titanium Man ends up chasing after Tony until War Machine wakes up. In the nick of time, Tony Stark's Mark II armor arrives and helps War Machine fight Titanium Man.HP Pavilion DV4-1203TU Battery
  • Iron Man was able to bind Titanium Man with his own weapon long enough for the duo to use a double blast from their repulsors to heat up the Titanium Man armor to its burning point. Upon returning to Hammer Multinational, Justin Hammer bails from the red-hot suit as Blizzard attempts to freeze it.HP Pavilion DV4-1203TX Battery
  • Unfortunately, the Titanium Man armor's burning point being so high that once Blizzard manages to cool it down, all that remains of the Titanium Man armor is a pile of molten slag. Despite destroying the armor, Tony believes that Titanium Man will return stronger than ever.HP Pavilion DV4-1204AU Battery
  • Later in "The Hawk and the Spider," Hammer uses the Titanium Man armor to steal the U.I chip of Obadiah Stane which was stolen from Iron Man by Hawkeye and Black Widow.
  • Titanium Man is in the Iron Man video game (based on the 2008 Iron Man film) voiced by Dimitri Diatchenko. In the game, the Titanium Man is Boris Bullski, and is an agent working for A.I.M.HP Pavilion DV4-1204TU Battery
  • His suit (presumably based on the designs of the original Iron Man armor that were supplied to A.I.M. by Obadiah Stane) has a limited onboard battery charged by high intensity radiation. He is first seen at the nuclear power plant, working alongside mercenaries to obtain a power source for A.I.M., when Iron Man arrives and stops him.HP Pavilion DV4-1204TX Battery
  • Later however, Titanium Man and A.I.M. soldiers later launch an attack on the Stark Industries compound to try to take Stark's Iron Man suit, but Iron Man defeats him and all of his A.I.M. forces. In the PSP version, The Titanium Man armor can also be unlocked as an alternate costume for Iron Man.HP Pavilion DV4-1205AU Battery
  • Although it is supposed to be Titanium Man, it looks little bit more like a Guardsman suit.
  • The third Titanium Man appears as a boss character in Marvel: Ultimate Alliance 2 voiced by Crispin Freeman. He orchestrates the terrorist attack on Washington, DC and has captured some Senators and taken them into the subway.HP Pavilion DV4-1205TU Battery
  • The heroes catch up with Titanium Man who escapes without the Senators. They catch up with Titanium Man at the Lincoln Memorial and defeat him. After being defeated, Titanium Man states that the heroes still lost.
  • Titanium Man, based on his animated appearance, was part of the Toy Biz Iron Man toyline.HP Pavilion DV4-1205TX Battery
  • Titanium Man, based on his design from the video game, is featured in the toyline for the Iron Man film.
  • Titanium Man was released in the Iron Man Face Off 4-pack from the Marvel Super Hero Squad line, packaged with figures of Iron Man, War Machine, and Crimson Dynamo.HP Pavilion DV4-1206TU Battery
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Thorium is nearly half as dense as uranium and plutonium, but is harder than either of them. All actinides are radioactive,paramagnetic, and, with the exception of actinium, have several crystalline phases: plutonium has seven, and uranium, neptunium and californium three. HP Pavilion DV4-1230BR Battery

Crystal structures of protactinium, uranium, neptunium and plutonium do not have clear analogs among the lanthanide and are more similar to those of the 3d-transition metals.

All actinides are pyrophoric, especially when finely divided, that is, they spontaneously ignite upon reaction with air.HP Pavilion DV4-1230TX Battery

The melting point of actinides does not have a clear dependence on the number of f-electrons. The unusually low melting point of neptunium and plutonium (~640 °C) is explained by hybridization of 5f and 6dorbitals and the formation of directional bonds in these metals.HP Pavilion DV4-1231TX Battery

Chemical properties

Like the lanthanides, all actinides are highly reactive with halogens and chalcogens; however, actinides react more easily. Actinides, especially those with a small number of 5f-electrons, are prone to hybridization. This is explained by the similarity of the electron energies at the 5f, 7s and 6d shells. HP Pavilion DV4-1232TX Battery

Most actinides exhibit a larger variety of valence states, and the most stable are +6 for uranium, +5 for protactinium and neptunium, +4 for thorium and plutonium and +3 for actinium and other actinides.

Chemically, actinium is similar to lanthanum, which is explained by their similar ionic radii and electronic structure. HP Pavilion DV4-1233TX Battery

Like lanthanum, actinium has oxidation of +3, but it is less reactive and has more pronounced basic properties. Among other trivalent actinides Ac3+ is least acidic, i.e. has the weakest tendency to hydrolyze in aqueous solutions.

Thorium is rather active chemically. Owing to lack of electrons on 6d-and 4f-orbitals, the tetravalent thorium compounds are colorless. HP Pavilion DV4-1234TX Battery

At pH < 3, the solutions of thorium salts are dominated by the cations [Th(H2O)8]4+. The Th4+ ion is relatively large, and depending on the coordination number can have a radius between 0.95 and 1.14 Å. As a result, thorium salts have a weak tendency to a hydrolysis. HP Pavilion DV4-1235EE Battery

The distinctive ability of thorium salts is their high solubility, not only in water, but also in polar organic solvents.

Protactinium exhibits two valence states; the +5 is stable, and the +4 state easily oxidizes to protactinium(V). Thus tetravalent protactinium in solutions is obtained by the action of strong reducing agents in a hydrogen atmosphere. HP Pavilion DV4-1235EI Battery

Tetravalent protactinium is chemically similar to uranium(IV) and thorium(IV). Fluorides, phosphates, hypophosphate, iodate and phenylarsonates of protactinium(IV) are insoluble in water and dilute acids. Protactinium forms soluble carbonates. The hydrolytic properties of pentavalent protactinium are close to those of tantalum(V) and niobium(V). HP Pavilion DV4-1235TX Battery

The complex chemical behavior of protactinium is a consequence of the start of the filling of the 5f shell in this element.

Uranium has a valence from 3 to 6, the last being most stable. In the hexavalent state, uranium is very similar to the sixth group elements. Many compounds of uranium(IV) and uranium(VI) are nonstoichiometric, i.e. have variable composition. HP Pavilion DV4-1236TX Battery

For example, the actual chemical formula of uranium dioxide is UO2+x, where xvaries between ?0.4 and 0.32. Uranium(VI) compounds are weak oxidants. Most of them contain the linear "uranyl" group, UO22+. Between 4 to 6 ligands can be accommodated in an equatorial plane perpendicular to the uranyl group. HP Pavilion DV4-1237TX Battery

The uranyl group acts as a hard acid and forms stronger complexes with oxygen-donor ligands than with nitrogen-donor ligands. NpO22+ and PuO22+ are also the common form of Np and Pu in the +6 oxidation state. Uranium(IV) compounds exhibit reducing properties, e.g., they are easily oxidized by atmospheric oxygen. HP Pavilion DV4-1238TX Battery

Uranium(III) is a very strong reducing agent. Owing to the presence of d-shell, uranium (as well as many other actinides) forms organometallic compounds, such as UIII(C5H5)3 and UIV(C5H5)4.

Neptunium has valence states from 3 to 7, which can be simultaneously observed in solutions. HP Pavilion DV4-1239TX Battery

The most stable state in solution is +5, but the valence +4 is preferred in solid neptunium compounds. Neptunium metal is very reactive. Ions of neptunium are prone to hydrolysis and formation of coordination compounds.

Plutonium also exhibits the valence between 3 and 7, and thus is chemically similar to neptunium and uranium.HP Pavilion DV4-1240TX Battery

It is highly reactive, and quickly forms an oxide film in air. Plutonium reacts with hydrogen even at temperatures as low as 25–50 °C; it also easily forms halides and intermetallic compounds. Hydrolysis reactions of plutonium ions of different oxidation states are quite diverse. Plutonium(V) can enter polymerization reactions.HP Pavilion DV4-1241TX Battery

The largest chemical diversity among actinides is observed in americium, which can have valence between 2 and 6. Divalent americium is obtained only in dry compounds and non-aqueous solutions (acetonitrile). Oxidation states +3, +5 and +6 are typical for aqueous solutions, but also in the solid state. HP Pavilion DV4-1242TX Battery

Tetravalent americium forms stable solid compounds (dioxide, fluoride and hydroxide) as well as complexes in aqueous solutions. It was reported that in alkaline solution americium can be oxidized to the heptavalent state, but these data proved erroneous. The most stable valence of americium is 3 in the aqueous solutions and 3 or 4 in solid compounds.HP Pavilion DV4-1243TX Battery

Valence 3 is dominant in all subsequent elements up to lawrencium (with the possible exception of nobelium). Curium can be tetravalent in solids (fluoride, dioxide). Berkelium, along with a valence of +3, also shows the valence of +4, more stable than that of curium; the valence 4 is observed in solid fluoride and dioxide.HP Pavilion DV4-1244TX Battery

The stability of Bk4+ in aqueous solution is close to that of Ce4+. Only valence 3 was observed for californium, einsteinium and fermium. The divalent state is proven for mendelevium and nobelium, and in nobelium it is more stable than the trivalent state. Lawrencium shows valence 3 both in solutions and solids.HP Pavilion DV4-1245BR Battery

The redox potential   increases from ?0.32 V in uranium, through 0.34 V (Np) and 1.04 V (Pu) to 1.34 V in americium revealing the increasing reduction ability of the An4+ ion from americium to uranium. All actinides form AnH3 hydrides of black color with salt-like properties.HP Pavilion DV4-1245TX Battery

Actinides also produce carbides with the general formula of AnC or AnC2 (U2C3 for uranium) as well as sulfides An2S3 and AnS2.

