Self-circulation blasting pressure relief and permeability improvement system for high-gas dense coal seam

Abstract

The application discloses a high-gas dense coal seam self-circulation blasting pressure relief and permeability improvement system, which comprises the following steps: spraying microwave reflection material on the inner wall of a coal seam drilling hole to form a microwave reflection layer on the inner wall of the drilling hole, which can fully reflect waves; after the coal seam drilling hole is sealed, mixed gas of coal dust and gas is injected into the coal seam drilling hole, and the concentration of the coal dust and gas in the coal seam drilling hole is monitored by using a concentration detection probe; when the concentration of the coal dust and gas in the coal seam drilling hole reaches a set value, microwaves are continuously injected into the coal seam drilling hole by a microwave emission device, the microwaves are reflected by the microwave reflection layer, a high-temperature area is formed in the middle area of the drilling hole, and the mixed gas of the coal dust and gas is detonated, so that the purpose of drilling hole blasting is achieved. The method uses mixed gas of gas and coal dust as blasting material, which can not only significantly improve the blasting effect and reduce the dependence on traditional explosives, but also reduce the additional cost caused by storage and transportation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coal seam mining, and particularly relates to a self-circulation blasting pressure relief and permeability improvement system for high-gas and dense coal seams. BACKGROUND

[0002] In the process of coal mine production, gas and coal dust are two key substances with great potential value. The main component of gas is methane, which is flammable and explosive, so effective monitoring and extraction are needed to ensure the safety of coal mine operations. Generally, before coal production, ground stress measurement and gas concentration detection are performed to determine the gas extraction area and scheme. During production, gas extraction is carried out by drilling holes to concentrate and discharge gas to a safe area to prevent its accumulation in the coal seam. However, the current utilization of gas is limited, mainly through combustion to generate heat or direct discharge and storage. The combustion and storage methods not only have high costs but also have low utilization rates, failing to achieve full conversion and reuse of gas resources, resulting in energy waste and increased processing costs. At the same time, coal dust is an inevitable byproduct of coal mining and coal seam blasting, and due to its small particle size and high calorific value, when it is suspended in the air and the concentration reaches a certain standard, it is easy to explode due to a fire source. Therefore, coal dust treatment is also one of the key points of coal mine safety management. Currently, coal mines usually use water spraying, coal dust collectors, and other methods to control coal dust concentration to prevent its accumulation. However, these methods have certain limitations, such as incomplete collection and control of coal dust, high equipment cost, and high water consumption, and coal dust is often treated as waste without effective utilization. In fact, the high calorific value and flammability of coal dust indicate that it has certain energy characteristics, and if it can be recycled from the production environment, it will provide a new way for coal mine safety and economic benefits. SUMMARY

[0003] The main purpose of the present application is to provide a self-circulation blasting pressure relief and permeability improvement system for high-gas and dense coal seams, which uses gas and coal dust mixture as blasting material, significantly improving blasting effect, reducing dependence on traditional explosives, and reducing additional costs of storage and transportation.

[0004] To this end, the self-circulation blasting pressure relief and permeability improvement system for high-gas and dense coal seams provided by the present application includes the following steps:

[0005] Step 1: Spray microwave reflective material on the inner wall of the coal seam drill hole to form a microwave reflective layer on the inner wall of the drill hole that can fully reflect the waves;

[0006] Step 2: After sealing the coal seam drill hole, inject a mixture of coal dust and gas into the coal seam drill hole, and monitor the concentration of coal dust and gas in the coal seam drill hole using a concentration detection probe;

[0007] Step 3, when the concentration of coal dust and gas in the coal seam drilling reaches the set value, the microwave emission device continuously injects microwave into the coal seam drilling, the microwave is reflected by the microwave reflection layer, a high temperature area is formed in the middle area of the drilling, and the mixed gas of coal dust and gas is detonated, so as to achieve the purpose of drilling blasting.

[0008] Specifically, when the concentration of gas in the coal seam drilling is monitored to reach 9-10%, and the concentration of coal dust is monitored to reach 300-400g / m 3 , the microwave is injected into the coal seam drilling.

