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    15 November 2022, Volume 51 Issue 11
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    Study Status and Development Direction of Loss and Dilution in Non-pillar Sublevel Caving Method in China
    HE Rongxing, CHEN Liyuan, REN Fengyu
    2022, 51(11):  1-9. 
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    It is safe in production,have high mining intensity,high efficiency and a simple recovery process in non-pillar sublevel caving,which occupies a large proportion in underground mining.However,the problem of large loss and dilution limit the application of this method in precious metal mines,which is a research hotspot of many scholars.This study summarizes the 60 year development process of non-pillar sublevel caving method,and systematically summarizes the study status of control loss and dilution from the four aspects,including ore drawing theory,stope structure parameters,ore drawing method and roadway layout form,and overburden layer.Only the flowing characteristics of granular is considered in the ore drawing theory,and the factors such as blasting block size,ore drawing port size,side hole angle,and shovel depth are not included in the ore drawing theory.The stope structure parameters determined according to the shape of ore drawing of drawing theory,which cause stope structure parameters are not optimal parameters.In actual production,the low-dilution ore drawing method is not strictly followed,and the layout of the mining roadway cannot fully adapt to the changes in the shovel loading of the ore body,and the formation method of overburden layer is not conducive to loss dilution control in some mines.In view of these problems,the study direction and measures to further control the non-pillar caving method are put forward,which has theoretical guiding significance for the production mine to further control the loss and dilution indexes.
    Main Study Progress and Prospect of Geo-electrochemistry Technology in China
    LIU Panfeng, LUO Xianrong, WEN Meilan, ZHENG Chaojie, OUYANG Fei, SHAN Jiangtao, GAO Wen
    2022, 51(11):  10-22. 
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    Based on a review of the development history of geoelectrochemical technology in China,the development of geoelectrochemical technology is summarized,and the research progress of geoelectrochemical technology made since 2011 is emphatically analyzed as follows:① The halo-forming mechanism of "segmented theory" is put forward,which is divided into the generation process for ore-forming-related metal particles (mainly electrochemical dissolution),the migration process of metal particle (containing aeration and saturated zone),and the unloading process of metal particle (geochemical barrier).② The manufacturing process of extraction electrode is simplified which maximizing the material performance and the preprocessing methods with adsorption material (polyurethane foam) is improved.Meanwhile,the controllability of the instrumentation power supply is optimized which resulting in the reality of relevant data (instantaneous voltage and current) collection and recordation during geo-electrochemical extraction.③ The whole progress of geo-electrochemical technology,from sample collection,processing,testing and analysis is standardized and the Technical Specification of Geo-electrochemical Measurement (Version for Comment) is drafted.④ In terms of application,favoring prospecting results and predictive progress have been respectively achieved not only in different coverage and typical mining areas but also in soil heavy metal remediation.Based on the above discussion results,the future development of geo-electrochemical technology is envisioned from three aspects:① From the macroscopically study perspective of elemental content changes and occurrence forms on the shallow surface (both on bedrock and weathering layer-soil):with the microscopic point of view,to observe the elemental migration forms and factors affecting their distribution with the help of high-resolution electron microscope to further improve the method and mechanism.② based on the concept of portability,automation and commercialization,further attention will be focused on optimizing the time control and data storage function of the power supply,and improving the visualization and application degree of the environmental protection materials for the extraction device,and applying more mature statistical methods to extract weak abnormal information from geoelectric data to meet the demand of the exploration market as far as possible.③ To enhance the universality of technology application in other fields,it is necessary to accelerate the compilation of technical regulations,which can further deepen the application of geo-electrochemistry technology in the field of soil heavy metal remediation.
    Study Progress and Outlook of Pulsed-jet Cleaning Technology for Filter Cartridge of Dust Collector
    LI Jianlong, CHEN Yuanzheng, LIN Zijie, WU Quanquan, WU Daishe
    2022, 51(11):  23-35. 
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    Filter cartridge cleaning is the key process in the operation of the dust collector.Pulsed-jet reverse airflow cleaning technology,as the most widely used cleaning technology,has the advantages of simple operated,airflow uninterrupted and so on.In recent years,the proportion of pulse-jet cleaning filter cartridge dust collectors in industry is gradually increased for its technology advantages and related research is developed rapidly.Researchers have extensively explored the pulse-jet cleaning technology of filter cartridges using theoretical analysis,experimental research and numerical simulation,and have made a lot of useful progress.This paper describes the basic principle of dust filter cartridge pulse-jet cleaning technology,the adhesion of dust cake,and the evaluation method of dust removal effect.Main factors affecting dust cleaning performance of the filter cartridge are analyzed,main problems are outlined,the latest progress of improvement measures to improve dust removal uniformity are summarized,and the development direction of dust filter cartridge pulse-jet cleaning technology are pointed out.The research shows that the theory of pulse jet pressure is generally adopted to understand the mechanism and the static pressure on the filter wall is taken as the jetting index.The evaluation of cleaning effect is mainly based on the change of filtration resistance and fallen dust mass.The jet deviation,patchy cleaning and dust re-deposition are common problems faced by the filter cartridge,of which the patchy cleaning is the focus of current research.The main measures to improve the dust cleaning performance of the filter cartridge are nozzle designing,venturi tube addition,filter cartridge structure optimization,jet strategy improvement and so on.Among them,opposing pulse jet cleaning technology breaks through the limitation of single-point source type and has great potential to overcome the patchy cleaning problem.Key points for future research including theory analysis of pulse jet filter cylinder cleaning,structure design of pulse jet cleaning and parameter optimization,regular analysis of dust cake releasing and migration,and establishment of specification for pulse jet system and parameter.The research results can provide reference for the development and engineering application of pulse-jet cleaning technology for dust filter cartridge.
    Study on the Influence of Differential Time and Stemming Length on the Adjacent Backfill
    JIANG Linjing, JIN Aibing, YAO Baoshun, CHEN Shuaijun
    2022, 51(11):  36-43. 
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    In the two-step stope with subsequent filling,medium-deep hole blasting has an impact on the filling experience,so it is of great significance to study the blasting response of backfill to ensure mining safety.Through the field blasting vibration velocity test,the attenuation equation was obtained by fitting the monitoring data.At the same time,ANSYS/LS-DYNA finite element software was used to conduct numerical simulation analysis on different differential time and different stemming length schemes.The results showed that:① the calculated results of attenuation equation were basically consistent with the numerical simulation results,and ANSYS/LS-DYNA software used to simulate the influence of blasting on the stability of backfill could obtain ideal results.② With the increase of the differential time from 19 ms to 25 ms,the maximum effective stress and peak velocity at the interface between the stope and backfill firstly decrease and then increase.When the differential time is 23 ms,the maximum value reaches the minimum value,which meets the specification requirements and has the least influence on the backfill.③ Based on the original mine blasting parameter scheme,four kinds of stemming length schemes were designed.By analyzing the maximum effective stress and peak velocity of the interface between the mine room and the backfill,when the stemming length ls1~ls5 was 2,4,2,5,4 m respectively,the blasting had the least influence on the backfill and had the best vibration reduction effect.The study results can be used as a reference for the design of blast hole parameters in similar mines.
