Hildesia potash plant
| Hildesia potash plant | |||
|---|---|---|---|
| General information about the mine | |||
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| Rare minerals | Hard salt ( rock salt , sylvine , kieserite ), carnallite | ||
| Information about the mining company | |||
| Operating company | Kali Chemie AG / Ronnenberg Group | ||
| Start of operation | 1897 | ||
| End of operation | 1959 | ||
| Successor use | Reserve plant | ||
| Funded raw materials | |||
| Degradation of | Potash salt | ||
| Mightiness | 18 m | ||
| Greatest depth | 914 m | ||
| Mightiness | 25 m | ||
| Raw material content | up to 96% | ||
| Geographical location | |||
| Coordinates | 52 ° 5 '36 " N , 9 ° 54' 13" E | ||
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| Location | Bahnberg / Hildesiaweg, 31199 Diekholzen | ||
| local community | Diekholzen | ||
| District ( NUTS3 ) | Hildesheim | ||
| country | State of Lower Saxony | ||
| Country | Germany | ||
| District | South Hanover potash district | ||
The former Hildesia potash plant was located on the southern edge of the Hildesheim Forest in the Diekholzen community in the Hildesheim district ( Lower Saxony ). After the potash production was stopped , the mine was kept open as a reserve mine for around 40 years. At the end of the 1990s, the mine building was flooded with residues from potash mining from the Werra region .
geology
The formation of the salt dome in the Hildesheim Forest
The salt dome of the Hildesheim Forest is one of around 200 known deposits of this type ( steep storage ) in northern Germany. The salt layers from which this was created formed at the time of the Zechstein around 260 million years ago when seawater evaporated in a shallow basin. The salt layers were later covered by further deposits and are now at a depth of around 3000 m. From a weak zone in the basement, the salts pierced the slopes of the red sandstone (→ halokinesis ). The salt in the upper part of the salt dome was dissolved and washed away by the groundwater. Hardly soluble anhydrite and clay remained. These formed the so-called gypsum hat over the actual salt deposit.
Geographical location and extent
The salt level of the salt dome in the Hildesheim Forest, i.e. the upper limit, lies at a depth of around 180 meters. The salt dome extends under the mountain range of the same name in an area west of Diekholzen to east of Bad Salzdetfurth .
mineralogy
The mass of the salt dome consists of rock salt . In depths between 360 and 923 meters there are carnallite , sylvinite and hard salt deposits with a maximum thickness of 25 meters and 19 to 96% potassium chloride .
History and technology
Revelation story
The later trade union Hildesia was preceded by the potash drilling company Eschershall . This had in the then district Marienburg around the Hildesheim Forest Berechtsame of 22 square kilometers. At the mine fields of Escher Hall mark scheideten the unions Schierenberg , Mathilde Hall and the Kalibohrgesellschaften New Hope and United fertilizing .
From 1894 a total of five deep boreholes were drilled to explore the deposit . A maximum of three carnallite and sylvinite deposits with a thickness of three to four meters could be drilled in depths between 360 and 923 meters.
The Kalibohrgesellschaft was converted into the Hildesia union in 1897. At the head of the company were the banker Selly Meyerstein from Hanover and the architect Franz Stommel . The financier was the Hanoverian bank Max Meyerstein , which also financed the Alkaliwerke Ronnenberg AG . In 1898, the Ronnenberg alkali works took advantage of the weak financial base of the Hildesia union to take over the majority of the Kuxen .
Hildesia mine
The shaft construction
The sinking of the Hildesia shaft began on October 27, 1897. The starting point had been chosen so that Sylvin could already be extracted and sold when sinking . The colliery area north of Diekholzen was opened up by a standard-gauge railway line, the Marienburg (Han) –Hildesia railway, completed in 1898 . The shaft construction work in conventional drilling and shooting went well at first. In 1898, a depth of 187 meters had already been completed and segments of up to 171 meters had been installed when a strong lye inflow of 18 m³ / min occurred. This could not be mastered with all available pumps, so that the shaft filled up to 70 meters below the hanging lawn bench .
As a result of the events, it was decided to continue building the shaft using the Kind Chaudron shaft drilling method . The work was started on December 11, 1899 by the Düsseldorf company Haniel & Lueg . A pilot drill with a diameter of 2.5 meters and a main drill with a diameter of 4.1 meters were alternately drilled. The drill heads, which can weigh up to 20 tons, often got stuck in the plaster hat and the wooden drill rods repeatedly broke. Sometimes it took two weeks to recover the drill. The drilling work was finished on March 24th, 1904 at a depth of 349 meters and on April 8th the assembly and the floating of the Küvelage started. The annulus between the basin and the shaft joint was filled with a total of 1140 tons of cement using a lowerable spoon. Despite a setting time of five weeks, immediately after the sump of the shaft on September 7, 1904, there was a renewed ingress of caustic solution of 5 m³ / min. For further sealing, the lower part of the basin layer had to be drilled 52 times over 40 shaft meters and the shaft joint had to be flushed with cement slurry. This work, which lasted from January 3 to March 28, 1905, consumed another 560 tons of cement. Once again, it was not possible to achieve a complete seal. In the middle of 1905, cement slurry had to be pressed through another 165 boreholes, this time with a hydraulic press. On November 18, 1905, the shaft was initially dry and the Moosbüchse (= Küvelageboden) could be expanded. The shaft was then further sunk from December 5, 1905. Tubbings were installed below the Küvelage between 349 and 403 meters depth to secure, and below that the shaft tube was lined up to 651 meters. At 588 meters, the drilled sylvine bearing was encountered with 87% potassium chloride. In April 1907 the Hildesia shaft had reached its preliminary final depth of 738 meters and the first filling point and the first floor were excavated at 720 meters .
