BAUXITE

BeschreibungBauxite is the major source of aluminum sesquioxide (alumina, Al2O3) worldwide. Bauxite is a soft and red clay, rich in alumina. From a geological point of view bauxite is defined as a residual sedimentary rock in the laterite family that results from in situ superficial weathering in moist tropical climates of clays, clayey limestones, or high-alumina-content silicoaluminous igneous and metamorphic rocks containing feldspars and micas.Bauxite is a sedimentary rock, so it has neither a precise definition nor chemical formula. From a mineralogical point of view, bauxite is mainly composed of hydrated alumina minerals such as gibbsite [Al(OH)3 or Al2O3.3H2O, monoclinic] in recent tropical and equatorial bauxite deposits, while boehmite [AlO(OH) or Al2O3.H2O, orthorhombic] and, to a lesser extent, diaspore [AlO(OH) or Al2O3 .H2O, orthorhombic] are the major minerals in subtropical and temperate bauxite old deposits. The average chemical composition of bauxite is 45 to 60 wt.% Al2O3 and 10 to 30 wt.% Fe2O3, the remainder consisting of silica, calcia, titanium dioxide, and water.

VerwendenAbsorbent catalysts

VerwendenBauxite is refined into alumina and then smelted into pure metal. Its uses include abrasives, high-temperature furnace bricks (refractories), and high-alumina cement.

DefinitionA natural aggregate of aluminumbearing minerals, more or less impure, in which the aluminum occurs largely as hydrated oxides. It is usually formed by prolonged weathering of aluminous rocks. Contains 30–75% Al2O 3 , 9–31% H2O, 3–25% Fe2O 3 , 2–9%, SiO2, 1–3% Ti O 2 .