Aiming at the phenomenon of strong underground pressure and abnormal pressure law in fully mechanized caving mining face under gully landforms, the paper takes the advancing process of a mine 12309 working face through gully landforms as the engineering background, and comprehensively uses numerical simulation and similar simulation research method, analyzed the overlying strata migration and fracture characteristics and the evolution of plastic zone during the advancement of the working face, and revealed the influence mechanism of gully landform on the behavior of fully mechanized caving mining. The research results show that the breaking of the main key stratum will cause the separation between the bedrock and the loess stratum, causing the crack to penetrate to the surface and form a crack. At this time, the uneven surface load of the gully landform is likely to interact with the mining stress, causing the upslope section of the overburden and loess stratum has a tendency to turn to the goaf, resulting in abnormally violent underground pressure in the fully mechanized caving face; Simultaneously, similar simulation results quantify that the first weighting interval of the basic roof of 12309 working face is 35 m, and the periodic weighting step distance is between 23 and 34 m. Numerical simulation analyzes the evolution of the plastic zone of the overlying strata in the working face, which is consistent with similar simulation results. This research conclusion can provide a reference for advancement planning of working face under similar conditions.

Abstract：Aiming at design problems of the temporary drainage system of the second area of Xiaozhuang mine, based on short service life and saving engineering quantity and time limit, the new conception for temporary engineering was proposed. Utilize crossheading of main roadway for constructing water pump house and lay out main water sump and auxiliary water sump on both sides of the pump room. Engineering application shows: By using this design method, under the condition of detriment of the drainage function, it can effectively avoid the crossing of the tunnel, reduce the amount of excavation and the construction period, and has certain guiding significance for the construction of the temporary system.

In order to solve the problem of short lap travel and low tunneling efficiency of the supporting equipment for the roadway excavation in mengda mine. Through the research of the geological conditions, laneway specifications and construction technology of the mengda mine. Hydraulic?pressure?rockbolt?drill?vehicle, long span bridge conveyor and track-type mobile?tail as the main equipment is developed and designed. The system can meet the engineering requirement of 50 m per day, and improves the overall tunneling efficiency by 2.5 times.The system will be applied to 31104 laneway in heading face of 3-1 coal seam of Mengda Mine.The results show that: So far, the system has an average daily advance of 45 m, monthly average of 1100 m, to meet the requirements of use and design. At the same time, the system also provides an optional scheme for laneway driving face under 3 km.

In order to improve the design quality of coal mine roadway and improve the traditional information utilization mode, Based on BIM technology, the 3d design system of coal mine roadway was developed and applied in engineering practice. Through this system, the 3d parametric design、visual presentation and data expression of roadway can be conducted quickly and conveniently. Moreover, it can output all kinds of engineering drawings and statistical statements meeting the construction requirements with one key, at the same time, the effective extension of BIM service chain is realized, tt is of great significance to the construction and operation process, which provides a strong foundation for construction of digital mine and has certain reference value.

The most effective means to prevent water disaster in coal mine is to take the initiative to monitor and warn the influencing factors of water disaster. To realize the integration of surface and underground coal mine hydrology monitoring and early warning system, first of all, analyze the key factors affecting the main water disasters occurring in coal mines, coal mine hydrology monitoring important monitoring parameters, from the practical consideration design function of the hydrological monitoring and early warning system's overall structure, respectively, on the surface and subsurface hydrology monitoring operation structure architecture, the field application results show that the hydrological monitoring and early warning system can realize the effective monitoring and early warning of the water disaster factors in the production process of coal mine through digital means, grasp the dynamic change law of mine hydrogeology in time, and analyze the possible water inrush condition in the mine.

The differential equation of shear lag effect of the structure under the lateral force is derived by using energy variation principle, and then is solved under the boundary conditions, in which the frame-tube structure is equivalent to a solid tube. Then, the reinforced concrete shaft tower model is established in Midas Gen finite element software. By the program, the shear lag effect of shaft tower is analyzed under condition of different beam to column stiffness ratio, corner posts stiffness, tower height and height width ratio. The results show that the maximum shear lag effect of the shaft tower is mainly emerged in the bottom. If remaining the overall stiffness of the shaft tower, increasing the shear stiffness of the beam, reducing the corner posts stiffness and controlling the height width ratio are beneficial to reduce the shear lag effect of the shaft tower.

