Oxygen-free working face construction method and mine safety mining system

Abstract

The invention discloses an oxygen-free working face construction method and a mine safety mining system, and aims to radically treat gas explosion and coal seam spontaneous combustion risks and simplify a mine system. The core is that an oxygen-free working face with the oxygen concentration smaller than or equal to 2% is constructed through a triple intelligent sealing door and a dynamic nitrogen injection gas barrier, and the necessary disaster conditions are cut off; a traditional multi-lane multi-system is reconstructed into a machine-rail integrated lane integrated system, a special air return lane and a large ventilator are omitted, and cost and energy consumption are reduced. And an electric trackless rubber wheel type air emergency vehicle is matched, so that 24-hour emergency operation of eight persons is guaranteed. According to the system, the safety risk is reduced by more than 99%, the annual comprehensive cost of a million-ton mine is saved by more than 1 billion yuan, and the system has safety, high efficiency and economical efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of coal mining, and specifically to a mining method and supporting system that eliminates the risks of gas explosion and coal seam spontaneous combustion by actively constructing an oxygen-free working face (oxygen concentration ≤ 2%), while simultaneously simplifying the mine system. Background Art

[0002] 1. Hazards of gas explosions and spontaneous combustion of coal seams: In traditional coal mining, gas explosions and spontaneous combustion of coal seams are a constant threat to coal mine safety. Spontaneous combustion of coal seams causes resource loss and waste every year, posing a threat to life safety. 2. Disadvantages of existing preventive measures: To overcome the above-mentioned difficulties, current measures adopted by coal mines, such as drilling to control gas, spraying inhibitors, and constructing grouting systems, are costly, restricted by geological conditions, and have unstable effects. For example, the directional drilling gas extraction technology disclosed in Chinese patent CN108756212A has an extraction efficiency of only 30%-50% under complex geological conditions; conventional mine fire prevention and extinguishing systems have an annual consumption cost of 20 yuan per ton of coal, and the fire prevention and extinguishing effect decreases by more than 40% in coal seams with an inclination greater than 25 degrees. At a key state-owned coal mine in Heilongjiang, disaster relief costs reached as high as 100 yuan per ton. 3. Limitations of Traditional Ventilation Systems: Traditional coal mining faces rely on extensive return air systems. Excavating return air tunnels is a massive undertaking, with excavation costs accounting for over 40% of total excavation costs and ventilation energy consumption accounting for 20% of the mine's total energy consumption. 4. Problems Caused by Gas Ventilation: Gas ventilation causes both environmental pollution and resource waste. my country's annual gas exhaust volume exceeds 15 billion cubic meters, accounting for approximately 81% of coal mine methane. This represents a high-quality resource valued at tens of billions of yuan, discharged as waste gas, generating an annual greenhouse gas impact of approximately 200 million tons of carbon dioxide equivalent. 5. Opportunities Presented by New Technologies: Intelligent unmanned operation technologies (such as CN112325678B) offer the potential for innovative mining models. However, existing intelligent mines remain stuck in the underlying logic of "allowing oxygen to exist" and rely on traditional ventilation systems. This has neither fundamentally addressed safety risks nor resolved the complex and costly issues of the system. Therefore, the industry urgently needs to develop an oxygen-free mining solution that eliminates risks at their source and streamlines and improves efficiency. Summary of the Invention

[0003] (I) Core Objectives. By constructing an oxygen-free working face with an oxygen concentration of ≤2%, we will eliminate the necessary conditions for gas explosions (requiring O2 ≥12%) and coal seam spontaneous combustion (requiring O2 ≥5%) at their source. Simultaneously, we will restructure the mine system from a "multi-lane, multi-system" model to a "single and dual-lane integrated model," achieving the triple goals of safe, efficient, and low-cost mining.

