Search Results (245)

Given that the stock of coal gangue is increasing annually, and especially considering the problem of resource utilization after the spontaneous combustion of coal gangue accumulations with large thickness, the post-spontaneous combustion of coal gangue (SC coal gangue) from Yangquan, Shanxi, was selected as a research object. After crushing and screening, SC coal gangue was used as a coarse and fine aggregate, and through concrete mix design and a trial mix of concrete and mix ratio adjustment, concrete of strength grade C20 was obtained. Through experiments, the strength, elastic modulus, frost resistance, carbonation depth and other performance indicators of the concrete were measured. Using the SC coal gangue concrete, a 20 mm thick SC coal gangue panel was designed and manufactured. Through experimental tests, the bearing capacity, hanging force, impact resistance, impermeability and other properties of the board met the requirements of the relevant standards for building wallboard. For the SC coal gangue panel composite rock wool, its heat transfer coefficient decreased by 34.0%, air sound insulation was $\ge 45 \mathrm{d}\mathrm{B}$, and the self-weight of the external wallboard was reduced by 37.5%, so the related performance was better than the requirements of the current standard. The research results have been successfully applied to an office building project in Shanxi, China. Using SC coal gangue to make the external wallboard of the building, the reduction and recycling of solid waste are realized. In addition, the production of wall panels has been industrialized, thereby improving the construction efficiency. Full article

Mine fire is caused by external heat source or coal seam spontaneous combustion, and there are serious hidden dangers in mining operation. The existing detection methods have high cost, limited coverage and delayed response. An edge intelligent fire detection system based on multi-source information fusion is proposed. We enhance the YOLOv5s backbone network by (1) optimized small-target detection and (2) adaptive attention mechanism to improve recognition accuracy. In order to overcome the limitation of video only, a dynamic weighting algorithm combining video and multi-sensor data is proposed, which adjusts the strategy according to the real-time fire risk index. Deploying quantitative models on edge devices can improve underground intelligence and response speed. The experimental results show that the improved YOLOv5s is 7.2% higher than the baseline, the detection accuracy of the edge system in the simulated environment is 8.28% higher, and the detection speed is 26% higher than that of cloud computing. Full article

Grey cast iron with spheroidal graphite has been known and widely used since the 20th century (since 1947). Numerous methods have been developed for the secondary metallurgy process to produce nodular graphite. Spontaneous crystallization of nodular graphite is known in foundry practice and other fields. Examples of cast iron with spheroidal graphite include pure alloys with low sulfur content and natural samples containing nodular graphite, formed by natural forces (meteorites and combustion ash). This article presents the results of two industrial experiments that led to the formation of nodular graphite precipitates without the addition of elements that promote spheroidization. Studies were carried out on high-silicon cast iron intended for corrosion-resistant castings. TDA, chemical composition analysis, light and scanning microscopy, EDS, X-ray spectroscopy, and digital image analysis were used to identify the nodular precipitates. The analyses confirmed the presence of nodular graphite precipitates, and known growth mechanisms were assigned to them. It is likely that deoxidation of the metal bath during the metallurgical process contributed to the spontaneous crystallization of graphite spheroids. Full article

Air pollution issues are relevant all over the world, especially in industrial areas. The main pollution of the atmosphere is caused by dust emissions from industry. This article discusses the issue of dust emission from the coal industry. The purpose of this research is a comprehensive analysis and environmental assessment of the impact of coal storage processes on the environment. The study was conducted on the example of a coal deposit in the Karaganda region of the Republic of Kazakhstan. The Karaganda region is the industrial base of Kazakhstan, and is characterized more by coal industry facilities. In addition to the impact during the mining period, coal storage is also a serious problem. The problem of storing energy coals on a large scale of their extraction and consumption has a huge impact on the environment, but it is of great economic importance for the region. In this paper, practical methods of combating weathering are considered using the example of coal: small fraction—0–50 mm; large fraction—50–300 mm; oversized—more than 300 mm. Calculations of the formation of emissions, the maximum surface concentrations of pollutants from coal depots were carried out, and plots of their dispersion were constructed. When plotting the dispersion of pollutants, it was revealed that the largest concentration of substances falls on the territory of the coal deposit. According to the data obtained, a directly proportional dependence of the amount of emissions on the volume of incoming coal and the area of the base of the coal stacks is obvious; the temperature fluctuation in the stacks during the research is in the range from 21.9 to 26.1 °C. Scientifically researched anti-emission cover (AEC) on coal stacks. AEC has advantages for a specific climate (frequent winds, dryness): preservation of properties up to 90% over their service life; resistant to environmental aggressiveness and mechanical influences. This method solves two tasks: the first task is to prevent spontaneous combustion of coal stacks, and the second task is to reduce dust emissions from coal stacks. Measures have been developed to minimize the negative impact of coal stacks on the environment. Full article

