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1

Applying model studies to support the monitoring of methane hazard during theprocess of underground coal mining

Tutak Magdalena, Brodny Jarosław, Małkowski Piotr, Grebski Wes

Production Engineering Archives

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2023

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Vol. 29, Iss. 3

319-327

EN

The process of underground mining is one of the most complex and hazardous activities. In order to maintain the continuity and efficiency of this process, it is necessary to take measures to reduce this hazard. The paper addresses this issue by presenting a developed methodology for using model studies and numerical simulations to support the process of monitoring methane hazards. Its basis is the developed model of the region of underground mining exploitation along with the ventilation phenomena occurring in it. To develop it, the ANSYS Fluent program was used, based on the finite volume method classified as computational fluid mechanics. The model reflects both the geometries and physical and chemical phenomena occurring in the studied area, as well as the auxiliary ventilation equipment used during operation. The research was conducted for two variants of methane emissions from goaf zones, the first of which concerned the actual state of the mining area, and the second of which concerned increased methane emissions from these goaf zones. The purpose of the study was to determine the distribution of methane concentrations in the most dangerous part of the studied area, which is the intersection of the longwall and the tailgate, as well as the distribution of ventilation air flow velocities affecting them. The studies for both variants made it possible to determine places particularly exposed to the occurrence of dangerous concentrations of methane in this region. The methodology developed represent a new approach to studying the impact of methane emissions from goaf zones into mine workings.

2

Methane hazard during the closure of mine excavations in liquidated mine – numerical simulation

Dziurzyński Wacław, Krawczyk Jerzy, Pałka Teresa, Krach Andrzej, Skotniczny Przemysław

Archives of Mining Sciences

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2023

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Vol. 68, no. 3

525--538

EN

The closure of deep mines, featuring multi level seam extraction, lasts many years. During this time period, the ventilation system must ensure adequate working conditions, and ensure the safety and stability of fan operation in gas and fire hazards conditions. The analysis of air flows and methane inflows during the progress of mining mine excavations closure, is the primary object of the article. Execution of such analysis requires knowledge of the mining mine excavations’ closure schedule, the structure of the ventilation system under consideration, the values of the parameters describing the air flows delivered to the mine excavations, and the current characteristics of operating fans and predicted methane exhalation. A computer database, currently being updated by a mine ventilation department for the VentGraph-Plus computer software, has been used simulate the various ventilation scenarios experienced, during the final stage of closure, including the shutdown of the main fans and the backfilling of shafts. The results of case study, containing 2 variants of simulated examples, are presented in the form of diagrams of methane concentration changes in time at characteristic places of the mine. The completed simulations of ventilation processes during the closure of mine excavations and transfer of inflowing methane, indicate useful possibilities of the computational tool used.

3

The role, importance and impact of the methane hazard on the safety and efficiency of mining production

Palka Dorota, Brodny Jarosław, Tutak Magdalena, Nitoi Dan

Production Engineering Archives

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2022

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Vol. 28, Iss. 4

390--397

EN

Underground mining production is an extremely important process for the economy and carried out in very difficult and complex environmental conditions. The disturbance of the balance of this environment makes it also a very dangerous process. Due to the importance of coal, mainly as an energy raw material, the process of its exploitation is carried out all over the world. The specificity of its production is mainly determined by mining and geological conditions, which determine the method of operation and the selection of machines and devices for this process. One of the most dangerous natural hazards associated with this process are ventilation hazards, including methane hazard. The reason for this threat is methane, an odorless and colorless gas, which becomes a flammable and explosive gas under certain criteria. These features make this gas a huge threat to mining operations. Its huge amounts, contained in coal seams, are released into the mine atmosphere during the exploitation process, causing a very high threat to work safety. Events related to the occurrence of methane are most often the cause of mining disasters, in which people die and the technical and mining infrastructure is destroyed. The reason for the growing methane hazard is the increasingly difficult mining conditions, and mainly the increasing depth of mining, and thus also the increase in methane-bearing capacity of the seams. Taking into account the huge impact of methane hazard on the mining process, the article discusses its impact on the safety and efficiency of this process. The results of the literature review with regard to this risk are presented and the accident statistics are presented. On the basis of actual data, an analysis of interruptions in the exploitation process related to exceeding the permissible me-thane concentrations was carried out in one of the mines. The problem of limiting the production process due to these exceedances is an important factor reducing the efficiency of this process. The obtained results clearly indicate that the losses resulting from these breaks deteriorate the profitability of the entire process and affect the economic efficiency of the industry. In order to effectively counteract the dangerous phenomena related to the methane hazard and to improve the efficiency of the mining production process, solutions were proposed to improve this state and the directions for further research were proposed.

