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    15 July 2022, Volume 51 Issue 07
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    Background and New Thinking about Intelligent Blasting
    WANG Xuguang, WU Chunping
    2022, 51(07):  2-6. 
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    Engineering blasting has gradually developed into an independent and systematic research field.However,there are some bottleneck problems at present,such as lack of fundamental breakthrough in blasting theories,difficulties to collect blasting multiple heterogeneous information,lack of effective technologies for blasting surroundings perception,deficiency of blasting operations accuracy,and lack of unified data interaction and information processing mechanism.These problems hindered the development of blasting technologies to the direction of "precision control".In recent years,the concept of informatization has gained increased attention.In addition,the new generation of information technologies such as 5G,artificial intelligence(AI),big data,and cloud computing accelerate the penetration and deep integration with various fields of economy and society.The authors propose the development direction of intelligent blasting,based on the new generation of information technology and the development trend of blasting industry in China.The historical background and new thinking model of intelligent blasting were introduced.
    Study Prospect of Precision Blasting Technology in Open-pit Deep Hole Bench
    XIE Xianqi, HUANG Xiaowu, YAO Yingkang, HE Li, WU Yue
    2022, 51(07):  7-18. 
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    Since the 21st century,with the progress and development of drilling equipment and blasting equipment,scale of open-pit blasting mining is expanding,and the open-pit deep hole bench blasting technology enters a new stage of refinement.In recent years,open-pit deep-hole bench blasting technology make great technological breakthroughs and create remarkable social and economic benefits.Based on the concept of precise blasting,the research progress of intelligent blasting design,open-pit drilling equipment,digital electronic detonator,field mixed explosive,charge structure and initiation network in the field of open-pit deep-hole bench blasting are summarized and described.The study results show that:① There are many types of intelligent blasting design systems and the progress is obvious.It is necessary to increase the promotion efforts in combination with the production practice to truly achieve the goal of auxiliary engineering design.② The manufacturing capacity of open-pit drilling equipment in China lags behind that of the developed countries in the world.It is necessary to develop the specifications and performance of the equipment and improve the level of automation and intelligence.③ Digital electronic detonators and field mixed explosives enhance the intrinsic safety of blasting equipment,not only improve the safety of blasting equipment,but also help to improve rock breaking effect and reduce blasting vibration.④ The charge structure and initiation network are important embodiments of precision blasting technology,but the relevant basic theories are not perfect.It is necessary to strengthen the interdisciplinary integration,and ultimately achieve the accurate release of explosive energy and improve the energy utilization rate.The development status and main problems of open-pit deep-hole bench blasting technology are analyzed,and the research and development direction of this technology is discussed.
    Gas Explosion Study on Load Characteristics and Action Effect in Pipe Gallery
    ZHONG Dongwang, LI Tengfei, HE Li, YANG Zhilong, CHEN Jiangwei
    2022, 51(07):  19-26. 
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    The gas explosion effect of pipe galleries seriously endangers urban development and social life stability.Studying the load characteristics and effect of gas explosion has guided significance of the optimal design of pipe gallery structure.The similarity model test of gas explosion in urban pipe gallery was designed,and the time history curve and pressure distribution characteristics of gas explosion shock wave under different methane concentration were analyzed.The calculation formula of the peak displacement response of the structural roof under the action of the gas explosion load is theoretically deduced,and the theoretical calculation results of the displacement response are verified by combining the model experiment results and numerical simulation results.The results show that when the concentration of methane is 9.5%,the peak overpressure of gas explosion is higher than the concentration of 10%.In this case,the peak value of overpressure depends on the concentration conditions of gas explosion.Under the test conditions,the size of the overpressure peak depends on the concentration conditions of the gas explosion.The gas explosion overpressure time-history curve has a boosting time of 500~700 ms,and the overpressure action time is about 1 500 ms,the action time of explosion overpressure is directly related to the size of the model.The peak overpressure at each measuring point is evenly distributed,which can be approximated as a time-varying uniform load.The study results show that the given calculation formula for roof displacement response is effective and can be used to calculate the roof′s maximum displacement under the action of gas explosion loads.
    Application of Digital Electronic Detonator in Blasting Excavation of Rock Roadway in High Gas Mine
    YANG Renshu, BAO Zhouqi, WANG Yanbing, HU Shaoyin, XIE Ping, HE Zhihao
    2022, 51(07):  27-34. 
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    The traditional electric detonator has only five segments,which can not meet the requirement of delay time for the borehole subsection technology.Digital electronic detonator adopts electronic control module,blasting delay time can be arbitrarily set,the minimum delay time can be set to 1 ms,to meet the requirements of completing the blasting process within 130 ms of gas roadway.In addition,the utilization rate of borehole is low due to the increase of rock clip at the bottom of borehole in the deep hole blasting driving of rock roadway in coal mine.In this paper,based on digital electronic detonator,the piecewise cut blasting technology is applied to change the continuous charge in the cut hole to the piecewise charge and realize the piecewise delayed initiation.The new technology was tested in Gubei Coal Mine in Huainan.The results show that,based on digital electronic blasting cap,the single-cycle footage increases by about 0.7 m,the hole utilization rate increases by about 10%,and the average lumpiness decreases by about 15% compared with the original scheme,which provides a good condition for the next cycle.It is estimated that the monthly footage can be increased from 65 m to 100 m,which improves the tunneling efficiency on the whole.As the first test of digital electronic detonator in underground rock tunneling,digital electronic detonator can still be used normally under high gas condition,which can provide reference for similar rock tunneling blasting construction in the future.
    Explosion Energy Conversion Mechanism of Green Blasting
    ZHOU Guisong, ZHONG Dongwang
    2022, 51(07):  35-41. 
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    The essence of green blasting is to improve the utilization level of explosion energy,increase the beneficial work related to rock breaking effect as much as possible,and reduce harmful work,ineffective work,heat loss and energy loss.Based on the theory of thermodynamics,the mechanism of explosion energy conversion is preliminary studied under the detonation gas loading.The stage,condition,path,cost and influencing factors of the conversion of internal heat energy carried by explosive gas into work is also explored.The physical and mechanical model of explosion energy conversion process including three conversion processes is established.The study reveals the distribution law of explosion energy in the near,middle and far areas of blasting.Four main final transformation forms of explosion energy are pointed out:rock breaking work,heat exchange loss,gas leakage loss and dynamics energy loss.On this basis,the implementation path of green blasting is discussed.
