The balance between energy and water preservation in the deposition of dry tailings in wet climates

Authors: Kruyswijk, JB Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2115_13

Cite As:
Kruyswijk, JB 2021, 'The balance between energy and water preservation in the deposition of dry tailings in wet climates', in AB Fourie & D Reid (eds), Paste 2021: Proceedings of the 24th International Conference on Paste, Thickened and Filtered Tailings, Australian Centre for Geomechanics, Perth, pp. 145-156, https://doi.org/10.36487/ACG_repo/2115_13



Abstract:
In the past two decades, the mining industry has become more interested in ‘dry’ tailings. The improved water recovery and potential operational cost benefits have been described by several authors. Compared with conventional tailings disposal, increasing the level of dewatering improves water preservation without having a major impact on operational costs. Dry tailings deposition is a method whereby in the deposition of the tailings, no free water is released. Ultimately, there are two varieties of dry tailings: paste tailings and filtered tailings. Paste tailings are dewatered to the maximum saturated density, whereas filtered tailings are mechanically dewatered to an unsaturated state. Saturated, loose, contractant tailings are susceptible to liquefaction; the primary mode of failure in most catastrophic tailings storage facility (TSF) failures. Consequently, well-compacted filtered tailings are increasingly considered for risk control. The prerequisite for long-term stability is that the filtered tailings remain unsaturated over time and are in a dense state. This condition may not be met in wet or seasonally wet conditions. When saturation of the tailings may occur, TSF design must make accommodations for sufficient drainage and containment of the stored tailings. Under these conditions, the key differentiator between paste and filtered tailings is the approximate 10% extra water recovery. The improved water recovery comes at the expense of a significant increase in power and fuel consumption. In circumstances where the increased spend on the latter two energy sources is offset by the value of the reclaimed water, it may be justifiable to consider the application of filtered tailings. From a sustainability point of view, the increased CO2 emissions will also have to be taken into consideration when selecting the preferred dry tailings deposition method. In this paper, it is demonstrated that in given applications the balance between energy consumption, water preservation, and CO2 emissions favours paste tailings deposition.

Keywords: paste tailings, filters tailings, high-density tailings, tailings management, water preservation, CO2 emissions, power consumption, fuel consumption, sustainability

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