Abstract

Extractive metallurgy that involves chemical production of metals from their naturally occurring compounds, follows mining of the ore, and the processing of the minerals. The essential extractive process, the reduction of a metallic compound to the metal, is often preceded by preparatory steps and followed by a refining one to achieve suitable properties.Pyrometallurgy, processing at high temperature, often yields a molten metal, but may produce a vapor or a solid. Refining is the removal of impurities by volatilization, precipitation, or by transfer into a molten slag phase as in steelmaking. Hydrometallurgy, processing through an aqueous solution, consists of leaching, purification of the pregnant solution, and recovery of the valuable metal by reduction or precipitation of one of its compounds. Electrometallurgy is the use of electrical energy for reducing the metal either from an aqueous electrolyte or from a high temperature melt. Examples are given for all processes.