A new method for preparing of anhydrous calcium sulfate from gypsum

Gypsum or calcium sulfate dihydrated is one of the main and convectional chemical which is produced in majority from mineral sources. The ordinary method of preparation of anhydrous calcium sulfate (type II) is dehydration of gypsum by moderate amount of sulfuric acid at high temperature (about 130 oC) or great amount at low temperature. In this investigation a new method for preparing of anhydrous calcium sulfate was presented which in dehydration of gypsum by low amount of sulfuric acid at moderate temperature (90 oC) was studied experimentally. The results show that prepared anhydrous calcium sulfate has proper specifications in comparison with commercial anhydrous calcium sulfate. The product, also, has good stability and whiteness degree which can be used as paper pigment.