Table of Content

15 March 2023, Volume 52 Issue 03

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Research Status and Prospect of Thermal Environment Regulation of the Deep Mine of China in the Past 20 Years

WANG Yunmin, LI Gang, XU Yu, REN Jiaze, JIA Mintao, ZHOU Wei

2023, 52(03):  1-13. 

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As mining engineering proceeds to increasingly greater depths,higher rock temperatures and thermal stress pose a major challenge for the safe and efficient exploitation of deep resources. Mine ventilation and air conditioning gradually becomes the main energy consumption in deep mineral resources development,and concerns the mine production environment and costs,and sustainability of mining industry. The development evolution of mine ventilation and heat transfer theory and the research status of mine cooling technology are summarized. Besides,the characteristics of common cooling technology in mines are analyzed,and the future development direction of mine thermal environment control is forecasted. The study results show that:At present,the method of mechanical refrigeration and ventilation cooling is the main choice for mine heat hazard control, but it do not efficiently meet the cooling requirements of deep mines owing to high operational cost,difficult maintenance,low cooling efficiency,and low cooling capacity. To improve the effect of heat hazard control in deep mines,the new idea of “reducing source and opening flow” should be advocated,active cooling measures should be carried out during mine development,and multiple cooling methods should be implemented simultaneously. In addition,the cooling system combined with intelligent ventilation can control temperature more accurately and reduces the requirement of cooling capability. Circulation ventilation cooling technology can be adopted to improve the utilization rate of cooling capacity. High-performance cooling protective clothing should be developed and applied in special high-temperature working scenarios. The key to cooling the deep mine effectively and upgrading the energy structure is to transform the traditional technical thinking of heat hazard control into the conception of geothermal resource utilization in mines,and combine mine thermal environment control and geothermal resource exploitation.

Review on the Study Progress of Rockburst Mechanism and Prediction in Underground Metal Mines in China

QIAO Lan, DONG Jinshui, IU Jian, CHEN Lu

2023, 52(03):  14-28. 

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Rockburst is an unavoidable dynamic geological disaster in underground mining of metal mines. Its frequency and degree will be more and more serious with the continuous increase of mining depth of metal mines. Rockburst is still a worldwide problem in the field of rock mechanics. Firstly,the current situation of rockburst disasters in metal mines in China was summarized;Then,the research progress on the mechanism and prediction of rockburst was discussed;Finally,a new method for rockburst prediction was proposed based on the energy theory of rock mechanics. The main conclusions are as follows:① The compressive test is one of the most important means to study the mechanism of rockburst. According to the loading conditions of the sample,it can be divided into uniaxial loading,biaxial loading,true triaxial loading and coupled static and dynamic loading. The mechanical mechanism of rockburst can be summarized into three types:compression induced cracking,compression induced shear cracking and bending bulge. ② The index criterion method and mathematical method are two of the most widely used rockburst prediction methods. Index criterion method is empirical summary for a certain project,which is not universal. The internal influencing mechanism of rockburst factors can not be obtained by mathematical methods,and its interpretability is poor. On the basis of the above analysis,the study directions of rockburst mechanism and prediction are prospected,so as to provide reference for the subsequent work.

Study on the High-efficient Mining Technique for Deep Inclined Broken Gold Ore-body

LI Yang, SONG Weidong, DU Yunlong, ZHANG Chao, ZHANG Shaopeng

2023, 52(03):  29-35. 

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In view of the special geological conditions of deep inclined broken orebody in Sanshandao Gold Mine,a comprehensive mining technique is proposed,which includes the stage open stope and subsequent filling and secondary high-pressure grouting prestressed anchorage support,and the basic principle of hanging wall pre-reinforcement treatment is analyzed. The numerical simulation of stress,displacement and plastic zone of broken orebody mining is carried out,then,the rationality of stage open stope and subsequent filling mining method and the feasibility of hanging wall pre-reinforcement treatment are analyzed. The study results show that the stage open stope and subsequent filling mining method with hanging wall pre-reinforcement can effectively reduce the deformation of the surrounding rock of the side wall of the deep stope,and control the loss rate of the stope to 9. 7% and the dilution rate to 7. 8%. It can ensure the safe and efficient mining of deep broken orebody in Sanshandao Gold Mine,and provide a theoretical basis for the efficient mining of similar mines.

Strength Properties of Cemented Tailings Backfill Mixed by High Salinity Underground Mine Water

ZHU Gengjie, ZHU Wancheng, SUN Xianteng, WANG Zhuoran, JING Xiaodong, SANG Laifa

2023, 52(03):  36-43. 

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In order to explore the influence of high salinity mine water (total dissolved solid content >1 g / L) containing chlorine on strength of cemented tailings backfill,taking tailings from a gold mine in Bohai Bay,Jiaodong Peninsula,China as aggregate,the compressive strength of backfill prepared by mixing slag-based cementing materials ( desulfurized gypsum and hydrated lime as activator) and tailings with high salinity mine water was tested. The hydration products of the slag-based binder and micro-structure of harden backfill were detected by X-ray diffractometer,scanning electron microscope and mercury porosimeter. The influence of variables (mass ratio of desulfurized gypsum / hydrated lime and slag dosage) on strength of backfill was analyzed. The results show that:① The introduced high salinity underground mine water containing chlorine promotes the formation of hydration products and optimizes the microstructure of backfill,thus obtaining the high-strength cemented tailings backfill. Ettringite and calcium silicate hydrate ( C—S—H) are two main hydration products,and no new hydration products are formed due to the incorporation of Cl-,Na+,Ca2+ and Mg2+ ions,but the effect on the molecular structure of C—S—H needs further study. ② The strength of backfill at each curing age increases first and then decreases with the increase of the ratio of desulfurized gypsum to hydrated lime,and the ratio of desulfurized gypsum to hydrated lime corresponding to each peak strength increases with the extension of curing time. However,the optimal slag content corresponding to the peak strength of different ages is always stable at 67. 8%. The proportion of desulfurized gypsum and hydrated lime can be adjusted to meet the time demand for the strength of backfill in specific engineering. The results of this study can provide theoretical basis and technical guidance for the application of high salinity mine water in the preparation of backfill materials for mines. The results ofthis study can provide theoretical basis and technical guidance for the application of high salinity mine water in the preparation of backfill materials for mines.

Study on Rheological Characteristics of Full Tailings Filling Slurry with Time-Temperature Effect in Miaoling Gold Mine

CHEN Xiaoli, YANG Hua, YANG Yong

2023, 52(03):  44-51. 

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Cemented backfill is an economic and environmental protection mining technology. At present,the temperature effect on the rheological properties of the high concentration slurry cemented filling has a lack of research. This paper takes full tailings filling slurry of Miaoling Gold Mine as the study object and a series of rheological properties experiments were carried out by Rheolab Q C advanced rheometer to comprehensively study the influence of time temperature effect on the rheological properties of high concentration cemented filling slurry. The results show that the rheological characteristics of both fresh cemented slurry and dynamic slurry have obvious Bingham fluid characteristics,the yield stress and plastic viscosity of slurry increase with increasing time,while the plastic viscosity decreases with increasing temperature and the yield stress decreases first and then increases. The rheological properties of the static slurry don′t conform to the common rheological model theory,and the fluidity of the slurry decreases with the increase of the standing time. For the static slurry,the rheological properties are more affected by time factor than temperature. For the dynamic slurry,the rheological properties are more affected by temperature than time. The influence of slurry concentration on rheological properties is greater than that of cement-sand ratio for both dynamic and static slurry.

