剪切浓密床层孔隙网络模型与导水通道演化
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摘要
剪切作用是膏体重力浓密制备的基础要素,本文研究了浓密床层孔隙和喉道的变化对导水通道的影响,揭示了水分排出的来源与比例.开展半工业实验并结合计算机断层扫描(CT)与孔隙网络模型(PNM)提取床层微观孔隙结构,利用最大球搜索算法识别并分析剪切前后孔隙与喉道的演化规律.结果表明,添加转速为2 r·min~(-1)的剪切作用将尾砂底流浓度(即底流的固相质量分数)由55. 8%提升到58. 5%,孔隙率由43. 05%降低到36. 59%,孔隙率降低的比率为15%.通过PNM技术将孔隙空间划分为"球体"储水孔隙与"棍体"喉道;剪切后球体和棍体数量分别增加了16. 5%和22%,球体平均尺寸小幅下降,球体半径多集中在40～60μm之间.棍体平均半径由9. 83μm降低至8. 58μm,降低了12. 7%,棍体长度变化较小.剪切作用下的球体配位数在5～10的部分从25. 73%增加至44. 58%,配位明显增多,颗粒接触紧密.本文提出"球棍比"的概念用于孔隙结构的定量表征.剪切后球体体积占比由14. 14%降低至12. 75%,球体体积减少的比率达到9. 83%;棍的体积由28. 91%降低至23. 84%,棍体积减少的比率为17. 54%.球棍比由48. 91%增加至53. 48%,球棍比提升的比率达到了9. 34%,与球体体积减小相比,棍的体积减少的幅度更大,导致球棍比上升.本文从孔隙结构变化的角度揭示了全尾砂重力浓密剪切排水机理;剪排水过程中主要排出的是喉道中的水分,孔隙中的水分排出较少.
Shearing is the basic factor involved in gravity thickening of paste. This work focuses on the influence of pores and throats characteristics on water drainage channel evolution,and determines the proportion of discharged water in tailings thickener bed.Pilot-scale experiment combined with computed tomography( CT) and pore network model( PNM) technology to determine the micropore structure. The maximum ball algorithm is used to analyze the evolution of pores and throats with and without shearing. The results show that the tailings underflow concentration increases from 55. 8% to 58. 5% under 2 r·min~(-1) rake shearing and the porosity decreases from 43. 05% to 36. 59%,the decrease rate of porosity is 15%. The pore structure can be divided into two types,i. e.,"balls"and"sticks,"by the PNM technology. The quantity of"balls"and"sticks"increases by 16. 5% and 22%,respectively. However,the average radius of balls decreases slightly in the range of 40-60 μm under shearing. The average radius of sticks decreases from9. 83 μm to 8. 58 μm,i. e.,by 12. 7%. Nevertheless,the length of sticks exhibits only a slight change. The coordination number of balls increases significantly from 25. 73% to 44. 58% in the range of 5-10 under shearing,and the particles are in close contact. The concept of"the volume ratio of pores to balls"is proposed for the quantitative characterization of the pore structure. The volume fraction of balls decreases from 14. 14% to 12. 75%,the decrease rate of volume fraction is 9. 83%,and volume fraction of sticks decreases from 28. 91% to 23. 84%,the decrease rate of volume fraction is 17. 54%. The volume ratio of balls to sticks increases from48. 91% to 53. 48%,and increase rate of it is 9. 34%. When the volume decrease of balls is more than that of sticks,the volume ratio of balls to sticks increases. This work reveals the shearing drainage mechanism of unclassified tailings gravity thickening from the perspective of pore structure change,i. e.,the drainage is mainly discharged from the throat more than the pore from the tailings thickener bed shear dewatering process.
