Mine Production Research Articles

Low-carbon development path based on carbon emission accounting and carbon emission performance evaluation: a case study of Chinese coal production enterprises.

Carbon emission accounting is the basic premise of effective carbon emission reduction and management. This study aimed to establish the carbon emission model and performance evaluation framework of coal mine production enterprises and clarify the low-carbon development path of enterprises. In this study, we took a typical coal production enterprise (K enterprise) in the Shanxi province of China as the research object. We also estimated the carbon emissions of the enterprise mainly according to the Chinese Carbon Emission Accounting Standard (GB/T 32151.11-2018). The triangular model was used to construct the carbon performance evaluation framework. On this basis, we suggested the enterprise's low-carbon development path. The results showed that (1) the carbon emission of K enterprise in 2021 was 36,875.38 tCO2eq; the carbon emission intensity of each ton of coal produced was 0.089 tCO2eq. The critical carbon emissions were electricity consumption and methane fugitive emissions during production. (2) The evaluation indicators for carbon emission performance revealed an imbalance in K enterprise's economic, energy, and environmental development in 2021. The work on energy saving and consumption reduction was relatively weak. (3) Countermeasures for low-carbon development, including a carbon emission ledger, were proposed based on carbon emission accounting and performance evaluation results. This study can help typical underground coal production enterprises in Shanxi province obtain more accurate carbon emission data, providing practical guidance and reference for the same underground coal production enterprises to improve the carbon emission control effect.

Development of Novel Hybrid Intelligent Predictive Models for Dilution Prediction in Underground Sub-level Mining

Tenuous dilution estimates in underground mine production scheduling continue to cause significant variations between schedule forecasts and actual production. This arises partly from the inference of dilution from predecessor stopes’ performance, disregarding that these stopes would have undergone multiple intermediate design changes between scheduling and actual mining. The resultant drill and blast-influenced dilution factors gradually lose its robustness over longer planning horizons or when applied to greenfield or brownfield expansions that do not have prior performance data. To overcome this problem, a new methodology is proposed to predict dilution in underground sub-level open stoping (SLOS) using basic geological, geotechnical and stope design attributes available in the early stage of mine planning. The method utilises principal component analysis (PCA), classification and regression tree (CART) algorithm and stepwise selection and elimination (SSE) analysis. First, SSE analysis was conducted to identify the most important independent variables to be used with the CART algorithm (i.e., the SSE-CART model) to provide a predictive model. PCA analysis was then performed, and the new principal components were used to propose a new comparative model (i.e., the PCA-CART model). Low R2 values were observed for both models, necessitating the consolidation of dilution categories to increase the models’ prediction bandwidth. The hybrid PCA-CART model outperformed the SSE-CART model with overall F1 score prediction accuracy of 72% and target dilution category prediction accuracy of over 93% against SSE-CART’s 70% and 72%, respectively. Importantly, this study revealed a 13% minimum underestimation of dilution relative to the original design stopes.

Experimental study on the mechanical characteristics of weakly cemented mudstone under different loading rates

With the gradual shift of coal mining to the western coal mining region of China, floor heave in weakly cemented mudstone roadways has become an issue affecting the safety and efficiency of coal mine production. Additionally, different mining rates can lead to fluctuating support stresses on the roof and floor of weakly cemented mudstone roadways. Therefore, obtaining a comprehensive understanding of the mechanical properties of weakly cemented mudstone at different loading rates is conducive to improving the issue of floor heave in such roadways and provides a theoretical basis for further study. In this context, a series of uniaxial mechanical tests with concurrent acoustic emission monitoring were conducted on specimens of weakly cemented mudstone under various loading rates (0.005, 0.01, 0.05, and 0.1 mm/s). The stress‒strain and acoustic emission response curves were obtained to effectively characterize the strength, deformation, damage, macroscale instability, and crack propagation characteristics of the mudstone under the influence of loading rate effects. The research results support the following findings: (1) With increasing loading rate, the peak strength and elastic modulus of weakly cemented mudstone significantly increase, while the peak axial strain and peak radial deformation significantly decrease. (2) With increasing loading rate, the stress required to trigger the expansion of weakly cemented mudstone gradually increases, and a significant power-law relationship arises between the strain of the mudstone at the start of expansion and the loading rate. (3) With increasing loading rate, the acoustic emission ringing count of weakly cemented mudstone increases: The failure of weakly cemented mudstone changes from small-range progressive failure to sudden failure, and the failure mode transitions from shear failure to tensile‒shear composite failure. (4) The studied mudstone damage variables increase with increasing loading rate, following an approximate exponential function. The conclusions obtained in this work can provide a theoretical basis for the evolution mechanism and control of floor heave in deep roadway mining.

