CHEMICAL COAL CLEANING USING SELECTIVE OXIDATION

The chemical desulfurization of two high-sulfur Illinois Basin coals (Illinois No. 6 and Indiana No. 5) was investigated using selective oxidation with a mixture of hydrogen peroxide in acetic acid, which is known to produce peroxyacetic acid in situ. The simultaneous removal of both inorganic and organic sulfur was measured with respect to coal type, particle size, method of coal preparation, reaction time and reaction temperature. The desulfurization reactions were evaluated by measuring the sulfur contents of the desulfurized products, their S/C ratios, their ash yields and the amount of sulfur removed versus the amount of coal dissolved. In general, all inorganic sulfur and some of the organic sulfur could be removed from these coals using very mild conditions. More organic sulfur could be removed at slightly higher temperatures and longer reaction times, but more of the coal became soluble and the yields of solid products declined. The level of desulfurization was largely independent of particle size, but demineralization appeared to affect sulfur removal adversely. Preliminary results suggest that selective oxidation may be very effective as a pretreatment for subsequent desulfurization reactions.