Abstract: In view of the large use of calcium fluoride in LF refining process， an optimization scheme of fluorine-free refining slag system is proposed.Calculated by FactSage software， the optimal composition of the fluorine-free refining slag was determined to be： the mass fraction of CaO：52%-58%， SiO2：8%-12%， Al₂O₃：25%-35%， MgO：5%-7%， with a basicity of 4-6 and a （CaO）/（Al₂O₃）ratio of 1.5-2.0. Compared to the original slag system， the new fluorine-free slag system can be completely melted at 1 500 ℃， reducing the melting temperature by 60 ℃， and has a Mannesmann index of approximately 0.15， which meets the performance requirements of LF refining slag. Using the optimized slag system in the actual production， the application of the optimized slag system resulted in a 24% reduction in total oxygen content， a 21.3% reduction in nitrogen content， a 22.9% reduction in the number of inclusions during refining process， and a 22.4% reduction in the number of inclusions during the tundish process compared to the pre-optimization slag system. The results demonstrate that the fluorine-free slag system not only significantly improves the cleanliness of molten steel and enhances the quality of steel but also aligns with current development trend of environmental protection and energy saving， reducing the corrosion of metallurgical equipment and environmental pollution， thus offering significant environmental protection and economic benefits. This study provides a viable solution for steel enterprises to achieve efficient refining processes and significantly improve the cleanliness and quality of steel without using calcium fluoride.

Key words: 45 Steel, Inclusions, Refining Slag Optimization, CaF₂

摘要： 针对某钢厂在LF精炼过程中大量使用氟化钙的问题，本研究提出了一种无氟精炼渣系的优化方案。通过FactSage软件计算，确定了无氟精炼渣的最佳成分比例：CaO的质量分数为52%~58%，SiO2为8%~12%，Al₂O₃为25%~35%，MgO为5%~7%，碱度控制在4~6之间，（CaO）/（Al₂O₃）比值为1.5~2.0。与原渣系相比，新的无氟渣系在1 500 ℃下即可完全熔化，熔化温度降低了60 ℃，曼内斯曼指数约为0.15，满足LF精炼渣的性能要求。在实际生产中应用优化后的渣系，与优化前相比，轧材的全氧含量下降了24%，氮含量下降了21.3%，精炼过程中夹杂物数量减少了22.9%，中间包过程中夹杂物数量减少了22.4%。结果表明，无氟渣系能显著提高钢水的洁净度，对提升钢材质量具有重要作用，同时，也符合当前环保和节能的发展趋势。这些改进不仅提升了钢材的质量，还符合当前环保和节能的发展趋势，减少了对冶金设备的腐蚀和环境的污染，具有重要的环保和经济效益。通过本研究，钢铁企业可以在不使用氟化钙的情况下，依然实现高效的精炼过程，显著提升钢材的洁净度和质量。

关键词: 45钢, 夹杂物, 精炼渣优化, 氟化钙