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Calcium Sulphate Dihydrate is also known as "natural anhydrite".
Chemical formula is CaSO4.
The molecular weight is 136.14.
CAS: 10101-41-4
MF: CaH6O5S
MW: 158.18
EINECS: 231-900-3
Synonyms
GYPSUM;c.i. 77231;CALCIUM SULFATE-2-HYDRATE;CALCIUM SULFATE SOLUTION R;CALCIUM SULFATE DIHYDRATE;CALCIUM SULPHATE 2H2O;CALCIUM SULPHATE 2-HYDRATE;CALCIUM SULPHATE DIHYDRATE
Calcium Sulphate Dihydrate is rhombic system crystal.
The relative density is 2.960, refractive index is 1.569,1.575,1.613.
Another is soluble anhydrite: melting point is 1450℃, the relative density is 2.89, refractive index is 1.505,1.548, When be incandescent, it can decompose.
Its hemihydrate is commonly known as "plaster of Paris", "plaster", Calcium Sulphate Dihydrate is white amorphous powder, relative density is 2.75.
Calcium Sulphate Dihydrate's dehydrate is commonly known as "gypsum", as a white crystal or powder, relative density is 2.32, refractive index is 1.521,1.523,1.530, when be heated to 163℃, it can lose all crystal water.
Calcium Sulphate Dihydrate is slightly soluble in water, hydrochloric acid, nitric acid, it is soluble in hot sulfuric acid, it is insoluble in alcohol.
Natural product is soluble in alkaline sulphates, sodium thiosulfate, aqueous solution of ammonium salt.
Method: Calcium Sulphate Dihydrate is derived by the reaction of CaO with SO3 under red-hot.
Soluble anhydrous gypsum is derived by CaSO4·2H2O which heated at 200℃ to constant.
Hemihydrate gypsum is derived by the calcination dehydration.
Calcium Sulphate Dihydrate is reacted by calcium chloride and ammonium sulfate.
The main purpose of calcium sulphate: natural anhydrite is used for medicine; soluble anhydrite can be used for interior decoration, Calcium Sulphate Dihydrate can also be used to prepare chemicals, beverages, etc; hemihydrate is used for construction materials, but also can be used in plaster statues, ceramics material; its dihydrate is used to product hemihydrate, fillers, etc.
Gypsum: a monoclinic mineralform of hydrated calcium sulphate,CaSO4.2H2O.
Calcium Sulphate Dihydrate occurs in five varieties:rock gypsum, which is oftenred stained and granular; gypsite, animpure earthy form occurring as asurface deposit; alabaster, a purefine-grained translucent form; satinspar, which is fibrous and silky; andselenite, which occurs as transparentcrystals in muds and clays.
Calcium Sulphate Dihydrate is usedin the building industry and in themanufacture of cement, rubber,paper, and plaster of Paris.
A mineral that consists of calcium sulfate with water molecules attached, or the rock that consists primarily of this mineral.
Calcium Sulphate Dihydrate Chemical Properties
Melting point: 128°C -1.5H₂O
Boiling point: 163°C -2H₂O
Density: 2.32
Bulk density: 400-600kg/m3
Fp: 163°C-2H₂O
Storage temp.: Store at +5°C to +30°C.
Solubility H2O: 0.01 M at 20 °C, clear, colorless
Form: powder
Color: White
Specific Gravity: 2.32
PH: 7.0 (50g/l, H2O, 20℃)(slurry)
Odor: at 100.00?%. odorless
Water Solubility: 2 g/L (20 ºC)
Sensitive: Hygroscopic
Merck: 14,1706
Solubility Product Constant (Ksp): pKsp: 4.5
Dielectric constant: 2.5（Ambient）
Exposure limits ACGIH: TWA 10 mg/m3
Stability: Stable. Incompatible with aluminium, strong acids.
InChIKey: PASHVRUKOFIRIK-UHFFFAOYSA-L
LogP: -1.031 (est)
CAS DataBase Reference: 10101-41-4(CAS DataBase Reference)
NIST Chemistry Reference: calcium sulfate(10101-41-4)
EPA Substance Registry System: Calcium sulfate dihydrate (10101-41-4)
Calcium Sulphate Dihydrate is monoclinic crystal, crystal form is clintheriform, columnar, aggregates shows dense block, fibers, flakes, earthy or kidney-shaped.
Calcium Sulphate Dihydrate is glass shiny.
Calcium Sulphate Dihydrate is slightly soluble in water and dissolved in hydrochloric acid.
