Analysis of Methane Hazard Conditions in Mine Headings

One of the most dangerous and the most common hazards in coal mines is methane hazard. This threat is associated with inflammation and/or explosion of methane in the mixture of air. Analysis of the scale of methane hazard allows the selection of such a longwall ventilation system operating, which provides the requisite provisions of the chemical composition of the mine atmosphere, and the required efficiency of methane drainage. The article presents the results of numerical analysis of the flow of the mixture stream of air and methane by the layout of workings of one of the mines. The aim of this study was to analyse the workings and the designation of zones of the ventilation system in question, where there may be dangerous, explosive concentrations of methane. The results are important when taking preventive actions aimed at reducing methane emissions to the external environment in the process of methane drainage

Applying Cfd Model Studies to Determine Zones at Risk of Methane Explosion and Spontaneous Combustion of Coal in Goaves

Underground mining operations are subject to a number of natural hazards. Events resulting from these hazards are difficult to predict, and if they occur, they disrupt the entire mining process and pose a great danger to the crew. Some of the most dangerous include ventilation hazards involving methane explosions and fires caused by the spontaneous combustion of coal. The complex state of the underground environment means that these hazards oftentimes occur simultaneously, making mining conditions even worse. The following paper addresses this issue by developing the methodology for determining areas endangered by methane explosions and spontaneous coal combustion in goaves. The reference to goaves results from the fact that this particular area is most frequently affected by spontaneous coal combustion and the accumulation of dangerous amounts of methane. The developed methodology was based on model tests with the use of the CFD method and data necessary to develop a numerical model. The research encompassed a real longwall in one of the hard coal mines, ventilated with the Y system during its exploitation, which is beneficial in the case of the methane hazard but worsens the safety in terms of the self-ignition of coal. As a result of the conducted research, for the exploitation conditions, dangerous zones were specified due to the potential possibility of methane explosion and self-heating of coal. The basis for determining dangerous zones was the criteria of occurrence of the examined phenomena. In this study, the zones were identified for each of the investigated hazards separately and for their simultaneous occurrence. Thus, the aim of the study, which involved the determination of potentially hazardous zones by applying modern methods of modelling in the mining area, was achieved. The results are an immensely important source of information for activities aimed at improving safety in the studied area in relation to the studied threats

Analysis of Gas and Dust Emissions From the Mining and Quarrying Sector in the European Union Countries

Despite the ongoing changes in the energy and economic structure of the European Union countries, mineral and energy resources such as hard coal, brown coal, natural gas, copper ores, zinc ores and many other minerals continue to be extracted. Each year, the mining and extraction sector emits thousands of tons of harmful substances into the atmosphere, in the form of greenhouse and other air-polluting gases, as well as harmful dusts. These substances include, amongst others, carbon dioxide, methane, carbon monoxide, as well as PM2.5 and PM10. The European Union climate policy clearly recommends that the exploitation of mineral resources be carried out in full respect of the principles of their rational, economical and environmentally neutral acquisition, which is confirmed by the promoted strategy of sustainable development economy. Therefore, this means the necessity to undertake actions aimed at limiting the emission of greenhouse gases and air pollutants into the atmosphere. To assess the actions taken by the European Union countries to date with respect to limiting those emissions, a comparative analysis was carried out for the particular countries. This analysis encompassed the emission of harmful substances from the mining and quarrying sector by the European Union countries in the years 2008 and 2017. The purpose of the analysis was to show the diversity of those countries in terms of the emission of harmful gases and dusts, as well as to divide them into similar groups. Such a division paves the way for developing a common climate policy and exchanging experiences between the countries from the particular groups. The European Union countries were divided into similar groups using the k-means grouping method. Comparison was also made for the emissions of the substances under analysis for the particular countries over the research years. The results obtained unequivocally demonstrate that this emission has been limited in the European Union, but there are countries where the emission of certain substances has increased

The Influence of the Permeability of the Fractures Zone Around the Heading on the Concentration and Distribution of Methane

