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    15 September 2020, Volume 49 Issue 09
    Study Progress and Development Directions of the Prevention and Control Technology of Ground Water Pollution in Coal Mine Sites
    DU Mingze, LI Hongjie, LI Wen, QIU Hao, JIANG Peng, WANG Donghao
    2020, 49(09):  1-14. 
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    At present,the prevention and control of groundwater pollution in coal mine sites was still in the primary stage,the lack of a groundwater pollution prevention and control system for the entire life cycle of a mine caused some problems such as improper prevention and control of groundwater pollution and aggravation of pollution,etc..Based on the scientific definition of pollution sites and groundwater pollution assessment units in coal mine sites,study progress and development directions of the monitoring,early warning,prevention and control technology of groundwater pollution in coal mine sites were discussed.Based on the definition of contaminated sites,the groundwater contaminated site and groundwater contaminated flow field units in the coal mine sites were scientifically defined,and the scopes of groundwater contaminated site and groundwater flow field assessment in the coal mine sites were also defined.The types and patterns of groundwater pollution in coal mine sites were analyzed,and the main characteristic pollution factor during coal mining and pit closure were explained.Based on the groundwater pollution risk theory,the status quo of groundwater pollution monitoring and early-warning technology in coal mine sites were analyzed.From the perspectives of mine production and pit closure,the existing water-preserved-mining technology methods based on strata control,blocking materials,and underground water storage were described.The active and passive technical means of the process of pit closure and groundwater pollution prevention and control after the pit closure were described.Based on the above analysis results,according to the characteristics of different stages of the entire life cycle of mine,it points out that development directions of the prevention and control technology of ground water pollution in coal mine sites are mainly for conducting accurate detection of groundwater pollution,study and development of intelligent identification,monitoring and early warning technology and equipment of specific pollutant,study the key technologies such as source control,process blocking and end remediation of groundwater pollution in coal mining area,so as to form the technical system and standard prevention and control of groundwater pollution throughout the life cycle of coal mining area.The above study results can provide certain reference for the prevention and control of groundwater pollution in mines.
    Study on Measure Evaluation of Synergy Degree of Synergy Mining Methods
    CHEN Qingfa, HU Huarui, JIANG Tenglong
    2020, 49(09):  15-25. 
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    The measure evaluation of synergy degree of synergy mining methods has been an unsolved scientific problem in mining engineering.Mining methods were divided into the system structure of three-layer sub-system,and on this basis,the structure pattern graph of the synergy elements in the synergy mining method was drawn.A measure evaluation model of synergy degree of synergy mining methods was created by introducing the concept of synergy entropy.Based on the revised analytic hierarchy process and entropy weight method,the weighting method of each subsystem's synergy degree evaluation index was determined.According to the classification standard of the system synergy degree,the application process of the synergy entropy evaluation model is comprehensively illustrated with the example of pseudo-inclined pillar mining method for combined operation of electric rake and blasting force,and the statistical analysis of the synergy degree of the 19 synergy mining methods invented by Chinese scholars in the recent decade was made.The study results show that the structure pattern diagram of the synergy elements in the synergy mining method clearly shows the synergy relations among the elements and the structural relations among the technological links.The sample mining method is generally in the state of a basic synergy,in which stope mining, stope structure,ore removal and ore transport are in the states of good synergy,slightly unsynergy and highly synergy respectively.Among the 19 synergy mining methods,8 are in a basic synergy state,7 are in a good synergy state and 4 are in a highly synergy state.The above discussion results can provide reference for the evaluation of technical level of synergy mining methods.
    Study on the Resistance of Cemented Paste Backfill Slurry Pipeline Transport Considering Wall Slip Effect
    GAN Deqing, YAN Zepeng, XUE Zhenlin, LIU Zhiyi, SUN Haikuan
    2020, 49(09):  26-32. 
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    n order to explore the variation characteristics of the transport resistance of cemented paste backfill (CPB) slurry under the influence of wall slip effect,a pipeline transportation model considering the effect of wall slip was established,and the influence of slurry concentration,pipe diameter and ash-sand ratio on pipeline resistance loss was analyzed by using Comsol numerical simulation software.The study shows that:① The relative error of the simulation results is within a reasonable range,and the model is used to calculate the resistance of the filling slurry pipeline by considering the wall slip effect is reliable;② Considering the wall slip effect,order of the influence degree of each factor on the pipe resistance is the pipe diameter,mass concentration and lime sand ratio,the pipe diameter is increased,the wall shearing force is reduced, and the migration movement of the particles is slower and slipper,the shift effect is weakened,and the decrease in the resistance of the pipeline is reduced;③ The main controlling factors of the thickness of the slurry slip layer in different concentration ranges are different,which leads to different amplitudes of transport resistance increase with concentration;④ When the cement to tailings ratio relatively low, the growth rate of the pipeline transportation resistance is low,as the cement to tailings ratio increases,the pipeline transportation resistance increases rapidly.Numerical simulation was carried out with a mine in Eastern Hebei Province as the study background,and the best parameters for pipeline transportation of filler slurry are determined as concentration 66%,68% ,and the cement-sand ratio is 1∶8.
    Study on Pressure Loss and Optimization of L-shaped Filling Pipe Slurry
    KANG Zhiqiang, XIN Dongfu, SHAO Luhang, ZHANG Chen
    2020, 49(09):  33-40. 
