A mine working face recovery system and method without ventilation

Abstract

The present application provides a kind of mine no ventilation working face mining system and method, it is related to coal mining technical field, the mining system includes L type working face;Coal winning machine, be arranged in L type working face, for completing coal wall cutting, roof support and coal transportation;Air door, be arranged in the position of transport drift near with auxiliary transport roadway junction, for closing the entrance of L type working face, to form closed space;Low temperature nitrogen injection system, be arranged in auxiliary transport roadway, its output end passes through air door, for the nitrogen gas that is transported to L type working face after cooling treatment, make the oxygen concentration in L type working face drop to below 5%, temperature is maintained at 20~25 ℃, and keep positive pressure state;Exhaust system, be arranged in return air roadway, its input end passes through air door, for the gas of L type working face is discharged.Compared with the traditional ventilation system, the present application system realizes the near zero carbon emission of coal mining process, can reduce more than 90% of gas emission and more than 95% of dust emission.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a mining system and method for unventilated working faces in mines. Background Technology

[0002] In underground coal mining, ventilation systems have always been a core technological support for ensuring mining safety. Since the application of mechanical ventilation technology in the 18th century, coal mining has gradually achieved large-scale mining from shallow to deep levels. Modern longwall mining has developed a mature technological system represented by the "U"-shaped ventilation system. This system forms a complete ventilation loop by arranging intake and return airways, using mechanical ventilation to provide fresh airflow to the working face, expel harmful substances such as gas and dust, and control temperature and humidity. In terms of specific implementation, existing ventilation mining technology mainly adopts the longwall fully mechanized mining technology, whose typical configuration includes a coal mining machine, scraper conveyor, hydraulic supports, and supporting ventilation facilities. The working face usually adopts a "one-in-one-out" or "two-in-two-out" roadway layout, and the ventilation system maintains a safe working environment. To prevent harmful gases from the goaf from seeping into the working area, it is often necessary to leave a 20-30m wide protective coal pillar or to backfill the roadway side.

[0003] While traditional ventilation mining technology plays a vital role in coal mine safety, it suffers from several significant drawbacks that severely restrict the economic efficiency and safety of coal mining. Firstly, the construction cost of ventilation systems is exorbitant, requiring multiple roadways to meet ventilation requirements. The excavation cost of each 2000m roadway reaches 32 million yuan. Adding the costs of ventilation equipment and maintenance, the ventilation cost per ton of coal reaches 50-90 yuan, accounting for 20%-25% of the total mining cost, significantly weakening the market competitiveness of coal products. Secondly, the increased number of roadways required to meet ventilation demands leads to a greater number of coal pillars for roadway protection, resulting in substantial coal resource losses. A single working face can lose up to 420,000 tons of coal resources as a result, with direct economic losses exceeding 200 million yuan. Thirdly, environmental pollution is a prominent issue. In existing ventilation systems, over 90% of the gas is directly released into the atmosphere through exhaust air, with annual emissions exceeding 18.7 million tons. Its greenhouse effect is equivalent to hundreds of millions of tons of carbon dioxide. Simultaneously, the annual dust emissions generated during coal mining are approximately 7.6 million tons, causing severe pollution to the mining area and surrounding environment. Fourth, safety hazards remain. Accidents involving ventilation and gas control account for approximately one-third of all coal mine accidents. The inherent reliability issues of ventilation systems make it difficult to completely eliminate gas accumulation and spontaneous combustion in mines with complex geological conditions. Fifth, technological equipment development is limited. Explosion-proof requirements result in heavy, energy-intensive, and low-level intelligent equipment. Many mature surface technologies cannot be directly applied underground, severely hindering the development of intelligent coal mining. Sixth, system adaptability is poor. Existing ventilation and mining systems are insufficiently adaptable to changes in geological conditions, failing to function effectively in complex geological conditions such as those without coal pillars or with high gas levels, thus limiting the scope for innovation in mining processes. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the purpose of this invention is to propose a mine unventilated working face mining system and method that can eliminate gas and dust emissions, achieving near-zero carbon emissions in the coal mining process.

[0005] To achieve the above objectives, the first aspect of the present invention provides a mine unventilated working face recovery system, comprising:

[0006] The L-shaped working face is formed by the working face cut and the transport roadway being vertically connected;

[0007] The three coal mining machines are located within the L-shaped working face and are used to complete coal wall cutting, roof support, and coal transportation.

