Structural characteristics of separated components from high-Sulfur coking coal: Innovative research on pyrolysis sulfur migration behavior and coke quality improvement

Understanding the structural characteristics of high-sulfur coking coals is essential for the effective use of high-sulfur coals. In this study, thermal dissolution was employed to separate the Duizhen high-sulfur coking coal (DZ) into an extract (DZE) and a residue (DZR). The influence of the structural differences between DZE and DZR on sulfur migration behavior was further investigated, and the quality of the cokes from co-pyrolysis of DZ with DZE and DZR was evaluated. The results indicate that DZE is rich in aliphatic chain structures and oxygen-containing functional groups, whereas DZR retains a higher content of aromatic matrix and ash. DZE promotes the migration and transformation of sulfoxides and thiophenes by releasing reactive H and enhancing mass transfer. In contrast, the highly aromatic structure of DZR tends to bind with reactive sulfur species, forming stable sulfur-containing compounds, which thereby inhibits the release of H 2 S. Functioning as both a hydrogen donor and a binder modifier, DZE not only enhances synergistic desulfurization during co-pyrolysis but also contributes to improved coke quality. Although DZF also supports desulfurization to some extent, its limited caking properties and elevated ash content adversely affect the structural integrity and overall quality of the resulting coke. This study further explored the synergistic effects occurring during the co-pyrolysis process, revealing how the distinct structural features of the separated fractions influence sulfur migration behavior. This study provides theoretical basis and technical pathways for the clean and efficient conversion and resource utilization of high-sulfur coal.