    Optimization and Stability Analysis of Stope Structure Parameters of Large-diameter Deep Hole Open Stoping with Subsequent Filling
    CHEN Lin, HUANG Mingqing, TANG Shaohui, ZHANG Ming, LIU Qingling
    2022, 51(11):  44-51. 
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    Large-diameter deep hole open stoping with subsequent filling is a safe and efficient mining approach to utilize inclined and extremely thick orebody.Reasonable stope structure parameters is key premise to stope stability.Aiming at massive underground mining with a capacity of 10 Mt/a at Jama Copper Mine,stable zone and hydraulic radius are calculated using Mathews stability graph,and stope stability is numerically simulated using FLAC3D software to optimize the stope structural parameters with high section and large stope.Numerical simulation is operated with respect to four parameter combinations in the mining pattern of "mining one at three stope intervals".The relationship of exposed areas of stope roof,sidewall and hydraulic radius is revealed by Mathews stability graph.Results shows that stope roof span is favorable at 15 m,stope length is limited to 46 m when stope height is 100 m.When the span of secondary stope increases from 15 m to 19.5 m,the roof displacement and plastic zone volume of stope are accordingly increased.Sidewalls of trench at bottom structure have a relatively low safety factor and therefore tend to suffer a range of shear failure.Since the numerical simulation results are consistent with the evaluation of Mathews stability graph,the stope structure parameters are optimized as 45 m in stope length,15 m in the preliminary stope width,18 m in the secondary stope width,and 100 m in stope height.The research results provide theoretical support for the safety mining of the high and middle sections of the inclined extremely thick orebody.
    Study on the Optimization of the Stope Structure Parameters of Gently Inclined Extremely Thin Orebody
    XU Yongwen, WU Bingshu, LI Guanbing, LI Zhengcan, LIU Yunqiu
    2022, 51(11):  52-57. 
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    In order to further optimize the stability of the stope structure of the gently inclined extremely thin ore body in Shandong Gold Mining (Xinhui) Gold Mine,the stope structure of the double side throwing and subsequent filling mining method was optimized.By using the finite element analysis software FLAC3D and combining the actual situation of the ore body,five stope width structures at 1.0,1.5,2.0,2.5,3.0 m were designed.Calculating and analyzing the maximum principal stress and maximum displacement after excavation under different conditions so as to obtain the optimal stope structure parameters.The study results shows that with the increase of the mining width,the stress and damage range generated after the first step of mining increase significantly,and the subsidence displacement of the roof gradually increases.In the plan with the mining amplitude of 2.5 m and 3.0 m,after the stress redistribution of the fourth and fifth step of mining,the stress of surrounding rock presents an upward trend,with potential rock burst risk.In different mining processes,the stress in the surrounding rock is released,which makes the stress distribution reach a new equilibrium state.At the same time,through data comparison and analysis,the stope structure parameter of 1.5 m is the best scheme for the gently inclined extremely thin orebody by adopting the double side throwing and subsequent filling mining method,which can ensure the safe and efficient production in the mine.
    Parameter Determination of Empirical Model of Artificial Frozen Clay and Verification of Creep Law
    YAO Zhaoming, LI Nan, GUO Mengyuan
    2022, 51(11):  58-63. 
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    The artificial freezing method is not only commonly used in the excavation of subway side passages in soft soil,sand layers,and foundation pit support,but also in the construction of mine shafts with rich water,deep rock and soil.Mastering the physical,mechanical properties and creep laws of artificial frozen soil is essential for safe and fast construction.Perform uniaxial compressive strength tests at -5,-8,-10 and -15 ℃ and creep characteristics tests at different stress levels on the deep formation clay of a mine shaft constituted by the freezing method.The experimental results show that the compressive strength is linearly related to the freezing temperature;At the same test temperature,as the stress level increases,the axial deformation shows an upward trend;At the same stress level,as the test environment temperature decreases,the axial deformation shows a downward trend.Introduce an empirical creep model that takes into account the temperature effect,based on the linear relationship between the strain and time at each negative temperature and different stress levels,the linear expression is brought into the corresponding formula to solve the simultaneous equations to determine the model parameters.Comparing the calculated values of the model with the experimental data shows that the model can better simulate the initial deformation stage and the stable deformation stage of artificially frozen clay.The established model has the advantages of fewer parameters,easy determination,and clear physical meaning of the parameters,which provides an effective calculation method for the design of frozen walls.
    Stability Analysis and Control of Surrounding Rock of 1 500 m Service Shaft Bedrock Section in Sishanling Iron Mine
    LI Yangyang, ZHAO Xingdong, DAI Bibo, LI Huaibin
    2022, 51(11):  64-70. 
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    In view of the limitations of the traditional theory and method of stability control of shallow shaft surrounding rock in application of deep shaft construction,based on the 1 500 m service shaft project of Sishanling Iron Mine,the stability analysis and control method of surrounding rock of deep shaft are explored.The self-support height without support and the stand-up time are used to analyze the stability of surrounding rock of service shaft in Sishanling Iron Mine,and the minimum self-support height is 22 m,the corresponding stand-up time is 125 days,the above of which can ensure the stability of surrounding rock during shaft sinking with 4 m sinking advance and 1~2 days cycle.However,it is still required to install support to ensure the long-term stability of surrounding rock during shaft excavation to service.Simultaneously,based on NATM and NMT,the theory of stability control of shaft surrounding rock which emphasizes making full use of the self-support capability of the surrounding rock is put forward,the stability control method of surrounding rock of deep shaft with the primary support (rock bolts,steel wire mesh and shotcrete) and the permanent support (concrete lining) is established.And accordingly,combined with the support design of the bedrock section of service shaft in the mine,the support design process of deep shaft is analyzed,and the support scheme of the bedrock section of service shaft is proposed.The safety of support scheme for the service shaft is verified by using Phase 2 software,which demonstrates that the stability control theory,method and support design method of shaft surrounding rock proposed in this paper is feasible for the construction of deep shaft.
    Experimental Study on Fracture Behavior of Red Sandstone Subjected to Breakdown Effect of High Voltage Electric Pulse
    PENG Jianyu, WANG Haonan, WU Shuo, ZHANG Fengpeng
    2022, 51(11):  71-76. 
