Calculation of chemical equilibrium between aqueous solution and minerals: the EQ3/6 software package
Description
The newly developed EQ/36 software package computes equilibrium models of aqueous geochemical systems. The package contains two principal programs: EQ3 performs distribution-of-species calculations for natural water compositions; EQ6 uses the results of EQ3 to predict the consequences of heating and cooling aqueous solutions and of irreversible reaction in rock--water systems. The programs are valuable for studying such phenomena as the formation of ore bodies, scaling and plugging in geothermal development, and the long-term disposal of nuclear waste. EQ3 and EQ6 are compared with such well-known geochemical codes as SOLMNEQ, WATEQ, REDEQL, MINEQL, and PATHI. The data base allows calculations in the temperature interval 0 to 3500C, at either 1 atm-steam saturation pressures or a constant 500 bars. The activity coefficient approximations for aqueous solutes limit modeling to solutions of ionic strength less than about one molal. The mathematical derivations and numerical techniques used in EQ6 are presented in detail. The program uses the Newton--Raphson method to solve the governing equations of chemical equilibrium for a system of specified elemental composition at fixed temperature and pressure. Convergence is aided by optimizing starting estimates and by under-relaxation techniques. The minerals present in the stable phase assemblage are found by several empirical methods. Reaction path models may be generated by using this approach in conjunction with finite differences. This method is analogous to applying high-order predictor--corrector methods to integrate a corresponding set of ordinary differential equations, but avoids propagation of error (drift). 8 figures, 9 tables
Availability note (English)
MF available from INIS under the Report Number; Available from NTIS., PC A03/MF A01.Files
10474294.pdf
Files
(2.4 MB)
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Additional details
Additional titles
- Augmented title (English)
- In FORTRAN extended 4.6 for CDC6600 and 7600
Publishing Information
- Imprint Pagination
- 46 p.
- Report number
- UCRL--52658
INIS
- Country of Publication
- United States
- Country of Input or Organization
- United States
- INIS RN
- 10474294
- Subject category
- S12: MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; S58: GEOSCIENCES;
- Quality check status
- Yes
- Descriptors DEI
- AQUEOUS SOLUTIONS; CDC COMPUTERS; CHEMICAL COMPOSITION; CHEMICAL REACTION KINETICS; COMPUTER CODES; DISSOLUTION; E CODES; EQUILIBRIUM; FELDSPARS; FORTRAN; GEOTHERMAL POWER PLANTS; GROUND WATER; HEATING; HIGH PRESSURE; HIGH TEMPERATURE; MEDIUM PRESSURE; MEDIUM TEMPERATURE; MINERALIZATION; MINERALS; NEWTON METHOD; ORES; PRECIPITATION; RADIOACTIVE WASTE DISPOSAL; SCALING; SEAWATER;
- Descriptors DEC
- CHEMICAL REACTIONS; COMPUTERS; CORROSION; DISPERSIONS; HOMOGENEOUS MIXTURES; HYDROGEN COMPOUNDS; ITERATIVE METHODS; KINETICS; MANAGEMENT; MIXTURES; OXYGEN COMPOUNDS; POWER PLANTS; PROGRAMMING LANGUAGES; REACTION KINETICS; SEPARATION PROCESSES; SOLUTIONS; THERMAL POWER PLANTS; WASTE DISPOSAL; WASTE MANAGEMENT; WATER;