Extension of the EQ3/6 computer codes to geochemical modeling of brines
Recent modifications to the EQ3/6 geochemical modeling software package provide for the use of Pitzer's equations to calculate the activity coefficients of aqueous species and the activity of water. These changes extend the range of solute concentrations over which the codes can be used to dependably calculate equilibria in geochemical systems, and permit the inclusion of ion pairs, complexes, and undissociated acids and bases as explicit component species in the Pitzer model. Comparisons of calculations made by the EQ3NR and EQ6 compuer codes with experimental data confirm that the modifications not only allow the codes to accurately evaluate activity coefficients in concentrated solutions, but also permit prediction of solubility limits of evaporite minerals in brines at 25/sup 0/C and elevated temperatures. Calculations for a few salts can be made at temperatures up to approx. 300/sup 0/C, but the temperature range for most electrolytes is constrained by the availability of requisite data to values less than or equal to 100/sup 0/C. The implementation of Pitzer's equations in EQ3/6 allows application of these codes to problems involving calculation of geochemical equilibria in brines; such as evaluation of the chemical environment which might be anticipated for nuclear waste canisters located in a salt repository. 26 references, 3 figures, 1 table.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6151123
- Report Number(s):
- UCRL-91121; CONF-841157-62; ON: DE85005502
- Country of Publication:
- United States
- Language:
- English
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Verification and validation studies of the addition of Pitzer's equations to the EQ3/6 brine model
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12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
58 GEOSCIENCES
580400* -- Geochemistry-- (-1989)
BRINES
CHEMISTRY
COMPUTER CODES
COMPUTERIZED SIMULATION
E CODES
EQUILIBRIUM
GEOCHEMISTRY
KINETICS
REACTION KINETICS
SIMULATION
THERMODYNAMIC ACTIVITY