A method and apparatus for coal seam co-mining based on rock mass mechanical strength

Abstract

This invention discloses a method and apparatus for co-mining coal seams based on rock mass mechanical strength. The mining method includes the following steps: In a mining roadway, a pre-splitting borehole is drilled horizontally along a direction perpendicular to the roadway's extension direction, extending to the gangue layer. Multiple pre-splitting boreholes are then drilled at intervals along the roadway's extension direction. A controllable shock wave device is placed in the pre-splitting borehole using a drill rod, causing micro-fractures in the gangue layer using the controllable shock wave device. A microwave generator is inserted into the pre-splitting borehole using a drill rod, causing the micro-fractures to develop and form a fracture network using microwave radiation generated by the microwave generator. The above steps are repeated to complete the pre-splitting work of multiple pre-splitting boreholes and then sealing them. A high-pressure water-sand mixture is injected into at least one pre-splitting borehole, further expanding and interconnecting the fracture network within the gangue layer. Coal and gangue are mined simultaneously using a coal mining machine, and the cut coal and gangue are transported to the surface and screened.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method and apparatus for mining coal seams in combination based on the mechanical strength of rock mass. Background Technology

[0002] my country's coal mining is mainly carried out using underground mining methods. With the depletion of shallow coal resources and the continuous increase in mining depth, the mining of extremely close-range thin coal seams is receiving increasing attention from the mining industry in my country and even the world.

[0003] Thin coal seams are widely distributed across 80 mining areas in my country, totaling more than 750 seams. Industrial reserves are abundant, reaching 9.83 billion tons, of which recoverable reserves are approximately 6.5 billion tons, accounting for about 20% of the total recoverable reserves. However, the mining of thin coal seams involves high labor intensity, extremely low mechanization, and low economic efficiency, leading to a widespread phenomenon of "mining thick seams and abandoning thin ones" in various mining areas. This results in a huge waste of coal resources and a significant mismatch between recoverable reserves and actual production. Thin coal seam output accounts for only about 10% of the national coal production. Safe and efficient mining of thin coal seams is a crucial way to improve coal resource recovery rates.

[0004] The pre-coal-forming sedimentary environment, such as crustal uplift and subsidence, changes in paleogeographic environment, glacial melting, and the compression of sediments like peat layers, causes fluctuations in coal seam thickness and the alternation of coal and rock strata. Under geological conditions with excessively hard interbedded rock or thick interbedded rock layers, the cutting efficiency and economic benefits of co-mining coal and gangue are significantly affected. Currently, some rock pre-splitting methods exist for mine roadway excavation faces that can generate through-fractures within the rock mass; however, the controlled shock waves create large blocks with low fracture density, which cannot meet the requirements of co-mining coal and gangue. Summary of the Invention

[0005] This solution addresses the problems and needs raised above by proposing a coal seam fusion mining method based on rock mass mechanical strength. The method achieves the aforementioned technical objectives and brings about several other technical benefits due to the adoption of the following technical features.

[0006] One object of the present invention is to provide a coal seam fusion mining method based on rock mass mechanical strength, comprising the following steps:

[0007] S10: Conduct mechanical testing and analysis on the gangue layer, and determine the pre-splitting borehole depth and spacing, microwave heating duration and high-pressure water injection pressure based on the rock mass mechanical strength test results;

[0008] S20: In the mining roadway, a pre-splitting borehole is drilled in the gangue layer in a horizontal direction perpendicular to the roadway extension direction using a drilling rig. Multiple pre-splitting boreholes are drilled sequentially at intervals along the extension direction of the mining roadway.

[0009] S30: The controllable shock wave device is placed in the pre-splitting borehole through the drill pipe, and the controllable shock wave device is used to create micro-cracks in the gangue layer.

[0010] S40: The microwave generator is sent into the pre-splitting borehole through the drill rod. The microwave radiation generated by the microwave generator causes the micro-fractures to develop further and form a fracture network.

[0011] S50: Repeat steps S30 to S40 to complete the pre-splitting work and sealing of multiple pre-splitting boreholes opened at intervals along the extension direction of the mining roadway.

