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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]
Bauxite is the main source of the rare metal gallium. [17] During the processing of bauxite to alumina in the Bayer process, gallium accumulates in the sodium hydroxide liquor. From this it can be extracted by a variety of methods. The most recent is the use of ion-exchange resin. [18]
Aluminium smelting is the process of extracting aluminium from its oxide, alumina, generally by the Hall-Héroult process. Alumina is extracted from the ore bauxite by means of the Bayer process at an alumina refinery .
Bauxite was discovered in 1821 by Pierre Berthier who named it after a village named Les Beaux where he found it. [6] To obtain the alumina from the bauxite ore, a process was developed that used acid to dissolve aluminium but resulted in a product that contained large amounts of iron and titanium dissolved within which were difficult to remove. [6]
The Hall–Héroult process is the major industrial process for smelting aluminium.It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite, aluminium's chief ore, through the Bayer process) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell.
The first stage is the calcination of the bauxite at 1200 °C with sodium carbonate and coke. The alumina is converted in sodium aluminate. Iron oxide remains unchanged and silica forms a polysilicate. In the second stage sodium hydroxide solution is added, which dissolves the sodium aluminate, leaving the impurities as a solid residue. The ...
A metamorphic rock called emery that is mostly made of corundum which is an aluminum oxide. This is an example of an aluminum deposit. Aluminum is the third most abundant element in the lithosphere at 82,000 ppm. It occurs in low levels, 0.9 ppm, in humans. [1] Aluminum is known to be an ecotoxicant and expected to be a health risk to people.
Bauxite, a major aluminium ore. The red-brown color is due to the presence of iron oxide minerals. Overall, the Earth is about 1.59% aluminium by mass (seventh in abundance by mass). [64] Aluminium occurs in greater proportion in the Earth's crust than in the universe at large.