Comparison of Coal Gasification and Combustion Residues

Abstract

Slags produced from the entrained flow gasification and cyclonefurnace combustion of Pittsburgh seam coal are morphologically similar and exhibit similar leaching behavior. Both wastes consist predominantly of dense glassy shards with low specific surface area (<1m2/g). Based on aqueous extraction and inorganic analyses according to the extraction procedure specified under the Resource Conservation and Recovery Act (RCRA), none of the combustion or gasification solid wastes examined in this study would be classified as hazardous under current federal regulations. The concentrations of most trace elements in RCRA and other batch extracts of the gasification slag and combustion bottom wastes were below current or proposed drinking water levels. In contrast, arsenic, cadmium, chromium, selenium, zinc, manganese, copper, and sulfate in batch extracts of two combustion fly ashes from Pittsburgh coal exceeded drinking water criteria. These results suggest that slags from entrained flow coal gasification should not require solid waste management practices substantially different from those currently used for coal combustion solid wastes.