Environmental protection is one of the most relevant application areas of lime (calcium oxide and calcium hydroxide).
In this field Calcium Oxide and Hydroxide are used for the treatment of waste waters to control the pH, to retain heavy metals by precipitation or for its flocculant capacity.
Lime also stabilizes sludge and heavy metals present in certain industrial residues and to make these residues more manageable.
In flue-gases treatment, Calcium Hydroxide is used as dry powder or as milk of lime to neutralize the emissions of sulphur dioxide, hydrochloric acid, fluorhydric acid or dioxins, consequently avoiding the emission of these pollutants into the atmosphere. This material is obtained by hydration of calcium oxide (quicklime) in equipment called hydrators or as a by-product from calcium waste from manufacturing processes of various substances, by precipitation of the mixture of a calcium chloride solution with a sodium hydroxide solution or by reacting calcium carbide with water.
In addition, the water generated in treatment plants by the desalination of seawater requires post-treatment to improve both flavor and chemical quality. At this stage of water treatment in desalination plants lime is used as a post-treatment reagent which is supplied in the form of hydroxide (Ca(OH)2) to make milk of lime.