The shafts of freeze sinking method in China have passed through 500 m, 600 m and 700 m thick alluviums successively. The existing standard has only the method of freezing pressure value of less than 500 m thick alluvium. Because the freezing pressure is the main calculated load for the strength and thickness design of the outer shaft wall, to study and determine the standard value of the freezing pressure of alluvium thicker than 500 m has important theoretical and practical significance for scientific and rational design of outer wall and safe construction of shaft wall. Based on the analysis and research on the test results of freezing pressures of the freezing walls in deep alluvium in China, a method for determining the standard value of freezing pressure in outer shaft wall design of frozen shafts in deep alluvium over 500m was put forward, which could be used as a reference for the design and construction of outer shaft structure.

In order to solve the engineering problem that the closure time of artificial frozen wall increased or even failed to overlap under the action of groundwater with large flow rate, considering the effect of groundwater on the artificial freezing temperature field, the method of encrypting the freezing pipes in the upstream area of the water flow was proposed to optimize the freezing scheme. The hydrothermal coupling mathematical model was constructed which was based on the apparent heat capacity method, and the rationality of the mathematical model was verified by large physical model tests. Based on the mathematical model and the design parameters of a freezing scheme in a shaft of Huainan mining area, the optimization effects of the seven optimization schemes were analyzed by numerical calculation. The optimization effect was analyzed: Under the action of groundwater with a large flow rate, the freezing effect of the upstream position of the freezing pipe arrangement circle is a decisive factor affecting the closure time and thickness of the entire frozen wall. After encrypting the freezing pipes in the upstream position, the spacing between adjacent freezing pipes is reduced, and the cold supply in the upstream position was increased, thereby the closure time of the frozen wall in the upstream area was shortened, and the freezing efficiency of the entire frozen wall was increased .when the angle of encryption was 105 , and the spacing of the freezing pipes was reduced to 1 m, the maximum interlacing velocity of the frozen wall reaches 13 m/d, which is 62.5% higher than that was before optimization (8m/d). And corresponding to the same freezing time, the thickness of the frozen wall formed by the optimized freezing scheme was significantly larger than that before the optimization. The optimized design method would provide an important reference for the design of freezing holes in freezing method with large-flow-rate groundwater.

Aiming at the difficult problems that the depth of alluvium in the West Ventilating Shaft of Zhaogu No.2 Coal Mine exceeds 700 m, little construction experience of similar vertical shaft in China and abroad, and the guiding principle of freezing design is not unified, through analysis and summary of the problems existing in the construction of frozen shaft in deep alluvium, and choose the guiding principle of freezing design to strengthen the freezing strength of the outer side of freezing wall in deep alluvium, which can fully reflect the safety, advancement and economy. The freezing scheme of the West Ventilating Shaft of Zhaogu No.2 Coal Mine was designed by using the method of arranging the main freezing holes outside and classifying the freezing holes according to their functions, combining with the comprehensive analysis method of freezing wall formation characteristics, and the target curve of temperature control of the shaft lining was put forward. Under the good construction conditions created by the combination of freezing and excavation, the average excavation speed of the outer wall of the alluvium section of the shaft reaches 87.1 m/month, which can be used for reference in the deep alluvium freezing shaft sinking project in China.

The influence of shaft use on the strength of shaft concrete is slow and continuous. There is no mature theory and technical specification for inclined shaft freezing technology in China. In this paper, the ultrasonic rebound comprehensive method widely used at this stage is adopted to check and test the compressive strength of the shaft wall, and it is found that the current strength of the shaft wall and floor concrete is lower than the designed value (or the initial value), which is not conducive to long-term safe operation and provides reliable basis for the evaluation of shaft safety state.

