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Coupling Tailings Deposition Modelling with Hydrus-1D and Python for Pseudo-3D Seepage Predictions

University of British Columbia. Norman B. Keevil Institute of Mining Engineering; Tailings and Mine Waste Conference (2023 : Vancouver, B.C.)

Management of tailings storage facilities (TSFs) has become a hot topic in the mining industry since the recent catastrophic failures occurred. A robust tailings deposition analysis is a crucial task, as it allows the engineer to plan the operation accordingly. A proper analysis must, however, capture several complexities, including non-linear flow and deformation analyses and staged construction processes. This paper presents an automated modelling tool that uses Hydrus-1D, Python and Autodesk® Dynamo® to model time-dependent pseudo-3D seepage. This tool was developed to model seepage through a real TSF, enabling pseudo-3D seepage analyses to predict seepage evolution over time over the entire TSF. A Python script is used to automate the Hydrus-1D modelling sequence and is summarized as follows: i) the TSF 3D shape is discretized in space and time using the tailings production data and the deposition sequence of the tailings as 3D elements/columns; ii) the seepage is solved sequentially on each discretized column, and fresh tailings blocks are stacked on top of previously solved columns as tailings are being deposited; iii) the time-dependent total seepage over the entire base of the TSF is then computed, thus enabling, where required, the justification for geosynthetic liners (i.e., hydraulic barriers) and the design of drainage systems. The code has been used for several projects where the bottom seepage of conventional TSFs was predicted. The tool can also be used to determine the base seepage in waste rock dumps (WRD), heap leach facilities (HLF) and combined facilities (co-disposal). A real case example applied in Madaouela project is presented along several sensitivity analyses that account for variation in relevant inputs, such as hydraulic conductivities and tailings saturation. A key consideration for designing the seepage collection pond was to determine the rate of seepage at various stages of the project, to ensure adequate pond size to accommodate both seepage flows and potential stormwater runoff.

Text

2024-07-10

Attribution-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88608

Unreviewed

http://creativecommons.org/licenses/by-nd/4.0/