Explain electrolytic refining.

(N/A) In this method,the impure metal is made to act as the anode. $A$ strip of the same metal in pure form is used as the cathode. They are placed in a suitable electrolytic bath containing a soluble salt of the same metal.
The reactions taking place at the electrodes are:
Anode: $M \rightarrow M^{n+} + ne^-$
Cathode: $M^{n+} + ne^- \rightarrow M$
For example,in the refining of copper,impure copper acts as the anode and pure copper strips act as the cathode. The electrolyte is an acidified solution of copper sulphate. The net result of electrolysis is the transfer of pure copper from the anode to the cathode:
Anode: $Cu \rightarrow Cu^{2+} + 2e^-$
Cathode: $Cu^{2+} + 2e^- \rightarrow Cu$
Impurities like antimony,selenium,tellurium,silver,gold,and platinum settle down as anode mud,which can be recovered to offset the cost of refining.