University of Zagreb. Faculty of Chemical Engineering and Technology.
Abstract
Otpadni gips, CaSO4×2H2O, hidrotermalno je transformiran pri temperaturama od 120-160 °C u reaktorskom sustavu otvorenom i zatvorenom prema atmosferi. Pri temperaturama od 130-160 °C, rendgenskom difrakcijom ustanovljeno je da nakon 24 h gotovo nestaje gips, a nastaje hemihidrat, CaSO4×½H2O, anhidrit, CaSO4, te rijetko spominjana faza CaSO4×0.67H2O. Ovi su rezultati u suglasju s rezultatima infracrvene spektroskopije. Ustanovljen je utjecaj hidrotermalne obrade na morfologiju kristala nastalog produkta kojom se pripravlja gips visokih mehaničkih svojstava. U daljnjem radu potrebno je pratiti i održavati željeni parcijalni tlak vodene pare u sustavu.Waste gypsum, CaSO4×2H2O, had been hydrothermaly transformed in reaction system closed and open to the atmosphere at temperatures 120-160 °C during 24 h. Samples prepared at 130 °C and higher temperatures contained, from the results of X-ray diffraction, mainly bassanite mineral (hemihydrate) CaSO4×½H2O, anhydrite, CaSO4, and rarely mentioned hydrate phase, CaSO4×0.67H2O. These results are in concordance with the results of infrared spectroscopy. The influence of hydrothermal treatment on product crystal morphology opens up the possibility of preparation of gypsum of high mechanical properties. Further work should focus on the improvement of experimental setup, especially regarding the possibility of measuring and controlling water vapor partial pressure
