Uranium ore
Uranium ore deposits are economically recoverable concentrations of
Globally, the distribution of uranium ore deposits is widespread on all continents, with the largest deposits found in Australia, Kazakhstan, and Canada. To date, high-grade deposits are only found in the Athabasca Basin region of Canada.
Uranium deposits are generally classified based on host rocks, structural setting, and mineralogy of the deposit. The most widely used classification scheme was developed by the International Atomic Energy Agency (IAEA) and subdivides deposits into 15 categories.
Uranium
Uranium is a silvery-gray
Uranium has the highest atomic weight of the naturally occurring elements and is approximately 70%
Uranium minerals
The primary uranium ore mineral is
A large variety of secondary uranium minerals are known, many of which are brilliantly coloured and fluorescent. The most common are gummite (a mixture of minerals),[7] autunite (with calcium), saleeite (magnesium) and torbernite (with copper); and hydrated uranium silicates such as coffinite, uranophane (with calcium) and sklodowskite (magnesium).
Uranium Minerals[8][9] | |
---|---|
Primary uranium minerals | |
Name | Chemical Formula |
uraninite or pitchblende | UO2 |
coffinite | U(SiO4)1–x(OH)4x |
brannerite | UTi2O6 |
davidite | (REE)(Y,U)(Ti,Fe3+)20O38 |
thucholite | Uranium-bearing pyrobitumen |
Secondary uranium minerals | |
Name | Chemical Formula |
autunite | Ca(UO2)2(PO4)2 x 8–12 H2O |
carnotite | K2(UO2)2(VO4)2 x 1–3 H2O |
gummite | gum like mixture of various uranium minerals |
saleeite | Mg(UO2)2(PO4)2 x 10 H2O |
torbernite | Cu(UO2)2(PO4)2 x 12 H2O |
tyuyamunite | Ca(UO2)2(VO4)2 x 5–8 H2O |
uranocircite | Ba(UO2)2(PO4)2 x 8–10 H2O |
uranophane | Ca(UO2)2(HSiO4)2 x 5 H2O |
zeunerite | Cu(UO2)2(AsO4)2 x 8–10 H2O |
Ore genesis
There are several themes of uranium ore deposit formation, which are caused by geological and chemical features of rocks and the element uranium. The basic themes of uranium ore genesis are host mineralogy, reduction-oxidation potential, and porosity.
Uranium is a highly soluble, as well as a radioactive, heavy metal. It can be easily dissolved, transported and precipitated within
Uranium is an incompatible element within
Classification schemes
IAEA Classification (1996)
The International Atomic Energy Agency (IAEA) assigns uranium deposits to 15 main categories of deposit types, according to their geological setting and genesis of mineralization, arranged according to their approximate economic significance.
- Unconformity-related deposits
- Sandstone deposits
- Quartz-pebble conglomerate deposits
- Breccia complex deposits
- Vein deposits
- Intrusive deposits (Alaskites)
- Phosphorite deposits
- Collapse breccia pipe deposits
- Volcanic deposits
- Surficial deposits
- Metasomatite deposits
- Metamorphic deposits
- Lignite
- Black shale deposits
- Other types of deposits
Alternate scheme
The IAEA classification scheme works well, but is far from ideal, as it does not consider that similar processes may form many deposit types, yet in a different geological setting. The following table groups the above deposit types based on their environment of deposition.
Uranium Deposit Classification[10] | |
---|---|
Uranium Transport / Precipitation Conditions |
Deposit Type |
Surface Processes / synsedimentary | Surficial deposits |
Quartz-pebble conglomerate deposits | |
Phosphorite deposits | |
Lignite | |
Black shales | |
Diagenetic
|
Sandstone deposits |
Diagenetic – Hydrothermal? | Unconformity-related deposits |
Vein deposits | |
Collapse breccia pipe deposits | |
Magmatic – Hydrothermal? | Breccia complex deposits |
Volcanic deposits | |
Metasomatite deposits | |
Vein deposits | |
Intrusive deposits | |
Metamorphic – Hydrothermal? | Metamorphic deposits |
Deposit types (IAEA Classification)
Unconformity-type uranium deposits host high grades relative to other uranium deposits and include some of the largest and richest deposits known. They occur in close proximity to
Phanerozoic unconformity-related deposits occur in Proterozoic metasediments below an unconformity at the base of overlying Phanerozoic sandstone. These deposits are small and low-grade (
The two most significant areas for this style of deposit are currently the Athabasca Basin in Saskatchewan, Canada, and the McArthur Basin in the Northern Territory, Australia.
