Characterization of molybdenum interfacial crud in a uranium mill that employs tertiary-amine solvent extraction

Conference · Sat Jan 01 00:00:00 EST 1983

OSTI ID:6468981

Moyer, B; McDowell, W J

In the present work, samples of a molybdenum-caused green gummy interfacial crud from an operating western US uranium mill have been physically and chemically examined. Formaton of cruds of this description has been a long-standing problem in the use of tertiary amine solvent extraction for the recovery of uranium from low-grade ores (Amex Process). The crud is essentially an organic-continuous dispersion containing about 10 wt % aqueous droplets and about 37 wt % greenish-yellow crystalline solids suspended in kerosene-amine process solvent. The greenish-yellow crystals were found to be a previously unknown double salt of tertiary amine molybdophosphate with three tertiary amine chlorides having the empirical formula (R/sub 3/NH)/sub 3/(PMo/sub 12/O/sub 40/).3(R/sub 3/NH)Cl. To confirm the identification of the compound, a pure trioctylamine (TOA) analog was synthesized. In laboratory extraction experiments, it was demonstrated that organic-soluble amine molydophosphate forms slowly upon contact of TOA solvent with dilute sulfuric acid solutions containing low concentrations of molybdate and phosphate. If the organic solutions of amine molybdophosphate were then contacted with aqueous NaCl solutions, a greenish-yellow precipitate of (TOAH)/sub 3/(PMo/sub 12/O/sub 40/).3(TOAH)Cl formed at the interface. The proposed mechanism for the formation of the crud under process conditions involves build up of molybdenum in the solvent, followed by reaction with extracted phosphate to give dissolved amine molybdophosphate. The amine molybdophosphate then co-crystallizes with amine chloride, formed during the stripping cycle, to give the insoluble double salt, which precipitates as a layer of small particles at the interface. The proposed solution to the problem is the use of branched-chain, instead of straight-chain, tertiary amine extractants under the expectation that branching would increase the solubility of the double salt. 2 figures, 5 tables.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: Union Carbide Corporation, Division of Chemical Sciences, Oak Ridge, TN (US); USDOE
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 6468981
• Report Number(s): CONF-830317-2; ON: DE83009770
• Resource Relation: Conference: TMS/AIME meeting, Atlanta, GA, USA, 6 Mar 1983
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
MOLYBDATES
CHEMICAL REACTIONS
MOLYBDENUM COMPLEXES
PHYSICAL PROPERTIES
PRECIPITATION
STRUCTURAL CHEMICAL ANALYSIS
PHOSPHATES
SODIUM CHLORIDES
TOA
SYNTHESIS
AMEX PROCESS
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
FEED MATERIALS PLANTS
HYDROMETALLURGY
INTERFACES
LEACHING
SOLVENT EXTRACTION
URANIUM ORES
X-RAY DIFFRACTION
ALKALI METAL COMPOUNDS
AMINES
CHELATING AGENTS
CHLORIDES
CHLORINE COMPOUNDS
COHERENT SCATTERING
COMPLEXES
DATA
DIFFRACTION
DISPERSIONS
DISSOLUTION
EXTRACTION
EXTRACTIVE METALLURGY
HALIDES
HALOGEN COMPOUNDS
INDUSTRIAL PLANTS
INFORMATION
KINETICS
METALLURGY
MIXTURES
MOLYBDENUM COMPOUNDS
NUCLEAR FACILITIES
NUMERICAL DATA
ORES
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
REACTION KINETICS
REPROCESSING
SCATTERING
SEPARATION PROCESSES
SODIUM COMPOUNDS
SOLUTIONS
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENT COMPOUNDS
050400* - Nuclear Fuels- Feed Processing
400105 - Separation Procedures
400201 - Chemical & Physicochemical Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)