Pyrometallurgi

Pyrometallurgy is the branch of extractive metallurgy that uses high temperatures to extract and refine metals from ores, concentrates, and secondary materials. It covers the preparation of feedstock and a sequence of thermal treatments, including calcination and roasting to convert minerals to oxides, followed by reduction and smelting to separate metal from its mineral matrix. Refining may involve high-temperature conversions to improve purity, or subsequent electrorefining in some cases; the latter is often considered a separate electrometallurgical process, but pyrometallurgical steps remain central for many metals.

Key processes in pyrometallurgy include roasting (oxidizing sulfides to oxides with release of sulfur gases), smelting (reducing oxides or sulfides with carbon or other agents to yield metal and a protective slag), and refining (further purification through high-temperature treatment and sometimes selective oxidation). The choice of method depends on ore type, desired purity, energy availability, and environmental controls.

Industrial systems rely on various furnaces and reactors, such as blast furnaces for iron production, reverberatory and flash smelting for copper and zinc, and related converters and refining furnaces. Feedstocks range from primary sulfide and oxide ores to secondary materials like scrap metal and spent catalysts.

Products of pyrometallurgy include base metals and their alloys, with associated slags and gases. The process is energy-intensive and historically significant, having driven the development of large-scale metallurgy. Modern practice emphasizes energy efficiency, gas cleaning, and slag or byproduct valorization to mitigate environmental impact while maintaining metal production.