Study on the formation mechanism of a radon source during coal spontaneous combustion in a goaf

Lu, Zhifan; Zhou, Bin; Wang, Junfeng; Chan, Zhikang; Yang, Qifan; Dong, Zhiyu; Dong, Kaili

doi:10.1016/j.fuel.2022.127135

Cited by 9 publications

(5 citation statements)

References 25 publications

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“…These conditions often prompt the transfer of moisture and gas from high-stress areas to low-stress areas within the rock mass, which alters the underground migration and accumulation of gas and water. These effects cause radon gas to accumulate in the goaf and decrease in nearby areas [70]. Radon migrates through the goaf and fracture zones to the surface, which causes a noticeable anomaly on the surface that corresponds to the shape of the goaf below.…”

Section: Radiometric Explorationmentioning

confidence: 99%

“…They highlight the potential of radon as a tracer and precursor in various hydrogeological and geological applications. Lu et al [70] studied the principles of radon gas transport in goafs and changes in the migration mode under coal self-ignition conditions. Their results can be used as a basis for locating goafs, subsidence columns, uranium ore bodies, tectonic fracture zones and groundwater resources.…”

Section: Radiometric Explorationmentioning

confidence: 99%

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Methods for the Geophysical Exploration and Sustainable Utilisation of Coalbed Methane Resources in Abandoned Mines of Shanxi, China

Liu,

Li,

2024

Sustainability

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Underground coal mining results in large goafs and numerous abandoned mines that contain substantial amounts of coalbed methane. If this methane is not used and controlled, it will escape into the atmosphere through geological fractures and can result in serious greenhouse gas effects and environmental damage. Exploring and developing the coalbed methane resources of abandoned mines can not only improve coal mine safety and protect the ecological environment but also reuse waste and mitigate energy shortages. Geophysical methods have made some progress in detecting abandoned coal mines, but there are still some challenges and difficulties. The resolution of seismic exploration may not be enough to accurately describe the details of coal seams and CBM rich areas, and the effect of resistivity method in deep CBM exploration is limited. In addition, the geological structure of abandoned coal mines is usually more complex, such as faults, folds, etc., which makes the application of exploration methods more difficult and increases the difficulty of data interpretation. Therefore, it is necessary to develop and perfect exploration technology continuously including the application of geophysical big data, deep learning, and artificial intelligence inversion to realize the accurate detection and evaluation of CBM resources in abandoned coal mines.

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Section: Radiometric Explorationmentioning

confidence: 99%

Section: Radiometric Explorationmentioning

confidence: 99%

Methods for the Geophysical Exploration and Sustainable Utilisation of Coalbed Methane Resources in Abandoned Mines of Shanxi, China

Liu,

Li,

2024

Sustainability

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“…By substituting Y in Equation (32) into Equation ( 31) and taking the derivative with respect to time t, the approximate equation of temperature of the coal field can be obtained:…”

Section: Theoretical Derivationmentioning

confidence: 99%

“…The analysis of the effect of oxygen concentration on the initial heating time of coal shows that gas insertion in goaf is conducive to preventing the development of coal spontaneous ignition. 32,33 However, experiments 34 show that the critical oxygen concentration to prevent spontaneous combustion of coal is a variable and depends on many other factors. The adsorption property of coal and gas penetration rate have the greatest influence on the critical oxygen concentration.…”

Section: Initial Oxygen Concentrationmentioning

confidence: 99%

Dependence evaluation of factors influencing coal spontaneous ignition

Wu,

Yao,

Chen

et al. 2023

Energy Science & Engineering

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Coal spontaneous combustion is determined by a variety of factors. Testing can describe the changes incoal spontaneous combustion with various factors, however, the dependence of spontaneous combustion on various factors is unclear. Therefore, reliability theory was used to deduce the functional relationship of the dependence of coal spontaneous combustion on various factors, and construct a model algorithm for predicting the probability of occurrence of coal spontaneous combustion, which is adopted to evaluate and rank the degree of influence of various factors on coal spontaneous combustion. Effective prevention methods are proposed by strengthening the role of the most important factors. The results show that, by taking the duration of coal heating to 150°C as the measurement standard of coal spontaneous combustion, the duration of the initial stage of coal heating increases linearly with the increase of specific heat capacity, thermal conductivity, and moisture content of coal. With the increase of oxygen concentration, oxidation rate, and initial temperature of the coal, the duration of the initial stage of coal heating decreases exponentially. With the increase of gas flow seepage velocity in the coal body, the duration of the initial heating stage changes in a parabolic manner. At the same time, the probability of spontaneous combustion decreases exponentially with the increase of specific heat capacity and moisture content of the coal. The probability of coal spontaneous combustion increases linearly with the increase of coal thermal conductivity, oxygen concentration, gas seepage velocity, and rate of oxidation. The dependence of coal spontaneous combustion probability on different factors can be expressed as follows: coal temperature > gas seepage velocity > specific heat capacity > oxidation rate > oxygen concentration > moisture content > thermal conductivity.

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“…The fire source location provides information about changes in the physical and chemical properties of coal and its surrounding rocks. Technologies for the fire source location includes temperature [5][6][7][8], gas concentration [9][10][11][12], radon concentration [13][14][15], magnetic field [16], resistivity [17], and numerical simulation [18], et al Zhang et al [19] used oxygen concertation as the indicator to identify the residual coal spontaneous combustionprone region. Pi et al [20] laid thermocouple thermometry and bundle tube monitoring system into the goaf to measure the fire location.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional inverse problem of fire location in the closed goaf of coal mine based on optical fiber sensors

Liu,

Chen,

Wang

et al. 2024

PLoS ONE

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Monitoring the temperature to determine the fire source locations is essential for controlling the spontaneous combustion in the goaf. Optical fiber sensors are employed to measure the temperature distribution in the goaf. However, due to changes in the geological conditions and the influence of the falling rocks in the goaf, only sensors on the upper side of the uncompacted goaf, due to inclination and coal pillar, may remain. Unilateral sensors are located on the upper side of the goaf, while fire occurs in the center. To investigate the issue with linear unilateral sensors, a two-dimensional inverse method has been developed to determine the location of fire sources by considering heat transfer after a fire inside the goaf. The equations were theoretically solved using Green’s function method to obtain the internal temperature distribution of the physical model of the goaf. Sensitivity analysis identified the most crucial parameters in the process of spontaneous heating at different temperature. The fire source location can be determined using a loop method based on the model calculations. We considered a case to validate the model. Accurately identifying the fire source location in the goaf using the unilateral sensors has an essential theoretical and practical significance for fire prevention and fighting.

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Study on the formation mechanism of a radon source during coal spontaneous combustion in a goaf

Cited by 9 publications

References 25 publications

Methods for the Geophysical Exploration and Sustainable Utilisation of Coalbed Methane Resources in Abandoned Mines of Shanxi, China

Methods for the Geophysical Exploration and Sustainable Utilisation of Coalbed Methane Resources in Abandoned Mines of Shanxi, China

Dependence evaluation of factors influencing coal spontaneous ignition

Two-dimensional inverse problem of fire location in the closed goaf of coal mine based on optical fiber sensors

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