Bauxite
Bauxite is an amorphous clayey sedimentary rock, primarily known as the main commercial ore of aluminium. It comprises mostly of aluminium oxides and hydroxides (or hydrated alumina), often with iron oxide impurities.
Bauxite can be found in many countries, with a higher level of deposits in the tropics. Australia has been one of the top exporters since the 1950's with a list that now includes China, Indonesia, Brazil, and India.
Bauxite is mined by open-cut mining, which is a surface method where topsoil is removed and frequently stored for later land restoration. The bauxite ore is then processed, most commonly by the Bayer process, where it is heated to up to 200 degrees C, under pressure with a sodium hydroxide solution (caustic soda). The aluminium is dissolved as sodium aluminate (primarily [Al(OH)4]−) and extracted.
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