During the reaming construction process of the reverse well drilling method, the well reduction diameter and the instability of the surrounding rock are the difficult and difficult problems in the development of the anti-well drilling method. When the reaming passes through a stratum composed mainly of water-softening rocks, the influence of water on the surrounding rock of the well is very prominent. The mudstone with water softening characteristics is taken as the research object. Firstly, the elastic modulus and Poisson's ratio of mudstone under different water immersion time were obtained by water immersion softening experiment, and the quantitative relationship between these two parameters and water immersion time was fitted, and the parameter equation considering softening effect was established. Then, based on the circular axisymmetric elastic solution, the displacement formula under the unsupported state of the reaming well is obtained, and then the parameters considering the softening effect are substituted into this formula. Finally, an analytical model of the displacement and immersion time of the surrounding rock considering the boundary effect is established to evaluate the safety of the wellbore reduction and the instability of the surrounding rock during the reaming construction of the reverse well drilling method. Engineering applications provide a reference.

Taking the high pressure pipeline shaft of Yimeng Pumped Storage Power Station as the research background, the motion state and track of the hob under the reaming state of the raise boring machine are analyzed theoretically. The relationship between the drilling speed and the drilling pressure and rotation speed is studied. The test is carried out at a depth of 24m from the ground, the diameter of the shaft is 2.5m, and the rock mass is granite. By adjusting the pulling force and the rotation speed of the drill pipe, and using the dynamic signal test analysis system and the intelligent digital tachometer, the drilling pressure and rotation speed of the drill pipe are obtained. Data processing and analysis obtained the relationship between drilling speed and drilling pressure, drilling speed and rotation speed of the raise boring machine. The results show that the theory and the test can be well matched, and the accuracy of the theory is proved, which provides a basis for the reasonable setting of drilling parameters of the raise boring machine.

in order to extend the service life of Zhangcun Coal Mine, the second level of Changcun Coal Mine and the sixth mining area in the north are designed to be exploited as the expansion area of Zhangcun coal mine. According to the existing situation of Zhangcun coal mine underground and surface production system, the main factors affecting the expansion area of Zhangcun Coal Mine are analyzed, and the new auxiliary industrial site is determined to be arranged in the northeast direction of Yizi village in the West expansion area Two new shafts, auxiliary shaft and West return shaft, are added. From the aspects of roadway layout, mining level and division of mining area, the development mode of West expansion area of Zhangcun coal mine is determined to maximize the utilization of resources, significantly improve the economic benefits, promote scientific and balanced production, and lay the foundation for sustainable development of coal mine.

In order to achieve safe and efficient recovery of super-long fully mechanized caving face in soft and thick coal seam, the paper studies the key technology of 1312 super long fully mechanized caving mining face in the soft thick coal seam of Sanyuan Coal Industry. Through theoretical analysis, downhole field data analysis, the transportation equipment, support strength, mine pressure and coal wall stability of the 362m super-long fully mechanized caving face in the soft thick coal seam of Sanyuan Coal Mine were analyzed. The research shows that the current mining technology and equipment level can fully meet the requirements for support and transportation of super-long fully mechanized caving face in soft and thick coal seams; During the recovery period of the super-long fully mechanized caving face, the top plate activity is more frequent than the working face below 200m, the tendency of the direction cycle is unsynchronized, and the mining pressure is more intense, and the roof management is more difficult; In order to improve the stability of the top surface of the working face and the coal wall, sufficient support strength is ensured;A dual-circuit liquid supply system is required to ensure sufficient initial support of the bracket, and the advancement speed of the working surface should be appropriately accelerated. Grouting reinforcement technology is adopted when the coal wall and roof are broken. The research results have achieved good results in the application of 1312 super long fully mechanized caving face in Sanyuan Coal Industry, and provide reference for the safe mining of similar working conditions around the surrounding area.

Abstract: This paper introduces the auxiliary underground transportation system of Luan Wangzhuang Coal Mine of the +540m level. By enumerating and calculating methods, the paper calculated the time of underground auxiliary transportation by starting from the distribution of mining sites, types of equipment, service scope and multi-purpose material requirements, and studied the factors that affecting the efficiency of auxiliary transportation system. It laid the foundation and pointed out the direction for Wangzhuang Coal Mine to take measures to solve the current auxiliary transportation problems. The paper also has a very important guiding significance for production mines with similar auxiliary transportation problems.

