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Enhancing leaching efficiency of ion adsorption rare earths by ameliorating mass transfer effect of rare earth ions by applying an electric field

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Journal of Rare Earths 2024年第1期42卷 172-180,I0006页

作者： Lingbo Zhou Jie Yang Shijie Kang Xiaojun Wang Hongdong Yu Yinhua Wan Rare Earth Institute University of Science and Technology of ChinaHefei230000China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou341000China Jiangxi Institute of Rare Earths Chinese Academy of SciencesGanzhou341000China School of Resources and Environment Engineering Jiangxi University of Science and TechnologyGanzhou341000China

Improving the seepage of leaching solution in the ore body and strengthening the mass transfer process of rare earth ions during in-situ leaching are two critical methods to improve the leaching efficiency of rare earth.In this study,2 wt%MgSO_(4)solution was used for the indoor simulated column leaching experiment on rare earth samples and an electric field was applied at both ends of the samples.Then the effects of different intensities,initial application time and duration of the electric field on the rare earth leaching system and its mechanism were investigated.The results show that compared with the single MgSO_(4)solution leaching,applying an electric field with a strength of 6 V/cm can save the leaching time of 30 min and increase the flow velocity of the rare earth leachate by 26.98%.Under the optimal conditions of applying an electric field with a strength of 6 V/cm for 20 min to the leaching system after10 min of the rare earth leachate flowing out,the leaching efficiency of sample increases from 81.20% to 86.05% with the increase of 4.85%.The mechanism analysis shows that when a direct current electric field is applied to the rare earth leaching system,rare earth ions rapidly change from disorderly movement with the seepage into faster and directional movement.In addition,the seepage of the leaching solution is also improved due to the increase of the cross-sectional area of the seepage channel,the polarized water molecules migrate directionally by force from the negative pole,and the movement of the hydrogen is generated by the electrolytic water.More impo rtantly,based on the principle of in-situ leaching process,the layout of injection holes and deflector holes in this process provides a natural site for the electrode layout of the electric field.With the simple equipme nt and the ope ration,the rare earth leaching process with the applied electric field has high feasibility in industrial application.

关键词： Ion adsorption rare earths Leaching system Electric field Mass transfer process seepage

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seepage behavior of soil mixed with randomly distributed recycled plastic materials

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Water Science and Engineering 2022年第3期15卷 257-264页

作者： V.P.Devipriya S.Chandrakaran K.Rangaswamy Department of Civil Engineering National Institute of Technology CalicutCalicut 673601India

seepage through embankment fill materials is crucial issue in the construction of embankments for irrigation and drainage projects.Proper ground improvement methods should be used to improve the strength and stability characteristics of soil used as fill material.Utilization of waste plastic materials to enhance the engineering properties of soil is a sustainable approach.Additionally,the use of raw products directly from plastic recycling units in the form of flakes and pellets as soil additives has the potential to further enhance the economic benefits of this method.This study randomly mixed plastic materials with soil for use in the construction of earth embankments,such as river levees,dykes,and canal diversion structures,and evaluated the effectiveness of these materials in reducing seepage failures in hydraulic structures.To achieve these goals,this study collected high-density polyethylene(HDPE)plastic from plastic recycling units and used soil mixed with HDPE plastic in the form of flakes and pellets in different contents as embankment fill materials,then evaluated how these materials affected the piping features.Laboratory experiments were conducted to determine the seepage velocity and critical hydraulic gradient of soil mixed with plastics in various contents and to compare the values with those of plain soil.The results showed that random distribution of waste plastics in the form of flakes and pellets in soil is an effective method for improving the piping resistance of soil.

