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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 ...
Hall and Heroult share credit for inventing aluminium electrolysis. [9] The Hall–Heroult method is the primary method of producing modern aluminium and requires high purity alumina to produce aluminium. The Bayer process produces high purity alumina which is then used in the Hall–Heroult process as the main raw material. [9]
Bust of Heroult in Thury-Harcourt. Paul (Louis-Toussaint) Héroult (10 April 1863 – 9 May 1914) was a French scientist. He was one of the inventors of the Hall-Héroult process for smelting aluminium, and developed the first successful commercial electric arc furnace. [1]
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
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Molten cryolite is used as a solvent for aluminium oxide (Al 2 O 3) in the Hall–Héroult process, used in the refining of aluminium. It decreases the melting point of aluminium oxide from 2000–2500 °C to 900–1000 °C, and increases its conductivity [ 18 ] thus making the extraction of aluminium more economical.