chemical reaction of zinc

The following processes are involved in the extraction of zinc from zinc blende:
(i) Concentration: Zinc blende ore is crushed and the concentration done by froth- floatation process.
(ii) Roasting: The concentrated ore is then roasted in presence of excess of air at about 1200 K as a result zinc oxide is formed.

(iii) Reduction : Zinc oxide obtained above is mixed with powdered coke and heated to 1673 K in a fire clay retort where it is reduced ‘ to zinc metal.

At 1673 K, zinc metal being volatile (boiling point 1180 K), distills over and is condensed.
(iv) Electrolytic refining: Impure zinc is made the anode while pure zinc strip is made the cathode. ZnSO4 solution acidified with dil. H2SO4 is the electrolyte used. On passing electric current, pure zinc gets deposited on the cathode.