Fortuna pit (Groß Döhren)
Map with all coordinates: | Fortuna pit | |||
|---|---|---|---|
| General information about the mine | |||
 Opencast facilities at the Fortuna I shaft in the 1940s. |
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| Mining technology | Opencast mining , magazine construction , expansion mining | ||
| Funding / year | up to 864,300 t | ||
| Funding / total | 11 million tons of iron ore | ||
| Information about the mining company | |||
| Operating company | Barbara Erzbergbau AG | ||
| Employees | 596 (in 1940) | ||
| Start of operation | before 1869 | ||
| End of operation | 06/30/1963 | ||
| Funded raw materials | |||
| Degradation of | Brown iron stone | ||
| Mightiness | 10-30 | ||
| Greatest depth | 440 m | ||
| Geographical location | |||
| Coordinates | 51 ° 59 '47 " N , 10 ° 25' 33" E | ||
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| Location | Weißer Weg, 38704 Liebenburg | ||
| local community | Liebenburg | ||
| District ( NUTS3 ) | Goslar | ||
| country | State of Lower Saxony | ||
| Country | Germany | ||
| District | Peine-Salzgitter area | ||
The Fortuna mine is a disused iron ore mine in the Peine-Salzgitter district near Groß Döhren , municipality of Liebenburg in the Goslar district ( Lower Saxony ).
The last mine operated by Barbara Erzbergbau AG was the largest in the southern Salzgitter ridge . A rubble ore deposit of the Lower Cretaceous, consisting of several partial deposits, was mined in open pit and underground mining .
geology
The formation of the ore deposits of the Fortuna mine
The formation of the camps proceeded like that of the other deposits in the Salzgitter area : the coastline of the Lower Cretaceous Sea was in the area of the Salzgitter ridge. In the area of decaying marine organisms dissolved in water iron compounds could very well precipitate , forming so-called Toneisenstein- geodes . These were preferentially deposited in natural depressions near the coast due to the sea surf. Due to the weathering processes after the water withdrew, they disintegrated into numerous rubble. During subsequent floods, iron oolites were deposited in the same place . The originally flat deposits (also called ore ponds ) that were created in this way were disturbed and erected over the course of millions of years by tectonic processes and / or rising salt domes.
Geographical location and extent
The Fortuna deposit is located on the southeastern edge of the Salzgitter ridge between the towns of Groß Döhren and Liebenburg. It strikes from north to south and falls steeply with 73 to 90 gon from west to east. In the area of the Fortuna mine, the deposit has been developed over a striking length of 1500 meters; in the north, the Anna and Hope mine of the Ilseder Hütte built the continuation of these ore deposits. The most important part of the deposit was the so-called brown deposit with a thickness of 10 to 30 meters. Separated from it by layers of clay of 10 to 25 meters, there was the Rothe-Rose or Rote Lager above . In the south of the deposit, a third camp occasionally occurred, the Red South Camp . The course of the camps was offset by disturbances .
mineralogy
The ores encountered fluctuated very strongly in their mineral composition. It was a conglomerate of lenticular to shell-shaped brown iron fragments less than one to 15 millimeters in diameter, phosphorites , sandstone and glauconites in a sandy-clay binder.
The average composition of the later raw ore was: 25 to 38% Fe , 0.1 to 0.2% P , 2 to 5% CaO and 28 to 35% SiO 2 .
History and technology
Predecessor mining
The Fortuna mine field was muted in 1857 by the mountain ridge Wilhelm Joseph Leopold Osthaus from Clausthal . He sold it to the Lüneburger Eisenwerke in 1858 . In 1868 it was owned by Emil Langen and AG Eisenwerk zu Salzgitter , which operated an ironworks at the Gittertor near Salzgitter from 1868 to 1874 . Langen was to create an open pit and the 160-meter field Fortuna Döhrenbach cleats mount up .
First beginnings in the years 1869 to 1884
On July 10, 1869, the major railway company Bethel Henry Strousberg acquired the Eisenstein fields Dorothea , Fortuna, Glückauf , Rothe Rose and Glücksborn near Groß Döhren for 250,000 thalers . The ores from the Fortuna mine were to be used to supply the iron and steel works built near Othfresen in 1869 . To this end, a 2,330 meter long narrow-gauge track was laid from the hut to the mine . An operating license from the Goslar Mining Authority of February 25, 1869 was already in place and in 1870 an opencast mine with three stops and an annual output of around 15,000 tons was in operation. Two tunnels were driven towards the opencast mine . In 1872 the opencast mine had reached a depth of 20 meters, the ore deposit there was 33 meters thick.
Due to his daring investments, Strousberg repeatedly got into financial difficulties and sold the Fortuna mine and the Othfresen blast furnace together with the Glückauf-Tiefbau hard coal mine on February 20, 1872 to the Union, AG for mining, iron and steel industry ( Dortmunder Union ) for a total of 6 million thalers.
