Judgment method suitable for coal spontaneous combustion development stage of old kiln goaf of coal mine

Abstract

The invention provides a coal spontaneous combustion development stage determination method suitable for a coal mine old kiln goaf. The method comprises the following steps: S1, collecting a standard rock sample; s2, measuring the magnetic susceptibility of the standard rock sample under a variable temperature condition, and drawing a temperature-magnetic susceptibility curve; s3, drilling, sampling and measuring temperature; s4, measuring the normal-temperature magnetic susceptibility xm of the rock core sample obtained in the step S3 under a normal-temperature condition; and S5, judging the coal spontaneous combustion development stage. The coal spontaneous combustion development stage judgment method is constructed by combining coal seam temperature measurement, magnetic susceptibility analysis and coal seam coal sample state observation, and the problem that different development stages in the same temperature interval are difficult to accurately distinguish in the prior art is effectively solved. The method is simple in operation process and refined in judgment result, can be widely applied to coal spontaneous combustion hidden danger assessment scenes of the old coal mine kiln goaf, can accurately recognize the coal spontaneous combustion development stage of the old coal mine kiln goaf, and provides a scientific basis for hidden danger prevention and treatment before continuous mining.

Description

Technical Field

[0001] This invention belongs to the field of safety monitoring and coal spontaneous combustion prevention technology in coal mine goaf areas, specifically involving a method for determining the development stage of coal spontaneous combustion in old coal mine goaf areas. Background Technology

[0002] As concealed spaces formed after coal mining, the old goaf in coal mines is prone to spontaneous combustion due to the residual coal in a long-term enclosed environment. This is caused by multiple factors, including historical mining disturbances, evolution of surrounding rock stress, fissure conduction, and adjustments to the ventilation system. During the historical mining or closure period, these goafs often exhibit precursors such as localized coal temperature increases, abnormal gases indicating spontaneous combustion, or sporadic fires. After long-term closure, the risk of spontaneous combustion may be in different stages of development, including the heat accumulation period, the early stage of intense combustion, and the afterburning period.

[0003] Currently, the determination of the development stage of spontaneous combustion of coal in old mining goaf areas mainly relies on traditional technical methods such as borehole temperature measurement, gas detection, ground-penetrating radar detection, and resistivity method. These technologies have played a certain role in the initial investigation of potential coal spontaneous combustion hazards, but they are insufficient to meet the needs of precise determination of the development stage of spontaneous combustion in subsequent mining or near-field mining scenarios.

[0004] Existing technologies for determining the risk of spontaneous combustion of coal in the goaf of old coal mines have significant limitations: 1. Although borehole temperature measurement can accurately measure temperature, it cannot distinguish whether the stage of spontaneous combustion of coal is in the early or late stage.

[0005] 2. Gas detection technology may show the same characteristic gas concentration characteristics at different stages of coal spontaneous combustion. Moreover, in the long-term closed environment of the old coal mine goaf, the gas is an accumulated amount, making it difficult to define the specific development stage by gas indicators alone.

[0006] 3. Conventional geophysical exploration techniques, such as ground-penetrating radar and resistivity methods, mainly focus on the detection of the spatial morphology of the goaf and the integrity of the surrounding rock.

[0007] If the detailed stage of spontaneous combustion development in the goaf of an old coal mine cannot be accurately determined, subsequent protection and control plans will lack specificity, seriously threatening the safety of mining personnel and the orderly progress of mining operations. Therefore, there is an urgent need for a technical method that can accurately identify the stage of spontaneous combustion development in the goaf of an old coal mine, providing a scientific basis for hazard prevention and control before subsequent mining. Summary of the Invention

