Spontaneous Combustion Zone Research Articles

Advanced machine learning schemes for prediction CO2 flux based experimental approach in underground coal fire areas

IntroductionUnderground coal fires pose significant environmental and health risks due to releasing CO2 emissions. Predicting surface CO2 flux accurately in underground coal fire areas is crucial for understanding the distribution of spontaneous combustion zones and developing effective mitigation strategies. In recent years, advanced machine learning techniques have shown promise in various carbon-related studies. This research uses an experimental approach to explore the power of advanced machine learning schemes for predicting CO2 flux in underground coal fire areas. ObjectivesBy leveraging the power of advanced machine learning schemes and experimental approaches, this research aims to provide valuable insights into CO2 flux prediction in coal fire areas and inform environmental monitoring and management strategies. MethodsThe study involves the collection of an experimental dataset specific to underground coal fire areas, encompassing various parameters related to CO2 flux and underground coal fire characteristics. Innovative feature engineering techniques are applied to capture the unique characteristics of underground coal fire areas and their impact on CO2 flux. Different machine learning algorithms, including Natural gradient boosting regression (NGRB), Extreme gradient boosting (XGboost), Light gradient boosting (LGRB), and random forest (RF), are evaluated and compared for their predictive capabilities. The models are trained, optimized, and assessed using appropriate performance metrics. ResultsThe NGRB model yields the best predictive performances with R2 of 0.967 and MAE of 0.234. The novel contributions of this study include the development of accurate prediction models tailored to underground coal fire areas, shedding light on the underlying factors driving CO2 flux. The findings have practical implications for delineating the spontaneous combustion zone and mitigating CO2 emissions from underground coal fires, contributing to global efforts in combating climate change.

Calculating the Spontaneous Combustion Temperature of Coal Based on Measured Gas concentration: A Case Study in the Huangshan Mine, China

ABSTRACT The actual coal temperature of “spontaneous combustion zone” is not convenient to obtain, which causes a lot of inconvenience to the prevention and control of coal spontaneous combustion fire. The traditional temperature measurement method does not consider the influence of gas flow in the goaf, so the measured coal temperature cannot directly reflect the actual state of coal spontaneous combustion. This paper presents a method to predict the coal temperature in the “spontaneous combustion zone” based on the theoretical data obtained in the laboratory, combined with the actual coal temperature in the “dissipation zone,” and applies it to the B4 layer coal mine in Huangshan, Jiangxi Province. The results show that the method is objective and effective, and can be used for the prediction of CSC (coal spontaneous combustion) in the goaf of coal mines.

Research on the spontaneous combustion of the goaf at different advancing distances based on the dynamic evolution of porosity

Spontaneous combustion of residual coal in the goaf is one of the main disasters in coal mines. Understanding the law of spontaneous combustion of residual coal can effectively prevent coal mine fires. This paper establishes a dynamic evolution model of overburden caving and porosity in the goaf using PFC numerical simulation software, and compares and analyzes the dynamic changes in porosity and the spontaneous combustion zone at advancing distances of 50 m, 70 m, and 100 m. The results show that when the working face advances 100 m, the porosity in the caving zone of the goaf decreases from 0–0.6 to 0.16–0.3. The range of the spontaneous combustion zone on the return air side expands from 42m-50 m to 39m–61 m, and on the inlet side, it expands from 0 to 22m–50 m. With increased exposure time, the spontaneous combustion zone range shifts slightly forward to 32m–55 m on the inlet side and 21m–49 m on the return side. This study reveals the dynamic evolution law of the spontaneous combustion zone in the goaf under the influence of different advancing distances and exposure times, which can assist in preventing goaf fires.

Determination of Coal Spontaneous Combustion Zone in Overlaying Multilayer Goaf and Its Control Technology of Thickened Slurry

ABSTRACT In order to study the law of coal spontaneous combustion and prevention methods in the overlying multilayer goaf, this study combined the situation of 378 working face and overlying multilayer goaf in Anyuan Coal Mine and determined the coal spontaneous combustion zone in the overlying multilayer goaf by overlaying the oxidation zones divided by wind velocity and oxygen concentration, and verified it. Subsequently, a new type of thickened slurry was prepared based on sodium alginate, carboxymethyl cellulose, loess, and water as the main raw materials, and a thickened slurry fire prevention technique suitable for overlying multilayer goaf was proposed. The research results indicated that the coal spontaneous combustion zone was located near the 3117 return air roadway and the 378 return air roadway in 378 working face, as well as the upper part of 3117 return air roadway in 372 (4) goaf. When the water-soil ratio was 8:1 and thickener concentration was 0.3%, the suspension performance of the thickened slurry was better. At this point, the corresponding yield stress was the smallest and the flow ability was better. Through the used of fixed-point grouting and regional sealing of a thickened slurry fire prevention technique, it was found that the CO concentration gradually decreased to zero in the 372 (4) goaf. The oxygen concentration significantly decreased and the pressure difference remained stable in the sealing wall in the return air roadway. The outlet water temperature were below 25°C all boreholes.