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    Rock breaking by high voltage pulse has the characteristics of environmental protection and energy controllable,which is an emergent rock fragmentation technology with broad application prospect.The fracture mechanism of red sandstone specimens under high voltage pulse was analyzed by electric breakdown experiment,and the fracture modes and fracture degrees of red sandstone specimen under different size and discharge voltages were studied.The results show that high temperature and shock wave are the internal mechanisms leading to the fracture of the specimen.Under the action of high voltage pulse,a breakdown zone near the electrodes is formed in the sandstone specimen due to the rapid expansion of plasma channel,and the damage is the most serious.Radial cracks appear on the outside of the breakdown zone under the action of shock wave.When the shock wave is strong enough,it can induce spalling cracks near the boundary.The formation of breakdown zone,radial cracks and spalling cracks is closely related to the specimen size and discharge voltage.The crack density and fractal dimension are selected to quantitatively analyze the fracture degree of the specimen after high voltage pulse.With the increase of specimen size,the failure mode of specimen changes from fragmentations to perforation failure,the fracture density,the complexity and the fractal dimension of the specimen decrease continuously.With the increase of discharge voltage,the failure mode of specimen changes from perforation failure to fragmentations,the fracture density,the complexity of crack and the fractal dimension of the specimen are increased.
    Study on Vibration Effect of Deep Hole Blasting in Open-pit Mine Based on EEMD-HHT
    CHEN Junkai, WEI Zheng, HAO Xiangjun, ZHANG Xiaojun, GAO Wenxue
    2022, 51(11):  77-83. 
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    Engineering blasting plays an important role in the process of national economic construction in China,but blasting vibration,as the first harmful effect of blasting,is a problem that can not be ignored.In order to study the "elevation effect","whiplash effect" and the energy distribution characteristics of blasting vibration wave in deep-hole controlled blasting in open-pit mine,a method for analyzing blasting vibration effect based on the precise delay of electronic detonator and EEMD-HHT signal analysis technology is proposed in this paper,relying on the deep-hole controlled blasting project in Xingguang Open-pit Mine and through field blasting test.The test and analysis results show that the blasting vibration velocity shows attenuation trend,and there is elevation amplification effect with obvious directivity.The amplification coefficient is vertical (Z direction)> radial (X direction) > tangential (Y direction).At the same elevation,the phenomenon of "whiplash effect" is obvious,which shows that the peak vibration velocity of rock mass near the outer edge of the step is greater than that at the foot of the inner edge slope.The dominant frequency band of blasting vibration signal energy is distributed in 10~50 Hz,and mainly in low frequency band.The energy of blasting vibration wave is vertical (Z direction)> tangential (Y direction)> radial (X direction).Through the study on the vibration effect of deep-hole controlled blasting in open-pit mine,the influence of blasting vibration on rock mass disturbance is reduced,and the slope rock mass is stable,the outline is clear and the broken rock mass is uniform after blasting,which provides reference for similar engineering.
    Study on the Mechanical Properties of Limestone under Three-dimensional Combined Dynamic and Static Loading
    YU Yongqiang, YU Liwei, FAN Lidan, XU Feng, ZHOU Guijie
    2022, 51(11):  84-91. 
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    Deep rock mass is in the complex environment of " three high and one disturbance ".In order to study the influence of impact load on roadway surrounding rock during roadway excavation,limestone is taken as the research object,and the mechanical properties of limestone under three-dimensional dynamic and static combined loading are studied through the improved SHPB dynamic and static combined loading test device of Henan Polytechnic University.Typical axial pressure gradients (8,15,16 and 17 MPa) and circumferential pressure gradients (1,2,3,5 and 7 MPa) were selected,and three-dimensional combined loading tests with impact pressure gradients (0.5,0.6,0.8 and 1.0 MPa) were carried out.The results showed that the peak strain of limestone increased under the three-dimensional combined dynamic and static loading,and the absorbed energy also increased,with the peak value reaching 87.7 W/J,which was about 60% of the incident energy,and the fragmentation of the specimen was the most obvious,showing the trend of "rock burst" in the laboratory.The reflected energy,transmitted energy and absorbed energy increased linearly with the increase of incident energy,increased linearly with the increase of incident energy.The reflected energy,transmitted energy,absorbed energy,incident energy and absorbed energy per unit volume increased as a quadratic function with the increase of the average strain rate.In addition,when the axial pressure and confining pressure remain unchanged,the stress-strain curve is divided into four stages with the increase of the impact pressure.When the strain reaches the peak value,there is a rebound phenomenon,that is,the strain begins to decrease after the deformation of the sample reaches the peak strain.The variation law of the stress-strain curves when the confining pressure and the confining pressure remain unchanged is basically consistent with that of the impact pressure when the axial pressure and the confining pressure remain unchanged.The failure modes of rock under different confining pressures are mainly tensile failure and compressive shear failure.
    Analysis on the Main Influencing Factors for Titanium and Iron Separation Using Direct Reduction and Magnetic Separation Treating Titanomagnetite
    GAO Enxia, FANG Qingsong, GENG Chao, JIANG Man, SUN Tichang
    2022, 51(11):  92-100. 
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    The progress of direct reduction and magnetic separation of titanomagnetite was summarized from four aspects:reduction process of titanomagnetite,effects of roasting method,reduction condition and grinding condition on the separation of Ti and Fe.The reduction sequence of titanomagnetite in the direct reduction is Fe2.75Ti0.75O4→Fe2TiO5→Fe2TiO4→FeTiO3→FeTi2O5→Ti2O3.From the present stage,the commonly used roasting methods mainly include blending and embedding method.Among them,blending has the characteristics of low reduction temperature,short reduction time,low reducing agent dosage,low cost and better separation effect of Ti and Fe.However,TiO2 grade in titanium-rich products obtained by embedding method is high,which is conducive to the recovery and utilization of titanium resources in titanomagnetite.In the direct reduction process of titanomagnetite,reduction conditions,such as reducing agent,reduction temperature,reduction time and additives,have effects on the separation of Ti and Fe.The appropriate reduction conditions are conducive to the reduction of titanomagnetite and the aggregation and growth of iron particles,so as to promote the separation of Ti and Fe.Grinding fineness and magnetic field strength also affect the separation effect of Ti and Fe.Grinding fineness should not be too coarse/too fine,and magnetic field strength should not be too large/too small.Through analysis and comparison,it can be seen that in-depth study of reduction process of titanomagnetite and strengthening separation of Ti and Fe are of great significance to the comprehensive utilization of titanium and iron resources in it.Finally,the main direction of the development and progress of the separation Ti and Fe of titanomagnetite by direct reduction and magnetic separation was pointed out.
    Experiment Study on Magnetization Roasting-Low Intensity Magnetic Separation for Ores from Masteel Gushan Iron Mine
    ZHANG Jianting YANG Feng LI Zhiming FANG Shunyao
    2022, 51(11):  101-106. 
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    The TFe grade of Gushan iron ore in Masteel is 37.68%.The main iron-containing mineral is hematite,and gangue composition is mainly composed of SiO2 and Al2O3.The content of harmful element P is high.It is difficult to obtain good technical and economic indexes by using traditional beneficiation technology,while the magnetization roasting for refractory iron ore is an effective pretreatment method.Therefore,an experimental study on magnetization roasting-low intensity magnetic separation was carried out for Gushan iron ore,and the effects of roasting feeding fineness,roasting temperature,reducing gas concentration and roasting time on magnetization roasting effect were explored.The results showed that under the conditions of -0.074 mm accounting for 50%,roasting temperature of 500 ℃,CO gas concentration of 40%,roasting time of 20 min,gas flow rate of 500 mL/min,the roasted products were obtained by grinding-magnetic separation-regrinding-magnetic separation-tertiary grinding-magnetic separation.Iron concentrate with iron grade of 63.98%,iron recovery rate of 83.32% and P content of 0.15% was obtained,and the product index was better than the existing process.The research results can provide a new idea for the efficient utilization of Gushan iron ore in Masteel.
