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Advances in Coal Processing, Utilization, and Process Safety
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Advances in Coal Processing, Utilization, and Process Safety

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Energy Systems".

Deadline for manuscript submissions: 31 December 2025 | Viewed by 9072

Special Issue Editors

Dr. Feng Du

E-Mail Website
Guest Editor
School of Emergency Management and Safety Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China
Interests: mining safety engineering; prevention and control of coal rock dynamic disasters; safety and emergency management; theory of gas flow in coal
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Leilei Si

E-Mail Website
Guest Editor
State Key Laboratory Cultivation Base for Gas Geology and Gas Control, Henan Polytechnic University, Jiaozuo 454000, China
Interests: coal mine disaster prevention and control; occupational health; mineral utilization
Prof. Dr. Chaojun Fan

E-Mail Website
Guest Editor
College of Mining, Liaoning Technical University, Fuxin 123000, China
Interests: mining safety engineering; prevention and control of coal rock dynamic disasters; process safety in mining
Dr. Qiming Zhuo

E-Mail Website
Guest Editor
School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China
Interests: deep ash reduction; quality improvement and fine sorting of coal; comprehensive utilization of mineral resources
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The coal industry plays a pivotal role in the global energy supply chain, yet it faces increasingly severe challenges related to safety, environmental concerns, and operational efficiency. Although coal remains a critical energy resource, ensuring its safe extraction, processing, and utilization is of paramount importance. Key issues such as mine safety engineering, gas flow dynamics in coal seams (including rock mechanics, fluid dynamics, seepage theory, and gas dynamics), and the prediction and prevention of coal–gas compound dynamic disasters are at the forefront of current research and technological innovation. Concurrently, advancements in mineral processing and utilization are essential for enhancing the sustainability and economic efficiency of mining operations. Addressing these challenges is crucial for improving productivity and safety in mining operations while minimizing risks to personnel and infrastructure.

In this Special Issue on “Advances in Coal Processing, Utilization, and Process Safety”, we seek to gather high-quality research focused on the latest developments in mine safety engineering, coal seam gas migration theory, mineral processing, and utilization technologies. The Issue aims to explore new methods, models, and technologies that enhance process safety and provide predictive insights into potential risks in coal mining and mineral processing.

Topics include, but are not limited to the following:

  • The latest advancements in mineral processing technologies;
  • Safety and efficiency optimization in mineral utilization;
  • Innovative methods in mine safety engineering and disaster prevention;
  • Mechanisms and prediction models for coal–gas dynamic disasters;
  • Gas migration theory in coal seams and its applications in coal mine safety;
  • Safety and emergency management systems for coal extraction operations;
  • Simulation and predictive modeling of coal seam gas outbursts and rock bursts;
  • New technologies in coal processing and their implications for process safety;
  • Research on coal utilization and its safety impacts;
  • Environmental and safety considerations in coal–gas extraction and utilization;
  • The coal spontaneous combustion mechanism.

Dr. Feng Du
Prof. Dr. Leilei Si
Prof. Dr. Chaojun Fan
Dr. Qiming Zhuo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • mineral processing
  • mineral utilization
  • mine safety engineering
  • coal seam gas flow dynamics
  • coal rock dynamic disasters
  • safety and emergency management
  • predictive modeling
  • process safety in mining
  • intelligent mining

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Published Papers (15 papers)