In order to measure gas pressure accurately in coal seam and designed borehole parameters quickly and efficiently, established a geometric model for calculating borehole parameters based on the two relative positions between piezometric drilling site and coal seam. According to the spatial relationship among drilling field, drilling hole and coal seam in the model, the formulas for calculating related parameters of upward drilling hole and downward drilling hole are obtained. A numerical example is analyzed by using mathematical software, and the appropriate parameter space for drilling design is obtained. Using the calculation model to designed and constructed the pressure measurement boreholes, it can be find that the error between theoretical calculation length and actual drilling length is less than 10%, which verifies the applicability and accuracy of the calculation formula.

Combined with occurrence characteristics of coal in Wu Lan mine, Mechanical model is established，and the mining adit and coal pillar width of the mining adit are theoretical analysis calculated. The characteristics of surrounding rock in each stage of mining and filling are calculated by numerical simulation. According to the analysis and calculation results, the working slope fill mining technology is successfully applied in Wu Lan coal mine. Stability of side wall is guaranteed, at the same time, the recovery rate of coal is improved greatly.

The vehicles used in large-scale open pit mines have small speeds and large models. The roads in large-scale open pit mines are one-way and two-lane and the road width is large. The traditional highway traffic signs are difficult to meet the driver's demand for road information. In this paper, the driver's visual recognition process of the roadside sign is analyzed theoretically. It is determined that the static blind zone is the main factor limiting the setting of the open-pit mine sign. A method for setting the single roadside sign based on the static blind zone is proposed. The calculation example proves that the calculation model is practical and feasible.

Based on the field survey and theoretical analysis and demonstration, combined with the existing data and task requirements, a feasible test plan is prepared; through the full test of the exploration area, the reasonable acquisition parameters are selected, the acquisition work of seismic exploration is well completed, and the first-hand original data is obtained. Through the later data processing and interpretation, more abundant geological results are obtained: the contour map of 2 × coal seam floor with basic contour distance of 5m is compiled, the fault property, extension direction and range with H ≥ 5m are found out, the fold property, extension direction and range with fold amplitude of more than 10m are found out, the gob and range of 2 × coal seam in the exploration area are basically found out, and the third three times of this project are well completed The geological task undertaken by the seismic exploration of dimension has been verified by the practice of 2202 working face.

In order to solve these problems of roof broken coal, soft and easily separated and caved interlayer in roof rock, sidewall convergence at the side of coal pillar, roof cracking, rib spalling, bad stability control effect, and ensure surrounding rock stability during the whole process of excavation and mining, satisfy the demand to cross-section and safety. Support parameters selection principle coupled with dynamic information design method consisted of test point investigation, geomechanics accreditation, initial design, underground monitoring, information feedback, revised design and daily monitoring were used. High prestress and intensive bolt-cable combined support system was proposed to control surrounding rock stability of 12301 working face return airway. Through engineering practice and comprehensive ground pressure monitoring, support technology application effect were verified and optimized. Investigation results showed that high prestress and intensive support was successfully accomplished in demonstration roadway, bolt and cable stress remained stable during the whole excavation and mining progress. Although there was still a relatively large convergence in coal pillar, roof was stable, the maintain of floor was greatly reduced and the safety production was fully guaranteed. Compared with original support, high prestress and intensive support technology had obvious technical and economic benefits.

Abstract: With the increase of mining depth in the mine, the influence of section pillar support pressure and mining pressure on the return air drift of the coal mining face is getting larger and larger, and the maintenance quantity and cost of the drift increase. Based on the practice of roadway driving along goaf with narrow coal pillar in Renjiazhuang coal mine, this paper concludes that roadway driving along goaf with narrow coal pillar can not only change the stress condition of roadway, improve the use and maintenance conditions of roadway, but also improve the recovery rate of mining area, which has universal popularization significance.

