Question

In the froth flotation process for the purification of ores, the particles of ore float because:
A.Their surface is not easily wetted by water
B.They are light
C.They are insoluble
D.They bear electrostatic charge

Answer 1

In mineral processing, Flotation is a method used to concentrate and separate ores by altering their surfaces to a hydrophobic (fear of water) or hydrophilic (water-loving) condition i.e. the surfaces are either attracted or repelled by water.

Complete step by step answer:
Froth flotation is a process for selectively separating hydrophobic materials from hydrophilic and it is used in paper recycling, wastewater treatment industries, and mineral processing. Firstly, it was used in the mining industry. In this method, the particles of ore float because their surface is not easily wetted by water during the purification of ores due to the hydrophobic nature of their surface. It is based on the principle of wetting properties and its differences, sulfide ores are preferentially wetted or moistened by pine oil (it is used as frothier because it enhances non-wettability of the mineral particles) whereas the gangue particles or oxide are wetted or moistened by water. For example: an ore contains $ZnS$ and $PbS$ . $NaCN$ is used as a depressant and it prevents $ZnS$ from coming to froth but allows $PbS$ to come with the froth.

So, the correct answer is Option A .

Note:
It is a physical-chemical action where a mineral particle is attracted to and attaches itself to the surface of a bubble. Frothers are the chemical substance that is used to strengthen the surface tension of an air bubble.

The principle to remember is when any boat displaces a weight of water equal to its weight; it floats just like a floating object displaces a weight of fluid equal to its object. This is called a principle of flotation. So many valuable minerals are recovered because of the froth flotation method.