The mining methods are classified as the methods of data analysis and the knowledge acquisition and they are derived from the methods of "Knowledge Discovery". Within the scope of these methods, there are two main variants associated with a form of data,i.e.: "data" and "text mining". The author of the paper tries to find an answer to a question about helpfulness and usefulness of these methods for the purpose of knowledge acquisition in the construction industry. The very process of knowledge acquisition is essential in terms of the systems and tools operating based on knowledge. Nowadays, they are the basis for the tools which support the decision-making processes. The paper presents three cases studies. The mining methods have been applied to practical problems – the selection of an adhesive mortar coupled with alternative solutions, analysis of residential real estate locations under construction by a developer company as well as support of technical management of a building facility with a large floor area.
Coal mining activities carried out for 200 years in Upper Silesia have had a negative effect on buildings. T his impact is in all cases related with continuous deformations of the surface and in certain cases with discontinuous deformations (mostly cave-ins), changes in water relations and mining tremors. T he paper presents an evaluation of the impact of a mining activity on a building situated in the Upper Silesian Coal Basin. T he building was affected by continuous deformations and mining tremors. Calculations were made of the values of deformation rates by means of Budryk–Knothe’s theory, which were partly verified on the basis of the results from geodetic measurements. An analysis of the velocity and acceleration of basement vibrations caused by mining-induced tremors was also conducted. T he conclusions included a high consistency between the results obtained on the basis of calculations and the values obtained by means of PGA and PGV measurements. In the case of tremors with the highest energy in the hipocentrum, there an empirical formula allowing for calculation of PGA value in given geological and mining conditions was also proposed. T he application range of the formula mentioned above is obviously limited only to the conditions in consideration. The presented conclusions indicate that at present, sufficiently precise methods, allowing for calculations for practical purposes, not only of deformation indices’ values, but also of PGV and PGA values, presently exist.
Mining-induced seismicity, particularly high-energy seismic events, is a major factor giving rise to dynamic phenomena within the rock strata. Rockbursts and stress relief events produce the most serious consequences in underground mines, are most difficult to predict and tend to interact with other mining hazards, thus making control measures difficult to implement. In the context of steadily increasing mining depth within copper mines in the Legnica-Głogów Copper Belt Area (Poland) alongside the gradually decreasing effective mining thickness, a study of the causes and specificity of mining-induced seismicity in specific geological and mining settings may improve the effectiveness of the prevention and control measures taken to limit the negative impacts of rockbursts in underground mine workings, thus ensuring safe working conditions for miners. This study investigates the presumed relationship between the mined ore deposit thickness and fundamental parameters of mining-induced seismicity, with the main focus on the actual locations of their epicenters with respect to the working face in commonly used room-and-pillar systems. Data recalled in this study was supplied by the O/ZG Rudna geophysics station. Based on information about the actual ore deposit thickness in particular sections of the mines (Rudna Główna, Rudna Północna, Rudna Zachodnia) and recent reports on seismic activity in this area, three panels were selected for further studies (each in different mine region), where the ore deposit thickness was varied (panel G-7/5 – Rudna Główna, panel XX/1 – Rudna Północna, panel XIX/1 – Rudna Zachodnia). Data from seismic activity reports in those regions was used for energetic and quantitative analysis of seismic events in the context of the epicenter location with respect to the selected mining system components: undisturbed strata, working face and abandoned excavations. In consideration of the available rockburst control methods and preventive measures, all events (above 1 × 103 J) registered in the database were analysed to infer about the global rockburst hazard level in the panel and phenomena induced (provoked) by blasting were considered in order to evaluate the effectiveness of the implemented control measures.
