Shaft 371

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Headframe of shaft 371 in autumn 2004

Shaft 371 of the main shaft of the disused is mining operations Aue (formerly object 09 ) of the Wismut , a uranium - mine in Westerzgebirge . With a total depth of more than 1,800 m until it was closed, the mine was the deepest mine in Germany.

location

The shaft 371 is located in Popp Forest in the valley of the Mulde on the corridor of the community Hartenstein. It lies on the Schwarzenberg – Zwickau railway line and the Hartenstein – Bad Schlema road.

history

Mining in the Schlema valley began in the 15th century for copper , silver and iron . The rich silver mineralization in Schneeberg, also discovered in the 15th century, is associated with cobalt , nickel and bismuth . When the silver yield decreased, these ores, especially cobalt, became the subject of Schneeberg mining. Together with the silver ores, a heavy black mineral of unknown composition appeared, which was called pitchblende because of its color and gloss . In 1789, Martin Heinrich Klaproth discovered the element uranium in a pitchblende stage of the Georg Wagsfort mine in Johanngeorgenstadt . On March 1, 1896, Antoine Henri Becquerel accidentally discovered the radioactivity of uranium. Marie Curie and her husband Pierre Curie discovered the elements polonium and radium in waste ores from Joachimsthal in 1898 . This was the trigger for the establishment of a therapeutic bath in the Bohemian St. Joachimsthal, which was opened in 1906. It used the radioactive waters of the uranium-silver deposit there. The flourishing spa on the Bohemian side aroused desires on the Saxon side. Then Carl Schiffner and Max Weidig from the Bergakademie Freiberg started looking for radioactive water in Saxony on behalf of the Royal Saxon Ministry of Finance . In 1909 Richard Franz Friedrich in Oberschlema discovered strong springs in the radium site of the Marx-Semler-Stolln , which drains the Schneeberg district. As a result, the construction of a spa in Oberschlema began on August 2, 1916 and opened on May 16, 1918.

After the end of the Second World War , these sources in Oberschlema and the known uranium deposits in Schneeberg and Johanngeorgenstadt became the starting point for the Soviet exploration work on uranium in Saxony for the Soviet nuclear weapons program . In 1946, work began on clearing old mines in Oberschlema ( object 02 ) and Schneeberg ( object 03 from 1947 ) and the first ore was mined. In the course of the investigation work on the flanks of the Schneeberg and Oberschlema deposits through the object 21, the continuation of the Oberschlema deposit to the north in the area of ​​Niederschlema and Aue - Alberoda was discovered in 1948/1949 . Object 09 was founded in autumn 1948 to mine this deposit. The object 09 quickly developed into the most important uranium producer in the Ore Mountains. The mineralization was significantly deeper than in Schneeberg and Oberschlema. This and the size of the deposit made modern shaft systems necessary, the primitive systems from the early days of uranium mining were unsuitable for the further development of the deposit. Therefore, several modern extraction and weather shafts were put into operation in the 1950s. On April 4, 1956, object 11 of the SDAG Wismut began the sinking work for shaft 371. On May 1, 1959, the shaft was handed over to production as "May 1st, youth shaft". In the course of the 1960s, most of the upper levels up to the -540 m level of the Niederschlema deposit were removed and production in the shafts responsible for those levels was discontinued. From 1972 shaft 371 remained as the last extraction shaft on the deposit. In the event of an accident, shaft 366 could temporarily take over the tasks of shaft 371. The highest production result was achieved in 1963 with 4,553 t uranium per year. After that, production gradually declined. In 1989, in the last full year of operation, around 1.4 million tons of ore with a uranium content of 442 tons of uranium were delivered to the processing plants. The extraction costs were 364.62 marks / kilogram, making the Aue mining operation the second most expensive of 7 active mining operations of SDAG Wismut in that year. The scheduled uranium extraction was discontinued on December 31, 1990, residual mining was carried out until March 1, 1991 in order to minimize the contact area between uranium ore and flood water. In total, the deposit delivered 73,125 t of uranium in 44 years of operation.

In 1991, the rehabilitation work began on the Niederschlema deposit with extensive underground and surface measures. Pollutants were removed, pits secured, buildings demolished and heaps outlined and covered. Furthermore, a water treatment plant for the pit water was built. During this time it was possible for visitors to enter shaft 371 up to the -540 m level. For a while, the shaft was the deepest European visitor mine. In 1997 the flooding water reached the -540 m level and work on shaft 371 was discontinued. However, the buildings continue to be used by Wismut GmbH, Aue branch, as an operating point for the renovation of the operating areas in the area. Furthermore, the mineralogical deposit collection of Wismut GmbH is located on shaft 371 and is open to the public.

