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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 .
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.
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).
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 ...
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.
About 2.2:1 is the ratio (by weight) for compounding sulfur and quicklime; this makes the highest proportion of calcium pentasulfide. If calcium hydroxide (builders or hydrated lime) is used, an increase by 1/3 or more (to 115 g/L or more) might be used with the 192 g/L of sulfur. If the quicklime is 85%, 90%, or 95% pure, use 101 g/L, 96 g/L ...
For sodium sulfate, 250 to 500 mg/litre, with calcium sulfate at 250 to 1000 mg/litre and magnesium sulfate at 400 to 600 mg/litre. A study by Zoeteman found that having 270 mg of calcium sulfate and 90 mg of magnesium sulfate actually had improved the taste of the water.
Bassanite is a calcium sulfate mineral with formula CaSO 4 · 1 / 2 H 2 O or 2CaSO 4 ·H 2 O. In other words it has half a water molecule per CaSO 4 unit, hence its synonym calcium sulfate hemihydrate. Bassanite was first described in 1910 for an occurrence on Mount Vesuvius. It was named for Italian paleontologist Francesco Bassani ...