Investigation of Mineral Carbonation with Direct Bubbling into Concrete Sludge

[Image: see text] Mineral carbonation, which is CO(2) fixation through a carbonation reaction using alkaline earth metals, is being investigated as a carbon capture and utilization method to reduce CO(2) atmospheric emissions. Concrete sludge is an alkali waste material from the concrete industry and contains abundant calcium components. We investigated the applicability of concrete sludge for mineral carbonation. In this study, gas containing CO(2) was bubbled through the model concrete sludge solution and the effects of the solid–liquid ratio, bubbling time, gas flow rate, and the partial pressure of CO(2) on the CO(2) fixation ratio and fixation rate were investigated. The CO(2) fixation ratio decreased with increasing CO(2) bubbling time, CO(2) flow rate, and CO(2) partial pressure. The CO(2) fixation rate increased with increasing CO(2) flow rate and CO(2) partial pressure. The formation of calcite, a form of calcium carbonate, was confirmed.