[0008] An air damper is located near the connection point between the transport roadway and the auxiliary transport roadway, and is used to close the entrance of the L-shaped working face to form a closed space;

[0009] The cryogenic nitrogen injection system is located in the auxiliary haulage roadway. The output end of the cryogenic nitrogen injection system passes through the air damper and is used to deliver cooled nitrogen gas to the L-shaped working face, so that the oxygen concentration in the L-shaped working face is reduced to below 5%, the temperature is maintained at 20-25°C, and a positive pressure is maintained.

[0010] An exhaust system is located in the return air tunnel. The input end of the exhaust system passes through the air damper and is used to exhaust the gas from the L-shaped working face.

[0011] According to one embodiment of the present invention, it further includes two L-shaped directional long boreholes for collecting gas from the coal seam and suppressing gas accumulation in the L-shaped working face; the entrance end of one of the L-shaped directional long boreholes is connected to the surface, and the entrance end of the other L-shaped directional long borehole is connected to the auxiliary haulage roadway.

[0012] According to one embodiment of the present invention, the coal mining three-machine system includes a coal mining machine, a hydraulic support, and a scraper conveyor. The coal mining machine is equipped with a coal mining machine drum, which is disposed at the tail end of the scraper conveyor to perform overcutting to form an overcutting area at the coal wall. The length of the overcutting area is greater than the radius of the coal mining machine drum.

[0013] According to one embodiment of the present invention, there are multiple hydraulic supports arranged sequentially along the transport direction of the scraper conveyor, wherein at least one of the hydraulic supports near the tail end of the scraper conveyor is provided with a coal cleaning mechanical bucket, which is used to clean the coal and gangue mixture located in front of the scraper conveyor after the coal mining machine leaves the tail end of the scraper conveyor, so as to facilitate the smooth advancement of the scraper conveyor.

[0014] According to one embodiment of the present invention, the system further includes a transfer machine, a roadway belt conveyor, a coal chute, a belt incline, an uphill belt conveyor, a coal bunker, and a coal feeder. The transfer machine and the roadway belt conveyor are located within the roadway, and the transfer machine is used to transfer coal conveyed by the scraper conveyor to the roadway belt conveyor. One end of the belt incline is located below the roadway and is connected to the roadway via the coal chute. The coal bunker is located between the coal chute and the roadway and is connected to the coal chute. The other end of the belt incline is used to connect to the main haulage roadway. The coal feeder is located below the coal chute and is used to receive coal discharged from the coal bunker. The uphill belt conveyor is located within the belt incline and is used to transfer coal discharged by the coal feeder to the main haulage belt conveyor.

[0015] According to one embodiment of the present invention, it further includes multiple monitoring units for monitoring ambient temperature, ambient air pressure, concentrations of various harmful gases and dust concentrations, wherein the monitoring units are located at at least one of the following locations: inside the transport roadway, inside the belt conveyor uphill roadway, inside the ventilation door and inside the working face cut.

[0016] According to one embodiment of the present invention, the device further includes multiple respirator component replacement cabinets, which are disposed within the L-shaped working surface, and each respirator component replacement cabinet is equipped with a portable calcium hydroxide cleaning canister and a portable oxygen canister.

[0017] The second aspect of this invention provides a method for mining a non-ventilated working face in a mine, implemented based on the non-ventilated working face mining system described in the first aspect, the method comprising:

[0018] Install underground equipment under well-ventilated tunnel conditions;

[0019] The air damper is closed to achieve airtightness of the L-shaped working face;

[0020] Start the cryogenic nitrogen injection system and exhaust system to create a positive pressure oxygen-free working environment inside the L-shaped working face;

[0021] Coal mining operations are underway.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] 1. The mine ventilation-free longwall mining system of the present invention adopts an L-shaped longwall layout with a single roadway, completely changing the traditional ventilation mining method that requires "one-in-one-out" or "two-in-two-out" roadway layout. By eliminating ventilation in this local area, the system of the present invention reduces the roadway excavation cost of each longwall face from 32 million yuan to below 16 million yuan, a reduction of more than 50%. At the same time, due to the reduction in the number of roadways, the amount of coal pillars left for roadway protection is correspondingly reduced, and a single longwall face can recover approximately 420,000 tons more coal resources, directly creating economic benefits of over 200 million yuan and significantly enhancing the market competitiveness of coal products.