In order to solve the problems of the easy breakage and large subsidence of the roof in the surrounding rock with composite roof cutting at gob-side entry retaining, taking the tailgate of 3124S working face in Longtan Coal Mine as the engineering background. Based on the deformation monitoring results of the composite roof cutting at gob-side entry retaining, the deformation characteristics of the surrounding rock with composite roof cutting at gob-side entry retaining were studied, and the deformation failure mechanism of the composite roof cutting at gob-side entry retaining was revealed. Meanwhile, the regional multi-media coupling support technology and process were proposed according to the deformation characteristics of the surrounding rock. The results show that the roof deformation can be effectively controlled by taking the multi-media coupling support technology in the different areas. The maximum subsidence of the roof, reduced by 60% to 75%, is 62mm, and the efficiency of roadway retained is increased by 15% to 40%,which ensures the rapid advancement of the working face.

Aiming at the problem of supporting difficulties in extremely close coal seams, basing on the geological conditions of a mine in Shanxi province, theoretical analysis method was used to study the stress distribution below the residual coal pillar, and the stability of mining roadway under non-uniform loading. The results show that one side lane and roof are prone to local damage under severe non-uniform load. The UDEC-Trigon numerical model was used to analyze the failure characteristics of the surrounding rock of the roadway at different locations and the evolution law of the surrounding rock crack under different support conditions. The results suggest that the mining roadway under the residual coal pillar should avoid the influence of the stress increasing area and the stress reducing area of high level stress. Appropriate supporting structure can effectively restrain the increase of cracks and stabilize mining roadway. The practical results of the mining roadway at NO.3106 working face show that the mining roadway is arranged 15 m away from the center of the residual coal pillar, which can reduce the influence of the floor stress. At the same time, the use of a high-strength anchor (cable) coordinated support scheme for key parts is conducive to enhancing the overall stability of the surrounding rock of the roadway.

In order to reveal the influence law of surrounding rock stability of mining roadway affected by repeated mining under the influence of superimposed stress of overlying residual coal pillar, Theoretical calculation and numerical simulation verify that the overlying "t" shape distribution of the residual coal pillar on the underlying roadway surrounding rock stress caused by superposition, the influence range is about 170m, and on this basis, seven stability analysis stations are arranged at an interval of 30 ~ 35m; the spatial and temporal evolution process of surrounding rock stress, lateral and advanced abutment pressure of roadway side and plastic zone are further simulated and analyzed. The results show that the stress of surrounding rock transfers from symmetrical distribution to coal pillar side during roadway driving, primary mining disturbance and secondary mining advance influence. The maximum stress is 20.5mpa, 32.7mpa and 59.3mpa respectively, and the stress concentration coefficient is 2.14,3.41,6.18. The results show that the lateral abutment pressure changes from symmetry to asymmetry, from obvious difference in three sections to stress concentration under the overlying coal pillar step by step. The peak coefficient of the leading support pressure directly below the coal pillar is 4.08, and the leading severe influence range is about 10-60m in different stages, and the general influence range is up to 180m.And the asymmetric evolution process and space-time dangerous area of plastic zone of surrounding rock are found. The integrated coordinated control scheme of hydraulic fracturing pressure relief, long-distance support advanced support, asymmetric reinforcement of coal pillar and solid slope is put forward. The field application effect is good. The research results can provide reference for similar support decision-making of mining roadway affected by dynamic pressure and long service period.

