What is the significance of leaching in the extraction of aluminium?
Bauxite is the principal ore of aluminium. The impurities present in bauxite are SiO 2 , iron oxides and titanium oxide (TiO 2 ). Al 2 O 3 is extracted out as sodium aluminate. The impurity, SiO 2 too dissolves forming sodium silicate. Other impurities are left behind. Al 2 O 3 +2NaOH+3H 2 O→2Na[Al(OH) 4 ] Thus, leaching is used to remove the impurities present and hence option A is the correct option.
