Browsing by Author "Rajaratnam, G"

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    The kinetics of chlorite dissolution
    (Elsevier, 2007-03-15) Lowson, RT; Brown, PL; Comarmond, MJ; Rajaratnam, G
    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.