Mine Atmosphere Research Articles

Flow of a viscous dispersing gas-air mixture due to a sudden release of gas into the mine atmosphere

Flow of a viscous dispersing gas-air mixture due to a sudden release of gas into the mine atmosphere

Использование нечеткого метода распознавания образов для мониторинга запыленных помещений

ABSTRACT This article discusses a decision support system (DSS) based on fuzzy methods used to identify and process gas dynamic images obtained during monitoring and control of underground coal mine atmosphere processes. DSS supports ventilation operator solutions in complex and unforeseen gas dynamic situations. The work will analyze the quantitative and qualitative information used by the ventilation operator to make decisions. Based on these data, an analysis of the effectiveness of using fuzzy models and methods for interpreting and processing gas dynamic images will be carried out. Fuzzy models and methods of interpretation and processing of gas dynamic images will be proposed. In the future, based on these models and methods, the operator's decision support software will be developed.

Semi-autonomous sensor fusion-based strategy for unmanned aerial atmospheric surveillance system in open field environments

<p>This paper explores the convergence of semi-autonomous systems and sensor fusion for monitoring hazardous atmospheric substances in open and semi-confined environments such as open-pit mines. As the heart of this system, a universal and flexible device leveraging wireless technologies to collect and analyze large volumes of data, designed by the authors, is proposed. The article outlines the key components of the platform, emphasizing its potential for increasing personnel safety levels as stipulated by the international public exposure guidelines. In modern mines, it becomes crucial to monitor elevated concentrations of nitrogen and carbon oxides, as well as other pollutants after blasting and the toxic gas emissions produced by the heavy transportation equipment such as mining trucks and excavators. In this paper, industrial-grade electrochemical sensors are compared with price-affordable but less precise microelectrochemical ones. The performed experiments for lowering computational requirements show promising results. The integration of an ultrasonic anemometer enhances the system’s capabilities, contributing to a comprehensive understanding of atmospheric conditions. In parallel, the research discusses the role of computer vision in autonomous control systems, with a focus on the architecture and processing pipeline of the state-of-the-art system-on-module Kria by AMD. Advocating the potential of adaptive computing for enhanced efficiency in dynamic environments, the paper underlines the importance of the integrated approach in developing a semi-autonomous atmospheric surveillance system and highlights the impact of adaptive computing in dynamic scenarios. The main part of the measuring equipment and methods has been experimented with in real conditions in open-pit mines in Bulgaria. This is an initial phase of ongoing research aimed at serving as a foundation for future improvements and the elaboration of a fully autonomous prototype for hazardous substances evaluation in the atmosphere of open-pit mines.<strong></strong></p>

Assessing the hazard of diesel particulate matter (DPM) in the mining industry: A review of the current state of knowledge

In the confined spaces of underground mines, the exposure of over 10,000 miners in the U.S. to diesel exhaust and diesel particulate matter (DPM) is an occupational inevitability, particularly in metal and nonmetal mineral extraction. These workers routinely operate amidst diesel-powered equipment, often outdated and highly polluting, extracting resources such as limestone, gold, and salt. The acute health effects of such exposure are significant, leading to symptoms like headaches and flu-like conditions, with the impact being more pronounced in these closed work environments. This review scrutinizes DPM’s hazard in the mining sector, consolidating the extant knowledge and exploring ongoing research. It encapsulates our understanding of DPM’s physicochemical properties, existing sampling methods, health ramifications, and mitigation technologies. Moreover, it underscores the necessity for further study in areas such as the evolution of DPM’s physicochemical attributes, from its genesis at high-pressure, high-temperature conditions within diesel engines to its emission into the mine atmosphere. A key research gap is the intricate interaction of DPM with specific characteristics of the mine environment—such as relative humidity, ambient temperature, the presence of other mineral dust, and the dynamics of ventilation air. These factors can significantly alter the physicochemical profile of DPM, influencing both its in-mine transport and its deposition behavior. Consequently, this can affect the respiratory health of miners, modifying the toxicity and the respiratory deposition of DPM particles. Identified research imperatives include (1) the advancement of instrumentation for accurate number measurement of DPM to replace or supplement traditional gravimetric methods; (2) the development of long-lasting, cost-effective control technologies tailored for the mining industry; (3) an in-depth investigation of DPM interactions within the unique mine microclimate, considering the critical components like humidity and other aerosols; and (4) understanding the differential impact of DPM in mining compared to other industries, informing the creation of mining-specific health and safety protocols. This review’s findings underscore the urgency to enhance emission control and exposure prevention strategies, paving the way for a healthier underground mining work environment.