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    In the pipeline transportation of unclassified tailings slurry, the bottom of the slurry pipeline is worn out, which greatly affects the service life of the slurry pipeline. Based on the filling status of the L-shaped pipeline of a tailings slurry of an iron mine in Tangshan,the minimum pressure loss of L-shaped pipeline was taken as the principle to conduct study work.The filling slurry with the ratio of cement to sand ratio of 1∶4,1∶6,1∶8,slurry concentration was 54%,58%,62%,and the test was carried out at 3,5,7 m/s is the slurry flow rate.The pressure loss of the pipe diameters of 70,80,90,100 mm is calculated based on the 3D numerical model by using COMSOL Multiphysics numerical simulation software,besides that,the influence factors of pressure loss were analyzed and optimized.The study results show that the larger the diameter of the pipe,the greater the pressure of the 45° section,and the pressure loss of the L-shaped pipe is quadratic polynomial function;the diameter of the pipe is reduced to 70 mm or increased to 100 mm,which will accelerate the abrasion of the bottom of the L-shaped pipe.In order to extend the service time of the L-shaped pipeline in the mine and minimize the wear of the bottom of the pipeline,it is suggested that diameter of the L-shaped filling slurry conveying pipeline of the mine can be determined as 85 mm ,the slurry flow rate is 3 m/s,the cement-sand ratio is 1∶4 and the mass concentration is 64%.
    Study on Preparation and Hydration Mechanism of Composite Cementitious Materials using Molybdenum Tailings
    WANG Changlong, YE Pengfei, ZHANG Kaifan, HAN Guosong, HUO Zekun, ZHAO Gaofei, REN Zhenzhen
    2020, 49(09):  41-47. 
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    The composite cementitious materials were prepared using molybdenum tailings for enhancing the utilization of solid waste resources.In order to solve the environmental and safety problems caused by tailings accumulation,and provide the corresponding theoretical basis,the research focuses on effects of grinding time and contents of molybdenum tailings on properties of cementitious materials and hydration mechanism of composite cementitious materials were conducted by means of particle size analysis, mechanical properties testing, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicate that: ① when the grinding time was 80 min and the specific surface area was 500 m2/kg, the 28 d activity index of the molybdenum tailings was close to 1.2. The mortar block of 28 d compressive strength is about 52 MPa when cementitious materials is consisting of 40% molybdenum tailings, and the mass ratio of cementitious materials to standard sand is 1∶3 with the water-cement ratio of 0.5. ② The hydration products of composite cementitious materials are calcium silicate hydrate and ettringite at early stage, which provided the early strength for the mortar block strength. The main products in the later hydration reaction are C—S—H gels, calcium aluminate hydrate and ettringite (AFt), and mortar block strength is provided by the aggregation effect of residual tailings particles and hydration products.
    Effects of Early Strength Accelerators on the Strength of Filling Body Comprised of Consolidated Powder and Mixed Aggregate
    YANG Xiaobing, GAO Qian, WANG Yongding, HE Jianyuan
    2020, 49(09):  48-53. 
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    For the utilization of waste rock and consolidated powder in Jinchuan mining area,firstly,the particle size grading analysis of mixed aggregate was carried out with different ratio of waste rock to rod mill sand.The results show that the packing density and Talbol power index n of the mixed aggregate with ratio of 4∶6 were 0.635 and 0.591 respectively.Then,as the ratio of waste rock in mixed aggregate increasing from 10% to 50%,unconfined compressive strength tests were taken for the filling body with and without early strength accelerators respectively.The study results show that the strength of fill body increases firstly and then decreases as the increasing of waste rock content.When the ratio of waste rock is 40% and the slurry mass concentration is 79%~81%,the average strength of fill body without early strength accelerators in three curing periods (3 d,7 d and 28 d) was 1.23 MPa,3.79 MPa and 5.98 MPa respectively,and its early strength is lower than the mine designed strength.By adding early strength accelerators,the average strength of filling body in three curing periods reached 1.55 MPa,3.34 MPa and 6.46 MPa respectively,meeting the needs of cemented backfill strength by the downward slicing drift mining operation in Jinchuan mining area.Therefore,with cement- aggregate ratio of 1∶5,waste rock-rod mill sand ratio of 4∶6,slurry mass concentration of 79%~81%,the mixture comprised with consolidation powder,mixed aggregate and 1% early strength accelerators could be widely applied in Jinchuan mining area.
    Test Study on the Effect of Particles Size Fraction on Natural Repose Angle of Ore-rock Dispersion
    CHANG Shuai, LI Nan, CONG Longsheng, YAO Baoshun, LI Shufeng
    2020, 49(09):  54-59. 
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    The accumulation of ore-rock dispersion is common in mining production and is one of the main factors affecting mine production safety and ore recovery.The angle of accumulation (natural repose angle) of dispersion is one of the main characteristics of its liquidity,and also an important physical parameter.Self-made measuring device is used to conduct physical test,so as to study the variation regularity of natural repose angle of ore and rock mass dispersion with different granule grades under static and stope ore-drawing conditions.The results show that under static and stope ore-drawing conditions,the natural repose angle increases when the size fraction of particles increase,its natural repose angle is increasing gradually, and in the nonuniform ore and rock mass,with the increase of the proportion of granular ore and rock mass,its natural repose angle is also increasing gradually.The static test conditions are similar to ore drawing in pass,ore drawing in funnel and accumulation in dump,when selecting the slope angle of the ore-drawing through the well and funnel,determining the floor area and slope angle of the dump site,the corresponding parameters can be adjusted according to the particle size.According to the test results of ore-drawing conditions in stope,appropriately increasing the particle size can reduce the distance from ore outlet and the volume of the bulk,improve the operating conditions of the scraper,and improve the production efficiency.The fluidity of small granule dispersion is better than that of large granule dispersion,the granule of overburden should be larger than that of ore,which is beneficial to ore outflow.
    Influences of Initial Movement of Ore or Rock Block on the Rule of Impacting on Orepass Wall
    LU Zengxiang, WU Xiaoxu, MA Chi, YIN Yue
    2020, 49(09):  60-64. 
