| 摘要 |
<p>1496952 Purifiying fluoride-containing effluents ASEA-ATOM AB 18 March 1975 [19 March 1974 4 July 1974 (2) 18 Dec 1974] 11151/75 Headings C1A and C1C Dissolved fluorides (e.g. NH 4 F) are removed from the effluent of a plant manufacturing uranium fuel from uranium hexafluoride, by contacting the effluent with alkaline earth metal carbonate particles at least 75% of which have a grain size exceeding 0À08 mm., the particles thereby being transformed into alkaline earth metal fluoride particles of the same size. Preferably CaCO 3 (limestone), MgCO 3 , BaCO 3 or SrCO 3 of grain size 0À1-2À0 mm. is used. The effluent may be passed through one or more beds of the carbonate at 60-120‹ C. and a pressure in the range 1-10 atmospheres sufficient to inhibit liberation of CO 2 . Alternatively the carbonate may be added to the effluent at elevated (e.g. boiling) temperature, and the fluoride formed then filtered off. The effluent may be pre-treated with a peroxide to precipitate uranium compounds, and, after the carbonate treatment, may be distilled to precipitate uranium compounds and obtain from the vapours aqueous ammonium carbonate which may be acidified to give ammonium nitrate or sulphate. Plants for carrying out these processes are illustrated. Substances recoverable from the above process are thus (i) alkaline earth metal fluorides; (ii) unspecified water-insoluble uranium compounds; (iii) ammonium nitrate or sulphate.</p> |