[0012] S60: Inject high-pressure water-sand mixture into at least one pre-splitting borehole to further expand and interconnect the fracture network within the gangue layer;

[0013] S70: After the high-pressure injection of water-sand mixture, the coal mining machine is used to mine coal and gangue together, and finally the cut coal and gangue is transported to the ground and screened.

[0014] In this technical solution, firstly, the depth and spacing of pre-splitting boreholes, microwave heating time, and high-pressure water injection pressure are determined by conducting mechanical testing and analysis on the gangue layer. Then, a working position is set within the mining roadway, and a fixed drilling rig is installed so that it drills pre-splitting boreholes extending into the gangue layer in a horizontal direction perpendicular to the roadway's extension direction. Pre-splitting boreholes are then drilled sequentially and at intervals along the extension direction of the mining roadway. Next, a controllable shock wave device is placed in the pre-splitting boreholes via a drill rod, using the controllable shock wave device to induce micro-cracks in the gangue layer. The process involves several steps: First, a microwave generator is inserted into the pre-splitting borehole via a drill rod. The microwave radiation from the generator further develops the micro-fractures, forming a fracture network. After repeating this process for multiple pre-splitting boreholes, a high-pressure water-sand mixture is injected into each borehole. This further expands the fracture network within the gangue layer, allowing it to interconnect. Finally, after the high-pressure injection of the water-sand mixture, a coal mining machine is used for simultaneous coal and gangue mining. The excavated coal and gangue are then transported to the surface for screening. This mining method, based on controlled shockwave precision pre-splitting, solves the technical problems of high hardness and thick gangue interbedded in closely spaced coal seams, which are detrimental to coal seam mining. The pre-splitting direction and effect are controllable, and it features fast construction speed and high safety. Secondly, microwave radiation further develops the micro-fractures, optimizing the degree of pre-splitting. Furthermore, compared to existing explosive mining methods, this development method significantly improves mine production efficiency and economic benefits.

[0015] Furthermore, the coal seam fusion mining method based on rock mass mechanical strength according to the present invention may also have the following technical features:

[0016] In one example of the present invention, in step S20,

[0017] The depth of the pre-splitting boreholes is 10m to 100m. Among the multiple pre-splitting boreholes that are equally spaced along the extension direction of the mining roadway, the distance between two adjacent pre-splitting boreholes is 8m to 12m.

[0018] In one example of the present invention, in step S30, inducing micro-cracks in the gangue layer using a controllable shock wave device includes the following steps:

[0019] S31: Use a plugger to seal the port of the pre-splitting borehole and inject water into the pre-splitting borehole;

[0020] S32: The controllable shock wave device uses metal vapor generated by the electric explosion of metal wire to form plasma. The intense light radiation causes the molecular bonds of energetic materials in the water medium to break, thereby driving the water medium to form a controllable shock wave to create the micro-cracks in the gangue layer.

[0021] In one example of the present invention, step S30 further includes:

[0022] The controllable shock wave device is placed at different positions in the gangue layer in the pre-splitting borehole by the drill rods of different lengths, and the controllable shock wave generated by the controllable shock wave device creates micro-cracks at different positions.

[0023] In one example of the present invention, step S40 further includes:

[0024] The microwave generator is placed at different positions in the gangue layer of the pre-splitting borehole by the drill rods of different lengths to radiate microwaves, so that multiple microwave radiation positions arranged at intervals along their own extension direction in the pre-splitting borehole form a fracture network.

[0025] In one example of the present invention, in step S40, the radius of the slit network formed by the microwave generating device at the microwave radiation location is 4m to 6m.

[0026] In one example of the present invention, in step S40, the microwave radiation mode of the microwave generator is continuous loading, and the microwave heating time is 5 min to 10 min.

[0027] In one example of the present invention, in step S60, the water pressure injected into the pre-splitting borehole by the high-pressure water-sand mixture is 8 MPa to 12 MPa.

[0028] Another object of the present invention is to provide a coal seam fusion mining device based on rock mass mechanical strength, comprising:

[0029] The drilling rig, located in the mining roadway, is configured to drill pre-splitting holes extending into the gangue layer in a horizontal direction perpendicular to the roadway extension direction.

