Table of Content

15 September 2023, Volume 52 Issue 09

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Study on Stress Transfer Rule and Distribution of Multi-layer Vanadium Orebody Mining

CHI Xiuwen, DONG Haoran, WANG Zongying, WANG Qizhou, ZHAO Long, FAN Chunchao

2023, 52(09):  1-11. 

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Aiming at the problems of overlapping distribution of multi-layer orebodies,repeated disturbance of adjacent mining layers and complex stress distribution of surrounding rock,etc. ,theoretical analysis and numerical simulation methods are used to establish a plane model of surrounding rock stress distribution in the rectangular goaf of single-layer orebodies,and combine the numerical simulation results to fit the relationship equation between the change rate of the vertical stress peak in surrounding rock in the goaf of single-layer mine and its span,and analyze the characteristics of superposition of surrounding rock stress in multiple stopes of single-layer mine. On this basis,the type of relative position relationship of the goaf during the mining of double-layer orebody is defined,and the influencing pattern of different span and vertical distance of the goaf of double-layer mine on the characteristics of its surrounding rock stress distribution is studied. The study results show that there are four typical distribution characteristics of stress release,stress drop,stress increase and original stress in the surrounding rocks of the vanadium orebody,the larger the span of the extraction zone,the higher the stress peak,and the stress change rate in the deep surrounding rocks of the stress increase zone decreases with increasing distance from the stress peak point according to the power function relationship,and the stress change rate in the stress drop zone increases with increasing distance from the stress peak point. The stress increase zones in adjacent goafs will be superimposed in the column between them,and the stress change rate at a point in the column is the sum of the stress change rates caused by the goafs on both sides at that point. When the stress release zone in the lower goaf overlaps with the stress increase zone in the upper goaf,it will result in higher tensile stresses in the surrounding rock,and when the stress release zone in the upper goaf overlaps with either area in the lower goaf,it will result in lower compressive stresses. Significant stress changes at the intersection of the overlapping and non-overlapping areas of the upper and lower goafs. According to the stress migration patterns of multi-layer orebody mining,the strong and weak disturbance distance of the goaf is proposed,and the strongly disturbed area,weakly disturbed area and undisturbed area are divided to provide reference for determing reasonable recovery parameters and recovery sequence of multi-layer orebody mining.

Numerical Method of Grouting Reinforcement in Deep Roadway Considering Pore Characteristics of Surrounding Rock

WEN Xudong, LU Haifeng, LIU Quansheng, LIU Bin, WU Yuexiu

2023, 52(09):  12-23. 

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Grouting reinforcement can effectively improve the environment of fracture development in deep mining area, and ensure the stability of roadway surrounding rock and safe mining in mining area. Based on the grouting reinforcement project of mudstone roadway in Gubei Coal Area in Huainan Mining Area,the relationship between the pore characteristics of surrounding rock and the mechanical properties of grouting consolidation body was studied by scanning electron microscope test and mechanical properties test of grouting consolidation body. On this basis,the Mohr-Coulomb constitutive model of consolidation body was modified. Based on FLAC3D software,the numerical simulation analysis method of grouting reinforcement evaluation considering the pore characteristics of surrounding rock was developed,and the grouting reinforcement effect of roadway group in mining area was calculated. The results show that the porosity of rock mass has a great influence on the strength and deformation characteristics of grouting consolidation body. The elastic modulus and cohesion of the consolidation body are logarithmically increasing with the porosity,and the internal friction angle decreases with the increase of porosity. There are two cementation modes of wrapped and overlapped grouting consolidation body. The numerical simulation results of roadway group show that the subsidence displacement of tunnel vault,convergence displacement of two sides and floor heave displacement are the most obvious without grouting. With the increase of grouting consolidation time,the deformation of each part tends to be stable,which verifies that this method can well characterize the grouting reinforcement effect. The research results can provide analysis and evaluation methods for grouting reinforcement design and construction of coal mine roadway.

Study on Modification and Ratio Optimization of Unclassified Tailings Filling Material in a Gold Mine

CHEN Hexin, HU Liqiang

2023, 52(09):  24-28. 

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Aiming at the problems of large deformation and low strength of the filling material of a gold mine,the strength and shrinkage performance of the total tailings filler were improved by adding compound admixture,and the optimal ratio of admixture was obtained. The composite materials selected in the experiment included slag fiber,fly ash,quicklime,cement and tailing sand. The optimal proportion of additives was determined by orthogonal test. The microscopic mechanism of the modified materials was studied by means of mineral diffraction and scanning electron microscopy. The results show that the best filling material ratio is 1. 6% fiber content,0. 5% fly ash content,10. 0% quick lime content and 20. 0% cement content. The flexural strength and compressive strength of the modified packing are increased by 3. 8 and 1. 6 times respectively,and the shrinkage rate is reduced by 120%. XRD patterns show that different mineral compositions change with increasing curing age,which reflects the whole process of hydration reaction. The SEM scanning images clearly showed that the pores of the filler were full of cement and quicklime particles,and the slag fiber adsorbed a large number of solution gel products,which explained the reason for the improvement of strength and shrinkage properties from the perspective of microscopic mechanism,indicating that the increase in strength and shrinkage properties was due to the addition of additives to change the original microstructure and the formation of gelling products.

Experimental Study on Shear Properties of Sandstone under Osmotic Water Pressure

HU Bin, DING Jing, LI Jing, CUI Kai, MA Liyao, TANG Qi

2023, 52(09):  29-36. 

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The mechanism of water-rock interaction is a key problem in the study of slope long-term stability. Aiming at the problem that the seepage damage mechanism of slope rock mass is unclear due to the difference between the test design and the research object in the current water-rock interaction study and the actual engineering practice,the shear test of water-saturated sandstone under high pressure seepage is carried out by using the rock shear-seepage coupling test device independently developed. The effects of osmotic water pressure on shear strength,shear section failure and normal stress-deformation of sandstone were investigated. The results show that the mechanical properties of sandstone are degraded by osmotic water pressure, and the shear strength,peak normal deformation and peak shear deformation of sandstone are decreased with the increase of osmotic water pressure. When the shear stress of sandstone reaches the yield point,the shear stress will be affected by the crack connection and produce different degrees of shear stress drop. In the yield failure stage,there is a corresponding relationship between the normal deformation and the change of normal stress at the time point,and their change law reflects the propagation of the internal crack in the sandstone at this stage. In the shear process,the secondary cracks appear symmetrically. With the increase of osmotic water pressure,the secondary cracks gradually reduce or even disappear,and the shear section tends to be flat. The study results can lay a foundation for long-term stability study of high slope under continuous heavy rainfall.

Study on Shear Failure and Acoustic Emission Characteristics of Anchored Anisotropic Structural Plane

GAO Junqiang, LIU Guangjian, DU Shigui, JIA Ruifeng, WANG Kangyu, XU Yudong

2023, 52(09):  37-46. 

