In order to improve the efficiency of coal mining, considering chamber filling design of narrow coal pillar of roadway in gob entry driving, take the geological conditions of Jingfang Mine Area as the background, the reasonable width of narrow coal pillar and stress distributed characteristic of water cavern roof under goaf were analyzed by numerical simulation of FLAC3D. The technology of goaf filling was proposed. Surrounding rock support control scheme on narrow coal pillar was formulated. The in-situ monitoring was made on the working load of bolt and crack development characteristics of surrounding rock in gob entry driving. The research results show that: the 6m narrow coal pillar surrounding rock has less crack development, good integrity of surrounding rock, which can meet the needs of safety production, but the surrounding rock crack development in the water cavern area of goaf needs support measures. The feasibility of excavating and filling technology was verified. The deformation of roadway surrounding rock and the working load of bolt were controlled with the use of filling technology. The research solves the technical problem of controlling the surrounding rock passing through the chamber of goaf with narrow coal pillars, which produce greatly economic benefits and provide reference experience for similar projects.

The width of section coal pillar directly affects the stability of coal pillar, the difficulty of roadway maintenance and the recovery rate of working face. Aiming at the problems of resource loss and roadway maintenance caused by unreasonable coal pillar size in fully-mechanized caving mining face, taking the geological conditions and mining parameters of a fully mechanized top coal caving face in a mine in Northern Shaanxi as the research object, using the methods of physical simulation, FLAC3D numerical calculation and theoretical analysis, the ground pressure behavior law of fully-mechanized caving mining face, the stability of coal pillar in different width sections and the distribution form of dynamic stress are studied, The deformation and failure characteristics, ultimate strength and instability probability of section coal pillar with different width height ratio are mastered. The results show that the stability of coal pillar has obvious width height ratio effect, the maximum stress and plastic zone width of coal pillar are negatively correlated with the width height ratio of section coal pillar, and the core area ratio of coal pillar is positively correlated with the width height ratio; When the width of section coal pillar is greater than 18m, the nuclear area rate is greater than 65%, the safety factor of coal pillar is greater than 1.1, the probability of instability is less than 45%, and the coal pillar is relatively stable; When the width of coal pillar is less than 18m, the nuclear area rate is less than 65%, the safety factor of coal pillar is less than 1.0, the probability of coal pillar instability is greater than 60%, and the coal pillar is easy to instability. It has been verified in practice in 406 working face of the mine that there is only local slope phenomenon in coal pillar slope and mining slope, and the roadway deformation is small, which ensures the safe mining of the working face. The size of coal pillar can be used as a reference for the study of similar mining conditions.

In order to solve the problem of gangue discharge on the ground in the future of Jingu Coal Mine and realize the safe and green mining of the coal mine, the technology of gangue backfilling mining is proposed, and the gangue backfilling mining in the fully mechanized mining face of Jingu Coal Mine is designed from four aspects: the processing and transportation of gangue from the ground, the transportation of gangue underground, the mining and filling of gangue in the working face, and the retaining of roadway along the goaf. The results show that the gangue backfilling mining in the fully mechanized mining face of Jingu Coal Mine can not only meet the control requirements of rock stratum deformation and surface movement, but also comprehensively utilize industrial wastes, avoiding the cost of large-scale land acquisition and environmental treatment.

Aiming at the problems of difficult operation in confined space and poor cooperative working ability of multiple machines in thin coal seam fully mechanized mining face,intelligent system is built. A shearer positioning method based on multi-signal fusion of infrared, radio frequency and shaft encoder is proposed., the working face straightening technology based on inertial navigation and supplemented by video signal is established. Intelligent support systems such as emulsion pump station intelligent system, spray intelligent system, three machines and belt machine fault diagnosis system are built. An integrated control platform is set up in the crossheading centralized control center, based on advanced and reliable electro-hydraulic control system access to each subsystem through multiple data interfaces, use industrial bus network as the channel, realize underground centralized control and ground remote control. The industrial operation shows that the system can realize the automatic production of the whole process of coal mining in the working face, the production team of the coal mining team at the working face has been reduced by 5 people, the number of personnel has been reduced by 30%, the average daily advance is 6 knives, and the production efficiency has been increased by 102%.

