Coal Spontaneous Combustion Research Articles

Study on radon gas transport law of overlying rock layer under different geological conditions of coal spontaneous combustion

Study on radon gas transport law of overlying rock layer under different geological conditions of coal spontaneous combustion

Compound disaster characteristics of rock burst and coal spontaneous combustion in island mining face: A case study

The island mining face in coal mines often encounters stress concentration and significant air leakage, elevating the risk of rock burst and spontaneous combustion of residual coal in the goaf. This study centers on the investigation of the 9305 island mining face within a mine situated in Shandong Province, China. Leveraging the features of coal spontaneous combustion and data from microseismic and gas monitoring throughout the mining process, a novel method for calculating safe mining speeds under compound disasters is introduced. The safe mining speed of the 9305 island mining face is stratified, and a prevention and control technology integrating long distance directional drilling for impact-spontaneous combustion compound disasters is proposed. Findings suggest that to mitigate spontaneous combustion of residual coal, considering the seam's spontaneous combustion tendency, the safe mining speed should exceed 3.7 m per day. Accounting for the distribution of microseismic events during coal seam extraction, the safe mining speed is maintained below 4.8 m per day in the unprotected mining area and capped at 8 m per day in the protected zone. Through a comprehensive analysis considering coal seam spontaneous combustion tendency, impact tendency, and time to coal seam oxidation to critical temperature, the safe mining speed for the island mining face ranges from 3.7 m per day to 4.8 m per day in the unprotected area and from 5.14 m per day to 8 m per day in the protected area. The proposed long distance directional drilling 'one hole, multiple purposes' scheme enables an integrated approach encompassing pressure relief before coal seam extraction, water injection during mining, and grouting post-mining. This method effectively prevents and controls the compound disasters of rock burst and coal spontaneous combustion, presenting innovative technical solutions for the safe extraction of coal resources.

Numerical Investigation of coupling hazard zone of coal spontaneous combustion and gas in gob for high-gas mines

As coal mining operations continue to deepen, the frequency of coal spontaneous combustion (CSC) and gas explosion disasters in high-gas mines is increasing. Understanding the distribution patterns of CSC and gas compound disaster zones in the gob during the extraction process is crucial for reducing the risks of combustion and explosion. This study focuses on the 201 working face of the Shuanglong Coal Mine, where a multi-physical field coupling model of pressure, temperature, gas seepage, and diffusion was established to investigate the evolution characteristics of compound disaster zones and propose corresponding prevention and control measures. The results demonstrate that the area with the most severe composite hazard is mainly located at the return roadway side, extending to the middle of the gob. With increased ventilation volume and advance rate, the area of the CSC and gas coupling hazard zone expands continuously. By implementing measures such as brattice cloth and nitrogen injection, the areas of spontaneous combustion and CH4 explosion zones were reduced by 53.6 % and 49.5 %, respectively, effectively controlling the extent of the compound disaster zone and eliminating the risk of gas explosions.

Influences of surface active-groups on the exothermic properties and oxidation of coal molecules

In this study, coal samples' reactive group contents were changed using extractants, and the effects of the reactive group contents spontaneous coal combustion were investigated using infrared spectroscopy, thermogravimetry/derivative thermogravimetry, and differential scanning calorimetry. The results showed that the coal samples' hydroxyl group contents decreased in the order ethylenediamine (3.832 %) > N-methyl-2-pyrollidone mixed solution (2.091 %) > petroleum ether (0.882 %) > toluene (0.495 %) and that the hydroxyl group content was inversely related to the characteristic temperature point. RDG analysis showed that ethylenediamine formed N–H–O hydrogen bonds with hydroxyl-group-bearing molecules, coal molecules formed C–H–O hydrogen bonds with NMP molecules, petroleum ether generated a cumulative dispersive force with aliphatic side chains, and toluene molecules' benzene rings formed a very stable spatial structure with coal molecules' benzene rings. The thermogravimetry/derivative thermogravimetry curves showed that because the characteristic temperature points of the extracted coal samples moved to the high-temperature region from T5 onward, the coal samples had to be heated to a higher temperature to reach the energy required for the reaction. From the DSC thermograms, the exergy decreased in the order toluene (110.68 J/g) > NMP (110.52 J/g) > ethylenediamine (78.29 J/g) > petroleum ether (65.45 J/g). With increasing temperature from T1 to T6, the Pearson correlation coefficients of the alcoholic and phenolic hydroxyl groups were calculated at −0.7, −0.72, −0.93, −0.84, −0.8, −0.8, and −0.93 and −0.72, −0.91, −0.83, −0.79, −0.815, and −0.91, respectively, indicating that the hydroxyl group content influenced the coal's spontaneous combustion more than the other groups' contents.

