Desulfurization of high sulfur coals by rapid pyrolysis with alkali treatment

Subbituminous Muswell Brook and bituminous Nan Tong coals with added potassium hydroxide were heated at 523K in a nitrogen stream to transform thermally stable organic sulfur to reactive species. The parent coals and alkali treated samples were pyrolyzed rapidly in a free fall pyrolyzer in a nitrogen stream at 1233K with a heating rates of 4000-6000K/s. In the rapid pyrolysis, the alkali treated samples provided higher extents of reduction of organic sulfur than the parent coals. The low density group separated by sink-float in aqueous zinc chloride showed more effective reduction of organic sulfur than in high density group. The combined process of rapid pyrolysis with alkali leaching was effective for reduction of organic sulfur.