Safety Of Mining Operations Research Articles

Optimization of Filling Material Ratio in Yellow Phosphorus Slag Mine.

Yellow phosphorus slag has been considered as a potential cement substitute for mine filling material due to its cementing activity; however, its slow setting and low early strength have limited broader use. This study investigates the grading, compactness, and strength of yellow phosphorus slag combined with tailing sand. Using yellow phosphorus slag as an aggregate, cement as a binder, and mixing tailing sand in different ratios, this study evaluates its feasibility as a coarse aggregate in mine backfill. The key findings are as follows. (1) The grading index of tailing sand was 0.5, aligning with Fuller grading, but it required mixing with coarse aggregates to enhance strength and reduce cement consumption. Yellow phosphorus slag, with a grading index of 0.97, does not match Fuller's curve and thus benefits from mixing with tailing sand. (2) For mixtures of waste rock and tailings, the 5:5 ratio aligned closely with Fuller's theory, showing optimal packing density and strength. Mixtures of yellow phosphorus slag and tailings at ratios of 3:7, 4:6, and 5:5 had R2 values of 0.73, 0.80, and 0.85, respectively, confirming reliable fit. The 5:5 mixture provided the best packing density and strength. (3) A new strength prediction model, accounting for aggregate, cement, and water effects, suggests that a 5:5 ratio with a 71% mass concentration and 1/7 ash-sand ratio meets industrial strength requirements. FLAC3D simulations indicated that cemented backfill reduces stress concentrations caused by excavation and supports stability during mining while also absorbing energy through compaction, creating favorable conditions for safe mining operations.

Innovative computational model for optimal deep coal mining under large-scale crustal stress conditions

Understanding and controlling the ground stress in deep coalfield mining is crucial for ensuring mine safety and efficiency. This study aims to address two unresolved scientific issues in ground stress research: the selection of optimal excavation plans and the large-scale rapid acquisition of ground stress data. A novel computational model is proposed for key rock layer control under different crustal stress conditions. The model considers the complexity and uncertainty of ground stress distribution by simplifying the key rock strata into a fixed-fixed beam model and calculating their safety through mechanical methods. Introducing an innovative approach for acquiring large-scale stress fields using GPS data. By inverting large-scale strain fields in the coalfield area, combined with World Stress Map (WSM) and measured data, accurate stress fields are obtained. The proposed optimal excavation plan can be applied to various coalfield locations worldwide, providing a scientific basis for safe and efficient mining operations. Additionally, the innovative use of GPS data in obtaining large-scale stress fields offers a valuable tool for assessing ground stress variation.

Geological characteristics of coal mines in the Zagros basin of Iran: Unveiling rock mechanical properties and time-dependent behavior

The Zagros Basin in southwestern Iran is a significant source of coal, with numerous coal mines operating in the region. Ensuring the stability of coal mines is crucial for safe and efficient mining operations. This study investigates the time-varying response of rocks and roof resistance in coal mines in the Zagros Mountains using a novel approach that combines numerical simulation, relaxation testing, and rock displacement studies. The results show that rocks exhibit significant time-dependent behavior, with changes in rock mechanical properties over time. A comprehensive viscoelastic-plastic model is developed to accurately describe the time-varying strain-softening response of rocks and simulate laboratory tests. The model integrates the Burgers and strain-softening models, simulating stress relaxation curves and rock displacement over time. The study reveals that the rock mass displays significant nonlinear behavior, with changes in rock mechanical properties over time. The findings of this study highlight the importance of considering the time-varying response of rocks and roof resistance in coal mine stability analysis. The results provide valuable insights into the time-dependent behavior of rock mass in coal mines in Iran, which can inform mining practices and mitigate potential hazards. Results in this study can contribute to developing strategies for improving roof stability and reducing the likelihood of roof collapses.