[0008] To address the aforementioned problems, the purpose of this invention is to provide a method for determining the spontaneous combustion development stage of coal in old coal mine goaf areas.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for determining the spontaneous combustion development stage of coal in the goaf of old coal mines, specifically including the following steps: Step S1: Collect standard rock samples: The overlying rock strata of the coal seam in the old mine goaf of a certain coal mine where the spontaneous combustion development stage of coal needs to be determined are used as the sampling object. Normal rock samples that are not affected by high temperature and have intact lithology are collected. The sampling points are set up in the outcrop profile of the mining area or in undisturbed areas underground. After sampling, the samples are immediately sealed and packaged as standard rock samples. Step S2: Measure the magnetic susceptibility of the standard rock sample under varying temperature conditions, plot the temperature-magnetic susceptibility curve, obtain the heating curve and cooling curve, determine the Curie point A in the heating curve, and determine the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A. J , and the magnetic susceptibility χ0 when the temperature drops to room temperature point B in the cooling curve; Step S3, Drilling, Sampling and Temperature Measurement: Select a detection point on the ground in the work area to carry out drilling construction. The drilling depth penetrates the overlying rock strata and the target coal seam. Take coal samples from the target coal seam and rock core samples from the top plate 10cm away from the coal seam side. Visually observe and record the state of the coal seam samples and seal the rock core samples. After sampling, measure the real-time temperature T of the target coal seam stratum in the hole. Step S4: Measure the room temperature magnetic susceptibility χ of the rock core sample obtained in step S3 under room temperature conditions. m ; Step S5, Determination of the spontaneous combustion development stage of coal: Combining the temperature T measured in step S3, the state of the coal seam and coal sample observed and recorded by the naked eye, and the χ measured in step S4 m Based on the magnetic susceptibility χ0 measured in step 2, and according to Table 1, the stage of spontaneous combustion development of coal at this detection point is determined as follows: .

[0010] Furthermore, in step S1, the sampling method is core drilling or manual chiseling, and the weight of a single sample is not less than 500g.

[0011] Furthermore, the measurement of magnetic susceptibility of the standard rock sample under varying temperature conditions in step S2 specifically includes the following steps: Step S201: Use a pulverizer to pulverize the standard rock sample from step S1 into uniform particles, and place it in a drying oven to dry at 60°C for 48 hours to obtain a standard pulverized rock sample. Step S202: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, and place the standard crushed rock sample in the test tube; Step S203: Set the heating and cooling rates of the temperature-varying magnetic susceptibility meter to 2℃ / min, and the experimental temperature range to room temperature to 700℃. Test the magnetic susceptibility of the rock sample at different temperatures during the heating process and at different temperatures during the cooling process. Step S204: Plot the temperature-magnetic susceptibility curve based on the test results to obtain the heating curve and cooling curve. Determine the Curie point A in the heating curve and determine the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A. J And the magnetic susceptibility χ0 when the temperature drops to the normal cooling point B in the cooling curve.

[0012] Furthermore, the method for determining the Curie point A is as follows: determine the temperature T corresponding to the highest magnetic susceptibility value in the cooling curve. d Within the temperature range ≥400℃ of the heating curve, identify one or more abrupt changes in magnetic susceptibility where it decreases sharply after increasing temperature. When there is only one abrupt change, this point is the Curie point A. When there are multiple abrupt changes, their temperature values ​​are related to T. d The closest mutation point is Curie point A.

[0013] Furthermore, the working area in step S3 is the projected area of ​​the old coal mine goaf on the ground in step S1.

[0014] Furthermore, in step S3, the diameter of the borehole is 89mm-110mm, and the borehole depth penetrates the overlying rock strata and the target coal seam.

