Mine Fire Research Articles

Mine Fires, Experiences in Extinguishing Large Underground Mine Fires

Mine fires are common the underground exploitation of mineral raw materials. With the development of mining science and practice, the methods of extinguishing mine fires using new methods and materials were also developed. Today, in mining practice, direct fire extinguishing with water or fire extinguishers, isolation of oxidation zones with insulating walls, installation of torket concrete on the walls of the pit room or use of special foams are most often used. Methods based on ventilation methods or the use of inert gases can also be encountered. All these methods are used to extinguish local oxidation processes, fires are localized in a part of the pit, ventilation department or goafs. This paper presents methods of extinguishing a mine fire where the fire zone covered a larger area and it was not possible to localize it in one part of the underground mine, the pit is completely closed and isolated until the oxidation process subsides due to lack of oxygen. At the time of the complete closure and isolation of the pit, several gas detectors remained in operation in the pit, through which the change in the composition of the pit air could be monitored during the still active pit fire. At the same time, samples of the pit atmosphere behind the isolation walls were regularly taken, their analysis was performed and they were compared with the data obtained using active gas detectors. The key question was when to reopen the pit, conduct an inspection and try to reactivate the pit operations. Although it is an underground brown coal mine, some experiences and knowledge can be applied and used in underground mines of other mineral resources threatened by pit fires. Experiences can also be applied in case of fire, where it is possible to control the fire zone only through insulating walls. It was established that changes in the activity of the pit fire were manifested both on the insulation walls and on the active gas detectors.

Comparative analysis of different CFD turbulence models for a diesel pool combustion event in an underground mine: a case study

ABSTRACT Underground mine fires are dangerous, consume resources, and emit pollutants. Therefore, acquiring in-mine data for fire research is hazardous and expensive due to unsteady temperature changes and toxic gas emissions. Computational fluid dynamics (CFD) models are often developed to mimic airflows and combustion-associated heat transfer. However, research on the performance evaluation of the CFD turbulence models to mimic fire events is limited. This paper summarises the modelling results for a diesel pool fire event in an experimental underground mine that uses an exhaust ventilation system. A fire dynamics simulator (FDS) model was developed to show the spatio-temporal temperature evolution. Reynolds-Averaged Navier-Stokes and large eddy simulation (LES) models were developed using ANSYS Fluent to model species transportation in the transient-state combustion event. LES models showed the closest agreement with the experiments but required the most computing resources. Similar exercises will assist the mine operators in emergency preparedness and in training their safety teams.

Research on the Dynamic Model of Emergency Rescue Resource-Allocation Systems for Mine-Fire Accidents, Taking Liquid CO2 Transportation as an Example

After a mine-fire accident occurs, a large number of emergency resources need to be allocated to rescue those involved in the mine-fire accident. The allocation of emergency resources for mine-fire accidents has the characteristic of being a complex system with strong uncertainty. To investigate the impact of various variables on the allocation of emergency resources in mine-fire situations, this paper analyzes the relevant factors that influence the process of allocating emergency resources during mine fires. It defines the variables of the mine-fire emergency resource-allocation system based on relevant assumptions. Causal loop and stock flow diagrams are drawn to illustrate the relationships between the variables and the system dynamics equation. Finally, a system dynamics model for mine-fire emergency resource allocation is established. The Vensim software was used to simulate the model of a mine-fire emergency rescue. The simulation produced curves for the evolution rate of the fire, the arrival rate, the demand for emergency resources, in-transit resources, arrival, and the usage of resources during the emergency. The results indicate a positive correlation between the quantity of emergency resources in-transit and the arrival rate of emergency resources: they are positively correlated with the amount of emergency-management investment. Additionally, the duration of the maximum quantity of emergency resources in-transit is positively correlated with the length of the emergency resource-allocation route. On the other hand, the evolution rate of the mine fire and the arrival rate of its emergency resources are negatively correlated with the level of emergency management. The evolution rate of the mine fire becomes larger and the damage caused by the mine-fire accident is greater when the decision-making ability of commanders is at a low level.

