Abstract
This paper examines the main processes of ladle desulfurization of cast iron, which include Kanbara Reactor (KR), MMI ("Ukraine-Desmag") and Co-injection; describes the equipment set-up used, desulfurization reactions, as well as advantages and disadvantages of each process. The authors compare three different processes guided by the following parameters: processing time, consumption of reagents, iron loss, heat loss, equipment wear. For convenience, relative values of the parameters are given (the minimum value is assumed to be nominal, i.e. one). Comparison of the cast iron ladle desulfurization processes based on the final parameter values showed that the Co-injection process (the co-injection of magnesium granules and lime in the nitrogen stream) has the most rational – i.e. minimal – value. This process is adopted by numerous steel makers around the world, including MMK PJSC. A new iron desulfurization unit (IDU) was built and is now in operation at MMK’s BOF site. The paper provides the IDU characteristics. During the adoption phase, probably significant linear dependencies were established of the desulfurization degree on the nitrogen injection time, the total weight of the reagents, the weight ratio of fluidized lime and magnesium. The iron desulfurization degree varied within a wide range of 50 to 87.5% and was on average 77.3%. The co-injection process is the most popular cast iron ladle desulfurization process in today’s steel industry. It is also implemented at MMK PJSC. The iron desulfurization unit of the BOF shop removes an average of 83.5% of sulfur, and its residual concentration is 0.003% (data for 15 months).
Keywords
Liquid iron, ladle, desulfurization, processes, comparison, industrial implementation.
1. Grigorovich K.V. Modern low-carbon microalloyed steels: Ways to develop the technology and metallurgical quality parameters. Sbornik trudov XIII Mezhdunarodnogo kongressa staleplavilshchikov [Proceedings of the 13th International Congress of Steelmakers]. Polevskoy: Ezaprint, 2014, pp. 28‒33. (In Russ.)
2. Efron L.I. Metallovedenie v “bolshoy” metallurgii. Trubnye stali [Metal science as part of "big" metallurgy. Pipe steel]. Moscow: Metallurgizdat, 2012, 696 p. (In Russ.)
3. Kolesnikov Yu.A., Budanov B.A, Stolyarov A.M. Metallurgicheskie tekhnologii v vysokoproizvoditelnom konverternom tsekhe: uchebnoe posobie [Metallurgical technologies in a high-performance converter shop: Learner’s guide]. Magnitogorsk: Publishing House of Nosov Magnitogorsk State Technical University, 2015, 379 p. (In Russ.)
4. Bigeev V.A., Agapitov E.B., Erofeev M.M. et al. The results of steel processing in a ladle furnace with hollow electrodes. Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta im. G.I. Nosov [Vestnik of Nosov Magnitogorsk State Technical University], 2007, no. 1, pp. 36‒38. (In Russ.)
5. Frank Schrama, Bart van der Berg, Guido van Hattum. A comparison of the leading hot metal desulfurization methods. Teoriya i tekhnologiya metallurgicheskogo proizvodstva [Theory and technology of metallurgical production], 2015, no. 1 (16), pp. 38-43. (In Russ.)
6. Ushakov S.N., Avramenko V.A., Bigeev V.A., Stolyarov A.M., Potapova M.V. Production of low-sulfur pipe steel with ladle desulfurization of cast iron. Metallurg [Metallurgist], 2017, no. 11, pp. 47–50. (In Russ.)
7. Kolokoltsev V.M., Kotok A.P., Dolbilov K.A. Problems of sulfur in cast alloys. Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta im. G.I. Nosov [Vestnik of Nosov Magnitogorsk State Technical University], 2014, no. 3, pp. 30‒32. https: // doi.org/10.18503/1995-2732-2014-3-30-32. (In Russ.)
8. M.G. Dumitru, A. Ioana, N. Constantin. Steel refining possibilities in LF. IOP Conf. Series: Materials Science and Engineering, 294 (2018) 012018. doi:10.1088/1757-899X/294/1/012018.
9. Sanjeev Manocha, François Ponchon. Management of lime in steel. Metals 2018, 8(9), 686; https://doi.org/10.3390/met8090686.
10. E. Ardelean, M. Ardelean, A. Socalici. Researches on the influence of slag addition and secondary treatment duration on steel quality. IOP Conf. Series: Materials Science and Engineering, 477 (2019) 012010. doi:10.1088/1757-899X/477/1/012010.
11. Shengli Wu, Laixin Wang, Yanan Lu, Kai Gu. Improving the desulphurization in COREX-3000 process by the optimization of chemical compositions of slag. ISIJ International. doi.org/10.2355/isijinternational.ISIJINT-2018-427.
12. Qing Cao, Laurentiu Nastac, April Pitts-Baggett, Qiulin Yu. Numerical investigation of desulfurization kinetics in gas-stirred ladles by a quick modeling analysis approach. Metallurgical and Materials Transactions B. June 2018, vol. 49, no. 3, pp. 988–1002.
13. Suguna Soumya Varanasi, R.K. Pathak, K.K. Sahoo, Venu Madhava Rao More, Dey Santanu, Sankar Reddy Alli. Effect of CaO–Al2O3-based synthetic slag additions on desulphurisation kinetics of ladle furnace refining. Transactions of the Indian Institute of Metals, (2019), pp 1–6.