Question

Explain the froth floatation method with a neat labelled diagram.

Answer 1

1. The froth floatation process is based on two opposite properties of the particles, hydrophilic and hydrophobic.
2. The metal sulphide particles are hydrophobic. Due to this property, they get wetted mainly with oil. On the other hand, gangue particles are hydrophilic and get wetted by water.
3. In this method, the finely divided metal ore is added in a big tank containing large amount of water. To this, certain vegetable oil (pine oil, eucalyptus oil, etc.) is added for the formation of froth.
4. In the tank, compressed air is circulated through the water. Bubbles are formed due to this blown air. A rotating agitator at the centre of the floatation tank agitates the mixture and draws air into it to form bubbles. As a result, foam is formed which carries metal sulphide particles. The foam rises to the surface of water and floats. Therefore, this method is called froth floatation process.
5. This method is used to separate metal sulphide ores such as zinc blende (ZnS) and copper pyrite (CuFeS₂).

Froth floatation method