Sinkhole

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Sinkworks in the Bex salt mine

A sink works , also called Laugwerk , normal works or simply works , is a plant for the extraction of table salt in wet underground mining . It consists of an in rock salt leading or rock salt Mountain hewn cavity with fresh water is filled. By the fresh water, the salt is out of the rock leached and forms with the water brine . The saturated brine is pumped out and in salt mines to saline boiled. Today, wet salt mining is no longer carried out in sinks, but in drilling and flushing works .

Basics

Sinking is one of the oldest methods of extracting salt from underground salt domes . The process is similar to the creation of natural brine springs . The solubility of the salt in water is used to produce salt. The method is or was used in most salt mines in the Alps, until some of the following salt pans were abandoned or the changeover to the drilling fluid process . B. in Berchtesgaden , Hallein , Altaussee , Bad Ischl or the Swiss salt pans in the Hasel Mountains . The Haselgebirge are partially saline mountains mixed with gypsum , clay and anhydrite . The salt is extracted from this contaminated salt store by leaching it from the rock with added water. Which is then from the brine salt in the salt works excreted. In addition to the conventional method of extracting brine by means of sinking works, since the mid-1960s brine has been extracted by means of drilling flushing works. The process is more economical than the conventional manufacturing process.

Sink types

A sinkhole is an underground, spatially defined chamber. The side walls of this chamber referred to the miner as elm or plant elms . The lower boundary surface of the sink unit is called the bottom . The miner calls the roof of the sinkhole heaven . A basic distinction is made between two types of sink units, the scoop units and the discharge units. The main difference between the two types is the way the brine is obtained . Buckets are the oldest lye works. A distinction is made in the pumping stations between the simple pumping station and the pumping station with pütte . In these plants, the saturated brine is scooped up using buckets or barrels and then taken for further processing. Drainage works are a technical further development of the pumping station. With them, the saturated brine is drained through an outlet for further processing. This technique has been used in the salt mines since the beginning of the 17th century. With the development of the drainage works, salt extraction by means of a pumping station was no longer used.

Creating the work

First of all, the deposit must be prepared . For this purpose, several superimposed tunnels or routes are driven in the deposit . These main lines are tonnlägige shafts interconnected. Then, starting from the main line, a right - angled cross passage is driven in such a way that the location of the line is about 70 to 80 laughs away from the main line. Starting from this cross passage, several intersecting locations between one and eight pools in length are excavated in such a way that the base area is divided into pillars, similar to the construction of the location . The individual cross passages and locations are created with a height of two meters. The different lengths of the sites create an approximately elliptical base. Of an overlying sole is an obliquely incident distance that the Bergmann Ankehrschurf or Ankehrschachtricht calls ascended up to the cross passage. In the same way, several sinkholes are created on each level. A safety pillar remains between the individual sinks .

The main route is then closed with a dam construction at the ends of the individual cross passages. This dam construction, which is also known as the weir, is placed in such a way that it is still possible to drive over the sinks above. Pipes with closable taps are installed in the weir, through which the brine can later be drained. The fresh water is then introduced into the cavity via the return chute . The Sinkwerke are always first on the upper sole created, then lower on the. Sinkworks that are built using this process can reach a height of up to 30 meters over the years .

The weir

The weirs are constructed in different ways, there are standing or lying weirs, but also combinations of both types. A weir ( Wöhre in Austria ) is often built from two dams. The dams are placed in the cross passage leading to the sink unit so that the rear dam is located directly at the transition between the cross passage and the sink unit. The front dam, also called the wing or wreath, is two laughs away from the rear dam. The space between the two dams, which is two laughs long, is called the long furnace. The long furnace is protected against leaching with a watertight lining. The long furnace and the two dams are collectively referred to as the weir. Since the dams can become leaky or loose after a long period of use of the sink system due to obsolescence, the cross passage in which the weir system was installed is opened for so long that a new weir can be built. Since the weir has to withstand a certain pressure, attention is paid to the greatest possible strength and safety when constructing the weir. In addition, the weir is constructed in such a way that the brine can run off unhindered after the weir is complete.

used material

Wood and special clays are used as materials for the dams and the lining of the long furnace. Depending on the construction, square timbers with an edge length of 10 to 14 inches are used. The clay or Lette gained during the driveway is used for sealing . The Lette is crushed and mixed with saturated brine in a container. This mixture is left to stand until the Lette no longer draws brine. Then balls are formed from the pulp, which are then dried in the sun. This process is necessary in order for the Latvian to be more resistant to leaching. The clay recovered is mixed with leach residues from old sinks and also shaped into balls and dried.

