Sulfur migration during co-pyrolysis of high sulfur coking coal with fat coal and lean coal

Abstract

Desulfurization remains a critical yet challenging aspect of producing high-quality metallurgical coke through pyrolysis. Previous studies have suggested that introducing hydrogen-rich gases may improve sulfur removal efficiency. To further explore this approach, we investigated the effects of volatile matter on sulfur migration during co-pyrolysis of high-sulfur coal (SC) with both fat coal (FC) and lean coal (LC). Our findings indicate that most sulfur is transferred into the coke during pyrolysis, with sulfide and pyrite being relatively easy to decompose, while thiophenes and sulfones tend to be thermally stable. Co-pyrolysis with FC significantly decreased sulfur content in the final coke product, while co-pyrolysis with LC resulted in higher sulfur content. The comparative analysis points to the beneficial influence of volatile matter in promoting desulfurization through enhanced sulfur transfer into the gas phase and reduced sulfur fixation with nascent coke. These findings offer practical guidance for coke-making industries to optimize coal blending scheme and to achieve efficient desulfurization during coke-making.