Reaction paths and equilibrium end-points in solid-solution aqueous-solution systems

Journal Article · Thu Feb 01 00:00:00 EST 1990 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(90)90317-E· OSTI ID:6935827

Glynn, P D; Plummer, L N; Busenberg, E ^[1]; Reardon, E J ^[2]

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1. Geological Survey, Reston, VA (USA)
2. Univ. of Waterloo, Ontario (Canada)

Equations are presented describing equilibrium in binary solid-solution aqueous-solution (SSAS) systems after a dissolution, precipitation, or recrystallization process, as a function of the composition and relative proportion of the initial phases. Equilibrium phase diagrams incorporating the concept of stoichiometric saturation are used to interpret possible reaction paths and to demonstrate relations between stoichiometric saturation, primary saturation, and thermodynamic equilibrium states. The concept of stoichiometric saturation is found useful in interpreting and putting limits on dissolution pathways, but there currently is no basis for possible application of this concept to the prediction and/or understanding of precipitation processes. Previously published dissolution experiments for (Ba, Sr)SO{sub 4} and (Sr, Ca)CO{sub 3orth.} solids are interpreted using equilibrium phase diagrams. These studies show that stoichiometric saturation can control, or at least influence, initial congruent dissolution pathways. The results for (Sr, Ca)CO{sub 3orth.} solids reveal that stoichiometric saturation can also control the initial stages of incongruent dissolution, despite the intrinsic instability of some of the initial solids. In contrast, recrystallization experiments in the highly soluble KCl-KBr-H{sub 2}O system demonstrate equilibrium. The phase diagram reveals an alyotropic maximum located at {chi}{sub KBr} = 0.676 and at a total solubility product, {Sigma}II = (K{sup +})((Cl{sup {minus}}) + (Br{sup {minus}})) = 15.35.

• OSTI ID: 6935827
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Vol. 54:2; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CARBONATE MINERALS
PRECIPITATION
STOICHIOMETRY
SOLID SOLUTIONS
EQUILIBRIUM
THERMODYNAMIC ACTIVITY
SULFATE MINERALS
AQUEOUS SOLUTIONS
BARIUM SULFATES
DISSOLUTION
FREE ENERGY
GEOCHEMISTRY
PHASE DIAGRAMS
PHASE STUDIES
RECRYSTALLIZATION
SATURATION
STRONTIUM CARBONATES
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATES
CHEMISTRY
DIAGRAMS
DISPERSIONS
ENERGY
MINERALS
MIXTURES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SEPARATION PROCESSES
SOLUTIONS
STRONTIUM COMPOUNDS
SULFATES
SULFUR COMPOUNDS
THERMODYNAMIC PROPERTIES
580000* - Geosciences