关键词： Earth embankments seepage Recycled plastics Critical hydraulic gradient Piping resistance

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Theoretical research on gas seepage in the formations surrounding bedded gas storage salt cavern

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Petroleum Science 2022年第4期19卷 1766-1778页

作者： Xiang-Sheng Chen Yin-Ping Li Ya-Long Jiang Yuan-Xi Liu Tao Zhang State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure East China Jiaotong UniversityNanchang 330013Jiangxi China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsChinese Academy of SciencesWuhan 430071 HubeiChina University of Chinese Academy of Sciences Beijing 100049China

When constructing salt cavern gas or petroleum storage in lacustrine sedimentary salt formations rich in mudstone interlayers, the influence of the sealing performance of interlayers and salt-mud interface on the storage tightness should be considered adequately. In order to reveal the gas seepage in deep formations surrounding bedded salt cavern underground storage, a leakage analysis model was established based on the characteristics of a low dip angle and the interbedded structure of bedded rock salt. The gas seepage governing equations for one-dimensional and plane radial flow were derived and solved. A gas seepage simulation experiment was conducted to demonstrate the accuracy and reliability of the theoretical calculation results. The error of the seepage range was approximately 6.70%, which is acceptable. The analysis and calculation results indicate that the motion equation of gas in deep formations satisfies a non-Darcy's law with a threshold pressure gradient and slippage effect. The sufficient condition for the gas flow to stop is that the pressure gradient is equal to the threshold pressure gradient.The relationship between the leakage range and operating time is a positive power function, that is, the leakage range gradually increases with time and eventually stabilizes. As the seepage range increases, the seepage pressure decreases sharply during the early stage, and then decreases gradually until the flow stops.Combining the research results with engineering applications, three quantitative evaluation indexes named the maximum admissible leakage range, leakage volume and leakage rate are proposed for the tightness evaluation of gas storage salt cavern during their operating stage. These indexes can be used directly in actual engineering applications and can be compared with the key design parameters stipulated in the relevant specifications. This work is expected to provide theoretical and technical support for the gas loss and tightness evaluation of gas storage salt caverns.

关键词： Gas storage salt cavern seepage Tightness Non-Darcy's law Leakage

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Application of the Navier-Stokes Equations to the Analysis of the Landslide Sediments Permeability and Related seepage Effects

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Fluid Dynamics & Materials Processing 2022年第2期18卷 313-327页

作者： Meng Song Yuncai Liu Zhen Wang Huanghe Science and Technology College Zhengzhou450063China Gaoda Construction Engineering Co. Ltd.of HenanZhengzhou450063China

The purpose of the study is to implement a new model based on the Navier-Stokes equations for the characterization of landslide sediments interacting with a moving fluid.The model is implemented by combining Hypermesh,the LS-DYNA software and MATLAB.The results show that the main factors affecting the permeability of landslide sediments are the genetic mechanism,the structure and composition of materials,material lithology,and stress.The characteristics and mechanism of permeability changes are determined by adjusting the water levels of fluids.It is found that the permeability of landslide sediments increases at the front and decreases in the middle and at the rear of the considered domain.The magnitude of the internal flow for the whole system decreases first and then increases with a change in the water level during seepage.

关键词： Navier-Stokes equation landslide sediment seepage

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seepage simulation of high concrete-faced rockfill dams based on generalized equivalent continuum model

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Water Science and Engineering 2018年第3期11卷 250-257页

作者： Shou-kai Chen Qi-dong He Ji-gang Cao School of Water Conservancy North China University of Water Resources and Electric PowerZhengzhou 450045China Henan Key Laboratory of Water Environment Simulation and Treatment North China University of Water Resources and Electric PowerZhengzhou 450045China Academician Workstation of Water Environment Governance and Ecological Restoration Zhengzhou 450002China Collaborative Innovation Center of Water Resources Efficient Utilization and Protection Engineering North China University of Water Resources and Electric PowerZhengzhou 450045China

This research focused on the three-dimensional(3 D) seepage field simulation of a high concrete-faced rockfill dam(CFRD) under complex hydraulic conditions. A generalized equivalent continuum model of fractured rock mass was used for equivalent continuous seepage field analysis based on the improved node virtual flow method. Using a high CFRD as an example, the generalized equivalent continuum range was determined, and a finite element model was established based on the terrain and geological conditions, as well as structural face characteristics of the dam area. The equivalent seepage coefficients of different material zones or positions in the dam foundation were calculated with the Snow model or inverse analysis. Then, the 3 D seepage field in the dam area was calculated under the normal water storage conditions, and the corresponding water head distribution, seepage flow, seepage gradient, and seepage characteristics in the dam area were analyzed. The results show that the generalized equivalent continuum model can effectively simulate overall seepage patterns of the CFRD under complex hydraulic conditions and provide a reference for seepage analysis of similar CFRDs.