Integrating geodetic infrastructures for GNSS displacements analysis in Chile: A case study with REDGEOMIN (2019–2022)

This article investigates crustal displacements in Chile between 2019 and 2022, a region marked by the interaction between three Plates. Utilizing the Red Geodésica para la Minería (Geodetic Network for Mining, REDGEOMIN), which incorporates GNSS stations within Chile and fiduciary stations from the International GNSS Service (IGS) and the Sistema de Referencia Geodésico para las Américas (Geodetic Reference System for the Americas, SIRGAS) outside the country, our solutions are aligned with the International Terrestrial Reference Frame (ITRF). This approach ensures our research has significant local relevance and contributes to the global scientific community. This work thoroughly analyses GNSS geodetic infrastructure and covers equipment specifications, post-processing data availability, and quality control measures. REDGEOMIN's methodology aligns with IGb14 and the SIRGAS-Continuously Operating Network (SIRGAS-CON), ensuring precision and reliability. The primary objective of this research is to identify regions with significant displacement and areas requiring densification to improve vector variation. The study achieved high precision in aligning station coordinates to the IGb14 frame, with deviations of less than 1 mm, and to SIRGAS-CON, with deviations of 1 mm in planimetry and 2 mm in altimetry. The temporal evolution from 2019 to 2022, analyzed through the Analysis Deformation Beyond Los Andes (ADELA) project, reveals 3–5 cm/year displacements during interseismic periods, with contrasting directions in the northern and south-central regions. Metric displacements during co-seismic periods underscore the compelling necessity for kinematic reference frames in Chile and the incorporation of co-seismic displacement into scientific processing software. Therefore, this study ultimately emphasizes the need to establish a robust geodetic infrastructure in Chile, aiming for a comprehensive characterization and monitoring of the existing geodynamic processes in this region. These results, with their significant practical applications for future geodetic research and mining in Chile and internationally, enhance the precision and safety of mining operations in seismic zones, thereby demonstrating the relevance and applicability of the findings.

Research on the evolution law and control technology of deviatoric stress in the surrounding rock of gob-side entry retaining

Gob-side entry retaining (GER) play a crucial role in enhancing coal recovery, improving roadway stress conditions, and ensuring safe and efficient mining operations. This study focuses on investigating the stability characteristics of surrounding rock using flexible formwork concrete (FFC) along the headgate of 3405 panel. According to the fracture pattern of roof, a mechanical model of GER was developed. This study derived expressions for the support resistance of the filling body and determined its optimal bearing capacity. A FLAC3D numerical model was employed to simulate the GER process, segmented into early, middle, and late stages. Simulation results demonstrate a progression in peak deviatoric stress and extent of plastic zones in the surrounding rock. This evolution includes an initial minor increase (early stage), followed by rapid escalation (middle stage), and eventual stabilization (late stage). The middle stage emerges as critical, characterized by pronounced mining-induced stress effects on the roof. During this phase, significant changes are observed in deviatoric stress curves, with plastic zones rapidly migrating deeper into the rock mass. Practical implementation of the findings revealed a maximum deformation of the filling body of only 198 mm, affirming the feasibility of employing FFC in GER. This research provides valuable insights into managing stability concerns in GER thereby enhancing safety and operational efficiency in coal mining under similar conditions.

Қазба айналасындағы тау массивінің жағдайын ескере отырып, контурға жақын топырақ жыныстарын бекіту

The maintenance of excavation workings will also require significant repair costs both before and after they are put into operation, especially in the zone of influence of stoping operations. Maintaining and increasing the volume of underground coal mining is possible only if there is a highly efficient technology for conducting and maintaining development workings. The purpose of the research was to evaluate the stability control parameters of the contours of mine workings, fixed with anchor bolting, in order to create a technology for intensive and safe excavation of excavation workings based on the identified patterns of behavior of adjacent rock masses. The idea of the approach is to use the technogenic stress-strain state to develop an effective technology for fastening the near-contour rock mass. The mechanism of deformation, displacement and collapse of rocks in a structurally disturbed heterogeneous rock mass was studied to assess the state of the rock mass around mine workings. A technology for fastening near-contour soil rocks has been developed, taking into account the state of the rock mass around the working, and the parameters for the operation of rock bolts in mines for fixing rods in workings in order to ensure the safety of mining operations in the mines of the Karaganda coal basin have been determined.

