Pyrometallurgie

Pyrometallurgy is the branch of extractive metallurgy that uses high temperatures to extract and purify metals from ores, concentrates, and secondary materials. It covers processes such as roasting and calcination to transform raw minerals into reactive oxides, followed by reduction and smelting to produce metal and a coexisting slag. The term derives from the Greek pyr, meaning fire, and metallurgy.

In roasting, sulfide minerals are oxidized to oxides with the release of sulfur gases, while calcination removes volatile parts from carbonates and hydrates. Smelting then reduces oxide compounds with a reducing agent (commonly carbon or carbon monoxide) in furnaces such as blast furnaces, reverberatory furnaces, or electric furnaces, yielding metal and slag. The extracted metal may undergo further refining, often by fire refining methods to achieve required purity. In some operations, smelting is integrated with matte and slag handling to separate metal sulfides and base metals.

Key pyrometallurgical technologies include flash smelting, which rapidly heats and reduces sulfide concentrates (notably for copper and nickel), and electric arc furnace processing for various ferrous and nonferrous metals. Pyrometallurgy is contrasted with hydrometallurgy, which uses aqueous solutions at lower temperatures.

Common applications involve ironmaking, copper smelting, and production of nickel, zinc, and lead. By-products include slag, dross, and sulfur-containing gases requiring abatement. The field faces environmental and energy challenges but also opportunities for process intensification and slag valorization, such as using slag as construction material or extracting valuable elements from it.

Historically central to metal production, pyrometallurgy remains a foundational approach in primary metallurgy, often complemented by hydrometallurgical and electrolytic methods in modern integrated plants.