TY - JOUR
T1 - Phase transition and dissolution behavior of Ca/Mg-bearing silicates of steel slag in acidic solutions for integration with carbon sequestration
AU - Mei, Xiaohui
AU - Zhao, Qing
AU - Min, Yi
AU - Liu, Chengjun
AU - Saxén, Henrik
AU - Zevenhoven, Ron
N1 - Funding Information:
The authors gratefully acknowledge supports by the National Natural Science Foundation of China (No. 52074078 ), the Liaoning Provincial Natural Science Foundation of China (No. 2019-MS-127 ), and the Fundamental Research Funds for the Central Universities ( N2125034 ).
Publisher Copyright:
© 2022 The Institution of Chemical Engineers
PY - 2022/3
Y1 - 2022/3
N2 - Steel slag (SS) and carbon dioxide are two major waste products of the iron- and steelmaking process. Indirect aqueous carbonation of SS using Ca/Mg is a promising way for carbon capture, utilization, and storage (CCUS). However, it is generally accepted that the Si-rich layer produced during the leaching of silicates in SS has serious implications for the Ca/Mg recovery. Therefore, understanding the phase transition and dissolution behavior of Ca/Mg-bearing silicates of SS in acidic solutions is of vital importance for SS-based CCUS. In this work, three synthetic Ca/Mg-bearing silicates (Ca3MgSi2O8, Ca2MgSi2O7, and γ-Ca2SiO4) of SS were prepared and studied by leaching tests. Experiments were carried out with leaching silicate powder in 0.1 mol· L−1 HCl solution for various reaction time at room temperature. Results show γ-Ca2SiO4 and Ca3MgSi2O8 dissolved rapidly during the early leaching stages, giving more silica gel towards the end. Phases of Ca3MgSi2O8 and Ca2MgSi2O7 dissolved to yield Ca2+ and Mg2+ in solution in a similar ratio as in the original mineral. The Ca2MgSi2O7 phase was transformed into diopside (CaMgSi2O6) and silica gel during the acid leaching. Thus, the difference in phase transition of the studied Ca/Mg-bearing silicates is primarily related to the dissolution of the Si group in the crystal.
AB - Steel slag (SS) and carbon dioxide are two major waste products of the iron- and steelmaking process. Indirect aqueous carbonation of SS using Ca/Mg is a promising way for carbon capture, utilization, and storage (CCUS). However, it is generally accepted that the Si-rich layer produced during the leaching of silicates in SS has serious implications for the Ca/Mg recovery. Therefore, understanding the phase transition and dissolution behavior of Ca/Mg-bearing silicates of SS in acidic solutions is of vital importance for SS-based CCUS. In this work, three synthetic Ca/Mg-bearing silicates (Ca3MgSi2O8, Ca2MgSi2O7, and γ-Ca2SiO4) of SS were prepared and studied by leaching tests. Experiments were carried out with leaching silicate powder in 0.1 mol· L−1 HCl solution for various reaction time at room temperature. Results show γ-Ca2SiO4 and Ca3MgSi2O8 dissolved rapidly during the early leaching stages, giving more silica gel towards the end. Phases of Ca3MgSi2O8 and Ca2MgSi2O7 dissolved to yield Ca2+ and Mg2+ in solution in a similar ratio as in the original mineral. The Ca2MgSi2O7 phase was transformed into diopside (CaMgSi2O6) and silica gel during the acid leaching. Thus, the difference in phase transition of the studied Ca/Mg-bearing silicates is primarily related to the dissolution of the Si group in the crystal.
KW - Ca/Mg-bearing silicate
KW - CO sequestration
KW - Indirect aqueous carbonation
KW - Phase transition
KW - Steel slag
UR - http://www.scopus.com/inward/record.url?scp=85122508061&partnerID=8YFLogxK
U2 - 10.1016/j.psep.2021.12.062
DO - 10.1016/j.psep.2021.12.062
M3 - Article
AN - SCOPUS:85122508061
SN - 0957-5820
VL - 159
SP - 221
EP - 231
JO - Process Safety and Environmental Protection
JF - Process Safety and Environmental Protection
ER -