    Discussion on the Flotation Recovery of Sulfur and Cobalt Before Low Intensity Magnetic Separation of Vanadium and Titanium Magnetite Ore in Panxi Area
    ZHAI Yuke, CHANG Ziyong, WANG Xiaoli, LIU Wei, WANG Han, WANG Huajun
    2022, 51(11):  107-114. 
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    Panxi region is the largest production area of vanadium titanomagnetite in China.In addition to the primary elements such as iron,vanadium and titanium,vanadium titanomagnetite is also accompanied by 60 million tons of sulfur resource and 900 000 tons of cobalt resource,which has high industrial utilization value.At present,the processing flowsheet of vanadium titanium magnetite ore in industry is "stage grinding-low intensity magnetic separation of iron-high intensity magnetic separation of titanium from iron tailings-desulfurization of titanium concentrates-flotation of ilmenite" to get products including iron concentrate,titanium concentrate and sulfur (cobalt) concentrate.The recovery of sulfur-cobalt concentrate primarily happens in the titanium concentrates desulfurization stage.Because the cobalt grade is less than 0.3%,the product is sold as sulfur-cobalt concentrate when the market price of cobalt is high,while as sulfur concentrate when the market price of cobalt is low,leading to the significant waste of cobalt resources.In this work,authors attempted to recover sulfur and cobalt by flotation before the low intensity magnetic separation,based on the principle of early recovery and fast recovery.In the laboratory,the vanadium titanomagnetite ore was ground to 45% passing 0.074 mm,and the flotation reagents include copper sulfate of 250 g/t,isoprene xanthate of 150 g/t,3# foaming agent of 30 g/t.A product with yield of 14.33%,sulfur grade of 3.11%,cobalt grade of 0.06%,nickel grade of 0.03%,copper grade of 0.1%,sulfur recovery rate of 68.14%,cobalt recovery rate of 35.12%,nickel recovery rate of 47.23% and copper recovery rate of 43.12% was achieved after one roughing flotation.The integrated ball grinding-flotation machine and shallow tank rapid flotation machine were developed for the pre-flotation recovery of sulfur and cobalt from the raw ore of vanadium titanomagnetite.Experimental results indicated that the shallow tank rapid flotation machine was promising for the early and fast recovery of sulfur and cobalt before the low intensity magnetic separation.
    Study on the Effect Law of Hematite Conversion Rate on Magnetic Separation during Magnetization Roasting
    WANG Shuai, SUN Yongsheng, HAN Yuexin, LI Yanjun, GAO Peng
    2022, 51(11):  115-119. 
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    Magnetization roasting and magnetic separation is one of the main methods for treating refractory iron ores at present.In order to explore the influence law of roasting process parameters on hematite magnetic conversion rate and magnetic separation index,magnetization roasting-magnetic separation test of hematite with natural pure hematite as the research object were systematically carried out,and the growth trend and phase transformation process of magnetite were explored by polarizing microscope and XRD.The test results showed that:aiming at the sample,the suitable roasting temperature of hematite is 550 ℃,the CO concentration is 20%,and the reduction time is 4 min.At this time,the magnetic separation recovery of the sample reaches 99.58%,and the magnetic conversion of hematite is 32.99%.In the roasting process of hematite,newborn magnetite is first formed on the mineral surface and cracks.With the increase of roasting time,newborn magnetite grows internally along the surface of ore particles.When the outer part of the particles is reduced to magnetite and the conversion rate of hematite reaches 32.99%,the whole particles can be recovered in the magnetic separation process,good magnetic separation indexes can be obtained without completely reducing hematite to magnetite.
    Experimental Study on Beneficiability of a Low Grade Lead-zinc Sulfide Ore in Xinjiang #br# #br#
    LI Shaoping, WANG Jinke, ZHANG Weiguang, LI Jie, DONG Fa
    2022, 51(11):  120-125. 
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    A low-grade lead-zinc ore in Xinjiang is of simple mineral composition,complex mineral association relationship and uneven particle size.In order to recover lead and zinc in the ore effectively,the appropriate beneficiation process flow and reagent system were determined through the experiments of lead-zinc flotation conditions with lead-zinc preferential flotation process.The results showed that in the condition of grinding fineness of -0.074 mm accounting for 70%,aiming at the raw ores with lead grade of 1.04% and zinc grade of 1.66%,the lead concentrate with lead grade of 45.16% and zinc grade of 1.21% could be obtained by using two roughing for lead selection and then three cleaning for lead coarse concentrate which has been ground to -0.038 mm accounting for 100%.After activation of lead-selected tailings by CuSO4,zinc was selected by two roughing and three cleaning.Finally,lead concentrate with lead grade of 44.16% and lead recovery rate of 85.04% and zinc concentrate with zinc grade of 43.31% and zinc recovery rate of 92.45% were obtained by closed-circuit test in the whole process,which better realized the separation and recovery of lead and zinc.The research results can provide useful reference for the development and utilization of the same type ore.
    Research Study on Comprehensive Recovery for Associated Tantalum-niobium-lithium from a Rubidium-bearing Granite Ore
    LI Hong, SUN Jinlong, TAN Xiumin, ZHANG Xiufeng, LÜ Zihu, MIAO Qunfeng, LI Zhibin, QI Yunfei
    2022, 51(11):  126-133. 
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    Comprehensive utilization of associated resources is a critical initiative for green mine construction and energy conservation.In order to achieve the resource utilization for a rubidium-bearing granite ore with tantalum,niobium and lithium,a detailed study on comprehensive recovery experimental was carried out.The ore has Ta2O5 grade of 42.15 g/t，Nb2O5 grade of 184.00 g/t,Li2O grade of 0.086%.Tantalum and niobium occurs in niobite,and lithium mainly occurs in zinnwaldite.The beneficiation process of magnetic separation priority recovery of niobite and zinnwaldite-gravity concentration recovery of tantalum and niobium in magnetic concentrate-floating lithium in gravity tailings was determined.The results showed that under the condition of grinding fineness of -0.074 mm accounting for 61.81%,the tantalum-niobium concentrate containing 11 650 g/t Ta2O5、50 400 g/t Nb2O5 was obtained by low intensity magnetic separation iron removal,high intensity magnetic separation and two stage shaker table gravity separation.The recovery rate of tantalum and niobium were 38.46% and 38.11%,respectively,and the concentration factor were more than 270.Using sodium carbonate and sodium silicate as adjusting agents,oxidized paraffin soap and dodecylamine as cation-anion combination flotation collectors,the flotation was carried out on tailings of gravity concentration for selecting zinnwaldite.After one roughing,one cleaning and one scavenging,the zinnwaldite concentrate with Li2O grade of 1.837% and recovery rate of 50.84% was obtained.The recovery and enrichment of associated tantalum-niobium-lithium are realized,which provides a reference for the industrial utilization of this type of ore.