Prediction of Floor Failure Depth Based on Dividing Deep and Shallow Mining for Risk Assessment of Mine Water Inrush

Understanding and predicting floor failure depth is crucial for both mitigating mine water inrush hazards and safeguarding groundwater resources. Mining activities can significantly disturb the geological strata, leading to shifts and damage that may result in floor cracks. These disruptions can extend to confined aquifers, thereby increasing the risk of water inrushes. Such events not only pose a threat to the safety of mining operations but also jeopardize the sustainability of surrounding groundwater systems. Therefore, accurately predicting floor failure depth to take effective coal seam floor management measures is the key to reducing the impact of coal seam mining on water resources. Seventy-eight sets of data on coal seam floor failure depth in China were collected, and the main controlling factors were considered: mining depth (D1), working face inclination length (D2), coal seam inclination (D3), and mining thickness (D4). Firstly, the distance evaluation function based on Euclidean distance was constructed as the clustering effectiveness index, and the optimal cluster number K = 3 was determined. The collected data were clustered into three categories using the K-means clustering algorithm. It was found that the clustering results were positively correlated with the size of D1, indicating that D1 played a dominant role in the clustering. The D1 dividing points of the three types of samples were between 407.7~414.9 m and 750~900 m. On this basis, the grey correlation analysis method was used to analyze the order of the influence weights of the main controlling factors of coal seam floor failure depth. For the first group, the order was D2 > D1 > D3 > D4, while, in the other two, it was D1 > D2 > D3 > D4. D1 emerged as the most influential factor, surpassing D2. Therefore, D1 between 407.7 and 414.9 m could be used as the boundary, the first group could be classified as shallow mining, and the second and third groups could be classified as deep mining. Based on this boundary, CatBoost prediction models for the depth of coal seam floor failure in deep and shallow parts were constructed and the prediction results of the model test set were compared with the calculation results of the empirical formula. These models exhibited superior accuracy with a lower mean squared error (MSE) and mean absolute error (MAE) and a higher R-squared (R2) compared to the empirical formula. This study helps to enhance the understanding of coal seam floor behavior, guide floor management, and protect groundwater resources by defining deep and shallow mining to accurately predict floor failure depth.

Characterization of Seismic Dynamic Response of Uranium Tailings Dams Based on Discrete Element Method

Tailings dams play a critical role in ensuring the safety of mining operations. However, earthquakes can cause breaches in these dams, resulting in significant casualties and property damage. This study investigates the dynamic response characteristics of uranium tailings dams subjected to seismic loading, employing the discrete element method. It specifically analyzes how seismic wave amplitude, frequency, and the friction angle of tailings sand affect the dams’ dynamic response. The results reveal that the peak ground acceleration ratio (PGAR) exhibits an increasing–decreasing–increasing pattern with elevation. When the friction angle of the tailings sand exceeds 35°, the overall stability of the dam improves. Conversely, a friction angle below 25° significantly increases the risk of dam failure. Additionally, the dam shows a reduced dynamic response to seismic waves with frequencies exceeding 15 Hz. At lower frequencies, deformation and damage are primarily concentrated on the slope face, while at higher frequencies, damage is predominantly located at the bottom of the model. These findings provide a theoretical foundation and reference for the safe operation of tailings dams, highlighting their practical significance.

Data-driven visual model development and 3D visual analytics framework for underground mining

Data visualisation is broadly utilised to aid in presenting complex information, facilitating decision-making, and enhancing operational efficiency in the mining sector. However, due to the extensive utilisation of CAD files and the complexity and difficulty of converting 2D drawings into 3D models, it is challenging to realise (near) real-time 3D data visualisation in mining applications. The difficulties are including site drawing complexity, lack of standardisation, time-consuming cleaning, and imperative manual intervention. This paper addresses these challenges by focusing on an automatic, data-driven approach for 3D visual model development in mining, with an emphasis on lifetime support and sustainability. Therefore, we introduce standardised visual model data diagram and proposed conversion workflows to leverage digitised 2D drawings in automatic 3D visual model development. Moreover, to improve visualisation efficiency and facilitate visual analytics construction in mining, this paper also proposes a 3D tile index methodology for efficient visual model reconstruction and generic production data integration. To ensure lifetime support and sustainable development in visualisation, we propose two model expansion schemes: one based on dxf file-driven model development, and the other one is interaction-oriented 3D model design and development, which the two schemes share the same data exchange and conversion workflows. Furthermore, to facilitate data fusion among various datasets, we also provide insights into revealing spatial–temporal patterns among multimodality data by real-time visualisation. These advancements aim to propel the field of underground mining visualisation, offering significant insights into enhancing the efficiency and safety of mining operations.