4

Analysis of the application of methane-bearing capacity test methods in the conditions of Polish mining

Karbownik Marcin

Journal of Sustainable Mining

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2022

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Vol. 21, iss. 4

309--318

EN

The methane hazard is one of the natural hazards occurring in hard coal mining. The content of natural methane in hard coal seams, the so-called methane-bearing capacity, is one of the key parameters that allow for proper assessment of the methane hazard and the state of the threat of gas and rock outbursts. For safety purposes, there is a constant need to improve the methods for the determination of this parameter. In the conditions of Polish mining, the method used for methane-bearing capacity determination is the direct drill cuttings method. This paper contains a comparative study presenting three different methods of methane-bearing capacity determination. Tests were conducted using two direct methods (the drill cuttings method and the United States Bureau of Mines (USBM) method), and the indirect method based on the desorption intensity index. On the basis of the obtained test results, it was found that the results obtained with the USBM method were slightly higher than those obtained with the direct drill cuttings method. Gas losses, an important element affecting the final value of the assay, were also analysed. This comparative study will evaluate the validity and applicability of the above methods under specific conditions in hard coal mining.

5

Przyrząd do wczesnego wykrywania zagrożenia metanowego w oparciu o odcinkowy pomiar stężenia metanu

Ostrogórski Piotr, Skotniczny Przemysław, Jońca Maciej

Prace Instytutu Mechaniki Górotworu PAN

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2021

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T. 23, nr 1-4

11--16

EN

The article presents a prototype of a new device enabling the monitoring of gas hazards, in particular methane hazard and the hazard caused by excessive carbon dioxide concentration in the air. The methane hazard requires control through appropriate proactive activities, which includes measuring the concentration of methane with individual devices. Point measurements of methane concentration are used both for routine inspections in designated places and for the assessment of the source of the hazard. A portable methane meter was developed for the ongoing evaluation of methane hazard by measuring the concentration of methane along the measurement sections. It is equipped with the possibility of locating the measurement by sections and the algorithm of inference about the hazard level. The device is in the prototype stage and has an implemented „beacon” algorithm enabling localization.

PL

W artykule przedstawiono prototyp nowego urządzenia umożliwiającego monitorowanie zagrożeń gazowych w szczególności zagrożenia metanowego oraz zagrożenia spowodowanego nadmiernym stężeniem dwutlenku węgla w powietrzu. Zagrożenie metanowe wymaga kontroli poprzez właściwą profilaktykę do której zalicza się wykonywanie pomiarów stężenia metanu przyrządami indywidualnymi. Punktowe pomiary stężenia metanu służą zarówno do rutynowych kontroli w miejscach do tego wyznaczonych jak i do oceny źródła zagrożenia. Opracowano metanomierz przenośny służący do bieżącej oceny zagrożenia metanowego poprzez pomiar stężenia metanu wzdłuż odcinków pomiarowych. Wyposażono go w możliwość lokalizacji odcinka pomiarowego i algorytm wnioskowania o zagrożeniu. Przyrząd jest w fazie prototypowej oraz ma zaimplementowany algorytm „beacon” umożliwiający lokalizację.