Combined with the analysis and comparison of foundation schemes for a 100 meter commercial and residential building in the northern suburbs of Xi'an, in view of the relatively thick and dense sand layer about 20m below the surface of the second terrace of the Weihe River, the open PHC short pipe pile foundation reinforcement method of hammer driven pile is selected by using the effect of soil plug at the pile end to improve the vertical compressive bearing capacity of the pile, which can successfully drive the pile and save the construction period and project cost. According to the comparative analysis of the static load test results, under the reasonable pile driving conditions, With the increase of pile top load, when the pile end is squeezed into the dense sand layer for about 5.0~6.0d, the soil plug effect of phc400 (AB) -95 open short pipe pile is strong, and the ultimate end resistance in the sand layer is significantly increased. It is proposed that when PHC open pipe pile takes the dense sand layer as the pile end bearing layer, the modified nominal equivalent ultimate end resistance under the soil plug effect can be considered, and the correction coefficient is 1.8~2.3. The observation results of building settlement are consistent with the previous analysis and prediction, which provides a reference for the foundation design of similar sites.

In order to solve the safety problem of large section abandoned roadway in fully mechanized mining face, the research on abandoned roadway supporting technology at home and abroad was carried out. The technical problems caused by jump mining, filling and conventional reinforcement support were analyzed. The deformation and instability of surrounding rock and pumping support mechanism of abandoned roadways were analyzed.The treatment combining pumping support and anchor cable support was put forward. Through numerical simulation and theoretical calculation, the design of anchor cable &W steel belt &wall net & pumping pillar around goaf is determined. Wulanmulun colliery industrial test showed that, both working face and roadways floor heave didn’t occur during cutting through abandoned roadways. Within a total of 10 measuring points arranged, the maximum subsidence is less than 12cm. When pumping pillar has been cut more than 2/3 diameter, buckling collapse occurred. It shows that the pumping pillar has the characteristics of anti-dynamic load, large deformation, good stability and easy cutting, which can meet the needs of surrounding rock control of large section abandoned roadway.

In order to obtain the main controlling factors affecting the stability of the surrounding rock structure of the gob-side roadway in the thick coal seam，taking the project overview of the 1014 working face of Yushuquan Coal Mine as the background，the discrete element program UDEC was used to simulate and analyze the roadway burial depth，gob-side coal pillar width and lateral direction. The rock beam cantilever length，the basic top breaking depth，and the degree of coal integrity affect the structural stability of the surrounding rock in the gob-side roadway in thick coal seams. The results show that the depth of the roadway，the width of gob pillar，the length of the lateral rock beam cantilever，the fracture depth of the main roof，and the integrity of the coal body all have a certain impact on the stability of gob-side roadway，the degree of influence from large to small：the integrity of the coal body>the depth of the roadway>the width of gob pillar>the length of the lateral rock beam cantilever>the fracture depth of the main roof．

