摘要
The CaO–SiO_(2)–Al_(2)O_(3)–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 and w(MgO)/w(Al_(2)O_(3))ratios.The changes in w(MgO)/w(Al_(2)O_(3))ratio and basicity could affect the stability of each ion-oxygen.Increasing the basicity and w(MgO)/w(Al_(2)O_(3))ratio,the average coordination number of O surrounding Si atom only 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 4 to 6,which indicated that the Al existence form could be transformed from[AlO_(4)]^(5−) tetrahedron to[AlO_(5)]^(7−) pentahedron and[AlO_(6)]^(9−) octahedron.Also,the diffusion rate of ions was accelerated with the increase in w(MgO)/w(Al_(2)O_(3))ratio and basicity.Moreover,the self-diffusion coefficients of each ion were obtained,and the magnitudes were observed to be in the following order:Mg^(2+)>Ca^(2+)>Al^(3+)>Si^(4+).The calculation and analysis of the slag viscosity and activation energy of viscous flow under different basicities and w(MgO)/w(Al_(2)O_(3))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(Al_(2)O_(3))ratio could be controlled between 0.45 and 0.55.
基金
The authors received financial support from the National Natural Science Foundation of China(No.51874171)
University of Science and Technology Liaoning Talent Project Grants(No.601011507-05)
Project of"Xingliao Talents Plan"of Liaoning Province(XLYC1902092).