Athabasca Basin
The highest grade uranium deposits are found in the
McArthur Basin
The deposits of the McArthur River basin in the East Alligator Rivers region of the Northern Territory of Australia (including Jabiluka, Ranger, and Nabarlek) are below the unconformity and are at the low-grade end of the unconformity deposit range but are still high grade compared to most uranium deposit types. There has been very little exploration in Australia to locate deeply concealed deposits lying above the unconformity similar to those in Canada. It is possible that very high grade deposits occur in the sandstones above the unconformity in the Alligator Rivers/Arnhem Land area.[13]
Sandstone deposits
Sandstone deposits are contained within medium to coarse-grained sandstones deposited in a continental fluvial or marginal marine sedimentary environment. Impermeable shale or mudstone units are interbedded in the sedimentary sequence and often occur immediately above and below the mineralised horizon.[13] Uranium is mobile under oxidising conditions and precipitates under reducing conditions, and thus the presence of a reducing environment is essential for the formation of uranium deposits in sandstone.[11]
Primary mineralization consists of pitchblende and coffinite, with weathering producing secondary mineralization. Sandstone deposits constitute about 18% of world uranium resources. Orebodies of this type are commonly low to medium grade (0.05–0.4% U3O8) and individual orebodies are small to medium in size (ranging up to a maximum of 50,000 t U3O8).[13]
Sandstone hosted uranium deposits are widespread globally and span a broad range of host rock ages. Some of the major provinces and production centers include:
- the Wyoming basins
- the Grants District of New Mexico
- deposits in Central Europe and
- Kazakhstan
Significant potential remains in most of these centers as well as in Australia, Mongolia, South America, and Africa.
This model type can be further subdivided into the following sub-types:
- tabular
- roll front
- basal channel
- structurally related
Many deposits represent combinations of these types.
Tabular
Tabular deposits consist of irregular tabular or elongate
Tabular sandstone uranium deposits contains many of the highest grades of the sandstone class, however the average deposit size is very small.
Roll front
Roll-front uranium deposits are generally hosted within
The Rollfront subtype deposits typically represent the largest of the sandstone-hosted uranium deposits and one of the largest uranium deposit types with an average of 21 million lb (9,500 t) U3O8. Included in this class are the
Typical characteristics:
- roll-front deposits are crescent-shaped bodies that transect the host lithology
- typically the convex side points down the hydraulic gradient.
- the limbs or tails tend to be peneconcordant with the lithology.
- most ore-bodies consist of several interconnected rolls.
- individual roll-front deposits are quite small but collectively can extend for considerable distances.
Basal channel (palaeochannel)
Basal channel deposits are often grouped with tabular or rollfront deposits, depending on their unique characteristics. The model for formation of
Some particularly rich uranium deposits are formed in palaeochannels which are filled in the lower parts by lignite or brown coal, which acts as a particularly efficient reductive trap for uranium. Sometimes, elements such as scandium, gold and silver may be concentrated within these lignite-hosted uranium deposits.[14]
The Frome Embayment in South Australia hosts several deposits of this type including Honeymoon, Oban, Beverley and [Four-Mile][15] (which is the largest deposit of this class).[16][17][18] These deposits are hosted in palaeochannels filled with Cainozoic sediments and sourced their uranium from uranium-rich Palaeo- to Mesoproterozoic rocks of the Mount Painter Inlier and the Olary Domain of the Curnamona Province.
