Analysis of the Phase Composition and Microstructure of Slag from a Semi-Steel Converter
DOI:
https://doi.org/10.24425/afe.2026.158015Abstract
To clarify the phase composition, microstructural characteristics, and phosphorus retention mechanisms of semi-steel converter slag, this study employed characterization techniques such as XRD, SEM-EDS, FTIR, and Raman spectroscopy to systematically compare the mineral composition, phosphorus retention patterns, and microstructure of semi-steel converter slag with those of single-slag converter slag. The results show that the main mineral phases in both types of slag are C2F, C2S, and the RO phase; in single-slag converter slag, phosphorus primarily exists as n-dicalcium silicate-tricalcium phosphate solid solutions, with a small amount tending to be fixed in the glass phase and other phosphates; in semi-steel converter slag, phosphorus is enriched in the form of nC2S-C3P solid solutions and C3P, with a small amount present in the glass phase and phosphorus-containing solid solutions; Both types of slag are composed of phosphates, silicates, and iron-aluminum coordination structures, with relatively low siloxane polymerization degrees, and P-O-P and P-O-Si are not major structural units. However, there are significant differences in the iron coordination environment: in semi-steel converter slag, iron primarily exists as FeO4 tetrahedra and FeO6 octahedra, whereas in single-slag converter slag, iron tends to form FeO4 tetrahedra; furthermore, the silicon and phosphorus group content and network polymerization degree in single-slag converter slag are significantly higher than those in semi-steel converter slag. This study provides a theoretical basis for the resource utilization of converter slag and the optimization of smelting process parameters.
References
[1] Chen, K., Wang, D. & Guo, A. (2025). Research on green development efficiency of iron and steel industry based on super-efficient SBM-malmquist index modeling. International Core Journal of Engineering. 11(6), 23-32. https://doi.org/10.6919/ICJE.202506_11(6).0003 .
[2] Kasraee, A.R., Shirazi, H. & Alba, K.A. (2026). Scientometric review of green technologies in the steel industry. Iranica Journal of Energy & Environment. 17(1), 72-92. https://doi.org/10.5829/ijee.2026.17.01.07.
[3] Han, D.W., Qiu. J., Hu, F.W. et al. (2019). High efficiency dephosphorization method and low cost control for 150 t converter of bearing steel. China Metallurgical Society. In Proceedings of the 12th China Iron and Steel Annual Conference—Vol. 2: Steelmaking and Continuous Casting (pp. 500-505). Beijing: Metallurgical Industry Press.
[4] Zhang, Z. L., Chen, R., Men, X. R. & Sun, Y. (2019). Phase compositions and microstructure of slag in BOF. Journal of Materials and Metallurgy. 18(1), 37-40.
[5] Zhang, R., Jia, J.X., Liu, C. & Min, Y. (2021). Microstructure behaviors of phosphorus in converter slag. Journal of Northeastern University (Natural Science). 42(5), 646-651.
[6] Liang, X. H., Wang, X. H., He, X. F. & Wang, W. J. (2014). Mineral phase and utilization of semisteel slag produced during BOF double slag process. Journal of Iron and Steel Research. 26(10), 15-20.
[7] Zhou, C., Chen, Q., Zhao, J., Ai, L., Wang, S., Shi, D. & Li, J. (2023). Effect of sinter return ore addition on dephosphorisation behaviour of hot metal. ISIJ International. 63(11), 1842-1853. https://doi.org/10.2355/isijinternational.ISIJINT-2023-183.
[8] Agathopoulos, S., Tulyaganov, D. U., Ventura, J. M. G., Kannan, S., Saranti, A., Karakassides, M. A. & Ferreira, J. M. F. (2006). Structural analysis and devitrification of glasses based on the CaO–MgO–SiO2 system with B2O3, Na2O, CaF2 and P2O5 additives. Journal of Non-Crystalline Solids. 352(4), 322-328. DOI: 10.1016/j.jnoncrysol.2005.12.003.
[9] Li, B. & Zhou, G. (2025). Preparation of phosphate glass by the conventional and microwave melt-quenching methods and research on its performance. Materials. 18(5), 1079, 1-20. https://doi.org/10.3390/ma18051079.
[10] Sun, Y., Zhang, Z., Liu, L. & Wang, X. (2015). FTIR, Raman and NMR investigation of CaO–SiO2–P2O5 and CaO–SiO2–TiO2–P2O5 glasses. Journal of Non-Crystalline Solids. 420, 26-33. DOI: 10.1016/j.jnoncrysol.2015.04.017.
[11] Wang, Z., Sun, Y., Sridhar, S., Zhang, M., Guo, M. & Zhang, Z. (2015). Effect of Al2O3 on the viscosity and structure of CaO–SiO2–MgO–Al2O3–FetO slags. Metallurgical and Materials Transactions B. 46(2), 537-541. https://doi.org/10.1007/s11663-015-0303-4.
