Effect of volatile matter and ash composition on the migration of organic sulfur during pyrolysis of high-sulfur coal

Investigating the forms of organic sulfur in coal and their thermal conversion characteristics is crucial for the efficient utilization of high-sulfur coal. The research explores the extraction of thermal dissolution soluble fraction (DZE) from Duizhen high-sulfur coking coal (DZ) using thermal dissolution technology and investigates the impact of volatile and ash compositions on the migration behavior of organic sulfur through various co-pyrolysis experiments. The results indicate that sulfurs present in sulfides and sulfates exhibit a greater tendency to migrate into the gas or liquid phase compared to other sulfur forms. During DZE pyrolysis, the residual rate of sulfoxides in coke was lower than that observed during DZ pyrolysis, while the rates for thiophene and sulfone remained relatively stable. Co-pyrolysis experiments demonstrate that volatile matter reduce sulfur retention in coke by providing active hydrogen in situ and enhancing mass transfer. The alkaline minerals (Fe 2 O 3 and CaO) in the ash, counteract the beneficial effects of volatiles on thermal desulfurization by trapping S radicals and H 2 S. However, deashing treatment enhanced the migration of sulfur to the gas and liquid phases during pyrolysis, facilitating the decomposition and conversion of sulfones. These findings suggest that the coke industry can effectively utilize pretreated high-volatile coal as a hydrogen-supplying raw material for the thermal desulfurization of high-sulfur coal.