Speciation Characteristics and Contamination Degree of Trace Elements in Coal Gangue Hill of a Mining Area in Huainan Coalfield, China

Coal gangue is one of the most accumulated solid wastes in China, its accumulation occupies a large amount of land resources and the potential environmental risks posed by coal gangue continue to rise. In this study, sequential extraction was employed to analyze the fractionation behavior of trace elements (Cd, Cr, Cu, Mn, Ni, Pb, V and Zn), The contamination degree and potential ecological risk of trace elements were comprehensively evaluated by Geo-accumulation Index ( I geo ), Potential ecological risk index and the Risk assessment code (RAC) method. The results of XRD shows that there are various minerals in coal gangue, with obvious diffraction peak characteristics, and the minerals with higher levels are quartz, kaolinite, dolomite and potassium feldspar. The trace elements are predominantly found in the residual state. The results of I geo reveal that all trace elements are in a pollution-free state. The potential ecological risk level of Cd belongs to strong risk, while the level of the other elements is slight risk. The result of RAC indicates that the active forms of Mn may cause the greatest harm to the ecological environment, and which deserves further attention. The results can provide scientific basis for the stacking management and comprehensive utilization of coal gangue.