Characterization and environmental evaluation of Atikokan coal fly ash for environmental applications

Abstract

This study presents the results of physical, chemical, and mineralogical characterization of fresh and landfilled coal fly ash from Atikokan Thermal Generating Station, Ontario. The acid neutralization capacity, heavy metal sorption capacity, and possible environmental impact under different environmental conditions during utilization of the coal fly ash were also evaluated. The results show significant variations in morphology, mineralogy, and chemical composition between fresh and landfilled fly ashes attributed largely to weathering of the coal fly ash during landfilling. The formation of secondary minerals (predominantly calcite) in landfilled fly ash samples is confirmed by X-ray diffraction, thermal analysis, and Chittick tests. Chemical analysis of the generalized acid neutralization leaching test indicated that the heavy metals from both fresh and landfilled fly ash samples were below the leachate criteria set by the Ontario Government. Despite variations in acid neutralization capacity and physical and geochemical behaviors between fresh and landfilled coal fly ash materials, the overall results of this study suggest both materials have favorable engineering and environmental properties that make them suitable for various environmental applications.