The dual-effect of the CO₂ capture efficient by red mud under atmospheric pressure and synergistic de–alkalization

With the objective of using red mud to 60% by 2025 and carbon peaking in the Al₂O₃ industry by 2030, red mud carbon capture would become an area of investigation. This research presents a synergistic dealkalization technique for net CO₂ capture from red mud at atmospheric pressure. Red mud captures 11.67 g/kg CO₂ at 80–100 mesh particle size, 1:20 solid–liquid ratio, 10 ml/(g min) ventilation rate, 60 °C reaction temperature, and 10% CO₂ ratio. FTIR and XRD revealed the primary mechanism for capturing CO₂ is the reaction of CO₃²⁻ and HCO₃²⁻ with other minerals, including aqueous calcium aluminum garnet, to form minerals that were primarily calcium nephelite. Furthermore, H₂O mostly coupled with SiO₂ and other Si-containing components to generate silicate, which then combined with CO₂ to form calcium nepheline, achieving CO₂ capture and mineralization, according to C and Si XPS. Finally, given the present yearly production of red mud, which is around 120 million tons, the net fixed CO₂ of red mud in China is 600–700 kt.