What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?

Sulphide ores are preferentially wetted by oils while the gangue is preferentially wetted by water .The ore particles get adsorbed on oil droplets and come to the surface where they can be collected as froth gangue is wetted by water and gets settled down. Eg. It is done for PbS ores.

Here, in this froth floatation process, low grade sulphide ores are concentrated by separating them from earthly and silicious (containing silicon) matter. Here, pine oil is used as the frothing agent. The sulphide ore is shaken with pine oil and water, the ore particles are adsorbed on froth that floats and the gangue particles settle down as discussed earlier.

Thus, role of adsorption in froth floatation process can be understood as following processes.

(i) Adsorption of pine oil on sulphide ore particles.

(ii) Formation of emulsion takes place.

(iii) Froth is formed along with ore particles.

(iv) As sulphide are extracted using froth floatation method therefore, only sulphide ore particles will show these type of adsorbing tendency. It is showing shape selective catalysis.