Uranium mining is the process of extraction of uranium ore from the ground. As uranium ore is mostly present at relatively low concentrations, most uranium mining is very volume-intensive, and thus tends to be undertaken as open-pit mining. It is also undertaken in only a small number of countries of the world, as the resource is relatively rarely found.
The worldwide production of uranium in 2003 amounted to 41,429 tonnes, of which 25% was mined in Canada. Other important uranium mining countries are Australia, Russia, Niger, Namibia, Kazakhstan, Uzbekistan, South Africa, and the USA.
A prominent use of uranium from mining is as fuel for nuclear power plants. As of 2008, known uranium ore resources which can be mined at about current costs are estimated to be sufficient to produce fuel for about a century, based on current consumption rates.
Uranium minerals were noticed by miners for a long time prior to the discovery of uranium in 1789. The uranium mineral pitchblende was reported from the Saxonian Ore Mountains (Erzegebirge) as early as 1565. Other early reports of pitchblende date from 1727 (Joachimsthal) and 1763 (Schwarzwald).
In the early 1800s, uranium ore was recovered as a by-product of mining in Saxony, Bohemia, and Cornwall. The first deliberate mining of radioactive ores took place in Jáchymov (also known by its German name, Joachimsthal), a silver-mining city in what is now the Czech Republic. Marie Curie used pitchblende ore from Jáchymov to isolate the element radium, a decay product of uranium; her death was from aplastic anemia, almost certainly due to exposure to radioactivity. Until World War II uranium mining was done primarily for the radium content. Sources for radium (contained in uranium ore) were sought for use as luminous paint for watch dials and other instruments, as well as for health-related applications (some of which in retrospect were incredibly unhealthy). The byproduct uranium was used mostly as a yellow pigment.
In the United States, the first radium/uranium ore was discovered in 1871 in gold mines near Central City, Colorado. This district produced about 50 tons of high grade ore between 1871 and 1895. However, most American uranium ore before World War II came from vanadium deposits on the Colorado Plateau of Utah and Colorado.
In Cornwall, the South Terras Mine near St. Stephen opened for uranium production in 1873, and produced about 175 tons of ore before 1900. Other early uranium mining occurred in Autunois in France's Massif Central, Oberpfalz in Bavaria, and Billingen in Sweden.
The Shinkolobwe deposit in Katanga, Belgian Congo now Shaba Province, Zaire was discovered in 1913, and exploited by the Union Minière du Haut Katanga. Other important early deposits include Port Radium, near Great Bear Lake, Canada discovered in 1931, along with Beira Province, Portugal; Tyuya Muyun, Uzbekistan, and Radium Hill, Australia.
Because of the need for the uranium for bomb research during World War II, the Manhattan Project used a variety of sources for the element. The Manhattan Project initially purchased uranium ore from the Belgian Congo, through the Union Minière du Haut Katanga. Later the project contracted with vanadium mining companies in the American Southwest. Purchases were also made from the Eldorado Mining and Refining Limited company in Canada. This company had large stocks of uranium as waste from its radium refining activities.
American uranium ores mined in Colorado were mixed ores of vanadium and uranium, but because of wartime secrecy the Manhattan Project would only publicly admit to purchasing the vanadium, and did not pay the uranium miners for the uranium content. (In a much later lawsuit, many miners were able to reclaim lost profits from the U.S. government.) American ores had much lower uranium concentrations than the ore from the Belgian Congo, but they were pursued vigorously to ensure nuclear self-sufficiency.
Similar efforts were undertaken in the Soviet Union, which did not have native stocks of uranium when it started developing its own atomic weapons program.
Intensive exploration for uranium started after the end of World War II as a result of the military and civilian demand for uranium. There were three separate periods of uranium exploration or "booms." These were from 1956 to 1960, 1967 to 1971, and from 1976 to 1982.
In the 20th century the United States was the world's largest uranium producer. Grants Uranium District in northwestern New Mexico was the largest United States uranium producer. The Gas Hills Uranium District, was the second largest uranium producer. The famous Lucky Mc Mine is located in the Gas Hills near Riverton, Wyoming. Canada has since surpassed the United States as the cumulative largest producer in the world.
