Speciation of Al, Si, and K in supercritical solutions: Experimental study and interpretation

Journal Article · Tue Aug 01 04:00:00 EDT 1989 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(89)90305-0· OSTI ID:7024648

Pascal, M L ^[1]; Anderson, G M ^[2]

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1. C.R.S.C.M., Orleans (France)
2. Univ. of Toronto, Ontario (Canada)

Corundum and quartz solubilities in KOH-H{sub 2}O and NaOH-H{sub 2}O solutions were measured at 500-700{degree}C and 2 kbar. The observed solubility increase in interpreted by the formation of neutral alkali-aluminum and alkali-silica complexes, with a minor contribution of SiO(OH){sup {minus}}{sub 3} ions; Al(OH){sup {minus}}{sub 4} ions are believed to be practically non-existent at these conditions. The equilibrium constants for these species have been determined, which allows the calculation of their concentration in solutions in the system K{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2}-H{sub 2}O for any 3-mineral buffering association. These calculated concentrations were compared to direct composition measurements for solutions experimentally equilibrated with the considered 3-mineral assemblages. The agreement between calculated and measured concentrations is good for alkaline assemblages where the alkali-aluminum complex seems to be the main Al-bearing species with molalities ranging from 0.002 to 0.02. But for common assemblages such as quartz-mica-feldspar, the (K, Na)Al complex molality is negligible (10{sup {minus}6} to 10{sup {minus}4}), whereas the experimental Al-concentrations (10{sup {minus}3} m) suggest the presence of another Al-bearing species involving both silica and alkalies.

• OSTI ID: 7024648
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 53:8; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

15 GEOTHERMAL ENERGY
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58 GEOSCIENCES
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ALKALI METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL COMPOSITION
CHEMISTRY
COMPLEXES
CONCENTRATION RATIO
CORUNDUM
DISPERSIONS
DISSOLUTION
ENERGY SYSTEMS
EQUILIBRIUM
GEOCHEMISTRY
GEOTHERMAL SYSTEMS
HYDROGEN COMPOUNDS
HYDROTHERMAL SYSTEMS
HYDROXIDES
MINERALS
MIXTURES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
PRESSURE EFFECTS
QUARTZ
ROCK-FLUID INTERACTIONS
SILICON COMPLEXES
SILICON COMPOUNDS
SILICON OXIDES
SOLUBILITY
SOLUTIONS
SUPERCRITICAL STATE
TEMPERATURE EFFECTS