Explain the purification of sulphide ore by Froth Floatation Method.

Explanation

Froth floatation method :
`rarr` This method is used to concentrate sulphide ores.
`rarr` In this process a suspension of the powdered ore is made with water.
`rarr` A rotating paddle is used to agitate the suspen-sion and air is blow into the suspension in presence of an oil.
`rarr` froth is formed as a result of blown of air, which carries the mineral particles.
`rarr` To the above slurry froth collectors and stabilizers are added.
`rarr` Collectors like pine oil enhance non -wetta-bility of the mineral particles .
`rarr` forth stabilizers like cresol stabilize the froth.
`rarr` The mineral like particles wet by oil and gangue particles wet by water.
`rarr` The broth is light and is skimmed off. The ore particles are then obtained from the froth.
By using depressants in froth floatation process, it is possible to separate a mixture of two suplhide ores. Eg : In the ore containing ZnS and PbBS, the deprssant used is NaCN. It prevents ZNS from coming to the froth but allows PbS to come with the froth.