[0009] Specifically, the coal dust collected in the coal mine production process is ground to 8-12μm, and then conveyed to the mixer by air flow, mixed with the gas extracted by the coal seam gas extraction pipe, and then injected into the coal seam drilling.

[0010] Specifically, the orifice of the coal seam drilling is plugged by a plugging device, and a jet pipe inserted into the coal seam drilling is fixedly installed on the plugging device, the tail end of the jet pipe is connected with the outlet of the mixer through a conveying pipe, and a switch valve is arranged on the conveying pipe.

[0011] Specifically, the mixer comprises a gas storage tank, a coal dust storage tank and a mixing bin, the coal seam gas extraction pipe is communicated with the gas storage tank, the gas storage tank is communicated with the gas inlet of the mixing bin through a first pipeline, the coal dust storage tank is communicated with the coal dust inlet of the mixing bin through a second pipeline, and a coal dust grinder is communicated with the coal dust storage tank through a third pipeline, control valves are arranged on the first pipeline, the second pipeline and the third pipeline, air pressure gauges are arranged on the gas storage tank and the coal dust storage tank, and a pneumatic conveying system is arranged on the third pipeline.

[0012] Specifically, the mixing bin is divided into a plurality of mixing cavities distributed from top to bottom by a partition plate, the gas outlet pipe of the mixing bin extends to the bottom of the mixing bin, and a stirrer is arranged in the gas outlet pipe, the gas and the coal dust are mixed in each mixing cavity from top to bottom in turn, and then further mixed under the stirring action of the stirrer and discharged from the top of the mixing bin.

[0013] Specifically, the emission probe and the concentration detection probe of the microwave emission device are installed on the plugging device.

[0014] Specifically, the microwave reflection layer is an indium tin oxide, zinc oxide or titanium oxide ceramic film.

[0015] Specifically, the microwave reflection layer preparation process is as follows: after the ceramic powder, polyvinylpyrrolidone, deionized water and polyvinyl alcohol are stirred uniformly, the ceramic spraying slurry is prepared; then the ceramic spraying slurry is uniformly sprayed on the inner wall of the drilling hole by using a spray gun, the spraying process is from the hole bottom to the hole opening, and the telescopic spray rod of the spray gun moves along the axial direction of the drilling hole during the spraying process, so that the entire drilling hole wall is uniformly sprayed with the ceramic spraying slurry, and the microwave reflection layer is prepared after standing for 1-2 hours.

[0016] Specifically, the telescopic spray rod of the spray gun directly serves as the spray pipe, and two inlets are arranged on the spray gun, one of which is in communication with the ceramic spraying slurry source, and the other is in communication with the conveying pipe.

[0017] Compared with the prior art, the present application has the following beneficial effects: by spraying the microwave reflection material on the hole wall of the coal seam drilling hole to form a microwave reflection layer, and then mixing the extracted gas with the coal dust generated during the production activities and inputting them into the coal seam drilling hole, and using the microwave to explode the mixed gas to blast the coal seam, not only the blasting efficiency can be improved, but also the safety hidden danger of the coal mine can be effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 is a schematic diagram of the novel blasting method of coal seam provided by the embodiment of the present application;

[0020] Figure 2 is a schematic diagram of the mixer structure provided by the embodiment of the present application;

[0021] Figure 3 is a schematic diagram of the mixing bin structure provided by the embodiment of the present application;

[0022] Figure 4 is a schematic diagram of the slurry spraying equipment provided by the embodiment of the present application;

[0023] 1, coal seam drilling; 2, microwave reflection layer; 3, concentration detection probe; 4, microwave emission device; 5, mixer; 501, gas storage tank; 502, coal dust storage tank; 503, mixing bin; 5031, partition; 5032, mixing cavity; 5033, stirrer; 5034, gas outlet pipe; 504, first pipeline; 505, second pipeline; 6, coal dust grinder; 7, plugging device; 8, conveying pipe; 9, injection pipe; 10, emission probe; 11, gas extraction pipe; 12, on-off valve; 13, third pipeline; 14, pneumatic conveying system; 15, air pressure gauge; 16, slurry injection equipment; 161, slurry bin; 162, booster motor; 163, spray gun; 164, spray rod; 165, spray head; 166, trigger switch; 167, flow regulating valve; 168, spray width regulating valve; 169, slurry pipe; 17, PC end; 18, peeping probe. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0026] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0027] Reference Figures 1-4 A new blasting method for coal seams, comprising the following steps:

