| 摘要 |
<p>Uranium and zirconium are recovered by solvent extraction of a solution containing uranyl nitrate, prepared by contacting a zirconium-uranium composition with at least a 4M. aqueous solution of ammonium fluoride, at a temperature up to the reflux temperature of the resultant solution, to dissolve zirconium, adding a peroxide in incremental amounts to convert the uranium to a soluble uranyl salt and adding sufficient nitric acid to form the nitrate. Zirconium is thought to dissolve in the ammonium fluoride solution as ammonium zirconium fluoride, and the concomitant evolution of hydrogen may be diminished by adding ammonium nitrate (up to 1 molar); the uranium dissolves to form ammonium uranous fluoride which is converted by the peroxide, e.g. H2O2, to ammonium uranyl fluoride. It is preferred to add aluminium nitrate with the nitric acid to diminish corrosion. Preferably sufficient hydrogen peroxide is added to make the final solution 0,1 molar in H2O2. The molar ratio of free fluoride to uranyl (U+6) provided by the particular ammonium fluoride solvent should be at least 60. The free fluoride concentration is defined as: Total fluoride concentration minus 6 times the zirconium concentration, the concentration being expressed in moles.</p> |