Large deformation and difficult support of the surrounding rock of deep mine preparation roadway, affect the safe and efficient production of coal mine. Based on the geological conditions of track-dip roadway of the district in Pingdingshan No.5 Mine, with theoretical analysis and industrial field test, the paper studied the deformation causes, deformation characteristics and support principles for track-dip roadway, and in-situ support test. The results show that, (1) the surrounding rock stress is higher, the lithology is poor and coal face mining effects, and bolt-grouting support method and its parameters are unreasonable, which is the main reason for the surrounding rock deformation and failure of track-dip roadway; (2) the principles of full-section support, strengthening bearing capacity of surrounding rock, and flexible shotcrete support are proposed. The technical parameters of the wire-rope mesh shotcrete structure, grouting bolt and grouting parameters are determined. The wire-rope mesh bolt-grouting support was carried out in repair of track-dip roadway. After renovation, the track-dip roadway was sustained on its both side coal faces mining, which could meet the production safety requirements. Therefore, the field test was successful.

in allusion of the problem of the gas controlling which is in the condition of the low content, high flow, high intensity mining of Tashan coal mine . In Datong mining area coal，carboniferous seam gas content is low and coal permeability is poor. Nowadays the methods of the conventional drainage at home and abroad can not solve the problem of the transfinite gas in Tashan coal mine. But using ground "L" type drilling method, we can extract the gas which lies in the high gas concentration area behind the upper corner of the stope face. The gas concentration in upper corner and in the return air lane will reduce significantly .In upper corner of the stope face ，the gas concentration will decrease by a large margin sharply .The gas concentration is only 0.05%. The effect of the gas extraction is obvious. It has reference uses for providing a new way for gas controlling in high-intensity mining fully mechanized caving mining face.

Abstract: Understanding the evolution law of the advance support pressure is an important basis for determining the advance support distance. Based on the engineering background of a deep mine thick seam fully mechanized caving face, this paper uses the methods of field monitoring, theoretical analysis and numerical simulation, the evolution law of advance support pressure is studied, and the reasonable advance support distance is determined. The following conclusions are drawn: Advanced abutment pressure is based on the time and space series, which is periodic, and the period is consistent with the roof breaking period; Compared with the analysis of the stress variation of "single measuring point", the advance support distance obtained by analyzing the stress variation characteristics of "whole monitoring area" is more reasonable and accurate; When no mining monitoring area is pushed, its stress curve presents the shape of "near-high, far-low". When mining monitoring area is pushed, its stress curve presents the shape of "near-horizontal", with the distance of near-horizontal span being 90m.

Aiming at the conditions of geological and production of the 4101 false slope mechanized mining face with large cutting and angle which is affected by the small fault structure, this paper analyses the influencing factors on stability of the "bracket-surrounding rock" system, and studies the initial pressure law on main roof of the 4101working face by the methods of UDEC numerical simulation, and theoretical calculation and field measurement of mine pressure behaviour. The results showed that: the initial pressure on main roof of 4101 false slope mechanized face with large cutting and angle present the features of segmented weighting, which avoids the large-scale effects on the working face by the breaking and weighting of whole main roof at the same time. However, it appears stress concentration on the roof of the lower end head and small faults area of the working face, and mine pressure behaviour is relatively strong, which should be focused on strengthening management and control.

Abstract: For effective prevention and control of mine bumps accident which happened in 73 on 29 island coal face, respectively, using the comprehensive index method and probability index method to evaluate macroscopic face impact ground pressure hazard, integrated strata movement factors and factors divided by the coal mining face impact ground pressure hazard area, finally to put forward the prevention and control of different solution, for the similar geological conditions provide certain reference prevention and control of the island coal face of impact ground pressure.

In order to solve the problem of low-permeability and high-gas short-distance coal seam group mining, a large amount of pressure relief gas from adjacent coal strata poured into the working face, adopt the method of combining theoretical analysis and numerical simulation, the analysis of the working face roof fissure and the relationship between the pressure relief seam gas enrichment, to simulate the mining working face roof fracture distribution and evolution law, puts forward the directional drilling pump mining goaf roof km upper agglomeration of the technical scheme of pressure relief gas, and combined with the actual conditions of 14301 working surface, the technical parameters of directional drilling arrangement for roof kilometer are determined in this paper. Field application shows that during the observation period of gas extraction in the roof kilometer drilling field, the concentration of gas extraction is always more than 25%, and the highest is 80%. The pure amount of gas extraction is between 2.0m3/min, and the effective extraction concentration lasts for a long time, achieving good gas extraction effect.