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14 pages, 5687 KiB  
Article
Mechanism and Application of Static Stress Intervention for Controlled Directional Roof Caving in Fully Mechanized Mining Faces
by Hao Shi, Bingyuan Hao, Xingyun Ren and Ji Zhang
Processes 2025, 13(5), 1552; https://doi.org/10.3390/pr13051552 - 17 May 2025
Viewed by 167
Abstract
To address roof overhang hazards (e.g., rock bursts and gas accumulation) in high-gas coal mines, this study proposes a static stress intervention method for controlled directional roof collapse. Using the 150110 fully mechanized face at Yiyuan Coal Mine as a case study, we [...] Read more.
To address roof overhang hazards (e.g., rock bursts and gas accumulation) in high-gas coal mines, this study proposes a static stress intervention method for controlled directional roof collapse. Using the 150110 fully mechanized face at Yiyuan Coal Mine as a case study, we investigate the mechanical mechanism of static stress intervention-induced roof collapse through theoretical modeling and FLAC3D simulations in the absence of pre-cracks. The study reveals that advanced boreholes filled with static expansion agents generate stress concentration zones along the drilling array. When superimposed with mining-induced stresses, this configuration induces tensile failure preferentially at borehole locations, thereby achieving controlled directional roof collapse. Theoretical calculations indicate that roof fracturing occurs at predetermined locations when expansion pressure reaches ≥9.11 MPa. FLAC3D simulations analyzed stress redistribution and plastic zone evolution under combined static and mining-induced stresses, demonstrating the method’s efficacy in optimizing roadway stability. Field trials implement spaced boreholes (65 mm diameter, 16 m depth, 1 m spacing) with alternating expansion agent charging, achieving a 6 m reduction in roof collapse intervals, effectively mitigating overhang hazards. Results confirm that static stress intervention reshapes the roof stress field, inducing tensile failure along predetermined paths without relying on pre-cracks. The findings provide theoretical and technical insights for roof stability control in high-gas coal mines. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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19 pages, 10188 KiB  
Article
Distribution Characteristics of Mining-Induced Stress Fields and Surrounding Rock Control Technology in Adjacent Working Faces Within Fold Structure Zones
by Jingya Wang, Gao Li, Wencai Wang, Hu Liu, Rui Wang, Hao Zhang and Shengxiao Yuan
Processes 2025, 13(5), 1534; https://doi.org/10.3390/pr13051534 - 16 May 2025
Viewed by 46
Abstract
Mining operations in fold structure zones are often subject to dynamic disasters due to the influence of tectonic topography. To explore the interaction between the tectonic stress field and the mining-induced stress field throughout the entire mining process of adjacent working faces in [...] Read more.
Mining operations in fold structure zones are often subject to dynamic disasters due to the influence of tectonic topography. To explore the interaction between the tectonic stress field and the mining-induced stress field throughout the entire mining process of adjacent working faces in fold structure zones, this study adopts a comprehensive research methodology that integrates field investigations, theoretical analysis, numerical simulations, and industrial experiments. The stress distribution characteristics before and after mining in fold structure zones are systematically analyzed to elucidate the evolution laws of stress and displacement in coal seams, reveal the mechanisms of surrounding rock instability, identify high-risk locations for roof collapse, and propose targeted surrounding rock control strategies for practical application. The key findings of this research are as follows: (1) In fold structure zones, the horizontal stress is significantly influenced by tectonic factors, whereas the vertical stress is predominantly affected by mining activities. (2) The evolution of the mining-induced stress field in fold structure zones is jointly governed by the initial tectonic stress and the mining-induced stress. The advancing position of the working face determines the specific locations of stress concentration, while the tectonic stress regulates the intensity of stress concentration across different regions. (3) The mechanism of surrounding rock failure and instability in fold structure zones is irreversible, with the stress field being a superposition of tectonic and mining-induced stresses. The extent of failure depends on the combined stress concentration at specific locations, which is directly correlated with the distribution of the initial tectonic stress field. (4) Based on the failure patterns of surrounding rock in fold structure zones, a coordinated control strategy incorporating supplementary roof support was developed, along with detailed parameter specifications. The practical implementation of this strategy ensured the stability of surrounding rock during mining through fold structure zones, effectively preventing incidents of roof collapse or rib spalling. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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15 pages, 4390 KiB  
Article
Deformation and Pore Structure Characteristics of Lignite Pyrolysis with Temperature Under Triaxial Stress
by Feng Zhang, Shiwei Niu, Jiawei He, Kai Zhang and Zhongcheng Qin
Processes 2025, 13(5), 1444; https://doi.org/10.3390/pr13051444 - 9 May 2025
Viewed by 241
Abstract