Shearing is the basic factor involved in gravity thickening of paste. This work focuses on the influence of pores and throats characteristics on water drainage channel evolution,and determines the proportion of discharged water in tailings thickener bed.Pilot-scale experiment combined with computed tomography( CT) and pore network model( PNM) technology to determine the micropore structure. The maximum ball algorithm is used to analyze the evolution of pores and throats with and without shearing. The results show that the tailings underflow concentration increases from 55. 8% to 58. 5% under 2 r·min~(-1) rake shearing and the porosity decreases from 43. 05% to 36. 59%,the decrease rate of porosity is 15%. The pore structure can be divided into two types,i. e.,"balls"and"sticks,"by the PNM technology. The quantity of"balls"and"sticks"increases by 16. 5% and 22%,respectively. However,the average radius of balls decreases slightly in the range of 40-60 μm under shearing. The average radius of sticks decreases from9. 83 μm to 8. 58 μm,i. e.,by 12. 7%. Nevertheless,the length of sticks exhibits only a slight change. The coordination number of balls increases significantly from 25. 73% to 44. 58% in the range of 5-10 under shearing,and the particles are in close contact. The concept of"the volume ratio of pores to balls"is proposed for the quantitative characterization of the pore structure. The volume fraction of balls decreases from 14. 14% to 12. 75%,the decrease rate of volume fraction is 9. 83%,and volume fraction of sticks decreases from 28. 91% to 23. 84%,the decrease rate of volume fraction is 17. 54%. The volume ratio of balls to sticks increases from48. 91% to 53. 48%,and increase rate of it is 9. 34%. When the volume decrease of balls is more than that of sticks,the volume ratio of balls to sticks increases. This work reveals the shearing drainage mechanism of unclassified tailings gravity thickening from the perspective of pore structure change,i. e.,the drainage is mainly discharged from the throat more than the pore from the tailings thickener bed shear dewatering process.
引文
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[4]Y lmaz T,Ercikdi B,Deveci H.Utilisation of construction and demolition waste as cemented paste backfill material for underground mine openings.J Environ Manage,2018,222:250
[5]Shan Z Y,Su Y S.Study on the broken depth of floor failure on the mining face with paste filling.J Henan Polytech Univ Nat Sci,2012,31(1):35(单智勇，苏勇松．膏体充填工作面底板破坏深度研究．河南理工大学学报:自然科学版，2012,31(1):35)
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[7]Yin S H,Shao Y J,Wu A X,et al.Association analysis of expansion crack development characteristics and uniaxial compressive strength property of sulphide-containing backfill.Chin J Eng,2018,40(1):9(尹升华，邵亚建，吴爱祥，等．含硫充填体膨胀裂隙发育特性与单轴抗压强度的关联分析．工程科学学报，2018,40(1):9)
[8]Cao S,Song W D,Yilmaz E.Influence of structural factors on uniaxial compressive strength of cemented tailings backfill.Constr Build Mater,2018,174:190
[9]Cao S,Song W D,Xue G L,et al.Mechanical characteristics variation of stratified cemented tailing backfilling and its failure modes.J China Univ Min Technol,2016,45(4):717(曹帅，宋卫东，薛改利，等．分层尾砂胶结充填体力学特性变化规律及破坏模式．中国矿业大学学报，2016,45(4):717)
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[11]Liu L,Zhu C,Chen G L,et al.Erosion mechanism of sulfurbearing tailings in micro-scale.J Xi’an Univ Sci Technol,2018,38(4):553(刘浪，朱超，陈国龙，等．微观尺度下含硫尾砂胶结充填体侵蚀机理．西安科技大学学报，2018,38(4):553)