关键词： Concrete-faced rockfill dam(CFRD) Generalized equivalent continuum model Node virtual flow method Fractured rock mass seepage field seepage coefficient

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seepage failure by heave in sheeted excavation pits constructed in stratified cohesionless soils

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Frontiers of Structural and Civil Engineering 2019年第6期13卷 1415-1431页

作者： Serdar KOLTUK Jie SONG Recep IYISAN Rafig AZZAM HPC AG Stuttgart 70597Germany Department of Engineering Geology and Hydrogeology RWTH Aachen UniversityAachen D-52064Germany Civil Engineering Faculty Istanbul Technical UniversityIstanbul 34646Turkey

In this study,experimental and numerical investigations are performed to clarify the seepage failure by heave in sheeted excavation pits in stratified cohesionless soils in which a relatively permeable soil layer(Kupper)lies above a less permeable soil layer(Klower)between excavation base and wall tip.It is shown that the evaluation of base stabilities of excavation pits against seepage failure by using Terzaghi and Peck's approach leads to considerably lower critical potential differences than those obtained from the model tests.On the other hand,a relatively good agreement is achieved between the results of the model tests and the finite element(FE)analyses.Further investigations are performed by using axisymmetric excavation models with various dimensions and ground conditions,and a comparison between the results obtained from Terzaghi and Peck's approach and finite element analyses is given.

关键词： seepage failure by heave cohesionless stratified soil model test Terzaghi and Peck's approach FE analysis

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seepage Mitigation in Hydropower Dams by Optimization in Roller Compacted Concrete Interlayer (Monoliths) Joint Bonding Technology

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Open Journal of Civil Engineering 2022年第1期12卷 139-151页

作者： Junjie Jin Qingguo Zhou Yuanguang Liu Shuncai Ning Kafue Gorge Lower Hydropower Station Sinohydro Bureau No.11 Co. Ltd Zhengzhou China Kafue Gorge Lower Hydropower Station Project Sinohydro Bureau No.11 Co. Ltd Zhengzhou China Kafue Gorge Lower Hydropower Station Project Institution of Engineering and Technology Sinohydro Bureau No.11 Co. Ltd Zhengzhou China Expert Team of Sinohydro Bureau No.11 Co. Ltd Zhengzhou China

Roller Compacted Concrete (RCC) has gained favorable recognition in hydropower and water resource dam construction. With optimization in construction technology and materials used for RCC Dams, cost is no longer a major disadvantage as compared to environmental impact, that is, wildlife habitat disruption. In as much as it has become optimal for investment in hydropower dam construction, the scourge for dam failure is still eminent, which is as a result of excessive seepage compromising the integrity of the mechanical properties of the dam. The aim of the paper is to highlight successful application methods in joint bonding to avoid excessive seepage and reduce the autogenous healing to a few years of operation. In view of optimization, this paper presents a comprehensive study on the influences of interlayer joints bonding quality from RCC mix performances and how it consolidates the RCC layers to withstand the shear strength along the interface, especially on the high dams. The case study is the RCC dam at the 750 MW Kafue Gorge Lower Hydropower Station. The scope of the study reviews the joint type judged by Modified Maturity Factor (MMF) with joint surface long time exposed in regions with dry and high temperature, technical measures of layer bonding quality control under condition of long time joint surface exposure, effects of joints shear strength and impermeability of the RCC layers when under the conditions of plastic and elasticity. The subtle observations made during the dam construction phases were with respect to the optimal use of materials in relation to RCC mix designs and the basis for equipment calibration for monitoring important data that can be referenced during analysis of shear forces acting on the RCC dam over time.

