Explain froth floatation, with diagram.

Explanation

(i) Froth floatation method is commonly used to concentrate sulphide ore such as galena (PbS), zinc blende (ZnS) etc.
(ii) In this method, the metaalic ore particles which are perferentially wetted by oil can be separated from gangue.
(iii) In this method, the crushed ore is suspended in water and mixed with frothing agent such as pine oil, eucalyptus oil etc.
(iv) A small quantity of sodium ethyl xanthate which act as a collector is also added.
(v) A froth is generated by blowing air through this mixture.
(vi) The collector molecules attach to the ore particles and make them water repellent.
(vii) As a result, ore parrticles, wetted by the oil, rise to the surface along with the froth.
(viii) The froth is skimmed off and dried to recover the concentration ore.
(ix) The gangue particles that are preferentially wetted by water settle at the bottom.