Insight into resource recoverability and environmental hazards of coal gasification fine slag from trace element distribution perspective

Clarifying the distribution characteristics of trace elements including valuable and hazardous ones in coal gasification fine slag (CGFS) is the key to achieving a win-win situation for both economic and environmental benefits in the CGFS treatment process. In this study, the content levels of trace elements in a Chinese CGFS sample and their distribution characteristics in particle size-classified and density-classified products were comprehensively studied, and the recovery potential of valuable elements and the environmental pollution potential of hazardous ones in this CGFS were evaluated. The results revealed that the contents of various trace elements decreased and then increased as the particle size of CGFS increased, and they increased as the density of CGFS increased. According to the geological enrichment metallogenic characteristics, rare metal elements Li, Be, and Sr have no prospect of resource recovery currently while rare-scattered element Ga has a high resource recovery value. The recovery potential of rare earth elements from raw CGFS is unpromising, while that from some classified products is promising. According to the ecological risk assessment, the environmental pollution potential of <0.037 mm particle size grade and >2.0 g/cm(3 )density grade is the highest, while that of the others is reduced compared with raw CGFS. In addition, since hazardous trace elements are closely associated with valuable elements, the adverse impact of hazardous elements on the environment should be of great concern in the resource utilization process of CGFS including recovering valuable elements.