Study on Strength Evolution Characteristics and Mechanical Effect of Cemented Tailings Backfill in a Mine

MIAO Leigang, NIU Yuanyuan, PAN Yangbo

2023, 52(03):  52-58. 

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Taking filling mining of a metal mine as the study background,the compressive and tensile strength tests of backfill body under different proportion parameters were carried out,and the strength evolution characteristics of backfill under different proportion parameters were analyzed. Meanwhile,FLAC3D numerical simulation software was used to analyze the mechanical characteristics of filling body and surrounding rock in the process of orebody mining and goaf filling,revealing the mechanical effect of filling body in the stope. The results show that with the increase of curing time,the mechanical strength of backfill tends to increase continuously,and the compressive strength of backfill with higher concentration or cement-sand ratio increases more. At the early curing stage,the influence of cement content reduction on the strength of cemented tailings backfill is not significant. After orebody mining,the roof and floor of stope show the characteristics of compressive stress concentration, but the stress concentration of surrounding rock is obviously improved after goaf filling. In addition,after the second-step goaf filling,the tensile stress value of the filling body reaches 0. 20 MPa,which exceeds the tensile strength of some backfill. Therefore,it is recommended that the lowest ratio of cement to sand of the backfill should be 1 ∶ 6 to maintain the stability of the backfill in the stope.

Experimental Study on Performance of Graphene Oxide Modified Clay-cement Slurry

LIU Shujie, SUN Jinze, DING Zhenyu, ZHANG Jiwei

2023, 52(03):  59-64. 

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As a sort of widely used material in mining construction,the clay-cement slurry grouting has low seepage and filtration resistance at the initial reinforcement stage. The grouting reinforcement is affected because of its low strength and brittle damage. In order to prepared the new clay-cement slurry,graphene oxide( hGO) is selected to blend with the common claycement paste,which is prepared by Hummers method as a modifier. Based on the comparative analysis of the main performance parameters of hGO modified clay-cement slurry,including viscosity,stability,plastic strength and mechanical properties,under differences hGO incorporation by means of indoor tests and combined with the mechanism of hGO from microscopic morphological point of view employed scanning electron microscope experiment,the growth model of hGO modified clay-cement slurry nodules is proposed. The results show that:A spatial skeleton of clay-cement slurry body with hGO lamellae as the core and filled by clay particles is formed,which explains hGO modified clay-cement slurry performs better than traditional clay-cement slurry. With the increase of hGO admixture,the viscosity of clay-cement slurry increases by 163% at most. The stability and plastic strength of the modified clay-cement slurry are significantly enhanced,and the maximum of plastic strength is 7. 11 times under the same maintenance time. The early impermeability and water plugging of the slurry are significantly improved. The uniaxial compressive strength and shear strength of the plasma stone body are increased by 23. 94% and 25. 27%,which has obvious effects on the optimization of slurry durability.

Impact Failure Modes and Energy Dissipation Characteristics of Graphite Rock with Different Grades

YE Haiwang, WEN Ying, LEI Tao, WANG Qizhou, YU Menghao, YAN Lide, WEI Wenpeng, LI Xingwang, WANG Jionghui, ZHAO Mingsheng

2023, 52(03):  65-72. 

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Under the blasting action,the problems of large fragmentation dispersion and low energy utilization exist in graphite ores of different grades. Dynamic compression tests of five grades of graphite rock samples with different strain rates were carried out with a ϕ50 mm SHPB apparatus. The impact failure modes and energy dissipation characteristics of graphite rock samples with different grades were studied by combining high-speed photography and microstructure. The study results show that as the grade increases,the failure mode of the graphite ore rock sample changes from tensile failure to tensile-shear failure. The energy consumption characteristics of graphite ore rock have an obvious strain rate effect. The incident energy increases exponentially with the increase of the strain rate,and the absorbed energy shows a linear growth trend;The grade also has a great influence on the energy absorption rate. The change characteristics of energy absorption rate with strain rate have obvious differences in graphite ore rock with different grade. There is a good correspondence between the average broken size of the graphite ore rock sample and the absorption energy. When the graphite ore rock grade is 18. 97%,the average broken size is the smallest. The microstructure of the crushed rock sample was observed through microscope. It was found that the graphite flake structure will produce structural interface in the ore rock and the strength of the ore rock was reduced accordingly.

Experimental Study of Quasi Wedge Compound Cut Blasting Based on Digital Electronic Detonator

WANG Yanbing, BAO Zhouqi, XIE Ping, ZHANG Yinghao, WANG Guohao

2023, 52(03):  73-79. 

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Aiming at the problems such as unsatisfactory blasting effect and long single cycle time in the current cut blasting,the blasting experiment was carried out in the third middle yard of horth-1 coal roof track in Gubei Mine,the original blasting scheme was improved and the blasting parameters were optimized. The digital electronic detonator is introduced for the first time in the underground rock tunneling,and the digital electronic detonator is used to replace the common electronic detonator permitted in coal mine,and the blasting section is increased. According to the field situation of rock roadway,two new quasiwedge compound cut blasting schemes are designed by using the advantage that digital electronic detonator can arbitrarily set the delay time of blasting section. By comparing the blasting effects of the three schemes,the utilization rate of borehole is improved to 96. 1%,and the single-cycle footage is increased to 1. 78 m,which is 12. 8% higher than the original scheme. The results show that the reliability of digital electronic detonator is high,and the delay time of blasting section is preliminarily determined when the utilization rate of borehole is the highest. The use of digital electronic detonator in rock tunneling can make the blasting process controllable,have sufficient blasting space except the cut hole,increase the single cycle footage,reduce the single cycle time,improve the quality of tunnel forming,improve the work efficiency,and have good economic and social benefits.

Comparative Analysis of Vibration Energy between Electronic Detonator and Nonel Detonator Blasting

GUAN Yueqiang, ZHANG Mingyuan, WANG Fanfan, LI Hongwei, WANG Jing, ZHONG Shuai

2023, 52(03):  80-85. 

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In order to compare the effect of delayed initiation of electronic detonators and nonel detonators on the distribution law of blasting vibration energy,the model test and field test were carried out from the perspective of blasting vibration energy. Based on MATLAB wavelet packet analysis method,the blasting vibration signal is divided into 32 frequency bands according to frequency,and the energy and particle peak velocity of each frequency band are analyzed. The results show that the vibration energy generated by the detonators of electronic detonators and nonel detonators is mainly concentrated in the 1 ~ 4 frequency band (0~ 125 Hz),and the energy distribution tends to the middle and high frequency band with the increase of blasting vibration energy. The vibration energy significantly affects the PPV,and the PPV in each frequency band of detonator decreases from low to high,and then increases and then decreases,showing an " N-shaped" distribution. In the field test,compared with the nonel detonator,the average vibration reduction rate of the electronic detonator is 21. 3% and the average vibration energy is reduced by 32. 7%. When using detonator for differential blasting operation,the delay accuracy of nonel detonator is poor,which leads to obvious vibration superposition effect between holes,and the vibration energy generated by blasting is much larger than that generated by electronic detonator. In practical engineering,setting reasonable delay time with electronic detonator can effectively reduce blasting vibration.

