E516 CALCIUM SULPHATE

E516 Calcium sulphate commonly occurs in several hydrated forms, including gypsum and plaster of Paris.
E516 Calcium sulphate occurs naturally as the mineral gypsum (CaSO₄·2H₂O).
E516 Calcium sulphate is less soluble than calcium chloride but more soluble than calcium carbonate.

CAS Number: 99400-01-8
Molecular Formula: CaO4S
Molecular Weight: 136.14

Synonyms: E516 Calcium sulphate, 7778-18-9, Anhydrous gypsum, Drierite, Karstenite, Muriacite, calcium sulphate, Basic E516 Calcium sulphate, E516 Calcium sulphate, anhydrous, E516 Calcium sulphate anhydrous, Crysalba, Osteoset, Thiolite, Anhydrous sulfate of lime, Natural anhydrite, Sulfuric acid, calcium salt (1:1), Anhydrous E516 Calcium sulphate, Oparex 10, Calmatrix, GIBS, Franklin Fiber H 45, SSS-A, Calcarea sulphurica, Dead-burned gypsum, Insoluble anhydrite, Raddichem 27, E516 Calcium sulphate (1:1), E516 Calcium sulphate (CaSO₄), Denka sigma 1000, CAS 20, Shigao, Calcii sulfas, Calcarea sulphurica 30C, Stone paste, Calcium sulphate anhydrous, Anhydrous sulphate of lime, Shi gao, Sulfuric acid calcium salt (1:1), Calcium sulphate, anhydrous, INS No. 516, Calcium (as sulfate), CI 77231, Native calcium sulphate, INS-516, E934B3V59H, NSC-529649, Precipitated calcium sulphate, CALCIUM SULPHATE ANHYDROUS (E516), E-516, CHEBI:31346, E516 Calcium sulphate (1:1) dihydrate, SULFURIC ACID CALCIUM(2+) SALT (1:1), 231-900-3, Calcium salt of sulfuric acid, Calc Sulph, Gypsum, Dental, Calcarea Sulfurica, Calc Sulph 3X, Calc Sulph 6X, Calc Sulph 12X, Calc Sulph 14X, Calc Sulph 30X, Calc Sulph 200X, CALCAREA SULPH, Artificial Dental Stone, TONICPET 3, Dental Stone, Artificial, Stone, Artificial Dental, RefChem:917892, Calcarea Sulphurica 200CK, Calcarea Sulphurica 8003, E516 Calcium sulphate, unspecified, WAT0DDB505, CALCAREA SULFURICA 6X, CALCAREA SULPHURICA 6X, SULFURIC ACID CALCIUM SALT, Bestmade Natural Products Calc Sulph, D-123, 604-615-0, Anhydrite, calcium;sulfate, CaSO₄, Sulfuric acid, calcium salt, E516 Calcium sulphate, Anhydrous, Puratronic (Metals Basis), E516 Calcium sulphate [NF], Drierite, regular 8 mesh, MFCD00010912, E516 Calcium sulphate (NF), Calcium sulfuricum, 99400-01-8, Caswell No. 152, Calcium sulphate, natural, CCRIS 3666, HSDB 902, EINECS 231-900-3, EPA Pesticide Chemical Code 005602, NSC 529649, Plaster of Paris, anhydrite, Kalziumsulfat, A 30, calcium sulfat, UNII-E934B3V59H, AI3-02330, E516 Calcium sulphate FCC, CaO₄S, Regular drierite 6 mesh, E516 Calcium sulphate Submicron, E516 Calcium sulphate nanopowder, Drierite, regular 4 mesh, E516 Calcium sulphate-325 mesh, Drierite commercial 4 mesh, Drierite commercial 6 mesh, Drierite commercial 8 mesh, Indicating drierite 8 mesh, EC 231-900-3, SCHEMBL4120, Drierite, indicating 4 mesh, E516 Calcium sulphate [MI], Drierite, indicating 6 mesh, Drierite commercial 200 mesh, E516 Calcium sulphate [HSDB], CHEMBL2106140, Drierite, regular 10–20 mesh, Drierite, regular 20–40 mesh, DTXSID9029699, Drierite with indicator, 4 mesh, Drierite with indicator, 6 mesh, Drierite with indicator, 8 mesh, Indicating drierite 10–20 mesh, CALCAREA SULPHURICA [HPUS], Drierite without indicator, 4 mesh, Drierite without indicator, 6 mesh, Drierite without indicator, 8 mesh, Drierite commercial 10–20 mesh, Drierite commercial 20–40 mesh, AKOS015902936, E516 Calcium sulphate ANHYDROUS [II], DB15533, E516 Calcium sulphate, UNSPECIFIED FORM, Drierite with indicator, 10–20 mesh, Drierite without indicator, 20–40 mesh, DB-230081, Drierite without indicator, 10–20 mesh, NS00074390, E516 Calcium sulphate with cobalt chloride indicator, Drierite® indicating (CaSO₄), Lab Grade, D09201, USP Solution E516 Calcium sulphate TS, F545124, Q407258, E516 Calcium sulphate, Anhydrous, Puratronic (Metals Basis), PubChem, E516 Calcium sulphate;E516 Calcium sulphate Fcc;E516 Calcium sulphate for tofu;(2-Bromo-5-methoxy-59-methyl-phenyl)-methano