Taking the 20104 working face of Wangjialing coal mine of Jinneng holding coal industry group as the engineering background, through the combination of on-site ground pressure monitoring, refined numerical simulation, mechanical mechanism analysis and on-site industrial test, the 20102 return air roadway driving along the gob during the mining of 20104 working face is studied. The results show that: 20102 air return drift was affected by mining disturbance of adjacent 20104 working face. The deformation and failure of surrounding rock can be divided into three stages: initial slow growth stage (20104 advanced testing station 125 m range), rapid and continuous growth stage (20104 advanced testing station 125 m range to 100 m lag) and accelerated growth stage (20104 delayed testing station 100~200 m range); the variation law of the support stress in the two sides of the roadway obtained by numerical simulation confirms the accuracy of the field ground pressure monitoring results. At the same time, the numerical simulation results also point out that the pre splitting treatment of the roof rock can significantly reduce the peak value of the support stress in the two sides of the surrounding rock of the roadway along the gob, so as to reduce the damage degree and convergence of the surrounding rock of the roadway; according to the on-site engineering geological conditions, the pre-splitting method of roof and rock stratum is determined and the on-site industrial test is carried out. The cumulative convergence of surrounding rock roof and floor and two sides are reduced by 506 mm and 326 mm respectively. The deformation of surrounding rock in 20102 return air drift has been controlled to a certain extent. The research results provide guidance and reference for roadway excavation along gob under similar engineering geological conditions.

The support form of "single/hydraulic support" in advance section of two roadway in longwall coal face does not match the development trend of automation and intelligence of the working face. The active advance support technology provides a feasible technical path to realize the dehumanization of advance section of two roadway. Aiming at the problems of high labor intensity and low mining efficiency of passive advanced support in thick and hard roof working face of Qiwu Coal Mine, the field test of roadway surrounding rock structure was carried out with 217 working face transport lane as the research object, and the crack development law of roadway roof in 3 upper coal seam was revealed, and the advanced abutments pressure was calculated according to the mechanical model of roadway surrounding rock. Based on this, the "regional differentiation" active advanced support scheme was proposed, and the active advanced support scheme was checked at each stage through the support strength checking formula, which met the requirements of advanced support. The industrial test shows that the maximum relative movement of roof and floor is 50 mm, and the maximum relative movement of two sides is 56 mm. There is no obvious breakage or separation in the roof, and only a small amount of 0.01 m transverse cracks appear in the shallow part. Therefore, active forepole can completely meet the needs of the abutment pressure area supporting quality, the stability of surrounding rock is stronger, better able to control the surrounding rock fracture, and improved the labor environment, reduce the security hidden danger, enrich the active forepole project cases, for the similar geological conditions of extraction roadway active support to provide the reference in advance.

In view of the problems of difficult drilling slag discharge, low drilling efficiency and difficulty in forming holes in the construction of hydrodynamic directional drilling in broken soft coal seams, analysis of the instability characteristics of boreholes in broken soft coal seams. According to the larger stirring volume of coal slag per unit of the drill pipe, the more conducive to spiral slag discharge, a composite slag discharge method with high spiral mechanical slag discharge as the main and hydraulic slag discharge as the auxiliary is proposed. The Φ98mm welded spiral drill pipe is developed, and the structural characteristics and slag discharge capacity of three specifications of spiral drill pipes are compared and analyzed.A field tests were carried out in Wangpo Mine and four boreholes with depth over 300 m were constructed.The test results showed that the drilling efficiency of Φ98 mm welded auger rods could reach 30.6 m/shift, and the amount of slag returned per unit footage can reach 270 kg/m, and the drilling efficiency and slag discharge capacity are more than doubled compared with Φ89 mm auger pipe and Φ89 mm triangular auger pipe, formation of directional drilling equipment and technology suitable for high-efficiency slag discharge in crushed and soft coal seams.

In view of the fact that the current advanced drilling hydraulic fracturing cutting roof pressure relief method commonly used in coal mine can not deal with the hard composite roof with high thickness well, based on the multi-point drag-type open-hole stage fracturing complete set equipment in coal mine, the technology of weakening and defusing the danger in the fractured zone of the ultra-long drilling hole with hard composite roof is formed. Through the implementation of "high-low" directional long drilling segmented hydraulic fracturing, the basic roof can collapse and contact the gangue in advance, form effective support to the working face roof, and avoid the occurrence of rock burst. In addition, in Ordos mining area, the method of directional long drilling segmented fracturing in underground coal mine is adopted to carry out advanced regional weakening treatment, and the engineering practice proves that the prevention and control effect is remarkable: In the fracturing process, a three-dimensional fracture network can be formed in the rock mass to communicate macro and micro fractures, and the overburden rock can fully collapse, so that it can reach the full mining state faster, and reduce the risk of dynamic load on the working face caused by sudden instability of overburden rock roof after reaching the limit span. It greatly reduces the energy release intensity, periodic pressure intensity and the leading stress peak value in the coal body, and effectively slows down the roadway deformation.

