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 oxi dation with a mixture of hydrogen peroxide in acetic acid, which is kn own to produce peroxyacetic acid in situ. The simultaneous removal of both inorganic and organic sulfur was measured with respect to coal ty pe, particle size, method of coal preparation, reaction time and react ion temperature. The desulfurization reactions were evaluated by measu ring the sulfur contents of the desulfurized products, their S/C ratio s, their ash yields and the amount of sulfur removed versus the amount of coal dissolved. In general, all inorganic sulfur and some of the o rganic sulfur could be removed from these coals using very mild condit ions. More organic sulfur could be removed at slightly higher temperat ures and longer reaction times, but more of the coal became soluble an d the yields of solid products declined. The level of desulfurization was largely independent of particle size, but demineralization appeare d to affect sulfur removal adversely. Preliminary results suggest that selective oxidation may be very effective as a pretreatment for subse quent desulfurization reactions.