Australia has the world's largest uranium reserves - 24 percent of the planet's known reserves. The majority of these reserves are located in South Australia with other important deposits in Queensland, Western Australia and the Northern Territory. Almost all the uranium is exported under strict International Atomic Energy Agency safeguards to satisfy the Australian people and government that none of the uranium is used in nuclear weapons. Australian uranium is used strictly for electricity production; however, some argue this still frees other uranium to be used in weapons.
The Olympic Dam operation run by BHP Billiton in South Australia is combined with mining of copper, gold, and silver, and has reserves of global significance. There are currently three operating uranium mines in Australia, and several more have been proposed. The expansion of uranium mining in Australia is supported by the Federal Australian Labor Party (ALP) Government headed by Prime Minister Kevin Rudd. The ALP abandoned its long-standing and controversial "no new uranium mines" policy in April 2007. One of the more controversial proposals was Jabiluka, to be built inside the World Heritage listed Kakadu National Park. The existing Ranger Uranium Mine is surrounded by the National Park as the mine area was not included in the original listing of the Park.
Uranium mining and export and related nuclear issues have often been the subject of public debate, and the anti-nuclear movement in Australia has a long history.
Canada's first uranium discovery was in the Alona Bay area, south of Lake Superior Provincial Park in Ontario, by Dr. John Le Conte in 1847. But the Canadian uranium industry really began with the 1932 discovery of pitchblende at Port Radium, Northwest Territories. The deposit was mined from 1933 to 1940, for radium, silver, copper, and cobalt. The mine shut down in 1940, but was reopened in 1942 by Eldorado Mining and Refining Limited to supply uranium to the Manhattan Project. The Canadian government expropriated the Port Radium mine and banned private claimstaking and mining of radioactive minerals.
In 1947 the government lifted the ban on private uranium mining, and the industry boomed through the 1950s, spurred by high prices due to the nuclear weapons programs. Production peaked in 1959, when 23 mines in five different districts made uranium Canada’s number-one export. That same year, however, Great Britain and the United States announced their intention to halt uranium purchases in 1963. By 1963, seven mines were left operating, a number that shrunk to only three in 1972.
A price rise caused uranium to boom again in 1975 and 2005.
Uranium was discovered at Blind River-Elliot Lake area in 1949, and production began in 1955. The deposits are in Precambrian quartz-pebble conglomerates, similar to uranium deposits in Brazil and South Africa.
Today the Athabasca Basin in northern Saskatchewan hosts the largest high-grade uranium mines and deposits. Cameco, the world’s largest low-cost uranium producer, which accounts for 18% of the world’s uranium production, operates three mines and one dedicated mill in the region. Among the major mines are Cameco's flagship McArthur River mine, the developing Cigar Lake mine, the Rabbit Lake mine and mill complex, and the world's largest uranium mill at Key Lake. French-owned uranium syndicate Areva also operates the McClean Lake mill. Most of these mines are joint ventures between Cameco, Areva, and various other joint venture shareholders. Future mines currently in early development stages include Areva's Midwest Project (near McClean Lake), and Cameco's Millennium Project (near Key Lake). As of 2007, with uranium spot market prices well over the $100 USD/lb mark, Saskatchewan has become a hotbed of uranium exploration, with many junior exploration companies rushing to explore the highly valuable Athabasca basin.
Most uranium ore in the United States comes from deposits in sandstone, which tend to be of lower grade than those of Australia and Canada. Because of the lower grade, many uranium deposits in the United States became uneconomic when the price of uranium declined sharply in the 1980s.
Regular production of uranium-bearing ore in the United States began in 1898 with the mining of carnotite-bearing sandstones of the Colorado Plateau in Colorado and Utah, for their vanadium content. The discovery of radium by Marie Curie, also in 1898, soon made the ore also valuable for radium. Uranium was a by-product. By 1913, the Colorado Plateau uranium-vanadium province was supplying about half the world supply of radium. Production declined sharply after 1923, when low-cost competition from radium from the Belgian Congo and vanadium from Peru made the Colorado Plateau ores uneconomic.
Mining revived in the 1930s with higher prices for vanadium. American uranium ores were in very high demand by the Manhattan Project during World War II, although the mining companies did not know that the by-product uranium was suddenly valuable. The late 1940s and early 1950s saw a boom in uranium mining in the western US, spurred by the fortunes made by prospectors such as Charlie Steen.
