Simultaneous analysis of sulfur and mercury occurrence forms in coal by sequential chemical extraction procedures combined with plasma low-temperature ashing and their correlation study.

Sulfur and mercury are two pollution elements with affinity, and their correlation studies are crucial for understanding their migration, transformation, and directional regulation during coal thermal conversion. Studies on the correlation between sulfur and mercury in coal have been inconsistent, so it is necessary to classify the occurrence forms of sulfur and mercury in coal simultaneously and study the correlation between the same form of sulfur and mercury. The sequential chemical extraction procedures (SCEPs) combined with plasma low-temperature ashing (PLTA) have obvious advantages in simultaneous analysis of the occurrence forms of sulfur and mercury in coal containing fine-grained pyrite. The content accuracy of form sulfur and form mercury is increased by 11.59 % and 6.22 %, respectively. The total contents of organic S and sulfide S, organic matrix-bound Hg and sulfide-bound Hg in coal are 56.73 %-85.51 % and 65.49 %-90.86 %, respectively. There is a significant positive correlation between organic S and organic matrix-bound Hg, sulfide S and sulfide-bound Hg, and the correlation index is 0.9996 and 0.9998, respectively. This study lays a theoretical foundation for the migration and transformation of sulfur and mercury in the process of thermal conversion.