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There are structural planes with different lithology on both sides in nature,and anchors are commonly used in engineering to inhibit the sliding of structural planes. In order to study the direct shear characteristics of anchored anisotropic structural plane,the direct shear experiment was carried out. Combined with the results of acoustic emission monitoring,the shear strength,failure type and crack evolution law of the anchored anisotropic structural plane are discussed. The results show that:With the increase of the strength of the weak sidewall rock in the anisotropic structural plane with anchor, the shear strength increases nonlinearly. The shear strength of the structural plane with anchor increases by 200%,267% and 303% respectively compared with that without anchor. The failure types are shear,tensile shear and splitting,and the main crack direction is basically the same as the shear direction;The shear-displacement curve of anchoring anisotropic structural plane is divided into four stages:compaction,elasticity,yield and failure. In the compaction stage,the anchoring agent is squeezed and destroyed. In the elastic stage,cracks appear at the extrusion position of rock mass and anchor bolt. In the yield stage,the anchor bolt undertakes the main shear resistance and deforms. In the failure stage, the rock sample is cut and broken. When the strength of the weak side rock of the structural plane is low,the acoustic emission events are concentrated in the elastic stage. When the strength of the wall rock is high,the acoustic emission events are concentrated in the yield stage;With the increase of strength of weak sidewall rock in structural plane,when λ<1 rock specimen produces large-scale shear cracks,when λ≥ 1 rock specimen produces small-scale shear cracks.

Rock Thermal Infrared Image Tension-shear Crack Detection Based on Improved Faster RCNN

HUANG Xiaohong, LU Ye ZHANG Rundong DONG Shiqi

2023, 52(09):  47-53. 

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Distinguishing rock failure modes is of great significance for mine disaster prevention and control. In order to effectively identify rock failure modes and monitor the failure process,a strain shear crack detection algorithm based on improved Faster RCNN in rock thermal infrared images is proposed. Firstly,the uniaxial compression test of granite was carried out,and the thermal infrared image of rock fracture was obtained by infrared imager,and the infrared fracture data set of rock was made. Then,the Faster RCNN network model is improved,and the feature extraction method is optimized by introducing the attention-guided context feature pyramid network. A cascade structure is adopted to improve the accuracy of detection frame regression. At the same time,the infrared rock fracture data set is used to train and verify the model. Finally,the tensile shear crack identification is carried out in infrared image of measured rock. The experimental results show that the detection accuracy of the algorithm reaches 94. 15%,the detection frame number per second is 19. 27 fps,and the comprehensive performance is significantly improved. The research results can provide a way to predict the rock fracture location and fracture mode.

Study on the Dominant Impact Crushing Angle of Oil Shale under the Influence of Stratigraphic Angle

GAN Ze, LI Fuping, YANG Xi, GAN Deqing

2023, 52(09):  54-62. 

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Oil shale contains a large number of stratification structures. The variation of stratification angle can cause a large difference in crushing form and crushing size. In order to clarify the dominant impact crushing angle,crushing form and particle characteristic under the influence of stratification angle,sieving test,oil content determination,electron microscope scanning analysis and numerical simulation were carried out. The results showed that oil shale particles in the range of 3~ 1 mm particle size have high oil content,which is the advantageous particle size range for oil shale particle crushing. The form of oil shale fragmentation is influenced by the stratigraphic structure,and the crushing forms can be divided into five types under different stratification angles, namely, splitting damage through layers, shearing damage through layers, through-layer damage, shearing damage and splitting type of shear tensioning damage. At 70°,80° and 90° stratification angles,the particle size of crushed oil shale is smaller,and the content of dominant particle size reaches more than 40%. Among them,the dominant particle size content is the highest at 80°,and the uniformity of oil shale particles is better at 90°. It can be considered that the dominant impact crushing angle of oil shale is 80° ~ 90°. The particle size distribution function of oil shale after crushing is essentially a description of the fractal distribution. On this basis,the Weibull distribution function model is used to quantitatively describe its crushing particle size,and the results are more accurate.

Multi-period Overall Optimization of Internal Dumping Short-term Programming by Truck in Open-pit Mine

ZHAO Ming, WANG Zhongxin, XIN Fengyang, WANG Jinjin, ZENG Xiangyu

2023, 52(09):  63-68. 

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In order to further optimize the stacking sequence of rock and soil mass in open-pit dump and reduce transportation costs,an optimization algorithm for the stacking sequence of rock and soil mass in open-pit dump is proposed,which is oriented to the internal dumping transport of trucks and takes into account the dynamic changes of mining and stripping. The dumping position is represented by a block,and the mining and stripping position is represented by a solid model. The transport distance is calculated according to the coordinates of the entity centroid point of the mining and stripping position in each period,the centroid point coordinates of the dumping block body and the length of the working line. The transport distance is corrected considering the actual situation,and then the transport cost from the mining and stripping position to the dumping block in each period is calculated according to the transport cost. The time dimension is added to the abandoned block,and the time segment transportation cost is calculated. Based on the objective function of minimizing the total transport cost of the stripping material,the internal discharge planning model was constructed by taking the spatio-temporal development relationship,safe distance and discharge volume of the dump as constraint conditions. 0-1 integer programming was used to solve the model at one time in multiple periods,and the optimal stacking sequence of rock and soil mass in the inner dump was obtained. Taking an open-pit mine as an example,the proposed algorithm is used to optimize the stacking sequence of rock and soil masses in the mine′s internal dump. The optimization results show that:the total stripping transport cost of the optimal soil discharge planning scheme is 920. 994 1 million yuan,which saves 12. 841 7 million yuan compared with the original design scheme,and achieves the optimization goal of the optimal time and location of the soil mass discharge in the inner dump. The research results further reflect that:on the basis of the completion of the design of the waste dump,the deep excavation of the spatial and temporal development relationship of the waste dump engineering and the overall optimization of the multi-period waste dump planning are proposed,which has certain reference significance for the development of scientific and reasonable waste dump planning.

Optimization Design of Microseismic Monitoring Scheme for High Steep Rock Slope and Identification of Hidden Danger Zones

ZHANG Wenge, WANG Jiachuang, DONG Longjun, GONG Suwen, LUO Caiyan, HAO Chenliang, CAO Heng, YAN Xianhang

2023, 52(09):  69-75. 

