Concentration Of Ores

Removal of the unwanted materials from the ore is known as concentration, dressing or benefaction. It involves multiple steps and these steps depend upon the physical properties of the compound of the metal in that ore.

1. Hydraulic Washing

This is based on the differences in gravities of the ore and the gangueparticles. It is therefore a type of gravity separation. In one such process an upward stream of running water is used to wash the powdered ore. The lighter gangue particles are washed away and the heavier ores are left behind

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.

4. Leaching

Leaching is used when the ore is soluble in some suitable solvent. 

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