[0015] Furthermore, step S4 specifically includes the following steps: Step S401: Use a pulverizer to pulverize the rock core sample obtained in step S3 into uniform particles, and place it in a drying oven to dry at 60°C for 48 hours to obtain a pulverized rock sample. Step S402: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, place the crushed rock sample particles in a test tube, and directly measure its magnetic susceptibility χ at room temperature. m ; Furthermore, the method for determining the spontaneous combustion development stage of coal in old coal mine goaf areas also includes: Step S6: Measurement of the entire working area: Multiple detection points are selected within the work area, and steps S3-S5 are repeated to obtain the determination results of the coal spontaneous combustion development stage at different detection point locations.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Significantly improved accuracy. This invention determines the accuracy based on the real-time temperature T of the target coal seam in the goaf and the ambient temperature magnetic susceptibility χ of the rock core sample. mIn addition to the state of coal seam samples observed and recorded by the naked eye, and combined with the temperature-magnetic susceptibility characteristic parameters of standard rock samples (Curie temperature Tc, heating magnetic susceptibility χ), J , magnetic susceptibility at room temperature (χ0), through χ m Compared with the standard value χ J The comparison can accurately distinguish the heating or cooling stages within the same temperature range and trace whether it has experienced a violent later stage of combustion.

[0017] (2) Supporting differentiated prevention and control. The present invention subdivides the stages precisely to correspond to different risk situations. Combined with the magnetic susceptibility index, the historical combustion intensity can be clearly identified, providing a strong basis for prevention and control in high-risk stages and simplifying monitoring in low-risk stages, avoiding over-control or insufficient prevention and control, and improving the targeting and economy of the control.

[0018] (3) Adaptable to concealed application scenarios. This invention is designed for the long-term closed nature of old goaf areas. The magnetic susceptibility index is not affected by gas accumulation or fracture distribution. The state of coal seam samples can be judged by the naked eye. It has stronger environmental adaptability than traditional technology, and the judgment results are more reliable, effectively ensuring the safety of subsequent mining.

[0019] In summary, this invention constructs a method for determining the development stage of spontaneous combustion of coal by combining coal seam temperature measurement, magnetic susceptibility analysis, and observation of coal seam sample conditions. The operation process is simple and the determination results are precise. It can be widely applied to the assessment of spontaneous combustion hazards in old coal mine goaf areas, accurately identifying the development stage of spontaneous combustion of coal in old coal mine goaf areas, and providing a scientific basis for hazard prevention and control before continued mining. Attached Figure Description

[0020] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The temperature-magnetic susceptibility curve of the standard rock sample is obtained by measuring the magnetic susceptibility of the standard rock sample under varying temperature conditions in step S2 of this invention. In the figure: 1 is Curie point A, 2 is the heating curve, 3 is the cooling curve, and 4 is the room temperature point B. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] The present invention will now be described in detail with reference to the accompanying drawings.

