1. extraction of metals extraction of aluminium -
Metals can be extracted from their ores by electrolysis. Electrolysis is an expensive method and is used to extract very reactive metals such as aluminium, calcium and sodium.
extraction of aluminium
aluminium is extracted from its ore, bauxite (Al2O3).
giant crucible for holding molten aluminium
molten Al2O3 and cryolite +
to electric power supply -
steel tank lined with carbon
carbon electrodes
molten aluminium produced from the decomposition of Al2O3
industrial electrolysis of aluminium

2. extraction of metals extraction of aluminium 2O2-(l) O2(g) + 4e-
the electrolyte is molten aluminium oxide and molten cryolite
electrolyte contains Al3+ and O2- ions
at the anode, O2- ions are discharged as O2 gas; O2 burns away the carbon anodes; C electrodes must be replaced
2O2-(l) O2(g) + 4e-
at the cathode, Al3+ ions are discharged as molten aluminium; collected in a crucible
Al3+(l) + 3e Al(l)
overall reaction
2Al2O3(l) Al(l) + 3O2(g)