Question

What is the difference between calcination and roasting.

Answer 1

Calcination	Roasting
The ore is heated in the absence of air or in a limited supply of air. It involves thermal decomposition of carbonate ores. Carbon dioxide is given out during calcination. ${\mathrm{ZnCO}}_3\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{ZnO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right)$	The ore is heating in the presence of air or oxygen. It carried out mostly for sulphides ores. Metallic and acidic compounds are released during roasting. $2\mathrm{ZnS}\left(\mathrm{s}\right)+3{\mathrm{O}}_2\left(\mathrm{g}\right)\stackrel{∆}{\to }2\mathrm{ZnO}\left(\mathrm{s}\right)+2{\mathrm{SO}}_2\left(\mathrm{g}\right)$