Question

differentiate between calcination and roasting​

Answer 1

Calcination : It is used to convert carbonate ore into oxide ore.

It takes place in absence or limited supply of air.

Roasting:It is used to convert sulphide ore into oxide ore.

It takes place in presence of oxygen.

Answer 2

Roasting

Calcination

One is heated in the presence of excess of oxygen or air. one is heated in the absence or limited supply of oxygen or air

This method is employed for sulphide ores. This method is employed for carbonate ores.

Sulphur dioxide is produced along with metal oxide. Carbon dioxide is produced along with metal oxide.

Example: For the ores ZnS (sphalerite) and Cu2S (chalcocite), balanced equations for the roasting are:

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

2 Cu2S + 3O2 → 2 Cu2O + 2 SO2

Example: ZnCO3--> ZnO+ C02