Evolution of Interface Characteristic between Quicklime and CaO-SiO2-FetO-MgO Melt during Slag-Forming Procedure in Converter under Different Times

作者：Zhang, Mengxu; Li, Jianli^*; Jia, Cao; Yu, Yue; Xie, Xiao^*

来源：Steel Research International, 2023, 94(12).

DOI：10.1002/srin.202300183

• 2CaO
• SiO2
• dissolution rates
• mass transfers
• quicklimes
• reaction interfaces

In 2022, China produced 1.018 billion tons of crude steel, with steel slag accounting for 10-15% of the output. The presence of 10-20% f-CaO in steel slag causes volume instability, hindering comprehensive utilization. The generation of f-CaO is closely associated with the dissolution of quicklime during the converter slag-forming procedure. This study focuses on investigating the evolution of the lime-slag interface and the variations in lime dissolution rate under different slag conditions using the electron probe microanalyzer and ImageJ. The results reveal that the formation of the CaO-FeO solid solution, (Ca, Mg, Fe) olivine, and low-melting point (Ca, Mg) olivine at 1400 & DEG;C. As the FeO content decreases, a dense and high-melting-point 2CaO & BULL;SiO2 layer is formed. A maximum thickness of the 2CaO & BULL;SiO2 layer is precipitated at a dissolution time of 180 s. Additionally, the average dissolution rate of lime in different slags shows an initial increase followed by a subsequent decrease. Among the slag studied, the highest average dissolution rate is in slag A3 at 2.24 x 10(-6) m s(-1), while the lowest rate is in slag A4 at 1.49 x 10(-6) m s(-1). The presence of the 2CaO & BULL;SiO2 layer hinders the mass transfer, thereby further inhibiting the reaction.