Biao Kong

The coal gangue waste dumps formed by open-pit coal mining are prone to low-temperature oxidation and heat storage, creating deep hidden high-temperature abnormal areas, continuously releasing toxic gases, and causing complex disasters such as slope instability and water and soil pollution. At present, self-ignition prevention and control technology is only applicable to the shallow treatment of small and flat gangue mountains. For large, deep, high-temperature waste dumps with significant height differences, multiple steps, and large areas, there is a lack of an integrated, complete set of technologies. The multi-field coupling mechanism of grouting fire extinguishing lacks engineering verification, and there is no quantitative evaluation system combining long and short periods. This paper takes the deep spontaneous-combustion high-temperature area of the No. 5 spoil dump of Lutian Coal Mine of Wuhai Energy as the research object. With the core goals of precisely delineating the fire zone space, revealing the multi-field coupling fire extinguishing mechanism of grouting, and establishing a long-term quantitative evaluation system, this study proposes a multi-process joint governance technology, along with a standardized hole filling and zoned differentiated grouting parameter system. The research systematically demonstrated technical feasibility through on-site drilling, large-scale grouting construction, and full-process quality control and error analysis. The results show that the 50 m interval geothermal gradient boreholes can accurately identify high-temperature distributions in the deep part of the dump from 0 to 34 m. The maximum combustion depth of the fourth-level and fifth-level platforms is 34 m and 20 m, respectively. A total of 1578 grouting boreholes have been constructed, with a total grouting volume of 139,289.3 cubic meters. After the treatment, the concentrations of toxic gases were all below the detection limits of the equipment, and the single cooling range reached 43% to 87%. This research refined relevant theories on the spontaneous combustion control of large-scale multi-step waste dumps, established standardized engineering processes, and provided theoretical and engineering references for the prevention and control of spontaneous combustion of solid waste in similar mines. It holds significant value for the ecological safety of mines and regional pollution control.

The coal mine production safety hazards are large, and the situation is difficult, and coal mine workers are affected psychologically, producing unsafe psychological states and triggering unsafe behavior. This paper firstly studies the interactive influence process of the unsafe psychological state of coal mine workers and reveals the emergence process of unsafe psychology and behavior of coal mine workers. According to the characteristics of qualitative simulation of safety behavior, safety psychology and unsafe state of coal mine personnel, 23 simulation schemes are designed, and simulation analysis is carried out using QSIM simulation software platform. According to the simulation results of 23 schemes, the dynamic emergence process of safety behavior, safety psychology, and unsafe state of coal mine workers was sorted out from the aspects of different states and the intensity of different management measures, and the law of the effect of coal mine workers' safety psychology on safety behavior and safety state was obtained , revealing the interactive influence of coal mine workers' psychology on the unsafe state and the internal evolution mechanism of the emergent process. It is of great theoretical and practical significance for coal mine safety management to study the interaction of hazardous psychological states of coal mine workers and the dynamic generation mechanism of the emergence process of unsafe behaviors.

Acoustic emission (AE) technology has the advantage of online localization to study the change laws of AE in the process of coal spontaneous combustion and to reveal the generation mechanisms of AE signal during the process of heating and rupture of coal body from a microscopic perspective. This paper first constructs a large-scale coal spontaneous combustion AE test system and conducts experimental tests on the AE signal in the process of coal spontaneous combustion. The results show that with the increase of temperature in the process of coal spontaneous combustion, the AE signal shows a trend of increasing fluctuations. Low-temperature nitrogen adsorption experiments studied the pore structure of coal spontaneous combustion, and the results showed a correspondence between the development of pores and the temperature of coal spontaneous combustion. Further, through the analysis of the evolution of the pore structure of coal through Fourier transform and fractal theory, it is found that the high-frequency main frequency AE signal and average frequency are continuously enhanced with the increase of temperature. The fractal dimension of the pore structure and the fractal dimension of the AE count of the coal body first rise and then decline. The mechanism of coal spontaneous combustion AE of coal is revealed, and the pore development caused by thermal stress when coal heats up is the main source of AE signal generation. The research in this paper is of great significance for applying AE technology to detect the position of coal spontaneous combustion.