The current rockburst hazard conditions in the copper mines are the consequence of mining-induced seismicity of the rock strata whilst the majority of registered rockbursts have been caused by high-energy seismic events. T he analysis of seismic activity in recent years indicates that the region of the Rudna mine is the region of the highest seismic activity. This paper is an attempt at evaluating the seismicity levels in the Rudna mine in the period from 2006-2015, within the entire mine and in its particular sections. Key parameters of seismic activity include the number of registered seismic events, total energy emission levels, and a unit energy factor. The variability of Gutenberg -Richter (GR) parameters are analyzed and the epicenters’ locations are investigated with respect to the stope position. T he distinction is made between low-energy (103 ≤ As < 105 J) and high-energy (As ≥ 105J) seismic events ahead of the stope, in the opening-up cross-throughs and in the gob areas. It appears that the risk level of a high-energy event occurrence in the R udna mine has not changed in recent years and has remained on a high level whilst the differences in seismic activity, in particular mine sections, are attributed to the varied extraction height and varied thickness of rockburst-prone carbonate layers in the roof of the copper ore deposit. The analysis of the epicenters’ locations with respect to the stope reveals that no matter what the seismic energy levels, the largest number of rockbursts are registered in the opening-up cross-through zone. Low-energy tremors are mostly located in the gob areas, high-energy events occur mostly ahead of the stope. T hus, the evaluation of the seismicity conditions in the Rudna mine seems to positively verify the relationship between the number of registered events and the levels of generated seismic energy, taking the local geological and mining conditions and the specificity of the room and pillar mining method into account.
Since the 1970s, the Legnica-Głogów Copper District has an area of intensive mining of copper. Mining activities resulted in the appearance of induced seismic activity. This situation caused the necessity of setting an underground seismological network. In the mid-1990s, due to the great damage of objects on the surface caused by the ground vibrations due to mining tremors, a surface strong motion seismic network equipped with accelerometers was created. They monitor the vibration levels of both the land and the buildings themselves. This contributed to a better knowledge of the nature of ground vibration and the resistance of objects. In recent years, anthropogenic threats, which include seismicity induced by mining activities, are arousing more and more interest. To be able to develop test methods for seismic source physics, the analysis of the impact of vibrations on the surface and the seismic hazard, network measurement should also be developed and modernized. In the years 2014–2015, the IS-EPOS “Digital research space of induced seismicity for EPOS purposes” project, extended the LUMINEOS modern seismological network presently consisting of 15 seismometers and 10 accelerometers, with the possibility of additional further expansion. The data obtained from the LUMINEOS network complements the existing underground mining network and surface strong motion network. This allows for an advanced seismic analysis.
The article is an analysis of the content of the reports of the national mining companies and vertically integrated operators in the energy value chain, in light of the guidelines of global standards of corporate social responsibility (CSR – Corporate Social Responsibility). A verification of the review of the literature and reports of selected companies in terms of non-financial data publication was conducted, that is information which is based on ES(G) (E – Environment; S – Social; G – Governance), especially considering all environmental and social aspects. It was also indicated which selected mining companies prepare integrated reports (financial and non-financial data), in line with the GRI (Global Report Initiative) guidelines and G4 Mining and Metals – the document contains a set of disclosures for use by all organizations in the Mining and Metals sector. According to the author, universal access to non-financial data expanding the circle of stakeholders and can mitigate the negative public opinion towards the mining industry. Integrated reporting is a new experience for Polish mining companies and vertically integrated energy groups reporting sent to various stakeholder groups, using the GRI guidelines. The analysis showed that only two domestic companies out of the 10, i.e. LW Bogdanka S.A. and KGHM Polska Miedź S.A. submitted the report for 2015, based on the indices dedicated to the, „mining and metals” Industry. The selection of companies has been dictated by their significant share in the mining industry in Poland. The article indicates skipping important aspects of the business activities of mining and vertically integrated enterprises, which should be a necessary part of the reports (due to the obvious impact of mining on the environment and society). It refers to the GRI G4 Mining and Metals guidelines as the indicators which are additional tools to reporting on sustainable development. The purpose of this article is to point out important aspects of the mining companies and vertically integrated enterprises which are omitted and, in the opinion of the author, should be the components of those reports.
For years, the Polish hard coal mining has been struggling with the problem of fire hazards in areas with coal residue, mainly in goafs. Currently, a common method of limiting this hazard is the fire prevention involving use of fine-grained hydromixtures based on power generation waste, mainly fly ashes. The hydromixture is introduced into the caving zone created by the advancement of exploitation face and its task is to fill in voids, limiting the possibility of access to the mine air oxygen to a minimum. The first part of the article presents theoretical fundamentals of determining the parameters of gravitational hydraulic transport of water and ash hydromixtures used in the mining pipeline systems. Each hydromixture produced based on fine-grained wastes is characterized by specified rheological parameters that have a direct impact on the future flow parameters of a given pipeline system. Additionally, the gravitational character of the hydraulic transport generates certain limitations concerning the so-called correct hydraulic profile of the system in relation to the applied hydromixture characterized by required rheological parameters that should ensure safe flow at a correct efficiency. This paper shows an example of optimisation of the composition of a selected fly ash-water hydromixture in relation to its capacity for hydrotransport in gravity pipeline installations, as well as the amount of excess water that will always drain from the location of feeding the hydromixture to the underground workings.