As early as 1871, with the end of the Franco-Prussian War, a downturn in the iron-making industry began, as Lorraine with its extensive mines ore deposits had fallen to the German Empire . As a result, the Dortmund Union shut down the iron and steel works in 1874, dismantled parts of the facilities and moved them to Dortmund . The mining operations were suspended from 1874 to 1881 due to a lack of sales. Plans to resume mining failed because of the high transport costs to the Ruhr area . After another 29,000 tons of ore had been mined for smelting attempts from 1881 to 1883, the workforce was dismissed in 1884 and operations ceased.
Investigation of the deposit, mining and processing attempts from 1920 to 1934
After losing World War I , Lorraine fell back to France and the iron and steel industry of the Weimar Republic had to look for a new domestic raw material base. Now the Salzgitter ores and with it the Fortuna camp moved again into the interest of the steel works in the Ruhr. The Dortmunder Union and its authorized persons in Groß Döhren and the disused Fortuna mine were taken over in 1910 by the German-Luxemburgish Mining and Hütten-AG ( DL ). On July 16, 1919, the DL reported to the mining authorities in Goslar that they were considering an investigation of the deposit near the surface . Erzstudien GmbH , a consortium in which, in addition to DL, the Hörder Bergwerks- und Hütten-Verein , Hoesch AG , Gelsenkirchener Bergwerks-AG and Rheinische Stahlwerke AG were involved, was commissioned with the investigation work .
In order to go beyond the experience of the Ilseder Hütte to research the economic extraction of salt grid ores, the Fortuna consortium was founded on April 16, 1920 , and it was decided to resume and expand mining to a capacity of 10,000 tons of ore per month. To this end, the old opencast mine was restarted and another was opened. The mined ores were transported away via a Bremsberg and the renewed railway line to Othfresen. From 1923 the excavation began . The Rothe Rose shaft , the stacking shaft and the barrel-length shaft were sunk . All three shafts were around 35 meters deep and reached up to the 200 m level ( NN ). Furthermore, the Dorotheen tunnel was driven from the Barley . In 1924, 211 miners were working on Fortuna and mining up to 6,000 tons of ore per month. The raw ore contained about 30 to 34% Fe and was enriched in a first test preparation to form concentrates of 36 to 39% Fe. A second test preparation was built in 1925.
The ores encountered were difficult to process; on the one hand, the mineral composition of the deposit was different at each operating point in the mine, and on the other hand , the hardness of the ore increased towards the depth . The high ratio of silica to lime in the raw ore with a comparatively low iron content was a disadvantage for economic smelting . Therefore sales of the concentrates soon stalled. As early as 1924 and 1925, the mining operations had to be temporarily stopped. Following the merger of most of the shareholders to form Vereinigte Stahlwerke AG on January 14, 80% of the shares in the Fortuna consortium were held by VESTAG and 20% by Hoesch AG. In the following years the mine did not get beyond a sporadic trial run.
Expansion and heyday from the four-year plan to the economic miracle in the years 1935 to 1953
With the four-year plan of the National Socialist regime in 1935, the exploration and expansion work on the Fortuna mine was revitalized. The stacking shaft, now called Fortuna shaft , was sunk down to the -50 m level (5th underground level = 280 meters depth) and the ore deposit there was examined. After all civil engineering soles with the shaft Fortuna durchschlägig were connected, the shaft Rothe rose and the Tonnlägige were Schacht dropped . The mine connection railway to Othfresen was expanded to standard gauge . On the basis of the experimental work in the 1920s to the early 1930s, a completely new preparation was created from 1936 to 1938. Furthermore, numerous auxiliary buildings were built, such as the administration, the workshops or the chew building .
As early as 1937, 235,000 tons of raw ore were extracted. The selection of a suitable mining method in underground mining also caused difficulties . So far, no such mighty, steep iron ore deposit has been mined in Germany with comparatively less stable side rocks. After initial attempts with butt construction or ridge construction , the magazine construction without offset prevailed, a variant of the chamber construction that had been developed in the Swedish ore mining industry. Here, the remained losgeschossene debris in the excavation chamber to face the Auserzung and was finally completely over a pedestrian course deducted. The work in the quarries was dangerous because the tusks had to work standing on the heap while drilling and removal was not possible. This is why this process was replaced at the Fortuna mine at the beginning of the 1940s by the so-called expansion construction . The tusks were now protected in small, stacked mining stretches on the edge of the widening, the so-called hamlets . The widenings had a footprint of 3 meters by 8 meters. The ore was shot down an embankment ( aprons ) and fell through roller holes into a scraper track . With this mining principle, up to 600 tons of ore per day were extracted from one expansion. In 1940 the mining output was 10 tons of ore per man and shift. As the mines were shot to break after the ore was removed, clear funnel-like subsidence occurred over the course of days . This was consciously accepted, it was an uninhabited area. Later, in the 1950s and 1960s, these hoppers were filled with processing residues.
In the shaft, the ore was lifted to the surface with a skip conveyor and transported to processing on a conveyor bridge. There it was first ground . The grist was then washed with water ( refined ). The clayey-sandy tailings came off as sludge and were collected in a sludge pond with a volume of 2 million m³. Then the so-called semi - concentrate was sieved, subjected to a separation via the specific density and finally subjected to magnetic separation . In this way, about 55% of the disruptive silica could be removed from the concentrate. In contrast to most of the neighboring mines in the Salzgitter area, the majority of the output was sent to the Ruhrhütten for dispatch. In 1940, 472 miners extracted 395,225 tons of ore.