[0028] Step 1, spray microwave reflection material on the inner wall of the coal seam drilling 1, so that the inner wall of the drilling forms a microwave reflection layer 2 which can fully reflect the waves;

[0029] Step 2, after sealing the coal seam drilling 1, inject the mixed gas of coal dust and gas into the coal seam drilling 1, and monitor the concentration of coal dust and gas in the coal seam drilling 1 by using the concentration detection probe 3;

[0030] Step 3, when the concentration of coal dust and gas in the coal seam drilling 1 reaches the set value, continuously inject microwaves into the coal seam drilling 1 by the microwave emission device 4, the microwaves are reflected by the microwave reflection layer 2, forming a high temperature area in the middle of the drilling, and exploding the mixed gas of coal dust and gas, so as to achieve the purpose of drilling blasting.

[0031] The present application forms a microwave reflection layer 2 on the wall of the coal seam drilling 1 by spraying microwave reflection material, then mixes the gas and the coal dust generated by production activities and inputs them into the coal seam drilling 1, and uses microwave to explode the mixed gas to blast the coal seam, which not only improves the efficiency of blasting, but also effectively reduces the safety hazards of coal mines.

[0032] The inventor further found that the concentration of gas and coal dust in the coal seam drilling 1 has a significant impact on the blasting effect. When the concentration of gas in the coal seam drilling 11 reaches 9-10%, and the concentration of coal dust reaches 300-400g / m3, injecting microwaves into the coal seam drilling 11 can achieve good blasting effect. This is because when the concentration of gas is below the above range, the mixed gas cannot be detonated due to lack of sufficient combustible gas. When the concentration of gas reaches the highest explosion limit, the explosion power is cut off due to lack of oxygen, and even cannot be detonated. When the concentration of coal dust is less than 300g / m³, there is not enough combustible material, even if the concentration of gas is within the explosion limit, the explosion power is weak. When the concentration of coal dust is too high (more than 400g / m3), the oxygen in the air is occupied by a large amount of coal dust, and the mixture is not easy to form explosive gas uniformly, and the explosion power will be reduced or even cannot be detonated.

[0033] In actual design, the gas in the coal seam gas extraction pipe is injected into the mixer 5, the coal dust generated in the coal mining process is ground to 8-12μm, and then conveyed to the mixer 5 by air flow to mix with the gas uniformly, and then injected into the coal seam drilling 1 through the injection pipe 9. In this embodiment, the explosion raw materials are all derived from the actual production of coal mines, which can significantly improve the utilization efficiency of gas and coal dust, and further improve the environmental, economic and safety benefits.

[0034] The gas in this embodiment is collected during the gas extraction process, and is injected into the mixer 5. Coal dust is mainly generated during the mining and transportation of coal, and a portion of the coal dust is the original coal dust present in the cracks of the coal seam before the coal seam is mined. The collected coal dust is poured into the coal dust grinder 6. After the coal dust passes through the screen and the larger particles are screened out, the coal dust enters the grinding wheel group, and the coal dust particles are ground into powder with a diameter of about 10 μm. The coal dust particles can be floated in the air, and then the coal dust is transported to the mixer 5 by air flow through the pipeline.

[0035] Referring to Figure 1 and Figure 4 In some embodiments, the borehole of the coal seam drilling 1 is sealed by the obturator 7, and the injection pipe 9 inserted into the coal seam drilling 1 is fixedly installed on the obturator 7. The tail end of the injection pipe 9 is connected to the mixer 5 through the conveying pipe 8, and the on-off valve 12 is provided on the conveying pipe 8. The uniformly mixed gas and coal dust in the mixer 5 are conveyed to the injection pipe 9 through the conveying pipe 8, and enter the coal seam drilling 1 from the gas outlet of the injection pipe 9.