[0004] (II) Core technical solutions: 1. Construction of oxygen-free working surface: the core of risk eradication. Based on the natural low-oxygen environment of the coal seam (native oxygen ≤1%), a "triple-door physical isolation + dynamic nitrogen injection gas barrier" is used to prevent external oxygen intrusion and maintain an oxygen concentration of 1%-2% at the working face: 2. Triple intelligent sealed door system: installed at the entrance of the machine-track integrated tunnel, it forms a first-level buffer zone (O2 ≤ 8%) and a second-level buffer zone (O2 ≤ 5%). The door body is equipped with flexible sealing brushes (gap ≤ 5mm) and a nitrogen curtain generator to prevent air from mixing during transportation / passage; 3. Dynamic nitrogen injection system: Using 97% concentration nitrogen (oxygen content ≤ 3%), it adjusts according to the three levels of "normal micro-injection (20-50m³ / h), strong injection when the door is opened (150-200m³ / h), and emergency supplementary injection (200-300m³ / h)" to maintain a slight positive pressure (0.3-0.4kPa) in the door body area, prevent air leakage by leaking a small amount of nitrogen, and ensure that the oxygen concentration at the working face is stable at 1%-2%. 4. Mine system reconstruction: the key to cost reduction. Taking advantage of the fact that oxygen-free working faces require no ventilation, systematic simplification has been achieved: First, a revolution in the number of tunnels. The traditional four tunnels (two inlet and two outlet) have been eliminated, replaced by a single "machine-rail integrated tunnel" serving two working faces (one on each side). This tunnel integrates four major functions: rail transport (equipment and materials); belt transport (coal); gas extraction pipelines (Ø1000mm, extraction purity ≥90%); power lines, electromechanical equipment trains, and monitoring lines (sensors and control cables). Second, the ventilation system has been streamlined. The dedicated return air shaft, dedicated return air lane, and accompanying main ventilation fans were eliminated and replaced with a single set of small main ventilation fans (achieving an air volume of 3,000-5,000 m³ / h, only 10%-30% of that of a traditional mine, with one primary and one backup). All the mine's system tunnels are now exposed to fresh air. Because the working face does not require gas removal (gas is extracted through pipelines), the airflow does not mix with the gas, reducing ventilation energy consumption from 20% to less than 3%. Thirdly, emergency support is adapted. A "one-in-use, one-in-backup" air emergency vehicle is provided, allowing access to the work area through a temporarily sealed interface with a triple door, addressing equipment maintenance and emergency rescue needs in an oxygen-free environment.

[0005] (III) Core Innovations: 1. Subversion of underlying logic: Shifting from "allowing oxygen to exist and passively controlling risks" to "eliminating oxygen and proactively blocking conditions," eradicating gas and spontaneous combustion hazards; 2. System Reconstruction Breakthrough: Simplifying four lanes into one "united track and machine lane," streamlining the ventilation system and achieving a revolutionary reduction in construction and maintenance costs; 3. Dynamic Balancing Technology: Using "triple doors + staged nitrogen injection," this technology solves transportation and emergency response challenges in oxygen-free environments, ensuring system feasibility.

[0006] (IV) Beneficial Effects. 1. Safety: The risk of gas explosion and spontaneous combustion is reduced by more than 99%, fundamentally changing the "high-risk industry" attribute of coal mines. 2. Cost: The number of tunnels is streamlined, the ventilation system is simplified, and the investment in disaster prevention is reduced. The annual comprehensive cost of tens of millions of tons of mines is saved by more than 1 billion. Taking the tens of millions of tons of Shenhua Baode Coal Mine as an example, the absolute gas outburst volume is 129m3. 3 / min. If all gas were used for power generation, 240 million kWh of electricity could be generated annually, creating an economic benefit of 144 million yuan. 3. Efficiency and Resource Aspects: High-concentration gas power generation can generate annual revenue ranging from tens to hundreds of millions of yuan. A single tunnel serves two working faces, reducing excavation by 60% and system complexity by 50%, shortening the mining cycle, improving production efficiency, and significantly reducing the number of underground workers.

[0007] Description of the accompanying drawings. Figure 1 A schematic diagram is constructed for the oxygen-free working face of a coal mine, which clearly shows the layout of the coal mining working face and its surrounding tunnels. The specific contents are as follows: 1. Oxygen-free coal mining working face: the core area of coal mining operations, where coal mining is carried out in an oxygen-free environment; 2. Oxygen-free tunneling working face: the core area of coal mining operations, where tunneling operations are carried out in an oxygen-free environment; 3. Goaf: the area after coal mining is completed; 4. Stop mining line: the boundary marking the end position of coal mining operations; 5. Sealed: a closed facility used to isolate space and block gas circulation; 6. Gas extraction pipeline: a special pipeline system for extracting gas to ensure operational safety; 7. Intelligent sealing system: a combination of polyurea composite sealant and intelligent sealing door structure is used to isolate space and block gas circulation; the intelligent sealing system has a three-layer structure, which separates regional airflow and stabilizes the protective door of the ventilation system; 8. Mining area track lane (air inlet): a track lane serving as an air inlet channel, which transports fresh air to the working area Business area; 9. Mining area belt lane (return air): It has both belt transportation and return air functions, and discharges polluted air from the working area; 10. Coal mining working face machine-rail integrated lane: A comprehensive lane that integrates mechanical operation and rail transportation functions; 11. Adjustment window: A facility that controls the ventilation volume by adjusting the ventilation area; 12. Centralized rail lane (inlet air): The main rail lane with large-scale air intake provides fresh air flow for the mining area; 13. Centralized belt lane (return air): The main belt lane that undertakes the return air task, centrally discharges the return air from the mining area; 14. Air emergency vehicle: Used for emergency use in oxygen-free coal mining and excavation working faces. When manual intervention is required, personnel can drive the air emergency vehicle to enter the working face entrance, and workers wear oxygen cylinders to enter temporary emergency operations; 15. Nitrogen generator: Produce nitrogen to assist the ventilation system in regulating the gas environment; 16. Air compressor: That is, an air compressor, which provides compressed air for the system to support the operation of ventilation equipment and pneumatic tools. Appendix Figure 2This is a gas extraction diagram, clearly showing the layout of the extraction pipeline. The details are as follows: 1. Oxygen-free coal mining face; 2. Oxygen-free tunneling face; 3. Gas extraction pipeline; 4. Pipeline multi-parameter detector; 5. Vertical shaft; 6. Surface extraction pump station; 7. Gas power station; 8. Gas extraction direction.

