2019 Vol. 45, No. 7

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Research on mine flood identification and trend prediction method based on video image
SUN Jiping, JIN Chunhai, CAO Yuchao
2019, 45(7): 1-4. doi: 10.13272/j.issn.1671-251x.17459
<Abstract>(66) <HTML> (7) <PDF>(9)
Abstract:
The characteristics of mine flood video images were analyzed. The mine flood identification and trend prediction methods based on video images were proposed, including flood video dynamic identification, region segmentation, area estimation and trend prediction. The results were verified by experiments. The main conclusions are as follows: ① Both threshold pixel grayscale statistical method and pixel grayscale statistical method can monitor and identify floods. The threshold pixel grayscale statistical method not only can suppresses noise below the grayscale threshold and improve the accuracy of recognition, but also can reduce the pixel grayscale statistics, enhance contrast of a particular pixel grayscale range. ② Both the threshold segmentation method and the video differential segmentation method can segment the image of the flood area, the former is better overall and the latter is more detailed.③ The area of the water inrush area can be estimated and the trend can be forecast based on the segmented flood area image.
Research on fine design method of pre-drainage zoning borehole on high gas working face
YANG Liping
2019, 45(7): 5-9. doi: 10.13272/j.issn.1671-251x.2019010102
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Abstract:
At present, single borehole spacing is generally used to pre-drainage gas on high gas working face. But in the design of pre-drainage boreholes, influence of geological structure and other factors on the design of pre-drainage area are not considered, and relationship between extraction time and borehole spacing is also not accurately analyzed under condition of drainage standards. As a result, pre-drainage design of mining area on working face has not realized fine design of classification and zoning. For the above problems,taking 3603 working face of Huoerxinhe Coal Mine as research object, a fine design method of pre-drainage zoning borehole on high gas working face was proposed, which changes the extensive design mode of single borehole spacing from final line to open-off cut. Firstly, according to the geological conditions of the working face, the pre-drainage area is divided, and the extraction time of each area is determined by mining plan. Then, the pre-drainage hole spacing of each zoning area is determined according to the numerical relationship between the extraction time and the borehole spacing under different extraction rates, so as to realize the fine design of the pre-drainage area. The field test results show that compared with the original design, extraction time is reduced from 8 months to 6 months, and borehole engineering quantity is reduced from 319 440 m to 154 960 m; during observation period, the volume fraction of gas concentration on the whole working face does not exceed 0.58%, and there is no over-limit phenomenon.
Underground multi-sensor integrated navigation system
ZHANG Yuangang, LIU Kun, BAI Meng, PENG Jiguo
2019, 45(7): 10-16. doi: 10.13272/j.issn.1671-251x.17432
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Abstract:
In view of problems of high cost of high-precision inertial navigation of underground vehicle and large drift of low-cost MEMS inertial sensor, an underground multi-sensor integrated navigation system was proposed, which uses bluetooth ranging information, MEMS inertial sensor and vehicle odometer information for integrated navigation. The system uses Kalman filter technology to fuse multi-sensor data, combines Bluetooth ranging information to suppress MEMS inertial sensor drift, and improve positioning accuracy of inertial sensor in a period of time; Vehicle position is predicted by MEMS inertial sensor to effectively filter out Bluetooth signal of interference tags, so as to improves data reliability; Integration of odometer data can make the positioning result more stable and reliable. The test results show that the positioning error of every 10 m is less than 3.2 m under the condition that the underground Bluetooth tags are distributed 10 m apart, which can meet requirements of underground navigation.
