Calcination : It is a process in which the ore is heated to a high temperature below the melting point of meteal in absence of air or limited supply of air.
The changes that take place capcination with reactions are :
(a) Moisture and water from hydrated ores, volatile impurities and organic matter are removed.
(b) Ore becomes porous.
(c) Carbonates decompose to oxides.
`ZnCO_(3)overset(Delta)toZnO+CO_(2)`
`CuCO_(3)overset(Delta)toCuO+CO_(2)`
`CaCO_(3)overset(Delta)toCaO+CO_(2)`
`underset("(Dolomite)")underset()(CaCO_(3),)MgCO_(2)overset(Delta)toCaO+MgO+2CO_(2)`
`2Fe_(2)O_(3)*3H_(2)Ooverset(Delta)to2Fe_(2)O_(3(s))+3H_(2)O`
