Answer. Refining the impure metal by electrolysis is the most widely used process of refining metals. The impure slab of the metal is made the anode, while a pure thin sheet of metal is made the cathode. For example, electrolytic refining of copper is carried out in an electrolytic tank having copper sulphate solution as shown in figure below:
On passing the electric current through the solution, anode (impure copper) dissolves to provide Cu2+ ions to the solution. These Cu2+ ions are discharged by gaining of electrons from the cathode.
Thereby copper atoms deposit on the cathode, making it thick block of pure copper metal as is shown in figure. The impurities like gold and silver settle down as anode mud.