Zone refining is based on the principle that ___________.

A circular mobile heater is fixed at one end of a rod of the impure metal.Molten zone passes through a rod slowly and the impurities dissolve in the molten metal and move along leaving behind very pure metal which crystallises out. This method of purification is called zone refining and is based on the principle that impurities are more soluble in molten metal than in solid metal.