Give examples to differentiate roasting and calcination.

Explanation

Roasting: In roasting, the ore is heated in a regular supply of air in a furance, at a temperature, below the melting point of the metal.
The ore loses sulphur as its oxide leaving bëhind-oxide of the metal. Roasting is done in reverberatory or blast furnace. :
`2ZnS+3O_(2) to 2ZnO+2SO_(2)`
`2PbS+3O_(2) to 2PbO+2SO_(2)`
Calcination : Calcination involves heating of the ore in the absence of air just below its fusion temperature. Volatile matter escapes leaving behind the metal oxide, Calcination makes the ore porous and is made in reverberatory furnace.
`Fe_(2)O_(3).xH_(2)O(s) overset(Delta)to Fe_(2)O_(3)(s)xH_(2)O(g)`
`ZnCO_(3)(s) overset(Delta)to ZnO(s)+CO_(2)(g)`
`CaCO_(3). MgCO_(3)(s) overset (Delta) to CaO(s)+MgO(s)+2CO_(2)(g)`