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Ground pressure monitoring is a key link in mine safety management and an effective monitoring method in the development of mineral resources. According to the geological conditions and ground pressure activity of Sifang Gold Mine in Shaanxi Province,in order to improve the recovery rate of resources,effectively control the ring slope of the mine surface,and solve the key problems of safe and green mining,the ideal positioning errors of different layout schemes are analyzed according to the characteristics of mine production and the basic requirements of sensor layout. The monitoring scheme of ground pressure system which meets the requirements of mine monitoring is analyzed and designed from the economic point of view. In order to further explore the weak and abnormal areas of the mine slope and determine the regional stability of the slope,this paper uses wave velocity field imaging technology to obtain the imaging results of the low-speed dangerous area and high-speed dangerous area of the slope monitoring profile. Furthermore,the advanced identification and monitoring effect analysis of the hidden cavity abnormal area inside the slope body is realized. The results show that under ideal conditions,when a certain monitoring point is set at different elevations,the difference in volume positioning error is not obvious. Combining with the relative wave velocity field imaging results of the mine slope area where the monitoring source is monitored,based on the current station network layout scheme,it can meet the needs for identification of dangerous areas within the mine slope monitoring profile. This research results is of great significance for reducing the occurrence of mining disaster accidents and improving the stability of mine safety and production.

Stability Analysis of Artificial Soil-rock Mixed Slope Considering Block Size and Distribution

LI Zhihui, YANG Xiaobin, YUAN Wenjie, LÜ Xiangfeng, LIU Tenghui, ZHAO Yuting, ZHANG Zewen, XIAO Desheng

2023, 52(09):  76-82. 

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In order to explore the influence of block size and distribution on slope stability in artificial soil-rock mixed slope,the different block sizes,block spacing,block profile and other parameters of the soil-rock mixed slope model are scripted in Python language,and realizing the random generation of block size and distribution of soil-rock mixed slope. The model is imported into ABAQUS software to generate the numerical calculation model of soil-rock mixed slope. The stability of the soilrock mixed slope is calculated and the influence rule of rocks with different sizes and distribution conditions on the stability of soil-rock mixed slope is revealed using numerical simulation. The results show that under the condition of the same rock proportion and the block size range is 10~ 50 cm,the safety factor of the soil-rock mixed slope increases gradually with the increase of block size,the plastic failure zone becomes wider and longer,and the stability of soil-rock mixed slope increases. When 10~ 20 cm and 30~ 40 cm block stones exist in the soil-rock mixed slope at the same time,the closer the distribution of large-size rocks to the bottom,the higher the safety factor of the soil-rock mixed slope,the plastic failure zone of soil-rock mixed slope becomes wider,and the slope stability increases. The research results can provide reference for the construction of artificial soilrock mixed slope.

Reduction Kinetics of Hematite in CO and H₂ Atmosphere and the Mechanism Study of Mineral Phase Transformation

LI Xinyu, YUAN Shuai, GAO Peng, WANG Ruofeng, ZHANG Honghao, LI Yanjun

2023, 52(09):  83-89. 

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Mineral phase transformation experiments under CO and H2 atmosphere were carried out for hematite in order to perform kinetic analysis of the reduction process,and the phase transformation and microstructural changes were studied by X-ray diffraction and scanning electron microscopy in order to compare the differences in the mineral phase transformation effects of CO and H 2 and the microstructural evolution patterns. The results showed that the increase of the mineral phase transformation temperature could significantly accelerate the reaction rate in the temperature range of 460 ~ 620 ℃ . In CO atmosphere,the best reation model of the reaction kinetics is shrinkage core model,the integral form is G(α) = 1 - (1 - α)1/ 2,the reation activation energy is 8. 35 kJ / mol,and the finger front factor is 0. 21 min-1. In H2 atmosphere,the best reation model of the reaction kinetics is shrinkage core model. The integral form is G(α) = 1 - (1 - α)1/ 3,the reation activation energy is 20. 73 kJ / mol,and the finger front factor is 4. 37 min-1. The SEM analysis results showed that in the process of mineral phase transformation,adsorption of reducing gas and transformation of hematite occur preferentially at the surface and cracks of hematite particles,and the reaction proceeds gradually inward from the surface and cracks of particles,and the cracks generated by temperature stress and phase-transformation stress provide channels for gas diffusion,which is conducive to the internal diffusion of reducing gas and gas products in the particles and accelerates the reaction. Under the same test conditions,the mineral phase transformation effect of H2 is better than that of CO. The results of the study can provide theoretical support for the regulation of the mineral phase transformation process of hematite under H2 and CO atmosphere.

Study on the Effect of Calcium Ion on the Flotation Behaviors of Scheelite and Its Regulation

SUN Wenjuan, HAN Haisheng, ZOU Qin, CHEN Wensheng

2023, 52(09):  90-97. 

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The surface properties and flotation behaviors of scheelite are affected by metal ions in the pulp. In order to investigate the effect of calcium ions on scheelite flotation and its regulation methods,flotation tests of scheelite and calcite in the presence of calcium ions with different pH adjusters were carried out,and the mechanism was analyzed by XRD,particle size analysis,infrared spectroscopy,and adsorption amount tests. The results showed that when the pH was adjusted to 10 by sodium carbonate in calcium ions slurry,the flotation recovery of scheelite was only 11. 40%,which was 46. 73 percentage points lower than the flotation recovery when sodium hydroxide was utilized. The addition of sodium fluoride boosted the flotation recovery of scheelite from 20. 46% to 76. 01% when pH was adjusted to 9. 50 with sodium carbonate for scheelite flotation. The mechanism studies showed that when sodium carbonate was used to adjust the pH of calcium ions slurry,a large amount of calcium carbonate nanoparticles was generated in the slurry,and the Pb-BHA collectors chemisorbed on their surfaces with a higher adsorption amount than that of scheelite. After the addition of sodium fluoride,the nano-calcium carbonate surface was transformed to generate calcium fluoride,and the adsorption amount of the collectors on its surface was significantly reduced. The nano-calcium carbonate generated when sodium carbonate was used in high-calcium ions slurry competed with scheelite surface for adsorption of collectors in flotation,which made the flotation of scheelite worse. Sodium fluoride promoted the surface conversion of calcium carbonate nanoparticles to calcium fluoride and reduced the adsorption of collectors on their surfaces,thus eliminating their unfavorable effect on scheelite flotation.

Experimental Study of Novel Surfur Depressant HD12 Replacing Lime

WANG Tichen, DENG Jiushuai, LU Yu, SUN Zhenwu, ZHU Kaishun, ZHU Xuanfei

2023, 52(09):  98-102. 

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The zinc sulfide ores in Ximeng area of Inner Mongolia contains zinc of 1. 46% and iron of 22. 07%. The main metallic minerals in ores are sphalerite,magnetite,pyrite and pyrrhotite. The gangue minerals in ores are mainly quartz,calcium iron garnet,calcite,mica and amphibole. In order to solve the safety and environmental problems caused by the large amount of lime used in the flotation process of the ore,an novel surfur depressant HD12 was used to replace lime and the beneficiation experiment was carried out. The appropriate reagent system was determined by condition tests as follow:HD12 of 10 g / t,copper sulfate of 240 g / t,sodium butyl xanthate of 80 g / t in the grinding fineness of -0. 074 mm accountng for 75%. On this basis, the closed-circuit flotation process of " one roughing flotation,two cleaning flotation and three scavenging flotation" was adopted to treat the ore. Finally,the zinc concentrate with Zn grade of 50. 04% and Zn recovery rate of 88. 97% could be obtained. The efficient recovery of zinc resources from the zinc sulfide ores is realized. Using HD12 as a sulfur inhibitor,the zinc separation index is excellent,and the dosage of the reagent is significantly reduced,which could replace lime for the separation of sphalerite from pyrite and magnetite.