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    The moving ore-rock block in the orepass will collide with the wall of the orepass and lead to the impact damage of the orepass wall.The study of the movement law of ore or rock block in an orepass is beneficial to reduce the collision rate between the ore-rock block and the orepass wall.Based on the kinematic principle,the relation model of the initial direction of the ore or rock block movement and its motion law is established,the movement track equation of the ore or rock is obtained,the condition of collision with the orepass wall during the movement of the ore or rock block is established,the calculation formula of the first time collision point of the ore or rock block and the orepass wall is obtained,and the influence of the initial movement of the ore-rock into the orepass is studied.It is found that:① the diameter D of the orepass, the initial velocity [v0] and direction [α] of the ore or rock block are the main factors affecting the collision between the ore or rock block and the orepass wall;② when D and [v0] remains unchanged, the value of collision position h1 increases with the increase of [α],and vice versa,the smaller the value of h1 is; ③ when D and [α] remains unchanged, with the increase of [v0],the value of collision position h1 is smaller,and on the contrary,the greater the value of h1 is;④ when and remains unchanged, with the increase of D,the value of collision position h1 is larger,and on the contrary, the smaller the value of h1 is.The study results further show that the collision probability between the ore or rock block and the orepass wall could be reduced by properly increasing the diameter of orepass,selecting the appropriate structure and reducing the speed of the ore or rock block entering the orepass,which is beneficial to reduce the degree of impact damage of the ore or rock block.
    Characteristics of Ore or Rock Movement in Inclined Orepass and Its Damage and Failure to Orepass Wall
    MA Chi, WU Xiaoxu, LU Zengxiang
    2020, 49(09):  65-71. 
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    The inclined orepass is an important layout method in mines at home and abroad and its deformation and failure are a serious problem in the engineering application.The root cause of the deformation and failure of orepass wall is that the ore or rock dispersions contact and make a force with the orepass wall during their moving in orepass.Different ore-rock movement characteristics in inclined orepass lead to large differences in the degree and scope of deformation and damage of orepass walls in different areas.The deformation and failure mechanism and the failure zone of inclined orepass wall were analyzed by studying the movement characteristics and its influencing factors of ore-rock dispersion moving in inclined orepass.The study results show that: ①Different ore-rock movement modes are affected by factors such as the dip angle of the slip shaft, the shape,particle size and distribution characteristics of the ore block,the physical and mechanical properties of the ore rock,the flatness of the orepass wall and the initial movement direction of the ore block when entering the slip shaft.The damage characteristics to the orepass wall are also different.②The impact damage of the orepass wall caused by the falling or jumping of the ore-rock block mainly occurs at the bottom of the orepass in the direction of the falling rock at the intersection of the branch and the main orepass,and the friction damage of the orepass wall caused by rolling or sliding is mainly distributed on the bottom plates of the branch and the main orepass. ③ According to the deformation and damage characteristics of different orepass wall,it should be prevented from the perspective of optimizing the structure of the orepass and taking corresponding reinforcement measures.
    Study on the Main Influencing Factors of the Critical Medium Column
    ZHANG Dongjie, REN Fengyu, ZHENG Youwei
    2020, 49(09):  72-79. 
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    When underground mines are mined by the open stpoe method or the caving method,the roof will cave.After the caving of the roof strata has developed to the surface,the rock movement will pose a serious threat to the surface industrial facilities and the environment.The theory of critical medium column provides a new idea for surface rock movement control.Taking the mining status of the Xilinhaote Fluorite Deposit with the steeply inclined medium-thick orebody which using short-hole shrinkage method as the engineering background,the main influencing factors of the critical bulk column are studied through field monitoring investigation and similar physical tests.The results show that:① The height of the critical medium column decreases with the increase of the dip angle of the ore body. With the progress of the underground ore drawing, the height of the loose body column is only 39.4%~45.7% of the total height of the bulk,the dense scattered columns above it play a major role in restricting rock movement.② For different ore body thicknesses,by increasing the filling height of the scattered body and reducing the thickness-span ratio,the surface subsidence range can be controlled.③ Proper deformation of the surrounding rock can increase the passive side pressure of the bulk,and reduce the critical medium column height required for the stability of the rock mass of the collapse pit.④ The arch characteristics of the collapse pit are affected by the granularity of the bulk and the collapse pit width,and control the effective height of the critical medium column.The critical arch size range of the Xilinhot Fluorite Deposit is 0.5~0.7 m ,and the critical arch width is 3.5~4.0 m,which is much smaller than the actual distribution width of the collapse pit,that is,the bulk can maintain continuous flow.The above discussion result further indicated that the critical medium column theory can be well applied to Xilinhot Fluorite Mine.
    Study on the Determination of Optimal Blasting Delay Time of Inducement Dilapidation of the Roof in an Underground Mine
    JIANG Fuliang, GUO Jintao, YANG Wenchao, ZHANG Chao, ZHANG Honghao, MA Yikun
    2020, 49(09):  80-86. 
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    Reasonable selection of the delay time of induced caving blasting in the goaf roof can effectively improve the effect of induced caving. In order to determine the optimal delay time of millisecond delay blasting in goaf, after analyzing the technical principle of induced caving, using the delay time as the starting point, combined with the actual situation of an underground mine, a numerical simulation model of induced caving blasting was established. Using the LS-DYNA finite element analysis software to simulate the explosion process with delay time of 20 ms, 35 ms and 50 ms respectively, the stress cloud diagram of the explosion process and the curve of the effective stress of each observation point with time are obtained. The simulation results show that the minimum stress and maximum value of the central part of the roof is affected by the blasting delay time, and the corresponding delay time was 35 ms when the maximum effective stress at both ends of the roof was the lowest. When judging by the proximity between the maximum effective stress and the compressive strength of ore and rock, it was concluded that the induction effect is the best when the delay blasting time between presplitting blasting and roof caving blasting was 20 ms.By comparing and analyzing the change of effective stress at each observation point, it is determined that the effect of induced caving is the best when the delay time is 20 ms. The study results can provide a reference for the optimization of blasting parameters in mines by adopting induced caving method.
    Study on Monitoring Site Selection Model of Mining Area Based on Geographical Scene
    LI Wenjing, HU Dan, LI Nan
    2020, 49(09):  87-95. 