Some actinides can exists in various oxide forms: An2O3, AnO2, An2O5 and AnO3. For all actinides, oxides AnO3are amphoteric and An2O3, AnO2 and An2O5 are basic, they easily react with water, forming bases:HP Pavilion DV4-1246TX Battery

An2O3 + 3 H2O ? 2 An(OH)3.

These bases are poorly soluble in water and by their activity are close to the hydroxides of rare-earth metals. The strongest base is of actinium. All compounds of actinium are colorless, except for black actinium sulfide (Ac2S3).[84] Dioxides of tetravalent actinides crystallize in the cubic system, same as in calcium fluoride.HP Pavilion DV4-1247TX Battery

Thorium reacting with oxygen exclusively forms dioxide:

Thorium dioxide is a refractory material with the highest melting point among any known oxide (3390 °C). Adding 0.8–1% ThO2 to tungsten stabilizes its structure, so the doped filaments have better mechanical stability to vibrations. HP Pavilion DV4-1248TX Battery

To dissolve ThO2 in acids, it is heated to 500–600 °C; heating above 600 °C produces a very resistant to acids and other reagents form of ThO2. Small addition of fluoride ions catalyses dissolution of thorium dioxide in acids.

Two protactinium oxides were obtained: PaO2 (black) and Pa2O5(white); the former is isomorphic with ThO2 and the latter is easier to obtain. Both oxides are basic, and Pa(OH)5 is a weak, poorly soluble base.HP Pavilion DV4-1249TX Battery

Decomposition of certain salts of uranium, for example UO2(NO3)·6H2O in air at 400 °C, yields orange or yellow UO3.[93] This oxide is amphoteric and forms several hydroxides, the most stable being UO2(OH)2. Reaction of uranium(VI) oxide with hydrogen results in uranium dioxide, which is similar in its properties with ThO2. HP Pavilion DV4-1250TX Battery

This oxide is also basic and corresponds to the uranium hydroxide (U(OH)4).

Plutonium, neptunium and americium form two basic oxides: An2O3 and AnO2. Neptunium trioxide is unstable, thus only Np3O8could be obtained so far. However, the oxides of plutonium and neptunium with the chemical formula AnO2 and An2O3 are well characterized.HP Pavilion DV4-1251TX Battery

Actinides easily react with halogens forming salts with the formulas MX3 and MX4 (X = halogen). So the first berkelium compound, BkCl3, was synthesized in 1962 with an amount of 3 nanogram. Like the halogens of rare earth elements, actinide chlorides, bromides, and iodides are water soluble, and fluorides are insoluble.HP Pavilion DV4-1252TX Battery

Uranium easily yields a colorless hexafluoride, which sublimates at a temperature of 56.5 °C; because of its volatility, it is used in the separation of uranium isotopes with gas centrifuge or gaseous diffusion. Actinide hexafluorides have properties close to anhydrides. They are very sensitive to moisture and hydrolyze forming AnO2F2.HP Pavilion DV4-1253TX Battery

Pentachloride and black hexachloride of uranium were synthesized, but they are both unstable.

Action of acids on actinides yields salts, and if the acids are non-oxidizing then the actinide in the salt is in low-valence state:HP Pavilion DV4-1254TX Battery

U + 2 H2SO4 ? U (SO4)2 + 2 H2

2 Pu + 6 HCl ? 2 PuCl3 + 3 H2

However, in these reactions the regenerating hydrogen can react with the metal, forming the corresponding hydride. Uranium reacts with acids and water much easier than thorium.HP Pavilion DV4-1255TX Battery

Actinide salts can also be obtained by dissolving the corresponding hydroxides in acids. Nitrates, chlorides, sulfates and perchlorates of actinides are water soluble. When crystallizing from aqueous solutions, these salts forming a hydrates, such as Th(NO3)4·6H2O, Th(SO4)2·9H2O and Pu2(SO4)3·7H2O. Salts of high-valence actinides easily hydrolyze.HP Pavilion DV4-1256TX Battery
So, colorless sulfate, chloride, perchlorate and nitrate of thorium transform into basic salts with formulas Th(OH)2SO4 and Th(OH)3NO3. The solubility and insolubility of trivalent and tetravalent actinides is like that of lanthanide salts.HP Pavilion DV4-1257TX Battery

So phosphates, fluorides, oxalates, iodates and carbonatesof actinides are weakly soluble in water; they precipitate as hydrates, such as ThF4·3H2O and Th(CrO4)2·3H2O.

Actinides with oxidation state +6, except for the AnO22+-type cations, form [AnO4]2–, [An2O7]2– and other complex anions. HP Pavilion DV4-1258TX Battery

For example, uranium, neptunium and plutonium form salts of the Na2UO4 (uranate) and (NH4)2U2O7 (diuranate) types. In comparison with lanthanides, actinides easier form coordination compounds, and this ability increases with the actinide valence.HP Pavilion DV4-1259TX Battery

Trivalent actinides do not form fluoride coordination compounds, whereas tetravalent thorium forms K2ThF6, KThF5, and even K5ThF9 complexes. Thorium also forms the corresponding sulfates (for example Na2SO4·Th (SO4)2·5H2O), nitrates and thiocyanates. HP Pavilion DV4-1260TX Battery

Salts with the general formula An2Th(NO3)6·nH2O are of coordination nature, with the coordination number of thorium equal to 12. Even easier is to produce complex salts of pentavalent and hexavalent actinides. The most stable coordination compounds of actinides – tetravalent thorium and uranium – are obtained in reactions with diketones, e.g.acetylacetone.HP Pavilion DV4-1265DX Battery

Applications

While actinides have some established daily-life applications, such as in smoke detectors (americium) ]and gas mantles(thorium),[76] they are mostly used in nuclear weapons and use as a fuel in nuclear reactors.HP Pavilion DV4-1272CM Battery

The last two areas exploit the property of actinides to release enormous energy in nuclear reactions, which under certain conditions may become self-sustainingchain reaction.

The most important isotope for nuclear power applications is uranium-235. It is used in thethermal reactor, and its concentration in natural uranium does not exceed 0.72%. HP Pavilion DV4-1275MX Battery

This isotope strongly absorbs thermal neutrons releasing much energy. One fission act of 1 gram of 235U converts into about 1 MW·day. Of importance, is that 235U emits more neutrons than it absorbs;[101] upon reaching the critical mass, 235U enters into a self-sustaining chain reaction.HP Pavilion DV4-1280US Battery

Typically, uranium nucleus is divided into two fragments with the release of 2–3 neutrons, for example:

Other promising actinide isotopes for nuclear power are thorium-232 and its fission product, formed uranium-233.HP Pavilion DV4-1281US Battery

Emission of neutrons during the fission of uranium is important not only for maintaining the nuclear chain reaction, but also for the synthesis of the heavier actinides. Uranium-239 converts via ?-decay into plutonium-239, which, like uranium-235, is capable of spontaneous fission. HP Pavilion DV4-1282CM Battery

The world's first nuclear reactors were built not for energy, but for producing plutonium-239 for nuclear weapons.

About half of the produced thorium is used as the light-emitting material of gas mantles. Thorium is also added into multicomponent alloys of magnesium and zinc. HP Pavilion DV4-1283CL Battery

So the Mg-Th alloys are light and strong, but also have high melting point and ductility and thus are widely used in the aviation industry and in the production of missiles. Thorium also has good electron emissionproperties, with long lifetime and low potential barrier for the emission.HP Pavilion DV4-1287CL Battery

The relative content of thorium and uranium isotopes is widely used to estimate the age of various objects, including stars (see radiometric dating).

The major application of plutonium has been in nuclear weapons, where the isotope plutonium-239 was a key component due to its ease of fission and availability. HP Pavilion DV4-1290BR Battery

Plutonium-based designs allow reducing the critical mass to about a third of that for uranium-235. The "Fat Man"-type plutonium bombs produced during the Manhattan Project used explosive compression of plutonium to obtain significantly higher densities than normal, combined with a central neutron source to begin the reaction and increase efficiency. HP Pavilion DV4-1290EL Battery

Thus only 6.2 kg of plutonium was needed for anexplosive yield equivalent to 20 kilotons of TNT. (See also Nuclear weapon design.) Hypothetically, as little as 4 kg of plutonium—and maybe even less—could be used to make a single atomic bomb using very sophisticated assembly designs.HP Pavilion DV4-1292CM Battery

Plutonium-238 is potentially more efficient isotope for nuclear reactors, as it has smaller critical mass than uranium-235, but releases much more thermal energy (0.56 W/g). However, its application is limited by the high price (about 1000 USD/g). This isotope has been used in thermopiles and water distillationsystems of some space satellites and stations. HP Pavilion DV4-1299EE Battery

So Galileo and Apollo spacecrafts (e.g. Apollo 14 ) had heaters powered by kilogram quantities of plutonium-238 oxide; this heat is also transformed into electricity with thermopiles. The decay of plutonium-238 is produced relatively harmless alpha particles and is not accompanied by gamma-irradiation. HP Pavilion DV4-1300 CTO Battery

Therefore and this isotope (~160 mg) is used as the energy source in heart pacemakers where it lasts about 5 times longer than conventional batteries.

Actinium-227 is used as a neutron source. Its high specific energy (14.5 W/g) and the possibility of obtaining significant quantities of thermally stable compounds are attractive for use in long-lasting thermoelectric generators for remote use. HP Pavilion DV4-1301TU Battery

228Ac is used as an indicator of radioactivity in chemical research, as it emits high-energy electrons (2.18 MeV) that can be easily detected. 228Ac-228Ra mixtures are widely used as an intense gamma-source in industry and medicine.