As people pay increasing attention to the clean and efficient mining and utilization of coal resources, efforts to improve the utilization rate of coal, modify coal resources, and carry out coal gasification have become more and more important. The deformation characteristics of lignite, [...] Read more.
As people pay increasing attention to the clean and efficient mining and utilization of coal resources, efforts to improve the utilization rate of coal, modify coal resources, and carry out coal gasification have become more and more important. The deformation characteristics of lignite, the most appropriate coal type for underground coal gasification, are intricately linked to its mechanical properties, permeability characteristics, and mining efficiency throughout the extraction process. The deformation and pore structure characteristics of lignite from room temperature to 650 °C have been studied through high-temperature triaxial penetration testing systems, NMR, and X-CT. As the temperature increases, the porosity of lignite rises, its mechanical strength decreases, and significant deformation occurs, and high temperatures promote pore development in lignite. The axial deformation of lignite pyrolysis is divided into three stages: the dehydration and degassing at room temperature to ~200 °C, the slow deformation between 200 °C and 300 °C, and the pyrolysis deformation from 300 °C to 650 °C. Significant deformation occurs during both the dehydration degassing and pyrolysis deformation stages. Between 250 °C and 650 °C, a large number of highly interconnected pore networks form. Investigating the deformation and pore structure characteristics of lignite is crucial for elucidating its mechanical and permeability features under varying temperature and pressure conditions. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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15 pages, 6246 KiB  
Article
Research and Application of Gas Drainage Negative Pressure Regulation Method Considering Permeability Differences
by Xiaoyu Cheng, Cheng Cheng, Hui Wang, Lu Xiao and Xingying Ma
Processes 2025, 13(4), 1236; https://doi.org/10.3390/pr13041236 - 19 Apr 2025
Viewed by 283
Abstract
This study investigates a dynamic regulation strategy for intelligent gas drainage negative pressure using a comprehensive approach involving numerical simulations, intelligent algorithms, and field experiments. In the numerical simulation component, a permeability evolution model was developed to characterize the area in front of [...] Read more.
This study investigates a dynamic regulation strategy for intelligent gas drainage negative pressure using a comprehensive approach involving numerical simulations, intelligent algorithms, and field experiments. In the numerical simulation component, a permeability evolution model was developed to characterize the area in front of the mining face. Simulations were performed under three negative pressure settings (13 kPa, 18 kPa, and 25 kPa) to investigate the relationships among drainage negative pressure, gas concentration, and flow rate. For the intelligent algorithm, a Long Short-Term Memory (LSTM) prediction model was developed to forecast drainage negative pressure. Based on the predictions, a dynamic regulation strategy for intelligent gas drainage negative pressure was formulated. For field validation, a 120-day in situ experiment was carried out. Intelligent control valves and monitoring instruments were deployed across various sections of the coal seam ahead of the mining face, validating the proposed regulation strategy. The results indicate that permeability is highest in the pressure-relief zone ahead of the mining face and lowest in the stress concentration zone. In the original stress zone, which is unaffected by mining disturbances, the permeability remains unchanged. Drainage negative pressure is positively correlated with gas flow rate, but negatively correlated with gas concentration. In the stress concentration zone, when drainage negative pressure reaches 25 kPa, permeability ceases to be the dominant factor influencing gas flow. At this stage, the pressure gradient between the gas in coal fractures and the drainage system becomes the primary driving force for gas flow. The intelligent dynamic regulation strategy for gas drainage, underpinned by the LSTM prediction model, demonstrated strong performance in field applications. Following intelligent regulation, gas concentrations in various regions showed significant improvement. The findings of this study actively contribute to the advancement of intelligent gas drainage technology. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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22 pages, 12021 KiB  
Article
On the Fluid Behavior Response Characteristics During Early Stage of CBM Co-Production in Superimposed Pressure Systems: Insights from Experimental Analysis
by Jiewei Ren, Qixian Li, Meichang Zhang, Jiang Xu, Yang Li and Pengbin Yang
Processes 2025, 13(4), 1095; https://doi.org/10.3390/pr13041095 - 5 Apr 2025
Viewed by 240
Abstract
The fluid disturbance effect is a significant challenge in CBM (CBM) co-production within superimposed pressure systems in China. To address the unique CBM reservoir of superimposed pressure systems, a CBM co-production experimental apparatus for multi-pressure systems has been independently developed. To comprehensively understand [...] Read more.
