CO2 uptake of cement by-pass dust via direct aqueous carbonation: an experimental design for time and temperature optimisation

The compositional characteristics of cement by-pass dust (CBPD), specifically its alkalinity and salt content, present significant limitations to its reinsertion in cement production. Furthermore, these characteristics give rise to considerable concerns regarding its disposal. The present study investigated the potential for treating CBPD through the application of a direct aqueous carbonation technique. The aim is to assess carbon capture potential of the material and to investigate the impact of the mineralisation process on its composition. The process was conducted under atmospheric pressure, at low temperature (20-60 degrees C) and for short duration (20-60 min). Different CO2 quantification techniques were employed to assess experiments efficiency and replicability of the adopted quantification techniques. A Design of Experiment was developed to identify the optimum carbonation conditions in terms of time and temperature. The conditions for CO2 content maximisation resulted in a fair agreement with the prediction of the response surface methodology. High values in CO2 uptake (25.1%) and carbonation degree (82%) were achieved, outperforming previous literature studies. Moreover, the mineralisation process significantly reduces the chloride content of CBPD, paving the way for its adoption as a supplementary cementitious material in integrated industrial processes for carbon capture and utilisation.