62 results about "Hard coal" patented technology

The invention discloses a deep thick and hard rock stratum roof directional long drill hole staged fracturing weakening method and system, and relates to the technical field of coal mining. The method comprises the following steps: determining a fracturing target horizon according to mining area geological data and to-be-treated working face monitoring data; a drill site construction position is determined, and drilling track parameters are determined in the fracturing target horizon; a fracturing assembly is installed, fracturing construction parameters are determined, and the operation sequence of drilling construction and fracturing construction is determined; and drilling construction is conducted according to the operation sequence, fracturing construction is conducted through the fracturing assembly, and the stability condition of the roadway is monitored in the whole process and before and after. The technical scheme aims at weakening far-field strong stress of a top plate of a thick and hard coal rock stratum overlying a deep coal mine underground roadway, and is particularly suitable for design of a directional long drilling hole fracturing weakening scheme in the field of deep thick and hard rock stratum top plate pressure relief and roadway protection engineering. And the roadway deformation condition under the disturbance influence of advanced high supporting stress and mining strong stress of the working face is improved.

The invention relates to the field of coal mine tunnel deformation control, in particular to a coal mine tunnel floor heave prevention and treatment method based on bottom plate blasting pressure relief, which comprises the following steps: S1, determining a coal seam side support pressure curve and a coal pillar or entry retaining filling body side support pressure curve of a mining tunnel; the Rankine soil pressure theory is introduced to analyze the stress characteristics of a bottom plate of the mining roadway, and the coal seam side sliding body range and the coal pillar or entry retaining filling body side sliding body range are determined; s2, determining a blasting pressure relief rock stratum in the bottom plate; s3, determining a blasting pressure relief range; and S4, blasting is conducted on the determined blasting pressure relief range through blasting pressure relief drill holes. According to the method, the blasting pressure relief area is selected from the thick and hard coal seam bottom plate and is close to the sliding body, and floor heave prevention and control can be carried out on the basis of constructing the blasting pressure relief area in the minimum range; meanwhile, after the Rankine soil pressure theory is introduced to determine the slippage body, the reasonable blasting pressure relief area range is determined based on the slippage body and the supporting pressure.

The invention discloses a coal measure stratum hard coal rock composite structure modifying and cracking system and method. The system comprises a cracking device arranged in a directional drill hole extending into a cracking area, a high-pressure pump and a hydraulic pump, wherein the high-pressure pump and the hydraulic pump are arranged in a coal seam roadway and inject a high-pressure cracking agent into the cracking device. The method comprises the following steps: 1, determining the position of a modified cracking area of the overlying strata of the coal seam; 2, determining drilling parameters; 3, obtaining a directional drill hole; fourthly, a fracturing device is installed, and the hole is sealed; 5, calculating the fracture pressure of the rock stratum and carrying out primary water fracturing; 6, liquid nitrogen reinforced cracking of the rock mass; and 7, judging whether the coal measure stratum hard coal rock composite structure modification cracking effect is achieved or not. On the basis of hydraulic fracturing, liquid nitrogen fracturing and mechanical auxiliary fracturing are introduced and ingeniously combined, meanwhile, the fracturing means can be autonomously adjusted according to different working conditions, the hard roof fracturing modes are enriched, the method has the advantages of being small in engineering amount, low in pollution, high in safety and high in working efficiency, and the cracking effect is enhanced.

The utility model discloses a two-stage coal blending system based on coking coal grading and grading crushing, and belongs to the technical field of coal storage and blending. The coal blending system comprises a hard coal silo, a two-stage screening and crushing mechanism, a coal blending bunker and a coal bunker, a discharging port of the hard coal silo is connected with a feeding port of the first-stage screening and crushing mechanism through a belt, and a discharging port of the first-stage screening and crushing mechanism is connected with a feeding port of the coal blending bunker through a belt; a discharging port of the coal blending bin is connected with a feeding port of the second-stage screening and crushing mechanism through a belt, and a discharging port of the second-stage screening and crushing mechanism is connected with a feeding port of the coal bin through a belt. By adopting the coal blending system disclosed by the utility model, the characteristics of various coals are effectively utilized, and various coking coals are matched according to a proportion, screened and then crushed, so that the mixing uniformity of the coals is improved, the phenomenon of coarse coal leakage in the coal blending process is improved, the coke quality is improved, and the coal blending cost is also reduced.