In order to reduce the possible impact risk of hard roof during mining in Mengcun coal mine, the surface horizontal well and staged fracturing mature technology are applied to the prevention and control of mine rock burst for the first time. By reasonably selecting the fracturing target horizon, optimizing the fracturing process, implementing two surface L-shaped horizontal wells on the hard roof, and carrying out staged fracturing technology transformation, forming effective artificial fractures, breaking the coal seam roof and releasing the formation stress. At the same time, the method of combining the ground microseismic real-time fracture monitoring system of the whole well section with the downhole microseismic monitoring and evaluation system is used to effectively monitor the expansion range of the segmented fracture of the surface horizontal well. This technology realizes the weakening of the overlying hard roof area within the working face, and reduces the possible rockburst risk caused by the collapse of a large area of hard roof during the mining of the coal face.

In order to solve the problem of gas overrun in the upper corner or return air flow caused by a large amount of gas flowing into the goaf of the working face due to pressure relief after the mining of the upper protective layer under the condition of short-range high gas coal seam group, the 03X00 working face of Dongyu mine in Xishan coalfield of Xifenliu mining area is taken as the research object, The stress distribution of the protected layer after the mining of the upper protective layer is analyzed by using the method of theoretical calculation and numerical simulation, and the law of pressure relief gas migration is obtained, so as to determine the vas treatment technical scheme of "one working face and three lanes" arrangement of the working face and pre drainage of the overlying coal seam + pressure relief drainage of the underlying coal seam. The field results show that after the mining of 03X00 working face, the No. 2 coal seam is completely within the pressure relief range, the pressure relief rate of the protected No. 2 coal seam reaches 92%, the gas content and gas pressure of the coal seam decrease significantly, the reduction rate reaches more than 60%, the pressure relief gas extraction concentration increases by 60%, the pure quantity increases by nearly one time, and the maximum gas concentration of the return air flow of the track chute and the bottom drainage roadway is 0.3%, The maximum gas concentration in the upper corner is 0.4%, which avoids gas overrun, ensures mine safety production, and provides scientific support for coordinated mining of coal and gas.

Aimed at the main problems of independent operation of Yicheng Coal preparation Plant, with the help of the existing trusteeship operation mode, the washing problem of the plant is solved from two aspects of technology and management. After the trusteeship operation mode is realized, the ash content of cleaned coal on screen is reduced to 9.67%, the clean rate of gangue is reduced to 1%, the clean rate of medium coal is reduced to 5%, and the recovery rate is increased by about 3%. Referring to the design capacity of coal preparation plant of 240Mt/a, the raw coal can be increased by 72,000 t/a, the water content of cleaned coal is reduced by 3.68%, and the transportation cost is improved. The washing capacity of raw coal per hour increased to 380t/h, and the failure rate of equipment decreased from 2.5h to 0.5h, basically realizing the modern production of Yicheng Coal preparation Plant, thus verifying the feasibility of the managed operation mode of Yicheng Coal preparation Plant.

