Question

Why calcination is not performed on sulphide ores?

Answer 1

Oxides of substance are easy to purify than other ores. So for purification all the ores are first converted into it's oxide. Sulphide ores are converted into it's oxide by a process called roasting. In this process the sulphide ore is strongly heated in excess of oxygen to form it's oxides. The process of converting carbon ores into it's oxides is called calcification. This is done by heating the ore in limited supply of oxygen. Roasting is done with excess of air and calcification limited supply of air so Roasting cannot be carried on carbonate ores.