Expansion construction

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Expansion construction using fire-setting
Expansion in the former "Einheit" pebble mine in Elbingerode

The expansion is a mining method in underground mining. The process belongs to the chamber-like construction. It is therefore a variant of the chamber construction in which, after mining, the layer boundaries between the deposit and the adjacent rock form the boundary and support pillars of the resulting chamber (in this case widening ) as mountain forts . The expansion construction is used for massive , consistently buildable deposits.

history

One of the oldest and most widespread application of Weitungsbaus was noted by Georgius Agricola described fire setting , which for. B. was used in the Ore Mountains until the 19th century. The rock was heated by burning wood (later also coke) in order to make it brittle and cracked on the surface during the subsequent cooling. (See principle of temperature weathering ) This expansion construction method was used in particular in tin mining areas , as here the ore often does not occur as a dike , but as a continuously finely mineralized stock .

Basics

Basically, a distinction is made between two types of expansion building, expansion building from bottom to top and expansion building from top to bottom. The precondition for the expansion construction is a high stability of the adjacent rock. In addition, the deposit must be of sufficient thickness and dip greater than 55 gons. The thickness of the deposit should be six meters or more. The expansion construction can also be used in deposits that have an irregular shape. This is because the widenings adapt better to the irregularities of the deposit. In the case of a steep deposit, the boundaries to the hanging and lying walls , i.e. the joints of the extraction chamber, would correspond to the roofs and floors of the extraction chamber in the case of flat deposits . One form of expansion building on irregularly distributed deposits is called multi-storey building. It leaves widenings that can be arranged horizontally and / or vertically offset from one another. The advantage of the expansion building is that it does not require a large apparatus . Another advantage is the larger mining area compared to other mining methods.

Even if the assumption is obvious, the term widening does not make any statement about the actual size of the cavity created. The dimensions of the widenings are limited by the thickness of the buildable deposit parts and the strength of the adjacent rock. During regular expansion work in the Altenberg region, expansions with a base area of ​​eight by ten meters were created. These were then created one behind the other. But there were also widenings with a base area of ​​900 to 1000 square meters. As a rule, the resulting widenings are significantly larger than, for example, in roof construction , longwall construction or butt construction . In the tin mining areas of the Eastern Ore Mountains around Altenberg and Zinnwald-Georgenfeld , the expansion work left numerous cavities with a diameter of up to 20 m. Individual widenings were over 40 m high and over 50 m wide at the bottom. The so-called cruiser width reached a height of 60 to 90 meters. In contrast, some of the pillars were only a few meters thick. In salt mining, the widenings could reach a height of up to 70 puddles and a diameter of 30 to 50 puddles.

The procedure

In this degradation process are initially on each sole high and wide distances , so-called augmentations, ascended , located in the right angle cross each other. Pillars are left to support the hanging wall; these pillars stand on top of each other on the individual floors and are smaller than in the case of multi-storey buildings . These pillars are left to ensure the stability of the cavities. If possible, they are placed in areas where the rock has little usable mineral. Depending on the thickness of the deposit, several levels are created one below the other in this way. The miner allows up to four meters of rock to stand between the bottom of the upper widening and the roof of the lower widening . These spaces are called floating. The size of the widenings vary depending on the mineral and can be up to ten meters wide and almost the same height. The pillars are about eight meters wide and up to 50 meters long. If the mining sites are too dense and irregular in a confined space, the pillars between the widenings can, however, be weakened to such an extent that collapses and pinging occur. With valuable minerals or fractured rock single pillars are mitgewonnen and as a substitute pillars of tailings created. However, these pillars will only be won at the end.

There are three different ways of working in the widenings and how the widenings are created. First of all, there is the possibility of leaving the gained masses in the widening until the widening is completely finished. This has the advantage that the miners use the debris to stand on. The entire pile is then removed later. In the second way of working, the widening is completely spanked. In the third working method, offset is introduced into the widening sole. The backfill is either generated from the side rock that is extracted during extraction , or it is extracted from above ground. In the offset, rollers are also guided upwards, through which the mined mineral is then conveyed to the lowest level. Due to the offset, the widening fills up from below and the sole moves further upwards. Instead of the mountain offset, concrete can also be used, which is introduced into the widening after the widening has been cleared. The dismantling direction is from bottom to top for all working methods.