    Study and Development on Wireless Remote Intelligent Initiation System Based on LoRa Internet of Things
    LI Pingfeng, ZHANG Jinlian, XU Zhenyang, ZHANG Bingbing, YANG Fei, LI Xin
    2022, 51(07):  42-49. 
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    Intelligent initiation system is one of the important means to effectively improve blasting safety control level.At present,there are still some problems,such as insufficient initiation energy or wrong network connection.A wireless remote intelligent blasting system based on LoRa IOT is developed,comparing the differences between LoRa technology and mainstream wireless communication technology,briefly describing the intelligent detonation.LoRa communication technology and HM-TRLR-S433MHz wireless remote intelligent blasting system has the advantages of long communication distance,strong anti-interference,small size,etc.;GPS module selected Air530Z module,digital electronic detonator receiving module for Zigbee wireless transmission module,using MBus driver circuit to send the detonation signal to the digital electronic detonator,which could realize wireless initiation.The safety control and power supply design principle of the system is implemented to test the anti-interference and system reliability of the wireless remote intelligent blasting system for different distances and terrains.The results show that the system operates stably in the horizontal distance range from 200 m to 1 000 m and in the height difference range from 50 m to 100 m,and the module normal rate exceeds 90% under electromagnetic interference and stray current interference,and the vibration interference meets the design requirements,so the system reliability is up to 100%.The research results achieve independent operation of each digital electronic detonator,intelligent control of blasting area,improve the efficiency and safety of blasting network connection,provide technical support for intelligent blasting construction,scientific management and decision-making.
    Study on Pore Pressure of Discharge Head of Liquid CO2 Phase Change Cracker
    WANG Wei, LI Yadong, ZHENG Yongxiang, YIN Chao, LI Chaobo, LU Xiaoxi, ZHOU Xingyu
    2022, 51(07):  50-57. 
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    Using CO2 phase change blasting instead of traditional explosive blasting as input energy,the physical transformation of "blasting and increasing permeability" of low-permeability sandstone uranium deposit is of great significance to improve the production of natural uranium in China.At present,the industrialized CO2 fracturing device is mainly designed for coal and rock mining and other fields,and has poor adaptability in blasting seepage increasing conditions.Therefore,the porous design of the discharge head of the traditional crack maker is carried out to balance the pressure of each vent hole,which provides a theoretical reference for the design of the crack maker with "large and uniform pressure of each vent hole" in the field of blasting infiltration.RNG k-ε based on the turbulence model,the numerical simulation test of the energy discharge head of the crack breaker is carried out based on computational fluid dynamics (CFD).The gas flow law and pressure distribution characteristics in the energy discharge head are analyzed,and the influence law of the position relationship and the pore size characteristics on the pressure change of the vent hole is explored.The results show that in order to keep the stable output of pore pressure,the symmetrical distribution of vent holes is better than the staggered distribution of vent holes;At the same time,the diameter of the vent hole is set as a non-uniform type from the head to the end,which can effectively reduce the pressure difference between the pores.The above analysis results furhter show that the type of non-uniform and symmetrical energy discharge head is more in line with the needs of blasting infiltration.
    Experimental Study on On-site Mixed Emulsion Explosive in Underground Roadways Excavation Blasting
    HAO Yafei, XUE Li, ZHANG Xiaoyong, YANG Minhui, XIAO Qingsong
    2022, 51(07):  58-63. 
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    In order to solve the problems of high manual charging intensity,low operation efficiency and poor safety when using packaged explosives in underground roadways excavation blasting,a modular onsite mixed emulsion explosive charging device is developed,the end sensitization device is designed,the sensitization technology research at different times is carried out,and the way of using on-site mixed emulsion explosives to realize smooth blasting is explored.The results show that the charging accuracy of modular charging device is controlled within ±1.5%,which is well adapted to the characteristics of low single hole charge.Using the end sensitization technology and different concentrations of sensitizers,the explosive density is stable and controllable.The modular charging device is integrated into the chassis of the engineering vehicle,the charging efficiency is increased by 2.4 times through the wireless terminal control system,and the blasting effect is good.At the same time,the performance of the smooth blasting technology of on-site mixed charging explosives has been preliminarily verified,and the whole set of technology can well replace the traditional blasting operation mode of packaged explosives.
    Experimental Study and Numerical Simulation on Micro-difference Time of Cutting Hole of Electronic Detonator in Rock Roadway Blasting
    LI Hongwei, HUANG Xinxu, WU Lihui, YANG Saiqun, GUAN Yueqiang, WU Yanmeng
    2022, 51(07):  64-72. 
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    In order to study the effect of the delay time between the cutting hole and the auxiliary hole on the cutting blasting effect,the model experiment of electronic detonator was used to study the formation process and characteristics of the cavity under different delay conditions.In the experiment,the high-speed camera was used to observe the formation process of the block cavity,and the finite element analysis software ANSYS / LS-DYNA was used to carry out the numerical simulation analysis on the crack propagation of the cavity.The results show that: ① Under the experimental conditions of this model,when the delay time is 1~3 ms,the explosion energy interaction between the cutting hole and the auxiliary hole is the closest,and provides a new free surface for the auxiliary hole initiation,reduces the clamp production used in the auxiliary hole initiation,and the blasting effect is the best.② The rock mass medium between adjacent cutting holes and auxiliary holes is broken more fully than the rock mass medium in the cavity contained in the cutting hole.When the initiation time is delayed by 1 ms,the instantaneous velocity of rock movement between the cutting hole and the auxiliary hole under the blast wave of the auxiliary hole is the largest,and the crack range generated by the initiation of the auxiliary hole is the largest,so the cutting effect is the best.③ The influence on the rock in the cavity gradually disappears after the initiation of the cutting hole exceeds 1 ms,and the initiation of the auxiliary hole is not conducive to the superposition of the explosion energy between the cutting hole and the auxiliary hole,which reduces the blasting effect of the cutting hole.
    Influence Mechanism and Application of Delay Interval on Rock Breaking by Blasting
    ZHANG Xiliang, YI Haibao, HAN Han, LI Erbao, WANG Yu, YANG Haitao, ZHOU Jian
    2022, 51(07):  73-79. 