Study on the Calculation Method of Early Temperature Stress of Deep Frozen Shaft Wall

LI Fangzheng, YU Xinhao, ZHANG Jiwei

2023, 52(03):  86-93. 

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In order to study the early temperature stress variation law of deep frozen shaft wall at different time nodes,an analytical solution of early temperature stress of frozen shaft wall was derived based on the heat conduction principle and thermoelastic mechanics theory,considering the temperature history of frozen shaft wall and the change of concrete elastic modulus. Taking the 1. 7 m thick wall seat of No. 1 air shaft in Hongqinghe Coal Mine as the study example,the distribution law of early temperature stress in the inner wall of frozen shaft was obtained,and the main reason of early temperature stress leading to high risk area of shaft fracture was determined. The study results show that:① In the early stage,the radial stress σr is compressive stress as a whole,and the maximum σr can reach -2. 2 MPa,and decreases gradually along the frozen wall to the inner edge of the shaft wall. At any position of the borehole wall, σr decreases first and then increases with the development of age. ② In the early stage,the annular stress σθ is compressive stress as a whole,and the maximum σθ can reach -8. 98 MPa. When it tends to the frozen wall, σθ decreases rapidly first. When tending to the inner wall edge, σθ increases first and then decreases. ③ In the early stage,the vertical stress σz is compressive stress,which can reach the maximum of -19. 64 MPa,and increases rapidly at first and then decreases slowly with the development of age. ④ It is suggested that the temperature history formula of the same kind of shaft wall should be fitted according to the engineering analogy method for the theoretical calculation of temperature stress of frozen shaft wall in the future. On this basis,the measures to reduce the risk of rupture of frozen borehole wall are put forward,including two ideas:① Reduce the temperature difference between the outer edge of borehole wall and the center and the inner edge. ② Prepare crack resistant concrete suitable for freezing wellbore.

Study on Mechanical Properties and Damage of Sandstone under Acidic Conditions and Freeze-thaw Cycles

PENG Cheng, LI Anran, LIU Shun, XIE Yangfa, ZHONG Qiming

2023, 52(03):  94-99. 

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In order to study the change of sandstone mechanical properties and the law of damage and deterioration under the action of hydrochemistry-freeze-thaw cycles,sandstone samples with different damage degrees were obtained by immersion in hydrochemical solution and freeze-thaw cycles,and then uniaxial compression experiments were carried out to discuss their mechanical properties,the damage and deterioration mechanism of sandstone was analyzed from a microscopic point of view by scanning electron microscope. The study results show that:① With the increase of freeze-thaw cycles,the longitudinal wave velocity attenuation and mass loss rate of sandstone in acidic solution are greater than those in neutral solution,and the lower the pH value of acidic solution is,the greater the response range is. ② The peak stress is negatively correlated with the number of freeze-thaw cycles,and positively correlated with the pH value of soaking solution. The sandstone presents a tendency of transformation from brittleness to ductility. ③ From the perspective of microscopic structure analysis,it is concluded that the damage and deterioration of sandstone is alternately and continuously accumulated. ④ The elastic modulus was used to define the damage variable of sandstone,and the law function model of the damage variable was established by fitting,which showed that the lower the pH value of soaking solution,the higher the number of freeze-thaw cycles,the greater the damage deterioration degree of sandstone. The study results can provide references for engineering construction in cold areas and underground mining in the acid-eroded environment.

Experimental Study on Relationship Between the Breakdown Characteristics and Physical and Mechanical Parameters of Rocks Under High Voltage Pulses

PENG Jianyu, LI Jiaqiang, ZHANG Fengpeng, DU Chuan

2023, 52(03):  100-105. 

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High voltage pulse provides a new rock breaking technology with great application prospect. In order to study the fracture characteristics of rock breakdown by high voltage pulses, and clarify the relationship between breakdown field strength and physical and mechanical parameters,electric breakdown experiments on different lithological rocks were conducted. The microscopic fracture mechanisms of rocks after breakdown were analyzed with the aid of a scanning electron microscopy,and the rupture patterns of different lithological rocks at just breakdown were compared. Besides,the influence of physical and mechanical parameters on the breakdown field strength of rocks was studied. The results of microscopic analysis show that: the region near the plasma channel shows high-temperature burning characteristics with smooth grain surface and holes;The crack region presents intergranular and transgranular fractures under shock waves;The transition area shows the joint action of high temperature and shock waves. In addition,there is little correlation between the breakdown field strength and the density, wave velocity,and elastic modulus. However,a good quantitative relationship can be established between the breakdown field strength and the compressive and tensile strengths of rocks,which increases exponentially with the increase of these two parameters.

Acoustic Emission Characteristics and Damage Evolution of Sandstone under True Triaxial Step-loading

CHEN Peng, LI Nan, FANG Liulin, CAI Chao, HUANG Jing, LI Yi, LIU Xuan

2023, 52(03):  106-113. 

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Deep mines,tunnels,and other deep engineering rock masses are in a three-dimensional high-stress state,and surrounding rocks affected by mining are often subjected to significant step-loading in the vertical direction. The study on the acoustic emission characteristics of rock under true triaxial step-loading is of great significance to the monitoring and early warning of the deformation and destruction of the surrounding rock in deep ground engineering. To this end,a true triaxial step-loading acoustic emission monitoring experiment of sandstone was carried out,the acoustic emission signal characteristics of sandstone during the true triaxial step-loading process were studied,and the evolution process of rock damage based on the number of acoustic emission window waveforms was revealed. The results show that under true triaxial conditions,with the continuous increase of the maximum principal stress,the failure mode of sandstone gradually changes from tensile failure to shear failure. The number of acoustic emission window waveforms has a good response to the internal stress changes of sandstone and can directly reflect the internal damage evolution of the rock. Therefore,a damage variable and damage evolution model based on the cumulative window waveform number is proposed. The sandstone damage-strain relationship canbe divided into 4 stages. In the initial damage stage,three-way simultaneous loading leads to compact closure of the internal defects of the rock causing slight damage. In the steady development stage of the damage,the damage increases slowly,and the damage-strain relationship is close to linear; the damage develops rapidly. During the rapid development stage of damage,the strain of the rock does not increase with the increase of stress,and the damage increases rapidly. In the stage of failure,the strain keeps increasing,the internal cracks expand and penetrate to form a macroscopic fracture surface until the rock is unstable and damaged.