6

Modeling and Simulation of the Methane Risk in the Mining Production Process

Palka Dorota

Multidisciplinary Aspects of Production Engineering

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2021

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Vol. 4, Iss. 1

1--13

EN

The mining production process is of particular importance for the area of Upper Silesia, as well as a very significant impact on the economy of the entire country. One of the most common and most dangerous threats to this process is the methane hazard. It is related to the presence of methane in coal seams, which under appropriate conditions is a flammable and explosive gas. Events related to the methane hazard constitute a huge threat to the life and health of the crew as well as the infrastructure and equipment of excavations. Therefore, they have a huge impact on the efficiency of the entire mining production process. In order to ensure the safety and continuity of the production process, it is necessary to prevent the formation of dangerous methane concentrations in the area covered by the operation. One of the tools that can be used to assess the state of methane hazard are model studies supported by numerical simulation. Based on these studies, the article analyzes the distribution of methane concentration in the mining area. This area included an actual mining excavation in one of the hard coal mines. The model tests were carried out with the use of the finite volume method in the ANSYS Fluent software. The obtained results can be used for preventive measures and constitute an important source of information for the assessment of the methane hazard state.

7

Zastosowanie wyników modelowania numerycznego stref odprężenia eksploatacyjnego w prognozowaniu emisji metanu z warstw otaczających do ścian zawałowych

Wierzbiński Krystian

Przegląd Górniczy

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2020

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T. 76, nr 8

1--12

PL

Wielopoziomowy charakter eksploatacji pokładów węgla charakterystyczny dla Górnośląskiego Zagłębia Węglowego oraz zaleganie w strefie odprężenia eksploatacyjnego wielu pokładów metanowych skutkuje intensyfikacją zagrożenia metanowego w ścianach z tytułu dopływu metanu desorbującego z pokładów objętych strefą odprężenia eksploatacyjnego. Dla zminimalizowania błędu prognozy metanowości bezwzględnej kluczowego znaczenia nabiera trafne określenie zasięgu strefy odprężenia eksploatacyjnego, uzależnionego od lokalnych warunków górniczo-geologicznych, a w szczególności od parametrów geomechanicznych warstw skalnych. Mając na uwadze fakt, że w aktualnie stosowanej metodzie prognozowania metanowości bezwzględnej ścian zasięg strefy odprężenia eksploatacyjnego nie uwzględnia właściwości warstw skalnych, w artykule w oparciu o Metodę Różnic Skończonych (MRS) - wyznaczone zostały strefy odprężenia eksploatacyjnego dla dwóch ścian o długości 186 m i 250 m. W przypadku zasięgu górnej strefy odprężenia eksploatacyjnego wyniki modelowania potwierdziły założenia przyjmowane do prognozy metanowości bezwzględnej ścian. Dla strefy odprężenia eksploatacyjnego obejmującej warstwy spągowe uzyskano jednak znaczne różnice między zasięgiem określanym metodą empiryczną a metodą modelowania MRS. Po zaimplementowaniu stref MRS do algorytmu prognozowania metanowości bezwzględnej, opracowano prognozy dopływu metanu do ścian z warstw znajdujących się w strefie odprężenia eksploatacyjnego. Przeprowadzenie badań dołowych emisji metanu pozwoliło zweryfikować trafność prognozy uwzględniającej parametry geomechaniczne górotworu.

EN

The multi-level character of coal seams exploitation characteristic for the Upper Silesian Coal Basin and the fact that many methane seams are deposited in the destressing zone results in the intensification of methane hazard in longwalls due to the inflow of desorbing methane from the seams covered by the destressing zone. For minimising the error of forecasting the methane emission, it is crucial to correctly determine the range of the destressing zone, which depends on the local mining and geological conditions, and in particularly on the geomechanical parameters of rock layers. Considering the fact that the currently used methane emission forecasting method does not take into account the properties of rock layers, the destressing zones for two longwalls with a length of 186m and 250m were determined on the basis of the Finite Difference Method (FDM). For the upper destressing zone, the modelling results confirmed the assumptions applied to the prognosis of methane emissions to the longwalls. In case of the bottom layers, significant differences were obtained between the range of destressing zone determined by the empirical method and the FDM. After the implementation of FDM zones into the methane emission prediction algorithm, prognoses of methane inflow to longwalls from layers located in the destressing zone were performed. Underground tests of methane emission allowed to verify the accuracy of the prognosis based on geomechanical parameters of the rock mass.

