The significant growth of the metallic mining industry over the last few decades has made the construction of tailings deposits of large dimensions necessary, tailings being the fine mining waste resulting from the milling and concentration processes. In some cases the dams required to contain these tailings could reach a considerable height. The most common types of tailings dam in mining are the tailings sand dam, a special kind of hydraulic fill dam, for two main reasons: because such dams need to be built over a long period of time, and due to the low cost of sand available from the tailings. Both types have not only a similar construction method in common, but also negative social perception due to the history of failures associated with the original designs of these dams. These designs have evolved with time to more adequate schemes enabling a much better performance. Although these types of dam differ in many aspects, such as main objective, source of the sand for construction, and the total construction time, the evolution of their designs has some interesting similarities. At this Conference, critical aspects in the performance of both types of dams will be discussed, together with the evolution of their original designs.

In particular, this paper analyses the behavior of tailings dams in Chile, one of the most seismically active countries in the world. The worldwide tendency to design and construct taller tailings dams, as well as the effect of the resulting high confining pressures on the geotechnical behavior of the tailings sands, drain gravels, and filter materials is also discussed. The importance of the operational phase is addressed, because in tailings dams this phase can last many years and be the determinant in the final behavior of the dams. Finally, recommendations to mitigate risks along the complete life cycle of the dams are given, and new developments in tailings deposits are considered.