Abstract
For recovering CaO from spent gypsum at relatively low temperatures, decomposition behavior of CaSO4 was studied by using a thermogravimetric analyzer in CO-CO2-N2 and H2-C2-N2 atmosphere in a temperature range of 1123-1273K. The conversions of CaSO4 to CaO and CaS byproduct were determined by the weight change of the decomposition of CaSO4 and the oxidation of CaS to CaSO4, respectively.
It was found that the conversion of CaSO4 to CaO increased with an increase in temperature in both CO-N2 and H2-N2 atmosphere. On the other hand, the formation of CaS byproduct increased with the increase in CO and H2 concentrations, whereas the yield of CaO was decreased. It was possible to suppress the formation of CaS by adding high concentration CO2 to CO-O2-N2 and H2-CO2-N2 gas atmosphere. The conversion, greater than 90% of CaSO4 to CaO was obtained in a mixed gas of CO : 2%, CO2 : 30%, N2 : 68% at 1273K. The formation of CaS byproduct was not detectable in this condition.