Uses
Calcium Sulfate Dihydrate is obtained from gypsum, a naturally occurring compound. Also used in the preparation of calcium sulfate and calcium sulfoaluminate.
(1) Calcium Sulphate Dihydrate can be used as raw material of building materials and cement, it can also be widely used in rubber, plastics, fertilizers, pesticides, paints, textiles, food, pharmaceutical, paper, household chemicals, arts and crafts, culture and education sectors.
In the areas of absence of sulfur resource Calcium sulfate dihydrate can be used to manufacture sulfuric acid and ammonium sulfate.
Colorless and transparent gypsum can be used for optical materials.
(2) Calcium sulfate dihydrate can be used as raw material of manufacturing cement, calcium sulfate hemihydrate and sulfuric acid.
Paint and paper industry can be used as fillers.
Calcium Sulphate Dihydrate can be used as fertilizer in agriculture which can reduce the alkalinity of the soil, improve soil properties.
Food grade can be used as nutritional supplements (calcium to strengthen), coagulants, yeast food, the dough adjusting agents, chelating agents, Calcium Sulphate Dihydrate can also be used as enhancer of tomatoes, potatoes, canned organizations, hardener of brewing water, flavor-enhancer of wine, etc.
(3) Calcium sulfate dihydrate can be used as hygroscopic agent of analysis of trace nitrogen fertilizer production of carbon dioxide and carbon monoxide and carbon dioxide.
Calcium Sulphate Dihydrate can be used in paint, artificial ivory, paint, paper, dyes, printing, metallurgy, water treatment.
1.Calcium Sulphate Dihydrate is a raw material for the manufacture of cement, calcium sulfate hemihydrate and sulfuric acid.
2.Used as a filler in the paint and paper industry
3.Used as fertilizer in agriculture to reduce soil alkalinity and improve soil performance
4.Food grade can be used as a nutritional supplement (calcium strengthening), coagulant, yeast food, dough conditioner and chelating agent.
5.Used as a tissue fortifier in canned tomatoes, canned potatoes, a hardener for brewing water and a flavor enhancer for wine
Agricultural application
Mineral gypsum (CaSO4·2H20) is the most commonly used amendment for sodic and alkali soil reclamation.
Gypsum reclaims alkali soils and is thus beneficial to agriculture.
Much of the high-grade gypsum comes from the wet process phosphoric acid industry.
Given the high demand for phosphorus in the world, many industrial plants have been set up in many countries.
Calcium Sulphate Dihydrate has given rise to huge amounts of phosphogypsum waste, giving rise to disposal problems.
Mineral gypsum also poses the same problem.
Gypsum is a hydrated form of calcium sulphate (CaSO4·2H20).
Calcium Sulphate Dihydrate is a white or yellowish solid which can be ground to particle sizes from 10 to 100 mesh. Pure gypsum has 18.6% sulphur and 23.2% calcium.
A 70 to 80% pure commercial agricultural grade gypsum contains 13 to 15% sulphur, 16 to 19% calcium and varying amounts of impurities such as the oxides of iron, aluminum, calcium and magnesium.
Selenite, which is a salt of selenic acid (H2SeO3), and very similar to sulphite, is made by the oxidation of selenium by nitric acid.
The low solubility of ironselenite complexes is responsible for the non-toxic level of selenium in plants growing on acid soils having a very high total selenium content.
Plants absorb selenite, but generally to a lesser extent, than selenate, which is another form of selenium.
Production method
When natural gypsum mine removes impurity, clay is calcined and then milled together can get it.
Sodium sulfate is added into by-product (calcium chloride) of ammonia and alkali method to product alkali, the reaction product is refined to get calcium sulfate dihydrate.
Byproduct of manufacturing organic acid.
For example: The byproduct calcium oxalate is decomposed by sulfuric acid when oxalic acid is manufacturing, and then it is refined to get calcium sulfate dihydrate.
There are also open-pit mining to underground mining.
The former is the open hillside, stepped mining; the latter mining method which employs the majority of the mine shaft development or inclined to open up, and room and pillar mining method, next is comprehensive mining method.
Mining technological process sees "phosphate rock."
The vast majority of gypsum mining is used hand-selected method, some mine production is without any ore sorting, extraetedore is mined mineral.
Purification Methods
Calcium Sulphate Dihydrate loses only part of its H2O at 100-150o (see below).
Calcium Sulphate Dihydrate is soluble in H2O and very slowly soluble in glycerol.
Calcium Sulphate Dihydrate is insoluble in most organic solvents.
