excess of air. This process is known as roasting. Generally the sulphide ores are roasted to convert them into oxides before reducing them to metal.

The metal oxides are then reduced to the corresponding metal by using suitable reducing agent such as carbon

oxides are reduced by coke in a closed furnace which gives the metal and carbon monoxide (CO).

In the extraction of Cu from its sulphide ore, the ore is subjected partial roasting in air to give its oxide.

When the supply of air is stopped and the temperature is raised. The rest of the sulphide reacts with oxide and forms the metal and SO2.

Thermite process involves the reaction of metal oxides with aluminium. When highly reactive metals such as sodium, calcium, aluminium etc., are used as reducing agents, they displace metals of lower reactivity from the compound. These displacement reactions are highly exothermic. The amount of heat evolved is so large that the metals produced are in molten state.