Uranium mining
Uranium mining is the extraction of uranium from uranium deposits . The largest uranium mining countries are Canada , Australia , Kazakhstan , Russia , Niger , Namibia , Uzbekistan and the USA . Around 70% of the known uranium reserves in North America are found on indigenous land. Uranium can also be extracted from the ashes of coal-fired power plants .
Test drilling and uranium mining mark the beginning of the uranium economy . Fuel elements for nuclear power plants are produced over several processing stages (processing into yellow cake , then chemical conversion to uranium hexafluoride and uranium enrichment ) .
Exploration
At the beginning of the exploration is the choice of the exploration concept. Depending on the geology, different areas show the potential for different types of uranium deposits. This also determines the exploration method to be used. This can range from classic geological field work (mapping of rock units and tectonic structures), water and soil air measurements to geophysical methods such as magnetic , gravimetric or radiometric measurements. Due to the high costs, drilling is usually only used in a late phase of exploration, when previous methods demonstrate a significant potential for uranium mineralization. If mineralization is found that warrants further interest, a more closely meshed network of holes follows in order to determine the size of the deposit and to check its profitability.
Deposits currently in operation contain between a few hundred thousand and a few hundred million tons of ore with uranium contents between 0.01% by weight and 15% by weight. The largest uranium resource is currently the Olympic Dam deposit in South Australia with at least 8.4 billion tons of ore and an average of 0.028 wt.% Uranium (the main resource is copper, however, gold and silver).
Extraction
Uranium is extracted in open-cast mining , underground mining or by in-situ leaching. The selected extraction method depends on the properties of the ore body , such as depth, shape, ore content, tectonics, type of host rock and other sizes. Uranium can arise as a by-product in the extraction of other raw materials, just as uranium mining itself can also produce other metals.
Civil engineering
A large part of the uranium is extracted in civil engineering at depths of 100 to over 2000 m. The deposits are accessed via shafts , tunnels , ramps or spirals . Problems are caused by the penetrating pit water and the ventilation . The pit water must be lifted and, if necessary, cleaned of heavy metals. When ventilating, it must be ensured that the radon formed during the radioactive decay of uranium and its secondary products does not exceed the maximum concentration in the workplace. In the past, inadequate ventilation was the main cause of lung cancer in many miners .
The special mining method is in turn selected according to the properties of the deposit . Above all, the shape of the ore bodies and the distribution of the uranium in them are decisive. An ore body can be mined in a targeted manner in civil engineering, which results in much less overburden than in open-cast mining. In modern mines, extraction is mainly carried out with diesel-powered trackless technology. The largest underground mine is currently McArthur River in Saskatchewan, Canada, with an annual production of around 7200 tons of uranium.
Open pit
Ore bodies close to the surface or very large are preferably extracted in opencast mining. This enables the use of cost-effective large-scale technology. Modern open-cast mines can be a few meters to over 1000 m deep and a few kilometers in diameter. Large amounts of overburden are often produced in open-cast mining. As in civil engineering, large amounts of water may have to be lifted for an opencast mine , but ventilation is less of a problem. The Ranger III opencast mine in the Australian Northern Territory is currently the most productive uranium mine with around 4,600 t of uranium per year. The Rössing mine in Namibia is the largest uranium mine in the world.
Solution mining
Sandstone-bound uranium deposits can be made usable through solution mining (also ISL for in-situ leaching or ISR for in-situ recovery ). The ore body is tapped by drilling and an oxidizing fluid is introduced which mobilizes the uranium. Usually it is dilute sulfuric acid . The solution is introduced into the ore body via injection holes located in the outer area of the ore body. In the center of the ore body, the production wells are drilled, which extract the uranium-containing solution. This ensures a flow of the fluid to the center of the deposit and prevents uncontrolled distribution in the rock. There are monitoring wells in the larger area surrounding the deposit, with which it is monitored that there is no contamination in the area surrounding the deposit.
In order to be able to use this method, the uranium-containing rock must have a certain permeability in order to allow the solution to flow. In addition, it should be bounded above and below by impermeable (clayey) rocks. Solution mining enables the cost-effective extraction of small ore bodies. The advantage is that there is no actual movement of rock and no overburden is produced.
