An investigation of the porosity dependent strength and leachability of mine tailings matrices containing heavy metals

Abstract

Abstract Mine tailings are the byproducts of the mining industry. For many decades these tailings used to be stored in specially formed tailings ponds. This method of storage has caused several environmental disasters, coupled in some instances with human fatalities. These catastrophes prompted a change in the management strategy of tailings. This change started with attempting to solidify the tailings to immobilize them and reduce their hazard. As part of this new strategy, and in an effort to investigate the applicability of using mine tailings as a construction material, this study is an attempt to investigate the porosity dependent strength and leachability of newly formed mine tailings matrices. And to evaluate the applicability of using four different theoretical models to predict the strength of these matrices. For this purpose, two mine tailings, Musselwhite and Mont Wright, from the Eastern parts of Canada have been selected. In this study, solidification of the newly formed tailings matrices was investigated using Ordinary Portland cement, fly ash, slag and the new binder Calsifrit. Results show that using Calsifrit as a partial cement replacement, in addition to slag and fly ash, reduced the porosity of the tailings matrices. The leaching test showed that several types of heavy metals have a high percentage of retention in these matrices. Compressive strength results indicate that the tailings matrices are suitable as construction materials for certain structural applications. However, current theoretical models overpredict their strength and overprediction increases when fly ash or slag are added to the mix.