The problem of deposit protection and the process of liquidation of mining plants does not find effective solutions in the national law. Nevertheless, this is a very up-to-date issue. This situation prompted the authors of the article to once again analyze these issues. The number of abandoned exploitation sites which were published in the Polish Geological Institute reports should affect the entire licensing system and the state’s raw material policy. As a good host of raw materials, which we have been given by Earth Mother, we cannot allow that the mining licensing system, the liquidation procedures of mining plants without due diligence, result in the lack of protection of these deposits. The rational raw material economy and the ability to exploit it for the future generations, while failing to effectively enforce the site liquidation process makes it necessary to take actions leading to not blocking the mineral deposits in this way. The analysis shows what appropriate actions should be taken. The authors have thoroughly investigated the legal regulations over the past century, compiling them with the current legislation, and pointing out the weaknesses of the system in the field of deposits protection, particularly in the part of the unexploited deposits. Criticism covered both the statutory regulations – Geological and mining law as well as executive acts in the field of deposit protection. A separate analysis was subjected to the procedure of liquidation of the mining plants in the aspect of deposits protection, for mining plants operating on the basis of the Province Marshal’s licenses. The process presented in the flowchart layout clearly shows the weak points of the currently operating system.
The article discusses problems related to rules and regulations determining compensations for the mining usufruct of mineral deposits covered by the so called “state mining ownership”. Specific acts of law framing agreements on mining usufruct between government and mining enterprises were analyzed. Rules and algorithms applied to calculate an appropriate compensation are evaluated leading to several conclusions, including the one about lack of a direct legal grounding for them. Such a situation creates disputes and may be risky for all involved. It was also indicated that, in parallel, the State lets another class of mineral deposits, namely the ones owned as a result of real estate ownership and the related Civil Code regulations confirmed by the mining law. In such cases, a mining entrepreneur gets usufruct of a real estate, but only the one with mineral rights. Subsequently a comparison of the rules and algorithms established for determining compensation for mining usufruct and for usufruct of real-estates comprising rights for mineral assets was performed. Arguments for a far going harmonization between these two were put forward. This implies that a starting point for determining any compensation has to be a valuation of a relevant mineral deposit market value as opposed to any universal, however complicated, prescribed algebraic formula. Such a process is complicated and demands competences in geology, mining and finance. Consequently, regulations set in the Polish Mineral Asset Valuation Code shall be applied to both a running a valuation process and indicating competent persons. As a result, recommendations leading to correlate rules applied in both cases are put forward including the adoption of mineral asset valuation as a fundament to determine the level of compensation for the mining usufruct. The closing section contains recommendations regarding necessary changes in the legal framework.
Coal mining is one of the most important sectors of the Polish industry. It can be said that the coal is a national raw material. This results in Poland being a pioneer in the European Union in terms of coal mining as well as its use in the production of electricity and heat. There are many companies in Poland which have been established and developed around the coal mining industry aimed at coal extracting. The operations of those companies depends on the condition of the mining companies and their cooperation with them: commercial, service and advisory, called referred to as “mining supporting companies”. The article focuses on the results of a survey carried out in mining supporting companies, such as mining machinery and equipment manufacturers, mining-related service companies and mining-related research and development institutions. The authors evaluated the relationship and dependence of those companies on the mining industry. It was assumed that the measure of the mining supporting companies condition is the overall quantity of public related payments contributed to the state budget and local budgets. In the article, the authors raised the problem of the size of losses for public finances, as a result of the significant limitations of financial flows from the mining companies. The surveyed companies are those associated with the Polish Mining Chamber of Industry and Commerce. As a result, the authors prepared conclusions regarding the dependence of the mining supporting companies on the situation of the mining subsector.
