Stabilization and/or regeneration of spent sorbents from coal gasification. Final technical report, September 1, 1991--August 31, 1992

The objective of this investigation was to determine the effects of SO{sub 2} partial pressure and reaction temperature on the conversion of sulfide containing solid wastes from coal gasifiers to stable and environmentally acceptable calcium sulfate, while preventing the release of sulfur dioxide during the stabilization step. An additional objective of this study was to investigate the use of the Spent Sorbent Regeneration Process (SSRP) to regenerate spent Ca-based sorbent, from a fluidized-bed gasifier with in-bed sulfur capture, for recycling to the gasifier. To achieve these objectives, selected samples of partially sulfided sorbents were reacted with oxygen and SO{sub 2} at various operating conditions and the extent of CaS and CaO conversion were determined. Partially sulfided dolomite was used in sulfidation/regeneration over several cycles and the regeneration efficiency and sorbent reactivity were determined after each cycle. The results of the stabilization tests show that partially sulfided Ca-based sorbents (both limestone and dolomite) can be sulfated at temperatures above 1500{degrees}F resulting in high CaS conversion without release of SO{sub 2} producing environmentally acceptable material for disposal in landfills. The results also indicate that spent dolomite can be regenerated in the SSRP process, in successive cycles, with high regeneration efficiency without lossmore » of reactivity toward hydrogen sulfide.« less