Safety Wearable for Miners

INTRODUCTION: Mining is the process of extraction of valuable minerals, ores and other non-renewable resources from the Earth’s surface. The mining industry is known for its hazardous and highly risky working environment. OBJECTIVES: The mining industry is involved in the extraction of these geological materials, which is essential for the development of the country and its economy. However, this industry comes with its fair share of risks and dangers. Recent statistics show that around 100 miners fall victim to the harsh working conditions every year. METHODS: Explosions due to Methane and coal dust followed by roof collapses, mine fires, gas outburst, blasting accidents, poisoning and suffocation are the major reasons out of these few of them causes deaths inside the mines. RESULTS: Even though many precautions are suggested, and measures have been taken to improve the safety of the miners and to improve the work environment, but mines are still unpredictable, and accidents are also recorded then and there. CONCLUSION: The existing safety technologies and measures have either failed to monitor multiple vital features that could lead to fatalities, or to provide adequate and appropriate rescue resources in time to help the miners in danger.

Determination of Sulfur Content in Mineral Mass for Prediction of Hazardous Properties of Coal Mine Seams

Introduction. Sulfur is found in the organic and mineral parts of all types of solid fuels, and its concentration determines the extent of the hazardous characteristics of mine seams. Therefore, research on the determination of sulfur content in fossil fuels has not lost its relevance. The total sulfur content and its varieties has been studied in most cases in terms of the efficiency of fuel processing processes, the quality and environmental safety of coal products. Less attention was paid to the hazardous properties of mine seams, forecasting and developing preventive measures for endogenous fires in coal mines. This work aims to develop an engineering method to calculate the elemental sulfur content in the mineral mass of coal to predict the hazardous properties of mine seams.Materials and Methods. According to the results of the correlation analysis, we established how the sulfur content in the combustible part of the fuel depended on the total sulfur. We analyzed data on coals from almost all mine seams of the Donetsk and Lviv-Volyn coal basins. We presented the ash ratios for the formation and basin samples, as well as the information about the total sulfur and sulfur content in the combustible part. This allowed us to estimate the sulfur content in mineral impurities by calculation. The initial data for developing the method were taken from reference and regulatory documents.Results. Seven sets were considered, which included from 149 to 1827 mine seams. For each, reference and calculation data were summarized:- sulfur content — total (Std) and in the combustible part of the fuel (Sг);- conditional points for adjusting the indicators to avoid obtaining negative average values;- empirical equations that describe the calculated and corrected dependencies based on the ratio of Std and Sг;- correlation of these indicators;- ranges of change in ash yield.All this information was presented for clean and raw coals, for ash yields of more and less than 10%. In one case, satisfactory results were noted for determining the calculated sulfur content in a conditionally non-combustible mass. This was a set of 149 mine layers. For 13 of them, the difference in indicators (Std – Sг) was greater than or equal to zero. For 136 — less than zero. For 81, the sulfur content in the conditionally non-combustible part of the fuel Sн was less than zero. At the same time, there was a sufficient level of correlation (0.79) and a limited range of changes in ash yield (2.4–10). The empirical equation corresponding to this set was recommended for predicting the hazardous properties of mine seams with an ash yield of less than 10%.Discussion and Conclusion. The results of this study can be used to improve regulations for the safe conduct of mining activities, taking into account sulfur content in organic matter and in mineral impurities of fossil coal.

Investigation of a conveyor belt fire in an underground coal mine: Experimental studies and CFD analysis

Coal produced in underground mines is transported to the surface by means of conveyor belts throughout long roadways. The combustion of belts puts a large number of employees at great risk. Underground collieries differ from other underground mines -due to the combustible nature of the product. The most prevalent cause of belt fires in underground coal mine is spontaneous combustion due to oxidation of the coal, which also enables the conveyor belt to burn over time. In 2014, a belt fire in an underground coal mine in Manisa-Soma, Turkey caused 301 fatalities. A study has been conducted on this accident for approximately 3 years, consisting of combustion tests in a purpose-built research gallery, comparison of the test results with mine records of the accident, and CFD modelling of the mine environment. The intensity of the fire was sufficient to redirect the air flow underground, causin large amounts of toxic gases to fill almost the entire mine in approximately 15 minutes. It is recommended that CFD analysis be used in planning emergency action strategies in underground mines.

