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1

Underground mine gas explosion accidents and prevention techniques – an overview

Song Wanting, Cheng Jianwei, Wang Wenhe, Qin Yi, Wang Zui, Borowski Marek, Wang Yue, Tukkaraja Purushotham

Archives of Mining Sciences

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2021

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Vol. 66, no. 2

297--312

EN

Mine gas explosions present a serious safety threat in the worldwide coal mining industry. It has been considered the No.1 killer for underground coal mining workers. The formation of an explosive atmosphere involves various factors. Due to complicated stratified geology and the coal production process, geological conditions and coal production process reasons and particular working sections underground present a high risk of an explosion that would most likely cause casualties and property loss. In this study, the basic conditions, propagation law and hazards analysis of gas explosions are reviewed, followed by a review of the typical locations where an explosion would occur. Finally, current technologies used in the mining industry for preventing gas explosions and suppressing the associated dangers were studied. Preventive gas explosion technologies mainly include gas drainage, gas accumulation prevention and gas and fire source monitoring technologies. The technologies often used to control or mitigate gas explosion hazards are usually divided into active and passive, and the advantages and disadvantages of each method are discussed and compared. This paper aims to summarise the latest technologies for controlling and suppressing gas explosion and guides mining engineers to design risk mitigation strategies.

2

Innovative technology of tight liquidation of workings on the example of the Wieliczka Salt Mine

Gonet Andrzej, Stryczek Stanisław Antoni

Archives of Mining Sciences

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2021

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Vol. 66, no. 1

3--12

EN

The authors of the paper describe the way in which the longitudinal working Gussmann was mined in level V and the longitudinal working Kosocice in level VI, which in both cases resulted in a water flux from behind the northern boundary of the salt deposit. Only after concrete dams were seated on both levels, the brine flux was stopped leaving a direct contact of the dams with the pressurized water around the mine. For the sake of controlling water beyond the dams, steel pipelines were conducted through both dams and equipped with gauges before the dams. Their use in a saline environment, the developing corrosion increased the possibility that the tightness of the pipelines would be damaged. For this reason a decision was made to protect the mine by making a tight reconstruction of the safety pillar in both levels along the longitudinal working for about 600 m from the dams eastwards. For this purpose the pipeline injection method was applied. As the volume of voids to be tightly filled equaled to about 3800 m3, the task had to be divided into stages. Because of considerable distances of the liquidated workings from the closest shaft, the sealing slurries were prepared in a special injection center on the surface from where they were transported to the destination with a pumping pipeline through the Kościuszko shaft. The most important aspect of liquidating the end parts of the longitudinal working was to properly select the sealing slurries in view of their best cooperation with the rock mass, and such parameters as tightness, durability and cost. At the end stage of works, both longitudinal workings were equipped with dams, which were sealed up with the hole injection method. The innovative technology was implemented in the Wieliczka Salt Mine to reconstruct the safety pillar in levels VI and V in the most westward workings, the mine was shortened by about 600 m, the length of the ventilation system was reduced, systematic observations and pressure read-outs in dams 3 and 4 were systematically eliminated in dams 3 and 4. In this way the costs were lowered and safety of the mine improved.

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Study on the mechanics and micro/macroeconomics of multiple strip-shaped pillar recovery

Chen Qingfa, Wu Shiwei, Zhao Fuyu

Archives of Mining Sciences

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2020

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Vol. 65, no. 1

19--33

EN

The structural system of a multiple strip-shaped pillar-roof is common in underground mine exploitation, and research on its mechanics and micro/macroeconomics is meaningful for utilizing strip-shaped pillar resources. A general model of the structural system of a multiple strip-shaped pillar-roof was established, the deformation mechanism of the model was analysed by material mechanics, and the deflection curve equations of the model were obtained. Based on the stress strain constitutive relation of the strip pillar and cusp catastrophe theory, the nonlinear dynamic instability mechanism of the structural system of a multiple strip-shaped pillar-roof was analysed, and the expressions of the pillar width for maintaining the stability of different types of structural systems were derived. The benefits of different structural systems were calculated using micro/macroeconomic theory, the type of the structural system was determined, and different recovery schemes were obtained. Theoretical application research was applied to a large manganese mine, and the results demonstrate that no pillar recovery was needed in 2016, a 9-m wide artificial pillar could be built to replace a pillar in 2017, and the construction of 14-m wide artificial pillars can be conducted in 2018.

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The Process of Closing of Ventilation Areas of the Paskov Mine, OKD a.s. – Czech Republic

Hruzek Z., Kosnovsky V., Grygarcik F., Hudecek V.

