Question

(i) What is meant by concentration of ores?
(ii) Name the process of concentration,
(a) based on densities
(b) based on magnetic nature
(iii) How an ore is concentrated by froth flotation process?

Answer 1

(i) The method of removing gangue particles from the ore to the maximum possible extent is called the concentration or dressing of the ore.

(ii) The concentration processes used on the basis of:
(a) densities – gravity separation method
(b) magnetic nature – magnetic separation method

(iii) Froth flotation process – This process is used to concentrate sulphide ores. It depends on the preferred wetting of the ore and gangue particles. Here, powdered ore particles are taken in a large tank containing water and some oils. The ore particles are wetted by oil and the gangue particles, by water. The mixture is stirred up by compressed air. This allows the ore particles that are wetted by oil to produce froth and come to the surface. These ore particles along with froth are then scraped out.