[0030] The pre-splitting assembly, which is installed on the drill rod of the drilling rig, is configured to generate micro-fractures in the gangue layer in the pre-splitting borehole and generate microwave radiation in the pre-splitting borehole to further develop the micro-fractures and form a fracture network.

[0031] The water injection machine has one end connected to a water tank containing a water-sand mixture, and the other end connected to the pre-splitting borehole via a water injection pipe. It is configured to pressurize the water-sand mixture and inject it into the pre-splitting borehole, thereby further expanding and interconnecting the fracture network within the gangue layer.

[0032] In one example of the present invention, the drilling rig opens a plurality of pre-splitting boreholes at intervals along the extension direction of the mining roadway, wherein the depth of the pre-splitting boreholes is 10m to 100m, and the distance between two adjacent pre-splitting boreholes in the plurality of pre-splitting boreholes arranged at intervals along the extension direction of the mining roadway is 8m to 12m.

[0033] In one example of the present invention, the pre-splitting component includes a controllable shock wave device and a microwave generator, wherein the controllable shock wave device is installed on the drill rod of the drilling rig when it is necessary to generate micro-fractures in the gangue layer in the pre-splitting borehole; and the microwave generator is installed on the drill rod of the borehole when it is necessary to further develop the micro-fractures in the pre-splitting borehole and form a fracture network.

[0034] The preferred embodiments of the invention will be described in more detail below with reference to the accompanying drawings, so as to facilitate an understanding of the features and advantages of the invention. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. The drawings are merely illustrative of some embodiments of the present invention and are not intended to limit the scope of the present invention to all embodiments.

[0036] Figure 1 This is a top view of coal seam mining according to an embodiment of the present invention;

[0037] Figure 2 for Figure 1 Sectional view along line AA;

[0038] Figure 3 This is a flowchart of a coal seam fusion mining method according to an embodiment of the present invention.

[0039] List of reference numerals in the attached diagram:

[0040] 110 mining tunnels;

[0041] Gangue layer 120;

[0042] Drill hole 121;

[0043] Drilling rig 130;

[0044] Drill pipe 131;

[0045] Controllable shock wave device 140;

[0046] Microwave generator 150;

[0047] Upper coal seam 160;

[0048] Lower coal seam 170;

[0049] Top plate 180;

[0050] Base plate 190;

[0051] Occlusion device 200;

[0052] Water inlet pipe 210;

[0053] Water pressure monitoring gauge 220;

[0054] Extending direction X;

[0055] Horizontal direction Y;

[0056] Depth direction Z;

[0057] Slit network A. Detailed Implementation

[0058] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0059] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, “an” or “a” and similar terms do not necessarily indicate a quantity limitation. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described object changes.

[0060] It should be noted that the coal seam structure, along the depth direction Z (which is perpendicular to the extension direction X and the horizontal direction Y), consists of the roof 180, the upper coal seam 160, the gangue layer 120, the lower coal seam 170, and the floor 190 from top to bottom. The mining roadway 110 is located between the roof 180 and the floor 190.

[0061] According to a first aspect of the present invention, a method for coal seam fusion mining based on rock mass mechanical strength is provided, such as... Figures 1 to 3 As shown, it includes the following steps:

[0062] S10: Conduct mechanical testing and analysis on gangue layer 120, and determine the depth and spacing of pre-splitting borehole 121, microwave heating time and high-pressure water injection pressure based on the rock mass mechanical strength test results;

[0063] S20: In the mining roadway 110, a pre-splitting borehole 121 is drilled in the gangue layer 120 along the horizontal direction Y perpendicular to the roadway extension direction X using a drilling rig 130. Multiple pre-splitting boreholes 121 are drilled sequentially at intervals along the extension direction X of the mining roadway 110. For example, the pre-splitting borehole 121 is drilled horizontally in the gangue layer 120 of the mining roadway 110, and the depth of the borehole 121 extends into the gangue layer 120. The depth of the pre-splitting borehole 121 is 80m, thereby ensuring the cutting efficiency of the coal mining machine during the entire coal and gangue mining process.