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    In order to optimize the appropriate delay interval and guide the control of production blasting parameters,the numerical simulation software was used to establish two-dimensional and three-dimensional numerical calculation models,and the influence of different delay intervals on the rock breaking amount was studied.The relationship between rock breaking amount and vibration velocity was studied,and field application tests were carried out.The study results showed that the blasting sequence of the front and rear rows of blast holes does not affect the optimal delay interval,but affects the final rock breaking amount.With the increase of the delay interval,the blasting rock volume shows a fluctuating trend,and when the delay time is 10 ms,the maximum rock breaking volume and larger vibration speed can be obtained.The two indicators of vibration speed and rock breaking volume should be comprehensively considered.Within the safe vibration speed range of buildings (structures),blasting rock volume should be given priority to improve production efficiency.After the field application,the blasting size is relatively uniform,which effectively verifies the feasibility and reliability of the optimal parameters.
    Blasting Powder Rate Control Technique in Aggregate Mines
    YE Haiwang, LI Xingwang, YUAN Erjun, LEI Tao
    2022, 51(07):  80-88. 
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    Controlling the rate of blasting powder ore is an important way to reduce ore loss and promote high quality development of aggregate mine.Taking a limestone aggregate mine as an example,firstly, rock dynamics tests were carried out through on-site mine sampling,and the crushing characteristics of limestone under dynamic load were analyzed in combination with the screening test of broken rock,and the range of energy consumption density and corresponding dynamic load intensity which control powder ore production were explored.Secondly, based on the test results,the dynamic load strength and particle vibration velocity peak criterion were introduced to carry out numerical simulation of bench blasting with different delay time between holes,aiming at reducing the rate of blasting powder mineral and taking into account the yield of controlling blasting bulk,the delay time between holes was optimized.Finally,the optimized delay time is applied to mine production blasting to verify its optimization effect.The results show that the reasonable energy consumption density for control of powder ore is in the range of 1.85~2.05 J/cm3,and the corresponding dynamic load strength is in the range of 200~205 MPa.The numerical simulation results show that when the delay time is 20 ms,the blasting powder ore rate and bulk rate are relatively low, and the blasting effect is the best.When the delay time between holes is adjusted to 20 ms,the blasting powder ore rate decreases by 6.12%,and the blasting bulk rate and average crushing size also decrease correspondingly.
    Directional Demolition of Mine Landslide Dangerous Rock Mass Emergency Removal Method by Throwing Blasting
    HU Bin, JIA Yalan, LI Jing, WEI Erjian, MA Liyao
    2022, 51(07):  89-96. 
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    Mine landslide-hazardous rock mass is prone to secondary landslide disasters under extreme conditions.How to realize emergency risk elimination and the safety and effectiveness verification of risk elimination methods has always been a practical problem that plagues mining enterprises.Taking the landslide dangerous rock mass on the west side of Mohuandang as the research object,according to the technical idea of directional demolition and blasting of urban high-rise buildings,a directional demolition throwing blasting emergency elimination method is proposed.Using the method of bottom-up and inward-by-hole millisecond differential blasting,the landslide dangerous rock mass is directionally thrown to the designated position,in so as to achieve the purpose of emergency risk management and convenient procurement and transportation.Considering the irreversibility of the on-site risk elimination test,using the discrete element method,a dynamic analysis model for blasting dangerous rock mass in equal proportion mines was established,the blasting effect is simulated by the explosion point particle expansion method,set the no-reflection boundary,and analyze the final blasting hazard elimination effect,so as to verify the reliability of the method in advance.The results show that with a detonation time difference of 50 ms,when detonating sequentially from the 740 m—760 m—780 m platform and from the slope inward,the boulder yield is small,and there is no tight bottom,all landslide dangerous rock mass can be removed.The farthest throwing distance of the dangerous rock mass is 186 m,in line with the Blasting Safety Regulations (GB 6722—2014) of the flying stone safety distance regulations.The maximum blasting height is 22 m,mainly stacked on the 685 m platform at the foot of the slope,it can realize the safe and rapid mining,loading and transportation of dangerous rock mass.The research results provide a new method for the safe and rapid management of this kind of "shaky" landslide dangerous rock mass.It has certain engineering application value.
    Grey Correlation Analysis of Vibration Reduction Effect of Damping Hole Parameters
    DUAN Baofu, ZHANG Zhengxin, ZHANG Chunwu, SUN Zongjun
    2022, 51(07):  97-104. 
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    Blasting in mines and tunnels will cause certain vibration hazards to adjacent buildings,and it is necessary to explore feasible vibration reduction measures during the construction process.Setting vibration-damping holes in the working face is a new type of active vibration-damping technology.The research on vibration-damping holes can provide a reasonable vibration-damping scheme for mine and tunnel blasting design.Combined with field measurement and numerical calculation,the law of vibration damping effect of vibration damping holes during blasting construction was analyzed,and the grey correlation degree theory was used to determine the degree of influence of vibration damping hole parameters on vibration damping effect,and each parameter affected vibration damping effect.The primary and secondary relationship can be described as:distance between the edge of the damping hole>distance between the damping hole and the explosion source>diameter of the damping hole>depth of the damping hole>row spacing of the double-row damping hole.Combined with numerical calculation and comprehensive analysis of on-site construction effects,it is found that during the construction process,the distance between the edge of the vibration-damping holes is 120 mm,the distance between the vibration-absorbing holes and the explosion source is 2 000 mm,the diameter of the vibration-absorbing holes is more than 120 mm,and the depth of the vibration-absorbing holes is 1 200~1 500 mm,double-row vibration-damping hole spacing is 50~100 mm,which can achieve better vibration-damping effect.The results of numerical simulation,gray correlation analysis and measured data show good consistency in the vibration reduction effect,which can provide a reference vibration reduction technology for blasting construction in mines and tunnels.It has certain reference value and guiding significance for vibration control.
    Blasting Process Optimization Based on Grade Control Model in Openpit Uranium Mine
    CAI Xingqi, DONG Wenming, TAN Qiren, YU Zhi, BI Lin
    2022, 51(07):  105-112. 
