Metals that are very reactive (placed at the top position of the electrochemical series) such as sodium, calcium, magnesium and aluminium are extracted from their compounds using electrolysis. Electrolysis is usedbecause these reactive metals cannot be extracted from the minerals by reduction using carbon.
Extraction of Aluminium Metal from the Mineral Bauxite.
Bauxite is the major ore of aluminium consisting of Aluminium oxide, Al2O3. Cryolite (Na3AlF6) is added to aluminium oxide to lower its melting point from 2000˚C to about 950˚C. Molten aluminium oxide is electrolysed using carbon as electrodes in the electrolytic cell as show in figure below: