Search the digital library catalog

Abstract: With in-depth geomechanical analyses of sub-level mining using the longwall mining method we can identify the relationships between the physical and mechanical parameters of geological materials, depending on the intensity of the coal extraction. The extent and the intensity of the mining operations impose impacts on the stresses and cause deformation changes in the rocks and in the coal seams on a broader area of excavations. The method of sub-level coal extraction requires multi-caving of the hanging-wall layers, which are recompressed, and in sub-level stoping each represents a hanging wall. The repeating processes of caving-in and compression, from the aspect of the theory of plasticity, have been relatively little researched because every such process brings about structural changes in natural, multi-caved and recompressed materials in the hanging wall. The intensity of the coal extraction has direct impacts on the surrounding and distant mining areas. Extensive stress and deformation changes in the surrounding area, and in the mine, represent a safety hazard for the employees, since the supporting system in the mine roadway could collapse. Therefore, a controlled excavation of the coal, and a good understanding of the geomechanical properties of all the materials and processes involved, is extremely important for planning and managing economic production, while also ensuring safe mining operations. A numerical model that allows for in-depth analyses of the geomechanical processes that occur in the hanging wall, the footwall and in the coal seam during sub-level coal excavation, is broadly applicable and highly relevant for analysing the intensity and the level of the caving processes in sub-level coal mining, and for making realistic plans for coal excavation with workers’ safety in mind.
Keywords: coal mining, sub-level mining method, longwall coal mining method, carving processes, finite-difference method, FLAC, mathematical model
Published in DKUM: 11.06.2018; Views: 1117; Downloads: 96
Full text (589,19 KB)
This document has many files! More...

Abstract: This article presents the evolution of the conditions of state aid admissibility to the coal industry, starting with legal regulations within the European Coal and Steel Community, the European Community, and now the European Union. The thesis was formulated that, in connection with the expiry on 31 December 2010 of Council regulation No. 1407/2002, on the basis of which the European Commission allowed aid for the national mining industry in different member states in the period before the onset of the financial and economic crisis, the immediate cause of introduction of the next regulation for mining state aid in the form of Council Decision 2010/787/EU on state aid to facilitate the closure of uncompetitive coal mines was the increasing intensity of the aid for the mining industry in recent years.
Keywords: financial and economic crisis, state aid, coal mining sector, legal regulations, the European Union
Published in DKUM: 14.11.2017; Views: 1412; Downloads: 204
Full text (297,71 KB)
This document has many files! More...