The solution mining is to play a bigger role in the future, there are significant companies in Kazakhstan, Uzbekistan, the USA and Australia. The most important operation in 2009 was Tortkuduk (owners: Areva and Kazatomprom ) in Kazakhstan with an uranium extraction of 2272 t per year.
A modification of the method was used in the Königstein deposit ( Saxon Switzerland ). The mine was converted from conventional civil engineering to underground extraction. To improve the yield, the mineralized sandstone was divided into mining blocks, which were first blasted and then leached.
Uranium as a by-product
Uranium is extracted as a by-product in various plants. Most important due to its size is the Olympic Dam deposit , in which, together with gold and silver, around 3,400 t of uranium per year are extracted as a by-product of copper mining (200,000 t per year). A feasibility study is currently being carried out by the operator BHP Billiton for the development of the southern part of the deposit, with production being gradually increased to 700,000 t of copper and around 15,000 t of uranium oxide per year. Significant uranium production also took place in the gold mines of the Witwatersrand gold field in South Africa. This is to be resumed, whereby the economic importance of uranium could outweigh that of gold. Uranium was also extracted from the waters of oil production in the former Soviet Union. Uranium from lignite filter ash is also likely to gain importance in the future. There are corresponding projects in Hungary and China. Some phosphate deposits also contain uranium in recoverable concentrations. In the past, extraction from such deposits played a role primarily in the USA and is now being discussed again in various countries.
By-products of uranium mining
The uranium deposits on the Colorado Plateau in the USA were also a very important supplier for the steel refiner vanadium in the past . The large uranium deposit Jabiluka in Australia's Northern Territory contains a large amount of gold. However, further work on this deposit has been stopped by the owner ERA (Energy Resources Australia) for the time being, as there was great resistance to mining due to the location in Kakadu National Park . Deposits similar to Jabiluka in Canada sometimes contain high levels of nickel, but this metal was not extracted due to the difficult processing. In uranium deposits in the Ore Mountains, copper, cobalt, nickel, bismuth, lead, zinc, silver, tin, selenium and building materials were also extracted to a small extent by the SAG / SDAG Wismut .
Unconventional extraction
Processes that are not currently used on an industrial scale are referred to as unconventional processes. This includes, for example, the extraction of uranium from black shale , phosphate rock or lignite.
In principle, uranium extraction from seawater is also possible, which is the largest known uranium deposit with a uranium content of around 4.5 billion tons. For this purpose, special absorbers could be placed on coasts with a high tidal range or within natural ocean currents. Based on tests in the USA and Japan, the cost of uranium from seawater was estimated at around $ 300 / kg. This is far above today's market prices; the production costs of electrical energy would increase by less than € 0.01 / kWh if this expensive uranium were used (use in today's light water reactors, without reprocessing). Since these additional costs are manageable, uranium from seawater must be viewed as an economically accessible long-term reserve (several tens of thousands of years with today's consumption), provided that the extraction processes can also be implemented on an industrial scale.
Coal almost always contains traces of the radioactive elements uranium , thorium and radium . The content is between a few ppm and 80 ppm, depending on the deposit . Since around 7,800 million tons of coal are burned in coal-fired power plants worldwide every year , the total emissions are estimated at 10,000 tons of uranium and 25,000 tons of thorium, which is largely contained in the ash. The ash from European coal contains around 80-135 ppm uranium.
Between 1960 and 1970, around 1,100 tons of uranium was extracted from coal ash in the United States. In 2007, the Chinese National Nuclear Corp commissioned the Canadian company Sparton Resources, in cooperation with Beijing No. 5 Testing Institutes conduct trials to extract uranium from the ashes of the Xiaolongtang coal-fired power station in Yunnan Province . The uranium content of the ashes from this power plant is 210 ppm uranium (0.021% U) on average, higher than the uranium content of some uranium ores.
Processing of uranium ore
The uranium present in the ore is separated (digested) from the rest of the rock by physical and chemical processes. For this purpose, the ore is crushed (broken, finely ground) and the uranium is extracted (leached). This is done with acid or alkali with the addition of an oxidizing agent in order to convert the uranium from the very poorly soluble chemically tetravalent state to the readily soluble hexavalent form. In this way, over 90 percent of the uranium in the ore can be extracted.