Caving in the excavation of mining galleries is a dangerous phenomenon, resulting in a threat to the health and life of humans, technological difficulties (transport, ventilation, etc.) and economic losses. Mining galleries list: design errors, runtime errors, errors and random causes among the causes of the caving occurring in recent periods in the excavation of underground coal mines. Examples in the recent period of caving in the excavation of mining galleries in coal mines indicated that one of the main causes of the situation was the loss of capacity and double timber technical wear caused by the corrosion of the profile. In practice, the caving that occur as a result of the technical wear can be divided into the breaking arc of a roof – bar, the loss of stability of one of the heading walls and a total heading collapse. On the basis of the carried out analysis of these cases, guidelines were proposed for improving the safe operation of the workings. The improvement of support stability may be achieved by applying additional supports, stabilizing the structure by bolting the support sets or by introducing a fiber-reinforced concrete coating with injection into the rock mass. Examples of caving occurring in the excavation, for which the preparatory selection of support does not match the geological-mining conditions, were also presented. The summary indicated the importance of diagnostics roadway in the safe and efficient conduct of mining that should be covered by the operational rules, and their scope and frequency should be adapted to the rank of the occurrence of hazard and support construction.
Plastic rocks can creep, therefore the knowledge of the rheological properties of the drilled formations is an important element of the drilling process and when choosing borehole designs. These properties of plastic formations also influence the way in which appropriate drilling technology and drilling mud properties are selected. The article presents the effect of basic rheological parameters of salt from the Fore-Sudetic Monocline deposit on the drilling of boreholes in the mining area of KGHM Polska Miedź, which in the future can be used as a good drilling practice to improve the safety and efficiency of drilling. The process of drilling in plastic rocks may be hindered. Salt is a plastic rock and in the analyzed rock mass it is deposited at a considerable depth. The caprock exerts big loads on it, beside the temperature in the deposit intensifies the rheological properties of the rock. The creep process causes that the borehole contracts, therefore the knowledge about the rheological properties of the drilled rock is very important for establishing the safe time in which the well may remain uncased. The paper is devoted to the influence of basic rheological parameters of salt bed in the Fore-Sudetic Monocline on the process of drilling of a borehole in the area of KGHM Polska Miedź as these data can be used in drilling practice in the future.
Exploitation of hard coal seams by roadway system is applied by two coal mines in southern Poland in Upper Silesian Basin. It is a secondary mining exploitation carries out in safety pillars of urban areas and shafts within mining areas of closed coal mines. Roadway system is the excavation process of gateways which are made in parallel order leaving coal pillars between them. An optimal width of coal pillar makes roadway stable and reduces subsidence of terrain surface. The article presents results of subsidence simulation caused by partial extraction using empirical and numerical methods on the example of one exploitation field of “Siltech” coal mine. The asymptotic state of subsidence was considered after mining ceased in the study area. In order to simulate of subsidence, numerical model of rock mass and model of Knothe-Budryk theory were calibrated. Simulation of vertical displacements in numerical method was carried out using RS3 program by Rocscience based on finite element method. The assumption was made that model of rock mass is transversely isotropic medium, in which panels were designed according to order of extraction of coal seams. The results of empirical and numerical methods were compared with measured values of subsidence at benchmarks along drawn lines (subsidence profiles).
This article presents a concept method which aids the forecasting of the reclamation cost in post- rock mining areas. The method may also prove useful in estimating the investment profitability of a mining operation at its planning stage as well as managing a potential Reserve Fund to cover future activities, such as land reclamation. The development of the method consisted in defining a set of basic/typical land reclamation directions and the typical structure of reclamation operations/works, which are based on “statistically stable” values. The estimations included the distribution of the probable cost of these works with respect to the reclamation direction and were calculated on the basis of the analyzed current price lists and historical land reclamation projects. The article proposes a method for estimating the cost structure of multi-directional projects by combining the basic directions. The changeability and predictability of various land reclamation solutions was analyzed in terms of fuzzy logic. A price list was developed, which included unit costs for separate types of reclamation works, independent of their type and scale. The assumed optimal measure involved comparing the cost of individual types of operations to the surface of the reclamation area. As an example, the method was also applied to hypothetical data from a clastic rock mine with a surface of 20 ha, and for the forest, agricultural and forest-agricultural reclamation directions. The forest-agricultural reclamation directions was presented in the proportions of 0.3:0.7.
