Question

Generally sulphide ores are concentrated by which of the following process?
A) Handpicking
B) Washing with water
C) Leaching
D) Froth flotation.

Answer 1

Hint: Sulphide ores are typically concentrated using a method that distinguishes materials depending on whether they are water repellent (hydrophobic) or have a preference for water (hydrophilic). Surface adsorption is the process that takes place.

Complete step-by-step answer:
A) Handpicking: Hand-picking is not possible as it will be difficult for us to detect the impurities from the ore with our bare eyes and complete removal of impurities is impossible because of human errors. Hence, this option is incorrect.
B) Washing with water: Washing with water is manual work that doesn’t guarantee the complete removal of impurities from the ore. Hence, this option is incorrect
C) Leaching: Leaching concentrates gold and silver ores. In this process, we treat the ore with a reagent that is soluble for the ore but not for the impurities. But in sulphide ores, the impurities can be soluble with the reagent as it is soluble in water too. Hence, this option is incorrect.
D) Froth flotation: The variation in the wetting properties of the ore and gangue particles with water and oil is the basis for the froth floatation process. This process is used for metals whose ore is best wetted by oil and whose gangue is best wetted by water. The oil preferred to wet the sulphide ores, and the gangue settled to the bottom of the tank with the water.

Thus the correct answer is option ‘D’.

Note: Pine oil is used in the froth floatation process because it attracts impurities from the ore. Pine oil is therefore hydrophobic due to its chemical components, which are cyclic terpene alcohols, which reduces its affinity for water.