In order to solve the problem of surrounding rock control of open - cutting entry retaining near goaf, this paper studies the supporting system and key technologies of pressure relief through theoretical analysis and field test. The comprehensive surrounding rock control technology system and process of roof pressure relief, surrounding rock active support and high strength passive reinforcement are proposed. The ' directional pre-splitting + loose blasting ' combined pressure relief technology is implemented for thick hard roof. Through parameter optimization design, 90 % of the single fracture surface and the roof of the goaf behind the hydraulic supports is timely caving, and the surrounding rock structure is improved. After mining, the support of ' the coal side reinforcement anchor cable + roof constant resistance anchor cable + gangue sealing support+ alternating wooden stack + hydraulic single shed ' is adopted in time, and the deformation of surrounding rock is controlled by active and passive support reinforcement measures. When the working face is mined at 280 m, the surrounding rock of the open - cutting retaining roadway is stable, the displacement of the two sides is less than 300 mm, and the displacement of the roof and floor based on the floor heave is less than 500 mm. The surrounding rock control effect of the open - cutting retaining roadway meets the production demand.

Abstract: Aiming at the problems of serious deformation and damage of surrounding rock and poor supporting effect in soft gently inclined coal seam roadway with thick hard roof. The paper adopts the method of combining on-site measurement, mechanical modeling, numerical simulation and field test, the deformation and failure characteristics of the surrounding rock in soft gently inclined coal seam roadway with thick hard roof is mastered, the deformation and failure mechanism of the surrounding rock in the roadway is revealed, and the change law of the plastic zone of the surrounding rock of the roadway under the influence of different factors is analyzed, a joint supporting plan of “reaming grouting of the bottom bolt hole + grouting of the two sides + asymmetric bolting (cable) with wire mesh” is proposed. The research shows that the deformation and failure of the surrounding rock of roadway is obviously asymmetric, and the approximate location of the deformation and failure of the surrounding rock of roadway is obtained. Increasing the thickness of the hard roof and increasing the C (φ) value of the coal sides can effectively reduce the asymmetric deformation and failure range of the surrounding rock of the roadway; The joint supporting plan of “reaming grouting of the bottom bolt hole + grouting of the two sides + asymmetric bolting (cable) with wire mesh” can effectively control the deformation of surrounding rock of such roadway.

Due to the reasons of preferential exploitation of protective layer, production water and karst fissure water in coal seam geology, a large amount of water is pooled in the goaf of the overlying coal seam in the mining process of the close coal seam, while the mining of the underlying coal seam will perform secondary pressure relief on the overlying rock. Lead to overburden rock under the condition of hydraulic fracture cross fall pattern, to strength, to step distance is different from the characteristic parameters such as pressure is not affected by hydraulic condition of working face, therefore in this paper, the theoretical analysis, analog simulation and numerical simulation study the research method of combining under the influence of hydraulic conditions was analyzed v in the process of the coal bed mining strata fracture dynamic evolution rule, The influence of hydraulic conditions on overburden straddling and mining-induced fracture development is pointed out. The results showed that: Upper strata across the fall the process of mining face and evolution law of mining-induced fractures is not affected by hydraulic conditions, but under the influence of hydraulic conditions first weighting interval of overburden rock decreases 10 m, the periodic weighting interval decreases 3 m, and the mining face the same distance influenced by hydraulic conditions of caving of working surface rock strength is relatively severe, Its displacement and compressive strength are also relatively large, so the support strength or density should be increased when supporting the overburden of working face.

In order to systematically study the relationship between groundwater replenishment and discharge in Anxin Coalfield, and to master the law of groundwater seepage in Anxin Coalfield, a conceptual model of hydrogeology was established by means of numerical simulation, the stratigraphic structure and the boundary conditions of the model were generalized, and the evolution law of the seepage field of each aquifer in the upper part of the coal seam was analyzed. The results show that: The second aquifer in Anxin coalfield has a high confined water head, and the second aquifer of Anxin coalfield has a high confined water head in Heihe River Valley. With the exploitation of the mine and surrounding mines, it has a certain drainage effect on the groundwater, and its water head has a certain attenuation. The sandstone composite confined aquifer on the top of the No.4 coal roof has a larger head value, but the water richness of the composite aquifer is significantly different in both plane and vertical directions, and the recharge conditions and water richness are poor.The No.4 coal roof sandstone composite confined aquifer has little effect on the mining in Daliu coal mine, but there is a hidden danger of water inrush to the No.4 coal in Xinbai coal mine. Through the global sensitivity analysis, it is concluded that the total sensitivity of the model is small, and the results are relatively stable, which verifies the accuracy of the model.