Inżynieria Mineralna

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2018

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R. 20, nr 2

213--220

EN

On the 31st March 2017, the mining of hard coal in the last active mine in the Ostrava part of Ostrava-Karviná Coalfield was completed according to plan. Based on the decision of management of the company OKD, a.s. concerning the closure of the Paskov Mine, a plan of gradual closure of individual ventilation areas of the mine was prepared. Currently, the Paskov Mine is, from the point of view of mining legislation, in the stage of treatment and, in accordance with this plan, operations connected with the closure of individual areas are being performed. The decommissioning of main mine workings can be commenced after obtaining a necessary permit from the District Mining Authority for the area of the Moravian-Silesian and the Olomouc Region. In the article, information on the current process of closing of ventilation areas of the Paskov Mine and the expected subsequent process of mine closure is summarised.

PL

W dniu 31 marca 2017 r. wydobycie węgla kamiennego w ostatniej czynnej kopalni w Ostrawskiej części Zagłębia Ostrawsko- -Karwińskiego zakończono zgodnie z planem. Na podstawie decyzji zarządu firmy OKD, a.s. w sprawie zamknięcia Kopalni Paskov przygotowano plan stopniowego zamykania poszczególnych obszarów wentylacyjnych kopalni. Obecnie Kopalnia Paskov jest z punktu widzenia przepisów górniczych na etapie likwidacji i zgodnie z tym planem prowadzone są działania związane z zamknięciem poszczególnych obszarów. Likwidacja głównych wyrobisk górniczych może zostać rozpoczęta po uzyskaniu niezbędnego zezwolenia od Powiatowego Urzędu Górniczego na obszar województwa morawsko-śląskiego i ołomunieckiego. W artykule podsumowano informacje na temat aktualnego procesu zamykania obszarów wentylacyjnych kopalni Paskov oraz oczekiwanego późniejszego procesu zamykania kopalni.

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Explosion testing of a polycarbonate safe haven wall

Perry K. A., Meyr R. A.

Archives of Mining Sciences

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2016

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Vol. 61, no. 4

809--821

EN

The MINER Act of 2006 was enacted by MSHA following the major mining accidents and required every underground coal mine to install refuge areas to help prevent future fatalities of trapped miners in the event of a disaster where the miners cannot escape. A polycarbonate safe haven wall for use in underground coal mines as component of a complete system was designed and modeled using finite element modeling in ANSYS Explicit Dynamics to withstand the MSHA required 15 psi (103.4 kPa) blast loading spanning 200 milliseconds. The successful design was constructed at a uniform height in both half-width scale and quarter-width scale in the University of Kentucky Explosives Research Team’s (UKERT) explosives driven shock tube for verification of the models. The constructed polycarbonate walls were tested multiple times to determine the walls resistance to pressures generated by an explosion. The results for each test were analyzed and averaged to create one pressure versus time waveform which was then imported into ANSYS Explicit Dynamics and modeled to compare results to that which was measured during testing for model validation. This paper summarizes the results.

PL

W następstwie poważnych wypadków w kopalniach, w roku 2006 MSHA uchwaliła Ustawę Górniczą na mocy której wszystkie kopalnie zobowiązane zostały do wyznaczenia odpowiednich stref bezpieczeństwa dla uniknięcia w przyszłości ofiar śmiertelnych wśród górników uwięzionych w kopalni w przypadku katastrofy uniemożliwiającej ucieczkę. Zaprojektowano ścianę ochronną wykonana z poliwęglanów zabezpieczającą strefę bezpieczeństwa w kopalniach podziemnych, jako element całego systemu zabezpieczeń. Ścianę zaprojektowano i modelowano w oparciu o metodę elementów skończonych z wykorzystaniem pakietu ANSYS Explicit Dynamics. Według wymogów MSHA ściana winna wytrzymywać ciśnienia 15 psi (103.4 kPa) w trakcie najsilniejszej fali wybuchu trwającej 200 milisekund. Odpowiedni projekt wykonano w odpowiedniej skali: połowie i ćwierci wysokości, jako obiekt jednolity. Modele zweryfikowane zostały przez badaczy z Uniwersytetu w Kentucky, z wykorzystaniem odpowiedniego tunelu testowego. Ściany wykonane z poliwęglanów zostały wielokrotnie przebadane aby określić ich wytrzymałość na ciśnienia powstające w trakcie wybuchu. Wyniki każdego z testów zostały przeanalizowane i uśrednione a otrzymany przebieg ciśnienia w funkcji czasu został zaimportowany do pakietu ANSYS Explicit Dynamice i zamodelowany, tym samym umożliwiając jego porównanie do wyników pomiarów wykonanych w ramach walidacji modelu. W niniejszej pracy zestawiono uzyskane wyniki prac.