Describe the underlying principle of each of the following metal refining methods :
Electrolytic refining of metals.

Explanation

This method is used for the refining of Ag, Au, Cu, Zn, Ni, Cr, etc. In this method, impure metal forms the anode while a thin plate of pure metal acts as cathode. The electrolytic solution consists of soluble salt of the metal. On passing electric current, the pure metal gets deposited on the cathode and insoluble impurities settle down at the anode in the form of anode mud.