A three-zone division method based on isolation and filling at both ends of a coal mining face

Abstract

The application discloses a three-zone division method based on isolation and filling of both ends of a coal mining face, which comprises the following steps: sealing and isolating both ends of a goaf of the coal mining face; inerting the goaf by using a reserved inerting pipeline; arranging a gas concentration and temperature monitoring system in the goaf; analyzing the air leakage flow field of the goaf; establishing a multi-field coupling mathematical model of the air leakage flow field, the gas concentration field and the temperature field of the goaf, simulating the distribution, dynamic change and coupling relationship of each physical field in the goaf; determining three-zone division indexes and threshold values of the goaf according to simulation results and field monitoring data; dynamically dividing the three zones of the goaf by using the division indexes and threshold values; and compressing the space of the oxidation and temperature rising zone according to the division results, so as to control the three zones of the goaf and reduce the spontaneous combustion risk. The method can dynamically and accurately divide the spontaneous combustion three zones of the goaf in combination with the isolation and filling of both ends of the coal mining face, take accurate fire prevention measures for the oxidation and temperature rising zone, and compress the length of the oxidation and temperature rising zone.

Description

Technical Field

[0001] This invention belongs to the field of coal mining technology, and in particular relates to a three-zone division method based on the isolation and filling at both ends of a coal mining face. Background Technology

[0002] During coal mining, spontaneous combustion of coal in the goaf is a serious threat to mine safety. Accurately defining the three zones of spontaneous combustion in the goaf (including the heat dissipation zone, the oxidation and heating zone, and the asphyxiation zone) is a prerequisite for effective prevention and control. Among these, the oxidation and heating zone is a high-risk area for spontaneous combustion fires in the goaf and a key monitoring target for fire prevention and extinguishing. The extent of the oxidation zone is mainly influenced by factors such as the intensity of air leakage in the goaf, the thickness of residual coal, and the tendency of the coal to spontaneously combust. Therefore, areas with high air leakage and easily spontaneously combustible residual coal pose a greater risk to the oxidation and heating zone.

[0003] With increasing mining depth and more complex mining conditions, air leakage at both ends of the coal face is becoming increasingly prominent. This leakage alters the oxygen distribution and temperature field in the goaf, affecting the distribution range of the "three zones" (air, coal, and gas). If the "oxidation and heating zone" experiences prolonged air leakage and oxygen supply, the loose coal will oxidize and heat up, increasing the risk of spontaneous combustion. While existing technologies use methods such as placing shredded coal bags at the ends to form isolation walls and control air leakage, these bags have poor pressure resistance, are not flame-retardant, and require significant labor, time, and safety risks, resulting in ineffective sealing. Furthermore, the lack of a method combining end-end isolation and filling for "three zones" delineation makes it impossible to accurately and in real-time delineate the zones based on the effectiveness of the filling. This negatively impacts the targetedness and effectiveness of measures to prevent spontaneous combustion in the goaf.

[0004] Therefore, there is an urgent need for a method that can dynamically and accurately delineate the three zones of spontaneous combustion in the goaf by combining the isolation and backfilling conditions at both ends of the coal mining face. This method can be used to precisely locate the oxidation and heating zone, accurately take fire prevention measures, shorten the length of the oxidation and heating zone, improve the effectiveness of coal spontaneous combustion prevention, and better ensure the safe production of the mine. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a three-zone division method based on the isolation and backfilling at both ends of the coal mining face. This method can dynamically and accurately divide the three zones of spontaneous combustion in the goaf by combining the isolation and backfilling conditions at both ends of the coal mining face, providing a reliable basis for the prevention and control of spontaneous combustion of coal. It also allows for precise fire prevention measures to be taken for the oxidation and heating zone, reducing the length of the oxidation and heating zone, improving the effectiveness of preventing and controlling spontaneous combustion of coal, and better ensuring safe production in the mine.

