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Ammonium uranyl carbonate

Ammonium uranyl carbonate
IUPAC name uranium(VI)dioxide di-ammonium carbonate
Other names uranyl ammonium carbonate
Molecular formula UO2CO3·2(NH4)2CO3
Molar mass 522.199 g/mol
Melting point

Decomposes between 165°C and 185°C

Solubility in water Insoluble
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Ammonium uranyl carbonate(UO2CO3·2(NH4)2CO3) is known in the uranium processing industry as AUC and is also called uranyl ammonium carbonate. This compound is important as a component in the conversion process of uranium hexafluoride (UF6) to uranium dioxide (UO2). The ammonium uranyl carbonate is combined with steam and hydrogen at 500-600°C to yield UO2. In another process aqueous uranyl nitrate, known as uranyl nitrate liquor (UNL) is treated with ammonium bicarbonate to form ammonium uranyl carbonate as a solid precipitate. This is separated from the solution, dried with methanol and then calcinated with hydrogen directly to UO2 to obtain a sinterable grade powdwer. The ex-AUC uranium dioxide powder is free-flowing, relatively coarse (10 µ) and porous with specific surface area in the range of 5m2/g and suitable for direct pelletisation, avoiding the granulation step. Conversion to UO2 is often performed as the first stage of nuclear fuel fabrication.

The AUC process is followed in South Korea and Argentina. In the AUC route, calcination, reduction and stabilization are simultaneously carried out in a vertical fluidized bed reactor. In most countries, sinterable grade UO2 powder for nuclear fuel is obtained by the ammonium diuranate (ADU) process, which requires several more steps.

Ammonium uranyl carbonate is also one of the many forms called yellowcake in this case it is the product obtainded by the heap leach process.


    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ammonium_uranyl_carbonate". A list of authors is available in Wikipedia.
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