Application of Artificial Intelligence to the Alert of Explosions in Colombian Underground Mines

The use of Artificial Intelligence (AI), particularly of Artificial Neural Networks (ANN), in alerting possible scenarios of methane explosions in Colombian underground mines is illustrated by the analysis of an explosion that killed twelve miners. A combination of geological analysis, a detailed characterization of samples of coal dust and scene evidence, and an analysis with physical modeling tools supported the hypothesis of the existence of an initial methane explosion ignited by an unprotected tool that was followed by a coal dust explosion. The fact that one victim had a portable methane detector at the moment of the methane explosion suggested that the ubiquitous use of these systems in Colombian mines could be used to alert regulatory agencies of a possible methane explosion. This fact was illustrated with the generation of a database of possible readouts of methane concentration based on the recreation of the mine atmosphere before the explosion with Computational Fluid Dynamics (CFD). This database was used to train and test an ANN that included an input layer with two nodes, two hidden layers, each with eight nodes, and an output layer with one node. The inner layers applied a rectified linear unit activation function and the output layer a Sigmoid function. The performance of the ANN algorithm was considered acceptable as it correctly predicted the need for an explosion alert in 971.9 per thousand cases and illustrated how AI can process data that is currently discarded but that can be of importance to alert about methane explosions.

Самовоспламенение пылегазовоздушных смесей в атмосфере горных выработок

The underground mining of coal deposits is usually accompanied by manifestation of a number of negative factors, one of which is the presence of dust and gas-air mixtures consisting of fine coal dust, methane released from the broken coal and the air of the mine atmosphere. Despite modern methods and means of dust suppression and dust collection, it has not yet been possible to achieve complete neutralization of dust and gas-air mixtures in the atmosphere of mine workings. The negative effects of dust and gas-air mixtures can manifest themselves in different ways. On the one hand, deposits of coal dust in the worked-out spaces, under certain conditions, form foci of spontaneous combustion, which are the causes of endogenous fires. On the other hand, dust and gas-air mixtures are predisposed to ignition from external sources or to spontaneous ignition followed by combustion in the form of deflagration, which, under certain conditions, turns into detonation, spreading in the atmosphere of mine workings at supersonic speed. This article considers a nonstationary one-dimensional problem of selfignition of dust and gas-air mixtures in the air flows of mine workings. The temperature and the period of spontaneous ignition of dust-gas-air mixtures are found based on the solution of this problem, expressed numerically using the Geer method. An analysis of the mixture self-ignition process is performed and some patterns of the influence of the parameters of mixtures on the period of their self-ignition are revealed.

К особенностям проветривания урановых рудников

The systems of ventilation of radioactive deposits require special measures to minimize the impact of radon on miners. During the production of uranium ores, the working conditions of miners are determined by the content of metal in the broken ore, the intensity of radon emission, and the ventilation quality; therefore, the issues of mine atmosphere quality management become the top of the agenda. The patterns of gas interaction are found by modeling, with the determination of values of leaks through the exhaust space. The depth of regulation of air supply to the shaft bottom is determined as a function of regulation on the outgoing jet, the regime of airflow through the exhaust space, and the leak coefficient. A model of airflow in the direction of the shaft bottom has been compiled with the variables of the movement of ventilation jets. The pattern of airflow movement depending on the amount of air and the dimensions of the collapse area has been obtained. The mechanism to reduce contamination by using gas drainage through the collapsed wall has been identified. The recommendation on airing the mine workings with turbulent jets at a turbulent, laminar, and transient regime has been provided. A method to manage the atmosphere in the mine by adjusting the regime of leak movement through the mine working spaces has been recommended. The possibility of providing a mine with the required air by rationalizing the aerodynamic connection of mining operations with the surface has been substantiated. A practical issue of the airing of a section of an operating mine has been resolved as an example. It has been demonstrated that the substantiation of the possible use of isolated ventilation workings to release the contaminated air ensures cost savings due to the dismissal of a part of ventilation mine workings while ensuring the safety of miners. It has been proved that the possibilities of the injection method of ventilation increase when using an auxiliary drainage system.