Design of automatic monitoring and control device for double-gear roller crusher in fully mechanized working face
ZHU Jianfei, LEI Zhipeng, REN Xiyi, TIAN Muqin, SONG Jiancheng, MEN Rujia, XU Chunyu
2019, 45(7): 17-20. doi: 10.13272/j.issn.1671-251x.2019020007
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Abstract:
For problems of limited monitoring parameters, single control function and inability to linkage in existing crusher monitoring and control systems, a double-gear roller crusher monitoring and control system in fully mechanized working face was developed, and a design scheme of automatic monitoring and control device for double-gear roller crusher in the system was emphatically introduced. The device, which adopts STM32F103 microprocessor as control core, has three control modes namely centralized control, on-site control and overhaul, and can realize functions of interlocked start-stop control among conveyers of double-gear roller crusher, scraper conveyor, stage loader and so on, normal protections of motor and status monitoring data display. The field test result shows that the device has stable operation and accurate monitoring data, and can realize automatic interlocked start-stop control among double-gear roller crusher and other conveyors, which improves automation level of conveyors in fully mechanized working face.
Research on regional linkage and intelligent control system of mine fire wind-smoke flow
WANG Kai, HAO Haiqing, JIANG Shuguang, WU Zhengyan, SHAO Hao
2019, 45(7): 21-27. doi: 10.13272/j.issn.1671-251x.17440
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Abstract:
For existing status of low emergency decision-making and intelligent control level and inability to remotely control wind-smoke flow under abnormal conditions of mine ventilation, a regional linkage and intelligent control system of mine fire wind-smoke flow was designed. Combining with ventilation network structure, regional linkage control mechanism of wind-smoke flow during fire period was analyzed, which realized wind volume distribution according to needs of two parallel branches of smoke flowing zone and non-smoke flowing zone during fire period through setting smoke sensor, adjustable air doors and other ventilation equipments and remote control. Influence factors on intelligent control of mine fire wind-smoke flow were researched. An intelligent control model of wind-smoke flow during fire period was built through analyzing ventilation network structure before and after mine fire, and realization algorithm of visual function was also introduced. The system obtains real-time wind volume of each branch according to wind resistance, ventilation network structure and operation parameters of main ventilator during fire period, calculates ideal wind volume of key roadways through simulating fire process and sets a threshold value. When error between actual wind volume and the threshold value exceeds 10%, open degree of air door is controlled remotely, so as to realize optimal wind distribution. The application result shows that there is a perfect coupling among simulated calculation result of the system, displaying result on visual interface and field test result of wind volume in roadway.
Framework and key technologies of intelligent coal preparation plant
WANG Ranfeng, GAO Jianchuan, FU Xiang
2019, 45(7): 28-32. doi: 10.13272/j.issn.1671-251x.17465
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Abstract:
According to connotation of intelligent coal preparation plant, framework of intelligent coal preparation plant was introduced from aspects of Internet of things layer, control layer, management layer and decision-making layer. Key technologies adopted in construction of intelligent coal preparation plant were expounded emphatically, including intellectualization of dense medium separation process, flotation process, slime water health guarantee system and coal preparation manufacturing execution system, which laid technical foundation for development of coal preparation plant from automation and informatization to intelligence.
Design of intelligent control system for dense medium suspension density with wide domai
QIU Jiakai, WANG Ranfeng, FU Xiang
2019, 45(7): 33-37. doi: 10.13272/j.issn.1671-251x.17429
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Abstract:
In order to meet demand of adjusting dense medium suspension density in wide range due to change of raw coal quality, an intelligent control system for dense medium suspension density with wide domain was designed by using reverse split technology in dense medium separation process. BP neural network is used to establish liquid level prediction model of qualified medium barrel. Deviation between actual value and set value of suspension density, actual liquid level of qualified medium barrel and opening degree of shunt valve and water replenished valve are taken as input variables of the model, and predicted liquid level of qualified medium barrel is calculated through the model. According to liquid level deviation of qualified medium barrel and the density deviation, control mode switching of adding medium, steady state, density step up and density step down is realized through one-to-one multi-classification algorithm based on support vector machine. Opening degree of shunt valve, water replenished valve and water adding valve and opening time of thick medium pump and reverse shunt pump are automatically adjusted according to control mode, so as to realize wide range adjustment of density. Density fluctuation range is stable within ±0.005 g/cm3 and density adjustment time is short after application of the system.
