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Reddish-brown bauxite Bauxite with US penny for comparison QEMSCAN mineral maps of bauxite ore-forming pisoliths. Bauxite (/ ˈ b ɔː k s aɪ t /) is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium and gallium.
Bauxite forms by the weathering of aluminum-rich and silica-poor rocks in hot, humid, climates, at places with good drainage. Under the proper conditions, weathering disintegrates the aluminium silicate minerals, and dissolves and removes the silica, creating bauxite. The mined US bauxite deposits have all been in the southeastern United States.
Boehmite or böhmite is an aluminium oxide hydroxide (γ-AlO(OH)) mineral, a component of the aluminium ore bauxite. It is dimorphous with diaspore. It crystallizes in the orthorhombic dipyramidal system and is typically massive in habit. It is white with tints of yellow, green, brown or red due to impurities.
The US imported nearly all the bauxite (the only commercial aluminum ore) used in producing primary aluminum. For years, the US has produced less than 1% of the bauxite used to make aluminum. The US also imported 33 percent of the aluminum that was used in 2014. Of the imported aluminum, 63% came from Canada. [1] [19]
Bauxite is a raw material used primarily in the production of aluminium. The bauxite ore is refined into alumina before being smelted into aluminium. [3] Australia is known for its high-grade ore, especially in the Weipa and Gove deposits. [2] The quality of bauxite ore is determined by its available alumina (Al 2 O 3) content.
The Bayer process is the principal industrial means of refining bauxite to produce alumina (aluminium oxide) and was developed by Carl Josef Bayer.Bauxite, the most important ore of aluminium, contains only 30–60% aluminium oxide (Al 2 O 3), the rest being a mixture of silica, various iron oxides, and titanium dioxide. [1]
Red mud near Stade Bauxite, an aluminium ore (Hérault department, France). The reddish colour is due to iron oxides that make up the main part of the red mud. Red mud , now more frequently termed bauxite residue, is an industrial waste generated during the processing of bauxite into alumina using the Bayer process .
Gibbsite is an important ore of aluminium in that it is one of three main phases that make up the rock bauxite. Gibbsite has three named structural polymorphs or polytypes : bayerite (designated often as α-Al(OH) 3 , [ 2 ] : 2 but sometimes as β-Al(OH) 3 ) [ citation needed ] , doyleite , and nordstrandite .