The invention discloses a thin coal seam cutting device, a coal mining machine and a coal mining system.The thin coal seam cutting device comprises a roller and a plurality of first cutting teeth, the first cutting teeth are arranged on the end face of the first end of the roller at intervals, and compared with the first cutting teeth far away from the central axis of the roller, the first cutting teeth are smaller than the first cutting teeth; the tooth tips of the first cutting teeth close to the central axis of the roller are farther away from the end face of the first end of the roller, the tooth tips of the multiple first cutting teeth are located on a first arc face, and the first arc face is an arc face protruding in the direction away from the end face of the first end of the roller. Compared with the prior art that the end part of a feed cutting device is generally of a plane structure, the thin coal seam cutting device provided by the embodiment of the invention can more efficiently destroy a coal wall and cut the coal wall during feed, so that the coal mining speed and the coal mining efficiency are greatly improved, and in addition, the cutting efficiency of the thin coal seam is greatly improved. The thin coal seam cutting device provided by the embodiment of the invention is high in cutting strength and suitable for cutting harder coal rocks.

The invention relates to the technical field of coal deep processing equipment, and particularly discloses a coal preparation device which comprises coal receiving equipment, pre-crushing equipment, a coal distributing mechanism, a coal blending bin, coal blending crushing equipment and a coal tower which are sequentially arranged along a production process, and materials are conveyed among the equipment through belt conveyors; the coal receiving equipment comprises a coal receiving pit and a coal feeder arranged below the coal receiving pit; the coal distributing mechanism comprises a first coal distributing mechanism which is arranged in front of the pre-crushing equipment and is used for conveying coal types which do not need to be pre-crushed to the coal blending bin; the second coal distributing mechanism is arranged behind the pre-crushing equipment and is used for conveying the pre-crushed coal types to the coal blending bin; the plurality of coal blending bunkers are used for respectively storing different coal types, and electronic automatic batching scales are arranged below the coal blending bunkers; and iron removers are arranged between the coal receiving equipment and the pre-crushing equipment as well as between the coal blending bunker and the coal blending crushing equipment. The invention aims to solve the problems that coal with high hardness cannot be finely crushed and coal easy to crush is excessively crushed due to a process with coal blending equipment.

The invention provides a regional top coal caving dynamic control method and device for extra-thick hard coal. The method comprises the following steps: collecting top coal transportation state data; performing multi-source data processing by adopting a data-level, feature-level and decision-level fusion algorithm, and generating a top coal crushing degree evaluation result, a falling state recognition result and a top plate stability analysis result; performing multi-model collaborative reasoning by utilizing a D-S evidence theory, fuzzy logic and a Bayesian network according to a top coal crushing degree evaluation result, a falling state recognition result and a top plate stability analysis result, and generating opening and closing time prediction and control instructions of a coal discharge port of each region; and the control instruction is issued to a hydraulic support through an electro-hydraulic control system, differentiated opening and closing control over the regional coal caving openings is achieved, and a control strategy is dynamically adjusted according to real-time feedback data. According to the method, regional dynamic accurate control over the top coal caving process of the extra-thick hard coal seam is achieved, the top coal recovery rate is remarkably increased, the gangue mixing rate and the support instability risk are reduced, and the mining efficiency and safety are improved.