Research on the Intelligent Planning of Mine Fire Evacuation Routes Based on a Multifactor Coupling Analysis

Efficient evacuation route planning during underground coal mine fires is essential to minimize casualties. This study addresses current shortcomings by proposing a real-time method that integrates a multifactor coupling analysis and the optimized multilayer perceptron regressor-shortest path faster algorithm (MSPFA). This research aims to enhance evacuation route planning by overcoming factors such as inadequate consideration, low accuracy, and information lag in existing methods. This study improves the shortest path faster algorithm (SPFA) for dynamic route planning, mitigates the impact of fixed walking speed parameters using the particle swarm algorithm, and selects the optimal model (MLPRegressor) through the Bootstrap algorithm for estimating personnel walking speeds. Validated through smoke-spread experiments, the MSPFA algorithm dynamically adjusts evacuation routes, preventing toxic passages. Visualization via drawing interchange format (DXF) successfully enhances route comprehension. The MSPFA algorithm outperforms the Dijkstra algorithm with a runtime of 78.5 msand a personnel evacuation time of 3344.74 s. This research establishes a theoretical foundation for intelligent evacuation decision making in underground fire disasters. By introducing the MSPFA algorithm, it provides crucial technical support, significantly reducing the risk of casualties during emergencies.

A study on rapid simulation of mine roadway fires for emergency decision-making

In traditional mine fire simulation, the FDS simulation software has been verified by large-scale and full-size fire experiments. The resulting calculations closely align with real-world scenarios, making it a valuable tool for simulating mine fires. However, when a fire occurs in a mine, utilizing FDS software to predict the fire situation in the mine entails a sequence of steps, including modeling, environmental parameter setting, arithmetic, and data processing, which takes time in terms of days, thus making it difficult to meet the demand for emergency decision-making timelines. To address the need for rapid predictions of mine tunnel fire development, a method for swiftly estimating environmental parameters and the concentration of causative factors at various times and locations post-fire has been devised. FDS software was employed to simulate numerous roadway fires under diverse conditions. Parameters such as fire source intensity, roadway cross-sectional area, roadway wind speed, roadway inclination angle, time, and others were utilized as the input layer for a neural network. In contrast, wind flow temperature, carbon monicide (CO) concentration, fire wind pressure, visibility, and others were designated as the output layer for training the neural network model. This approach established a fire prediction model to resolve issues related to time-consuming numerical simulations and the inability to provide a rapid response to disaster emergencies. The trained neural network model can instantaneously predict the environmental parameters and concentrations of the causative factors at different times and locations. The model exhibits an average relative error of 12.12% in temperature prediction, a mean absolute error of 0.87 m for visibility, a mean absolute error of 3.49 ppm for CO concentration, and a mean absolute error of 16.78 Pa for fire wind pressure. Additionally, the mean relative error in density is 2.9%. These predictions serve as crucial references for mine fire emergency decision-making.

Lung function changes in children exposed to mine fire smoke in infancy.

Chronic, low-intensity air pollution exposure has been consistently associated with reduced lung function throughout childhood. However, there is limited research regarding the implications of acute, high-intensity air pollution exposure. We aimed to determine whether there were any associations between early life exposure to such an episode and lung growth trajectories. We conducted a prospective cohort study of children who lived in the vicinity of the Hazelwood coalmine fire. Lung function was measured using respiratory oscillometry. Z-scores were calculated for resistance (R5 ) and reactance at 5 Hz (X5 ) and area under the reactance curve (AX). Two sets of analyses were conducted: (i) linear regression to assess the cross-sectional relationship between post-natal exposure to mine fire-related particulate matter with an aerodynamic diameter of less than 2.5 micrometres (PM2.5 ) and lung function at the 7-year follow-up and (ii) linear mixed-effects models to determine whether there was any association between exposure and changes in lung function between the 3- and 7-year follow-ups. There were no associations between mine fire-related PM2.5 and any of the lung function measures, 7-years later. There were moderate improvements in X5 (β: -0.37 [-0.64, -0.10] p = 0.009) and AX (β: -0.40 [-0.72, -0.08] p = 0.014), between the 3- and 7-year follow-ups that were associated with mean PM2.5 , in the unadjusted and covariance-adjusted models. Similar trends were observed with maximum PM2.5 . There was a moderate improvement in lung stiffness of children exposed to PM2.5 from a local coalmine fire in infancy, consistent with an early deficit in lung function at 3-years after the fire that had resolved by 7-years.

