Special Issue “Advances in Coal Processing, Utilization, and Process Safety”

Safety in production has always been the top priority in the coal industry. Although renewable energy is growing rapidly, coal resources still occupy an important place in the energy mix of many countries [1]. In recent years, as coal mining has continued to extend into deeper formations, mining conditions have become extremely harsh under the complex deep geological environment characterized by “three highs and one low”. The risk of dynamic coal-rock disasters has increased significantly, making it particularly important to ensure the safe extraction of coal [2,3,4]. Meanwhile, the subsequent processing and utilization of coal are equally important. This concerns not only the efficient conversion and clean use of coal resources, but also serves as an important support for ensuring the safe and sustainable operation of the entire energy industry chain [5].

In response to the needs for safety, efficiency, and green development in the process of coal development and utilization, scholars at home and abroad have carried out extensive research in recent years on mineral processing and the efficient utilization of resources, process safety control, and mine disaster prevention and control. Relevant studies focus not only on new technologies for mineral processing and pathways to improve efficiency [6,7,8], but also on issues such as dust explosions [9,10,11], spontaneous coal combustion [12,13], and safety in coal-related processes [14].

Meanwhile, in the field of mine safety engineering and disaster prevention, research on the mechanisms of coal-rock and gas dynamic disasters [15,16]—as well as coalbed methane migration [17]—has shown a development trend toward multi-scale and multi-method interdisciplinary integration. In particular, with the continuous advancement of intelligent prediction and early-warning technologies [18,19] as well as numerical simulation [20], research on risk identification, mechanism analysis, and prevention-and-control optimization throughout the entire process of coal processing, mining, gas drainage, and utilization is being continuously deepened, providing important theoretical foundations and technical support for achieving the safe extraction of coal resources, their clean utilization, and the coordinated development of the industrial chain.

The Special Issue “Advances in Coal Processing, Utilization, and Process Safety” in the journal Processes brought together research papers presented at the forum on safe coal mining, mine disaster prevention and control, and coal utilization. Its content covers topics such as mine pressure and surrounding rock control, coalbed methane migration, and the monitoring and early warning of dynamic disasters in coal mines. Many of the studies are interdisciplinary in nature, but their overarching theme is coal mine production safety.

In the area of mine pressure and surrounding rock control, different scholars have revealed the evolution patterns of disasters and the corresponding control mechanisms under deep mining conditions from various engineering perspectives. Liu [21] conducted triaxial permeability tests on three types of coal-rock samples by combining physical simulation with FLAC3D numerical simulation, revealing the coupled evolution mechanism of the stress–fracture–seepage field in the overburden, and providing a basis for the identification and prevention of water inrush risks. Li [22] used PFC2D to analyze the effects of floor stiffness, strength, and joint distribution on the heave mechanism during mining, providing a theoretical basis for the optimal groove-cutting design. Liu [23] used PFC2D to investigate the corresponding evolution of overburden fractures during continuous multi-seam mining, providing a basis for determining the optimal location for roadway construction in coal seams. Shi [24] theoretical analysis and FLAC3D numerical simulation combined with field conditions, proposed a method to address the hazards caused by roof hanging. Wang [25] used FLAC3D to simulate the stress field distribution during coal seam extraction under folded geological conditions and proposed a coordinated control strategy to ensure the stability of the surrounding rock. Zhang [26] systematically studied the coordinated variation mechanism of the stress distribution and plastic zone morphology of the surrounding rock in a roadway on one side of a goaf under mining disturbance by comprehensively applying theoretical analysis, numerical simulation, and case studies. A quantitative evaluation method for assessing the stability of roadway surrounding rock was established. Zhang [27] investigated the mechanical parameters, failure characteristics, acoustic emission characteristic parameters, and energy evolution of specimens through laboratory tests and numerical simulations under different drilling parameters, providing a useful reference for the selection and optimization of pressure-relief drilling parameters in rock burst mines.

