Effect of CaO-MgO-FeO-SiO[sub.2]-Ix/INa[sub.2]O Slag System on Converter Dephosphorization

• Published in: Metals (Basel ) 2023-04, Vol.13 (5)
• Main Authors: Geng, Bin, Zhan, Dongping, Jiang, Zhouhua, Yang, Yongkun
• Format: Article
• Language: English
• Subjects: Iron oxides; Lime; Steel-works; Supply and demand
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met13050844

Na[sub.2]O is an alkaline oxide, which can significantly improve the dephosphorization ability of converter slag. The effect of Na[sub.2]O on the dephosphorization of converter slag was analyzed with a high-temperature dephosphorization experiment in a MoSi[sub.2] resistance furnace. We found that the dephosphorization rate increased with the increase of (Na[sub.2]O) in the dephosphorization slag. The elements of Ca, Si, O, and P in the dephosphorization slag are distributed in the same area, mainly in the form of phosphate minerals, such as Ca[sub.2]SiO[sub.4]·0.05Ca[sub.3](PO[sub.4])[sub.2] and 6Ca[sub.2]SiO[sub.4]·Ca[sub.3](PO[sub.4])[sub.2]. After adding Na[sub.2]O, part of the Na will replace the Ca in the phosphorus-containing phase to form Ca[sub.2]SiO[sub.4]·Ca[sub.2]Na[sub.2](PO[sub.4])[sub.2]. The industrial test showed that the average dephosphorization rate in the early stage of the test heats with the CaO-MgO-FeO-SiO[sub.2]-0.5%Na[sub.2]O slag system could reach 62.39%, which was 19.62% higher than that of the conventional heats. The average basicity of the final slag was 0.19% lower than that of the conventional heats, while w(P[sub.2]O[sub.5]) increased by 0.36%, and T.Fe decreased by 0.69%. The average consumption of the slagging materials was 35.93 kg/t, which was 7.24 kg/t less than that of the conventional heats. Through thermodynamic calculation, we found that with the increase of (Na[sub.2]O), the phosphorus distribution ratio between slag and steel increased significantly, the area of the liquid phase zone of the slag system increased continuously, and the viscosity decreased continuously.