Study on Grouting Performance Optimization of Polymer Composite Materials Applied to Water Plugging and Reinforcement in Mines.

With the increasing drilling depth of mines, the cross-complexity of fissures in the rock body, and the frequent occurrence of sudden water surges, polymer slurry, with its advantages of good permeability and strong water plugging, is increasingly used in mine grouting projects. Additional research is needed in order to further improve the grouting performance of polymer slurry, ensure the safety of mining operations, and reduce the grouting cost. In this paper, a polymer composite grouting material was prepared with diphenyl methyl diisocyanate, polyether polyol, and fly ash, as the main raw materials, with coupling agent and catalyst as auxiliary reagents. The performance of the composite grouting material in terms of mechanical properties, thermal stability, hydrophobicity, and bonding was explored. This study's findings indicated that incorporating fly ash led to notable enhancements in the thermal stability and water resistance of the polymer slurry. Furthermore, the introduction of fly ash notably raised the starting degradation temperature of the polymer, boosted the water contact angle of the composite material, and reduced the density and reaction temperature of the composite material. In addition, the catalyst and coupling agent as auxiliary reagents affected the polymers in terms of mechanical properties; in this paper, dibutyltin dilaurate was used as the catalyst, and organosilanes were used as the coupling agent. The catalyst successfully sped up the polymer's gel time, however, an excessive quantity of catalyst compromised the polymer's mechanical characteristics. The addition of organosilanes has a positive effect on the dynamic mechanical properties of the composites, fracture toughness, compression, bending, and bond strength. The research can offer a theoretical direction for creating polymer mixtures in mine grouting projects.

Exploring Machine Learning Techniques for Open Stope Stability Prediction: A Comparative Study and Feature Importance Analysis

The stability of underground excavations is essential for ensuring the safety of mining operations. Classical stability assessment methods, established in empirical formulas and rock mass classification systems, have long been employed for evaluating stope stability in underground mining. Stability graphs, a popular empirical approach, utilize factors like rock stress, joint orientation, and surface orientation to calculate stability numbers critical for stope design. However, modern advancements in machine learning present new opportunities for enhancing predictive capabilities and understanding complex relationships influencing stope stability. Building upon research demonstrating the feasibility of using machine learning for stability prediction, our study investigates and compares several machine learning algorithms. By analyzing a dataset comprising stope dimensions and geomechanical properties, we explore the potential of machine learning models such as Random Forest, Support Vector Machine, AdaBoost, XGBoost, LightGBM, and Artificial Neural Network in predicting stope stability. Evaluation metrics including accuracy, precision, recall, and F1 score are employed to assess model performance, with the Artificial Neural Network emerging as the most effective. Furthermore, SHapley Additive exPlanations (SHAP) analysis enhances interpretability by explaining the contribution of individual features to model predictions.

Predicting mine water inflow volumes using a decomposition-optimization algorithm-machine learning approach

Disasters caused by mine water inflows significantly threaten the safety of coal mining operations. Deep mining complicates the acquisition of hydrogeological parameters, the mechanics of water inrush, and the prediction of sudden changes in mine water inflow. Traditional models and singular machine learning approaches often fail to accurately forecast abrupt shifts in mine water inflows. This study introduces a novel coupled decomposition-optimization-deep learning model that integrates Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), Northern Goshawk Optimization (NGO), and Long Short-Term Memory (LSTM) networks. We evaluate three types of mine water inflow forecasting methods: a singular time series prediction model, a decomposition-prediction coupled model, and a decomposition-optimization-prediction coupled model, assessing their ability to capture sudden changes in data trends and their prediction accuracy. Results show that the singular prediction model is optimal with a sliding input step of 3 and a maximum of 400 epochs. Compared to the CEEMDAN-LSTM model, the CEEMDAN-NGO-LSTM model demonstrates superior performance in predicting local extreme shifts in mine water inflow volumes. Specifically, the CEEMDAN-NGO-LSTM model achieves scores of 96.578 in MAE, 1.471% in MAPE, 122.143 in RMSE, and 0.958 in NSE, representing average performance improvements of 44.950% and 19.400% over the LSTM model and CEEMDAN-LSTM model, respectively. Additionally, this model provides the most accurate predictions of mine water inflow volumes over the next five days. Therefore, the decomposition-optimization-prediction coupled model presents a novel technical solution for the safety monitoring of smart mines, offering significant theoretical and practical value for ensuring safe mining operations.