8

Macierzowa metoda prognozowania efektywności odmetanowania

Gajdowska Maria

Przegląd Górniczy

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2020

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T. 76, nr 1

1--5

PL

Problematyka zwiększenia efektywności odmetanowania w środowisku eksploatowanych ścian wymusza niejako wcześniejsze podejmowanie obliczeń wentylacyjno-metanowych na etapie projektowania ścian. W artykule przedstawiono macierzową metodę prognozowania efektywności odmetanowania. Prognozowane wartości efektywności odmetanowania dla projektowanych etapów wybiegu ściany przy zakładanym postępie mają kluczowe znaczenie przy określeniu warunków eksploatacji i mogą być pomocne przy doborze właściwego systemu odmetanowania. Analizę prognoz efektywności odmetanowania przedstawiono na przykładzie dwóch ścian.

EN

It is necessary to make early ventilation and methane calculations at the longwall design phase due to the issues associated with the increase in methane drainage efficiency in the area of mined longwalls. This paper presents a matrix method for projecting methane drainage efficiency. Projected values of methane drainage efficiency for designed panel lengths with the expected longwall mining progress are of significant importance in relation to determining mining conditions and may be useful for the selection of an appropriate methane drainage system. The analysis of methane drainage efficiency projections is demonstrated on the basis of two longwalls.

9

Istota zagrożenia metanowego w zlikwidowanej kopalni węgla kamiennego, w aspekcie planowanego wznowienia wydobycia

Słota Krzysztof, Słota Zbigniew, Morcinek-Słota Anna

Przegląd Górniczy

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2020

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T. 76, nr 5

42--48

PL

Zgodnie z Programem dla sektora górnictwa węgla kamiennego w Polsce na lata 2018-2030 konieczne jest dostosowanie wydobycia do potrzeb rynku. w związku z tym istnieje możliwość ponownego uruchomienia zlikwidowanej kopalni i wydobywanie dobrej jakości węgla kamiennego. Ponowne wznowienie wydobycia wiąże się między innymi z odwodnieniem kopalni, a sama przyszła eksploatacja będzie prowadzona w pokładach metanowych. Zachodzi zatem konieczność analizy zagrożenia metanowego, możliwości zastosowania odmetanowania i zagospodarowania metanu w celach przemysłowych (do produkcji energii i chłodu). W artykule określono zagrożenie metanowe w oparciu o wyniki badań gazowych (m.in. metanonośności, analizy chemizmu gazów pokładowych), wykonanych w otworach wiertniczych oraz w dołowych wyrobiskach korytarzowych jeszcze wtedy, gdy w kopalni prowadzone było wydobycie.

EN

According to the Programme for the hard coal mining sector in Poland for the years 2018-2030, it is necessary to adapt the extraction to the market needs, therefore it is possible to restart the decommissioned mine and extract good quality hard coal. The resumption of extraction is associated, among other things, with dehydration of the mine and the future exploitation itself will be carried out in methane seams. Therefore, it is necessary to analyze the methane hazard, the possibility of using methane de-methanation and the use of methane for industrial purposes (for energy and cooling production). The article defines the methane hazard on the basis of the results of gas tests (e.g. methane carrying capacity, analysis of the chemistry of the seabed gases) carried out in boreholes and in underground corridor excavations while mining was still being carried out in the mine.

10

Study of the Accuracy of Methane Concentration Forecasts in the Area of Longwall Outlet B-3 in Seam 407/1 in KWK “Borynia-Zofiówka” Ruch Zofiówka

Badura Henryk, Zmarzły Marian, Trzaskalik Paweł, Korshunov Aleksandr Ivanovich

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

120--130

EN

In the presented publication, an ex post forecast of methane concentration at the airway outlet was carried out on the basis of equations previously developed and repeatedly tested by H. Badura and its errors were calculated. This forecast was considered as a reference level. Next, using the same forecast equations, the forecasting of methane concentration at the sensor location up to 10 m in front of the longwall face and at the longwall outlet was carried out, followed by the analysis of forecast errors. Since the measurement of methane concentrations in the locations under consideration differed, the results of forecasts also differed. Therefore, in order to assess the accuracy of forecasts, their absolute and relative errors were calculated and then compared with the forecast errors at the airway outlet. The analysis of errors showed that there are differences in forecast accuracy and it is advisable to develop new forecast equations mainly for the longwall outlet, but also for the location of methane concentration sensor installed in the airway up to 10 m in front of the longwall.

