Enhancing Process Kinetics for Mineral Carbon Sequestration

The current low-cost process for mineral carbonation involves the direct carbonation of a slurry of magnesium or calcium silicate mineral with supercritical CO2. The process is currently limited by the slow reaction kinetics of the carbonation reactions, and in particular the slow dissolution rates of the silicates in weakly acidic conditions. Enhancing the dissolution rate in weakly acidic conditions has been identified as one of the main opportunities for lowering the costs of a direct mineral carbonation process. Serpentine has been identified by its reactivity and abundance as a potential mineral for use in a mineral carbonation process. In this paper we discuss the results of dissolution experiments in which ground serpentine was reacted in weakly acidic aqueous systems containing NH4Cl, NaCl,, sodium citrate, sodium EDTA, sodium oxalate, and sodium acetate. All experiments are carried out at 120 degrees C and under 20 bars of CO2 in a batch autoclave. It was found that the sodium salts of citrate, oxalate, and EDTA significantly enhance the dissolution of serpentine under weakly acidic conditions. (C) 2009 Elsevier Ltd. All rights reserved.