Laboratory evaluation of limestone and lime neutralization of acidic uranium mill tailings solution. Progress report
Experiments were conducted to evaluate a two-step neutralization scheme for treatment of acidic uranium mill tailings solutions. Tailings solutions from the Lucky Mc Mill and Exxon Highland Mill, both in Wyoming, were neutralized with limestone, CaCO/sub 3/, to an intermediate pH of 4.0 or 5.0, followed by lime, Ca(OH)/sub 2/, neutralization to pH 7.3. The combination limestone/lime treatment methods, CaCO/sub 3/ neutralization to pH 4 followed by neutralization with Ca(OH)/sub 2/ to pH 7.3 resulted in the highest quality effluent solution with respect to EPA's water quality guidelines. The combination method is the most cost-effective treatment procedure tested in our studies. Neutralization experiments to evaluate the optimum solution pH for contaminant removal were performed on the same two tailings solutions using only lime Ca(OH)/sub 2/ as the neutralizing agent. The data indicate solution neutralization above pH 7.3 does not significantly increase removal of pH dependent contaminants from solution. Column leaching experiments were performed on the neutralized sludge material (the precipitated solid material which forms as the acidic tailings solutions are neutralized to pH 4 or above). The sludges were contacted with laboratory prepared synthetic ground water until several effluent pore volumes were collected. Effluent solutions were analyzed for macro ions, trace metals and radionuclides in an effort to evaluate the long term effectiveness of attenuating contaminants in sludges formed during solution neutralization. Neutralized sludge leaching experiments indicate that Ca, Na, Mg, Se, Cl, and SO/sub 4/ are the only constituents which show solution concentrations significantly higher than the synthetic ground water in the early pore volumes of long-term leaching studies.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5226136
- Report Number(s):
- NUREG/CR-3449; PNL-4809; ON: DE84007401
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CALCIUM CARBONATES
COMPARATIVE EVALUATIONS
CALCIUM HYDROXIDES
MILL TAILINGS
PH VALUE
SLUDGES
LEACHING
CHEMICAL COMPOSITION
COST
EXPERIMENTAL DATA
GROUND WATER
LEACHATES
LIMESTONE
LIQUID WASTES
REAGENTS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE ROCKS
CARBONATES
DATA
DISPERSIONS
DISSOLUTION
HYDROGEN COMPOUNDS
HYDROXIDES
INFORMATION
MIXTURES
NUMERICAL DATA
OXYGEN COMPOUNDS
ROCKS
SEDIMENTARY ROCKS
SEPARATION PROCESSES
SOLID WASTES
SOLUTIONS
TAILINGS
WASTES
WATER
052001* - Nuclear Fuels- Waste Processing
053000 - Nuclear Fuels- Environmental Aspects