Write the principle behind the froth floatation process. What is the role of collectors in this process ?

Froth floatation method is a method for the concentration of sulphide ores.

Sulphide ores are preferentially wetted by pine oils (having an affinity for sulphide ores) 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.

To ensure that the mineral particles are non-wetted, collectors are added. Examples of collectors are pine oil, fatty acids and xanthates. 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.