Niobium in hydrothermal systems related to alkali granites: Thermodynamic description of hydroxo and hydroxofluoride complexes
| Autor: | V. S. Korzhinskaya, N. N. Akinfiev, E. V. Lukyanova, Alexander V. Zotov, I. T. Rass, N. P. Kotova |
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| Rok vydání: | 2017 |
| Předmět: |
Aqueous solution
010504 meteorology & atmospheric sciences Inorganic chemistry Oxide Niobium chemistry.chemical_element Geology 010502 geochemistry & geophysics Alkali metal 01 natural sciences Hydrothermal circulation Ion chemistry.chemical_compound chemistry Geochemistry and Petrology Economic Geology Solubility Fluoride 0105 earth and related environmental sciences |
| Zdroj: | Geology of Ore Deposits. 59:305-314 |
| ISSN: | 1555-6476 1075-7015 |
| Popis: | Available experimental data on the solubility of Nb2O5 and the stability constants for particles of an aqueous solution in the Nb–O–H–F system were processed. As a result, a set of thermodynamic properties for 25°C and 1 bar was obtained, in addition to the equation parameters for the HKF model (Helgeson–Kirkham–Flowers) for hydroxo and hydroxofluoride niobium complexes. F– ion is the most important factor governing the concentration of dissolved Nb: neutral hydroxo complex Nb(OH)5(aq) is formed at a low HF concentration, whereas an increase in HF results in an increase in the first Nb(OH)4F(aq) and second Nb(OH)3F2(aq) fluoride complexes. The Nb(OH)5F– oxofluoride anion determines oxide solubility in alkali F-bearing fluids. Neutralization of acidic fluoride solution can be the main factor leading to niobium deposition. |
| Databáze: | OpenAIRE |
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