Separation of americium, curium, and rare earths from high-level wastes by oxalate precipitation: experiments with synthetic waste solutions

Technical Report · Tue Jan 01 04:00:00 EST 1980

DOI:https://doi.org/10.2172/5602200· OSTI ID:5602200

Forsberg, C. W.

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., TN (USA)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5602200
• Report Number(s): ORNL/TM-6445
• Country of Publication: United States
• Language: English

Related Subjects

052001* -- Nuclear Fuels-- Waste Processing
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
ACTINIDES
AMERICIUM
CARBOXYLIC ACID SALTS
CARBOXYLIC ACIDS
CURIUM
DIAGRAMS
DICARBOXYLIC ACIDS
ELEMENTS
FISSION PRODUCTS
FLOWSHEETS
HIGH-LEVEL RADIOACTIVE WASTES
ION EXCHANGE
ISOTOPES
MANAGEMENT
METALS
OPIX PROCESS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXALATES
OXALIC ACID
PRECIPITATION
PROCESSING
RADIOACTIVE MATERIALS
RADIOACTIVE WASTE PROCESSING
RADIOACTIVE WASTES
RARE EARTHS
SEPARATION PROCESSES
TRANSPLUTONIUM ELEMENTS
TRANSURANIUM ELEMENTS
WASTE MANAGEMENT
WASTE PROCESSING
WASTES