The article contains considerations on possible actions directed at increasing productivity of hard coal mining industry. It is necessary to improve the state of the industry, and ensure its survival. Basic definitions and measures concerning productivity and management were presented to illustrate examples referring to a mining enterprise. Then, basing on organizing, one of the management functions, the issue of productivity in a mining enterprise and its influence on improving effectiveness of operational management, was analysed. An assumption was presented that solutions concerning identification of sources and volume of costs, hitherto existing in mining enterprises, ought to be complemented with the planning function following process approach. It can be the starting point for decisions of economic feasibility of given deposits, seams or parts of them, before mining operations start, and to control incurred costs in process approach. The article is summed up with a process algorithm of cost management.
In recent years, the outsourcing of a variety of different activities has been more commonly observed in the coal mining industry. This is connected with employing workers by external companies. These practices are not necessarily perceived as good ones by mines’ employees because they may influence their remuneration directly or indirectly. Firstly, as external employees treat work in mining company as a source of a quick income. Therefore, external companies often calculate their employees compensation not based on working time (i.e. hours) but on the basis of a specific, accomplished task. Such employment is called piecework, whereas the workers employed in this kind of system are called output workers/piece workers. Therefore, to receive higher wages in these companies, employees carry out their tasks faster and more efficiently. This, in turn, can affect the standards of workers employed by the mining company. In addition, outsourced workers are often retired miners, so the costs incurred by employers are significantly lower. In addition, in order to not to lose the retirement benefit, they work for a much lower rate. On the other hand, outsourced work can be done in a hurry (on a piece rate), which is not conducive to compliance with safety regulations, therefore mine employees may feel unsafe. This article aims to present how mine employees assess outsourcing underground works. In order to achieve this aim, a survey was carried out among employees of one of the coal mine companies in Silesia. Participants of the survey were randomly chosen among underground miners employed at one mine company. The survey was anonymous which obviously might have influenced respondents’ honesty in answering. The survey was carried out in several mines of the chosen company. In some of them the survey was carried out online and in the remaining ones it was filled out on paper. Analyzing the survey results allowed for a better understanding of the reasons of the disapproval of outsourcing underground works. This, in turn, may be used for better human resources management including, in particular, planning an incentive based pay system.
The aim of the article is to show the dependence of what is our/mine and Other/Alien in thinking about conflicts around investment projects. Investments related to the development of space and resources of the Earth, especially if they cause any (real or potential) changes, generate negative emotions which often become the embers of conflict. Paradoxically, participation in such conflict may benefit the parties involved. Positive outcomes include: meeting needs (attention and significance), fulfilling (new) social roles, learning about other points of view, finding themselves in new social groups or embedded in local communities. Living in the social theater of life, each person plays different roles, which can lead to tension and a sense of ambivalence. In this situation, the individual has a sense of identity dispersion, being able to be simultaneously in several groups opposing each other. The conflict surrounding the Orzesze mining project can serve as an example here. This and other examples show that what is mine and the Other/Alien, with all its separateness, is, however, more or less intertwined with each other. So, the phenomenon of mutual dependence between the Other/Alien and conflict can provide an interesting perspective when looking at conflicts in managing the space and resources of the Earth. Conflicts, in particular mining-related ones, are an extremely complex phenomenon with great potential – both negative and positive. The appreciation of the benefits mentioned in the article, which result from the mutual dependence of the parties involved in the conflict along with their readiness to go outside their comfort zones, provide an opportunity for mutual understanding and reaching agreement which could lead to a positive change consistent with the idea of sustainable development. In this complex situation, the incorporation of not only sociological but also psychological aspects becomes an important element of the states’ and companies’ resources policy and cannot be neglected any more.
The article presents basic changes introduced in the first edition of the governmental Urban Planning and Building Code. The changes regard spatial development, especially planning and permit documents, and competences of the governmental bodies in accepting, legislating and issuing such documents. In this respect, the article points out important regulations for the mining industry, in particular for deposit protection and the initiation of mining projects. In certain cases, critical opinions of some of the governmental institutions are mentioned. In a new document regarding the “Spatial Development Study of a Community”, the draft of the Code orders a division of the community into functional zones. Therefore a mining and extractive industry could be delimited as a functional zone. The Code also specifies that while delimiting a new urbanization area, the documented mining deposits areas should be avoided. In relation to the local spatial plan, the Code establishes the following: in documented strategic mining deposit zones the initiation of non-public purpose investments can only be carried out according to the urban spatial plan. This project also orders that only the local spatial plan can allow for the localization of “establishments that carry a risk of serious industrial breakdown” and “investments that can seriously impact the environment”. The Code also introduces another innovation: the possibility of issuing the local spatial plan with an integrated evaluation on the environmental impact. The “investment permits” are intended to replace both the previous building permits and previous decisions on the conditions of development of the areas not covered in the local spatial plans. The investment permits referring to mining establishments will be issued by the mining administration authorities. The main adverse change for mining is that the exploration of mining deposits owned by the State Treasury loses its previous status of public purposes. The article also indicates that some of the described regulations might be changed during the further legislation process.