[0024] 2. The system and method of this invention construct a closed, oxygen-free mining environment through a cryogenic nitrogen injection system, achieving near-zero carbon emissions during coal mining. The cryogenic nitrogen injection system effectively blocks the emission pathways of methane and dust. Compared with traditional ventilation systems, the system of this invention can reduce methane emissions by more than 90% (annual reduction of over 16.8 million tons) and dust emissions by more than 95% (annual reduction of approximately 7.2 million tons). Its greenhouse gas emission reduction effect is equivalent to reducing hundreds of millions of tons of carbon dioxide emissions annually, and has a significant effect on improving the environmental quality of the mining area and its surroundings.

[0025] 3. The system and method of this invention fundamentally eliminate the risks of gas explosions and spontaneous combustion of coal through an oxygen-free positive pressure environment. When the oxygen concentration at the working face is below 5%, the gas loses its explosive potential; simultaneously, the positive pressure environment effectively isolates external gas infiltration, preventing harmful gases from the goaf from entering the working area. Combined with high-concentration gas extraction technology (extraction concentration >90%) and monitoring units, the incidence of safety accidents at the working face can be reduced by more than 90%, significantly improving the level of mine safety production.

[0026] 4. The system and method of this invention overcome the explosion-proof constraints of underground equipment, enabling the direct application of non-explosion-proof high-end equipment and intelligent systems in the mining area. In an oxygen-free environment, equipment does not need to meet explosion-proof requirements and can adopt lighter, lower-energy-consumption, and more intelligent mature surface technologies, such as industrial robots, intelligent sensing devices, and advanced control systems. This not only reduces equipment manufacturing costs and improves equipment performance but also provides a technological foundation for truly realizing intelligent and unmanned mining in coal mines.

[0027] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. Wherein:

[0029] Figure 1 This is a top view of a mine unventilated working face mining system according to an embodiment of the present invention.

[0030] Figure 2 This is a top view of coal production and transportation in a non-ventilated working face according to an embodiment of the present invention.

[0031] Figure 3 This is a cross-sectional view of a coal bunker in one embodiment of the present invention.

[0032] Figure 4 This is a schematic diagram of the L-shaped directional long borehole arrangement in the top plate crack zone according to one embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of the arrangement of monitoring points on the working face in one embodiment of the present invention.

[0034] Figure 6 This is a schematic diagram of the respirator component replacement cabinet in one embodiment of the present invention.

[0035] Figure 7 This is a schematic diagram of a hydraulic support for recovering tailings coal in one embodiment of the present invention.

[0036] Figure 8 This is a schematic diagram of the operation of the coal mining machine on the over-cutting area at the tail of the machine in one embodiment of the present invention.

[0037] Figure 9 This is a schematic flowchart of a mining method for a non-ventilated working face in an embodiment of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1-Coal mining machine; 2-Hydraulic support; 3-Scraper conveyor; 4-Transfer conveyor; 5-Belt conveyor in the roadway; 6-Coal chute; 7-Air door; 8-Cryogenic nitrogen injection system; 9-Exhaust system; 10-Working face cutter; 11-Transport roadway; 12-Belt conveyor uphill roadway; 13-Auxiliary haulage roadway; 14-Main haulage roadway; 15-Return airway; 16-Coal seam to be mined; 17-Stop mining line; 18-Uphill belt conveyor; 19 - Main conveyor belt; 20- Coal bunker; 21- Monitoring unit; 22- Coal feeder; 24- Goaf; 25- Breathing device component replacement cabinet; 26- Portable calcium hydroxide cleaning canister; 27- Portable oxygen canister; 28- Coal cleaning machine bucket; 29- Coal and gangue mixture; 30- Coal mining machine drum; 31- Overcutting area; 32- L-shaped directional long borehole; 121- First conveyor belt uphill roadway; 122- Second conveyor belt uphill roadway. Detailed Implementation

[0040] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the invention, and should not be construed as limiting the invention. Rather, embodiments of the invention include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0041] The following is for reference. Figures 1 to 8 This describes a mine unventilated working face recovery system according to an embodiment of the present invention.