Проведение исследований по обоснованию возможности последовательного проветривания технологических объектов на угольных шахтах АО УД "АрселорМиттал Темиртау"

The purpose of the work is to substantiate the possibility of sequential ventilation of technological sites in the coal mines of JSC UD «ArcelorMittal Temirtau». These objects of research are equipped with automated systems for monitoring the mine atmosphere (ASKRA) and systems for dispatching control and management of mining enterprises (ASKU). The developed preliminary measures allowed for a systematic and comprehensive approach to the implementation of the complex of studies carried out. The carried out research allowed specialists to process a significant amount of information on the state of the gas and dust situation at the studied technological objects. The results obtained will allow specialists to confirm the safety of work during sequential ventilation of technological sites of coal mines of JSC CD «ArcelorMittal Temirtau», determining additional conditions and a set of measures for trouble-free operation. The findings will serve as the basis for preparing proposals for amending the requirements of paragraph 153 of the «Industrial Safety Rules for Hazardous Industrial Sites in Coal Mines».

Studies of methane inflow from longwall floor into the mine atmosphere

Studies of methane inflow from longwall floor into the mine atmosphere

Methodological approach to determining the area of air recycling on metro lines with double track tunnels

The article discusses the issues of operating existing metro lines with double-track tunnels. Significant differences between average annual, average monthly and extreme values of outdoor air temperature affecting the thermodynamic and thermophysical parameters of the mine atmosphere of subway tunnels, both in Russia and abroad, are analyzed. The results of a comprehensive analysis of the conditions that determine the temperature regime of the lines of double-track tunnels are presented. Air recirculation in the tunnels has been determined considering climatic conditions. Engineering and technical calculations have been carried out in metro tunnels when the seasonal periods of their operation change. Each of these periods is characterized by its own temperature, for example, for the winter period these are: average winter temperatures, temperatures of the coldest month, the coldest five-day period. The obtained results of the research work will make it possible to select the amount of air for each specific variant of the year, which will ensure, during the operation of this kind of metro lines, the standard thermodynamic parameters of the air environment, both in underground stations and in metro tunnels, and possibly lead to a positive economic effect.

Forecast of the Maximum Methane Concentration in the Longwall Outlet and in the Ventilation Roadway. Case Study

Abstract The mining process of the coal seam wall is accompanied by the release of methane into the mine atmosphere. This process is highly variable and depends on the methane content in the seam and the methane saturation of the rocks surrounding the seam. This is the specificity of the Polish hard coal mining industry. In the article, prognostic formulas for the maximum methane concentration at the outlet of the longwall ventilation gallery were developed. In the presented article, these formulas were used to predict methane concentration at the longwall outlet and in the ventilation gallery at a distance of up to 10 m in front of the longwall. In order to assess the accuracy of the forecasts, their results were compared with the forecast at the exit of the ventilation roadway. The obtained results are so accurate that it is worth repeating this type of check also using measurements in other longwalls. It will allow to reduce the risk of methane explosion during operation.