CFD modeling of optimal airflow rates for safe production in isolated mining faces with high methane concentration and coal spontaneous combustion

From the perspective of airflow rate adjustment for disaster prevention, controlling methane concentration and reducing spontaneous combustion zone in the goaf naturally contradict. Generally, an increased airflow rate is beneficial in reducing methane concentration but also increases the risk of coal spontaneous combustion. Coal pillars on both sides of an isolated mining face are broken to form air leakage passages, which connect its goaf and the two sides of the goafs to form triple goafs. Especially for triple goafs of the isolated mining faces with high methane concentration and coal spontaneous combustion tendencies, the lack of air leakage law and knowledge of the distribution of methane and oxygen concentrations makes disaster prevention and control difficult. To solve the above problem, this study adopts a computational fluid dynamics (CFD) modeling method to construct a physical model containing triple goafs and investigate the optimal airflow rates for safe production, with an isolated mining face in a mine in Guizhou taken as an object. Results show that the air leakage paths in the triple goafs of the isolated mining face mainly consist of “U–shaped” and “semi–U–shaped”. The optimal airflow rates to maintain methane concentration at safety limits and to minimize the spontaneous combustion zone in the triple goafs are 1800 m3/min to 2000 m3/min. In consideration of economic efficiency and workload, the optimal installation spacing of the dynamic barriers is determined as 15.0 m–20.0 m. The study results provide scientific concepts and practical guidance for the prevention and control of methane and coal spontaneous combustion hazards in triple goafs of isolated working faces.

Compositional Difference and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons over the Coal Spontaneous Combustion Zone

In this study, the U.S. Environmental Protection Agency prioritized polycyclic aromatic hydrocarbons (PAHs), associated pollution level, and health risks were assessed in a typical coal spontaneous combustion zone in the Rujigou coal mine in Northwestern China. This study used gas chromatography-mass spectrometry (GC-MS) to detect the chemical composition, spatial variation, distribution profiles, impact of coal spontaneous combustion, and health risks of PAHs. The entire study area is divided into three zones according to different features: the spontaneous combustion zone (C-zone), the living zone (L-zone), and the non-spontaneous combustion zone (N-zone). The results showed that: (1) the highest concentrations were measured in the C-zone, and the average concentrations of PAHs in the C-zone, N-zone, and L-zone were 13.28 ng·m−3, 9.56 ng·m−3, and 7.67 ng·m−3, respectively. (2) The PAHs of the study area were mainly composed of three ring to five ring PAHs. (3) EPA positive matrix factorization (PMF) analysis of qualitative source apportionment of PAHs showed that chemical production was the major source of atmospheric PAHs in all three zones, followed by coal combustion. (4) The inhalation of PAHs showed higher potential cancer risk for children than for adults, and the impact of coal combustion in the C-zone was much greater than the other zone. The adverse health impacts associated with PAH exposure indicates the need for mitigation measures of pollution control in this region.

Determination of Hazardous Zone of Coal Spontaneous Combustion in Ultra-Long Working Face Based on the Gob Porosity Evolution and Flow Field Distribution

