Currently, the methods of analyzing sulfur and mercury occurrence in coal are not uniform, which makes it difficult to study the transition behavior of sulfur and mercury during coal pyrolysis. At the same time, the difficult removal of fine-grained pyrite in coal poses a challenge to the design of sulfur and mercury occurrence analysis methods. In this study, the sulfur and mercury in coal were simultaneously divided into five forms by SCEPs-PLTA. The transition behaviors of sulfur and mercury during coal pyrolysis were qualitatively and quantitatively analyzed by Py-MS-GC-MA combined with various characterization methods. The results show a significant correlation between sulfur and mercury in the same occurrence form. The release and migration behaviors of sulfur and mercury during the pyrolysis of coal containing fine-grained pyrite are basically the same as those of coal containing coarse-grained pyrite. During the pyrolysis process, mercury mainly enters the gas phase in the form of Hg⁰, and sulfur mainly remains in the char and tar in the form of organic sulfur. Inconsistent with the coal containing coarse-particle pyrite, the coals pretreated with SCEPs-HNO₃ still had decomposition release peaks of sulfide sulfur and sulfide-bound mercury during the pyrolysis process, further confirming that HNO₃ cannot completely extract the fine-grained pyrite in the coal. In addition, the presence of fine-grained pyrite in coal will hinder the oxidation of the coal matrix by HNO₃ extraction. These results provide a theoretical basis for the synergistic directional regulation of sulfur and mercury during thermal conversion.

Sulfur; Mercury; Occurrence; Transition behavior; Fine-grained pyrite