    Study on Process Mineralogy of a Cu-Zn-Fe Polymetallic Ore in Central Tibet
    WANG Hailiang, YAO Denglei, GAO Chunqing
    2022, 51(11):  134-140. 
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    The grade of copper,zinc and iron in a polymetallic mine in central Tibet are 0.48%,7.75% and 33.57%,respectively.In order to develop and utilize the ore rationally,detailed process mineralogy of the ore was studied detailly by means of MLA,SEM-EDS,X-ray energy spectrum analysis and electron probe.The occurrence states of valuable elements,mineral composition and content,the distribution characteristics of target minerals,and the dissociation degree of the main minerals,as well as the factors affecting the comprehensive and efficient recovery of valuable elements were found out.The results showed that copper mainly occurs in chalcopyrite and covellite with a distribution rate of 95.66%.Zinc is produced in the form of marmatite and smithsonite,with distribution rates of 92.11% and 7.89%,respectively.Magnetite is the main occurrence state of iron with a distribution rate of 32.68%.Marmatite coats a large number of fine-grained,milky drop pyrrhotite and chalcopyrite,and is closely embedded with pyrite.Part of irregular marmatite is closely associated with magnetite and gangue minerals.Fine chalcopyrite closely coexisted with pyrite,small amount of coarse chalcopyrite contains marmatite enclosures.Magnetite and gangue minerals interweave with a stockwork structure.The research results provide a theoretical basis for determining the appropriate separation process and reagent system,and realizing the comprehensive recovery of valuable elements in the polymetallic ore.
    Study on Process Mineralogy of Gold Ore in Chaihulanzi in Inner Mongolia
    REN Hui, LIU Jie, LÜ Liang, WANG Xun, ZHANG Shumin
    2022, 51(11):  141-146. 
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    In order to provide theoretical support for a modification of the original process of cyanidation leaching process,the chemical composition,mineral composition,particle size distribution and dissemination characteristics of gold ore in Chaihulanzi were detailed using chemical analysis,microscopy，automatic mineral analyzer,scanning electron microscopy,X-ray energy spectrum analysis and optical microscope analysis.The results indicated that the Au contents of the ore was 2.83 g/t,and the gold mainly exists in the form of electrum.The main gangue minerals were quartz,epidote,chlorite,sericite and calcite.The mineral composition of gold ore was complexed,and the distribution of gangue minerals was very fine,which belonged to quartz vein type gold deposits.The occurrences of electrum in the gold mine was wrapped gold,intergranular gold and fissure gold.Pyrite and pyrrhotite were the main gold bearing minerals with the relative content of 41.61% and 23.77%,respectively.Based on the results of process mineralogy analysis,an environmental protection process of stage grinding with gravity separationflotation combined process was proposed.
    Experiment Study on Copper Recovery from Copper Smelting Dust
    LIU Guixin, LIU Kuiren, CHEN Jianshe, LI Binchuan, HAN Qing
    2022, 51(11):  147-153. 
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    In order to recover valuable metals from copper smelting dust,properties analysis were carried out on the dust of high copper and high arsenic produced by a copper smelter,and the occurrence state and content of main elements in the dust were determined.The results showed that copper and zinc mainly existed in the form of sulfate and oxide,while arsenic mainly existed in the form of oxide,which has good leaching characteristics.The copper in dust was recovered by low concentration acid leaching-sulfide precipitation method,and the effect of flocculant on settling property of sulfide pulp was investigated.The results showed that:① under the conditions of initial sulfuric acid concentration of 40 g/L,leaching temperature of 50 ℃,leaching time of 90 min,liquid-solid mass ratio of 4∶1 mL/g,the leaching rates of copper,zinc and arsenic were 96.33%,96.52% and 83.72%,respectively.② Under the conditions of sodium sulfide excess coefficient of 1.3,pH value of 3.0 and reaction time of 20 min,the copper precipitation rate could reach 99.99%.The main phase of sulfide precipitation products was CuS,and the grade of copper was 56.90%,which could be directly used in industrial production.After precipitating copper,the solution could continue to recover valuable metals such as Zn.③ The addition of flocculant could increase the size of sulfide precipitate,accelerate the settlement of pulp and facilitate solid-liquid separation.
    Characteristics of Geo-electric Extraction Anomalies and Prospecting Prediction in Lejia Survey Area,Xiangshan Orefield,Jiangxi Province
    OUYANG Fei, LUO Xianrong, TONG Ruiling, HAN Shupeng, YANG Xiaoxiao, WANG Baohua
    2022, 51(11):  154-166. 
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    Xiangshan is an important uranium reserve base in China,but no progress has been made in prospecting in the middle part of Xiangshan because of the deep basement of the volcanic basin.In order to build the technical system of deep uranium exploration and develop the deep prospecting technology of geochemical exploration,Lejia survey area was selected as the study area,and the prediction work of geo-electric extraction survey method was carried out in the central area of Xiangshan.The results show that the spatial distribution characteristics of elements are closely related to the structure of Xiangshan volcanic basin and uranium mineralization.The anomalies of U,Th,Mo reflect the main mineralization,and the background values of U and Th are mainly controlled by the depth of the basement,showing a NW zonal distribution,which is consistent with the results inferred by geophysical exploration methord of AMT.The anomalies of Pb,As,and Sb may reflect acidic magma and hydrothermal activity.The above characteristics show that the spatial distribution characteristics of each element are closely related to the structure of Xiangshan volcanic basin and uranium mineralization.Geo-electric extraction survey can better reflect the geological conditions and metallogenic laws of the study area,and can provide more reliable information for deep ore prospecting.Based on the above analysis results,three prospecting prospect areas were delineated,including Xingshuxia,Shangjialing,and the NE side of Lejia,and among these areas,Xingshuxia is the best.
    Application of Geo-electrochemical Methods to Prospecting in the Concealed Uranium:A Case Study of Lujing Area,Zhuguang
    ZHAO Xinyi, OUYang Fei, LUO Xianrong, LIU Panfeng, TANG Guodong, SU Yihuai, WU Yanbin, TANG Rui
    2022, 51(11):  167-178. 
