Dehydration of Gypsum Rock by Solar Energy: Preliminary Study

Abstract

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 formation 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 composed of 92.7% of anhydrite and 7.3% of bassanite was obtained for 5 min of solar exposure. Morphological and textural modifications were followed by SEM and interferometric/confocal profilometer.