The effect of disposal method on environmental properties of surface paste tailings

9th International Symposium on Mining with Backfill
Thomas Deschamps, Mostafa Benzaazoua, Bruno Bussière, Michel Aubertin, Tikou Belem,
Abstract Surface paste tailings have been recently proposed as an alternative to “conventional” tailings disposal methods for surface storage. The main objective of surface paste tailings is the creation of a self-supporting homogenous (non-segregating) tailings stack without the construction of large water-retaining structures. Although the method is already used, the environmental behavior of paste tailings containing sulphide minerals is not yet well understood so it remains difficult to optimize the disposal approach. The main objective of this paper is to present the result of an investigation on the effect of binder addition on the hydrogeological and geochemical properties of surface paste tailings. Nine leaching columns where prepared with different disposal configurations: uncemented, uncemented with cemented layers, and fully cemented (the proportions of cement by total dry tailings weight are between 0 and 1%). The material used is a sulphide-rich tailing produced by a Canadian hard rock polymetallic mine. The columns have been watered once a week during 30 weeks. The recovered leachates were analyzed for pH, Eh, conductivity, and a wide range of elemental analyses. The percolation rates were monitored after each column flush. Results show that binder addition can improve the whole environmental performance for some of the studied scenarios. The configurations consisting of intercalation of three 2% cement paste layers within non-cemented layers (0.66 wt.% of cement for the whole column), and the configuration with 2% cement added only in the two bottom layers (0,44 wt.% of cement for the whole column), produced the best results in terms of water quality and percolation rates. Results also show an important change in the paste hydrogeological properties over the 30 weeks testing.
Keywords: surface paste tailings, acide mine drainage, leaching test
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