The chief ore of zinc is the sulphide,
ZnS. The ore is concentrated by floatation process and then heated in air, which converts the
ZnS to
ZnO.
I. 2ZnS+3O290.6%−−−→2ZnO+2SO2The
ZnO is then treated with dilute
H2SO4.
II. 2ZnO+2H2SO4100%−−−→2ZnSO4+2H2O
Zn metal is produced on electrolysis.
III. 2ZnSO4+2H2O98.2%−−−→2Zn+2H2SO4+O2
Efficiencies of the processes have been indicated above the arrow mark. Mass of Zn will be obtained from an ore containing 225 kg of ZnS in kg is (nearest integer value):