The individual constructions

Depending on the location and the material used, a distinction is made between the following weir dams:

  • Lettendammwehr (Lettendammwöhre)
In the case of the Lettendamm weir, an approximately 8 inch deep slot is first created at the joints and in the area of ​​the roof and bottom  . A wooden construction made of 12 to 14 inch square timber is built into the slot, which has the shape of a whole door frame . This construction is fastened in the middle with a tension bolt. Behind this first door frame construction, a second door frame construction made of 10 to 12 inch square timber is created. In both constructions, wood is used in which a 7 inch wide fold was previously worked in the middle. The constructions are installed one behind the other in such a way that the door frame construction with the slightly thinner square timber is in the direction of the sink unit. The Letten frame created in this way is stabilized with so-called Letten leaves and wooden nails. 7 inch planks are then inserted into the folds. The entire construction is then sealed with Letten. For this purpose, the Latvians are pounded into place with a so-called Lat iron. Latvian dams are suitable for salt mountains, as the Latvians soak up moisture and swell and thus seal the dam well, in plaster they are less suitable.
  • Stockdammwehr (Stockdammwöhre)
The stock dam weir is constructed in a similar way, but here two dams are created, each half as wide as the individual Lettendamm. The wooden structures are installed so firmly that, due to the tension under which the timbers are placed, they are sufficiently tight even without additional sealing by means of a Lette. Any leaks are eliminated by wedging the wood.
  • Püthendamm weir (Püthendammwöhre)
At the Püthendamm weir, the dams are installed in a horizontal position. The advantage of these weirs is that they cannot be cut around by fresh water. The long furnace at these weirs cowardly attached. For this dam, too, 12 to 14-inch square timbers are used, which are assembled from bundled timber and so-called swelling timber to form a special wooden structure. To seal, the joints are pickled, clipped and cemented from the outside.
  • Püthenstockdammwehr (Püthenstockdammwöhre)
The Püthenstock dam weir is constructed in a similar way to the Püthendamm weir.

The water inlet

In conventionally constructed sink units, the first water inlet is set so that the water does not initially reach the roof of the sink unit. The miner describes the process of letting fresh water into the sinkhole as sweeping. This is necessary so that the individual pillars are first leached. When the pillars are exhausted, the sinkhole is filled with water up to the roof. The period in which this process takes place is known as the arrival period or filling period . By leaching out the rock, impurities such as sand, lime, gypsum and clay are also removed. Since they do not dissolve in the water, these impurities gradually sink to the bottom of the sinkhole. The concentration of the brine increases continuously.

For the further procedure, a distinction is made between two processes: intermittent (interrupted) washing and continuous (uninterrupted) washing.

With intermittent watering, no more water is added after the first complete filling of the sink unit. As soon as the brine is saturated, it is drained into so-called siphon boxes after prior clarification. Now the bottom of the sinkhole is cleaned from the laist and the weir is revised, if necessary. Then you fill the sink with new fresh water. In the course of use, the diameter of the sink unit expands from 30 to 40 meters to 100 meters.

With continuous watering, fresh water is constantly admitted to the rear of the sink unit and brine is discharged to the same extent via the pipes. The height of the water level must be checked regularly so that there is not too much or too little water in the sink unit. Care is taken to ensure that the brine always touches the roof. As a result, the fresh water only acts in the sky, so that the leaching takes place only there and not on the elms. The miner calls this procedure also sky burn. If too little water was kept in the sink, the water would only attack the elms and widen the sink. If too much water is introduced into the sink, it will penetrate too deeply into the roof. This in turn causes the layers to be detached and fall onto the sole and not be used to increase the salt content of the brine. The miner then describes this as the sky above. With this mode of operation, the roof of the sinks reaches an area of ​​up to 10,000 m².

business

Sinkworks can be used between five and ten years. The operation of a sinkhole ends as soon as it has reached the level from which it is operated. How often a sink unit can be started with intermittent watering depends on the salinity of the deposit and the size of the sink unit. Smaller sinks are started several times a year, larger sinks are often up to a year, sometimes longer. Regulated water management is important for optimal use so that not too many pillars remain that are not depleted. Each sinkhole must be designed in such a way that it is connected to the main lines. So that the mountains do not collapse, no sinkholes may be built on top of each other. With an optimal design, the sink unit grows upwards by one centimeter every day.

