Write the principles of the following methods: (i) Froth floatation method (ii) Electrolytic refining

(i) It is based on the difference in wetting qualities of gangue and the sulphide ore particles with water and oil. Whereas the ore particles are wetted by oil, the gangue or the earthy particles are wetted by water. (ii) In electrolytic refining process a slab of impure copper is used as anode and a thin sheet of pure copper as cathode. The copper sulphate is used as electrolytic solution. By passing electricity through the cell copper is dissolved from the anode and deposited on cathode. The impurities either remain in solution or collect as an insoluble gangue.