Remaining pillar

As residual pillars , also remaining festivals or Kohleninsel called, are in mining not mined a part flözartigen deposit referred. These seams have only a small circumference and are surrounded on at least three sides by the old man . Remaining pillars have a detrimental effect on the mining of parts of the deposit located in the hanging wall and lying on the ground .

Basics

When coal is extracted , parts of the deposit remain, depending on the extraction method . These coal islands that remained between the individual mining fields now support the remaining part of the deposit like a pillar on a small area. As a result, the mountain above the pillars remains in its original position, although the hanging wall around the pillar sinks down to the surface . The pillars loaded in this way must not only bear the weight of the vertical hanging wall layers but also the weight of the area adjacent to them. The pillar now transfers this high load to the layers in the lying area via its small base area. As a result, zones with increased rock stresses form both in the lying area and in the hanging wall and also within the pillar . The bank-level compression pressure in the hanging and lying walls increases the convergence in the area of the remaining pillar . Along the boundary of the coal island is a 10-30 meter wide zone in which the additional pressure from the old man acts on the pillar. This additional pressure fluctuates within wide limits and can still be noticeable over 200 meters below the point of impact. In the case of very narrow pillars, a pressure maximum can develop in the middle of the remaining pillar. The smaller the pillar, the greater the pressure maximum. However, the pressure absorption of each remaining pillar is not infinite, but is limited by the strength of the coal.

Effects

Remaining pillars have a number of negative effects on further dismantling. By the formation of zones of increased rock stress it can cause in the affected areas under certain conditions, rock bursts come. Due to the increased mountain pressure , there is increased methane outgassing . Furthermore, under certain conditions, the coal in the remaining pillars can spontaneously ignite . This occurs in particular in thick coal seams with strong bad and loosening paired with changing coal hardness . The most critical point here is around five to ten meters below the upper mining section . Since the pressure uptake of the remaining pillar is limited, if the pressure increases further, the coal face will leak. The coal is widely used in fine-grain or powder form from the coal face ejected. This is favored by the further weakening of the pillar due to the fire. Ultimately, the seam fire can develop into a pit fire .

Dismantling of remaining pillars

Because of their negative effects, remaining pillars should be dismantled as completely as possible. However, the extraction of remaining pillars is not easy. This is due to the pressure on the pillar. In order to break down the pillars, he must starting from the old man toward the unverritzten seam in Verhieb be taken. The miner must take the pillar in such a way that the mining front is always parallel to the narrowest side of the pillar. With this procedure, the old extraction pressure zones are crossed in the shortest possible way.

Individual evidence

^ ^A ^b ^c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
↑ ^a ^b ^c ^d ^e ^f ^g Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962, pp. 217, 413-414.
↑ ^a ^b ^c ^d ^e Helmut Kratzsch: Bergschadenkunde. 5th updated and revised edition, Papierflieger Verlag GmbH, Clausthal-Zellerfeld 2008, ISBN 3-00-001661-9 , pp. 117–119, 222–224, 747–749.
↑ ^a ^b ^c ^d ^e ^f ^g ^h Carl Hellmut Fritzsche: Textbook of mining science. Second volume, eighth and ninth completely revised edition, Springer-Verlag, Berlin / Göttingen / Heidelberg 1958, pp. 199, 242, 277, 367–368.
↑ Investigations of the rock pressure effects in seams and rock stretches . In: Commission of the European Communities (Ed.): Research books coal. No. 22, Gebirgsdruckforschung Synthesis report I of the Steinkohlenbergbauverein, Luxemburg 1969, pp. 9-10.
↑ ^a ^b ^c P. Cabolet: Development and prevention of pit fires through self-ignition of coal . In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Upper Mining District Dortmund (Ed.), No. 50, 75th year, December 16, 1939, pp. 953–962.

[Quelle_1-1] A ^b ^c Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .

[Quelle_2-2] ↑ ^a ^b ^c ^d ^e ^f ^g Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962, pp. 217, 413-414.

[Quelle_3-3] Helmut Kratzsch: Bergschadenkunde. 5th updated and revised edition, Papierflieger Verlag GmbH, Clausthal-Zellerfeld 2008, ISBN 3-00-001661-9 , pp. 117–119, 222–224, 747–749.

[Quelle_4-4] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Carl Hellmut Fritzsche: Textbook of mining science. Second volume, eighth and ninth completely revised edition, Springer-Verlag, Berlin / Göttingen / Heidelberg 1958, pp. 199, 242, 277, 367–368.

[Quelle_6-5] Investigations of the rock pressure effects in seams and rock stretches . In: Commission of the European Communities (Ed.): Research books coal. No. 22, Gebirgsdruckforschung Synthesis report I of the Steinkohlenbergbauverein, Luxemburg 1969, pp. 9-10.

[Quelle_5-6] P. Cabolet: Development and prevention of pit fires through self-ignition of coal . In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Upper Mining District Dortmund (Ed.), No. 50, 75th year, December 16, 1939, pp. 953–962.