How cobalt is made

Almost all cobalt is a byproduct of mining copper or nickel, so its supply follows those metals.

stations: 6
things upstream: 15
raw sources: 9
steps from the ground: 4

The short version

Cobalt is usually produced as a byproduct of copper and nickel mining. Ore from places such as the Copperbelt is floated to a concentrate and roasted, then leached with water and sulfuric acid to pull out cobalt salts. These are converted into cobalt oxide, which is reduced to metal with aluminum or carbon.

Mine the copper-cobalt ore

Cobalt is found in copper and nickel minerals, and the Copperbelt of the Democratic Republic of the Congo and Zambia supplies most of the world's cobalt. Mining is mostly aimed at the copper, and the cobalt comes with it.

Goes in
Cobalt ore
Float a concentrate

Froth flotation, with surfactants that bind to the ore minerals, enriches the cobalt-bearing ore and separates it from the waste rock.
Roast it to sulfate

Roasting converts the cobalt minerals to cobalt sulfate, and the copper and iron to oxides, which do not dissolve in water.
Leach out the cobalt

Water takes up the sulfate along with arsenates, and the leftover residue is leached again with sulfuric acid. Cobalt can also be leached from the slag of copper smelting.

Goes in
Sulfuric acid
Convert to cobalt oxide

The various products of leaching are transformed into cobalt oxide, Co3O4, which is the form that is reduced to metal.
Reduce it to metal

The oxide is reduced to metal by an aluminothermic reaction, in which aluminum takes the oxygen, or by carbon in a blast furnace.

Goes in
Aluminum

End of the lineCobalt Next it goes into hip implant, lithium-ion cell, hard drive and 3 more.

Worth repeating

Cobalt has colored glass blue since the Bronze Age, and the oldest cobalt-colored glass is from the eighteenth dynasty of Egypt.
The name comes from the kobold, a goblin that 16th-century German silver miners blamed for an ore that was a nuisance to them.