Explain different methods of concentration of ores.

There are mainly three different methods for concentration of ores and they are:

i) Concentration or centrifugation on the basis of difference of densities: This method is used when there is large difference in densities of ores and impurities. In this method finely, powdered ore is placed on a moving table with slots and it is moved rapidly so that light particles of metal remain in the slot in the table

ii) Froth floatation method: This method is used for the concentration of ores of the metals whose ores are in sulphide form.

The fine powder of ore and water are filled in a big vessel and pine or turpentine oil is added to it. The sulphide particles of metals get wet and stick to it, while impurities do not get wet.

Air is passed with pressure through a tube and froth is produced around the light particles of the sulphide ore and comes to the surface of the liquid mixture.

The impurities get wet by water and settles down and the ore is removed with sieves and washed with water.

By this method clay, sand, etc are removed.

iii) Magnetic separation: This method is used when either of ore or the impurity have some magnetic properties.

Powdered ore is allowed to fall on a belt.

A magnet at one end of the belt which attracts the ore particles and fall nearer, the remaining particles fall away because of not being attracted.

Thus, by method of magnetic separation impurities are removed from the ore.