Mass transfer of phosphorus in high-phosphorus hot-metal refining

Abstract

Mass transfer of phosphorus in high-phosphorus hot-metal refining was investigated using CaO-Fe _tO-SiO₂ slags at 1623 K. Based on a two-film theory kinetic model and experimental results, it was found that the overall mass transfer coefficient, which includes the effects of mass transfer in both the slag phase and metal phase, is in the range of 0.0047 to 0.0240 cm/s. With the addition of a small amount of fluxing agents Al₂O₃ or Na₂O into the slag, the overall mass transfer coefficient has an obvious increase. Silicon content in the hot metal also influences the overall mass transfer coefficient. The overall mass transfer coefficient in the lower [Si] heat is much higher than that in the higher [Si] heat. It is concluded that both fluxing agents and lower [Si] hot metal facilitate mass transfer of phosphorus in liquid phases. Furthermore, the addition of Na₂O could also prevent rephosphorization at the end of the experiment.

Keywords

steelmaking / refining / dephosphorization / mass transfer coefficients / kinetics

References

[1] He JY, Zhou P, Zhuang GZ, Du JH. Study of dephosphorization process for high-phosphorus iron ore. Min. Eng., 2008, 6(2): 29.

[2] Liu J, Li GQ, Zhu CY, Wang CA. Research progress in treatment of high phosphorus iron ore and dephosphorization of high phosphorus hot metal. J. Mater. Metall., 2007, 6(3): 173.

[3] Tripathy PK, Banerjee A, Singh B, Das D, Das AK. Approaches for conversion of high phosphorus hot metal to steel for flat products. ISIJ Int., 2008, 48(5): 578.

[4] Wang YH, Xie B, Diao J, Li XJ, Zhang JX. Solubility in citric acid of dephosphorization slags from high phosphorus hot metal refining. J. Univ. Sci. Technol. Beijing, 2011, 33(3): 323.

[5] Diao J, Xie B, Wang YH, Guo X. Recovery of phosphorus from dephosphorization slag produced by duplex high phosphorus hot metal refining. ISIJ Int., 2012, 52(6): 955.

[6] Zhou JD, Bi XG, Yang F. Experimental study on phosphorus distribution between CaO-FeO*-SiO₂-P₂O₅(15%)-CaF₂ slag and carbon-saturated hot metal at 1573.15 K. Ironmaking Steelmaking, 2014, 41(4): 298.

[7] Basu S, Lahiri AK, Seetharaman S, Seetharaman S, Halder J. Change in phosphorus partition during blowing in a commercial BOF. ISIJ Int., 2007, 47(5): 766.

[8] Choudhary SK, Lenka SN, Ghosh A. Assessment and application of equilibrium slag-metal phosphorous partition for basic oxygen steelmaking. Ironmaking Steelmaking, 2007, 34(4): 343.

[9] Zheng SS, Chen WH, Cai J, Li JT, Chen C, Luo XT. Mass transfer of phosphorus in silicon melts under vacuum induction refining. Metall. Mater. Trans. B, 2010, 41(6): 1268.

[10] Zhang X, Xie B, Li HY, Diao J, Ji CQ. Coupled reaction kinetics of duplex steelmaking process for high phosphorus hot metal. Ironmaking Steelmaking, 2013, 40(4): 282.

[11] Manning CP, Fruehan RJ. The rate of the phosphorous reaction between liquid iron and slag. Metall. Mater. Trans. B, 2013, 44(1): 37.

[12] Wei P, Sano M, Hirasawa M, Mori K. Kinetics of phosphorus transfer between iron oxide containing slag and molten iron of high carbon concentration under Ar-O₂ atmosphere. ISIJ Int., 1993, 33(4): 479.

[13] Conejo AN, Lara FR, Macias-Hernández M, Morales RD. Kinetic model of steel refining in a ladle furnace. Steel Res. Int., 2007, 78(2): 141.

[14] Tian ZH. Technology and Theory of Molten Steel Deep Dephosphorization out of Converter for Production of Ultra-low Phosphorus Steel, 2005, Beijing, University of Science and Technology Beijing, 141.

[15] Mori K, Doi S, Kaneko T, Kawai Y. Rate transfer of phosphorus between metal and slag. Trans. Iron Steel Inst. Jpn., 1978, 18(5): 261.

[16] Manning CP. Behavior of Phosphorus in DRI/HBI during Electric Furnace Steelmaking, 2000, Pittsburgh, Carnegie Mellon University, 175.