Influence of initiation conditions of methane-air mixture on the explosion parameters in the degasation pipeline

Purpose. Increasing the safety of personnel at underground works in case of the threat of gas explosions, including explosion of degassing pipelines by taking into account the influence of the place of initiation of the explosion and the mode of combustion when calculating the parameters of the explosion. Mathematical modeling of the process of ignition and combustion of the methane-air mixture in the degassing pipeline. Research methods. nalysis and generalization of theoretical studies, numerical simulation of gas-dynamic detonation combustion of a gas-air mixture, including a model of chemical combustion kinetics, which, on the whole, allows one to trace the dynamics of formation of shock air waves in conditions of mine workings. Mathematic processing of the results of the experiment by the method of least squares. When solving the nonlinear regression equations, linearization was used by the method of logarithm. Results. It is established that the combustion dynamics of the gas-air mixture has a decisive influence on the formation of UVB: in the deflagration combustion mode of the gas-air mixture, with the initiation at the edge of the cloud, the length of the blast wave is increased 3.6 times in the direction opposite to combustion, and the wave amplitude by 10% spread of flame. In the detonation mode, the effect of a directed explosion is observed, in which the amplitude of the shock air wave is opposite to the motion of the detonation wave 5 times less than in the direct shock air wave. The model of an instantaneous volumetric explosion, in comparison with combustion models, yields an underestimated amplitude value. Scientific novelty. As a result of numerical modeling of the ignition and combustion of the sealed section of the mine atmosphere, regularities in the formation and propagation of shock air waves, the dependence of their parameters on the combustion regime and the location of the initiation of the gas-air mixture were obtained. Practical value. The conducted research allows to improve the method of calculating the resistance of degassing pipelines and their elements to explosive load.

Минимизация опасности металлизированных шахтных стоков

Increase in ore production volumes and the use of large-sized equipment contribute to the loss of ores during mining, which gives rise to the phenomenon of natural leaching. On the example of deposits of the Sadon ore cluster, the hazard of metallized mine effluents for living matter and humans is shown. Of the relatively young methods of mine water purification, the most promising is the combination of electrochemical softening of mine effluents with electrodialysis desalination and concentration. The improvement of environmental protection technologies is developing on the basis of the managed disposal of mining and processing waste as a generator of natural leaching. The results are presented related to the experimental study of the parameters of metals extraction from the mine effluents by electrodialysis desalination with simultaneous concentration. The mechanism is formulated related to the development of oxidative processes of sulfide minerals in the presence of carbon dioxide of the mine atmosphere with the occurrence of electrochemical bonds between the crystals and mineral grains. The process of electromembrane treatment of metal-containing wastes is detailed. It is shown that during the electrochemical decomposition of salt systems, associated commercial products are formed. The dynamics of pollution of the Ardon river washing the Sadon deposit is given. The chemical processes of leaching of lost ores are described. An installation for electrochemical wastewater treatment is recommended, and a quantitative assessment of its efficiency is given. It is noted that the processes of electrochemical wastewater treatment are adequate, described by linear graphs and subject to correction. It is shown that the drains of mines are hazardous for living matter. It is indicated that the improvement of environmental protection technologies will be developed in the direction of waste disposal of mining and processing. The general principle of mine water hazard reduction is a combination of electrochemical softening with electrodialysis desalination and concentration.

Measurement and modeling of water vapor sorption on nano-sized coal particulates and its implication on its transport and deposition in the environment

One major cyclical environmental parameter within the underground mine space is the fluctuation of relative humidity, which varies daily and seasonally. Therefore, moisture and dust particle interactions are inevitable and indirectly control dust transport and fate. After being released into the environment, the coal dust particles stay there for a long period depending upon several parameters such as particle size, specific gravity, ventilation etc. Due to their smaller size, nano-sized coal dust particles could remain in the mine environment indefinitely while interacting with it. Correspondingly the primary characteristic of nano-sized coal dust particles could get modified. The nano-sized coal dust samples were prepared in the lab and characterized using different techniques. The prepared samples were allowed to interact with moisture using the dynamic vapor sorption technique. It was found that the lignite coal dust particles could adsorb up to 10 times more water vapor than the bituminous coal dusts. Oxygen content is one of the primary factors in deciding the total effective moisture adsorption in the nano-sized coal dust, with moisture adsorption proportional to the oxygen content of the coal. This means that lignite coal dust is more hygroscopic when compared to bituminous coal dust. GAB and Freundlich's models perform well for water uptake modeling. Because of interaction with atmospheric moisture, particularly swelling, adsorption, moisture retention, and particle size changes, such interactions will significantly change the physical characteristics of nano-sized coal dust. This will affect the transport and deposition behavior of coal dust in the mine atmosphere.

