Stabilization/solidification of Iron Ore Mine Tailings Using Cement, Lime and Fly Ash

Current research emphasis is more on the utilization of materials that are considered as waste. Tailings and fly ash are major category of industrial wastes, whose disposal is problematic from environmental point of view. In this present research, Industrial byproducts, namely, lime (CaO) and class F type fly ash have been used as candidate materials along with the partial addition of ordinary Portland cement (OPC) in the Stabilization/solidification (S/S) of polymetallic iron ore mine tailings (TM). The effectiveness of S/S was assessed by comparing laboratory experimental values obtained from unconfined compressive strength (UCS), hydraulic conductivity and leaching propensity tests of S/S samples with regulatory standards for safe surface disposal of such wastes. Some S/S cured matrices were found unable to provide the required immobilization of pollutants. S/S and 28 days cured mine tailing specimens made with composite binders containing TM/10/0/0, TM/5/0/20, TM/10/0/40 and TM/0/10/40 significantly impaired the solubility of all contaminants investigated and proved successful in fixing metals within the matrix, in addition to achieving adequate UCS and hydraulic conductivity values, thus satisfying regulatory norms (U.S. EPA). Laboratory investigations revealed the TM blends (stabilized materials) were non-hazardous. The test results of this study are encouraging and it may be possible to undertake large-scale fill construction with stabilized tailing material that is sustainable and cost effective.