The Mechanism of the Reduction of Hematite-Magnetite Concentrate by Graphite-Calcium Carbonate Mixture in Hoganas Process

Document Type : Original Articles

Authors

Seyyed Mohammad Ali Haghi ¹

Ahad Zabett ²

Mostafa Mirjalili ²

¹ Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad

² Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad.

10.22067/jmme.2021.58727.0

Abstract

In this study, the mechanism of reduction of hematite-magnetite concentrate (HMC) by graphite-calcium carbonate reductant mixture at 1000 °C was investigated. The initial and middle stages of the reduction process (up to 63%) are mainly affected by the heat transfer inside the crucible. In the middle and final stages of the reduction process, the gaseous diffusion to the FeO-Fe reaction interface and the carbon gasification by CO2 jointly controlled this progress. The reduction rate was relatively slow below the temperature at which the carbon gasification by CO2 commences. According to the XRD analysis, prior to the carbon gasification, the metallic iron was not found. The reduction of the HMC hollow cylinder proceeded topochemically mainly from the outer surface. The SEM micrographs indicated the formation of sintered iron whisker.

Keywords

Reduction

Graphite–Calcium Carbonate Mixture

Mass Transfer

Carbon Gasification

Kinetics

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References

1.  

   1.       Ghosh, A., "Kinetics of reduction of iron oxide in mixtures of oxide and carbon: a critical appraisal", Transactions of the Indian Institute of Metals, Vol. 66, pp. 71-77, (2013).

   2. Sah, R. and Dutta, S. K., "Kinetic studies of iron ore–coal composite pellet reduction by TG–DTA," Transactions of the Indian Institute of Metals, 64, NO. 6, pp. 583-591, (2011).
   3. Khattoi, S. C. and Roy, G. G., "Reduction efficiency of iron ore–coal composite pellets in tunnel kiln for sponge iron production," Transactions of the Indian Institute of Metals, 68, NO. 5, pp. 683-692, (2015).
   4. Havemann, H. A., "Direct Iron Ore Reduction for Asia," pp. 260-272, (1959).
   5. Eriksson, K. and Larsson, M., "Energy survey of the sponge iron process," Department of Chemical Engineering, Lund Institute of Technology, Lund, Sweden, (2005).
   6. Dutta, S. K., "Kinetics and Mechanism of Iron Ore-Coal Composite Pellets Reduction," Transactions of the Indian Institute of Metals, 58, NO. 5, pp. 801-808, (2005).

   7.       Mishra, S. and Roy, G.G., "Effect of amount of carbon on the reduction efficiency of iron ore-coal composite pellets in multi-layer bed rotary hearth furnace (RHF)," Metallurgical and Materials Transactions B, Vol. 47B, pp. 2347-2356, (2016).

   8. Sun, K. and Lu, W.-K., "Mathematical modeling of the kinetics of carbothermic reduction of iron oxides in ore-coal composite pellets," Metallurgical and Materials Transactions B, 40B, pp. 91-103, (2009).
   9. Fortini, O.M., and Fruehan, R.J., "Rate of reduction of ore-carbon composites:part II. modeling of reduction in extended composites," Metallurgical and Materials Transactions B, 36B, pp. 709-717, (2005).
   10. Sun, S. and Lu, W.-K., "A theoritical investigation of kinetics and mechanisms of iron ore reduction in an ore/coal composite," ISIJ International, 39, NO. 2, pp. 123-129, (1999).
   11. Chowdhury, G.M., Murmu, C.S., Roy, S.K. and Roy, G.G., "Some studies to establish the reaction mechanism for the reduction of iron ore-graphite composite pellets in a packed bed reactor," Steel Research International, 81, NO. 11, pp. 925-931, (2011).
   12. Mookherjee, S., Ray, H.S. and Mukherjee, A., "Thermogravimetric studies on the reduction of hematite ore fines by a surrounding layer of coal or char fines. part 1. isothermal kinetic studies," Thermochimica Acta, 95, pp. 235-246, (1985).
   13. Mookherjee, S., Ray, H.S. and Mukherjee, A., "Thermogravimetric studies on the reduction of hematite ore fines by a surrounding layer of coal or char fines. part 2. non-isothermal kinetic studies," Thermochimica Acta, 95, pp. 247-256, (1985).
   14. مختاری، م.،"مطالعه متغیرهای موثر بر فرایندHoganas در تولید آهن اسفنجی به روش احیا مستقیم توسط زغال"، پایان­ نامه کارشناسی ارشد، دانشگاه فردوسی مشهد، (1392).
   15. شکیبا، ع.، زارع، م.، همتی، م. ح.، وحدتی خاکی، ج. و ضابط، ا "بررسی تأثیر افزودن کاتالیست های فلزی بر روند احیای اکسیدآهن هماتیتی توسط زغال سنگ کک نشو به روش لایه ای"، ششمین همایش مشترک انجمن مهندسین متالورژی و انجمن علمی ریخته گری ایران، (1391).
   16. Fruehan, R.J., "The rate of reduction of iron oxides by carbon," Metallurgical and Materials Transactions B, 8, NO. 1, pp. 279-286, (1977).
   17. Rao, Y., "The kinetics of reduction of hematite by carbon," Metallurgical Transactions, 2, NO. 5, p. 1439–1447, (1971).
   18. Casal, M., Díez, M., Alvarez, R. and Barriocanal, C., "Primary tar of different coking coal ranks," International Journal of Coal Geology, 76, NO. 3, pp. 237-242, (2008).
   19. Liu, G.S., Strezov, V., Lucas, J.A. and Wibberley, L.J., "Thermal investigations of direct iron ore reduction with coal," Thermochimica Acta, 410, pp. 133-140, (2004).
   20. Sohn, I. and Fruehan, R.J., "The reduction of iron oxides by volatiles in a rotary hearth furnace process: part I. the role and kinetics of volatile reduction," Metallurgical and Materials Transactions B, 36B, pp. 605-612, (2005).
   21. Plaul, F.J., Böhm, C. and Schenk, J.L., "Fluidized-bed technology for the production of iron products for steelmaking," The Journal of The Southern African Institute of Mining and Metallurgy, 108, pp. 121-128, (2009).
   22. Rao, T., "Kinetics of Calcium Carbonate Decomposition," Chemical Engineering & Technology, 19, pp. 373-377, (1996).
   23. Khawam, A. and Flanagan, D.R., "Solid-state kinetic models: basics and mathematical fundamentals," The Journal of Physical Chemistry B, 110, NO. 35, p. 17315–17328, (2006).
   24. hmed, H.M., Viswanathan, N.N. and Björkman B., "Isothermal reduction kinetics of self-reducing mixtures," Steelmak, pp. 1-10, (2016).
   25. Lewis, J., Thermal Gas Reactions of Graphite, Ch. 4, Modern Aspects of Graphite Technology, Academic Press, London, (1970).
   26. Walker, P.L., Shelef, Jr.M. and Anderson, R.A., "Catalysis of Carbon Gasification" Chemistry and Physics of Carbon, Marcel Dekker Inc., New York, (1968).
   27. Ghosh, A. and Ghosh, S., A Textbook of Metallurgical Kinetics, PHI Learning, 2014.
   28. Seaton, C.E., James, S., Foster and Velasco, J., "Structural changes occurring during reduction of hematite and magnetite pellets containing coal char," Transaction of the Iron and Steel Institue of Japan, 23, pp. 497-503, (1983).