Abstract: In order to solve the problem of dust pollution in fully mechanized face, based on the theory of jet ventilation, this paper analyzes the basic principle of pressure wind shunting and sectionally control airflow to control dust, and put forward the existence of dust control surface,and based on the principle that the axial and radial outflow and the distance between the outlet and the working face coal wall must meet the minimum wind speed requirement, and established mathematical model, and revealed the relationship between the axial and radial outflow and the distance between the outlet and the outlet, and obtained the best matching relation of the key parameters of sectionally control airflow to control dust, and carry out application verification at the scene. The field application shows that according to the parameters of the air-control and dust-control system deduced from the theory, the dust concentration and dust-control efficiency of each point in the working face can be increased by more than 95%, and the overall dust-control efficiency can reach more than 98.4%. The high-concentration dust can be controlled in a certain area in the front of the working face, and the dust in the working personnel area can be controlled within 30 mg/m3. The dust control effect is remarkable, and the working environment is obviously improved, which verifies the validity of matching parameters.

Steeply inclined coal seam rock backfill mining can effectively restrain the dynamic phenomena of coal seam and roof and floor, and improve the stability of "support-surrounding rock" system. Based on the analysis of influencing factors of surrounding rock movement and deformation, by using UDEC numerical simulation software, the migration law of surrounding rock under different coal seam dip angle, buried depth, filling rate and filling strength conditions was studied. The results show that with the increase of coal seam dip angle, the deformation and disturbance range of roof decrease, while the displacement deformation and failure of floor increase gradually; the deeper the burial depth, the higher the stress concentration and maximum subsidence value of surrounding rock; with the increase of filling rate and filling strength, the displacement deformation amount of surrounding rock decreases and the stability increases. This study can provide a reference for safe and efficient mining of steeply inclined coal seam.

Many mines optimize their development or prepared roadway in protective coal pillar for buildings such as villages. To solve the problem of prediction for surface subsidence of roadway in protective coal pillar for buildings such as villages, the authors put forward the probability density function method in surface subsidence prediction of roadway layout in protective coal pillar for buildings, and the paper studied the parameters’ selection of surface subsidence rates and deviation of inflection point in the protective coal pillar roadways layout after it’s sheared. With the aid of Matlab platform, this paper studied surface movement deformation under this situation. Research and engineering application show that the probability density function method and surface subsidence parameters selection system of sub-critical mining condition for used for roadway layout in protective coal pillar of buildings is very appropriate. Combining research results of surface ultimate tensile deformation value for brick-concrete structure buildings, maximum surface subsidence value on condition of three roadway layout is about 1.24 times of double roadway layout in protective coal pillar.

With the increase of resources exploration in the western area of China,the contradiction of coordinated exploitation amongmulti-energy minerals wereappearedgradually in Ordos Basin, where enrichedoil, gas, coal,uranium,etc.The most prominently is between in-situ uranium leaching and coal mining. Take Tarangaole coal mine for example, the lithologic character of coal seam roof from341 boreholes inthe shaft area and outflow testdata wereanalyzed. It shows thatthemaximum drawdownof coal mining influenceto groundwater is about 224.33m, which might damage the hydrogeological conditions of uranium mining. According to the mining conditions, four kinds of coal mining methodswere analyzed, such as filling mining, room-pillar mining,strippillar mining and fully-mechanized caving method. The result shows that water-control mining on fully-mechanized caving methodwerefeasible and available.In order to optimize the mining plan for minimize the influenceto groundwater, themajor mining conditions were analyzed which includingdestruct height of overlying strata,thickness of aquifuge,characteristic of having aquifers, requirements of production, etc.The calculation result shows thatthe water inflow of the optimum mining face is 229m3/h whenaquifers were destroyedpartially, and the maximum drawdown of groundwaterwere 45.86mafter20 years, whichcan significantly reduce the influenceto uranium mining conditions.

Aiming at the problem of low stability and poor tracking performance of traditional shearer drum heightening technology, a control strategy of shearer drum heightening based on improved simulated annealing algorithm is proposed. Using the improved simulated annealing algorithm and taking ITAE as the performance index of the heightening system, the PID control parameters of the shearer heightening system are optimized. The simulation model of the control system is established by the Simulink toolbox of MATLAB. The control strategy has better robustness and signal tracking ability, which can provide a basis for the efficient production of coal.

