Influence of disposal configurations on hydrogeological behaviour of sulphidic paste tailings: A field experimental study

Surface paste disposal (SPD) is a new alternative employed by the mining industry for storage of mine tailings at the surface. In comparison with the conventional slurry tailings disposal, SPD could offer operational and environmental advantages, such as a better water management, no need for complex retaining dams, a reduced footprint of the tailings disposal area, and the possibility to use progressive reclamation. This paper describes a field investigation through a large-scale experimental cell to assess an SPD application for sulphidic mine tailings. The work addresses the effect of two disposal configurations (i.e., partially cemented and un-cemented) on their hydrogeological behaviour when submitted to actual climatic conditions, focusing mainly on the implementation challenges as well as on the first results obtained. Tailings were deposited in thin layers (10 layers of 10 cm each one) into two experimental cells (D × L × H = 8 m × 15 m × 2 m). Cement was added locally (2 wt.% of Portland cement) in the first layer of the cell (CC) to study its effect; the second cell (UC) is cement free. The evolution of volumetric water content Ѳ, suction ψ, oxygen consumption and cracks for each cell was monitored during and after deposition. Results show that the CC provides slightly higher Ѳ and smaller ψ values than the UC, most likely due to its geological properties dictated by the bottom cemented layer.