Editing Yellowcake

{{More citations needed|date=March 2021}}
{{short description|Uranium concentrate powder}}
{{About|the chemical urania|the type of cake|cake|the falsified documents leading to an event popularly referred to as the 'yellowcake scandal'|Niger uranium forgeries}}
{{distinguish|yellow substance}}
{{chembox
| Watchedfields = changed
| verifiedrevid = 455328748
| Name = Yellowcake
| ImageFile = Yellowcake.jpg
| ImageSize = 250px
| OtherNames = urania
|Section1={{Chembox Identifiers
| CASNo = 1344-57-6
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = L70487KUZO
  }}
|Section2={{Chembox Properties
| Formula = variable, see text
| MolarMass =
| Appearance = Yellow granules (as Yellowcake); Brown or black granules (UO<sub>2</sub> and others)
| Solubility =
| MeltingPtC = 2880
| BoilingPt = 
 }}
}}
[[File:Yellowcake (03010301).jpg|thumb|Yellowcake]]
'''Yellowcake''' (also called '''urania''') is a type of [[powder (substance)|powdered]] [[uranium]] concentrate obtained from [[In-situ leach|leach solutions]], in an intermediate step in the processing of [[uranium ores]]. It is a step in the processing of uranium after it has been mined but before fuel fabrication or [[uranium enrichment]]. Yellowcake concentrates are prepared by various extraction and refining methods, depending on the types of ores. Typically, yellowcakes are obtained through the milling and chemical processing of uranium [[ore]], forming a coarse powder that has a pungent odor, is insoluble in water, and contains about 80% [[uranium oxide]], which melts at approximately 2880&nbsp;°C.

==Overview==
Originally, raw uranium ore was extracted by traditional mining, and this is still the case in many mines. It is first crushed to a fine powder by [[mineral processing|passing it through crushers and grinders]] to produce "pulped" ore. This is further processed with concentrated [[acid]], [[alkaline]], or [[peroxide]] solutions to leach out the uranium. However, nearly half of yellowcake production is now produced by [[in situ leach]]ing in which the solution is pumped through the uranium deposit without disturbing the ground.<ref name=Gil/>  Yellowcake is what remains after drying and filtering. The yellowcake produced by most modern mills is actually brown or black, not yellow; the name comes from the color and texture of the concentrates produced by early mining operations.<ref>
{{cite web|title=Yellowcake|url=https://www.nrc.gov/reading-rm/basic-ref/glossary/yellowcake.html|work=U.S. Nuclear Regulatory Commission|access-date=12 April 2014}}
</ref><ref>{{cite web|title=Yellowcake|url=https://www.euronuclear.org/info/encyclopedia/y/yellow-cake.htm|work=European Nuclear Society nuclear glossary|access-date=10 July 2017|archive-date=6 July 2017|archive-url=https://web.archive.org/web/20170706110632/http://euronuclear.org/info/encyclopedia/y/yellow-cake.htm|url-status=dead}}</ref>

[[File:U.S. uranium concentrate (U3O8) production in 1950 through 2021 (52242826664).png|thumb|upright=1.4|US [[triuranium octoxide]] (U<sub>3</sub>O<sub>8</sub>) production, 1950–2021]]
Initially, the compounds formed in yellowcakes were not identified; in 1970, the [[U.S. Bureau of Mines]] still referred to yellowcakes as the final precipitate formed in the milling process and considered it to be [[ammonium diuranate]] or [[sodium diuranate]]. The compositions were variable and depended upon the leachant and subsequent precipitating conditions. The compounds identified in yellowcakes include [[uranyl hydroxide]], [[uranyl sulfate]], [[sodium para-uranate]], and [[uranyl peroxide]], along with various [[uranium oxide]]s.  Modern yellowcake typically contains 70% to 90% [[triuranium octoxide]] (U<sub>3</sub>O<sub>8</sub>) by weight. Other oxides such as [[uranium dioxide]] (UO<sub>2</sub>) and [[uranium trioxide]] (UO<sub>3</sub>) exist.<ref>{{cite journal |year=1998 |title=Characterizing and Classifying Uranium Yellow Cakes: A Background |first=Donald M. |last=Hausen |journal=[[JOM (journal)|JOM]] |volume=50 |issue=12 |pages=45–47 |doi=10.1007/s11837-998-0307-5 |bibcode = 1998JOM....50l..45H |s2cid=97023067 }}</ref>