Study of Diversity in Surface Properties and Floatability of Different Minerogenetic Pyrites

DUAN Wenting, DENG Rongdong, MA Yingqiang, LIU Wenyuan, YANG Yuankun

2023, 52(09):  103-110. 

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Aiming at high sulfur epithermal pyrite (HSEP) and porphyry pyrite (PP) in the middle and upper ore zone of a deposit in Serbia,the surface characteristics and floatability were studied by X-ray diffraction,pure mineral flotation test, contact angle measurement,Zeta potential test and infrared spectrum test. The results showed that the Fe / S ratio of HSEP and PP are 0. 49 and 0. 47,respectively. HSEP grows with the preferred orientation of (210) and (211) crystal faces,while PP grows with the preferred orientation of (220) and (311) crystal faces. The natural floatability of HSEP is better than that of PP. With the increase of pulp pH value,the floatability of HSEP and PP gradually decreases,and the difference between them gradually decreases. The sensitivity of PP was higher when the dosage of butyl xanthoxanthate was low,and there was no significant difference in floatability between the two pyrites with the increase of dosage. The floatability of HSEP was better than that of PP when ammonium butylated black was used as collector,and the floatability difference of the two pyrites was increased under different pH conditions. PP is more easily inhibited by starch,while when lime is used to inhibit pyrite,the difference of flotability between the two pyrite gradually decreases with the increase of pH value. When pH is of 12,there is no significant difference in flotability between the two pyrites and they are completely inhibited. Under different copper sulfate dosage and pulp pH value,the floatability of the two kinds of pyrite is obviously different. Increasing the amount of collector and sulfuric acid has better effect on HSEP activation.

Experimental Study on Beneficiation of A Antimony Sulfide Ore in Yunnan

HE Mingfei, TANG Youyou, JIA Min, LI Guojun, WEI Shuntao, PAN Wenzhou

2023, 52(09):  111-116. 

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In order to efficiently exploit and utilize an antimony sulfide ore in Yunnan Province,a detailed beneficiation experiment was conducted on the basis of the process mineralogy study of the raw ore. The results showed that the grade of the main valuable element antimony in the ore is 2. 16%,and the antimony mainly exists in the form of sulfide with the oxidation rate of 4. 15%. The antimony mineral is mainly stibnite,the sulfide is mainly pyrite,and the gangue mineral is mainly quartz, sericite and calcite. The distribution size of stibnite is coarse,mainly in the range of 0. 02~ 2. 56 mm. When the grinding fineness of -0. 074 mm is accounting for 74. 56%,the monomer separation degree of stibnite is greater than 90%. Based on the research results of ore properties,under the condition of grinding fineness of -0. 074 mm accounting for 74. 56%,using sodium hmetaphosphate as dispersant,lead nitrate as activator,M7 as collector and terpinol oil as foaming agent,antimony concentrate with a grade of 35. 30% and recovery rate of 93. 52% could be obtained after the closed-circuit flotation process of " one roughing,three cleaning and two scavenging" . The research results can provide a useful reference for the subsequent sorting of sulfide ores in middle and deep mines and the optimization of the existing process.

Geochemical Exploration Effects and Prospecting Potential in Getiaoping District of Luanchuan County,Henan Province

LI Wei, LÜ Xianhe, BAI Guodian, REN Jiande

2023, 52(09):  117-126. 

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Through 1 ∶50 000 stream sediment survey in Getiaoping area in Luanchuan County,Henan Province,the distribution pattern,enrichment and dispersion of main ore-forming elements were summarized. It was found that there were local enrichment phenomena of Mo,W,Au,Ag,Cu,Pb,Zn and other ore-forming elements,especially the enrichment coefficient (K) of Mo element was the highest (1. 53) in the whole area. On the basis of comprehensive analysis of regional metallogenic geological conditions,1 ∶10 000 soil geochemical survey was deployed to the optimal AS-33 comprehensive anomaly. The Mo anomaly has good recurrence,and is associated with W,Cu and other elements combination,showing horizontal zonation phenomenon,and has the characteristics of hydrothermal Mo anomaly. Through trough exploration,12 molybdenum ore bodies,1 tungsten ore body and 4 tungsten mineralized bodies have been ringed,and good prospecting results have been obtained. Based on the above analysis results,the comprehensive prospecting model of molybdenum ore is established,and five prospecting targets of tungsten,molybdenum,lead and zinc polymetallic ore are delineated. It has certain reference value for the prospecting of molybdenum and tungsten ore in Luanchuan area.

Filtering Method of the Pit Dense Point Cloud Based on Peripheral Elastic Constraint

XIONG Hexi SUN Jiuyun YAN Zhigang ZHANG Xinnai

2023, 52(09):  127-133. 

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In view of the characteristics of complex terrain,steep pit wall and dense thickets of the pit,it is difficult to obtain a fine DEM by traditional DEM acquisition and processing methods. Referring to the idea of cloth simulation filtering,an elastic constraint filtering algorithm for a pit dense point cloud of oblique photogrammetry is proposed in this paper. Based on the optimization of filtering grid,the concave terrain is differentiated into several elastics according to the height difference. By simulating the deformation process of elastics,the elastic meshes close to the ground is obtained,so as to separate the ground points and generate the DEM. Taking an abandoned mine in Xuzhou as an example,the proposed filtering algorithm is verified by experiments. Compared with the commonly used filtering algorithm,the accuracy of the experimental results is improved by 10. 15%. It performs well in the area with large topographic relief,and the filtering accuracy is 81. 73%. The goodness of fit between the randomly selected ground points and the interpolated elevation is 0. 830,and the root mean square error is 0. 048. The experimental results show that the method proposed in this paper has low data acquisition cost and high efficiency,and can effectively extract the pit ground points,so as to provide the high-precision pit DEM data for the mining area.

Discontinuous Deformation Analysis of Open-pit Slope Based on Photogrammetry of Unmanned Aerial Vehicle

LI Jinwei

2023, 52(09):  134-139. 