[0036] Referring to Figure 1 Specifically, the emission probe 10 of the microwave emission device 4 is installed at an angle that is aligned with the central axis direction of the drilling, and the microwave of the microwave emission device 4 is turned on to enter the drilling. The wave is totally reflected under the action of the microwave reflection layer 2, and the microwave is fold-reflected through the hole wall. Most of the reflected wave will pass through the middle region, so that a high-temperature zone is formed in the middle region of the drilling, and the high temperature ignites the gas and coal dust. When the concentration detection probe 3 detects that the concentration of the gas and the concentration of the coal dust in the coal seam drilling 1 reach the set value, the on-off valve 12 is closed, the microwave emission device 4 is started, and the microwave is injected into the drilling to ignite the mixed gas, so as to achieve the purpose of blasting the coal seam.

[0037] Referring to Figure 1 and Figure 2It needs to be explained that in some designs, the mixer 5 includes a gas storage tank 501, a coal dust storage tank 502 and a mixing bin 503, the coal seam gas extraction pipe 11 is connected with the gas storage tank 501, the gas storage tank 501 is communicated with the gas inlet of the mixing bin 503 through the first pipeline 504, the coal dust storage tank 502 is communicated with the coal dust inlet of the mixing bin 503 through the second pipeline 505, the coal dust grinder 6 is communicated with the coal dust storage tank 502 through the third pipeline 13, the first pipeline 504, the second pipeline 505 and the third pipeline 13 are all provided with control valves (not shown in the figure), the flow and opening and closing of each pipeline can be controlled through the control valves, the gas storage tank 501 and the coal dust storage tank 502 are each provided with a gas pressure gauge 15, the third pipeline 13 is provided with a pneumatic conveying system 14, the gas extracted by the coal seam gas extraction pipe is directly conveyed to the gas storage tank 501, and the ground coal dust is conveyed to the coal dust storage tank 502 through the airflow provided by the pneumatic conveying system 14, the gas in the gas storage tank 501 and the coal dust in the coal dust storage tank 502 are fully mixed in the mixing bin 503, and then conveyed to the injection pipe 9 through the conveying pipe 8, during the mixing process, the flow can be adjusted by using the control valves, and the gas pressure in the tank body can be monitored by using the gas pressure gauge 15, so as to ensure the safety of the tank body.

[0038] Referring to Figure 3 In some designs, the mixing bin 503 is divided into multiple mixing cavities 5032 distributed from top to bottom by a partition plate 5031, the gas outlet pipe 5034 of the mixing bin 503 extends to the bottom of the mixing bin 503, and a stirrer 5033 (impeller type) is further arranged in the gas outlet pipe 5034, the gas and the coal dust are sequentially mixed in each mixing cavity 5032 from top to bottom, and then further mixed under the stirring action of the stirrer 5033 and discharged from the top of the mixing bin 503, by designing multiple mixing cavities 5032 and making the airflow flow from bottom to top, the full mixing of the gas and the coal dust can be effectively ensured.

[0039] In some designs, the preparation process of the microwave reflection layer 2 is as follows:

[0040] Firstly, the target ceramic powder (such as zinc oxide, titanium oxide or indium tin oxide) is selected, a suitable solvent deionized water and a dispersant PVP are matched, the ceramic powder and the dispersant PVP are gradually added into the solvent, and are preliminarily dispersed under low-speed stirring, then are further treated by ultrasonic waves to break the particle agglomeration and realize uniform dispersion. In order to improve the stability of the solution and the adhesion of the coating, a proper amount of adhesive polyvinyl alcohol is diluted or concentrated according to the requirements of the shotcrete viscosity, and finally the ceramic shotcrete is prepared. In order to ensure the performance of the shotcrete, the uniformity of the particles can be monitored by means of a dynamic light scattering instrument, and the settlement of the solution is observed to optimize the dispersion system, and then the preparation of the ceramic shotcrete is completed.