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    Lujing area is one of the important granite-type uranium deposits in China.To expand the reserves of resources in China and deepen the prospecting depth of uranium deposits,geo-electrochemical method is used to predict the prospecting in this area.Based on the principle of “ from known to unknown ”,the feasibility experiment of the known profile was carried out in the Shulouqiu Uranium Deposit in the south of the study area,and it was found that a clear geoelectric extraction anomaly appeared above the distribution range of the known ore body.The anomaly corresponds to the ore body with a high degree,and the ore indication is good,indicating that the geo-electrochemical method is feasible and effective in finding concealed uranium deposits in Lujing area.Through the geoelectric extraction measurement in the unknown area in Lujing area,based on the measurement data,the content of 12 elements (As,Co,Cu,Mo,Ni,Pb,Sb,Th,Ti,U,V,Zn) was counted and the enrichment and dispersion degree were analyzed by using the element variation coefficient diagram.The results show that the U element in the study area has good metallogenic potential.Through cluster analysis and factor analysis,the 12 elements were divided into three groups:F1 (Co-Ni-Cu-Pb-Zn-V-Ti),F2 (U-Th-Pb-V) and F3 (Mo-As-Sb).It is also found that the abnormal distribution of w(U)/w(Th)>1/3 value has an important reference value for finding uranium deposits.According to the abnormal matching of element combination and the abnormal plane distribution characteristics of U single element and w(U)/w(Th) value,combined with orecontrolling and metallogenic geological conditions and metallogenic potential,three prospecting targets are delineated so as to provide reference for the further prespecting work.
    Prediction Model of Mine Spare Parts Procurement Based on Big Data Analysis
    LIU Wei, LI Guoqing, HOU Jie, WANG Hao, CHEN Lianyun, FAN Chunchao
    2022, 51(11):  179-185. 
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    In order to solve the problems of over reliance on human experience and single procurement strategy in the process of traditional mine spare parts procurement,big data analysis technology is used to realize optimization of spare parts procurement strategy and intelligent decision-making.On the basis of sorting out the process of spare parts procurement in mining enterprises,the mining spare parts procurement prediction model with "intelligent classification of spare parts-consumption prediction of spare parts " as the core framework is constructed,and the decision-making method for guiding spare parts procurement of mining enterprises is formed.The traditional ABC classification method is extended in attribute classification,and purchase price,consumption speed,and purchase cycle are selected as the classification dimensions of spare parts,and the K-means algorithm is used to realize spare parts classification.Aiming at the procurement characteristics of different types of spare parts,the Prophet-LSTM combination prediction model was constructed,and the reasonable spare parts procurement quantity and procurement time were determined according to the prediction results,so as to realize the intelligent procurement of spare parts in mines.Based on the spare parts data of an underground gold mine in Shandong Province,the model was verified and the results showed that the application of spare parts procurement prediction model to formulate procurement plans effectively improved the management level of spare parts and scientific procurement capabilities of mining enterprises.
    Optimization and Analysis of the Consequent Rock Slope Anchorage Engineering with Weak Interlayer
    GUO Xianzhang, YANG Zhihua, LI Fengzhu, ZHANG Juanxia, ZHENG Lizhi, ZHANG Xuezhi
    2022, 51(11):  186-192. 
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    For the specific consequent rock slope,the KS-d curve of the slope safety factor(KS)and the distance (d) between the soft interlayer and the slope shoulder was obtained by using the ultimate balance theory.Then,the Geo-Slope software was used for numerical simulation to verify the analytical calculation formula and the KS-d curve mentioned above.According to KS-d curve,the key weak interlayer of consequent rock slope meeting the requirement of safety factor was determined,which was also the interface between anchorage section and free section,so that the length of anchor cable was optimized.Combined with the study of anchor cable stress mechanism,FLAC3D was used to simulate slope stability coefficient KS under different anchor rows spacing (l),so KS-l curve was obtained,thus the optimum spacing (l) of anchorage rows was determined.On this basis,an optimized slope anchoring model was established,and FLAC3D was also applied to analyze the slope stability.According to the maximum axial force diagram of anchor cable,the material parameters of anchor cable were checked by inverse calculation.The position and characteristics of potential main slip surface could be judged by the positive and negative interface of shear force received by the cement slurry.The optimized scheme met the safety standards and saved a lot of engineering work compared with the original design scheme.It was of great economic value for the future large-scale slope reinforcement and a certain reference value for similar slope engineering.
    Prediction of Slope Displacement Based on Conv-LSTM Combined with Self-attention Mechanism
    ZHENG Haiqing, ZHAO Yuelei, ZONG Guangchang, SUN Xiaoyun, JIN Qiang
    2022, 51(11):  193-197. 
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    The stability of slopes in open-pit mines directly affects the safety production of mines.Slope displacement monitoring data are important parameters to characterize the development process of slope deformation,and the early warning of landslide can be realized by analyzing and studying the monitoring data.Taking a mining slope of Hebei Jinyu Zenith Cement Co.,Ltd.as the study example,based on the displacement data collected from the monitoring points,a multi-factor slope displacement prediction model based on Conv-LSTM is established.The Long short-term memory network (LSTM) is used to extract the timing information in the displacement time series,and the deep features hidden in the displacement series are extracted by the convolutional layer.Aiming at the problem that the convolutional layer is not sufficient to extract the internal features between the data,the self-attention mechanism is introduced to fully extract the relationship features between the slope displacement data by using the self-attention mechanism.The test results show that the Conv-LSTM slope displacement prediction model with self-attention echanism has higher prediction accuracy and better correlation with the original displacement sequence,which can more truly reflect the deformation law of the slope.
    Study on the Stability Evaluation of the Mianluan Expressway Construction Site on the Goaf
    YANG Feng, WANG Liang, GUO Qingbiao, AN Zhansheng
    2022, 51(11):  198-207. 
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    In order to solve the deficiency of fuzziness and complexity in the stability evaluation of the construction site above the old goaf,based on the triangular fuzzy analytic hierarchy process and cloud model,the stability evaluation of the construction site in the goaf section of Mianluan Expressway is studied.First of all,taking into account the hydrogeological conditions,mining technical conditions,site deformation characteristics and external disturbance,a comprehensive evaluation model of construction site stability above the old goaf is established.Secondly,considering the complexity and uncertainty of the evaluation process,the analytic hierarchy process of triangular fuzzy function is proposed to determine the weight of each evaluation index.Finally,the evaluation set of the influencing factors in the study area is transformed into the digital characteristics of the cloud model by using the cloud model,and the stability grade of the study area can be obtained by combining the weight of the evaluation index.The study results are applied to the stability evaluation of the construction site of Mianluan Expressway.The results show that the stability of construction site is mainly stable and basically stable,and based on this,the countermeasures of subgrade and pavement treatment that are applicable to the goaf section of Mianluan Expressway are proposed.
    Outlier Diagnosis of Tailings Dam Displacement Monitoring Data Based on IF-CM-LOF
    YI Sicheng, KANG Ximing, WU Hao, HU Shaohua
    2022, 51(11):  208-215. 