Tectonic-lithologic controlled uranium deposits occur in sandstones adjacent to a permeable fault zone[13] which cuts the sandstone/mudstone sequence. Mineralisation forms tongue-shaped ore zones along the permeable sandstone layers adjacent to the fault. Often there are a number of mineralised zones 'stacked' vertically on top of each other within sandstone units adjacent to the fault zone.[11]
Quartz-pebble conglomerate deposits
Quartz pebble conglomerate hosted uranium deposits are of historical significance as the major source of primary production for several decades after
Two main sub-types have been identified:
Quartz pebble conglomerate hosted uranium deposits formed from the transport and deposition of uraninite in a fluvial sedimentary environment
Uranium minerals were derived from uraniferous pegmatites in the sediment source areas. These deposits are restricted to the
Quartz pebble conglomerate uranium deposits are typically low grade but characterized by high tonnages. The Huronian deposits in Canada generally contain higher grades (0.15% U3O8)[10] and greater resources (as shown by the Denison and Quirke mines), however some of the South African gold deposits also contain sizeable low grade (0.01% U3O8)[10] uranium resources.
Witwatersrand sub-type
In the
Uranium minerals in the Witwatersrand deposits are typically uraninite with lesser uranothorite, brannerite, and coffinite. The uranium is especially concentrated along thin carbonaceous seams or carbon leaders. Strong regional scale alteration consists of pyrophyllite, chloritoid, muscovite, chlorite, quartz, rutile, and pyrite. The main elements associated with the uranium are gold and silver. Gold contents are much higher than in the Elliot Lake type with U:Au ranging between 5:1 and 500:1, which indicates that these gold-rich ores are essentially very low grade uranium deposits with gold.
Elliot Lake sub-type
Sedimentological controls on the Huronian deposits of the Elliot Lake district appear to be much stronger than in the Witwatersrand deposits. Ores grade from uranium through thorium to titanium-rich with decreasing pebble size and increasing distance from their source. While evidence of post-diagenetic remobilization has been identified, these effects appear far subordinate to the sedimentological controls.
Ore consists of
This schematic model represents the original depositional setting. The
Breccia complex deposits (IOCG-U)
Only one
Uranium occurs with copper, gold, silver, and
Another example for the Breccia type is the Mount Gee area in the Mount Painter Inlier, South Australia. Uranium mineralised quartz-hematite breccia is related to Palaeoproterozoic granites with uranium contents of up to 100 ppm. Hydrothermal processes at about 300 million years ago remobilised uranium from these granites and enriched them in the quartz-hematite breccias. The breccias in the area host a low grade resource of about 31,400 t U3O8 at 615 ppm in average.[20]
Vein deposits
Vein deposits play a special role in the history of uranium: the term "pitchblende" ("Pechblende") originates from German vein deposits when they were mined for silver in the 16th century. F.E. Brückmann made the first mineralogical description of the mineral in 1727 and the vein deposit Jachymov in the Czech Republic became the type locality for uraninite.[21] In 1789 the German chemist M. H. Klaproth discovered the element of uranium in a sample of pitchblende from the Johanngeorgenstadt vein deposit. The first industrial production of uranium was made from the Jachymov deposit and Marie and Pierre Curie used the tailings of the mine for their discovery of polonium and radium.
Vein deposits consist of uranium minerals filling in cavities such as cracks, veins, fractures, breccias, and stockworks associated with steeply dipping fault systems. There are three major subtypes of vein style uranium mineralisation:
- intragranitic veins (Central Massif, France)
- veins in metasedimentary rocks in exocontacts of granites
- quartz-carbonate uranium veins (Erzgebirge Mts, Germany/Czech Republic; Bohemian Massif, Czech Republic)
- uranium-polymetal veins (Erzgebirge Mts, Germany/Czech Republic; Saskatchewan, Canada)
- mineralised fault and shear zones (central Africa; Bohemian Massif, Czech Republic)
Intragranitic veins form in the late phase of magmatic activity when hot fluids derived from the magma precipitate uranium on cracks within the newly formed granite. Such mineralisation contributed much to the uranium production of France. Veins hosted by metasedimentary units in the exocontact of granites are the most important sources of uranium mineralisation in central Europe including the world class deposits
The
Intrusive associated deposits
Intrusive deposits make up a large proportion of the world's uranium resources. Included in this type are those associated with intrusive rocks including
Phosphorite deposits
Marine sedimentary phosphorite deposits can contain low grade concentrations of uranium, up to 0.01–0.015% U3O8, within fluorite or apatite.[10] These deposits can have a significant tonnage. Very large phosphorite deposits occur in Florida and Idaho in the United States, Morocco, and some middle eastern countries.[11][13]
Collapse breccia pipe deposits
Collapse
Primary ore minerals are
The best known examples of this deposit type are in the Arizona breccia pipe uranium mineralization in the US, where several of these deposits have been mined.