On January 9, 1908, lye inflows again occurred at a depth of 420 meters. The masonry therefore had to be removed up to 487 meters and replaced with additional segments. This work lasted until October 4, 1909. The segment at the inlet point was equipped with a recording bore. At first, almost 8 liters of lye emerged from this per minute. However, the inflow soon became significantly less and initially no further work was necessary.
Two blind shafts were sunk on the 720 m level . At a depth of 843 meters, an 8-meter-thick hard salt deposit was opened up. For this reason, the decision was made in 1912 to deepen the main shaft to 914 meters and to set up another excavation level at 894 meters to fix the hard salt storage facility.
Operation of the potash plant between 1908 and 1930
In parallel to the underground work, the necessary operating buildings were erected above ground . Most of it was completed in 1907. There was a shaft hall with headframe , hoisting machine house , a power plant with boiler house , a loading station with salt shed and an administration building. Houses for the miners were built in the vicinity of the mine .
The first potash salts were mined in 1908 and thus the entry into the German potash certificate took place . Since there was considerable resistance to the construction of our own chlorinated potassium factory, the crude salt was first processed in the factories of the Riedel trade union and the Ronnenberg alkali works. The introduction of the final lye into the innermost was controversial ; in addition to agriculture and fishing, the neighboring potash works also saw their interests at risk.
In 1913 a connection to the neighboring Mathildenhall mine was started in order to create a second mobile exit for the mine to the surface, as prescribed by the mining law . At distance meter 610, an 18-meter-thick carnallite warehouse was approached. The KCl content was a maximum of 25.3%.
The mines of the Ronnenberg Group survived the economic difficulties of the First World War without major problems . In 1917 the remaining Kuxen of the Hildesia, Riedel and Germany unions were acquired through a capital increase of four million marks . After the end of the war, sales at the Hildesia potash plant collapsed due to material shortages. The production was reduced and in 1923 only research work was carried out. After the merger of AG Deutsche Kaliwerke with the Glückauf-Sondershausen union and the Ronnenberg AG alkali works, the Hildesia union was taken over by Wintershall AG in 1927 . On June 30, 1927, the union was liquidated at the union meeting. The remaining operations continued until 1930, after which the decommissioned mining facilities were kept open as a reserve facility.
Military use and short-term recommissioning from 1937 to 1959
The Hildesia mine was handed over to the German Wehrmacht in 1937 together with the Mathildenhall mine , which set up an army ammunition plant in the underground mine workings . The facility was officially called Heeres-Munitionsanstalt Diekholzen . Additional buildings were built for military use, mainly accommodation. The Marienburg (Han) –Hildesia small railway was put back into operation.
At the end of the Second World War , the potash plant was captured and occupied by invading American troops on April 7, 1945. It was finally returned to Wintershall AG on January 13, 1948.
The caustic inflow into the shaft tube has increased sharply again since 1945 and put the 894 m level under water. In connection with the planned recommissioning, 50 m of masonry below the last wedge had to be replaced and the basin between 320 and 487 meters backfilled with cement. This successfully completed the sealing work for the future.
In September 1950, the extraction of potash salts from the 720 m level was resumed. While 25 men carried out the most important maintenance work in the first years after the war, in 1955 400 miners were already employed. For treatment of potash crude salts one has flotation built. The remaining plant facilities were overhauled and the headframe was replaced by a new one. Only kainite fertilizer salts with a K 2 O content of 10 to 15% were produced in order to meet increased demand.
It soon became clear that the small Hildesia-Mathildenhall plant would not be able to compete with the other, more powerful potash plants in West Germany, and production was discontinued in 1959. The shafts remained open as a reserve. Until 1973, the systems were looked after by the sister plant Bergmannssegen-Hugo in Lehrte . After the assets were transferred to the Kassel- based Kali + Salz AG, which was founded in 1970 , the mine building served as a potential extension for the neighboring Salzdetfurth potash plant, which is producing from the same salt dome . There was no resumption of mining in the Hildesia-Mathildenhall field until the closure of the Salzdetfurth potash plant in 1992.
