Editing Yellowcake (section)

==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.