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    Husab Uranium Deposit is characterized by complex orebody shape,unstable thickness and uneven distribution of useful components.When openpit mining method is adopted and geological resource model is used in blasting design of blasting area,due to the low precision of model,the boundary between ore and waste rock is not accurate enough,the expected blasting effect is often not achieved,resulting in high dilution rate and loss rate of mining.The grade control model is established based on the hole grade data of a single blasting area.The model has the advantage of high accuracy,which can reflect the actual distribution of ore and waste rock in the blasting area more accurately,and provide reliable basis for blasting design.Since the borehole grade data can only be obtained after drilling and logging,the traditional blasting process needs to be optimized.Under the condition that the boundary line between ore and waste rock is clear and their distribution is relatively concentrated in the blasting area,the blasting separation of ore and waste rock can be realized by changing the blasting charge,charging structure and connecting mode,and further reduce the mining dilution rate and loss rate.On the basis of the study of grade cotrolling model,the original blasting process is optimized,and the separation blasting test is done by selecting the proper blasting area.The test results show that the dilution rate of the blasting area is effectively reduced by the optimization of blasting process.The study results indicated that the blasting design process optimization of Husab Uranium Mine based on grade control model can effectively improve the mining quality and efficiency,and basically meet the requirements of modern mine fine management.
    Study on Propagation Characteristics of Axial Detonation Wave of Mining Linear Charges
    MIAO Yusong, GUO Jian, CHEN Xiang, WANG Hailiang, ZHANG Yiping, SUN Bowen
    2022, 51(07):  113-119. 
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    A bilinear symmetrical initiation technique is proposed to solve the problem of high bulk rate and bedrock when hard rock blasting.In this paper,the propagation characteristics of axial detonation wave of cylindrical charge under bilinear symmetric initiation are analyzed by combining numerical simulation with the standard test.The numerical simulation results show that the detonation wave produces positive reflection,oblique reflection,and Mach reflection in sequence when the bilinear symmetric initiation is adopted,which can effectively increase the detonation pressure inside the explosive.The detonation pressure can reach more than 1.75 times of the stable detonation pressure at the central point of initiation.Compared with the central point initiation,the detonation pressure value is more than 4.09 times of the stable detonation pressure on the crosssection edge perpendicular to the line between the center of the charge column and the initiation point.In the range of 32~80 mm charge diameter,the cumulative effect of detonation collision increases with the increase of the charge diameter.Compared with the lead block test results,the power capacity of the explosive can be increased by 14.5% (lead block test) and 17.1% (numerical simulation) when using the bilinear symmetric initiation method compared with the central point initiation method.The research results are of certain significance to study the mechanism of detonation collision energy accumulation,and provide a new method of reducing the blasting bedrock and improving the energy utilization rate of explosives.
    Study on the Optimization Design of Blasting Parameters and Threedimensional Visualization of Mine Roadway Excavation
    ZHU Quanjie, ZHANG Zhen, LIANG Juan, ZHANG Jiaofu, LIU Xiaohui, WANG Zhishuai
    2022, 51(07):  120-127. 
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    In view of the current situation that the workload of designing blasting parameters for underground excavation in mines is large and inefficient,and the construction layout drawings are mostly two-dimensional plans,it is proposed to use particle swarm optimization algorithm and neural network algorithm to establish an improved model for the design optimization of blasting parameters for underground excavation to accurately predict the optimal blasting parameters for the roadway to be excavated.Using the designed optimal blasting parameters as data support,3D visualization techniques are applied to automatically construct 3D fine models of blast holes,charge structures,etc.The study was carried out in a mine in Shandong Province to optimize the design of blasting parameters and construct a 3D visualization model.The results show that the error between the blasting parameters designed in this study and the blasting parameters of typical successful cases is small,MAE,RMSE and R2 are 0-154，0-096 and 0-914 respectively.The established 3D model of blasting borehole is of high quality and can directly describe the information of blasting boreholes such as spatial distribution,charging structure and so on.
    Test of Underwater Drilling Blasting Damage Monitoring Based on Piezoelectric Signal
    SI Jianfeng, QIAN Bo, ZHONG Dongwang, HE Li, CHEN Jiangwei
    2022, 51(07):  128-135. 
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    The underwater explosion vessel was used to simulate the water depth of 40 m,and two sets of underwater concrete models with different charge structures were used to conduct a single blasting damage test with the same charge amount.Before and after blasting,the active signals of the concrete samples along the central axis of the hole were collected by using the active monitoring method of piezoelectric ceramic sensors.Through the statistical analysis of the peak value and energy of the signal at the monitoring point,it is found that the signal received along the direction of the hole gradually increases,and the peak value and energy of the signal received near the bottom of the hole appear obvious mutation.By comparing the position of the mutation point under different charge structures,it is found that the mutation point of the sample with high impedance ball and coarse sand at the bottom of the hole is significantly advanced,indicating that the damage depth of the retained concrete part at the bottom of the hole is small.Finally,the frequency law of piezoelectric signal before and after blasting was studied by EMD method.The research showed that the underwater energy dissipation blasting technology can effectively weaken the damage to bedrock rock mass caused by borehole blasting,and the damage monitoring method based on piezoelectric signal can be used to monitor the damage depth of rock mass in underwater borehole blasting.
    Dynamic Damage and Energy Dissipation of Broken Red Sandstone Considering Mesoscopic Characteristics
    XU Zhenyang, ZHANG Jiuyang, WANG Xuesong, GUO Lianjun, LIU Xin
    2022, 51(07):  136-144. 
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    It is one of the ways to understand the mechanism of rock blasting to explore the dynamic properties of rock in mesomechanics.The dynamic loading of red sandstone under confining pressure was carried out by the split Hopkinson pressure bar,and the microscopic characteristics were characterized by porosity change.Based on the energy dissipation index,the energy dissipation of dynamic damage and fracture of red sandstone was studied.The results show that the overall trend of impact number decreases with the increase of air pressure,and the energy dissipation increases before the specimen is broken,and there is no obvious rebound.In the third or fourth shock,the dynamic characteristics are different.In the initial impact,porosity is closed from mesopores and macropores to micropores.With the increase of impact load,the peak value of micropore porosity difference moves backward.
    Prediction of Blasting Vibration Velocity of Mines Based on Particle Swarm-least Squares Support Vector Machine Model
    HE Li, LIU Yihe, LI Linna, CHEN Jiangwei, YAO Yingkang, LIU Changbang
    2022, 51(07):  145-150. 
