The effect of CO2CO2 and salinity on olivine dissolution kinetics at 120∘C

This paper reports the results of an experimental study on the dissolution kinetics of olivine (Mg1.82Fe0.18SiO4Mg1.82Fe0.18SiO4) at operating conditions relevant to the mineral carbonation process for the permanent storage of CO2CO2. In particular, we investigated the effects of CO2CO2 fugacity (fCO2fCO2) and of salinity on the kinetics of olivine dissolution, which is assumed to be the rate-limiting step of the overall carbonation process. Dissolution experiments were carried out at 120∘C in a stirred flow-through reactor. Different pH values (between 3 and 8) and solution compositions were investigated by varying fCO2fCO2 and by dosing LiOH (for pH control), NaCl, and NaNO3NaNO3. The specific dissolution rate values, r  , were estimated from the experimental data using a population balance equation (PBE) model coupled with a mass balance equation. The logarithms of the obtained rr values were regressed with a linear model as a function of pH and compared to the model reported earlier [Hänchen, M., Krevor, S., Mazzotti, M., Lackner, K.S., 2007. Validation of a population balance model for olivine dissolution. Chem. Eng. Sci. 62, 6412–6422] for experiments with neither CO2CO2 nor salts. Our results confirm that, at a given temperature, olivine dissolution kinetics depends on pH only, and that fCO2fCO2 and the concentrations of NaCl and NaNO3NaNO3 affect it through their effect on pH.