This is the Commercial process for the production of
Aluminium from
Alumina. It was discovered in 1886 by two people in different continents, Hall in
America and Heroult in
Europe.
By this method, Alumina is mixed with molten Cryolite. An electrolytic reduction cell is then set up in which the anode is a carbon rod, which is consumed by the process. A Cryolite-Alumina electrolyte is placed in contact with these, with a layer of molten aluminium below it. The Aluminium is siphoned off regularly and the electrolyte replaced.
Esssentially, the rection is as follows, 2Al2O3
+3C -> 4Al +3CO2.
Electricity is used to power the reaction, using 13000-15000 kWh for each tonne of Aluminium produced. It also takes approximately 3.5 tonnes of Bauxite to produce 1 tonne of Aluminium.