[0064] S30: The controllable shock wave device 140 is placed in the pre-splitting borehole 121 through the drill rod 131, and the controllable shock wave device 140 is used to generate micro-cracks in the gangue layer 120.

[0065] S40: The microwave generator 150 is fed into the pre-splitting borehole 121 through the drill rod 131. The microwave radiation generated by the microwave generator 150 causes the micro-fractures to develop further and form a fracture network A.

[0066] S50: Repeat steps S30 to S40 to complete the pre-splitting work of multiple pre-splitting boreholes 121 opened at intervals along the extension direction X of the mining roadway 110 and then seal them.

[0067] S60: Inject high-pressure water-sand mixture into at least one pre-splitting borehole 121, so that the fracture network A in the gangue layer 120 further expands and interconnects with each other; for example, high-pressure injection water-sand mixture can be injected into one of the pre-splitting boreholes 121; or for example, water-sand mixture can be injected into each pre-splitting borehole 121.

[0068] S70: After the high-pressure injection of water-sand mixture, the coal mining machine is used to mine coal and gangue together, and finally the cut coal and gangue is transported to the ground and screened.

[0069] The specific mining method is as follows:

[0070] First, mechanical testing and analysis of the gangue layer 120 were conducted to determine the depth and spacing of the pre-splitting boreholes 121, the microwave heating time, and the high-pressure water injection pressure. Then, a working position was set within the mining roadway 110, and a fixed drilling rig 130 was installed. The drilling rig 130 drilled pre-splitting boreholes 121 extending to the gangue layer 120 along a horizontal direction Y perpendicular to the roadway extension direction X. Pre-splitting boreholes 121 were drilled sequentially and at intervals along the extension direction X of the mining roadway 110. Next, a controllable shock wave device 140 was placed in the pre-splitting boreholes 121 via the drill rod 131. The controllable shock wave device 140 was used to break up the gangue layer 120. 20. Micro-cracks are generated. Next, the microwave generator 150 is sent into the pre-splitting borehole 121 through the drill rod 131. The microwave radiation generated by the microwave generator 150 causes the micro-cracks to develop further and form a crack network A. After the pre-splitting work of multiple pre-splitting boreholes 121 is repeated, high-pressure water-sand mixture is injected into the pre-splitting boreholes 121 in sequence, so that the crack network A in the gangue layer 120 further expands and interconnects with each other. Finally, after the high-pressure injection of water-sand mixture is completed, the coal and gangue are mined together using a coal mining machine. Finally, the cut coal and gangue are transported to the surface and screened.

[0071] This mining method utilizes controlled shock waves for precise pre-fracture, addressing technical challenges such as high hardness and thickness of interbedded rock during close-range coal seam mining. The pre-fracture direction and effect are controllable, offering advantages such as fast construction speed and high safety. Secondly, microwave radiation further develops tiny fissures, optimizing the degree of rock strata pre-fracture. Furthermore, compared to existing explosive mining methods, this development method significantly improves mine production efficiency and economic benefits.

[0072] In one example of the present invention, in step S20,

[0073] The depth of the pre-splitting borehole 121 is 10m to 100m. Among the multiple pre-splitting boreholes 121 that are equally spaced along the extension direction X of the mining roadway 110, the distance between two adjacent pre-splitting boreholes 121 is 8m to 12m.

[0074] The depth of the pre-splitting borehole 121 is 10-100m, thereby ensuring the cutting efficiency of the coal mining machine during the entire coal and gangue mining process; the spacing of the pre-splitting borehole 121 should be 8m-12m, thereby ensuring that the cracks in the gangue layer 120 are interconnected.

[0075] In one example of the present invention, in step S30, inducing micro-cracks in the gangue layer 120 using the controllable shock wave device 140 includes the following steps:

[0076] S31: Use the plugger 200 to plug the port of the pre-splitting borehole 121 and inject water into the pre-splitting borehole 121 (via the water injection pipe 210 provided on the plugger 200);

[0077] S32: The controllable shock wave device 140 uses metal vapor generated by the electric explosion of metal wire to form plasma. The intense light radiation causes the molecular bonds of energetic materials in the water medium to break, thereby driving the water medium to form a controllable shock wave to produce the micro-cracks in the gangue layer 120.

