Dissolution of dehydroxylated lizardite at flue gas conditions: II. Kinetic modeling

•A kinetic model for the dissolution of dehydroxylated lizardite is developed.•Two particle structures are proposed and validated for the dehydroxylated particles.•The model describes a non-steady state dissolution behavior.•Non-stoichiometric dissolution profiles of the solutes are accurately captured.

A non-steady state kinetic model was developed that describes the dissolution kinetics of partially dehydroxylated lizardite at far-from-equilibrium operating conditions, at temperatures of 30–120 °C and CO2 partial pressures of 0.1–2.0 bar. Based on two simplified dehydroxylation pathways that represent the extreme cases, namely of a fully homogeneous dehydroxylation and a heterogeneous dehydroxylation, two different particle structures for the dehydroxylated material were considered. The model uses surface complexation mechanisms to describe the specific dissolution rates. Both particle structures were able to reproduce equally well the experimental concentration profiles which were the result of multiple dissolving species in the particles. The model estimates the kinetic parameters for these species from the large set of dissolution data reported in the first part of this publication series. The model was able to describe the evolution of the non-stoichiometric aqueous concentration profiles of magnesium and silica accurately, taking into account the dynamic evolution of the reactor pH at non-steady state dissolution conditions. The kinetic parameters could be used to compare the dissolution performances of differently activated minerals in their application as potential feed materials for an ex situ mineral carbonation process.