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    Blasting seismic hazard is one of the most significant negative effects in the process of mining.Accurate prediction of peak particle velocity (PPV) is of great engineering practical significance to effectively prevent the instability and damage of buildings (structures) caused by blasting vibration.The blasting vibration test of openpit mine excavation was designed and carried out,the sensitivity analysis of the influencing factors of PPV was analyzed by the grey correlation analysis method,and the primary and secondary relationships between the influencing factors were determined.On this basis,the least squares support vector machine (LS-SVM) model is established to predict PPV,and the optimal parameter combination of regularization parameters and kernel function width coefficient in the LS-SVM model is determined by local optimization of particle swarm optimization (PSO).Finally,the prediction results of PSO-LSSVM model are compared with those of BP neural network model,LS-SVM model and traditional Sadowski formula.The results show that the fitted correlation coefficient (R2),root mean square error (RMSE),mean relative error (MRE) and Nash-Sutcliffe efficiency coefficient (NSE) of the PSO-LSSVM model for PPV prediction are 97.38%,2.68%,1.36% and 99.98%,respectively,and the PSO-LSSVM model has higher prediction accuracy and better generalization ability,which is feasible for mine blasting PPV prediction under multi-factor influence.
    Study on Dust-settling Technology of Explosive Water Mist Field for Trench Blasting in Open-pit Mine
    HUANG Yiwei, WANG Desheng, GUO Bin, LI Yonghua, WANG Hongfei, DING Ke
    2022, 51(07):  151-157. 
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    Due to the small network parameters and high explosive consumption in trench blasting of open-pit mine,compared with normal bench blasting,the blasting dust produced by the trench blasting is higher in concentration,faster in diffusion,and more harmful in pollution.The traditional method of surface sprinkling in the blast area can only wet the superficial rock mass.Affected by the harmful effects of blasting flying rocks and shock waves,remote spraying dust reduction methods such as mine water cannons cannot be implemented simultaneously with blasting dust production.In addition,the passive treatment of blasting dust after diffusion is difficult and ineffective.In this paper,Fluent numerical simulation was used to study the formation and initial expansion characteristics of trench blasting dust in open-pit mine,and the technical scheme of in-situ dustfall was proposed by laying explosive water mist field around excavation trench blasting area.Through the orthogonal test of explosive water bag and explosive water mist field,the important dust-settling technical parameters such as the composition of explosive water bag,the spatial scale and the stagnation time of explosive water mist field were determined.Explosive water mist field was set up based on the principle of "surrounding interception,synchronous generation and in-situ adsorption" in the field dustfall test of Bayan Obo Iron Mine.On-site high-speed photography analysis showed that the explosive water mist field was generated at a high speed in the early stage of mushroom dust cloud formation,the blasting dust was intercepted and adsorbed simultaneously to achieve the environmental protection goal of dust reduction at the source.The test results showed that the mass concentration of blasting dust was reduced by 40%,which provided a new environmental protection technology for low dust trench blasting and green mining of open-pit mines.
    Study on the Technology of Intercepting and Reducing Dust by Explosion Water Mist Field in Open Bench Blasting
    MA Chao, WANG Desheng, GUO Bin, LI Yonghua, WANG Hongfei, DING Ke
    2022, 51(07):  158-163. 
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    The dust from open-pit bench blasting has the characteristics of instantaneity,high concentration and fast diffusion,which will endanger the health of stope workers,increase the loss of the air intake system,and pollute the surrounding atmospheric environment.Due to the hazards such as blasting flying rocks and shock waves,personnel and equipment cannot be close to the pollution source in the blasting area,so the traditional means of sprinkling water to reduce dust can not be implemented synchronously with the blasting.In this paper,the method of numerical simulation and field test is used to study the explosion water mist dustfall,combined with the actual situation of Bayan Obo Iron Mine,the three-dimensional flow field model of open-pit bench blasting is established,the technical characteristics of bench blasting dust and explosion water mist field are studied,and the technical scheme of explosion water mist field intercepting dustfall is put forward based on the simulation results of explosion water spray field and blasting dust.The reasonable arrangement range of the water bag in the front of the step slope at 16~21 m was determined,the functional relationship between the lateral dynamic migration trajectory of blasting dust and time was obtained as Δt=t-1.21,and the reasonable delay time of the water bag excitation was determined.The optimal combination of water bag size and explosion load was determined by the range analysis of the water fog type test results using SPSS software.The test results showed that the space scale of the explosion water fog field was 18 m×8.7 m,and the time for water fog to reach the maximum space scale was 1.2 s.The field blasting dust suppression test results showed that the dust concentration at 50 m and 100 m away from the blasting area was reduced by 43.6% and 40.9%,respectively,when the water bag was laid at 18.5 m in front of the slope and the reasonable excitation delay was set at 1 100 ms.The simultaneous implementation of the explosion water mist field and the blasting operation was realized,and the dust reduction effect was remarkable.
    Experimental Study on Direct Reduction for a Carboncontaining Magnetite Concentrate
    ZHU Chaobo, HUANG Zili, YANG Fu, YUAN Chenguang, LIU Chuyu, HUANG Tao, XIAO Shuo
    2022, 51(07):  164-169. 
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    In order to explore the new technology of direct reduction iron and improve product quality,carbon was added in a low sulfur magnetite concentrate with the total iron contents of 64.71% for the preparation of raw pellets and dextrin as organic binder.Then,the reduction roasting tests were carried out under the protection of nitrogen.The results showed that under the conditions of coke dosage of 20%,reduction temperature of 1 150 ℃,reduction time of 1 h,dextrin addition of 1%,grinding fineness of -0.074 mm accounting for 80% and magnetic field intensity of 80 kA/m,direct reduced iron product with total iron contents of 92.67% and iron recovery rate of 95.74% was obtained.With the addition of 1.6% sodium carbonate,the total iron contents of the direct reduced iron product reached 93.55%,which increased by nearly one percentage point,and the iron recovery rate decreased to 94.20%.SEM-EDS analysis showed that the product has large grain size and obvious metal iron diffraction peak,which can be used as high quality raw material to replace scrap steel in electric furnace steelmaking.
    Experiment Study on Synchronous Iron Extraction of Pre-oxidation and Heat-retaining Reduction for a Cyanide Tailings
    ZHAO Lingbo, ZHAO Bing, GAO Peng, DONG Zaizheng
    2022, 51(07):  170-174. 