[0078] The mechanism of crack formation: radial compressive stress (compression) causes tangential tensile stress (tension), which in turn produces radial cracks; when the rock is subjected to radial compression, the rock stores elastic potential energy, and the release of elastic potential energy causes the rock particles to move centripetally, generating radial tensile stress and resulting in circumferential cracks; under the combined action of radial stress and tangential stress, shear stress is generated.

[0079] In other words, after the pre-splitting borehole 121 is completed by the drill rod 131, a controllable shock wave device 140 is installed on the drill rod 131 and penetrates into the gangue layer 120 in the pre-splitting borehole 121. Then, the port of the pre-splitting borehole 121 is sealed with a plug 200, and water is injected into the pre-splitting borehole 121 so that the water medium fills the pre-splitting borehole 121. Then, the controllable shock wave device 140 uses the metal vapor generated by the electric explosion of the metal wire to form plasma. The intense light radiation causes the molecular bonds of the energetic materials in the water medium to break, thereby driving the water medium to form a controllable shock wave to produce the micro-cracks in the gangue layer 120.

[0080] It should be noted that the plug 200 is fixed at the port of the pre-splitting borehole 121, and the drill rod 131 needs to pass through the packer 100 into the pre-splitting borehole 121. For example, an installation hole can be opened on the plug 200, and a sealing ring can be set at the installation hole to ensure the sealing between the drill rod 131 and the installation hole. The above-mentioned technology regarding the plug 200 is all prior art and will not be described in detail here.

[0081] In one example of the present invention, step S30 further includes:

[0082] The controllable shock wave device 140 is placed at different positions in the gangue layer 120 in the pre-splitting borehole 121 by the drill rods 131 of different lengths, and the controllable shock wave generated by the controllable shock wave device 140 creates micro-cracks at different positions.

[0083] For example, when the controlled shock wave device 140 performs shock wave pre-fracture in the pre-fractured borehole 121, the length of the drill rod 131 is extended sequentially at equal intervals in the pre-fractured borehole 121 to perform shock wave pre-fracture, thereby forming equally spaced micro-cracks.

[0084] For example, when the controlled shock wave device 140 performs shock wave pre-fracture in the pre-fractured borehole 121, the length of the drill rod 131 is shortened sequentially at equal intervals in the pre-fractured borehole 121 to perform shock wave pre-fracture, thereby forming equally spaced micro-cracks.

[0085] In one example of the present invention, step S40 further includes:

[0086] The microwave generator 150 is placed at different positions in the gangue layer 120 in the pre-splitting borehole 121 by the drill rods 131 of different lengths to radiate microwaves, so that multiple microwave radiation positions arranged at intervals along their own extension direction X in the pre-splitting borehole 121 form a fracture network A.

[0087] For example, when microwave radiation is applied to the pre-splitting borehole 121 by the microwave generator 150, the length of the drill rod 131 is extended sequentially at equal intervals in the pre-splitting borehole 121 to apply microwave radiation, thereby forming an equally spaced fracture network A.

[0088] For example, when microwave radiation is applied to the pre-splitting borehole 121 by the microwave generator 150, the length of the drill rod 131 is shortened sequentially by equal length to apply microwave radiation at equal intervals in the pre-splitting borehole 121, thereby forming an equally spaced fracture network A.

[0089] It is understood that the multiple microwave radiation positions of the microwave generator 150 arranged along the extension direction X of the pre-splitting borehole 121 correspond one-to-one with the multiple shock wave fracture positions of the controllable shock wave device 140 in real time.

[0090] In one example of the present invention, in step S40, the radius of the slit network A formed by the microwave generating device 150 at the microwave radiation position is 4m to 6m; that is, the radius of the slit network that each microwave generating device 150 can form through microwave radiation is in the range of 4m to 6m.

