Effects of Magnetic Field on Reduction of CaOContaining Iron Oxides

doi:10.11900/0412.1961.2018.00492

Acta Metall Sin

2019, Vol. 55

Issue (3): 410-416 DOI: 10.11900/0412.1961.2018.00492

Current Issue | Archive | Adv Search

Effects of Magnetic Field on Reduction of CaOContaining Iron Oxides

Yongli JIN^1,²,Hai YU²,Jieyu ZHANG¹,Zengwu ZHAO³(

)

1. School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
2. School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China
3. Inner Mongolia Key Laboratory for Utilization of Bayan Obo Multi-Metallic Resources, Inner Mongolia University of Science and Technology, Baotou 014010, China

Cite this article:

Yongli JIN,Hai YU,Jieyu ZHANG,Zengwu ZHAO. Effects of Magnetic Field on Reduction of CaOContaining Iron Oxides. Acta Metall Sin, 2019, 55(3): 410-416.

Download:

HTML

PDF(11025KB)
Export: BibTeX | EndNote (RIS)

Abstract

Iron ore direct reduction is an attractive alternative route for effective use of low-grade complex symbiotic iron ore resources as well as reducing CO₂ emissions from steel making. In this process, solid iron ore pellets are converted to so-called direct reduced iron with a reduction gas such as CO and H₂. However, the slow reduction rate of iron oxides at lower temperatures has restricted the productivity of direct reduced iron. We have been studying the use of a magnetic field to enhance the direct reduction process, and investigating the influences of the magnetic field on the reduction of iron oxides and morphology of direct reduced iron. Iron ores are rich in iron oxides and also contain other oxides. The presence of other oxides, for instance CaO, is likely to interact with iron oxides during reduction so as to enhance the reduction rate by varying the lattice structure of solid iron oxides and gas/solid mass transport. In the present work, the effects of magnetic field on the reduction of CaO-containing iron oxides were studied. Isothermal reduction of compact samples of pure Fe₂O₃ and 2.5%CaO (mass fraction) containing Fe₂O₃ was carried out at 1073 K under a reaction atmosphere 75%CO+25%CO₂ (volume fraction). A constant magnetic field (B=1.02 T) was applied during reduction to compare with the reaction under a normal condition without a magnetic field applied. The results showed that the magnetic field accelerates the reaction rate of Fe₂O₃ reduction to metallic Fe, and there are no phase compositions change during reduction in a constant magnetic field. The magnetic field promotes the diffusion of Ca in Fe₂O₃+2.5%CaO, and the reduced sample obtained in a magnetic field appears loose and porous. Thermodynamic calculation indicated that the Gibbs free energy of Fe₂O₃ reduction and CaFe₅O₇ phase decomposition is decreased with an interaction of magnetic field, resulting in an increase of the reaction equilibrium constant thus making the reduction of Fe₂O₃ and decomposition of intermediate phase CaFe₅O₇ occur more readily.

Key words: magnetic field direct reduction Fe₂O₃ CaO equilibrium constant

Received: 01 November 2018

ZTFLH:

TF01

Fund: National Natural Science Foundation of China(51464039);National Natural Science Foundation of China(51464040)

	Service

	E-mail this article
	Add to citation manager
	E-mail Alert
	RSS
	（）
	Articles by authors
	Yongli JIN
	Hai YU
	Jieyu ZHANG
	Zengwu ZHAO

URL:

https://www.ams.org.cn/EN/10.11900/0412.1961.2018.00492 OR https://www.ams.org.cn/EN/Y2019/V55/I3/410

Fig.1 Schematic of magnetic field reduction furnace (1—gas cylinder, 2—moisture filter, 3—oxygen filter, 4—mass flow controller, 5—gas mixer, 6—Al₂O₃ work tube with heating elements wrapped around the tube, 7—heat insulation cover, 8—water cooling jacket, 9—permanent magnet, 10—thermocouple, 11—sliding rail for moving heat insulation cover (7) and magnet (9), 12—furnace temperature controller)

Fig.2 Isothermal reduction curves of pure Fe₂O₃ and Fe₂O₃+2.5%CaO systems in a constant magnetic field (CMF) 1.02 T, and under the normal condition (NC) without a magnetic field applied

Fig.3 XRD spectra of Fe₂O₃+2.5%CaO after reduction for various reaction periods in a constant magnetic field 1.02 T (a) and under the normal condition without a magnetic field applied (b)

Table 1 EDS results of points 1~6 in Fig.4 (mass fraction / %)

Fig.4 SEM images of reduced samples for pure Fe₂O₃和Fe₂O₃+2.5%CaO after reduction for various periods in a constant magnetic field 1.02 T, and under the normal condition without a magnetic field applied(a) pure Fe₂O₃, CMF, 20 min (b) Fe₂O₃, NC, 20 min (c) Fe₂O₃+2.5%CaO, CMF, 20 min (d) Fe₂O₃+2.5%CaO, NC, 20 min (e) Fe₂O₃+2.5%CaO, CMF, 60 min (f) Fe₂O₃+2.5%CaO, NC, 60 min

