It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals.
[1] Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing.
Roasting consists of thermal gas–solid reactions, which can include oxidation, reduction, chlorination, sulfation, and pyrohydrolysis.
Concern about the production of carbon dioxide is only a recent worry, following the identification of the enhanced greenhouse effect.
[citation needed] Smelting usually takes place at a temperature above the melting point of the metal, but processes vary considerably according to the ore involved and other matters.