[0091] In one example of the present invention, in step S40, the microwave radiation mode of the microwave generating device 150 is continuous loading, and the microwave heating time is 5 min to 10 min.

[0092] Specifically, the microwave generator 150 can generate microwaves at a frequency of 2.45 GHz through electromagnetic oscillation, with a power of 0 to 20 kW. To ensure the development of micro-cracks and the formation of crack network A, the microwave radiation method is continuous loading, and the microwave heating time is 5 to 10 minutes. When the moisture content of the coal is low, the thermal stress generated by the selective thermal effect of the microwaves generated by the microwave generator 150 on different minerals in the coal body is the main influencing factor causing thermal cracking of the coal body. When the moisture content of the coal body is high, the splitting effect of the vapor pressure generated by the evaporation of water in the coal body under microwave radiation is the main influencing factor causing coal body cracking.

[0093] In one example of the present invention, in step S60, the water pressure injected into the pre-splitting borehole 121 by the high-pressure water-sand mixture is 8 MPa to 12 MPa.

[0094] The abrasive in the water-sand mixture can support the cracks expanded by high-pressure water injection after the water is discharged, preventing them from closing. Preferably, the high-pressure water injection pressure is 12 MPa, and the water pressure of the pre-cracked borehole 121 can be monitored by a water pressure monitoring gauge 220 (installed on the plugger 200), thereby ensuring that the cracks in the gangue layer 120 are interconnected.

[0095] According to a second aspect of the present invention, a coal seam fusion mining apparatus based on rock mass mechanical strength comprises:

[0096] Drilling rig 130 is installed in the mining roadway 110 and configured to drill pre-splitting boreholes 121 extending to the gangue layer 120 along the horizontal direction Y perpendicular to the roadway extension direction X.

[0097] The pre-splitting assembly is mounted on the drill rod 131 of the drilling rig 130 and is configured to generate micro-fractures in the gangue layer 120 in the pre-splitting borehole 121 and generate microwave radiation in the pre-splitting borehole 121 to further develop the micro-fractures and form a fracture network A.

[0098] The water injection machine has one end connected to a water tank containing a water-sand mixture, and the other end connected to the pre-splitting borehole 121 via a water injection pipe 210. It is configured to pressurize the water-sand mixture and inject it into the pre-splitting borehole 121, so that the fracture network A in the gangue layer 120 further expands and interconnects with each other.

[0099] First, mechanical testing and analysis of the gangue layer 120 were conducted to determine the depth and spacing of the pre-splitting boreholes 121, the microwave heating time, and the high-pressure water injection pressure. Then, a working position was set within the mining roadway 110, and a fixed drilling rig 130 was installed. The drilling rig 130 drilled pre-splitting boreholes 121 extending to the gangue layer 120 along a horizontal direction Y perpendicular to the roadway extension direction X. Pre-splitting boreholes 121 were then drilled sequentially and at intervals along the extension direction X of the mining roadway 110. Next, a controllable shock wave device 140 was placed in the pre-splitting boreholes 121 using drill rod 131, and the pre-splitting components were used to fracture the gangue layer 120. 20 generates micro-cracks; then, the pre-splitting component is sent into the pre-splitting borehole 121 through the drill rod 131, and the microwave radiation generated by the pre-splitting component causes the micro-cracks to develop further and form a crack network A; after the pre-splitting work of multiple pre-splitting boreholes 121 is repeated in sequence, the water injection machine injects high-pressure water-sand mixture into the pre-splitting boreholes 121 in sequence, so that the crack network A in the gangue layer 120 further expands and interconnects with each other; finally, after the high-pressure injection of water-sand mixture is completed, the coal mining machine is used to mine coal and gangue together, and finally the cut coal and gangue are transported to the surface and screened.

[0100] This mining device utilizes controlled shock waves for precise pre-splitting, addressing technical challenges such as high hardness and thickness of interbedded rock during close-range coal seam mining. The pre-splitting direction and effect are controllable, offering advantages such as fast construction speed and high safety. Secondly, microwave radiation further develops tiny fissures, optimizing the degree of rock strata pre-splitting. Furthermore, compared to existing technologies using explosives, this device significantly improves mine production efficiency and economic benefits.