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    Intelligent mining platform carries out real-time measurement, control and digitization of mine, human,machine and environment.It can enable the whole mine to have the ability of self-analysis and decision-making,so as to realize the visualization, automation,intelligence and unmanned in the process of mine production management,and achieve the goal of high yield,high efficiency and safety.The construction of geo-video system is an important means to solve the safety problem in the intelligent mining platform.In view of the location problem of geo-video monitoring equipment in the mine safety,this paper proposes a location model of mining monitoring based on geographical scene.Firstly, this model extracts a set of extensible geographic scene semantic classification models for monitoring location by comparing and analyzing four aspects of geographic entities,geographic scenes,and monitoring equipment and location principles in several typical semantic models.Then,the monitoring candidate group and the horizon range of monitoring equipment are input as parameters into the set coverage model based on monitoring location selection,and the linear programming method is used to solve the problem.Finally,the test results of a mining area proves that the model can scientifically and reasonably locate monitoring equipment in the study area.The experimental results show that the candidate points are evenly distributed and have certain regularity.This proofs that the method can replace the previous manual screening methods,improve the efficiency and accuracy of site selection,and has a better stress capability for the ever-changing monitoring requirements and environmental elements.
    Study on the Stability analysis and Reinforcement Technique of a Large Underground Chamber Group
    XIAO Yigai, LIU Yunqiu, WANG Weiping, WANG Yubo, XIA Caichu, XU Chen, Lü Zhitao, LIN Ziliang
    2020, 49(09):  96-103. 
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    A large underground cavern group as historical relics generally lasts for hundreds of years or even thousands of years,which level of security is different from general rock mass engineering,under the influence of various factors,large cavern group of rock mass structural stability and strength are reduced,eventually lead to the instability of rock mass, damage,therefore,it is necessary to conduct stability analysis of rock mass and reinforce technique study of the large underground chamber group.The large underground chamber group construction project belongs to the large underground rock mass excavation project.Before the excavation of the rock mass project,the engineering geological survey results show that the overall stability of the rock mass of the chamber group is good,and the stability analysis is carried out by the stability empirical evaluation method,it is found that the overall stability of the chamber group is good.Based on the above discussion results,the three-dimensional numerical simulation method is used to evaluate the overall stability of the chamber group.The calculation results are basically consistent with those of the engineering geological survey and the stability empirical evaluation method.The surrounding rock of the large chamber group after excavation is generally in a stable state.In view of the local fault fracture zone and the instability hidden danger of the local block in the adit,the reinforcement scheme of anchor net spraying,which is based on the combination of anchor bolt, grouting and pouring concrete is proposed,it is help for effectively ensuring its safety and stability.
    Study on Mineral Processing Technology of a Refractory Copper-lead-zinc Ore with High Sulfur and Arsenic from Inner Mongolia
    SU Jianfang, XIAO Qiaobin, WANG Zhongming, TAN Xin, LIU Fang, LIU Shujie, LING Shisheng, LU Dongming
    2020, 49(09):  104-110. 
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    A copper, lead and zinc sulfide ore from Inner Mongolia belongs to high-sulfur and high-arsenic with the contents of copper, lead and zinc of 0.26%, 0.72% and 4.60%, respectively, and the contents of sulfur and arsenic in the ores are 13.14% and 2.49%, respectively. In order to realize the effective recovery of copper, lead, zinc and sulfur in the ores and avoid a series of problems caused by traditional high alkalinity method, the conditions tests of copper-lead bulk flotation, magnetic separation for desulfurizing and zinc flotation were studied. The whole process closed-circuit test including the copper-lead bulk flotation with roughing concentrate regrinding cleaning, magnetic separation for desulfurizing with bulk tailings and zinc flotation was conducted based on the conditional test. Finally, the copper and lead mixing concentrate with the copper of 9.27%, the lead of 40.53% and the silver of 4 397.76 g/t were obtained and the recovery rate was 59.22%, 88.93% and 74.05%, respectively. The zinc concentrate with zinc grade of 45.94% and zinc recovery rate of 93.10% was obtained, which realized the effective recovery of associated silver and reduced the harmful impurity arsenic contents in the concentrate.
    Experimental Study on Flotation of a Low-grade Copper-zinc Sulphide Ore in Abroad
    ZOU Qin, LONG Bing, LEI Xiaoming, YANG Chang'an, LIU Cheng
    2020, 49(09):  111-117. 
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    A low grade overseas copper-zinc sulfide ores belong to skarn type. In order to determine the feasibility of the development and utilization of valuable metals in the ore, the dressing experiment was carried out. The reasearch showed that the copper and zinc grade in the ore is 0.38% and 1.26%, respectively. According to the composition properties of the ore sample, the process was established to select the copper minerals first, and then the zinc minerals. In the condition of grinding fineness of -0.074 mm accounting for 74.60%, copper sulfide precedence flotation was conducted using lime as the pulp pH regulators, zinc sulfate and sodium sulfite as mixed depressant and Z-200 as collector. Then, zinc minerals were floated from the copper flotation tailings using lime as pH adjustor, copper sulfate as activator and butyl xanthate as collector. By the closed-circuit flotation test of "two roughing and two cleaning" for copper, “one roughing, three cleaning and two scavenging” for zinc, the Cu grade and recovery rate was 22.55% and 85.19%, respectively in copper concentrate, and Zn grade and recovery rate was 44.83% and 74.36%, respectively in zinc concentrate, which achieved the separation and recovery of copper and zinc sulphide minerals effectively and provided a reference for the development and utilization of overseas sulphide ore.
    Experimental Study on Improvement of the Leaching Properties for Zijinshan Copper Ore with High Voltage Pulse Breakage
    HUANG Liefeng, HE Zeming, LIU Weichao, ZUO Weiran
    2020, 49(09):  118-124. 