Analysis of security parameters specific to coal mines

Coal continues to remain a basic energy source for industry, but the impact on the environment and underground security resulting from its extraction and use must be given ever-increasing attention. Ecological impact analysis is currently the most powerful tool for preventing pollution and environmental degradation, respectively for underground security, in any project related to coal mining. The current trend of restricting mining activity in more productive perimeters, but far from the main connections with the surface, implies a substantial increase in the demand for ventilation systems due to underground pollutants and implicitly the continuously increasing risk factors. The particularly complex conditions and with major implications in the security levels of mining operations require the objectification of control by monitoring security parameters, through systems, installations, devices and modern automatic programs in parallel with the manual control system with modern portable devices. The paper analyzes the possibility of monitoring security parameters related to the environment, mine fires and degassing installations specific to mining operations in the Valea Jiului coal basin, in order to remove several risk factors that endanger underground mining. The main safety parameters analyzed refer to the underground environment, endogenous fires and degassing of coal seams. The parameters that are followed in order to assess the efficiency of the degassing networks are: the depression in the degassing network, the methane concentration of the captured gas and the methane flow from the network.

Research on the Optimization of Coalbed Methane Utilization Based on Hydraulic Fracturing Enhanced Permeability Technology

This study presents the solution of the extraction and coal seam. Through the combination of numerical simulation study and field investigation, the fracturing radius is 12 meters after 30 days of hydraulic fracturing in the 6th coal seam, and the implementation measures of fracturing hole spacing of 20 meters and 5 meters were formulated. The results showed that the hydraulic fracturing technology significantly increased the gas concentration of drilling extraction to 93%, and the attenuation rate of gas concentration in 120 days was 14%. This technology has significantly increased the extraction flow, and effectively controlled the occurrence of coal seam fire. The methods and results of this study are instructive for coalbed methane utilization in other mines.

Research on typical fire impact and emergency escape planning in Yushuling Coal Mine

Abstract Mine fire is a very dangerous underground disaster. In order to better study the situation and influence range of mine fire, this paper uses Ventsim to establish a three-dimensional visual ventilation model of Yushuling coal mine. The fire simulation of coal mining face and central substation is carried out by simulation method to study the change law of CO concentration, visibility and temperature in different places. The results show that the CO concentration and visibility change greatly in the downstream of the fire source point when a fire occurs in the coal face; As for the temperature, the temperature at the fire source varies greatly, and the temperature below the inclined air shaft hardly changes; All of them show a decreasing trend with the increase of the distance from the fire source; In case of fire in central substation, there are great changes in all substances in the roadway before and after the air door is opened and closed; After the air door is closed, the CO concentration drops sharply, the change rate at the end of the fire is reduced, the end time is advanced to half of the original, the temperature change is relatively small, and the visibility remains low for a long time after the damper is closed and the recovery time is late. The research results have important guiding significance for the escape of underground fire.

Enhancing fire safety in underground mines: Experimental and large eddy simulation of temperature attenuation, gas evolution, and bifurcation influence for improved emergency response

The occurrence of underground mine fires remains a significant and persistent safety challenge in the mining industry, posing imminent risks to both miners' lives and the operational integrity of mining facilities. Current underground mine fire studies lack scale accuracy due to lab experiments and fail to consider bifurcation effects on smoke gas temperature. This study performed full-scale experiments and built validated CFD models to explore the interactive impact of ventilation and fire size on temperature attenuation, gas behavior, and CO generation in underground mines. A new empirical correlation for temperature decay in the mine drift was developed and its accuracy was compared with established models in the literature. In addition, the influence of bifurcation on maximum smoke temperature was analyzed. This research combines full-scale experiments and validated CFD modeling to address major gaps in underground mine fire studies. Unlike previous methods, this study explores the interactive effects of ventilation, fire size, temperature attenuation, and toxic gas spread, offering unprecedented insights. This innovation enables the development of tailored fire safety standards for mines, ensuring safer designs, rapid fire suppression, and improved evacuation strategies. By bridging theory and practice, this work transforms fundamental knowledge, empowering the mining industry to enhance safety measures, protect lives, and mitigate the impact of underground mine fires.