[0006] This invention provides a three-zone division method based on the isolation and backfilling at both ends of a coal mining face, comprising:

[0007] Seal and isolate the two ends of the goaf in the coal mining face;

[0008] The goaf is inertized using the reserved inerting pipeline;

[0009] A gas concentration and temperature monitoring system was installed in the goaf area;

[0010] Analyze the air leakage flow field in the goaf;

[0011] A multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field in the goaf is established to simulate the distribution, dynamic changes, and coupling relationships of various physical fields in the goaf.

[0012] Based on simulation results and field monitoring data, the division indicators and thresholds for the three zones of the goaf were determined. The three zones include the heat dissipation zone, the oxidation and heating zone, and the asphyxiation zone.

[0013] The three zones of the goaf are dynamically divided using the division index and the threshold.

[0014] Based on the division results, the space of the oxidation heating zone is compressed to control the three zones of the goaf and reduce the risk of spontaneous combustion.

[0015] Preferably, in the above-mentioned three-zone division method based on the isolation and filling of both ends of the coal mining face, the sealing and isolation of both ends of the goaf of the coal mining face includes:

[0016] A bag belt is placed at both ends of the goaf, and the bag belt extends 2 to 5 meters from both ends of the working face toward the goaf.

[0017] Inorganic sealing material is filled into the abscess to form an abscess isolation wall.

[0018] Preferably, in the above-mentioned three-zone division method based on the isolation and filling of both ends of the coal mining face, an inorganic sealing material is filled into the bladder zone from a distance using a high-power electric grouting pump with a pressure ≥15MPa and a flow rate ≥120L / min.

[0019] Preferably, in the above-mentioned three-zone division method based on the isolation and filling of both ends of the coal mining face, the sealing and isolation of both ends of the goaf of the coal mining face further includes:

[0020] Inject gel into the unburdened space between the two said capsule-like isolation walls.

[0021] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the step of inerting the goaf using the reserved inerting pipeline includes:

[0022] Nitrogen gas is produced using a nitrogen generator and then inertized through the inerting pipeline to inertize the goaf.

[0023] Alternatively, liquid carbon dioxide can be transported via a liquid carbon dioxide tanker through the inerting pipeline to inertify the goaf.

[0024] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the gas concentration and temperature monitoring system deployed in the goaf includes:

[0025] A gas concentration and temperature monitoring system is installed in the goaf to monitor the gas concentrations of O2, CO, CH4, CO2, N2, C2H6, C2H4, C2H2, and temperature in the goaf.

[0026] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the analysis of the air leakage flow field in the goaf includes:

[0027] The absolute pressure distribution in the goaf was monitored by on-site observation and the deployment of pressure sensors to determine the pressure energy distribution pattern inside the goaf and to analyze the air leakage flow field and air leakage channel distribution in the goaf.

[0028] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the establishment of a multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field of the goaf to simulate the distribution, dynamic changes, and coupling relationships of various physical fields within the goaf includes:

[0029] The multi-field coupled mathematical model was established using FLUENT software. During the simulation, the oxidative exothermic characteristics of the coal body in the goaf and the effects of end-point isolation filling, glue injection, and inert gas injection on air leakage were considered.

[0030] The criteria and thresholds for determining the division of the three zones in the goaf based on simulation results and field monitoring data include:

[0031] The oxygen concentration of the heat dissipation belt shall not be less than 18%, and the temperature difference between the heat dissipation belt and the ambient temperature shall not exceed 5℃.

[0032] The oxygen concentration in the oxidative heating zone is 10% to 18%, the temperature difference between the zone and the ambient temperature exceeds 5°C, and a characteristic gas is present.

[0033] The oxygen concentration in the asphyxiation zone does not exceed 10%, and there are no characteristic gases.

[0034] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the dynamic division of the three zones of the goaf using the division index and the threshold includes:

[0035] The dynamic division period is set to 1 to 3 days. When abnormal monitoring data is detected, the dynamic division period is shortened to 12 to 24 hours.

[0036] Preferably, in the above-mentioned three-zone division method based on the isolation and backfilling at both ends of the coal mining face, the step of compressing the space of the oxidation and heating zone according to the division result to control the three zones of the goaf and reduce the risk of spontaneous combustion includes:

[0037] When the length of the oxidation heating zone is not less than 25 meters, the space of the oxidation heating zone is compressed by using the interval of sealing and isolation and / or increasing the flow rate of injection gel and / or increasing the flow rate of injection inert gas, so that the length of the oxidation heating zone is less than 25 meters.

