Cob

Cobalt (Co) is a chemical element with the atomic number 27 in the Periodic Table. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal. 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 to be due to the known metal bismuth. Miners had long used the name kobold ore (German for goblin ore) for some of the blue-pigment-producing minerals; they were so named because they were poor in known metals, and gave poisonous arsenic-containing fumes when smelted. In 1735, such ores were found to be reducible to a new metal (the first discovered since ancient times), and this was ultimately named cobalt from the German term used by miners.

Properties and Uses

Cobalt is a ferromagnetic metal with a specific gravity of 8.9. The Curie temperature is 1,115 °C (2,039 °F) and the magnetic moment is 1.6–1.7 Bohr magnetons per atom. Cobalt has a relative permeability two-thirds that of iron. Metallic cobalt occurs as two crystallographic structures: hcp (hexagonal close-packed) and fcc (face-centered cubic). The transition temperature between the hcp and fcc structures is very high, and thus they are not easily induced.

Cobalt is used in the preparation of magnetic, wear-resistant, and high-strength alloys. Its compounds, cobalt silicate and cobalt(II) aluminate (CoAl_2O_4, cobalt blue), give a distinctive deep blue color to glass, ceramics, inks, paints, and varnishes. Cobalt is also used in the production of batteries, including lithium-ion and nickel-cadmium batteries, as well as in electroplating, and as catalysts for the petroleum and chemical industries.

Health and Environmental Effects

Cobalt is an essential element for life in minute amounts. The vitamin B12, a cobalt-containing compound, is essential for the production of red blood cells. However, at higher concentrations, cobalt can be hazardous to health, causing skin and lung effects in the short term and more serious health effects in the long term, such as heart problems and thyroid damage.

Environmental exposure to cobalt and its compounds can occur through the burning of fossil fuels, processing of cobalt-containing ores, and the use and disposal of cobalt-containing products. Cobalt can accumulate in aquatic ecosystems and soil, posing risks to humans, animals, and plants.

Production and Reserves

The majority of cobalt production is as a by-product of copper and nickel mining. The Democratic Republic of the Congo (DRC) is the largest producer of cobalt, accounting for more than half of the world's supply. Other significant producers include Russia, Australia, and Canada. Cobalt reserves are distributed globally, with the DRC, Australia, and Cuba having the largest identified reserves.

Recycling

Recycling of cobalt is becoming increasingly important due to the metal's use in rechargeable batteries and other technological applications. Cobalt can be recovered from spent batteries, catalysts, and alloy scraps. Recycling not only provides a secondary source of cobalt but also reduces environmental impact associated with cobalt mining and processing.

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