A WG/C/XG (water glass/sodium carboxymethyl cellulose/xanthan gum) gel was created in this study by incorporating a tracer indicator into the fire protection material. The gel is both a tracer and flame retardant. First, scanning electron microscopy, UV spectrophotometer, and chromatography-mass spectrometer was used to characterize the samples. The microstructure of the WG/C/XG gel was investigated, as well as its impact on high-temperature response. The average rate of tracer gas release varies significantly before and after 55°C. Moreover, the release patterns of the two tracer gases are similar, indicating that the WG/C/XG gel is suitable for the solid loading of tracer gases. A thermal analyzer and programmed warming oxidation experiment analysis were used to investigate the inhibitory effect of WG/C/XG gel on the oxidation of spontaneous coal combustion. The experimental results demonstrated that the WG/C/XG gel improved the thermal stability of coal samples and inhibited spontaneous coal combustion. In mined areas, WG/C/XG gel is an excellent tracer material.

Coal spontaneous combustion (the term is hereafter abbreviated as CSC) is an important problem facing by China to achieve carbon peak and carbon neutrality. CSC affects the mining process of mining for a long time, not only causing a large amount of waste of coal resources, but also severely destroying the ecological environment. At present, filling & plugging materials (the term is hereafter abbreviated as F&P materials) is widely welcomed and developed rapidly because of its advantages of wide application, obvious performance and low price. Based on the research of the prevention and control of CSC and the materials applying for it, this paper creatively puts forward an application system of materials used for the prevention and control of CSC. The types of F&P materials are systematically summarized. According to the form of materials, the F&P materials are divided into slurry, colloid and foam. The performance and effect of three kinds of F&P materials are analyzed in detail. On this basis, the cost and environmental protection characteristics of F&P materials in China were compared and evaluated. Finally, this paper predicts the development of F&P materials. This paper provides an effective reference for Chinese coal mining enterprises to select suitable F&P materials, which is of great significance for the prevention and control of CSC and environmental protection.

At present, aging mines are faced with development bottlenecks such as lack of national policy support, serious problems left over from history, and difficulties in enterprise transformation and development, which seriously restrict the safe production and sustainable development of aging mines. In order to deeply analyze the influencing factors of group unsafe behavior in aging mines, the evolution law of unsafe behavior is qualitatively simulated and quantitatively analyzed to realize the safety evaluation of group unsafe behavior in aging mines. Based on this analysis of the emergence mechanism and influencing factors of unsafe behavior in aging mines, the evaluation index of unsafe behavior in the aging mine population was established. These include six criterion layers and 30 index layers; the mutation level value of the target layer is 0.9405. Group dynamic effect and safety management factors are the two important factors restricting their development and safety. The unsafe behavior of the aging mine groups was evaluated based on game theory and system dynamics—dynamic game simulation on the influence of unsafe behavior in aging coal mines. A qualitative simulation analysis was also performed using the QSIM algorithm. The evolution law of the safety psychology and behavior of aging mine workers are analyzed. This paper shows the importance of the unsafe behavior of aging mines, which helps the safety production and clarifies the safety psychology and the behavior evolution law. This paper puts forward new methods and theories on the safety psychology and behavior evolution law of the safety behavior and provides a reference for the sustainable development of aging mines.

High temperature causes thermal damage to rock; the macrofracture and microfracture of rock can be produced under the action of temperature treatment. Under the influence of high temperature, the surrounding rock of deep underground engineering will suffer instability damage and cause serious harm to the people. In order to use the electromagnetic radiation (EMR) technology (a non-contact geophysical method) for evaluating the thermal stability of rock in underground thermal engineering applications, we established the EMR testing experimental system of rock under the action of a continuous heat source. The variation of EMR signals of rock under different temperatures was tested, and the EMR signals generates during the process of rock thermal deformation and thermal fracture, which were later analyzed. Under the action of a continuous heat source, the rock materials produced EMR signals with three kinds of frequencies. With the increase of rock temperature, the variation trends of EMR signals varied from the slow growth rate to the rapid growth rate, EMR signals can be divided into five stages. The increase of EMR signals is positively correlated with temperature, the Hurst exponent was higher than 0.7. The thermal stress was responsible for thermal deformation and fracture, thus generating the EMR signals. The research results have important guiding significance for the application of EMR technology to the evaluation of rock thermal stability.