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The rock mass structural plane affects the stability of rock slope in open-pit mine to a great extent. In order to improve the accuracy of rock slope structural plane information acquisition and energy dissipation in dynamic failure process,a multi-layer and omni-directional photogrammetry method is proposed to obtain surface information of open-pit slope with the advantage of unmanned aerial vehicle (UAV) non-contact photogrammetry. Secondly,viscous damping is applied to the dynamic failure process to achieve energy dissipation,and the results are compared with the test results. Finally,the proposed method was applied to Discontinuous Deformation Analysis (DDA) of a rock slope in an open-pit mine. The study results show that the multilayer and omnidirectional UAV photogrammetry method has a good accuracy in collecting the information of slope structural surface,and the analysis results of discontinuous deformation with 2. 45% ~ 2. 53% viscous damping are basically consistent with the experimental results. The simulation results of the actual failure process of a rock slope in an open-pit mine are good, and the position of the sliding surface obtained by DDA analysis is consistent with the results of in-situ displacement monitoring. The safety factor of sliding surface is 1. 167,which is in the critical state of instability. Therefore,the overlying pre-unstable rock mass should be stripped in advance to solve the problem of landslide hazard from the source. The proposed method can also be applied to the slope body analysis with other structural plane development.

Fine 3D Reconstruction and Accuracy Analysis of Buildings Based on Ground LiDAR

BAO Guo, ZHANG Shubi, CHEN Qiang, ZHENG Youlei, CHEN Chun

2023, 52(09):  140-144. 

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With the continuous advancement of the construction of " real 3D China" and smart mines,higher requirements are put forward for the refinement of 3D models that carry the basic data of digital construction. Based on the 3D reconstruction technique of ground LiDAR,a refined 3D reconstruction method for buildings is proposed. The 3D laser scanner was used to obtain the scanning data of the building. After point cloud denoising,point cloud coloring,multi-point cloud stitching and coordinate transformation,a 3D model based on the 3D laser point cloud was constructed,and the modeling quality was evaluated from the position accuracy and texture structure information. The results show that the position accuracy of the 3D model based on ground LiDAR is high,the median error of X direction is ±0. 92 cm,the median error of Y direction is ±0. 60 cm,the median error of plane is ±1. 10 cm,and the median error of elevation is 0. 77 cm. In terms of structural texture accuracy,it can accurately express the information of the lower part of building and the interior,and the texture is fine.

Research on Key Technologies of Flotation Hydrodynamics and Equipment Intelligent Development Path

ZHANG Wei, LI Tengfei, GUAN Xiaoqiang, ZHOU Shiqing, TAN Zhiyong, LI Haibin, WANG Chao

2023, 52(09):  145-155. 

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In order to define and measure the flotation hydrodynamics key parameters precisely such as gas volume flow (Qg),superficial air flow rate ( Jg ),bubble size ( D32 ) and its distribution,bubble surface area flux ( Sb ) and gas holdup (εg),Chinalco Research Institute of Science and Technology (CRIST) develops the new generation of flotation hydrodynamic sensors system. The results showed the sensor system may model and analyze the collected data through multi-dimensional measurement of flotation equipment and the core parameters of flotation circuit,forms an optimization scheme and generates automatic operation instructions to promote the selection. The optimization and improvement of mining technology and economic indicators effectively fills the technical gap in the research and development of such equipment in the domestic mining field, creating favorable conditions for the realization of mineral processing industry 4. 0. The results of industrial application showed that the sensor system has the ability to accurately evaluate the operation efficiency of large flotation equipment,and can achieve the optimal solution of economic indicators such as metal recovery rate and concentrate grade in mine flotation process.

Fault Diagnosis of Mining Excavator Engine Based on IFOA-RotGBM

GU Qinghua, SUN Wenjing, LI Xuexian

2023, 52(09):  156-163. 

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Aiming at the complex working mechanism,low fault diagnosis efficiency and low accuracy in mining excavator engine,a fault diagnosis method of mining excavator engine based on RotGBM optimized by IFOA is proposed. Firstly,the random forest-recursive feature elimination method (RF-RFE) is utilized to extract the features from the fault data of excavator engine and eliminate redundant irrelevant features. Secondly,an improved fruit fly optimization algorithm ( IFOA) is proposed to optimize the hyper-parameter of LightGBM. Then,RotGBM is generated by combining Rotation Forest and LightGBM,and a new fault diagnosis model is constructed. Finally,the fault data of a mine excavator engine is used to verify the model,and the performance is compared with other commonly used methods. The simulation results show that the proposed method has better diagnostic performance than other diagnosis methods,and can reach 98. 31% diagnosis accuracy,0. 22% false positive rate and 2. 5% missed detection rate,which meets the requirements of fault diagnosis of mine excavator engine.

Simulation Model and Application Research of High-Pressure Grinding Rolls Based on DEM-MBD

REN Yunpeng, LI Anshuai, LI Xudong, SONG Fang

2023, 52(09):  164-172. 

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Aiming at the problems of the commonly used mathematical models and the current discrete element simulation models in predicting the processing capacity,unit energy consumption and crushing ratio of high-pressure grinding rolls (HGPR) with large errors,this paper proposes the simulation modeling analysis of HGPR using the co-simulation technology of discrete element method ( DEM) and multi-body dynamics ( MBD). Taking the KHD375ϕ1400-1000 HGPR used in Sanshandao Gold Mine,Shandong Gold Mining (Laizhou) Co. ,Ltd. ,as the research object,the key simulation parameters are set according to the relevant theory and actual equipment operation parameters,and the co-simulation is carried out by EDEM and MotionView. The simulation results are compared with the mathematical model,single EDEM simulation model and the actual operation data of the mine. The results showed that the DEM-MBD co-simulation model can simulate the operation of the HGPR more realistically and accurately. Compared with the DEM simulation model,the DEM-MBD co-simulation model reduces the error values of processing capacity,unit energy consumption and crushing ratio by 13. 41,38. 10 and 6. 74 percentage points respectively,which effectively reduces the error values of the existing simulation model. The study also provides a reasonable reference for the simulation of such complex crushing equipment,which has some engineering application value.

Study on Mine Video Monitoring Technology Based on 3D Video Fusion

MIAO Zuohua, TANG Yang, REN Lei, WANG Mengting, XIE Yuan, ZHAN Chuan, LI Hongliang

2023, 52(09):  173-179. 

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The traditional mine video monitoring has the problems of large amount of video data,poor correlation between video images,and lack of direct linkage with the three-dimensional spatial location information. It is difficult for regulators to effectively reproduce the scene and location in the face of multiple fragmented monitoring video images,which makes it impossible to solve relevant problems in time when emergencies occur,and seriously affects the timely and effective development of mine emergency rescue work. In view of the above problems,a mine video monitoring method based on three-dimensional video fusion is proposed. Using three-dimensional video fusion technology,the real-time monitoring video is used as a texture to construct a geometry,and the feature points are selected and matched to fuse with the mine three-dimensional model. On this basis,in order to make the three-dimensional video texture fusion effect better,the Laplacian grid deformation algorithm is adopted to correct the distortion of the video geometry texture. The experimental results show that the three-dimensional video fusion has a strong visual perception effect. The video and video are interrelated,and the fragmented video is integrated. The fusion of video and three-dimensional model solves the problem of non-linkage between three-dimensional space data and video,makes up for the defects of traditional video monitoring technology,and enriches the means of mine monitoring.