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    The total cyanide contents of a gold-selecting roasting cyanide tailings from Liaoning Xindu Gold is 719 mg/kg.The main iron minerals in residue is mainly hematite and the TFe grade is of 35.08%.The iron concentrate could be recycled from the cyanide tailings with the decomposition of cyanide efficiently by synchronous iron extraction of per-oxidation and heat-retaining reduction.The results showed that the total cyanide content in cyanide tailings can be reduced to below the detection limit at 550 ℃,25 min in the cyanide-oxidation stage,and the heating of the tailings was completed.Then,under the condition of reduction temperature of 560 ℃,reduction time of 30 min,CO concentration of 40%,gas flow of 500 mL/min,the heat-retaining reduction tests was carried out.The iron concentrate with a TFe grade of 58.94% and the recovery of 89.93% was obtained by low intensity magnetic separation at magnetic field intensity of 143.28 kA/m after being ground to -0.038 mm accounting for 82.02% by rod mill.This process can not only oxidize the cyanide effectively,but also realize efficient recovery and utilization of iron minerals from cyanide tailing.
    Effect of Fine Hematite on Adsorption Properties of Starch with Quartz and Its Mechanism Research
    ZHANG Lunxu, SUN Boyuan, JIN Dan, MA Yiwen
    2022, 51(07):  175-180. 
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    In order to analyze the effect of fine hematite on the interaction between quartz and starch inhibitors,the adsorption experiments of different particle sizes of hematite,quartz single mineral and their mixture with starch inhibitors were studied,and FT-IR and AMF were used to analyze and characterize,which could provide theoretical guidance for optimizing flotation process of Anshan-type fine hematite.The results showed that when the adsorption temperature was 35 ℃,the pulp pH value was 11.5,the concentration of starch inhibitor was 3 g/L,and the adsorption time was 5 min,the starch inhibitor had the greatest difference with hematite and quartz.And with the increase of starch concentration,the adsorption strength of -0.037 mm fine hematite particles was significantly enhanced.The physical adsorption of starch inhibitor on the fine hematite surface is dominated by multimolecular layers adsorption based on van der Waals force,and the physical adsorption of starch inhibitor on quartz surface occures in the multi-molecular layer,and there exists adsorption hysteresis.When the content of -0.045 mm fine hematite particles was 34.6%~88.4%,the inhibition of starch could be weakened,resulting in iron concentrate entering tailings and reducing the flotation indexes.
    Purification Experiments Research of a Lowgrade Sedimentary Sepiolite
    HOU Kai, ZHENG Chenghui, ZHANG Junhua, YANG Huaming
    2022, 51(07):  181-186. 
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    The grade of a low-grade sedimentary sepiolite ore from Hunan Province is 28.90%,and the main gangue minerals are quartz,talc and calcite.In order to improve the grade of sepiolite as much as possible and simplify the beneficiation process,the flowsheet of water leaching,sieving,dispersion and sedimentation was carried out according to the properties of the raw ore.After water leaching,the raw ore was sieving with a 74 μm sieve,and the fine grained products were screened for dispersion test.After optimization of dispersion conditions,the proper dispersant was determined as sodium pyrophosphate,and the proper addition amount was 0.8 g/L.The grade of sepiolite was 92.77% and the enrichment ratio was 3.21 with the dispersion solid-liquid ratio of 1∶10 mg/L,the dispersion time of 20 min,the dispersant speed of 2 000 r/min and the slurry pH of 9,which realized the efficient purification of sepiolite resource.
    Study on the Reaction Mechanism of Fluorite and Calcite Flotation Separation by Carboxymethyl Cellulose
    MA Qiang, LI Yubiao, LI Wanqing, YANG Xu
    2022, 51(07):  187-192. 
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    In order to separate fluorite and calcite more effectively by flotation,the effects of carboxymethyl cellulose (CMC) in the flotation separation of fluorite and calcite was studied by flotation test and various measurements such as contact angle,zeta potential,microcalorimetry,thereby revealing the selective inhibition mechanism for fluorite and calcite by CMC.The results showed that the CMC concentration of 20 mg/L depressed calcite efficiently and maximized the flotation separation at pH=8.Due to the high adsorption of —RCOO— dissociated from the CMC component on the calcite surface,the calcite surface only adsorbed a small quantity of oleate ions.At the same time,an apparent negative shift of calcite zeta potential was observed,leading to a greater hydrophilicity,consistent with the contact angle measurements.The proposed adsorption model indicated that the diminished active Ca2+ sites on the calcite surface was the main reason for its depression,with a reaction order of n=1.
    Experimental Study on Beneficiation of a High Mud Accumulation Type Bauxite in Southwestern District
    DOU Zengwen
    2022, 51(07):  193-197. 
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    The Al2O3 and SiO2 contents in a high mud accumulation type bauxite in southwest district are 47.25% and 10.86%,respectively,and the Al to Si ratio is 4.35.The main target mineral is diaspore,the main gangue mineral is kaolinite,and other metallic minerals are hematite,goethite and anatase.The symbiotic relationship of minerals in ores is complicated,and the particle size of target minerals is uneven with the low monomer dissociation degree.The iron,titanium minerals and aluminum minerals is in complicated symbiotic relationship,leads to the difficult in effective separation.The dressing process of full mud flotation was selected with sodium hydroxide as regulator,sodium silicate as inhibitor,EMB-506 as collector.Under the condition of grinding fineness of -0.074 mm accounting for 70%,flotation concentrate with Al2O3 grade of 51.62%,Al2O3 recovery rate of 86.66%,SiO2 grade of 6.05%,Al to Si ratio of 8.53 could be obtained by closed-circuit test.The process structure and flotation reagent system are simple,and the flotation concentrate obtained can meet the requirements of alumina feeding in Bayer process.
    Experimental and Mechanism Research on Coagulation Settlement of Bauxite Ore Dressing Slime
    WEI Qiaoquan, CHENG Guanwen, ZHANG Yuling, ZHANG Zhenglin, HUANG Zhenyi, NONG Guowu
    2022, 51(07):  198-205. 
