Developing durable paste backfill from sulphidic tailings Available to Purchase

Mitigation of acid mine drainage (AMD) generated from the surface disposal of mine tailings (MT) containing sulphide minerals is one of the major challenges facing the mining industry today. AMD results in acidic effluents containing elevated concentrations of sulphates and metallic and metalloid elements. It can thus cause severe contamination of soils, surface and groundwater, along with devastating environmental damage. Paste backfill is a relatively new technology whereby MT are solidified/stabilised using binders and processed back into the mined space. The cogent reasons supporting this technique include lower operating costs, efficient ground support, reduction in the amount of waste to be disposed of on the surface and significant environmental benefits through better control of pollutants. An additional advantage is that industrial by-products such as cement kiln dust (CKD) and fly ash can be used alone or in combination with Portland cement to enhance the properties of paste backfill and reduce binder cost. The goal of the present research is to examine the strength development of paste backfill prepared using sulphidic MT and industrial by-products (e.g. CKD and fly ash) with or without Portland cement. Furthermore, the pH and sulphate content of paste backfill mixtures was monitored to provide information on both the tailings oxidation process and potential sulphate attack in paste backfill. The findings indicate that utilising industrial by-products in the preparation of paste backfill reduced the availability of calcium aluminate compounds susceptible to sulphate attack associated with cemented paste backfill containing ordinary Portland cement. It is also shown that developing an efficient technique for AMD control through making paste backfill from sulphidic MT can be both feasible and cost-effective.