The use of cobalt and its pollution

　　cobaltIt is a transition metal element with an atomic number of 27 and magnetic properties. It is widely distributed, but the content in the earth's crust is very low, only 0.0023 percent.

The distribution of cobalt resources in the world is extremely uneven. Congo, Australia and Cuba together account for 70% of the world's total reserves, of which Congo has the largest reserves, accounting for 47.89%. China's cobalt reserves are 80,000 tons, accounting for only 1.13%, ranking No. 1 in the world 9.

As a scarce resource, cobalt is an important strategic material and plays an important role in various fields of the national economy and people's life (see the figure below). It is the most widely used and the closest to the public, and is currently the mainstream rechargeable battery : Lithium battery. The negative electrode material of lithium battery is lithium cobaltate, and cobalt is an indispensable raw material.

The second major use of cobalt is as an important alloying element in the composition of high-performance steel alloys such as superalloys, cemented carbides, high-speed tool steels, magnetic materials, and dental materials.

The contribution of cobalt to the alloy is mainly 3:

(1) Improve the heat resistance of the alloy;

(2) Improve strength and toughness;

(3) Improve red hardness (hard, high temperature resistance).

Typical example: AF1410 steel containing 14% cobalt has super strength and super toughness; Stellite alloy containing more than 50% cobalt will not lose its original hardness even when heated to 1000 degrees Celsius.

In terms of magnetism, cobalt is one of the few metals that can remain magnetic once magnetized. Its coercivity is high, the magnetism is difficult to heat (the Curie point is as high as 1150 degrees Celsius), and it is not easy to lose (cobalt steel is only Losing 2% and 3.5% of the magnetic properties). Therefore, it is widely used in the manufacture of high-performance magnetic materials.

Also, blue cobalt salts always give porcelain and enamel a beautiful color. The mineral or compound of cobalt has long been used as a glaze for ceramics, glass and enamel. Or you can add glass to make a different color.