Uranium mining declined with the last open pit mine (Shirley Basin, Wyoming) shutting down in 1992. United States production occurred in the following states (in descending order): New Mexico, Wyoming, Colorado, Utah, Texas, Arizona, Florida, Washington, and South Dakota. The collapse of uranium prices caused all conventional mining to cease by 1992. In-situ leach mining has continued primarily in Wyoming and adjacent Nebraska as well has recently restarted in Texas. Rising uranium prices since 2003 have increased interest in uranium mining in the United States.
The Grand Canyon Watersheds Protection Act has been proposed. This is a bill that would permanently ban uranium mining in the area. The impacts of uranium development have raised concerns of scientists and government officials alike. Due to increasing demand, uranium projects have been on the increase posing a threat to water, public health, and fragile desert ecosystems.
Today, the Rožná underground facility is Europe’s only operating uranium mine, continuously operating since 1957. Since 2007, the Australian company Uran Ltd. is interested to participate in the operations at Rožná, as well as seeking permits with the Czech Ministry of Trade and Resources to open mines in Czechia at other known locations, like Brzkov, Jamné, Polná and Věžnice, through its Czech partner Timex Zdice and since 2008 through its subsidiary Urania Mining.
Niger's uranium came to world attention before the US invasion of Iraq, when it was asserted that Iraq had attempted to buy uranium from Niger (see Niger uranium forgeries).
The Geiger counter was the original radiation detector, recording the total count rate from all energy levels of radiation. Ionization chambers and Geiger counters were first adapted for field use in the 1930s. The first transportable Geiger–Müller counter (weighing 25 kg) was constructed at the University of British Columbia in 1932. H.V. Ellsworth of the GSC built a lighter weight, more practical unit in 1934. Subsequent models were the principal instruments used for uranium prospecting for many years, until geiger counters were replaced by scintillation counters.
The use of airborne detectors to prospect for radioactive minerals was first proposed by G.C. Ridland, a geophysicist working at Port Radium in 1943. In 1947, the earliest recorded trial of airborne radiation detectors (ionization chambers and Geiger counters) was conducted by Eldorado Mining and Refining Limited. (a Canadian Crown Corporation since sold to become Cameco Corporation). The first patent for a portable gamma-ray spectrometer was filed by Professors Pringle, Roulston & Brownell of the University of Manitoba in 1949, the same year as they tested the first portable scintillation counter on the ground and in the air in northern Saskatchewan.
Airborne gamma-ray spectrometry is now the accepted leading technique for uranium prospecting with worldwide applications for geological mapping, mineral exploration & environmental monitoring.
A deposit of uranium, discovered by geophysical techniques, is evaluated and sampled to determine the amounts of uranium materials that are extractable at specified costs from the deposit. Uranium reserves are the amounts of ore that are estimated to be recoverable at stated costs.
Sandstone uranium deposits are generally of two types. Roll-front type deposits occur at the boundary between the up dip and oxidized part of a sandstone body and the deeper down dip reduced part of a sandstone body. Peneconcordant sandstone uranium deposits, also called Colorado Plateau-type deposits, most often occur within generally oxidized sandstone bodies, often in localized reduced zones, such as in association with carbonized wood in the sandstone.
Precambrian quartz-pebble conglomerate-type uranium deposits occur only in rocks older than two billion years old. The conglomerates also contain pyrite. These deposits have been mined in the Blind River-Elliot Lake district of Ontario, Canada, and from the gold-bearing Witwatersrand conglomerates of South Africa.
Underground uranium mining is in principle no different to any other hard rock mining and other ores are often mined in association (eg copper, gold, silver). Once the ore body has been identified a shaft is sunk in the vicinity of the ore veins, and crosscuts are driven horizontally to the veins at various levels, usually every 100 to 150 metres. Similar tunnels, known as drifts, are driven along the ore veins from the crosscut. To win the ore, the next step is to drive tunnels, known as raises when driven upwards and winzes when driven downwards through the deposit from level to level. These raises are subsequently used to develop the stopes where the ore is mined in the veins.
The stope, which is the workshop of the mine, is the excavation from which the ore is being extracted. Two methods of stope mining are commonly used. In the “cut and fill” method and open stopping method, the space remaining following removal of ore after blasting is filled with waste rock and cement. In the “shrinkage” method just sufficient broken ore is removed via the chutes below to allow the miners to work from the top of the pile to drill and blast for the next layer to be broken off; eventually leaving a large hole. Another method, known as room and pillar, is used for thinner flatter ore bodies. In this method the ore body is first divided into blocks by intersecting drives, removing ore while so doing, and then systematically removing the blocks, leaving sufficient for roof support.
