Effects of flotation on the release behavior of sulfur and nitrogen during coal pyrolysis

Two Chinese coals were selected to investigate the effects of flotation on the release behavior of sulfur and nitrogen during pyrolysis. The results show that the removal rate of minerals and sulfur-containing compounds from raw coal by flotation are closely related to coal properties. The significant alterations of sulfur and nitrogen forms on coal surface are mainly presented in the decrease of sulfidic-S, thiophenic-S, and pyridinic-N, the increase of sulfones-S and quaternary-N after flotation. The release of sulfur-and nitrogen-containing gases during pyrolysis of raw and clean coals has evident differences, which are mainly caused by the change of the relative proportions of different sulfur and nitrogen forms in the process of flotation.