Question

Explain zone - refining (figure not necessary).

Answer 1

The process of zone refining follows the principle that impurities in a metal are more soluble when the metal is in the molten state than when it is in the solid state. Therefore, in the zone refining method, a circular mobile heater is attached to a metal rod (made of impure metal) at one end. The heater is moved and so does the molten zone of the rod. The pure metal gets removed from the melt through crystallization while the impurities pass on into the adjacent zone of molten metal. If this process is repeated, the impurities are gradually removed from the metal. The impurities finally accumulate at one end and this end can be cut off.