Comparative Study on Effect of Ball Milling and Tower Milling for High Pressure Roller Milling-Preconcentration Concentrate in an Iron Mine

HAN Cheng, WANG Ziyang, HOU Ying, CHEN Laibao

2023, 52(03):  114-119. 

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In order to improve the grinding efficiency of the mine and realize energy saving and consumption reduction, taking the high pressure roller milling-preconcentration concentrate of an iron mine as the research object,the ball mill and tower mill were used as the rough grinding equipment to carry out the grinding test. The results showed that :① when the ball mill is used for grinding and the grinding time is 200 s,the energy consumption of the newly generated -0. 074 mm product is 150. 08 kW· h / t,and the utilization coefficient of the mill -0. 074 mm is 0. 586 t / (m3· h). When the grinding time is 600 s, the energy consumption of the newly - 0. 074 mm product is 138. 53 kW· h / t, and the utilization coefficient of the mill -0. 074 mm is 0. 195 t / (m3· h). The yield difference of each grade of the products of the two grinding methods is mainly concentrated in +0. 150 mm and 0. 150~ 0. 074 mm. ② The appropriate tower grinding process parameters were determined by the optimization test as follow:grinding time of 300 s,grinding concentration of 60%,stirrer speed of 300 r / min,medium filling rate of 16. 15%,and material-ball ratio of 0. 166 4. Under this condition,-0. 074 mm utilization coefficient of the mill is 0. 625 t / (m3· h),and the energy consumption of the newly generated -0. 074 mm product is 53. 62 kW· h / t. Compared with the ball mill,the utilization coefficient of - 0. 074 mm is increased by 6. 66%,and the energy consumption of the newly generated -0. 074 mm product is reduced by 64. 27%. The research results could provide useful reference for the application of tower mill.

Study on Influencing Factors of Dephosphorization Agent CaCO3 in Reduction Roasting of High Phosphorus Oolitic Hematite

LIAN Xiaoxiao, SUN Tichang, KOU Jue, GUO Xiaoshuang

2023, 52(03):  120-126. 

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In order to reveal the influence mechanism of lignite dosage and roasting temperature on the effect of CaCO3, the direct reduction-magnetic separation tests were carried out for a foreign high-phosphorus oolitic hematite with lignite and CaCO 3 as reductant and dephosphorization agents, respectively. Thermodynamic calculations, XRD and SEM-EDS analysis showed that the effect of CaCO 3 was the synergism of CO2 and CaO generated by the decomposition of CaCO3. The main role of CaO is to promote the formation of apatite from the part of the phosphorus in the iron mineral,which is in the form of Fe3PO7, and inhibit the reduction of apatite and the formation of iron olivine and iron spinel. CO2 can promote the gasification of coal and accelerate the reduction of iron oxides. The lignite dosage and the roasting temperature affect the degree of response of CaO,which in turn will affect the effect of CaCO3. Due to the high degree of melting in the roasting process at low lignite calculations or high roasting temperature,the solid phase reaction of CaO can be promoted,so the effect of CaCO3 is good. Experimental studies have found that the direct reduction roasting effect was good at roasting temperature of 1 200 °C,the lignite dosage of 20% and CaCO3 dosage of 28%,in which the dephosphorization rate was as high as 92%.

Experiment Research on Reselection of a Lead-Zinc Flotation Tailings in Fujian

LI Xin, DENG Rongdong, WANG Jinrong, CHEN Qin, ZHANG Chengjie, HE Huanyin, LIN Jiansui, LIU Xiangxiang

2023, 52(03):  127-134. 

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The grades of lead,zinc and silver in a lead-zinc flotation tailings from Fujian are 0. 23%,2. 11% and 36. 3 g / t,respectively,among which zinc and silver have high recovery value. The main metallic minerals in the tailings are sphalerite,pyrite and galena,and the non-metallic minerals are mainly calcite and quartz. According to the characteristics of ore,preferential flotation was used to carry out the process optimization test. The results showed that:under the condition of grinding finness of -0. 074 mm accounting for 69. 92%,using lime as pH regulator,zinc sulfate as inhibitor,ethylthio-nitrogen as collector and 2# oil as foaming agent,silver-lead concentrate with lead grade of 4. 56%,silver grade of 320 g / t and lead recovery rate of 15. 55% and silver recovery rate of 6. 63% can be obtained through one roughing,three cleaning and one scavenging for lead flotation. With lime as pH regulator,copper sulfate as activator,butyl xanthate as collector and 2# oil as foaming agent,zinc concentrate with zinc grade of 37. 32%,silver grade of 152 g / t,zinc recovery rate of 73. 25% and silver recovery rate of 18. 80% was obtained through one roughing,three cleaning and two scavenging for zinc flotation. The test index is good and would provide data support for the comprehensive utilization of the tailings.

Influence of Surface Wettability Regulation on Hydration Films at the Solid-Liquid Interface

LI Bao, CHE Daochang, GUO Jianying, YANG Zhichao, LIU Shengyu

2023, 52(03):  135-139. 

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The thinning and rupture of the hydration film at the solid-liquid interface are the key factors affecting the flotation performance. In order to clarify the influence of mineral surface wettability changes on the hydration film,graphite was used as the research object,and hydrogen peroxide and surfactants were used to regulate the surface wettability of graphite. The structure and thickness of the hydration film were directly characterized by Atomic Force Microscopy (AFM),and the mechanism was studied. The results showed that the thickness of the hydration film increased with the degree of graphite oxidation, and the hydrophilic polar groups increased by oxidation mainly increased the thickness of the ordered layer in the hydration film;The surfactant adsorption can effectively cover the oxygen-containing groups on the mineral surface,thereby changing the structure of the hydration film. The ordered layer in the hydration film transformed to the transition layer,which can reduce the thickness of the ordered layer under low surfactant concentration,while the excessive adsorption of the surfactant could only increase the thickness of the transition layer,and the thickness of the ordered layer would not change significantly. In the flotation process,a small amount of excess agent is beneficial to the thinning and rupture of the hydration film on the hydrophilic mineral surface.

Study on Process Mineralogy of a Gold Ore With Extremely Refractory Altered Rock Type

HU Mengzhong, XIONG Zhaohua, TIE Ying, DING Chao, MA Shengping, MA Quanming, HONG Qiuyang

2023, 52(03):  140-146. 

