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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 process produces a quantity of fluoride waste: perfluorocarbons and hydrogen fluoride as gases, and sodium and aluminium fluorides and unused cryolite as particulates. This can be as small as 0.5 kg per tonne of aluminium in the best plants in 2007, up to 4 kg per tonne of aluminium in older designs in 1974.
Aluminium recycling is the process in which secondary commercial aluminium is created from scrap or other forms of end-of-life or otherwise unusable aluminium. [1] It involves re-melting the metal, which is cheaper and more energy-efficient than the production of virgin aluminium by electrolysis of alumina (Al 2 O 3 ) refined from raw bauxite ...
Aluminium (or aluminum) metal is very rare in native form, and the process to refine it from ores is complex, so for most of human history it was unknown. However, the compound alum has been known since the 5th century BCE and was used extensively by the ancients for dyeing .
The Wöhler process was one of the first routes for producing aluminium metal. It involves the reduction of anhydrous aluminium chloride with potassium , produced powdered aluminium: [ 1 ] AlCl 3 + 3 K → Al + 3 KCl
In 1891 after Cowles began to advertise "pure aluminum" they were sued by the Pittsburgh Reduction Company. The judge announced his decision in January 1893, finding them to be infringing the patent of Hall and having gained knowledge of his process by hiring away a chemist named Hobbs who was the foreman in Pittsburgh.
Charles Martin Hall (December 6, 1863 – December 27, 1914) was an American inventor, businessman, and chemist.He is best known for his invention in 1886 of an inexpensive method for producing aluminum, which became the first metal to attain widespread use since the prehistoric discovery of iron.
Figure 1: Hall–Petch strengthening is limited by the size of dislocations. Once the grain size reaches about 10 nanometres (3.9 × 10 −7 in), grain boundaries start to slide. In materials science, grain-boundary strengthening (or Hall–Petch strengthening) is a method of strengthening materials by changing their average crystallite (grain