11

Analysis of Stoppages in the Process of Roadway Drivage Caused by Exceeding the Maximum Allowable Level of Methane Concentration

Brodny Jarosław, Tutak Magdalena, Felka Dariusz, Dorota Palka

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

197--210

EN

Methane is one of the most dangerous gases occurring in mining production. Being inseparably connected with the rock mass, it presents a serious risk to occupational safety and reduces the effectiveness of mining production. A particularly high methane hazard occurs directly during exploitation in longwall headings and the drivage of roadways. Exceeding the maximum allowable level of its concentration in these headings makes it necessary to disconnect all machines until this concentration level is reduced. This leads to unscheduled downtimes of such machines, thus increasing the costs of their operation and decreasing their effectiveness. The paper demonstrates the results from the analysis of machine downtimes in the drivage of roadways, caused by excessive methane concentration levels. The analyses were based on the indications from the system for automatic monitoring of the ventilation parameters in this heading. The results obtained clearly demonstrated that exceeded values of methane concentration caused a series of unexpected downtimes in the drivage process. As a result, the process was disturbed and its effectiveness reduced. The presented analyses are one of the first to address the issue of how methane emissions affect machine downtimes. However, this phenomenon represents a major problem that needs to be addressed comprehensively in order to minimise the losses arising out of the necessary disruptions to the exploitation process.

12

Analysis of Gas-Geodynamic Phenomena During the Preparatory and Mining Works in Seam 358/1 at KWK “Budryk”

Zmarzły Marian, Schubert Michał, Salamon Krystian

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

131--148

EN

The nature of gas-geodynamic phenomena is so complicated and unpredictable that it forces the necessity of continuous search for new principles of identifying the outburst threat and ongoing monitoring of this threat with view of current conditions in the mine. After the incidents in JSW S.A, the mines carrying out works in seams threatened with outbursts, upon their own initiative introduced additional rigours and increased the frequency of measurements and tests regardless of the existing legal requirements. Incidents that have taken place in KWK “Budryk” in recent years show how important is continuous verification of knowledge related to the forecasting of the outburst threat on the basis of ongoing observations of works. The local occurrence of a zone characterized by high methane-bearing capacity in the coal seam, even after taking preventive measures and introducing additional rigorous did not allow for the complete elimination of gas-geodynamic phenomena and avoidance of danger to employed people.

13

Method for a Drainage Roadway Location Determination for an Overlying Methane Drainage System

Borowski Marek, Cała Marek

Inżynieria Mineralna

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2020

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no. 2, vol. 1

201--207

EN

The paper analyses possibilities to carry out methane drainage of a longwall in seam 510. A possibility to fight against the methane hazard was determined based on results of forecasting for methane emission to mine workings. A system of methane drainage was suggested for the adopted method of longwall face ventilation. The location of drainage roadway was determined for the selected methane drainage system. The paper includes a geomechanical analysis for a numerical model, which was aimed at determination of the optimum location of the drainage roadway in a seam overlying the longwall panel.

PL

W artykule przedstawiono analizę możliwości prowadzenia odmetanowania ściany w pokładzie 510. Na podstawie wyników prognozy wydzielania metanu do wyrobisk górniczych określono możliwości zwalcza-nia zagrożenia metanowego. Zaproponowano system odmetanowania z chodnikiem drenażowym ponad eksploatowanym pokładem dla przyjętego sposobu przewietrzania wyrobiska ścianowego. Dla wybranego systemu odmetanowania wyznaczono lokalizację chodnika drenażowego. W artykule zamieszczono analizę geomechaniczną dla modelu numerycznego, której celem było określenie optymalnej lokalizacji chodnika drenażowego pokładzie wyżej leżącym nad polem eksploatacyjnym.