Volcanic deposits
Volcanic deposits occur in
Mineralization occurs either as structurally controlled veins and breccias discordant to the stratigraphy and less commonly as stratabound mineralization either in extrusive rocks or permeable
Volcanic hosted uranium deposits occur in host rocks spanning the Precambrian to the Cenozoic but because of the shallow levels at which they form, preservation favors younger age deposits. Some of the more important deposits or districts are
The average deposit size is rather small with grades of 0.02% to 0.2% U3O8.[11] These deposits make up only a small proportion of the world's uranium resources.[13] The only volcanic hosted deposits currently being exploited are those of the Streltsovkoye district of eastern Siberia. This is in fact not a single stand-alone deposit, but 18 individual deposits occurring within the Streltsovsk caldera complex. Nevertheless, the average size of these deposits is far greater than the average volcanic type.
Surficial deposits (calcretes)
Surficial deposits are broadly defined as
Surficial deposits account for approximately 4% of world uranium resources.[13] The Yeelirrie deposit is by far the world's largest surficial deposit, averaging 0.15% U3O8. Langer Heinrich[26] in Namibia is another significant surficial deposit.[11]
Metasomatite deposits
Metasomatite deposits consist of disseminated uranium minerals within structurally deformed rocks that have been affected by intense sodium metasomatism.[10][11] Ore minerals are uraninite and brannerite. Th/U ratio in the ores is mostly less than 0.1. Metasomatites are typically small in size and generally contain less than 1000 t U3O8.[11] Giant (up to 100 thousands t U) U deposits in sodium metasomatites (albitites) are known in Central Ukraine and Brazil.[citation needed]
Two subtypes are defined based on host lithologies:
- metasomatized granite; ex. Ross Adams deposit in Alaska, United States, Novokostantynivka deposit in Kirovogradska oblast, Ukraine.
- metasomatised metasediment; , Australia.
Metamorphic deposits
Metamorphic deposits those that occur in metasediments or metavolcanic rocks where there is no direct evidence for mineralization post-dating metamorphism.[10][11] These deposits were formed during regional metamorphism of uranium bearing or mineralized sediments or volcanic precursors.
The most prominent deposits of this type are Mary Kathleen, Queensland, Australia, and Forstau, Austria.
Lignite
Lignite deposits (soft brown coal) can contain significant uranium mineralization. Mineralization can also be found in clay and sandstone immediately adjacent to lignite deposits. Uranium has been adsorbed onto carbonaceous matter and as a result no discrete uranium minerals have formed. Deposits of this type are known from the Serres Basin, in Greece, and in North and South Dakota in the USA. The uranium content in these deposits is very low, on average less than 0.005% U3O8, and does not currently warrant commercial extraction.[10][11]
Black shale deposits
Black shale mineralisations are large low-grade resources of uranium. They form in submarine environments under oxygen-free conditions. Organic matter in clay-rich sediments will not be converted to CO2 by biological processes in this environment and it can reduce and immobilise uranium dissolved in seawater. Average uranium grades of black shales are 50 to 250 ppm. The largest explored resource is Ranstad in Sweden containing 254,000 t of uranium. However, there are estimates for black shales in the US and Brazil assuming a uranium content of over 1 million tonnes, but at grades below 100 ppm uranium. The Chattanooga Shale in the southeastern USA for example is estimated to contain 4 to 5 million tonnes at an average grade of 54 ppm.[25]
Because of their low grades, no black shale deposit ever produced significant amounts of uranium with one exception: the
Other types of deposits
- There are also uranium deposits, of other types, in the Jurassic Todilto Limestone in the Grants District, New Mexico, USA.[11]
- The
- In some countries, for example China, trials are underway to extract uranium from fly ash.[27]
See also
- List of countries by uranium reserves
- List of uranium mines
- Nuclear fuel cycle
- Ore genesis
- Uranium mining
References
- ^ "Cameco – Uranium 101". Retrieved February 1, 2009.