Effect of low blockage ratio obstacle on explosion characteristic in methane/air mixture

Methane/air explosion is one of the common hazards in process and mining industries. In this study, the methane explosion propagation is studied, and two-dimensional configuration is considered. The gas phase equations are solved using an OpenFOAM code for compressible reacting flow, EXiFOAM. The effects of the low blockage ratio (LBR) obstacles are investigated. The results show that the flame propagation speed, flame structure, shock wave propagation, and gas flow are considerably affected by LBR obstacles. Specifically, the flame propagation speed first increases and then decreases. As the initial pressure increases, the flame propagation speed gradually increases. The maximum speed is up to 500 m/s, when the initial pressure is 1.5 MPa. If the flame propagation is prevented, resulting in the flame deformation. Moreover, the flame disruptive phenomenon is captured due to the reflected waves. In front of the obstacle, the cellular structures of the high-pressure distribution are formed. Note that the tiny cellular structures are produced in the wake of the leading shock. Furthermore, a high-speed flow region and two low-speed flow regions are produced around the LBR obstacles. It is found that as the initial pressure increases, the explosion pressure is larger, while the temperature change is not obvious. These research findings have implications for enhancing safety production in coal mines.

Research on the optimal design of roadway support for fully mechanized coal seam working face

Abstract For the optimal design of surrounding rock deformation and support in the shallow buried coal seam of large-scale fully mechanized mining face, this paper took the surrounding rock of the roadway as the research object, used theoretical calculation and numerical simulation to establish the mechanical model of the deformation of the surrounding rock structure, and proposed and analyzed the reasonable roadway support scheme of the shallow buried coal seam. The numerical simulation results showed that the top anchor rod with Φ18×2200 mm and the inter-row distance of 1100×1000 mm, the anchor cable with Φ15.24×6300 mm and the inter-row spacing of 2200×2000 mm, the upper part anchor of Φ16×2200 mm, and the C30 concrete with a thickness of 200 mm for laying the bottom plate are selected, which was certified as the optimal support scheme. In practical engineering applications, the deformation of surrounding rock has been effectively controlled, and the supporting effect of surrounding rock was obvious, which was of great significance to ensure the safe production of coal mines.

Experimental study on classification and identification method for fault signals of mining steel wire ropes

Abstract In the coal mining production process, wire ropes play a crucial role as the main tool for transporting personnel and materials in the entire coal mine hoisting system, and their fault identification is particularly critical. To address the problem of fault identification of mining wire ropes, a recognition model design combining K Singular Value Decomposition (SVD) with Genetic Algorithm (GA) optimized Support Vector Machine (SVM) is proposed. Firstly, K Singular Value Decomposition is used to denoise the collected wire rope damage signals. Feature vectors are extracted from the denoised and reconstructed signals to form the feature set of wire rope damage. Genetic Algorithm is utilized to select the optimal parameters of the Support Vector Machine and train it to obtain the optimal identification model for wire rope damage. Simulation and experimental results show that compared with wavelet thresholding and Empirical Mode Decomposition (EMD) denoising algorithms, the method using K Singular Value Decomposition for denoising achieves a signal-to-noise ratio of 25.166dB and a root mean square error of 0.805. Compared with Particle Swarm Optimization (PSO) optimized Support Vector Machine identification model, the identification rate of the Support Vector Machine identification model optimized by Genetic Algorithm is higher, reaching 96.67%. This method realizes accurate identification of different damage signals of wire ropes, which is conducive to ensuring the safe and efficient production of coal mines.

