Calcium sulphate anhydrous (CaSo4)
Description
Calcium sulphate anhydrous (CaSO₄) is the water-free form of gypsum, appearing as a white, odorless, fine crystalline powder or granular solid with orthorhombic crystal structure.
Properties
It has low water solubility (0.21 g/100 mL at 20°C), high density (2.96 g/cm³), melting point around 1460°C (decomposes), and is hygroscopic, readily absorbing moisture to form hemihydrate (plaster of Paris) or dihydrate (gypsum).
Production
Obtained by heating gypsum (CaSO₄·2H₂O) above 200°C to drive off water, or as a byproduct from flue-gas desulfurization; γ-anhydrite form reacts slowly with water unlike soluble forms.
Main uses
Serves as a desiccant (e.g., Drierite), setting retarder in Portland cement, weighting agent in oil-based drilling fluids, food additive (E516) for acidity regulator, and in construction, agriculture (soil conditioner), and pharmaceuticals.
Specifications
| Model No. | N-CH1525 |
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