(N/A) There are two main methods to convert concentrated ore into oxide: $(A)$ Calcination and $(B)$ Roasting.
$(A)$ Calcination: Calcination involves heating the ore in the absence or limited supply of air. This process removes volatile impurities and leaves behind the metal oxide.
$Fe_2O_3 \cdot xH_2O(s) \xrightarrow{\Delta} Fe_2O_3(s) + xH_2O(g)$
$ZnCO_3(s) \xrightarrow{\Delta} ZnO(s) + CO_2(g)$
$CaCO_3 \cdot MgCO_3(s) \xrightarrow{\Delta} CaO(s) + MgO(s) + 2CO_2(g)$
$(B)$ 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:
$2ZnS + 3O_2 \rightarrow 2ZnO + 2SO_2$
$2PbS + 3O_2 \rightarrow 2PbO + 2SO_2$
$2Cu_2S + 3O_2 \rightarrow 2Cu_2O + 2SO_2$
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 $(FeSiO_3)$,and copper is obtained in the form of 'copper matte',which contains $Cu_2S$ and $FeS$.
$FeO + SiO_2 \rightarrow FeSiO_3$
The $SO_2$ gas produced is used in the production of $H_2SO_4$.