Uranous sulfate precipitation as a novel hydrometallurgical process for uranium purification

• Uranous sulfate will crystallize from a solution upon the application of heat and the addition of sulfuric acid
• Precipitation is selective in the presence of the impurities Al, Cu, Fe, and Ni
• A complete reduction and precipitation process has been tested successfully on the bench scale.
• Suggestions for the scale-up of the proposed process, and for equipment design, are discussed.

Uranous sulfate is known to crystallize from uranium(IV) sulfate solutions upon the addition of sulfuric acid and the application of heat. This phenomenon, when coupled with a prior reduction process, could be exploited as a new way to selectively separate uranium from impurities in a high-grade leach solution. In the present work, the selectivity of uranous sulfate precipitation in the presence of the impurities Al, Cu, Fe, and Ni is demonstrated. A process employing this concept, including electrolytic reduction, precipitation, washing, drying, and calcining, has been tested on the bench scale from beginning to end, demonstrating that the process is technically viable.