[0101] In one example of the present invention, the drilling rig 130 opens a plurality of pre-splitting boreholes 121 at intervals along the extension direction X of the mining roadway 110, wherein the depth of the pre-splitting boreholes 121 is 10m to 100m, and the distance between two adjacent pre-splitting boreholes 121 arranged at intervals along the extension direction X of the mining roadway 110 is 8m to 12m.

[0102] The depth of the pre-splitting borehole 121 is 10-100m, thereby ensuring the cutting efficiency of the coal mining machine during the entire coal and gangue mining process; the spacing of the pre-splitting borehole 121 should be 8m-12m, thereby ensuring that the cracks in the gangue layer 120 are interconnected.

[0103] In one example of the present invention, the pre-splitting assembly includes a controllable shock wave device 140 and a microwave generator 150, wherein the controllable shock wave device 140 is installed on the drill rod 131 of the drilling rig 130 when it is necessary to generate micro-fractures in the gangue layer 120 in the pre-splitting borehole 121; and the microwave generator 150 is installed on the drill rod 131 of the borehole 121 when it is necessary to further develop the micro-fractures in the pre-splitting borehole 121 and form a fracture network A.

[0104] In one example of the present invention, the microwave radiation mode of the microwave generator 150 is continuous loading, and the microwave heating time is 5 min to 10 min.

[0105] Specifically, the microwave generator 150 can generate microwaves at a frequency of 2.45 GHz through electromagnetic oscillation, with a power of 0 to 20 kW. To ensure the development of micro-cracks and the formation of crack network A, the microwave radiation method is continuous loading, and the microwave heating time is 5 to 10 minutes. When the moisture content of the coal is low, the thermal stress generated by the selective thermal effect of the microwaves generated by the microwave generator 150 on different minerals in the coal body is the main influencing factor causing thermal cracking of the coal body. When the moisture content of the coal body is high, the splitting effect of the vapor pressure generated by the evaporation of water in the coal body under microwave radiation is the main influencing factor causing coal body cracking.

[0106] The foregoing description, with reference to preferred embodiments, details an exemplary implementation of the coal seam fusion mining method based on rock mass mechanical strength proposed in this invention. However, those skilled in the art will understand that various modifications and alterations can be made to the above specific embodiments without departing from the concept of this invention, and various combinations can be made to the various technical features and structures proposed in this invention without exceeding the protection scope of this invention, which is determined by the appended claims.

Claims

1. A method for mining coal seams in multiple layers based on rock mass mechanical strength, characterized in that, Includes the following steps: S10: Conduct mechanical testing and analysis on the gangue layer (120) located between the upper coal seam (160) and the lower coal seam (170), and determine the depth and spacing of the pre-splitting borehole (121), microwave heating time and high-pressure water injection pressure based on the mechanical testing and analysis results. S20: In the mining roadway (110), a pre-splitting borehole (121) is opened in the gangue layer (120) by a drilling rig (130) along the horizontal direction (Y) perpendicular to the roadway extension direction (X). Multiple pre-splitting boreholes (121) are opened sequentially at intervals along the extension direction (X) of the mining roadway (110). S30: The controllable shock wave device (140) is placed in the pre-splitting borehole (121) through the drill rod (131), and the controllable shock wave device (140) is used to generate micro-cracks in the gangue layer (120); wherein, the process of generating micro-cracks in the gangue layer (120) using the controllable shock wave device (140) includes the following steps: S31: The port of the pre-splitting borehole (121) is sealed with a plug (200), and water is injected into the pre-splitting borehole (121); S32: The controllable shock wave device (140) uses metal vapor generated by the electric explosion of metal wire to form plasma, and the intense light radiation causes the molecular bonds of the energetic materials in the water medium to break, thereby driving the water medium to form a controllable shock wave to generate the micro-cracks in the gangue layer (120); S40: The microwave generator (150) is sent into the pre-splitting borehole (121) through the drill rod (131). The microwave radiation generated by the microwave generator (150) causes the micro-fractures to develop further and form a fracture network (A). S50: Repeat steps S30 to S40 to complete the pre-splitting work and sealing of multiple pre-splitting boreholes (121) opened at intervals along the extension direction (X) of the mining roadway (110); S60: Inject high-pressure water-sand mixture into at least one pre-splitting borehole (121) to further expand and interconnect the fracture network (A) within the gangue layer (120); S70: After the high-pressure injection of water-sand mixture, the coal mining machine is used to mine coal and gangue together, and finally the cut coal and gangue is transported to the ground and screened.