Toxicity

Radioactive substances can harm human health via (i) local skin contamination, (ii) internal exposure due to ingestion of radioactive isotopes, and (iii) external overexposure by ?-activity and ?-radiation.HP Pavilion DV4-1301TX Battery

Together with radium and transuranium elements, actinium is one of the most dangerous radioactive poisons with high specific ?-activity. The most important feature of actinium is its ability to accumulate and remain in the surface layer of skeletons. At the initial stage of poisoning, actinium accumulates in the liver. HP Pavilion DV4-1302TU Battery

Another danger of actinium is that it undergoes radioactive decay faster than being excreted. Adsorptionfrom the digestive tract is much smaller (~0.05%) for actinium than radium.[

Protactinium in the body tends to accumulate in the kidneys and bones. The maximum safe dose of Pa in the human body is 0.03 µCithat corresponds to 0.5 micrograms of 231Pa. HP Pavilion DV4-1302TX Battery

This isotope, which might be present in the air as aerosol, is 2.5×108 times more toxic than hydrocyanic acid.[62]

Plutonium, when entering the body through air, food or blood (e.g. a wound), mostly settles in the lungs, liver and bones with only about 10% going to other organs, and remains there for decades.HP Pavilion DV4-1303TU Battery

The long residence time of plutonium in the body is partly explained by its poor solubility in water. Some isotopes of plutonium emit ionizing ?-radiation, which damages the surrounding cells. The median lethal dose (LD50) for 30 days in dogs after intravenous injection of plutonium is 0.32 milligram per kg of body mass, HP Pavilion DV4-1303TX Battery

and thus the lethal dose for humans is approximately 22 mg for a person weighing 70 kg; the amount for respiratory exposure should be approximately four times greater. Another estimate assumes that plutonium is 50 times less toxic than radium, and thus permissible content of plutonium in the body should be 5 µg or 0.3 µCi.HP Pavilion DV4-1304TU Battery

Such amount is nearly invisible in under microscope. After trials on animals, this maximum permissible dose was reduced to 0.65 µg or 0.04 µCi. Studies on animals also revealed that the most dangerous Pu exposure route is through inhalation, after which 5–25% of inhaled substances is retained in the body. HP Pavilion DV4-1304TX Battery

Depending on the particle size and solubility of the plutonium compounds, Pu is localized either in the lungs or in the lymphatic system, or is absorbed in the blood and then transported to the liver and bones. Contamination via food is the least likely way. In this case, only about 0.05% of soluble 0.01% insoluble compounds of plutonium absorbs into blood, and the rest is excreted. HP Pavilion DV4-1305TU Battery

Exposure of damaged skin to plutonium would retain nearly 100% of it.

The lanthanide or lanthanoid (IUPAC nomenclature) series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium.HP Pavilion DV4-1305TX Battery

These fifteen elements, along with chemically similar scandium andyttrium, are often collectively known as the rare earth elements.

The informal chemical symbol Ln is used in general discussions of lanthanide chemistry. All but one of the lanthanides are f-block elements, corresponding to the filling of the 4f electron shell; HP Pavilion DV4-1306TU Battery

lutetium, a d-block element, is also generally considered to be a lanthanide due to its chemical similarities with the other fourteen. All of the lanthanide elements form trivalent cations, Ln3+, whose chemistry is largely determined by the ionic radius, which decreases steadily from lanthanum to lutetium.HP Pavilion DV4-1306TX Battery

The lanthanide elements are the group of elements with atomic number increasing from 57 (lanthanum) to 71 (lutetium). They are termed lanthanide because the lighter elements in the series are chemically similar to lanthanum. Strictly speaking, both lanthanum and lutetium have been labeled as group 3 elements, because they both have a single valence electron in the d shell. HP Pavilion DV4-1307TU Battery

However, both elements are often included in any general discussion of the chemistry of the lanthanide elements.

In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each seriesHP Pavilion DV4-1307TX Battery

(either lanthanum or lutetium, and either actinium or lawrencium, respectively) shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; HP Pavilion DV4-1308TU Battery

a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).

Etymology

Together with scandium and yttrium, the trivial name "rare earths" is sometimes used to describe all the lanthanides. HP Pavilion DV4-1308TX Battery

This name arises from the minerals from which they were isolated, which were uncommon oxide-type minerals. However, the use of the name is deprecated by IUPAC, as the elements are neither rare in abundance nor "earths" (an obsolete term for water-insoluble strongly basic oxides of electropositive metals incapable of being smelted into metal using late 18th century technology).HP Pavilion DV4-1309TU Battery

Cerium is the 26th most abundant element in the Earth's crust, neodymium is more abundant than gold and even thulium (the least common naturally occurring lanthanide) is more abundant than iodine.HP Pavilion DV4-1309TX Battery

Despite their abundance, even the technical term "lanthanides" could be interpreted to reflect a sense of elusiveness on the part of these elements, as it comes from the Greek ????????? (lanthanein), "to lie hidden". However, if not referring to their natural abundance, but rather to their property of "hiding" behind each other in minerals, this interpretation is in fact appropriate. HP Pavilion DV4-1310TU Battery

The etymology of the term must be sought in the first discovery of lanthanum, at that time a so-called new rare earth element "lying hidden" in a cerium mineral, and it is an irony that lanthanum was later identified as the first in an entire series of chemically similar elements and could give name to the whole series. HP Pavilion DV4-1310TX Battery

The term lanthanide was probably introduced by Victor Goldschmidt in 1925.[7]

Chemical compounds

The electronic structure of the lanthanide elements, with minor exceptions is [Xe]6s24fn. In their compounds, the 6s electrons are lost and the ions have the configuration [Xe]4fm.HP Pavilion DV4-1311TU Battery

The chemistry of the lanthanides differs from main group elements and transition metals because of the nature of the 4f orbitals. These orbitals are "buried" inside the atom and are shielded from the atom's environment by the 4d and 5p electrons.HP Pavilion DV4-1311TX Battery

As a consequence of this, the chemistry of the elements is largely determined by their size, which decreases gradually from 102 pm (La3+) with increasing atomic number to 86 pm (Lu3+), the so-called lanthanide contraction. All the lanthanide elements exhibit the oxidation state +3.HP Pavilion DV4-1312TU Battery

In addition Ce3+ can lose its single f electron to form Ce4+with the stable electronic configuration of xenon. Also, Eu3+ can gain an electron to form Eu2+ with the f7configuration which has the extra stability of a half-filled shell. Promethium is effectively a man-made element as all its isotopes are radioactive with half-lives of less than 20 y.HP Pavilion DV4-1312TX Battery

In terms of reduction potentials, the Ln0/3+ couples are nearly the same for all lanthanides, ranging from -1.99 (for Eu) to -2.35 V (for Pr). Thus, these metals are highly reducing, with reducing power similar to alkaline earth metals such as Mg (-2.36 V).HP Pavilion DV4-1313DX Battery

Separation of lanthanides

The similarity in ionic radius between adjacent lanthanide elements makes it difficult to separate them from each other in naturally occurring ores and other mixtures. Historically, the very laborious processes of cascading and fractional crystallization was used.HP Pavilion DV4-1313TU Battery

Because the lanthanide ions have slightly different radii, the lattice energy of their salts and hydration energies of the ions will be slightly different, leading to a small difference in solubility. Salts of the formula Ln(NO3)3.2NH4NO3.4H2O can be used. Industrially, the elements are separated from each other by solvent extraction.HP Pavilion DV4-1313TX Battery

Typically an aqueous solution of nitrates is extracted into kerosene containing tri-n-butylphosphate, (BunO)3PO. The strength of the complexes formed increases as the ionic radius decreases, so solubility in the organic phase increases. Complete separation can be achieved continuously by use of countercurrent exchange methods.HP Pavilion DV4-1314TU Battery

The elements can also be separated by ion-exchange chromatography, making use of the fact that the stability constant for formation of EDTA complexes increases for log K ? 15.5 for [La(EDTA)]- to log K ? 19.8 for [Lu(EDTA)]-.

Ln(III) compounds

The trivalent lanthanides mostly form ionic salts. HP Pavilion DV4-1314TX Battery

The trivalent ions are hard acceptors and form more stable complexes with oxygen-donor ligands than with nitrogen-donor ligands. The larger ions are 9-coordinate in aqueous solution, [Ln(H2O)9]3+ but the smaller ions are 8-coordinate, [Ln(H2O)8]3+. There is some evidence that the later lanthanides have more water molecules in the second coordination sphere.HP Pavilion DV4-1315TU Battery

Complexation with monodentate ligands is generally weak because it is difficult to displace water molecules from the first coordination sphere. Stronger complexes are formed with chelating ligands because of the chelate effect, such as the tetra-anion derived from 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA).HP Pavilion DV4-1315TX Battery

Ln(II) and Ln(IV) compounds

The most common divalent derivatives of the lanthanides are for Eu(II), which achieves a favorable f7configuration. Divalent halide derivatives are known for all of the lanthanides. They are either conventional salts or are Ln(III) "electride"-like salts. HP Pavilion DV4-1316TU Battery

The simple salts include YbI2, EuI2, and SmI2. The electride-like salts, described as Ln2+, 2I-, e-, include NdI2, DyI2 and TmI2. Many of the iodides form soluble complexes with ethers, e.g. TmI2(dimethoxyethane)3.[11] Samarium(II) iodideis a useful reducing agent.HP Pavilion DV4-1316TX Battery

Ce(IV) in ceric ammonium nitrate is a useful oxidising agent. Otherwise tetravalent lanthanides are rare. The Ce(IV) is the exception owing to the tendency to form an unfilled f shell.