Fig.5 SEM image of Fe₂O₃+2.5%CaO after reduction for 30 min in a constant magnetic field 1.02 T (a) and its element maps of Fe (b), Ca (c) and O (d)

Process	Equation (2)		Equation (3)
	Equation (2)		Equation (3)
	Gibbs free energy J·mol^-1	K	Gibbs free energy J·mol^-1	K
	Gibbs free energy J·mol^-1		Gibbs free energy J·mol^-1

NC	$Δ G ?$ = -3.0720×10⁴	31.299	$Δ G ?$ = -3.4127×10⁵	9.4330×10³
CMF	ΔG^T= -3.1523×10⁴	34.243	ΔG^T= -8.4863×10⁵	1.3531×10⁴

Table 2 Gibbs free energies and equilibrium constants for reactions associated with equations (2) and (3)

[1]	Zhang T A, Yang H, Wei S C, et al. Application of electromagnetic technology in metallurgy [J]. Mater. Rev., 2000, 14(10): 23
[1]	张廷安, 杨欢, 魏世承等. 电磁技术在冶金中的应用 [J]. 材料导报, 2000, 14(10): 23
[2]	Huang K M, Liu Y Q, Tang J X, et al. The non-heat effect of electromagnetic waves on chemical reaction and its application in the mechanism research of athermal biologic effect of electromagnetism [J]. J. Microwav., 1996, 12: 126
[2]	黄卡玛, 刘永清, 唐敬贤等. 电磁波对化学反应的非热作用及其在电磁生物非热效应机理研究中的意义 [J]. 微波学报, 1996, 12: 126
[3]	Chelluri B. Dynamic magnetic consolidation (DMC) process for powder consolidation of advanced materials [J]. Mater. Manuf. Proc., 1994, 9: 1127
[4]	Celluri B, Barber J P. Full-density, net-shape powder consolidation using dynamic magnetic pulse pressures [J]. JOM, 1999, 51(7): 36
[5]	Yang S X, Huang J H. Application of magnetic field sintering in preparation of materials [J]. Mater. Rev., 2002, 16(2): 19
[5]	杨四新, 黄继华. 磁场烧结在材料制备中的应用 [J]. 材料导报, 2002, 16(2): 19
[6]	Qiu T S, Xiong S H, Xia Q. Study on treating arsenic-bearing refractory gold ore by magnetic field-intensified cyanidation leaching [J]. Met. Mine, 2004, (12): 32
[6]	邱廷省, 熊淑华, 夏青. 含砷难处理金矿的磁场强化氰化浸出试验研究 [J]. 金属矿山, 2004, (12): 32
[7]	Li X C, Wang T X, Jiang X, et al. Effect of electromagnetic field on melting slag resistance of MgO-C refractories [J]. J. Chin. Ceram. Sci., 2011, 39: 452
[7]	李享成, 王堂玺, 姜晓等. 电磁场对MgO-C耐火材料抗熔渣侵蚀性的影响 [J]. 硅酸盐学报, 2011, 39: 452
[8]	Xiao K J, Chen J, Li Q L, et al. Intensified extraction of pectin from orange peel in an electromagnetis fiebl of super-high frequency [J]. Food Sci., 2001, 1(3): 50
[8]	肖凯军, 陈健, 李巧玲等. 高频电磁场强化浸取果胶的研究 [J]. 食品科学, 2001, 1(3): 50
[9]	Ludtka G M, Jaramillo R A, Kisner R A, et al. In situ evidence of enhanced transformation kinetics in a medium carbon steel due to a high magnetic field [J]. Scr. Mater., 2004, 51: 171
[10]	Zhang Y D, Esling C, Lecomte J S, et al. Grain boundary characteristics and texture formation in a medium carb on steel during its austenitic decomposition in a high magnetic field [J]. Acta Mater., 2005, 53: 5213
[11]	Chio J K, Ohtsuka H, Xu Y, et al. Effects of a strong magnetic field on the phase stability of plain carbon steels [J]. Scr. Mater., 2000, 43: 221
[12]	Ohtsuka H. Effects of strong magnetic fields on bainitic transformation [J]. Curr. Opin. Solid State Mater. Sci., 2004, 8: 279
[13]	Kim W H, Lee Y S, Suh I K, et al. Influence of CaO and SiO2 on the reducibility of wüstite using H2 and CO gas [J]. ISIJ Int., 2012, 52: 1463
[14]	Shigematsu N, Iwai H. Effect of CaO added with SiO2 and/or Al2O3 on reduction rate of dense wustite by hydrogen [J]. ISIJ Int., 1989, 29: 486
[15]	El-Geassy A A. Influence of doping with CaO and/or MgO on stepwise reduction of pure hematite compacts [J]. Ironmaking Steelmaking, 1999, 26: 41
[16]	El-Geassy A A. Reduction of CaO and/or MgO-doped Fe2O3compacts with carbonmonoxide at 1173-1473 K [J]. ISIJ Int., 1996, 36: 1344
[17]	El-Geassy A A. Stepwise reduction of CaO and/or MgO doped-Fe2O3 compacts to magnetite then subsequently to iron at 1173-1473 K [J]. ISIJ Int., 1997, 37: 844
[18]	Zhao Z L, Tang H Q, Guo Z C. Effects of CaO on precipitation morphology of metallic iron in reduction of iron oxides under CO atmosphere [J]. J. Iron Steel Res. Int., 2013, 20: 16
[19]	Zhao Z L. Particle surface structure evolution of CO reducing iron oxide process [D]. Beijing: Beijing University of Science and Technology, 2012
[19]	赵志龙. CO还原铁氧化物过程的颗粒表面结构演变 [D]. 北京: 北京科技大学, 2012
[20]	Nakiboglu F, St John D H, Hayes P C. The gaseous reduction of solid calciowustites in CO/CO2 and H2/H2O gas mixtures [J]. Metall. Trans., 1986, 17B: 375
[21]	Inami T, Suzuki K. Effects of SiO2 and Al2O3 on the lattice parameter and CO gas reduction of CaO-containing dense wustite [J]. ISIJ Int., 2003, 43: 314
[22]	Khedr M H, Bahgat M, Nasr M I, et al. Effect of additives on the reduction behaviour and CO2 catalytic decomposition of nanocrystallite Fe2O3 [J]. Miner. Process. Extr. Metall., 2008, 117: 240
[23]	Iguchi Y, Goto K, Hayashi S. Surface segregation of calcium oxide in wustite and its effects on the reduction [J]. Metall. Mater. Trans., 1994, 25B: 405
[24]	Piotrowski K, Mondal K, Wiltowski T, et al. Topochemical approach of kinetics of the reduction of hematite to wüstite [J]. Chem. Eng. J., 2007, 131: 73
[25]	Geva S, Farren M, St John D H, et al. The effects of impurity elements on the reduction of wustite and magnetite to iron in CO/CO2 and H2/H2O gas mixtures [J]. Metall. Trans., 1990, 21B: 743
[26]	Guo B, Han H B, Chai F. Influence of magnetic field on microstructural and dynamic properties of sodium, magnesium and calcium ions [J]. Trans. Nonferrous Met. Soc. China, 2011, 21(Suppl. 2): S494
[27]	Zhang J Y, Song B, Xing X R, et al. Metallurgical Physical Chemistry [M]. Beijing: Metallurgical Industry Press, 2004: 21
[27]	张家芸, 宋波, 邢献然等. 冶金物理化学 [M]. 北京: 冶金工业出版社, 2004: 21
[28]	Zhang S Y, Lu Q, Xue R H, et al. Fundamentals of Magnetic Materials [M]. Beijing: Science Press, 1988: 16
[28]	张世远, 路权, 薛荣华等. 磁性材料基础 [M]. 北京: 科学出版社, 1988: 16