Закономерности аэрогазодинамических процессов при подземных пожарах

The issue was studied related to increasing occupational safety in underground mining of the mineral raw materials. The forms of the goaf are classified. An algorithm was developed for air distribution in emergency ventilation mode, including when the main ventilation fan is turned on after an emergency stop. The possibilities and mechanism of the fan influence at the stages of ventilation in emergency conditions was clarified. An algorithm is proposed for calculating ventilation parameters in case of emergency reversion of the ventilation jet. The methods for calculating the amount of air and the inertia of the ventilation system are presented at normal ventilation and during the transition from normal ventilation to emergency. The problem of air distribution during the transition period is solved with the representation of the air branch in the form of a node with multidirectional and limited movement of air jets. The methodology for predicting hazardous working situations is detailed based on the laws of diffusion transfer of gas components of the mine atmosphere. A new method of experimental determination of elements of the transitional period of ventilation was developed. The results are given concerning the study of the influence of the goaf on the efficiency of the fans operation and the duration of the transition process after reversing the fan in an emergency. A new idea is substantiated related to the gas situation as a fragment of a ventilation network with distributed sources of oxygen absorption and gas release. The structure of the matrix of the state of mine workings in an emergency was proposed. An algorithm for calculating ventilation modes for optimizing emergency response plans is formulated. It is shown that the establishment of the regularity of the processes of gas transfer during emergency ventilation mode allows to increase the efficiency of measures to ensure occupational safety in underground mining.

Напряженное состояние в шахтной перемычке, обусловленное давлением на фронте ударной волны

The development of coal deposits is accompanied by the release of methane from the destroyed coal and the formation of dust-gas-air mixtures predisposed to chemical reaction, manifested in the form of deflagration or detonation, as a result of which the shock waves are formed in the mine atmosphere, which in the conditions of coal mines can lead to catastrophic consequences. In order to prevent the propagation of shock waves and thermodynamic processes in the mine atmosphere at coal mines, various designs of shaft jumpers are used, for which the technological construction schemes were developed. However, scientifically substantiated and reliable methods for calculating jumpers have not yet been created. To date, the design parameters of the jumpers, primarily their thickness, are assigned on the basis of rather primitive strength calculations, which are based on the design scheme of a thin plate, the thickness of which, by definition, is significantly less than its other dimensions. The thickness of the shaft jumper is comparable to the dimensions of its cross section, which fundamentally contradicts the main requirement for the design scheme of a thin plate. In this regard, it can be said that the existing methods for determining the parameters of the jumpers based on the calculation scheme of a thin plate do not correspond to the actual operating conditions of the jumpers, therefore, they cannot be recommended to ensure the reliability of the shaft jumpers. This article discusses the stress-strain state in a shaft jumper with a circular cross section based on the classical theory of elasticity. The paper formulates a boundary value problem of the stress-strain state of a jumper in a linear formulation, constructs its solution, as a result of which the stress components in the jumper under the action of static pressure caused by a shock wave are found.

ФИЗИЧЕСКИЕ ПРИНЦИПЫ И МАТЕМАТИЧЕСКОЕ ОПИСАНИЕ ФОРМИРОВАНИЯ ПОЛЕЙ СКОРОСТИ ВОЗДУХА И КОНЦЕНТРАЦИЙ ГАЗОВЫХ ПРИМЕСЕЙ В ГОРНЫХ ВЫРАБОТКАХ УГОЛЬНЫХ ШАХТ

The air composition of the mine atmosphere in coal mines; Safety Rules regulate heat-humidity and speed conditions created by the ventilation system. At the same time, physic-chemical, aero-gas-dynamic and thermos-physical processes occur, which affect the level of aerological safety. A system of equations recommended that allows one to calculate longitudinal air velocity profiles at any point in the mine ventilation network. These recommended describing the transfer of gas impurities in the mine atmosphere by the equation of turbulent-convective diffusion.

