Document Type

Article

Publication Date

8-2013

Keywords

mineral carbonation, ultrasound, process intensification, stainless steel slag, shrinking core, carbon sink

Abstract

Several aspects of ultrasound-assisted mineral carbonation were investigated in this work. The objectives were to intensify the CO2 sequestration process to improve reaction kinetics and maximal conversion. Stainless steel slags, derived from the Argon Oxygen Decarburization (AOD) and Continuous Casting / Ladle Metallurgy (CC/LM) refining steps, were used for assessing the technical feasibility of this concept, as they are potential carbon sinks and can benefit from reduction in alkalinity (pH) by mineral carbonation. Ultrasound was applied by use of an ultrasound horn into the reaction slurry, where mineral carbonation reaction took place at 50 oC for up to four hours; comparison was made to solely mechanically mixed process. It was found that sonication increases the reaction rate after the initial stage, and permits achieving higher carbonate conversion and lower pH. AOD slag conversion increased from 30% to 49%, and pH decreased from 10.6 to 10.1; CC slag conversion increased from 61% to 73% and pH decreased from 10.8 to 9.9. The enhancement effect of ultrasound was attributed to the removal of passivating layers (precipitated calcium carbonate and depleted silica) that surround the unreacted particle core and inhibit mass transfer. Significant particle size reduction was observed for sonicated powders, compared to particle size growth in the case of stirring only; D[4,3] values increased without sonication by 74% and 50%, and decreased with sonication by 64% and 52%, respectively for AOD and CC slags. Considerations on scale-up of this technology, particularly with regards to energy efficiency, are also discussed.

Comments

9 November 2016: At the time of publication, Sheridan College author Rafael M. Santos was associated with the Katholieke Universiteit Leuven in Belgium.

Faculty

Faculty of Applied Science & Technology

School

School of Chemical and Environmental Sciences

Journal

Applied Thermal Engineering

Version

Post-print

Peer Reviewed/Refereed Publication

yes

Funder

PGS-D support from the Natural Sciences and Engineering Research Council of Canada (NSERC)

Terms of Use

Terms of Use for Works posted in SOURCE.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Original Publication Citation

Santos, R. M., Francois, D., Mertens, G., Elsen, J., & Van Gerven, T. (2013). Ultrasound-intensified mineral carbonation. Applied Thermal Engineering, 57(1-2), 154-163. doi:10.1016/j.applthermaleng.2012.03.035

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