Sulfur migration and distribution during pyrolysis of a typical Chinese pyrite-enriched coal

Sulfur migration and distribution during pyrolysis of coal is quite complicated with the effect from different intertwined influencing factors, which requires extensive investigation. In this research, a typical Chinese pyrite-enriched coal was selected and pretreated through acid leaching combined with CrCl2 reduction. Thereby, minerals such as silicates and sulfates in the raw coal were effectively separated with the ash contents decreased from 37.74% to 0.57% while the inorganic sulfur was completely removed. Furthermore, programmed combined with isothermal pyrolysis of the selected coal and its two pretreated counterparts were conducted on the home-designed horizontal reactor to systematically ascertain the gaseous sulfur evolution. Possible sulfur formation pathways were revealed to explain the effect from the intertwined factors between the reaction temperature and the intrinsic factors as minerals distribution, different sulfur occurrences and their association with the organic matrix of coal. Finally, quantitative evaluation of the temperature effect on the sulfuric gases distribution and their yields was conducted with the total fraction of all the gaseous sulfur much decreasing from 5.6% to below 2.0% for the deashed and depyrited coal. Overall, through such a systematic investigation on the sulfur evolution from a typical pyrite-rich coal, comprehensive insights were obtained for future efficient sulfur control.