Analysis of possible ways to reduce sulfur content in pig iron

One of the ways to increase the energy efficiency and intensity of blast furnace smelting, especially when using pulverized coal fuel, is to increase the hot strength of coke. In the conditions of OJSC NLMK, an oil additive was introduced into the coal charge to improve the coke quality. At the same time, sulfur content in the coke increases, and, consequently, sulfur content in the cast iron increases as well. In this regard, the task of finding ways to improve the desulfurization of cast iron in blast furnace becomes urgent. The main factors determining the desulfurization of cast iron are slag basicity, content of MgO oxide in it, temperature of the smelting products, and the slag viscosity. The purpose of this work was to compare the efficiency of sulfur removal by increasing the slag basicity and MgO content. On the basis of wellknown equations, an algorithm was developed that allows the problem to be solved. It was established that an increase in MgO content in the slag promotes desulfurization of cast iron to a greater extent than a basicity increase. In addition, an increase in MgO content by 1 % is accompanied by an increase in slag yield by 3.0 – 3.5 kg/t of cast iron. At the same time, an increase in basicity by 0.01 leads to an increase in the slag yield by 4 – 5 kg/t of pig iron. Consequently, reducing the sulfur content in pig iron by increasing the slag basicity requires less heat. In terms of the specific consumption of coke, difference in heat demand is 0.4 – 0.5 kg/t of pig iron. It is shown that with an increase in MgO content in the slag, the slag viscosity at a temperature of 1450 °C increases to a lesser extent than with an increase in basicity.

1. Ishikawa Y., Kase M., Abe Y., Ono K., Sugata M., Nishi T. Influence of post reaction strength of coke on blast furnace operation. Proceedings – Ironmaking Conference. 1983, vol. 42, pp. 357–368.

2. Bertling H. Coal and coke for blast furnaces. ISIJ International. 1999, vol. 39, no. 7, pp. 617–624.

3. Chatterjee A., Prasad H.N. Possibilities of tar addition to coal as a method for improving coke strength. Fuel. 1983, vol. 62, no. 5, pp. 591–600.

4. Gonzalez-Cimas M.J., Patrick J.W., Walker A. Influence of pitch additions on coal carbonization: Coke strength and structural properties. Fuel. 1987, vol. 66, no. 8, pp. 1019–1023.

5. Liziero Ruggio da Silva G., Souza R., Belchior Reis T., Ladeira Lima I., Quintas A., Amorim L., Andretti Sabino Mota M., Brasil Dias Haneiko N. Influence of coal tar addition on coke quality. AISTech Conference Proceedings. 2018, pp. 173–184.

6. Geerdes M., Chaigneau R., Kurunov I., Lingiardi O., Ricketts J. Modern Blast Furnace Ironmaking. 3rd ed. IOS Press, 2015, 228 p.

7. Sharma R., Tiwari H., Banerjee P. Producing high coke strength after reactivity in stamp charged coke making. Coke and Chemistry. 2014, vol. 57, no. 9, pp. 351–358.

8. Stukov M.I., Mamaev M.V., Chernavin A.Yu. etc. New coke for metallurgy. Chernaya Metallurgiya. Byul. in-ta “Chermetinformatsiya”. 2012, no. 5 (1349), pp. 35–37. (In Russ.).

9. Vegman E.F. Domennoe proizvodstvo: Spravochnoe izdanie. V 2-kh t. T. 1. Podgotovka rud i domennyi protsess [Blast-Furnace Production: Reference Book. In 2 vols. Vol. 1. Preparation of Ores and Blast Furnace Process]. Moscow: Metallurgiya, 1989, 496 p. (In Russ.).

10. Tovarovskii I.G., Severnyuk V.V., Lyalyuk V.P. Analiz pokazatelei i protsessov domennoi plavki [Analysis of Indicators and Processes of Blast-Furnace Smelting]. Dnepropetrovsk: Porogi, 2000, 420 p. (In Russ.).

11. Tovarovskij I.G. Melting conditions of low silicon pig iron with low sulphur content. Stal’. 1992, no. 10, pp. 5–8. (In Russ.).

12. Skachko A.S., Togobitskaya D.N., Bel’kova A.I. Influence of charge composition on coefficients of elements distribution between products of blast furnace smelting. Metallurgicheskie protsessy i oborudovanie. 2013, no. 4 (34), pp. 8–15. (In Russ.).

13. Dovgalyuk B.P., Shcherbitskii B.V., Yaroshenko N.M. etc. Improving pig iron quality by slag composition stabilizing. Metallurgicheskaya i gornorudnaya promyshlennost’. 1978, no. 3, pp. 3, 4. (In Russ.).

14. Druzhkov V.G., Prokhorov I.E. Selection of the iron and slag tapping mode from hearth of blast furnaces in modern conditions. Vestnik Magnitogorskogo gosudarstvennogo tekhnicheskogo universiteta im. G.I. Nosova. 2011, no. 4 (36), pp. 9–12. (In Russ.).

