Heavy metals like Cu . Zn , Fe . So , etc ., arc obtained by roasting and smelting .
Reduction of the Oxides to Metal
The roasted or the calcined ore is then converted to the free metal by reduction . Reduction method depends upon the activity of metal .
Metals which are low in the activity series ( like Cu , Hg , Au ) are obtained by heating their compounds lD air : metals which are in the middle of the activity “ cries ( like Fe . Zn , Ni , Sn ) are obtained by heating their oxides with carbon while metals which are very high in the activity series ( e . g ., Na , K , Ca , Mg , Al ) are obtained by electrolvtic reduction method .
( i ) Smelting ( reduction with carbon ) The process of extracting the metal by fusion of its oxide ore with carbon ( C ) or CO is called smelting . It is carried out in a reverberatory furnace .
During smelting a substance . called flux is added which removes the nonfusible impurities as fusible slag . This slag is insoluble in the molten metal and is lighter than the molten metal . So , it floats over the molten metal and is skimmed off .
Acidic flux For basic impurities , acidic flux is added . e . g ., CaO + SiO2 → CaSiO3