A new technique for simultaneous grinding and hydrating of fluidized bed combustion (FBC) bottom ash has been developed. This method has been shown to be effective in hydrating the CaO component of the ash, so that the sorbent is reactivated. Careful control of water levels is required to prevent energy demand increases for grinding. No problems associated with the potentially exothermic reaction of water with FBC bottom ash have been observed during grinding. When excess water (over that required by hydration) is used, the resulting material is a slurry and, while quantitative conversion of CaO in the solids is achieved, using the slurry for the sorbent would require a redesign of the limestone feed system. Therefore, coal or unreacted ash is added to the mixture after grinding. The resulting dry product contains the spent bed material in a completely hydrated form. The reactivated ash produced has been evaluated for sulfur capture using thermogravimetric analysis and a CFBC pilot plant. Conversion rates...