[0024] Example 1: A method for determining the spontaneous combustion development stage of coal in the goaf of old coal mines, specifically including the following steps: Step S1: Collect standard rock samples: Select the overlying rock strata of the coal seam in the old mine goaf of a certain coal mine where the spontaneous combustion development stage of the coal is to be determined as the sampling object. The sampling points are set at the surface outcrops or underground exposure points of the overlying rock strata. Collect normal rock samples that are not affected by high temperature and have intact lithology. After sampling, seal and package them immediately as standard rock samples. The sampling method is either core drilling or manual chiseling, and the weight of a single sample is not less than 500g. Step S2: Measure the magnetic susceptibility of the standard rock sample under varying temperature conditions, plot the temperature-magnetic susceptibility curve to obtain heating curve 2 and cooling curve 3, determine the Curie point A1 in heating curve 2, and identify the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A1. J And the magnetic susceptibility χ0 at room temperature point B4 in cooling curve 3; specifically including the following steps: Step S201: Use a pulverizer to pulverize the standard rock sample from step S1 into uniform particles (200-300 mesh), and place it in a drying oven to dry at 60℃ for 48 hours to obtain a standard pulverized rock sample; Step S202: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, and place the standard crushed rock sample in the test tube; Step S203: Set the heating and cooling rates of the temperature-varying magnetic susceptibility meter to 2℃ / min, and the experimental temperature range to room temperature to 700℃. Test the magnetic susceptibility of the rock sample at different temperatures during the heating process and at different temperatures during the cooling process. Step S204: Plot the temperature-magnetic susceptibility curve based on the test results, such as... Figure 1 As shown, heating curve 2 and cooling curve 3 are obtained. The Curie point A1 in heating curve 2 is determined, and the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A1 are determined. J And the magnetic susceptibility χ0 when the temperature drops to room temperature point B4 in cooling curve 3; The method for determining the Curie point A1 is as follows: determine the temperature T corresponding to the highest magnetic susceptibility value in the cooling curve 3.d Within the temperature range of ≥400℃ on the heating curve, find one or more abrupt change points where the magnetic susceptibility drops sharply after increasing temperature; when there is only one abrupt change point, this point is the Curie point A1; when there are multiple abrupt change points, their temperature values ​​are related to T. d The closest mutation point is the Curie point A1; Step S3, Drilling, Sampling, and Temperature Measurement: Select a detection point on the ground in the working area (the projected area of ​​the old coal mine goaf in Step S1) and carry out drilling. The diameter of the borehole is 89mm-110mm, and the borehole depth penetrates the overlying strata and the target coal seam. Take coal samples from the target coal seam and rock core samples from 10cm away from the coal seam on the roof. Visually observe and record the state of the coal seam samples, and seal and encapsulate the rock core samples. After sampling, measure the real-time temperature T of the target coal seam stratum inside the borehole. Step S4: Measure the room temperature magnetic susceptibility χ of the rock core sample obtained in step S3 under room temperature conditions. m Specifically, it includes the following steps: Step S401: Use a pulverizer to pulverize the rock core sample obtained in step S3 into uniform particles (200-300 mesh), and place it in a drying oven to dry at 60℃ for 48 hours to obtain a pulverized rock sample; Step S402: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, place the crushed rock sample particles in a test tube, and directly measure its magnetic susceptibility χ at room temperature. m ; Step S5, Determination of the spontaneous combustion development stage of coal: Combining the temperature T measured in step S3, the state of the coal seam and coal sample observed and recorded by the naked eye, and the χ measured in step S4 m Based on the magnetic susceptibility χ0 measured in step 2, and according to Table 1, the stage of spontaneous combustion development of coal at this detection point is determined as follows: .

[0025] In Table 1: (1) The principle for judging the state of coal seam coal samples based on visual observation is as follows: Normal state: The coal body has not undergone oxidation reaction, and its appearance and structure are consistent with the undisturbed original coal seam, with no signs of oxidation or metamorphism; Semi-oxidized state: The coal body undergoes oxidation, resulting in reduced luster, localized looseness and fragility, but the overall structure is not completely destroyed; Fully oxidized state: The coal body is completely transformed into oxidized minerals, completely dull, with completely destroyed bedding, no blocky morphology, and a thoroughly loose structure. Only some oxidation products can be extracted by core drilling.

[0026] (2) The definition and characteristics of the development stage of spontaneous combustion of coal are described as follows: Stable temperature period: This stage is characterized by the real-time temperature T of the coal seam being comparable to the background temperature of the working area, T≤25℃, and the temperature remaining stable without fluctuation. During this stage, no significant oxidation and heat storage reaction occurs in the coal body, no chemical phase transformation occurs in the roof rock, and the rock magnetic susceptibility remains in its original state. m <χ J ; The heat storage period is characterized by 25℃ < T ≤ 100℃. During this stage, the coal body undergoes oxidation and continuously accumulates heat. The roof rock does not undergo a chemical phase transformation, and the rock's magnetic susceptibility can return to its initial state after cooling to room temperature. (χ) m <χ J ; Early heating phase: Characterized by 100℃ < T ≤ 400℃. During this stage, a large amount of heat accumulates in the coal body, the roof rock does not undergo chemical phase transformation, and the rock's magnetic susceptibility can return to its initial state after cooling to room temperature. χ m <χ J ; Early stage of intense combustion: characterized by 400℃ < T. During this stage, the coal burns intensely, the roof rock does not undergo chemical phase transformation, and the rock's magnetic susceptibility largely recovers to its initial state after cooling to room temperature. χ m <χ J ; Late stage of intense combustion: characterized by 400℃ < T. During this stage, the coal burns intensely, and the roof rock currently or previously exceeded Tc temperature, undergoing an irreversible chemical phase transformation. The magnetic susceptibility χ of the rock after cooling to room temperature... m ≥χ J Value, and χ m =χ0.

