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Numerical Investigation of the Unsaturated Flow of the Leaching Solution in Heap Considering the Clogging Phenomenon

Sheikhmiri, Ali | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57251 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Sadeghi, Hamed
  7. Abstract:
  8. Due to humanity's increasing demands, the provision of raw materials plays a crucial role in meeting these needs, with a significant portion of the required materials being obtained from mines. One method for increasing the efficiency of mine wastes is heap leaching. A leaching heap is a layered mound of low-grade ore particles piled on an impermeable layer called a leaching pad. After being sprayed on the heap and reacting with the ores, the leaching solution is drained through the drainage system located in the heap leach pad and transferred to the collection pond for recovery of the target minerals. Due to the flow of fluid within the heap and the degradation of particles due to leaching, the existing or generated fines move downward in the heap and cause the clogging phenomenon to occur. Due to the impact of this issue on safety, economic, and environmental issues, the study of this phenomenon is of particular importance. The aim of this study is a numerical investigation of the unsaturated flow of the leaching solution in a heap considering the clogging phenomenon using the finite element method. For this purpose, a clogged layer under a layer of normal heap material is implemented in a 2D section of the geometry of the Miduk heap. The values of saturated hydraulic conductivity, porosity, and soil-water retention curve parameters for heap soil materials in normal and clogging conditions were determined using statistical methods after collecting relevant data from technical literature. The results of this study show that increasing the severity of clogging prevents the leaching solution from penetrating the lower layers, leading to cases such as pooling and leaching solution discharge from the slope of the heap instead of the drainage layer. The results of this study show that with increasing clogging severity, the time of the first discharge of leaching solution from the heap increases, which directly leads to an increase in extraction time and economic losses. The factors reducing efficiency include a 13% decrease in the flow rate of fluid discharge from the heap and a 38 to 52% increase in the remaining leaching solution in the heap, which is due to the rise in clogging severity. If the severity of clogging exceeds a limit that depends on the characteristics of the heap material, the location of the maximum pore fluid pressure will be transferred from the bottom of the heap to the boundary between the plugged layer and the normal heap material layer
  9. Keywords:
  10. Heap Bioleaching ; Clogging ; Statistical Analysis ; Numerical Modeling ; Soil Properties After Leaching ; Unsaturated Flow

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