ABSTRACT
The surface deposition of thickened or paste tailings has gained increasing acceptance in the mining industry over the past 25 years, with large potential benefits for the mining industry (Robinsky, 1999). Tailings can now be dewatered to the extent that only minimal bleed water is generated when the tailings are not in motion. Deposition of tailings in this relatively dense state, substantially reduces both water use and the footprint of the waste impoundment, compared with slurry deposition. Thickened tailings exhibit some shear strength, and gain further strength through desiccation and selfweight consolidation under subsequent layers of deposition. Thus, a stable “stack” can be built up, obviating the need for large dams and thus eliminating the risk of catastrophic failure by dam collapse. However, in the case of acid-generating tailings, there remains some risk for generation and release of acid drainage to the environment. Minimization of this risk requires knowledge of the hydraulic properties of the tailings, and understanding the various hydrologic processes that may contribute to acid drainage (Figure 1).