[0038] As described above, the three-zone division method based on the isolation and filling of both ends of a coal mining face provided by this invention includes: sealing and isolating both ends of the goaf of the coal mining face; inerting the goaf using pre-reserved inerting pipelines; arranging gas concentration and temperature monitoring systems in the goaf; analyzing the air leakage flow field of the goaf; establishing a multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field of the goaf to simulate the distribution, dynamic changes, and coupling relationships of various physical fields within the goaf; and determining the three zones of the goaf based on the simulation results and on-site monitoring data. The system defines three zones: a heat dissipation zone, an oxidation and heating zone, and a suffocation zone. Using these criteria and thresholds, the three zones of the goaf are dynamically defined. Based on the defined zones, the space of the oxidation and heating zone is compressed to control the three zones and reduce the risk of spontaneous combustion. Therefore, by combining the isolation and backfilling conditions at both ends of the coal face, the system can dynamically and accurately define the three spontaneous combustion zones of the goaf, providing a reliable basis for coal spontaneous combustion prevention. Precise fire prevention measures are then implemented for the oxidation and heating zone, compressing its length and improving the effectiveness of coal spontaneous combustion prevention, thus better ensuring safe production in the mine. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of an embodiment of a three-zone division method based on the isolation and filling of both ends of a coal mining face provided by the present invention. Detailed Implementation

[0041] The core of this invention is to provide a three-zone division method based on the isolation and backfilling at both ends of the coal mining face. This method can dynamically and accurately divide the three zones of spontaneous combustion in the goaf by combining the isolation and backfilling situation at both ends of the coal mining face, providing a reliable basis for the prevention and control of spontaneous combustion of coal. It can also take precise fire prevention measures for the oxidation and heating zone, reduce the length of the oxidation and heating zone, improve the effectiveness of preventing and controlling spontaneous combustion of coal, and better ensure safe production in the mine.

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] An implementation example of the three-zone division method based on the isolation and backfilling at both ends of a coal mining face provided by this invention. Figure 1 As shown, Figure 1 This is a schematic diagram of an embodiment of a three-zone division method based on the isolation and backfilling at both ends of a coal mining face provided by the present invention. This three-zone division method based on the isolation and backfilling at both ends of a coal mining face may include the following steps:

[0044] S1: Seal and isolate the two ends of the goaf in the coal mining face;

[0045] It should be noted that, specifically, bale-shaped grouting strips can be placed at both ends of the goaf, extending 2 to 5 meters from both ends of the working face into the goaf. These strips can be self-supporting plastic bags, possessing characteristics such as flame retardancy, antistatic properties, and high compressive strength. Then, inorganic sealing material is filled into the strips to form a bale-shaped isolation wall. Ideally, a high-power electric grouting pump with a pressure ≥15MPa and a flow rate ≥120L / min can be used to fill the inorganic sealing material into the strips remotely. This allows for convenient remote operation, eliminating the need for personnel to approach, and also increases work efficiency, saves operation time, and quickly achieves sealing. Furthermore, gel can be injected into the uncollapsed space between two bale-shaped isolation walls to improve the sealing and isolation effect at both ends of the coal face.

[0046] In a specific example, a barrier wall needs to be constructed at the end of the tunnel according to work requirements. Personnel hang the sealing strips at the location to be sealed at the tunnel end, and leave grouting pipes inside the strips and in the effective space between the two strips. Using a high-power electric grouting pump installed in the third mining track roadway, inorganic filling material is mixed with water, and the mixed grout is filled into the strips through the pre-laid grouting pipes, filling the internal space of the strips, solidifying, and forming the wall. Using the same method, the limited space between the two strips that has not collapsed is filled with water glass gel (baking soda + water, water glass + water).

