Aluminium is industrially extracted from bauxite by Bayers process. It involves 3 steps - 

1. Heating the bauxite ore with sodium hydroxide at very high temperatures like 150 - 200ºC

Al₂O₃ + 2 NaOH → 2 NaAlO₂ + H₂O

2. Conversion to aluminium hydroxide

2 H₂O + NaAlO₂ → Al(OH)₃ + NaOH

3. Conversion to aluminium oxide from which pure aluminium is extracted by Halt=Heroult method.

2 Al(OH)₃ → Al₂O₃ + 3 H₂O