In order to solve a series of problems of ecology, environmental protection and economy caused by water gushing from burnt rock at the east side of Xiwan Open-pit Coal Mine, the idea of constructing a water cut-off curtain in burnt rock outside the mine was proposed, and the spatial location of the cut-off curtain was designed. And structural parameters; in view of the difficulty of ensuring the water permeability of the curtain wall caused by the deformation of the open pit side and frequent blasting, comprehensive consideration of technology, economy, construction period and other factors, combined with the actual geology and stripping conditions of the pit, the first to use clay-based slurry construction The new method of open-pit mine flexible, earthquake-resistant water-cutting curtain; in response to the problem of large grout intake of burnt rock, a new clay grout grouting process with clay slurry, clay-cement slurry, clay-cement-water glass slurry is proposed. A water-cutting curtain wall with a length of 720m, a depth of 80m, and an effective thickness of 7m was constructed. Finally, the quality and water reduction effect of the curtain were tested by the water pressure test method, the water level dynamic method, and the water volume analysis method. The results show that the curtain wall permeability coefficient K<10-4cm/s, the water permeability reaches the weakly permeable level, the groundwater level outside the curtain wall rises significantly, the water inflow within the treatment area is reduced from 698m3/h before treatment to 71m3/h, and the water reduction rate Up to 89%. This project pioneered the use of clay-based flexible and seismic curtains to intercept burnt rock water in open-pit mines. It has important reference to the research and application of other types of open-pit curtains.

The roof of 1102 working face in Qiuji Coal Mine is a dense and hard composite limestone roof. Based on the model of surrounding fixed rock beam, the first caving and periodic caving steps of the roof before roof cutting are calculated theoretically. It is found that the large-span suspended roof appears in the goaf after the pushover of the working face. In order to solve this problem, this paper analyzes and calculates the reasonable length of the suspended roof, and puts forward the technology of deep hole blasting to close and cut the roof. It is proposed to use the concentrated energy blasting to form the closed through cracks on the directional fractured roof, so as to help the roof of the Goaf Collapse in time with the pushing mining and reduce the length of the suspended roof in the goaf. According to the geological conditions of the project, the height of the cut roof, the angle of the cut roof and the spacing of the blastholes are specifically designed A set of complete design scheme of blasting cutting parameters is formed. The field test shows that after blasting, the cracks between adjacent blastholes cut through to form a closed seam surface, and the suspended roof of the goaf collapses along the closed seam surface in time. The first caving step of the composite roof is reduced from 45m to 24m, and the periodic caving step is reduced from 19m to 11m, 46.6% and 42.1% respectively. The caving effect is good, which provides a reference for solving the problem of large-span suspended roof under the same geological conditions.

Aiming at the phenomenon that the caving effect of extra thick hard top coal is poor and difficult to be released. Taking 3107 working face of Shen-Shupan coal mine in Yulin area as the research site. According to the theory of cantilever beam, the reasonable crack interval of top coal fracture above the support is analyzed.It is suggested that the vertical crack spacing of top coal should be less than 2.8 m. Then, the scheme of fracturing with deep hole water jet interval cutting is put forward. The distance between each group of presplitting holes is designed to be 10 m. The distance between the holes is 7.5m.The vertical crack spacing is 2.6m.Hydraulic fracturing holes are arranged in advance in two crossways. The interference with working face mining operation is avoided. After construction, the effect of pre cracking is tested by electromagnetic wave CT technology. The results show that: the pre fracture propagation radius can reach 6 m in top coal. After fracturing, the side length of top coal caving block is not more than 0.6m. The recovery rate of top coal is 72.49%. And the coal cutting efficiency is also improved. This technology provides an effective way to improve the caving ability of top coal in hard and extra thick coal seam.

The division of gas geological unit in coal mine field is the basis of studying the Geological Occurrence Law of coal seam gas and the implementation of comprehensive gas prevention and control technology. It is of great significance to improve the gas drainage efficiency and ensure the safe and efficient production of coal. In order to make the implementation of gas drainage measures more accurate and mine gas drainage efficiency higher, this paper divides the gas geological units of Weijiadi coal mine in Jingyuan mining area of Gansu Province, and establishes four levels of step extraction of mining face according to the gas content of different geological units. The areas with different step contents are implemented with gas drainage by drilling along the seam, buried pipe drainage at the upper corner and upper exit Different gas drainage technology measures, such as middle hole gas drainage, roof rock strike high-level drilling and surface drilling gas drainage, established the mine gas precise drainage mode, and carried out the experimental practice in dong102 fully mechanized caving face. The results show that the residual gas content in the coal body is reduced to less than 6m3/t through the implementation of gas cascade control and precise drainage mode; during the mining period, the gas concentration in the return air flow of the working face is controlled at 0.2 ~ 0.3%, and the randomness and blindness of the implementation of the field gas drainage measures are also avoided. The precise gas extraction based on the division of gas geological units provides a theoretical basis for energy saving and consumption reduction, quality and efficiency improvement and fine management, and ensures the safe and efficient production of the mine.

