Explain the process of producing alumina from bauxite.

Explanation

Bauxite `(Al_2 O_3. 2H_2 O)` is the ore of aluminium. The ore of aluminium contains impurities such as silicas, oxides of iron etc: The powdered ore is treated with fiat concentrated solution of NaOH under pressure to form sodium aluminate solution. The gangue remains at the bottom and is filtered off and a little aluminium hydroxide is added to it. The aluminium hydroxide is added to it. The aluminium hydroxide in solution is precipitated. This is filtered washed and strongly heated when we get anhydrous alumini.