关键词： seepage Roller Compacted Concrete (RCC) Mix RCC Joint Exposure Time Modified Maturity Factor (MMF) Dry and High Temperature Area RCC Joint Bonding Quality Control Measures Impermeability Shear Forces

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COMPOSITE ELEMENT METHOD FOR seepage ANALYSIS OF GEOTECHNICAL STRUCTURES WITH DRAINAGE HOLE ARRAY

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Journal of Hydrodynamics 2004年第3期16卷 260-266页

作者： CHENSheng-hong XUQing HUJing StateKeyLaboratoryofWaterResourcesandHydropowerEngineeringScience WuhanUniversityWuhan430072 CollegeofEnvironmentScienceandEngineering HohaiUniversityNanjing210098China SchoolofWaterResourcesandHydropower WuhanUniversityWuhan430072China

Air element concept and Composite Element Method (CEM) were introduced inthis paper firstly, and then an explicit drainage holes element model was developed. The mainadvantage of the new model is that it allows drainage holes to be located within soil elements.Therefore the mesh generation of complicated geotechnical structures with a large number of seepagedrainage holes becomes relatively convenient and feasible. This will further facilitate the optimaldesign of seepage control system, and in this case the calculation mesh can be kept unchanged whenthe number, position and orientation of drainage holes are adjusted. The model was been implementedin software. A sluice foundation seepage control problem was studied, by which the validity and therobustness of the new model were verified.

关键词： seepage drainage hole air element composite element geotechnicalengineering

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Alluvial channel hydrodynamics around tandem piers with downward seepage

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Frontiers of Structural and Civil Engineering 2020年第6期14卷 1445-1461页

作者： Rutuja CHAVAN Wenxin HUAI Bimlesh KUMARC Department of Civil Engineering Maulana Azad National Institute of Technology BhopalBhopalMadhya Pradesh 462003India Department of Harbor School of Water Resources and Hydropower EngineeringWuhan UniversityWuhan 430072China Department of Civil Engineering Indian Institute of Technology GuwahatiGuwahati 781039India

In this paper,we report the turbulent flow structures and the scour geometry around two piers with different diameters.An experiment was conducted on a non-uniform sand bed with two types of tandem arrangements,namely,pier(T1)with a 75 mm front and 90 mm rear,and pier(T2)with a 90 mm front and 75 mm rear,with and without-seepage flows,respectively.A strong wake region was observed behind the piers,but the vortex strength diminished with downward seepage.Streamwise velocity was found to be maximum near the bed downstream of the piers and at the edge of the scour hole upstream of the piers.Quadrant analysis was used to recognize the susceptible region for sediment entrainment and deposition.Upstream of the piers near the bed,the moments,turbulent kinetic energy(TKE),and TKE fluxes were found to decrease with downward seepage,in contrast to those in a plane mobile bed without piers.The reduction percentages of scour depth at the rear pier compared with the front one were approximately 40%for T1 and 60%for T2.Downward seepage also resulted in restrained growth of scouring with time.

关键词： scour seepage Strouhal number tandem arrangement turbulent characteristics

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Numerical Method for seepage in Blocky Rock Mass

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岩石力学与工程学报 2001年第3期20卷 359-364页

作者： She Chengxue 1 Guo Yanyang 2 Wang Weiming 1 Chen Shenghong 1 ( 1 College of Hydraulic and Electric Engineering, Wuhan University, Wuhan 430072 China) ( 2 Changjiang Water Resource Commission, Wuhan 430010 China) 武汉大学湖北武汉 430072 水利部长江水利委员会湖北武汉 430010

A new finite element method for the seepage in faults or joints of blocky rock mass is presented to match the stability calculation by the block theory. The variational formulation of the finite element method in the continuum medium is modified, and the new method is established. The method is applied to calculate the seepage in rock foundation under an arch dam, and reasonable results are obtained. Because of the same mesh being used, the calculated results of seepage can be directly used to calculate the seepage load for stability calculation without any data transfer.

关键词： seepage rock mass FEM

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