Coal fire remains one of the main hazards of underground work. Spontaneous coal fires cause serious casualties and property losses. At present, most of the studies on coal spontaneous combustion have been conducted on working faces shorter than 200 m. However, the ultra-long working face gob of shallow buried coal seam is much larger, the distribution of its flow field is more complex, and, thus, risk of spontaneous combustion in the gob is higher. Exploring the evolution law of the gob flow field of ultra-long working face to quickly determine the range of the coal spontaneous combustion hazardous zone is of great significance to the safe production of similar mines. In this study, the gas flow field distribution in the gob of an ultra-long working face was measured by buried pipeline method and oxygen concentration was used as the index. It is found that the oxygen concentration decreases with the advance of the working face. Based on the flow field distribution, the oxidation zone of the gob was determined. Meanwhile, a three-dimensional (3D) numerical model of the working face was established, and the overlying stratum collapse and porosity evolution in the gob were simulated using the particle flow software, PFC3D discrete element software, for the porosity distribution law of the gob. The obtained porosity data were then imported into FLUENT using the custom function UDF to construct a 3D grid model. The flow field distribution in the gob was then numerically simulated for the seepage and migration law of the wind flow in the gob. The results reveal an arch-shaped wind flow field distribution with a swirl shape on the intake airway side. In the strike direction, the wind flow gradually becomes weaker with the advance of the working face. In the dip direction, the wind flow seepage range on the return airway side is obviously higher than that on the intake airway side. In the vertical direction, the wind flow range in the upper gob is larger than that in the middle and lower gob. The spontaneous combustion and oxidation zone of the gob is determined to be at 140.4–313.3 m on the intake airway side, 201.2–351.6 m in the middle of the gob, and 153.2–328.1 m on the return airway side. Finally, the residual coal distribution was superimposed onto the oxygen concentration distribution to obtain the spontaneous residual coal combustion hazardous zone in the gob.

Variation of the mass susceptibility of sandstone after high-temperature heating

Burnt rocks usually exhibit magnetic enhancement, which can be used to detect the spontaneous combustion zone of a coal fire or locate the resources in burnt rocks. To elucidate the mechanisms underlying magnetic enhancement, sandstone is heated to high temperatures between 100 and 1200°C. The mass susceptibility of the sandstone is measured after cooling, and the magnetic characteristics are explained based on the changes in colour and porosity, thermogravimetric and differential thermal analysis experiments and the observation of thin sections of rocks and scanning electron microscopy images. The findings are as follows: (1) the magnetic susceptibility of sandstone increases rapidly by two orders of magnitude as the temperature rises above 800°C. (2) The oxidation of iron ions and the formation of magnetite enhance the magnetic susceptibility of sandstone. The formation of magnetite at 800°C significantly enhances the magnetic susceptibility. (3) The highest temperature experienced by a burnt rock can be evaluated by analysing the different responses of the susceptibility of sandstone to temperature. Furthermore, it is possible to use the magnetic anomaly of the burnt rock to locate it and develop and utilise the beneficial resources in the burnt rock.

Study on Regional Distribution of Spontaneous Combustion in Goaf of Deep Inclined Working Face and Effect of Low Temperature Inert Gas Injection

ABSTRACT Affected by the occurrence conditions, the inclination angle of the goaf and the ground temperature change the caving structure and temperature rise environment of the goaf, which in turn affects the distribution range of the spontaneous combustion zone in the goaf. During the process of inert gas injection, the cooling and diffusion range of the inert gas determines the its inerting effect. In this paper, the temperature-programmed experiment was used to obtain the oxygen consumption rate of coal at different temperatures. Fluent simulation showed that when no inert gas was injected, the scope of the spontaneous combustion zone on the inlet side moved backward and expanded, while the gas in the gob on the return air side overflowed, and the spontaneous combustion zone The range becomes smaller; when inert gas is injected at low temperature, the influence of different inert gases (N2, CO2) on cooling and diffusion distribution is quite different, CO2 accumulates at the bottom of the goaf, and the influence range is larger; And the space inerting effect is better; the spontaneous combustion area is affected by the injection of inert gas, and there is a risk of secondary re-ignition when the inert gas injection ends.

Study on multi field coupling numerical simulation of nitrogen injection in goaf and fire-fighting technology

