give defination with examples a)calcination b)roasting

a)Calcination :-Calcination is a thermal treatment process in presence of air or oxygen applied to ores and other solid materials 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
. For example, in limestone calcination, a decomposition process, the chemical reaction isCaCO3 → CaO + CO2(g)

b)Roasting:-Roasting consists of thermal gas–solid reactions, which can include oxidation, reduction, chlorination, sulfation, and pyrohydrolysis. In roasting, the ore or ore concentrate is treated with very hot air. This process is generally applied to sulphide minerals. During roasting, the sulfide is converted to an oxide, and sulfur is released as sulfur dioxide, a gas. For the ores Cu2S (chalcocite) and ZnS (sphalerite), balanced equations for the roasting are:

2 Cu2S + 3O2 → 2 Cu2O + 2 SO2
2 ZnS + 3 O2 → 2 ZnO + 2 SO2