Write essential equations in extraction of zinc from zinc blend
Answers
Extraction of Zinc from Zinc Blend: Zinc is mainly extracted from its sulphide ore , zinc blend. The various steps involved are as following:
Step1: Concentration: the ore is crushed and then concentrated by froath floatation procss as it is a sulphide ore
Step2: Roasting: Since the ore is a sulphide ore, so it is then roasted in prescence of excess air at about 1200K when ZnO (zinc oxide) is formed as; 2ZnS + 3O2 --> 2ZnO + 2SO2
Step 3: Reduction: Zinc oxide is now mixed with powdered coke and heated to 1673K in a fire clay retort to produce Zn metal as; ZnO + C --> Zn +CO
Step 4: Purification: Now the zn obtained is purified as follows;
a. By fractional distillation Since impure zinc contaions Cd, Pb, Fe etc. so it is distilled by fractional methode so that the all the other matals are distilled by leaving Zn as all of them have different b.pt.
b. By electrolysis impure Zn is made as anode and the pure zn makes a cathode in a ZnSO4solution containing a little dil. sulphuric acid. Now on passing electric current , pure Zn-metal is obtained.