Effect of pH, CO<sub>2</sub> and organic ligands on the kinetics of talc and lizardite dissolution

Natural sheet magnesium silicates are potential sources of divalent cations, which are necessary for the mineralization of CO2 in the carbonates. In order to study the influence of inorganic (HCO3−) and organic (oxalate and citrate) ligands on the kinetics of dissolution of talc and serpentine, experiments were performed in a flow-through reactor at 25°C. Dissolution rates of natural silicates r (mol cm−2 s−1) in solutions of various compositions were calculated at the stationary stage of dissolution after a rapid initial stage, which is characterized by the formation of a surface leached layer depleted in magnesium. The presence of ligands increases the dissolution rate of magnesium silicates due to the formation of surface complexes, which leads to separation of magnesium from the surface and transition into solution. Initial incongruent stage may be the most promising for the development of carbonation technologies, since the minimum removal of the network-forming elements prevents the undesirable formation of secondary minerals (for example, clays), which exclude divalent cations from the carbonation process and greatly reduce the permeability of rocks.