Unwanted accompanying substances are removed in several cleaning steps by decanting , filtering , extracting , etc. Uranium is precipitated from the liquid , for example by adding ammonia . The precipitated product (chemically: ammonium diuranate ) is called " yellowcake " because of its yellow color . In dried form, it contains 70 to 80 percent by weight uranium. This material is partly converted into uranium oxide by calcination at the mining site .
The residues from uranium processing ( tailings ) must be safely stored in special tanks for a long time. They still contain the largest part of the activity inventory of the original uranium ore (in the form of the decay products of uranium such as radium) and heavy metals.
Uranium mining by country
Germany
In Germany, the first uranium ore was mined in Johanngeorgenstadt in 1839 .
Until 1939,
approx. 104 tons of uranium ore mined.
Of these, Schneeberg supplied 60 t and Johanngeorgenstadt 29 t. Extraction was sporadic and peaked between 1880 and 1890. Despite state funding programs between 1910 and 1921 and from 1934, no significant uranium deposits were found in the areas mentioned. At the end of the Second World War, the defunct German Empire had the largest reserves of uranium oxide in the world, most of which, however, did not come from Germany, but from other countries.
East Germany
After the Second World War , the SAG / SDAG Wismut operated intensive uranium mining in the Soviet occupation zone of Germany and later the GDR . Some of the uranium deposits in the Ore Mountains were known before the war, but they were only exploited to a limited extent. Until 1945 it was assumed that there were only small stocks. The investigations carried out in 1945 by the Saxon ore search group and from 1946 by the Saxon extraction and exploration group led to the discovery of larger reserves. The SAG / SDAG Wismut exploration program was expanded to include the entire SBZ / GDR. The black slate deposits near Ronneburg in East Thuringia, the uranium mineralization of the coals of the Döhlen basin and the Königstein sandstone deposit in Saxon Switzerland were discovered.
Up to 1990 about 216,300 tons of uranium were mined, half of which in Thuringia and Saxony. The last inventory balance of SDAG Wismut was available on January 1, 1991. This named deleted reserves amounting to 251,510 t of uranium, balance reserves of 57,922 t of uranium and prognostic resources of 74,078 t of uranium.
West Germany
In the three western zones, on the other hand, there were only smaller uranium deposits in the Black Forest , in the Bavarian Forest and in the Fichtel Mountains . The small deposits Poppenreuth, Mähring , Wittichen and Rudolphstein, as well as the small deposits Müllenbach (3000 tons), Großschloppen (1500 tons) and Hebanz were explored. The uranium ores occurring in the Wölsendorf river spar area were also examined. The only deposit that got beyond the exploration stage was Menzenschwand . Between 1973 and 1991, around 480 tons of metallic uranium were mined here. The prognostic reserves amount to approximately 3500 tons of uranium.
Federal Republic of Germany after reunification
After reunification, uranium mining in the GDR, which had not previously covered costs, was no longer viable after the Soviet Union had stopped making payments in 1990 and was stopped in 1991. In the same year the SDAG Wismut was converted into the federally owned Wismut GmbH. After the mining rights were withdrawn, the Brunhilde union went bankrupt in 1991 and mining in Menzenschwand was stopped. The remediation of the legacy of the Wismut was assigned to the Federal Republic of Germany in the 2 + 4 treaty and stipulated that the Soviet Union and its successor states do not have to bear these costs. Since 1990 the various mining operations of Wismut GmbH have been shut down, converted into renovation operations and gradually closed. During the remediation, uranium continues to be produced , mainly through the cleaning of the flooding water from the Königstein remediation company . This is sold and the proceeds used for the renovation. In 2012, around 50 tons of uranium were sold, representing the inventory for several years. At other locations, such as Schlema , Ronneburg and Pöhla , pollutants (uranium, radium , arsenic , iron and manganese ) are removed from the mine water in water treatment plants, solidified with cement and deposited. The treated waters are fed into the natural cycle via flowing waters .
United States
In early 2012, the US government imposed a 20-year moratorium on exploring new uranium deposits in the Grand Canyon due to potential conflicts with tourism and environmental issues .