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    Bauxite ore dressing slime has the characteristics of small particles,negatively charged,fluid state and pH of weakly alkaline,which is difficult to settle naturally.In order to improve the coagulation and settlement effect of the slime,take the slime produced in the third stage of Pingguo Aluminum as the research object,investigate the coagulation and settling performance of polyaluminum aluminum chloride (PAC),polyaluminum ferric chloride (PFC) and polyacrylamide (PAM) on the slime,and study their mechanism of action.The results showed that the addition of PAC or PFC makes the pH of the slime system decrease,the conductivity increases,the Zeta potential of the slime particles increases,the particle size becomes smaller,and the sedimentation effect is poor.PAC or PFC is not suitable as a coagulant for the slime.Anionic polyacrylamide (APAM) mainly uses the polar group —CONH2 to hydrogen bond with the kaolinite and diaspore in the slime,the coagulation and sedimentation effect of the sludge is very obvious,the suitable dosage is 40～60 g/t,and the best dosage is 60 g/t.Non-ionic polyacrylamide (NPAM) mainly uses macromolecular chains to wrap around,and the coagulation and sedimentation effect of the sludge is obvious,the suitable dosage is 50~70 g/t,and the best dosage is 70 g/t.Cationic polyacrylamide (CPAM) mainly uses electrostatic adsorption to adsorb sludge particles,the coagulation and sedimentation effect of sludge is average,the suitable dosage is 60~80 g/t,and the best dosage is 80 g/t.
    Process Mineralogy Research of a High Sulfur and Low Grade Leadzinc Ore in Yunnan
    LÜ Chao, ZHANG Jing, YANG Lin, ZHANG Shuguang
    2022, 51(07):  206-211. 
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    A high sulfur lead-zinc deposit in Yunnan is a new orebody found in the lower part of the present mining area.In order to determine the reasonable development process,the process mineralogy of the lead-zinc deposit was studied by means of chemical analysis,microscope observation and MLA analysis.The results showed that: ① The valuable elements in the ores are mainly Pb,Zn,Fe and S,with contents of 3.20%,3.04%,26.36% and 30.84%,respectively,which belongs to high-sulfur and low-grade lead-zinc ore.② The ore composition is complex and consist of about 26 kinds of constituent minerals.The useful minerals are mainly pyrite,galena and marmatite,and the gangue minerals are mainly quartz,kaolinite and montmorillonite.③ The ore has dense disseminated structure,massive structure and vein-like structure,and the mineral mainly has inclusion structure,euhedral—semieuhedral—allohedral granular structure,opacities structure,internal cleavage structure and so on.④ The embedded characteristics of the main minerals are complex.Pyrite，galena and marmatite have close symbiosis relationship and are obviously wrapped each other.It is one of the main factors unfavorable to mineral separation that the distribution of minerals in ores is complicated and the content of useful minerals varies greatly.The recommended test flow is lead and sulfur iso-flotation + lead and sulfur separation—zinc and sulfur iso-flotation + zinc and sulfur separation.
    Effect of Grinding Process Parameters of Stirring Mill on Particle Size Characteristics of Products
    LI Guofeng, LI Chunnan, LI Yanfeng, LIU Liwei
    2022, 51(07):  212-218. 
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    The stirring mill has the characteristics of low energy consumption and high efficiency,and is expected to replace the traditional ball mill as the main equipment for iron ore fine grinding.In order to fully understand the influence of the grinding process parameters of the stirring mill on the particle size characteristics of the grinding products,the vertical spiral agitating mill machine is adopted for grinding tests of Gongchangling Concentrate regrinding feeding.The accumulation particle size and particle size distribution characteristics of grinding productions were detected through NKT6100-D laser particle size analyzer,and R—R granularity characteristic equation was applied for analyzing product granularity,so as to systematacially study the effect law of grinding process parameters on product size characteristics.The results showed that: under the conditions of medium ratio m（φ5 mm）∶m（φ3 mm）=2∶3,pulp concentration of 65%,feed to ball ratio of 0.6,filling rate of 70%,agitator speed of 450 r/min,the particle size of the products is fine and relatively uniform,in which the -0.043 mm particle content,the uniformity coefficient n and particle characteristic parameter b is 92.23%,1.177 7 and 0.031 4,respectivly.The research results have certain guiding significance for improving the qualified grain yield of grinding products.
    Study on Preparation and Preventing Leakage Mechanism of Dense Pre-hydrated Geosynthetic Clay Liner
    LIAO Min, GUAN Junfan, ZHENG Changwen, LI Yin, YANG Chengliang, DING Ding
    2022, 51(07):  219-224. 
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    In order to explore the effects of modification and mixing process on preventing leakage effect of dense pre-hydrated geosynthetic clay liner (DPH-GCL),infiltration test of the DPH-GCL in different preparation conditions were conducted with bentonite in Xiazijie street in Xinjiang as raw material,natural rain as the leakage of water medium.The appropriate preparation technology were determined,and preventing leakage mechanism were analyzed through the microscope,FTIR and XRD.The results showed that: ① The preventing leakage effect of C-type blanket,which was treated with modified and mixing combinated process,is the best.And the dosage scheme of modified reagent is 2 g amide polymer monomer Ⅰ,0.15 g initiator Ⅱ and 0.07 g initiator Ⅲ.The preventing leakage effect of B-type blanket treated only by modification is slightly worse,and the preventing leakage effect of A-type blanket without modification or mixing is the worst.② The suitable laminating time and pressure of three kinds of DPH-GCl are as follows: A-type blanket 5 min,5 MPa,B-type blanket 5 min,1 MPa,C-type blanket 1 min,1 MPa.③ Modification and mixing process can affect the bonding state of bentonite.After modification,the surface of bentonite particles is hydrophobic,and mixing enhances the hydration ability of bentonite.Bentonite can adsorb more water molecules and other ions in the solution,and the structure is more compact between the particles,and more stable.
    Application of Bifunctional Bacterial Flora in the Remediation of Butyl Xanthate and Cd Compound Contamination Soil in Metal Mining Areas
    LIN Hai, QIN Kangjia, DONG Yingbo, LI Bing, HOU Xuewen, TANG Yalu
    2022, 51(07):  225-232. 
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    Typical flotation chemicals butyl xanthate and heavy metal Cd in metal mining areas have the characteristics of easy accumulation and high migration,which lead to serious compound pollution of the soil around the mining area,but there is still a lack of efficient and green remediation technology for them.The effectiveness and soil microbial characteristics of the bifunctional flora SDMC in remediating the compound contamination soil with butyl xanthate and Cd were studied,and the results showed that the degradation rate of butyl xanthate and Cd mineralization rate could reach 63.34% and 71.83%,respectively,with good remediation effect.The soil microbial abundance,peroxidase,urease,sucrase activity,and AWCD increased by 9,1.22,5.92,1.15 and 1.18 times,respectively,compared with the non-remediated soil,indicating significant facilitation for soil microbial abundance,enzymatic and metabolic activity.The relative abundance of Sporosarcina,Hyphomicrobium and Pseudomonas,which play a role in degrading mineralized composite pollutants,increased by 43.75 percentage points,21.32 percentage points and 4.25 percentage points,respectively,indicating that SDMC has become the dominant bacteria for remediation,and this study provides a new method for remediation of butyl xanthate and Cd compound pollution soil in metal mining areas.