The utilization of mining waste is an important problem in Poland and Ukraine. The article presents one of the variants of waste mining in the quarry in Płaza. An analysis of the resource base of the deposit and their location at the area of Płaza deposit is carried out. The Płaza deposit is located in the western part of the Małopolskie province, in the entire Chrzanów commune. The Płaza deposit is constructed of Middle Triassic carbonates represented by the limestone-dolomite Olkusz Formation and the limestone-marlized Gogolin Formation. The deposit series lies on the dolomites of Röt age (Lower Triassic – Olenekian). The most valuable raw material was the pure limestone from the lower part of the Olkusz Formation, now almost completely exploited. The article presents the current state of mineable reserves of the deposit and their quality (chemical and physical characteristics). Moreover the article shows potential consumers of raw material and the possibility of extending the life of the mine work. According to the results of the environmental monitoring the ground and hydrogeological conditions were evaluated, the results of which allowed a more efficient use of the existing quarry area for mining waste disposal to be proposed. The paper presents a conceptual waste transport scheme, planned distribution and compaction of wastes belonging to the first, second and third group and then a surface reclamation. In view of the absence of similar decisions analogs, the consideration of the open-pit as a one solid geomechanical system functioning under the conditions of uncertainty is suggested. In order to examine the dynamics of the waste compaction process, some measures are foreseen to constantly observe their subsidence. The proposed measures for the synchronous disposal of mining waste in the worked-out area of the open-pit and the simultaneous mining operation in the quarry will allow the life cycle of the open-pit to be prolonged for 15–20 years.
The article discusses the validation process of a certain method of balancing gas contained in the pore space of rocks. The validation was based upon juxtaposition of the examination of rocks’ porosity and the effects of comminution in terms of assessing the possibility of opening the pore space. The tests were carried out for six dolomite samples taken from different areas of the ‘Polkowice-Sieroszowice’ copper mine in Poland. Prior to the grinding process, the rocks’ porosity fell in the range of 0.3-14.8%, while the volume of the open pores was included in the 0.01-0.06 cm3/g range. The grinding process was performed using an original device – the GPR analyzer. The SEM analysis revealed pores of various size and shape on the surface of the rock cores, while at the same time demonstrating lack of pores following the grinding process. The grain size distribution curves were compared with the cumulative pore volume curves of the cores before grinding. In order to confirm the argument put forward in this paper – i.e. that comminution of a rock to grains of a size comparable with the size of the rock’s pores results in the release of gas contained in the pore space – the amount of gas released as a result of the comminution process was studied. The results of gas balancing demonstrated that the pore space of the investigated dolomites was filled with gas in amounts from 3.19 cm3/kg to 45.86 cm3/kg. The obtained results of the rock material comminution to grains comparable – in terms of size – to the size of the pores of investigated rocks, along with asserting the presence of gas in the pore space of the studied dolomites, were regarded as a proof that the method of balancing gas in rocks via rock comminution is correct.
This article concerns numerical modeling of the impact of mining operations on fault behavior, carried out on the basis of a calculation program based on the finite element method. It was assumed that the fault is a single discontinuity in the form of a vertically-oriented plane, and the conditions in which surfaces merge are defined by the right of the Coulomb friction. On the one hand, the calculations are related to the fault’s response to additional weight resulting from mining operations, and on the other, they are related to the impact that occurrences in the fault’s plane had on the immediate surroundings of the extraction center. The behavior of the fault was analyzed based on distributions in the plane of shear stress and slip, together with their range and energy dissipated due to friction. In turn, the impact of the fault on its immediate environment was analyzed based on variations in the total energy density of elasticity. The results of numerical modeling made it possible to draw conclusions concerning mining operation in the proximity of tectonic dislocations in the context of seismic hazard’s levels.