particularities

If it is determined in the case of a deposit that the mining cannot be carried out effectively from the bottom up, the mining of the deposit can also be carried out from the top to the bottom. This variant of the expansion construction differs from the other variant in the direction of the mining. First of all, cross-passages that rise upwards are driven from the lower level to the end of the widening. The dismantling and thus the creation of the widening takes place from top to bottom. A prerequisite for this mining process is a long shelf life and stability of the deposit. If this method is used in insufficiently stable rock, the widening can collapse before it is completely created. Another option, which is often used in steep deposits, is the form of expansion construction known as funnel construction. Here, the warehouse is first driven on two levels, an upper and a lower level that is up to 200 meters lower. These two levels are then connected to one end of the deposit with a spiral section . Starting from the spiral section, partial floors are then driven at a distance of 20 to 25 meters. The material to be mined is then recovered in the form of a pen. On the lowest level, the extracted mineral is removed using a scraper and then conveyed away . So that the mountains remain stable, ten to twelve meter thick mountain forts are left every 80 to 100 meters. The dismantled parts of the deposit are then refilled with an offset.

application

Examples of expansion can be found primarily in the tin deposits in the Ore Mountains. In Altenberg , Seiffen and Geyer , larger pings testify to the medieval and modern expansion building by setting fire. But the ore was also mined in the Rammelsberg near Goslar in the expansion process. Expansion construction was also used in the Wieliczka Salt Mine . The expansion was also used in the Eisenstein camps on the Büchenberge, on the Eisenstein stocks in Sweden, on the lead stocks in Offenbanya and Rodnau and in the salt domes in Bochnia. Expansion construction is also used to mine lignite in civil engineering . Further examples can be found in the limestone deposits of Lengefeld and Rabenstein and in ore mining in the Eifel.

Individual evidence

  1. ^ A b c d Emil Stöhr, Emil Treptow : Basics of mining science including processing. Spielhagen & Schurich publishing bookstore, Vienna 1892.
  2. ↑ a b c Ernst-Ulrich Reuther: Introduction to mining. 1st edition. Glückauf Verlag, Essen, 1982, ISBN 3-7739-0390-1 .
  3. ↑ a b c d e f Albert Serlo: Guide to mining science. First volume, fourth revised and up to the most recent edition supplemented. Published by Julius Springer, Berlin 1884.
  4. ↑ a b c d e Ronald Symmangk: Some remarks on setting fire and its use in the Ore Mountains . In: Association of Friends of Mining in Graubünden. (Ed.): Berg-Knappe. No. 104, Volume 28, April 2004, pp. 40-43.
  5. ^ Georg Agricola: Twelve books on mining and metallurgy. in commission VDI-Verlag, Berlin
  6. ↑ a b c d Gustav Köhler: Textbook of mining science. 6th improved edition. Published by Wilhelm Engelmann, Leipzig 1903.
  7. ↑ a b Alexander Maass: The importance of mining and its socio-economic structures in the Neolithic. Dissertation. Albert Ludwig University of Freiburg, Freiburg 2005.
  8. ^ A b c d Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition. Springer Verlag, Berlin / Göttingen / Heidelberg 1962.
  9. ↑ a b c d e Emil Stöhr: Catechism of Mining Studies. Lehmann & Wentzel bookstore for technology and art, Vienna 1875.
  10. ↑ E. Frey (Ed.): Luegers Lexicon of the entire technology and its auxiliary sciences. First volume A to drilling, third completely revised edition. German publishing company, Stuttgart / Berlin / Leipzig 1926.
  11. ^ A b Association of Scholars, Artists and Experts (ed.): The sciences in the nineteenth century, their point of view and the results of their research. First volume, Romberg's Verlag, Leipzig 1856.
  12. ↑ Wolfgang Reichel, Manfred Schauer: The Döhlener basin near Dresden, geology and mining. Saxon State Office for Environment and Geology (LfUG), Saxoprint, Dresden, Dresden 1983, ISBN 3-9811421-0-1 .
  13. ↑ a b c d Friedrich Freise: History of mining and metallurgical engineering. First volume: Antiquity. Published by Julius Springer, Berlin 1908.
  14. ↑ a b Dieter D. Genske: Engineering Geology Basics and Application. Springer Verlag, Berlin Heidelberg 2006, ISBN 3-540-25756-X .
  15. ↑ Edward Baustark: cameralistic Encyclopedia, Handbook of cameralistics and its literature . Printed and published by Karl Groos, Heidelberg / Leipzig 1835.
  16. ↑ G. Dall'Armi, M. Lovitt, M. Roper: Olympic Dam . In: Dynamit Nobel AG (Ed.): Nobel Hefte. December 2005, pp. 61-64.
  17. ^ Wirtschaftsvereinigung Bergbau eV: The mining manual. 5th edition. Glückauf Verlag, Essen 1994, ISBN 3-7739-0567-X .
  18. ^ Emil Treptow: Mining including quarrying and precious stone extraction. Publishing house and printing by Otto Spamer, Leipzig 1900.
  19. ^ Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition. Glückauf Verlag, Essen 1988, ISBN 3-7739-0501-7 .

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