Synergistic inhibition kinetics and mechanisms of polyethylene glycol – citric acid on non-caking coal oxidation at low temperature

ABSTRACT Focused on the insufficient efficacy of conventional flame retardants in mitigating coal spontaneous combustion (CSC), a novel composite flame retardant synthesized from polyethylene glycol (PEG) 2000 and citric acid (CA) is proposed. Through Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) experiments, the inhibitory kinetics and mechanisms were conducted. By enhancing heat absorption rate and enthalpy, with a significant increase by 90 kJ·mol−1 of activation energy, CSC resistance is improved. CA-metal ion interaction raises activation energy to inhibit methyl/methylene oxidation, while PEG disrupts aromatic oxidation by generating H ions upon hydration. This composite retardant offers a promising avenue for CSC mitigation in coal, enhancing coal fire safety.

New exploration on the goaf inerting with hidden fire source under CO2 injection volume of adsorption compensation

To strengthen the rationality of the design of CO2 injection volume in goaf, a framework is proposed to study goaf inerting characteristics with hidden fire sources under CO2 injection volume of adsorption compensation. The zone of hidden fire source is determined by similar simulation experiment of coal spontaneous combustion on a working face of coal mine. The range of injection volume without adsorption is calculated theoretically. A three-dimensional initial flow field model of coal spontaneous combustion is established combined with field measurement. The error of oxidation zone width is 3.64 %, which verifies the reliability of model. The influence of injection volume on the inerting effect in goaf is studied, and optimal injection volume without adsorption is 1000 m3/h. Based on the relationship between adsorption capacity and temperature, a quantization model of injection volume with adsorption compensation is established. The maximum dissipation ratio is then proposed. The optimal injection volume after adsorption compensation is calculated. The results show that intermittent injection of gaseous CO2 is recommended under simulated conditions. The maximum dissipation ratio is 1/4, and the CO2 injection volume compensated by adsorption is 1333 m3/h. The research results can provide theoretical guidance for the optimization of CO2 inerting parameters in goaf.

Study on the Inhibition Performance of a Lipoic Acid Microcapsule Gel Composite Inhibitor in the Spontaneous Combustion of Coal

ABSTRACT In order to improve the inhibition performance of an inhibitor, a microcapsule material was prepared with modified chitosan and lipoic acid as the main raw materials, and a gel material was prepared with polyethylene glycol and sodium alginate. By combining the microcapsule and gel, a composite inhibitor SAA/PEG-MALA was finally obtained, with a good inhibition effect and a long-lasting inhibition time. A scanning electron microscopy experiment showed that SAA/PEG-MALA has a unique radioactive pore structure, thus improving the moisture absorption and water retention performance. A thermogravimetric experiment showed that, after treatment with SAA/PEG-MALA, the characteristic temperature of the coal samples were increased, of which the dry cracking temperature T2 was increased by 16.9°C, and the thermal decomposition temperature T5 was increased by 72.2°C. A differential scanning calorimetry experiment showed that the transition temperature of an SAA/PEG-MALA-inhibited coal sample increased by 31.6°C, and the heat release decreased by 5828.0 J/g. A thermogravimetric infrared experiment showed that the average inhibition rate of the SAA/PEG-MALA was 94.04%, and its average inhibition life was 27.43 min. These results indicate that SAA/PEG-MALA can effectively inhibit the spontaneous combustion of coal.

Microscopic mechanism of oxygen consumption inhibitor delaying the oxidation of coal