Individual evidence

  1. ↑ a b c d e f g h Heinrich Veith: German mountain dictionary with documents. Wilhelm Gottlieb Korn, Breslau 1871.
  2. ↑ a b Kurt Thomanek: Fascination Salt Worlds. Salzburg - Hallstatt - Altaussee, pp. 24-27.
  3. ↑ a b c d e f g h i j k l m n F. A. Fürer: Salt mining and salt mining. Printed and published by Friedrich Vieweg and Son, Braunschweig 1900, pp. 495–507.
  4. ↑ Moritz Ferdinand Gaetzschmann: Collection by mining expressions. Craz & Gerlach Publishing House, Freiberg 1881.
  5. ↑ a b salt . In: Meyers Großes Konversations-Lexikon . 6th edition. Volume 17, Bibliographisches Institut, Leipzig / Vienna 1909, pp.  495–498 ..
  6. ^ Heinrich Otto Buja: Germany's mineral treasures. Geology-Exploration-Extraction, 2nd edition, Verlag Cornelius GmbH, Norderstedt 2010, ISBN 978-3-7392-7612-0 , pp. 255-256.
  7. ↑ a b c R. Holnsteiner: Hydrogeological Risks in Mining. In: Contributions to Hydrogeology. Graz 2012, pp. 155, 156.
  8. ^ A b Carl Hellmut Fritzsche: Textbook of mining science. Second volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1962, p. 330.
  9. ↑ a b Carl Hartmann (Ed.): Conversations-Lexicon of mining, metallurgy & salt works and their auxiliary sciences. Fourth volume QZ, Buchhandlung J. Scheible, Stuttgart 1841, pp. 76-86.
  10. ↑ a b Kurt Thomanek: Fascination Salt Worlds. Salzburg - Hallstatt - Altaussee, pp. 24-27.
  11. ↑ a b c Salt from the Berchtesgadener Land. ( Memento of March 4, 2016 in the Internet Archive ) (last accessed on October 29, 2012; PDF; 1.4 MB).
  12. ↑ Hans-Jürgen Holtmeier (Ed.): Significance of sodium and chloride for humans. Analytics - Physiology - Pathophysiology - Toxicology and Clinic, Symposium of the Society for Minerals and Trace Elements e. V. at the University of Hohenheim, Springer Verlag, Berlin / Heidelberg 1992, ISBN 978-3-642-77341-9 , p. 74.
  13. ^ A b c d Carl von Scheuchenstuel: Idioticon of the Austrian mountain and hut language. For a better understanding of the Austrian mountain law. kk bookseller Wilhelm Braumüller, Vienna 1856.
  14. ↑ a b c d Raimund Bartl: 500 years of the Berchtesgarden salt mine. In: VKS e. V. (Ed.): Potash and rock salt. 2nd edition, Berlin 2017, ISSN 1614-1210, pp. 46–56.
  15. ↑ a b c Gustav Köhler: Textbook of mining science. Sixth improved edition, published by Wilhelm Engelmann, Leipzig 1903, pp. 333–337.
  16. ↑ a b c d e f g h i j Wilhelm Leo: Textbook of mining science. Printed and published by G Basse, Quedlinburg 1861, pp. 347–351.
  17. ↑ a b c Carl Hartmann: Handbuch der Bergbaukunst. Second volume, Verlag Bernhard Friedrich Voigt, Weimar 1852., pp. 78–84. (on-line)
  18. ^ A b c Emil Stöhr, Emil Treptow : Basics of mining science including processing. Spielhagen & Schurich publishing house, Vienna 1892, pp. 123–124.
  19. ^ A b c Heinrich Lottner, Albert Serlo: Guide to mining history. First volume, published by Julius Springer, Berlin 1873, pp. 423-429, OCLC 257925327 .
  20. ↑ a b c d Michael Kopf: Description of the salt works in Hall in Tyrol. Printed and published by G. Reimer, Berlin 1841m, pp. 120–134.
  21. ↑ Carl Hartmann: Conversations-Lexicon of mining, metallurgy & salt works and their auxiliary sciences. Second volume, J. Scheible bookstore, Stuttgart 1840.
  22. ^ Albert Miller: The southern German salt mining represented in a technical relationship. Especially reprinted from the III. Volume of the yearbooks of the educational institute in Leoben, in Commission at Tendler and Comp, Vienna 1853, pp. 29–45.
  23. ^ A b c d W. FA Zimmermann: Chemistry for laypeople. Seventh volume, Verlag Gustav Hempel, Berlin 1861, pp. 352–361.
  24. ↑ Fritz Reinboth: Laboratory experiments on the formation of still water facets and lye blankets. In: Association of Austrian cave researchers (ed.): The cave. Journal of Karst and Speleology, DVR 0556025, Issue 1, Volume 43, Vienna 1993, ISSN 0018-3091, p. 6.
  25. ↑ Herbert Klein: On the history of the technology of alpine salt mining in the Middle Ages. In: Gesellschaft für Salzburger Landeskunde (Ed.) 1st Austrian Historians' Day publication, Vienna 1950, pp. 262–268.