MODEL RELEASED. Aluminium processing plant. Worker removing bars of aluminium from an electrolysis tank. Aluminium metal is produced from the aluminium ore bauxite. The first stage involves crushing the bauxite, dissolving it in caustic soda and then heating it to precipitate out alumina, a white powder. The alumina is then mixed with molten cryolite (sodium-aluminium fluoride) in a tank lined with pitch and coke. This lining acts as a cathode. A carbon anode is inserted into the tank and an electrical current is passed through it. The breaks the alumina down into molten aluminium and oxygen. The aluminium is then cooled and removed for further processing.