Cobalt, element symbol Co, atomic number 27, atomic weight 58.9332, closely packed hexagonal crystal, located in the 4th period and 8th group of the periodic table, with common valences of +2 and +3.
Cobalt is a shiny steel-gray metal, hard and brittle, and ferromagnetic. When heated to 1 150℃, the magnetism disappears. It does not react with water at room temperature, but oxidizes to generate CoO when heated to above 300℃ in air, and burns to generate Co3O4 when heated in white heat.
As for cobalt, China knew about it in the early days, and it was used in pottery glaze. The ancient Greeks and Romans used its compounds to make colored glass and produced beautiful dark blue. The blue color of China Tang Dynasty colored porcelain is also due to the existence of cobalt compounds.
Content distribution:
The average content of cobalt in the crust is 0.00 1% (mass), and the total amount of cobalt in the ocean is about 2.3 billion tons. There are nearly a hundred kinds of cobalt-containing minerals known in nature, but there is no single cobalt mineral, most of which are associated with sulfide deposits such as nickel, copper, iron, lead, zinc, silver and manganese, and the cobalt content is low.
The proven cobalt reserves in the world are 6.5438+0.48 million tons, while China has only 470,000 tons. It is distributed in 24 provinces (regions) such as Gansu, Qinghai, Shandong, Yunnan, Hubei, Qinghai, Hebei and Shanxi. The total reserves of these seven provinces account for 7 1% of the national total reserves, of which Gansu has the largest reserves, accounting for 28% of the national total.