To investigate the effect of oxygen concentration on the activation energy of coal oxidation, low-temperature oxidation experiments were carried out on coal samples under controlled oxygen levels (21%, 12%, 10%, 7%, 5%, and 3%) using a programmed-temperature apparatus. The oxygen consumption rates and gas production were measured in relation to temperature, and critical temperatures were identified for each condition, enabling the division of the oxidation process into two distinct stages. Kinetic analyses were conducted for each stage based on the Arrhenius equation derived from the oxygen consumption rate. The apparent activation energy was determined from the slope of the linearized Arrhenius plot. The results demonstrate a strong dependence of activation energy on oxygen concentration, with values increasing from 12.98 kJ·mol⁻¹ at 21% O₂ to 25.11 kJ·mol⁻¹ at 3% O₂. A marked difference in activation energy was observed across the critical temperature—for instance, under 21% O₂, activation energies were 12.98 kJ·mol⁻¹ below and 41.72 kJ·mol⁻¹ above the critical point. Furthermore, a safety threshold of 6% O₂ was identified for goaf atmospheres, providing critical guidance for the prevention of coal spontaneous combustion. Full article

Abnormal CO gas concentration is one of the common problems in coal mine safety production. In view of the phenomenon of CO overrun in the working face, this paper takes the fully mechanized discharge working face of Zhaoxian Mine as the research object, analyzes the occurrence of primary coal seam gas through the coal sample tank analysis experiment and the indoor crushing experiment, and explores the source of CO in the fully mechanized working face. According to the calculation model, the predicted value of CO concentration at the return air corner of the working face was calculated and, combined with the gas data of the working face monitored on site, it was proven that the CO concentration of the working face was in the normal range. This study found that the oxidation of residual coal in the goaf and the generation of CO during the mining process were the main reasons for the high CO concentration in the working face, rather than the occurrence of raw coal. This study reduces the interference of CO concentration on the determination of coal spontaneous combustion, prevents the misjudgment of coal spontaneous combustion, ensures the safe production of the Zhaoxian Coal Mine, provides data and theoretical support for the subsequent establishment of the CO prevention and control system of the working face, and provides a solution and technical reference for the CO overrun phenomenon in the working face of other high-gas mines. Full article

Coal gangue, a primary solid waste by-product of coal mining and processing, constitutes approximately 10–15% of total coal output. Its accumulation poses substantial environmental challenges, including land occupation, spontaneous combustion, acid mine drainage, and heavy metal leaching. Despite its high silica and alumina content (typically exceeding 70% combined), the highly stable and crystalline structure of raw coal gangue limits its pozzolanic activity and adsorption efficiency. To address this limitation, this review emphasizes recent advances in activation strategies such as thermal (500–900 °C), mechanical (dry/wet grinding to less than 200 µm), chemical (acid/alkali treatments), microwave, and hybrid methods. The activated coal gangue resulted in an enhanced surface area (up to 55 m²/g), amorphization of kaolinite to metakaolinite, and the generation of mesoporosity under optimal conditions. This review critically examined the geotechnical applications, such as soil stabilization and mine backfill, highlighting the replacement of 50–75% of cementitious binder in backfilling and meeting the subgrade/base material strength criteria (UCS > 2 MPa). In geoenvironmental applications (adsorption of phosphate, dyes, heavy metals, and CO₂ mineralization), more than 90% of pollutant removal is attained. In construction applications, supplementary cementitious materials and sintered bricks are examined. Several critical knowledge gaps, including limited understanding of long-term durability, inconsistent activation optimization across different coal gangue sources, and insufficient assessment of environmental impacts during large-scale implementation, are clearly addressed. This review provides a roadmap for advancing sustainable coal gangue utilization and highlights emerging opportunities for cost-effective applications in the mining and construction sectors. Full article

