Question

Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.

Answer 1

Sulphide ore of low reactivity:
Metal sulphide like $\text{HgS(s)}$ reacts with ${\text{O}}_2\left(g\right)$ to form mercuric oxide and sulphur dioxide. The reactions involved is:
$2{\text{HgS}}_4\left(s\right)+3{\text{O}}_2\left(g\right)⟶2\text{HgO}\left(s\right)+2{\text{SO}}_2$(g)

Mercuric oxide can be heated to form Hg(s) which can be refined by distillation.
$\text{HgS(s)}+2\text{HgO(s)}⟶3\text{Hg(s)}+{\text{SO}}_2\left(g\right)$

Sulphide ore of medium reactivity:
Sulphide ore lead like PbO, on roasting gives metal oxide. The reactions involved is:
$2\text{PbS}\left(s\right)+3{\text{O}}_2\left(g\right)⟶2\text{PbO(s)}+2{\text{SO}}_2\left(g\right)$

On reduction with coke in a close furnace gives metal and carbon monoxide. It is further purified by liquation.
$\text{PbO}\left(s\right)+\text{C}\left(s\right)⟶\text{Pb(s)}+\text{CO(g)}$