A STUDY ON THE EXAMINATION OF THE SINTER METALOGRAPHIC STRUCTURE

Abstract

Sintering process is carried out domestic and imported iron ore powders, fluxes (limestone, dolomite etc.), coke dust, metallurgical recycling powders and slag forming agents. The purpose of the sintering process is to produce a charging material with suitable thermal, mechanical, physical and chemical properties that can be fed into the blast furnace. Nowadays, in order to obtain process and operating parameters that will work with the best sinter quality, extensive researches have been made by iron and steel industry. The sinter quality parameters followed by the sinter blend loaded on the sinter strand and then granulated were examined. In the sintering process, the temperature rises to 1450 oC, partially melting between the sinter grains and a series of reactions take place in the sinter matrix to be charged into the blast furnace to produce liquid crude iron. Many different approaches have been used to estimate sinter quality, to explain the effects of iron ore properties and process variables on sintering mechanisms, and to characterize sinter mineralogy of iron ore. We can obtain chemical analysis of the phases by scanning electron microscopy (SEM) technique, but full consistency with images is not always possible and especially SFCA (silico-ferrite of calcium and aluminium) and SFCA-I phases are difficult to distinguish from each other and future studies are required in this field. The mineralogy and microstructure of the sinter plays an important role in determining the physical and metallurgical properties of the iron ore sinter. Mineralogical characterization of sinter phases; it is a complementary tool to conventional physical and metallurgical tests applied to iron ore sinter to evaluate and estimate sinter quality. Measurement techniques used in this study; optical image analysis and X-ray diffraction (XRD), scanning electron microscopy (SEM), energy distribution spectroscopy (EDS), the results from raw data converted to autoquan format will be explained on the new studies on the interpretation of the Rietveld system. Depending on the measurement objectives of each technique, the quantification of the crystal phases, the relationship between the measurement results, the chemical composition of the phases and the relations between the minerals, as well as their advantages and disadvantages will be explained.

Keywords

• Iron ore sinter mineralogy,agglomeration,crystal structure,SFCA,phase chemistry

References

1. [1] Zöll, K., Kahlenberg, V., Krüger, H., & Tropper, P. (2018). Investigations on FCAM-III (Ca2. 38Mg2. 09Fe3+ 10.61 Fe2+ 1.59 Al9.33O36): A new homologue of the aenigmatite structure-type in the system CaO-MgO-Fe2O3-Al2O3. Journal of Solid State Chemistry, 258, 307-319.
2. [2] Hsieh, L.H., & Whiteman, J.A. 1989. Effect of oxygen potential on mineral formation in lime-fluxed iron ore sinter, ISIJ International, vol. 29, no. 8, p. 625- 634.
3. [3] Kama, M., Miyazaki, T., Ito, K., Hida, Y & Sasaki, M. 1984. Morphological analysis of calcium ferrite and hematite in sintered ore. Transactions ISIJ. vol. 24.
4. [4] Liu, D., Loo, C. E., & Evans, G. 2016. Flow characteristics of the molten mix generated during iron ore sintering. International Journal of Mineral Processing, 149, 56-68.
5. [5] Pownceby, M.I. & Patrick, T.R.C. 2000. Stability of SFC (silico-ferrite of calcium): solid solution limits, thermal stability and selected phase relationships within the Fe2O3-CaOSiO2 (FCS) system. European Journal of Mineralogy. vol. 12. p. 455-468.
6. [6] Young, R.A. 1993. The Rietveld method, International Union Crystallography, Oxford University Press, Oxford, 298p.
7. [7] Dawson, P.R, Ostwald, J. & Hayes, K.M. 1984. The influence of sintering temperature profile on the mineralogy and properties of iron ore sinters, Proc. Aust. Inst. of Mining and Metallurgy, p. 103-169.
8. [8] Wei, R., Lv, X., Yang, M., Xu, J., & You, Z. 2018. Improving the property of calcium ferrite using a sonochemical method. Ultrasonics sonochemistry, 43, 110-113.

