The kinetics of chlorite dissolution
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Date
2007-03-15
Journal Title
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Publisher
Elsevier
Abstract
A model for the dissolution of chlorite has been developed based on fast ligand assisted proton attack of the alumina tetrahedra within the alumina-silica lattice followed by slower dissolution of the remnant silica lattice. While the rate determining step is within the silica dissolution regime, the rate is a function of the H+ and Al3+ concentrations and the dominant aqueous Al species. Individual rates may be described by a generic rate equation applicable across the spectrum of Al species: where rn is the rate subscripted for the nth Al species, k is the rate constant of the rate controlling step, K is the surface exchange constant, β is the solution stability constant subscripted for the Al species, a is the species activity subscripted for species and raised to the power of the stoichiometry, p and q are stoichiometric coefficients, z is the ligand charge and τ is the fractional coefficient for the precursor of the rate defining step. The observed rate is the sum of the individual rates. When the observed rate is in a domain of dominance for a single aluminium species and in the absence of strong complexing agents such as oxalate, the observed rate is proportional to (a3H+/aAl3+)τn. The model is supported by experimental data for the dissolution of chlorite over a pH range of 3–10 and temperature range 25–95°C. The results have hydrometallurgical application. © 2007, Elsevier Ltd.
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Keywords
Kinetics, Chlorite minerals, Dissolution, Ligands, Aluminates, Silica
Citation
Lowson, R. T., Brown, P. L., Comarmond, M. C. J., & Rajaratnam, G. (2007). The kinetics of chlorite dissolution. Geochimica Et Cosmochimica Acta, 71(6), 1431-1447. doi:10.1016/j.gca.2006.12.008