Question

What is a concentration of ores? Explain the process with diagram by which metallic ore with sulphide as an impurity is purified.

Answer 1

1. The ores are concentrated on the basis of the type of impurities and their percentage proportions. As a result, most of the impurities are removed and the proportion of the ore is increased. This process is called concentration of the ore. For this, (i) concentration or centrifugation on the basis of difference in densities (ii) froth floatation and (ii) magnetic separation methods are used.

2. Froth floatation method is used for concentration of the ores of the metals whose ores are in sulphide form. The concentration of sulphide ores of copper, lead and zinc metal are carried out by this method. In this method, the fine powder of the ore, and water are filled in a big vessel. Substances like pine or turpentine oil are added to it.
3. The sulphide particles of the metals get wet and stick to it, while clay, particles of sand, do not get wet. In this liquid mixture, air is passed with pressure through a tube. Hence, the froth is produced around the light particles of the liquid mixture. Heavy particles like clay, sand etc. become wet by water and settle down at the bottom

4. The sulphide ore of metal is removed with sieves in a second vessel and washed with water. By this method, ores like copper pyrites are concentrated and clay, sand etc. are removed.