[12]Sun W,Hou K P,Yang Z Q,et al.X-ray CT three-dimensional reconstruction and discrete element analysis of the cement paste backfill pore structure under uniaxial compression.Construction Building Mater,2017,138:69
[13]Yang B H,Wu A X,Miao X X.3D micropore structure evolution of ore particles based on image processing.Chin J Eng,2016,38(3):328(杨保华，吴爱祥，缪秀秀．基于图像处理的矿石颗粒三维微观孔隙结构演化．工程科学学报，2016,38(3):328)
[14]Sun W,Wu A X,Hou K P,et al.Application of X-Ray CTtechnology in the pore structure study of subsidence area backfilling body.Rock Soil Mech,2017,38(12):3635(孙伟，吴爱祥，侯克鹏，等．基于X-Ray CT试验的塌陷区回填体孔隙结构研究．岩土力学，2017,38(12):3635)
[15]Wu D,Fall M,Cai S J.Numerical modelling of thermally and hydraulically coupled processes in hydrating cemented tailings backfill columns.Int J Min Reclamation Environ,2014,28(3):173
[16]Miao X X.Dual Pore-system Ore Aggregates Characterization and Leaching Behaviours Modelling[Dissertation].Beijing:University of Science and Technology Beijing,2018(缪秀秀．双尺度孔隙结构矿堆精细表征及浸矿多场耦合模型研究[学位论文]．北京:北京科技大学，2018)
[17]Wang X M,Zhao J W.Optimal flocculating sedimentation parameters of unclassified tailings slurry.J Cent South Univ Sci Technol,2016,47(5):1675(王新民，赵建文．全尾砂浆最佳絮凝沉降参数．中南大学学报(自然科学版)，2016,47(5):1675)
[18]Liu X J,Zhu H L,Liang L X.Digital rock physics of sandstone based on micro-CT technology.Chin J Geophys,2014,57(4):1133(刘向君，朱洪林，梁利喜．基于微CT技术的砂岩数字岩石物理实验．地球物理学报，2014,57(4):1133)
[19]Li Y L,Zhang Y F,Cong L,et al.Application of X-CT scanning technique in the characterization of micro pore structure of tight sandstone reservoir:Taking the Fuyu Oil Layer in Daan Oilfield as an Example.J Jilin Univ Earth Sci Ed,2016,46(2):379(李易霖，张云峰，丛琳，等．X-CT扫描成像技术在致密砂岩微观孔隙结构表征中的应用:以大安油田扶余油层为例．吉林大学学报:地球科学版，2016,46(2):379)
[20]Song D Y,He K K,Ji X F,et al.Fine characterization of pores and fractures in coal based on a CT scan.Nat Gas Ind,2018,38(3):41(宋党育，何凯凯，吉小峰，等．基于CT扫描的煤中孔裂隙精细表征．天然气工业，2018,38(3):41)
[21]Al-Kharusi A S,Blunt M J.Network extraction from sandstone and carbonate pore space images.J Pet Sci Eng,2007,56(4):219
[22]Su N.Three-Dimensional Reconstruction of Microscopic Pore Structure in Low-Permeability Reservoir[Dissertation].Chengdu:Southwest Petroleum University,2011(苏娜．低渗气藏微观孔隙结构三维重构研究[学位论文]．成都:西南石油大学，2011)
[23]Wang D X.The Research of Digital Core Network Extraction Based on Micro-CT Images[Dissertation].Changchun:Jilin U-niversity,2015(王冬欣．基于Micro-CT图像的数字岩心孔隙级网络建模研究[学位论文]．长春:吉林大学，2015)
[24]Wu A X,Wang Y,Wang H J.Effect of rake rod number and arrangement on tailings thickening performance.J Cent South Univ Sci Technol,2014,45(1):244(吴爱祥，王勇，王洪江．导水杆数量和排列对尾矿浓密的影响机理．中南大学学报:自然科学版，2014,45(1):244)
[2]Wang H J,Zhou X,Wu A X,et al.Mathematical model and factors of paste thickener rake torque.Chin J Eng,2018,40(6):673(王洪江，周旭，吴爱祥，等．膏体浓密机扭矩计算模型及其影响因素．工程科学学报，2018,40(6):673)
[3]Guo L J,Xu W Y,Shi C X.Application of the stockpile tailings cemented filling technology on abandoned cavity treatment.China Min Mag,2014,23(Suppl 2):194(郭利杰，许文远，史采星．堆存尾砂胶结充填处理废弃采空区的应用实践．中国矿业，2014,23(增刊2):194)
[4]Y lmaz T,Ercikdi B,Deveci H.Utilisation of construction and demolition waste as cemented paste backfill material for underground mine openings.J Environ Manage,2018,222:250
[5]Shan Z Y,Su Y S.Study on the broken depth of floor failure on the mining face with paste filling.J Henan Polytech Univ Nat Sci,2012,31(1):35(单智勇，苏勇松．膏体充填工作面底板破坏深度研究．河南理工大学学报:自然科学版，2012,31(1):35)
[6]Khaldoun A,Ouadif L,Baba K,et al.Valorization of mining waste and tailings through paste backfilling solution,Imiter operation,Morocco.Int J Min Sci Technol,2016,26(3):511