15. Shapovalov A.N., Druzhkov V.G. Povyshenie effektivnosti desul’furatsii chuguna [Improvement of the Efficiency of Pig Iron Desulfurization]. Magnitogorsk: MGTU im. G.N. Nosova, 2011, 148 р. (In Russ.).

16. Babich A., Senk D., Gudenau H.W., Mavrommatis K.Th. Ironmaking. Aachen: Institut für Eisenhüttenkunde der RWTH, 2008, 402 p.

17. Andersson A.J., Andersson A.M.T., Jönsson P.G. A study of some elemental distributions between slag and hot metal during tapping of the blast furnace. Steel Research Int. 2004, vol. 75, no. 5, pp. 294–301.

18. Hatch G.G., Chipman J. Sulphur equilibria between iron blast furnace and metal. The Journal of the Minerals, Metals & Materials Society. 1949, vol. 1, pp. 274–284.

19. Loginov V.I., Berin A.L., Lebed’ P.K. etc. Effect of magnesia on desulfurizing power of blast-furnace slags. Metallurgist. 1976, vol. 20, no. 5, pp. 315–317.

20. Pehlke R.D., Fuwa T. Control of sulphur in liquid iron and steel. International Metals Reviews. 1985, vol. 30, no. 1, pp. 125–140.

21. Zuo H.B., Wang C., Xu C.F., Zhang J.L., Zhang T. Effects of MnO on slag viscosity and wetting behaviour between slag and refractory. Ironmaking & Steelmaking. 2016, vol. 43, no. 1, pp. 56–63.

22. Choi J.Y., Kim D.J., Lee H.G. Reaction kinetics of desulfurization of molten pig iron using CaO–SiO2–Al2O3–Na2O slag systems. ISIJ International. 2001, vol. 41, no. 3, pp. 216–224.

23. Spirin N.A., Ipatov Yu.V., Lobanov V.N. etc. Informatsionnye sistemy v metallurgii [Information Systems in Metallurgy]. Ekaterinburg: izd. UGTU – UPI, 2001, 617 p. (In Russ.).

24. Onorin O.P., Spirin N.A., Terent’ev V.L. etc. Komp’yuternye metody modelirovaniya domennogo protsessa [Computer Modeling of Blast Furnace Process]. Ekaterinburg: izd. UGTU – UPI, 2005, 301 p. (In Russ.).

25. Mitropol’skii A.K. Tekhnika statisticheskikh vychislenii. Izd. 2-e [Technique of Statistical Calculations. 2nd ed.]. Moscow: Nauka, 1971, 568 p. (In Russ.).

26. Listopadov V.S., Togobitskaya D.N., Murav’eva I.G. etc. Stabilization of slag mode of blast-furnace smelting in the operating conditions of BF No. 9 of JSC “ARSELORMITTAL KRIVOY ROG” on a multicomponent charge. Chernaya Metallurgiya. Byul. in-ta “Chermetinformatsiya”. 2008, no. 8 (1304), pp. 14–20. (In Russ.).

27. Eyring H., Yenderson D., Ree T. Thermodynamic and transport properties of liquids. Progress in Int. Research on Thermodynamic and Transport Properties. 1962, pp. 340–351.

28. Roberto de Oliveira J., Cristo Clem de Oliveira H., Gambarine Soares S. etc. Comparative study of hot metal desulfurization mixtures. AISTech Proceedings. 2018, pp. 1034–1042.

29. Izyumskii N.N., Gordon Ya.M., Tretyak A.A. Mathematical model and system for stabilizing the slag operating mode of blast furnace. Chernaya Metallurgiya. Byul. in-ta “Chermetinformatsiya”. 2017, no. 11, pp. 46–52. (In Russ.).

30. Gimmel’farb A.A., Kotov K.I. Protsessy vosstanovleniya i shlakoobrazovaniya v domennykh pechakh [Reduction and Slagging Processes in Blast furnace]. Moscow: Metallurgiya, 1982, 328 p.

31. (In Russ.).

32. Sukhareva S.P., Gileva L.Yu., Zagainov S.A. Analysis and forecast block for slag mode of blast furnace smelting. Izvestiya. Ferrous Metallurgy. 2004, no. 3, pp. 75, 76. (In Russ.).

33. Voskoboinikov V.G., Dunaev N.E., Mikhalevich A.G. etc. Svoistva zhidkikh domennykh shlakov [Properties of Liquid Blast Furnace Slags]. Moscow: Metallurgiya, 1975, 184 p. (In Russ.).

34. Yan Z., Pang Z., Lv X.W., Qiu G., Bai C. Effect of TiO2 on the viscous behavior of high alumina blast furnace slag. Minerals, Metals and Materials Series. 2018, vol. F10, pp. 725–733.