In order to solve the problem that the pillar of hydraulic support is easy to be damaged by the impact load of stope, the impact model of the pillar hydraulic system is established by using AMESim simulation software on the basis of establishing the pillar model, the large flow safety valve model and the weight hammer model of the pillar hydraulic system. According to the national test requirements for the coal mine hydraulic support, the impact model of the pillar hydraulic system is established. The impact test was carried out on the column, and the impact response characteristics of the hydraulic system of the column were studied. The peak emulsified hydraulic pressure and its variation curve were obtained. The conclusion is that under the impact load, the strength of the secondary cylinder block of the hydraulic support column needs to be strengthened, and the response time of the hydraulic support column system to the peak pressure has a certain relationship with the impact quality and the drop height of the weight hammer, which provides an important basis for the design of liquid supply system and hydraulic support in coal mining face.

Coal permeability is a critical parameter for characterizing coalbed methane reservoirs and predicting their production; however, the role of the directional permeability in coalbed methane prediction has been neglected in previous studies. This study is focused on directional permeability, its existance is confirmed experimentally and a method is presented to determine the maximum and minimum principal permeability. In addition, the results showed that directional permeability measured on different coal samples varies significantly and is dependent on the effective stress. After determining the maximum and minimum principal permeability, the only functional relationship between the directional permeability and the effective stress is finally determined, which is helpful to accurately evaluate coalbed methane reservoirs.

Based on square transparent experimental tube with 1.5m long, photoelectrical transducer, pressure transducer and high-speed video camera was used to set up optical and pressure signal testing system. The obstacles are of 4 types (i.e. plates, triple prisms, cuboids and cylinders) and three kinds of blockage ratios (i.e. 20%, 40% and 60%). The results in the experiment show that: (1) plates and triple prisms increase flame speed and overpressure much larger, and cuboids are intermediate, while effects of cylinders are comparatively limited. (2) The obstacles can remarkably accelerate the flame velocity and pressure, and the irregularities of their surface are the main factor contributing to the flame turbulence. (3) There is a small difference in the initial stage of flame acceleration, and the flame speed and overpressure are increased obviously when the flame comes across the obstacles. The research has some effect on preventing and controlling explosion disaster of methane in mine and other combustible gases in pipelines.

Based on the analysis of hydrogeological characteristics and water inrush characteristics of a coal mine in Shanxi, the hydrogeochemistry and environmental isotope characteristics of various water bodies in the mining area were studied. It was determined that the source of the 01 working face water inrush was mixed water of Taiyuan Formation limestone aquifer and Ordovician limestone aquifer. The isotope method was used to quantitatively calculate that the Taiyuan Formation limestone aquifer accounts for 46% of the source water inrush from the working face, while the Ordovician limestone aquifer accounts for 54%. The research results showed that The isotope method can determine the main source of mine water inrush quantitatively and accurately, and provide a scientific basis for the development of effective water control measures.

In order to study the influence of grouting and filling on groundwater quality,the grouting and filling status in No.102 mining area of a mine in Huaibei Mining (Group) Co., Ltd. was used.Based on the study of the spatial relationship between mining fissures and separation zones, the grouting and filling tracing tests were carried out to simulate the grouting and fluid migration laws. The water samples were collected near the grouting station and underground for water quality detection. The results show that the height of caving zone is 12.0-12.8 m, the height of water conducting fracture zone is 46-52.24 m, the effective support area of grouting accounts for 70% of the total mined out area, and the grouting body forms an effective support function; the presence of tracer particles in the lane-way indicates that the grouting fluid has a certain hydraulic relationship with the lane-way; with the passage of time, the grouting fluid migration occurs, and the influence range of migration is within 1 km of the grouting hole. Internally, grouting slurry has no effect on drinking water in Quaternary loose strata, but has a partial effect on the quality of sandstone fissure water in coal strata at the local roof of coal seam. With the dilution of mine water, this part of influence can be neglected.