14

Influence of rock geomechanical parameters on increased longwall absolute methane emission rate forecasting accuracy

Walentek Andrzej, Wierzbiński Krystian

Archives of Mining Sciences

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2020

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Vol. 65, no. 3

641--664

EN

In longwall absolute methane emission rate forecasting, the range of the destressing zone is determined empirically and is not considered to be dependent on the geomechanical parameters of the rock strata. This simplification regarding destressing zone determination may result in significant differences between the forecast and the actual methane emission rates. During the extraction of coal seams using a system involving longwalls with caving under the conditions of low rock mass geomechanical parameters, the absolute metha-ne emission rate forecasts are typically underestimated in comparison to the actual methane emission rates.In order to examine the influence of the destressing zones on the final forecasting result and to assess the influence of the rock mass geomechanical parameters on the increased accuracy of forecast values, destressing zones were determined for three longwalls with lengths ranging from 186 to 250 m, based on numerical modelling using the finite difference method (FDM). The modelling results confirmed the assumptions concerning the upper destressing zone range adopted for absolute methane emission rate forecasting. As for the remaining parameters, the destressing zones yielded great differences, particularly for floor strata. To inspect the accuracy of the FDM calculation result, an absolute methane emission rate forecasting algorithm was supplemented with the obtained zones. The prepared forecasts, both for longwall methane emission rates as well as the inflow of methane to the longwalls from strata within the destressing zone, were verified via underground methane emission tests. A comparative analysis found that including geomechanical parameters in methane emission rate forecasting can significantly reduce the errors in forecast values.

15

Rozwój elektrycznych urządzeń budowy przeciwwybuchowej dla kopalń metanowych

Gierlotka Stefan

Śląskie Wiadomości Elektryczne

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2019

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Nr 2 (124)

26--30

PL

W artykule omówiono rozwój urządzeń elektrycznych dla kopalń wynikający z zagrożeń związanych z gazami kopalnianymi, tj. metanem oraz pyłem węglowym. Przedstawiono prace badawcze ze stosowania i konstrukcji urządzeń elektrycznych budowy przeciwwybuchowej, zarówno w Polsce, jak i na świecie. Omówiono także normy dla tych urządzeń.

EN

The paper presents development of electric devices for mines where a danger connected with gases like methane and coal dust is observed. Research works presenting construction and application of the devices in Poland and abroad are presented. Standards for the devices are also described.

16

Wpływ zagrożeń naturalnych na bezpieczeństwo prowadzenia robót w kopalniach podziemnych

Szlązak Nikodem, Swolkień Justyna

Systemy Wspomagania w Inżynierii Produkcji

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2019

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Vol. 8, iss. 1

73--86

PL

W artykule przedstawiono charakterystykę zagrożeń aerologicznych wpływających ze wzrostem głębokości prowadzonej eksploatacji na bezpieczeństwo prowadzonych robót górniczych. Szczególną uwagę zwrócono na zagrożenie klimatyczne i metanowe i ich wzajemne powiązania. Współwystępowanie zagrożeń naturalnych przyczynia się do obniżenia bezpieczeństwa prowadzonych robót górniczych. Wzrost występujących zagrożeń naturalnych wiąże się ze wzrostem kosztów prowadzonej eksploatacji wynikających głównie z konieczności ich zwalczania.

EN

The article presents the characteristics of natural hazards occurring with the increase in the depth of exploitation and their impact on the safety of mining operations. Particular attention was paid to climate and methane hazards and their interrelationships. Co-occurrence of natural hazards contributes to a decrease in the safety of mining operations. The increase in natural hazards is associated with an increase in operating costs resulting mainly from the need to combat them.

17

Rejestracje rozkładu stężenia metanu na skrzyżowaniu wylotu ściany z chodnikiem nadścianowym