The fluid disturbance effect is a significant challenge in CBM (CBM) co-production within superimposed pressure systems in China. To address the unique CBM reservoir of superimposed pressure systems, a CBM co-production experimental apparatus for multi-pressure systems has been independently developed. To comprehensively understand fluid behavior during the early stage of CBM co-production, two sets of experiments were conducted using the self-developed physical simulation test device: one in single-production mode and the other in co-production mode. The dynamic response of reservoir fluids and gas production characteristics were analyzed, and the fluid disturbance mechanism under wellbore fluid confluences was explored. The method adopted in this study addresses the issues of traditional co-production equipment, such as the use of series-parallel core holders, small dimensions, limited monitoring capabilities, single loading methods, and the lack of consideration for wellbore co-production flow disturbance and fluid redistribution in superimposed pressure systems. The following results were obtained: ① A flow disturbance effect emerges when fluids from coal reservoirs with different pressure properties converge and mix in a main wellbore. The pressure inside the four horizontal wells simultaneously reaches 1.45 MPa at t = 0.03 min. ② Based on the fluid disturbance effect, the evolution process of wellbore pressure is categorized into two stages: the confluence disturbance stage and the confluence pressure drop stage. ③ This fluid disturbance effect exacerbates the disparities among coal reservoirs, facilitating fluid exchange between the main wellbore and coal reservoirs through branch wellbores. Under the co-production mode, the instantaneous gas production of the No. 1 coal reservoir reaches its maximum negative value at the moment of production, amounting to −3.85 L/min, indicating that a portion of the fluid from high-pressure coal reservoirs flows back into low-pressure coal reservoirs. ④ A dynamic characterization compatibility method is proposed based on the differences in fluid flow between the single and co-production modes during the early stage of CBM production. For example, at t = 0.1 min, the pressure compatibility coefficients of the No. 1–4 coal reservoirs are 0.72, 0.45, 0.34, and 0.33, respectively. The pressure compatibility and production compatibility coefficients exhibit rapid growth during the early stages, followed by a slight decrease during the middle and later stages. ⑤ The worst compatibility performances are observed during the early stage of CBM co-production, but these performances improve as the co-production time extends. ⑥ Optimizing superimposed pressure systems involves progressive co-production: dynamically introducing coal reservoirs, balancing reservoir pressure, minimizing fluid disturbance, and enhancing recovery efficiency. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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25 pages, 15668 KiB  
Article
Study on the Influence of Drilling Parameters on the Mechanical Properties and Pressure Relief Effect of Coal Rock
by Yujiang Zhang, Yexing Chen, Shuai Zhang, Guorui Feng, Yuguo Wang, Shule Li, Qian Wang, Bo Wang and Liang Zhao
Processes 2025, 13(4), 993; https://doi.org/10.3390/pr13040993 - 26 Mar 2025
Viewed by 287
Abstract
Based on considering the stress state distribution and potential failure surface of the specimen during uniaxial compression, the drilling parameters (layout, spacing, position) are set. Thoroughly understanding the influence of different drilling parameters on the pressure relief effect is conducive to reducing the [...] Read more.
Based on considering the stress state distribution and potential failure surface of the specimen during uniaxial compression, the drilling parameters (layout, spacing, position) are set. Thoroughly understanding the influence of different drilling parameters on the pressure relief effect is conducive to reducing the occurrence of coal mine rock burst accidents. Through laboratory tests and numerical simulation tests under different drilling parameters, the influence laws of mechanical parameters, failure characteristics, AE characteristic parameters and energy evolution of specimens under different drilling parameters were studied. The pressure relief effect under different drilling parameters was evaluated by using the pressure relief effect evaluation index (X), and the best combination of drilling parameters was obtained. The results show the following: (1) Compared with the intact specimen, the peak strength of the drilling specimen is significantly reduced, and the drilling layout has the greatest influence on the mechanical properties, followed by the drilling spacing and drilling position. (2) Different drilling layouts will form different weak-strength surfaces in the specimen, and lead the expansion and penetration of cracks, resulting in different failure modes of the specimen. The stress distribution inside the specimen will affect the stress concentration around the borehole, finally affect the damage degree of the specimen. (3) Drilling can not only effectively reduce the energy accumulation capacity, but also enhance the degree of energy dissipation. The AE ringing counts and energy of the triangular-drilling specimens are the least. The AE ringing counts and energy decrease first and then increase with the increase in drilling spacing, and are the smallest at three times the drilling diameter. The AE ringing counts and energy increase gradually with the upward movement of the drilling position. (4) The optimal combination of drilling parameters was obtained by the test, and it was triangular-layout drilling, drilling spacing three times the diameter, and the drilling position in the middle of the specimen, and the value of the pressure relief effect evaluation index (X) was 65.41. The research results can provide some reference for the selection and optimization of drilling pressure relief parameters in rock burst mines. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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18 pages, 7579 KiB  