E516 Calcium sulphate deposits form through evaporation of sulfate-rich waters.
Large gypsum and anhydrite deposits are associated with evaporite formations.
These deposits provide valuable information about ancient climate and marine conditions.

E516 Calcium sulphate is chemically neutral and does not significantly alter pH in solution.
This neutrality distinguishes it from many other calcium salts.
As a result, it is compatible with a wide range of chemical and biological systems.

Thermally, gypsum loses water in stages upon heating.
The first dehydration step forms hemihydrate, followed by complete dehydration to anhydrite.
These controlled phase changes are critical in industrial processing and materials design.

E516 Calcium sulphate also exhibits good compatibility with organic and inorganic additives.
This allows modification of setting time, strength, and microstructure.
Such control is essential in construction, biomedical, and specialty material applications.

When partially dehydrated, it forms E516 Calcium sulphate hemihydrate (CaSO₄·½H₂O), commonly known as plaster of Paris.
The anhydrous form (CaSO₄) is also found in nature as the mineral anhydrite.

Physically, E516 Calcium sulphate is a white to colorless solid.
E516 Calcium sulphates solubility in water is relatively low compared to many other sulfate salts.

Solubility varies depending on temperature and degree of hydration.
Chemically, E516 Calcium sulphate is stable under normal environmental conditions.
It does not readily decompose and is non-volatile.

In aqueous systems, it dissociates slightly into calcium and sulfate ions.
E516 Calcium sulphate can be produced industrially from natural gypsum or as a by-product of chemical processes.
E516 Calcium sulphate is also formed during flue gas desulfurization in power plants.

E516 Calcium sulphate occurs in several hydrated forms; the anhydrous state (known as anhydrite) is a white crystalline solid often found in evaporite deposits. 
Its dihydrate form is the mineral gypsum, which may be dehydrated to produce bassanite, the hemihydrate state. 
Gypsum occurs in nature as crystals (selenite) or fibrous masses (satin spar), typically colorless to white, though impurities can impart other hues. 

All forms of E516 Calcium sulphate are sparingly soluble in water and cause permanent hardness when dissolved therein.
E516 Calcium sulphate is an inorganic compound with the chemical formula CaSO₄.
It consists of calcium cations (Ca²⁺) and sulfate anions (SO₄²⁻) arranged in an ionic crystal lattice.

E516 Calcium sulphate is a grayish-white dense powder that occurs in nature in both an anhydrous form (anhydrite) and hydrated form(gypsum); it is also the byproduct of many chemical reactions. 
E516 Calcium sulphate has many industrial uses;for example, as a source of sulfur and sulfuric acid,in cements, tiles and plaster,as a soil conditioner, in paints, dyes,and polishes, and as a food additive.E516 Calcium sulphate.
E516 Calcium sulphate is an inorganic salt with the chemical formula CaSO

E516 Calcium sulphate controlled dehydration and rehydration processes allow conversion between its hydrated forms.
E516 Calcium sulphate is widely studied in materials science, geology, and environmental chemistry.
Its phase transformations between gypsum, hemihydrate, and anhydrite are well characterized.

These transformations are important for both natural geological processes and industrial applications.
E516 Calcium sulphate shows distinct physical and structural properties depending on its hydration state.
Gypsum contains two water molecules per formula unit, while plaster of Paris contains half a water molecule and anhydrite contains none.

These differences strongly affect hardness, reactivity with water, and mechanical strength.
When E516 Calcium sulphate hemihydrate is mixed with water, it undergoes an exothermic hydration reaction.
This reaction reforms gypsum and causes the material to set and harden.

This setting behavior is the basis for its widespread use in casting and construction materials.
In aqueous environments, E516 Calcium sulphate exhibits limited solubility and establishes a dissolution–precipitation equilibrium.
This equilibrium plays an important role in controlling water hardness and scaling.