Study on Safety Risk Identification of Deep Foundation Pit Based on BIM and Knowledge Graph

HU Yuanyuan, LIU Junsheng, WANG Xingfeng

2023, 52(09):  180-186. 

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With the continuous expansion of the development and application scale of urban underground space,the safety risk control related to the construction and operation management of underground space projects has attracted more and more attention from the government and relevant departments. The efficient and intelligent safety risk identification of deep foundation pit has increasingly become an urgent need for professionals. According to the practical needs of deep foundation pit safety supervision,this paper constructs the overall architecture of deep foundation pit intelligent supervision based on IOT,BIM and GIS technology. A deep foundation pit safety risk identification method integrating Building Information Model ( BIM) and knowledge map is designed. This method constructs the deep foundation pit safety risk identification knowledge graph based on the deep foundation pit construction requirements,safety specifications and accident experience summary,and focuses on the knowledge discovery,knowledge extraction and knowledge construction of construction objects and related objects based on BIM model,to fully and quickly mine the entity relationships of different types of deep foundation pit construction,So as to assist in the intelligent identification of the safety risk of deep foundation pit. The example verification shows that this method can greatly improve the work efficiency of professionals,solve the problems of manual dependence and professional dependence in the process of safety identification to a certain extent,and provide some support for the rapid,efficient and accurate identification of deep foundation pit safety risks.

Study on Miner Location Algorithm Based on Radio Frequency Identification Technology

FANG Yuechun, WANG Hong

2023, 52(09):  187-192. 

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With the development of smart mining technology,more and more mines have begun to use automated equipment to replace human operations,thereby improving production efficiency and safety. In order to reduce the accuracy and increase the error caused by fluctuating signals when miners work underground in the mine,a mine location algorithm based on radio frequency identification (RFID) technology is proposed. Firstly,a location model based on the received signal strength index is established,and considering the influence of random noise in signal propagation,Log-Normal signal propagation model and Kalman filter algorithm are used to process and optimize the original signal. Secondly,a reference point optimization method based on K-Means clustering algorithm is designed to select appropriate reference points and improve the accuracy and stability of positioning. Experiments show that the proposed algorithm has a significant improvement in positioning accuracy and robustness compared with existing algorithms. This method can not only improve the working safety and efficiency of miners,but also provide more accurate and effective means for mine safety supervision and management.

Mine Fingerprint Localization Algorithm Based on Hadoop Cloud Platform

HAN Jiying, LI Fangli, ZHU Yuankai

2023, 52(09):  193-198. 

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Aiming at the current problems of the low positioning accuracy and weak real-time performance of existing mine fingerprint localization algorithms,a Hadoop cloud platform-based mine fingerprint localization algorithm is proposed. The proposed algorithm first preprocesses the multi-base station signal sources in the mine before fingerprint feature extraction to improve the reliability and robustness of the fingerprint features. Secondly,the source fingerprint signal is transformed linearly using wavelet basis functions,and the signals from multiple base stations are decomposed into frequency bands of different scales to obtain representative fingerprint feature vectors. Furthermore,for each location-based signal of the miner or mobile device,it is decomposed into several sub-signal regions,and the correlation coefficient matrix between the test signal source and the feature set is calculated for each region,based on which matching of fingerprint information is implemented. Finally,using the doppler effect and signal attenuation principle,estimate the position of each node to obtain specific location information for each node. A localization experiment is conducted on a mine in China,and the results showed that compared with mainstream fingerprint localization algorithms,the proposed mine fingerprint localization algorithm can quickly and accurately locate people or mobile devices in the mine,with high positioning accuracy and real-time performance. The proposed algorithm can be applied to practical mine safety monitoring and management,providing support for mine safety and efficient production.

Classification Damming Process and Design Method for High Concentration Tailings

LIU Xinxin SHENG Mingqiang AI Luoyan YAN Qin

2023, 52(09):  199-205. 

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In view of the lack of theoretical design methods for the classification system in the damming process of high concentration tailings ponds,13 key calculation parameters for the design of classification system were summarized by classifying the relevant parameters. Based on theoretical analysis,the theoretical calculation formulas for construction period,sediment yields and distribution rate of original tailings were put forward,the selection and quantity determination process of hydrocyclones based on separation particle size were analyzed,and the production scale of the dressing plant and the efficiency of dam construction were explained. A systematic calculation method of cyclone classification process parameters is derived,and the feasibility and effectiveness of the established calculation method are verified according to the construction practice of a high concentration discharge tailings pond. The results show that the calculation results of the underflow tailings,overflow tailings concentration,sediment yields,and the -200 mesh particle content in the underflow tailings are in good agreement with the monitoring values when the feed tailings concentration is similar to the calculated set value. The research results can provide theoretical and technical support for the upstream tailings dam construction of high concentration tailings ponds.

Numerical Simulation of Tailings Flow Discharge Process of Tailings Dam Break in Real Terrain

LIU Xiaofeng, LIAO Zongwen, XIAO Lixing, YAO Chi

2023, 52(09):  206-212. 

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In order to study the influence of tailings flow caused by dam break on downstream sensitive targets,a real three-dimensional terrain numerical model was established for a overhead tailings pond in Jiangxi Province. The FLOW-3D three-dimensional hydrodynamics software was used to simulate the temporal and spatial changes of tailings flow in the downstream 1km range under different working conditions. The results show that:the development direction,distribution,water depth and sediment deposition of dam break tailings flow are obviously affected by the real three-dimensional terrain changes. The dam break tailings flow mainly distributes in the downstream paddy fields and low-lying areas. As the main flood passage, Qianxi River has obvious water depth changes and sediment deposition. Only the removed Qianxi Village is submerged by the tailings flow,as far as the fish pond in the west of Gangkou Village,the other villages were not affected. The results can provide the basis for the safe operation management of tailings pond and the formulation of dam break emergency plan.

Analysis of Spatiao-temporal Variation of Ecological Environment in Mining City Based on Remote Sensing Ecology Index

TENG Yongjia, YAN Yueguan, GUO Wei, LI Kai, ZHAO Chuanwu

2023, 52(09):  213-222. 

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With the depletion of coal resources in the east and the strategic shift of the mining center to the west,the green transformation and development of mining cities in the east has put forward new requirements for the evaluation of ecological environment quality. At present,most relevant researches focus on the intensive and high-intensity mining areas in the west,and there are few studies on the applicability of relevant methods and experiences to the eastern mining cities. Secondly, the current research on the ecological environment of mining areas based on statistical results cannot provide quantitative analysis of spatial heterogeneity. Furthermore,under the relatively small mining intensity,the impact of coal mining itself on the environment is controversial,while the ecological effects of coal storage and transportation have not received much attention. The Landsat remote sensing images from 2013 to 2020 were used,the Fengfeng mining area of the industrial and mining city was taken as the study area,and the RSEI ( Remote Sensing Ecology Index),coupled with the landscape ecological index,were constructed to the study area. Heterogeneity was quantitatively analyzed,the ecological effects of the local coal " mining-storagetransportation" process were studied,and the driving factors were analyzed. The results showed that:from 2013 to 2020,the habitat quality of the Fengfeng mining area showed a small fluctuation,but the structure configuration was obviously optimized; The landscape index analysis showed that the spatial heterogeneity of each grade of RSEI was strengthened,and the non-equilibrium distribution phenomenon was more obvious;The process of coal mining-storage-transportation had a certain disturbing effect on the ecological environment and its stability,the effect of coal mining was not strong,and the ecological impact of storage and transportation present a gradient effect;RSEI had a relatively stable positive correlation with elevation,slope,and vegetation cover,and a relatively stable negative correlation with light index. The study results can provide scientific reference for the coordinated sustainable development of mining cities.