Wasilewski Stanisław

Prace Instytutu Mechaniki Górotworu PAN

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2019

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T. 21, nr 1-4

15--26

PL

Praktyka górnicza oraz wyniki badań pokazują, że dla przewietrzanie ścian sposobem na „U” po caliźnie węglowej występuje migracja metanu ze zrobów do likwidowanej części chodnika wentylacyjnego, co ma istotny wpływ na zagrożenia metanowe. Wcześniejsze badania prowadzono dla rozpoznania dopływu metanu do ściany w czasie urabiania kombajnem. Obecnie jest to próba oszacowania dopływu metanu z odkrytej calizny, a przede wszystkim ze zrobów ściany przy braku urabiania i pracy maszyn. Praktyka pokazuje, że w przypadku przewietrzania ściany sposobem na U po caliźnie węglowej powietrze ucieka do zrobów w początkowym odcinku ściany, aby wypływać w jej końcowym biegu wynosząc gazy zrobowe, w tym metan, do ściany oraz do skrzyżowania ściany z likwidowanym chodnikiem wentylacyjnym. W artykule przedstawiono eksperyment badawczy, w którym zastosowano bezprzewodowe czujniki metanu nie skrepowane liniami pomiarowymi. Taka instalacja umożliwiła rejestrację stężenia metanu dla dowolnego rozłożenia czujników metanu na końcu ściany i na skrzyżowaniu wylotu ściany z chodnikiem nadścianowym. Uzyskane wyniki rejestracji maja istotne wartości poznawcze dostarczając potrzebnych danych do weryfikacji i walidacji badań modelowych.

EN

Mining practice and research results show that for longwalls with the “U” type ventilation system and variant with airflow along the solid coal, methane migration from goaf to the liquidated part of the tailgate has a significant impact on methane hazards. Earlier studies were conducted to identify the methane inflow to the longwall during mining with a shearer. Currently, it is an attempt to estimate the inflow of methane during stoppage of mining and machine operation. Then remaining emission sources are mainly all the longwall goaf and a smaller amount comes from the coal face. Practice shows that in the case of such ventilation arrangement, the air leaks from longwall into the goaf in the initial section of the longwall and flows back into the longwall close to the end, carrying the goaf gases, including methane, to the longwall and to the crossing of the longwall outlet with the tailgate. The paper presents a research experiment in which wireless methane sensors were used. Due to the lack of cumbersome wires they could be freely distributed in the final sections of the longwall and at the crossing of the longwall outlet with the tailgate. The registration results obtained have significant cognitive values, providing the necessary data for verification and validation of model research.

18

Tests of methane desorption and emission from samples of hard coal in the context of mine closures through flooding

Krause Eugeniusz, Karbownik Marcin

Journal of Sustainable Mining

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2019

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Vol. 18, iss. 3

127--133

EN

Forecasts of methane emissions during and after flooding a closed gassy hard coal mine and the evaluation of possible methane migration to the surface in post-mining areas, after cutting off the vertical ventilation workings of hard coal mines from the surface, provide valuable information which can help to ensure public safety. This article presents research into the influence of changes in the hydrostatic pressure of a water column in a flooded mine on the volume of methane emission and migration from hard coal seams, during and after the flooding of a closed mine. The tests were conducted based on a modified research method developed by the French National Institute for Industrial Environment and Risks (INERIS), France, and the Central Mining Institute (GIG), Katowice, Poland. A test stand for gas desorption and autoclaves for emissions, under controlled pressure and temperature, were used. The tests were conducted and changes in pressure in the autoclaves over time were observed. The observations led to the conclusion that water inhibits methane desorption and emission from coal to varying extents, depending on the hydrostatic pressure exerted. Based on the conducted tests, developed a model of methane emission into flooded goafs was developed. A method of determining index k2 was also developed, which lowers the forecast volume of methane emission into goafs depending on the value of the hydrostatic pressure of the water column and the level of submersion. Results of the tests form the basis to calculate forecasts in the developed model of methane emission into the goafs of a mine during its closure, which, as a consequence, enables the identification of the level of methane hazard and the selection of preventive measures aimed at combating methane hazard during and after the closure of a gassy mine.

19

Methane emissions in selected hard-coal mines of the Upper Silesian Coal Basin in 1997–2016

Dreger Marcin

Geology, Geophysics and Environment

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2019

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Vol. 45, no. 2

121--132

EN

Hard coal is extracted in the Upper Silesian Coal Basin (USCB) from deeper and deeper coal seams every year. In 2000, the average depth of coal extraction was 600 m, in 2010 – 700 m, but in the last two years (2016–2017) this has been extended to a depth of 770 m. The USCB is not homogeneous in layout in terms of methane hazard, but rather very diverse. Therefore, the USCB has been divided into seven gassy regions to show differences in methane danger distribution. Northern and central USCB regions (I, II and III) are the mostly naturally degassed, so the most dangerous gassy conditions are in the IV and V regions, where methane content in coal seams varies from 6 m3/Mg coaldafto above 18 m3/Mg coaldaf. The two westernmost USCB gassy regions (VI and VII) are poorer in methane than the IV and V areas. Six representative coal mines were chosen: Mysłowice-Wesoła, Budryk, Brzeszcze, Pniówek, Marcel and Rydułtowy-Anna based on their high hard coal production and total methane emissions. The reason for the highest methane emission in those regions might be fault tectonics facilitating methane migration and also the thick and continuous Miocene cover constituting a hermetic screen for gases in the southern part of the USCB.

