Smelting
Chemical reduction or smelting is a form of extractive metallurgy. The main use of smelting is to produce iron and steel.
It makes use of a chemical reducing agent such as carbon (coke, or in earlier times charcoal) to change the oxidation state of the metal ore. When coke is mixed with iron ore and heated, the oxygen will move from the iron to the carbon. The iron will be reduced, and the carbon will be oxidised, producing carbon dioxide and carbon monoxide. A fluxing agent such as limestone is used to remove the accompanying rock gangue as slag.
See also