- ^ "Cameco – Uranium 101, Where is uranium found?". Retrieved 2009-01-28.
- ISBN 0-939950-50-2)
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: CS1 maint: multiple names: authors list (link - ^ "Uranium". Los Alamos National Laboratory. Retrieved 2009-02-11.
- ^ "WorldBook@NASA: Supernova". NASA. Archived from the original on 2006-09-30. Retrieved 2009-02-11.
- ISBN 0-471-80580-7
- ^ "Gummite".
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- ^ "Mineralogy Database". Retrieved March 25, 2009.
- ^ ISBN 0-7245-7107-8
- ^ ISBN 0-642-46716-1, archived from the original(PDF) on October 2, 2012, retrieved February 12, 2009
- ^ RPA Fission U Patterson Lake South Technical Report
- ^ a b c d e f g h i j k l m "Geology of Uranium Deposits". world-nuclear.org. Retrieved 15 April 2023 – via World Nuclear Association.
- ^ Douglas, G., Butt, C., and Gray, D. (2003). "Mulga Rock Uranium and Multielement Deposits, Officer Basin, WA" (PDF). Retrieved February 13, 2009.
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: CS1 maint: multiple names: authors list (link) - ^ "Alliance Resources Limited – Uranium and gold producer – Projects : Four Mile Uranium Project, SA". www.allianceresources.com.au. Archived from the original on 13 March 2017. Retrieved 18 April 2018.
- ^ "AGM Presentation by MD Mr Patrick Mutz". allianceresources.com.au. Retrieved 18 April 2018.
- ^ "Australia' s Uranium Deposits and Prospective Mines". www.world-nuclear.org. Archived from the original on 2011-06-04.
- ^ "Geoscience Australia: Australia's uranium resources, geology and development of deposits". Archived from the original on 2009-12-25. Retrieved 2010-01-26.
- ISBN 0-919216-34-X.
- ^ "Marathon Resources Ltd – Paralana Mineral System (Mt Gee)". Archived from the original on 2009-04-10. Retrieved 2009-04-22.
- ^
Veselovsky, F., Ondrus, P., Gabsová, A., Hlousek, J., Vlasimsky, P., Chernyshew, I.V. (2003). "Who was who in Jáchymov mineralogy II". Journal of the Czech Geological Society. 48 (3–4 ed.): 93–205.)
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: CS1 maint: multiple names: authors list (link - ^ Ruzicka, V. (1993). "Vein uranium deposits". Ore Geology Reviews. 8 (3–4): 247–276. .
- ^ a b c various... (1999), Chronik der Wismut, Chemnitz: Wismut GmbH
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- ^ "Langer Heinrich Uranium Mine – Mining Technology | Mining News and Views Updated Daily". Mining Technology.
- ^ Winning, David (22 February 2010). "Out of the Ashes". Wall Street Journal.
Additional sources
- Dahlkamp, Franz (1993). Uranium Ore Deposits. Berlin, Germany: Springer-Verlag. ISBN 3-540-53264-1.
- Burns, P.C.; Finch, R., eds. (1999), Reviews in Mineralogy, vol. 38: Uranium: Mineralogy, Geochemistry and the Environment., Washington D.C., U.S.A.: Mineralogical Society of America, ISBN 0-939950-50-2
- "Geoscience Australia Uranium factsheet" (PDF). Archived from the original (PDF) on 2007-09-11. Retrieved 2007-08-14.
- "Uranium Ore Deposits". WISE Uranium Project. Retrieved 2008-09-20.