[0042] like Figure 1 As shown, the mine unventilated working face mining system according to an embodiment of the present invention includes an L-shaped working face, three coal mining machines, an air door 7, a low-temperature nitrogen injection system 8, and an exhaust system 9.

[0043] The L-shaped working face is formed by the vertical connection between the working face cut-out 10 and the transport roadway 11. The transport roadway 11 is a horizontal roadway excavated along the coal seam strike, used for transporting coal and laying pipelines. The working face cut-out 10 is a connecting roadway excavated perpendicular to the transport roadway 11. The coal seam to be mined 16 is located in the coal body area extending outward from the intersection of the transport roadway 11 and the working face cut-out 10. The three mining machines are located in the L-shaped working face and are used to complete coal wall cutting, roof support, and coal transportation. The three mining machines typically include a coal mining machine 1, a hydraulic support 2, and a scraper conveyor 3. The coal mining machine 1 is responsible for coal wall cutting, the hydraulic support 2 provides roof support, and the scraper conveyor 3 undertakes the task of coal transportation. As the mining operation progresses, a goaf 24 is formed behind the L-shaped working face. The ventilation door 7 is located near the connection between the transport roadway 11 and the auxiliary haulage roadway 13, used to close the entrance of the L-shaped working face to form a closed space. Auxiliary haulage roadway 13 is a roadway in the mine specifically used for auxiliary transportation. The number of air doors 7 is set according to actual needs and is not limited. For example, there are 3 air doors 7. The cryogenic nitrogen injection system 8 is located in the auxiliary haulage roadway 13, and its output end passes through the air doors 7. It is used to deliver cooled nitrogen gas to the L-shaped working face, reducing the oxygen concentration in the L-shaped working face to below 5%, maintaining the temperature at 20-25℃, and maintaining a positive pressure state. The original temperature in coal mines is usually greater than 25℃. The nitrogen injection rate is adjusted in real time according to the working face space volume and oxygen concentration. The pressure value under positive pressure is selected according to actual needs. For example, the pressure value under positive pressure is 300-500 Pa. The cryogenic nitrogen injection system 8 has the function of separating nitrogen from the air and refrigeration. The specific type is not limited. For example, the cryogenic nitrogen injection system 8 can be a combination of a membrane separation nitrogen generator and an air conditioner. The exhaust system 9 is located within the return air roadway 15. It contains a built-in dust filter, with its inlet passing through the air damper 7. This filter removes dust-laden gas generated at the L-shaped working face, effectively eliminating dust. The return air roadway 15 is part of the mine's main ventilation network, guiding the purified air from the exhaust system 9 to the mine's main return air shaft, ultimately discharging it to the surface and reducing environmental pollution. The specific type of exhaust system 9 is determined based on actual needs and is not limited thereto. For example, the exhaust system 9 could be a blower.

[0044] The mine-free longwall mining system of this invention adopts an L-shaped longwall face layout with a single roadway, completely changing the traditional ventilation mining method that requires "one-in-one-out" or "two-in-two-out" roadway layout. The mine-free longwall mining system of this invention constructs a closed oxygen-free mining environment through a low-temperature nitrogen injection system 8, achieving near-zero carbon emissions in the coal mining process. The mine-free longwall mining system of this invention fundamentally eliminates the risks of gas explosion and coal spontaneous combustion through an oxygen-free positive pressure environment. When the oxygen concentration at the working face is below 5%, gas loses its explosive potential; simultaneously, the positive pressure environment effectively isolates external gas infiltration, preventing harmful gases from the goaf 24 from entering the working area.

[0045] In one example, the coal mining machine 1 is a high-power electrically traction coal mining machine equipped with a 2.5m diameter coal mining drum 30, featuring automatic height adjustment and memory cutting functions. The hydraulic support 2 adopts an electro-hydraulic control system, enabling automatic group support movement and support status monitoring. The scraper conveyor 3 adopts a heavy-duty cast-welded bottom structure, with a transport capacity of 3000 tons / hour.