In order to inhibit the coal-oxygen complex that triggers spontaneous coal combustion, a retardant consisting of sodium alginate solution, sodium bicarbonate, inorganic salt MgCl2 and deoxidiser that can achieve multiple effects of hysteresis and oxygen depletion was developed. Taking the sulfur-containing side-chain reactive group of coal molecule -CH2-SH as the object of study, the Gaussian 16W procedure and density-functional-transfer theory (DFT) were applied to investigate the electrostatic potential and reaction tendency, oxygen adsorption capacity, front-line orbitals, natural bonding capacity, and oxygen adsorption capacity of the reactive group before and after the formation of the complexes with Na+ and Mg2+, using the solvation effect at the level of B3LYP/6-31G(d, p), respectively. The changes of electrostatic potential and reaction tendency, oxygen adsorption, front orbitals, natural bonding orbitals and charge transfer before and after the formation of complexes between -CH2-SH reactive groups and Na+, Mg2+, respectively. Comparative analysis of the interaction with oxygen before and after the formation of coordination blocking structure of coal and inorganic salts in gaseous environment, aqueous environment and retarded oxygen-depleting sodium alginate blocking solution environment, respectively. The calculated results show that the side chain of the aromatic ring of the raw coal is the active site for easy adsorption of oxygen, and the stability of the coordination blocking structure is significantly enhanced under the environment of hysteretic oxygen-depleting sodium alginate gel blocking agent, and the adsorption of oxygen before and after the coal molecule combines with Na+ and Mg2+ is the weakest under the environment of hysteretic oxygen-depleting sodium alginate gel blocking agent; The absolute value of the HOMO orbital energy increases the most, and the energy level difference (ELUMO - EHOMO) of the complexes increases the most; the natural bonding orbital analysis reveals that the lone pair of electrons of S atoms in -CH2-SH under the environment of hysteresis oxygen depletion sodium alginate gel blocker has a strong coordination effect with Na+ and Mg2+. In the hysteresis oxygen depletion sodium alginate gel resist environment, the stability of the coordination blocking structure is strengthened due to the moderateness of the dielectric constant, and its oxygen depletion also reduces the number of O2 molecules, which further reduces the adsorption and collision chances between the two, and a more desirable blocking effect can be obtained. The results reveal the micro-mechanism of the hysteresis oxygen depletion inhibitor in preventing spontaneous combustion of coal, which can provide a reference for further improving the inhibition effect of the inhibitor.

Thermal index parameter investigation of coal–oxygen adsorption during low-temperature oxidation of coal

Oxidative spontaneous combustion is an inherent property of coal. In which, coal oxygen adsorption heat is the decisive speed step of coal spontaneous combustion self-acceleration process, and coal oxygen adsorption heat is closely related to coal pore structure. By utilising an automatic physicochemical adsorption instrument, it was found that the form of pore existence in coal was dominated by mesopores, that the pore structure, oxygen uptake capacity and temperature varied non-linearly, and that pore size was positively correlated with pore volume; Using a self–built air adsorption calorimetric experimental system, it was found that when oxygen was involved in the adsorption reaction, the presence of oxygen would lead to a significant time lag in the adsorption equilibrium. Additionally, the transition temperature of coal adsorption mode has been determined to be 40 °C, shedding light on the mechanism behind the thermal self-accelerating reaction of coal oxygen adsorption; Using the correlation method, it was obtained that the index affecting the physical adsorption heat release is the percentage of mesopore volume in the coal, while the index affecting the chemical adsorption heat release is the pore size. The research findings are anticipated to offer theoretical backing for advancing flame-resistant materials.

Study on preparation and performance of bagasse/sodium carboxymethyl cellulose gel for inhibiting coal spontaneous combustion

In order to effectively prevent and control coal spontaneous combustion and improve the safety of coal mining, bagasse carboxymethy cellulose (BCC) prepared from bagasse (BS) and sodium carboxymethyl cellulose (CMC) were used as the substrates. A gel (BCC-CMC) for inhibiting coal spontaneous combustion was prepared using a chemical crosslinking method involving zirconium citrate crosslinking and glucono-delta-lactone (GDL) modification. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize both the crystal and molecular structure of bagasse and its derived bagasse carboxymethyl cellulose. The results indicated that new carboxymethyl groups were introduced into bagasse during the treatment, facilitating the successful extraction and preparation of sodium carboxymethyl cellulose. The results of viscosity and bonding tests demonstrated that the concentration and dosage of CMC had the most significant influence on the gel viscosity, which remained higher and more stable at room temperature. The coal bonded by the gel coal mixture can effectively seal surface cracks, with a bonding degree of up to 70.72 %. TG-DTG, temperature-programmed oxidation experiment and FTIR analyses revealed that, compared to raw coal, coal samples treated with gel exhibited improved stability, fewer active groups, and fewer oxygen-containing functional groups, effectively inhibiting coal’s low temperature oxidation and reducing the risk of spontaneous combustion. The gel is environmentally friendly, cost-effective, and exhibits good flame retardant properties. This study is of great significance for preventing and controlling coal spontaneous combustion, effectively ensuring the safe production of coal resources and the safety of mine workers, achieving the green sustainable development of the mine.

