Cobalt Mining

COBALT MINING:

Cobalt is a chemical element present in the Earth's crust, along with metallic ores of copper, nickel, and iron. It is an abundant element primarily found in the upper crust of the Earth.

ORES:

Traces of cobalt occur in ores such as cobaltite (CoAsS), linnaeite, skutterudite (CoAs₃), smaltite, heterogenite, erythrite (Co₃(AsO₄)₂·8H₂O), as well as in nickel and copper ores.

MINING:

The majority of cobalt is extracted as a byproduct of nickel, copper, and nickel-copper ore mines. Nickel and copper ores are mined using surface mining methods such as open-cut mining. In open-cut mining, ores near the Earth's surface are extracted. Copper and nickel ores containing cobalt are excavated from the wall benches created in the open-pit mine. The mined ore is collected and transported to nearby initial processing units by trucks using the ramps in the mines. Cobalt-containing ores are heavy and require blasting and drilling methods for proper excavation. This open-pit mining technique is widely used because it is less expensive and has fewer hazards.The Democratic Republic of Congo mines about 50% of the world's cobalt-containing copper ores.

PROCESSING AND EXTRACTION:

The 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. These small pieces are then melted to convert them from insoluble to soluble particles; this process is called smelting. The result of smelting raw ore is a copper-iron-cobalt alloy known as slag. The slag is collected and roasted in a blast furnace at high temperature, during which the cobalt is oxidized and recovered as cobalt oxide. The recovered cobalt oxide is then reduced to cobalt metal by heating it in the presence of aluminum.

In nickel-cobalt ore, cobalt is extracted from nickel during the electrolytic refining process as a precipitate in the electrolyte. The precipitate is in the form of cobalt hydroxide, which is later reduced into cobalt. On some occasions, cobalt can also be separated from the smelting of nickel. The nickel-cobalt slag obtained after smelting is leached under 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.

DEFINITION:

Cobalt is a solid, lustrous, grey metal, a chemical element with the symbol Co. Although cobalt-based colors and pigments have been used since ancient times for creating jewelry and paints, and miners have long used the name "kobold ore" for some minerals, free metallic cobalt was not discovered until 1735 by Georg Brandt.

PROPERTIES:

Cobalt is a ferromagnetic metal. Pure cobalt is not found in nature, but compounds of cobalt are common. Small amounts of it are found in most rocks, soil, plants, and animals. It has an atomic number of 27. The Curie temperature is 1115°C, and the magnetic moment is 1.6-1.7 Bohr magnetons per atom.

APPLICATION:

Most of the created cobalt is put away in cobalt-based superalloys. The temperature stability of these alloys makes them suitable for use in turbine blades for gas turbines and jet aircraft engines, though nickel-based single crystal alloys surpass them in this regard. Cobalt-based alloys are also corrosion and wear-resistant. Special cobalt-chromium-molybdenum alloys are used for prosthetic parts such as hip and knee replacements.