2. The coal seam fusion mining method based on rock mass mechanical strength according to claim 1, characterized in that, In step S20, The depth of the pre-splitting borehole (121) is 10m~100m Among the multiple pre-splitting boreholes (121) equally spaced along the extension direction (X) of the mining roadway (110), the spacing between two adjacent pre-splitting boreholes (121) is... 8m~12m .

3. The coal seam fusion mining method based on rock mass mechanical strength according to claim 1, characterized in that, Step S30 further includes: The controllable shock wave device (140) is placed at different positions in the gangue layer (120) in the pre-splitting borehole (121) by the drill rods (131) of different lengths, and the controllable shock wave generated by the controllable shock wave device (140) creates micro-cracks at different positions.

4. The coal seam fusion mining method based on rock mass mechanical strength according to claim 1, characterized in that, Step S40 further includes: The microwave generator (150) is placed at different positions in the gangue layer (120) in the pre-splitting borehole (121) by the drill rod (131) of different lengths to perform microwave radiation, so that multiple microwave radiation positions arranged at intervals along their own extension direction (X) in the pre-splitting borehole (121) form a fracture network (A).

5. The coal seam fusion mining method based on rock mass mechanical strength according to claim 1, characterized in that, In step S40, the radius of the slit network (A) formed by the microwave generator (150) at the microwave radiation location is 4m to 6m.

6. The coal seam fusion mining method based on rock mass mechanical strength according to claim 1, characterized in that, In step S60, the water pressure injected into the pre-splitting borehole (121) by the high-pressure water-sand mixture is... 8MPa~12MPa .

7. A coal seam fusion mining device based on rock mass mechanical strength, characterized in that, A method for implementing coal seam fusion mining based on rock mass mechanical strength as described in any one of claims 1 to 6, comprising: A drilling rig (130) is installed in the mining roadway (110) and configured to drill pre-splitting boreholes (121) extending to the gangue layer (120) in a horizontal direction (Y) perpendicular to the roadway extension direction (X). The pre-splitting assembly, which is mounted on the drill rod (131) of the drilling rig (130), is configured to generate micro-fractures in the gangue layer (120) in the pre-splitting borehole (121) and generate microwave radiation in the pre-splitting borehole (121) to further develop the micro-fractures and form a fracture network (A). The water injection machine has one end connected to a water tank containing a water-sand mixture, and the other end connected to the pre-splitting borehole (121) via a water injection pipe (210). It is configured to pressurize the water-sand mixture and inject it into the pre-splitting borehole (121), so that the fracture network (A) in the gangue layer (120) further expands and interconnects with each other.

8. The coal seam fusion mining device based on rock mass mechanical strength according to claim 7, characterized in that, The drilling rig (130) drills multiple pre-splitting holes (121) at intervals along the extension direction (X) of the mining roadway (110), wherein the depth of the pre-splitting holes (121) is... 10m~100m Among the multiple pre-splitting boreholes (121) spaced at intervals along the extension direction (X) of the mining roadway (110), the spacing between two adjacent pre-splitting boreholes (121) is... 8m~12m .

9. The coal seam fusion mining device based on rock mass mechanical strength according to claim 7, characterized in that, The pre-splitting assembly includes a controllable shock wave device (140) and a microwave generator (150), wherein the controllable shock wave device (140) is installed on the drill rod (131) of the drilling rig (130) when it is necessary to generate micro-fractures in the gangue layer (120) in the pre-splitting borehole (121); and the microwave generator (150) is installed on the drill rod (131) of the borehole (121) when it is necessary to further develop the micro-fractures in the pre-splitting borehole (121) and form a fracture network (A).

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