Numerical analysis of the possibility of noxious gases infiltration into a shelter located in a gas-bearing coal-rock mass

Shelters in coal mines are used to protect miners during accidents associated with gassing of roadways, fires, explosions of methane-air mixture. Supporting of the shelter must provide the necessary level of tightness to prevent the penetration of noxious gases from the mine atmosphere or gas-bearing rocks. The purpose of this work is to study the possibility of noxious gases penetration into a shelter in case of its sealing failure for the early detection of weak constructional elements and to ensure safe conditions for people in the shelter during accidents. To achieve the goal, methods of numerical simulation of time-dependent processes of elastic-plastic deformation and gas filtration were used. A coal-rock mass with a roadway and an adjacent shelter with typical supporting elements were considered at a depth of 400 m and 1000 m. The study of the stress state of the shelter support showed that under the considered conditions, in the case of a relatively small depth, hard steel and concrete constructional elements withstand the load without loss of their stability. With an increase in the depth of the shelter location, inelastic deformation of the concrete barrier between the shelter and the roadway occurs on a small area. The probable destruction of this zone will not lead to a violation of the entire barrier integrity, which makes it impossible to start mass exchange processes between clean air in the shelter and harmful combustion products in the roadway. The roof and walls of the shelter, covered with reinforced concrete and sealed, remain practically impermeable from the next day after their construction in both the first and second cases. But later, in the lower left corner of the shelter at a depth of 1000 m, methane from the coal seam begins infiltrating through the unsupported and unsealed floor. The developed numerical model can be used with other basic data on mining and geological conditions to identify constructional elements of a shelter, which lose stability during operation and threaten the shelter's tightness. Timely strengthening of such weak elements will prevent the danger of noxious gases infiltrating into the shelter. Keywords: time-dependent rock deformation, shelter, sealing failure, gas filtration, numerical simulation.

ИССЛЕДОВАНИЕ СОРБЦИОННЫХ СВОЙСТВ СОЛЕЙ НА ПРИМЕРЕ ГАЗОВ, СОДЕРЖАЩИХСЯ В АТМОСФЕРЕ КАЛИЙНЫХ РУДНИКОВ

Currently, one of the important tasks of mining enterprises is the development of new ways to improve the energy efficiency of ventilation systems in underground mines. One of these measures is the introduction of ventilation schemes with partial reuse of outgoing air to ventilate subsequent work areas. The safety of the proposed measure can be substantiated by a comprehensive study of the properties of the potash array. One of these properties is the ability of sylvinite to actively absorb harmful gaseous impurities present in the outgoing air stream from the mine atmosphere. The paper presents the scientific substantiation of the sorption of gases by the potash massif, as well as a number of natural and laboratory studies.

Analysis of Forecasted Methane Concentration at the Top Gate of a Wall Ventilated by Means of the “U” System. Case Study

Abstract The release of methane into the mine atmosphere poses a threat to the miners. Methane is an explosive gas at concentrations of 5-15% in air by volume and throughout the history of coal mining has been the cause of devastating explosions in mines around the world. For these reasons, in methane coal mines, the concentration of methane emitted from the coal face and the entire mine is controlled by means of a well-designed ventilation system, a system controlling the concentration of methane in the mine atmosphere and a system for methane drainage of the rock mass and goafs. The presented article concerns the forecast of the average concentration of methane on a given day, in the places of sensors located in the longwall roadways of discharge air exhausted from the longwall: up to 10 m in front of the wall and at the outlet of the roadway. Both forecasts were made using the prognostic equations on the basis of measurement data concerning the ventilation roadways of one of the longwalls at JSW SA.