Piles of these tailings often contain elevated concentrations of radioisotopes compared to normal rock. Other waste piles consist of ore with too low a grade for processing. The transition between waste rock and ore depends on technical and economic feasibility criteria. All these piles threaten people and the environment after shut down of the mine due to their release of radon gas and seepage water containing radioactive and toxic materials.
In some cases uranium has been removed from this low-grade ore by heap leaching. This may be done if the uranium contents is too low for the ore to be economically processed in a uranium mill. The leaching liquid (often sulfuric acid) is introduced on the top of the pile and percolates down until it reaches a liner below the pile, where it is caught and pumped to a processing plant. Due to the potential for extreme damage to the surrounding environment , this practice is no longer in use.
Environmental impact studies are performed when evaluating ISL, because ground water can be affected. In-situ leaching is the only type of uranium mining currently being done in the United States (2006).
At the Takasaki Radiation Chemistry Research Establishment of the Japan Atomic Energy Research Institute (JAERI Takasaki Research Establishment), research and development has continued culminating in the production of adsorbent by irradiation of polymer fiber. Adsorbents have been synthesized that have a functional group (amidoxime group) that selectively adsorbs heavy metals, and the performance of such adsorbents has been improved. Uranium adsorption capacity of the polymer fiber adsorbent is high, approximately tenfold greater in comparison to the conventional titanium oxide adsorbent.
One method of extracting uranium from seawater is using a uranium-specific nonwoven fabric as an absorbent. The total amount of uranium recovered from three collection boxes containing 350 kg of fabric was >1 kg of yellowcake after 240 days of submersion in the ocean. According to the OECD, uranium may be extracted from seawater using this method for about $300/kg-U. The experiment by Seko et al. was repeated by Tamada et al in 2006. They found that the cost varied from ¥15,000 to ¥88,000 (Yen) depending on assumptions and "The lowest cost attainable now is ¥25,000 with 4g-U/kg-adsorbent used in the sea area of Okinawa, with 18 repetitionuses [sic]." With the May, 2008 exchange rate, this was about $240/kg-U.
At the height of the nuclear energy Euphoria in the 1950s methods for extracting diluted uranium and thorium, found in abundance in granite or seawater, were pursued. Scientists promised that, used in a breeder reactor, these materials would potentially provide limitless source of energy.
American military requirements declined in the 1960s, and the government completed its uranium procurement program by the end of 1970. Simultaneously, a new market emerged: commercial nuclear power plants. However, in the U.S. this market virtually collapsed by the end of the 1970s as a result of industrial strains caused by the energy crisis, popular opposition, and finally the Three Mile Island nuclear accident in 1979, all of which led to a de facto moratorium on the development of new nuclear reactor power stations.
In Europe a mixed situation exists. Considerable nuclear power capacities have been developed, notably in Belgium, France, Germany, Spain, Sweden, Switzerland and the UK. In many countries development of nuclear power has been stopped and phased out by legal actions. In Italy the use of nuclear power was barred by a referendum in 1987, however this is now under revision. Ireland also has no plans to change its non-nuclear stance and pursue nuclear power in the future.
Since 1981 uranium prices and quantities in the US are reported by the Department of Energy. The import price dropped from 32.90 US$/lb-U3O8 in 1981 down to 12.55 in 1990 and to below 10 US$/lb-U3O8 in the year 2000. Prices paid for uranium during the 1970s were higher, 43 US$/lb-U3O8 is reported as the selling price for Australian uranium in 1978 by the Nuclear Information Centre
Uranium prices reached an all-time low in 2001, costing US$7/lb, but has since rebounded strongly and in the last few months extremely so. In April 2007 the price of Uranium on the spot market rose to US$113.00/lb. This is very close to the all time high (adjusted for inflation) in 1977. The higher price has spurred expansion of current mines, construction of new mines and reopening of old mines as well as new prospecting.
In January 2008 Areva was nominated for an Anti Oscar Award. The French state-owned company mines uranium in northern Niger where mine workers are not informed about health risks, and analysis shows radioactive contamination of air, water and soil.The local organization that represents the mine workers, spoke of “suspicious deaths among the workers, caused by radioactive dust and contaminated groundwater.”
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