COBALT ORE

Listing description:

Cobalt is a hard, lustrous, gray metal, a chemical element with symbol Co and atomic number 27. Cobalt-based colors and pigments have been used since ancient times for jewelry and paints, and miners have long used the name kobold ore for some minerals.

Detailed description:

Cobalt occurs in various metallic-lustered ores, for example cobaltite (CoAsS), but is mainly produced 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 mined worldwide.

Cobalt is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Smalte (cobalt silicate glass) and cobalt blue (cobalt(II) aluminate, CoAl₂O₄) gives a distinctive deep blue color to glass, ceramics, inks, paints, and varnishes. Cobalt-60 is a commercially important radioisotope, used as a tracer and in the production of gamma rays for industrial use.

Cobalt is an essential trace element for all animal organisms as the active center of coenzymes called cobalamins. These include vitamin B₁₂ which is essential for mammals. Cobalt is also an active nutrient for bacteria, algae, and fungi.

Characteristics

Electrolytically refined cobalt, 99.9 %, segment of a large plate.

Cobalt is a ferromagnetic metal with a specific gravity of 8.9 (20°C). 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. It has the atomic number 27. The Curie temperature is 1115 °C, and the magnetic moment is 1.6–1.7 Bohr magnetons per atom. In nature, it is frequently associated with nickel, and both are characteristic minor components of meteoric iron. Mammals require small amounts of cobalt which is the basis of vitamin B₁₂. Cobalt-60, an artificially produced radioactive isotope of cobalt, is an important radioactive tracer and cancer-treatment agent. Cobalt has a relative permeability two thirds that of iron. Metallic cobalt occurs as two crystallographic structures: hcp and fcc. The ideal transition temperature between hcp and fcc structures is 450 °C, but in practice, the energy difference is so small that random intergrowth of the two is common.

Creation

The stable form of cobalt is created in supernovas via the r-process

History

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 AD 79), and in China dating from the Tang dynasty (AD 618–907) and the Ming dynasty (AD 1368–1644). Cobalt glass ingots have been recovered from the Uluburun shipwreck, dating to the late 14th century BC.^[15]

Swedish chemist Georg Brandt (1694–1768) is credited with discovering cobalt circa 1735. He was able to show that cobalt was the source of the blue color in glass, which previously had been attributed to the bismuth found with cobalt. The word cobalt is derived from the German kobalt, from kobold meaning "goblin", a term used for the ore of cobalt by miners. The first attempts at smelting the cobalt ores to produce cobalt metal failed, yielding cobalt(II) oxide instead. Also, because the primary ores of cobalt

Occurrence

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. The mineral cattierite is similar to pyrite and occurs together vaesite in the copper deposits in the Katanga Province.^[1 Upon contact with the atmosphere weathering the sulfide minerals oxidatize to pink erythrite ('cobalt glance': Co₃(AsO₄)₂·8H₂O) and sphaerocobaltite (CoCO₃).

Production

Cobalt ore

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.

In 2005, the copper deposits in the Katanga Province (former Shaba province) of the Democratic Republic of the Congo was the top producer of cobalt with almost 40% world share, reports the British Geological Survey. The political situation in the Congo influences the price of cobalt significantly.

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. 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. 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.

Applications

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 gas turbines and jet aircraft engines, though nickel-based single crystal alloys surpass them in this regard. Cobalt-based alloys are also corrosion and wear-resistant. Special cobalt-chromium-molybdenum alloys are used for prosthetic parts such as hip and knee replacements. Cobalt alloys are also used for dental prosthetics, where they are useful to avoid allergies to nickel. 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.

Batteries

Lithium cobalt oxide (LiCoO₂) is widely used in lithium ion battery electrodes. Nickel-cadmium (NiCd) and nickel metal hydride (NiMH) batteries also contain significant amounts of cobalt.

Catalysis

Several cobalt compounds are used in chemical reactions as oxidation catalysts. 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.^[28] The same carboxylates are used to improve the adhesion of the steel to rubber in steel-belted radial tires.

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.^[28]

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. Smalt is produced by melting a mixture of the roasted mineral smaltite, quartz and potassium carbonate, yielding a dark blue silicate glass which is ground after the production.^[31] Smalt was widely used for the coloration of glass and as pigment for paintings.^[32] In 1780 Sven Rinman discovered cobalt green and in 1802 Louis Jacques Thénard discovered cobalt blue.^[33] The two colors cobalt blue, a cobalt aluminate, and cobalt green, a mixture of cobalt(II) oxide and zinc oxide, were used as pigments for paintings due to their superior stability.^[34][35]

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.^[36] 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). The location where the cobalt compounds were obtained is unknown.^[37][38]

Other uses

• Electroplating due to its appearance, hardness, and resistance to oxidation
• Ground coats for porcelain enamels

Biological role

Cobalt is essential to all animals, including humans. It is a key constituent of cobalamin, also known as vitamin B₁₂. A deficiency of cobalt leads to pernicious anemia, a lethal disorder. Pernicious anemia is very rare, though, because trace amounts of cobalt are available in most diets. The presence of 0.13 to 0.30 mg/kg of cobalt in soils markedly improves the health of grazing animals.^{[citation needed]}

The cobalamin-based proteins use corrin to hold the cobalt. Coenzyme B₁₂ features a reactive C-Co bond, which participates in its reactions.^[39] 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, 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 non-B₁₂. These proteins include methionine aminopeptidase 2 and nitrile hydratase.^[40]

Precautions

Main article: Cobalt poisoning

Cobalt is an essential element for life in minute amounts. The LD₅₀ values 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.

After nickel and chromium, cobalt is a major cause of contact dermatitis and is considered carcinogenic.

PRICE

$53.37/KG

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