Tailings and mine waste / Хвостохранилища и шахтные отходы

Down-valley discharge of tailings in a valley storage, where practical, can provide a cost benefit through minimizing the size of the containment embankment. However, down-valley discharge results in water pooling against the containment embankment and the collection of finer, saturated material that can be subject to rapid strength loss. These factors limit the potential for upstream raise construction and can also present a long-term dam break risk if the embankment is not appropriately designed. A down-valley layout can also present an erosion and sediment release risk at closure. The Carrapateena project in South Australia required the design of a new tailings storage facility (TSF) in a broad valley with a large drainage catchment.Carrapateena represents one of Australia’s largest undeveloped copper deposits, with the project on schedule for first concentrate production in Quarter 4 of 2019. To reduce start-up costs, a down-valley arrangement was adopted for the initial stage of the TSF. A staged design was then developed to address dam break and closure risks, transitioning the tailings storage method from down-valley discharge to upvalley discharge during the second stage of operation and then to partial perimeter discharge. Partial perimeter discharge was selected to trans-locate the supernatant pond to a location some distance from the cross-valley embankment, but near the ultimate closure spillway. The staged design strategy considers up to six stages of development, for the cross-valley storage, with a transition from the downstream raise construction method to the upstream raise method. Although the site climate is arid, historical records show large rainfall events do occur. Gravity decant systems were developed for the life of mine design, with an inclined chute system during the down-valley discharge phase (for Stage 1) and a series of temporary towers for the transition phase and permanent towers for the longterm partial perimeter discharge arrangement. <...>