TRAFFIC CAPACITY ANALYSIS OF EXISTING CONDITIONS WITH THE EFFECT OF ADDITIONAL COAL TRANSPORTATION TARGETS ON THE TANJUNG ENIM - TARAHAN RAILWAY LINE

The production volume target from 24.8 million tons in 2020 to 29.5 million tons in 2021 underlies the optimization of transportation availability in distributing coal mining products carried out by PT Bukit Asam Persero in achieving the growing target until 2023. In 2021, the Company will increase investment in developing business diversification, downstream coal. The railway network in Sumatra has a strategic role in serving the distribution of coal transportation. The railway line, which is directly connected to the location of the mining plant to port access and the availability of locomotive facilities and wagons that are very adequate, is an attractive option for mining companies and freight forwarders to establish coal transportation cooperation by rail. To meet the Babaranjang train tonnage target of 52 tons / year in accordance with the target of PT Bukit Asam (Persero), the Loop rail line design at TLS T4 PT Bukit Asam Muara Enim used the most effective classification. From the calculation results, 55 train trips are required per day to transport the production target of 57 tons / year in 2023. It is necessary to pay attention to the adequacy of the rail track from the TLS loop to Tanjung Enim Baru here it is necessary to conduct a study regarding the traffic from TLS to Tanjung Enim Baru because the number of trains set per day is 55 sets.

Insulation life prediction of stacking multi-model fusion motors based on Conv1d-LSTM

Abstract The insulation system of the mine motor is key to ensuring its stable operation, which affects the efficiency of mine production and transportation and the benefit of enterprises. The prediction of motor insulation life can effectively prevent the deterioration of motor performance. Due to the complex underground environment, many factors affect the insulation of coal mine motors, which are not conducive to the selection of feature parameters. The insulation life prediction efficiency and accuracy of motors need to be improved. To solve this problem, this paper proposes a prediction method based on Conv1d (one-dimensional convolve) and LSTM (long short-term memory neural network), which integrates multiple models and the Stacking integrated algorithms. The operating data and environmental parameters of a coal mine motor under different conditions are analyzed. Three Conv1d-LSTM hybrid models with batch normalization, residual network, and dense number are used as the base learner, and the results are weighted by K-fold to verify the accuracy of the three models. The linear regression model is used as a meta-learner to prevent overfitting of the model and effectively improve the speed and accuracy of single network optimization. Compared with the traditional method, the results show that the optimization of the LSTM neural network by the multi-feature model has a higher accuracy in predicting the remaining life of motor insulation, which provides a new way for the prediction of motor insulation life.

Assessment of Mine Plans for Production and Variations at Ibese Limestone Mines

This research investigated the mine plans used for the production target and annual production of limestone for the past seven (7) years. The actual amount of limestone produced per year in tons was computed to determine the variations in the mine's production and the life span of the reserve of limestone deposits. A new mine plan was proposed, and a targeted amount of limestone production per year was suggested. The mine plans for the mine's production were generated from 2014 to 2020 using a complete data collection system for Real Time (RTK) GPS and Total Stations with in-field coordinate geometry called SurCE by Carlson Software. The total production target for the seven (7) years was 87,017,146 tons and the actual production was 76,313,056 tons. The total variations for the years under this assessment were -10,704,090 tons except for the year 2018 when the actual production was higher than the production target of 511,179 tons. The volumetric reserve estimation revealed that the total volume of the limestone reserve is 5,052,236,090.186 tons. The expected production per week was computed to be 356,400 tons/week, expected monthly production, (EMP) was estimated to be 1,425,600 tons/month. The expected production year, (EPY) was 17,107,200 tons/year and the life span of the limestone deposit, (LS) was computed to be 295.34 years. It can be suggested that the company should target a production rate of 1,425,200 monthly and 17,104,200 per year. This suggestion can be achieved if there is enough investment in terms of skilled labour, heavy-duty machinery, and equipment which will cost-effectively boost production.

Оценка хозяйственных рисков при реализации технологий угледобычи в современных условиях недропользования