[0041] Before spraying, first use slurry spraying device to test spray outside the hole to check if the slurry spraying device 16 is running normally, such as Figure 4 As shown in the figure, the slurry spraying device 16 includes a slurry bin 161 and a spray gun 163, the slurry bin 161 is connected with the spray gun 163 through a slurry pipe 169, a booster motor 162 is arranged on the slurry pipe, a central hole is arranged on the obturator 7 for the telescopic spray rod 164 of the spray gun 163 to insert, the ceramic slurry is delivered to the spray gun 163 after being pressurized by the booster motor 162, then the trigger switch 166 of the spray gun 163 is pulled, the spray rod 164 rotates under the action of the motor, and the ceramic slurry is sprayed from the spray head 165 at the front end of the spray rod 164 under the rotary drive of the motor, wherein the flow rate and the spray width can be adjusted by adjusting the flow rate adjusting valve 167 and the spray width adjusting valve 168 on the spray gun 163.

[0042] Then, the coal seam drilling 1 is sprayed: the spray rod 164 of the spray gun 163 is inserted into the coal seam drilling 1 from the central hole of the obturator 7, the spray flow is from the bottom of the hole to the hole, according to the length of the drilling, the spray rod 164 of the spray gun 163 needs to be connected, then the spraying of the ceramic slurry is started, the ceramic slurry is delivered to the spray gun 163 by the bin under the action of the booster motor 162, the trigger switch 166 of the spray gun 163 is pulled, and the ceramic slurry is sprayed from the spray head 165 under the rotary drive of the motor, the spray gun 163 rod moves along the axis of the drilling during the spraying process to uniformly spray the ceramic slurry on the entire drilling wall, after the spraying is completed, the microwave emission film is prepared after the slurry is dried after standing for 1-2 hours. After the spraying is completed, the spray rod 164 is withdrawn from the coal seam drilling 1, and then the spray pipe 9 is installed on the central hole, and subsequent inflation operation can be performed.

[0043] In addition, it is conceivable that, in order to simplify the structure and save costs, the telescopic spray rod 164 of the spray gun 163 can directly serve as the mixed gas spray pipe 9, only an inlet communicating with the delivery pipe needs to be additionally arranged on the spray gun 163, the mixed gas delivered by the delivery pipe enters the spray gun through the inlet, and then enters the drilling through the spray rod 163 of the spray gun, and a switch valve is also arranged on the slurry pipe. The functions of spraying the ceramic solution and injecting the gas are combined in the embodiment, and the automatic telescoping and rotation of the spray head can be realized by the motor, a peep probe 18 is installed at the front end of the spray head to cooperate with the PC end 17 to observe the spraying ceramic film, and the purpose is to check the integrity of the ceramic film. Of course, the spray pipe can also be separately arranged, and the spray pipe can be directly installed on the central hole of the obturator 7 after the spray gun 163 is withdrawn from the drilling.

[0044] Any of the technical solutions of the present application disclosed above, if it discloses numerical ranges, the disclosed numerical ranges are preferred numerical ranges, any person skilled in the art should understand that the preferred numerical ranges are only the values with more obvious technical effects or representative values among the many implementable values. Because there are too many values to enumerate, the present application discloses some values to illustrate the technical solutions of the present application, and the above-mentioned enumerated values should not constitute a limitation on the protection scope of the present application.

[0045] At the same time, if the above-mentioned present application discloses or involves mutually fixed connecting parts or structural parts, except otherwise stated, the fixed connection can be understood as: detachable fixed connection (for example, using bolt or screw connection), and can also be understood as: non-detachable fixed connection (for example, riveting, welding), of course, the mutually fixed connection can also be replaced by an integral structure (for example, using casting process integral forming manufacturing) (obviously, except for integral forming process).

[0046] In addition, the terms used to represent the position relationship or shape in any of the technical solutions of the present application disclosed above, except otherwise stated, its meaning includes the approximate, similar or close state or shape. Any component provided by the present application can be assembled from a plurality of individual components, or can be a single component manufactured by integral forming process.

