Question

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

Answer 1

We need to understand the process of froth flotation used in the concept of metallurgy. Metallurgy is the science of production and purification of metals. In the mining of minerals, unwanted material surrounds or mixed with the ore deposit is known as gangue. Froth flotation is a process by which the minerals are separated from the gangue where the minerals are collected from the froth and the gangue and impurities are settled at the bottom.

Complete answer:
We can discuss the principle behind the froth flotation process as the basic principle of the froth flotation process is that the ore containing the impurities and the mineral are crushed into fine powder and mixed with water. If the minerals of interest are hydrophobic in nature, they get attracted to the froth and the impurities are wetted by water. When air is passed through the mixture, the hydrophobic mineral particles are carried with the air bubbles and are floating at the surface, thereby forming a froth which can be removed. The hydrophilic impurities stay in the liquid phase with the water.
Now we can discuss the role of collectors in this process: Several chemicals are used in the process of froth flotation and to achieve optimized quality of the mineral of interest. One of them is the collector chemical which is an organic compound which attaches itself to the mineral particles in such a way that the mineral of interest along with the collector becomes a water repellent or hydrophobic compound which is easily passed into the froth and can be collected. These collectors are basically oils or soaps which can either be cationic, anionic or nonionic depending on the extent of hydrophobicity of the mineral of interest. Some examples of collectors are kerosene oil, ethyl xanthate, salts of linoleic acid and oleic acid (soaps), etc.

Note:
It must be noted that the froth flotation process is widely used for the purification of sulphide ores. The sulphide ores are wetted collector oils and the impurities are wetted by water. The collector used for sulphide ores is pine oil which wets the sulphide particles and the gangue particles are settled at the bottom. It is basically the selective separation of hydrophobic minerals from hydrophilic impurities.