CO<sub>2</sub> Sequestration by Direct Aqueous Mineral Carbonation under Low-Medium Pressure Conditions

Abstract

As CO2 is the largest contributor to the greenhouse effect, reducing the total CO2 emissions into the atmosphere has been considered as the breakthrough point of mitigating the greenhouse effect. Mineral carbonation is a potential route for CO2 sequestration. In this paper, the mineral carbonation reaction characteristics of wollastonite, serpentine and olivine under low-medium pressure conditions were investigated. Many tests including XRD, XRF, BET and thermal decomposition were applied. Parameters, such as reaction temperature, reaction pressure, particle size, solution composition and heat-treatment, were discussed in details. The results show that besides increase of reaction temperature and pressure, addition of NaHCO3 and decrease of particle size can also effectively accelerate the carbonation reaction for all the three minerals. Heat-treatment of minerals is only useful for serpentine. Highest carbonation conversion efficiency of 83.5%, 47.7% and 16.9% was respectively achieved for wollastonite, serpentine and olivine under the condition of T=150°C, P=40 bar and particle sizes <30 µm. Compared the conversion efficiencies, it is indicated that wollastonite was the most reactive mineral and olivine was suggested to be not suitable for CO2 sequestration by direct aqueous mineral carbonation under low-medium pressure conditions.