Microbial-Enhanced Steel Slag Fixation of CO2 from Cement Kiln Flue Gas for the Production of Supplementary Cementitious Material
Chunxiang Qian,
Yijin Fan,
Yafeng Rui,
Xiao Zhang,
Yangfan Xu
Affiliations
Chunxiang Qian
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Microbial Bio-Mineralization Technology, China Construction Materials Industry, Nanjing 211189, China; Research Center of Green Construction Materials and Carbon Utilization, Southeast University, Nanjing 211189, China; Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China; State Key Laboratory of Engineering Materials for Major Infrastructure, Southeast University, Nanjing 211189, China; Corresponding author.
Yijin Fan
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Microbial Bio-Mineralization Technology, China Construction Materials Industry, Nanjing 211189, China; Research Center of Green Construction Materials and Carbon Utilization, Southeast University, Nanjing 211189, China; Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China; State Key Laboratory of Engineering Materials for Major Infrastructure, Southeast University, Nanjing 211189, China
Yafeng Rui
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Microbial Bio-Mineralization Technology, China Construction Materials Industry, Nanjing 211189, China; Research Center of Green Construction Materials and Carbon Utilization, Southeast University, Nanjing 211189, China; Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China; State Key Laboratory of Engineering Materials for Major Infrastructure, Southeast University, Nanjing 211189, China
Xiao Zhang
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Microbial Bio-Mineralization Technology, China Construction Materials Industry, Nanjing 211189, China; Research Center of Green Construction Materials and Carbon Utilization, Southeast University, Nanjing 211189, China; Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China; State Key Laboratory of Engineering Materials for Major Infrastructure, Southeast University, Nanjing 211189, China
Yangfan Xu
School of Materials Science and Engineering, Southeast University, Nanjing 211189, China; Key Laboratory of Microbial Bio-Mineralization Technology, China Construction Materials Industry, Nanjing 211189, China; Research Center of Green Construction Materials and Carbon Utilization, Southeast University, Nanjing 211189, China; Jiangsu Key Laboratory of Construction Materials, Southeast University, Nanjing 211189, China; State Key Laboratory of Engineering Materials for Major Infrastructure, Southeast University, Nanjing 211189, China
The production of cement and concrete using carbonated steel slag as a supplementary cementitious material achieves the dual benefits of efficient steel slag utilization and CO2 fixation. In this study, a combination of microbial technology and a rotary kiln process was employed to expedite the carbonation of steel slag for CO2 fixation from cement kiln flue gas. This approach resulted in a significant increase in the CO2-fixation rate, with a CO2-fixation ratio of approximately 10% achieved within 1 h and consistent performance across different seasons throughout the year. Investigation revealed that both the CO2-fixation ratio and the particle fineness are pivotal for increasing the soundness and reactivity of steel slag. When the CO2-fixation ratio exceeds 8% and the specific surface area is at least 300 m2∙kg−1, the soundness issue of steel slag can be effectively addressed, facilitating the safe utilization of steel slag. Residual microbes present in the carbonated steel slag powder act as nucleating sites, increasing the hydration rate of the silicate phases in Portland cement to form more hydration products. Microbial regulation results in the biogenic calcium carbonate having smaller crystal sizes, which facilitates the formation of monocarboaluminate to increase the strength of hardened cement paste. At the same CO2-fixation ratio, microbial mineralized steel slag powder exhibits greater hydration activity than carbonated steel slag powder. With a CO2-fixation ratio of 10% and a specific surface area of 600 m2∙kg−1, replacing 30% of cement clinker with microbial mineralized steel slag powder yields an activity index of 87.7%. This study provides a sustainable solution for reducing carbon emissions and safely and efficiently utilizing steel slag in the construction materials sector, while expanding the application scope of microbial technology.