The utility model discloses an energy-absorbing pressure-resistant top beam of a top coal caving hydraulic support. The energy-absorbing pressure-resistant top beam comprises a top beam main body, a lifting plate and a pressure-resistant unloading assembly, the top beam main body has corresponding supporting force and is used for supporting a top plate; sinking grooves are formed in the supporting working face and used for containing corresponding parts; the lifting plate is erected above the sinking groove through the pressure-resistant unloading assembly, and an extrusion strip is arranged at the top end of the lifting plate to carry out corresponding support extrusion operation; the compression-resistant force unloading assembly comprises a deformation energy absorption part which is arranged in the sinking groove and located below the lifting plate, a supporting plate is assembled at the top end of the deformation energy absorption part and has corresponding supporting force, and the lifting plate is erected above the supporting plate through a lifting supporting column; the movable supporting blocks are fixedly connected and supported at the two ends of the bottom of the deformation energy-absorbing piece, balls are arranged at the bottom of the movable supporting blocks, and when the deformation energy-absorbing piece is stressed and deforms, the movable supporting blocks move in the frame moving direction in the sinking groove; the supporting springs are arranged between the movable supporting blocks and the corresponding inner walls of the sinking grooves in the frame moving direction, self-adaptive deformation is carried out when the movable supporting blocks move, a top coal seam top plate is stably supported, large and hard coal briquettes can be crushed through extrusion, and the situation that the large coal briquettes fall off to crush the top beam is prevented.

The invention relates to the technical field of coal seam gas extraction, in particular to a gas extraction method for a soft and hard coal composite area. In the drilling and production process, drilling cuttings and drilling machine mechanical parameters along with the coal seam; soft and hard coal area demarcation and characteristics are dynamically discriminated, and spatial interpolation and three-dimensional geological modeling are carried out in combination with the drilling spatial position; the boundary radiuses of the soft coal area, the hard coal area and the transition area of the soft coal and the hard coal are obtained through calculation, permeation increasing measures are arranged for drilling operation of the corresponding coal seam areas respectively, and hydraulic measure parameters are adjusted; and observing to obtain the fracture expansion range and the size of the cavity, and performing gas extraction when the conditions are met. According to the method, the gas extraction effect of the different coal seam composite area is improved by dynamically recognizing the soft and hard coal areas and combining the areas with precise gas treatment. The method can guide actual gas extraction engineering in the underground coal mine field, and is of great significance to the related fields of carbon sequestration, coal bed gas development and mine gas control.

The invention discloses a cutting device, a coal mining machine and a coal mining system.The cutting device comprises a roller and a plurality of first cutting teeth, the first cutting teeth are arranged on the end face of the first end of the roller at intervals, an included angle is formed between the central axis of each first cutting tooth and the axial direction of the roller, and the included angle is larger than or equal to 25 degrees; compared with the first cutting teeth far away from the central axis of the roller, the included angle between the central axis of the first cutting teeth close to the central axis of the roller and the axial direction of the roller is smaller. Thus, the cutting feed end of the cutting device provided by the embodiment of the invention is provided with the first cutting teeth with different inclination angles, multi-angle destructive force can be generated on the coal wall during cutting, the coal wall can be more efficiently destroyed and cut, the coal mining speed and the coal mining efficiency are greatly improved, and in addition, the coal cutting efficiency is improved. The cutting device provided by the embodiment of the invention is high in cutting strength and suitable for cutting harder coal rocks.

The present application belongs to the field of coal mine drilling, and particularly relates to a reamer for directional long drilling of coal seams; the reamer comprises a reamer barrel, a strip-shaped groove is uniformly formed on the inner wall of the reamer barrel along the circumferential direction, a cutter seat is slidably arranged in the strip-shaped groove, and a cutter wing is mounted on the cutter seat; a top plate penetrating through the cutter seat is further hingedly arranged on the cutter seat, a driving part for driving all the cutter seats to synchronously slide up and down in the strip-shaped groove is further arranged in the reamer barrel, and the cutter wing is used for adjusting the position of the cutter wing protruding from the outer wall of the reamer barrel and further adjusting the cutting diameter during the up-and-down sliding of the cutter seat in the strip-shaped groove; the driving part further cooperates with the top plate to drive the top plate to swing and remove the coal ash in the gap of the cutter wing; the present application reduces the abrasion from layered cutting, cooperates with self-cleaning and heat dissipation to maintain the cutting efficiency, dynamically adjusts the hole diameter and real-time performs the hole wall trimming during the reaming process, and forms a functional closed loop from the local to the whole to jointly solve the problems of tool life, chip removal and hole forming accuracy in the reaming of hard coal seams.