A rapid dual-drive technology for extinguishing large high-gas coal mines fires

Fires formed by the high gas protrusion in coal mines are difficult and risky to extinguish during the mine closure process due to the mine’s large closed range and underground gas stock. To achieve efficient and safe unsealing, reduce the risk of re-ignition and gas explosion, and accurately determine the fire extinguishing effect, a dual-drive rapid fire extinguishing technology is proposed. This technology involves ground precise positioning of drilling holes, rapid and large flow of liquid nitrogen injection, and curtain grouting to block fires in ultra-large high-gas mines. The practical results demonstrate that the implementation of surface injection of liquid nitrogen for fire extinguishing and cooling, and plugging effectively reduces the concentration of CO in the underground space from 230 PPm to 0 PPm, and decreases the CH4 concentration content from 90% to less than 0.75%. The fire extinguishing and cooling effect is fast and significant. A technical scheme for unsealing the fire area of the whole mine is formulated on a large scale based on the state of pumping and releasing pressure in the closed space of the mine. This scheme has important guiding significance for safety rescue and rescue operations after serious fire accidents occur in similar high-gas prominent mines.

Exposure to air pollution concentrations of various intensities in early life and allergic sensitisation later in childhood

BackgroundEvidence on the relationship between air pollution and allergic sensitisation in childhood is inconsistent, and this relationship has not been investigated in the context of smoke events that are predicted to increase with climate change. Thus, we aimed to evaluate associations between exposure in two early life periods to severe levels of particulate matter with an aerodynamic diameter < 2.5 μm (PM2.5) from a mine fire, background PM2.5, and allergic sensitisation later in childhood.MethodsWe measured specific immunoglobulin E (IgE) levels for seven common aeroallergens as well as total IgE levels in a cohort of children who had been exposed to the Hazelwood coal mine fire, either in utero or during their first two years of life, in a regional area of Australia where ambient levels of PM2.5 are generally low. We estimated personal exposure to fire-specific emissions of PM2.5 based on a high-resolution meteorological and pollutant dispersion model and detailed reported movements of pregnant mothers and young children during the fire. We also estimated the usual background exposure to PM2.5 at the residential address at birth using a national satellite-based land-use regression model. Associations between both sources of PM2.5 and sensitisation to dust, cat, fungi, and grass seven years after the fire were estimated with logistic regression, while associations with total IgE levels were estimated with linear regression.ResultsNo association was found between the levels of exposure at either developmental stage to fire-related PM2.5 and allergic sensitisation seven years after the event. However, levels of background exposure were positively associated with sensitisation to dust (OR = 1.90, 95%CI = 1.12,3.21 per 1 μg/m3).ConclusionsChronic but low exposure to PM2.5 in early life could be more strongly associated with allergic sensitisation in childhood than time-limited high exposure levels, such as the ones experienced during landscape fires.

A Review on Mine Fire Prevention Technology and Theory Based on Bibliometric Analysis

Of all mine disasters, fires are very threatening to mine safety and often lead to the most serious consequences. Research on mine fire prevention technology and theory has experienced significant growth and is attracting escalating academic interest and attention. However, dedicated literature reviews on this topic are scarce. For the purpose of uncovering the research characteristics and trends on mine fire prevention technology and theory, this paper employs bibliometric analysis using the Web of Science Core Collection database. This study presents a detailed analysis of relevant articles published between 2010 and 2022. An assessment of the influences of journals, countries, institutions, and authors was conducted through a citation analysis. Furthermore, this paper describes co-authorship networks among different countries, institutions, and authors. Lastly, a review of the mine fire prevention techniques and theories researched during this period was carried out through a keyword clustering analysis. Four main research topics in mine fire prevention research were identified: “mine fire control technology”, “mine fire occurrence mechanism”, “mine fire prediction technology”, and “mine fire monitoring technology”. Additionally, the theory study of spontaneous combustion and its underlying mechanisms may represent a potential focus for future research. These findings contribute to providing a solid foundation for future research endeavors in this field of fire prevention.