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    In order to investigate the influences of high voltage pulse breakage (HVPB) and mechanical breakage on particles properties and column leaching efficiency of Zijinshan copper ore, mechanical breakage and high voltage pulse breakage with charging voltages of 110 kV and 135 kV, respectively, were used to crush the copper ores with the fraction from 6.7 to 9.5 mm. The properties of progeny particles were measured, including exposure degree of metallic mineral on surface, existence of cracks, aspect ratio, circulartiy and saturated water content of ore heap and the clumn leaching were carried out using the copper ores from different breakage ways. The results indicated that only 1.6% of the particles had metallic minerals exposed on particle surface, and 2.5% of the particles had cracks existed on particle surface for mechanical breakage product. While these two proportions had increased to 3.4%~3.7% and 7.3%~17.2% respectively for HVPB products, which made the leaching solution easier to contact the metallic minerals inside the ore particles. The averaged aspect ratio of HVPB product was 1.42, lower than that of mechanical breakage product of 1.51. As a result, the permeation capacity of leaching solution along the major axis of the progeny particles of HVPB was higher than that of mechanical breakage product for 3.3%~3.5%. In comparison with the mechanical breakage product, the product of HVPB had slightly higher circulartiy and ore heap saturated water content, which could slightly improve the fluidity of the leaching solution on the particle surface and inside the ore heap. Column leaching tests were conducted for the product of different breakage methods and different size fractions. After 21 days for leaching, the copper leaching rate of HVPB product was found to be higher than that of mechanical breakage product by 6.6~11.1 percent, indicating that HVPB can effectively improve the leaching properties for Zijinshan copper ore.
    Experiment on Improving the Gold Recovery Rate of a Low-grade Gold Mine in Henan
    NI Qingqing, GAO Zhi, SONG Zuguang
    2020, 49(09):  125-130. 
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    A low-grade gold deposit in Henan province are characterized by uneven grain size, wide grain size distribution and serious gangue inclusion, which makes it difficult to recover the gold minerals. In order to improve the recovery rate of the gold, a series of beneficiation experiments were carried out on the basis of mineral processing. The results showed that:①the main useful mineral of the raw ore is native gold. The gold grade is 1.39 g/t in the raw ores. The grade of the siliver is 3.35 g/t, which could be recycled as the associated metal. The secondary metal minerals are mainly pyrite, with a small amount of chalcopyrite, magnetite, bismuth and galenite. The gangue minerals mainly are quartz, plagioclase, chlorite, mica, dolomite and calcite, followed by a small amount of amphibole. ②Gold particles mainly exist in the form of wrapped gold accounting for 58.83%, followed by cracked gold accounting for 23.53% and intergranular gold accounting for 17.65%, in which the gold in quartz accounting for 19.11% of the gold. ③Under the best test conditions, the combined process with gravity separation and flotation was adopted. After three times Nelson gravity separation and one cleaning with shaker, the heavy separation tailings were floated by one roughing, two cleaning and two scavenging. Finally, the gravity sand contains 986.60 g/t of gold, the gold recovery rate of 50.42%, and the flotation concentrate contains 35.75 g/t of gold, and the gold recovery rate of 41.57% were obtained. The total recovery rate of the gold in the whole process reached 91.99%, which well completed the recovery of the gold in the mine.
    Flotation Tests of a New Collector DTL-1 on Suspension Roasted Gibbsite
    ZHU Yimin, WANG Yan, ZHANG Jing, GU Xiaotian, LI Yanjun
    2020, 49(09):  131-136. 
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    Anionic collector DTL-1 was a new collector developed by Northeastern University for the reverse flotation dealumination test of suspension roasting magnetic separation iron concentrate. Flotation tests were carried out by collector DTL-1 on the aluminum mineral sample which was pure gibbsite treated by suspension roasting and the artificial mixed minerals of aluminum mineral sample and hematite mineral sample which was pure hematite and pure gibbsite treated by suspension roasting-magnetic to test the dealumination effect of collector DTL-1. The results showed that DTL-1 had a good effect on the collection of aluminum mineral at room temperature. In the artificial mixed minerals, the mass ratio of iron mineral sample to aluminum mineral sample was 15.67∶1, the grade of Al2O3 was about 5.95%. When the pH value was 8.0, the recovery rate of Al2O3 could be 91.21% in the single mineral flotation test, the grade of TFe could be 70.67%, the recovery rate of TFe could be 76.11%,the grade of Al2O3 could be 1.93% and the removal rate of aluminum could be 74.72% in the artificial mixed minerals flotation test. The adsorption mechanism were studied by Zeta potential measurements and Fourier transform infrared spectrum. The experimental results showed that there were electrostatic adsorption, hydrogen bond adsorption and chemisorption between collector DTL-1 and aluminum mineral sample.This showed that DTL-1 was a new type of room temperature anionic collector which could be used in the reverse flotation dealumination of suspension roasting magnetic separation iron concentrate.
    Study on the Process Mineralogy of a High Phosphorus Oolitic Iron Ore in Abroad
    HUANG Wusheng, YAN Li, WU Shichao, SUN Tichang
    2020, 49(09):  137-141. 
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    In order to find out the properties of a certain foreign high-phosphorus oolitic iron ore, chemical analysis, X-ray diffraction and scanning electron microscopy were used to study its chemical composition, mineral composition, embedding characteristics and the occurrence state of phosphorus. The results showed that the main iron-bearing minerals in the ore are hematite and magnetite, and a small amount of siderite and goethite. The main gangue minerals are chlorite and calcite. The ores contains phosphorus of 48.61% in apatite and 47.22% in the iron minerals. The iron minerals are mainly distributed in the oolitic grains and closely symbiotic with gangue minerals, making it difficult to separate. Most of the apatite is in the oolitic particles and surrounded by the iron minerals. It has a fine grain size and closely related to the iron minerals. The phosphorus exsited in the iron mineral is evenly distributed and cannot be separated by physical methods. A small amount of phosphorus appears in the form of cellophane and surrounded by iron minerals. In view of the complex mineralogy of the ore, especially the complex form of phosphorus, it is recommended to use the direct reduction and magnetic separation process to treat the iron ore.
    The Influence of Crushing Modes on Grinding Speed and Ball Mill Work Index of the Magnetite Iron Ore
    LI Mingyu, CHEN Wanqing, CHENG Yicun, GUO Tianyu
    2020, 49(09):  142-146. 
