The process that involves the removal of sulphur from the ores is called roasting. In roasting, the ore is heated in a regular supply of air in a furnace at a temperature below the melting point of the metal. Some of the reactions involving sulphide ores are 2ZnS+3O2⟶2ZnO+2SO2 2PbS+3O2⟶2PbO+2SO2 2Cu2S+3O2⟶2Cu2O+2SO2