Wismut (company)
SAG/SDAG Wismut was a uranium mining company in East Germany during the time of the Cold War. It produced a total of 230,400 tonnes of uranium between 1947 and 1990 and made East Germany the fourth largest producer of uranium ore in the world at the time. It was the largest single producer of uranium ore in the entire sphere of control of the USSR. In 1991 after German reunification it was transformed into the Wismut GmbH company, owned by the Federal Republic of Germany, which is now responsible for the restoration and environmental cleanup of the former mining and milling areas. The head office of SDAG Wismut / Wismut GmbH is in Chemnitz-Siegmar.
History
The Ore Mountains in southern East Germany at the border with the Czech Republic are closely connected to the history of uranium exploitation. The metal was discovered in a sample from a silver mine in the mountain range, and uranium was produced first as a by-product in the early 19th century and later as a main product from the 1890s on. The chemists Marie and Pierre Curie discovered the elements radium and polonium in pitchblende tailings from a Czech uranium mine in these mountains. Radioactive waters were used in several towns for health treatment.The uranium mines in the Erzgebirge, in the south-eastern provinces of Thüringen and Sachsen were the sites of a number of NKVD mining camps employing forced labor. Wismut AG was the Soviet company that ran the uranium mines. Stalin gave greatest priority to this mining project in his competition with the United States to produce nuclear weapons. On April 4, 1946, the Council of Ministers of the Soviet Union decided to place the uranium mining under the control of the NKVD. Regular mining operation for uranium started in the summer of 1946. Lavrentii Beria, Soviet Minister of Internal Affairs, chief of the NKVD, who was directly responsible for the Soviet atom bomb project, appointed NKVD Major General Mikhail M. Maltsev, a veteran commander of GULAG labor camps in the USSR and recipient of the highest Soviet decorations, to lead this enterprise. He was under the direct command of Colonel General Ivan Serov, head of the NKVD/MVD in the Soviet Zone of Occupation and Beria’s deputy.
Maltsev applied GULAG discipline methods in the early days of the Wismut operation, such as withdrawing food rations from miners who did not fulfill their quotas or the use of military tribunals for those workers accused of alleged sabotage. But unlike the GULAG forced labor camps in Siberia, it was difficult to hide the abuses of labor in the Erzgebirge, a fairly densely settled region of East Germany. To maintain secrecy and security, however, in early 1947, the mining districts became closed military zones, banning even the East German government party, SED, from activities there. Wismut, as it was under the political control of the NKVD, dealt with all important issues between the company and its German employees. The Soviet military employees in Wismut, on the other hand, were under the authority of the Ministry of State Security, Minister Viktor Abakumov, who had frequent conflicts with Serov.
The NKVD maintained a strict security system in the Wismut mines. NKVD/MVD troops guarded not only the mines, but the total Wismut zone of mines as well. having up to 15,000 troops there. These troops were under the command of the NKVD military head of Wismut. There were additional armed military units stationed in the uranium mining districts. Military and NKVD checkpoints were present at all approaches to this zone. The mines were surrounded by wooden fences and watch towers, and access to them was only through a guarded gate. There were also NKVD posts at district or town levels at the fourteen Wismut mines. A special NKVD group, commanded by a Major Malygin, was very important in its work at all the pits and plants of Wismut. He had the task of investigating all cases of espionage and diversion and reported directly to General Serov.
The uranium industry grew in the early years after the war at an extraordinary rate, reaching its highest number of employees in autumn 1950 with over 200,000 workers. Wismut AG became the largest enterprise in the Soviet Zone of Occupation. The initial program of compulsory labor was eventually supplanted by volunteer labor, responding to higher wages and better working and living conditions. Wismut health records indicate that at least 20,000 miners died of or suffered from lung disease "induced by exposure to radiation and dust".
At the end of 1953 the company was liquidated and the Soviet-East German stock company Wismut was newly founded, with the Soviet Union and the German Democratic Republic each owning 50%. Working and technological standards improved significantly in the following years. Uranium exploration and mining concentrated in the first years after World War II on the old mining areas of the Ore Mountains and adjacent Vogtland mountains. Many uranium occurrences had long been known there and were accessible using the old adits and shafts from the silver and base metal mining of former centuries. In 1950 the giant ore deposit of Ronneburg and the medium-sized Culmitzsch deposit were discovered and in 1965 the Königstein deposit in the Elbe Sandstone Mountains. The peak of uranium production by the Wismut company occurred from the mid-1960s to the early 1970s, reaching nearly 7,000 tonnes of uranium per year, after which it declined to 3,500 tonnes in the last normal production year, 1989.
Political and economic changes in East Germany and the subsequent reunification of Germany led to the cessation of uranium mining in December 1990. The Federal Republic of Germany assumed ownership of the East German and Soviet stocks of the company and transformed the company into Wismut GmbH in 1991. This new company is responsible for restoring the former mining and milling sites, for which the government approved a total budget of around 6.4 billion euro, but higher costs are anticipated. This activity includes securing/filling underground cavities, covering dumps and tailings, treating mine water and removal/decontamination of the buildings at the mine and milling sites. In 2011 the restoration program was extended to the year 2022.
