Question

Why is pine oil used in the froth floatation method?

Answer 1

Hint: Pine oil acts as per the mechanism of soap. Soap has two parts- one is hydrophobic and other is hydrophilic. Its hydrophobic ends attach themselves to the dirt and remove it from the clothes. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the centre of the cluster.

Complete step by step solution:
> As we know that Froth floatation method is especially applied to sulfide ores, such as galena (PbS),zinc blende (ZnS) or Copper pyrites ($\text{CuFe}{{\text{S}}_{2}}$). It is based on the different wetting properties of the surface of the ore and gangue particles. The sulphide ore particles are wetted preferentially by oil and gangue particles by water. In this process, finely powdered ore is mixed with either pine oil or eucalyptus oil. It is then mixed with water. Air is blown through the mixture with a great force. Froth is produced in this process which carries the wetted ore upwards with it, Impurities (gangue particles) are left in water and sink to the bottom from which they are drawn off.
> The role of the oil is to create foam (or froth) with air. Other frothing agents include xanthates, fatty acids with sulfide ores. This oil acts as a hydrophobic agent and forms froth with hydrophobic impurities because it does not have affinity towards water (because of the hydrophobic chemicals as its constituents) and it attracts impurities which can be washed away leaving behind the concentrated mineral.
So, pine oil is used in froth floatation methods to purify sulfide ores to remove the dirt leaving behind the cleaned ores.

Note: We should know why pine oil is hydrophobic in nature. Pine oil is an essential oil obtained by the steam distillation of needles, twigs and cones from a variety of species of pine. Chemically, pine oil consists mainly of cyclic terpene alcohols. It may also contain terpene hydrocarbons, ethers and eaters due to which its hydrophobicity increases.