Experimental Study on Spontaneous Combustion of Low Rank Coal Containing High Sulfur in Goaf Atmosphere

Experimental Study on Spontaneous Combustion of Low Rank Coal Containing High Sulfur in Goaf Atmosphere

Study on the Spontaneous Combustion Law of Coal Body around a Borehole Induced by Pre-extraction of Coalbed Methane.

To address the challenges associated with the high gas content, high pressure, and low permeability coefficient in deep coal seams, strategies such as infilling boreholes and increasing the negative pressure of extraction are commonly implemented to alleviate issues related to coalbed methane extraction. However, long-term mining pressure can lead to the development of cracks in the coal seam near the borehole, thereby creating air leakage channels, which could potentially impact the oxygen supply during the extraction process. This leads to secondary disasters such as the spontaneous combustion of coal and gas explosions, considerably impacting the life and health of underground workers. To solve this issue, a thermal-fluid-solid coupling model for the working surface was constructed based on numerical simulation software, taking into account the multimechanism coupling effect of coal seam gas. The laws of coal oxidation and spontaneous combustion induced by coalbed methane extraction around boreholes were studied. The variation laws of the oxygen concentration, coal temperature, and oxidation heating zone around the borehole under different extraction conditions were simulated and analyzed. The findings demonstrate that the negative extraction pressure enables the gas to penetrate the fracture zone of the borehole, leading to an increase in the oxygen consumption rate and coal temperature around the borehole with an increase in negative extraction pressure. The coal gas leakage surrounding the borehole reduces as the sealing depth increases, and both the heating rate of coal and oxygen volume fraction show a downward trend. The fitting relationship between the negative pressure of drainage, depth of sealing, and temperature change in the coal body surrounding the boreholes was identified. It was determined that the negative pressure of 13 kPa for borehole drainage and a sealing depth >18 m are the optimal extraction parameters. The range of the oxidation zone and the position of the boundary line under this parameter were predicted, and the position function of the dangerous area of oxidation heating was defined. The research results have remarkable implications for the coordinated prevention and control of gas and coal spontaneous combustion in coalbed methane predrainage boreholes, as well as for efficient prevention and control of CO in on-site gas extraction boreholes, thus ensuring efficient and safe gas extraction.

Preparation and Effectiveness of a Nano-Modified Composite Gel Foam in Preventing the Spontaneous Combustion of Coal

ABSTRACT In China, coal is considered the cornerstone in the energy mix for ensuring the security of national energy production. With the increasing intensity and depth of coal seam mining in China, spontaneous coal combustion in goaf areas has become a major issue affecting mine safety. The development of a nano-modified composite gel foam to prevent the spontaneous combustion of residual coal was therefore investigated in the current study. Chemical modification through intercalation and grafting was found to significantly enhance the water retention performance of the antioxidant component. In addition, the optimal component ratios were determined using single-factor experiments and response surface methodology. The modified gel foam, consisting of 2.995 wt% gelling agent, 0.25 wt% foaming agent, 0.296 wt% crosslinker, 0.491 wt% foam stabilizer, 3.772 wt% nanoparticles, and 2.964 wt% modified antioxidant, demonstrated environmental friendliness. Thermogravimetric experiments showed that the critical temperature for achieving a significant increase in the dehydration rate rose from 80 to 120°C after modification. Compared with typical inhibitors, the nano-modified gel foam exhibited a superior performance in terms of preventing coal oxidation and spontaneous combustion, particularly at low temperatures. Oxidation during the oxygen absorption and weight gain stages was also effectively inhibited, and the high temperature combustion processes were suppressed.

Study on multi-field coupling characteristics of underground coal combustion and nitrogen injection parameter optimization

Underground coal fires, which are widely distributed and cause serious resource waste and environmental hazards, have become a common concern of the international community. This paper aims to reveal the mechanism of coal spontaneous combustion and the expansion law of underground coal fires. A void rate model from the goaf to the ground surface and a multi-field coupling model for underground coal fires were established. Based on which, the combustion process from the beginning of oxidation to the formation of large-scale fire of the remaining coal in goaf was analyzed. Furthermore, the evolution law of underground coal fire after nitrogen injection and the influence of different nitrogen injection parameters were analyzed. The results show that the coal spontaneous combustion can be divided into three stages: slow reaction stage (stage Ⅰ), violent combustion stage (stage Ⅱ), and stable combustion stage (stage Ⅲ), and the transformation of different stages is mainly controlled by the oxidation reaction rate of coal. To obtain the optimal parameters for nitrogen injection for fire suppression, the fire extinguishing efficiency concerning nitrogen injection time, nitrogen injection amount and nitrogen injection position, as well as the distribution law of nitrogen in rock strata were analyzed. Through range analysis, it is determined that the most effective fire extinguishing occurs with the injection rate of 0.15 m3/s in stage I, and the injection position has little influence on the fire extinguishing effect. This understanding contributes to a deeper understanding of the multi-field coupling mechanism of underground coal fires and provides a guidance for extinguishing and preventing underground coal fires.