[0047] The above-mentioned embodiments are only examples for clearly illustrating the present application, and are not limited to the embodiments. Based on the above-mentioned description, other different forms of changes or variations can also be made by those skilled in the art. Here, it is neither necessary nor possible to enumerate all the embodiments. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A self-circulation blasting pressure relief and permeability improvement system for high-gas dense coal seams, characterized in that, It comprises the following steps: Step 1, spraying microwave reflection material on the inner wall of the coal seam drilling hole to form a microwave reflection layer on the inner wall of the drilling hole which can fully reflect the waves; Step 2, after sealing the coal seam drilling hole, injecting the mixed gas of coal dust and gas into the coal seam drilling hole, and monitoring the concentration of coal dust and gas in the coal seam drilling hole by using the concentration detection probe; Step 3, when the concentration of coal dust and gas in the coal seam drilling hole reaches the set value, continuously injecting microwaves into the coal seam drilling hole by the microwave emission device, the microwaves are reflected by the microwave reflection layer to form a high temperature area in the middle area of the drilling hole, and the mixed gas of coal dust and gas is ignited to achieve the purpose of drilling blasting; When the gas concentration in the coal seam drilling hole reaches 9-10% and the coal dust concentration reaches 300-400 g / m 3 , the microwave is injected into the coal seam drilling hole. After grinding the coal dust collected in the process of coal mine production to 8-12μm, the coal dust is conveyed to the mixer by air flow, mixed with the gas extracted by the coal seam gas extraction pipe, and then injected into the coal seam drilling hole; The orifice of the coal seam drilling hole is sealed by a plugging device, and a jet pipe inserted into the coal seam drilling hole is fixedly installed on the plugging device, the tail end of the jet pipe is connected with the outlet of the mixer through a conveying pipe, and a switch valve is arranged on the conveying pipe; The mixer comprises a gas storage tank, a coal dust storage tank and a mixing bin, the coal seam gas extraction pipe is communicated with the gas storage tank, the gas storage tank is communicated with the gas inlet of the mixing bin through a first pipeline, the coal dust storage tank is communicated with the coal dust inlet of the mixing bin through a second pipeline, and a coal dust grinder is communicated with the coal dust storage tank through a third pipeline, control valves are arranged on the first pipeline, the second pipeline and the third pipeline, air pressure gauges are arranged on the gas storage tank and the coal dust storage tank, and a pneumatic conveying system is arranged on the third pipeline.

2. The high gas density coal seam self-circulation blasting pressure relief and permeability improvement system according to claim 1, characterized in that: The mixing bin is divided into a plurality of mixing cavities distributed from top to bottom by a partition plate, an air outlet pipe of the mixing bin extends to the bottom of the mixing bin, and a stirrer is arranged in the air outlet pipe, the gas and the coal dust sequentially pass through each mixing cavity from top to bottom to be mixed, and are further mixed under the stirring action of the stirrer and discharged from the top of the mixing bin.

3. The high gas density coal seam self-circulation blasting pressure relief and permeability improvement system according to claim 1, characterized in that: The emission probe of the microwave emission device and the concentration detection probe are both installed on the plugging device.

4. The high gas density coal seam self-circulation blasting pressure relief and permeability improvement system according to any one of claims 1-3, characterized in that: The microwave reflection layer is an indium tin oxide ceramic film, a zinc oxide ceramic film or a titanium oxide ceramic film.

5. The high gas content dense coal seam self-circulation blasting pressure relief and permeability improvement system according to claim 4, characterized in that, The preparation process of the microwave reflection layer is as follows: uniformly stirring ceramic powder, polyvinylpyrrolidone, deionized water and polyvinyl alcohol to prepare ceramic shotcrete, then uniformly spraying the ceramic shotcrete on the inner wall of the drilling hole by using a spray gun, the spraying process is from the hole bottom to the orifice, and the telescopic spray rod of the spray gun moves along the axis of the drilling hole during the spraying process, so that the entire drilling hole wall is uniformly sprayed with ceramic shotcrete, and the microwave reflection layer is prepared after standing for 1-2 hours.

6. The high gas content dense coal seam self-circulation blasting pressure relief and permeability improvement system, according to claim 5, characterized in that: The telescopic spray rod of the spray gun directly serves as the jet pipe, and two inlets are arranged on the spray gun, one of which is communicated with a ceramic shotcrete source, and the other is communicated with the conveying pipe.

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