Numerical modeling of flow due to consolidation of mine waste tailings
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ORIGINAL PAPER
Numerical modeling of flow due to consolidation of mine waste tailings Emad Ghazavi Baghini 1
Received: 20 July 2015 / Accepted: 26 February 2016 # Saudi Society for Geosciences 2016
Abstract Tailing dams are complex geotechnical structures. The present paper focuses on the Sarcheshmeh Copper Complex tailing dam in Iran, with the objective of gaining knowledge about the tail behavior under consolidation. The main goal is to find the steady-state flow of the tail consolidation. The tail consolidation was modeled by using the finite element method and large-strain consolidation concepts. A two-dimensional consolidation model for modified coordinates was developed. Recorded data on the seepage flow at the Miduk Copper Complex tailing dam, (also in Iran) were used for model training and prediction of the Sarcheshmeh tailing dam seepage flow. By using the void ratio concept and by regulating the solid content diagram and volume compressibility in each step of analysis, the volume of water released over time could be obtained. The results show good convergence between the monitored seepage flow at the Miduk tailing dam and the output of the finite element code. Furthermore, this technique for finding consolidation flow of tailings can be used for various types of tails and geometries. Keywords Tailing dam . Large-strain consolidation . Finite element method . Modified coordinates . Flowmeter
Introduction Tailing dams are built for the purpose of impounding mine waste materials, which are produced during the concentration * Emad Ghazavi Baghini [email protected]
1
Civil Engineering Department, Shahid Bahonar University of Kerman, Kerman, Iran
process. The main objective for the construction of these dams, besides the environmental aspects, is water recycling for mining activities (Azam and Li 2010). After the deposition of tailing materials behind the dam, tailing densification occurs due to sedimentation; bleed water is released during this process. Bleed water is the water in tailings which tends to rise to the surface of tailings. The next step in the densification process is the result of consolidation. When fine-grained slurry is poured rapidly, water is locked in the tail body, and the water pressure in the pore spaces increases. Then, depending on the consolidation parameters, the pore water pressure dissipates. These processes are accompanied by a decrease in the volume of the slurry, an increase in density, and the discharge of free water to the surface and base of the tailing deposit (Azam et al. 2005). Tailing materials are generally fine-grained; therefore, their permeability coefficient is low. Low permeability plays a significant role in the consolidation phenomenon. The tailings permeability under self-weight consolidation also has a decreasing trend; as a result, it takes a long time to complete the consolidation process. The Sarcheshmeh tailings contain 30–40 % water; hence, when this amount of water is discharged, large deformations occur in the tailing materials. The phenomeno
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