In order to effectively prevent the spontaneous combustion of residual coal in goaf, taking the 10,101 fully mechanized top coal caving face of Baozigou coal mine as research object, the multi-field coupling numerical model of nitrogen injection in goaf is established. The FLUENT software is used to study the variation law of spontaneous combustion zone in goaf under dynamic mining of working face with different nitrogen injection parameters, determining the range of spontaneous combustion zone in stable stage. The fitting curve between nitrogen injection parameters and width of spontaneous combustion zone in goaf is obtained. Results show that with the increase of nitrogen injection depth from 10 to 60 m, the width of spontaneous combustion zone in goaf begins to decrease gradually, yet the width of spontaneous combustion zone tends to expand after more than 40 m. When the nitrogen injection location is 40 m, the spontaneous combustion zone width decreases from 49 to 22 m as the nitrogen injection volume increases from 500 to 1000 m3/h. Nitrogen injection continuously reduces the area of high temperature zone and temperature extreme value. When the nitrogen injection parameter is set to (40 m–1000 m3/h), temperature extreme value decreases by 308.85 K compared with that without nitrogen injection. When the nitrogen injection parameter is (40 m–690 m3/h), it can meet the inert cooling requirements of goaf. The width of spontaneous combustion zone is 31 m and the temperature extreme value is 309.95 K at the moment. Finally, engineering application of the fire prevention technology combining shot-off loss wind and nitrogen injection is used to test effect of spontaneous combustion prevention and verify accuracy of nitrogen injection simulation. CO concentration at the measuring point 1, 3 and 5 are reduced to 0 × 10−3‰, 2 × 10−3‰ and 1.2 × 10−3‰, and temperature are reduced to 295.15 K, 296.15 K and 295.65 K respectively. It shows that the spontaneous combustion of residual coal in goaf has been successfully controlled.

Monitoring the spontaneous combustion zone of a rock-coal massif using the ground-penetrating radar method

Introduction. Endogenous fires are common and one of the most complex types of accidents in the mining industry. The main cause of endogenous fires is oxidation of combustible rock by oxygen. Existing fires significantly complicate mining operations, lead to the loss of coal reserves prepared for excavation, expensive coal-mining equipment, and cause huge economic losses associated with firefighting operations. Fired areas are sources of emissions of gases harmful for breathing into the atmosphere, so the environmental damage is also very significant. Due to the fact that endogenous fires are difficult to predict and forecast, especially in their initial stages, their study is relevant to scientists of the leading research institutes of the mining industry. Research objective is to investigate and analyze the effectiveness of the ground-penetrating radar (GPR) method for diagnosing the spontaneous-combustion zones of the rock-coal massif. Methods of research. In order to assess the effectiveness of the GPR method, field experimental studies on the recognition and localization of underground fires were carried out. In order to determine the informative value of this method, wells were drilled and geological data was compared with the GPR survey results. Results. The site of an active underground fire was visually inspected to predefine the combustion areas; inspection results were presented in the paper. Using the method of GPR sounding and based on the typical anomalous zones location on fire radiograms, the fire sources were diagnosed by depth and on the plan. Boreholes were drilled to study the lithological structure of the rock mass. Additional GPR sounding was aimed at defining the width of the fire in plan more precisely. Conclusions. The GPR method makes it possible to obtain on-line data on the location of coal massif spontaneous-combustion zones and their sizes. This technology contributes to timely measures for preventing the development of underground fires in the territories of mines and open pits surface plants.

Prevention and Control of Spontaneous Combustion of Residual Coals in Acid‐Soaked Goaf in Gas Drainage Condition

With the increase of mine mining intensity, the scope of goaf continues to expand, a large amount of coal remains in goaf, and the spontaneous combustion fire of coal is particularly serious. In addition, the spontaneous combustion of coal under the condition of gas mining is not clear. At once, spontaneous combustion can induce gas explosion, resulting in the waste of manpower and material resources, bringing hidden dangers to the mine safety production. In order to prevent and control the fire caused by spontaneous combustion of left coal under the condition of gas mining, in this paper by means of laboratory test, field measurement, and numerical simulation, the law of spontaneous combustion of residual coal under gas mining is studied. The index gas of coal spontaneous combustion was determined by temperature‐programmed experimental device. Secondly, the distribution of the stope working face, goaf, and O2 is discussed. It is of great significance to study the spontaneous combustion rule of three belts in goaf under acid leaching condition and then to discuss the best position of injection idling opening and put forward targeted precontrol measures, which is of great significance to guarantee the safety of mine production. The results show that CO begins to appear when the temperature rises to 40 °C, and its concentration increases exponentially with the increase of coal temperature, which can reflect the degree of coal oxidation in goaf. Therefore, CO should be selected as the indicator gas in the working face. Under the influence of negative drainage pressure, the dangerous area will be enlarged. The optimal drainage volume of high drainage roadway is 90 m3/min, and the optimal air intake volume of working face is 1400 m3/min. The area 0–34 m away from the working face is scattered zone, 34–135 m away is spontaneous combustion zone, and 135 m away is asphyxiation zone. When the position of the idler is 50 m behind the working face, the reduction of the oxidation zone is the largest.