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    In order to verify the effect of crushing modes on grinding speed and Bond ball grinding work index, the grinding dynamics test and Bond ball grinding work index test were respectively carried out by using the jaw crusher product, cone crusher product and high pressure roller grinding product of a magnetite concentrator. The results showed that:①the grinding effect of high pressure roller mill is the best, followed by the cone crusher product and the jaw crusher. The grinding speed of the same crushing product decreases with the increase of grinding time. For different crushing products, with the increase of grinding time, particle properties and grinding speed are gradually uniform and close to each other. And the influence of crushing modes on grinding speed is gradually unconspicuous. ②The test of Bond ball grinding work index showed that when the particle size of the grinding product is larger than 0.10 mm, the crushing modes has a significant impact on the energy consumption of the grinding product, and the high pressure roller grinding product is the most energy-saving. When the particle size of the grinding product is less than 0.10 mm, the impact of crushing modes on the energy consumption of the grinding product is reduced. The uasage of high pressure roller mill in crushing process is beneficial to increase the processing capacity of mill and reduce the grinding energy consumption.
    Analysis of the Metallogenic Structure and Prospecting prediction of the Zhazixi Tungsten-antimony Deposit in Anhua County, Hunan Province
    SU Te, QIAN Jianping, ZHOU Weijiao, YU Juyang, ZHANG Guo, GUAN Xiandong, WU Zhengpeng
    2020, 49(09):  147-158. 
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    The Zhazixi tungsten-antimony deposit in Hunan Province is a large antimony deposit which has associated tungsten mine in Western Hunan.The study on its metallogenic structure is still less,which restricts the further prospecting.The regularity of tectonic ore-controlling and the sequence of tectonic evolution of this area have been summarized through regional ore-controlling structure analysis, field structure and ore body geological survey, compilation and mapping of exploration data over the years, occurrence statistics of geological bodies and composition analysis of ore bodies. The results show that ore deposits distribution is main controlled by the positive structure.The type of ore-controlling structure in mining area is "cross" type. Antimony orebody has superiority trend in NWW and NNW trending,tungsten orebody has superiority trend in NEE trending. Antimony orebody has the lateral trending in SE, and the tungsten orebody is in NE. Subsidiary fractures of F3 in the hanging wall is the host structure for antimony orebody. Antimony and tungsten formed in different structure-mineralizing stages and formation of tungsten is earlier. Mineralization center is in the south of the mining area.The deformation-metallogenic sequence in mining area can be summed up as follows: NE trending anticlinorium of the regional tectonics uplifted in Caledonian; NEE trending coaxial superimposed fold in the cover and basement formed in the first stage of Indo-Chinese epoch; NE trending tungsten orebody formed in the second stage of Indo-Chinese epoch; NNW-NWW trending antimony orebody formed in the third stage of Indo-Chinese epoch; NEE trending ore-breaking structure formed in Himalayan Epoch. Based on the study of geological characteristics, structural ore-controlling regularity and vertical mineralization zoning regularity of the deposit,it is considered that the deep part of the mining area has good prospecting prospects and two prospecting target areas are obtained:No.1 prospecting target area is located in the SE of No.9 antimony orebody, between No.2 and No.6 exploration lines and the vertical elevation is from -750 m to -900 m; No.2 prospecting target area is located in the NE of No.13 tungsten orebody,between W10 to W12 exploration lines and the vertical elevation is from -270 m to -370 m.
    Geological Characteristics and Regional Prospecting Potential of Tongling Baoshantao Ag-Pb-Zn Deposit
    HU Yanqiang, DING Ruiying, LIN Xin
    2020, 49(09):  159-166. 
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    Baoshantao Ag-Pb-Zn Deposit in Tongling is located in the southeastern wing of Shujiadian anticline in Guichi-Fanchang fault fold bundle and the northeast side of Xinwuli rock mass.It is a medium-sized Ag-Pb-Zn polymetallic deposit newly discovered in recent years.Based on the regional and mining exploration results,the metallogenic geological background and geological characteristics of the deposit,ore body characteristics and ore characteristics are summarized,and the ore-controlling factors and genesis of the deposit are analyzed.The results show that: ① orebodies mainly occur in Qixia Formation (P1q),Gufeng Formation (P1g),Longtan Formation (P2l) and Dalong Formation (P2d),mainly controlled by interlayer sliding structures,and ore bodies are mostly layered and lenticular in shape.The controlled length of ore body along strike reaches 2 200 m,ore body strike is 50°~60°,dip direction is southeast with 60°~85° dip angle,and the maximum depth along the dip is 591 m.The orebody is characterized by expansion,shrinkage and pinch-out reappearance. ② Metal minerals in ores are mainly composed of pyrite,galena,sphalerite and a small amount of chalcopyrite, tetrahedrite, arsenopyrite and trace silver-gold ore,natural silver,white iron ore and hessite.Gangue minerals are mainly composed of a small amount of quartz and calcite.The ore structure is mainly veinlet structure and disseminated structure. ③ The genesis of the deposit belongs to a medium-low temperature hydrothermal filling type Ag-Pb-Zn deposit.On the basis of the above analysis,the regional prospecting potential is discussed,and it is concluded that there is a good potential of Pb-Zn mineralization in Tongling area.
    Prospecting Prediction of Chifeng-Hulunbeier Metallogenic Belt Based on Weight of Evidence Model
    TIAN Jiuling
    2020, 49(09):  167-172. 
