Stetten Salt Mine

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Stetten Salt Mine
General information about the mine
Salt mine Stetten 03.JPG
General view from the north
Mining technology Chamber construction
Funding / year 500,000 t
Information about the mining company
Operating company Wacker Chemie
Employees approx. 70
Start of operation 1854
Funded raw materials
Degradation of Rock salt
Geographical location
Coordinates 48 ° 21 '11.9 "  N , 8 ° 48' 39.2"  E Coordinates: 48 ° 21 '11.9 "  N , 8 ° 48' 39.2"  E
Stetten Salt Mine (Baden-Wuerttemberg)
Stetten Salt Mine
Location of the Stetten salt mine
local community Haigerloch
District ( NUTS3 ) Zollernalb district
country State of Baden-Württemberg
Country Germany

The Stetten salt mine , often salt Stetten called, lies on the southern edge of the village Stetten in Haigerloch in Zollernalbkreis and is the oldest mining techniques depleting salt mine in Germany, which is still operational.

history

In 1850 the two principalities of Hohenzollern-Hechingen and Hohenzollern-Sigmaringen came to the Kingdom of Prussia . The background to this was the resignation of the two Hohenzollern princes as a result of the March unrest of 1848, as a result of which the previously concluded inheritance agreements between the principalities and Prussia came into force.

In view of the good yields from the salt pans of Sulz am Neckar , Wilhelmshall near Schwenningen , Rottenmünster in Rottweil and other salt pans in Bad Dürrheim and Bad Rappenau in the nearby Grand Duchy of Baden , the Prussian government felt compelled to search for natural resources in the newly acquired areas of Hohenzollern .

Ownership

Due to the merger with the Kingdom of Prussia, the exploration and operation of the salt works fell under the sovereignty of the Prussian state ( mining treasury ), which acted as owner. On February 15, 1924, the salt works became the property of Preussische Bergwerks- und Hütten AG , a predecessor of Preussag AG . Since the previous year, Dr. Alexander Wacker Gesellschaft für elektrochemische Industrie GmbH from Munich (today Wacker Chemie AG ) large quantities of rock salt from Stetten. The company needed the salt for the chlor-alkali electrolysis in its plant in Burghausen . Wacker Chemie leased the salt works on March 1, 1924, and bought it in October 1960. In 1960, in addition to the daily facilities, the mine included four pit fields with a total area of ​​8.8 km 2 . These extended over the markings of Stetten, Haigerloch, Gruol and Owingen in the former district of Hechingen (today Zollernalbkreis).

geology

The rock salt store is located in the mine field of the salt mine at a height of 320–370 m above sea ​​level , which corresponds to a depth of 80–130 m (below the surface). In this area, which has bearing a thickness m of 6-10. At 97–98%, the salt is very pure and therefore ideally suited for use as industrial salt or road salt .

The camp dips with an average of 2-3 degrees from northwest to southeast, faults occur in places . The hanging wall of the deposit is made of clay and dolomite stone . Immediately above the rock salt, this is followed by a 0.7–1.0 m thick layer of ribbon salt, which is called "clay salt" here. Underneath is the actual deposit made of coarsely chipped rock salt, which is up to 5 m thick - only this part, which contains only small amounts of additive, is dismantled. This area is followed by a 0.1 to 0.6 m thick anhydrite zone , including a further 3–4 m thick rock salt layer, which, however, is not mined due to its high clay and anhydrite content. The horizontal is formed by a 2-3 m thick layer of basic anhydrite (black-gray anhydrite), which is followed by an approximately equally thick layer of dolomite. The conclusion is a 7 m thick layer of marl clay , which is CO 2 -conducting in many places .

Exploration of the deposit

The search for mineral resources began in October 1852 with a test borehole. This borehole 1 was drilled 600 m southeast of Stetten and to the right, i.e. east, of the Eyach . The starting point was about 5 m above the river at a level of 450 m above sea level. In March 1853, at a depth of 123 m, the salt store was encountered, which at this point had a total thickness of 8.80 m. Another borehole was sunk in 1853 to check this, about 1.5 km west of the first location, opposite the confluence of the Stunzach and Eyach, at a level of 437 m above sea level. Here the salt store was already found at a depth of 77 m, but at this point it was only 2.25 m thick.

In the years 1944, 1965, 1973 and 2004 the extent of the salt deposit was checked with further exploratory drilling. The results of the measurements showed that there were enough supplies to continue operations.