Effect of Coal Mining Subsidence Cracks on Soil Nutrients at Different Slope Positions in Windy Desert Area

GAO Qin, DANG Xiaohong, MENG Zhongju, GAO Yong, GAO Yan, LIU Hongxin

2023, 52(09):  223-230. 

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In order to explore the variation characteristics of soil nutrients in different slope positions of coal mining subsidence cracks in aeolian sand area,taking the coal mining subsidence slope of Lijiata Coal Mine in Ordos as the research object,the longitudinal variation law of soil nutrient indexes in different slope positions of coal mining subsidence slope and nonfracture zone was analyzed. The results showed that the soil indexes of coal mining subsidence slope increased from the top to the bottom of the slope,the soil water content at the top of the slope was maintained at 10. 61%,and the soil organic matter in the fracture zone was 28. 61% lower than that in the non-fracture zone. Compared with the non-fractured zone,the soil moisture content and soil organic matter in the fracture zone at the middle and bottom of the slope decreased by 7. 32%,102. 59% and 21. 76%,149. 06%,respectively. The soil available nutrients in the fracture zone increased by 0. 03% ~ 14. 00% compared with the non-fracture zone. The study results indicated that:the coal mining subsidence cracks caused by coal mining have different degrees of influence on soil nutrients. With the decrease of slope,the influence of subsidence cracks on soil nutrients gradually increases. The subsidence cracks accelerate the evapotranspiration of soil moisture and the decomposition rate of soil organic matter,so that the soil available nutrients are enriched in the surface soil of the cracks,which lays a theoretical and practical foundation for the soil improvement of coal mining subsidence and the ecological restoration of mining areas.

Study on the Adsorption Behavior of Litchi Shell Adsorbent for Gold Ion

HUANG Kai, ZHU Qing, ZHU Jiajun

2023, 52(09):  231-239. 

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In order to recover the trace gold ions in the leaching solution,litchi shell was used to prepare gold ion adsorption material. The behavior and mechanism of gold ion adsorption of litchi shell were studied in detail by means of various instruments. Gold particles were observed under the optical microscope,and the X-ray diffraction further confirmed the appearance of gold metal on the modified lychee husk adsorbent,which successfully adsorbed the gold ions in the solution by an electrostatic attraction coupled with the in-situ reduction reaction. XPS analysis confirmed that at least 94. 9% of the gold ions were reduced to gold. The concentration of hydrochloric acid and co-existing base metal impurity ions have little effect on the adsorption efficiency of gold,and in 1 mol / L of HCl,almost 50% of Pd and 35% of Pt are simultaneously adsorbed. In HCl medium of 0. 1 mol / L,100% of Pd and 100% of Pt will be adsorbed simultaneously. Under the concentration of 0. 1 mol / L hydrochloric acid,the saturated adsorption capacity of modified litchi shell for gold was 33. 36 mg / g. During the adsorption process,the ORP (REDOX potential) value of the solution decreased sharply,which also confirmed that the reduction occurred during the adsorption of gold ions by litchi shell. Moreover,the higher the adsorption temperature,the faster the ORP value decreased. The preparation of adsorption materials by litchi shell is simple,low cost,high efficiency and green,and it is expected to be a new technology for recovering trace gold ions from industrial wastewater by adsorption.

Study on Biocarbon Enhanced Microbial Remediation of Heavy Metal Complex Pollution from a Smelting Slag in Sichuan

LIU Zeming, FU Kaibin, ZHONG Qiuhong, KONG Yunlong, ZHU Leming

2023, 52(09):  240-246. 

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In order to solve the problem of multiple heavy metal composite pollution in a certain metallurgical slag in Sichuan,biochar solidification microbial experiment and adsorption kinetics experiment were used to study the synergistic effect of biochar and microorganisms on the remediation of multiple heavy metals and the adsorption kinetics behavior of multiple heavy metals on the surface of biochar. Fourier transform infrared spectroscopy ( FTIR) and scanning electron microscopy (SEM) were used to explore the interface mechanism of biochar group enhanced microbial remediation of heavy metals. The results showed that in the anaerobic atmosphere,Sulfate-reducing bacteria ( SBR) and acidophilic thiobacillus ferrooxidans (At. f,pH = 5. 0) were mixed at volume ratio of 3 ∶ 2,the inoculation amount was 20%,the addition amount of biochar was 10%,and after 30 days of solidification,the bioavailability reduction rates of iron,zinc,copper,lead and chromium in the dressing and smelting slag were 98. 37%,90. 32%,90. 81%,96. 52% and 100%,respectively. The adsorption kinetics test showed that the reaction process was chemical reaction. Fourier transform infrared spectroscopy and scanning electron microscopy analysis indicated that heavy metals react with hydroxyl and carboxyl groups on the surface of biochar,solidifying / stabilizing heavy metals such as Zn and Cu in the form of precipitation,reducing their bioavailability.

Effect of Bentonite on the Forms and Bioavailability of Cu (Ⅱ ) in Soil

YANG Xiumin, ZHAO Fujun

2023, 52(09):  247-253. 

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The form of heavy metals in soil reflects the bioavailability and potential harm of heavy metals. In order to discuss the influence of bentonite on the form distribution of Cu( Ⅱ ) and bioavailability,a pot experiment were carried out to study the characteristics of the Cu(Ⅱ ) forms through simulating Cu contaminated soil and Tiesser method,and the correlation between pH value of soil and Cu(Ⅱ ) forms were studied. The results showed that:bentonite significantly reduced the concentration of exchangeable form of Cu( Ⅱ ) in the cultivated soil,increased the concentration of Fe-Mn oxide form and organic form,and had little effect on carbonate form and residual form. Bentonite significantly reduced the concentration of exchangeable form of Cu(Ⅱ ) in the virescence soil,increased the concentration of the carbonate form,Fe-Mn oxide form and organic form,and had little effect residual form. Bentonite decreased the biological activity coefficient and migration coefficient of Cu (Ⅱ ) in soil,and decreased the bioavailability of Cu(Ⅱ ) in soil. The correlation analysis of Cu(Ⅱ ) forms with soil pH value showed that there is a proven negative correlation between exchangeable form of Cu(Ⅱ ) with pH value in the cultivated soil, and there is a proven positively correlation between Fe-Mn oxide form,organic forms of Cu(Ⅱ ) with soil pH value,and there is little correlation between carbonate form and residual form of Cu(Ⅱ ) with soil pH value. There is a proven negative correlation between exchangeable form of Cu(Ⅱ ) with pH value in the virescence soil,and there is a proven positively correlation between carbonate form,Fe-Mn oxide form,organic forms of Cu(Ⅱ ) with soil pH value,there is little correlation between residual form of Cu(Ⅱ ) with soil pH value. The study shows that bentonite reduces the exchangeable concentration of Cu(Ⅱ ) mainly by changing soil pH value,thus reducing the bioavailability of Cu(Ⅱ ).