9. [9] Ding, X., & Guo, X. M. 2016. Study of SiO2 involved in the formation process of silico-ferrite of calcium (SFC) by solid-state reactions. International Journal of Mineral Processing, 149, 69-77.
10. [10] De Magalhaes, M.S. & Brandao, P.R.G. 2003. Microstructures of industrial sinters from Quadrilatero Ferrifero’s iron ores, Minerals Engineering, Elsevier,p.1251.
11. [11] Scarlett, N.V.Y., Pownceby, M.I., Madsen, I.C. & Christensen, A.N. 2004. Reaction sequences in the formation of silico-ferrites of calcium and aluminum in iron ore sinter, Metallurgical and materials transactions B, vol. 35B, p. 929- 936.
12. [12] Webster, N. A., Churchill, J. G., Tufaile, F., Pownceby, M. I., Manuel, J. R., & Kimpton, J. A. 2016. Fundamentals of silico-ferrite of calcium and aluminium (SFCA) and SFCA-I iron ore sinter bonding phase formation: effects of titanomagnetite-based ironsand and titanium addition. ISIJ International, 56(10), 1715-1722.
13. [13] Koryttseva, A., Webster, N. A., Pownceby, M. I., & Navrotsky, A. 2017. Thermodynamic stability of SFCA (silico‐ferrite of calcium and aluminum) and SFCA‐I phases. Journal of the American Ceramic Society, 100(8), 3646-3651.
14. [14] CaI, B., Watanabe, T., Kamijo, C., Susa, M., & Hayashi, M. 2018. Comparison between Reducibilities of Columnar Silico-ferrite of Calcium and Aluminum (SFCA) Covered with Slag and Acicular SFCA with Fine Pores. ISIJ International, 58(4), 642-651.
15. [15] Webster, N. A., Pownceby, M. I., & Pattel, R. 2017. Fundamentals of silico-ferrite of calcium and aluminium (SFCA) and SFCA-I iron ore sinter bonding phase formation: effects of mill scale addition. Powder Diffraction, 32(S2), S85-S89.
16. [16] Cores, A., Babich, A., Muñiz, M., Ferreira, S & Mochon, J. 2010. The influence of different iron ores mixtures composition on the quality of sinter, ISIJ International, vol. 50 , no. 8, p. 1089-1098.
17. [17] Pownceby, M.I. & Clout, J.M.F. 2003. Importance of fine iron ore chemical composition and high temperature phase relations, applications to iron ore sintering and pelletizing. Mineral Processing and Extractive Metallurgy, vol. 112, p. 44-51.
18. [18] Bristow, N.J., & Waters, A.G. 1991. Role of SFCA in promoting high-temperature reduction properties of iron ore sinters. Mineral Processing & Extractive Metallurgy, Section C. vol. 100. p. 1-4.
19. [19] Mumme, W.G., Clout, J.M.F. & Gable, R.W. 1988. The crystal structure of SFCA-I Ca3.18Fe3+ 14.66Al1.34Fe2+ 0.82O28, a homologue of the aenigmatite structure type, and new structure type, and new crystal refinements of -CCF, Ca2.99Fe3+ 14.30Fe2+ 0.55O25 and Mg-free SFCA, Ca2.45Fe3+ 9.04Al1.74Fe2+ 0.16Si0.6O20. Neues Jahrbuch Miner. Abh, vol. 173, no. 1, p. 93-117.
20. [20] Mumme W.G. 2003. The crystal structure of SFCA-II, Ca5.1Al9.3Fe3+ 14.30Fe2+ 0.55O48, a homologue of the aenigmatite structure type, and new structure type, and new crystal refinement of SFCA, Ca2Al5Fe7O20. Implications for the nature of the “ternary-phase solid-solution previously reported in the CaO-Al2O3-iron oxide system. Neues Jahrbuch Miner. Abh., vol. 178, no. 3, p.307-335.
21. [21] Bhagat R.P., Chattoray, U. & SIL, S.K. 2006. Porosity of sinter and its relation with the sintering indices, ISIJ International, vol. 46, no. 11, p. 1728-1730.
22. [22] T. van den Berg and J.P.R. de Villiers: T. I. Min. Metall. C, 2009, vol. 118, pp. 214–21.
23. [23] Sasaki, M., Hida, Y.,1982. Considerations on the properties of sinter from the point of sintering reaction. Tetsu to Haganè 68, 563–571.
24. [24] McAndrew, J., Clout, J.M.F., 1993. The nature of SFCA and its importance as a bonding phase in iron ore sinter. In: Proceedings of the 4th China–Australia Symposium on the Technology of Feed Preparation for Ironmaking, Dampier, pp. 1–15.
25. [25] Chaigneau, R. 1994. Fluxed sinter formation and SFCA reduction under Simulated Conditions, PhD Thesis, Delft University Press, p. 12-28.
26. [26] Liles, D. C., de Villiers, J. P., & Kahlenberg, V. 2016. Refinement of iron ore sinter phases: a silico-ferrite of calcium and aluminium (SFCA) and an Al-free SFC, and the effect on phase quantification by X-ray diffraction. Mineralogy and Petrology, 110(1), 141-147.
27. [27] Bölükbaşi Ö.S. (2015). Demir Cevheri Sinterleme Prosesinde ideal SFCA (siliko-ferrit-kalsiyum-alüminyum) Faz Yapısının Belirlenmesi, TÜBİTAK Araştırması (1059B191401374) 1. Rapor Sonucu.
28. [28] Ishikawa, Y., Shimomura, Y., Sasaki, M & Toda, H. 1983. Improvement of sinter quality based on the mineralogical properties of ores. Ironmaking Proceedings. vol. 42. p. 17-29.
29. [29] Hancart, J., Leroy, V., & Bragard, A. 1967. A study of the phases present in blast furnace sinter. Some considerations on the mechanism of their formation. CNRM Metall. Report, 3-7.
30. [30] Patrick, T. R., & Pownceby, M. I. 2002. Stability of silico-ferrite of calcium and aluminum (SFCA) in air-solid solution limits between 1240° C and 1390° C and phase relationships within the Fe2 O3-CaO-Al2O3-SiO2 (FCAS) system. Metallurgical and Materials Transactions B, 33(1), 79-89.
31. [31] Garbers-Craig, P. C., & JMA, J. W. 2003. The influence of increased air flow on the spatial variation of iron sinter quality. Journal of the Southern African Institute of Mining and Metallurgy, 103(10), 645-650.
32. [32] Wei, R., Lv, X., Yang, M., Xu, J., & You, Z. (2018). Improving the property of calcium ferrite using a sonochemical method. Ultrasonics sonochemistry, 43, 110-113.
33. [33] Scarlett, N.V.Y., Pownceby, M.I., Madsen, I.C, & Christensen, A.N. 2004. In situ X-ray diffraction analysis of iron ore sinter, Journal of Applied crystallography, vol. 37, no. 3, p. 362-368.
34. [34] Kalenga, M.K. 2007. Investigation into the influence of magnesia content, alumina content, basicity and ignition temperature on the mineralogy and properties of iron sinter, MSc Thesis, University of Pretoria, p.25-27.