Question

please solve the problem

Answer 1

CALCINATION : It is the process of heating the concentrated ore in the absence of air. By this process, volatile impurities are removed.

Carbonate an hydrated oxide ores are calcined as shown.

∆

Al2O3.H2O ---------> Al2O3 + H2O

∆

CaCo3 ---------> CaO + CO2

ROASTING : It is the process of heating the ore in the presence of excess air. This method is used in case of sulphide ores. The sulphides are converted into oxides by roasting and SO2 is evolved.

For example,

∆

2ZnS + 3O2 --------> 2ZnO + 2SO2

∆

2PbS + 3O2 --------> 2PbO + 2SO2