TOWARD A BETTER UNDERSTANDING OF DESILICATION PRODUCT (DSP) PRECIPITATION KINETICS

LaMacchia, R.

Deriving kinetics equations for DSP precipitation can be difficult because of the simultaneous effects of two concurrent processes, namely reactive silica dissolution and DSP precipitation. In this work, a more fundamental approach has been sought, to further understand DSP precipitation mechanisms over wide ranging sets of conditions. While the literature has historically reported growth rates for this reaction, DSP growth is not the sole mechanism at play. For this reason, conventional methods for obtaining the kinetic rate constant and order are confounded. In modelling the pre-digestion circuit of an alumina refinery, it is hypothesized that secondary nucleation is the dominant mechanism, allowing a conventional fit to an empirical kinetic equation with order, n = 1.81 ± 0.63.