The mining area was initially limited to the triangle where the Stunzach meets the Eyach. Today (2012) this extends to the east running Rötenbach (another tributary of the Eyach) and extends to about 5 km south of the shaft. The underground route network has a length of over 240 km (as of 2004).

Construction work 1854–1858

Site plan of the Stetten salt works near Haigerloch (around 1924)

At the beginning of March 1854, the sinking work for the shaft began . For this purpose, a point was chosen roughly in the middle between the two test bores. The place was to the left of the Eyach on a hill 12.5 m (449.54 m above sea level) above the river, so you could use the water power , but was safe from flooding. The first problems arose during the sinking when considerable water inflows occurred between 51 and 68 m depth, in the lower area of ​​the hanging dolomites of the Middle Muschelkalk . These went back later and the lining of the shaft made it possible to reduce them so that the remaining water could be pumped out.

When in December 1855, at a depth of 100 meters, unexpected drops of carbon dioxide occurred, the construction of the shaft was stopped. The shaft was filled and sealed to a depth of 98 meters. The carbon dioxide that was still escaping was intercepted and discharged through a pipe via the water solution tunnel leading to the Eyach . In the following period, the shaft was lined and the headframe and hoisting machine were erected above ground .

The shaft was created with a clear width of 3.20 × 4.80 m. The first brick lining in natural stone, executed in an elliptical cross-section , was about 70 cm thick in the lower area, further up it narrowed to 40 cm. The material came from the nearby quarry near Weildorf . At the end of the 19th century, the shaft installations had to be replaced for the first time and in 1920 the shaft wall was renewed. The previously wooden headframe was replaced by an iron headframe during renovation work in 1926, and a new electric hoist was installed. In addition, major repair work was carried out in the shaft in 1973.

The construction of the daytime facilities had already started in 1854, including the shaft house, the workshops, a salt mill and the energy supply, as well as residential buildings and a salt works . This construction work was completed in 1858 with the commissioning of the salt works. A large part of these massive buildings is still in use today.

Shaft construction works from 1944 to 2008

In 1944, work began on a further vertical shaft north of the mining field. The client was the Todt Organization , which wanted to use the salt works for armaments purposes. At the end of the Second World War , the work was stopped and the shaft, which had been sunk up to 15 m, was backfilled .

First inclined shaft 1966–1968

Entrance to the first inclined shaft

In the mid-1960s it became apparent that the vertical shaft sunk in 1854 was no longer sufficient for the increasing sales volumes. In addition, it was necessary to improve the weather management and create a second shaft as an escape route for the workforce. The decision was made to build a new inclined shaft , which on the one hand should be equipped with a conveyor belt system, but on the other should also offer enough space to be able to move heavy equipment underground without having to largely dismantle it beforehand.

The sinking work was awarded to the Walter union from Essen (today Deilmann-Haniel Shaftsinking GmbH ). The inclined shaft was given a clearance profile of 4 m wide and 2.5 m high. The starting point of the 360 ​​m long shaft was 439.8 m above sea level, the shaft led at a slope of 17.5 ° up to 334 m above sea level.

The shaft construction work began in 1966. The work was often hindered by water inflows of up to 800 l / min. Only 30% of the construction time was spent on driving, the rest of the time was needed for sealing and cleaning work. After two years of construction, the breakthrough to the pit took place on June 14, 1968, and the inclined shaft was put into operation in December 1968.

Second inclined shaft 2007–2008

Entrance to the Clara tunnel

A second inclined shaft with a cross-section of 36 m 2 was sunk between June 2007 and May 2008. This 891.5 m long Clara tunnel can be used by trucks right up to the site and allows both the cost-effective loading of the salt extracted underground and processed there and the delivery of backfill to fill the cavities.

Truck loading tower 2012

Truck loading tower

A new truck loading tower was completed in 2012.

Operation of the mine

Aus and device of the mine

Through digging in the neighboring mine near Bergfelden , it was known that the carbon dioxide- bearing layers were in the horizontal (i.e. below) the salt store. The Stettener Schacht was located outside the salt store and this now had to be found through exploratory tunnels. The first investigation section was driven to the north in 1856 , but this did not produce any results, as was a transverse section to the west . It was not until the beginning of July 1857 that they finally found what they were looking for via a third route leading south . The deposit was then driven from here in an easterly direction. Salt production started in the same year.