Community Perception of Gold Mining Affecting the Water Quality of the Wariori River

This study examines community perceptions of gold mining and its impact on the water quality of the Wariori River in Aurmios Village. The population involved all residents of Aurmios Village with a sample size of 20 (twenty) people. Using a qualitative research approach based on postpositivism and interpretive philosophy, data were collected through triangulation, combining observation, questionnaires, and interviews. The results show significant negative impacts of illegal gold mining on water quality and community life. The majority of respondents (95%) reported an increase in river water turbidity after mining activities, in line with the findings of Yulianti et al. (2016) and Putri Ade Rahma Yulis (2018) on the increase in Total Suspended Solids (TSS) and heavy metal pollution. In addition, 100% of respondents reported reduced clean water sources, leading to economic and health challenges, such as increased healthcare costs and a shift in livelihoods from fisheries and agriculture to gold mining. Environmental impacts include ecosystem degradation and increased flood risk, and 100% of respondents recognized these issues. In order to address these adverse impacts, the study recommends strict government measures to regulate illegal mining, establish safe and legal mining operations, provide clean water infrastructure, as well as educate communities on the dangers of illegal gold mining. These measures are essential to restore the water quality of the Wariori River and ensure the sustainable well-being of Aurmios villagers. Further research is needed to monitor long-term impacts and develop effective mitigation strategies.

Моделирование нестационарного тепломассопереноса в длинном очистном забое с учетом особенностей нагрева и охлаждения горного оборудования

Adverse microclimatic conditions in mines and shafts negatively affect both health of employees and the safety of workflows as a whole. The existing models to calculate microclimatic parameters can consider technogenic heat emission sources (mining machinery and equipment) only in «operation» and «shutdown» modes. For the first mode, heat emissions are adopted as constant; for the second mode, they are identically zero. In reality, however, thermal inertia is specific to the equipment. It is crucial to consider it for the correct simulation of aerological processes in mine ventilation networks. A dynamic model enabling the calculation of changes in microclimatic parameters (temperature and relative air humidity) for the preset time interval and equipment operation mode in the space of longwall mining and the adjacent fitting forklifts has been suggested in the article to increase the safety of mining operations. The key feature of the model is the registration of non-stationary heat transfer between the air and the power train (the source of heat emissions). The airflow of the motor by ventilation is provided in order to protect the source motor against overheating. Upon the shutdown of the source, the cooling system is switched off, and the source is cooled due to the natural heat exchange with the air. The simulation results are provided as a space-and-time air temperature field. The high-precision simulation is confirmed by insignificant differences between calculated and experimental values. Based on the developed model, an approach to forecasting heat load levels for an employee during a work shift is proposed. The approach is based on the simulation data and the data on the employee’s location during the work shift (planogram-based). The results of the simulation show insignificant differences compared with the data of continuous measurements, which can be explained by the deviation of a real operational process from a modeled planogram. Based on the above-mentioned, it can be concluded that the model is applicable for the assessment of the thermal stress level to which employees are exposed when attending operating working areas.

Оптимизация технологических способов отработки калийных запасов при камерной системе разработки