[0046] Combination Figures 1 to 3 As shown, the mine's unventilated working face mining system also includes a transfer conveyor 4, a roadway belt conveyor 5, a coal chute 6, a belt incline 12, an incline belt conveyor 18, a coal bunker 20, and a feeder 22. The transfer conveyor 4 and the roadway belt conveyor 5 are located within the roadway 11. The transfer conveyor 4 is used to transfer coal conveyed by the scraper conveyor 3 to the roadway belt conveyor 5. One end of the belt incline 12 is located below the roadway 11 and is connected to the roadway 11 via the coal chute 6. The coal bunker 20 is located between the coal chute 6 and the roadway 11 and is connected to the coal chute 6. The other end of the belt incline 12 is used to connect to the main haulage roadway 14. The feeder 22 is located below the coal chute 6 and is used to receive coal discharged from the coal bunker 20. The incline belt conveyor 18 is located within the belt incline 12 and is used to transfer coal discharged by the feeder 22 to the main haulage belt conveyor 19.

[0047] The head of the scraper conveyor 3 is connected to the transfer conveyor 4 via a cross-side unloading method. The number of belt conveyor uphill roadways 12 is selected according to actual needs. For example, there are two belt conveyor uphill roadways 12: the first belt conveyor uphill roadway 121 and the second belt conveyor uphill roadway 122. Both the first belt conveyor uphill roadway 121 and the second belt conveyor uphill roadway 122 are coal transportation channels, with the second belt conveyor uphill roadway 122 serving as a backup transportation line. The roadway belt conveyor 5 uses a 1.4 m wide flame-retardant belt, and its transportation capacity matches that of the scraper conveyor 3. The coal bunker 20 serves as a coal storage and buffer adjustment mechanism; its capacity is selected according to actual needs. For example, the coal bunker 20 is designed with a capacity of 500 tons.

[0048] The coal transportation process in a mine using the unventilated working face mining system of this invention is as follows: Figure 2 As shown, the coal cut off by the coal mining machine 1 is transported to the transfer conveyor 4 via the scraper conveyor 3. The transfer conveyor 4 then transfers the coal to the roadway belt conveyor 5, and the coal subsequently enters the coal bunker 20 through the coal chute 6. The coal at the bottom of the coal bunker 20 flows into the coal feeder 22, which evenly distributes the coal to the uphill belt conveyor 18 in the uphill belt roadway 12. The uphill belt conveyor 18 uses a steep-angle belt conveyor, which ultimately transfers the coal to the main haulage belt conveyor 19 in the main haulage roadway 14, completing the entire transportation of coal from the L-shaped working face to the surface.

[0049] like Figure 4 As shown, in some embodiments, the mine's unventilated working face recovery system also includes two L-shaped directional long boreholes 32 for collecting gas from the coal seam and suppressing gas accumulation within the L-shaped working face. One of the L-shaped directional long boreholes 32 has its inlet end connected to the surface, while the other L-shaped directional long borehole 32 has its inlet end connected to the auxiliary haulage roadway 13. In one example, the boreholes are arranged with a horizontal spacing of 30 m and a vertical spacing of 44 m. Frequency conversion control ensures that the extracted gas concentration is greater than 90%, effectively controlling gas accumulation at the working face. The collected gas can be commercially utilized, reducing environmental pollution.

[0050] In some embodiments, such as Figure 8 As shown, the coal mining machine 1 is equipped with a coal mining machine drum 30, which is positioned at the tail end of the scraper conveyor 3 to perform overcutting, thereby forming an overcutting area 31 at the coal face. The length of the overcutting area 31 is greater than the radius of the coal mining machine drum 30. (Combined with...) Figure 1 and Figure 7 As shown, there are multiple hydraulic supports 2 arranged sequentially along the transport direction of the scraper conveyor 3. At least one hydraulic support 2 near the tail end of the scraper conveyor 3 is equipped with a coal-cleaning mechanical bucket 28, used to clear the coal and gangue mixture 29 located in front of the scraper conveyor 3 after the coal mining machine 1 leaves the tail end of the scraper conveyor 3, allowing the scraper conveyor 3 to advance smoothly. The coal-cleaning mechanical bucket 28 can be implemented by a combination of hydraulic cylinders and a mechanical arm. Through the overcutting zone 31 and the coal-cleaning mechanical bucket 28, the coal recovery rate is improved while ensuring the normal operation of the three coal mining machines.