[0008] Specific implementation method. This solution achieves safe operation of oxygen-free working face through "fixed isolation door + dynamic gas barrier + intelligent unmanned operation". The tunneling and coal mining stages share the same door system. The specific process is as follows: 1 Core facilities: fixed installation of triple doors (full-cycle isolation foundation). A triple intelligent sealing door is installed at the entrance of the machine-track tunnel as a permanent isolation facility. Specific parameters: (1) Spatial layout: The distance between the three doors is 15-20 meters (to meet the turning requirements of large equipment transportation), forming an independent closed area (first-level buffer, second-level buffer), and the door channel is 6.5m wide and 5.5m high (accommodating brackets, tunneling machines and other equipment); (2) Sealing treatment: The rock wall around the door is polished to a roughness of Ra ≤ 6.3μm, and a high-pressure airless spraying device (0.8-1.2MPa pressure) is used to spray polyurea composite sealant (two layers totaling 3mm) to ensure that the air leakage rate of the sealing layer is ≤ 0.1m³ / h; 300mm is installed on the edge of the channel Long flexible sealing brushes (gap ≤ 5mm) and a matching nitrogen curtain generator (flow rate 50m³ / h) are used to block air intrusion when the door is opened. (3) Functional configuration: integrated infrared sensor (sensing distance 5m), pressure sensor (accuracy ±0.01MPa), gas sensor (O2 / CH4 monitoring accuracy ±0.1%), supporting ground remote opening and closing and automatic linkage. 2. Excavation stage: Nitrogen is injected into the door area to create an oxygen-free environment. (1) Establishment of a gas barrier in the door area. After the triple gate is installed, 97% nitrogen (oxygen content ≤ 3%) is injected into the three gate intervals (first buffer, second buffer and the passage leading to the tunneling head). Parameters: initial nitrogen injection flow rate: 80-120m³ / h, pressure 0.4-0.6MPa; nitrogen is used to form a high-pressure gas barrier in the gate interval, naturally displacing the original air in the interval (discharged from the temporary exhaust hole at the tunneling head), and real-time monitoring of oxygen concentration to: the tunneling operation area (from the tunneling head to the third gate) oxygen concentration ≤ 2%; the second buffer zone (from the second to the third gate) oxygen concentration ≤ 5%; the first buffer zone (from the first to the second gate) oxygen concentration ≤ 8%; there is no need to inject nitrogen into the working face, and only the gas barrier in the gate interval is used to block the external air to maintain an oxygen-free environment. (2) Oxygen-free tunneling operation process. Equipment and control: An intelligent tunneling machine with three-dimensional laser guidance (positioning accuracy ± 10mm) is used, along with an intelligent anchor drill and concrete sprayer, and ground remote control is achieved through 5G + industrial Ethernet. Operation steps: The tunneling command is issued from the ground, and the tunnel boring machine advances according to the preset profile (cutting depth 0.8m / cycle); the intelligent anchor drilling machine (inter-row spacing 800×800mm) and the concrete spraying machine (support thickness 100mm) are started simultaneously to form a stable tunnel; the coal and gangue are transported out through the machine-track integrated tunnel belt conveyor and sent to the ground through the triple-door passage (the nitrogen curtain is automatically activated when the door is opened, and the interval pressure is restored within 3 minutes after closing). (3) Gas maintenance during tunneling.Normal nitrogen injection: Inject nitrogen in small amounts at a rate of 20-50 m³ / h to maintain a slight positive pressure of 0.3-0.4 kPa in the portal area (adjusted in real time by a pressure sensor) to prevent the intrusion of external air; Abnormal handling: If the oxygen concentration in the area is detected to be greater than 3%, the nitrogen injection flow rate will be automatically increased to 200-300 m³ / h, and excavation will be stopped at the same time to check for seal leakage (such as brush wear) until normal operation is restored. 3 Coal mining stage: Reuse the portal area to achieve oxygen-free mining. (1) Equipment entry and working face preparation After the excavation is completed and the machine-track tunnel is opened and the cut is opened, the original triple door is directly reused without adjusting the door position; transporting coal mining equipment (hydraulic supports, coal mining machines, etc.): when the equipment approaches, the door body infrared sensing linkage opens (the first → second → third lanes are delayed by 5 seconds in sequence), and strong nitrogen injection (150-200m³ / h) is started simultaneously to maintain the interval pressure and prevent air intrusion; after the equipment passes, the door body closes in sequence, and the interval pressure (0.3-0.4kPa) is restored within 30 seconds to ensure a stable oxygen concentration. (2) Gas control during mining. There is no need to inject nitrogen into the coal mining working face. Only nitrogen injection (20-50m³ / h) is used to maintain a slight positive pressure through the door body interval. The gas barrier is used to block the external air, so that the working face naturally maintains an oxygen concentration of 1%-2%; the coal produced by mining is transported out through the machine-track tunnel belt and through the preset channel of the door body, and the nitrogen curtain is used for synchronous protection to maintain pressure balance. (3) Gas extraction coordination. A 1000mm Φ corrosion-resistant extraction pipeline is laid in the integrated machine-track tunnel, connected to a surface intelligent pumping station (variable frequency speed regulation). The extraction flow rate (10,000 m³ / h) is adjusted based on the pressure differential between the working face and the mining area (0.5-1.0 kPa) to ensure gas purity ≥ 90% (a laser analyzer monitors in real time, automatically alarming if it is <90%). 4. Full-cycle safety assurance. Real-time monitoring: Sensors (O2, CH4, temperature, and pressure) are deployed between the portal and the working surface. Data is transmitted back to the ground every 10 seconds, and an audible and visual alarm is triggered in the event of an abnormality. Emergency measures: When the oxygen concentration on the working surface is greater than 3% or the gas concentration in the portal is greater than 1%, the system automatically starts: the nitrogen injection flow rate is increased to 200-300m³ / h, the equipment is shut down, and the portal is locked. An air emergency vehicle is equipped (with a 24-hour compressed air reserve for 8 people). The vehicle is equipped with portable oxygen cylinders and a backup vehicle air source. The vehicle enters the work area through the portal and maintains an oxygen-free environment in the area throughout the fault handling process. Emergency maintenance personnel must wear oxygen cylinders when leaving the air emergency vehicle to ensure one is in use and one is in reserve.