The invention discloses an active crushing control method of a hydraulic cutter type top coal caving support, and belongs to the technical field of coal mine intelligent control. The method comprises five steps of frame moving and locking, parameter setting, active crushing, pressure maintaining and expanding and retracting and resetting, crushing parameters can be adjusted in a self-adaptive mode, an extension structure is compatible, and dual-mode control and platform butt joint are supported. The method solves the problems of poor crushing and low recovery rate of traditional passive top coal caving, is suitable for various hard coal working faces, and can be used for transforming new supports and old supports.

The present invention relates to the technical field of coal mine equipment, and specifically to a roof stability monitoring and control and coal wall weakening method based on a hydraulic support. By constructing a roof stability monitoring and early warning model, the working face roof condition is monitored by a hydraulic support, and the hydraulic support is dynamically adjusted based on roof feature recognition and dynamic zoning to improve the crushing effect of thick hard coal seams, predict the roof condition in the working face advancement direction, change the hydraulic support pressure regulation strategy in real time, and eliminate the lag in the adjustment and adaptation of the existing pressure regulation strategy.

The invention discloses a mining device and a mining method suitable for a hard ore body, and belongs to the technical field of hard coal mining. The device comprises an unmanned mining car, an adjusting mechanical arm is installed on the unmanned mining car, a rotary rock breaking machine is detachably connected to the adjusting mechanical arm, and an ore shoveling bucket is installed on a car head of the unmanned mining car; a buffer assembly is installed at the joint of the adjusting mechanical arm and the rotary rock breaking machine, when the rotary rock breaking machine makes contact with ore for operation, the rotary rock breaking machine moves through a sliding rod and compresses a buffer spring, and then vibration force of the rotary rock breaking machine during ore excavation can be buffered; the vibration force transmitted to the adjusting mechanical arm or the unmanned mining vehicle is reduced, and when the rotary rock breaking machine makes contact with harder rock, the rotary rock breaking machine can be protected, and the service life of the rotary rock breaking machine is prolonged.

The invention discloses an intelligent cooperative system and method for graded utilization of multi-concentration gas in a deep coal mine. A high-concentration gas extraction unit conveys gas with the concentration exceeding 30% to the ground; the low-concentration gas movable in-situ utilization unit has three functions, gas with the concentration lower than 8% at different positions is collected and purified to serve as power fuel for underground movement of the gas, the surplus high-concentration gas after movement and energy consumption is merged into the high-concentration gas extraction unit, and the gas utilization rate is increased; meanwhile, in the moving process, an environment monitoring module carried by the device can carry out environment monitoring on different underground positions; according to the medium-concentration gas controllable combustion rock breaking unit, medium-concentration gas with the concentration ranging from 8% to 30% can be subjected to impact rock breaking through a water open fire restraining double-layer cavity combustion and explosion structure, and the purpose that existing rock breaking machinery is assisted in breaking hard rock (hard coal) is achieved. Under the regulation and control of a control center, the system formed by the equipment is mutually coordinated and matched, and the coal mine gas can be classified, divided into sources and accurately utilized underground.

The present invention relates to the field of coal mining, and in particular to an integrated support for gob-side entry driving with double roadway layout and a coal mining method with multi-functional use of one roadway. In combination with the limitations of the existing double roadway driving technology for working faces with extremely long advancing distances and the limitation that the gob-side entry driving technology results in isolated working faces due to skip mining, which cannot guarantee the efficient production of the working face. An integrated support for gob-side entry driving with double roadway layout and a coal mining method with multi-functional use of one roadway are proposed. The present invention is applicable to mining areas with relatively large coal seam thicknesses, and the coal mining roadways can be longitudinally arranged with "one high, one low, and horizontal stagger"; in mines with relatively hard coal quality, high gas content, and dynamic disaster problems in the coal seam and roof, the function of "multi-functional use of one roadway" can be fully realized. This method achieves the following effects: improving the recovery rate of coal resources in the mine; facilitating roadway maintenance; the gob-side entry driving along the roof can be used as a pressure relief roadway, a gas drainage roadway, or to realize functions such as weakening the top coal according to the actual situation of the mine, achieving the effect of "multi-functional use of one roadway" for the gob-side entry driving along the roof.

