The prediction of mineral solubilities in natural waters: A chemical equilibrium model for the Na-Ca-Cl-SO sub 4 -H sub 2 O system, to high temperature and concentration

Journal Article · Fri Apr 01 00:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90354-7· OSTI ID:5173629

Moeller, N ^[1]

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1. Univ. of California, San Diego, La Jolla (USA)

This paper describes a chemical equilibrium model for the Na-Ca-Cl-SO{sub 4}-H{sub 2}O system which calculates solubilities from 25{degree}C to 250{degree}C and from zero to high concentration (I {approximately} 18. m) within experimental uncertainty. The concentration and temperature dependence of the model were established by fitting available activity (solubility, osmotic and emf) data. A single ion complex, CaSO{sup 0}{sub 4}, which increases in strength with temperature, is included explicitly in the model. The validation of model accuracy by comparison to laboratory and field solubility data is included. Applications of the model are also given. Phase diagrams constructed for the Na-Ca-Cl-SO{sub 4}-H{sub 2}O system and predicted solubilities of anhydrite and hemihydrate in concentrated seawater at high temperature are in very good agreement with the data. Calculations of the temperature of gypsum-anhydrite coexistence as a function of water activity are compared to reported values, and are used to estimate the composition-temperature relation for gypsum-anhydrite transition in a natural brine evaporation. A preliminary model for barite solubility in sodium chloride solutions at high temperature (100{degree}C to 250{degree}C), based on this parameterization of the CaSO{sub 4}-NaCl-H{sub 2}O system, gives good agreement with the data.

• DOE Contract Number: AC03-85SF15522
• OSTI ID: 5173629
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 52:4; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
58 GEOSCIENCES
ANHYDRITE
SOLUBILITY
BARITE
BRINES
ROCK-FLUID INTERACTIONS
THERMODYNAMIC MODEL
GYPSUM
ACCURACY
ACTIVATION ENERGY
CONCENTRATION RATIO
DISSOLUTION
EQUILIBRIUM
GEOCHEMISTRY
PHASE STUDIES
RELIABILITY
SALT DEPOSITS
SODIUM CHLORIDES
SOLVENT PROPERTIES
TEMPERATURE EFFECTS
THERMODYNAMIC ACTIVITY
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BARIUM SULFATES
CALCIUM COMPOUNDS
CALCIUM SULFATES
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
ENERGY
GEOLOGIC DEPOSITS
HALIDES
HALOGEN COMPOUNDS
MATHEMATICAL MODELS
MINERALS
OXYGEN COMPOUNDS
PARTICLE MODELS
SODIUM COMPOUNDS
STATISTICAL MODELS
SULFATE MINERALS
SULFATES
SULFUR COMPOUNDS
400201* - Chemical & Physicochemical Properties
580000 - Geosciences