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Bauxite is a naturally occurring, heterogeneous material composed primarily of one or more aluminium hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminium silicates, and other impurities in minor or trace amounts. Bauxite is a sedimentary rock produced by in situ chemical weathering typically under tropical to subtropical climate conditions.
The principal aluminium hydroxide minerals found in varying proportions with bauxites are gibbsite and the polymorphs boehmite and diaspore. Bauxites are typically classified according to their intended commercial application: abrasive, cement, chemical, metallurgical, refractory, etc.
The bulk of world bauxite production (approximately 85%) is processed into aluminium oxide (Al2O3, also known as alumina) via a wet chemical, caustic leach method (the Bayer process). The resulting Al2O3 is then reduced to aluminium metal (Al) using an electrolytic process, the Hall-Heroult process.
Bauxite is the raw material most widely used in the production of aluminium on a commercial scale. Other raw materials, such as anorthosite, alunite, coal wastes, and oil shales, offer additional potential Al2O3 sources. Although it would require new facilities and technology, Al2O3 from these nonbauxitic materials could satisfy the demand for primary metal, refractories, aluminium chemicals, and abrasives. Synthetic mullite, produced from kyanite and sillimanite, substitutes for bauxite-based refractories. Although more costly, silicon carbide and alumina-zirconia substitute for bauxite-based abrasives.
History
Bauxite was named after the village Les Baux de Provence in southern France, where it was first discovered in 1821 by the geologist Pierre Berthier.
Due to the exhaustion of its bauxite mines, France has almost completely ceased the exploitation of bauxite since 1991. French mines were located in the Var, Bouches-du-Rhône and Herault départements.
World Bauxite Mine Production, Reserves, and Reserve Base
(x1000 tonne)
Mine production Reserves Reserve base
2000 2001
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Australia 53,800 53,500 3,800,000 7,400,000
Brazil 14,000 14,000 3,900,000 4,900,000
China 9,000 9,200 720,000 2,000,000
Guinea 15,000 15,000 7,400,000 8,600,000
Guyana 2,400 2,000 700,000 900,000
India 7,370 8,000 770,000 1,400,000
Jamaica 11,100 13,000 2,000,000 2,500,000
Russia 4,200 4,000 200,000 250,000
Suriname 3,610 4,000 580,000 600,000
United States NA NA 20,000 40,000
Venezuela 4,200 4,400 320,000 350,000
Other countries 10,800 10,200 4,100,000 4,700,000
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World total (rounded) 135,000 137,000 24,000,000 34,000,000
(Numbers for 2001 estimated)
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