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    In order to solve the problems of fuzzle and uncertainty in the processing results of boundary position data by isolated forest (IF) algorithm in the process of outlier identification,and improve the detection rate of outliers in monitoring data,on the basis of using the IF algorithm for preliminary identification of outliers,the outlier scores after quantitative calculation were introduced into the cloud model (CM) reverse cloud generator as variables.Based on the cloud digital eigenvalues obtained by the reverse cloud transform,the boundary data was located.The local anomaly factor (LOF) algorithm was further introduced to make the secondary accurate diagnosis of the located boundary data.The surface displacement monitoring data of a tailings dam was taken as an example to verify the model.The results show that for the real outliers and boundary random errors in the monitoring data,the detection rates of the IF model are 16.5% and 22.2%,while the detection rates of the IF-CM-LOF model are 90% and 61.1%,respectively.The diagnostic performance of outliers is obviously better than that of the IF model.
    Multi-scale Modeling of Mine Drainage System Based on Detailed Topological Structure
    LI Wenjing, ZHANG Xinxin, JIAO Yuhao
    2022, 51(11):  216-221. 
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    The construction of BIM model of mine drainage system is an objective requirement for the development of mine production information modernization.Affected by the daily drainage management requirements of mining enterprises,the model cognition is multi-tiered,and a panoramic model with detailed structure is needed to meet the application requirements of different levels.Therefore,this paper constructs a multi-scale BIM model of mine drainage system from the perspective of semantic characteristics,and puts forward the concept of "Topological Level of Details" to explore the changes of topological relations between models based on multi-scale modeling,so as to build a parameterized family library of mine drainage system and realize multi-scale application scenarios.Through experimental demonstration,this method can be associated with various processes of design,construction and daily management in the whole life cycle of mine drainage system,which helps to increase the hierarchical clarity of the model,reduce the redundancy of details,improve the work efficiency of modeling,and provide data support for meeting the comprehensive application requirements of BIM management of mine drainage system.
    Farmers′ Cognition of Heavy Metal Pollution Risk of Framland in Mining Area:A Case Study Based on the FCM Method
    YANG Mei, CHEN Yong, ZHOU Hao, LIANG Yaqi, YANG Jinfeng, HUANG Jin
    2022, 51(11):  222-228. 
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    Farmers are the direct users of heavy metals polluted farmland in mining areas,and their awareness of the risks of heavy metal pollution in farmland is related to the adoption of safe use behaviors of farmland and the health of farmers themselves.In this paper,farmers′ perceptions of heavy metal pollution risks in farmland in mining areas are divided into four levels:cause perception,fact perception,loss perception and response perception.The semi-structural interview method was used to investigate the cognition of heavy metal pollution risk of farmers in typical mining areas in Daye City,and the fuzzy cognition map of heavy metal pollution risk of farmers in mining areas was established.The cognitive analysis method of heavy metal pollution risk of farmers in mining areas was formed by integrating graph theory index analysis,cognition degree analysis and simulation analysis.The study results show that:① Farmers′ cognition is mainly based on perceptual knowledge.Since farmland income is no longer the main source of income for farmers,farmers are more concerned about the living environment and physical health.In the face of risk,it is easy to think of passive adaptation measures such as abandoning wasteland and changing planting structure.Passive adaptation measures such as abandoning farmland and changing planting structure,while paying relatively little attention to soil pollution,price reduction of agricultural products,and land rent reduction,and insufficient attention to active mitigation and governance measures such as plowing,soil improvement,and restoration.② The overall risk awareness of farmers is not high,and the awareness of risk reasons,risk facts,risk losses and risk responses is gradually decreasing.Farmers have a relatively clear understanding of risk sources,but they are relatively clear about risk facts,risk losses and risk responses.The cognition level of soil pollution is low,especially the low level of farmers′ awareness of soil pollution,which will seriously affect the safe use of farmland and the health of farmers themselves.
    Preparation of Sediment Ceramsite and Its Properties Research
    SAN Jiandi, CAI Desuo, OU Wenchang, XIE Zijun, CHEN Jiahui
    2022, 51(11):  229-237. 
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    In order to realize the harmless and resource utilization of river sediment,the sediment ceramsite was prepared by high temperature sintering using river sediment as the main raw material and bentonite,starch and limestone as auxiliary materials.Through single factor experiment,the influence of bentonite,starch and limestone dosage on the properties of ceramsite was discussed,and the raw material ratio and roasting process of ceramsite were optimized by orthogonal test.At the same time,the phase composition and microstructure of the ceramsite were studied by XRD and SEM analysis.The results showed that the optimal ratio of raw materials was the mass ratio of sediment,bentonite,starch and limestone of 70∶30∶10∶13,and the process conditions were preheating temperature of 400 ℃,preheating time of 10 min,roasting temperature of 1 000 ℃,roasting time of 15 min.Under the conditions,the bulk density of ceramsite was 725.52 kg/m3,the apparent density was 1 326 kg/m3,the water absorption rate was 25.00%,the compressive strength was 3.32 MPa,and the phosphorus removal rate was 98.69%.Sediment ceramsite has rough surface,rich pore structure,good water absorption and permeability,and high phosphorus removal rate,which could be used as ceramsite filter material in water treatment.
    Study on Volume Stability of Asphalt Concrete Based on Carbonated Steel Slag Aggregate
    HU Chenguang, LI Enshuo, SU Hang, FU Jiawei
    2022, 51(11):  238-245. 
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    Aiming at the unsoundness problem of steel slag aggregates for asphalt roads,the volume expansion rate of the asphalt mixture for carbonated steel slag was studied.The variation and relationship between f-CaO content and autoclaving pulverization rate in carbonated steel slag were investigated.The micro-morphology of carbonated steel slag was analyzed by BSE(Back Scattered Electron),SEM(Scanning Electron Microscope) and EDS(Energy X-ray Dispersive Spectroscopy).The results show that the active f-CaO in steel slag is mainly digested by carbonation below 90 °C under 1.0 MPa CO2 initial pressure,and the cubic CaCO3 particles are big size and uniform.The content of f-CaO in carbonated steel slag decreases linearly with its autoclaved pulverization rate.The active f-CaO in 4.75~9.5 mm steel slag can be completely digested by the carbonation system with temperature higher than 90 °C and time longer than 9 h,and the f-MgO or RO phase can be gradually digested,resulting in a linear decrease in the autoclave pulverization rate of carbonated steel slag.It also promotes the splitting and rearrangement of large aggregate minerals to small size and promotes the formation of CaCO3 with short clusters of inclusions such as MgCO3 and FeCO3.Finally,the unsoundness problem of steel slag can be fundamentally solved when the carbonation temperature is higher than 90 ℃ and the time is longer than 9 h.The volume expansion rate of asphalt mixture cured for 3 d (about 0.97 %) is lower than 35 % of the standard value (1.5 %),and the expansion rate of 6 d (about 1.16 %) tends to be stable and lower than 23 % of the standard value,which achieves the purpose of long-term good stability of steel slag asphalt concrete.
    Influence Mechanism of Wet Grinding Time on Carbonization and Consolidation Characteristics of Steel Slag Mud
    ZHAO Shaowei, LI Jiajie, NI Wen, MAO Shilong, QI Zihan
    2022, 51(11):  246-251. 