Organometallic compounds

Lanthanide-carbon ? bonds are well known but they exhibit carbanion-like behavior, unlike transition metal organometallic compounds.HP Pavilion DV4-1317TU Battery

Because of their large size, lanthanides tend to form more stable organometallic derivatives with bulky ligands to give compounds such as Ln[CH(SiMe3)3].[12] Similarly complexes ofcyclopentadienyl anion, e.g. [Ln(C5H5)3], are far less common than the corresponding pentamethylcyclopentadienyl, e.g. HP Pavilion DV4-1317TX Battery

Analogues of uranocene are derived from dilithiocyclooctatetraene, Li2C8H8. Organic lanthanide(II) compounds are also known, such as Cp*2Eu.

Magnetic and spectroscopic properties

All the trivalent lanthanide ions, except lutetium, have unpaired f electrons. However the magnetic moments deviate considerably from the spin-only values because of strong spin-orbit coupling. HP Pavilion DV4-1318TU Battery

The maximum number of unpaired electrons is 7, in Gd3+, with a magnetic moment of 7.94 B.M., but the largest magnetic moments, at 10.4-10.7 B.M., are exhibited by Dy3+ and Ho3+. However, in Gd3+ all the electrons have parallel spin and this property is important for the use of gadolinium complexes ascontrast reagent in MRI scans.HP Pavilion DV4-1318TX Battery

Crystal field splitting is rather small for the lanthanide ions and is less important than spin-orbit coupling in regard to energy levels.[13] Transitions of electrons between f orbitals are forbidden by the Laporte rule. Furthermore, because of the "buried" nature of the f orbitals, coupling with molecular vibrations is weak. HP Pavilion DV4-1319TU Battery

Consequently the spectra of lanthanide ions are rather weak and the absorption bands are similarly narrow. Glass containing holmium oxide and holmium oxide solutions (usually in perchloric acid) have sharp optical absorption peaks in the spectral range 200–900 nm and can be used as a wavelength calibration standard for optical spectrophotometers, and are available commercially.HP Pavilion DV4-1319TX Battery

As f-f transitions are Laporte-forbidden, once an electron has been excited, decay to the ground state will be slow. This makes them suitable for use in lasers as it makes the population inversion easy to achieve. The Nd:YAG laser is one that is widely used. Europium-doped yttrium vanadate was the first red phosphor to enable the development of colour television screens.HP Pavilion DV4-1320CA Battery

Lanthanide ions have notable luminescent properties due to their unique 4f orbitals. Laporte forbidden f-f transitions can be activated by excitation of a bound "antenna" ligand. This leads to sharp emission bands throughout the visible, NIR, and IR and relatively long luminescence lifetimes.HP Pavilion DV4-1320TX Battery

Geochemistry

The lanthanide contraction is responsible for the great geochemical divide that splits the lanthanides into light and heavy-lanthanide enriched minerals, the latter being almost inevitably associated with and dominated by yttrium. This divide is reflected in the first two "rare earths" that were discovered: yttria (1794) andceria (1803).HP Pavilion DV4-1321TX Battery

The geochemical divide has put more of the light lanthanides in the Earth's crust, but more of the heavy members in the Earth's mantle. The result is that although large rich ore-bodies are found that are enriched in the light lanthanides, correspondingly large ore-bodies for the heavy members are few. HP Pavilion DV4-1322TX Battery

The principal ores are monazite and bastnaesite. Monazite sands usually contain all the lanthanide elements, but the heavier elements are lacking in bastnaesite. The lanthanides obey the Oddo-Harkins rule - odd-numbered elements are less abundant than their even-numbered neighbours.HP Pavilion DV4-1322US Battery

Three of the lanthanide elements have radioactive isotopes with long half-lives (138La, 147Sm and 176Lu) that can be used to date minerals and rocks from Earth, the Moon and meteorites.

Biological effects

Compared to most other nondietary elements, non-radioactive lanthanides are classified as having low toxicity.HP Pavilion DV4-1323TX Battery

Technological applications

Lanthanide elements and their compounds have many uses but the quantities consumed are relatively small in comparison to other elements. About 15000 ton/year of the lanthanides are consumed as catalysts and in the production of glasses. HP Pavilion DV4-1324TX Battery

This 15000 tons corresponds to about 85% of the lanthanide production. From the perspective of value, however, applications in phosphors and magnets are more important.

Of the many technological devices, including superconductors, samarium-cobalt and neodymium-iron-boron high-flux rare-earth magnets, magnesium alloys, electronic polishers,HP Pavilion DV4-1325TX Battery

refining catalysts and hybrid car components (primarily batteries and magnets). Lanthanide ions are used as the active ions in luminescent materials used in optoelectronics applications, most notably the Nd:YAG laser. Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems.HP Pavilion DV4-1326TX Battery

Phosphors with lanthanide dopants are also widely used in cathode ray tube technology such as television sets. The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible. Yttrium iron garnet (YIG) spheres have been useful as tunable microwave resonators.HP Pavilion DV4-1327TX Battery

Lanthanide oxides are mixed with tungsten to improve their high temperature properties for welding, replacing thorium, which was mildly hazardous to work with. Many defense-related products also use lanthanide elements such as night vision goggles, rangefinders, the SPY-1 radar used in some Aegis equipped warships, and the propulsion system of Arleigh Burke-class destroyers all use rare earth elements in critical capacities. HP Pavilion DV4-1328TX Battery

Most lanthanides are widely used in lasers, and as (co-)dopants in doped-fiber optical amplifiers (e.g. Er-doped fiber amplfiers (EDFAs) which are used as repeaters in the terrestrial and submarine fiber-optic transmission links that carry internet traffic) . These elements deflect ultraviolet and infrared radiation and are commonly used in the production of sunglass lenses. HP Pavilion DV4-1329TX Battery

Other applications are summarized in the following table:

The complex [Gd(DOTA)]- is used in magnetic resonance imaging.

The lanthanide contraction is responsible for the great geochemical divide that splits the la

nthanides into light and heavy-lanthanide enriched minerals, the latter being almost inevitably associated with and dominated by yttrium.HP Pavilion DV4-1330TX Battery

This divide is reflected in the first two "rare earths" that were discovered: yttria (1794) andceria (1803). The geochemical divide has put more of the light lanthanides in the Earth's crust, but more of the heavy members in the Earth's mantle. The result is that although large rich ore-bodies are found that are enriched in the light lanthanides, HP Pavilion DV4-1331TX Battery

correspondingly large ore-bodies for the heavy members are few. The principal ores are monazite and bastnaesite. Monazite sands usually contain all the lanthanide elements, but the heavier elements are lacking in bastnaesite. The lanthanides obey the Oddo-Harkins rule - odd-numbered elements are less abundant than their even-numbered neighbours.HP Pavilion DV4-1332TX Battery

Three of the lanthanide elements have radioactive isotopes with long half-lives (138La, 147Sm and 176Lu) that can be used to date minerals and rocks from Earth, the Moon and meteorites.

Biological effects

Compared to most other nondietary elements, non-radioactive lanthanides are classified as having low toxicity.HP Pavilion DV4-1365DX Battery

Technological applications

Lanthanide elements and their compounds have many uses but the quantities consumed are relatively small in comparison to other elements. About 15000 ton/year of the lanthanides are consumed as catalysts and in the production of glasses.HP Pavilion DV4-1400 CTO Battery

This 15000 tons corresponds to about 85% of the lanthanide production. From the perspective of value, however, applications in phosphors and magnets are more important. HP Pavilion DV4-1404TX Battery

Of the many technological devices, including superconductors, samarium-cobalt and neodymium-iron-boron high-flux rare-earth magnets, magnesium alloys, electronic polishers, refining catalysts and hybrid car components (primarily batteries and magnets).HP Pavilion DV4-1405TX Battery

Lanthanide ions are used as the active ions in luminescent materials used in optoelectronics applications, most notably the Nd:YAG laser. Erbium-doped fiber amplifiers are significant devices in optical-fiber communication systems.Phosphors with lanthanide dopants are also widely used in cathode ray tube technology such as television sets. HP Pavilion DV4-1406TX Battery

The earliest color television CRTs had a poor-quality red; europium as a phosphor dopant made good red phosphors possible. Yttrium iron garnet (YIG) spheres have been useful as tunable microwave resonators. Lanthanide oxides are mixed with tungsten to improve their high temperature properties for welding, replacing thorium, which was mildly hazardous to work with.HP Pavilion DV4-1407TX Battery

Many defense-related products also use lanthanide elements such as night vision goggles, rangefinders, the SPY-1 radar used in some Aegis equipped warships, and the propulsion system of Arleigh Burke-class destroyers all use rare earth elements in critical capacities.HP Pavilion DV4-1408TX Battery

Most lanthanides are widely used in lasers, and as (co-)dopants in doped-fiber optical amplifiers (e.g. Er-doped fiber amplfiers (EDFAs) which are used as repeaters in the terrestrial and submarine fiber-optic transmission links that carry internet traffic) . These elements deflect ultraviolet and infrared radiation and are commonly used in the production of sunglass lensesHP Pavilion DV4-1409TX Battery

. Other applications are summarized in the following table:

The complex [Gd(DOTA)]- is used in magnetic resonance imaging.