[7]Yin S H,Shao Y J,Wu A X,et al.Association analysis of expansion crack development characteristics and uniaxial compressive strength property of sulphide-containing backfill.Chin J Eng,2018,40(1):9(尹升华，邵亚建，吴爱祥，等．含硫充填体膨胀裂隙发育特性与单轴抗压强度的关联分析．工程科学学报，2018,40(1):9)
[8]Cao S,Song W D,Yilmaz E.Influence of structural factors on uniaxial compressive strength of cemented tailings backfill.Constr Build Mater,2018,174:190
[9]Cao S,Song W D,Xue G L,et al.Mechanical characteristics variation of stratified cemented tailing backfilling and its failure modes.J China Univ Min Technol,2016,45(4):717(曹帅，宋卫东，薛改利，等．分层尾砂胶结充填体力学特性变化规律及破坏模式．中国矿业大学学报，2016,45(4):717)
[10]Yang Z Q,Wang Y Q,Gao Q,et al.Test research on cemented filling body strength of mixed filling aggregate in Jinchuan Nickel mine.J Henan Polytech Univ Nat Sci,2015,34(2):171(杨志强，王永前，高谦，等．金川镍矿混合充填集料胶结充填体强度试验研究．河南理工大学学报(自然科学版)，2015,34(2):171)
[11]Liu L,Zhu C,Chen G L,et al.Erosion mechanism of sulfurbearing tailings in micro-scale.J Xi’an Univ Sci Technol,2018,38(4):553(刘浪，朱超，陈国龙，等．微观尺度下含硫尾砂胶结充填体侵蚀机理．西安科技大学学报，2018,38(4):553)
[12]Sun W,Hou K P,Yang Z Q,et al.X-ray CT three-dimensional reconstruction and discrete element analysis of the cement paste backfill pore structure under uniaxial compression.Construction Building Mater,2017,138:69
[13]Yang B H,Wu A X,Miao X X.3D micropore structure evolution of ore particles based on image processing.Chin J Eng,2016,38(3):328(杨保华，吴爱祥，缪秀秀．基于图像处理的矿石颗粒三维微观孔隙结构演化．工程科学学报，2016,38(3):328)
[14]Sun W,Wu A X,Hou K P,et al.Application of X-Ray CTtechnology in the pore structure study of subsidence area backfilling body.Rock Soil Mech,2017,38(12):3635(孙伟，吴爱祥，侯克鹏，等．基于X-Ray CT试验的塌陷区回填体孔隙结构研究．岩土力学，2017,38(12):3635)
[15]Wu D,Fall M,Cai S J.Numerical modelling of thermally and hydraulically coupled processes in hydrating cemented tailings backfill columns.Int J Min Reclamation Environ,2014,28(3):173
[16]Miao X X.Dual Pore-system Ore Aggregates Characterization and Leaching Behaviours Modelling[Dissertation].Beijing:University of Science and Technology Beijing,2018(缪秀秀．双尺度孔隙结构矿堆精细表征及浸矿多场耦合模型研究[学位论文]．北京:北京科技大学，2018)
[17]Wang X M,Zhao J W.Optimal flocculating sedimentation parameters of unclassified tailings slurry.J Cent South Univ Sci Technol,2016,47(5):1675(王新民，赵建文．全尾砂浆最佳絮凝沉降参数．中南大学学报(自然科学版)，2016,47(5):1675)
[18]Liu X J,Zhu H L,Liang L X.Digital rock physics of sandstone based on micro-CT technology.Chin J Geophys,2014,57(4):1133(刘向君，朱洪林，梁利喜．基于微CT技术的砂岩数字岩石物理实验．地球物理学报，2014,57(4):1133)
[19]Li Y L,Zhang Y F,Cong L,et al.Application of X-CT scanning technique in the characterization of micro pore structure of tight sandstone reservoir:Taking the Fuyu Oil Layer in Daan Oilfield as an Example.J Jilin Univ Earth Sci Ed,2016,46(2):379(李易霖，张云峰，丛琳，等．X-CT扫描成像技术在致密砂岩微观孔隙结构表征中的应用:以大安油田扶余油层为例．吉林大学学报:地球科学版，2016,46(2):379)
[20]Song D Y,He K K,Ji X F,et al.Fine characterization of pores and fractures in coal based on a CT scan.Nat Gas Ind,2018,38(3):41(宋党育，何凯凯，吉小峰，等．基于CT扫描的煤中孔裂隙精细表征．天然气工业，2018,38(3):41)
[21]Al-Kharusi A S,Blunt M J.Network extraction from sandstone and carbonate pore space images.J Pet Sci Eng,2007,56(4):219
[22]Su N.Three-Dimensional Reconstruction of Microscopic Pore Structure in Low-Permeability Reservoir[Dissertation].Chengdu:Southwest Petroleum University,2011(苏娜．低渗气藏微观孔隙结构三维重构研究[学位论文]．成都:西南石油大学，2011)
[23]Wang D X.The Research of Digital Core Network Extraction Based on Micro-CT Images[Dissertation].Changchun:Jilin U-niversity,2015(王冬欣．基于Micro-CT图像的数字岩心孔隙级网络建模研究[学位论文]．长春:吉林大学，2015)
[24]Wu A X,Wang Y,Wang H J.Effect of rake rod number and arrangement on tailings thickening performance.J Cent South Univ Sci Technol,2014,45(1):244(吴爱祥，王勇，王洪江．导水杆数量和排列对尾矿浓密的影响机理．中南大学学报:自然科学版，2014,45(1):244)