Abstract: Lime utilization for sulfurous oxides absorption in fluidized combustion of carbonaceous fuels is improved by impregnation of porous lime particulates with iron oxide. The impregnation is achieved by spraying an aqueous solution of mixed iron sulfate and sulfite on the limestone before transfer to the fluidized bed combustor, whereby the iron compounds react with the limestone substrate to form iron oxide at the limestone surface. It is found that iron oxide present in the spent limestone acts as a catalyst to regenerate the spent limestone in a reducing environment. With only small quantities of iron oxide the calcium can be recycled at a significantly increased rate.

Abstract: In a fluidized-bed combustor the evolving sulfur oxides are reacted with CaO to form calcium sulfate which is then decomposed in the presence of carbonaceous material, such as the fly ash recovered from the combustion, at temperatures of about 900.degree. to 1000.degree. C., to regenerate lime. The regenerated lime is then recycled to the fluidized bed combustor to further react with the evolving sulfur oxides. The lime regenerated in this manner is quite effective in removing the sulfur oxides.

Abstract: Lime utilization for sulfurous oxides adsorption in fluidized combustion of carbonaceous fuels is improved by impregnation of porous lime particulates with iron oxide. The impregnation is achieved by spraying an aqueous solution of mixed iron sulfate and sulfite on the limestone before transfer to the fluidized bed combustor, whereby the iron compounds react with the limestone substrate to form iron oxide at the limestone surface. The iron oxide present in the spent limestone is found to catalyze the regeneration rate of the spent limestone in a reducing environment. Thus both the calcium and iron components may be recycled.

Abstract: High-purity coal useful in the production of high-purity carbon is produced by treating coal to remove the impurities therein. The coal, which may be subject to conventional pretreatment processes such as beneficiation processes or the like, digested in a caustic solution to solubilize certain of the impurities in the coal and to chemically react with other impurities to form acid soluble products. The digested coal is then filtered to separate the partially purified coal from the caustic and soluble impurities dissolved therein. The coal is then treated with a mineral acid to dissolve the acid soluble products contained in the coal. Finally, the coal is subjected to a nitric acid treatment to remove metal sulfides. The resultant high-purity carbon contains less than 0.1% by weight ash or metal sulfides.