Uranium in the environment refers to the science of the sources, environmental behaviour, and effects of uranium on humans and other animals. Uranium is weaklyradioactive and remains so because of its long physical half-life (4.468 billion years for uranium-238). HP Pavilion DV4-1413LA Battery

The biological half-life (the average time it takes for the human body to eliminate half the amount in the body) for uranium is about 15 days.[1] Normal functioning of the kidney, brain, liver, heart, and numerous other systems can be affected by uranium exposure, because uranium is a toxic metal.HP Pavilion DV4-1414LA Battery

The use of depleted uranium (DU) in munitions is controversial because of questions about potential long-term health effects.

Uranium is a naturally occurring element found in low levels within all rock, soil, and water. This is the highest-numbered element to be found naturally in significant quantities on earth.HP Pavilion DV4-1416LA Battery

According to the United Nations Scientific Committee on the Effects of Atomic Radiation the normal concentration of uranium in soil is 300 ?g/kg to 11.7 mg/kg.[5]

It is considered to be more plentiful than antimony, beryllium, cadmium, gold, mercury, silver, or tungsten and is about as abundant as tin, arsenic or molybdenum. HP Pavilion DV4-1425LA Battery

It is found in many minerals including uraninite (most common uranium ore), autunite,uranophane, torbernite, and coffinite. Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores (it is recovered commercially from these sources).HP Pavilion DV4T Battery

Seawater contains about 3.3 parts per billion of uranium by weight (3.3 µg/kg)[6][not in citation given] as uranium(VI) forms solublecarbonate complexes. The extraction of uranium from seawater has been considered as a means of obtaining the element.HP Pavilion DV4T-1000 CTO Battery

Uranium is weakly radioactive and remains so because of its long physical half-life (4.468 billion years for uranium-238). Thebiological half-life (the average time it takes for the human body to eliminate half the amount in the body) for uranium is about 15 days.HP Pavilion DV4T-1100 CTO Battery

During the extraction of uranium ore and its processing, some releases of uranium occur. The releases of radium and other decay products of uranium are normally more important than the uranium in tailings ponds at the mines and ore processing centers.HP Pavilion DV4T-1200 CTO Battery

Depleted uranium (DU) is useful because of its very high density of 19.1 g/cm3 (68.4% denser than lead). Civilian uses include counterweights in aircraft, radiation shielding in medical radiation therapy and industrial radiography equipment, and containers used to transport radioactive materials.HP Pavilion DV4T-1200SE CTO Battery

Military uses include defensive armor plating and armor-piercing projectiles.

Uranium metal can disperse into the air and water, United Nations Environment Programme (UNEP) study says in part:

"The most important concern is the potential for future groundwater contamination by corroding penetrators (ammunition tips made out of DU).HP Pavilion DV4T-1300 CTO Battery

The munition tips recovered by the UNEP team had already decreased in mass by 10-15% in this way. This rapid corrosion speed underlines the importance of monitoring the water quality at the DU sites on an annual basis."HP Pavilion DV4T-1300SE CTO Battery

Combustion

Studies of depleted uranium aerosol exposure suggest that uranium combustion product particles would quickly settle out of the air,[9] and thus could not affect populations more than a few kilometres from target areas. HP Pavilion DV4T-1400 CTO Battery

The U.S. has admitted that there have been over 100 "friendly fire" incidents in which members of the U.S. military have been struck by DU munitions, and that an unknown number have been exposed to DU via inhalation of combustion products from burning DU munitions.HP Pavilion DV4Z Battery

Corrosion

It has been reported that the corrosion of uranium in a silica rich aqueous solution forms both uranium dioxide and uranium trioxide.

In pure water, schoepite {(UO2)8O2(OH)12.12(H2O)} is formed in the first week and then after four months studtite {(UO2)O2·4(H2O)} was formed.HP Pavilion DV4Z-1000 CTO Battery

Uranium metal reacts with water to form hydrogen gas, this reaction forms uranium dioxide and 2% to 9% uranium hydride. It is important to note that the rate of corrosion due to water is far greater than that caused by oxygen at temperatures around 100 °C (212 °F). HP Pavilion DV4Z-1100 CTO Battery

At pH values below 2 the corrosion rate at 100 °C goes down greatly, while as pH values go from 7 upwards the corrosion rate declines. Gamma irradiation has little effect on the corrosion rate.

Oxygen gas inhibits the corrosion of uranium by water.HP Pavilion DV4Z-1200 CTO Battery

Nuclear waste

Spent uranium dioxide fuel is very insoluble in water, it is likely to release uranium (and fission products) even more slowly than borosilicate glass when in contact with water.HP Pavilion DV4 Battery

Note that while the vast majority of the uranium is removed by PUREX nuclear reprocessing, a small amount of uranium is left in the raffinate from the first cycle of the PUREX process. In addition because of the decay of the transplutonium minor actinides and the residual plutonium in the waste the concentration of uranium will increase on the waste.HP Pavilion DV4-1000 Battery

This will occur on a time scale of hundreds and thousands of years.

Health effects

Soluble uranium salts are toxic, though less so than those of other heavy metals such as lead or mercury.

HP Pavilion DV4-1000EA Battery

The organ which is most affected is the kidney. Soluble uranium salts are readily excreted in the urine, although some accumulation in the kidneys does occur in the case of chronic exposure. The World Health Organization has established a daily "tolerated intake" of soluble uranium salts for the general public of 0.5 ?g/kg body weight (or 35 ?g for a 70 kg adult): exposure at this level is not thought to lead to any significant kidney damage.

HP Pavilion DV4-1000ET Battery

The antidote for uranium in humans is bicarbonate, this is used because uranium (VI) forms complexes with carbonate. An alternative is to use tiron (sodium 4,5-dihydroxybenzene-1,3-disulfonate).

The use of depleted uranium (DU) in munitions is controversial because of questions about potential long-term health effects.

HP Pavilion DV4-1001 Battery

Normal functioning of the kidney, brain, liver, heart, and numerous other systems can be affected by uranium exposure, because uranium is a toxic metal.[2] The aerosol produced during impact and combustion of depleted uranium munitions can potentially contaminate wide areas around the impact sites leading to possible inhalation by human beings.HP Pavilion DV4-1001AX Battery

During a three week period of conflict in 2003 in Iraq, 1,000 to 2,000 tonnes of DU munitions were used.

The actual acute and chronic toxicity of DU is also a point of medical controversy. Multiple studies using cultured cells and laboratory rodents suggest the possibility of leukemogenic, genetic, reproductive, and neurological effects from chronic exposure.HP Pavilion DV4-1001TU Battery

A 2005 epidemiology review concluded: "In aggregate the human epidemiological evidence is consistent with increased risk of birth defects in offspring of persons exposed to DU." The World Health Organization, the directing and coordinating authority for health within the United Nations which is responsible for setting health research norms and standards, providing technical support to countries and monitoring and assessing health trends,[

HP Pavilion DV4-1001TX Battery

states that no risk of reproductive, developmental, or carcinogenic effects have been reported in humans due to DU exposure.[22]This report has been criticized by Dr. Keith Baverstock for not including possible long term effects of DU on human body.HP Pavilion DV4-1002 Battery

Birth defects

Most scientific studies have found no link between uranium and birth defects, but some claim statistical correlations between soldiers exposed to DU, and those who were not, concerning reproductive abnormalities.

One study concluded that epidemiological evidence is consistent with an increased risk of birth defects in the offspring of persons exposed to DU.HP Pavilion DV4-1002AX Battery

Environmental groups and others have expressed concern about the health effects of depleted uranium, and there is some debate over the matter. Some people have raised concerns about the use of this material, particularly in munitions, because of its mutagenicity, teratogenicity in mice, and neurotoxicity,  and its suspected carcinogenic potential. HP Pavilion DV4-1002TU Battery

Additional concerns address unexploded DU munitions leeching into groundwater over time.

Several sources have attributed the increase in the rate of birth defects in the children of Gulf War veterans and in Iraqis to depleted uranium inhalation exposure, HP Pavilion DV4-1002TX Battery

A 2001 study of 15,000 February 1991 U.S. Gulf War combat veterans and 15,000 control veterans found that the Gulf War veterans were 1.8 (fathers) to 2.8 (mothers) times more likely to have children with birth defects. In a study of UK troops, "Overall, the risk of any malformation among pregnancies reported by men was 50% higher in Gulf War Veterans (GWV) compared with Non-GWVs". HP Pavilion DV4-1003AX Battery

The conclusion of the study stated "We found no evidence for a link between paternal deployment to the Gulf war and increased risk of stillbirth, chromosomal malformations, or congenital syndromes. Associations were found between fathers' service in the Gulf war and increased risk of miscarriage and less well-defined malformationsHP Pavilion DV4-1003TU Battery

, but these findings need to be interpreted with caution as such outcomes are susceptible to recall bias. The finding of a possible relationship with renal anomalies requires further investigation. There was no evidence of an association between risk of miscarriage and mothers' service in the gulf."HP Pavilion DV4-1003TX Battery

Animals

It has been reported that uranium has caused reproductive defects, and other health problems in rodents, frogs and other animals. Uranium was shown to have cytotoxic, genotoxic and carcinogenic effects in animal studies.It has been shown in rodents and frogs that water soluble forms of uranium areteratogenic.HP Pavilion DV4-1004AX Battery

Bacterial biochemistry

It has been shown that bacteria can reduce and fix uranium in soils.[ These bacterium change soluble U(VI) into the highly insoluble complex forming U(IV) ion, hence stopping chemical leaching.HP Pavilion DV4-1004TU Battery

Behaviour in soil

It has been suggested that it is possible to form a reactive barrier by adding something to the soil which will cause the uranium to become fixed. One method of doing this is to use a mineral (apatite)  while a second method is to add a food substance such as acetate to the soil.HP Pavilion DV4-1004TX Battery