Melting point: >300°C
storage temp.: Hygroscopic, Room Temperature, under inert atmosphere
solubility: Water (Slightly)
form: Solid
color: Off-White to Pale Grey
Water Solubility: 2.4g/L
Solubility Product Constant (Ksp): pKsp: 4.31
Dielectric constant: 5.6（0.0℃

E516 Calcium sulphate plays a role in soil chemistry and agriculture.
It supplies both calcium and sulfur, which are essential plant nutrients.
Unlike lime, it improves soil structure without significantly changing soil pH.

Industrially, E516 Calcium sulphate is valued for its predictable hydration and dehydration behavior.
The ability to control setting time and mechanical strength through additives is critical.
This tunability supports its use across construction, medical, and specialty material sectors.

Environmentally, E516 Calcium sulphate is stable and non-toxic.
E516 Calcium sulphate occurs naturally and participates in the global sulfur cycle.
Its presence in sediments and rocks helps scientists interpret past environmental conditions.

The main use of E516 Calcium sulphate is to produce plaster of Paris and stucco. 
These applications exploit the fact that E516 Calcium sulphate which has been powdered and calcined forms a moldable paste upon hydration and hardens as crystalline E516 Calcium sulphate dihydrate. 
E516 Calcium sulphate is also convenient that E516 Calcium sulphate is poorly soluble in water and does not readily dissolve in contact with water after its solidification.

E516 Calcium sulphate occurs at three levels of hydration with different crystallographic structures: anhydrous, dihydrate, and hemihydrate.
The anhydrous CaSO4 (anhydrite) crystallizes as an tightly-bound orthohombic lattice with space group Pnma, in which each Ca2+ is 8-coordinated, or surrounded, by 8 oxygen atoms from tetrahedral SO2−4. 
It is similar in topology to zircon.

The dihydrate CaSO4·2H2O (gypsum) forms a monoclinic crystal with space group C2/c. 
Its structure consists of alternating layers: one with Ca2+ coordinated with tetrahedral SO2−4 and another with interstitial water molecules.
E516 Calcium sulphate has a long history of use in dentistry.

E516 Calcium sulphate has been used in bone regeneration as a graft material and graft binder (or extender) and as a barrier in guided bone tissue regeneration. 
E516 Calcium sulphate is a biocompatible material and is completely resorbed following implantation.
E516 Calcium sulphate does not evoke a significant host response and creates a calcium-rich milieu in the area of implantation.

E516 Calcium sulphate has a relatively low solubility in water, which is unusual among sulfate salts.
Its solubility slightly decreases as temperature increases, a behavior known as retrograde solubility.
This characteristic is important in scaling phenomena in boilers, heat exchangers, and desalination systems.

In natural waters, E516 Calcium sulphate contributes to permanent hardness.
Unlike temporary hardness caused by bicarbonates, sulfate-related hardness cannot be removed by boiling.
This makes E516 Calcium sulphate relevant in water treatment and industrial water management.

From a crystallographic standpoint, E516 Calcium sulphate forms well-defined crystal structures.
Gypsum crystals often grow as tabular or prismatic forms, sometimes producing large, transparent crystals known as selenite.
These crystal habits are studied in mineralogy and crystal growth research.

In biological and biomedical contexts, E516 Calcium sulphate is considered biocompatible.
It can dissolve gradually in physiological fluids, releasing calcium ions.
This property makes it suitable for temporary biomedical applications where resorption is desired.

Uses Of E516 Calcium sulphate:
E516 Calcium sulphate is used in medical and biomedical applications.
Plaster of Paris is used for orthopedic casts, molds, and dental impressions.
E516 Calcium sulphate pellets are also used as temporary bone fillers due to their biocompatibility and resorbability.

In agriculture, E516 Calcium sulphate (gypsum) is used as a soil conditioner.
It improves soil structure, reduces sodicity, and supplies calcium and sulfur nutrients.
Unlike lime, it does not significantly alter soil pH.

In food applications, E516 Calcium sulphate is used as a food additive.
E516 Calcium sulphate functions as a firming agent, coagulant, and calcium source.
Common examples include tofu production and flour treatment.

E516 Calcium sulphate is applied in water treatment.
E516 Calcium sulphate helps control hardness, scaling, and mineral balance.
It is also used in wastewater treatment and sludge conditioning.

In industrial processes, E516 Calcium sulphate is used as a filler and extender.
E516 Calcium sulphate improves texture, strength, and cost efficiency in paints, plastics, and paper.
Its chemical stability makes it suitable for a wide range of formulations.

E516 Calcium sulphate is also used in laboratory and research applications.
E516 Calcium sulphate serves as a drying agent and reference material.
Its well-characterized properties support analytical and materials research.

E516 Calcium sulphate is a general additive available as both calcium sul- fate anhydrous, made by the high-temperature calcining of gypsum which is then ground and separated, and E516 Calcium sulphate dihydrate, which is made by grinding and separating gypsum containing about 20% water of crystallization.
E516 Calcium sulphate anhydrous contains approximately 29% calcium, and E516 Calcium sulphate dihydrate contains approximately 23% calcium. 

