The non-volatile impurities are infusible and remain behind. In this process, metals with low boiling point, such as zinc,calcium and mercury are vaporized in a vessel. The pure vapours are condensed into pure metal in a different vessel. The non-volatile impurities are not vaporised and so are left behind. In this process, the impurities are oxidised instead of the metal itself.
Air is passed through the molten metal.
The impurities like phosphorus, sulphur, silicon and manganese get oxidised and rise to the surface of the molten metal, which are then removed. The process of electrolysis is used to obtain very highly purified metals. It is very widely used to obtain refined copper, zinc, tin, lead, chromium, nickel, silver and gold metals. In this process, The impure slab of the metals is made the anode A pure thin sheet of metal is made the cathode A salt solution of the metal is used as the electrolyte. On passing current, pure metal from the electrolyte is deposited on the cathode.