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