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    The Chifeng-Hulunbeier metallogenic belt is the part of Huanggangliang-Ganzhuermiao metallogenic belt in the south of Greater Xing'an Mountains.The geological structure of this area is complex,and crust and magmatic rock activities are intense,which has the potential to form polymetallic minerals in the South of Greater Khingan Mountains.In order to seek prospecting breakthroughs in the study area,and solve the problems of incomplete metallogenic prediction theory and model prediction of Chifeng-Hulunbuir metallogenic belt,a metallogenic prediction model of Chifeng-Hulunbuir metallogenic belt based on geographic information system technology and data weight theory is established.Firstly,the construction process of the prediction model is discussed.The spatial analysis software ArcGIS of the geographic information system is used to conduct spatial analysis on the obtained stratigraphic information,structural information and magmatic rock information in the study area,so as to construct a spatial database.Then,the weight of evidence theory is applied to the prediction model,the metallogenic prediction model of Chifeng-Hulunbuir metallogenic belt is established.Finally,based on the established model,metallogenic prediction work is done.According to the metallogenic potential,the study area is divided into three types target areas based on the evidence factors of the study area acquired by substituting the data from the spatial database into the prediction model.By verification,the metallogenic potential of the target areas are good,which indicated that the metallogenic prediction results is reliable.The established metallogenic prediction model has certain reference significance for conducting exploration and prospecting works in the Chifeng-Hulunbeier metallogenic belt in the future.
    Monitoring and Predicting the Subsidence of Mining Area Based on D-InSAR Technology and Improved GM(1,1) Models
    SHI Xiaoyu, WEI Xiangping, YANG Keming, WANG Jian, YAO Shuyi
    2020, 49(09):  173-178. 
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    Aiming at the problem of surface subsidence caused by large-scale mining of underground resources in mining area, an improved grey model describing the relationship between subsidence and time was proposed by taking Yuan'er Coal Mine of Huaibei Mining Group as the test area and combining differential synthetic aperture radar interferometry (D-InSAR) and grey model (GM (1,1)),which realizes the integration of monitoring and prediction of surface subsidence.The detail steps can be described as follows: firstly, in view of Sentinel-1A satellite and D-InSAR technology, the settlement deformation maps of the study area in different periods from November 16, 2017 to January 27, 2018 were obtained to analyze the process of dynamic subsidence. Then, according to the settlement value of different time series, the semi-parametric GM(1,1) model estimated by compensated least squares method(BGM(1,1)) and compensated least squares method with relative weight(WGM(1,1)) were established to fit and predict the settlement value.The test results show that D-InSAR technology has obvious advantages in dynamic monitoring of land subsidence in mining area, and its monitoring accuracy reaches millimeter level; in addition, BGM (1,1) and WGM (1,1) prediction models make up for the shortcomings of classical GM (1,1) model, the relative error of four test points predicted by WGM (1,1) is 1.99%~26.64%. The study can provide a theoretical basis for dynamic monitoring and subsequent treatment of ground subsidence in mining areas, furthermore, it has certain significance early warning function and reference.
    3D Modeling of Underground Tunnel Based on Close Range Photogrammetry Technique
    2020, 49(09):  179-183. 
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    A unified understanding and digital representation of the entire real mine and its related phenomena is an important part of digital mine construction,and 3D modeling and visualization of underground mine roadway is the core contents of digital representation.Aiming at the inefficiency of traditional 3D roadway modeling method of low efficiency and high cost,a 3D modeling method of underground roadway based on close-range photogrammetry technique was proposed. The modeling method mainly adopts the principle of close-up photography to measure the forward intersection of stereo pairs,uses the camera to obtain a set of images of the same target at different spatial positions,and calculates the geometric constraint relationship between the images to obtain the 3D coordinate information of the target surface to construct the 3D model of shooting target.Firstly,low-cost smartphone camera was adopted to collect multi-perspective close-up photos of the roadway;then,digital image modeling Context Capture software was used to perform aerial triangulation calculations on the image data and generate underground roadway points cloud data;finally,feature extraction and image matching were conducted on the obtained photos to complete the construction of 3D modling of underground roadway.Taking the underground air-raid shelter roadway of Henan Polytechnic University as the study example,566 photos were taken,the overlap between the photos is about 80%. The data processing results show that the 3D model structure of the object is complete and the texture is clear,which indicated that the method of 3D modeling method based on close-range photogrammetry is feasible.
    Study on Overall Architecture Design and Key Technology of Open-pit Mine Navigation System
    ZHONG Xiaoyu, ZHAO Qingfeng, SUN Xiaoyu, SUN Jian, XIAO Kaitai
    2020, 49(09):  184-190. 
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    In view of the problems of complex space,large equipment blind area and low visibility in open-pit mine road network,the overall system architecture is designed,which is composed of data access layer,business logic layer,interface layer and application layer.The data access layer determines the data structure and class structure of road network composed of points,road sections,regions and paths.In the business logic layer running in the server,it designs and develops general algorithms such as navigation path planning,road network matching, running distance and time prediction,intersection turning prompt,etc.The application layer calls the general algorithm through the interface to realize the terminal application function.Based on the overall structure of the system,the road network structure is defined,and the data structure of road network class is designed by using object-oriented technology.The key algorithm of business logic layer is studied,and then the interface of the algorithm is encapsulated.Finally,based on the road network data of Yimin Open-pit Mine of Huaneng Group,the system is divided into independent navigation and Baidu map navigation.The study results show that: the design of the overall architecture of the system makes the system has strong universality,practicability and expansibility;the system realizes the functions of navigation path planning,positioning point correction and road link matching, prediction of travel distance and travel time to destination,intersection direction prompt and other functions,solves the problems of the driver getting lost and taking the wrong road;the system can run independently.It can also effectively connect with Baidu map API,and can adapt to a variety of terminals.
    Research Status and Optimization Improvement of Magnetite Cleaning by Column Separator
    ZHANG Mingrui, GUO Xiaofei, REN Weijie, CUI Shaowen, DAI Shujuan
    2020, 49(09):  191-196. 
