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Title: Development of processes for the solubilization of uranium from waste leach residue. [Calsinter and fluoride sinter methods]

Technical Report ·
DOI:https://doi.org/10.2172/5262196· OSTI ID:5262196

Two processes, capable of solubilizing enriched uranium from refractory leach residue solids generated at the Y-12 processing facility, have been developed and tested on a laboratory scale. Both processes take advantage of a sinter step, followed by leaching with nitric acid. One process, designated the Calsinter method, uses a source of CaO as a sintering media to react with refractory metal silicates and provide subsequent solubilization of uranium from the sinter matrix by an acid leach. The sintering step in this case requires a temperature of approximately 1200/sup 0/C. The second process employs fluoride in the sinter media to free the uranium from any refractory silicate, thus rendering it soluble in subsequent acid leaching. A sintering temperature of 700 to 900/sup 0/C is used in this process. Both methods are capable of solubilizing 90 to 99% of the uranium remaining in the leach residue which, after current solids leaching treatment at the Y-12 Plant, still contains 1 to 3% enriched uranium. Uranium concentrations in final leached residues (after the sinter/leach techniques) have been reduced to as low as 500 to 1000 ..mu..g U/g. Physical and chemical characterizations of the Y-12 leach residue are discussed. Inconel trays or high-magnesia refractory material have been shown to be potential materials of containment for the Calsinter step. Sinter reaction and leaching parameters are presented and discussed. 9 tables.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
5262196
Report Number(s):
ORNL/TM-8913; ON: DE84009118
Country of Publication:
United States
Language:
English