Mine and pit field

Shaft 371 served as a ropeway , conveying , material and moving weather shaft. It was created as a round shaft with a clear diameter of 6.20 m. The shaft lining consists of formwork concrete. The hanging lawn bench is at 355  m above sea level. NN , the final depth of 1,090.60 m at 735.6  m below sea level , with connections to the -540 and -990 m level, whereby the sole designations refer to the Marx-Semler level as a 0-m level . The shaft tube for drainage was connected to the -1080 m level via an overburden. Shaft 371 had two parallel Koepe systems for shaft conveyance : A vessel conveyor system ( Skip ) with a payload of 7.5 t, a conveying capacity of 250 t / h and a maximum conveying speed of 16 m / s. The second system was a rack conveyor system with 4 floors for 2 trolleys each (0.63 m³), ​​of which 3 floors were used for 20 people each for cable travel. With a payload of 8 t and a conveying capacity of 160 t / h. The conveying speed was 12 m / s for rope travel (passenger conveyance) or 16 m / s in normal conveying operation.

The vertical distance between the floor level was 30 m in the upper area up to the -540 m level and 45 m below it. Levels below the -540 m level were connected by several blind shafts. As of 1986, the 1,800 m level was prepared as the deepest level. The predominant mining method was the roof butt construction with offset. In this process, the passage between two levels is dismantled from bottom to top and filled with waste rock. The horizontal conveyance in the pit was carried out on a track. Catenary-bound electric locomotives of the types El 30 and EL 30 T were used on the main lines and battery locomotives of the types B 360 and B 660 on the secondary lines . The trams used had a volume of 0.63 m³. In addition to the 4 fresh weather shafts 366, 371, 382 and 383, there were the four weather shafts 372, 373, 208 W and 208. The fresh weather for the deep levels had to be cooled in order to create acceptable working conditions. For this purpose, there were large cooling systems at shafts 382 and 383 as well as on levels -1485 and -1620. In addition to ventilating the pit, drainage was another challenge. The two main pumping stations at shaft 38 - 546 m level and at shaft 371 - 540 m level raised the collected water to the surface, from where it was discharged into the receiving waters . Between 1965 and 1989 this was an average of 20,696 m³ per day.

Until 1965 the ore was pre-sorted underground and packed in boxes and brought to the surface. In 1965 the Radiometric Processing Factory (RAF) went into operation at shaft 371, which pre-sorted step ore (0.1 to 1% uranium content) and factory ore (0.01 to 0.1% uranium content). From 1980 after the processing of the factory ore in the RAF, this was blended with the step ore and brought to an average uranium content of 0.4%. This ore was sent by rail to the processing plant in Crossen and from 1989 to Seelingstädt . The ores were then mechanically enriched and sent to the Soviet Union. From 1980 the shipment of step ore was stopped and all ores were processed into chemical uranium concentrate in the form of yellow cake in Crossen or Seelingstädt . Deaf material was conveyed to a hill behind the mine by means of an inclined elevator and from there distributed by truck to the two dumps 371 / I and 371 / II, some of which were poured into two small valleys. When operations were closed, Halde 371 / I had a volume of 9.3 million m³ and Halde 371 / II had a volume of 3.7 million m³.

geology

Uranium ore from Niederschlema-Alberoda

Shaft 371 itself is located outside of the actual Schneeberg-Schlema-Alberoda deposit . The shaft starting point was deliberately chosen so that there was no loss of supplies due to the shaft safety pier . The Niederschlema-Alberoda uranium deposit, like most uranium deposits in the region, is located on the Gera-Jachymov fault zone . It consists of more than 1,000 mineralized hydrothermal veins, which are mineralized with uranium over an average of 5% of their area. The corridors are in a series of paleozoic amphibolites , black schists , quartzites and skarns . The deposit is underlain by a Variscan granite , which itself contains hardly any mineralized veins. The uranium ore-bearing tunnels mostly line north-northeast / south-southwest and are a few centimeters to a few meters thick. The main uranium mineral is pitchblende and subordinate to coffinite in dolomite and quartz - calcite veins. Secondary components of the veins are fluorite , hematite , non-ferrous metal sulfide, pyrite and various bismuth, cobalt, nickel, silver and selenium minerals . The mineralization was proven to a depth of more than 2,000 m, but the largest uranium deposits were between 500 and 1,500 m depth. In total, reserves of more than 82,000 t of uranium were deleted in the Niederschlema-Alberoda deposit, from which 73,105 t of uranium were extracted. In 1991, residual resources including reserves of 2,049 t uranium were identified. Together with the unloaded reserves on the southern part of the Oberschlema and Schneeberg deposits as well as assumed resources in the Bernsbach exploration field, the total uranium content of the deposit was almost 100,000 t. This makes it the largest vein-type uranium deposit in the world.

literature

  • Wismut GmbH (Hrsg.): Chronicle of the bismuth. Chemnitz 1999.
  • Johannes Böttcher: Ropeway - On the trail of the Saxon uranium ore mining. Bode-Verlag, Haltern 2001, ISBN 3-925094-40-7 .
  • Oliver Titzmann: Radium bath Oberschlema . Self-published, Schlema 1995.
  • Axel Hiller, Werner Schuppan: Geology and uranium mining in the Schlema-Alberoda district (=  mining monograph . Volume 14 ). LfUG, Freiberg 2008, ISBN 978-3-9811421-3-6 .

Web links

Commons : Bismut (company)  - album with pictures, videos and audio files

Individual evidence

  1. ↑ Shaft 371 gets a cork , Freie Presse , May 17, 2010 (for a fee)

Coordinates: 50 ° 37 '55.1 "  N , 12 ° 41' 4.7"  E