To control gas drainage efficiently and specifically, No. 11 Mine of Pingdingshan Tian’an Coal Mining Corporation Ltd. took Ⅵ16-17-24070 work-plane as the test site. The technology of gas control with borehole instead of tunnel was adopted and comb-shaped directional branch hole was applied by means of directional drilling machine. Field test of directional borehole was conducted , original gas content and gas pressure of Ⅵ16-17-24070 work-plane were measured. The research results indicated that the original gas parameters of coal seam can be obtained by means of directional borehole and deep hole sealed coring technique. Main directional borehole is drilled in stable rock layer of roof and branch borehole penetrates into the coal seam from the roof, which can solve the problem of unstable and shrinkage of borehole in the outburst coal seam. The measured gas content is 3.74 m3/t ~ 4.91 m3/t with a maximum of 4.91 m3/t, and gas pressure is 0.13 MPa ~ 0.43 MPa with a maximum of 0.43 MPa, which are all lower than the "double 6" standard stipulated by Henan Province. It is determined that this range is predicted to be a non-outburst risk area. The test results can provide technical support for mastering the gas parameters of coal seam, safety and efficient mining.

In order to solve the problems of large quantity of enlarging the borehole and low efficiency of borehole forming comprehensively in the method of leading borehole with multi-stage drilling and enlarging of high-position large-diameter directional borehole in the roof of coal mine, the technology of multi-power drilling and enlarging of leading directional borehole is researched. The technology is developed based on the two power sources of drilling rig and mud pump, which combines the mechanical energy of borehole opening and the pressure energy of borehole bottom, and the matching down hole motor with double bits is also developed. The results of actual drilling test show that the borehole diameter from 120mm to 200mm can be completed by the technology and equipment of multi-power drilling and enlarging at a time, and the average mechanical drilling speed can reach more than 10m/h in the typical roof sandstone, which greatly reduces the amount quantity of in and out drilling tools, and the comprehensive drilling efficiency can be increased by more than 25%. The technology enriches the method of drilling and enlarging the diameter of leading directional borehole underground coal mine, which is of great significance to promote the development of large-diameter directional borehole in the roof instead of high-position drainage roadway.

pumped storage system in abandoned wells and roadways can realize the resource utilization of abandoned mine and the consumption of renewable energy, however, the theory and technology system still need to be further improved. The mining spatial distribution of coal mine in the main coal-producing provinces of China are statistically analyzed, The great potential of the development of pumped storage system in abandoned wells and roadways in China has been revealed. The theory and technical framework of pumped storage in abandoned wells and roadways are expounded From the aspects of engineering background, scientific problems, key technology and engineering practice. The research results show that: the occurrence law and resource utilization method of goaf water, the multi field coupling deformation mechanism of artificial dam and coal pillar, the technical and economic principle of pumped storage system in abandoned wells and roadways, and the transition mechanism from coal mining to pumped storage system in abandoned wells and roadways are the scientific problems that should be solved urgently in the development of pumped storage system in abandoned wells and roadways; Goaf water resources assessment and ecological utilization technology, coal pillar anti-seepage transformation technology, artificial dam design and construction technology, and floor anti-seepage transformation technology are the key technologies to be tackled. The theoretical research system of the development of pumped storage system in abandoned wells and roadways is further clarified, which provides a reference for the development and application of pumped storage system in abandoned wells and roadways.

