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.