Calcination is the process in which :

 Ore is heated strongly below its melting point in the presence of excess of ait and is

used for the conversion of carbonates and hydrated oxide ores to their respective oxides.

Ore is heated strongly below its melting point in the absence or limited supply of air

and is used for conversion of sulphide ores to their respective oxides

 Ore is heated strongly below its melting point either in the limited or absence of air

and is used to convert carbonates and hydrated oxide ores to their respective oxides

 Ore is heated strongly above its melting point in the limited supply of air to convert

sulphide ores to their respective oxides.