[0047] S2: Inertize the goaf area using the reserved inerting pipeline;

[0048] Specifically, the calculation can be based on the number of nitrogen injection pipelines and monitoring tubes buried in the goaf, according to the "three zones" division of the goaf in each coal mining face of the mine, and adjusted in a timely manner according to the actual measurement to ensure that the outlet of the nitrogen injection pipeline is always within the oxidation zone, and at least one monitoring tube is within the oxidation zone. The spacing of the monitoring tubes can be adjusted within the width of the oxidation zone based on factors such as the number of tubes in the tube bundle, tube material, tube tightness, and anti-impact protection measures, while meeting the minimum number of buried lines. In addition, nitrogen can be produced by a nitrogen generator and inerted through an inerting pipeline to inertify the goaf; or liquid carbon dioxide tanker trucks can be used to inertify the goaf through an inerting pipeline. Both of these methods can achieve precise inerting of the goaf.

[0049] S3: Install gas concentration and temperature monitoring systems in the goaf area;

[0050] Specifically, a gas concentration and temperature monitoring system can be deployed in the goaf to monitor the concentrations of O2, CO, CH4, CO2, N2, C2H6, C2H4, C2H2, and temperature. The system can use a monitoring bundle to monitor gas concentrations and fiber optics to measure temperature. This allows for real-time and effective collection of gas concentration and temperature data in the goaf. The spacing between the monitoring bundles can be 5m to 10m. Monitoring bundles and fiber optic temperature measurement points can be buried every 5m in the goaf at the return air side and intake air end of the working face. The depth of the installation extends from the working face advance direction into the goaf from 0 to 100m, with 20 sets of measurement points in each direction.

[0051] S4: Analyze the air leakage flow field in the goaf;

[0052] Specifically, the absolute pressure distribution in the goaf can be monitored through on-site observation and the deployment of pressure sensors to determine the pressure energy distribution pattern within the goaf. A research method combining theoretical analysis and numerical simulation can then be used to analyze the air leakage flow field and leakage channel distribution within the goaf. The pressure sensors used here can be multi-parameter pressure sensors capable of real-time measurement of pressure values ​​and changes.

[0053] S5: Establish a multi-field coupled mathematical model of the air leakage flow field, gas concentration field and temperature field in the goaf to simulate the distribution, dynamic changes and coupling relationship of various physical fields in the goaf;

[0054] Specifically, a multi-field coupled mathematical model can be established using FLUENT software. During the simulation, the oxidative exothermic characteristics of the coal body in the goaf and the effects of end-point isolation filling, grouting, and inert gas injection on air leakage can be considered. Specifically, the particle transport model in FLUENT fluid dynamics software can be used to inversely determine the development laws of various physical fields in a large-area goaf, analyze the coupling effects of fracture fields, pressure fields, and gas concentration fields under the influence of air leakage factors, reveal the transport laws of the air leakage flow field under the action of multiple physical fields, and simulate the entire process of gas transport in a large-area goaf.

[0055] S6: Based on the simulation results and field monitoring data, determine the division indicators and thresholds for the three zones of the goaf. The three zones include the heat dissipation zone, the oxidation and heating zone, and the asphyxiation zone.

[0056] It should be noted that the criteria for classifying the three zones of the goaf can include oxygen concentration, temperature, and the concentration of a marker gas. These "three zones" include the heat dissipation zone, the oxidation-heating zone, and the asphyxiation zone. Based on simulation results and field monitoring data, the specific criteria and thresholds for classifying the three zones of the goaf can be: The oxygen concentration in the heat dissipation zone is not less than 18%, and the temperature difference with the ambient temperature does not exceed 5℃; the oxygen concentration in the oxidation-heating zone is 10% to 18%, the temperature difference with the ambient temperature exceeds 5℃, and a marker gas is present; the oxygen concentration in the asphyxiation zone does not exceed 10%, and no marker gas is present. In a specific example, the heat dissipation zone on the intake side is 0-20m, the oxidation-heating zone is 20-45m, and the asphyxiation zone is ≥45m; the heat dissipation zone on the return air side is 0-17m, the oxidation-heating zone is 17-38m, and the asphyxiation zone is ≥38m.