Introduction. This paper presents research in the field of methodology of assessment and monitoring of associated under ground coalmining risks in order to level their impact on the resulting technical and economic indicators of production and economic activities in modern conditions of subsoiluse. The functioning of technological systems of coal mining enterprises at the present stage of subsurface use occurs in a highly dynamic and highly variable functional environment with a fair degree of uncertainty, which is generated by a significant variety of parameters and characteristics of the initial mining, geological and mining engineering environment, which, in turn, generates the emergence of various groups and risk factors for subsurface use. The established procedures and methods of risk forecasting currently do not give satisfactory results due to the globalization of world markets and high volatility of prices for coal products. Leveling the negative degree of influence of the risk component on the resulting indicators – indicators of technical and economic activity can be achieved through the introduction of an operational system for assessing and monitoring various groups of risk factors. Materials and methods. For the purpose of evaluation, it is proposed to use the methodological and methodological foundations of the method called “vector norms”, which involves the use of Affine space, the constituent areas of compromises and the introduction of utility estimates. A complete model representation of the assessment and monitoring of the impact of various risk factors of subsurface use, taking into account their clustering and ranking, is presented. The algorithmic support of this method is reduced to the following components-iterations: 1. Formation of criteria-based assessment matrices of various factors of subsurface use risk groups. 2. Assignment of optima to evaluation criteria. 3. In order to ensure the legality of the use and implementation of mathematical procedures and operations, the reduction of multi-dimensional evaluation criteria to a relative form, taking into account the assigned optima. 4. Formation of the objective function of the “norm of the vector” (integral indicator) and the development of a procedure for selecting the optimal option. Since the use of the methodological and methodological foundations of the method called “vector norms” allows us to form quantitative estimates of the presented factors-types of risk of subsurface use, this makes it possible to implement the clustering procedure or ranking of a selected set of coal mining enterprises in conjunction with existing risk areas. Results. Quite high values of correlation coefficients were obtained with a significant closeness of the relationship of inversely proportional dependencies of generalizing integral indicators of the degree of risk and the level of achievement of planned indicators and development of production capacity with the level of operational profitability from the conduct of production and economic activities of coal mining enterprises with a directly proportional dependence on the operating costs of mining 1t of coal. Discussion. Сomplete model representation of the assessment and monitoring of the impact of various risk factors of subsurface use, taking into account their clustering and ranking, is presented. As a practical component of the research, variable series of areas of integral degree of risk in the functional environment of Kuzbass coal mines are presented. The use of software modules for correlation and regression analysis, taking into account three-year retrospective dynamics, made it possible to establish the legality and objectivity of the proposed methodological apparatus for integrated risk assessment of the implementation of coal mining technologies in modern conditions of subsurface use. Conclusion. The results of the implementation of the theoretical components of the methodology and model representations of the developed conceptual foundations for the integrated risk assessment of the implementation of coal mining technologies in modern conditions of subsurface use, taking into account five-year retrospective dynamics, showed that in the Kuznetsk basin there was a steady tendency to reduce the cluster of coal mines, which is characterized by high risks of carrying out production and economic activities in the presence of a disproportion of resource potential (the emergent part). The accompanying processes of formation of this trend are manifested in a quantitative increase in the functional units of the rating cluster of group 2B with an average resource potential and inherent moderate risk. It is within this cluster that strategies for prioritizing investments for the development and renewal of technological systems and structures of coal mining are being formed, since only they are able to provide the fastest possible return on invested funds. Resume. The article presents the results of research in the field of methodology for assessing and monitoring the risks associated with underground coal mining in order to level out their impact on the resulting technical and economic indicators of production and economic activity in modern conditions of subsoil use. The research results can be useful in the implementation of coal mining technology in modern conditions of subsoil use.

THE EAST HINDIA COMPANY'S TRADE AND THE MOESLIM ECONOMY IN THE MUGHAL SULTANATE OF INDIA, 1610-1630 AD

The Mughal Sultanate was one of the great Islamic sultanates in the classical Islamic era, the Mughal contribution to Islamic civilization in India was very large in terms of politics, culture, architecture, and economy. In the economic field, the Mughals had been independent before the arrival of the EIC in the sultanate in 1610, the Mughals had exported a lot of their agricultural and mining products to both Asia and Europe by cooperating with Muslim merchants, as well as land rulers both Muslim and Hindu. The arrival of EIC in the Mughal Sultanate changed the existing economic order because EIC in smoothing its business often entered into contracts with landlords and bribes with the Mughal apparatus it had significant implications for the development of the Islamic economy in the Mughal Sultanate. EIC also played a monopoly in India and outside India, resulting in the death of the Islamic economy. Eventually, many Muslim merchants and landlords turned to EIC for the sake of their business.

