Calcium sulfate

Calcium sulfate (CAS 99400-01-8, formula Ca.H2O4S) is an inorganic mineral salt commercially available under trade names including Drierite, Crysalba, and Thiolite. It occurs naturally as gypsum and anhydrite and is also produced synthetically as a byproduct of industrial processes such as phosphoric acid manufacture.

In building and construction, calcium sulfate serves as the primary binder in plasterboard and floor screeds, where hydration reactions control setting time and mechanical strength. In water treatment, it promotes coagulation and flocculation by supplying calcium ions that destabilize colloidal particles. Food and pharmaceutical manufacturers also use it as a coagulant in tofu production and as a tablet excipient.

Calcium sulfate is supplied in anhydrous, hemihydrate, and dihydrate grades to suit specific processing requirements. Food-grade material conforms to FCC specifications, while pharmaceutical grades meet Ph.Eur. standards. The substance is registered under REACH and available in bulk bags and multi-wall paper sacks.