[0009] 1: Sealing and opening and closing system design of triple intelligent sealing door.

[0010] 1. Door Structure Overview. The triple-layer intelligent sealing door is a full-section steel structure (sizes match those of the integrated machine and track tunnel: 6.5m wide x 5.5m high). It is arranged along the tunnel axis in the following order: "First Isolation Door (G1), Second Buffer Door (G2), and Third Operation Door (G3)." Spaced 15-20m apart, they form a primary buffer zone (G1-G2) and a secondary buffer zone (G2-G3). The door body is constructed of Q690 high-strength low-alloy steel (50mm thick), offering impact and corrosion resistance, making it suitable for the high humidity and dust conditions underground.

[0011] 2. Core sealing system design (ensuring air leakage rate ≤ 0.1m³ / h) (1) Peripheral static sealing. Rock wall pretreatment: The tunnel rock wall at the door installation location needs to be laser leveled (flatness error ≤ 3mm), and two layers of polyurea composite sealant (bottom layer 1.5mm + surface layer 1.5mm) are sprayed using high-pressure airless spray equipment (pressure 1.0-1.2MPa). The glue layer extends 500mm outside the edge of the door body to form a flexible sealing transition zone of "rock wall-glue layer-door body" to avoid gaps caused by rigid contact. Door body edge sealing: "U-shaped" hydrogenated nitrile rubber strips (cross-sectional size 30mm×20mm, hardness 60±5Shore A) are inlaid around the door body to form an interference fit with the rock wall sealing glue layer (compression amount 15%-20%). The static sealing pressure at room temperature is ≥0.6MPa to ensure that the nitrogen barrier does not leak. (2) Bottom belt channel dynamic sealing. A 1.8m wide × 1.5m high belt channel is reserved at the bottom of the door body (aligned with the belt in the machine-track lane), and a "two-stage sealing component" is installed on the edge of the channel: Level 1: 300mm long wear-resistant flexible sealing brush (flame retardant material, made of PA66 nylon, monofilament diameter 0.3mm, density 100 pieces / mm²), close to the belt surface (contact pressure 5±1N / m), blocking dust and airflow; Level 2: Synchronous nitrogen curtain (5 fan-shaped nozzles are arranged along the width of the channel, with a total flow rate of 20m³ / h and a pressure of 0.3MPa), forming an airtight barrier to prevent external air from invading through the belt gap when the door body is opened. (3) Instantaneous sealing compensation when the door body is opened. During the door opening and closing process (opening angle 0°→90°), a "dynamic nitrogen curtain system" is equipped: annular nozzles (diameter 50mm) are arranged along the top and both sides of the door, with 20 nozzles with a 3mm aperture. They are automatically activated 10 seconds before opening, with a flow rate of 50m³ / h (G1 / G2) and 80m³ / h (G3, near the working area), forming an "air curtain" to block air mixing until 30 seconds after the door is completely closed.