Coal slime flotation foam image classification method based on semi-supervised clustering
CAO Wenyan, WANG Ranfeng, FAN Minqiang, FU Xiang, WANG Yulong
2019, 45(7): 38-42. doi: 10.13272/j.issn.1671-251x.17437
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Abstract:
In order to solve problems of subjectivity, hysteresis and extensiveness existed in reagent amount addition of coal slime flotation in coal preparation plant depended on manual intervention, a coal slime flotation foam image classification method based on semi-supervised clustering was proposed. Firstly, coal slime flotation foam images under known reagent-addition ratio and unknown reagent-addition ratio are collected, and the foam images are preprocessed to extract morphological characteristics such as bubble number, bubble area and bubble perimeter. Then, foam image morphological characteristic samples under known reagent-addition ratio are marked, while foam image morphological characteristic samples under unknown reagent-addition ratio are not marked, and the marked foam image morphological characteristic samples and the unmarked foam image morphological characteristic samples are mixed. Finally, semi-supervised clustering method based on Gaussian mixture model is used to cluster the mixed samples, so as to get various clusters, and information of the marked foam image morphological characteristic samples is mapped to the unmarked foam image morphological characteristic samples in various clusters. The application results show that the method can provide guidance for adjustment of reagent-addition amount in coal slime flotation production process, reduce consumption of reagent, and improve flotation automation level and economic benefit of coal preparation plant.
Design of intelligent ratio control system for raw coal in coal preparation plant
YUAN Pengtao, WANG Ranfeng, FU Xiang
2019, 45(7): 43-47. doi: 10.13272/j.issn.1671-251x.17427
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Abstract:
It is difficult to meet requirement of field production by theoretically calculating fixed ratio of raw coal in blended coal preparation process of coal preparation plant, and problems such as large randomness, low quality of clean coal and high labor intensity are existed in raw coal ratio adjustment according to manual experience. According to above problems, an intelligent ratio control system for raw coal in coal preparation plant was designed. Least squares support vector machine is used to establish a prediction model of intelligent raw coal ratio, and particle swarm optimization algorithm is adopted to optimize model parameters. The system takes measured ash content value of raw coal, measured sulfur content value of raw coal, average feed amount of raw coal per hour, separation density, measured ash content value of clean coal, ash content target value of clean coal, measured sulfur content value of clean coal and sulfur content target value of clean coal as input variables of the model, so as to obtain predicted value of raw coal ratio. Coal feed amount of coal feeder is measured by belt scale to calculate measured value of raw coal ratio, and deviation of raw coal ratio is obtained by comparing the measured value with the predicted value. PID controller controls frequency converter of the coal feeder according to the deviation amount to achieve accurate adjustment of raw coal ratio. The actual application results show that fluctuation range of ash and sulfur content of clean coal is significantly reduced and quality stability of clean coal is good. Difference between ash content of clean coal and ash content target value is controlled within ±0.2%, and difference between sulfur content of clean coal and sulfur content target value is controlled within ±0.15%, which verify quality improvement of clean coal.
Design of remote fault prediction system for coal preparation equipments
FU Xiang, WANG Ranfeng, PANG Liang
2019, 45(7): 48-52. doi: 10.13272/j.issn.1671-251x.17460
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In view of problems existing in current coal preparation equipments fault prediction, such as equipments monitoring data conversion method was not unified, single fault classification model cannot meet requirements of multiple fault types prediction, and the fault classification model cannot be updated and modified online. Based on remote operation and maintenance mode, a remote fault prediction system for coal preparation equipment was designed. By preprocessing sensor data of coal preparation equipment, full information is generated and input to various fault classification models. Overall fault index is weighted and fault prediction result is obtained through comprehensive decision. It can provide technical support for the whole life cycle management of intelligent coal preparation plant equipments. The application results verify effectiveness of the system.
