ORALS

SESSION: IronFriAM-R8	Usui International Symposium on Advanced Sustainable Iron and Steel Making (7th Intl. Symp. on Advanced Sustainable Iron and Steel Making)
Fri Oct, 25 2019 / Room: Ambrosia B (77/RF)
Session Chairs: Masaaki Naito; Oleg Ostrovski; Session Monitor: TBA

11:20: [IronFriAM01] Plenary
Gaseous Reduction of Iron Ore Agglomerates --- Reaction Behavior and Reaction Models
Tateo Usui¹ ; Masaaki Naito² ; Hirotoshi Kawabata³ ; Hideki Ono⁴ ; Hirokazu Konishi³ ; Paulo Assis⁵ ; ¹Osaka University, Ibaraki, Japan; ²Nippon Steel Technology Corporation, Futtsu, Japan; ³Osaka University, Suita, Japan; ⁴University of Toyama, Toyama, Japan; ⁵UFOP, Ouro Preto, Brazil;
Paper Id: 437 [Abstract]

Gaseous reduction behavior of iron oxide pellets and iron ore sinter with CO and H₂ were studied experimentally. In reaction models for gaseous reduction of iron ore agglomerates, the formations of both unreacted-core shrinking (UCS) model for one interface and UCS model for three interfaces and the developments of multi-stage zone-reaction models without and with considering solid-state diffusion are summarized; these models were used mainly for pellets but sometimes used for sinter. UCS model for six interfaces in consideration of quaternary calcium ferrite reduction process was newly developed for sinter. Comparisons of these reaction models for pellets and sinter were carried out by using experimental data on gaseous reduction of these iron ore agglomerates.

References:
1 T. Usui, M. Naito, T. Murayama and Z. Morita: Kinetic Analysis on Gaseous Reduction of Agglomerates, Part 1, Reaction Models for Gaseous Reduction of Agglomerates (in Japanese), Tetsu-to-Hagané, 80 (1994), 431-439.

2 T. Usui, M. Ohmi, M. Naito, H. Kamiya, Y. Oshima and Z. Morita: Kinetic Analyses on the Rate of Gaseous Reduction of Single Particles and Packed Beds of Iron Ore Agglomerates, Proceedings of The Julian Szekely Memorial Symposium on Materials Processing, ed. by H. Y. Sohn, J. W. Evans and D. Apelian, (October, 1997, Boston, Massachusetts, U.S.A.), 67-80, TMS.

3 M. Ohmi, T. Usui, M. Naito and Y. Minamide: Experimental Study of the Resistance Due to the Rate of Gas Flow on the Hydrogen Reduction of an Iron Oxide Pellet, Tetsu-to-Hagané (in Japanese), 67 (1981), 1943-1951; Trans. ISIJ (Transactions of the Iron and Steel Institute of Japan), 23 (1983), 81-89

4 M. Ohmi and T. Usui: Study on the Rate of Reduction of Single Iron Oxide Pellet with Hydrogen (in Japanese), Tetsu-to-Hagané, 59 (1973), 1888-1901; On the Unreacted-core Shrinking Model for Reduction of a Single Hematite Pellet with Hydrogen, Trans. ISIJ, 16 (1976), 77-84.

5 M. Ohmi, M. Naito and T. Usui: Applicability of Three Interface Model to the Analysis of Reduction Rate of Iron Oxide Pellets with Hydrogen, Technology Reports of the Osaka University, 34 (1984), No.1743, 19-27.

6 T. Usui, M. Ohmi and E. Yamamura: Analysis of Rate of Hydrogen Reduction of Porous Wustite Pellets Basing on Zone-reaction Models, Tetsu-to-Hagané (in Japanese), 72 (1986), 1263-1270; ISIJ International, 30 (1990), 347-355.

7 M. Ohmi, M. Naito and T. Usui: Multi-stage Zone-reaction Model for the Gaseous Reduction of Porous Hematite Pellets (in Japanese), Tetsu-to-Hagané, 68 (1982), 592- 601.

8 M. Ohmi and T. Usui: Improved Theory on the Rate of Reduction of Single Particles and Fixed Beds of Iron Oxide Pellets with Hydrogen, Trans. ISIJ, 22 (1982), 66-74.

9 M. Ohmi, M. Naito and T. Usui: Kinetic Analysis of Hydrogen Reduction of Various Hematite Pellets on the Basis of the Multi-stage Zone-reaction Models (in Japanese), Tetsu-to-Hagané, 69 (1983), 546-555.