    The Performance and Influencing Factors of Degradation of Atrazine with Pyriteactivated Persulfate
    TU Zhihong, ZHOU Shu, WU Qi, XIAO Qiudong, SONG Bo, HE Huijun, LIU Chongmin, LIU Jie, DANG Zhi
    2022, 51(07):  233-239. 
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    Atrazine (ATZ) is one kind of common herbicide,which is widely used in agricultural.However,ATZ pose a threat to the ecological environment as well as human beings,due to its high toxicity and easy residue.It has become one of the highly detected pollutants in water.Natural pyrite (FeS2),which is environmentally friendly and widely available,was selected for the activation of sodium persulfate (PS) to degrade ATZ in water.The effects of eight common inorganic ions in natural water: NH4+,Cu2+,Mn2+,HCO3-,CO32-,H2PO4-,NO3-,Cl- and humic acid (HA) on the degradation of ATZ were investigated.Electron paramagnetic resonance (EPR) detection revealed that the activation of PS by pyrite was found to produce strong oxidizing radicals ·OH and SO4-·,which are the main cause of oxidative removal of ATZ.In addition,all eight inorganic ions had different degrees of inhibition and the three inorganic ions with the strongest inhibitory effect were CO32-,HCO3- and H2PO4- in descending order.The degradation rate of ATZ was slightly inhibited by HA.Common metal chelating agents such as EDTA,sodium citrate and oxalic acid significantly inhibited the degradation of ATZ due to their tendency to complex with Fe2+ produced by pyrite,which reduced the performance of pyrite activated PS,thus significantly inhibiting the degradation of ATZ.The use of pyrite to activate PS can realize the reuse of tailings,and the results of the study also can provide certain theoretical basis for the practical application of pyrite/PS to degrade ATZ.
    Comprehensive Utilization of Ultra-fine Metal Tailings and Its Problems and Countermeasures in the Application of Backfill Materials
    LIU Juanhong, ZHOU Zaibo
    2022, 51(07):  240-249. 
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    Based on the present situation of the application of finegrained tailings,combined with the big hidden danger of dam construction and storage of fine-grained tailings and the long-term goal of the 14th Five-year Plan,the comprehensive utilization of ultra-fine metal tailings and its problems and countermeasures in the application of backfill materials are discussed.In view of the low utilization rate of fine tailings in building materials,this paper expounds the methods of applying tailings to ecological cementitious materials,cementbased materials and concrete admixtures.In view of the problems of low thickening concentration of the fine-grained tailings,poor workability and mechanical of backfilling materials,the dense synergist,anti-bleeding material and crystal nuclear material are put forward,and the improvement effect of water reducing agent and microbeads on transport performance was studied.Meanwhile,their action mechanism is expounded.The deficiency in the research of metal tailings and the countermeasures of comprehensive utilization in the future are discussed.It provides technical and theoretical support for comprehensive utilization of fine-grained metal tailings and solving the problems existing in mine backfilling.
    Research Status and Prospect of the Microstructure and Properties of Unstable Substance in Steel Slag
    LI Enshuo, HU Chenguang, SU Hang, FU Jiawei
    2022, 51(07):  250-258. 
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    The unstable substances such as f-CaO,f-MgO and RO phases in steel slag are the main substances affecting its stability,which limits the large-scale resource utilization of steel slag.The direct research method indicated that a large number of f-CaO with spherical large size and concentrated distribution,exist in the medium or high basicity steel slag,and f-CaO content will be decreased and particle size will be reduced by reducing steel slag basicity and utilizing the treatment methods of gas quenching,hot stuffy and so on.The chemical synthesis research method incicated that Fe and Mn ions doping in CaO by chemical synthesis will increase the compact density of f-CaO and reduce its grain size,and Mn2+ has a stronger reduction effect on the f-CaO grain size.Further,status in the hydration characteristics of f-CaO in steel slag,the volume expansion rate of steel slag,and the corresponding mathematical model of f-CaO hydration expansion and the volume expansion evolution model of steel slag aggregate,and then the relationship between the autoclave pulverization rate of steel slag and the expansion force of single steel slag particle and so on are introduced.Then,the microstructure and hydration characteristics of f-MgO and RO phases in steel slag are reviewed,and the results indicated that the increase of steel slag basicity can promote the formation of magnesia,and will be beneficial to the MnO incorporating into MgO-FeO solid solution;besides,the hydration activity of RO phases is directly related to basicity and KM=nMgO/n(FeO+MnO),RO phases in steel slag are unstable,therefore,when KM≥1,RO phases may cause stability damage.In the end,the future research direction is pointed out.Such as,under the different basicity,treatment process,aging time and hydration degree of steel slag,the hydration rate of unstable substances in steel slag,ions transport process and the force conduction mechanism at the microstructure level;and then effect of hydration product ions of active minerals in steel slag on the hydration process of unstable substances and its relationship with expansion characteristics or long-term stability of steel slag;besides,the criteria standard and evaluation methods of steel slag stability and its relationship with long-term stability.
    Research Status and Prospects of Ceramsite Preparation Technology Using Selecting and Smelting Solid Waste
    ZHANG Yunhao, CHAI Yifan, AN Shengli, WU Jiayi, WANG Yici
    2022, 51(07):  259-266. 
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    With the continuous development of social economy and the continuous improvement of the industrial system,a large amount of selecting and smelting solid waste is generated during the development and utilization of mineral resources,accounting for more than 60% of industrial solid waste generated in China.One of the ways to realize the resource utilization of bulk selecting and smelting solid waste is to develop the technology of synergistic preparation of ceramsite from selecting and smelting solid waste.It can also obtain good economic benefits while protecting the environment.The paper systematically expounds the preparation process and principle of ceramsite,and introduces the main uses of different types of ceramsite products.In addition,the technical progress of preparing different types of ceramsite from selecting and smelting solid waste is discussed.Finally,prospects and suggestions for the recycling of selecting and smelting solid waste resources are put forward from three aspects: technology development,multi-source solid waste coprocessing,and the combination of production,education,research and application.