bauksiitti

Bauksiitti is a naturally occurring sedimentary rock that is the primary ore of aluminum. It is composed mainly of aluminum hydroxides, including gibbsite, boehmite, and diaspore, along with impurities such as iron oxides, silica, and titanium dioxide. The color of bauxite can vary from white and gray to reddish-brown and yellow, depending on its mineral composition. Bauxite deposits are typically found in tropical and subtropical regions, often forming from the weathering of aluminum-rich rocks like granite and basalt.

The process of extracting aluminum from bauxite is a two-step method. First, the bauxite ore is purified using the Bayer process, which involves dissolving the aluminum compounds in a hot solution of sodium hydroxide. This produces a concentrated solution of sodium aluminate, from which pure aluminum hydroxide precipitates. This aluminum hydroxide is then heated to produce alumina (aluminum oxide). Second, the alumina is smelted in an electrolytic process called the Hall-Héroult process, where it is dissolved in molten cryolite and subjected to an electric current. This electrolysis separates the aluminum metal from the oxygen.

Bauxite is a crucial raw material for the global aluminum industry, with aluminum being used in a wide range of applications, including transportation, construction, packaging, and electronics. Major bauxite-producing countries include Australia, Guinea, Brazil, China, and India. The mining and processing of bauxite can have significant environmental impacts, including habitat destruction, water pollution, and greenhouse gas emissions, which are subjects of ongoing research and mitigation efforts.