Ju Jiantao, Ji Guangheng, Tang Chenmei, Yang Kangshuai, Zhu Zhihong
School of Metallurgical Engineering, Xi'an University of Architecture and Technology, Xi'an, 710055, People's Republic of China.
Research Center of Metallurgical Engineering Technology of Shaanxi Province, Xi'an, 710055, People's Republic of China.
Sci Rep. 2020 Jul 23;10(1):12284. doi: 10.1038/s41598-020-69283-6.
The isothermal kinetics of fluoride evaporation from CaF-CaO-AlO-MgO-TiO-(LiO) slag with varying LiO content were investigated in the temperature range 1743-1803 K by thermogravimetric analysis. Thermodynamic calculations and viscosity measurements were applied for studying the evaporation mechanism of fluoride. The results showed that the evaporation ratio increases with increasing LiO content and temperature. The volatile constituents from the molten slags, mainly LiF and CaF, were detected and their concentrations calculated. The fluoride evaporation is primarily affected by the vapour pressure of LiF and CaF, viscosity of the slags, and melt-component activities under given experimental conditions. On the other hand, mass transfer of the gas is not the rate-controlling step that affects fluoride evaporation from the slags. The activation energy for fluoride evaporation gradually decreased from 193 ± 11 to 113 ± 3 kJ mol as the LiO content in the slags increases from 0 to 5.48 wt%. These results hold great theoretical significance for developing low-fluoride slags for electroslag remelting.
通过热重分析研究了在1743 - 1803 K温度范围内，LiO含量不同的CaF-CaO-AlO-MgO-TiO-(LiO)熔渣中氟化物蒸发的等温动力学。采用热力学计算和粘度测量来研究氟化物的蒸发机理。结果表明，蒸发率随LiO含量和温度的升高而增加。检测到熔渣中的挥发性成分，主要是LiF和CaF，并计算了它们的浓度。在给定的实验条件下，氟化物蒸发主要受LiF和CaF的蒸气压、熔渣粘度以及熔体组分活度的影响。另一方面，气体的传质不是影响熔渣中氟化物蒸发的速率控制步骤。随着熔渣中LiO含量从0增加到5.48 wt%，氟化物蒸发的活化能从193±11逐渐降低到113±3 kJ/mol。这些结果对于开发用于电渣重熔的低氟熔渣具有重要的理论意义。