Article
Molecular Simulation of Ultra-Microstructural Characteristics of Adsorption Pores in Terms of Coal and Gas Adsorption Properties
by Pan Chen, Yanping Wang, Yanxia Zhao, Qi Wang, Zhihui Wen and Ligang Tang
Processes 2025, 13(3), 771; https://doi.org/10.3390/pr13030771 - 7 Mar 2025
Viewed by 423
Abstract
To investigate the ultra-microstructural characteristics and adsorption properties of coal pores, the pore structure of Dongsheng lignite and Chengzhuang anthracite in Qinshui Basin was characterized by the liquid nitrogen adsorption method. It was found that the SSA of micropores constituted more than 65% [...] Read more.
To investigate the ultra-microstructural characteristics and adsorption properties of coal pores, the pore structure of Dongsheng lignite and Chengzhuang anthracite in Qinshui Basin was characterized by the liquid nitrogen adsorption method. It was found that the SSA of micropores constituted more than 65% of the total SSA in both coal samples. The macromolecular model of coal and the N2 molecular probe were used to obtain the ultrastructure parameters, and the gas adsorption behaviors of the two coals under different conditions were simulated by Grand Canonical Monte Carlo (GCMC) and Molecular Dynamics (MD). The results show that the pores of the lignite are mainly small pores, while the pores of the anthracite are mainly micropores. The specific surface area of the adsorption pores mainly constitutes micropores and ultra-micropores. The adsorption capacity of the CH4 of anthracite is consistently higher than that of lignite. The CH4 adsorption amount is positively correlated with the specific surface area and pore volume. This indicates that the gas adsorption capacity of coal is concentrated in micropores and ultra-micropores. The adsorption capacity increases with the increase in pressure and decreases with the increase in temperature. In the competitive adsorption of CH4/CO2/H2O, the adsorption quantity is in the order of H2O > CO2 > CH4. The research results provide a theoretical basis for coalbed methane exploitation and methane replacement. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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17 pages, 4169 KiB  
Article
Characterization of Damage and Infiltration Modeling of Coal-Slurry Consolidation Mechanics Under Loaded Conditions
by Yaocai Tang, Peng Lu, Junxiang Zhang and Wang Jian
Processes 2025, 13(2), 400; https://doi.org/10.3390/pr13020400 - 2 Feb 2025
Viewed by 849
Abstract
Coal seam gas drainage is a primary measure for mitigating coal and gas outburst hazards. Grouting sealing can form coal-slurry consolidated bodies, significantly improving the sealing quality of gas drainage boreholes and alleviating coal and gas outburst risks. Therefore, this study conducts triaxial [...] Read more.
Coal seam gas drainage is a primary measure for mitigating coal and gas outburst hazards. Grouting sealing can form coal-slurry consolidated bodies, significantly improving the sealing quality of gas drainage boreholes and alleviating coal and gas outburst risks. Therefore, this study conducts triaxial loading and seepage experiments to analyze the mechanical failure characteristics and permeability variation of coal-slurry consolidated bodies under loading conditions following grouting sealing of gas drainage boreholes. Based on the “cube” model, a permeability model for the damaged coal-slurry consolidated body under loading conditions is established. The findings provide guidance for evaluating the leakage prevention performance of sealing materials in field engineering and optimizing the sealing efficiency of grouting materials. Future research may explore the damage and seepage evolution of coal-slurry consolidated bodies under various loading conditions and sealing material types. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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22 pages, 12515 KiB  
Article
Stress Zoning Characteristics and Migration of Leaked Methane from Gas Wells Penetrating Protective Coal Pillars in Longwall Mining Areas
by Jinhang Shen, Shun Liang, Yisong Hao, Zhi Ma, Weisheng He, Xu Liang, Shaoyou Xu and Changheng Luo
Processes 2025, 13(1), 47; https://doi.org/10.3390/pr13010047 - 28 Dec 2024
Viewed by 841
Abstract
There are a large number of abandoned or casing-damaged oil/gas wells in the western mining areas of China. Under the influence of mining-induced stress, the methane leaked from the oil and gas wells will be transported through fracture within the coal pillar to [...] Read more.
There are a large number of abandoned or casing-damaged oil/gas wells in the western mining areas of China. Under the influence of mining-induced stress, the methane leaked from the oil and gas wells will be transported through fracture within the coal pillar to the longwall working face, which will seriously threaten the safe mining of coal resources. There is no mandatory standard for the practice of coal pillars in coal and gas wells in coal/gas overlapping areas, and the problems of oversized coal pillars and waste of coal resources have occurred during the implementation. In this study, through finite element numerical simulation, three different sizes of protective coal pillars are modeled in the background of Shuangma Coal Mine. The impacts of different heights and widths of protective coal pillars on the evolution of stresses and the diffusion process of leaked methane are explored, and the spatial and temporal migration law of leaked methane under multi-field coupling is revealed. The results show that under mining-induced stress, the size of the protective coal pillar has a significant effect on the stress distribution and methane transport law. Compared with the 130 m coal pillar, the peak stress of the 150 m coal pillar decreased by 6.7%, and the peak stress of the 180 m coal pillar decreased by 9%. At 150 m and 180 m widths, the permeability difference between the two sides is only 1 mD, and the diffusion ranges are similar. From the stress distribution and gas diffusion law, it is shown that the effect achieved by 150 m and 180 m coal pillars is similar. This work is of great significance for the reasonable remaining protective coal pillars for oil/gas wells penetrating longwall mining areas, as well as the prevention and control of disasters caused by leaked methane from wells. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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16 pages, 9732 KiB  