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In order to make effective use of an extremely refractory gold ore,systematic process mineralogy tests have been carried out aiming at the raw ore. The material composition,particle size composition,texture and structure,main mineral distribution characteristics and gold particle characteristics of the ore have been studied. The results showed that:① The main available element in raw ore is gold,and the content of harmful impurity As is high with some carbon. Gold mainly exists in the form of sulphide coated gold,followed by exposed gold. ② The natural gold in raw ore is of trace amount,and the content of main gold-bearing minerals pyrite and pyrrhotite are 3. 829% and 0. 111%,respectively. Gangue mineral is mainly quartz,accounting for 45. 176%,in addition to containing arsenopyrite of 0. 779%. ③ The content of -0. 01 mm and the distribution rate of Au in the raw ore are less than 10%,and the grade of Au in each grain size has little change. The gold is only enriched in 0. 043 ~ 0. 02 mm of water precipitation sand. ④ The main texture of the ore include euhedral and semi-euhedral grains,heteromorphic grains,heteromorphic fragmentation and emulsion drops,and the main structure include sparsely disseminated,banded,brecciform and veined. ⑤ Gold is mainly contained in sulfide minerals such as arsenopyrite and pyrite,followed by gangue minerals such as quartz and sericite. 90% of the gold particle size is less than 8 μm,mainly fine and ultra-fine gold. ⑥ The distribution size of main gold-bearing minerals from coarse to fine is pyrite,pyrrhotite and arsenopyrite. The distribution size of arsenopyrite is very fine. Attention should be paid to the recovery of fine arsenopyrite in flotation. ⑦ When the grinding fineness is -0. 075 mm accounting for 62. 57%,the dissociation degrees of pyrite,arsenopyrite and sulfur and arsenic minerals are 90. 04%,81. 95% and 90. 04%,respectively. According to the research results of process mineralogy,free gold and sulfide minerals were recovered by flotation with a theoretical recovery of about 89%. The research results have important guiding significance for formulating reasonable beneficiation process.

Preparation of Polyaluminum Chloride by Acid Leaching and Micro-addition of Alkali Method Treating Secondary Aluminum Dross

HE Ziyang, TAN Xinyu, ZHANG Haiquan, LIN Wenliang, LU Shaokeng, WU Guoqing, WU Xu

2023, 52(03):  147-151. 

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Secondary aluminum dross is one of the main by-products in recycled aluminum industry and has been classified as hazardous waste. Long-term stacking or arbitrary disposal for secondary aluminum dross could cause many environmental problems. The secondary aluminum dross from a recycled aluminum company in Wuhan was used to prepare polyaluminum chloride by improved acid leaching process through controlling alkali addition. The effects of material dosing ratio,acid leaching temperature and leaching time on the leaching rate of aluminum from aluminum dross were studied. The effects of alkalinity B value,alkali adding rate and temperature on the morphology of polyaluminum hydrolytic polymerization were studied. The results showed that the optimal leaching conditions of secondary aluminum dross are as follows:material dosing ratio of m( secondary aluminum dross) ∶m(HCl) ∶m(water)= 1 ∶4 ∶4,acid leaching temperature of 85 ℃ and acid leaching time of 2. 0 h,in which the leaching rate of aluminum in the acid leaching solution reached the maximum of 60. 30%. Polyaluminum chloride was prepared by slowly adding 15% Na2CO3 solution into acid leaching solution prepared under optimized conditions. When the alkalinity B is 2. 4,the alkali adding rate is 3. 6 mL / min,and the alkali adding temperature is 80 ℃ ,the content of Alb in the polyaluminum chloride reaches the highest of 57. 49%. The polyaluminum chloride was successfully prepared by this process, realizing the recycling and harmless treatment of secondary aluminum ash.

Study on Whitening Test for a Sandy Kaolin

LI Hang, GUAN Junfang, YANG Chengliang, WANG Lulu, LIAO Min, DING Ding

2023, 52(03):  152-156. 

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In order to develop a kaolin ore resource in Yunnan Province reasonably and efficiently,two reducing agents, sodium disulfite and urea sulfur dioxide,were used to carry out whitening tests based on the analysis of ore properties. For kaolin samples with particle size of -0. 020 mm,the optimum bleaching conditions of urea sulfur dioxide were determined as pulp concentration of 20%,urea sulfur dioxide content of 2. 0%,pulp pH value of 13,oxalic acid content of 5%,reaction temperature of 30 ℃ ,reaction time of 20 min. Under the conditions,the Fe2O3 content of kaolin decreases from 0. 95% to 0. 70%,the iron removal rate reaches 26. 32%,and the natural whiteness increases from 65. 0% to 83. 5%. Compared with sodium disulfite,iron removal rate increased by 11. 58 percentage points and natural whiteness increased by 9. 1 percentage points. When urea sulfur dioxide is heated or catalyzed by alkali,strong reducing hyposulphuric acid is produced. Hyposulphuric acid reduces insoluble iron in kaolin to soluble ferrous iron and then removes it,thus improving the whiteness of sandy kaolin. Compared with sodium disulfite,urea sulfur dioxide has good iron removal effect,stable chemical properties and less environmental pollution. It can be used to remove iron and whiten kaolinite of the same type.

Geological Characteristics and Prospecting Prediction of Rechang Gold Polymetallic Deposit in the Eastern Section of Bangonghu-Nujiang Metallogenic Belt,Tibet

YUE Guoli, LI Min, LIAO Shijin, MA Yanfei, SUN Guofeng, WANG Yake

2023, 52(03):  157-168. 

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The Rechang gold polymetallic deposit is located in the eastern section of Bangonghu-Nujiang metallogenic belt. The geotectonic position of the deposit is located in the southern margin of Naqu-Luolong forearc basin. The metallogenic geological background and metallogenic geological conditions are superior. It is a favorable area for searching for gold,silver, copper,and lead-zinc polymetallic deposits. In order to preliminarily understand the prospect of mineral resources in the area, a section with large mineralization potential is proposed. The technical method combination of 1 ∶10 000 soil survey,1 ∶10 000 geological mapping,remote sensing geological interpretation,induced polarization sounding,and engineering verification is adopted to conduct a preliminary evaluation of the mining area. Nine gold ore bodies,three gold and silver ore bodies,and four copper ore bodies are found. The genetic type of the deposit is preliminarily determined to be porphyry epithermal hydrothermal type. The ore-forming rock body is a concealed body of biotite monzonite granite porphyry. On this basis,through the comprehensive study of the geological characteristics,geophysical and geochemical anomaly characteristics,and remote sensing image characteristics of the deposit,the prospecting indicators of the deposit are systematically summarized,and three prospecting target areas with great mineralization potential are delineated,which provides a basis for subsequent exploration work deployment. The research results also have important reference and enlightenment significance for regional prospecting in the eastern section of the Bangonghu-Nujiang metallogenic belt.

Deformation Monitoring and Analysis of Tailings Dam Based on DS-InSAR:A Case Study of Brumadinho Mine in Brazil

WU Hao, FAN Hongdong, ZHENG Chunliu, LIU Jiuli

2023, 52(03):  169-176. 

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Tailings pond is a dangerous source of artificial high gravity potential energy. Once the dam breaks,it will seriously pollute the environment and threaten the life and property safety of downstream people. However,the existing deformation monitoring methods of tailings pond have the problems of time-consuming,laborious and high cost. Therefore,this paper propose a deformation information extraction method of tailings pond based on distributed target interferometric radar measurement (DSInSAR),which is helpful to realize high-efficiency and high-precision deformation monitoring of tailings pond. This method uses the FaSHPS (Fast SHP Selection) method based on the parameter hypothesis test to select homogeneous pixels,extracts the dominant scatterer phase through the eigenvalue decomposition of the coherence matrix to achieve phase optimization,and then obtains the time-series deformation information of the tailings pond in combination with the permanent scatterer ( PS). Taking 23 Sentinel-1B images as data sources,this method is used to obtain the time-series surface deformation information of Brumadinho tailings pond in Brazil. The results show that the density of monitoring points of tailings pond obtained by this method is 2. 2 times that of PS-InSAR,and the deformation rate obtained by the two methods has a strong correlation,and the deformation of tailings pond shows a trend of outward diffusion from the middle of dam crest. The correlation analysis between rainfall and deformation shows that rainfall has a significant impact on the deformation of tailings pond. Generally,there are few deformation in dry season,but the opposite in rainy season.


