REGENERATION OF CALCIUM SULFIDE UNDER ALTERNATING OXIDIZING AND INERTCONDITIONS - KINETICS AND MECHANISM

A new process for regeneration of calcium sulfide produced from coal g as desulfurization has been proposed. The regenerative process involve s the exposure of calcium sulfide to alternating oxidizing and inert a tmospheres. The process consists of two oxidation steps during which C aS is converted to CaSO4. Each oxidation step is followed by a regener ation step during which there occurs an apparent solid-solid reaction between CaS and CaSO4, which yields the products CaO and SO2. The mech anisms and kinetics for the oxidation of CaS particles,the reaction be tween CaS and CaSO4, and the overall regenerative process have been in vestigated with a thermogravimetric analyzer and mass spectrometer. Th e conversion of CaS to CaSO4 was 30% during the first oxidation step, whereas it reached as high as 71.6% in the next oxidation step. This a mount comes very close to the stoichiometry for the reaction between C aS and CaSO4. The apparent solid-solid reaction was fairly rapid at >8 50 degrees C, and a high degree of fractional production was achieved. When the overall regenerative process was completed, similar to 95% o f the CaS in the sample had been converted to CaO.