Rock dust

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In mining, rock dust (also rock dust) is the name given to minerals made from limestone , dolomite or clay slate that are crushed to dust . The rock dust is used to fight pit fires , in the construction of rock dust barriers and to scatter rock dust . The rock dust must meet certain test regulations of the mining authority .

Requirements for the rock dust

In order for the rock dust to work at all, it has to be very finely ground. In the sense of the mining ordinances, only dust with a certain fineness counts as rock dust. The dust must be so fine that it can pass through a wire mesh with 144 meshes per square centimeter. Half of the dust has to be even finer so that it goes through a No. 200 fabric with 5840 meshes per square centimeter. Furthermore, the dust may contain a maximum of three percent by weight of combustible components. In order for the rock dust to remain airworthy in the long term, it must not absorb water from the weather or stick together. In addition, the rock dust must be of such a nature that it is harmless to the health of the miners . For this reason, rock dust with a particle size of less than 20 micrometers may contain 10 percent by weight and with a particle size of less than five micrometers five percent by weight of silica .

Mode of action

The rock dust can reduce the flammability of coal dust . This is because rock dust has the property of absorbing large amounts of heat. If the rock dust is introduced into a flame, the rock dust particles are strongly heated. As a result, the heat is withdrawn from the flame. As a result, the hot coal dust and the explosion flame are cooled below the ignition temperature in the event of an explosion . As a result, the flames are extinguished. The effect of the rock dust is all the more powerful, the denser the extinguishing dust cloud is. If the rock dust contains more, larger components, it cannot fully develop its effect.

literature

  • Mining Lexicon . In: Hans Grothe, Hermann Franke (Ed.): Lueger Lexikon der Technik . 4th completely revised and expanded edition. tape 4 mining. Deutsche Verlags-Anstalt, Stuttgart 1962, p. 257 .

Individual evidence

  1. ^ A b Ernst-Ulrich Reuther: Textbook of mining science. First volume, 12th edition, VGE Verlag GmbH, Essen 2010, ISBN 978-3-86797-076-1
  2. ↑ a b c d e f Fritz Heise, Fritz Herbst: Textbook of mining studies with a special focus on hard coal mining. First volume, fifth improved edition, published by Julius Springer, Berlin 1923, p. 490ff
  3. ^ Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7
  4. ^ A b Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962
  5. ↑ Standing committee for operational safety and health protection in hard coal mining (ed.): Flammable dusts . Doc. No. 3709/68 d, Luxembourg April 26, 1968, pp. 20-23
  6. ↑ K. Hatzfeld: The development of measures to combat coal dust . In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Dortmund Upper Mining District (Ed.), No. 44, 61st year, October 31, 1925, pp. 1385–1398
  7. ↑ a b F. Friedensburg: The fight against coal dust explosions by rock dust and the implementation of this process in English coal mining . In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Upper Mining District Dortmund (Ed.), No. 6, 49th year, February 8, 1913, pp. 201–209
  8. ↑ C. Beyling: Experiments with rock dust to combat mine explosions, carried out in the test section of the Knappschafts-Berufsgenossenschaft in Derne . In: Glückauf, Berg- und Hüttenmännische magazine. Association for Mining Interests in the Upper Mining District Dortmund (Ed.), No. 25, 55th year, June 21, 1919, pp. 457–466