In the years 1942 to 1943 a weather shaft was sunk to a depth of 185 meters. The pit was aligned and prepared on the + 154- (1st), + 100- (2nd) and + 50-m level (3rd underground level) . During the Second World War , the miners performed numerous special shifts called armored shifts. The continued operation of the mine suffered from the effects of the war. For example, the start of driving a connection to the Morgenstern sister mine in Klein Döhren had to be postponed . The collapse in May 1945 resulted in a temporary shutdown. However, as there was no war-related damage, operations started up again a few weeks later.
After the first post-war years were marked by the prevailing shortage of materials and personnel, an upswing set in at the beginning of the 1950s. The reconstruction required an increased amount of raw materials for iron and steel production, and a shortage of iron ore on the world market made the domestic ore deposits interesting. In 1949 270,800 tons were transported by 268 men, in 1952 it was 448,323 tons with a workforce of 427. In connection with the reorganization of the German coal and steel industry , the mine ownership of the Fortuna mine was transferred to Barbara Erzbergbau AG as the legal successor to the VESTAG raw material operations on March 18, 1953 .
Fortuna composite mine - rationalization until closure from 1954 to 1963
In the expectation of long-term ore sales to the iron and steel works in the Ruhr area, extensive expansion and modernization of the Fortuna mine began in 1954. First of all, the sinking of the Fortuna 2 shaft began northeast of the main Fortuna shaft . The five-meter-wide shaft reached up to a depth of 440 meters and received a combined vascular and rack promotion . From the Fortuna 2 shaft, a new deepest excavation level, the 7th (-188 m) level, was excavated. At the same time, a new ore processing facility with a larger capacity was set up, in which from 1956 the ores from the sister mines Morgenstern and Ida-Bismarck were also processed. The ores from Morgenstern were transported on a 3.3 km long lorry cable car , those from Ida by shuttle trains on the mine connection railway .
Before being shipped to the Ruhr area, the concentrate was processed in a Krupp racing facility in Salzgitter- Watenstedt , which was put into operation in December 1956, using rotary kilns to make pellets with an iron content of 92%.
With the breakthrough of the Fortuna-Morgenstern connection on the -50 m level in 1959, the two mines were also connected underground.
Fortuna achieved the highest individual production in 1959 with 593,100 tons and in 1961 864,300 tons of raw ore from all three mines were processed into concentrates in Fortuna. Between 1953 and 1960, underground output rose from 5.3 to 8.6 tons per man and shift.
At the end of 1961, the most important steel companies in the Ruhr area decided not to purchase domestic iron ores in the future. At this point in time, a ton of German ore with about 30% iron content cost around 100 German marks , a ton from Sweden including transport cost 51 German marks with 60% iron. The Krupp racing facility finally ceased operations in the spring of 1963, so that there was no longer any possibility of selling ore. The Fortuna mine was officially closed on June 30, 1963. In its 95-year history, a total of 11 million tons of iron ore have been mined in underground and open-cast mining. In 1964 the shafts were filled and the headframes and part of the daytime facilities were demolished.
Current condition (2010)
The colliery site is located in the forest west of Groß Döhren. From the L 510 ( Durnidistraße ), at the northern exit of the village, the street Weißer Weg starts , which after about one kilometer meets the former company property. The hoisting machine house and the shaft hall of shaft II are located in the north-east. Both buildings have not been used since they were closed and have accordingly fallen into disrepair. The former (new) administration and the Kaue follow further south. In the extreme southwest was Shaft I, the hoist house of which is still standing. The workshop building and the older administration are still nearby. The processing was carried out on the open space in the east of the mine, from which the massive concrete bunkers for mountains and concentrate have been preserved.
The drained, former waste treatment pond is now used as a sports field.
literature
- Rainer Slotta : Technical monuments in the Federal Republic of Germany - Volume 5, Part 1: The iron ore mining . German Mining Museum, Bochum 1986, p. 169-183 .
- Heinrich Korthöber et al .: Mining in Salzgitter . the history of mining and the life of miners from the beginning to the present. In: Archives of the City of Salzgitter (Ed.): Contributions to the city's history . 1st edition. tape 13 . Appelhans, Salzgitter 1997, ISBN 3-930292-05-X , p. 304-310 .
- Manfred Watzlawik et al .: Fortuna, Morgenstern, Georg-Friedrich . History and stories of ore mining near Döhren. Ed .: Döhrener Mining Working Group. 1st edition. Self-published, Groß-Döhren 1983.
Web links
- Web presence of the current activities of Barbara Erzbergbau GmbH
- Döhrener Mining and History Working Group
Individual evidence
- ↑ ERZGRUBEN: Last shift . In: Der Spiegel . No. 50 , 1961 ( online ).
- ↑ Der Spiegel, No. 29/1962 Gesang der Archangels, accessed on August 16, 2010