Concentration Of Ores
1. Hydraulic Washing
2. Magnetic Separation
If either the ore or the gangue is capable of being attracted by a magnetic field, then such magnetic separation is used. In this method, finely ground ore is passed on through a magnetic conveyor belt and it separates magnetic and non magnetic particles.
3. Froth Flotation Method
This is mainly used for removing gangue from sulphide ores.
In this process, a suspension of the powdered ore is made with water. To it, collectors and froth stabilisers are added. Collectors enhance non-wettability of the mineral particles and froth stabilisers stabilise the froth.The mineral particles become wet by oilswhile the gangue particles by water. A rotating paddle agitates the mixture and draws air in it. As a result, froth is formed which carries the mineral particles. The froth is light and is skimmed off. It is then dried for recovery of the ore particles.
Leaching is used when the ore is soluble in some suitable solvent.