[0012] 3. Intelligent opening and closing control system (1) Opening and closing drive and linkage logic. It adopts hydraulic drive (working pressure 16-20MPa), and the opening and closing time of a single door is ≤30 seconds (to meet the rapid passage of large equipment). It is equipped with a two-way limit sensor (accuracy ±2mm) to ensure that the door body is closed in place (the gap with the sealant layer is ≤1mm). The linkage control rule is: when the equipment is transported to the working surface, the first door (G1) is opened. After the equipment enters the area between G1 and G2, G1 is closed, and the second door (G2) is opened. After the equipment enters the area between G2 and G3, G2 is closed, and the third door (G3) is opened. When the equipment passes, G3 is closed. (2) Perception and adaptive adjustment. The door is equipped with integrated multi-dimensional sensors: infrared beam sensors (with a detection range of 8m, identifying equipment outlines and triggering opening and closing commands); pressure sensors (located at the four corners of the door, monitoring the sealing surface pressure in real time, and automatically adjusting the hydraulic system pressure when the deviation is greater than 0.1MPa); gas sensors (monitoring the O2 / CH4 concentration in the monitoring area, automatically locking the door and issuing an alarm when the concentration exceeds the standard); the ground monitoring center can remotely and manually intervene in the opening and closing process, and is equipped with an emergency mechanical opening and closing device (hand-cranked, suitable for power outage scenarios).

[0013] 4. Maintenance and life guarantee. (1) Seal replacement cycle: The polyurea sealant layer should be inspected every 2 years and repaired locally when the wear is greater than 30%. The rubber strips and sealing brushes should be replaced every 6 months (spare parts are stored in the air emergency vehicle). (2) Drive system maintenance: The hydraulic oil should be filtered every 3 months (accuracy 10μm), and the cylinder seals should be replaced every year to ensure that the opening and closing movements are free of jamming. (3) Life indicators: The door body is designed to have a service life of ≥10 years and a number of opening and closing times of ≥100,000 times (to meet the mining cycle requirements of the entire working face).

[0014] 5. Design highlights and compatibility with the main scheme. (1) The sealing system uses a triple guarantee of "static adhesive layer + dynamic air curtain + brush compensation", which fully matches the logic of the main scheme of "dynamic nitrogen injection to maintain micro-positive pressure" to ensure stable oxygen concentration in the interval; (2) Closed-loop control avoids the impact of pressure fluctuations and adapts to the core requirement of "preventing air intrusion during equipment transportation" in the main scheme; (3) The maintenance design is connected with the emergency guarantee mechanism of "air emergency train", solving the problem of seal replacement in an oxygen-free environment.

[0015] 2: Design of dynamic nitrogen injection and pressure balance system.

[0016] 1. System Core Objective: Maintain an oxygen concentration of ≤2% within the triple-door area and oxygen-free working surface, creating a slight positive pressure of 0.3-0.4 kPa (slightly higher than the external air pressure) relative to the mine's normal atmospheric pressure (approximately 101 kPa). Staged nitrogen injection is used to adapt to equipment access and emergency maintenance scenarios, ensuring the nitrogen barrier remains in place.

[0017] 2. Nitrogen injection system composition. (1) Nitrogen production equipment. Main nitrogen generators: 2 units (one for use and one for backup), with a single unit gas production capacity of ≥300 m³ / h, nitrogen purity ≥97% (oxygen content ≤3%), using PSA technology to adapt to high humidity and high dust environments underground. Emergency backup source: 10 m³ liquid nitrogen storage tank + vaporizer (evaporation capacity ≥100 m³ / h), which can be switched within 10 minutes in the event of a main nitrogen generator failure, ensuring emergency nitrogen injection for ≥8 hours. (2) Pipelines and nitrogen injection points. Main pipeline: Φ150 mm seamless steel pipe (pressure resistance ≥1.6 MPa), branching to each section. Nitrogen injection points: G1-G2 interval: 2 side wall nozzles (single port flow rate 50-100m³ / h); G2-G3 interval: 3 side wall nozzles (single port flow rate 80-150m³ / h); G3 outer side: 1 top annular nozzle (flow rate 100-200m³ / h).