The application discloses a hard coal seam acoustic wave penetration method, comprising the following steps: sampling coal blocks of a hard coal seam to be penetrated, and obtaining tensile strength and shear strength of the coal blocks; drilling a working borehole in the hard coal seam, and impacting the working borehole at a set working strength, so that the strength of an impact wave generated by the impacting is lower than the strength at which the impact wave generates a crushing zone in the hard coal seam; the impact wave generated by the impacting cracks the hard coal seam around the working borehole, the impact wave attenuates after cracking the hard coal seam, and forms an acoustic wave, and the acoustic wave penetrates the hard coal seam. The application solves the problem that an effective high-strength sound source capable of being loaded to a coal seam is difficult to develop in the prior art. The application cracks the coal seam around the borehole by impacting, and the acoustic wave attenuated by the impact force excites the coal seam. The application can obtain a high-strength acoustic wave directly loaded to the hard coal seam. The application can promote gas desorption, and meets the demand of gas treatment.

The invention discloses a coal mine roof blasting scheme determining method and device, equipment, a medium and a product, and relates to the technical field of coal mine thick and hard roof blasting pressure relief. According to the engineering geological conditions, a blasting scheme determination expert system is adopted, and a coal mine roof blasting scheme of the target blasting area is obtained; a knowledge base of the blasting scheme determination expert system comprises a typical case database and a blasting rule knowledge base. The expert system is applied to determination of the coal mine roof blasting scheme, the expert system knowledge base is constructed according to the typical case database and the blasting rule knowledge base, and a basis is provided for intelligent optimization of the coal mine roof blasting scheme.

The application provides a phase-change detonation directional metal jetting permeability enhancement process method, which is suitable for coal seam roof and floor rock mass and medium-hard coal body. Single or multiple phase-change detonation metal jetting equipment is installed on a drill rod and pushed into a target area, and the target area is subjected to directional pressure relief and permeability enhancement by using the phase-change detonation metal jetting equipment. The phase-change detonation metal jetting equipment comprises a pressure-bearing packer, a perforator and a gas tank, the gas tank is filled with liquid carbon dioxide, and a phase-change exciter and a phase-change instantaneous delay exciter are arranged on the gas tank. The liquid carbon dioxide is excited to change into a gaseous state, high-pressure detonation energy is generated, a bullet head is directed to jet into the target area, and a permeability enhancement hole is formed. Single or multiple continuous composite permeability enhancement can be realized, and the permeability of the coal seam is improved. The phase-change detonation directional metal jetting equipment has a reasonable structure, is easy to operate, has a wide application range, and can effectively improve the gas extraction rate and the mining safety. The application has the advantages of high efficiency, safety and controllability, overcomes the limitations of traditional permeability enhancement methods, has a remarkable permeability enhancement effect, and has a wide application prospect.

The invention belongs to the technical field of coal mining, and provides a roller blasting height-adjustable open pit coal mine coal mining and stripping machine which comprises a walking chassis mechanism and a control transmission unit, and the control transmission unit is used for controlling the walking chassis mechanism and remotely transmitting information to a construction site console; a driving groove is formed in the upper portion of the walking chassis mechanism, and during use, a user remotely controls two second hydraulic rods fixedly installed on the inner wall of the driving groove to stretch out and draw back through a 4G transmission unit and a controller on a console of a construction site; according to the coal mining spiral roller drilling device, the two hydraulic rods can drive sliding protrusions fixedly installed at the other ends of the two second hydraulic rods to be arranged below a movable frame to slide on the inner wall of a driving groove, driving of the movable frame is further achieved, and in other words, when a coal mining spiral roller is drilled, a user can drive the coal mining spiral roller to move by driving the movable frame, and the drilling efficiency is improved. Therefore, the device can be stably inserted into the surface of a hard coal seam or a rock layer.