With the development of the mining industry, safety issues in underground operations are becoming increasingly relevant. Complex gas conditions in mines, including the presence of explosive and toxic gases, pose a serious threat to the lives of miners and the stability of production processes. This paper describes the development and modeling of an integrated fire monitoring and automatic extinguishing system that combines gas collection, concentration analysis, and rapid response to emergencies. The main components of the system include the following: a gas collection module that uses an array of highly sensitive sensors to continuously measure the concentrations of methane (CH₄), carbon monoxide (CO), and hydrogen sulfide (H₂S) with an accuracy of up to 95%; a gas analysis module that uses data processing algorithms to identify gas concentration threshold exceedances (e.g., CH₄ > 5% vol. or CO > 20 ppm); and an automatic fire extinguishing module that activates nitrogen supply, ventilation, and aerosol/powder fire extinguishers when a threat is detected. Simulation results in MATLAB/Simulink showed that the system reduces the concentration of hazardous gases by 30% within the first 2 s after activation, which significantly increases safety. Additionally, scenarios with various types of fires were analyzed, confirming the effectiveness of the extinguishing modules in mines up to 500 m deep. The integrated system achieves 95% gas detection accuracy, 90 ms response latency, and 40% hazard reduction within 3 s of activation, verified in 500 m deep mine simulations. Quantitative comparison shows a 75% faster response time and 10% higher detection accuracy than conventional systems. The proposed system demonstrates high reliability in difficult conditions, reducing the risk of fires by 75% compared to traditional methods. This work opens up prospects for practical application in the coal industry, especially in regions with a high risk of spontaneous coal combustion, such as India and Germany. Full article

The spontaneous combustion of sulfide ores (SOSC) is an extremely dangerous mining disaster that directly threatens safety production in mines and causes far-reaching negative impacts on the surrounding ecosystem. In this study, oxidation weight gain experiments, self-heating temperature and ignition temperature tests, and thermogravimetric analysis (TGA) were conducted to detect the spontaneous combustion characteristics of sulfide ores with different sulfur contents (40.29%, 34.56%, 24.81%, and 14.2%). The results show that the sulfur content significantly affects the spontaneous combustion characteristics of sulfide ores. As the sulfur content decreased, the oxidized weight gain rate decreased overall, and the self-heating temperature (135, 152.5, 162.5, and 176.9 °C) and ignition temperature (425.3, 438.6, 455.4, and >500 °C) increased. The three combustion stages of the SOSC were divided based on the TG and DTG curves: low-temperature oxidation stage, combustion decomposition stage, and slow burnout stage. Furthermore, KAS and FWO methods were used to obtain the apparent activation energy in the combustion decomposition stage. The apparent activation energy decreased significantly with the increase in the sulfur content. The results of all experiments and analyses showed that sulfide ores with high sulfur content have a stronger tendency to undergo spontaneous combustion. The research results have important theoretical and practical implications for the prevention of SOSC. Full article

Spontaneous human combustion, today scientifically discredited, was considered a legitimate medical entity in Europe beginning in the 17th century. The aim of this study is to analyze Spanish medical conceptions about this phenomenon between the 18th and 19th centuries, starting from the world context. Primary sources were used with a deductive–inductive approach. Beyond providing an account of a discarded medical theory, this work explores how certain categories of knowledge persist, disappear, and resurface under different belief systems. We analyze how the Spanish medical discourse on SHC evolved in three stages: exposure, debate, and rejection. This allows us to observe changes in medical mentality regarding factors such as searching for sources of ignition and moderating alcohol consumption as a preventive health measure. This study and its historiographical approach enable us to explore broader issues relating to ignorance, alternative ideas, the stability of scientific knowledge over time, and shifts in the field of legal and forensic medicine. This research provides a model for analyzing the complex dynamics of knowledge and its evolution at the intersection of science, culture, and power. Full article

Coal serves as the primary energy source for China, with production anticipated to reach 4.76 billion tons in 2024. However, the mining process generates a significant amount of gangue, with approximately 800 million tons produced in 2023 alone. Currently, China faces substantial gangue stockpiles, characterized by a low comprehensive utilization rate that fails to meet the country’s ecological and environmental protection requirements. The environmental challenges posed by the treatment and disposal of gangue are becoming increasingly severe. This review employs bibliometric analysis and theoretical perspectives to examine the latest advancements in gangue utilization, specifically focusing on the application of computational chemistry to elucidate the structural features and interaction mechanisms of coal gangue, and to collate how these insights have been leveraged in the literature to inform its potential utilization routes. The aim is to promote the effective resource utilization of this material, and key topics discussed include evaluating the risks of spontaneous combustion associated with gangue, understanding the mechanisms governing heavy metal migration, and modifying coal byproducts to enhance both economic viability and environmental sustainability. The case studies presented in this article offer valuable insights into the gangue conversion process, contributing to the development of more efficient and eco-friendly methods. By proposing a theoretical framework, this review will support ongoing initiatives aimed at the sustainable management and utilization of coal gangue, emphasizing the critical need for continued research and development in this vital area. This review uniquely combines bibliometric analysis with computational chemistry to identify new trends and gaps in coal waste utilization, providing a roadmap for future research. Full article

