Caustic lime (calcium oxide, CaO)
Caustic lime (calcium oxide, CaO) is a white substance, well absorbing water. It is formed during calcination of chalk, dolomite, limestone and other minerals of calcium and magnesium type, where the share of impurities cannot exceed 6-8%. CaCO3=t>900°С=>CaO+CO2. CaO pieces with small pore size (5-10 cm) are produced by calcination of raw materials. Average density: 1600 … 1700 kg/m3. Depending on magnesium oxide content, air-hardening lime is divided into calcium (70-90% CaO and up to 5% MgO), magnesian (up to 20% MgO), highly magnesian or dolomite (20 to 40% MgO). The substance is marketed in 3 grades. Depending on the slaking time, it can be rapidly slaked (8 min); medium slaked (25 min), and slowly slaked (over 25 min). It is used in the production of cement, glass, calcium carbide, and also for producing slaked lime. In agriculture and horticulture it is used to treat plants against pests, for whitewashing of trees, as an acidic soil fertilizer. Ground limestone is a raw material in the production of feed for livestock, poultry feeding. It is used to disinfect pools, i.e. for parasite and pathogen control, for elimination of sulfur oxides from flue gases. It is an excellent softener of water, precipitating organic products and substances contained in it, and also provides neutralization of acidic natural and sewage water. In the energy field, lime pretreatment is used prior to chemical desalting of make-up water for boilers. The natural alkalinity of water is caused mainly by the presence of bicarbonate ions in chemical equilibrium with carbonic acid and carbonate ions. Lime pretreatment provides decrease in alkalinity, hardness and dry residue, removal of slurry and lightening, reduction of iron compounds, silica, organic compounds and decrease in water color index. Lump lime is shipped in bulk; powdered lime – in bulk or in paper bags according to GOST 2226. The substance is transported by any mode of transport in accordance with the applicable shipping rules.