The present invention discloses a combined storage and improvement method of sand-carrying oxidant pulse injection-static fracturing for hard coal seams. The method comprises the following steps: first, a sand-carrying oxidant liquid is pulsed injected into the coal seam, and the oxidant liquid impacts the coal body under the water wedge degradation effect of the pulse wave. Simultaneously, the oxidant liquid contacts the coal body during the impact process to carry out an oxidation reaction, so that the coal body forms a fracturing weak surface and generates microcracks. Then, small quartz sand particles and the oxidant liquid are squeezed into the microcracks to expand and extend the microcracks, while increasing the contact area between the oxidant liquid and the coal body, thereby enhancing the oxidation effect and providing more fracturing weak surfaces for subsequent static fracturing. Subsequently, the sand-carrying fracturing fluid is injected into the coal seam for static fracturing, so that the microcracks in the fracturing weak surface converge, develop and expand longitudinally, and large quartz sand particles are squeezed into the expanded cracks to further expand and extend the hole. By alternately performing the oxidant pulse injection and static fracturing processes, a complex fracture network is continuously formed inside the coal seam, and finally in-situ oxidation-static fracturing progressive permeability enhancement of the coal seam is completed.

The invention discloses drilling equipment for coal field exploration. The drilling equipment comprises a mounting frame and a lifting frame. According to the drill bit, the standard drill pipe and the drill bit pipe which can be spliced are adopted, the outer surfaces of the standard drill pipe and the drill bit pipe are each provided with a chip groove and an internal thread groove, the chip grooves are used for discharging chips generated during drilling in the drilling process, and the internal thread grooves increase the friction force with soil layers located in the standard drill pipe and the drill bit pipe; a worker can reasonably increase or decrease the length of the standard drill pipe according to the drilling depth, the application range is wider, use is more convenient, the protruding points arranged on the bottom face of the drill pipe smash the soil layer in the rotating process of the drill pipe, continuous soil breaking and drilling are facilitated, and the drilling efficiency is improved. The drill bit is simple in structure and convenient to operate, has high crushing capacity especially for a hard coal seam, improves the drilling and sampling efficiency, soil layer samples are located in the standard drill pipe and the drill bit pipe, the distribution state of the soil layer samples is not changed, exploration and analysis of workers are greatly facilitated, and the working efficiency is improved.

The application discloses a coal mine roadway coal seam tunneling pressure relief device and method, and relates to the field of coal mine roadway coal seam tunneling pressure relief devices and methods. The pressure relief device comprises a caterpillar tractor and a drill rod. The drill rod comprises a drill rod body, a first oil cavity extending along the length direction of the drill rod body, and a second oil cavity extending along the radial direction of the drill rod body and being in communication with the first oil cavity. A piston rod is adapted in the second oil cavity, and the piston rod can switch between an extended position outside the second oil cavity and a retracted position inside the second oil cavity. A first grouting pipe is arranged along the extension direction of the first oil cavity, and a second grouting pipe is arranged along the extension direction of the second oil cavity and is in communication with the first grouting pipe. The second grouting pipe is sequentially provided in the second oil cavity and the piston rod. When hydraulic fracturing is needed for the drill hole drilled by the drill rod body, the piston rod is switched from the retracted position to the extended position to form a fracture hole. When pressure relief is needed for hard coal bodies, silent expansion liquid is injected into the fracture hole through the first grouting pipe and the second grouting pipe.

This invention discloses a hammer-type coal cutter, comprising a trolley, a motor, and a cutting drum. The trolley includes a frame, handles, and wheels, with the handles and wheels connected to the frame. The motor is mounted on the frame. The cutting drum includes a drum shaft and several hammers. The drum shaft is rotatably mounted on the frame and extends horizontally. One end of each hammer is movably connected to the drum shaft. The motor drives the drum shaft to rotate. The hammer-type coal cutter disclosed in this invention has high coal cutting efficiency. Through the high-speed rotation of the cutting drum, the hammers repeatedly strike the coal at the bottom of the drum, peeling away the hard coal layer by layer, saving manpower. Furthermore, the hammer-type coal cutter has a simple and compact structure, small dimensions, and the cutting drum can extend to the bottom of the bottom conveyor belt for operation, making it suitable for use in narrow roadways.

The invention relates to the production of low-CO2 wood pellets with high energy density by adding coal dust, such as wood, hard coal or lignite dust, during the production process.

