Ans. 1) Roasting : It is the process of heating the ore in the presence of excess of air. This method is used in case of sulphide ores. The sulphides are converted into oxides by roasting and is evolved.
2) Calcination: It is the process of heating the concentrated ore in the absence of air. By this process volatile impurities are removed. The ore gets decomposed in this process.
3) Smelting : Smelting is a pyrochemical process, in which the ore is mixed with flux and fuel then is strongly heated. During smelting the impurities in the ore react with flux to form slag which is removed. Smelting is carried out in a specially built furnace known as blast furnace.