In terms of coalbed methane migration, Cheng [28] developed a permeability evolution model and a long short-term memory (LSTM) prediction model, formulated a dynamic regulation strategy for intelligent gas drainage, and carried out related applications. To address the unique CBM reservoir problems associated with superimposed pressure systems, Ren [29] independently developed an experimental apparatus for the joint production of CBM under multiple pressure systems. Chen [30] characterized the pore structures of lignite and anthracite using the liquid nitrogen adsorption method, and investigated the ultramicroscopic structural characteristics and adsorption properties of coal pores. In addition, Zhang [31] investigated the deformation behavior and pore-structure characteristics of lignite from room temperature to 650 °C through high-temperature triaxial experiments, nuclear magnetic resonance, and X-ray computed tomography, providing a theoretical basis for coalbed methane extraction and displacement. Tang [32] conducted triaxial loading and seepage tests to analyze the mechanical failure characteristics and permeability variation in coal–grout consolidation bodies under loading after grouting-based borehole sealing, providing guidance for evaluating the leakage-prevention performance of sealing materials and optimizing the borehole-sealing effectiveness of grouting materials in field engineering. Shen [33] used FLAC3D numerical simulation to investigate the effects of three protective coal-pillar heights and widths on stress evolution and the diffusion process of leaked methane, revealing the spatiotemporal migration patterns of leaked methane under multi-field coupling. In addition, displacement technology plays a key role in improving the extraction efficiency of coalbed methane (CBM) and mine gas. Yang [34] systematically reviewed advances in physical field modeling, such as flow and diffusion, with a particular focus on the evolution of multiphysics coupling mechanisms and permeability models.

In the field of monitoring and early warning for dynamic disasters in coal mines, Zhang [35] investigated the relationship between the spectral characteristics of artificial acoustic signals and gas pressure as well as stress state. Based on a modular design concept, a testing device and system capable of generating acoustic signals through mechanically induced vibrations was developed, which can provide a reference for disaster identification and prediction based on artificial acoustic signals. Liu [36] conducted an in-depth analysis of data cleaning, feature extraction, and model optimization in gas emission prediction, and proposed a high-accuracy prediction model based on KPCA-ICSA-SVR, providing important technical support for mine gas management. Wang [37] successfully synthesized La_0.7Gd_0.3Fe_0.9Co_0.1O₃ (S-2) perovskite microspheres via an efficient ultrasound-assisted hydrothermal method, demonstrating strong potential for use as a high-performance low-temperature methane sensor.

In terms of coal utilization and its environmental governance, Bao [38] proposed the use of a thermoelectric power generation device to convert the heat energy produced by coal fires into electrical energy, and established an experimental testing system for evaluation. Coal is an important energy source in industrial processes and is commonly used in power plant boilers. Flue gas desulfurization is essential for reducing pollutant emissions, but the desulfurization process generates a large amount of desulfurization wastewater that pollutes the environment. Liao [39] reviewed the main zero-liquid-discharge technologies used for treating desulfurization wastewater (DWW) in coal-fired power plants, providing ideas for technological improvement.

In other aspects of coal mine safety, He [40] used theoretical derivation and PyroSim numerical simulation to analyze tunnel fire spread under different wind-speed conditions, and established the relationship between wind speed and water-mist spray trajectory, providing theoretical support for the study of tunnel fire patterns and emergency response measures. Yuan [41] analyzed the causes of airflow oscillation under parallel upward ventilation and its influencing factors through theoretical analysis and COMSOL Multiphysics 5.5 numerical simulation, and found that the initial airflow velocity and branch length were the key factors affecting flow reversal. Rybár R [42] analyzed the representation of geological, mining, processing, and environmental processes in Minecraft, and conducted a methodological comparison between the mechanisms within the platform and real-world technological and geoscientific processes, evaluating the accuracy, degree of simplification, and educational applicability of various processes related to the extraction and use of mineral resources.

The above studies address many issues in coal mine safety from multiple perspectives. In the face of the many challenges confronting safe coal production, processing, and utilization, there remain many areas worthy of further exploration and in-depth discussion. The journal will continue to solicit high-quality submissions in these fields.

We would like to thank all contributors and editors for their enthusiastic support of this Special Issue, and we also appreciate the efforts of the editorial team of Processes.