[0018] 3. Gradual nitrogen injection control logic. Based on the normal atmospheric pressure of the mine, the system automatically adjusts according to the following scenarios: (1) Normal static state: flow rate 20-50 m³ / h, pressure +0.3-0.4 kPa (no equipment passing, oxygen concentration ≤ 2%). (2) Equipment passing: flow rate 150-200 m³ / h, pressure +0.4-0.5 kPa (activated 10 seconds before the door is opened to offset air intrusion). (3) Emergency nitrogen injection: flow rate 200-300 m³ / h, pressure +0.5-0.6 kPa (triggered when oxygen concentration >2% or pressure <0.2 kPa). (4) Manual emergency operation: flow rate 80-120 m³ / h, pressure +0.35 kPa (activated when the air emergency vehicle is connected). (5) Flow rate and pressure sensor are linked in real time (1 time / second), and automatic adjustment is made when the deviation >0.05 kPa to avoid overpressure.

[0019] 4. Pressure balance and leakage prevention. (1) Pressure gradient G1-G2 interval: +0.2-0.3kPa; G2-G3 interval: +0.3-0.4kPa; G3 outer side: +0.35-0.45kPa; the gradient ensures that the gas flow direction is "exterior → buffer zone → working area", preventing air intrusion. (2) Leakage treatment. Oxygen concentration (accuracy ±0.1%) and pressure sensors (accuracy ±0.1kPa) are installed at leak-prone points for real-time monitoring. In the event of local leakage (oxygen concentration 2%-3%), the nearest nitrogen injection point will be automatically opened to replenish pressure; when the leakage rate is greater than 0.1m³ / h, an alarm will be issued to prompt maintenance.

[0020] 5. Safe, redundant dual-circuit power supply + UPS + emergency generator ensures uninterrupted power to core equipment. The underground control cabinet supports manual flow adjustment (0-300 m³ / h) to accommodate sensor failure scenarios. Safety valves (trip pressure 0.8 kPa) are installed in each section to prevent overpressure from damaging equipment.

[0021] 6. Compatibility with the main solution. Nitrogen injection parameters are aligned with the triple-door seal design. Strong nitrogen injection when the doors are open counteracts air intrusion. The pressure gradient works in conjunction with the gas extraction system to prevent gas diffusion and ensure extraction purity ≥90%. Emergency mode is linked to the air emergency vehicle to ensure oxygen concentration ≤2% during manual inspections.

[0022] 3: Design of electric trackless rubber-wheeled air emergency vehicle and emergency measures.

[0023] 1. System Core Objective: Utilizes a pure electric rubber-tyred trackless vehicle to provide 24-hour continuous operation support for eight people in the oxygen-free working area and triple-door section. This zero-emission vehicle is suitable for oxygen-free environments, balancing flexibility and emergency safety.

[0024] 2. Core parameters of the emergency vehicle. (1) Vehicle body and power. Vehicle type: Mining explosion-proof electric trackless rubber-wheeled vehicle (four-wheel drive), size 7m×2.8m×2.2m (adaptable to 6.5m width of tunnel and triple gate). Power: Explosion-proof lithium battery pack (500Ah), endurance ≥24 hours (low-speed operation), full charge ≤8 hours, no exhaust emissions. (2) Oxygen supply system (8 people 24-hour endurance). Main gas source: 4 sets of 40L high-pressure oxygen cylinders (15MPa), total gas storage capacity ≥160m³ (meet the 24-hour needs of 8 people, 67% redundancy). Spare: 8 10L portable oxygen cylinders (1 per person, supporting 5-6 hours of off-vehicle operation). (3) Environmental protection (for the interior of the working cabin). Monitoring: Two O2 / CH4 sensors (accuracy ±0.1% / ±0.01%) provide real-time monitoring of gases within the work chamber: O2: Maintains a concentration of 19.5%-23.5% (optimal for human breathing, preventing oxygen shortages or oversupply); CH4: Prevents external gases from entering the chamber (alarms activate when concentrations exceed 1%, minimizing explosion risks). Ventilation: Dual explosion-proof fans (total air volume 300 m³ / h) are dedicated to air circulation within the work chamber. Function: Filters (dust removal + activated carbon) purify CO2 and odors produced by human breathing, while simultaneously diluting any trace amounts of harmful gases that may infiltrate, maintaining fresh air within the chamber (eliminating stuffiness during extended operations). The dual fan design, with one active and one standby, prevents ventilation interruptions caused by a single fan failure, ensuring a stable chamber environment during 24-hour continuous operation.

