Bauxite

Description

Bauxite is a sedimentary rock that serves as the primary industrial source for aluminum and gallium production. Mineralogically, it is composed of aluminum-bearing minerals—specifically gibbsite, boehmite, and diaspore—integrated with iron oxides such as hematite and goethite, alongside the clay mineral kaolinite and minor quantities of anatase and ilmenite. Physically, the material typically exhibits a dull luster and ranges in color from white or tan to reddish-brown. In metallurgical and ceramic contexts, bauxite undergoes the Bayer process, which utilizes grinding, high-pressure caustic digestion with lime, precipitation, and calcination to isolate aluminum oxide. This refining process is necessary to extract alumina from the raw ore, which often possesses a loss on ignition (LOI) of approximately 25%, reflecting its inherent water content and the need for significant thermal processing to achieve the stable white powder required for industrial applications.