[0051] like Figure 5As shown, in some embodiments, the mine's unventilated working face recovery system also includes multiple monitoring units 21 for monitoring ambient temperature, ambient air pressure, concentrations of various harmful gases, and dust concentration. The monitoring units 21 are located in at least one of the following locations: inside the transport roadway 11, inside the belt conveyor uphill roadway 12, inside the ventilation door 7, and inside the working face cut-out 10. The number and installation location of the monitoring units 21 are selected according to actual needs and are not limited thereto. A single monitoring unit 21 is used to install multiple sensors. The type and number of sensors used in each monitoring unit 21 are selected according to actual needs, such as: oxygen concentration sensor, nitrogen concentration sensor, methane concentration sensor, carbon monoxide concentration sensor, temperature sensor, air pressure sensor, and dust concentration sensor.

[0052] like Figure 6 As shown, in some embodiments, the mine's unventilated working face recovery system also includes multiple respirator component replacement cabinets 25. These cabinets 25 are located within the L-shaped working face and contain a portable calcium hydroxide cleaning canister 26 and a portable oxygen canister 27. The calcium hydroxide cleaning canister 26 and the oxygen canister 27 are used in conjunction. The number and location of the respirator component replacement cabinets 25 are determined according to actual needs and are not limited thereto. When workers need to enter the mine, they are protected with lightweight positive pressure oxygen respirators, weighing 6–8 kg. The respirator absorbs exhaled carbon dioxide and replenishes oxygen through the calcium hydroxide adsorbent in the portable calcium hydroxide cleaning canister 26, providing a continuous oxygen supply for 4 hours.

[0053] In some embodiments, the mine's unventilated longwall face mining system also includes a control system. This control system is communicatively coupled to the monitoring unit 21, the air door 7, the cryogenic nitrogen injection system 8, the exhaust system 9, and the three mining machines. The control system adjusts the nitrogen injection rate, gas extraction rate, and operating parameters of the three mining machines in real time based on monitoring data to ensure a stable environment and efficient equipment operation at the L-shaped working face. The unventilated longwall face mining system has automatic early warning and emergency response functions; when monitoring parameters exceed the set range, corresponding control measures are automatically activated. During L-shaped working face production, the L-shaped working face is sealed off through the air door 7, eliminating ventilation in that localized area. Necessary maintenance work is performed by workers wearing respirators entering the L-shaped working face; daily production is achieved through unmanned operation via the control system.

[0054] Combination Figures 1 to 9 As shown in the figure, this invention also proposes a method for mining a non-ventilated working face, based on the non-ventilated working face mining system described in the above embodiments. The implementation process of this method is as follows:

[0055] Step S102: Install the underground equipment under the ventilation conditions of the tunnel.

[0056] In this embodiment, the damper 7 is opened first, and key equipment such as the coal mining machine 1, hydraulic support 2 and scraper conveyor 3 are installed and debugged under ventilation conditions to ensure that they are in place and operate normally in a traditional ventilation environment.

[0057] Step S104: Close the damper 7 to achieve sealing of the L-shaped working surface.

[0058] In this embodiment, the L-shaped working surface is completely sealed by closing the damper 7, isolating external airflow and creating a foundation for an oxygen-free environment.

[0059] Step S106: Start the low-temperature nitrogen injection system 8 and the exhaust system 9 to create a positive pressure oxygen-free working environment inside the L-shaped working surface.

[0060] In this embodiment, the cryogenic nitrogen injection system 8 and the exhaust system 9 are activated to inject cooling nitrogen into the working face and remove the original gas. The oxygen concentration is reduced to below 5% through real-time control, the temperature is maintained at 20-25°C, and a positive pressure state is formed, thereby creating an oxygen-free mining environment.

[0061] Step S108: Coal mining operation is carried out.

[0062] In this embodiment, coal mining begins after the environment stabilizes. The coal mining machine 1 performs coal face cutting, and the coal is transported in an oxygen-free mining environment. The entire process is monitored by the control system to achieve safe and efficient mining. It should be noted that the coal mining machine 1 stops operating at stop line 17.