E516 Calcium sulphate is used, among other things, as a filler and baking powder for standardization purposes; a firming agent in canned potatoes, tomatoes, carrots, lima beans, and pep- pers; in dough as a source of calcium ions (because the absence of calcium ions causes bread dough to be soft and sticky and to pro- duce bread of poor quality); in soft-serve ice cream to produce dry- ness and stiffness; as a calcium ion source for reaction with alginates to form dessert gels; and as a calcium source for food enrichment.
E516 Calcium sulphate is used in the ceramics and pottery industry as a mold material.

Plaster molds made from E516 Calcium sulphate hemihydrate absorb water efficiently and allow precise shaping.
This is essential for slip casting of ceramic components.
In the glass industry, E516 Calcium sulphate is used as a fining agent and flux modifier.

E516 Calcium sulphate helps remove bubbles and improve glass clarity during melting.
Controlled sulfate content influences glass viscosity and quality.
E516 Calcium sulphate is applied in pharmaceutical manufacturing as an excipient.

E516 Calcium sulphate is used as a filler, binder, or diluent in tablets and capsules.
Its chemical inertness and biocompatibility make it suitable for oral dosage forms.
In paper and pulp processing, E516 Calcium sulphate is used as a filler and coating pigment.

E516 Calcium sulphate improves paper brightness, smoothness, and printability.
It also contributes to dimensional stability and cost reduction.
E516 Calcium sulphate is utilized in mining and metallurgy.

E516 Calcium sulphate is used in flotation processes and as a by-product in mineral processing.
Recovered gypsum is often reused in construction or agriculture.
In environmental engineering, E516 Calcium sulphate is used in flue gas desulfurization systems.

It is produced as synthetic gypsum during sulfur dioxide removal from exhaust gases.
This by-product is then recycled into building materials.
E516 Calcium sulphate is used in art, sculpture, and education.

Plaster of Paris is widely used for art casting, molds, and teaching demonstrations.
Its fast setting and ease of handling make it ideal for creative and instructional use.
In food processing beyond tofu, E516 Calcium sulphate is used to improve texture and firmness.

E516 Calcium sulphate is most often used as “gypsum” which is the dihydrate. 
In the form of b-anhydrite (the nearly anhydrous form), it is used as a desiccant. 
E516 Calcium sulphate is also used as a coagulant in products like “tofu”, which is a “bean curd”. 

When sold as a colorindicating variant under the name “Drierite ”, it appears blue or pink due to impregnation with cobalt chloride, which functions as a moisture indicator. 
In its natural state, unrefined E516 Calcium sulphate is a translucent, crystalline white rock. 
Many forms are known, including “Alabaster” and “Gypsum”, selenite, Satin spar, Desert rose, and Gypsum flower are four varieties of Gypsum minerals; all four varieties are crystalline. 

The four “crystalline” varieties of gypsum are sometimes grouped together and called selenite. 
All have the same chemical formulation, CaSO4·2H2O. All varieties of gypsum are very soft minerals (hardness: 2 on Mohs scale). 
This is the most important identifying characteristic of gypsum.

E516 Calcium sulphate is widely used in the construction industry.
Gypsum is used to produce plaster, drywall, and gypsum boards for walls and ceilings.
Plaster of Paris is used for casting, molding, and decorative architectural elements.

In building and civil engineering, E516 Calcium sulphate is used as a setting regulator in cement.
Small additions control the hydration rate of cement and prevent flash setting.
This ensures workable concrete and consistent strength development.

Safety Profile Of E516 Calcium sulphate:
Inhalation of E516 Calcium sulphate dust can lead to coughing, throat irritation, or short-term breathing discomfort.
Adequate ventilation and dust control measures are recommended in occupational environments.

Prolonged skin contact with dry E516 Calcium sulphate powder may cause mild dryness or irritation.
This effect is physical rather than chemical and is usually reversible.
Protective gloves and basic hygiene practices help minimize discomfort.

Accidental ingestion of small amounts is generally not harmful.
However, excessive ingestion may cause gastrointestinal discomfort such as constipation or irritation.
Such exposure is unlikely outside industrial or laboratory settings.

E516 Calcium sulphate is generally considered to have low toxicity and is not classified as hazardous under normal conditions of use.
E516 Calcium sulphate is a naturally occurring mineral widely used in construction, food, medical, and agricultural applications.

E516 Calcium sulphate normal handling does not pose significant health risks.
Exposure to dust or fine particles may cause mechanical irritation to the eyes, skin, or respiratory tract.