In order to obtain the stress distribution of the inclined roof roadway’s surrounding rock, based on the conformal mapping function, the analytic solution of stress distribution of the inclined roof roadway’s surrounding rock is solved by using complex function method. Taking the 17102(3) working face of the Pansan Coal Mine as the engineering background, the distribution characteristics of the main stress and the main stress concentration coefficient of the inclined roof roadway’s surrounding rock are analyzed. The results show that the maximum principal stress, the minimum principal stress, the maximum shear stress and the principal stress concentration coefficient of the inclined roof roadway surrounding rock all appear in the corners of the roadway, the maximum value of the principal stress exceeds 35MPa, and the maximum value of the principal stress concentration coefficient exceeds 4.5, 2.5, and 8, respectively, indicating that the corners of the roadway is the weak part of the inclined roof roadway; the maximum shear stress of the two sides is larger than that of the roof and floor indicating that the roof and floor are more stable than the two sides. The research results can provide theoretical reference for supporting design of the inclined roof roadway.

In Yili mining area, the coal seam is shallow, close to the aquifer, and the bedrock is thin and weak. The water inrush from the working face has become an important problem that restricts the safety production of the mine. Therefore, this paper studies the characteristics of overburden migration and the influence of water inflow on the working face by theoretical analysis and field measurement. The results show that there are only "two zones" in the upper part of the goaf, and there is no overburden condition to form the bending subsidence zone. The slow advancing speed of the working face will give the overburden full development time of mining fissures, and the high developing height of the two zones will lead to the large water inflow of the working face due to the communication with the aquifer; the acceleration of the advancing speed of the working face will lead to the emergence of the whole surface with the mining of all the weak overburden , regular subsidence, in order to fully develop the "two zones" to be compacted rapidly, to bridge the water channel of the fracture and reduce the water inflow of the working face. The research results provide an important basis for safe mining.

In order to analyze the feasibility and accuracy of the subdomains-analytic element method used in simulation of coal mine groundwater flow field, a coal mine groundwater flow field model was constructed based on the principle of the subdomains-analytic element method, and applied the model to an example of coal mine dewatering rate prediction, the simulation results were compared with that of Feflow.It shows that the head of each drainage hole predicted by the subdomains-analytical element method and Feflow falls below the critical safety head in 57 days and 60 days, respectively,and the head of each observation hole falls below the critical safety head after drainage,on the condition that the location and dewatering rate of each drainage hole in the subdomains-analytic element method model is the same as that of in the Feflow model. The results reveal that the subdomains-analytic element method is feasible and precision controllable in the simulation of groundwater flow field of coal mine. It is a useful supplement to simulation methods of groundwater flow field of coal mine.

The treatment and utilization of coal mining subsidence areas is an important measure for the coal industry to implement the theory of lucid waters and lush mountains are invaluable assets, and promote the construction of beautiful China. After analyzing the current condition of the technical standards and standard system for the land management and utilization in coal mining subsidence area, the problems such as imperfect standard system, lack of key technical standards and the lagging standardization in this field has been found. In order to solve the problems, we constructed a system framework structure, consisting of two first-level systems (including basic standards, and land treatment and utilization) and several second-level and third-level sub-systems, and offered some suggestions for the development of critical technical standards, following the principles of comprehensiveness, advancedness, practicality and openness. The constructed technical standard system framework will help improve the coal industry standard system, guide the formulation and implementation of specific technical standard, and actively promote the technology development for treatment and utilization in coal mining subsidence area.