Research on Underground Personnel Unsafe Behavior Identification and Early Warning System Based on Deep Learning

LI Wenjing, LIU Xin

2023, 52(03):  177-184. 

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The unsafe behavior of underground operators is one of the main causes of mine accidents. The existing underground monitoring methods are still mainly manual monitoring,which can not quickly identify the unsafe behavior of operators, resulting in the difficulty of real-time early warning. A deep learning-based development scheme of unsafe behavior identification and early warning system for underground personnel is designed. Firstly,the data set based on underground environment is made,and then the YOLOv4 network model is used to identify miners and safety helmets to judge the wearing of safety helmets. Then,openpose algorithm and ST-GCN model are adopted to identify the miners′ behavior in the monitoring video. Finally,the system is used to automatically warn the unsafe behavior. Combining various deep learning and computer development techniques,a kind of identification and early warning system for unsafe behavior of underground personnel is developed,which provides a new idea for safety management of underground personnel,at the same time,it has reference significance for the construction of intelligent mine.

Construction of Underground Stope Environment Perception Test Platform After Blasting Based on Mixed Reality Technology

QIN Ruibo, ZHU Wancheng, XU Xiaodong, LI Hui, CHEN Chengzhen, SONG Qingwei

2023, 52(03):  185-192. 

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Aiming at the problems of underground production efficiency reduction and personal safety under threat caused by inadequate and untimely perception of hazard sources in underground stope after blasting. This paper designs a test platform of environment perception of stope after blasting based on mixed reality. The test platform is based on HoloLens mixed reality device,supported by monitoring data from various sensors in the stope,combined with intelligent algorithms for stope safety evaluation and remote control technology for mining equipment,build a mixed reality environment with Unity3D development engine,realize the functions of environmental perception of stope after blasting, mine information transparency, remote expert guidance and dangerous scene restoration. Taking Northeastern University′s tunnel simulation training base as the background, by simulating the environment of stope after blasting artificially in the training base,the functions of each part of the test platform were tested. The test results show that the platform perceives and controls the mining environment effectively,and provides a technical guarantee for the safety of underground operations.

Intelligent Scheduling Optimization and Application of New Energy Electric Truck in Open-pit Mine

CHENG Ping, LI Xiaoguang, GU Qinghua, JIANG Song

2023, 52(03):  193-198. 

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With the implementation of the " dual-carbon" strategy,the application of new energy electric trucks in openpit mines has become more and more extensive under the background of green mine construction. In order to improve truck transportation efficiency and reduce mine production costs,a multi-objective scheduling optimization model for open-pit mine new energy electric trucks based on carbon emission costs is constructed by comprehensively considering various influencing factors such as battery power,truck shovel production capacity and ore grade,from the perspective of truck carbon emission costs and mine production indicators. The Non-Dominated Neighborhood Immune Algorithm ( NNIA) is adopted to solve the model. Through the simulation analysis of the production data of a domestic open-pit mine,it is found that the scheduling plan obtained by the established multi-objective optimization model increased the equipment utilization efficiency by 9. 5% and increased the ore transportation volume by 11. 29%. Besides that,it effectively reduces the cost of carbon emissions caused by electricity consumption.

Study on the Selection Algorithm of Mine Mesh Network Access Point Based on Transmission Layer Parameters

LÜ Xiao, ZHANG Yuansheng, YU Qianxiang, ZHAO Dazhuang, LI Ruoxi

2023, 52(03):  199-205. 

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In order to solve the problem that video,voice,command and other information transmission links are easily interrupted due to the congestion of communication network when accidents such as network damage occur in the mining process, a wireless Mesh network is proposed for mine emergency communication,and the Access Point ( AP) selection algorithm of network is studied from the transport layer. Firstly,the end-to-end global transmission delay of the wireless Mesh network is taken as the optimization objective,and the transmission layer delay is used to determine whether the current transmission link is interrupted or the emergency situation of serious bandwidth decline. Secondly,Broadcast Selection Mechanism of Adjacent AP (BSM-AP) is introduced so that communication terminals of the equipment can calculate the delay of information return of different APs without pre-associated AP,and reduce the overhead of system measurement and algorithm selection. Finally,the fuzzy logic method is used to select and access an AP with optimal comprehensive performance. The algorithm implanted on the Qualcomm prototype platform was used to test the transmission success rate of downhole communication information. The test results show that the proposed algorithm can greatly reduce the network delay of critical rescue information and ensure the reliability of transmission.

Study on Hyperspectral Accurate Estimation Method of Iron Grade for Iron Ore Powder

LI Mengqian, LI Mingduo, WANG Jinhua, HAN Xiuli, GAO Huishuang

2023, 52(03):  206-213. 

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Iron grade detection is a key technology in iron ore powder production. In view of the shortcomings of current iron grade detection methods,a mathematical method of iron grade inversion by hyperspectral curve is constructed,which has the advantages of fast detection speed and no secondary pollution. In this paper,54 iron ore samples from Shirengou were selected to measure the iron grade by chemical method,and the hyperspectral curves of the samples were measured by ASD FieldSpec4 spectrometer. It is found that iron ions in iron ore powder exhibit strong absorption characteristics at 526,713,905, 998 and 1 100 nm,and the absorption depth of samples with different iron grades is obviously different,and there is obvious interference noise. Based on the strong correlation between hyperspectral absorption characteristics of samples and iron grade,the Least Squares Method,Robust Estimation and Ridge Estimation were used to model hyperspectral iron grade. The experimental results show that the accuracy of iron grade inversion is different under different constraint rules. The accuracy of the least square estimation inversion is low,the robust estimation can reduce the interference of a few anomalous spectral values,and the ridge estimation can effectively avoid the influence of complex collinearity between parameters on the accuracy. Under the joint constraints of robust estimation and ridge estimation,the model has strong generalization ability and high accuracy of iron grade inversion,which can effectively improve the accuracy of iron grade inversion prediction,and can be used as a basic model for hyperspectral detection of iron grade for iron ore powder.

Effects of Dual Cone Structure on the Flow Field Characteristic and Separation Performance of Hydrocyclones

WEI Kefeng, ZHAO Qiang, KANG Zhangke, ZHANG Shuo, CUI Baoyu, LIU Keshuang

2023, 52(03):  214-221. 