Causes analysis of coal mine gas explosion accidents based on Bayesian network
ZHANG Ning, SHENG Wu
2019, 45(7): 53-58. doi: 10.13272/j.issn.1671-251x.2019010049
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Abstract:
Existing causes analysis of coal mine accidents is mainly based on unilateral factor, ignoring correlation and integrity of four factors of human, machine, environment and management, and the types of accidents involved are relatively generalized. In view of the above problems, factors inducing coal mine gas explosion accident are selected from four aspects of human, machine, environment and management, and correlation analysis is used to select variables with strong correlation. Bayesian network model of coal mine gas explosion causes is constructed by GeNie, and reliability and accuracy of the model are verified by cross-validation method. The parameters of each node in the model are analyzed by Bayesian network parameter learning and sensitivity analysis. The conditional probability distribution and posterior of the relevant nodes under different conditions are calculated to extract key factors inducing gas explosion accidents in coal mines. The analysis results show that insufficient ventilation will greatly increase the possibility of excessive gas content in coal seams, unqualified employee training is the main cause of gas missed inspection; in the case of coal mine gas explosion accidents has happened, the most likely cause is excessive gas content, and followed by missed gas inspection; the most critical factors leading to coal mine gas explosion accidents are excessive gas content, missed gas inspection, unstable roof, and unsound laws and regulations.
Numerical simulation of flame propagation characteristics of coal-dust explosion in horizontal pipeline space
LIU Tianqi
2019, 45(7): 59-65. doi: 10.13272/j.issn.1671-251x.2019020008
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In order to research flame propagation characteristics of coal-dust explosion in horizontal pipeline space, based on coal-dust explosion experimental equipment with horizontal glass pipeline, mathematical models of flame propagation characteristics of coal-dust explosion and geometry model of horizontal pipeline were constructed taking lignite as research object, and numerical simulation method was used to research flame propagation characteristics of coal-dust explosion along pipeline length direction (z direction) in horizontal pipeline space at different time and flame temperature propagation characteristics along z direction and in different cross-sections when explosion reaction was sufficient. The research results show: ① The maximum error between simulated value of explosion flame propagation distance and the measured one is 0.09 m at different time, and the minimum error is 0.01 m, which verifies feasibility of the numerical simulation method. ② When coal-dust explosion reaction is sufficient, the horizontal pipeline space can be divided into initial dusting zone of z=0-0.1 m, high temperature ignition zone of z=0.1-0.3 m, temperature jump zone of z=0.3-0.56 m, high temperature core zone of z=0.56-0.86 m and high temperature diffusion zone of z=0.86-1.4 m. ③When coal-dust explosion reaction is sufficient, in cross-section at z=0.2 m, the closer the location is to circle center, the lower the temperature at the location is, which indicates that the region is explosion source, but it is not core area of explosive heat release. There are narrow annular low temperature zones of about 500 K in the outermost peripheral wall region of cross-sections at z=0.2 m and z=0.4 m, which are due to constant pipeline wall temperature of 300 K.In cross-section at z=0.86-1.4 m, the closer the location is to circle center, the higher the temperature at the location is, and the farther the cross-section is away from high temperature core zone, the lower temperature is. The numerical simulation results are consistent with actual flame propagation.
Design of electromechanical and hydraulic integration virtual simulation platform for shearer mining operatio
WANG Xiao
2019, 45(7): 66-72. doi: 10.13272/j.issn.1671-251x.2019030029
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In view of problems that current virtual simulation of shearer mining operation are mostly based on preset trajectories, seldom consider impact of coal seam loading and can not show dynamic process of shearer operation, three-dimensional simulation of shearer mining operation, electrical and hydraulic system simulation, and specific working conditions are combined to design electromechanical and hydraulic integration virtual simulation platform for shearer mining operation using LabVIEW and Simulink interactive program development technology. Under condition of sudden change of coal seam load, the drum speed and traction speed are automatically adjusted to reduce the drum load through the control of electric speed control system and hydraulic height adjusting system. The test results show that the platform can accurately and visually display dynamic process of shearer operation and control process under condition of sudden change of coal seam load. In the shearer operation training, the platform can help shearer operator to master shearer control strategy under condition of sudden change of coal seam load to avoid actual operation risk.
