`text(Occurrence)` : Zinc is usually found in the combined state although traces of the metal in the native state have been reported from Melbourne (Australia). Its chief ores are :

(i) Zinc blende, `ZnS`.

(ii) Calamine or Sphalerite, `ZnCO_3`

(iii) Zincite, `ZnO`

(A) `text(Extraction process)` : It involves the following steps : See fig.

(B) `text(Roasting)` :

`text(Reactions)` :

`2ZnS + 3O_2 -> 2ZnO + 2SO_2`

`ZnS + 2O_2 -> 2ZnSO_4`

`ZnSO_4 -> 2ZnO + 2SO_2 + O_2`

When the ore is calamine, it shall decompose into oxide with evolution of carbon dioxide (calcination is used).

`ZnCO_3 -> ZnO + CO_2`

For roasting, a reverberatory furnace may be used.

`text(Smelting)` :

`ZnO + C -> Zn + CO`