To study the influence of slope inflection point position on slope stability, strip mechanical models of slopes with different inflection point positions were established based on the simplified Bishop method. The 117 slope models with different curvature and inflection point positions were simulated and analyzed by FLAC3D. The results show that the change of the slope inflection point position will affect the gravity of the strips in the slope sliding mass, and then affect the stability of the slope. Different trends in the safety factor of the slope with different shapes with the movement of the inflection point. The safety factor decreases linearly with the downward movement of the inflection point for interior polyline-shaped slopes and increases linearly with the downward movement of the inflection point for exterior polyline-shaped slopes. The safety factor of the slope decreases as the absolute value of slope curvature increases. The inflection point position effect of slope stability can be applied to the steep end-slope mining of open-pit coal mines, which can reduce the stripping ratio and improve the resource recovery rate.

Under the action of long-term heavy load and alternating load, the idler shaft of the shearer is prone to cracks at the root of the shaft shoulder, which affects the integrity of the structure. In order to quantitatively analyze the root cracks of the idler shaft, a two-dimensional finite element model for ultrasonic testing of the idler shaft is established to clarify the propagation process of the ultrasonic wave in the idler shaft and the law of its interaction with defects. An ultrasonic testing experimental platform was built to verify the validity of the finite element numerical model. The time-domain waveform and spectrum amplitude changes when the shoulder echo overlaps with the crack echoes of different depths are analyzed. The results show that with the increase of the crack depth, the echo amplitude at the shaft shoulder increases; from the spectrogram It can be seen that as the depth of the crack at the root of the shaft shoulder increases, the echo bandwidth becomes wider, and the spectral amplitude increases with the increase of the crack depth. The least square method is used to fit the amplitude, and the fitting function of the spectrum amplitude and the crack depth is obtained to realize the quantitative analysis of the crack depth at the root of the shoulder.

In order to locate underground operators and various types of underground equipment in real time, find abnormal situations in time and take measures to prevent safety accidents, in view of the complex underground scenes of coal mines, the existence of a large number of small targets and the large-scale changes of tracking targets, an algorithm for tracking moving objects based on deep learning is proposed. Based on the Siamese tracking algorithms, a local-global matching network is proposed to improve the tracking accuracy of the algorithm in different scenarios, and an anchor-free classification-regression network is designed to reduce the computational complexity of the model. In order to verify the performance of the model, 40 video sequences were collected for testing. The test results show that the proposed algorithm can effectively improve the tracking performance of small targets, targets with large scale changes and targets in complex backgrounds, which is better than commonly used object tracking algorithms and achieves a real-time running speed of 57fps.

In order to analyze the safety of the anti-backflow device for the ventiduct in the coal and gas outburst accident, the existing anti-backflow device was studied, and the dynamic characteristics of the existing anti-backflow device under the effect of the outburst shock wave overpressure of 10MPa coal seam gas pressure, basing the research results and safety design concepts Give an improvement plan. Combined with fluid dynamics, the mathematical model of shock wave overpressure at different positions of the roadway is obtained. According to the corresponding regulations and actual safety requirements of the coal industry, the LS-DYNA software is used to numerically simulate the structural damage of the blower backflow prevention device under the impact load. Obtain the dynamic characteristics of the anti-backflow device of steel wind tube of different structure and material. Research shows that the cross-sectional area of the ventiduct is much smaller than the cross-sectional area of the roadway. Due to the reduction of the cross-sectional area of the propagation path, the overpressure of the shock wave entering the ventiduct from the roadway will suddenly increase to five times that in the roadway. The maximum stress of the existing anti-backflow device under the shock wave overpressure of 10MPa coal seam gas pressure scale reaches 664MPa, which is far greater than the yield limit of Q235 steel of 235MPa,which cannot meet the safety requirements; The maximum stress of he improved structure of the 25mm and 30mm thickness anti-backflow device under the worst conditions is less than the yield stress of the material, and the maximum displacement is much less than its own thickness, which can meet safety requirements and the improvement plan is reasonable.

