22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Underground hard coal mine flooding control as a factor for limiting methane emissions to the atmosphere and for enabling its utilisation

24 Sep 2019, 16:00
1h
Trade Fairs and Congress Center (FYCMA)

Trade Fairs and Congress Center (FYCMA)

Av. de José Ortega y Gasset, 201 29006 Malaga, Spain
Poster Topic 5 - Tools, methods and models to study groundwater Poster with refreshments

Speaker

Ms Katarzyna Niedbalska (Central Mining Institute, Laboratory of Mining and Environmental Hydrogeology)

Description

Thus far, the condition of hard coal mining in the USCB reflects the general global trends, which prefer to limit the extraction of hard coal. Therefore new and unmined deposits are practically not opened out, whereas the extraction in active mines is either limited or nearing conclusion. Processes related to the decommissioning of mines and their total or partial flooding are currently widespread both in Czechia as well as in Poland. On the one hand, this process influences the ejection of methane towards the surface from the lowest-situated and typically methane-rich coal beds and workings, but on the other hand it may limit the desorption of methane and its long-term emission to the atmosphere through the restoration of static water resources and the renewed water saturation of the rock mass. Therefore the authors have concluded that the course of the mine flooding process should be forecast with the greatest precision. The rate of working flooding and methane ejection towards the surface can be regulated by controlling the drainage process conducted during mine flooding. It is beneficial to limit the rate of mine flooding in order to prevent the compression and non-concentrated outflows of mine gases with intensities that may result in significant methane emissions and general hazards on the surface. Yet on the other hand, limiting the rate at which water levels increase in the gobs will result in the removal of the majority of gas from post-mining caverns, and will simultaneously limit their emission and desorption from coal beds through the water saturation of the rock mass and the blocking of the routes of gas migration. This is significant in a hydrogeologically unconfined area where partial flooding of only the deep and methane-rich coal beds can be considered beneficial due to the limitation of the influence on climate change. As for mines in hydrogeologically confined areas, in order for methane emissions, including uncontrolled emissions, to cease completely, the flooding would have to concern the entire coal-bearing formation in the area of the mine. This often constitutes a significant limitation to the use of deposits adjacent to the flooded mine. On the other hand, maintaining the water table and the partial flooding of a methane-rich mine in the hydrogeologically confined area enables the planning of the controlled capture of methane and its utilisation. This also makes it possible to avoid uncontrolled releases of methane to the surface and the atmosphere, and allows the selection of the means for methane capture during the degasification processes of deposits, which is certainly beneficial with regard to climate change and the safety of adjacent mining activities.

Primary authors

Prof. Nada Rapantova (3VŠB-Technical University of Ostrava, Department of Geotechnics and Underground Engineering) Prof. Przemysław Bukowski (Central Mining Institute, Laboratory of Mining and Environmental Hydrogeology) Prof. Salvador Ordóñez (University of Oviedo, Department of Chemical and Environmental Engineering) Prof. Mirosława Bukowska (Central Mining Institute, Laboratory of Mining Geomechanics) Ms Katarzyna Niedbalska (Central Mining Institute, Laboratory of Mining and Environmental Hydrogeology) Dr Petr Hemza (Green Gas DPB, a.s.) Dr Ireneusz Grzybek (Central Mining Institute, Laboratory of Mining and Environmental Hydrogeology)

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