Taking Madaling landslide in Duyun Dity, Guizhou Province as an example, this paper simulated the excavation of coal bed based on Lagrangian fast difference algorithm of FLAC3D and revealed the deformation process and sliding mechanism of the slope. The results showed that (1) Coal bed excavation in Karst area has a significant impact on the stability of the slope. The excavation depth of coal bed controls the spatial distribution of vertical preferred structural plane of the slope body, the excavation width of coal bed controls the extension of vertical preferred structural plane, and the influence of the latter on the stability of the slope is much greater than that of the former;(2) The development process of Madaling landslide can be divided into two stages; (3)Due to unfavorable occurrence of stratum (NW282 ° < 18 °) and the existence of a large number of joint fissure water, a larger landslide disasters is being born.

The bonding behavior of liquid bridge in wet coal agglomeration is simulated by using the bonding particle model of discrete element method. The wet coal agglomeration model is constructed by using discrete element software EDEM and its secondary development. The collision behavior between the agglomeration and the flexible sieve plate is simulated.The rules of liquid bridge breakage of each part of agglomeration in collision process was studied. The effects of collision velocity, inclination angle of sieve plate and rotation velocity of agglomeration on the degree of depolymerization were analyzed.The results show that the breaking zone of the bond first occurs in the contact zone between the agglomeration and the screen surface, and then diffuses from the bottom to the top, from the center to the surrounding.After collision, the degree of Depolymerization increases with the increase of collision velocity and decreases with the increase of inclination angle of sieve plate, which is benefited frome the rotational speed of agglomeration.

Abstract: At present, the cantilever type roadheader control system has the problems of real-time data collection, inconvenient communication, and poor control of the control system. This paper designs a control system with DSP as the core. The control system uses DSP's abundant peripheral resources and superior data processing capabilities to complete the acquisition and calculation of the data of the roadheader's working conditions, real-time communication with peripheral devices, and realize the tunneling. The functions of precision cutting, automatic section control and remote monitoring of the machine cutting section provide technical support for the roadheader to adapt to automation and intelligent tunneling.

In view of the current situation that the detection technology and equipment of hydraulic support with large inclination is behind the development level of hydraulic support with large inclination. This paper developed the hydraulic support with large inclination, including main structure, rotary system, hydraulic system and test system, the technical problems of anti-down and anti-skid test of hydraulic support with coal seam inclination which is above 60 degrees、composite external loading test under inclined state and stepless adjustment of detection equipment’s height were solved. The testing equipment has a rotating angle of ±90°, average distributed load of 20 000kN, rated vertical external load of 11 000kN, rated horizontal external load of 6 000kN, rated lateral external load of 2 000kN, and table size of 7 200mm x 6 000mm.

In view of the difficulties in obtaining structural parameters and determining blade curvature which are the key components of mine main fan for performance analysis, this paper proposes a reverse modelling method for digital extraction and design of surface feature points based on the theory of reverse design and through the study of model reconstruction principle and parametric modelling method. Firstly，the digital scanning and the fan blade surface characteristics data of data are pre-processing, and then it extracts the characteristics of cross section contour line, and analyse its curvature characteristic points recognition, the surface reconstruction are processed by generating section spline curve. Finally, the reverse digital reconstruction of key components of mine main fan are realized, which provides an effective solution for the problem without the key structure parameters.

A coal industry efficiency evaluation index system including resources, economy and environment was constructed, and super efficiency SBM and Malmquist models were used to conduct horizontal, vertical, static and dynamic analysis of panel data of 20 coal resource-based provinces. The research found that: the longitudinal comparison showed that the overall industrial efficiency was on the rise, and the dynamic analysis by Malmquist showed that the improvement of efficiency mainly depended on technological progress, while the pure technical efficiency and scale efficiency did not play a role, indicating that the industrial scale and the allocation of organizational management level still need to be improved. Lateral comparison showed that the efficiency value, there is a big difference between the provinces, and there are different levels of volatility, found through the analysis of the dynamic Malmquist TFP is less than 1 provinces can be attributed to its technical efficiency lagging behind, that must be aware of the importance of technology progress for coal industry development, increasing the development of related technologies, pay attention to the defects of technical efficiency, improve the level of technology.