Sno.

Roasting

Calcination

1.

It is the process of heating the ore below its melting point with an excess of air.

It is the process of heating the ore below its melting point in the absence or limited supply of air.

2.

Sulphide ores are converted into oxide ores.

Carbonate ores are converted into oxide.

3.

Volatile impurities are removed as oxides SiO₂, As₂O₃, etc.

Water and organic impurities are removed.