Extraction of uranium: comparison of stripping with ammonia vs. strong acid
- Cameco Corporation (Canada)
- Bateman Solvent Extraction (Israel)
Following extraction of uranium in the first stage of solvent extraction using a tertiary amine, typically Alamine 336, the stripping of the extracted uranium is accomplished either by use of an aqueous solution of (NH{sub 4}){sub 2}SO{sub 4} /NH{sub 4}OH or by strong-acid stripping using 400-500 g/L H{sub 2}SO{sub 4}. Both processes have their merits and determine the downstream processing. The classical stripping with ammonia is followed by addition of strong base, to precipitate ammonium uranyl sulfate (NH{sub 4}){sub 2}UO{sub 2}(SO{sub 4}){sub 2}, which yields finally the yellow cake. Conversely, stripping with H{sub 2}SO{sub 4}, followed by oxidation with hydrogen peroxide yields uranyl oxide as product. At the Cameco Key Lake operation, both processes were tested on a pilot scale, using a Bateman Pulsed Column (BPC). The BPC proved to be applicable to both processes. It met the process criteria both for extraction and stripping, leaving less than 1 mg/L of U{sub 3}O{sub 8} in the raffinate, and product solution had the required concentration of U{sub 3}O{sub 8} at high flux and reasonable height of transfer unit. In the Key Lake mill, each operation can be carried out in a single column. The main advantages of the strong-acid stripping over ammonia stripping are: (1) 60% higher flux in the extraction, (2) tenfold higher concentration of the uranium in the product solution, and (3) far more robust process, with no need of pH control in the stripping and no need to add acid to the extraction in order to keep the pH above the point of precipitation of iron compounds. The advantages of the ammoniacal process are easier stripping, that is, less stages needed to reach equilibrium and lower concentration of modifier needed to prevent the creation of a third phase. (authors)
- Research Organization:
- Chemical Sciences Division, Oak Ridge National Laboratory (United States)
- OSTI ID:
- 21230349
- Resource Relation:
- Conference: ISEC 2008: International Solvent Extraction Conference on Solvent Extraction: Fundamentals to Industrial Applications, Tucson, AZ (United States), 15-19 Sep 2008; Other Information: Country of input: France; 3 refs; Related Information: In: Proceedings of ISEC 2008, International Solvent Extraction Conference - Solvent Extraction: Fundamentals to Industrial Applications, by Moyer, Bruce A. (ed.), 1740 pages.
- Country of Publication:
- United States
- Language:
- English
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