Obtaining accurate and reliable probability integral parameters is very important in the prediction of mining subsidence movement and deformation. In view of nonlinear models are widely used in parameter prediction, this paper develops a prediction method of probability integral dynamic parameters based on fusion of FWA and Logistic ( FWA-Logistic method ). The Logistic model has been widely used in agriculture, medicine, deformation prediction and other fields, and The morphological characteristics of the model conform to the law of probability integral parameters; Theoretically, the Logistic model can be better applied to the prediction of probability integral dynamic parameters. Taking into account the large volatility of nonlinear least squares to obtain model parameters, and the unreasonable selection of initial values will cause the results of the parameters to diverge, an FWA algorithm was introduced. Integrating the principle of FWA algorithm, Logistic model and the law of probability integral parameter, the FWA-Logistic method is proposed. The experimental results show that the effect of fitting sample parameters q, tanβ, θ is better, and the RMSE in fitting are 0.023, 0.097 and 0.025 respectively; The average relative error of predicted the parameters of the next 4 periods was 3.64%, 1.53%, 0.08%, and the maximum relative error was 7.76%. In order to verify the practicability of the predicted parameters, based on the predicted parameters in the last period, the subsidence of the main surface section is predicted by using the probability integral model. Compared with the actual measurement, the estimated subsidence error is between -243 mm and 196 mm, with RMSE of 90.57 mm.

In order to study the flow field characteristics of the negative pressure dust collector and improve the dust removal efficiency of the negative pressure dust collector, the dust removal principle of the negative pressure dust collector is analyzed, and the factors influencing the dust removal inside the ejector cylinder of the negative pressure dust collector are discussed. Based on Fluent software, the fluid model of the negative pressure dust collector is established. The single-variable method is used to analyze the internal flow field of the dust collector under different water pressure, nozzle diameter and nozzle position. The optimal parameters of the negative pressure dust collector are obtained as follows: the water pressure is 12 MPa, the nozzle diameter is 1.5 mm, and the optimal nozzle position is 400 mm away from the end face of the gas collecting hood. The simulation results have a certain reference value to study the dust removal efficiency of the negative pressure dust collector, and provide the basis for the nozzle structure design of the negative pressure dust collector.

Phase break fault is one of the main causes of three-phase asynchronous motor damage. The existing phase break identification methods require complex mathematical operations, and the data accuracy and calculation speed are greatly affected by the performance of the algorithm. Based on this, a new method is proposed to identify phase-break fault according to the proportion of second harmonic in three-phase current envelope signal. This paper analyzes the typical phase-break fault characteristics, and calculates the proportion of the second harmonic in the envelope signal of the three-phase current under the symmetrical operation, single-phase operation and asymmetric operation of the motor by Fourier series transform, verifies the three-phase unbalanced conditions, also gives the design principle of the hardware circuit.The practical application shows that this method is simple and sensitive to the phase-break fault. It can accurately identify the phase-break fault. It is not susceptible to the interference of unbalanced three-phase voltage amplitude, and has a wide range of adaptation. It provides a new feasible method for timely and effective identification of phase-break fault.

Aiming at the problems such as the autonomous positioning of the inspection robot without GPS in the coal mine water pump room, weak anti-interference ability, and inability to help the robot to complete the daily inspection tasks, a method of simultaneous localization and mapping based on Fast-SLAM was studied. Firstly, the probability model of SLAM was established, and the odometer was calibrated by least linear square and the sensor data was preprocessed by integrating the wheeled odometer and the IMU. the more accurate pose information was obtained than that of the wheeled odometer, so as to reduce the non-systematic errors in relative positioning. Then, the environmental information obtained by the external sensor and the motion information of the robot were converted into the world coordinate system by using the coordinate transformation relationship of the robot, and the distribution of the proposal was optimized based on the particle filter algorithm to obtain the accurate pose estimation of the robot. Finally, the global environment map is established by overlaying the grid map. Matlab simulation and experimental results show that the Gmapping algorithm after sensor pretreatment and algorithm optimization meets the needs of robot real-time positioning, and has a higher mapping accuracy, and can be effectively applied to the coal mine water pump room.

