Bismuth Production
Bismuth Production
Lead concentrates which are obtained from lead, lead-zinc and complex ores are the main source of bismuth. The common bismuth concentration in them is several hundredths of a percent, sometimes they reach 0.2%. Bismuth gets into the crude lead during the processing from which it is separated after refining. Bismuth is extracted using magnesium and calcium which transfer it as CaMg2Bi2 in dross, the surface layer. Another way of separation also is utilized using potassium and magnesium. Electrolytic refining during which bismuth passes into slimes is also applied.
Bismuth concentrates which contain approximately 3-5% of bismith (rarely the concentration may reach 30-60%) may be obtained by flotation on bismuth ores and are processed by either reducing fusion or precipitating smelting adding metal iron.
Refining consists of several steps of fusion processing: by sulphur adding coal for iron and copper removing; by alkali adding oxidizer or by air blasting for removing arsenic, antimony and tin; zinc used for removing gold and silver, and chlorine applied for removing lead and zinc. Electrolytic refining of water solutions [BiCl3, Bi2(SiF6)3], as well as fusions is also used. Combination of various methods is used for extracting high-pure bismuth.