Models that compute dewatering using accurate coupling of evaporation, unsaturated flow and large strain consolidation may have utility in providing guidance to optimise deposition of thickened tailings. A recently developed research model, UNSATCON, is used to analyse some typical field deposition profiles for both hard rock and oil sands fine tailings deposits. Model parameters are selected from previous studies on hard rock and oil sands tailings. Some validation with select field data is presented. Exploratory analysis reveals a number of interesting findings. For hard rock tailings, where self-weight consolidation after lift placement occurs relatively quickly due to high hydraulic conductivity of the tailings, maximisation of density can be achieved for a wide range of lift thickness and rates of rise even with relatively low rates of evaporation.
For desaturation and risk of oxidation, lift thickness and deposition timing become more important. For oil sands tailings, the timing of deposition and lift thickness are more important for maximising density due to the much lower hydraulic conductivity and, therefore, the longer time of self-weight consolidation.
Keywords: consolidation, unsaturated flow, field deposition, density, saturation, oxidation
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