Mining
Ore Mountains and Vogtland
The Ore Mountains and Vogtland were the first exploration targets for uranium and host the largest number of deposits mined by Wismut. All deposits in these mountain ranges are hydrothermal vein-style mineralisations in Palaeozoic metasedimentary and igneous rocks and Variscan age granites. Most deposits are situated in the western Ore Mountains and the neighbouring Vogtland region, whereas the central and eastern Ore Mountains contain only a few smaller deposits.The deposits are related to deep crustal northwest-trending fault structures, with the most important being the Gera-Jáchymov fault zone containing most of the larger deposits, including Jáchymov on the Czech site of the Ore Mountains, Johanngeorgenstadt, Pöhla-Tellerhäuser, Schneeberg-Schlema-Alberoda in the German part of the Ore Mountains, and Ronneburg black shale-type mineralisation in Thuringia. The size of the mineralisations ranges from very small deposits with some hundred kilogrammes of uranium content and a few mineralised veins, up to the giant deposit of Schneeberg-Schlema-Alberoda containing nearly 100,000 tonnes of uranium and about 2,000 mineralised veins. There are three major vein types carrying uranium: uranium-quartz-calcite veins, dolomite-uranium veins and BiCoNi-Ag-U veins. Only the first type is a primary mineralisation, while the latter two carry remobilised pitchblende from the older vein types. The BiCoNi-Ag-U mineralisation had been mined since the 15th century for its content of silver, bismuth, cobalt and nickel. The heavy black mineral often occurring in these veins was useless to the miners of former times and was named 'Pechblende' because of its color. This word is still used for the most important uranium mineral ore in all veins types, but coffinite deposits also occur. In the oxidation zones of the deposits there is a wide range of secondary uranium minerals. The distribution of uranium minerals in the veins varies considerably with the highest concentration of uranium in places where they crosscut reducing host lithologies like carbon-rich schist and skarn. The width of the veins ranges from a few centimeters to several meters, with an average ore grade of 0.1% of uranium. Lenses of massive pitchblende occur locally with a width of over 1 m. The most important deposits are described below.
Schneeberg-Schlema-Alberoda (Objects 02/03/09; mining division Aue)
This ore field was the largest deposit in the Ore Mountains. It is situated about 20 km south of Zwickau in the western Ore Mountains. Schneeberg was an important mining center since the 15th century, producing silver, cobalt, nickel and bismuth, and the town of Oberschlema was known for its strongest naturally occurring radioactive waters at the beginning of the 20th century. A radium health center was established in the town in 1914.After the Second World War, Soviet scientists started exploring the old mining areas for uranium, and mining commenced in 1946 even before SAG Wismut was established in 1947. Schneeberg at the southern end of the deposit became Object 03 and Oberschlema Object 02. Subsequently the blind northern part of the ore field was discovered and mining started there in 1949. Object 09 was established to mine the Niederschlema-Alberoda part of the ore field.
Mining in Schneeberg continued until 1954 reusing many shafts from previous silver and cobalt mining. Up to that time, about 200 tonnes of uranium was extracted from Schneeberg. Oberschlema was mined to depths of over 700 m. Mining ceased in 1960 after producing more than 7,000 tonnes of uranium. A high density of veins near the surface and the 'wild' mining methods of the 1940s and 1950s caused the complete destruction of Oberschlema. Most houses were so badly damaged and the subsurface so unstable that the entire small town was removed in the 1950s. Today the former mining area hosts a radon health center reestablished in the 1990s. After a restructure of the company in the 1960s, Object 09 became Bergbaubetrieb Aue. It developed into the single largest producer of uranium within SAG/SDAG Wismut with a peak production of 4,000 tonnes of uranium in 1965. In the last normal production year, 1989, it produced about 550 tonnes. This deposit was the first of all Wismut deposits to be supplied with large modern mining shafts and powerful ventilation in the mid-1950s. The most important shafts where Shaft 38, Shaft 366 and Shaft 371. The latter went into production in 1959 and was the main shaft of the deposit up to the end of production in 1990. Shaft 371 possessed an automated sorting plant used to separate different classes of ore and to increase the overall ore grade. High grade ore was sent directly to the Soviet Union without further processing, while ore containing less than 1% uranium was shipped to the mill at Crossen near Zwickau. This was done until 1980; afterwards all ore was milled, with the sorting plant raising the average ore grade to 0.4% before it was sent to Crossen for processing. An unsuccessful attempt was also made to produce base metals, silver and selenium as by-products. Shaft 371 was connected to the -540 and -990 m level. Deeper levels were connected by blind shafts. The deepest level opened in 1988 was the -1800 m level, nearly 2,000 m underground, making the mine the deepest in Europe. The mining method used was the same as in the centuries before, although with more modern equipment: galleries were driven along strike of the mineralised vein on a lower and upper level. These were connected by small shafts from the lower to the upper level. Then the vein was mined upward using drilling and blasting. The ore was transported to the lower level and brought to the main shafts by rail cars, while the stope was filled with waste rock, as possible. After a vein was mined out, the entrances were sealed to prevent radon from the old stopes from entering areas with active mining. This method was used in all vein type deposits of the Ore Mountains. The total production from Niederschlema-Alberoda was over 72,000 tonnes of uranium. Together with the production from Schneeberg and Oberschlema, production losses and unmined resources, the total uranium content was about 96,000 tonnes of uranium, making Schneeberg-Schlema-Alberoda the largest vein-style uranium deposit in the world.