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    Iron recover by magnetic separation method is one of the effective methods for the utilization of steel slag,but steel slag mud producted has low hydration activity and there is no feasible means of utilization at present.Accelerated carbonation curing technology has a positive effect on improving the early strength and volume stability of steel slag products.The compressive strength and carbonation degree of steel slag mud carbonated block materials under different wet grinding time were studied by carbonation curing method,and the strength enhancement mechanism was clarified by XRD and TG-DTG analysis.The results showed that：① steel slag mud has carbonation and consolidation characteristics.Among them,the carbonation and consolidation characteristics of steel slag mud are the best after wet grinding for 60 min.The steel slag wet grinding has the best time.Too long grinding is not conducive to carbonation and consolidation.② The strength of steel slag mud is proportional to the carbonation degree.During the process of pressing and carbonization curing,the hydration reaction is very small,and the formation of carbonized products brings about an increase in strength.③ The steel slag undergoes a hydration reaction in the process of wet grinding into steel slag mud,and some of the hydration products are easily carbonated with CO2 in the air to form carbonized products.Carbonation curing can make the carbonation reaction more thorough,and the crystal form of the carbonized product is more stable.The research results provide a reference for the comprehensive utilization of steel slag mud.
    Experimental Study on Preparation of the Steel Slag and Slag Composite Cementitious Material and Its Gelling Activity Inspiration
    LIU Shuxian, SU Yan, YANG Min, XU Ping′an, YI Chunjian, NIE Yimiao, WANG Ling
    2022, 51(11):  252-258. 
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    In order to improve the utilization rate of steel slag and slag high valueadded and the admixture of steel slag in cementitious materials,the effects on the compressive strength and flexural strength of the composite cementitious materials were investigated based on different steel slagslag admixtures,ratios and different excitation methods of cementitious activity,and the hydration mechanism of the steel slagslag composite cementitious materials were investigated using Xray diffraction,scanning electron microscopy and thermogravimetric analysis and other testing methods.The results showed that when the steel slagslag dosing was 80%,the steel slagslag mass ratio was 5∶5,and the grinding time of steel slag was 80 min (specific surface area was 509 m2/kg),the 28 d flexural strength of the steel slagslag composite cementitious material was 7.3 MPa and the compressive strength was 31.3 MPa.When NaOH,Na2CO3,Na2SO4 and water glass were selected as the excitation agents,only water glass improved the activity of the composite gelling material,and its 28 d flexural strength was 8.4 MPa and compressive strength was 43.0 MPa when the modulus of water glass was 2 and the Na2O equivalent was 4%.Through SEM microscopic morphology and XRD analysis of the gelling hydration products with the addition of water glass,the microscopic morphology was tight and dense,and the generated C—S—H gel,Ca(OH)2 and Aft interweave with each other,which improves the strength of the gelling material.
    Study on Mechanical and Durability Properties of Nickel Slag and Fly Ash Based Geopolymer
    YUAN Xuefeng, WANG Hua
    2022, 51(11):  259-264. 
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    As a new cementing material,geopolymer has a broad application prospect,and the preparation of geopolymer from nickel slag is of great significance to realize the comprehensive utilization of solid waste.Nickel slag and fly ash based polymer was prepared by activation of sodium silicate and sodium hydroxide composite alkali solution.The effect of fly ash content on the mechanical properties,antifreezing properties and antiseawater erosion properties of geopolymer was discussed,and the changing rules were expounded by means of XRD,SEM and pore structure analysis.The results showed that:① the strength of geopolymer is improved by the introduction of fly ash.When the fly ash content is 10%,the mechanical properties are optimal,and the 7 and 28 d compressive strengths are 37.2 MPa and 42.5 MPa,respectively,which are increased by 21.97% and 17.40% compared with the blank group.② Proper incorporation of fly ash can further reduce the compressive strength loss and mass loss of geopolymer in freezethaw cycle and drywet cycle.When 10% fly ash is added,the compressive strength loss rate and mass loss rate of the sample after 50 freezethaw cycles are 24.7% and 14.9%,respectively,and the compressive strength loss rate after 50 wetdry cycles is 21.5%.③ Fly ash is beneficial to alkali excited reaction and increases reaction products.At the same time,the smaller particle size of fly ash provides a better filling effect on geopolymer.The results can provide reference for the development of nickel slagfly ash base polymer and the exploration of related durability problems.
    Experimental Study on Preparation of Electrothermal Building Plate from Multi-source Graphite Solid Waste
    MA Junhui, REN Zijie, GAO Huimin, YANG Yunping, LÜ Yang, LI Xiangguo
    2022, 51(11):  265-270. 
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    In order to improve the utilization rate of multisource graphite solid waste and heating efficiency in winter.the experimental study on the preparation of electrothermal building plate was carried out by using graphite mining waste rock as aggregate and adding spherical graphite tailings material with different mass.The effects of spherical graphite tailings content,curing age and humidity on the electrical and mechanical properties of electrothermal building plate were investigated.The heating temperature and plate stability were studied by electric heating test.The results showed that:① the volume resistivity of electrothermal building plate is greatly affected by content of spherical graphite tailings and curing age,and the seepage threshold appears when the content of spherical graphite tailings is 9%.② The increase of curing age is beneficial to improve the mechanical properties of electrothermal building plate,but with the increase of spherical graphite tailings content,the mechanical strength increases first and then decreases,and the optimal content is 0.8%.③ When the content of spherical graphite tailings is 9%~11%,the final heating temperature of electrothermal building plate is 71~109 ℃ at 36 V alternating voltage voltage.After long time heating,the electrical properties are stable,which can provide technical indicators for the winter heating application of electrothermal building plate.
    Bleeding Characteristics of Coarse Aggregate Filling Slurry and Its Influence on the Performance of Backfill
    XU Yi′an, DENG Botuan,
    2022, 51(11):  271-276. 
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    In order to analyze the variation characteristics of bleeding rate of coarse aggregate slurry under different influencing factors and the relationship between bleeding rate and slurry slump,an experimental study on the characteristics of bleeding rate of coarse aggregate filling slurry was carried out in the laboratory.The effects of material composition,mass concentration and cement content on the bleeding rate of slurry were analyzed,and the relationship between the bleeding rate of coarse aggregate slurry and slump was further explored.The results show that the bleeding rate of tailings slurry decreases with the increase of slurry concentration,and the decrease of bleeding rate gradually decreases with the increase of cement content.When the bleeding rate is similar,the mass concentration of tailings slurry is significantly lower than that of coarse aggregate slurry,indicating that the incorporation of waste rock can help the mine to achieve high concentration slurry filling.The bleeding rate of coarse aggregate slurry also showed a trend of decreasing with the increase of mass concentration,but the decrease of bleeding rate showed a trend of decreasing with the increase of coarse aggregate content.The bleeding rate of slurry decreases with the increase of cement content,and the decrease of bleeding rate increases with the increase of concentration.The slump of slurry gradually increases with the increase of bleeding rate.Therefore,the transport performance of slurry can be qualitatively judged by the change of bleeding rate parameter.