One of the main problems related to the excavation of dog headings in coal beds is the emission of methane during this process. To prevent the occurrence of dangerous concentration levels of this gas, it is necessary to use an appropriate ventilation system. The operation effectiveness of such a system depends on a number of mining, geological, technical and organizational factors. One of them includes the size and permeability of the fractures zone formed around the excavated dog heading. The primary objective of the paper is to determine the influence of this zone on the ventilation parameters, including the concentration and distribution of methane in the excavated dog heading. In order to achieve the assumed objective, multivariate model-based tests were carried out, which reproduce a real-world dog heading. Literature data and test results in actual conditions were used to determine the size and permeability of the fractures zone around the excavated heading. These data served as the basis to develop a model of the region under analysis and adopt boundary conditions. The analyses were carried out for four permeability values of the fractures zone and for two volumetric flow rates of the air stream supplied to the heading. The results were used to determine the influence of the fractures zone on the distribution and concentration of methane in the heading under analysis. The model-based tests were performed using ANSYS Fluent software. The idea to take into account the fractures zone around the heading represents a new approach to the analysis of ventilation parameters in underground mine headings. The results clearly indicate that this zone affects the ventilation parameters in the heading, including the distribution and concentration of methane. The knowledge obtained from the tests should be used to optimize the ventilation process of dog headings. All authors have read and agreed to the published version of the manuscript

NUMERICAL ANALYSIS OF INFLUENCE OF EXOGENOUS FIRE IN DOG HEADING ON PARAMETERS OF THE AIR STREAM FLOWING THROUGH THIS HEADING

Flow of ventilation air stream through the dog heading with a fire centre is the flow with complex character, during which as a result of emission of fire gases into the mining atmosphere, there occur to disturbances of its flow. In the paper there is presented a numerical analysis of an influence of exogenous fire in a dog heading, on the parameters of the ventilation air stream flowing through this heading. Modeling tests were carried out with a use of ANSYS software, basing on the Finite Volume Method. For the made assumptions, there were determined physical parameters of air stream flowing through the heading with a fire centre, and also changes in mass fraction of gases in this stream during its flow through the analyzed heading: oxygen, carbon monoxide and carbon dioxide. As a result of performed analysis over the fire centre, the local increase of velocity and temperature and violent decrease of static pressure were recorded. Model of heading presented in the paper gives possibilities for development, and then the analysis of more complicated problems in a range of ventilation of mining headings

Analysis of the Time of Crew Evacuation from the Hazardous Area of Mining Exploitation Using Numerical Simulation

Hard coal mines are vulnerable to a series of hazards that affect the safety and effectiveness of mining production. One of such hazards is the risk of underground fires. As the exogenous underground fires appear suddenly and have a highly dynamic course, it is very often necessary to quickly evacuate the crew from the danger area. The time needed to evacuate the crew from the danger area is most commonly determined by means of analytical methods, which provide a very general calculation. Therefore, it becomes necessary to also make use of other methods and tools for determining this time. Undoubtedly, such characteristics are offered by modern calculation methods based on the artificial intelligence (AI) algorithm and characterised by high accuracy. The paper presents a sample application of such a method for evacuating a 20-member crew from the heading under threat. In order to determine the evacuation time for those individuals, a calculation model was built for the total length of the escape routes equal to 900 m. The results revealed that the total evacuation time for workers moving with the speed corresponding to the movement speed in a heading filled with smoke (with considerably reduced visibility) will amount to approx. 21 minutes. The results obtained may constitute an essential source of information for service teams responsible for ensuring the operational safety in mine headings. At the same time, the model developed allows for broader application to the estimation of crew evacuation times from danger areas

THE PRELIMINARY ANALYSIS OF DISTRIBUTION OF THE VELOCITY FIELD AND AIR PRESSURE FLOWING THROUGHT THE MINING HEADINGS WITH DIFFERENT GEOMETRY OF CROSS‐SECTION

