Question

Froth floatation process for the concentration of ores is an illustration of physical phenomenon of:
A.Adsorption
B.Absorption
C.Coagulation
D.Sedimentation

Answer 1

Hint:Wetting of ore particles by oil and wetting of gangue particles by water means accumulation of oil and water particles on the surface of ore and gangue particles respectively in the Froth floatation process of concentration of ore.

Complete step by step answer:
The removal of impurities from the ore in order to increase concentration of metal content is known as concentration of ore. In the case of froth floatation method for concentration of ore, this method is mainly employed or used for the concentration of sulphide ore. This method is based on the different wetting characteristics of the gangue or impurities and the sulphide ore with water and oil. The gangue preferentially wetted by water and the ore by oil. Here water or oil adsorbs on gangue or sulphide ore. So it is based on adsorption phenomenon. In this, crushed ore along with water is taken in a floatation cell. Various substances are added depending on the nature of the ore and a current of air is blown in too. The substances added are Frothers which generate a stable froth rises to the top of tank, Collectors are added as they attach themselves by polar group to the grains of the ores which then become water repellant and pass on into the froth, Depressant are added as these activate or depress the floatation property and help in separation of different sulphide ore present in mixture.
On the other hand, concentration of ore can also be done by levigation method. This method is based on the difference in the specific gravities of the ore and the gangue particles. Powdered ore is agitated with a running stream of water. The lighter gangue particles are taken away by water while heavier ore particles settle down. So, the levigation method is based upon the sedimentation phenomenon.

Thus, the correct option is A.

Note:
Adsorption involves higher concentration of gas or liquid at the surface of a substance. It is a surface phenomenon. On the other hand, absorption involves uniform distribution of molecular species throughout the bulk. Thus absorption is a bulk phenomenon.