[0057] S7: Dynamically divide the three zones of the goaf using division indicators and thresholds;

[0058] Specifically, the dynamic division period can be set to 1 to 3 days. When abnormal monitoring data occurs, such as a sudden increase in the concentration of gases like oxygen and CO, or an abnormal rise in temperature, the dynamic division period can be shortened to 12 to 24 hours. In a specific example, the dynamic division can be based on a 3-day period. When the oxygen concentration in a certain area suddenly increases by more than 3% or the temperature rises by 3°C, the division period can be shortened to 12 hours, and the "three zones" can be redefined.

[0059] S8: Based on the division results, compress the space of the oxidation heating zone to control the three zones of the goaf and reduce the risk of spontaneous combustion.

[0060] Specifically, when the length of the oxidation heating zone is not less than 25 meters, the space of the oxidation heating zone can be compressed by using the interval of sealing and isolation and / or increasing the flow rate of injection gel and / or increasing the flow rate of injection inert gas, so that the length of the oxidation heating zone is less than 25 meters, thereby achieving effective control of the "three zones" in the goaf and thus more efficiently reducing the risk of spontaneous combustion.

[0061] In a specific example, when monitoring data shows that the risk of oxidation in the goaf is high (e.g., O2 concentration > 10%, CO concentration continues to rise), the following measures are taken: increase the injection volume of inert gas (nitrogen, CO2) and water glass gel to directly suppress the development of the oxidation heating zone; increase the construction frequency of the isolation walls at both ends (e.g., from one every 20m to one every 5 to 10m).

[0062] The aforementioned method for dividing the three zones based on the isolation and backfilling at both ends of the coal face can accurately divide the "three zones" by considering the isolation and backfilling conditions at both ends of the coal face. It fully considers the impact of air leakage at both ends on the distribution of the "three zones" in the goaf, improving the accuracy of the division results, compressing the spatial range of the oxidation and heating zone, and preventing coal spontaneous combustion accidents, thus ensuring safe mining. Furthermore, by deploying a comprehensive monitoring system and establishing a multi-field coupled mathematical model, it is possible to acquire real-time data on the air leakage flow field, gas concentration, and temperature physical field of the goaf, achieving dynamic division of the "three zones" and providing timely and reliable data for coal spontaneous combustion prevention. Dynamically adjusting parameters such as the isolation wall spacing and the injection flow rate of sizing and nitrogen based on the "three zone" division results allows for targeted control of the distribution of the "three zones" in the goaf, greatly compressing the space of the oxidation and heating zone, thereby achieving effective control of the "three zones" in the goaf, reducing the risk of spontaneous combustion, and providing better protection for safe mining and shutdown / retreat.

[0063] As described above, the embodiment of the three-zone division method based on the isolation and filling of both ends of a coal mining face provided by the present invention includes: sealing and isolating both ends of the goaf of the coal mining face; inerting the goaf using reserved inerting pipelines; arranging a gas concentration and temperature monitoring system in the goaf; analyzing the air leakage flow field of the goaf; establishing a multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field of the goaf to simulate the distribution, dynamic changes, and coupling relationships of various physical fields within the goaf; and determining the mining zone based on the simulation results and on-site monitoring data. The criteria and thresholds for dividing the three zones of the goaf are used. These three zones include the heat dissipation zone, the oxidation and heating zone, and the asphyxiation zone. Using these criteria and thresholds, the three zones of the goaf are dynamically divided. Based on the division results, the space of the oxidation and heating zone is compressed to control the three zones of the goaf and reduce the risk of spontaneous combustion. Therefore, by combining the isolation and backfilling situation at both ends of the coal face, the three zones of spontaneous combustion in the goaf can be dynamically and accurately divided, providing a reliable basis for the prevention and control of coal spontaneous combustion. Precise fire prevention measures can be taken for the oxidation and heating zone, the length of the oxidation and heating zone can be compressed, the effect of coal spontaneous combustion prevention and control can be improved, and the safety of mine production can be better guaranteed.

