The chemical element Cobalt has the atomic number 27 and the symbol Co. Other than minor amounts found in naturally occurring meteoric iron alloys, cobalt is only found in the Earth's crust in chemically mixed form like nickel. Reductive smelting creates a hard, shiny silver metal as the free element.
Cobalt-based blue pigments have been used since the dawn of time to impart a characteristic blue color to jewellery, paint, and glass, but for a very long time it was believed that the color came from the well-known metal bismuth. Some of the minerals that produce the blue pigments were known to miners as "kobold ore" (German for "goblin ore") because they were deficient in known metals and produced toxic vapors containing arsenic when smelted. In 1735, similar ores were found to be reducible to a new metal (the first metal discovered since antiquity), which was later named kobold.
Currently, certain amounts of cobalt are obtained from one of the few ores with metallic luster, particularly cobaltite (CoAsS). However, this element is mostly produced as a by-product of copper and nickel mining. Most of the world's cobalt production is produced at the Copperbelt in Zambia and the Democratic Republic of the Congo (DRC). Natural Resources Canada estimates that 2016 tons (116.000 long tons; 114.000 short tons) of cobalt were produced worldwide in 128.000, with more than 50% of this occurring in the Democratic Republic of the Congo alone.
Lithium-ion batteries and the creation of magnetic, wear-resistant and high-strength alloys are the two main applications for cobalt. Cobalt silicate and cobalt(II) aluminate (CoAl2O4, cobalt blue) materials impart a characteristic deep blue color to glass, ceramics, inks, paints and varnishes.
Cobalt has only one stable isotope in nature, cobalt-59.
Cobalt-60 is a commercially important radioisotope used as a radioactive tracer and for the production of high-energy gamma rays. The active center of a class of coenzymes known as cobalamins is cobalt. Vitamin B12, the best-known example of its kind, is essential for all animals. For bacteria, algae and fungi, cobalt in inorganic form serves as a micronutrient.
The specific gravity of the ferromagnetic metal cobalt is 8,9. 1.115 °C (2.039 °F) is the Curie temperature and the magnetic moment has 1,6-1,7 Bohr magnetons per atom. Iron has a relative permeability that is twice that of cobalt. Metallic cobalt has two crystallographic forms: hcp and fcc. The optimal temperature for the transition between the hcp and fcc structures is 450 °C (842 °F), but in reality the energy gap is so small that spontaneous intermingling of the two forms often occurs.
A passivating oxide coating protects the weakly reducing metal cobalt from oxidation. Both halogens and sulfur damage it. At 900 °C (1.650 °F), heated Co3O4 Oxygen is lost from the , producing CoO monoxide.
Metal, fluorine (F) at 520 K2), chlorine (Cl2), bromine (Br2) and iodine (I2) produces comparable binary halides. Even when heated, it reacts with boron, carbon, phosphorus, arsenic and sulfur, although hydrogen gas (H2) or nitrogen gas (N2) does not react with It interacts slowly with mineral acids at normal temperatures and extremely slowly with moist air, but not with dry air.
Source: Wikipedia
Günceleme: 08/03/2023 13:21