In order to solve the problem of safety accidents caused by the loosening and failure of the anchor bolts of the head of the underground belt conveyor under long-term dynamic load, firstly, the failure mechanism of the anchor bolts is analyzed based on the horizontal force of the bottom plate and concrete, and the stress model of the head of the belt conveyor is established. Secondly, the stress balance of the head is analyzed, and the preload of the anchor bolts is determined, Finally, the numerical simulation software is used to study the influence of different diameter anchor bolts on the stress distribution and displacement of the bottom plate, and further determine the reasonable anchor bolt diameter parameters of the head anchorage. Through gmy400 anchor (cable) dynamometer, the fastening force of anchor bolt is monitored and statistically analyzed, and the rationality of selecting diameter is determined. The research shows that: in order to maximize the anchoring performance, the diameter of anchor bolt and the thickness of concrete wall should be comprehensively considered when anchoring. The field practice shows that selecting a reasonable diameter of anchor bolt can effectively reduce the loss of fastening force, improve the anchoring effect of anchor bolt and prevent the occurrence of head instability accident.

In order to improve the hierarchical management and control of coal mine safety risks and the ability of accident prediction and early warning, and realize the dynamic supervision and risk prevention and control of enterprises in the coal mine industry, we have established the development platform architecture and business application architecture of the coal mine intelligent video early warning system by using video analysis technologies such as artificial intelligence and machine learning to intelligently monitor many working scenes on and under the shaft, automatically detect hidden dangers and alarm, Put forward the index system of intelligent video early warning analysis of coal mines, early warning prevention and control and analysis methods, and establish a unified information platform for safety production; Based on video image data, seven application scenarios of intelligent video early warning system are analyzed, including GIS map dynamic panoramic display of working area, standardized wearing of safety helmets, identification of railway station personnel, identification of crawling and pedaling transport vehicle behavior, identification of key post personnel off post, belt deviation detection, belt empty load detection, and underground fireworks detection.

The output of coal fines is one of the key issues affecting the efficient development of CBM. The blockage of coal fines will cause the pump to be buried and stuck in the CBM well, increase the number of workover operations in the drainage and production of the CBM well, and affect the efficient development of the CBM well. Since the content of inorganic minerals in the coal fines produced by the coalbed methane wells is as high as 50%, in order to find out the effect of different dispersant types on the dispersion of mudstone particle suspensions with different particle sizes, the Taiyuan Formation of the Hancheng block in the eastern margin of the Ordos Basin was selected. 11# coal seam roof mudstone sample, carried out the dispersant optimization experiment of mudstone particles with different particle sizes, analyzed the static stability and mass concentration characteristics of mudstone particle suspensions with different dispersants, and discussed the effect of dispersants on mudstone particles with different particle sizes and different dispersants. Effects on the dispersion stability of mudstone particles of the same size. Optimizing dispersants with relatively good dispersing effect applied to CBM well-washing technology. The experimental results show that different dispersants have different effects on the dispersion stability of mudstone particles with different particle sizes. With the increase of particle size, the dispersion stability of mudstone particle suspension of SDS and SDBS dispersants becomes worse; the dispersion stability of mudstone particle suspension of SN dispersant does not change significantly. With the increase of standing time, the dispersion stability of mudstone particle suspensions with different dispersants decreases, and the mass concentrations of mudstone particle suspensions with different dispersants all decrease to varying degrees. The mudstone particle suspension of SDS dispersant has the largest mass concentration of mudstone particles under the conditions of different particle sizes and different standing times. The straight-chain alkane hydrophobic base of SDS is more easily adsorbed on the surface of mudstone particles, which can play a good dispersion effect on mudstone particles of three sizes, and has strong suspension dispersion effect and static stability. Based on the differences in the dispersion and suspension stability of coal fines and mudstone particles with different types of dispersants, it is suggested that SDS should be selected as the dispersant in the CBM well-washing technology.

