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Calcium sulfate (or calcium sulphate) is the inorganic compound with the formula CaSO 4 and related hydrates. In the form of γ- anhydrite (the anhydrous form), it is used as a desiccant . One particular hydrate is better known as plaster of Paris , and another occurs naturally as the mineral gypsum .
The necessary additional calcium is provided by the calcium hydroxide and calcium silicate hydrate in the cement paste; The effect of these changes is an overall loss of concrete strength. The above effects are typical of attack by solutions of sodium sulfate or potassium sulfate. Solutions containing magnesium sulfate are generally more ...
Sulfates and sulfites are ubiquitous in the natural environment and are present from many sources, including gypsum (calcium sulfate) often present as an additive in 'blended' cements which include fly ash and other sources of sulfate. With the notable exception of barium sulfate, most sulfates are slightly to highly soluble in water.
Phosphogypsum (PG) is the calcium sulfate hydrate formed as a by-product of the production of fertilizer, particularly phosphoric acid, from phosphate rock. It is mainly composed of gypsum (CaSO 4 ·2H 2 O).
Calcium is a chemical element; ... and calcium sulfate (CaSO 4) are particularly abundant minerals. ... Because of concerns for long-term adverse side effects, ...
Other common desiccants include activated charcoal, calcium sulfate, calcium chloride, and molecular sieves (typically, zeolites). Desiccants may also be categorized by their type, either I, II, III, IV, or V. These types are a function of the shape of the desiccant's moisture sorption isotherm. Alcohols and acetones are also dehydrating agents.
Calcium sulfite, or calcium sulphite, is a chemical compound, the calcium salt of sulfite with the formula CaSO 3 ·x(H 2 O). Two crystalline forms are known, the hemihydrate and the tetrahydrate, respectively CaSO 3 ·½(H 2 O) and CaSO 3 ·4(H 2 O). [2] All forms are white solids. It is most notable as the product of flue-gas desulfurization.
Crystals of calcium sulfate or calcium fluoride are doped with dysprosium. When these crystals are exposed to radiation, the dysprosium atoms become excited and luminescent. The luminescence can be measured to determine the degree of exposure to which the dosimeter has been subjected. [10]