Various steps involve are :
(a) Concentration: The ore is crushed and then concentrated: froth floation process.
(b) Roasting: The concentrated ore is then roasted in presence of excess of air at about 1200k when zinc oxide (ZnO) is formed.
(c) Reduction: Zinc oxide obtained above is mixed with powdered coke and heated to 1673K in a fire clay retort when it is reduced to Zinc metal.
At 1673 k, zinc metal being volatile (b.p. 1180 K), distills over and is condensed.
(d) Electrolytic refining: Impure zinc is made the anode while cathode consists of a sheet of pure zinc. The electrolyte consists of ZnSO4 solution acidified with dil H2SO4. On passing current pure Zn gets deposited on the cathode.
