Separation of americium, curium, and rare earths from high-level wastes by oxalate precipitation: experiments with synthetic waste solutions
The separation of trivalent actinides and rare earths from other fission products in high-level nuclear wastes by oxalate precipitation followed by ion exchange (OPIX) was experimentally investigated using synthetic wastes and a small-scale, continuous-flow oxalic acid precipitation and solid-liquid separation system. Trivalent actinide and rare earth oxalates are relatively insoluble in 0.5 to 1.0 M HNO/sub 3/ whereas other fission product oxalates are not. The continuous-flow system consisted of one or two stirred-tank reactors in series for crystal growth. Oxalic acid and waste solutions were mixed in the first tank, with the product solid-liquid slurry leaving the second tank. Solid-liquid separation was tested by filters and by a gravity settler. The experiments determined the fraction of rare earths precipitated and separated from synthetic waste streams as a function of number of reactors, system temperature, oxalic acid concentration, liquid residence time in the process, power input to the stirred-tank reactors, and method of solid-liquid separation. The crystalline precipitate was characterized with respect to form, size, and chemical composition. These experiments are only the first step in converting a proposed chemical flowsheet into a process flowsheet suitable for large-scale remote operations at high activity levels.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 5602200
- Report Number(s):
- ORNL/TM-6445; TRN: 80-004949
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMERICIUM
ION EXCHANGE
PRECIPITATION
CURIUM
OPIX PROCESS
RADIOACTIVE WASTE PROCESSING
HIGH-LEVEL RADIOACTIVE WASTES
RARE EARTHS
FISSION PRODUCTS
FLOWSHEETS
OXALATES
OXALIC ACID
ACTINIDES
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
DIAGRAMS
DICARBOXYLIC ACIDS
ELEMENTS
ISOTOPES
MANAGEMENT
METALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTES
SEPARATION PROCESSES
TRANSPLUTONIUM ELEMENTS
TRANSURANIUM ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES
052001* - Nuclear Fuels- Waste Processing