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Title: Calculation of chemical equilibrium between aqueous solution and minerals: the EQ3/6 software package. [In FORTRAN extended 4. 6 for CDC6600 and 7600]

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 350{sup 0}C, 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 more » 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. « less
Authors:
Publication Date:
OSTI Identifier:
6451946
Report Number(s):
UCRL-52658
TRN: 79-010364
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Research Org:
California Univ., Livermore (USA). Lawrence Livermore Lab.
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; 58 GEOSCIENCES; COMPUTER CODES; E CODES; GEOTHERMAL POWER PLANTS; SCALING; ORES; MINERALIZATION; RADIOACTIVE WASTE DISPOSAL; ROCK-FLUID INTERACTIONS; AQUEOUS SOLUTIONS; CDC COMPUTERS; CHEMICAL COMPOSITION; CHEMICAL REACTION KINETICS; DISSOLUTION; EQUILIBRIUM; FORTRAN; GEOTHERMAL FLUIDS; HEATING; HIGH PRESSURE; HIGH TEMPERATURE; MEDIUM PRESSURE; MEDIUM TEMPERATURE; MICROCLINE; MINERALS; NEWTON METHOD; PRECIPITATION; SALTON SEA; SEAWATER; WATER; CALIFORNIA; COMPUTERS; DISPERSIONS; FELDSPARS; FLUIDS; HYDROGEN COMPOUNDS; IMPERIAL VALLEY; ITERATIVE METHODS; KINETICS; MANAGEMENT; MIXTURES; NORTH AMERICA; OXYGEN COMPOUNDS; POWER PLANTS; PROGRAMMING LANGUAGES; REACTION KINETICS; SEPARATION PROCESSES; SOLUTIONS; THERMAL POWER PLANTS; USA; WASTE DISPOSAL; WASTE MANAGEMENT; WESTERN REGION Geothermal Legacy 152003* -- Geothermal Data & Theory-- Rock-Water-Gas Interactions; 150903 -- Geothermal Engineering-- Corrosion, Scaling & Materials Development; 052002 -- Nuclear Fuels-- Waste Disposal & Storage; 580400 -- Geochemistry-- (-1989)