Mineral carbonation accelerated by dicarboxylic acids as a disposal process of carbon dioxide

Abstract

Mineral carbonation is based on the reaction of carbon dioxide with metal-oxide bearing minerals, usually containing magnesium or calcium silicate, to form hardly soluble carbonates and other solid byproducts. The concept is based on acceleration of the naturally occurring rock weathering process. In the present work the calcium silicate is present in the mineral, wollastonite. To accelerate the process and make it potentially useful for practical applications, mineral carbonation is conducted here using an indirect two-step route in which the reactive component (Ca 2+ ions in considered case) is first extracted from the mineral matrix and afterwards carbonated. Two solid byproducts are formed in this process: silica in the extraction step and calcium carbonate in the carbonation step. In the experimental part of this work, both stages of mineral carbonation are investigated using three extraction media: acetic acid and two dicarboxylic acids, succinic and adipic. To interpret the extraction stage of the mineral carbonation process the shrinking core – shrinking shell model is proposed. In the model, the change of the unreacted core size is due to surface reaction that is affected by the porous layer diffusion, with the porous layer subject to abrasion. The model of abrasion is based on the theory of turbulence. Results of investigations show that succinic acid is most effective, followed by adipic acid and acetic acid when both stages of the process are considered in detail.