Search results
Results from the WOW.Com Content Network
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.
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. It has many uses in industry.
Selenite, satin spar, desert rose, and gypsum flower are crystal habit varieties of the mineral gypsum.. All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO 4 ·2H 2 O. Selenite contains no significant selenium – The similar names both derive from Greek selḗnē ...
Phosphogypsum is a by-product from the production of phosphoric acid by treating phosphate ore with sulfuric acid according to the following reaction: . Ca 5 (PO 4) 3 X + 5 H 2 SO 4 + 10 H 2 O → 3 H 3 PO 4 + 5 (CaSO 4 · 2 H 2 O) + HX
The process by which this synthetic gypsum is created is also known as forced oxidation: 2 CaSO 3 + H 2 O + O 2 → 2 CaSO 4 ·2H 2 O. A natural alkaline usable to absorb SO 2 is seawater. The SO 2 is absorbed in the water, and when oxygen is added reacts to form sulfate ions SO 2− 4 and free H +.
Ammonium sulfate also is manufactured from gypsum (CaSO 4 ·2H 2 O). Finely divided gypsum is added to an ammonium carbonate solution. Calcium carbonate precipitates as a solid, leaving ammonium sulfate in the solution. (NH 4) 2 CO 3 + CaSO 4 → (NH 4) 2 SO 4 + CaCO 3
The phase composition of a particular cement can be quantified through a complex set of calculation known as the Bogue formula. To avoid the flash setting of concrete, due to the very fast hydration of the tricalcium aluminate ( C 3 A ), 2–5 wt. % calcium sulfate is interground with the cement clinker to prepare the cement powder.
Selenitic lime, also known as Scotts' cement after Henry Young Darracott Scott, is a cement of grey chalk or similar lime, such as in the Lias Group, with about 5% added gypsum plaster (calcined gypsum). [13] Selenite is a type of gypsum, but selenitic cement may be made using any form of sulfate or sulfuric acid. [18]