(a) Principle of hydraulic washing – This separation is based on the difference in the specific gravities of the gangue particles and the ore particles. The powdered ore is agitated with water or washed with a running water. The heavy ore particles settle down while the lighter particles of sand, clay etc. are washed away. 

(b) Chromatography : - It is based on selective distribution of the various constituents of a mixture between two phases. A stationary phase and a moving phase. The stationary phase can be either solid (such as alumina, silicagel) or tightly bound liquid on a solid support. The moving phase may be liquid or a gas. 

 (c) Froth – floatation process. This process is based on the fact that metallic sulphide ore particles are preferentially wetted by oil where as silicate gangue particles are preferentially wetted by water. So sulphide ore particles rise to the surface in the form of froth while gangue particles sink to the bottom.