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Phase Equilibria in System CaO‐CO 2 ‐H 2 O and Related Systems, with Implications for Crystal Growth of Calcite and Apatite
Author(s) -
WYLLIE PETER J.
Publication year - 1967
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1967.tb14969.x
Subject(s) - calcite , apatite , crystallization , isothermal process , phase (matter) , aqueous solution , mineralogy , crystal (programming language) , isobaric process , phase diagram , chemical engineering , materials science , chemistry , thermodynamics , physics , organic chemistry , engineering , computer science , programming language
Conditions for crystallization of calcite from melts in the presence of a vapor or gaseous phase are reviewed to provide possible guidelines for growth of calcite. Phase equilibrium data for the system CaO‐CO 2 show that to precipitate calcite from molten CaCO 3 the temperature must be above 1230° C and excess CO 2 must be present at pressures greater than 39.5 bars. Phase equilibrium data for the system CaO‐CO 2 ‐H 2 O show that calcite can be precipitated from melts at 650°C in the presence of an aqueous vapor phase at 10 bars or more. Crystallization can be induced either by introducing temperature variations, or by changing the composition of the coexisting aqueous vapor phase under isobaric, isothermal conditions. The system CaO‐MgO‐CO 2 ‐H 2 O is used to show that doped calcite crystals, Ca x R 1 ‐ x CO 3 , could be precipitated, with precisely controlled compositions, from melts in the system CaO‐RO‐CO 2 ‐H 2 O. Apatite phase relations are also presented.