Yellowcake is produced by all countries in which uranium ore is mined.<ref name=Gil>Gil, Laura (2018), [https://www.iaea.org/sites/default/files/publications/magazines/bulletin/bull59-2/5922223.pdf "Uranium leaching: How yellowcake is made"], IAEA Bulletin (Online), vol. 59, iss, 2, pp. 22-23.</ref>

=== Further processing ===
Yellowcake is used in the preparation of uranium fuel for [[nuclear reactor]]s, for which it is smelted into purified UO<sub>2</sub> for use in [[nuclear fuel#PWR fuel|fuel rods]] for [[Pressurised Heavy Water Reactor|pressurized heavy-water reactors]] and other systems that use natural [[Natural uranium|unenriched uranium]].

Purified uranium can also be [[uranium enrichment|enriched into the isotope U-235]]. In this process, the uranium oxides are combined with [[fluorine]] to form [[uranium hexafluoride]] gas (UF<sub>6</sub>). Next, the gas undergoes [[isotope separation]] through the process of [[gaseous diffusion]], or in a [[gas centrifuge]]. This can produce [[low-enriched uranium]] containing up to 20% U-235 that is suitable for use in most large civilian electric-power reactors. With further processing, one obtains [[highly enriched uranium]], containing 20% or more U-235, that is suitable for use in compact nuclear reactors—usually used to power naval warships and [[submarine]]s. Further processing can yield [[weapons-grade]] uranium with U-235 levels usually above 90%, suitable for [[nuclear weapon]]s.

== Radioactivity and safety ==
[[File:Yellowcake-exhibit-peterborough.jpg|thumb|200px|Yellowcake and ore]]
The uranium in yellowcake is almost exclusively (>99%) [[Uranium-238 | U-238]], with very low radioactivity. U-238 has a [[half-life]] of 4.468 billion years and emits radiation at a slow rate. This stage of processing is before the more radioactive U-235 is concentrated, so by definition, this stage of uranium has the same radioactivity as it did in nature when it was underground, as the proportions of isotopes are at their native relative concentration. Yellowcake is hazardous when inhaled.<ref>{{cite book |last1=Keith |first1=Sam |last2=Faroon |first2=Obaid |last3=Roney |first3=Nickolette |last4=Scinicariello |first4=Franco |last5=Wilbur |first5=Sharon |last6=Ingerman |first6=Lisa |last7=Llados |first7=Fernando |last8=Plewak |first8=Daneil |last9=Wohlers |first9=David |last10=Diamond |first10=Gary |title=Health Effects|url=https://www.ncbi.nlm.nih.gov/books/NBK158798/ |publisher=Agency for Toxic Substances and Disease Registry (US) |access-date=22 August 2021 |language=en |date=February 2013}}</ref>

==See also==
*[[Uranium ore deposits]]
*[[Uranium mining]]
*[[Uraninite]], an ore that is mostly [[uranium dioxide]] (UO<sub>2</sub>)
*[[Niger uranium forgeries|Yellowcake forgery]], fraudulently depicted Saddam Hussein trying to buy uranium powder
*[[Sequoyah Fuels Corporation]], an American company involved in yellowcake processing
*[[COMINAK]], a [[Niger]] uranium mining and processing company
*[[SOMAIR]], a Niger uranium mining and processing company
*[[Vanadium(V) oxide]], hydrous precipitates of which are known as "redcake"

==References==

{{reflist}}

{{Uranium compounds}}

[[Category:Uranium compounds]]
[[Category:Oxides]]
[[Category:Nuclear materials]]