page_title: Wismut (mining company)
section_title: Milling
hierarchical_section_title: Wismut (mining company) / Milling
caption_attribution_description: For documentary purposes the German Federal Archive often retained the original image captions, which may be erroneous, biased, obsolete or politically extreme. Culmitzsch, Halde der Wismut, Uranerzaufbereitung ADN-Jan-Peter Kasper 25.10.90 Thüringen: Voller Betrieb herrscht noch auf der industriellen Absetzanlage der Wismut in Culmitzsch: Hier werden Rückstände aus der Uran-Erzaufbereitung endgelagert.
context_page_description: 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.
context_section_description: In the early years of mining, sorting of ore started in the vein style deposits directly on the stopes. High grade ore containing more than 1% uranium was handpicked and later automatically separated and shipped to the Soviet Union without further processing until 1980. Ore containing less than 1% (Fabrikerz - factory ore) was sent to mills. In the early years of SAG Wismut, it simply took over existing plants for processing its uranium ores. These were the mill of a tungsten mine in Lengefeld (Vogtland), the mill of the Tannenbergsthal (Vogtland) tin mine, a plant processing cobalt ore to produce colours at Oberschlema, a nickel processing plant at Aue, and some industrial areas at Freital. Further, a new mill was erected at Johanngeorgenstadt. These small mills produced different concentrates: mechanical, wet-mechanical and chemical (yellowcake). A total of 18 million tonnes of ore were processed in these smaller mills, and the last was shut down in 1962. Milling was concentrated at two central milling sites situated between Zwickau and Ronneburg.
  The mill at Crossen (a northern suburb of Zwickau) was erected in 1950 using the site of a former paper mill. It was called Object 101 / Factory 38 (later renamed Aufbereitungsbetrieb 101 - milling division 101) and processed ore from all major Wismut deposits. It produced mechanical as well as chemical concentrates and used for the latter one an alcalic-based technology resulting in yellowcake containing more than 70% uranium. The mill processed a total of 74.7 million tonnes of ore, producing 77,000 tonnes of uranium before it was shut down in 1989. Experimental milling was also carried out to process silver and tin ore from the deposits at Niederschlema-Alberoda and Pöhla.
  In 1961 the most modern milling plant (called Aufbereitungsbetrieb 102 - milling division 102) started production at Seelingstädt. It was built near the open pits of the Culmitzsch deposit which it used as tailings management facilities. It processed the majority of ore from Ronneburg, ore and solutions from Königstein, and also ore from the Ore Mountains. Depending on the chemistry of the ore it used both acid and soda-alcalic processes to produce yellowcake. It processed in total 108.8 million tonnes of ore producing concentrate containing 86,273 tonnes of uranium.
  About 216,000 tonnes of uranium were delivered in chemical and mechanical concentrates from the mills to the Soviet Union and about 15,000 tonnes were shipped in unprocessed high-grade ore directly from the mines.
  The restoration of the tailings storage facilities at the milling sites is a major issue for Wismut GmbH. The tailings at both sites have a total volume of 152 million m³ and contain between 50 and 300 g/t uranium and between 50 and 600 g/t arsenic. The activity of radium in the tailings has a total value of 1.5*10¹⁵ Bq.
caption: Tailings of Seelingstädt mill in 1990
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