(808c) Novel CO2 Capture and Carbonation Process With Waste Concrete

Yamasaki, A., Seikei University
Shuto, D., Seikei University
Hongo, T., Seikei University
Iizuka, A., Tohoku University

A novel CO2 capture and carbonation process is developed. In this process, wastes containing calcium, such as waste cement particles or steel slug, are used as a calcium source for carbonation reaction with CO2 emitted from point sources. The process is composed of several steps. CO2 in the flue gas is captured through absorption process with alkaline solution such as sodium hydroxide to form sodium carbonate and sodium bicarbonate. The calcium content in the waste cement particles is extracted with acid such as nitric acid or acetic acid to form solution containing calcium. Mixing of these two solutions leads to the precipitation of calcium carbonate: CO2 fixation via carbonation reaction. Electrodialysis is applied for the regeneration of acid and alkaline from the remained solution after filtration of the precipitant. Thus, the net input of the process is CO2 in the flue gas and waste cement particles, and the output is calcium carbonate. The process feasibility was examined through laboratory -scale experimental studies under various operation conditions. Based on the experimental results, the process was optimized and evaluated in terms of the power consumption and cost for the CO2 recovery, and compared with conventional processes. Net CO2 sequestration can be achieved by the process under certain conditions.