SiO2在炉渣CaO-SiO2-MgO-Al2O3体系中的熔解行为

采用直接熔解法研究了SiO₂颗粒在CaO-SiO₂-MgO-Al₂O₃渣系中的熔解过程, 探索了炉渣成分、温度对SiO₂颗粒熔解时间的影响规律, 通过SEM-EDS并结合factsage软件分析了SiO₂熔解机理, 确定SiO₂颗粒周围没有形成固相层, 并在此基础上结合缩芯模型构建了动力学模型。结果表明, 随着炉渣碱度及温度提高, SiO₂颗粒熔解完成所需时间逐渐降低, 而随着炉渣中MgO及Al₂O₃含量增加, SiO₂颗粒的熔解完成所需时间先降低后增加。SiO₂的熔解过程分为2个阶段, 反应前期为界面反应控制, 表观活化能为330.52 kJ/mol; 反应后期为外扩散控制, 表观活化能为480.28 kJ/mol, 控制环节的转变是由熔体黏度的变化造成的。

Melting Behavior of SiO2 in CaO-SiO2-MgO-Al2O3 System

The melting process of SiO₂ particles in CaO-SiO₂-MgO-Al₂O₃ system was studied by using direct melting method, and effects of furnace slag compositions, temperature on the SiO₂ particles melting time were investigated. The melting mechanism of SiO₂ particles was analyzed by using SEM-EDS and factsage software. It is found that there was no solid-phase layer formed around SiO₂ particles. On this basis, a kinetic model was constructed by combining with the shrinking core model. Results show that the melting time of SiO₂ particles in slag shortened with the rising of slag basicity and temperature, while the increased content of MgO and Al₂O₃ in slag led to the melting time of SiO₂ particles prolonged after initially shortened. It is shown that the melting process of SiO₂ is divided into two stages: an earlier stage is controlled by a surface reaction, with an apparent activation energy of 330.52 kJ/mol, and the later stage is controlled by an external diffusion with an apparent activation energy of 480.28 kJ/mol. And such transition is mainly caused by the variation in the melt viscosity.