A performance-based approach for the calibration and prediction of fine tailings settlement for closure design

Authors: Sharp, T; Llano-Serna, M; Han, C Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2415_64

Cite As:
Sharp, T, Llano-Serna, M & Han, C 2024, 'A performance-based approach for the calibration and prediction of fine tailings settlement for closure design', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2024: Proceedings of the 17th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 887-904, https://doi.org/10.36487/ACG_repo/2415_64



Abstract:
The International Council on Mining and Metals (ICMM) recommends the performance-based design method, an increasingly popular approach among tailings engineers, to manage uncertainty in design. This method involves using surveillance data collected during the facility lifecycle to adjust the existing design parameters and estimate future performance. Its significance is particularly pronounced in the post-closure phase of tailings facilities, which are designed to have an unlimited design life (i.e. annual exceedance probability 1/10,000). This paper shows a performance-based application. The approach was used to tune the settlement design parameters of a fine, high-plasticity tailings material to predict the closure landform performance. The method used data from different instruments installed during the facility lifetime, settlement plates and topographic survey. A large strain deformation model incorporated the laboratory test results from particle size distribution, specific gravity, Atterberg limits, and Rowe cell and oedometric compression testing. The model was developed using FSCA software; a 1D finite strain consolidation analysis program used to determine the rate and amount of settlement for tailings, slurry and soft soils. The model predicted the settlements at specific locations within the tailings storage facilities (TSF) over the monitoring periods and compared them to the corresponding survey and instrumentation data results. Using the predicted settlements to inform the final design surface, the calibrated model was then used to predict the landform evolution of the fine tailings facility over the closure construction and post-closure periods. The contours mapped for different periods can indicate the future risks associated with excessive settlement and help with risk-informed decision-making in the early stages of closure design.

Keywords: performance-based design, fine tailings, calibration, closure

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