This will enable bacteria to reduce the uranium (VI) to uranium (IV) which is much less soluble. In peat-like soils the uranium will tend to bind to the humic acids, this tends to fix the uranium in the soil.HP Pavilion DV4-1005TX Battery,HP Pavilion DV4-1006TX Battery,HP Pavilion DV4-1007TX Battery,HP Pavilion DV4-1008TX Battery,HP Pavilion DV4-1009TX Battery,HP Pavilion DV4-1010TX Battery,HP Pavilion DV4-1011TX Battery

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The actinide or actinoid (IUPAC nomenclature) series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

The actinide series derives its name from the group 3 element actinium.HP Pavilion DV4-1199EA Battery

All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence.HP Pavilion DV4-1199EE Battery

Of the actinides, thorium and uranium occur naturally in substantial, primordial, quantities and small amounts of persisting natural plutonium have also been identified. The radioactive decay of uranium produces transient amounts of protactinium, and atoms of neptunium are occasionally produced from transmutation reactions in uranium ores.HP Pavilion DV4-1199EF Battery

The other actinides are purelysynthetic elements. Nuclear weapons tests have released at least six of these synthetic actinides into the environment; analysis of debris from a 1952 hydrogen bomb explosion showed the presence of americium, curium, berkelium, californium,einsteinium and fermium.HP Pavilion DV4-1199EO Battery

All actinides are radioactive and release energy upon radioactive decay; naturally occurring uranium and thorium, and synthetically produced plutonium are the most abundant actinides on Earth. These are used in nuclear reactors and nuclear weapons. Uranium and thorium also have diverse current or historical uses, and americium is used in the ionization chambers of most modernsmoke detectors.HP Pavilion DV4-1199EP Battery

In presentations of the periodic table, the lanthanides and the actinides are customarily shown as two additional rows below the main body of the table, with placeholders or else a selected single element of each series (either lanthanum or lutetium, and either actinium or lawrencium, respectively) HP Pavilion DV4-1199ER Battery

shown in a single cell of the main table, between barium and hafnium, and radium and rutherfordium, respectively. This convention is entirely a matter of aesthetics and formatting practicality; a rarely used wide-formatted periodic table inserts the lanthanide and actinide series in their proper places, as parts of the table's sixth and seventh rows (periods).HP Pavilion DV4-1199ES Battery

Discovery, isolation and synthesis

Like the lanthanides, the actinides form a family of elements with similar properties. Within the actinides, there are two overlapping groups: transuranium elements, which follow uranium in the periodic table—and transplutonium elements, which follow plutonium.HP Pavilion DV4-1199ET Battery

Compared to the lanthanides, which (except for promethium) are found in nature in appreciable quantities, most actinides are rare. The most abundant, or easy to synthesize actinides are uranium and thorium, followed by plutonium, americium, actinium, protactinium and neptunium.HP Pavilion DV4-1200 CTO Battery

The existence of transuranium elements was suggested by Enrico Fermi based on his experiments in 1934. However, even though four actinides were known by that time, it was not yet understood that they formed a family similar to lanthanides. HP Pavilion DV4-1200 Battery

The prevailing view that dominated early research into transuranics was that they were regular elements in the 7th period, with thorium, protactinium and uranium corresponding to 6th-period hafnium, tantalum and tungsten, respectively. Synthesis of transuranics gradually undermined this point of view. HP Pavilion DV4-1201AU Battery

By 1944 an observation that curium failed to exhibit oxidation states above 4 (whereas its supposed 6th period neighbor, platinum, can reach oxidation state of 7) prompted Glenn Seaborg to formulate a so-called "actinide hypothesis". Studies of known actinides and discoveries of further transuranic elements provided more data in support of this point of view,HP Pavilion DV4-1201TU Battery

but the phrase "actinide hypothesis" (the implication being that "hypothesis" is something that's not been decisively proven) remained in active use by scientists through the late 1950s.

At present, there are two major methods of producing isotopes of transplutonium elements: irradiation of the lighter elements with either neutrons or accelerated charged particles. HP Pavilion DV4-1201TX Battery

The first method is most important for applications, as only neutron irradiation using nuclear reactors allows the production of sizeable amounts of synthetic actinides; however, it is limited to relatively light elements. The advantage of the second method is that elements heavier than plutonium, as well as neutron-deficient isotopes, can be obtained, which are not formed during neutron irradiation.HP Pavilion DV4-1202AU Battery

In 1962–1966, there were attempts in the United States to produce transplutonium isotopes using a series of six underground nuclear explosions. Small samples of rock were extracted from the blast area immediately after the test to study the explosion products, but no isotopes with mass number greater than 257 could be detected, HP Pavilion DV4-1202TU Battery

despite predictions that such isotopes would have relatively long half-lives of ?-decay. This inobservation was attributed to spontaneous fission owing to the large speed of the products and to other decay channels, such as neutron emission and nuclear fission.HP Pavilion DV4-1202TX Battery

From actinium to neptunium

Uranium and thorium were the first actinides discovered. Uranium was identified in 1789 by the German chemist Martin Heinrich Klaproth in pitchblende ore. He named it after the planet Uranus,[6] which had been discovered only eight years earlier. HP Pavilion DV4-1203AU Battery

Klaproth was able to precipitate a yellow compound (likely sodium diuranate) by dissolving pitchblende in nitric acid and neutralizing the solution with sodium hydroxide. He then reduced the obtained yellow powder with charcoal, and extracted a black substance that he mistook for metal.HP Pavilion DV4-1203TU Battery

Only 60 years later, the French scientist Eugène-Melchior Péligot identified it with uranium oxide. He also isolated the first sample of uranium metal by heating uranium tetrachloride with potassium. The atomic mass of uranium was then calculated as 120, but Dmitri Mendeleev in 1872 corrected it to 240 using his periodicity laws. HP Pavilion DV4-1203TX Battery

This value was confirmed experimentally in 1882 by K. Zimmerman.

Thorium oxide was discovered by Friedrich Wöhler in the mineral, which was found in Norway (1827). Jöns Jacob Berzeliuscharacterized this material in more detail by in 1828. By reduction of thorium tetrachloride with potassium, he isolated the metal and named it thorium after the Norse god of thunder and lightning Thor.HP Pavilion DV4-1204AU Battery

The same isolation method was later used by Péligot for uranium.

Actinium was discovered in 1899 by André-Louis Debierne, an assistant of Marie Curie, in the pitchblende waste left after removal of radium and polonium. He described the substance (in 1899) as similar to titanium nd (in 1900) as similar to thorium.HP Pavilion DV4-1204TU Battery

The discovery of actinium by Debierne was however questioned in 1971 and 2000, arguing that Debierne's publications in 1904 contradicted his earlier work of 1899–1900. The name for word actinium comes from the Greek aktis, aktinos (?????, ???????), meaning beam or ray.HP Pavilion DV4-1204TX Battery

This metal was discovered not by its own radiation but by the radiation of the daughter products. Owing to the close similarity of actinium and lanthanum and low abundance, pure actinium could only be produced in 1950. The term actinide was probably introduced by Victor Goldschmidt in 1937.HP Pavilion DV4-1205AU Battery

Protactinium was possibly isolated in 1900 by William Crookes. It was first identified in 1913, when Kasimir Fajans and Oswald Helmuth Göhring encountered the short-lived isotope 234mPa (half-life 1.17 minutes) during their studies of the 238U decay. They named the new element brevium (from Latin brevis meaning brief);HP Pavilion DV4-1205TU Battery

the name was changed to protoactinium (from Greek ?????? + ????? meaning "first beam element") in 1918 when two groups of scientists, led by Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of Great Britain, independently discovered 231Pa. The name was shortened to Protactinium in 1949. HP Pavilion DV4-1205TX Battery

This element was little characterized until 1960, when A. G. Maddock and co-workers in UK produced 130 grams of protactinium from 60 tonnes of waste left after extraction of uranium from its ore.

Neptunium (named for the planet Neptune, the next planet out from Uranus, after which uranium was named) was discovered by Edwin McMillan and Philip H. Abelson in 1940 in Berkeley, California.HP Pavilion DV4-1206TU Battery

They produced the 239Np isotope (half-life 2.4 days) by bombarding uranium with slow neutrons.It was the first transuranium element produced synthetically.

Plutonium and above

Transuranium elements do not occur in sizeable quantities in nature and are commonly synthesized via nuclear reactions conducted with nuclear reactors.HP Pavilion DV4-1206TX Battery

For example, under irradiation with reactor neutrons, uranium-238 partially converts to plutonium-239:

In this way, Enrico Fermi with collaborators, using the first nuclear reactor Chicago Pile-1, obtained significant amounts of plutonium-239, which were then used in nuclear weapons.HP Pavilion DV4-1207TU Battery

Actinides with the highest mass numbers are synthesized by bombarding uranium, plutonium, curium and californium with ions of nitrogen, oxygen, carbon, neon or boron in a particle accelerator. So, nobelium was produced by bombarding uranium-238 with neon-22 as.HP Pavilion DV4-1207TX Battery

First isotopes of transplutonium elements, americium-241 and curium-242, were synthesized in 1944 by Glenn T. Seaborg, Ralph A. James and Albert Ghiorso.[39] Curium-242 was obtained by bombarding plutonium-239 with 32-MeV ?-particles

.The americium-241 and curium-242 isotopes also were produced by irradiating plutonium in a nuclear reactor.HP Pavilion DV4-1208TU Battery

The latter element was named after Marie Curie and her husband Pierre who are noted for discovering radium and for their work in radioactivity.

