Manufacture of lime (CaO) from limestone (CaCO3)
CaC03 + heat → CaO + CO2
Manufacture of solid calcium hydroxide (slaked lime)
CaO + H20 ---> Ca(OH)2 + heat
Uses of quicklime (CaO):
making steel from iron, to neutralise acidity in soil, a drying agent in industry
Uses of slaked lime (calcium hydroxide):
neutralise acidity in soil, and in lakes affected by acid rain, neutralising acidic industrial waste products, e.g. flue gas desulphurisation, made by adding CaO to water.
Uses of calcium carbonate (limestone):
making cement – made by mixing limestone with clay, heating the mixture strongly in a kiln like the one below, adding gypsum (calcium sulphate), and grinding up the final solid to give a powder.
Making iron from iron ore – the limestone reacts with (neutralises) sand (an impurity) forming slag (calcium silicate), which is then used for road building.