[0063] It should be noted that in the description of this invention, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0064] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0066] In the description of this invention, the terms "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0067] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0068] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A mining system for unventilated working faces, characterized in that, include: The L-shaped working face is formed by the vertical connection between the working face cut (10) and the transport roadway (11); The three coal mining machines are installed in the L-shaped working face and are used to complete coal wall cutting, roof support and coal transportation. The three coal mining machines include a coal mining machine (1), a hydraulic support (2) and a scraper conveyor (3). Multiple ventilation doors (7) are located near the connection between the transport roadway (11) and the auxiliary transport roadway (13) to close the entrance of the L-shaped working face to form a closed space; The low-temperature nitrogen injection system (8) is located in the auxiliary transport roadway (13). The output end of the low-temperature nitrogen injection system (8) passes through the air door (7) and is used to deliver cooled nitrogen to the L-shaped working face, so that the oxygen concentration in the L-shaped working face is reduced to below 5%, the temperature is maintained at 20-25°C, and a positive pressure is maintained. An exhaust system (9) is provided in the return air tunnel (15). The input end of the exhaust system (9) passes through the air door (7) and is used to exhaust the gas from the L-shaped working face. Two L-shaped directional long boreholes (32) are used to collect gas from the coal seam and suppress gas accumulation in the L-shaped working face; the entrance end of one of the L-shaped directional long boreholes (32) is connected to the surface, and the entrance end of the other L-shaped directional long borehole (32) is connected to the auxiliary haulage roadway (13). The conveyor includes a transfer machine (4), a roadway belt conveyor (5), a coal chute (6), a belt incline (12), an incline belt conveyor (18), a coal bunker (20), and a coal feeder (22). The transfer machine (4) and the roadway belt conveyor (5) are located in the transport roadway (11). The transfer machine (4) is used to transfer the coal conveyed by the scraper conveyor (3) to the roadway belt conveyor (5). One end of the belt incline (12) is located below the transport roadway (11) and is connected to the roadway belt conveyor (5) through the coal chute (6). The conveyor roadway (11) is connected, and the coal bunker (20) is located between the coal chute (6) and the conveyor roadway (11), and is connected to the coal chute (6); the other end of the belt conveyor uphill roadway (12) is used to connect with the main conveyor roadway (14); the coal feeder (22) is located below the coal chute (6) and is used to receive the coal discharged from the coal bunker (20); the uphill belt conveyor (18) is located in the belt conveyor uphill roadway (12) and is used to transfer the coal discharged by the coal feeder (22) to the main conveyor belt conveyor (19).

2. The mine unventilated working face recovery system according to claim 1, characterized in that, The coal mining machine (1) is equipped with a coal mining machine drum (30), which is positioned at the tail end of the scraper conveyor (3) to perform overcutting, so as to form an overcutting area (31) at the coal wall. The length of the overcutting area (31) is greater than the radius of the coal mining machine drum (30).

3. A mine unventilated working face recovery system according to claim 2, characterized in that, The hydraulic supports (2) are multiple and arranged sequentially along the transport direction of the scraper conveyor (3). At least one of the hydraulic supports (2) near the tail end of the scraper conveyor (3) is equipped with a coal cleaning mechanical bucket (28) for cleaning the coal gangue mixture (29) located in front of the scraper conveyor (3) after the coal mining machine (1) leaves the tail end of the scraper conveyor (3), so that the scraper conveyor (3) can advance smoothly.

4. A mine unventilated working face recovery system according to claim 1, characterized in that, It also includes multiple monitoring units (21) for monitoring ambient temperature, ambient air pressure, concentration of various harmful gases and dust concentration. The monitoring units (21) are located in at least one of the following locations: inside the transport roadway (11), inside the belt conveyor uphill roadway (12), inside the air door (7) and inside the working face cut (10).

5. A mine unventilated working face recovery system according to claim 1, characterized in that, It also includes multiple respirator component replacement cabinets (25), which are located in the L-shaped working surface. Each respirator component replacement cabinet (25) is equipped with a calcium hydroxide cleaning portable canister (26) and an oxygen portable canister (27).

6. A method for mining a non-ventilated working face in a mine, characterized in that, Based on the mine unventilated working face recovery system according to any one of claims 1 to 5, the method includes: Install underground equipment under well-ventilated tunnel conditions; Close the damper (7) to achieve airtightness of the L-shaped working face; Start the cryogenic nitrogen injection system (8) and the exhaust system (9) to create a positive pressure oxygen-free working environment in the L-shaped working face; Coal mining operations are underway.

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