| 摘要 |
<p>Uranium is recovered from uranium-aluminium alloy fuels by dissolving in HNO3 at boiling point in the presence of mercuric ions, e.g. Hg(NO3)2, cooling the solution to ambient temperature, removing SlO2 if necessary, and extracting in countercurrent with a solution of an amine base diluted in a hydrocarbon. The amine may be aliphatic primary (molecular weight >200), secondary (M.W. >250) or tertiary (M.W. >300), or may be secondary or tertiary aromatic-aliphatic (M.W. >250). Examples are tri-n-octylamine and tri-n-dodecylamine. The hydrocarbon may be aliphatic or aromatic, or a mixture, e.g. solvent naphthas, and may contain 1-5% of a long-chain aliphatic alcohol. After washing with an aqueous solution of Al2(NO3)3 and HNO3, uranium ma be re-extracted in a countercurrent of 0.1 M.HNO3. The cycle may be repeated, after addition of Al2(NO3)3, and the product aqueous solution is concentrated and filtered on silica gel. Plutonium remains in the starting solution if a reducing agent, e.g. 10-2 M. ferrous sulphamate, is added, or it may be extracted in the IV-valent state by adding sodium nitrite (to give at least 10-2 M. nitrous acid), and then isolated in the second cycle by addition of reducing agent.</p> |