With reference to the situation experienced in several Polish collieries where the risk of occurrence of gas-geodynamic phenomena is increasing and decisions to start the mining activities need to take numerous constraints associated with previous mining into account, this paper addresses certain geo-mechanical aspects of longwall mining in the zones of excavation edge interactions giving rise to major changes in the conditions of the deposit and rock strata, as a consequence of previous mining operations in adjacent coalbeds. Starting from the analytical description of displacements and stresses in the proximity of longwall mining systems, the paper summarizes the results of model tests and investiga-tions of the influence that the excavation edge has on the behavior and structural continuity of a portion of the coal body in the coalbed beneath or above an old excavation. Based on selected nonlinear functions emulating the presence of edges in the rock strata, a comparative study is carried out by investigating two opposite directions of workface advance, from the gob area towards the coal body and from the coal body towards the gobs. The discussion of the results relies on the analysis of roof deformation and the concentration factor of the vertical stress component at the workface front.
The stability of gateroads is one of the key factors for the mining process of hard coal by a longwall system. Wrong designed and applied the gateroad support at the stage of drilling, may adversely affect the functionality of the gateroad and the safety of the crew throughout its existence. The article presents the results of the underground tests and observations such as: convergence of the gateroad, stratification and the fractured zone range in the roof rocks, carried out in four longwall gateroads at the stage of their drilling. The obtained test results were the basis for the assessment of the possibility of using a convergence control method in the design of the gateroad support. The method is based on three interdependent relationships, such as: Ground Reaction Curve (GRC), Longitudinal Displacement Profile (LDP), and a Support Characteristic Curve (SCC). All calculations were performed using numerical modeling in the Phase2 program, based on the finite element method (FEM).
This article presents the use of a multi-criterion Analytic Hierarchy Process (AHP) method to assess geological and mining condition nuisance in longwall mining operations in selected coal mines in Poland. For this purpose, a methodology has been developed which was used to calculate the operational nuisance indicator (WUe) in relation to the cost of mining coal in individual longwalls. Components of the aggregate operational nuisance indicator include four sub-indicators: the natural hazards indicator (UZN), an indicator describing the seam parameters (UPZ), an indicator describing the technical parameters (UT) and an environmental impact indicator (UŚ). In total, the impact of 28 different criteria, which formed particular components of the nuisance indicators were analysed. In total 471 longwalls in 11 coal mines were analysed, including 277 longwalls that were mined in the period of 2011 to 2016 and 194 longwalls scheduled for exploitation in the years 2017 to 2021. Correlation analysis was used to evaluate the relationships between nuisance and the operating costs of longwalls. The analysis revealed a strong correlation between the level of nuisance and the operating costs of the longwalls under study. The design of the longwall schedule should therefore also take into account the nuisance arising from the geological and mining conditions of the operations. Selective operations management allows for the optimization of costs for mining in underground mines using the longwall system. This knowledge can also be used to reduce the total operating costs of mines as a result of abandoning the mining operations in entire longwalls or portions of longwalls that may be permanently unprofitable. Currently, underground mines do not employ this optimization method, which even more emphasizes the need for popularizing this approach.
The paper discusses the current situation as well as the perspectives for hard coal extraction in India, a global leader both in terms of hard coal output and import volumes. Despite this, over 300 million people lack access to electricity in this country. The main energy resource of India is hard coal and Coal India Limited (CI L) is the world’s biggest company dealing with hard coal extraction. CI L has over 450 mines, employs over 400,000 people, and extracts ca. 430 million tons of hard coal from its 471 mining facilities. India is planning the decisive development of hard coal mining to extract 1.5 billion tons in 2020. Hard coal output in India can be limited due to the occurrence of various threats, including the methane threat. The biggest methane threat occurs in the mines in the Jharia basin, located in East India (the Jharkhand province), where coal methane content is up to ca. 18 m3/Mg. Obtaining methane from coal seams is becoming a necessity. The paper provides guidelines for the classification of particular levels of the methane threat in Indian’s mines. The results of methane sorption tests, carried by the use of the microgravimetric method on coal from the Moonidih mine were presented. Sorption capacities and the diffusion coefficient of methane on coal were determined. The next step was to determine the possibility of degassing the seam, using numerical methods based on the value of coal diffusion coefficient based on Crank’s diffusion model solution. The aim of this study was the evaluation of coal seam demethanization possibilities. The low diffusivity of coal, combined with a minor network of natural cracks in the seam, seems to preclude foregoing demethanization carried out by means of coal seam drilling, without prior slotting.