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    The increasing demand for high quality iron concentrate in iron and steel industry has promoted the rapid development of magnetite column cleaning equipment. The research status of magnetite column cleaning equipment is reviewed, and the problems of the traditional magnetite column, such as narrow range of particle size for feeding, poor recovery effect, large water consumption and low treatment capacity are analyzed in this paper. The upgrade research of composite magnetic field, structural optimization, permanent magnetization and control system has improved the TFe grade of magnetite concentrate and recovery rate of fine high-magnetic minerals, with the increase of the processing capacity of the equipment and decrease of the water consumption, which simplified the production process and improved the production efficiency. It is pointed out that the main development direction of magnetite column cleaning equipment in the future is the fine sorting based on different components of magnetite, and the research of efficient and intelligent sorting equipment and technology.
    Experimental Study on Influence Factors of Separation Grade of a New Type Dry Magnetic Separator
    CAO Liying, LIU Wenkai, WANG Jianxin, ZHANG Yi, REN Mingming, KONG Linghui
    2020, 49(09):  197-201. 
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    Guyang area of Baotou City in Inner Mongolia is dry and less rain, in which hematite is widely distributed and difficult to be separated. The TFe grade of the raw ore is only 13.51%, and the separation indexes with traditional magnetic separation equipment are poor, resulting in the lack of competitiveness. Thus, the influencing factors of the separation grade of the new three-stage dry-type permanent magnet drum-type magnetic separator were studied. Under the condition of wind speed of 5 m/s, the influences of the rotation speed and the particle size of selected ore on the test indexes of dry-type permanent magnet magnetic separator under different distribution modes of magnetic rollers were investigated. The results show that the optimum speed of the drum is 120 r/min in high, medium and low magnetic field distribution, and the optimum speed of the drum is 140 r/min in low, medium and high magnetic field distribution. When the magnetic field arrangement of the drum is high, medium and low, the sorting effect is better than that of low, medium and high magnetic field arrangement, performing the better concentrate yield and TFe grade. For this new type of permanent magnet dry magnetic separator, the better working parameters are the drum magnetic field strength from top to bottom of 0.23 T, 0.17 T and 0.11 T, rotation speed of 120 r /min, the feeding particle size of -2 mm,brought out the concentrate of the TFe grade of 34.62% and the tailings of the TFe grade of 10.95%, respectively. The experimental results provide technical parameters for the further research on improving the performance of the three-stage dry-type permanent magnet drum-type magnetic separator and a research basis for the development and utilization of low-grade hematite resources.
    Experimental of Copper and Iron Recovery from Copper Smelting Slag by Direct Reduction Roasting and Magnetic Separation
    QIU Tingsheng, ZHOU Liping, LI Guodong
    2020, 49(09):  202-207. 
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    Copper smelting slag contains valuable metals such as copper and iron. Copper metal could be recovered directly by flotation, but iron minerals are difficult to separate directly by magnetic separation due to complex minerals composition. In this paper, copper smelting slag containing 38.76% iron and 2.26% copper was taken as the research object. Based on the analysis of ore properties, copper and iron were recovered from the copper slag by direct reduction roasting and magnetic separation process when bituminous coal was used as the reducing agent. The results showed that the copper smelting slag, bituminous coal and CaO were mixed at a mass ratio of 100∶25∶20, and then roasted in 1 200 ℃ for 80 minutes. The roasted samples were ground to -0.045 mm accounted for 80%, and then subjected to magnetic separation at magnetic field intensity of 111 kA/m. Finally, concentrates with 91.54% iron-containing and 6.06% copper-containing was obtained. The corresponding recovery rates were 90.54% of copper and 89.04% of iron, respectively, which provides basis for the production and utilization of the copper smelting slag.
    Macrostructural and Microstructural Properties Analysis for The Polypropylene Fiber-reinforced Iron Tailings Sand
    JIN Jiaxu, YANG Hui, ZHANG Chenxi, WU Jinyu, SHI Mingyue
    2020, 49(09):  208-213. 
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    Experimental study was carried out to investigate the influence of polypropylene fibre on the shear behavior, compressive behavior and microstructural properties of polypropylene fiber-reinforced iron tailings. The shear behavior was determined by the shear resistance, and the compressive behavior was determined by the unconfined compressive strength. The structural changes of the fiber-reinforced tailing sand were evaluated by macrostructural failure analysis and microstructural test with SEM analysis. The tests was designed to research the influenence of fiber contents and moisture contents on the tailings specimens. The results showed that the fiber is an important factor to improve the shear strength and unconfined compressive strength, and the reinforcement effect mainly depends on the friction and bonding between the fiber interface and the sand interface. The best fiber contents is 0.3%, and the best moisture content is 12% in the shear tests and unconfined test. In addition, the macroscopic structural failure analysis and SEM microstructural tests showed that the action of polypropylene fiber is mainly to bridge the crack and counteract the external force through the friction force at the fiber interface and the sand interface to achieve the purpose of increasing the strength.
    Study on Preparation and Properties of Composite Insulation Materials with Kaolin/Manganese Tailings Slag and Straw
    LIANG Qiuqun, LIU Zheng, LIANG Chuxin, YANG Ruishan, ZHANG Shufen
    2020, 49(09):  214-220. 
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    Manganese tailings slag is rich in elements such as silicon and aluminum, which could be used as a raw material for preparing geopolymers. In order to investigate the possibility of combining manganese tailings slag with straw stalk as an insulation material, manganese tailings slag was used to replace some metakaolin for preparing geopolymer. After combining with straw stalk, kaolin/manganese tailings slag and straw composite insulation material was prepared. The effect of diffirent curing time under natural conditions and adding different proportions of straw on the mechanical properties and thermal conductivity of composite thermal insulation materials were studied. The results showed that when the addition of straw stalk powder was 3%, the compressive strength of the composite insulation material reaches 71.8 MPa after 28 days of curing with the flexural strength of 9.8 MPa, the thermal conductivity of 0.065 W/(m·K) and the density of 265 kg/m3. The main indicators meet the requirements of national standard Constrcution Industry Standard (JG 158-2004). The high temperature resistance tests of the composite insulation material was conducted. The results showed that the polymer has a certain protective effect on straw when the calcination temperature was lower than 200~500 ℃. The research results of the thesis have a certain promotion effect on improving the comprehensive utilization of manganese tailings and straw.