Internal combustion engine vehicles damage the environment and public health by emitting toxic fumes, such as CO₂ or CO and other trace compounds. The use of electric cars helps to reduce the emission of pollutants into the environment due to the use of batteries with no direct and local emissions. However, accidents of battery electric vehicles pose new challenges, such as thermal runaway. Such accidents can be serious and, in some cases, may result in uncontrolled overheating that causes the battery pack to spontaneously ignite. In particular, the most dangerous vehicles are heavy goods vehicles (HGVs), as they release a large amount of energy that generate high temperatures, poor visibility, and respiratory damage. This study aims to determine the potential consequences of large BEV fires in road tunnels using computational fluid dynamics (CFD). Furthermore, a comparison between a BEV and an ICEV fire shows the differences related to the thermal and the toxic impact. Furthermore, the adoption of a longitudinal ventilation system in the tunnel helped to mitigate the BEV fire risk, keeping a safer environment for tunnel users and rescue services through adequate smoke control. Full article

Taking a composite goaf in goaf-side entry retaining as our research focus, a kilogram-level spontaneous combustion experiment was carried out, and limit parameters for coal spontaneous combustion characteristics were assessed. Combined with the key parameters of the site, a numerical model of a multi-area composite goaf was constructed, and the distribution features of the dangerous area for coal spontaneous combustion in the lower layer of in goaf-side entry retaining were determined by means of the upper and lower layer composite superposition division method. The results show that at a floating coal thickness in the goaf of 1.9 m, the lower limit of oxygen concentration C_min, upper limit of air leakage intensity, and corresponding seepage velocity are 6%, 0.282 cm⁻³·s⁻¹·cm⁻², and 11.28 × 10⁻³ m/s respectively. The dangerous area regarding residual coal on the intake side is 23~38 m away from the working face, while that on the return air side is concentrated amid the goaf at 23~75 m, and that on the flexible formwork wall is concentrated at 0~121 m. The research results are of crucial practical importance for the prevention and control of coal spontaneous combustion within a composite goaf. Full article

The spontaneous combustion disaster of coal not only causes a waste of resources but also affects the safe production of coal mines. In order to accurately detect the range and location of the spontaneous combustion source of coal, this paper studies and summarizes previous research results, and based on the principles and research and development progress of existing detection technologies such as the surface temperature measurement method, ground temperature measurement method, wellbore temperature measurement method, and infrared remote sensing detection method, it briefly reviews the application of various detection technologies in engineering practice at this stage and briefly explains the advantages and disadvantages of each application. Research shows that the existing technologies are generally limited by the interference of complex environmental conditions (such as temperature measurement deviations caused by atmospheric turbulence and the influence of rock layer structure on ground temperature conduction) and the implementation difficulties of geophysical methods in mining applications (such as the interference of stray currents in the ground by electromagnetic methods and the fast attenuation speed of waves detected by geological radar methods), resulting in the insufficient accuracy of fire source location and difficulties in identifying concealed fire sources. In response to the above bottlenecks, the ”air–ground integrated” fire source location determination technology that breaks through environmental constraints and the location determination method of a CSC fire source based on a multi-physics coupling mechanism are proposed. By significantly weakening the deficiency in obtaining parameters through a single detection method, a new direction is provided for the detection of coal spontaneous combustion fire sources in the future. Full article

Electric bicycles in elevators pose serious safety hazards. Fires in the confined space make escape difficult, and recent accidents involving e-bike fires have caused casualties and property damage. To prevent e-bikes from entering elevators and improve public safety, this design employs the Nezha development board as the upper computer for visual detection. It uses deep learning algorithms to recognize hazards like e-bikes. The lower computer orchestrates elevator controls, including voice alarms, door locking, and emergency halt. The system comprises two parts: the upper computer uses the YOLOv11 model for target detection, trained on a custom e-bike image dataset. The lower computer features an elevator control circuit for coordination. The workflow covers target detection algorithm application, dataset creation, and system validation. The experiments show that the YOLOv11 demonstrates superior e-bike detection performance, achieving 96.0% detection accuracy and 92.61% mAP@0.5, outperforming YOLOv3 by 6.77% and YOLOv8 by 15.91% in mAP, significantly outperforming YOLOv3 and YOLOv8. The system accurately identifies e-bikes and triggers safety measures with good practical effectiveness, substantially enhancing elevator safety. Full article