[0027] The stable combustion period without the intense later stages of combustion is characterized by a temperature (T) comparable to the background temperature of the working area, T≤25℃, and a consistently stable temperature without fluctuations. During this stage, the coal is completely burned, leaving no residual heat. The roof rock never exceeds Tc temperature, no chemical phase transformation occurs, and its magnetic susceptibility recovers to its initial state after cooling to room temperature, and χ... m <χ J ; The coal underwent a period of intense combustion followed by a stable afterburning phase, characterized by a temperature (T) comparable to the background temperature of the working area (T≤25℃) with sustained stability. During this stage, the coal was completely burned, leaving no residual heat. The roof rock had exceeded the Tc temperature, resulting in an irreversible chemical phase transformation. The magnetic susceptibility (χ) of the rock after cooling to room temperature was [not specified]. m ≥χ J Value, and χ m =χ0; The initial cooling phase, before the intense combustion phase, is characterized by 100℃ < T ≤ 400℃. During this stage, the coal combustion intensity weakens. The roof rock never exceeds Tc temperature, no chemical phase transformation occurs, and its magnetic susceptibility recovers to its initial state after cooling to room temperature, and χ... m<χ J ; The coal underwent a period of intense combustion followed by a cooling phase, characterized by temperatures ranging from 100℃ to T ≤ 400℃. During this stage, the coal's combustion intensity decreased. The roof rock had exceeded the Tc temperature, resulting in an irreversible chemical phase transformation. The magnetic susceptibility χ of the rock after cooling to room temperature... m ≥χ J Value, and χ m =χ0; The cooling phase, which does not involve a period of intense combustion, is characterized by 25℃ < T ≤ 100℃. During this stage, the coal is completely burned, leaving only residual heat. The roof rock never exceeds Tc temperature, and no chemical phase transformation occurs. Its magnetic susceptibility recovers to its initial state after cooling to room temperature, and χ... m <χ J ; The coal underwent a period of intense combustion followed by a cooling phase, characterized by temperatures between 25℃ and 100℃. During this stage, the coal was completely burned, leaving only residual heat. The roof rock had exceeded the Tc temperature, resulting in an irreversible chemical phase transformation. The magnetic susceptibility χ of the rock after cooling to room temperature... m ≥χ J Value, and χ m =χ0; Example 2: The difference between this embodiment and Embodiment 1 is that it also includes: Step S6: Assessment of the degree of spontaneous combustion development in the goaf of old coal mines: Multiple detection points are selected within the work area, and steps S3-S5 are repeated to obtain the determination results of the coal spontaneous combustion development stage at different detection point locations.

[0028] Based on the results of the coal spontaneous combustion development stage determination at multiple detection points in the above-mentioned work area, a comprehensive assessment of the degree of coal spontaneous combustion development in the old mine goaf area of ​​the coal mine was conducted, providing technical support for the formulation of targeted protection and control plans.

