| 摘要 |
Hafnium dioxide contaminated with 0.1 to 1 weight percent uranium dioxide is contacted with an aqueous acid such as nitric acid, hydrochloric acid, sulfuric acid and mixtures thereof to leach the uranium dioxide from the hafnium dioxide, thereby producing a slurry of a uranium-containing leachate containing hafnium dioxide solids. The slurry is filtered to separate the uranium-containing leachate from the hafnium dioxide solids, which are then dried to produce hafnium dioxide containing less than about 0.005 wt % uranium dioxide. The hafnium dioxide may then be released for uncontrolled commercial uses. The separated uranium-containing leachate is neutralized to precipitate uranyl hydroxide, which is then separated from the leachate. The uranyl hydroxide may be processed to produce uranium-containing products or may be disposed of as radioactive wastes having a fraction of the total volume of radioactive wastes which would need to be buried if the hafnium dioxide could not be recovered for commercial uses. In addition, separated leachate from the uranyl hydroxide precipitation step can be recycled or discharged to settling ponds.
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