FEATURES OF THE IRON ORE MARKET OF UKRAINE DURING THE FULL-SCALE INVASION OF RUSSIA INTO UKRAINE

Objective. The objective of the article is to study the main features of the situation of the iron ore market of Ukraine during the full-scale invasion of russia into Ukraine. Methods. The following methods were used to analyze the main features of the market situation of ore mining products of Ukraine during the full-scale invasion: the dialectical method of learning processes and phenomena (for researching the market situation of ore mining products); methods of analysis and comparison (to study directions of changes in the market situation of ore mining products in the conditions of a full-scale invasion); graphic (to display the dynamics of the market situation of ore extraction products); index (to assess the rates of growth of the investigated indicators); method of multifactorial multiplicative forecasting (for forecasting sales volume of ore mining products). Results. In the conditions of a full-scale Russian invasion, there is a low market situation for iron ore in Ukraine. The main reasons for the negative changes in the iron ore market include: the destruction of industrial capacities, which affected the overall production volume of the mining industry, and the blockade of sea ports, which caused the problem of exporting Ukrainian iron ores to worsen during a full-scale invasion. An analysis of the main features of the situation of the Ukrainian iron ore market during the full-scale invasion showed a significant drop in the volume of iron ore exports and imports, with imports falling at a faster rate. The performed forecasting of the volumes of sold products of ore extraction shows an expected decline in the market situation during the next two years, however, in the future, provided that the full-scale invasion is completed and post-war recovery begins, positive changes in the market situation of ore extraction products can be expected.

Emerging techniques for the trace elemental analysis of plants and food-based extracts: A comprehensive review

This comprehensive review investigates the dynamic landscape of trace elemental analysis methodologies applied to plants and food-based extracts. The exploration spans from the inception of techniques to the latest procedures, contributing to heightened precision and sensitivity in elemental detection. According to the WHO, herbal plants and medicine from varied soil compositions serve as crucial therapeutic agents for 70–80 % of the world's population. Yet, their susceptibility to trace element toxicity poses a significant risk to human health. Rising population and increased food demands have led to environmental pollution, contaminating the food chain through unintended activities like industrialization, mining, and pesticide production. The elemental composition of plants and derived extracts is central to comprehending nutritional profiles, evaluating product quality, and ensuring food safety. Methodological advancements, progressing from manual procedures to sophisticated technologies such as X-ray fluorescence (XRF), neutron activation analysis (NAA), inductively coupled plasma optical emission spectroscopy (ICP OES), and inductively coupled plasma mass spectrometry (ICP-MS), are delineated. Recent strides in paper-based electrochemical sensors are highlighted for their distinctive capabilities and elucidation of associated advantages and limitations.Moreover, the review delves into innovative sample preparation methodologies, encompassing microwave-assisted digestion and solid-phase microextraction, to amplify the efficiency of elemental extraction and subsequent analysis. Integrating data analytics and machine learning in elucidating complex elementary datasets is explored, underscoring the potential for heightened accuracy and automation in trace elemental analysis. This review compiles literature data, summarizing sample preparation methods for various herbal parts (roots, soil, stems, bark, fruits, food). Standard protocols from WHO, United States Pharmacopeia-National Formulary (USP-FR), Ayurveda, Yoga and Naturopathy, Unani, Siddha, and Homeopathy (AYUSH) are considered. Lead, Cadmium, Mercury, and Arsenic are the primary toxic elements of concern in herbal medicines. This review furnishes valuable insights tailored for researchers, analysts, and policymakers actively involved in advancing the domain of trace elemental analysis in plants and food-based extract.

Ultimate Pit Limit Optimization Method with Integrated Consideration of Ecological Cost, Slope Safety and Benefits: A Case Study of Heishan Open Pit Coal Mine

The ecological impacts of mining and the instability of slopes are the key factors restricting the safe, efficient, and low-carbon production of open-pit mines. This study focused on the ultimate pit limit (UPL) optimization under the concept of sustainability by integrating consideration of the economic benefit, ecological impact, and slope geometry. The integrated UPL optimization model based on the floating cone method was proposed by establishing a quantitative model for ecological impacts arising from open-pit coal mining in arid or semi-arid weak ecological land and a cost calculation model of slope reinforcement based on the Monte Carlo method. The case study revealed that steepening the slope angle of given regions resulted in random variations in the quantity of ore rock and the limit morphology. There was an average economic profit rise of USD 9.54M with every 1° increase in slope angle, but the probability of slope instability and the reinforcement cost grows exponentially. In the arid or semi-arid weak ecological land, the ecological costs exceeded 20% of the mines’ average pure economic gains. The proposed optimization method contributes to obtaining an integrated optimal UPL, improving the benefits and the ore recovery rate.