Investigate on spontaneous combustion characteristics of lignite stockpiles considering moisture and particle size effects

Coal spontaneous combustion (CSC) threatens the safety of the coal industry, with moisture content and particle size being pivotal factors. This study examines the heating dynamics and critical self-ignition temperatures (CSITs) of Baiyinhua lignite stockpiles through wire-mesh basket (WMB) tests at two scales. The CSC process in coal stockpiles unfolds in four stages. Notably, Stage II is notable for significant moisture evaporation between 43 and 84 °C, while Stage IV marks the onset of self-heating. Moisture evaporation absorbs heat, linearly prolonging the Stage II duration, which accounts for 0%–70 % of the total time. Conversely, larger particle sizes enhance pore seepage, effectively shortening the heating time. The time for d = 20 mm (particle size) coal sample to reach ambient temperature is roughly half that of 1.5 mm. CSITs of raw coal increase by 10–15 °C compared to the dry coal, and CSIT of coal samples with d = 50 mm has increased by 17.5 °C compared to 10 mm. Therefore, both an increase in particle size and moisture content increase the CSIT, thereby reducing the propensity for CSC. Frank-Kamenetskii theory and dimensionless analysis predict spontaneous combustion risks in field-scale coal stockpiles. This investigation contributes valuable insights to the estimation and prevention of CSC.

The novel inorganic solidified foam prepared by direct foaming and its characteristics for preventing spontaneous combustion of coal

ABSTRACT To mitigate coal spontaneous combustion disasters caused due to air leakage in coal mines, inorganic solidified foam is widely employed to seal these areas. This study proposes a simplified method for preparing such foam by directly foaming a mixture of water, cement, fly ash, and foaming agent. This new inorganic solidified foam plugging material aims to enhance sealing effectiveness. The research investigates the foaming ability and stability characteristics of different types of surfactants, analyzing their compatibility with cement and fly ash. It identifies that lauramidopropyl surfactant (LX) exhibits the lowest viscosity in the cement-fly ash slurry mix, resulting in superior foaming performance. By studying effects of water-cement ratio and foaming agent concentration on the foaming performance of cement-fly ash slurry mix, it is found that when the water-cement ratio is 0.6 and the foaming agent concentration is 0.5%, the foaming performance of inorganic solidified foam is optimal, yield the highest foaming efficiency with a multiple of 4.33 times and compressive strength of 0.13 MPa, effectively bonding and reinforcing fractured coal bodies to sealing air leakage cracks efficiently. This study contributes to simplifying the preparation equipment and the application processes of inorganic solidified foam, making it more suitable for widespread application in the confined spaces of coal mines, providing a new technical approach for preventing and controlling coal spontaneous combustion in mines.

Experimental study on coal oxidation and temperature rise under different air leakage modes due to atmospheric pressure changes

ABSTRACT The spontaneous combustion of residual coal in enclosed goafs may induce coupled thermodynamic disasters with severe consequences. To study the dynamic characteristics of coal oxidation and temperature increase in an enclosed goaf under varying atmospheric pressure conditions, the air leakage model was analyzed through theoretical derivation. The resistance, temperature, and CO concentration during coal oxidation under different air leakage modes were further studied using a self-built experimental system. The results indicated three air leakage modes of coal oxidation in an enclosed goaf: constant, intermittent, and reciprocating. The resistance of the three modes increased from 5 Pa to 7 Pa with time. Compared to constant air leakage, the time of resistance change was advanced by 1428 s and 1897 s under intermittent and reciprocating air leakage, respectively. Additionally, both intermittent and reciprocating air leakage promote coal oxidation and produce higher CO levels compared to constant air leakage. However, intermittent air leakage is more likely to produce higher temperature points, while reciprocating air leakage is more likely to cause large areas of coal oxidation. The order of the promoting effect of the intermittent and reciprocating half cycle on coal oxidation is 60 s, 300 s, 600 s, and 1200 s. These results are significant for understanding coal spontaneous combustion and efficiently managing enclosed goafs.

