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Effect of Carbon Dioxide Pressure on Mineral Carbonation in Acidic Solutions
산성용액에서 이산화탄소의 압력이 광물탄산화에 미치는 영향
Econ. Environ. Geol. 2020 Feb;53(1):1-9
Published online February 28, 2020;  https://doi.org/10.9719/EEG.2020.53.1.1
Copyright © 2020 the Korean society of economic and environmental gelology.

Kyoung Won Ryu1, Seok Jin Hong2 and Sang Hoon Choi2*
류경원1 · 홍석진2 · 최상훈2*

1Korea University of Technology and Education, Cheonan 31253, Republic of Korea
2Department of Earth and Environmental Sciences, College of Natural Sciences, Chungbuk National University, Cheongju 28644, Republic of Korea
1한국과학기술대학교, 2충북대학교
Received December 24, 2019; Revised January 29, 2020; Accepted February 1, 2020.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
 Abstract
Magnesium silicate minerals such as serpentine [Mg3Si2O5(OH)4] have a high potential for the sequestration of CO2; thus, their reactivity toward dissolution under CO2-free and CO2-containing conditions in acidic solvents is a critical process with respect to their carbonation reactions. To examine the carbonation efficiency and dissolution mechanism of serpentine, hydrothermal treatment was performed to the starting material via a modified direct aqueous carbonation process at 100 and 150°C. The serpentine dissolution experiments were conducted in H2SO4 solution with concentration range of 0.3–1 M and at a CO2 partial pressure of 3 MPa. The initial pH of the solution was adjusted to 13 for the carbonation process. Under CO2-free and CO2-containing conditions, the carbonation efficiency increased in proportion to the concentration of H2SO4 and the reaction temperature. The leaching rate under CO2-containing conditions was higher than that under CO2-free conditions. This suggests that shows the presence of CO2 affects the carbonation reaction. The leaching and carbonation efficiencies at 150°C in 1 M H2SO4 solution under CO2-containing conditions were 85 and 84%, respectively. The dissolution rate of Mg was higher than that of Si, such that the Mg : Si ratio of the reacted serpentine decreased from the inner part (approximately 1.5) to the outer part (less than 0.1). The resultant silica-rich layer of the reaction product ultimately changed through the Mg-depleted skeletal phase and the pseudo-serpentine phase to the amorphous silica phase. A passivating silica layer was not observed on the outer surface of the reacted serpentine.
Keywords : serpentine, carbon dioxide, carbonation, dissolution rate, magnesite

 

February 2020, 53 (1)