Evaluation of Newly Developed Aluminum, Lime, and Fly Ash Technology for Solidifaction/Stabilization of Mine Tailings

In this study, samples treated with aluminum, lime, and fly ash technology were subjected to different leaching tests per the toxicity characteristics leaching procedures (TCLP). The leachants were simulated groundwater, acid rain, sulfuric acid solution (modified TCLP), and 0.1 molar acetic acid solution (TCLP). The leachate solutions were analyzed by atomic absorption spectroscopy for the metal concentrations. The success of the treatment was evaluated based on results of leachability combined with X-ray diffraction analysis. The results of the experiments indicate that upon availability of aluminum for reaction, ettringite, and ettringitelike minerals are formed and precipitated as stable minerals. Moreover, the high hydrogen ion concentration environment of the samples, produced by lime and fly ash addition, and the stabilization effect of ettringite had contributed significantly to the reduction of the solubility of heavy metals. The X-ray diffraction analysis indicated that ettringite remained stable during the testing period of 660 days.