Cobalt Mining

Cobalt is chemical element present on the earth's crust along the metallic ore of copper, nickel and iron. It is an abundant element which is found mostly on the upper crusts of the earth.

Ores:

The traces of cobalt occurs in the ores such as cobaltite (CoAsS), linnaeite, skutterudite (CoAs3), smaltite, heterogenite, erythrite (Co3(AsO4)2?8H2O) and with nickel and copper ores.

Mining:

Majority of cobalt is extracted as a byproduct of the nickel, copper and nickel-copper ore mines. The mining of nickel and copper ores are executed by surface mining methods such as open cut mining. In open cut mining the ores which present near the surface of the earth is mined. The copper and nickel ores containing cobalt are excavated in the created wall benches of the open pit mine. The mined ore is collected and transported to the nearby initial processing unit by trucks using the ramps in the mines. The cobalt containing ores are heavy and needs blasting and drilling methods to excavate properly. This open pit mining technique is widely used as it is less expensive and has fewer hazards.

Democratic Republic Of Congo mines about 50% of the world's cobalt containing copper ores.

Processing and extraction:

Extraction of cobalt from copper and nickel ore is a complex process. In copper ? cobalt ores, the extracted ore is initially milled and crushed into small pieces. The small pieces are then made to melt to convert them from insoluble to soluble particles; this process is called as smelting. The resultant of the smelting of raw ore will be copper-iron-cobalt alloy as a slag. The slag is collected and roasted in a blast furnace with high temperature in which the cobalt is oxidized and recovered as cobalt oxide. The recovered cobalt oxide is reduced to cobalt metal by heating in the presence aluminum.

In nickel-cobalt ore, cobalt is extracted from nickel during electrolytic refining process as precipitate in the electrolyte. The precipitate is will be in the form of cobalt hydroxide which is later reduced into cobalt. Some occasions, cobalt can also be separated from smelting of nickel. The nickel- cobalt slag obtained after smelting is leached under the pressure with ammonia which in turn reduces the cobalt by hydrogen. The reduced product is obtained as cobalt metal. China is the largest producer of refined cobalt as it imports raw cobalt ore from Congo for processing and sale.