10 M. Ohmi, M. Naito and T. Usui: Effects of Various Factors on the Reduction Rate of Hematite Pellets with Hydrogen (in Japanese), Tetsu-to-Hagané, 68 (1982), 1503-1512.

11 M. Ohmi, M. Naito and T. Usui: Multi-stage Zone-reaction Model with Solid-state Diffusion for the Hydrogen Reduction of Porous Hematite Pellets (in Japanese), Tetsu-to-Hagané, 69 (1983), 363-370.

12 T. Usui, M. Ohmi, S. Hirashima and N. Kitagawa: Kinetic Analysis on the Rate of Stepwise Reduction of a Single Sinter with CO-CO2-N2 Gas Mixture (in Japanese), Tetsu-to-Hagané, 73 (1987), 1956-1963.

13 T. Usui, M. Ohmi, S. Kaneda, M. Ohmasa and Z. Morita: Re-examination of Method of Kinetic Analysis on the Rate of Stepwise Reduction of a Single Sinter Particle with CO-CO₂-N₂ Gas Mixture, ISIJ International, 31 (1991), 425-433.

14 T. Usui, M. Ohmi, N. Kitagawa, S. Kaneda, H. Kawabata and Z. Morita: Change of Sinter Minerals and Final Fractional Reduction in the Reduction Stage from Hematite to Magnetite with CO-CO₂-N₂ Gas Mixture (in Japanese), Tetsu-to-Hagané, 77 (1991), 1251-1258.

15 T. Usui, H. Kawabata, T. Fujimori, I. Fukuda and Z. Morita: Influence of CO Ratio and Reduction Temperature upon the Reducibility of Calcium Ferrite in Sinter in the Initial Stage of Reduction with CO-CO₂-N₂ Gas Mixture (in Japanese), Tetsu-to-Hagané, 78 (1992), 982-989.

16 H. Ono-Nakazato, Y. Tsubone, Y. Takaki and T. Usui: Measurement of Hydrogen Reduction Rates of FeO in 2FeO.SiO₂ and CaO.FeO.SiO₂ (in Japanese), Tetsu-to-Hagané, 87 (2001), 320-326.

17 T. Usui, Y. Nakamuro, M. Nishi, M. Naito, H. Ono and Paulo S. Assis: Gaseous Reduction Model for Sinter in Consideration of Calcium Ferrite Reaction Process (Unreacted-core Shrinking Model for Six Interfaces), Tetsu-to-Hagané (in Japanese), 100 (2014), 294-301; ISIJ International, 55 (2015), 1617-1624.

18 T. Murayama, T. Usui, M. Naito and Y. Ono: Kinetic Analysis on Gaseous Reduction of Agglomerates, Part 2, Rate Parameters Included in the Mathematical Model for Gaseous Reduction of Agglomerates (in Japanese), Tetsu-to-Hagané, 80 (1994), 493-500.

19 M. Naito, T. Murayama and T. Usui: Kinetic Analysis on Gaseous Reduction of Agglomerates, Part 3, Application of Gaseous Reduction Models for Agglomerates to Blast Furnace Analysis (in Japanese), Tetsu-to-Hagané, 80 (1994), 581-586.

20 T. Usui, H. Konishi, K. Ichikawa, H. Ono, H. Kawabata, Francisco B. Pena, Matheus H. Souza, Alexandre A. Xavier and Paulo S. Assis: Evaluation of Carbonisation Gas from Coal and Woody Biomass and Reduction Rate of Carbon Composite Pellets, Advances in Materials Science and Engineering, Special Issue on Biomass Materials for Metallurgical Applications, Vol. 2018, Article ID 3807609, (2018), pp.1 – 14.