Flotation tailings is mainly stockpiled in coking coal preparation plants in China, which has caused serious environmental pollution, and its high-value application is imminent. In this paper, the flotation tail coal of Shanxi Coking Coal Group was selected as raw material, and the hydrogen rich fuel gas was prepared by co-catalytic pyrolysis of flotation tailings and pine branch after loading iron, calcium and potassium ions in different load methods in a fixed bed reactor. The results show that after the addition of catalyst, the semi-coke yield of flotation tailings and pine branch co-pyrolysis test decreases significantly, and the gas yield increases significantly, indicating that the addition of catalyst has a positive role in promoting the gas product yield and calorific value of co-pyrolysis. In general, iron-series catalyst > calcium-series catalyst > potassium-series catalyst. The different preparation methods of catalysts also have different effects on the co-pyrolysis gas products. As for the calorific value of gas products, the order from strong to weak is loading type > impregnation mixing type > mechanical mixing type; For the H2 yield of the target gas product, the order from strong to weak is impregnation mixing type > loading type > mechanical mixing type; There is no significant difference in the load methods of the catalyst for the CO yield of the target gas product; As for the yield of the target gas product CH4, the addition of potassium-series catalyst inhibited it; For the CO2 yield of the target gas product, the inhibitory effect of the catalyst on it from strong to weak is potassium-series catalyst > calcium-series catalyst > iron-series catalyst. These experimental results hope to provide industrial reference for the high-value application of the co-catalytic pyrolysis system of flotation tailings and pine branch.

In order to solve the problems of long heating time, high energy consumption and slow response of traditional electric heating conveyor belt joint vulcanizing machine, this paper applied electromagnetic induction heating technology. First of all, it established the electromagnetic-thermal coupling model of the electromagnetic induction heating device, analyzed the frequency and intensity of excitation current on the distribution law of eddy current field in the Maxwell heating plate, and explored the influence of adding magnetic guide on the electromagnetic induction heating power. Based on the electromagnetic induction simulation results, the Transient Thermal module was used to obtain the temperature rise curve and temperature field distribution, so as tot determine the optimal parameters of excitation current frequency and intensity. Finally, the electromagnetic induction heating experiment bench was built to conduct heating tests under the optimal parameters, thus verifying the accuracy of the simulation results. The results show that the heating power of the heating plate can be increased by adding the current frequency and intensity, along with 29.9% by expanding magnetic guide. Under the optimal excitation current frequency of 25 kHz and strength of 29 A, the heating plate rises from 28℃ to 145℃ after 238 s, and the average temperature difference is 8℃, which reduces the heating time of vulcanization. This paper also provides a theoretical basis for the application of induction heating technology in the conveyor belt joint vulcanizing machine.

Abstract: each link of coal mine auxiliary transportation system needs the participation of a large number of personnel, which has become a key problem to ensure underground safety and restrict the unmanned development of coal mine. According to the technical requirements of unmanned driving in coal mine, the vehicle control system controlled by CAN bus is designed, and the specific functions realized by each control execution unit of the vehicle are designed, including the functional design of driving auxiliary equipment such as driving motor, braking system, battery management system, personnel takeover control logic, methane gas alarm system, light, horn, etc, The wlr-9 (a) electric pickup truck of Shanxi Tiandi Coal Machinery Equipment Co., Ltd. was transformed and the application program was developed, and the ground and underground driverless tests were carried out in zhangjiamao coal mine. The test results show that the stability and reliability of the vehicle chassis controlled by CAN bus can meet the requirements of underground working conditions and environment in coal mines.