『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:
rn = kn ((Kn/βAlpLq(3p-zq))(aH+3p/aAl3+p)/(1
+ (Kn/βAlpLq(3p-zq))(aH+3p/aAl3+p)))τn,
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 stoichoimetry,
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 aluminum species and in the absence of strong complexing
agents such as oxalate, the observed rate is proportional to (aH+3/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℃. The results have hydrometallurgical
application.』
1. Introduction
2. Theory
2.1. Background
2.2. Theory
3. Experimental
3.1. Method
4. Results
4.1. Data
4.1.1. Raw data
4.1.2. Species calculations
4.1.3. Solubility of chlorite
4.2. Variation of reaction rate with H+ and Al3+
4.3. The fractional coefficient, τn
4.4. Energies of activation
5. Conclusions and applications
Acknowledgments
Appendix A
A.1. Temperature corrections
A.2. Variable flow corrections
A.3. Simplification of the general rate expression for the case
of mononuclear species
References