Mathildenhall mine
The Berechtsame founded on February 7, 1911 Union Hall Mathilde was created by the separation of 11.14 square kilometers mainly in forest areas nearby fields parts of the union Hildesia in Diekholzen. These were merged with the 8.63 km² of the mining company Mathildenhall , the majority of which also belonged to the Ronnenberg alkali works. The union was headed by well-known functionaries of the Ronnenberg alkali works, the banker brothers Selly and Siegmund Meyerstein , and the mining assessor Paul Behrendt .
To explore the deposit in this area and to choose the starting point of the shaft, three deep boreholes were drilled. In the spring of 1912, preparations for the sinking of the Mathildenhall shaft began by the Nordhausen civil engineering and refrigeration industry (→ Nordhausen shaft construction ). According to the contract, this subcontractor should bring the shaft through the water-bearing mountains to a depth of 175 meters using the freezing process . An electric narrow-gauge railway (gauge 600 mm) 3.9 km in length from the Hildesia mine was built to develop the site in the middle of the Hildesheim Forest . This had a standard gauge connection . On the Zechenplatz a hoisting machine house, moorings, workshops and other necessary operational buildings were built.
After the mountains had frozen, the actual devil work began on June 2, 1913. On December 23 of the same year, the shaft had reached a depth of almost 175 meters when strong water inflows made it necessary to cement the bottom of the shaft. Tubbings were installed up to a depth of 225 meters during the subsequent deepening. The outbreak of the First World War temporarily put an end to the work at a depth of almost 250 meters.
When the shaft sinking was resumed in September 1921, the shaft tube was under water up to 17 meters below the turf hanging bank. Since the German potash mining was in a crisis at the beginning of the 1920s, the expansion of the mine was only hesitantly advanced. Through the merger of the Ronnenberg alkali works, the Glückauf-Sondershausen union and the AG Deutsche Kaliwerke in the years 1924 to 1927, the Kuxen of the Mathildenhall union also came into possession of Wintershall AG without exception. This forced the shaft to be built again, as the shaft was supposed to serve as the second mobile exit of the Hildesia potash plant. The water-bearing red sandstone was cut through by using the cementing process. The shaft extension consisted of brick masonry from 225 to 250 meters depth, from 250 to 370 meters of concrete and between 370 and 426 meters depth, tubbings were installed again, which were stolen from the disused Thiederhall potash plant . In 1925, a hard salt and carnallite store was opened up at about 800 meters at the depth. The shaft was completed in 1926 with a final depth of 990 meters. The 849 and 965 m level were set up as conveyor levels. There the hard salt deposits were 10 to 25 meters thick. After the connection to the Hildesia shaft, which had begun in 1913, was completed, operations as an independent potash plant were officially closed. The allocated participation figure of 40% of the average participation of the potash works in the German Potash Indicator was transferred to other mines. In the years that followed, the Mathildenhall shaft was used exclusively as a weather shaft for the Hildesia potash plant. He shared its fate, such as the temporary shutdown in 1930 and military use from 1937 to 1945. From 1950 to 1959 again in operation as a weather shaft, the plans as a reserve for the Salzdetfurth potash plant were abandoned when it was closed in 1992.
After the shutdown
After the Bad Salzdetfurth potash plant was closed, the pits of the Hildesia reserve mine were no longer required. In 1997 the Mathildenhall shaft was backfilled and the daytime facilities completely demolished. The mine building was to be kept safe by flooding (→ hydraulic offset ) with residual liquors from the factory of the active Werra potash plant . For this purpose, the railway connection of the Hildesia potash plant was restored. Between 1998 and 2003 three trains a week with 20 caustic tank cars rolled to the Hildesia mine in order to discharge the residues into the shaft and the routes. The flooding was completed in September 2003 and all surface facilities were dismantled. On November 17, 2004 the landmark of Diekholzener potash mining, the headframe of the Hildesia shaft, was demolished.
Current condition (2011)
The daytime facilities of the Hildesia mine were located north of Diekholzen on the southern edge of the Hildesheim forest. The elongated colliery area extends along the streets Bahnberg and Hildesiaweg . Today only part of the old building is still standing.
The administration building and some outbuildings are still well preserved. The Mathildenhall shaft, located in the middle of the Hildesheim forest, has completely disappeared and the former colliery area has overgrown.
literature
- Rainer Slotta : Technical monuments in the Federal Republic of Germany - Volume 3: The potash and rock salt industry . German Mining Museum, Bochum 1980, p. 604-624 .
Single receipts
- ↑ Klaus Peter Breidung: Custody of potash and rock salt mines, including long-term safe shaft seals . In: Potash and Rock Salt . No. 2, 2002, p. 28.
- ↑ Lars Baumgarten: 4.9 Hildesia .
- ^ The Heeresmunitionsanstalt (mine) Diekholzen , on www.relict.com
- ↑ Detlev Herbst: The use of closed potash mines as ammunition plants. Retrieved June 8, 2020 . , on the website of the Heimatverein Volpriehausen
- ^ Demolition of the Hildesia headframe, Diekholzen . Mine Archaeological Society.
Web links
- Demolition of the headframe Hildesia, Diekholzen. Retrieved January 3, 2015 .