1 School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, Liaoning, China; 2 State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
Effect of w(MgO)/w(Al2O3) ratio and basicity on microstructure and metallurgical properties of blast furnace slag
1 School of Materials and Metallurgy, University of Science and Technology Liaoning, Anshan 114051, Liaoning, China; 2 State Key Laboratory of Advanced Special Steel, Shanghai Key Laboratory of Advanced Ferrometallurgy, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
摘要 The CaO–SiO2–Al2O3–MgO system is the main component unit in the slag formation process in blast furnace smelting. Its structural changes directly affect the high-temperature metallurgical properties of slag. Molecular dynamics simulations were thus conducted to analyze the microstructure changes of the quaternary slag system under different basicities andw(MgO)/w(Al2O3) ratios. The changes in w(MgO)/w(Al2O3) ratio and basicity could affect the stability of each ionoxygen. Increasing the basicity and w(MgO)/w(Al2O3) ratio, the average coordination number of O surrounding Si atomonly changed a little and remained approximately 4, indicating that Si exists as a stable structure of the [SiO4]4-tetrahedron in the slag structure, while the average coordination number of O surrounding Al atom changed greatly from 4to 6, which indicated that the Al existence form could be transformed from [AlO4]5- tetrahedron to [AlO5]7- pentahedron and [AlO6]9- octahedron. Also, the diffusion rate of ions was accelerated with the increase in w(MgO)/w(Al2O3) ratio andbasicity. Moreover, the self-diffusion coefficients of each ion were obtained, and the magnitudes were observed to be in the following order: Mg2+>Ca2+>Al3+>Si4+. The calculation and analysis of the slag viscosity and activation energy of viscous flow under different basicities and w(MgO)/w(Al2O3) ratios revealed that the metallurgical properties of slag at high temperature depend on the flow-unit diffusivity and the microstructure stability, simultaneously, the basicity should be controlled between 1.0 and 1.2, and the w(MgO)/w(Al2O3) ratio could be controlled between 0.45 and 0.55.
Abstract：The CaO–SiO2–Al2O3–MgO system is the main component unit in the slag formation process in blast furnace smelting. Its structural changes directly affect the high-temperature metallurgical properties of slag. Molecular dynamics simulations were thus conducted to analyze the microstructure changes of the quaternary slag system under different basicities andw(MgO)/w(Al2O3) ratios. The changes in w(MgO)/w(Al2O3) ratio and basicity could affect the stability of each ionoxygen. Increasing the basicity and w(MgO)/w(Al2O3) ratio, the average coordination number of O surrounding Si atomonly changed a little and remained approximately 4, indicating that Si exists as a stable structure of the [SiO4]4-tetrahedron in the slag structure, while the average coordination number of O surrounding Al atom changed greatly from 4to 6, which indicated that the Al existence form could be transformed from [AlO4]5- tetrahedron to [AlO5]7- pentahedron and [AlO6]9- octahedron. Also, the diffusion rate of ions was accelerated with the increase in w(MgO)/w(Al2O3) ratio andbasicity. Moreover, the self-diffusion coefficients of each ion were obtained, and the magnitudes were observed to be in the following order: Mg2+>Ca2+>Al3+>Si4+. The calculation and analysis of the slag viscosity and activation energy of viscous flow under different basicities and w(MgO)/w(Al2O3) ratios revealed that the metallurgical properties of slag at high temperature depend on the flow-unit diffusivity and the microstructure stability, simultaneously, the basicity should be controlled between 1.0 and 1.2, and the w(MgO)/w(Al2O3) ratio could be controlled between 0.45 and 0.55.
Wei-guo Kong,Ji-hui Liu,Yao-wei Yu, et al. Effect of w(MgO)/w(Al2O3) ratio and basicity on microstructure and metallurgical properties of blast furnace slag[J]. Journal of Iron and Steel Research International, 2021, 28(10): 1223-1232.
2021, Vol. 28 