Varying Heat Release Rates per Unit Area – The Impact in Underground Mines

Abstract The fire behaviour and smoke behaviour of a fire in an underground mine will be largely dictated by the heat release rate of the fire. The heat release rate per unit area is generally the output from small-scale fire experiments and can be applied for larger objects with varying surface area. This paper studies the impact of varying heat release rate per unit area for fires in materials and substances typically found underground. Data from earlier fire experiments were analysed and discussed, and several different heat release rate curves and flame spread velocities for various fuel components were developed and discussed. It was found that the hydraulic hose presented the highest peak heat release rate per unit area of the solid fuel items, followed by the low-voltage cable, cab interior, and tyre in descending order. The increase in the peak heat release rate was highest for the highest incident heat flux levels, representative for scenarios underneath a mining vehicle. The heat release rate per unit area of pool fires underneath a vehicle is significantly higher than a corresponding free burning case - attributed to the higher incident heat flux – but a gravel surface underneath a pool fire will reduce the heat release rate considerably. Line fires in larger bundles of electrical cables were modelled and found to attain the peak flame spread velocity more rapidly compared with a fire in hydraulic hoses. This was caused by the higher heat release rate of the initial fire and ignited segments in the electrical cable case.

Microstructural and thermal properties of coal measure sandstone subjected to high temperatures

To study the microscopic structure, thermal and mechanical properties of sandstones under the influence of temperature, coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25 °C–1000 °C. The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy (SEM). Based on thermogravimetric (TG) analysis and differential scanning calorimetric (DSC) analysis, the model function of coal measure sandstone is explored through thermal analysis kinetics (TAK) theory, and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are studied. Through the uniaxial compression experiments, the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are obtained. The results show that the temperature has a significant effect on the microstructure, mineral composition and mechanical properties of sandstone. In particular, when the temperature exceeds 400 °C, the thermal fracture phenomenon of rock is obvious, the activity of activated molecules is significantly enhanced, and the kinetic phenomenon of the thermal decomposition reaction of rock appears rapidly. The mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal decomposition. These research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification (UCG) channels and rock masses subjected to mine fires.

Application of Rapid Identification Technology in Shallow Coal Seam Fire Detection

ABSTRACT Due to the shallow buried depth of shallow coal seam, it is easy to produce cracks through the surface during the mining process, which leads to the occurrence of fire accidents in shallow coal seam. In this paper, a rapid identification method for shallow coal seam fire area is proposed to improve the accuracy and efficiency of radon measurement by increasing the number of single gas extraction and single detection range in radon measurement process. The new method was applied in a mine in Shaanxi, China, and the location and range of the fire area were successfully delineated according to the abnormal value of radon gas. The results show that the new method can reduce the number of measuring points, improve the efficiency of radon measurement, and expand the range of single measuring point to a circular area with a radius of 10 m, which expands the detection range. This provides an important reference for the rapid identification of fire areas in shallow coal seams and the next coal mine fire prevention and extinguishing work.

Experimental Study on the Microstructural Characterization of Retardation Capacity of Microbial Inhibitors to Spontaneous Lignite Combustion

Mine fires are one of the common major disasters in underground mining. In addition to the external fire sources generated by mining equipment and mechanical and electrical equipment during operations, coal is exposed to air during mining, and spontaneous combustion is also the main cause of mine fires. In order to reduce the hidden danger of coal mines caused by spontaneous coal combustion during lignite mining, the microbial inhibition of coal spontaneous combustion is proposed in this paper. Via SEM, pore size analysis, and NMR and FT-IR experiments, the mechanism of coal spontaneous combustion is discussed and revealed. The modification of lignite before and after the addition of retardants is analyzed from the perspective of microstructure, and the change in flame retardancy of the lignite treated with two retardants compared with raw coal is explored. The results show that, compared with raw coal, a large number of calcium carbonate particles are attached to the surface of the coal sample after bioinhibition treatment, and the total pore volume and specific surface area of the coal sample after bioinhibition treatment are decreased by 68.49% and 74.01%, respectively, indicating that bioinhibition can effectively plug the primary pores. The results of NMR and Fourier infrared spectroscopy show that the chemical structure of the coal sample is mainly composed of aromatic carbon, followed by fatty carbon and carbonyl carbon. In addition, the contents of active groups (hydroxyl, carboxyl, and methyl/methylene) in lignite after bioretardation are lower than those in raw coal, and methyl/methylene content is decreased by 96.5%. The comparison shows that the flame-retardant performance of biological retardants is better than that of chemical retardants, which provides an effective solution for the efficient prevention and control of spontaneous combustion disasters in coal mines.