Article
Experimental Study on Spectral Response Characteristics and Mechanical State of Coal Based on Artificial Acoustic Signals
by Jianguo Zhang, Wenlong Fu, Weilong Cui, Ji Ma and Feng Du
Processes 2024, 12(12), 2752; https://doi.org/10.3390/pr12122752 - 4 Dec 2024
Viewed by 829
Abstract
With the increase in coal mining depth, the stress and strain state of coal and rock mass affects the formation of dangerous zones of dynamic phenomena. In order to study the relationship between the frequency spectrum characteristics of artificial acoustic signals and the [...] Read more.
With the increase in coal mining depth, the stress and strain state of coal and rock mass affects the formation of dangerous zones of dynamic phenomena. In order to study the relationship between the frequency spectrum characteristics of artificial acoustic signals and the stress state of coal and gas pressure, a test device and system that can generate acoustic signals by mechanical vibration excitation are developed by using the design idea of the unit module. Firstly, the basic mechanical parameters of coal under uniaxial compression are analyzed. On this basis, we use the test device to study the qualitative and quantitative relationships between the relative stress coefficient K value of the coal body and the axial loading stress, whether it contains gas, and the mechanical vibration force. The test results show that when the gas-containing coal and the gas-free coal are subjected to the same external mechanical vibration knocking force to stimulate the artificial acoustic signal test, the relative stress coefficient K value increases first and then decreases with the increase in axial loading stress. The relationship between the relative stress coefficient K and the axial loading stress σ can be expressed in the form of exponential function K=e−Cσ. When the axial loading stress and the external mechanical vibration force are both fixed values, the relative stress coefficient K value of the coal body with gas is smaller than that without gas. When the axial loading stress and gas-bearing pressure of the coal body are both fixed values, the relative stress coefficient K value decreases with the increase in the impact force of the external mechanical vibration. This experimental study can provide a reference for the identification and prediction of dynamic disasters based on artificial acoustic signals. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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21 pages, 6506 KiB  
Article
Performance and Reliability of Thermoelectric Conversion Using a Crooked Thermosyphon to Enhance Heat Transfer from Coal Fires
by Qingfeng Bao, Xiuting Guo, Bo Li, Wuyi Chen, Zhenping Wang and Yang Xiao
Processes 2024, 12(12), 2692; https://doi.org/10.3390/pr12122692 - 29 Nov 2024
Cited by 1 | Viewed by 785
Abstract
A large amount of energy can accumulate and be stored during underground coal fires. As thermal energy cannot be easily removed using the traditional technologies of fire prevention and extinguishment, there is a potential benefit to collecting and utilizing thermal energy from coal [...] Read more.
A large amount of energy can accumulate and be stored during underground coal fires. As thermal energy cannot be easily removed using the traditional technologies of fire prevention and extinguishment, there is a potential benefit to collecting and utilizing thermal energy from coal fires and converting it to electrical energy. Thus, this work proposes a thermoelectric generator as a solution to convert thermal energy from coal fires to electrical energy. To improve the thermal energy conversion efficiency, an experimental test system was established using a thermosyphon, an electric heating module, a cooling circulation module, a thermoelectric module, and a data acquisition module. Under the condition of ensuring the same input heat and cooling boundary conditions, the influence of three factors, namely the cooling method, the connection method, and the coverage rate of thermoelectric devices, on the performance of the coal fire waste heat conversion system was studied. The results show that, compared with air cooling, water cooling provides a greater temperature difference for the thermoelectric module, and the maximum temperature difference can reach 65.90 °C. Series connection between thermoelectric devices will generate a higher open-circuit voltage and output voltage. The maximum horizontal open-circuit voltage value can reach 3.34 V, and the maximum output voltage is 2.61 V. Compared with the coverage rates of thermoelectric devices of 15.0% and 30.0%, the output power under the coverage rate of 22.5% is the largest at 0.35 W, and its thermoelectric conversion efficiency is also the largest at 0.35%. The optimal combination of thermoelectric modules obtained from the research results can provide ideas for the application of in situ coal fire prevention and control. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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16 pages, 2411 KiB  