[12] Lucazeau, G., Sergent, N., Pagnier, T., Shaula, A., Kharton, V. & Marques, F. M. B. (2007). Raman spectra of apatites: La10-xSi6-r(Al, Fe)rO26±δ. Journal of Raman Spectroscopy. 38(1), 21-33. https://doi.org/10.1002/jrs.1569.
[13] Zhang, R., Wang, Y., Zhao, X., Jia, J., Liu, C. & Min, Y. (2020). Structure and viscosity of molten CaO–SiO2–FexO slag during the early period of basic oxygen steelmaking. Metallurgical and Materials Transactions B. 51(5), 2021-2029. https://doi.org/10.1007/s11663-020-01888-8.
[14] Jung, S. S. & Sohn, I. (2014). Crystallization control for remediation of an FetO-rich CaO–SiO2–Al2O3–MgO EAF waste slag. Environmental Science & Technology. 48(3), 1886-1892.
[15] Li, T., Zhao, C., Sun, C., Song, S., & Wang, Q. (2020). Roles of MgO and Al2O3 in viscous and structural behavior of blast furnace primary slag with C/S=1.4. Metallurgical and Materials Transactions B. 51(6), 2724-2734. https://doi.org/10.1007/s11663-020-01980-z.
[16] Duan, R.G., Liang, K.M. & Gu, S.R. (1998). Effect of Na⁺ ion on the structure of 27CaO·12Al2O3·61SiO2 glass. Materials Chemistry and Physics. 57(1), 92-94. https://doi.org/10.1016/S0254-0584(98)00207-7.
[17] Stoch, P., Goj, P., Ciecińska, M., Jeleń, P., Błachowski, A., Stoch, A. & Krakowiak, I. (2020). Influence of aluminum on structural properties of iron–polyphosphate glasses. Ceramics International. 46(11), 19146-19157. https://doi.org/10.1016/j.ceramint.2020.04.250.
[18] Stoch, P., Stoch, A., Ciecinska, M., Krakowiak, I., & Sitarz, M. (2016). Structure of phosphate and iron–phosphate glasses by DFT calculations and FTIR/Raman spectroscopy. Journal of Non-Crystalline Solids. 450: 48-60. DOI: 10.1016/j.jnoncrysol.2016.07.027.
[19] Goj, P., Wajda, A. & Stoch, P. (2021). Raman imaging as a useful tool to describe crystallization of aluminum/iron-containing polyphosphate glasses. Journal of the European Ceramic Society. 41(8), 4572-4583. https://doi.org/10.1016/j.jeurceramsoc.2021.03.028.
[20] Sun, Y. & Zhang, Z. (2015). Structural roles of boron and silicon in the CaO–SiO2–B2O3 glasses using FTIR, Raman, and NMR spectroscopy. Metallurgical and Materials Transactions B. 46(4), 1549-1554. https://doi.org/10.1007/s11663-015-0374-2.
[21] Park, Y. & Min, D.J. (2017). A structural study on the foaming behavior of CaO–SiO2–Mo (Mo = MgO, FeO, or Al2O3) ternary slag system. Metallurgical and Materials Transactions B. 48(6), 3038-3046. https://doi.org/10.1007/s11663-017-1079-5.
[22] Wu, T., Zhang, Y., Yuan, F. & An, Z. (2018). Effects of the Cr2O3 content on the viscosity of CaO–SiO2–10 pct Al2O3–Cr2O3 quaternary slag. Metallurgical and Materials Transactions B. 49(4), 1719-1731. https://doi.org/10.1007/s11663-018-1258-z.
[23] Fowler, B.O., Markovic, M. & Brown, W.E. (1993). Octacalcium phosphate. 3. Infrared and Raman vibrational spectra. Chemistry of Materials. 5(10), 1417-1423.
[24] Ding, J., Chen, Y., Chen, W., Hu, L. & Boulon, G. (2012). Effect of P2O5 addition on the structural and spectroscopic properties of sodium aluminosilicate glass. Chinese Optics Letters. 10(7), 071602-071602.
[25] Silva, A. M. B., Correia, R. N., Oliveira, J. M. M. & Fernandes, M. H. V. (2010). Structural characterization of TiO2–P2O5–CaO glasses by spectroscopy. Journal of the European Ceramic Society. 30(6), 1253-1258. https://doi.org/10.1016/j.jeurceramsoc.2009.11.001.
[26] Zhang, R., Min, Y., Wang, Y., Zhao, X. & Liu, C. (2020). Structural evolution of molten slag during the early stage of basic oxygen steelmaking. ISIJ International. 60(2), 212-219. https://doi.org/10.2355/isijinternational.ISIJINT-2019-413.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Archives of Foundry Engineering
This work is licensed under a Creative Commons Attribution 4.0 International License.