In April 2014, the energy company Anadarko Petroleum reached an agreement with the United States Department of Justice to pay US $ 5.15 billion (EUR 3.75 billion) for pollution of its subsidiary Kerr-McGee Corporation at 2,700 contaminated sites by uranium mining. Around $ 4.4 billion of the agreed payment is expected to be spent on decontaminating contaminated land.
Other states
If you would like to see a detailed map of the world on mining "freely movable" in large format (5.6 MB), follow this link
There are many other countries around the world that are mining uranium, such as Brazil, Canada, Australia, China, Kazakhstan, Congo, Namibia, South Africa. In addition, other states are planning to introduce or expand uranium mining. This happened, for example, at the end of 2013 when the permit for mining was granted in Kvanefjeld (South Greenland), where a uranium deposit was found in a highly sensitive arctic nature (see world map).
| rank | country | Promotion (in k t ) |
|---|---|---|
| 1 |
 Kazakhstan
|
21.3 |
| 2 |
 Canada
|
9.0 |
| 3 |
 Australia
|
7.0 |
| 4th |
 Niger
|
4.7 |
| 5 |
 Namibia
|
4.5 |
| 6th |
 Russia
|
2.9 |
| 7th |
 Uzbekistan
|
2.4 |
| 8th |
 United States
|
1.6 |
| 9 |
 People's Republic of China
|
1.5 |
| 10 |
 Malawi
|
1.1 |
Source: Federal Institute for Geosciences and Raw Materials.
Risks
Uranium is a weakly radioactive element, which in its natural deposits does not initially pose a threat to the environment. The uranium content of currently used deposits fluctuates considerably between 0.03 and 18 percent. The radiotoxic hazard of the overburden is roughly in the same order of magnitude as that of the natural radiation intensity. In addition, the dead rock from which the overburden is made has sometimes high concentrations of other metals, which can pose a threat to the environment. Depending on the type of deposit, extraction method and storage, the uranium and heavy metal compounds still present on the spoil heaps can pollute the drinking water or contaminate remote areas by spreading dust.
Now that uranium mining has ceased completely in five Western European countries, around half of uranium production is currently taking place in sparsely populated areas of Kazakhstan, Canada and Australia. In Canada and Australia, mainly native people are affected, who are now politically and legally defending themselves against the damage that occurs. Another quarter of the uranium is mined in Uzbekistan, Niger , Namibia and Russia. About 70% of the deposits are located under the land of indigenous peoples, who are particularly affected by the consequences of uranium mining.
Overburden
The legacy of uranium mining in the form of spoil heaps , sedimentation lakes , landfills, etc., also in countries that no longer mine uranium ore, such as Tajikistan and Germany , pose a long-term risk to the local population and the environment from the radionuclides naturally occurring in uranium ore .
Possible CO 2 pollution of the environment
The study “Energy balance of the nuclear industry”, prepared by the Austrian Ecology Institute and the Austrian Energy Agency in November 2011, predicts that, due to the strong demand for uranium and the decreasing uranium reserves worldwide, uranium extraction could become more and more expensive due to the decreasing uranium ore concentration in the deposits, and with increasing CO 2 pollution would be linked to the environment.
The uranium ore content would become the decisive factor in the energy production chain: from a limit value of approx. 0.01%, the processing of the extracted uranium ore becomes the process step with the highest energy expenditure (over 40% of the primary energy used ) and the energy intensity of the nuclear energy production process increases to over 100%, i.e. This means that the energy used exceeds the generated: the environmental energy balance becomes negative (see also the law of conservation of energy ); from an energetic point of view, nuclear energy production would no longer make sense (or would be sustainable ); from here on the value of up to 288 g CO 2 emissions per nuclear generated kWh of electrical energy is mentioned.
The study was carried out as part of the “New Energies 2020” program and funded by the Climate and Energy Fund.
According to a study from 2008, a content of "200 grams per tonne of rock" (presumably derived from the Anglo-American measuring system ) or 200 mg / kg "coal equivalence" would be given; The net energy gain that can be achieved from the uranium ore would be equal to the energy required for extraction (generated from coal combustion).
radon
A dangerous decay product of uranium is the noble gas radon , which escapes colorless and odorless from processing plants, heaps, sedimentation basins and waste dumps as well as from mine tunnels, including abandoned ones . Without a cover, considerable amounts of radon can be released over the long term from tailings and sedimentation basins . The release rate can be up to 10 Bq per square meter.