Study on dynamic variation of acid-base properties of coal and its influence on environment during oxidation and heating

ABSTRACT The spontaneous combustion of coal poses a serious threat to production and environmental safety. Currently, scholars have conducted extensive research on the mechanisms and prevention methods of coal spontaneous combustion. However, these studies have not sufficiently addressed the changes in coal’s acid-base properties during combustion and their impact on environmental pH balance. This gap hinders a comprehensive understanding of coal combustion and precise fire suppression. This study focuses on the changes in the acid-base properties of coal during critical periods of spontaneous combustion prevention. The results showed that as the temperature increased, BJG becomes more alkaline, with a pH of 8.08 at 75°C, while HLS becomes more acidic, with a pH as low as 5.14. The aqueous solutions mainly contained SO4 2-, CO3 2-, and HCO3 −, with the SO4 2- concentration in HLS being about 200 times higher than in BJG. Additionally, this study innovatively analyzed the impact of organic substances on the acid-base properties of coal. It was found that the content of organic groups, mainly -COOH, increased by over 300%. However, the influence of pyrite is greater than that of organic acids and CO2. Furthermore, the consumption of H+ by minerals significantly reduces the acidity of the solution.

Research on the Potential of Persistent Free Radicals Triggering Open-Pit Coal Oxidation and Spontaneous Combustion

ABSTRACT This study attempts to reveal the triggering pathways of open-pit coal oxidation and spontaneous combustion from the perspective of persistent free radicals (PFRs). To this end, electron spin resonance technology, spin trap technology, and quantum chemical calculations were combined to study the occurrence characteristics of PFRs in coal and their photoreaction characteristics. Based on typical coal molecular fragments, the mechanism of PFRs triggering open-pit coal oxidation was further revealed. The results indicate that coal contains abundant PFRs, which produce reactive oxygen species (ROS) after exposure to sunlight, mainly including hydroxyl radicals (•OH) and superoxide anion radicals (O2 •−). Among them, the higher the initial content of PFRs or the longer the time of sunlight exposure, the more favorable it is for the production of •OH, the concentration of photoinduced •OH remains at the level of 1011 spin/mm3. Compared to O2 in the air, these photoinduced •OH have stronger oxidizing properties and can trigger free radical chain reactions of coal oxidation at room temperature (activation energies ＜ 40 kJ/mol), releasing reaction heat (average enthalpy change is −65.53 kJ/mol). As a common oxidant in coal spontaneous combustion (CSC) process, O2 does not possess these abilities (activation energies greater than 190 KJ/mol and enthalpy change greater than 160 KJ/mol). From the perspectives of thermodynamics and kinetics, PFRs in coal have the potential to indirectly trigger open-pit coal oxidation and spontaneous combustion. Therefore, the efficient quenching of PFRs or inhibiting the production of •OH will be beneficial for preventing the oxidation and spontaneous combustion of open-pit coal. This study provides a new perspective on revealing the mechanism of CSC and developing new inhibitors.

Identification of CO Source in Return Airway Corner Based on Oxygen Isotope Method: A Case Study

ABSTRACT The problem of CO exceeding the limit in the return airway corner of low-stage coal seriously affects fire prediction and forecasting as well as the health and safety of operating personnel. Identifying the sources of CO in return airway corner can help in the adoption of targeted measures to reduce the risk of coal spontaneous combustion (CSC). In this paper, a method based on oxygen isotope is proposed to identify the source of CO accumulation in return airway corner. Laboratory experiments (pyrolysis, ambient temperature oxidation [ATO], and crushing) and field tests (CO testing in the goaf and working face) were conducted to study the pattern of CO generation and field distribution and to obtain gas samples. The δ18O relationship between different sources of CO was analyzed by combining the results of18O tests of CO from experiments and in the field. Results show that the coal seam does not contain primary CO. The CO in the return airway corner originates from ATO and crushing of the coal. The coal sample can produce CO quickly during the first stage of oxidation at room temperature and during the crushing process, and it has a good linear relationship with time. The δ18O average of CO in the goaf is 26.41‰, which is close to ATO. The mean value of δ18O of CO in the return airway corner is 24.49‰, which is located between ATO and crushing. The calculated proportions of CO in the return airway corner originating from ATO and crushing were 87% and 13%, respectively. The study’s findings provide fresh perspectives for the prevention and control of CSC.