Question

Explain froth flotation process of copper pyrites.

Answer 1

Copper is extracted from copper pyrites by froth flotation process.

Froth flotation method is used to separate particles based on the differences in the ability of air bubbles to selectively attach to specific mineral surfaces in a mineral-water slurry. A finely crushed ore is suspended in water and a blast of air is passed through the suspension. The wet particles to which air bubbles are attached float as a froth which is skimmed, whereas the particles to which air bubbles are not attached gets heavy and sink to the bottom.

Copper is extracted from its principle ore Copper pyrites $CuFe{S}_2$. The ore is concentrated by froth flotation process. The concentrated ore is then roasted in a furnace where reactions remove sulphur and Arsenic gases-

$S+O_2\to S{O}_2$ and $4As+3O_2$$⟶$$2A{s}_2{O}_3$

And then the copper pyrite gets converted to a mixture of $C{u}_{2}S$ and $FeS$ by the following reactions.

$2CuFe{S}_2+O_2$ $⟶$ $C{u}_{2}S+2FeS+S{O}_2$

These Sulphides are then oxidized and by smelting them, copper is extracted successfully.