It can accumulate in insufficiently ventilated rooms above these facilities / locations and, if exposed to long-term exposure, lead to a significantly increased risk of lung cancer (Schneeberger disease). The International Agency for Cancer Research of the WHO as well as the Federal Office for Radiation Protection and the Radiation Protection Commission consider it to be proven that radon causes significant cancer even in low doses. A threshold could not be identified.
Accidents
In the shadow of the reactor accident at the Three Mile Island (TMI) nuclear power plant in 1979, an accident with uranium mining overburden occurred in the same year, which radiologically is considered to be the more serious. To reduce the radiation of the overburden, dams are often built and the waste behind is flooded with water. The rupture of such a dam on the Rio Puerco in New Mexico (USA) caused around 335,000 tons of radioactive water with around 1,000 tons of contaminated substances to flow into the Rio Puerco, which mainly serves as a water reservoir for the Diné , Hopi and Pueblo Indians . A measurement made immediately showed a value for drinking water that was 7000 times higher than the limit value. The information and education of the people affected turned out to be extremely difficult due to the lack of electronic means of communication and educational deficits; it is assumed that there are not a few cancer deaths.
Radio
- Thomas Gaevert : The Generational Project - Uranium Mining in East Germany and its Consequences - Production: Südwestrundfunk 2019, first broadcast: February 27, 2019, SWR 2
See also
literature
- WG Bachurow, SG Wetscherkin, IG Lutsenko: Underground leaching of uranium ores . Ed .: Chamber of Technology. Atomisdat , Moscow 1969 (150 p., Russian: Подземное выщелачивание урановых руд . Translated by Dr. Lothar Hartmann, Peter Fichtner).
- C. Keller: nuclear fuel cycle . Ed .: H. Möllinger. tape I . Hüthig, Heidelberg 1978, ISBN 3-7785-0507-6 .
- F.-K. Pickert: fuel cycle. German Atomic Forum , Bonn 1981, ISBN 3-922798-03-4 .
- Rimbert Gatzweiler, Diethard Mager: Contaminated sites of uranium mining (= The Geosciences . No. 11 ). 1993, p. 5–6 and 164–172 , doi : 10.2312 / geoscientific . 1993.11.164 .
- H. Nobukawa, M. Kitamura, SAM Swilem, K. Ishibashi: Development of a Floating Type System for Uranium Extraction from Sea Water Using Sea Current and Wave Power . In: Proceedings of the 4th International Offshore and Polar Engineering Conference, 10. – 15. April 1994 . Conference proceedings. Osaka 1994, p. 294-300 .
- Peter Diehl: Uranium Mining and Milling Wastes ( Memento from April 4, 2004 in the Internet Archive ) . An Introduction. 2003.
- State Parliament of Saxony, Parliamentary Documents, Drs. 4/51 25-2
Web links
- Information on the consequences of uranium mining.
- Wismut GmbH
- Wisutec , subsidiary of GEOS Freiberg mbH
- Cordula Meyer: Uranium mining in Niger: The yellow curse. In: Spiegel Online , April 2, 2010
- Bettina Rühl: The “clean” solution - From Niger and German nuclear power plants. dradio.de, Deutschlandfunk, Das Feature, October 26, 2010.
- terra incognita - Die Wismut , three-part documentary by Um Welt Film Produktionsgesellschaft mbH , 2016
Individual evidence
- ↑ Australia's uranium, Research Note no. 17 2006-07, Parliamentary Library, Australia. ( Memento from February 2, 2012 in the Internet Archive )
- ↑ a b Nando Stöcklin : Uranium economy in North America . The consequences for the indigenous people. Ed .: Incomindios Switzerland . Zurich 2001, p. 9 .
- ↑ a b c d e World Uranium Mining . World Nuclear Association, July 2008
- ↑ Klaus Schwochau: Uranium from sea water. In: News from chemistry, technology and the laboratory. 27, 1979, p. 563, doi: 10.1002 / nadc.19790270907 .
