With an example, explain roasting.

Explanation

Roasting is a method in which sulphide ore is heated in a regular supply of air at a temperature below the melting point of the metal. It converts sulphide ores into oxide ores. A part of sulphide may also act as reducing agent. In this method, impurities such as S, As, P, etc. is removed as volatile gases and ore becomes porous e.g.
`2ZnS + 3O_(2)overset(Delta)rarr 2ZnO + 2SO_(2)`