Evaluating the Profile Geochemical Characteristics and Environmental Risk Prediction of Typical Sulfide Tailing Ponds Through Multiple Methods

Abandoned tailings generated from copper mining are exposed to the environment for a long time will cause related risks, such as stability, landslides, surface and groundwater pollution, acid mine drainage (AMD) and secondary mineral deposits. This research started from multiple methods and comprehensively assessed the current status of mine tailings through the joint application of geophysics, geochemistry and mineralogy techniques to identify relevant environmental hazards. A thick oxidized hardened layer was formed on the surface of the tailings dam, but there were still faults or crack that affected its structural stability. According to the low-resistivity distribution of the tailings, the surface oxide compaction was judged, and the existence of high-resistivity cracks judged the potential migration path of heavy metals (HMs). The microscopic morphology and existing mineral phases of tailings particles at different depths in the profile were determined by SEM and XRD of representative samples as the main feature of iron crystalline phase. As the profile depth increased, the minerals such as calcite, pyrite and goethite gradually appeared. In addition, Cr and As were no risk, Cu, Zn, Pb were low risk, Ni was medium risk, and Cd was high risk in risk assessment code (RAC) analysis of the tailings. Judging whether HMs in the tailings are hazardous substances according to the results of toxicity characteristic leaching procedure (TCLP), it was found that the leaching contents of Cu, Zn, Pb, Cr, Ni, As were all lower than the limit, while the leaching content of Cd was higher than the limit, and additional attention should be paid to Cd pollution.