SESSION: IronFriAM-R8	Usui International Symposium on Advanced Sustainable Iron and Steel Making (7th Intl. Symp. on Advanced Sustainable Iron and Steel Making)
Fri Oct, 25 2019 / Room: Ambrosia B (77/RF)
Session Chairs: Masaaki Naito; Oleg Ostrovski; Session Monitor: TBA

12:10: [IronFriAM03] Invited
Influence of Basicity on Reduction Rate of Iron Oxide
Hirokazu Konishi¹ ; Tateo Usui² ; Hideki Ono³ ; ¹Osaka University, Suita, Japan; ²Osaka University, Ibaraki, Japan; ³University of Toyama, Toyama, Japan;
Paper Id: 273 [Abstract]

Since reducibility of iron oxide in iron ore directly affects the amount of CO₂ from BF, the enhancement of reducibility of iron oxide is important to reduce CO₂ emissions. The iron ore grade, however, becomes lower year by year. Gangue in iron ore is increasing especially in Al₂O₃. It is observed that the reducibility of sintered iron oxide pellets decreases with the increase of Al₂O₃ content in softening and melting zones over 1373 K in BF. Besides, it is reported that the initial melt formation temperature drops and the amount of melt increases with the increase of Al₂O₃ content [1]. Since molten oxide formed inside sintered iron oxide pellets causes pore occlusion [2], melt formation can affect reducibility in the softening and melting zones. Therefore, it is required to determine the effect of melt on reduction behavior to enhance reducibility of sintered iron oxide pellets. We focused on the reduction behavior and rate of sintered iron oxide pellets on the initial melt formation stage and investigated the effect of melt on the reducibility of iron oxide. The sample was prepared by sintering a mixture of Fe₂O₃, CaO, SiO₂, and Al₂O₃ regent powder. Reduction experiments were carried out to clarify the reduction behavior of a sample from 1273 K to 1473 K and to determine the effect of melt on reduction rate of a sample at 1473 K. The microstructure of a sample was observed by a scanning electron microscope (SEM) and porosity was estimated by an image analysis technique.

References:
[1] H. Konishi, H. Kawabata, H. Ono and E. Takeuchi, Advanced Experimental Mechanics, 1(2016), 251.\n[2] H. Kawabata, Y. Iwaki, H. Konishi, H. Ono, T. Usui, E. Takeuchi, M. Naito, T. Nishimura and K. Higuchi: Journal of JSEM, 16(2016), 20.

SESSION: IronSatAM-R8	Usui International Symposium on Advanced Sustainable Iron and Steel Making (7th Intl. Symp. on Advanced Sustainable Iron and Steel Making)
Sat Oct, 26 2019 / Room: Ambrosia B (77/RF)
Session Chairs: Tateo Usui; Masashi Nakamoto; Session Monitor: TBA

12:10: [IronSatAM03]
Methods to Remove Tramp Elements in Steel for Recycling Ferrous Scraps
Hideki Ono¹ ; Kenji Taguchi² ; Katsuhiro Yamaguchi³ ; Tateo Usui⁴ ; ¹University of Toyama, Toyama, Japan; ²Nippon Stool Corporation, Tokai City, Japan; ³Kobe Steel, Ltd., Kobe City, Japan; ⁴Osaka University, Ibaraki, Japan;
Paper Id: 416 [Abstract]

For preserving the environment and preventing the resource depletion, it is important to extend the allowance of recycling low grade ferrous scraps in iron- and steel-making. It is well known that the recycling also contributes to the reduction of carbon dioxide emissions from iron- and steel-making processes. However, lower grade ferrous scraps generally contain more tramp elements, such as copper and tin. It is difficult to remove such tramp elements from molten iron in iron- and steel-making processes. Highly-concentrated tramp elements negatively affect the quality of steel. For example, it is well known that copper in steel causes hot shortness by concentrated melting of copper onto the surface in hot-rolling process. In this work, the possibilities of removing impurities from molten iron by oxidation and evaporation, which are usual methods in metal refining, are firstly investigated. Of all the elements which are dissolved in molten iron, Cu, Sn Ni, Co, Mo and W are found to be difficult to be removed by such usual methods as oxidation and evaporation [1]. Subsequently, the prospective methods to remove such tramp elements are discussed. Copper, which is one of the most important tramp elements in iron, can be removed by evaporation [2] or by sulfurization [3]. As the other methods, the possibilities to remove copper in molten iron by oxidation [4] and by reduction are considered, and the lowering limits by these methods have been investigated.

References:
[1] H. Ono: CAMP-ISIJ, 31(2018), 40.
[2] H. Ono, K. Taguchi, Y. Seike and T. Usui: ISIJ Inter., 43(2003), 1691.
[3] T. Imai and N.Sano: Tetsu-to-Hagané, 74(1988), 640.
[4] K. Yamaguchi, H. Ono and T. Usui: Tetsu-to-Hagané, 96(2010), 531.