Article
Research on Gas Emission Prediction Based on KPCA-ICSA-SVR
by Li Liu, Linchao Dai, Xinyi Mao, Yutao Chen and Yongheng Jing
Processes 2024, 12(12), 2655; https://doi.org/10.3390/pr12122655 - 25 Nov 2024
Cited by 1 | Viewed by 622
Abstract
In the context of deep mining, the uncertainty of gas emission levels presents significant safety challenges for mines. This study proposes a gas emission prediction model based on Kernel Principal Component Analysis (KPCA), an Improved Crow Search Algorithm (ICSA) incorporating adaptive neighborhood search, [...] Read more.
In the context of deep mining, the uncertainty of gas emission levels presents significant safety challenges for mines. This study proposes a gas emission prediction model based on Kernel Principal Component Analysis (KPCA), an Improved Crow Search Algorithm (ICSA) incorporating adaptive neighborhood search, and Support Vector Regression (SVR). Initially, data preprocessing is conducted to ensure a clean and complete dataset. Subsequently, KPCA is applied to reduce dimensionality by extracting key nonlinear features from the gas emission influencing factors, thereby enhancing computational efficiency. The ICSA is then employed to optimize SVR hyperparameters, improving the model’s optimization capabilities and generalization performance, leading to the development of a robust KPCA-ICSA-SVR prediction model. The results indicate that the KPCA-ICSA-SVR model achieves the best performance, with RMSE values of 0.17898 and 0.3071 for the training and testing sets, respectively, demonstrating superior robustness and generalization capability. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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12 pages, 16346 KiB  
Article
Impact of Gas Accumulation on the Stability of Parallel Upward Ventilation in High-Temperature Sloped Shafts of Deep Wells
by Xiaoping Yuan, Qinghua Zhang and Zejun Wang
Processes 2024, 12(11), 2530; https://doi.org/10.3390/pr12112530 - 13 Nov 2024
Viewed by 785
Abstract
To explore the causes and influencing factors of wind flow oscillations in high-temperature inclined aisles of deep wells under parallel upward ventilation, this study conducts a comprehensive investigation using theoretical analysis and numerical simulations. Based on the kinetic analysis of gas flow, a [...] Read more.
To explore the causes and influencing factors of wind flow oscillations in high-temperature inclined aisles of deep wells under parallel upward ventilation, this study conducts a comprehensive investigation using theoretical analysis and numerical simulations. Based on the kinetic analysis of gas flow, a discriminant formula for wind flow reversal in the side branch is derived. Further analysis identifies initial wind speed and branch length as key factors influencing the reversal. Both gas pressure and thermal pressure contribute to wind flow reversal in the side branch, and the opposing directions of these pressures cause high-temperature gas to periodically flow between the two branches, resulting in wind flow oscillations. A higher initial wind speed can effectively reduce the oscillation amplitude due to increased initial kinetic energy and a larger pressure difference, but it does not extend the oscillation duration. Increasing the branch length can suppress wind flow oscillations by increasing airflow frictional resistance and damping. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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18 pages, 4669 KiB  
Article
Stress Zoning Characteristics of Goaf Side and Quantitative Evaluation of Surrounding Rock Stability
by Hongkai Zhang, Xiaofei Guo and Kunlin Yang
Processes 2024, 12(11), 2490; https://doi.org/10.3390/pr12112490 - 9 Nov 2024
Cited by 1 | Viewed by 820
Abstract
Aiming to maintain the stability of the mining roadway and the next working-face roadway in the goaf side of a coal mine, a systematic study was carried out, through theoretical analysis, numerical simulation, field case analysis, and other methods, of the synergistic change [...] Read more.
Aiming to maintain the stability of the mining roadway and the next working-face roadway in the goaf side of a coal mine, a systematic study was carried out, through theoretical analysis, numerical simulation, field case analysis, and other methods, of the synergistic change mechanism in the stress distribution and plastic zone development morphology of the roadway’s surrounding rock in the goaf side under mining disturbance. It was revealed that, under the influence of mining, the goaf side will form a high-deviatoric-stress environment, which directly affects the shape and stability of the plastic zone of the roadway’s surrounding rock. Based on the characteristics of the principal stress ratio and the morphological development law of the plastic zone of the surrounding rock, the side of the goaf is divided into four regions: unloading zone, high-deviatoric-stress zone, low-deviatoric-stress zone, and original-stress zone. And the corresponding mine pressure behavior zoning is proposed: fracture zone, butterfly failure zone, elliptical failure zone, and circular failure zone. A quantitative evaluation method for the stability of the roadway surrounding rock based on the plastic zone morphology criterion was established, and combined with the division of mine pressure, the stability of the surrounding rock on the side of the goaf was quantitatively evaluated. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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Review