[0025] 3. Emergency operation process. (1) Startup: Drive to the G3 gate and park within 15 minutes, deploy the side seal device (leakage rate ≤ 0.05m³ / h), and connect the nitrogen injection system to maintain pressure. (2) Operation: 8 people are divided into 2 groups in shifts (4 hours / shift), and the oxygen concentration in the cabin is adjusted to 21% ± 1% to support equipment maintenance, troubleshooting, and other operations. (3) Supply: Use other trackless vehicles to transport gas cylinders and supplies without interrupting operations. When docked near the work site, connect to the compressed air management to continuously and stably supply oxygen.

[0026] 4. Safety Measures. (1) Gas Source / Power: Gas cylinders are grouped for backup (automatic switching when pressure is <8 MPa). Batteries are equipped with overcharge / short-circuit protection. (2) Operation Limits: Maximum single operation time is 24 hours. Personnel leaving the vehicle must carry a portable detector and a safety rope (≤15m). (3) Termination Conditions: Evacuate immediately if CH4 > 1%, gas cylinder pressure < 5 MPa, battery < 10%, or seal failure occurs.

[0027] 5. Compatibility with the main solution. The dimensions are suitable for trackless transport and triple-door access. The electric drive is emission-free and works in conjunction with the nitrogen injection system to maintain zone pressure. The endurance is sufficient for extended operations and synergizes with the overall auxiliary transport system to improve emergency response efficiency.

[0028] The foregoing description is merely a preferred embodiment of the present invention, intended to more clearly illustrate the technical concept and practical methods of the present invention, and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, and reasonable combinations of partial technical features made to the technical solution that are within the spirit and core principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for constructing an oxygen-free working surface, characterized in that: The following steps are involved: (1) A triple intelligent sealing door is set at the entrance of the machine-rail integrated tunnel to form a first-level buffer zone (O2≤8%) and a second-level buffer zone (O2≤5%); the triple intelligent sealing door includes a first isolation door (G1), a second buffer door (G2), and a third operation door (G3) arranged in sequence along the tunnel axis, with a door body spacing of 15-20 meters and a passage size of 6.5m wide × 5.5m high; the machine-rail integrated tunnel is arranged between the left working face and the right working face, serving both working faces at the same time, and no protective coal pillar is set between adjacent working faces, and the tunnel axis is parallel to the advancing direction of the working faces on both sides; (2) Nitrogen with a purity of ≥97% (oxygen content ≤3%) is injected into the triple gate area and the working face through a dynamic nitrogen injection system to maintain an oxygen concentration of 1%-2% at the working face and form a micro-positive pressure of 0.3-0.4kPa relative to the atmospheric pressure of the mine; the dynamic nitrogen injection system adjusts the flow rate according to the scene level: 20-50m³ / h in normal static state, 150-200m³ / h when equipment is passing, 200-300m³ / h in emergency nitrogen replenishment, and 80-120m³ / h in manual emergency operation; and forms a pressure gradient: G1-G2 interval is + 0.2-0.3kPa, G2-G3 interval is + 0.3-0.4kPa, and the outside of G3 is + 0.35-0.45kPa; (3) Blocking the intrusion of external air through the sealing system: including a 3mm thick polyurea composite sealant layer (1.5mm bottom layer + 1.5mm surface layer) sprayed on the rock wall after pre-treatment, a "U-shaped" hydrogenated nitrile rubber strip on the edge of the door body (cross section 30mm×20mm, compression volume 15%-20%), a two-stage sealing component for the bottom belt channel (300mm long PA66 nylon brush + 20m³ / h nitrogen curtain), and a dynamic nitrogen curtain when the door body is opened and closed (G1 / G2 flow rate 50m³ / h, G3 flow rate 80m³ / h, start 10 seconds before opening and stop 30 seconds after closing); (4) Sealing maintenance: The polyurea sealant layer is inspected every 2 years (repaired when the wear is greater than 30%), the rubber strips and sealing brushes are replaced every 6 months, the door body is designed to have a service life of ≥10 years, and the number of openings and closings is ≥100,000 times; (5) Fire prevention and extinguishing control: The oxygen concentration maintained in step (2) (1%-2% < 5% critical oxygen concentration for spontaneous combustion of coal seams) blocks the oxidation and heat storage of the coal body without the need for traditional inhibitors or grouting; (6) Gas extraction: A Φ1000mm corrosion-resistant pipeline is laid in the machine-track integrated tunnel. The extraction flow rate is adjusted to 10,000m³ / h according to the pressure difference between the working face and the mining area tunnel (0.5-1.0kPa) to ensure that the gas purity is ≥90%.