In order to study the specific cut-off energy consumption in a specific mine or area, using the operating data of the MG900/2400-WD shearer in a certain mining area of the Shaanmeng Coalfield, combined with the actual working conditions of the equipment, a data cleaning algorithm for different data types is proposed , Eliminate errors in the data acquisition process. The speed correction algorithm uses the change of the frame number data to determine the speed direction of the shearer and correct the wrong speed data. The height correction algorithm uses the mode within 50s before and after the height data to fill in the sudden changes in the data caused by vibration and shock. Visualize the data before and after cleaning for comparison and verification. By observing the position change of the shearer, the data of 45 groups of shearers during normal cutting are selected. Use the shearer traction speed to determine the height of the mining and the depth of the drum to calculate the volume of coal cut by the shearer. Using the current data of the shearer motor, calculate the energy consumed by the shearer for cutting coal. The results show that these two algorithms can respectively correct the errors in the speed and height data, and use the cleaned data to calculate the cutting specific energy consumption. These two algorithms provide new ideas for the cleaning and application of big data for the shearer operation. The results of cutting specific energy consumption provide guidance data for the promotion, design and improvement of the shearer in the next stage.

Abstract：In this project, a new process of "cyclone separation + membrane treatment + swirling clarification" is proposed for high concentration mine water treatment. The large particles are separated by swirling flow, and then the suspended solids are removed by ceramic membrane filtration. The concentrated high concentration slime water is then fed into the cyclone clarifier to flocculate and precipitate, and the qualified produced water is obtained. The pilot test shows that the mine water treatment efficiency is high, the effluent turbidity is less than 10NTU, the system water recovery rate is 97.5%, the micro sand circulation rate is more than 97%, the dosage of agent is reduced by 40-60% compared with the traditional coagulation sedimentation technology, and the reagent cost per ton of water is saved by 0.2 yuan.

In order to solve the problem of high kerosene consumption and poor flotation effect in the flotation process of low-rank unfloatable coal slime. By magnetizing kerosine-SPAN80 collector, the flotation effect of on low-rank coal under different magnetization conditions was investigated. The response surface method was used to optimize the magnetization conditions of the collector, and a response surface regression model was established to analyze the effects of the magnetization temperature, magnetization intensity, magnetization time and their interactions on the yield and coal ash content of cleaned coal. Finally, a comparison experiment was conducted before and after optimization. The results show that the variable factors have significant influence on the yield and ash content of cleaned coal. When the magnetization temperature was 20℃~30℃, the magnetization intensity was 0.2~0.4 T, and the magnetization time was 4~8 min, the flotation effect of coal slime was at a good level. The second order regression equation of cleaned coal yield and tail ash is obtained by response surface optimization test. The magnetization time has the most significant influence on cleaned coal yield and tail ash, followed by magnetic field intensity and magnetization temperature. The interaction between magnetic field strength and magnetization time was significant. The optimal magnetization condition of the collector after optimization was the magnetization temperature of 27.5℃, magnetic field strength of 0.26 T, and magnetization time of 6.05 min. At this time, the cleaned coal yield and tail coal ash content were 63.41% and 74.29%, respectively. The error between the test value and the predicted value was only 0.82% and 1.09%, which proved that the response surface optimization model was feasible for predicting the actual situation.

It is an important guarantee to product ultra-low ash coal for the utilization of commercial coal materials in Shendong mining area.The idea of water hydrocyclone separation is put forward according to the requirement of ash and iron content of coal which used to make coal-based activated carbon.The effect of pyramid segment, cone angle, bottom nozzle diameter and feeding pressure on the separation result was studied,and the stability test was carried out under optimized conditions.The results showed that the optimized separation conditions were:cone angle of 120°,bottom nozzle diameter of 16 mm,and feeding pressure of 0.07mpa.The ash content,yield and iron content reached 2.42%,70.07% and 0.24% respectively.The quantitative efficiency is 87.59% and the imperfection is 0.21,which provides a new idea for raw coal of capacitive carbon production.

In order to shorten the purchasing period of imported wet brake drive axle of trackless rubber tyred vehicle in coal mine，reduce vehicle costs，the transmission principle, transmission ratio determination, the design of the structural, the calculation of the main reduction gear ratio, the determination of basic gear parameters, and the design of the structure of a type of wet brake drive axle wheel reducer were studied. The successfully developed wet brake drive axle has completed vertical bending fatigue strength and loading tests on the bench；the maximum service braking distance of 5t rubber tyred vehicle equipped with the drive axle is 4.7m，meet the design standard；runs continuously for 2 hours on the horizontal dry and hard road surface，the maximum surface temperature of axle housing is 68 ℃；the loading application shows that the arc bevel gear of the drive axle main reducer rotates clockwise and counterclockwise transfered torque is reliable, and it has no failure for 12 months in mine. The distribution of transmission ratio between wheel side reducer and main reducer of drive axle is beneficial to the design of multiple disc wet brake，and the safety factor design of the braking system should have margin, so as to improve the braking reliability of trackless rubber tyred vehicle in large angle and long distance roadway downhill.