The invention relates to the technical field of coal and coal bed gas co-mining, in particular to a coal bed gas multi-branch horizontal well ground coal extraction rapid pressure relief extraction system and method.The method comprises the steps that a ground horizontal well is arranged, specifically, a first drilling well is drilled to the position 60 m below a stable bed rock, and a second drilling well is drilled to the position within the range of 1-2 m from the end of a deflecting section to a coal bed top plate / coal bed bottom plate; the horizontal main branch section and the coal seam are drilled in parallel, windowing drilling of each branch section is completed in a backward mode from the far-end horizontal main branch section deviating from the first drilling well in sequence, the branch sections are provided with diameter-expanding coal digging caves, and a drilling track penetrating through the coal seam between a coal seam top plate and a coal seam bottom plate is formed; and drainage and mining equipment is installed for negative-pressure extraction, and rapid gas seeing and continuous high yield of the coal-bed gas well are achieved. The mode that the horizontal main branch section is drilled in the stable coal seam top plate or coal seam bottom plate is adopted, compared with coal seam drilling, the stable and hard coal seam top plate or coal seam bottom plate is easier, the well wall is more stable, collapse is not prone to occurring in the extraction process, and the method is suitable for long-term production.

The invention discloses a super-large mining height extra-thick hard coal top coal caving mining ratio determination method, which comprises the following steps: S1, carrying out stability analysis on a coal wall of a working surface, and determining a first mechanical mining height range H1 of a coal mining machine according to a strain range of the coal wall; s2, constructing a top coal body cantilever mechanical model, deducing to obtain a relational expression between the top coal thickness and the limit suspended top length, and determining a second machine mining height range H2 of the coal mining machine in combination with the coal caving step pitch parameter; and S3, comparing the first mechanical mining height range H1 with the second mechanical mining height range H2, if an overlapping area exists between the first mechanical mining height range H1 and the second mechanical mining height range H2, selecting the maximum value in the overlapping area as the mechanical mining height of the coal mining machine, and if the overlapping area does not exist between the first mechanical mining height range H1 and the second mechanical mining height range H2, selecting the maximum value in the first mechanical mining height range H1 as the mechanical mining height of the coal mining machine. The method for determining the top coal caving ratio of the extra-large mining height extra-thick hard coal has the advantages of being simple in step, high in safety performance and the like.

The present application relates to the technical field of coal seam mining, in particular to a coal pillar-free mining method suitable for thick and hard coal seam fully-mechanized caving face, comprising: first reinforcing the upper section track roadway; constructing a top breaking hole and a directional long borehole in the upper section track roadway; performing hydraulic fracturing through the directional long borehole; performing blasting top breaking through the top breaking hole; performing mining on the upper section working face and second reinforcing the upper section track roadway. The present application cuts off the stress transmission path of the goaf and the roadway roof rock stratum by directional blasting top breaking, improves the stress environment of the end of the working face surrounding rock; the thick and hard top coal is weakened by directional borehole hydraulic fracturing technology, which improves the top coal caving property and the coal recovery rate of the working face; in addition, the directional blasting top breaking and directional borehole hydraulic fracturing are performed before the mining of the working face, which does not increase the construction process during the mining of the working face.

The present invention relates to a method for highly efficient gas control in a large area of medium-hard coal seams throughout the whole time and space, belonging to the field of coal mine gas control. The method includes the following steps: Step S1, arranging a number of long directional boreholes along the coal seam inside the coal seam; Step S2, arranging a number of high-level directional branch long boreholes at the roof of the coal seam; Step S3, connecting to the gas drainage pipeline for gas drainage. This method realizes the highly efficient control of gas hazards in a large area, ahead of time, throughout the whole time and space from the source by developing the up and down mountain roadways. By means of hydraulic fracturing long directional boreholes, ordinary long directional boreholes, high-level directional branch long boreholes, etc., it can achieve the highly efficient control of gas in the whole time and space in the coal roadway, fracture zone, upper corner, coal face, adjacent seam, goaf during the mining process of medium-hard coal seams, solves the technical problems of the existing gas control methods that cannot be controlled ahead of time in terms of time, cannot cover the whole area in terms of space, and cannot achieve large-area ahead and highly efficient control in terms of efficiency, and reduces the engineering quantity and cost of gas control.