Give an example of zone refining of metals.

It is based on the principle that when an impure metal in a molten state is allowed to cool, only the metal crystallizes while the impurities remain present in the molten state (mass) or melt. The impure metal converted into a rod which is heated at one end with a circular heater. This method is used for refining metals having a low melting point. e.g., tin, lead, bismuth.