Bauxite

Bauxite is a naturally occurring, heterogeneous material composed primarily of one or more aluminum hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminosilicate[?], and other impurities in minor or trace amounts.

The principal aluminum 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 used as feed for the manufacture of alumina via a wet chemical caustic leach method commonly known as the Bayer process. Subsequently, the majority of the resulting alumina produced from this refining process is in turn employed as the feedstock for the production of aluminum metal by the electrolytic reduction of alumina in a molten bath of natural or synthetic cryolite (Na₃AlF₆), the Hall-Heroult process.

Bauxite is the only raw material used in the production of alumina on a commercial scale in the United States. However, the vast U.S. resources of clay are technically feasible sources of alumina. Other domestic raw materials, such as anorthosite[?], alunite[?], coal wastes, and oil shales, offer additional potential alumina sources. Although it would require new plants using new technology, alumina from these nonbauxitic materials could satisfy the demand for primary metal, refractories, aluminum 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 has been 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 departements.

World Bauxite Mine Production, Reserves, and Reserve Base

                        Mine production    Reserves    Reserve base
                         2000     2001
 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)

External Links

• USGS Minerals Information: Bauxite (http://minerals.usgs.gov/minerals/pubs/commodity/bauxite/)

See also: List of minerals