[0064] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A three-zone division method based on the isolation and backfilling at both ends of a coal mining face, characterized in that, include: Seal and isolate the two ends of the goaf in the coal mining face; The goaf is inertized using the reserved inerting pipeline; A gas concentration and temperature monitoring system was installed in the goaf area; Analyze the air leakage flow field in the goaf; A multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field in the goaf is established to simulate the distribution, dynamic changes, and coupling relationships of various physical fields in the goaf. Based on simulation results and field monitoring data, the division indicators and thresholds for the three zones of the goaf were determined. The three zones include the heat dissipation zone, the oxidation and heating zone, and the asphyxiation zone. The three zones of the goaf are dynamically divided using the division index and the threshold. Based on the division results, the space of the oxidation heating zone is compressed to control the three zones of the goaf and reduce the risk of spontaneous combustion; The sealing and isolation of the two ends of the goaf in the coal mining face includes: A bag belt is placed at both ends of the goaf, and the bag belt extends 2 to 5 meters from both ends of the working face toward the goaf. Inorganic sealing material is filled into the abscess to form an abscess isolation wall; Inorganic sealing material is filled into the bladder remotely using a high-power electric grouting pump with a pressure ≥15MPa and a flow rate ≥120L / min. The sealing and isolation of the two ends of the goaf in the coal mining face also includes: Inject gel into the unburdened space between the two said capsule-like isolation walls.

2. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 1, characterized in that, The inerting of the goaf using the reserved inerting pipeline includes: Nitrogen gas is produced using a nitrogen generator and then inertized through the inerting pipeline to inertize the goaf. Alternatively, liquid carbon dioxide can be transported via a liquid carbon dioxide tanker through the inerting pipeline to inertify the goaf.

3. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 1, characterized in that, The gas concentration and temperature monitoring system deployed in the goaf includes: A gas concentration and temperature monitoring system is installed in the goaf to monitor the gas concentrations of O2, CO, CH4, CO2, N2, C2H6, C2H4, C2H2, and temperature in the goaf.

4. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 1, characterized in that, The analysis of the air leakage flow field in the goaf includes: The absolute pressure distribution in the goaf was monitored by on-site observation and the deployment of pressure sensors to determine the pressure energy distribution pattern inside the goaf and to analyze the air leakage flow field and air leakage channel distribution in the goaf.

5. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 2, characterized in that, The establishment of a multi-field coupled mathematical model of the air leakage flow field, gas concentration field, and temperature field in the goaf, to simulate the distribution, dynamic changes, and coupling relationships of various physical fields within the goaf, includes: The multi-field coupled mathematical model was established using FLUENT software. During the simulation, the oxidative exothermic characteristics of the coal body in the goaf and the effects of end-point isolation filling, glue injection, and inert gas injection on air leakage were considered. The criteria and thresholds for determining the division of the three zones in the goaf based on simulation results and field monitoring data include: The oxygen concentration of the heat dissipation belt shall not be less than 18%, and the temperature difference between the heat dissipation belt and the ambient temperature shall not exceed 5℃. The oxygen concentration in the oxidative heating zone is 10% to 18%, the temperature difference between the zone and the ambient temperature exceeds 5°C, and a characteristic gas is present. The oxygen concentration in the asphyxiation zone does not exceed 10%, and there are no characteristic gases.

6. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 1, characterized in that, Using the aforementioned classification index and the aforementioned threshold, the three zones of the goaf are dynamically divided as follows: The dynamic division period is set to 1 to 3 days. When abnormal monitoring data is detected, the dynamic division period is shortened to 12 to 24 hours.

7. The three-zone division method based on the isolation and backfilling at both ends of the coal mining face according to claim 2, characterized in that, The method of compressing the space of the oxidation heating zone according to the division results to control the three zones of the goaf and reduce the risk of spontaneous combustion includes: when the length of the oxidation heating zone is not less than 25 meters, compressing the space of the oxidation heating zone by means of sealing and isolating the interval and / or increasing the flow rate of injection gel and / or increasing the flow rate of injection inert gas, so that the length of the oxidation heating zone is less than 25 meters.

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