Talk:Yellowcake
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Why is it called Yellowcake? Is it yellow? Edward 12:46, 7 Nov 2004 (UTC)
- It used to be, hence the name, but isn't any more due to changes in the manufacturing process. I've updated the article to reflect this. -- ChrisO 17:09, 7 Nov 2004 (UTC)
But... why the part about cake? Sure it may look like a cake or something, but you don't called radioactive materials "cake"! >_< Jobjörn 23:59, 17 August 2005 (UTC)
- Well, actually, we do. It's a bit like calling something Green Field when the site is neither green nor a field. Wikipedia doesn't decide this sort of usage, we just report it. Andrewa 17:56, 29 December 2005 (UTC)
- PS Banana cake is also radioactive, largely owing to the natural Potassium-40 in the bananas. So is every other food, but many of them less so. Banana cake may also be yellow, but is more often brown, like yellowcake. Enjoy! Andrewa 18:05, 29 December 2005 (UTC)
[edit] Yellowcake is NOT U3O8
Yellowcake is not U3O8. U3O8 is formed by high-firing of the UO2 or UO3 forms, typically in excess of 800 oC for an hour or more. It is a black, particulate powder, similar in consistency of sand, though the particles are more rounded. The term Yellowcake actually refers to the product produced when uranium is precipated using ammonium hydroxide to purify the ore prior to conversion to the oxides. Most often, the chemical formula for yellowcake is described as ammonium diuranate. It is a yellow powder, with consistency of flour. It can be confused with UO2, which is also yellow, and dried uranyl nitrate. It turns out that yellowcake is much more complicated than simply a pure ammonium diuranate molecule, and consists of a mixture of several ammonium-uranium-oxygen compounds. Because of the complex mixture, the uranium content of yellowcake can vary widely, though typically in the range of 40-60%. Pure U3O8 has a consistent uranium content of around 85%, with some minor variability. I can provide references, though they are copyrighted and perhaps can not be posted on this web site.
- Hmm... there are a lot of websites, including some government ones, which explicitly say that yellowcake *is* U3O8 (try Googling for "yellowcake U308"). Having said that, I see that Britannica says the following: "Uranium is usually precipitated as ammonium diuranate, (NH4)2U2O7. From alkaline solutions, uranium is most often precipitated by addition of sodium hydroxide, producing an insoluble sodium diuranate, Na2U2O7. It can also be precipitated by acidification (to remove carbon dioxide) and then neutralization (to remove the uranium) or by reduction to less soluble tetravalent uranium. In all cases, the final uranium precipitate, commonly referred to as yellow cake, is dried. In some cases—e.g., with ammonium diuranate—the yellow cake is ignited, driving off the ammonia and oxidizing the uranium to produce uranium trioxide (UO3) or the more complex triuranium octoxide (U3O8)." So who's right here? Britannica does sounds more authoritative... -- ChrisO 21:03, 19 January 2006 (UTC)
- I suspect that the definition of yellowcake has been more as an mid-point in the refining process than a strict chemical one. Perhaps we need to split the topic, and make a Triuranium octoxide page. --DV8 2XL 21:27, 19 January 2006 (UTC)
I'm the fellow who wrote "U3O8" is NOT yellowcake - just registered and have a user name now. Britannica is correct. Sadly, as I know all too well, many DOE folks incorrectly use the term yellowcake to refer to U3O8, UO3, UO2 and the ammonium diuranate, though U3O8 is the front runner for mis-usage. This is odd as U308 is black, while U03 is a bright yellow and can easily be mistaken for yellowcake (I suspect that is what you have a photo of - upon exposure to moisture in the air the U03 color changes slowly to a more orange). Here's a solid technical literature reference: " 'Yellow cake', a bright yellow material, was formerly thought to be ammonium diuranate, and indeed analytical results show this to be the approximate composition. However, it was shown that 'yellow cake' is a mixture of the following compounds: ..." then there's a whole bunch of uranium compounds of varying stoichiometries. This can be found in The Chemistry of the Actinide Elements, 2nd Ed, Katz, Seaborg and Morss; page 276 (that's Glenn Seaborg, nobel prize winner and "discoverer" of plutonium). Anyway, the fact is the term 'yellow cake' technically refers to the product of the precipitation of uranium from processed ores. Yellow cake, referred to as the 'final ore refining concentrate' in the text, is of sufficient purity to be used to create U02, U03 and/or U3O8 for use in the fuel cycle or for conversion (via several steps) to UF6 for enrichment, conversion back to an oxide or metal for use in reactors or weapons. For all practical purposes, the composition ammonium diuranate ((NH4)2U2O7 is reasonably accurate. Even U3O8 is an approximation - the stoichiometry (ratio of oxygen to uranium of 8:3) varies significantly depending on how it is fired in the furnace. I can provide photos of each of the oxide forms and yellowcake if you're interested. These materials are offered for sale by the laboratory I work for - which is the U.S. government's certifying authority for uranium and plutonium reference materials. Photo's will show the material in bottles with our label attached. OK - enough said!
References - Wasn't 'yellowcake' referred to in the Dave Chappelle skit, Black President? Zena Dhark…·°º•ø®@» 08:29, 11 September 2006 (UTC)
- Stop trying to POV push, OK? --Haizum μολὼν λαβέ 22:00, 20 December 2006 (UTC)
[edit] Can dropping it be dangerous?
If so, a warning should be placed in article. --NEMT 07:17, 3 July 2007 (UTC)
- Why would it be? --OuroborosCobra (talk) 04:56, 10 May 2008 (UTC)
[edit] Radioactivity
What is the level of danger to direct exposure to yellowcake? One of the books in the Life Nature Library series, titled The Earth, shows a picture of a worker using a garden rake to move yellowcake for processing, as if raking garden soil. Group29 (talk) 17:25, 9 May 2008 (UTC)