Bombarding curium-242 with ?-particles resulted in an isotope of californium 245Cf (1950), and a similar procedure yielded in 1949 berkelium-243 from americium-241.HP Pavilion DV4-1208TX Battery

The new elements were named after Berkeley, California, by analogy with its lanthanidehomologue terbium, which was named after the village of Ytterby in Sweden.

In 1945, B. B. Cunningham obtained the first bulk chemical compound of a transplutonium element, namely americium hydroxide.HP Pavilion DV4-1209TU Battery

Over the next three to four years, milligram quantities of americium and microgram amounts of curium were accumulated that allowed production of isotopes of berkelium (Thomson, 1949) and californium (Thomson, 1950). Sizeable amounts of these elements were produced only in 1958 (Burris B. Cunningham and Stanley G. Thomson), and the first californium compound (0.3 µg of CfOCl) was obtained only in 1960 by B. B. Cunningham and J. C. Wallmann).HP Pavilion DV4-1209TX Battery

Einsteinium and fermium were identified in 1952–1953 in the fallout from the "Ivy Mike" nuclear test (1 November 1952), the first successful test of a hydrogen bomb. Instantaneous exposure of uranium-238 to a large neutron flux resulting from the explosion produced heavy isotopes of uranium, including uranium-253 and uranium-255,HP Pavilion DV4-1210EA Battery

and their ?-decay yielded einsteinium-253 and fermium-255. The discovery of the new elements and the new data on neutron capture were initially kept secret on the orders of the U.S. military until 1955 due to Cold War tensions. Nevertheless, the Berkeley team were able to prepare einsteinium and fermium by civilian means, HP Pavilion DV4-1210EF Battery

through the neutron bombardment of plutonium-239, and published this work in 1954 with the disclaimer that it was not the first studies that had been carried out on the elements. The "Ivy Mike" studies were declassified and published in 1955.[51] The first significant (submicrograms) amounts of einsteinium were produced in 1961 by Cunningham and colleagues, but this has not been done for fermium yet.HP Pavilion DV4-1210EO Battery

The first isotope of mendelevium, 256Md (half-life 87 min), was synthesized by Albert Ghiorso, Glenn T. Seaborg, Gregory R. Choppin, Bernard G. Harvey and Stanley G. Thompson when they bombarded an 253Es target with alpha particles in the 60-inch cyclotron of Berkeley Radiation LaboratoryHP Pavilion DV4-1210ER Battery

; this was the first isotope of any element to be synthesized one atom at a time.[56]

There were several attempts to obtain isotopes of nobelium by Swedish (1957) and American (1958) groups, but the first reliable results was the synthesis of 256No by the Russian group (Georgy Flyorov et al.) in 1965, as acknowledges by the IUPAC in 1992. In their experiments, Flyorov et al. bombarded uranium-238 with neon-22.[8]HP Pavilion DV4-1210TU Battery

In 1961, Ghiorso et al. obtained the first isotope of lawrencium by irradiating californium (mostly californium-252) with boron-10 and boron-11 ions.[8] The mass number of this isotope was not clearly established (possibly 258 or 259) at the time. In 1965, 256Lr were synthesized by Flyorov et al. from 243Am and 18O.HP Pavilion DV4-1210TX Battery

Thus IUPAC recognized the nuclear physics teams at Dubna and Berkeley as the co-discoverers of lawrencium.

Thirty one isotopes of actinium and eight excited isomeric states of some of its nuclides were identified by 2010.HP Pavilion DV4-1211EA Battery

Three isotopes, 225Ac, 227Ac and 228Ac, were found in nature and the others were produced in the laboratory; only the three natural isotopes are used in applications. Actinium-225 is a member of radioactiveneptunium series;[61] it was first discovered in 1947 as a fission product of uranium-233, it is an ?-emitter with a half-life of 10 days. HP Pavilion DV4-1211TU Battery

Actinium-225 is less available than actinium-228, but is more promising in radiotracer applications.[29] Actinium-227 (half-life 21.77 years) occurs in all uranium ores, but in small quantities. One gram of uranium (in radioactive equilibrium) contains only 2×10?10 gram of 227Ac.HP Pavilion DV4-1211TX Battery

Actinium-228 is a member of radioactive thorium series formed by the decay of 228Ra;[61] it is a ?– emitter with a half-life of 6.15 hours. In one tonne of thorium there is 5×10?8 gram of 228Ac. It was discovered by Otto Hahn in 1906.[29]

Twenty nine isotopes of protactinium are known with mass numbers 212–240 as well as three excited isomeric states. HP Pavilion DV4-1212LA Battery

Only 231Pa and 234Pa have been found in nature. All the isotopes have short lifetime, except for protactinium-231 (half-life 32,760 years). The most important isotopes are 231Pa and 233Pa, which is an intermediate product in obtaining uranium-233 and is the most affordable among artificial isotopes of protactinium. HP Pavilion DV4-1212TU Battery

233Pa has convenient half-life and energy of ?-radiation, and thus was used in most studies of protactinium chemistry. Protactinium-233 is a ?-emitter with a half-life of 26.97 days.[57][62]

Uranium has the highest number (25) of both natural and synthetic isotopes. They have mass numbers of 217–242,[58] and three of them, 234U, 235U and 238U, are present in appreciable quantities in nature.HP Pavilion DV4-1212TX Battery

Among others, the most important is 233U, which is a final product of transformations of 232Th irradiated by slow neutrons. 233U has a very higher fission efficiency by low-energy (thermal) neutrons, compared e.g. with 235U. Most uranium chemistry studies were carried out on uranium-238 owing to its long half-life of 4.4×109 years.[HP Pavilion DV4-1213LA Battery

There are 19 isotopes of neptunium with mass numbers from 225 to 244;[58] they are all highly radioactive. The most popular among scientists are long-lived 237Np (t½ = 2.20×106 years) and short-lived 239Np, 238Np (t½ ~ 2 days).[37]

Sixteen isotopes of americium are known with mass numbers from 232 to 248.HP Pavilion DV4-1213TU Battery

The most important are 241Am and 243Am, which are alpha-emitters and also emit soft, but intense ?-rays; both of them can be obtained in an isotopically pure form. Chemical properties of americium were first studied with 241Am, but later shifted to243Am, which is almost 20 times less radioactive. HP Pavilion DV4-1213TX Battery

The disadvantage of 243Am is production of the short-lived daughter isotope 239Np, which has to be considered in the data analysis.[64]

Among 19 isotopes of curium,[58] the most accessible are 242Cm and 244Cm; they are ?-emitters, but with much shorter lifetime than the americium isotopes. HP Pavilion DV4-1214LA Battery

These isotopes emit almost no ?-radiation, but undergo spontaneous fission with the associated emission of neutrons. More long-lived isotopes of curium (245–248Cm, all ?-emitters) are formed as a mixture during neutron irradiation of plutonium or americium. Upon short irradiation, this mixture is dominated by curium-246, and then curium-248 begins to accumulate.HP Pavilion DV4-1214TU Battery

Both of these isotopes, especially 248Cm, have a longer half-life (3.48×105 years) and are much more convenient for carrying out chemical research than 242Cm and 244Cm, but they also have a rather high rate of spontaneous fission. 247Cm has the longest lifetime among isotopes of curium (1.56×107 years), but is not formed in large quantities because of the strong fission induced by thermal neutrons.HP Pavilion DV4-1214TX Battery

Fourteen isotopes of berkelium were identified with mass numbers 238–252.[58] Only 249Bk is available in large quantities; it has a relatively short half-life of 330 days and emits mostly soft ?-particles, which are inconvenient for detection. Its alpha radiation is rather weak (1.45×10?3% with respect to ?-radiation), but is sometimes used to detect this isotope. HP Pavilion DV4-1215EF Battery

247Bk is an alpha-emitter with a long half-life of 1,380 years, but it is hard to obtain in appreciable quantities; it is not formed upon neutron irradiation of plutonium because of the ?-stability of isotopes of curium isotopes with mass number below 248.[64]

Isotopes of californium with mass numbers 237–256 are formed in nuclear reactors;[58] californium-253 is a ?-emitter and the rest are ?-emitters. HP Pavilion DV4-1215TU Battery

The isotopes with even mass numbers (250Cf, 252Cf and 254Cf) have a high rate of spontaneous fission, especially 254Cf of which 99.7% decays by spontaneous fission. Californium-249 has a relatively long half-life (352 years), weak spontaneous fission and strong ?-emission that facilitates its identification. HP Pavilion DV4-1215TX Battery

249Cf is not formed in large quantities in a nuclear reactor because of the slow ?-decay of the parent isotope 249Bk and a large cross section of interaction with neutrons, but it can be accumulated in the isotopically pure form as the ?-decay product of (pre-selected) 249Bk. HP Pavilion DV4-1216TU Battery

Californium produced by reactor-irradiation of plutonium mostly consists of 250Cf and252Cf, the latter being predominant for large neutron fluences, and its study is hindered by the strong neutron radiation.

