How does natural anhydrous gypsum become dihydrate gypsum?
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Recently, the company has been working on a process for calcining gesso to produce hemihydrate gypsum. Analysis of the results showed that the so-called \"gesso\" raw material is actually anhydrous gypsum, derived from saltwater lakes and likely natural anhydrous gypsum. Should we produce anhydrous gypsum directly into gypsum, or should we first add water to natural anhydrous gypsum or expose it to the atmosphere to convert it into dihydrate gypsum, and then proceed with the usual process to calcine it and produce A-hemihydrate gypsum and B-hemihydrate gypsum? I did some research, and it seems that natural anhydrous gypsum is also a product available on the market, with a price that is even higher than that of B-hemihydrate gypsum! I would appreciate some guidance from those with more experience on this forum regarding how to handle this natural gypsum. If water is added to convert it into dihydrate gypsum, what are the reaction conditions? Can it become dihydrate gypsum by simply adding water and drying it?
Waiting online for answers; please help to solve it!
Natural anhydrous gypsum generally does not have the ability to hydrate into dihydrate gypsum. It needs to be ground very finely and then an activator added in order to have hydrating capacity