The basic meaning for the security of persons working in underground mining heading heir ventilation of headings. Providing the fresh air into the active mining heading is a fundamental task of ventilation service in the mine. Very significant impact on the efficiency of the ventilation process has the physical parameters of supplied airflow, such as its amount, speed and pressure. These parameters can be determined based on the "in situ" tests or modeling tests. Carrying out the tests in underground conditions is very expensive and not always available due to exploitation. As an alternative, in such cases the modeling tests can be used, which give more possibilities of analysis the impact of differentials factors on the studied parameters. In the paper there is presented results of modeling of airflow in mining heading, obtained basing on the numerical simulations with use of finite volume method in ANSYS Fluent software. The physical models of headings were prepared basing on the real cross sections of the dog headings. To find the solution of the mathematical model, the k‐ε turbulence model was used

Using MCDM Methods to Assess the Extent to which the European Union Countries Use Renewable Energy

Energy security is one of the basic tasks carried out by individual countries. It is of great socio-economic and political importance and constitutes the basis for independent development of both economies and groups of countries. Access to adequate resources of affordable and environmentally neutral energy in the production process is the basis for sustainable energy development. Therefore, an important element of sustainable energy is its environmental neutrality. Currently, this condition is fulfilled to the greatest extent by energy produced from renewable energy sources (RES). Renewable energy development is taking place all over the world, but the European Union (EU) is a definite leader. In its energy policy, the importance and role of RES in the energy production structure has been growing systematically for many years. Introduced regulations and energy strategies caused member states to take extensive actions to achieve the set targets for RES. However, the large diversity of the EU countries makes this process occur with different intensity. Thus, it was justified to conduct research to assess the level of renewable energy use in the EU countries in a 15-year perspective (2004-2019). The research was based on a set of 4 indicators characterizing the use of renewable energy in the EU countries by means of the WASPAS method (from the group of MCDM methods). The results showed that a high level of RES use in the whole studied period was found in Sweden, Austria, Latvia and Finland, and a low level, for 2004, was found in Cyprus, Luxembourg and Malta, and for 2019 – in Luxembourg and Malta

Analysis of the similarity of hard coal mines in terms of the number of dangerous incidents caused by the activation of natural hazards

Hard coal mines and mining enterprises involved in hard coal exploitation in the area of the Upper Silesian Coal Basin (Górnośląskie Zagłębie Węglowe) are characterised by the presence of natural hazards typical of this type of exploitation. These hazards include the risks related to methane, coal dust explosion, endogenous fires, as well as rock burst and caving of roof rocks. The article presents the results of a taxonomic analysis aimed at determining the similarity of hard coal mines and mining enterprises in Poland in terms of the dangerous incidents caused by the risks related to methane, coal dust explosion, endogenous fires, as well as rock burst and caving of roof rocks. The analysis was carried out for the 2008-2018 data and encompassed a total of 26 hard coal mines and mining enterprises located in the Upper Silesian Coal Basin. The analysis was performed using the k-means method of non-hierarchical clustering. The main objective of the article was to determine homogenous groups (clusters) of mines exhibiting the greatest similarity in terms of dangerous incidents caused by the activation of natural hazards in the years 2008-2018. These data can be successfully used for the development of preventive measures and risk analyses for these enterprises

Analysis of Similarities Between the European Union Countries in Terms of Sustainable Energy and Climate Development

Energy and climate issues are an essential part of the sustainable development process of the EU countries. They are also one of the primary objectives of international policy, as evidenced by their inclusion in Agenda 2030, adopted by the UN in 2015 among the Sustainable Development Goals. The implementation of these goals is also taking place in the EU countries. Although climate protection and energy transition activities have been undertaken in the EU for years, individual countries significantly vary in this regard. The aim of the research, the results of which are presented in this paper, was to analyze similarities between the EU countries in terms of sustainable energy and climate development. The analysis was conducted for all EU countries, based on 14 indicators characterizing energy and climate sustainability, in energy, climate, social and economic dimensions. Kohonen’s artificial neural networks were used for analysis. The research was conducted for data from the period between 2009-2018. The results showed that in the studied period (10 years), significant differences were found between the EU countries. A high level of energy and climate development was reported for Sweden, Denmark, Austria and France, among other states, and a low level for e.g., the Czech Republic, Poland and Bulgaria