Analisis Pelaksanaan Stockpile Terpadu dalam Tata Kelola Pertambangan di Kabupaten Lumajang

Community economy and Local Original Income as part of factors in regional development. One of the utilization of regional potential is natural resources. Lumajang Regency as one of the districts in East Java Province with the existence of Mount Semeru as one of the active volcanoes in Indonesia. Stockpile is a place that is used as a location for stockpiling mining products of IUP owners. Sand stockpiles are spread in almost all areas of Lumajang Regency. Stockpile management is part of the existing sand business license. Stockpile managers must have an IUP either on their own business or in cooperation with the IUP owner. In improving and structuring existing stockpiles in the Lumajang Regency area, the Lumajang Regency Government through Lumajang Regent Regulation number 40 of 2022 concerning Integrated Stockpiles is expected to organize and increase Regional Original Revenue (PAD) in the form of Non-Metal and Rock Mineral Taxes. This study uses a qualitative descriptive approach, with data collection in the form of interviews, observations and collection of existing regulatory documents. The informants of this research are individuals who are directly involved in mining activities or activities, communities around the integrated stockpile, the community of Lempeni Village, Tempeh District, which has a stockpile divided into an integrated stockpile, regional officials in charge of Non-Metal and Rock Mineral Tax and stockpile managementintegrated. The result of this study is that the community's economy for mining management at integrated stockpile locations increases with the growth of non-formal professions of the surrounding community, namely ticket guards, cleaners, stalls, as joggers, security officers and traffic. Meanwhile, in the people of Lempeni Village, Tempeh District, before there was an integrated stockpile, there was a reduced stockpile and even no longer worked in the mining sector, namely some did not work and some worked as factory workers.

Boundary quantitative characterization of the top-coal limit equilibrium zone in fully mechanized top-coal caving stope along the strike direction of working face

In the process of fully mechanized top-coal caving mining, the top-coal is affected by mining-induced stress, and the stress varies along the strike direction of working face, so the boundary position of its entering the limit equilibrium state changes accordingly. The determination of the boundary along the strike direction of working face can provide scientific guidance for the stability control of support-surrounding rock in fully mechanized top-coal caving face. Using the research methods of theoretical analysis, physical similarity simulation experiment and numerical simulation experiment, the stress state analysis model of the boundary position of the top-coal limit equilibrium zone under macro-scale conditions was established, the stress state characterization method of the boundary of the top-coal limit equilibrium zone along the strike direction of working face was given, and the quantitative characterization of the boundary of the top-coal limit equilibrium zone along the strike direction of working face was realized by combining with the mining-induced stress path, and the distance relationship between the boundary of the top-coal limit equilibrium zone and the langwall face along the strike direction of working face was revealed. The results show that after critical mining in fully mechanized top-coal caving face, the distance between the boundary of top-coal limit equilibrium zone and the langwall face along the strike direction of working face presents a relationship of increasing from top to bottom. The distance between the top-coal upper boundary and the langwall face was 2.85 m and the distance between the top-coal lower boundary and the langwall face was 5.39 m. The boundary of top-coal limit equilibrium zone along the strike direction of working face was verified by the top-coal elastic–plastic zone boundary and the boundary of the peak position of front abutment pressure in different layers of top-coal. The results show that the quantitative characterization of the top-coal limit equilibrium zone boundary along the strike direction of working face was reasonable. In order to improve mine production efficiency, optimization measures were put forward for hard coal seam and soft coal seam respectively.

Groundwater identification using geophysical tools and its implications for the stability of slopes in an open pit mine

The open pit mining development begins with the opening of pits with the rock mass excavation and formation of slopes and berms for ore exploration. Knowledge about the geological conditions represents an important step in this process, since rock masses generally have heterogeneous characteristics and the presence of discon- tinuities can become an aggravating factor in the safety of operations. The characterization and classification of these discontinuities, as well as the identification of the groundwater in the rock mass, has a great importance to ensure the safety of operations during the mine's production process, in addition to ensure the effectiveness of its decommissioning process. The use of DC resistivity geophysical method has been increasing to characterization and identification lithological types and presence of water, since it is a non-invasive research tool with fast ability to obtain data. DC resistivity together with visual investigation methods, such as obtaining the discontinuities orientation and their alteration characteristics, provides important information for the characterization of the rock mass. Given this importance, the present work aimed to use DC resistivity to identify the presence of water and its correlation with lithology and rock mass structure in order to identify how these variables influence the occurrence of ruptures. To this end, two-dimensional resistivity sections were designed and related to visual inspection data and kinematic analyzes obtained from structural data of the rock mass. The integration of these results indicated that the ruptures present in the investigated mine slopes are related to zones whose predominant lithology is volcanic breccia with the presence of water in the subsurface. These ruptures compromise the stability of the slopes and consequently make the decommissioning mine process difficult.

