ORALS

SESSION: IronThuPM2-R8	Usui International Symposium on Advanced Sustainable Iron and Steel Making (7th Intl. Symp. on Advanced Sustainable Iron and Steel Making)
Thu Oct, 24 2019 / Room: Ambrosia B (77/RF)
Session Chairs: Moritoshi Mizutani; Shunsuke Hori; Session Monitor: TBA

16:20: [IronThuPM210] Invited
In-Situ Evaluation for Crack Generation and Propagation Behavior of Iron Ore Burden during Low Temperature Reduction by Applying Acoustic Emission Method
Moritoshi Mizutani¹ ; Tsunehisa Nishimura² ; Takashi Orimoto¹ ; Kenichi Higuchi¹ ; Seiji Nomura¹ ; Koji Saito³ ; Eiki Kasai⁴ ; ¹Nippon Steel Corp., Futtsu, Japan; ²Nippon Steel Corpo., Futtsu, Japan; ³Nippon Steel & Sumitomo Metals Corp., Futtsu City, Japan; ⁴Graduate School of Environmental Studies, Tohoku University, Sendai, Japan;
Paper Id: 21 [Abstract]

Volumetric expansion during low temperature reduction of hematite to magnetite causes disintegration of iron ore burden in the upper part of blast furnace (1). The extent of such a property is generally evaluated by ISO11258/JISM8720 as a Reduction Disintegration Index (RDI) at low temperatures, where test samples are reduced with the constant gas composition at a constant temperature followed by the strength test after cooling. It is difficult, however, to observe detailed behaviors of crack formation during the test operation. Therefore, we have applied an acoustic emission (AE) method for an RDI test equipment (2). AE is an <i>in-situ</i> non-destructive technique that enables detection of the incidences of the generation and propagation of the crack (3)-(6). In a single particle reduction, the sinter emitted a large number of AEs during cooling, and the AE energy of the sinter was higher than that of the pellet. Furthermore, lump ores containing high combined water emitted a large number of AEs during heating. The latter result implies that this method is useful for the evaluation the decrepitation of iron ore lumps. In the packed bed tests, the effective AE signals were obtained against noise probably caused by frictions between the sample and the wave guide. The guide represents the average properties of the iron ore burden. The measurements revealed that thermal energy stress during cooling was higher than during reduction at 823 K for 30 min. The results show that the value of the standard RDI is affected by the cooling operation, which is different from blast furnace conditions. The AE method will be applied as a unique measure to observe real disintegration behaviors of iron ore burden during reduction.

References:
1) T. Inazumi, K. Shinada and M. Kawabe: Tetsu-to-Hagana, 68(1982), 2207.\n2) M. Mizutani, T. Nishimura, T. Orimoto, K. Higuchi, S. Nomura, K. Saito and E. Kasai: ISIJ Int., 58(2018), 1413.\n3) M. Enoki, S. Fujikawa and T. Kishi: Journal of the Japan Institue of Metals, 58(1994), 418.\n4) M. Ohtsu: Research in Nondestructive Evaluation, 6(1995), 169.\n5) K. Ito, H. Kuriki, M. Watanabe, S. Kuroda and M. Enoki: Materials Transactions, 53(2012), 671.\n6) H. Nakamura: Journal of The Japanese Society for Non-Destructive Inspection, 62(2013), 267.

SESSION: IronFriPM2-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: Taichi Murakami; Cyro Takano; Session Monitor: TBA

17:10: [IronFriPM212] Invited
Effect of Iron Ore-Carbon Composite Structure on Phosphorus Content in Reduced Molten Iron and Slag
Taichi Murakami¹ ; Daisuke Maruoka² ; Eiki Kasai¹ ; ¹Graduate School of Environmental Studies, Tohoku University, Sendai, Japan; ²Tohoku University, Sendai, Japan;
Paper Id: 76 [Abstract]

Demand for utilizing iron ore with high phosphorus content is increasing because of the depletion of the resource for high-grade iron ore. Utilization of oolitic hematite with very high phosphorus content [1] and development of the dephosphorization method by reduction and melting of iron ore-carbon composite are the main focus of this paper. It is known that most of phosphorus exists as calcium phosphate in oolitic hematite. It is known that calcium phosphate can reduce to phosphorus gas and moves into metallic iron in iron ore-carbon composites. In this study, the effect of the iron ore layout in composite on dephosphorization behavior is evaluated. Four thin composite samples, using hematite reagent, coke and three compacts of oolitic hematite, were prepared. These samples (thickness=2mm) were then set in the alumina crucible, which is named as the layer sample. The mixing ratio of total carbon to oxygen in iron oxide was 0.8 in molar [2]. For comparison, a uniform mixing composite sample was prepared using oolitic reagent, hematite powders (Ore: Reagent = 2:1) and coke. The sample was heated up to different target temperatures at a heating rate of 0.167°C/s. Phosphorus content in oolitic hematite, reduced iron, and slag was measured by ICP-AES. Phosphorus content in oolitic hematite was 0.78%. After heating up to 1300°C, melted iron and slag were obtained, and phosphorus content in melted iron of the layer sample was estimated at approximately 0.04% while that of the uniform mixing composite was approximately 0.4%.

References:
[1] M.Omran, T.Fabritius, R.Mattila, Powder Technology, 269(2015), 7-14.\n[2] T.Murakami, T.Nishimura, E.Kasai, ISIJ International, 49(2009), 1686-1693.