Jump to: Research

17 pages, 2915 KiB  
Review
Recent Advances in Zero Discharge Treatment Technologies for Desulfurization Wastewater in Coal-Fired Power Plants: A Mini-Review
by Binsheng Liao, Xianyang Zeng, Zhongqian Ling, Sanmei Zhao, Bin Li and Xinlu Han
Processes 2025, 13(4), 982; https://doi.org/10.3390/pr13040982 - 26 Mar 2025
Viewed by 503
Abstract
Zero Liquid Discharge (ZLD) is a wastewater management strategy that eliminates liquid waste while maximizing water use efficiency. This article reviews the primary ZLD technologies used for desulfurization wastewater (DWW) treatment in coal-fired power plants. These technologies include the thermal process and the [...] Read more.
Zero Liquid Discharge (ZLD) is a wastewater management strategy that eliminates liquid waste while maximizing water use efficiency. This article reviews the primary ZLD technologies used for desulfurization wastewater (DWW) treatment in coal-fired power plants. These technologies include the thermal process and the membrane process. The thermal process includes “concentrated crystallization” technology and “gas evaporation and drying” technology. The paper also highlights recent advances in membrane technology for power plant wastewater treatment. The advantages and limitations of each technique are discussed. Membrane technology is considered a promising solution for wastewater recycling, while thermal technology offers easy operation and maintenance without the need for pretreatment. Finally, the paper outlines possible future directions for the treatment of DWW. Full article
(This article belongs to the Special Issue Advances in Coal Processing, Utilization, and Process Safety)
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