Explain the two steps involved in the metallurgy of Zinc metal from zinc sulphate using appropriate balanced chemical equations.
Answers
Explanation:
Zinc: The important ores of Zinc are
Zinc blende, ZnS
Calamine, ZnCO
3
Zincite, ZnO
The extraction of zinc blende involves the following steps
(i) Concentration: The ore is crushed and then concentrated by froth-floatation process.
(ii) Roasting: The concentrated ore is then roasted in the presence of excess of air at about 1200K.
2ZnS+3O
2
Δ
2ZnO+2SO
2
↑
(iii) Reduction: Zinc oxide is mixed with powdered coke and heated to 1673 K in a fire clay retort, in which ZnO is reduced to zinc metal.
ZnO+C
1673K
Zn+CO↑
(iv) Purification: Zinc is purified by electrolytic refining. Where
Anode is impuric zinc
Cathode is a thin sheet of pure zinc
Electrolyte is Zinc sulphate solution + a little of dil. H
2
SO
4
On passing electric current, pure zinc get deposited at the cathode.