- ↑ jolisfukyu.tokai-sc.jaea.go.jp ( Memento from June 12, 2008 in the Internet Archive )
- ↑ PDF at jolisfukyu.tokai-sc.jaea.go.jp (PDF)
- ^ Naturally-Occurring Radioactive Materials
- ^ Radioactivity in Coal Ash
- ^ Dietmar Leopold and Michael Paul The reference project Wismut: Restoration and revitalization of uranium ore mining sites in Saxony and Thuringia. in: Proceedings of the International Mining Symposium WISMUT 2007. Gera, September 10-12, 2007: 21-30
- ^ Author collective: Chronicle of the bismuth . Ed .: Wismut GmbH, Public Relations Department, W. Runge. Wismut GmbH, Chemnitz 1999, 1.3.6, p. 14 (CD-ROM).
- ↑ Heike Wipperfürth: dradio.de No uranium mining in the Grand Canyon. In: Deutschlandfunk, Environment and Consumers, January 10, 2012 (January 14, 2012)
- ↑ Süddeutsche.de: US energy company pays record fine for pollution from April 4, 2014.
- ↑ AtomkraftwerkePlag Wiki: Uranium Mining / Uranium Mining Worldwide
- ↑ Greenland allows uranium mining . Euronews.com of October 25, 2013.
- ↑ Reserves, resources and availability of energy resources 2013. (PDF 11.5 MB) Federal Institute for Geosciences and Natural Resources (BGR), p. 94 , accessed on December 6, 2014 .
- ↑ Peter Diehl: Range of the uranium reserves in the world . Greenpeace Germany, Berlin January 2006 ( greenpeace.de [PDF]).
- ↑ Zoriy, P., Schläger, M., Murtazaev, K., Pillath, J., Zoriya, M., Heuel-Fabianek, B .: Monitoring of uranium concentrations in water samples collected near potentially hazardous objects in North-West Tajikistan . Journal of Environmental Radioactivity. No. 181, 2018, pp. 109–117, doi: 10.1016 / j.jenvrad.2017.11.010 .
- ↑ Video ZDF Environment: Radiant Namibia in the ZDFmediathek , accessed on February 11, 2014. (offline)
- ↑ B. Heuel-Fabianek, M. Schläger: The legacy of uranium extraction in Tajikistan. In: StrahlenschutzPRAXIS. 4/2010, pp. 53-59.
- ↑ Austrian Ecology Institute and Austrian Energy Agency: Summary of the study: Energy balance of the nuclear industry. (PDF; 1MB) November 2011, accessed on March 4, 2012 .
- ↑ Storm van Leeuwen, JW, Smith, P. (2007 and 2008): Nuclear power - The energy balance; Nuclear power insights, chapter "05 Climate change" Chaam, Netherlands; cited at the Austrian Ecology Institute and Austrian Energy Agency: Summary of the study: Energy balance of the nuclear industry. (PDF; 1MB) November 2011, accessed on January 31, 2019 .
- ^ Wiener Umweltanwaltschaft : New study on the life cycle analysis of nuclear energy (11/2011). (No longer available online.) November 2011, archived from the original on June 5, 2014 ; accessed on June 9, 2017 .
- ↑ literally: "At a grade of 200 gram uranium per ton rock as much ore has to be mined and processed as the amount of coal burned to generate the same amount of electricity. The leanest uranium ores exploited today are at or even below this grade .Storm van Leeuwen, JW, Smith, P. (2007 and 2008): Nuclear power - The energy balance; Nuclear power insights, chapter "05 Climate change" Chaam, Netherlands;
- ↑ M. Schläger, Kh. Murtazaev, B. Rakhmatuloev, P. Zoriy, B. Heuel-Fabianek: Radon Exhalation of the Uranium Tailings Dump Digmai, Tajikistan. Radiation & Applications. Vol. 1, No. 3, 2016, pp. 222–228, doi: 10.21175 / RadJ.2016.03.041 (Open Access).
- ^ IARC Working Group: Radiation IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, No. 100D IARC Working Group on the Evaluation of Carcinogenic Risk to Humans. (PDF) In: National Center for Biotechnology Information, US National Library of Medicine. International Agency for Research on Cancer, 2012, accessed on August 27, 2019 (English, page 241f).
- ↑ BfS - Health effects of radon - This is how radon affects health. Retrieved August 27, 2019 .