After the political changes production slowed down in 1990 and eventually stopped on 31 December 1990. Together with the closure of the uranium mine at Pöhla and the tin mines at Altenberg and Ehrenfriedersdorf this ended the 800-year-old history of metal mining in the Ore Mountains. After the end of production, the newly formed Wismut GmbH as successor of SDAG Wismut started restoration of the area. Flooding of the mine started in 1991 and in 1997 the water reached the -540 m level as the uppermost level of shaft 371. At this point, the mine was opened for the public as the deepest tourist mine in Europe. A water treatment plant was erected with a final capacity of 1,300 m3 per hour, removing uranium, radium, arsenic and iron from the contaminated mine water before releasing it into the Zwickauer Mulde river. Underground work, especially in Oberschlema, is being carried out to secure near-surface galleries and shafts from collapse and to provide safe airways for radon-containing mine air to prevent it from uncontrolled movement into populated areas of the region. The huge waste rock dumps were either relocated or recontoured and covered with 80 cm of clay and 20 cm of top soil. In 2008, most of the underground work was finished and nearly all shafts were sealed. Most dumps are poorly restored. Shaft 382 with a depth of 1,400 m will stay open and provide a controlled path for radon-bearing air to escape from the mine. There is still some uranium being won as a consequence of the restoration program; it is being purchased by the USA with long-term contracts.
Like most deposits in the western Ore Mountains, the Schneeberg-Schlema-Alberoda deposit is situated on the Gera-Jachymov fault zone. This major geological structure with a length of several hundred kilometres strikes NW-SE, running from the central Bohemian Massif in the Czech Republic to central Germany. The main element of this fault zone in the Ore Mountains is the Roter Kamm fault carrying a young quartz-hematite mineralisation, but no uranium. This fault forms the boundary between the Schneeberg and Oberschlema deposits, having a vertical displacement of about 400 m. The second controlling element for the deposit are Variscan granites, which underlie the deposit. The mineralised veins are within the exocontact of the granite, although the oldest uranium mineralisation is about 20 Ma younger than those granites. The third controlling factor is a heavily deformed unit of Ordovician to Silurian meta-sedimentary rocks. This so-called Loessnitz-Zwoenitz-Trough runs east-west, broadening toward the east. This rock unit is formed by quartzites, meta-black shales, amphibolites and skarns. It is contained within phyllites, which form the major rock type in this area of the Ore Mountains. The rocks of the Loessnitz-Zwoenitz-Trough are called the 'productive series', because they carry nearly all of the mineralisation. Although the vein structures can be followed from the productive series into the phyllites and granites, no significant mineralisation has been observed outside of it. The ore field contains about 1,800 mineralised veins. Uranium-bearing veins run approximately northwest to southeast, parallel to the Roter Kamm fault.
The oldest type of mineralisation consists of quartz, calcite, fluorite, pitchblende and minor hematite. The age of this primary mineralisation is about 270 Ma and it was the most important type in Oberschlema. About 100 Ma later a second uranium mineralisation formed. Veins of this type contain dolomite, calcite, pitchblende, minor sulphides and selenides. This mineralisation event did not bring new uranium into the deposit but remobilised uranium from the older mineralisation. These dolomite-uranium veins were the major uranium formation in Niederschlema-Alberoda. A third uranium-bearing vein type contains quartz, calcite, Co- and Ni-arsenides, native bismuth, silver and pitchblende. Like the dolomite veins, there was no input of new uranium but only remobilisation. These were the most important veins in Schneeberg, not only for uranium but also for Ag and Co-Ni production. Telescoping is also a common feature with different types of mineralisation being found stuck together in the same part of the vein.
Beside the uranium-bearing mineralisation types, there are about one dozen different styles of other mineralisation ranging from Sn-W, Pb-Zn, fluorite-barite to quartz-hematite. They had no economic importance but contributed to the large variety of the several hundred minerals known from the deposit. Especially in the oxidation zones of Schneeberg and Oberschlema, many rare secondary minerals are found, with many of them being newly discovered there. For example, in samples from a single ore shot in Schneeberg five new uranium minerals were discovered in 1871, namely walpurgite, zeunerite, troegerite, uranospinite and uranosphaerite.