Chemical-grade limestone

Chemical-grade limestone is a pure type of high calcium or dolomitic limestone used by the chemical-process industry or where exacting chemical requirements ate necessary. It contains a minimum of 95% total carbonate. In a few areas of the United States this minimum may be extended to 97 or 98%. 

Chemical food preservation, 12 85-86 Chemical formula, defined, 21 336 Chemical fossils, 18 571 Chemical gas scavengers, 12 77 Chemical gel stabilization, 23 71 Chemical-grade limestone, 15 27 Chemical-grade propylene, product specification for, 20 1111 Chemical hazards, 21 833-846... 

Some limestones contain over 95 % CaC03. Such chemical grade materials are particularly suitable for lime production, flue gas desulfurisation and a range of other processes. The quantities involved, however, amount at most to a few percent of the total extracted. 

Chemical-grade (or -quality) limestone see high-calcium limestone. 

Properties Commercial grades Uses Manufacture White to grayish-white solid. Reacts with water to form calcium hydroxide. Commercial lime is available in lump, pebble, ground, and pulverized forms. One of the oldest commercial chemicals. Used in hundreds of applications. The most important uses are for making steel and chemicals, water treatment, pollution control, pulp and paper, and construction. Limestone (calcium carbonate, CaCOj) from mines or quarries is heated in a kiln (calcined). 

Labotka TC, Nabelek PI, Papike JJ (1988) Fluid infiltration through the Big Horse limestone member in the Notch Peak contact-metamorphic aureole, Utah. Am Mineral 73 1302-1324 Lackey JS (2000) Fluid flow in Sandstones and Marbles During Wollastonite Grade Contact Metamorphism at Laurel Mf E-Central California, MS thesis. University Wisconsin-Madison, 121 p Lasaga AC (1981) Rate laws of chemical reactions. Rev Mineral 8 1-68... 

Activities of melts prepared from reagent grade chemicals and from deactivated limestone after cycling through the continuous unit are shown in Table VIII as a function of their composition. The activity of the fresh limestone determined in the same way is also given for reference. 

More specialized grades of calcium carbonate are produced by carefully controlled chemical refinement of limestone. The most commonly employed process (28) in the U.S. involves the following ... 

Calcium carbonate (1873) (aragonite, calcite, chalk, limestone, lithographic stone, marble marl, travertine, and whiting) n. CaCOs. Grades of calcium carbonate suitable as fillers for plastics are obtained from naturally occurring deposits as well as by chemical precipitation. The natural types are prepared by dry grinding, yielding... 

It has been found that for the grinding of relatively soft materials, such as marl, the addition of high-grade hard limestone — required primarily for correction of the deficient chemical composition of the raw material — improves the performance of... 

Purer quicklime is obtained from vertical kilns. In vertical kilns limestone is fed into the top of the kiln while fuel is introduced at the bottom. Either fuel oil or natural gas is used to cook the limestone. Fuel oil usually contains enough sulfur to generate SO2 and SO3 that are trapped in the quicklime, in much the way these gases are removed from stack gases in powerplants. Natural gas is the highest grade fuel and produces high quality lime. In my opinion it is the only lime that should be used as a raw material in chemical processes where it is to become a part of a consumer product. 

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