Coal desulfurization with methanol/water and methanol/KOH

Mae Moh coal from northern Thailand was desulfurized by leaching with methanol/water and methanol/KOH in a batch reactor. The effect of methanol concentration, KOH concentration, coal particles, reaction temperature and reaction time on the removal of ash and sulfur was investigated. Depending on the desulfurization conditions, the reductions ranged from 36 to 74% in pyritic sulfur, 20 to 42% in organic sulfur and 33 to 62% in total sulfur. Methanol/KOH enhanced the desulfurization process in which the inorganic and organic sulfur were removed preferentially. KOH addition can improve the sulfur removal. The kinetics of the oxidation of pyritic sulfur was investigated for Mae Moh coal. The rate of reaction was found to be well represented by a continuous reaction model that was second order with respect to pyritic sulfur.