Dehydration of Gypsum Rock by Solar Energy: Preliminary Study

The dehydration process of gypsum rock was studied under concentrated solar energy by using a Fresnel lens with power density of 260 Wcm−2. Temperatures higher than 700˚C were attained for 1 min of solar exposure. The effect of grain size of sample and radiation exposure time on the for-mation of bassanite and anhydrite was studied by XRD. The complete transformation of dihydrate into hemihydrate and/or anhydrate phases is complete for the finer size sample. Plaster com-posed of 92.7 % of anhydrite and 7.3 % of bassanite was obtained for 5 min of solar exposure. Mor-phological and textural modifications were followed by SEM and interferometric/confocal profi-lometer