Field trial of solidifying/stabilizing multi-heavy metals-contaminated soil using phosphorus-based binders

Field tests were conducted to evaluate the effectiveness of binders (SS-H and SS-E) for solidifying/stabilizing iron (Fe) and manganese (Mn) contaminated soils at a gold mining acid waste collection reservoir. The field-stabilized soils were subjected to the toxicity characteristic leaching procedure (TCLP), pH, dry density, dynamic cone penetrometer tests, and heavy metal speciation analysis. The results indicated that field stabilization using SS-H and SS-E significantly reduced the leached concentrations of Fe and Mn, with the leached concentrations of Fe and Mn being below the national groundwater quality standard (GB/T 14848—2017, Class III). SS-H was more effective in immobilizing Mn, with its leached concentration decreasing from 23 mg/L to 0.02 mg/L. SS-E was more effective in immobilizing Fe, reducing its leached concentration from 34.3 mg/L to 0.04 mg/L. Both SS-H and SS-E significantly improved the strength of the solidified soils. The dynamic cone penetration index of SS-H and SS-E solidified soils decreased by 93.1% and 93.2%, respectively, as compared to the untreated soils. The results demonstrate that both SS-H and SS-E binders are promising in solidifying/stabilizing multi-heavy metals contaminated soils with low pH.