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Lime is a calcium-containing inorganic material in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide or calcium hydroxide. It is also the name of the natural mineral (native lime) CaO which occurs as a product of coal seam fires and in altered limestone xenoliths in volcanic ejecta.〔(Lime in Handbook of Mineralogy )〕 The word "lime" originates with its earliest use as building mortar and has the sense of "sticking or adhering."〔http://www.etymonline.com/index.php?term=lime〕 These materials are still used in large quantities as building and engineering materials (including limestone products, concrete and mortar) and as chemical feedstocks, and sugar refining, among other uses. Lime industries and the use of many of the resulting products date from prehistoric periods in both the Old World and the New World. Lime is used extensively for waste water treatment with ferrous sulfate. The rocks and minerals from which these materials are derived, typically limestone or chalk, are composed primarily of calcium carbonate. They may be cut, crushed or pulverized and chemically altered. "Burning" (calcination) converts them into the highly caustic material ''quicklime'' (calcium oxide, CaO) and, through subsequent addition of water, into the less caustic (but still strongly alkaline) ''slaked lime'' or ''hydrated lime'' (calcium hydroxide, Ca(OH)2), the process of which is called ''slaking of lime''. When the term is encountered in an agricultural context, it probably refers to agricultural lime. Otherwise it most commonly means slaked lime, as the more dangerous form is usually described more specifically as quicklime or ''burnt lime''. ==Lime production process== Limestone in the lime industry is a general term for rocks that contain eighty percent or more of calcium or magnesium carbonates including marble, chalk, oolite, and marl. Further classification is by composition as high calcium, argillaceous (clayey), silicious, conglomerate, magnesian and other limestones, and dolomite〔(Lazell, Ellis Warren. ''Hydrated lime; history, manufacture and uses in plaster, mortar, concrete; a manual for the architect, engineer, contractor and builder..'' Pittsburgh: Jackson-Remlinger Printing Co., 1915. 21. Print. )〕 Uncommon sources of lime are coral, sea shells, calcite, and ankerite. Limestone is extracted from quarries or mines. Part of the extracted stone, selected according to its chemical composition and granulometry, is calcinated at about in different types of lime kilns to produce quicklime according to the reaction: CaCO3 + heat → CaO + CO2. Before use, quicklime is hydrated, that is combined with water, called slaking so hydrated lime is also known as slaked lime, and is produced according to the reaction: CaO + H2O → Ca(OH)2. ''Dry slaking'' is when quicklime is slaked with just enough water to hydrate the quicklime but remain as a powder and is referred to as hydrated lime. In ''wet slaking'' enough water, but not too much, is added to hydrate the quicklime and form a putty referred to as lime putty. Because lime has an adhesive property with bricks and stones, it is often used as binding material in masonry works. It is also used in whitewashing as wall coat to adhere the white wash onto the wall. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lime (material)」の詳細全文を読む スポンサード リンク
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