The diverse demand for inorganic fertilizers has predetermined the intensification of potash mining, which is a raw material for their production. In this regard, it has become necessary to create risk management technologies for underground mining of potash deposits considering the spatial planning of mining operations while increasing the technological productivity of underground combine machines. The purpose of the study is to develop a technology to increase the technological productivity of mining set equipment to a level as close as possible to a combine at a minimum volume of preparatory work coupled with stopping operations. The subject of the study is the procedure for mining a designated mine field of potassium-magnesium deposit. Methods. The study applies a formal logistics approach based on an analysis of known facts and existing problems at a mining enterprise, the regulatory and technical documentation used and current scientific trends in this field. Based on the results of the analysis, conclusions and justifications were made. Then, a solution to the problem is proposed. Results. The study presents a modernized and improved potash mining method considering spatiotemporal changes. When planning the development of individual sections of a deposit, geological services carry out underground additional exploration to supplement geological knowledge of the area in question. Such work includes geological exploration, drilling wells from the face and perimeter of the mined-out void to select core for mechanical and chemical (furrow and core) testing, geophysical studies, etc. Discussion. The set purpose is achieved by preparing and developing the field with diagonal rooms. Prior to stopping operations, additional exploration drifts are carried out along the upper edge of the mined seam by paired faces along the entire length of the selected block. These mined out voids allow obtaining additional geological information about the section of the mine field being mined. Conclusion. A scheme for mining a selected field with a described sequence of stopping and cutting is proposed. The proposed scheme allows: to increase the technological productivity of mining set equipment to a level as close as possible to a heading-and-winning machine; to minimize the volume of preparatory work coupled with stopping operations. Resume. The proposed scheme for mining a selected section of a mine field with the described sequence of excavation allows us to increase the technological productivity of the mining complex to a level that is as close as possible to the technical productivity of a mining and shearer while simultaneously minimizing the volume of preparatory work, combining these works with the work of mining. Suggestions for practical applications and directions for future research. The research results can be useful in potash deposit mining by chevron cutting method considering spatial planning, safe mining operations and replenishment of geological information about the field.

Модернизация технологий месторождений оловянных руд с учетом ретроспективной оценки опыта восстановления потенциала предприятий

The article describes the experience of restoring the potential of enterprises in the tin industry of the Khabarovsk Territory and the Chukotka Autonomous Okrug in difficult mining and geological conditions. The purpose of the study is a retrospective assessment of the experience of improving the technology of mining tin ores in stable rocks. Materials and methods. The goal is achieved through comprehensive research, including analysis and synthesis, comparison of calculated and experimental data, calculations of mass control parameters and measures to improve the quality of ores. Results. The characteristics of the deposits and the features of their location and ore extraction are given. The parameters of the applied development systems with differentiation into variants are detailed. A scheme of options is given with a critical analysis of their advantages and disadvantages so that they can be reproduced in similar conditions. Discussion. The effectiveness of the integration of ore mining processes and equipment for their implementation is shown. The experience of using an arsenal of systems for the development of shallow and inclined deposits in stable host rocks is described. The experimentally obtained dependences of the size of the pillars on the fall of the ore body and the spans of the mine are given. The variants of a promising chamber development system with the delivery of ore by the force of an explosion are detailed. Conclusion. It is shown that the development of tin deposits with the integration of the capabilities of technological processes and equipment ensures effective development of the field while improving the safety of mining operations and extraction of minerals from the subsurface. Resume. It is concluded that the integration of mining processes and equipment for their implementation is a reserve for the implementation of the production program, and the experience of developing tin deposits can be in demand when modernizing existing technologies and designing new deposits of solid minerals. Suggestions for practical applications and directions for future research. Future research will be aimed at addressing issues related to reducing ore losses and dilution, improving the rock pressure management system and increasing the environmental and economic efficiency of the enterprise.

A software for calculating coal mine gas emission quantity based on the different-source forecast method

The ability to predict gas emissions accurately is pivotal in managing gas control and ensuring safe mining operations. Existing internationally acknowledged gas control and prediction software does not cater to the specific conditions in Chinese coal mines. Hence, this paper introduces an object-oriented programming method to design a software tool for calculating the total gas emission quantity using the MATLAB application program designer runtime environment. The software incorporates an algorithm, data structure, framework, and module functions, all of which enable seamless integration and visualization of gas emission calculation software. This software tool mitigates the inefficiencies and inaccuracies associated with manual, different-source forecast methods. Based on the field data of the Hulonggou Coal Mine in Shanxi province, this technical software was used to predict the gas emission of the mine. The research results show that the predicted value of the technical software is close to the actual measured value. The differing estimates of the working face and coal mine output primarily account for the deviation between the tool's predicted gas emission value and the field-measured value. The underlying design logic of this technical software determines that it has good adaptability to mines with clear mining technology parameters and gas geological parameters. This study provides a valuable method for researchers and engineers seeking to improve gas emission calculation efficiency.