Application research on improved active disturbance rejection control in air speed regulation of local ventilator
OUYANG Mingsan, WU Guofang
2019, 45(7): 73-79. doi: 10.13272/j.issn.1671-251x.2019030001
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In view of the problem of strong fluctuation of control signal in the existing active disturbance rejection control algorithm for air speed regulation of mine local ventilator, which causes shock and vibration of frequency converter and motor, an improved active disturbance rejection control algorithm was proposed. The algorithm uses an improved method combining the arctangent function and the power function, the arctangent function enhances the linearity of control algorithm, ensures better smoothness at the origin of the function, and the power function guarantees the tracking speed of the control algorithm, and speed up the convergence of the control algorithm. The improved active disturbance rejection control algorithm is applied to the air speed regulation of mine local ventilator. The voltage signal processed by the control algorithm is used as the input signal of inverter of the local ventilator, and output frequency signal changes the speed of the asynchronous motor, so as to realize the dynamic adjustment of air speed of the local ventilator.The simulation results show that the improved active disturbance rejection control algorithm has obvious improvement in control speed and anti-interference ability compared with the existing PID control algorithm and active disturbance rejection control algorithm, which can adjust the air speed of local ventilator rapidly and stably.
Underground adaptive positioning algorithm based on SAPSO-BP neural network
MO Shupei, TANG Jin, DU Yongwan, CHEN Ming
2019, 45(7): 80-85. doi: 10.13272/j.issn.1671-251x.2019010066
<Abstract>(79) <HTML> (6) <PDF>(10)
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In view of problems of slow convergence, easy to form local extremum and large positioning error in strong time-varying electromagnetic environment of underground positioning algorithms based on traditional BP neural network, an underground adaptive positioning algorithm based on simulated annealing and particle swarm optimization and BP neural network (SAPSO-BP) was proposed. SAPSO algorithm is used to optimize the initial weight and threshold of BP neural network to accelerate training convergence speed and make it reach the global optimum. The target point RSSI value is collected by wireless calibrator installed in underground roadway and real-time calibrated by adaptive dynamic calibration method, in order to reduce influence of time-varying electromagnetic environment on positioning accuracy. Finally, the SAPSO-BP neural network is used to estimate position coordinates of target point. The experimental results show that confidence probability of positioning error within 2 m of the proposed algorithm is 77.54%, average error is 1.53 m, the positioning performance is better than uncalibrated SAPSO-BP neural network algorithm, PSO-BP neural network algorithm and BP neural network algorithm.
Research on dynamic mechanical properties and transient magnetic field characteristics of composite coal and rock mass
GOU Yong, WANG Ke
2019, 45(7): 86-91. doi: 10.13272/j.issn.1671-251x.2019010099
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Coal and gas outburst is the comprehensive mechanics result of roof-coal body-floor. It is difficult to fully reveal mechanism of coal and gas outburst by simply studying mechanical characteristics of coal or rock. In order to reveal dynamic mechanical properties and transient magnetic field signal characteristics of composite coal and rock mass, the dynamic mechanical properties of composite coal and rock mass were studied by Hopkinson pressure bar experiment system, and the signal characteristics of transient magnetic field of composite coal and rock mass were analyzed during dynamic failure process. The experiment results show that after composite coal and rock is impacted, the rock fragmentation is large, the coal fragmentation is small, and the coal with low strength has good stress attenuation and wave clipping effect on the composite sample. The stress attenuation decreases to 1/5 of the original after the stress wave passes through the composite sample. The attenuation and weakening effect of the composite coal and rock mass on the stress wave mainly depends on the microstructure of the coal body, and the microstructure of the coal body makes the plastic deformation of coal body increase and elastic modulus decrease gradually after being subjected to impact load. Compared with the composite samples, the single sample shows obvious brittle failure characteristics. The average strain rate, maximum strain rate, fracture stress limit value and failure strain of the composite samples have certain correlation with the amplitude of transient magnetic signals. With increase of the impact speed, average strain rate, maximum strain rate, fracture stress limit value of the composite samples, the amplitude of transient magnetic signals generated by the composite sample increases gradually, and the magnitude of damage strain and the amplitude of transient magnetic signals show a negative correlation, but the correlation between them is not strong and the discrete type is large.
