Developing an integrated CO₂ capture and mineralization process with lower energy consumption

The urgency to reduce CO₂ emissions and manage industrial residues like Recycled Concrete Aggregates (RCA) has led to innovative methods for converting CO₂ into mineralized carbonates. Direct carbon mineralization addresses both industrial residue treatment and CO₂ sequestration. However, high energy consumption in current CO₂ capture processes, such as the MEA process, and complex mineralization conditions hinder practical implementation. To overcome these challenges, we developed an integrated CO₂ absorption and mineralization process. Using an ammonia solution to capture CO₂, we create a CO₂ absorption solution (CAS) that reacts directly with RCA, producing calcium carbonate and regenerating the absorption solvent without the need for energy-intensive desorption. Experiments confirmed the carbonation reaction between CAS and RCA at ambient conditions, achieving a carbonation efficiency of 70.5 g_CO2/(kg_RCA·h). This method demonstrates the potential of storing CO₂ in RCA as calcium carbonate while minimizing energy penalties through regenerable CO₂ capture solvents. Techno-economic analysis (TEA) supports its economic viability, with a carbonated product cost below USD11.06/ton and energy consumption under 0.18 GJ/ton, allowing for an annual CO₂ storage capacity of 1 million tons in RCA.