[0029] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for determining the spontaneous combustion development stage of coal in the goaf of old coal mines, characterized in that, Specifically, the following steps are included: Step S1: Collect standard rock samples: The overlying rock strata of the coal seam in the old mine goaf of a certain coal mine where the spontaneous combustion development stage of coal needs to be determined are used as the sampling object. Normal rock samples that are not affected by high temperature and have intact lithology are collected. The sampling points are set up in the outcrop profile of the mining area or in undisturbed areas underground. After sampling, the samples are immediately sealed and packaged as standard rock samples. Step S2: Measure the magnetic susceptibility of the standard rock sample under varying temperature conditions, plot the temperature-magnetic susceptibility curve, obtain the heating curve and cooling curve, determine the Curie point A in the heating curve, and determine the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A. J , and the magnetic susceptibility χ0 when the temperature drops to room temperature point B in the cooling curve; Step S3, Drilling, Sampling and Temperature Measurement: Select a detection point on the ground in the work area to carry out drilling construction. The drilling depth penetrates the overlying rock strata and the target coal seam. Take coal samples from the target coal seam and rock core samples from the top plate 10cm away from the coal seam side. Visually observe and record the state of the coal seam samples and seal the rock core samples. After sampling, measure the real-time temperature T of the target coal seam stratum in the hole. Step S4: Measure the room temperature magnetic susceptibility χ of the rock core sample obtained in step S3 under room temperature conditions. m ; Step S5, Determination of the spontaneous combustion development stage of coal: Combining the temperature T measured in step S3, the state of the coal seam and coal sample observed and recorded by the naked eye, and the χ measured in step S4 m Based on the magnetic susceptibility χ0 measured in step 2, and according to Table 1, the stage of spontaneous combustion development of coal at this detection point is determined as follows: 。 2. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, In step S1, the sampling method is core drilling or manual chiseling, and the weight of a single sample is not less than 500g.

3. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, The step S2, measuring the magnetic susceptibility of the standard rock sample under varying temperature conditions, specifically includes the following steps: Step S201: Use a pulverizer to pulverize the standard rock sample from step S1 into uniform particles, and place it in a drying oven to dry at 60°C for 48 hours to obtain a standard pulverized rock sample. Step S202: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, and place the standard crushed rock sample in the test tube; Step S203: Set the heating and cooling rates of the temperature-varying magnetic susceptibility meter to 2℃ / min, and the experimental temperature range to room temperature to 700℃. Test the magnetic susceptibility of the rock sample at different temperatures during the heating process and at different temperatures during the cooling process. Step S204: Plot the temperature-magnetic susceptibility curve based on the test results to obtain the heating curve and cooling curve. Determine the Curie point A in the heating curve and determine the temperature value Tc and magnetic susceptibility χ corresponding to Curie point A. J And the magnetic susceptibility χ0 when the temperature drops to the normal cooling point B in the cooling curve.

4. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, The method for determining the Curie point A is as follows: determine the temperature T corresponding to the highest magnetic susceptibility value in the cooling curve. d Within the temperature range ≥400℃ of the heating curve, identify one or more abrupt changes in magnetic susceptibility where it decreases sharply after increasing temperature. When there is only one abrupt change, this point is the Curie point A. When there are multiple abrupt changes, their temperature values ​​are related to T. d The closest mutation point is Curie point A.

5. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, The working area in step S3 is the projected area of ​​the old coal mine goaf in step S1 on the ground.

6. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, In step S3, the diameter of the borehole is 89mm-110mm, and the borehole depth penetrates the overlying rock strata and the target coal seam.

7. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, Step S4 specifically includes the following steps: Step S401: Use a pulverizer to pulverize the rock core sample obtained in step S3 into uniform particles, and place it in a drying oven to dry at 60°C for 48 hours to obtain a pulverized rock sample. Step S402: Place the temperature-varying magnetic susceptibility meter in a laboratory with the same ambient magnetic field as the sampling point in step S1, place the crushed rock sample particles in a test tube, and directly measure its magnetic susceptibility χ at room temperature. m .

8. The method for determining the spontaneous combustion development stage of coal in the goaf of an old coal mine as described in claim 1, characterized in that, The method for determining the stage of spontaneous combustion of coal applicable to old coal mine goaf areas also includes: Step S6: Measurement of the entire working area: Multiple detection points are selected within the work area, and steps S3-S5 are repeated to obtain the determination results of the coal spontaneous combustion development stage at different detection point locations.

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