Division Method of Coal Spontaneous Combustion Zone in Multi-layer Goafs Based on Fracture Development Law

ABSTRACT In order to accurately divide the coal spontaneous combustion area of multi-layer goafs in shallow coal seam group so as to take effective control measures, a mathematical model is established on the basis of the seepage equation of porous media and the balance equation of oxygen concentration to study the development law of fracture channel under the influence of repeated mining. The results show that the boundary of the goaf has a higher degree of deformation and damage than the inside of the goaf. With the advance of the working face, the position of the area with large porosity in the back becomes higher, while the area with large porosity above the mining space continues to expand forward and maintain a slender shape. According to the theoretical and experimental analyses, the goaf of 22409 working face in Nantun Coal Mine is divided into extremely easy air leakage area, easy air leakage area, weak air leakage area and hard air leakage area.

Distribution of spontaneous combustion three zones and optimization of nitrogen injection location in the goaf of a fully mechanized top coal caving face.

In order to effectively prevent and control spontaneous combustion of residual coal in the goaf and reduce the waste of nitrogen caused by setting the position of nitrogen injection, 1303 fully mechanized coal caving faces of the Jinniu Mine are studied. By deploying a bundle tube monitoring system in the inlet air side and return air side of the goaf, changes in gas concentration in the goaf are continuously monitored. In addition, the distribution area for spontaneous combustion three-zone in the goaf is divided into heat dissipation zone, oxidized spontaneous combustion zone, and suffocation zone. Simulations from the COMSOL Multiphysics 5.3 software provide insight based on the three zones division standard of spontaneous combustion in the goaf. The gradual deepening of the nitrogen injection position into the goaf affects the lower limit of the oxidized spontaneous combustion zone significantly, but the impact on the upper limit of the oxidized spontaneous combustion zone is not obvious and is negligible. With regard to the width of the oxidized spontaneous combustion zone, it initially decreases followed by a gradual increase. Numerical calculations suggest the optimal nitrogen injection position is 40 m from the roof cutting line, with an oxidized spontaneous combustion zone width of 28 m. Based on the simulation analysis results, nitrogen injection controlling measures have been adopted for spontaneous combustion of residual coal in the goaf of the 1303 fully mechanized coal caving faces, and coal self-ignition in the goaf has been successfully extinguished.

Goaf Gas Control Improvement by Optimizing the Adjacent Roadway Large-Diameter Boreholes

This study introduced gas control technology in goaf using adjacent roadway large-diameter (550 mm) boreholes to control gas accumulation in the upper corner of a fully mechanized working face in high-gas coal seams. The gas control process in the upper corner and gas interception in goaf by large-diameter boreholes was analyzed using the CFD model of the gas flow in goaf. The latter considered the control equation of gas flow, the established permeability model of goaf, and the gas emission law in goaf. Using the 2-105 working face of the Tenghui Coal Mine, Shanxi Province, China, as a case study, the distribution patterns of gas concentration and flow field in the goaf for various extraction flow parameters and different positions of boreholes were numerically simulated. The dependences between various locations, drainage flows, and the gas concentration in the upper corner were determined and fitted by engineering equations. The evolution pattern of the spontaneous combustion zone in the goaf under the drainage conditions was also analyzed. The optimal borehole configuration parameters ensuring the extraction flow rate exceeding 3 m·s−1 and the effective gas control in the upper corner of the working face at a distance of 5 m–15 m behind the working face were identified. The engineering practice proved the feasibility of gas control in the goaf using the adjacent roadway large-diameter borehole. The gas concentrations in the return airflow and the upper corner of the working face were kept below 0.65 and 0.8%, respectively, to ensure production safety and improve the gas utilization efficiency.

Research on determining reasonable negative pressure based on the control of the goaf

In order to study the law of spontaneous combustion in goaf under the condition of gas extraction, the method of beam tube monitoring and numerical analysis is adopted to obtain three dimensional distribution of oxygen concentration and contour map under the condition of different negative pressure. Based on the way of regression analysis, reasonable negative pressure are determined. The results show that with the increase of negative pressure, the spontaneous combustion “three-zone” in goaf: the heat dissipation zone and the spontaneous combustion zone become wider and the suffocation zone narrows. At the same time, the trend of spontaneous combustion zone presents to the deep part of the goaf; the amount of gas extraction increases first and then decreases with the increase of negative pressure. Combined with the trend of spontaneous combustion zone and the amount of gas extraction in goaf, and the reasonable negative pressure value is 32kpa and verified.