Research on pore structure characteristics of gas coal in Fukang mining area
WANG Cuixia, LIU Wei, LIU Jiku
2019, 45(7): 92-96. doi: 10.13272/j.issn.1671-251x.2019010062
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In order to study gas storage and extraction feasibility in Fukang mining area, mercury intrusion method and liquid nitrogen adsorption method in low temperature were used to compare and analyze pore structure parameters and distribution characteristics of coal under different conditions.The analysis results show that large pores and micropores in coal samples account for a large proportion, the pores with large pore diameter are composed of cylindrical pores with open ends and parallel plate holes with four open sides, which has good openness and is beneficial to gas drainage and utilization;The total pore volume of gas coal samples is larger than that of high metamorphism coal samples, pore structure is conducive to the occurrence and release of gas; The specific surface area of gas coal pores is smaller than that of high metamorphic coal samples, but the specific surface area of small pores account for a large proportion in the pore structure, and small holes can provide large space for gas adsorption, so the gas coal in Fukang mining area also has certain gas adsorption capacity, coal seam gas can be extracted and utilized.
Application research on technology of non-pillar gob-side entry retainingformed by roof cutting and pressure release in high gas coal seam
WANG Xiaolong, DONG Zhiyong
2019, 45(7): 97-101. doi: 10.13272/j.issn.1671-251x.17387
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In view of problems of high cost, complex construction technology and slow construction progress existed in traditional gob-side entry retaining technology which mostly adopts method of filling at the side of goaf to protect the roadway, the technology of non-pillar gob-side entry retaining formed by roof cutting and pressure release in high gas coal seam was studied taking 62711 working face in high gas coal seam of Duerping Coal Mine as research object. The technical process of the technology of non-pillar gob-side entry retaining formed by roof cutting and pressure release was analyzed in detail from the aspects of key parameters design of pre-splitting and cutting joints, entry retaining reinforcement and support, gangue retaining support in goaf, gas safety management method, and rock pressure monitoring was carried out on the working face. The analysis results show that application of the technology of non-pillar gob-side entry retaining formed by roof cutting and pressure release in Duerping Coal Mine realizes pressure release effect on the stope, and successfully keep track transportation roadway of 62711 working face as the next adjacent working face belt transportation roadway, which obviously improves coal recovery rate, relieve the tension between coal mining and tunneling, and avoids mine disasters caused by residual coal pillars. In addition, the use of "Y" type ventilation mode effectively solves the problem of gas accumulation in the upper corner of the working face.
Research on distribution law of dominant gas extraction area of high-level borehole
HU Binqiang
2019, 45(7): 102-108. doi: 10.13272/j.issn.1671-251x.2019010081
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In order to improve efficiency of gas extraction of high-level boreholes in coal mines, the concept of dominant gas extraction area of high-level boreholes was put forward based on theory of overburden strata mining failure and characteristics of gas migration, that is, the area between caving zone and fracture zone that can guarantee stable and efficient extraction effect.Taking Xiagou Coal Mine as research object, numerical simulation and field verification methods were used to determine dominant gas extraction area of high-level boreholes in ZF302 coal face, and its distribution law was studied. The research results show that the dominant gas extraction area of high-level boreholes in ZF302 coal face is located in the area with vertical height of roof of 33-57 m. In the dominant gas extraction area, the gas extraction volume of single hole shows a trend of first increasing, then becoming stable, and then decreasing. When the height of the final hole is located in the area of 70-57 m, the gas extraction volume of single hole gradually increases from 0.66 m3 /min to 1.48 m3 /min, and then enters the stable area within the height of 57-34 m, and the gas extraction volume of single hole always keeps above 1.0 m3 /min.When the position of the final hole of high-level boreholes is located in the vertical height of 55-65 m, the extraction time of dominant gas extraction area is the longest and the gas extraction quantity of single hole is the highest. After optimization of drilling parameters, the number of boreholes in the drilling field is reduced from 28 to 18, a decrease of 35.71%. The daily extraction volume increases from 26 008.75 m3 to 31 046.4 m3, increasing by 19.37%.

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