Question

Describe the principle controlling each of the following processes:
(i) Preparation of cast iron from pig iron.
(ii) Preparation of pure alumina (Al₂O₃) from bauxite ore.

Answer 1

(i) Pig iron is melt with scrap iron and coke using hot air blast. Due to this, impurities such as C, S and P present in the pig iron are removed as CO₂, SO₂ and P₂O₅ and carbon content reduced to about 3%.

(ii) Bauxite is soluble in concentrated NaOH solution whereas impurities are not.