Laboratory investigation of the control of acid mine drainage using alkaline paper mill waste

Abstract

A great deal of research effort has been undertaken to find an effective solution to the problem of acid mine drainage. Indeed, Canadian legislation requires mining companies to respect environmental regulations by providing a rehabilitation plan with a financial guarantee. In order that the Canadian mining industry remains competitive, the proposed solutions have to be not only efficient but also economic, that is why the use of another waste material is attractive. The main objective of this study was to investigate the technical and environmental feasibility of stabilizing acid mine residues using alkaline paper mill waste produced by the pulp and paper industry as a basic source. The mineralogical characterization of the alkaline paper mill shows that calcite is the dominant mineral with hydrated lime (portlandite) present at a low content. The mineralogical characterization of the mining residues shows a polyphasic system where silica dominates the oxidized zone. On the other hand, a high pyrite content is present in the non-oxidized zone. The essential observations that emerge from the leaching tests undertaken in the laboratory can be summarized by the efficiency of the incorporation of the alkaline paper mill waste (1/3 waste and 2/3 mining residue) on the production of acid mine drainage. In fact, it can be observed that there is a reduction of the high toxicity elements like heavy metals. The increase in pH permits the reduction of catalytic bacterial activity and reduces the rate of oxidation in the mining residue.