Determination of the Spontaneous Combustion Hazardous Zone and Analysis of Influencing Factors in Bedding Boreholes of a Deep Coal Seam.

Accurately determining the spontaneous combustion zone of coal around the borehole plays an important role in preventing borehole accidents. To solve the problem of dividing the hazardous zone of spontaneous combustion in boreholes, a fully coupled model of the gas flow, coal oxidation reaction, and energy transportation is developed in this study. Taking the drainage borehole of the 24130 working face in the No. 10 Coal Mine of the Pingdingshan mining area as an example, the proposed model is used to simulate the seepage velocity field, oxygen concentration field, and temperature field of the coal around the borehole. The simulation results are found to be consistent with the field test results. Based on the simulation results, the coal around the borehole is divided into two areas in the axial direction of the borehole. The intersection of the seepage velocity u ≤ 0.004 m/s and oxygen concentration 7% ≤ C(O2) ≤ 21% are considered the “hazardous zone”, and the union of the oxygen concentration C(O2) < 7% and seepage velocity u > 0.004 m/s are considered the “safety zone”. The influences of various factors inducing spontaneous combustion of coal around the borehole on the hazardous zone are revealed by analyzing the drainage negative pressure, sealing length, and roadway temperature. The results show that reducing the drainage negative pressure and increasing the sealing length can effectively restrain the spontaneous combustion of the borehole and can also help reduce the scope of the hazardous zone of the borehole. Finally, a reasonable arrangement of the predrainage period in the appropriate season can also effectively inhibit the spontaneous combustion of coal around boreholes.

CFD Numerical Modelling of Spontaneous Combustion of Loose Coal in High Caved Area of Underground Roadway

Coal fires are serious health and safety hazards throughout the world. In underground, coal spontaneous combustion process often starts with the inside of coal, which makes it difficult to determine the ignition point. For example, the coal fire happened in high caved area of roadway is often hard to be noticed. Once the smoke appears, it has already been late to take control measures. In this paper, Simulation analysis of microcirculation flow field velocity distribution, temperature distribution and the possible distribution of the coal spontaneous combustion zone are preformed which could provide a good scientific and reasonable understanding of the fire risk due to microcirculation in loose coal in underground roadway.

Numerical Assessment of the Influences of the Coal Spontaneous Combustion on Gas Drainage Methods Optimization and Its Application

ABSTRACT Gas and spontaneous combustion of coal have seriously threatened the production safety and efficiency during the process of mining. Gas drainage can reduce the risk of gas while it may intensify the self-ignition of coal. In order to study the certain relationship between these two issues, the south 906 working face of Dalong Coal Mine was taken into research. The physical geometrical and mathematical model was established. Numerical investigation based on Fluent was conducted to identify the gas concentration distribution and air leakage field under four different gas drainage methods, such as high drill holes drainage (HDHE), buried pipe drainage (BPE), adjacent roadway drainage (ARE), and tail roadway drainage (TRE). The simulation results show that all these four gas drainage methods are able to control the gas concentration in the air return corner, so as not to exceed the certain limit (1%). However, these methods have also enlarged the area of spontaneous combustion zone with 1.11, 1.30, 1.61, and 2.10 times, respectively. According to the comprehensive analysis on simulation results, HDHE has the minimal influence under the same gas drainage amount. This gas drainage method was then applied in the aforementioned working face. The follow-up monitoring data proved our research results, with CO concentration in the drainage pipes always keeping lower than 0.0024% and gas concentration in the air return corner maintaining no more than 0.70%. The study provides significant references for managing the gob where exists symbiosis disaster of gas explosion and spontaneous combustion of coal.

Study on Distribution Law of Spontaneous Combustion “Three Zones” in Goaf of Fully Mechanized Mining Face with Large Mining Height

In order to explore the large mining height are broken coal seam fully mechanized working face goaf spontaneous combustion “three zones” under the different height of distribution, through the establishment of numerical model, builds the working face goaf spontaneous combustion “three zones” three-dimensional sampling analysis system, through the analysis of oxygen, carbon monoxide, carbon dioxide and other coal spontaneous combustion index gases change law of goaf spontaneous combustion dangerous area under different heights for the division, the goaf three-dimensional spontaneous combustion dangerous area is determined. The results show that the “spontaneous combustion zone” of goaf in fully mechanized coal face of large mining height gradually widens along the vertical height, and the spontaneous combustion risk area becomes larger.