Most lime is the natural chemical oxide (CaO), which is commonly referred to as lime, or quicklime. The name quicklime comes from an old meaning of "quick" as in alive or lively, since quicklime reacts vigorously with water. Quicklime is produced by roasting limestone in kilns like the one in the image above. Quicklime resembles white pebbles and is usually produced in sizes ranging from 0.3 to 4.5 cm.
Slaked lime is formed from reaction of quicklime with water. Quicklime reacts with water to form calcium hydroxide [Ca(OH)2]. Slaked lime is a fluid mixture of calcium hydroxide and water formed by mixing 1 part of quicklime with about 4 parts of water. Users of lime usually produce this mixture themselves in equipment called lime slakers. Slaked lime resembles a milk shake and is sometimes called "milk of lime."
Reagent grade limestone is crushed high calcium limestone that does not require roasting. It can be used in some applications as a substitute for quicklime and the gasification or burning of high sulphur fuels such as petcoke.
Current demand for Quicklime is estimated at 100,000 tonnes per year, mainly for boiler water treatment
Beginning 2008, an additional 80,000 tonnes per year required for flue gas desulphurization.
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