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Integrated Numerical Modeling of Sedimentation, Self-Weight Consolidation and Desiccation of Wet Mine Tailings

Ardeheh, Arman | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57407 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. The dewatering processes within Tailings Storage Facilities (TSFs) involve a complex interplay of sedimentation, self-weight consolidation, and desiccation driven by surface evaporation of tailings slurry. Effective management of TSFs presents significant challenges in the field of mining engineering, such as implementing sustainable disposal practices to mitigate environmental pollution, preventing soil contamination from leakage, and ensuring the structural stability of TSFs under static and seismic conditions. Therefore, accurate modeling of dewatering behavior in wet tailings within TSFs is crucial for assessing TSF volume, estimating the lifespan of existing TSFs, determining optimal discharge timings for new materials onto desiccated tailings, and optimizing TSF dimensions based on management strategies. In this research, following a review of technical literature, an implicite finite difference program was developed with the aim of modeling the integrated sedimentation-self-weight consolidation processes. To integrate sedimentation, self-weight consolidation, and desiccation processes, this program was added to the finite difference program of self-weight consolidation and desiccation developed by Samimi (2006). The program by Samimi (2006) can model self-weight consolidation and self-weight consolidation in layered soils, sequential filling of the TSF during consolidation, and drying due to evaporation from the surface and crack wall in very soft soils. In this study a refined transition function was introduced to facilitate a smooth transition between the sedimentation and consolidation phases, ensuring a clear distinction between each process. Furthermore, utilizing the discretization technique proposed by Samimi (2006), the integrated program was developed to effectively model the entire sequence from deposition to drying during successive filling periods. Subsequent validation of the finite difference program involved assessing its capability to simulate pure sedimentation, sedimentation-self-weight consolidation, self-weight consolidation-desiccation, and the integrated sedimentation-self-weight consolidation-desiccation processes using laboratory and field experiments. Additionally, a comprehensive parametric study was conducted to analyze the sensitivity of slurry behavior to initial conditions and specific gravity, as well as to investigate the impact of varying factors such as layer thickness, evaporation rate, and delays in surface water decantation on settlement behavior in TSFs. The findings revealed that changes in specific weight within conventional ranges had negligible effects on slurry settling behavior. Moreover, reducing the thickness of deposited layers increased the final settlement of tailings, while higher evaporation rates compromised the effectiveness of the drying process in enhancing settlement and density. Delaying surface water decantation was observed to postpone the desiccation process, thereby enhancing settlement and consolidation processes, ultimately increasing density within the TSF
  9. Keywords:
  10. Sedimentation ; Slurry ; Numerical Modeling ; Wet Mine Tailings ; Self-Weight Consolidation ; Large-Strain Self-Weight Consolidation ; Evaporative Desiccation ; Finite Difference Method

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