Study on Ratio Optimization and Diffusion-Gelation Process of Polymer Grouting Materials for Fracture Filling in Underground Mines.

The existence of fissures poses a serious threat to the safe production of underground mines, and this paper investigates a polymer grouting material for filling fissures in underground mines. To optimise the ratio of polymer grouting materials, this paper designed 16 test groups using the orthogonal test method to find the most reasonable slurry ratio. In order to study the gel diffusion process of polymer slurry in the fissure and to explore the changes of various parameters of the slurry after injection, simulated grouting tests were carried out, and the distribution laws of viscosity, pressure, and diffusion distance of the slurry were discussed. The findings indicate that when the proportion of ethylenediamine polypropylene oxide tetrol: glycerol polyether: catalyst: foam stabiliser is 10:8:0.5:0.4, the polymer grouting material has excellent compressive strength, and the maximum compressive strength can reach 12.31 MPa. Prior to reaching the gel time point, the viscosity of the polymer slurry was nearly constant, which is basically maintained at 0.772 Pa·s under normal temperature and pressure, but after reaching the gel time point, it abruptly rose. As the slurry mass increased, so did the penetration distance and pressure; in the simulated grouting test, when the slurry mass was 400 g, the maximum diffusion distance of the slurry reached 39 cm. Conversely, as the fracture pore size increased, the diffusion distance and pressure of the slurry decreased. Along the diffusion path, the slurry pressure progressively drops, but this change is not synchronised with the diffusion distance's change. This work can serve as a reference for the configuration of polymer slurry and aid in comprehending the diffusion law of the slurry within the fissure.

Analysis of the Gas Safety Situation Based on the Schweizer-Sklar Rule.

In the coal mining process, a large amount of harmful gases will be produced, which we call "gas". The main component of gas is methane. After the methane concentration reaches a certain limit, an explosion will occur, seriously affecting the safety of the production of coal mines. Gas safety situational awareness is an important basis for gas early warning. In order to take appropriate measures for different levels of risk, the safety situation level is classified into five levels, which can be attributed to the classification problem in machine learning. We propose a gas security situation analysis model based on the Schweizer-Sklar rule (GSSAM-SSR) using the multiweighted Schweizer-Sklar triangular norm array combination rule (SSR). First, the raw data are preprocessed. The model uses K-means clustering with feature preference to determine the label column of the data set and principal component analysis to reduce the dimensionality of the collected high-dimensional gas-related data. Ten basic classification models are constructed, and the best performing models are selected as the basic classifier set by using the preorder method. Then, the SSR combination rule is proposed to combine the basic classifiers. Finally, considering the dynamic and quasi dynamic data of the mine, the basic classifier set and SSR combination rule are combined to construct the GSSAM-SSR model and applied to the gas security situation analysis. Experimental results show that the SSR combination rule achieves the best classification performance, exhibiting an accuracy of 94.43%, which is 2.51% higher than the accuracy of the gradient boosting decision tree model, which was the highest performing basic classifier and higher than the accuracies of the voting method and Bayesian combination rule.

Full-scale study on the coupling settling behavior of droplets and PM10 particles based on the CLSVOF method and wetting experiments

Coal mines produce large quantities of dust during production and transportation of coal, especially respirable particulate matter of diameter < 10 µm (PM10). This not only jeopardizes the health of workers but also pollutes the environment. Currently, spraying is the most commonly used dust reduction technology. Traditional spraying techniques use pure water; however, the wetting and condensing of dust by pure water droplets is poor, resulting in low dust reduction efficiency. To address this issue, we used orthogonal tests to determine the optimal ratio of composite dust-reducing agents. Using the coupled level set and volume of fluid (CLSVOF) method, we investigated the dynamic wetting process of PM10 when using solutions of dust-reducing agents. We found that a particle size ratio of ≥ 2 and an initial velocity of droplets of 20–40 m/s resulted in optimal wetting and encapsulation of dust particles by droplets. We then conducted macroscopic experiments and found that the settling efficiency of PM10 reached 88.98 % when using a 1.5-mm caliber fine atomizing nozzle and a spray pressure of 6 MPa. Our findings reveal the dynamic wetting law of droplets and dust during the process of spray dust reduction, which could lead to improved efficiency of dust-reducing agents and better management of respirable dust. These findings will help to improve clean production in coal mines and the occupational health of coal miners.