Reaction between CO2 and CaO under dry grinding

This study was carried out to investigate the reaction between CO2 and materials that contain CaO under dry grinding. Chemical reagent CaO was used in this experiment, and waste concrete was also tested to examine the feasibility of CO2 sorption into it. Samples were ground in a CO2 atmosphere by a centrifugal ball mill. The reaction was measured with the constant volume method. The effects of amount of sample, the number and diameter of balls, the concentration of CO2 in the mixture of CO2 and air and the rotational speed on the CO2 sorption were examined. The amount of the CO2 sorption under grinding was larger than that without grinding. The grinding enhanced the reaction between CaO and CO2. The CO2 sorption steeply increased with time in the early stage of grinding. After that, it increased gradually. The CO2 reacted with the CaO at the surface layer of the newly exposed surface of the CaO particles during the grinding. The initial sorption rate of CO2 was related with the shear force. In the latter stage of grinding, the grinding process caused the CaO particles to agglomerate. As a result, the sorption of CO2 became slow. It was found that the waste concrete had high potential for sorption of CO2 by means of dry grinding.