Author:

Keywords:

Carbonation, Slag, Process Intensification, Ultrasound

Abstract:

Mineral carbonation of AOD stainless steel slags, synthetic minerals and pure oxides were investigated. The main goal was to sequester the maximal amount of CO2 under optimal conditions. Carbonation was conducted on humid samples in a CO2 chamber and in slurry phase. The carbonation reaction was intensified by the introduction of ultrasound as a means to accelerate the carbonation reaction by particle fragmentation and carbonate layer removal. Several process parameters that influence carbonation were studied, such as temperature, moisture content, particle size and CO2 partial pressure. It was found that C2S minerals have a greater CO2 uptake capacity than Merwinite, and hence steel slags containing greater C2S amounts showed greater carbonation extent. The highest conversion achieved with AOD steel slags in the CO2 chamber was 30% at 30oC, 20% CO2 partial pressure and 7 days duration. Briquettes of AOD slag were made in the CO2 chamber by carbonation, and the material was found to develop significant cohesive strength, reaching 8.5 MPa compressive strength after 7 days. Carbonation of calcium oxide in slurry reached full conversion over 60 minutes. The enhancement effect of sonication was dimmed by the fast reaction kinetics of calcium oxide. The sonication effect was observed by the reduction in particle size and the eroded morphology of the sonicated particles.