Barite solubilities and thermodynamic quantities up to 300/sup 0/C and 1400 bars
Solubilities of specially synthesized coarse-grained barite were determined in H/sub 2/O solutions from 22 to 280/sup 0/C and 1 to 1400 bars, and in 0.2 and 4 molal NaCl solutions from 100 to 250/sup 0/C and 1 to 500 bars. Isobaric solubilities are maximum near 100/sup 0/C in H/sub 2/O solutions; the maxima migrate to progressively higher temperatures in solutions of increasing NaCl concentrations. Isothermal solubilities increase with rising NaCl concentration and pressure. The effect of NaCl on increasing solubilities becomes greater with rising temperature. Changing temperatures cause different responses, depending on the composition of the solution and the temperature range. Initially-saturated dilute natural waters would precipitate barite with either increasing temperature or decreasing temperature, depending on the circumstances. Saline solutions are capable of behaving much like dilute solutions below 1 molal NaCl, but at higher NaCl concentrations the temperature effect on isobaric solubilities is monotonically positive. Barite solubility in sufficiently saline solutions in nature would increase with depth, due to increasing temperature and pressure. Precipitation would tend to occur during migration of solutions toward the surface. Because the low solubility of barite precludes effective transport of BaSO/sub 4/ in large quantities, precipitation of barite by the reaction of Ba/sup 2 +/ with sulfate derived from the oxidation of S/sup 2 -/ may be more important as a depositional mechanism than changes in the temperature-pressure environment. Thermodynamic equilibrium constants (K) and the free-energy changes for the reaction (..delta..G) for the dissolution of barite were calculated from the solubility data. Enthalpies, entropies, and volumes of reaction obtained from the solubility data are in accord with published data. Activity coefficients calculated using barite solubilities in NaCl solutions and log K data are accurately modeled by an extended form of the Debye-Hueckel equation.
- Research Organization:
- Idaho State Univ., Pocatello
- OSTI ID:
- 5025991
- Journal Information:
- Am. Mineral.; (United States), Vol. 62:9-10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BARITE
SOLUBILITY
THERMODYNAMIC PROPERTIES
AQUEOUS SOLUTIONS
BARIUM SULFATES
CHEMICAL REACTION KINETICS
ENTHALPY
ENTROPY
EQUILIBRIUM
HIGH TEMPERATURE
MATHEMATICAL MODELS
MEDIUM PRESSURE
MEDIUM TEMPERATURE
PRECIPITATION
PRESSURE DEPENDENCE
SODIUM CHLORIDES
TEMPERATURE DEPENDENCE
VOLUME
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHLORIDES
CHLORINE COMPOUNDS
DISPERSIONS
HALIDES
HALOGEN COMPOUNDS
KINETICS
MINERALS
MIXTURES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
SEPARATION PROCESSES
SODIUM COMPOUNDS
SOLUTIONS
SULFATES
SULFUR COMPOUNDS
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