Calcination is thermal decomposition of a material.  Examples include decomposition of hydrates such as ferric hydroxide to ferric oxide and water vapor, the decomposition of calcium carbonate to calcium oxide and carbon dioxide as well as  iron carbonate to iron oxide:
:CaCO  →  CaO  +  CO
Calcination processes are carried out in a variety of furnaces, including shaft furnaces, rotary kilns, and fluidized bed reactors.