Aqueous Carbonation of Steel Slags: A Comparative Study on Mechanisms

Author

Nannan Zhang
Gao Deng
Wenyu Liao, Missouri University of Science and TechnologyFollow
Hongyan Ma, Missouri University of Science and TechnologyFollow
Chuanlin Hu

Abstract

This study investigated the aqueous carbonation mechanisms of three typical steel slags: ladle metallurgy furnace (LMF) slag containing high Al content, electric arc furnace (EAF) slag featuring high Si content and relatively low Al content, and ladle-arc fusion (LAF) slag with medium-Al content. It was found that the carbonation kinetics of the three slags were similar and followed the surface coverage model within the first 6 h of carbonation. Initially, the carbonation process was primarily governed by the reaction product precipitation. After 3 h of carbonation, the process was dominated by mineral dissolution, controlled by the uncovered reactive sites. The carbonation-reactive Ca-bearing minerals in the slags, including silicates (CRSis) and aluminates (CRAls), sequestered CO2 to form calcite during carbonation, accompanied by the formation of silica gel and alumina gel, respectively. CRSi, mainly larnite, was present in EAF and LAF slags, showing high reactivity, whereas mayenite (i.e., C12A7), a CRAl mineral present across all slags, exhibited high reactivity in LMF slag but lower reactivity in EAF and LAF slags. Furthermore, AFm phases and katoite (i.e., C3AH6) were detected in LMF slag as CRAls along with mayenite, and their carbonation reactivity decreased in the order of AFm>mayenite>katoite. As a result, low-Al steel slag tends to have higher carbonation reactivity, as manifested by the high carbonation degree of EAF slag throughout the reaction period, notably achieving a 40 % carbonation degree within 30 min and 71 % after 24 h under the studied conditions.

Recommended Citation

N. Zhang et al., "Aqueous Carbonation of Steel Slags: A Comparative Study on Mechanisms," Cement and Concrete Composites, vol. 155, article no. 105838, Elsevier, Jan 2025.

The definitive version is available at https://doi.org/10.1016/j.cemconcomp.2024.105838

Department(s)

Civil, Architectural and Environmental Engineering

Comments

U.S. Department of Energy, Grant DE-FE0032395

Keywords and Phrases

Carbonation; Electric arc furnace slag; Kinetics; Ladle metallurgy furnace slag; Mechanism; Steel slag

International Standard Serial Number (ISSN)

0958-9465

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

01 Jan 2025