A New CRITIC-GRA Model for Stope Dimension Optimization Considering Open Stoping Stability, Mining Capacity and Costs

In the long-hole stage open stoping with subsequent backfill mining of underground metal mines, the selection or optimization of stope dimension parameters is significant for safe and economic mining operations. To analyze the optimal stope sizes, the Mathews empirical graph method and FLAC3D numerical method can be used, but the analyzed safety results of the two methods are generally independent from each other. More importantly, economic indicators including production capacity and mining costs should be considered simultaneously to optimize the stope dimension which was mostly ignored in previous reports. In this paper, a new CRITIC-GRA model was proposed for the first time to build up a multi-factor quantitative optimization for stope dimension, which allows for a comprehensive analysis with preset influential safety and economic indicators. The indicators considered include the safety indicators such as stability probability for the side walls and roof of the open stope via the updated Mathews graph method, maximum displacement, plastic zones volume and maximum principal stress via FLAC3D simulations, as well as economic indicators such as mining costs and stope production capacity in mine operations. The model was then illustrated in an underground iron mine. With the given rockmass quality in the mine, the overall stability of the open stope can be improved instead of reduced to enlarge the single stage stope height (60 m) to a double stage height (120 m) by reducing the stope width from 20 m to 15 m, thereby significantly increasing the mineable ore amount and improving the stope safety. An integrated evaluation of open stope stability, mining capacity and costs objectively determined that scheme No. 10, with a slope length of 50 m, a width of 15 m and a height of 120 m, was the optimum out of the 20 preset schemes. The new CRITIC-GRA model offers a dependable reference tool for determining the optimal stope dimensions in similar underground mines.

Research on the Influence of Temperature on the Assessment of Coal and Gas Outburst Dynamic Risk in Deep Mining

To ensure the sustainable development of energy supply, there is a continuous increase in demand for deep coal mining, making safe and efficient extraction a crucial area of research. However, with the increasing depth, rising ground temperatures pose new challenges for safe and sustainable mining operations. Among these challenges, coal and gas outburst dynamic hazards stand out as significant issues. Therefore, it is necessary to assess the impact of temperature variations on coal and gas outburst disaster prevention and control. To investigate this effect, we conducted an analysis based on outburst-triggering mechanisms and adsorption–desorption processes. Temperature was considered as the primary controlled variable, while gas expansion energy served as the criterion for assessing outburst hazards. Kilometer-deep coal samples were selected for measurement, focusing on indicators such as Langmuir adsorption constants (a,b), gas content (Q), gas pressure (P) and drilling cutting desorption indices (K1, Δh2). The results indicate that, under the same gas pressure, there is a slight decreasing trend in gas expansion energy with increasing temperature, although the overall change is minimal. Hence, the sole influence of temperature on the gas’s ability to perform work during outbursts is limited. Temperature exerts varying degrees of influence on gas parameters such as gas content and drill cutting desorption indices. The fluctuation amplitudes of these indicators range from large to small in the following order: Δh2 > ΔP > Q > K1 > P. Additionally, their correlation with gas expansion energy decreases in the following order: P > Q > Δh2 > K1 > ΔP. Thus, the influence of temperature on the indicators used in various prediction methods exhibits inconsistency, emphasizing the importance of considering temperature effects on predicted values. Gas pressure emerges as the optimal indicator for outburst determination, while gas content and drill cutting desorption indices are preferable as predictive indicators. These results will provide valuable references for the sustainable and safe development, risk assessment and prediction of deep coal mining.

Обеспечение безопасности труда горнорабочих совершенствованием электрических сетей при подземной добыче руд

In recent years, more attention has been paid to the increase in energy consumption by mining enterprises operating mines due to the need to replace the installed electric equipment and implement automated process management systems in mining and transport areas of the mine, which ultimately ensures safe and faultless operation of power supply system at various voltage levels in both individual subdivisions and the entire mine. During the experimental studies and solving problems, safe conditions for maintaining electric installations of the mine and maintenance personnel will be ensured. Weaknesses of the grid insulation and its elements have been detected; stable values for the resistance of motor insulation, switching equipment, laid cables, and the relevant probability distribution densities have been provided. This enables the replacement of individual unstable sectors of the power grid with new cables and equipment, which will significantly improve the safety of mining operations in the conditions of a high-altitude mine. It has been established that the motors used as actuators for scraper winches and fans must be replaced with motors of similar power equipped with organosilicon insulation or filling of frontal parts with enamel paint. The conducted studies enable the development of a comprehensive inspection methodology of the mine power supply system’s insulation elements and its application for further studies at other mines.