2. The method according to claim 1, characterized in that The opening and closing logic of the triple intelligent sealing door in step (1) is: when the equipment passes, G1 opens → G1 closes after the equipment enters → G2 opens (delay of 5 seconds) → G2 closes after the equipment enters → G3 opens (delay of 5 seconds), and pressure fluctuations are avoided through sequential linkage.

3. A mine safety mining system, characterized in that: include: (1) Triple intelligent sealed door system: installed at the entrance of the machine and track lane, the door body is made of Q690 high-strength low-alloy steel (thickness 50mm), integrated with infrared sensor (detection distance 8m), pressure sensor (accuracy ±0.01MPa), gas sensor (O2 / CH4 accuracy ±0.1%), supports remote opening and closing and automatic linkage, and is equipped with an emergency mechanical opening and closing device; sensor data is transmitted back to the ground every 10 seconds; (2) Dynamic nitrogen injection and pressure balance system: including two PSA nitrogen generators (one for use and one for standby) (single gas production ≥ 300 m³ / h, adapted to underground humidity ≤ 95%, dust ≤ 200 mg / m³), 10 m³ liquid nitrogen emergency source (evaporation capacity ≥ 100 m³ / h, switch within 10 minutes); the pipeline is Φ150 mm seamless steel pipe (pressure resistance ≥ 1.6 MPa), the nitrogen injection point arrangement is: two side wall nozzles (50-100 m³ / h) in the G1-G2 interval, three side wall nozzles (80-150 m³ / h) in the G2-G3 interval, and one top annular nozzle (100-200 m³ / h) outside G3; each interval is equipped with a safety valve with a take-off pressure of 0.8 kPa; (3) Integrated machine and rail lane: Extending along the edge of the goaf, a single lane serves two working faces on the left and right (without coal pillars), integrating rail transportation, belt transportation, gas extraction pipelines as described in claim 1, and power supply and monitoring lines, replacing the traditional four lanes; (4) Streamlining the ventilation system: Equipped with small fans (one main and one backup) with an air volume of 3000-5000m³ / h, and eliminating dedicated return air shafts and return air lanes; (5) Electric trackless rubber-wheeled air emergency vehicle: Dimensions: 7m×2.8m×2.2m, using 500Ah explosion-proof lithium battery pack (endurance ≥24 hours, charging ≤8 hours); oxygen supply system includes 4 sets of 40L high-pressure oxygen cylinders (15MPa, total gas storage capacity ≥160m³) and 8 10L portable oxygen cylinders; the operation cabin is integrated with 2 sets of O2 / CH4 sensors (accuracy ±0.1% / ±0.01%) and dual explosion-proof fans (total air volume 300m³ / h) to maintain O2 concentration at 19.5%-23.5%; the side sealing device has an air leakage rate of ≤0.05m³ / h; (6) Emergency termination mechanism: When the O2 in the working area is greater than 3%, the gas cylinder pressure is less than 5MPa, the emergency vehicle battery is less than 10%, or the seal leakage rate is greater than 0.1m³ / h, the operation will be automatically terminated and evacuation will be triggered; (7) Fire prevention and extinguishing coordination module: The dynamic nitrogen injection system is used to maintain the oxygen concentration of the working face ≤ 2% (lower than the critical oxygen concentration of 5% for spontaneous combustion of the coal seam). The integrated temperature sensor (accuracy ±1°C) and CO sensor (accuracy ±1ppm) trigger an alarm when the temperature is greater than 30°C or CO is greater than 24ppm and prompts the user to check the leakage point of the sealing system.

4. The system according to claim 3, characterized in that The triple intelligent sealing door is hydraulically driven (working pressure 16-20MPa). The opening and closing time of a single door is ≤30 seconds, and the gap with the sealant layer after closing is ≤1mm.

5. The system according to claim 3, wherein: The dynamic nitrogen injection and pressure balance system uses dual-circuit power supply + UPS + emergency generator, and the downhole control cabinet supports manual flow adjustment (0-300m³ / h).

6. The system according to claim 3, wherein: The electric trackless rubber-wheeled air emergency vehicle's dual explosion-proof fans are equipped with dust removal + activated carbon filtration devices to ensure that the dust concentration in the cabin is ≤2mg / m³.

7. The system according to claim 3, wherein: The temperature sensors and CO sensors of the fire prevention and extinguishing collaborative module are arranged at a distance of ≤5m to achieve full-area monitoring of the working face.

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