"This article reports on the findings of a study regarding the sulfur behavior across a Sasol−Lurgi gasifier. This was undertaken to understand the behavior of the various sulfur-bearing components in the coal, as they are exposed to the conditions in the gasifier. In this study, conventional characterization techniques were employed to monitor the behavior of sulfur-bearing mineral matter across the gasifier. It was observed from the study that the sulfur-bearing mineral (pyrite) in the coal structure undergoes various changes with pyrite being transformed to pyrrhotite and then to various oxides of iron with the subsequent loss of sulfur to form H2S. A low proportion of the sulfur species including the organically associated sulfur was encapsulated by a melt that was formed by the interaction between kaolinite and fluxing minerals (pyrite, calcite, and dolomite/ankerite) present in the coal at elevated temperatures and pressure, thereby ending up in the ash. The remaining small proportions of sulfur-bearing mineral matter including pyrite and organically bound sulfur in the unburned carbon in the carbonaceous shales also report to the ash."
We're sending this one along for a couple of reasons.
First, note that one of the authors is credentialed by Penn State - who, apparently, participated in the study.
And, they seem to be discussing ways in which objectionable sulfur can be bound to the ash (remember, we've sent you other references to "low-sulfur" liquid fuel derived from coal).
Finally, they are exposing the fact that properly designed coal conversion processes (whether Fischer-Tropsch, or, in this case, Sasol-Lurgi (an FT variant we've previously described for you) can be perform transmutations not only on coal, but on "carbonaceous shales" - a typical component of coal mine waste piles.