Bismuth - Occurrence and Production

Occurrence and Production

In the Earth's crust, bismuth is about twice as abundant as gold. The most important ores of bismuth are bismuthinite and bismite. Native bismuth is known from Australia, Bolivia, and China.

According to the United States Geological Survey, the world mining production of bismuth in 2010 was 8,900 tonnes, with the major contributions from China (6,500 tonnes), Peru (1,100 tonnes) and Mexico (850 tonnes). The refinery production was 16,000 tonnes, of which China produced 13,000, Mexico 850 and Belgium 800 tonnes.

The difference between world bismuth mine and refinery production reflects bismuth's status as a byproduct of extraction of other metals such as lead, copper, tin, molybdenum and tungsten. Bismuth travels in crude lead bullion (which can contain up to 10% bismuth) through several stages of refining, until it is removed by the Kroll-Betterton process which separates the impurities as slag, or the electrolytic Betts process. Bismuth will behave similarly with another of its major metals, copper.

The raw bismuth metal from both process contains still considerable amounts of other metals, foremost lead. By reacting the molten mixture with chlorine gas the metals are converted to their chlorides while bismuth remains unchanged. Impurities can also be removed by various other methods for example with fluxes and treatments yielding high-purity bismuth metal (over 99% Bi). World bismuth production from refineries is a more complete and reliable statistic.