Among the 16 known isotopes of einsteinium with mass numbers from 241 to 257[58] the most affordable is 253Es.HP Pavilion DV4-1216TX Battery

It is an ?-emitter with a half-life of 20.47 days, a relatively weak ?-emission and small spontaneous fission rate as compared with the isotopes of californium. Prolonged neutron irradiation also produces a long-lived isotope 254Es (t½ = 275.5 days).[65]

Nineteen isotopes of fermium are known with mass numbers of 242–260. 254Fm, 255Fm and 256Fm are ?-emitters with a short half-life (hours), which can be isolated in significant amounts. HP Pavilion DV4-1217LA Battery

257Fm (t½ = 100 days) can accumulate upon prolonged and strong irradiation. All these isotopes are characterized by high rates of spontaneous fission.[65][67]

Among the 15 known isotopes of mendelevium (mass numbers from 245 to 260),[58] the most studied is 256Md, which mainly decays through the electron capture (?-radiation is ?10%) with the half-life of 77 minutes. HP Pavilion DV4-1217TX Battery

Another alpha emitter, 258Md, has a half-life of 53 days. Both these isotopes are produced from rare einsteinium (253Es and 255Es respectively), that limits their so their availability.[57]

Long-lived isotopes of nobelium and isotopes of lawrencium (and of heavier elements) have relatively small half-lives.HP Pavilion DV4-1218TX Battery

For nobelium 11 isotopes are known with mass numbers 250–260 and 262. Chemical properties of nobelium and lawrencium were studied with 255No (t½ = 3 min) and 256Lr (t½ = 35 s). The longest-lived nobelium isotope 259No has a half-life of 1.5 hours.HP Pavilion DV4-1219TX Battery

Distribution in nature

Thorium and uranium are the most abundant actinides in nature with the respective mass concentrations of 1.6×10?3% and 4×10?4%. Uranium mostly occurs in the Earth's crust as a mixture of its oxides in the minerals uraninite, which is also called pitchblende because of its black color. HP Pavilion DV4-1220BR Battery

There are several dozens of other uranium minerals such as carnotite (KUO2VO4·3H2O) and autunite (Ca(UO2)2(PO4)2·nH2O). The isotopic composition of natural uranium is 238U (relative abundance 99.2742%), 235U (0.7204%) and 234U (0.0054%); of these 238U has the largest half-life of 4.51×109 years.HP Pavilion DV4-1220TX Battery

The worldwide production of uranium in 2009 amounted to 50,572 tonnes, of which 27.3% was mined in Kazakhstan. Other important uranium mining countries are Canada (20.1%), Australia (15.7%), Namibia (9.1%), Russia (7.0%), andNiger (6.4%).

The most abundant thorium minerals are thorianite (ThO2), thorite(ThSiO4) and monazite, ((Th,Ca,Ce)PO4).HP Pavilion DV4-1220US Battery

Most thorium minerals contain uranium and vice versa; and they all have significant fraction of lanthanides. Rich deposits of thorium minerals are located in the United States (440,000 tonnes), Australia and India (~300,000 tonnes each) and Canada (~100,000 tonnes).[HP Pavilion DV4-1221TX Battery

The abundance of actinium in the Earth's crust is only about 5×10?15%.[62] Actinium is mostly present in uranium-containing, but also in other minerals, though in much smaller quantities. The content of actinium in most natural objects corresponds to the isotopic equilibrium of parent isotope 235U, and it is not affected by the weak Ac migration.[HP Pavilion DV4-1222LA Battery]

Protactinium is more abundant (10?12%) in the Earth's crust than actinium. It was discovered in the uranium ore in 1913 by Fajans and Göhring.[33] As actinium, the distribution of protactinium follows that of 235U.

The half-life of the longest-lived isotope of neptunium, 237Np, is negligible compared to the age of the Earth.HP Pavilion DV4-1222NR Battery

Thus neptunium is present in nature in negligible amounts produced as intermediate decay products of other isotopes.[37] Traces of plutonium in uranium minerals were first found in 1942, and the more systematic results on 239Pu are summarized in the table (no other plutonium isotopes could be detected in those samples). HP Pavilion DV4-1222TX Battery

The upper limit of abundance of the longest-living isotope of plutonium, 244Pu, is 3×10?20%. Plutonium could not be detected in samples of lunar soil. Owing to its scarcity in nature, most plutonium is produced synthetically.

Extraction

Owing to the low abundance of actinides, their extraction is a complex, multistep process.HP Pavilion DV4-1223LA Battery

Fluorides of actinides are usually used because they are insoluble in water and can be easily separated with redox reactions.

Among the actinides, thorium and uranium are the easiest to isolate. Thorium is extracted mostly from monazite: thorium diphosphate (Th(PO4)2) is reacted with nitric acid, and the produced thorium nitrate treated with tributyl phosphate.HP Pavilion DV4-1223TX Battery

Rare-earthimpurities are separated by increasing the pH in sulfate solution.

In another extraction method, monazite is decomposed with a 45% aqueous solution of sodium hydroxide at 140 °C. Mixed metal hydroxides are extracted first, filtered at 80 °C, washed with water and dissolved with concentrated hydrochloric acid.HP Pavilion DV4-1224LA Battery

Next, the acidic solution is neutralized with hydroxides to pH = 5.8 that results in precipitation of thorium hydroxide (Th(OH)4) contaminated with ~3% of rare-earth hydroxides; the rest of rare-earth hydroxides remains in solution. Thorium hydroxide is dissolved in an inorganic acid and then purified from the rare earth elements.HP Pavilion DV4-1224TX Battery

An efficient method is the dissolution of thorium hydroxide in nitric acid, because the resulting solution can be purified by extraction with organic solvents:

Th(OH)4 + 4 HNO3 ? Th(NO3)4 + 4 H2O

Metallic thorium is separated from the anhydrous oxide, chloride or fluoride by reacting it with calcium in an inert atmosphere:HP Pavilion DV4-1225DX Battery

ThO2 + 2 Ca ? 2 CaO + Th

Sometimes thorium is extracted by electrolysis of a fluoride in a mixture of sodium and potassium chloride at 700–800 °C in a graphite crucible. Highly pure thorium can be extracted from its iodide with the crystal bar process.

Uranium is extracted from its ores in various ways. In one method, the ore is burned and then reacted with nitric acid to convert uranium into a dissolved state. HP Pavilion DV4-1225EE Battery

Treating the solution with a solution of tributyl phosphate (TBP) in kerosene transforms uranium into an organic form UO2(NO3)2(TBP)2. The insoluble impurities are filtered and the uranium is extracted by reaction with hydroxides as (NH4)2U2O7 or with hydrogen peroxide as UO4·2H2O.HP Pavilion DV4-1225LA Battery

When the uranium ore is rich in such minerals as dolomite, magnesite, etc., those minerals consume much acid. In this case, the carbonate method is used for uranium extraction. Its main component is an aqueous solution of sodium carbonate, which converts uranium into a complex [UO2(CO3)3]4–, which is stable in aqueous solutions at low concentrations of hydroxide ions.HP Pavilion DV4-1225TX Battery

The advantages of the sodium carbonate method are that the chemicals have low corrosivity (compared to nitrates) and that most non-uranium metals precipitate from the solution. The disadvantage is that tetravalent uranium compounds precipitate as well. Therefore, the uranium ore is treated with sodium carbonate at elevated temperature and under oxygen pressure:HP Pavilion DV4-1226TX Battery

2 UO2 + O2 + 6 CO32– ? 2 [UO2(CO3)3]4–

This equation suggests that the best solvent for the uranium carbonate processing is a mixture of carbonate with bicarbonate. At high pH, this results in precipitation of diuranate, which is treated with hydrogen in the presence of nickel yielding an insoluble uranium tetracarbonate.HP Pavilion DV4-1227LA Battery

Another separation method uses polymeric resins as a polyelectrolyte. Ion exchange processes in the resins result in separation of uranium. Uranium from resins is washed with a solution ofammonium nitrate or nitric acid that yields uranyl nitrate, UO2(NO3)2·6H2O. When heated, it turns into UO3, which is converted to UO2 with hydrogen:HP Pavilion DV4-1227TX Battery

UO3 + H2 ? UO2 + H2O

Reacting uranium dioxide with fluoric acid changes it to uranium tetrafluoride, which yields uranium metal upon reaction with magnesium metal:[76]

4 HF + UO2 ? UF4 + 2 H2O

To extract plutonium, neutron-irradiated uranium is dissolved in nitric acid, and a reducing agent (FeSO4, or H2O2) is added to the resulting solution. HP Pavilion DV4-1227US Battery

This addition changes the oxidation state of plutonium from +6 to +4, while uranium remains in the form of uranyl nitrate (UO2(NO3)2). The solution is treated with a reducing agent and neutralized with ammonium carbonate to pH = 8 that results in precipitation of Pu4+ compounds.HP Pavilion DV4-1228CA Battery

In another method, Pu4+and UO22+ are first extracted with tributyl phosphate, then reacted with hydrazine washing out the recovered plutonium.[74]

The major difficulty in separation of actinium is the similarity of its properties with those of lanthanum. Thus actinium is either synthesized in nuclear reactions from isotopes of radium or separated using ion-exchange procedures.HP Pavilion DV4-1228LA Battery

Properties

Actinides have similar properties to lanthanides. The 6d and 7s electronic shells are completed in actinium and thorium, and the 5fshell is being filled with further increase in atomic number; the 4f shell is filled in the lanthanides. HP Pavilion DV4-1228TX Battery

The first experimental evidence for the filling of the 5f shell in actinides was obtained by McMillan and Abelson in 1940. As in lanthanides (see lanthanide contraction), the ionic radius of actinides monotonically decreases with atomic number (see also Aufbau principle).HP Pavilion DV4-1229LA Battery

Actinides are typical metals. All of them are soft and have a silvery color (but tarnish in air), relatively high density and plasticity. Some of them can be cut with a knife. Their electrical resistivity varies between 15 and 150 µOhm·cm. The hardness of thorium is similar to that of softsteel, so heated pure thorium can be rolled in sheets and pulled into wire. HP Pavilion DV4-1229TX Battery

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