CBSE Class 10 Answered

Roasting is a metallurgical process involving gas-solids reactions at elevated temperatures. A common example is the process in which sulfide ores are converted to oxides, prior to smelting.

CuS + 1.5O₂ → CuO + SO₂

Calcination  is a thermal treatment process applied to ores and other solid materials in order to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials. Calcination is to be distinguished from roasting, in which more complex gas-solid reactions take place between the furnace atmosphere and the solids; however, calcination takes place in the absence of air.

CaCO₃ = CaO + CO₂; 848°C