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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 ...
Biphasic calcium sulfate is a granulated powder composed of calcium sulfate hydrate (CaSO 4 •2H 2 O) and calcium sulfate hemihydrate (CaSO 4 • 1 / 2 H 2 O). [citation needed] It is used primarily as a bone grafting material in dental augmentation procedures such as socket grafting, lateral augmentation, sinus lift, cyst enucleation and more.
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 ...
While humans have been able to adapt to higher levels of concentrations with time, some effects of ingestion of sulfur water has found to have cathartic effects on people consuming water with sulfate concentrations of 600 mg/litre according to a study from the US Department of health in 1962. Some adverse effects that have been found include ...
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.
The SO 2 is absorbed in the water, and when oxygen is added reacts to form sulfate ions SO 2− 4 and free H +. The surplus of H + is offset by the carbonates in seawater pushing the carbonate equilibrium to release CO 2 gas: SO 2 + H 2 O + O →H 2 SO 4 HCO − 3 + H + → H 2 O + CO 2
Interaction of anhydrite with hydrocarbons at high temperature in oil fields can reduce sulfate (SO 2– 4) into hydrogen sulfide (H 2 S) with a concomitant precipitation of calcite. [9] The process is known as thermochemical sulfate reduction (TSR). Hand sample of gypsum and anhydrite from diapir caprock showing "chicken wire" texture.