Contact of clay-liner materials with acidic tailings. II. Chemical modeling
The ion speciation-solubility model WATEQ3 was used to model original aqueous solutions and solutions resulting from liner materials contacted with uranium mill tailings, synthetic mill tailings or H/sub 2/SO/sub 4/. The modeling results indicate solution species which are in apparent equilibrium with respect to particular solids. These solids provide potential solubility controls for their corresponding dissolved constituents. The disequilibrium indices computed by WATEQ3 indicate amorphic Fe(OH)/sub 3/(A), Al0HO/sub 4/, alunite (KA1/sub 3/(SO/sub 4/)/sub 2/(OH)/sub 6/), gypsum (CaSO/sub 4/ . 2H/sub 2/O), celestite (SrSO/sub 4/), anglesite (PbSO/sub 4/) and MnHPO/sub 4/ may have precipitated in the contacted liner materials and may also provide solubility controls for their dissolved constituents. The disequilibrium indices also show that the solutions resulting from the interaction of Highland Mill tailings are oversaturated with K-, H-, and Na-jarosites ((K,H,Na)Fe/sub 3/(SO/sub 4/)/sub 2/(OH)/sub 6/). Because jarosite has been identified by x-ray diffraction as a precipitate in these reacted liner materials, it would appear that there is a kinetic barrier which prohibits jarosite from being an effective solubility control. Results of this study also show that the solubilities of many solid phases were pH dependent. This exploratory use of geochemical modeling has demonstrated its capability to test solubility hypotheses for clay liners reacted with tailings solutions and to guide the analyses of important constituents and parameters for these solutions. Geochemical modeling can be used, in parallel with characterization techniques for the solid phases, to support the presence of the solid phase and to guide the search for further solid phases. Geochemical modeling is also an effective tool in delineating the chemical causes for changes in permeability of liner materials.
- Research Organization:
- Pacific Northwest Lab., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5664896
- Report Number(s):
- PNL-SA-9824; CONF-811049-12; ON: DE82005897; TRN: 82-008506
- Resource Relation:
- Conference: 4. symposium on uranium mill tailings management, Fort Collins, CO, USA, 26 Oct 1981
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
58 GEOSCIENCES
36 MATERIALS SCIENCE
CLAYS
SOLUBILITY
LINERS
CHEMICAL REACTORS
MILL TAILINGS
ALUMINIUM SULFATES
CHEMICAL ANALYSIS
EQUILIBRIUM
GEOCHEMISTRY
GYPSUM
IRON HYDROXIDES
LEAD SULFATES
MANGANESE PHOSPHATES
MATHEMATICAL MODELS
PERMEABILITY
PH VALUE
STRONTIUM SULFATES
W CODES
X-RAY DIFFRACTION
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM SULFATES
CHEMISTRY
COHERENT SCATTERING
COMPUTER CODES
DIFFRACTION
HYDROGEN COMPOUNDS
HYDROXIDES
IRON COMPOUNDS
LEAD COMPOUNDS
MANGANESE COMPOUNDS
MINERALS
OXYGEN COMPOUNDS
PHOSPHATES
PHOSPHORUS COMPOUNDS
SCATTERING
SOLID WASTES
STRONTIUM COMPOUNDS
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
TAILINGS
TRANSITION ELEMENT COMPOUNDS
WASTES
052000* - Nuclear Fuels- Waste Management
580400 - Geochemistry- (-1989)
360603 - Materials- Properties