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The separation performance of the compound cone hydrocyclone is generally better than that of the single cone design,but the influence mechanism of the combination method of cone sections on separation process has not been fully understood yet,making the structural optimization of composite cone mainly based on production experience. Taking a laboratory ϕ150 mm hydrocyclone as the research object,the influences of the cone angle (10°,15°,20°,and 30°) and combination order of different conical sections on the flow field characteristics and separation performance of dual cone hydrocyclones were investigated using the RSM turbulence model and TFM multiphase flow model,which were also compared with single cone hydrocyclones. The results showed that the influence of cone angle in the dual cone structure is basically the same as that in the single cone,and its separation performance is just between those of two single-cone structures that make up the double-cone design. The partition curve,however, is mainly dependent on the small cone angle. Different conical sections showed distinct effects on separation process. The large cone mainly controls the centrifugal strength and separation sharpness by affecting the pressure drop and tangential velocity,while the small cone mainly determines the cut size,water split,and particle yield to the underflow by affecting the material packing and axial velocity near the spigot. Under the same operating conditions,the separation performance can be significantly improved by reasonably matching different cone sections. Specifically,DC-Ⅰ (30°+10°) has the smallest cut size (d50 = 15. 34 μm),while DC-Ⅳ (10°+30°) gives the highest cut sharpness (α = 7. 34) and lowest energy consumption (P= 67. 09 kPa). These results can provide theoretical guidance for the structural design and optimization
of dual cone hydrocyclones.


Development and Application of a Permanent Magnet Combined Box Magnetic Separator

ZHANG Xianwei, ZHOU Mingliang, YUAN Zhitao, WEI Bo, LI Lixia, ZHANG Qiang, ZHANG Junfei

2023, 52(03):  222-226. 

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The magnetic separation of coarser magnetite is generally adopted by cylindrical magnetic separator. The finer magnetite can obtain a good magnetic separation effect by using a separation device such as a magnetic separation column. However,the cylindrical magnetic separator and magnetic separation column have low separation efficiency for microgranular magnetite. In order to improve the separation effect of fine magnetite,a permanent magnet combined box magnetic separator was developed by innovative use of mechanical swing magnetic system and compound force field. Its main structure is frame,magnetic system,plate,sorting box,the ore and water feed system,transmission system and so on. The magnetic system of the equipment is oscillated on both sides of the sorting box,so that the strength of the magnetic field varies. The stronger magnetic field strength is conducive for the formation of magnetic chain settlement of fine magnetite, and the weaker magnetic field strength is conducive to the flushing water to disperse the magnetic chain and eliminate inclusion. The equipment uses permanent magnet material as magnetic source,magnetic system is stable and energy saving;Compared with the cylindrical structure such as magnetic separation column,cuboid box structure has lower water consumption and uniform magnetic field distribution in the separation chamber. This equipment is suitable for -75 μm magnetite cleaning operation. By combining the separation box and plate,it can meet the requirements of different scale of the separation plant. For magnetite with -75 μm of 96. 50%,a concentrate with TFe grade of 67. 81% and recovery of 96. 11% was obtained under the condition of feeding grade of 62. 83%.

Development and Test Research of a Periodic Vibrating-Pulsing High Gradient Magnetic Separator

XIONG Tao, HEN Luzheng, XIE Meifang, HUANG Huichun, LIU Xiangmin, LI Yuhan, WANG Zedong

2023, 52(03):  227-233. 

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Aiming at solving the problems of mechanical inclusion and relatively low concentration ratio of concentrate in the current high gradient magnetic separators,a vibrating matrix was introduced into the high gradient magnetic separation process to form a vibrating-pulsating coupling force field,to improve the separation accuracy. A new type of periodic vibratingpulsating high gradient magnetic separator was then developed and used for the separation of an ultra-fine copper-molybdenum mixed concentrate. The results showed that the pulsating field is beneficial to slurry dispersion and to washing the adsorbed minerals on the surface of magnetic matrix,while the vibrating field further reduces the inclusions of non-magnetic particles, thereby increasing the collision probability of magnetic matrix with magnetic minerals and generating an obvious improvement on the concentrate grade and recovery. For the ultra-fine copper-molybdenum mixed concentrate assaying 26. 12% Cu and 0. 36% Mo,this new magnetic separator produced a high-quality copper concentrate assaying 0. 07% Mo at a yield of 42. 53% and 50. 42% copper recovery;meanwhile,the molybdenum concentrate produced from the separator assays 0. 57% Mo at a molybdenum recovery reaching 91. 56%. The molybdenum removal rate reached 80. 56% at a separation efficiency of 40. 61%, showing a significant copper-molybdenum separation performance. The size-by-size recovery analysis of the copper and molybdenum concentrates indicates that the separator may effectively separate this fine copper-molybdenum mixed concentrate. This new high gradient magnetic seaprator has provided a new technical sulotion for the high-efficient separation of fine weakly magnetic ores.

Land Use Classification of Xilinhot Open-pit Mining Area Based on GEE and Multi-dimensional Features in Recent 30 Years

ZHANG Laihong, QIN Tingting, ZEREN Zhuoge, ZHANG Haitao, SHE Changchao, LI Jun, ZHANG Chengye

2023, 52(03):  234-241. 

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With the continuous exploitation of mineral resources,land use types in mining areas change frequently. Obtaining the results of long-term land use classification in mining areas is of great significance to land management and ecological reconstruction in mining areas. Based on the Google Earth Engine,this paper constructs a multidimensional feature set for sentinel-2 and Landsat data from three aspects:spectral features,texture features,and terrain features. The random forest algorithm was used to build different feature models separately and test the accuracy to filter out the optimal classification model for the mining areas. A long-time series land use classification study was conducted by using the open-pit mine in Xilinhot as the study area in recent 30 years (from 1991 to 2020). The results indicate that:① Based on the GEE remote sensing cloud platform, the land use classification results of the study area in the past 30 years from 1991 to 2020 can be extracted efficiently,quickly and accurately. ② The spectral features play a decisive role in classification accuracy,and the incorporation of texture features and terrain features can effectively improve the accuracy of the land use classification model in mining areas. ③ The unique red-edge band of Sentinel-2 has a high sensitivity to vegetation,which can effectively improve the classification accuracy. The long-term continuous monitoring results can effectively understand the changes and laws of land use in Xilinhot open-pit mining area,and provide a solid data support for further analysis of the impact of human production and living and environmental changes on land use.

Study on the Spatio-temporal Variation Regularity of Ecological Environment before and after Mine Closure Based on Remote Sensing Ecological Index

QIN Lu, CHEN Bingqian, YU Yang, YANG Jiale, YANG Yu

2023, 52(03):  242-249. 