Dismantling process

For the dismantling of the salt deposit, 3–6 m wide locations were prepared from the approximately west / east running main line, which were oriented roughly diagonally to the main line. The water slot method was initially used to mine the rock salt . For this purpose, slits were first “cut” in the camp by spraying fresh water onto the rock salt. The running brine , which contained about 14-16% salt, was collected and fed to the saline for further processing. The remaining layers of rock salt were then drilled into and blasted away with black powder . This procedure offered some advantages in connection with the operated saltworks, but it also became apparent that the use of the water threatened the stability of the salt piers that had been left standing to protect against collapse. From 1875 the salt was extracted exclusively by blasting and the pit now remained dry.

Two years later the mining method was changed and the pillar construction was introduced instead of the local construction . The dismantling was carried out in sections at right angles to each other, which were 11 m wide. Square pillars measuring 8 × 8 m were left between these to provide support. Seen from above, the result was a checkerboard-like pattern. With this mining method, the mining losses due to the remaining pillars, which also consisted of rock salt, amounted to around 25 to 30%. For additional safety, larger safety pillars were left along the main conveyor line from the 1930s .

In the mid-1950s, the mining method was changed again, instead of pillar construction, chamber construction was introduced . The salt was now mined in elongated chambers that were about 140 m long and 12 m wide. As before, 8 m wide pillars were left between these chambers, but they were no longer penetrated, but remained in place along the entire length of the chambers. In addition, the security against a collapse of the overburden was increased by leaving pillars 40 m wide after every five chambers. With this method, the mining losses were over 60%, a good double that of the pier construction, but this was accepted because of the higher security.

Extraction, processing and promotion

Large drill rig for borehole blasting

In the beginning, the rock salt was extracted exclusively by hand , crushed with the help of a pick and shovel and filled into the trolley . Electric drilling machines were introduced in 1924, mining machines for mining in 1960/61. Today (2010) drill rigs are used to drill holes up to 7 m deep in the salt. After blasting, the debris (around 1000 tons of crude salt per cut) is transported to the crushing plant with dump trucks and wheel loaders .

In order to bring the recovered goods to light, a rack conveyor was introduced in 1862 . Initially, the miners had to push the carts to the shaft. From 1875 horses were used to transport the wagons; this task was first taken over by electric mine locomotives in 1932 . With the installation of a primary crusher at the filling site , skip funding was introduced in 1961 . Since December 1968, the conveyance has been trackless with the help of tank conveyors , later dump trucks, wheel loaders and conveyor belts over the new inclined shaft.

The processing of the extracted rock salt takes place today (2010) exclusively underground . The debris is first pre-crushed using a roller crusher and then brought to the desired grain size using a milling crusher and hammer mill . Unwanted additions are sorted out using magnetic separators and micro-sorters in an optical separation process, so that the salt content is 99%.

Cavity offset

Until 1997, the cavities created by mining were neither backfilled nor expanded. Wacker-Chemie then started to store both the residues from rock salt extraction and suitable mineral waste. The delivery of third-party waste is largely carried out via the company's own rail connection. In order to guarantee constant backfilling, a transshipment point with a capacity of 40,000 tons was set up here. Since 2008, deliveries arriving by road can also be transported directly underground via the new inclined shaft, which is accessible by trucks.

Production and workforce

Until 1924, evaporated salt was almost exclusively produced. In the first 10 years, an average of 800 t / year was produced. The highest sales were reached in 1883/84 with over 2000 tons per year, but after that production decreased again and in 1924 was 640 tons per year.

After taking over the mine in 1924, Wacker Chemie stopped producing evaporated salt and shifted its focus to the provision of industrial salt . By the beginning of the Second World War, the production reached more than 40,000 t / year. After the war-related decline, more than 100,000 tons were mined in 1962, in 1968 it was already 200,000 tons, in 1971 400,000 tons were mined and since 2004 an average of 500,000 tons have been mined per year. Today (2010) the mine is designed for a maximum conveying capacity of 10,000 t / day, the product range mainly comprises chemical salt and de-icing salts, and in 1997 the storage of mineral waste as backfill was added as a new business area.

The workforce decreased from initially 43 men (1858/59) to 25 men at the turn of the century, at the beginning of the First World War there were only 16 men. From 1930 an average of 50 miners were employed; at the end of 2010 the company had 70 employees.

