(480a) Controlled Removal of Si-Rich Passivation Layer Using a Binary-Solid Fluidized Bed Reactor for Enhanced Carbon Capture and Storage Via Mineralization

Carbon capture, utilization, and storage (CCUS) is an important technology for our sustainable energy future. One of the combined CCUS approach is ex-situ carbonation of silicate minerals and alkaline industrial wastes such as steel slags. As magnesium and calcium silicates are chemically reacted with CO₂, value-added product can be produced in the form of thermodynamically stable solid carbonates. This is one of the most promising CO₂ sequestration technology because it can be integrated into various chemical processes and the overall process does not require the energy intensive solvent regeneration step. The main challenge of this technology is slow reaction rates associated with mineral dissolution, CO2 hydration and precipitation of solid carbonates. Our past studies showed that a mixture of Mg and Si-targeting ligands can significantly enhance the mineral dissolution, while whole-cell biocatalysts with carbonic anhydrase can improve the rate of CO2 hydration in the aqueous phase. While these advancements led to a better design of carbon mineralization process, the overall extent of reaction is still limited due to the development of Si-rich passivation layer on the surface of Mg and Ca-silicates. Thus, a binary-solid fluidized bed is designed to remove the Si-rich passivation layer during the mineral dissolution while bubbling CO2. The effects of the size and density ratios of mineral particles and in-situ grinding media are investigated in terms of the overall extent of reaction. A revised shrinking-core model is developed to describe how the thickness of the passivation layer impacts the dissolution behaviors of Mg- and Ca-bearing minerals.