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Our country is rich in coal resources. While the mining of coal resources plays a supporting role in local social and economic development,it also has a major impact on the ecological environment around the mining area. In recent years, due to the depletion of some coal mine resources and the promulgation of the national overcapacity reduction policy,a large number of coal mines have been closed. Existing research focuses more on the changes in the ecological environment during the mining process,and seldom involves research on the changes in the ecological environment after mine closures. For this reason, this paper takes the Jiawang closed mining area in Xuzhou as the study object,selects Landsat 5 and 8 images from 2009 to 2021,and uses the Remote Sensing Ecological Index (RSEI) method to dynamically monitor the temporal and spatial evolution of the ecological environment in the Jiawang mining area before and after the closure. The study results show that the overall ecological quality of the mining area is on the rise after the mine is closed. The RSEI value of Quantai Mine will increase from 0. 432 in 2009 to 0. 568 in 2021,and the RSEI value of Qishan Mine will increase from 0. 490 to 0. 546. The proportion of areas with poor and poor ecological grades in the Jiawang mining area is decreasing,from 41. 51% in 2009 to 29. 06% in 2021; while the proportion of areas with good and excellent ecological grades is increasing,from 36. 4% in 2009 to 47. 36% in 2021. In addition,areas with a low ecological index are not stable,and the center of gravity migration more obviously,while areas with a higher ecological index are relatively stable and concentrated. The visual comparison of the ecological results with the highresolution images shows that it is reliable to use the Landsat remote sensing image with 30 m resolution to evaluate the RSEI index of Jiawang mining area.


Study on Remediation Effect of Glomalin Related Soil Protein on the Ecological Environment of Vanadium-Titanium Magnetite Tailings

LU Sai, GU Haihong, AI Yanjun, ZHANG Yixuan, LI Fuping

2023, 52(03):  250-258. 

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In order to investigate the effect of Glomalin related soil protein (GRSP) released by Arbuscular mycorrhizal fungi (AMF) on the ecological restoration of vanadium-titanium magnet tailings,laboratory culture experiments of alfalfa were carried out. Exogenous applied different forms and doses of glomalin related soil protein to study the nutrient environment,aggregate structure and heavy metals availability in vanadium-titanium magnetite tailings. The results showed that the nutrient environment of vanadium-titanium magnetite tailings was significantly improved after GRSP was applied. The content of available phosphorus in vanadium-titanium magnetite tailings increased by 19. 7% ~ 60. 1% with EEG. TG effect was more significant, and the content of alkali-hydrolyzed nitrogen and available phosphorus increased by 12. 2% ~ 58. 9% and 44. 7% ~ 111. 3%,respectively. The increase of phosphoric acid is beneficial to enhance the precipitation of heavy metals. TG improve the stability of the aggregate structure of vanadium-titanium magnetite tailings,it can increase the proportion of large aggregates,the mean weight diameter and geometric mean diameter of vanadium-titanium magnetite tailings by 29. 36% ~ 114. 63%, 4. 76% ~ 15. 87% and 9. 26% ~ 16. 67%,respectively,which is beneficial to improve the retention capacity of vanadium-titanium magnetite tailings to heavy metals and nutrients. The effects of two GRSP forms on different heavy metals in vanadium-titanium magnet tailings are different,EEG can significantly reduce the availability of Cu,and the content of Cu extracted from DTPA decreases by 16. 7%;TG can passivate Cr,the content of Cr extracted from DTPA decreases by 72. 6%. In addition,the addition of sodium citrate inhibited the growth of alfalfa. Comprehensive analysis showed that the GRSP could change the availability of heavy metals and improve nutrient environment and aggregate structure in vanadium-titanium magnetite tailings,which could provide theoretical basis for ecological restoration in tailing areas.

Experimental Study on Synergistic Removal of Cu(Ⅱ ) in Simulated Mineral Processing Wastewater by Xanthan Gum and Butyl Xanthate

ZHANG Guoyang, YANG Zhichao, TENG Qing, HAN Yingqi, ZHANG Suhong, LIU Shengyu

2023, 52(03):  259-265. 

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Aimin at the problems that xanthan gun adsorbent is hydrophilic and difficult to separate from water,butyl xanthate was added for coprocessing Cu (Ⅱ ) in simulated wastewater. The suitable processing parameters were determined by condition experiments,and adsorption mechanism was analyzed through the Zeta potential,FTIR and XPS. The Cu(Ⅱ ) removal rate reached 87. 44% with the dosage of xanthan gum of 50 mg / L,the pH value of solution of 6,the stirring time of 30 min and the initial concentration of Cu(Ⅱ ) of 60 mg / L. On the basis of the above conditions,adding 40 mg / L butyl xanthan combined with xanthan gum to remove Cu(Ⅱ ),the removal rate reached 99. 86%,increased by 12. 42 percentage points. The adsorption mechanism of Cu( Ⅱ ) in wastewater by xanthan gum includes the electrostatic interaction between the negatively charged xanthan gum and the positively charged metal ions,and the coordination complexation between the unbonded electrons of the oxygen in the hydroxyl and carboxyl groups of xanthan gum and the vacant orbital of Cu( Ⅱ ). The S in butyl xanthate can provide electrons for the vacant orbital of Cu(Ⅱ ),which further enhances the adsorption effect and significantly increases the removal rate of Cu(Ⅱ ). The results provide a new idea for the efficient removal of heavy metal ions.

Parameter Inversion and Damage Research of Cement-Stabilized Steel Slag Discrete Element Model

WANG Shuyong, CHEN Guoxin, XU Yuhan, SU Wanzhong, ZHAO Xuzhang

2023, 52(03):  266-273. 

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Based on three-dimensional scanning technology,the discrete element model of cement-stabilized steel slag with real steel slag shape is constructed by Particle Flow Code 3D. The sensitivity between macro and micro parameters of the sample is explored and the nonlinear regression equation is established. The uniaxial compression simulation tests are carried out on the samples with different steel slag contents. Combined with the custom programs such as contact calculation and crack location,the macro and micro mechanical properties and micro-crack evolution law of the samples during the failure process are analyzed from the aspects of strength and fracture damage. The results show that the peak strength is directly proportional to the tensile strength and inversely proportional to the porosity. The elastic modulus is greatly affected by porosity,effective modulus, bond strength and parallel bond friction angle. Poisson′s ratio is mainly controlled by porosity. With the increase of steel slag content,the elastic modulus and peak strength of the samples increase,the Poisson′s ratio decreases,and the post-peak stress curve steepens,showing obvious brittle failure characteristics. The fracture formation can be divided into four stages:initiation, propagation,convergence and penetration. With the increase of steel slag content,the fracture surface thickness of the sample increases,and the number of micro-cracks increases exponentially.

Research on Preparation and Performance Optimization of Slag-Fly Ash Geopolymer Grouting Material

WANG Bo。WEN Hua

2023, 52(03):  274-278. 

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In order to reduce the use of cement in grouting materials and develop new grouting materials,fly ash and slag as the precursor,using alkali excitation method to prepare geopolymer grouting materials. The polypropylene fiber was added for performance optimization of grouting material,and the effects of polypropylene fiber on the workability,mechanical properties and microstructure of geopolyolytic grouting materials were studied. The results showed that the addition of fiber can increase the setting time and decrease the fluidity of geopolymer grouting material. The addition of fiber can significantly improve the compressive strength,flexural strength and frost resistance of geopolyster grouting material,and reduce the drying shrinkage rate of the material. Comprehensive test results showed that the optimal fiber content is 3%. The microstructure test results showed that the microstructure of geopolymer grouting material is more uniform and compact after adding fiber. Fiber can be used as micro-aggregate in geopolymer grouting material to optimize the properties of the material.