20

Methodology for determining methane distribution in a longwall district

Dziurzyński Wacław, Palka Teresa, Krach Andrzej, Wasilewski Stanisław

Archives of Mining Sciences

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2019

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Vol. 64, no. 3

467--485

EN

This paper presents mathematical models enabling the calculation of the distribution and patterns of methane inflow to the air stream in a longwall seam being exploited and spoil on a longwall conveyor, taking into account the variability of shearer and conveyor operation and simulation results of the min-ing team using the Ventgraph-Plus software. In the research, an experiment was employed to observe changes in air parameters, in particular air velocity and methane concentration in the Cw-4 longwall area in seam 364/2 at KWK Budryk, during different phases of shearer operation in the area of the mining wall in methane hazard conditions. Presented is the method of data recording during the experiment which included records from the mine’s system for automatic gasometry, records from a wireless system of eight methane sensors installed in the end part of the longwall and additionally from nine methane anemometers located across the longwall on a grid. Synchronous data records obtained from these three independent sources were compared against the recording the operating condition of the shearer and haulage machines at the longwall in various phases of their operation (cleaning, cutting). The results of the multipoint system measurements made it possible to determine the volume of air and methane flow across the longwall working, and, consequently, to calculate the correction coefficients for determining the volume of air and methane from measurements of local air velocity and methane concentration. An attempt was made to determine the methane inflow from a unit of the longwall body area and the unit of spoil length on conveyors depending on the mining rate. The Cw-4 longwall ventilation was simulated using the data measured and calculated from measurements and the simulation results were discussed.

PL

W artykule przedstawiono modele matematyczne pozwalające obliczyć rozkład i przebieg dopływu metanu do strumienia powietrza w ścianie z urabianego pokładu i urobku na przenośniku ścianowym z uwzględnieniem zmienności pracy kombajnu i przenośnika oraz wyniki symulacji pracy zespołu wydobywczego z zastosowaniem programu Ventgraph-Plus. W badaniach wykorzystano eksperyment obserwacji zmian parametrów powietrza, a w szczególności prędkości powietrza i stężenia metanu w rejonie ściany Cw-4 w pokładzie 364/2 KWK Budryk w czasie różnych faz pracy kombajnu w rejonie ściany wydobywczej w warunkach zagrożenia metanowego. Przedstawiono sposób rejestracji danych w czasie eksperymentu, który obejmował zapisy z kopalnianego systemu gazometrii automatycznej, rejestracje w systemie bezprzewodowych w liczbie 8 sztuk czujników metanu zabudowanych w końcowej części ściany oraz dodatkowo 9 sztuk meta-anemometrów zabudowanych w przekroju poprzecznym ściany na kratownicy. Synchroniczne zapisy danych pozyskane z tych trzech niezależnych źródeł porównano na tle zapisu stanu pracy kombajnu oraz maszyn odstawy w ścianie w różnych fazach ich pracy (czyszczenie, cięcie). Wyniki pomiarów systemem wielopunktowym pozwoliły wyznaczyć strumień objętości powie-trza i metanu w przekroju wyrobiska ścianowego i w następstwie obliczyć współczynniki korekcyjne dla wyznaczania strumienia objętości powietrza i metanu z pomiarów miejscowych prędkości powietrza i stężenia metanu. Podjęto próbę wyznaczenia wielkości dopływu metanu z jednostki powierzchni calizny ściany oraz z jednostki długości urobku na przenośnikach w zależności od prędkości urabiania. Wykonano symulację przewietrzania ściany Cw-4 z wykorzystaniem zmierzonych i obliczonych z pomiarów danych oraz omówiono wyniki symulacji.