Explain Calcination and Roasting in detail.

(N/A) There are two methods to convert concentrated ore into oxide: $(A)$ Calcination and $(B)$ Roasting.
$(A)$ Calcination: Calcination involves heating the ore in the absence of air or in a limited supply of air. This process removes volatile impurities and leaves behind the metal oxide.
$Fe_{2}O_{3} \cdot xH_{2}O_{(s)} \stackrel{\Delta}{\longrightarrow} Fe_{2}O_{3(s)} + xH_{2}O_{(g)}$
$ZnCO_{3(s)} \stackrel{\Delta}{\longrightarrow} ZnO_{(s)} + CO_{2(g)}$
$CaCO_{3} \cdot MgCO_{3(s)} \stackrel{\Delta}{\longrightarrow} CaO_{(s)} + MgO_{(s)} + 2CO_{2(g)}$
$(B)$ Roasting: In roasting,the ore is heated in a regular supply of air at a temperature below the melting point of the metal.
Some processes involving sulfide ores are:
$2ZnS + 3O_{2} \rightarrow 2ZnO + 2SO_{2}$
$2PbS + 3O_{2} \rightarrow 2PbO + 2SO_{2}$
$2Cu_{2}S + 3O_{2} \rightarrow 2Cu_{2}O + 2SO_{2}$
Copper sulfide ore is heated in a reverberatory furnace. If the ore contains iron,it is mixed with silica before heating. Iron oxide is removed as iron silicate 'slag' and copper is obtained in the form of 'copper matte' which contains $Cu_{2}S$ and $FeS$.
$FeO + SiO_{2} \rightarrow FeSiO_{3}$
The $SO_{2}$ gas produced is used in the production of $H_{2}SO_{4}$.