Microwave-enhanced Electrolytic Dissolution of Circuit Board Metals and Mechanism Study

LIU Zunzhang, QIN Wenjie, ZENG Zhi, ZHAO Jian, HE Chunlin, FUJITA Toyohisa

2023, 52(09):  254-262. 

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Aiming at the problems of long leaching time and low leaching rate of metal from waste printed circuit boards ( WPCBs),due to advantages of microwave heating,such as high penetrability,selective heating,small thermal inertia and nonionization,microwave-enhanced chlorine was utilized to leach metals from WPCBs combining microwave and electrochemistry. The results showed that:under the conditions of microwave power of 500 W and electrolysis leahing time of 100 min,the mass loss rate of WPCBs samples was 63. 49%,and the leaching rate of Cu was 83. 50% when plastic foam was used as the carrier medium. The increases of microwave power and electrolysis time were beneficial to the improvement of the leaching rate of Cu. Calorimetry,heating method,dielectric constant and other testing methods were used to reveal the microwave heating mechanism of pure metal powder and WPCBs materials,and microwave-enhanced leaching mechanism. The test results show that the metal of WPCBs being heated in the microwave field consumed the magnetic field. The metal in the WPCBs after absorbing the microwave energy and its temperature is higher than the temperature of the solution. The metal surface has a high energy and high temperature,and easy to react with the dissolved leaching agent and Cl2 which dissolved in solution. The temperature between metal surface and the solution are difference,therefore,the formation of thermal perturbation of the solution to promote the migration of leaching reagents in the solution occured to promote the reaction,and ultimately to enhanced leaching and improve leaching rate of metal in a shorter time and lower acid concentration. The results of the study provide a new microwave electrochemical leaching recovery pathway for WPCBs metal resource recovery.

Effect of Mixing Method on Fluidity and Mechanical Strength of Coal Gangue Fine Aggregate Concrete

CHEN Fengge, LIU Xin, ZHANG Yapeng, FENG Shenglei, MENG Wenqing, CUI Hanlong, GUO Qiushuo

2023, 52(09):  263-268. 

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Washing coal gangue has the characteristics of many impurities,large porosity and strong water absorption,and the concrete prepared from it has poor fluidity and low strength. In order to solve this problem,the mixing method of washing coal gangue was studied by optimization tests. Firstly,the washing coal gangue fine aggregate was pre-wetting,and then the concrete was mixed by one feeding method. The effect of additional water amount and pre-wetting time on the fluidity and strength of concrete was studied. Finally,scanning electron microscope was used to observe the influence of pre-wetting method on the micromorphology of concrete,and the gray level of the micromorphology was analyzed by Image J. The results showed that with the increase of additional water,the slump of concrete mixture presents an upward trend,and the 7 d and 28 d compressive strength increases with it. The longer the pre-wetting time of coal gangue fine aggregate,the greater the slump of the mixture, and the 7 d and 28 d compressive strength first increased and then decreased. The pre-wetting treatment can promote the formation of more C—S—H gels,improve the microporous structure of concrete,and increase the compactness. Better slump and higher compressive strength can be obtained by adding additional water to the washing coal gangue fine aggregate at 100% of saturated water absorption rate and mixing concrete after 60 minutes of prewetting. The research results are expected to provide theoretical guidance and technical support for the commercial application of washing gangue concrete.

Filling Performances of Iron Tailings Cemented by Fluid Cementing Materials

HUA Lei, XU Liang, LI Jiamao, FAN Chuan′gang, LI Shengjun, LI Zhenghao, FAN Xi

2023, 52(09):  269-274. 

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In order to simplify the process of cementitious material production and reduce the cost of filling,the fluid cementitious materials (FCM) were used to replace powder cementitious materials (PCM) for the solidification of iron tailings. The properties were investigated using fluidity tests,strength tests and water absorption tests for the specimens of solidified iron tailing (SIT) with two kinds of cementitious materials of PCM and FCM. The binding mechanism of SIT was analyzed using XRD and SEM techniques. For the specimen of SIT with the solid tailing content being 70% and the cement-to-tail ratio being 1 ∶10,the 3-day compressive strength (0. 87 MPa) of the specimens using PCM as tailing binder was about 0. 3 MPa higher than that using FMC. The difference of 7 d compressive strength was decreasing between two SIT specimens with PCM and FCM,and there was no significant difference for their 28 d compressive strengths. The flowability of the filling tailing with the addition of FCM was increased by 7. 4% compared to that with the addition of PCM. It indicated that the using of FCM could facilitate pumping and filling of iron tailing slurry without affecting the 28 d mechanical properties of SIT′s. XRD and SEM analysis showed that the hydration reaction of FCM was more benefit to the growth of ettringite.

Study on Strength and Rheological Properties of Steel Slag-based Cemented Backfill

CUI Chunliang

2023, 52(09):  275-280. 

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In view of the problem that cement as cementing material will increase the cost of backfill mining,steel slag, slag and quicklime are used as materials to conduct study on steel slag-based cementing materials,and the rheological properties of strength agent of steel slag-based backfill are analyzed in detail. The results show that slag content has a greater effect on the strength of backfill at 7 days than steel slag content,and steel slag content has a greater effect on the compressive strength of backfill at 28 days than slag content. With the increase of steel slag content,the compressive strength of the steel slag-based cemented backfill generally increases first and then decreases. When the steel slag content is 30%,the compressive strength of the backfill basically reaches the maximum value. Under the same content of cementing materials and slurry concentration,the 7 d and 28 d compressive strength of steel slag-based cemented backfill is significantly higher than that of cement based cemented backfill,which fully reflects that steel slag-based cemented backfill has better mechanical properties. With the increase of slurry concentration,the rheological parameters of steel slag-based filling slurry under different cement-sand ratios show an obvious trend of increase,but the change of cemented material content has no significant effect on the yield stress of steel slagbased filling material. Combined with the rheological test,it can be seen that the slurry concentration of steel slag-based backfill can be designed to be 62% ~ 64%,and the yield stress within this concentration range does not exceed 200 Pa,and the slurry shows good transportation performance.