calcination (kălˌsənāˈshən) [key], in metallurgy, process of heating solid material to drive off volatile chemically combined components, e.g., carbon dioxide. It is sometimes a step in the extraction of metals from ores. Calcination is distinguished from drying, in which mechanically held water is driven off by heating, and from roasting, in which a material is heated in the presence of air to oxidize impurities. Originally calcination meant the method of obtaining lime (calcium oxide) from limestone by heating it to drive off carbon dioxide.
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