Previous products

In the Barbarasaal, 120 m underground, there are occasional public cultural events.
Entrance toilet
ceiling

Saline Stetten

The original task of the salt mine was to supply the population in the two Hohenzollers' principalities with table salt. For the then (1854) approximately 66,000 inhabitants of Hohenzollern, an annual requirement of 600 tons of evaporated salt and 200 tons of crude salt (for commercial purposes) was determined, which should be covered by the Stetten salt works.

Construction of the salt works

The construction of the salt works had already started in 1854 and, like the construction of the mine buildings, was under the direction of the master builder C. Westphal. The first stage of expansion of the salt works was completed in 1858. This comprised crushing machines for the crude salt extracted from the mining industry, peeling tables for sorting out adjacent rock, a fire box in which the brine was made from the crude salt by adding water, a wooden reservoir as an intermediate storage facility for incidents, a boiling pan and a downstream smoke-drying pan. and steam dryer. The pan was 7 × 10 meters in size and around 50 cm high and was riveted together from strong sheet metal. The salt magazine, in which the salt was stored until it was transported, was housed in another building on the gable end of the boiling house.

Operation of the salt works

After the mine began to produce salt, the saltworks were also put into operation in 1858. In the first few years around 600 tons of evaporated salt were produced annually. When the state salt monopoly was lifted in 1867 , the demand rose due to falling prices and sales rose to 800 tons per year. In order to be able to meet the further demand, the systems were expanded in 1874/75, a second boiler and a further smoke-drying stove were installed, the ancillary systems and the salt magazine were also expanded. By 1896 production rose to up to 2000 tons and the workforce at the salt works increased from six to eight employees. There was no further expansion and the production figures changed little up to the First World War. When Wacker-Chemie leased the plant in 1924, sales had already fallen to less than 600 tons per year. Since the new tenant wanted to use the crude salt obtained in the mine for the chlor-alkali analysis in his plant in Burghausen, the operation of the saltworks was stopped and the buildings demolished or used for other purposes.

Hallerde production

Hallerde is a mixture containing minerals that was used as a fertilizer in the 19th century. It is a mixture of clay, rock salt and anhydrite and was mostly a waste product when operating salt pans. Inspired by the success of the nearby saltworks in Sulz am Neckar, a production facility for Hallerde was added to the construction of the saltworks in Stetten. The main component was impure crude salt with 10 to 35%, plus salt clay and anhydrite. The latter was later replaced by plaster of paris from a nearby factory gypsum quarry. In addition, the secondary rock sorted out on the puddle table and other waste from the saline were added. The coarse material was broken up and ground in the saline, then the remaining saline residues were added to obtain the ready-to-use fertilizer.

With the operation of the saline in 1858, the production of Hallerde was also started. In the first two years around 400 tons per year were produced, the highest production was reached in 1884 with 2023 tons per year. Later, other fertilizers such as potash salts or guano increasingly came onto the market, so that sales fell again. During the First World War and in the first few years after that, demand rose again when there were supply bottlenecks for potash salts. When the saline was shut down by Wacker Chemie in 1924, Hallerde production was also discontinued in Stetten.

Sale of carbonic acid (CO 2 )

During the construction of the first shaft, layers carrying carbonic acid / carbon dioxide gas were encountered. In spite of the sealing of the shaft, carbon dioxide continued to escape, which was intercepted and discharged via a tunnel. In 1902 a small factory hall was built in which the gas was purified, compressed and thus liquefied and bottled. Every day, a workforce of five filled 120 bottles and put them on the market. Production was stopped again in 1919 for economic reasons (high cleaning costs, decrease in the amount of gas escaping).

Ehrenhäckel

In the Stetten salt mine, an artistically designed "honorary chop" is passed on upon retirement. The Häckel serves to Steiger as a walking stick, and as a tool for checking the stability of mountains and mine roof by tapping.

literature

  • Werner Demel and Günter Schulz: The Stetten Salt Works near Haigerloch 1854 - 1974 . Ed .: Wacker Chemie GmbH, Munich. A. Pretzl KG, Hechingen, Munich 1976.
  • Günter Schulz: History of the Stetten salt works near Haigerloch . In: Landeskommunalverband d. Hohenzollern Land, Regional Research Center (Ed.): Works on Regional Studies of Hohenzollern, Issue 7 . Sigmaringen 1967.

Web links

Commons : Salzbergwerk Stetten  - Collection of images, videos and audio files

Individual evidence

  1. ^ Salt of the earth - 150 years of the Stetten salt mine . Wacker Chemie AG commemorative publication. Section: “Economy”. (PDF, 1.2 MB)
  2. retirement