In order to improve the control accuracy and stability of the hydraulic system, an intelligent solenoid valve control system based on the STM32F103 controller is designed. The intelligent control system collects the data of the spool displacement sensor and the flow sensor according to the frequency, and completes the solenoid valve intelligent control system based on the displacement and flow double feedback closed-loop control after the interface circuit conversion, ADC module, and PID module processing. Establish a solenoid valve test platform, complete the solenoid valve forward and reverse stroke tests, analyze and plot the relationship between valve core displacement, valve port flow sensor data and output voltage. The test results verify the effectiveness and accuracy of the designed solenoid valve intelligent control system, and the control effect is good.

In order to improve the measurement accuracy of coal seam gas, sealed coring is generally carried out in coal seam sampling. In this article, a kind of advanced water-proof PDC drill bit for sealed coring is designed, which equipped with a three-barrel single-acting coring device for sealed seam coring. By comparing and optimizing the three structure types of common bottom-spray bit, cone-faced coal core guide bit and advanced water-proof bit, the advanced water-proof bit is selected as the core bit for sealed coring, in the drill bit, an advanced small drill bit is pressed into the coal seam, which uses cemented carbide cutting teeth for dry drilling, effectively isolate the drilling fluid from entering the coal core. According to the continuity equation of hydrodynamics, the number and size of water eyes are optimized, which reduced the erosion of coal seam by waterhole drilling fluid, and adopt inclined water eye, reverse inclined water channel to prevent drilling fluid from entering the coal core. The PDC cutting teeth was arranged according to the principle of fully covering the bottom of the well to Optimize drilling efficiency. The designed drill bit was used in ground mining and pressure relief gas extraction well of Luling Coal Mine in Huaibei, the test proves that the coal coring adoption rate satisfies the requirements of the sealed coring construction.

In order to reduce working boom lifting angle of SL3, method of optimizing chute length is chosen, through simulating and amending throwing coal track of chute bucket, actual throwing coal track function is confirmed, in the same position and different chute length, different throwing coal distance is gotten, with the working requiring of SL3, shortening range of chute length of SL3 is 1.5～2m, meanwhile controlling method of SL3 working coal dust is introduced. After the solution is carried out, working lifting angle of SL3 boom is reduced up to 3°～5°, SL3 works well, working process flow-rate of SL3 is added up to 95t/h, economic benefit is promoted well.

Coal mine safety risk precaution model is an important channel to realize safety risk prediction and precaution. In order to further improve the accuracy of automatic assessment of coal mine safety risk precaution, the relation network, the index weight factor and the flexible relation operator base of index system attribute characteristic are studied. A decision tree model of risk precaution based on flexible logic is proposed. Compared with the traditional decision tree and analytic hierarchy process prediction analysis algorithms, which aim at the safety production data in Inner Mongolia Coal Mines, this method can automatically obtain higher prediction and early warning accuracy, it is helpful to reduce the accident rate of safety production in coal mine.

As the research contact accident of coal mine management, combined with years of coal mine construction, production technology management and safety management experience and field investigation, accident analysis in recent years, the author found out that: The main reason of the accident is the management chaos of coal mining enterprises, not strictly implemented “Three responsibility”?and “Three must”;Safety management system,legal system construction,the management system is not perfect or not strictly implemented;the safety management organization is not perfect or the managers fail to perform their duties; safety production access control is not strict; the phenomenon of “Three violations”occurs frequently and so on.Safety management system for the above problem, and the rule of law, system,team and safety culture construction, safety production access, anti“three violations”, etc in this paper, the coal mine safety management methods and Suggestions.