[1]	SU Zhenqi, ZHANG Congjiang, YUAN Xiaotan, HU Xingjin, LU Keke, REN Weili, DING Biao, ZHENG Tianxiang, SHEN Zhe, ZHONG Yunbo, WANG Hui, WANG Qiuliang. Formation and Evolution of Stray Grains on Remelted Interface in the Seed Crystal During the Directional Solidification of Single-Crystal Superalloys Assisted by Vertical Static Magnetic Field[J]. 金属学报, 2023, 59(12): 1568-1580.
[2]	SONG Qingzhong, QIAN Kun, SHU Lei, CHEN Bo, MA Yingche, LIU Kui. Interfacial Reaction Between Nickel-Based Superalloy K417G and Oxide Refractories[J]. 金属学报, 2022, 58(7): 868-882.
[3]	YUAN Jiahua, ZHANG Qiuhong, WANG Jinliang, WANG Lingyu, WANG Chenchong, XU Wei. Synergistic Effect of Magnetic Field and Grain Size on Martensite Nucleation and Variant Selection[J]. 金属学报, 2022, 58(12): 1570-1580.
[4]	LUAN Xiaosheng, LIANG Zhiqiang, ZHAO Wenxiang, SHI Guihong, LI Hongwei, LIU Xinli, ZHU Guorong, WANG Xibin. Strengthening Mechanism of 45CrNiMoVA Steel by Pulse Magnetic Treatment[J]. 金属学报, 2021, 57(10): 1272-1280.
[5]	TANG Haiyan, LIU Jinwen, WANG Kaimin, XIAO Hong, LI Aiwu, ZHANG Jiaquan. Progress and Perspective of Functioned Continuous Casting Tundish Through Heating and Temperature Control[J]. 金属学报, 2021, 57(10): 1229-1245.
[6]	REN Zhongming,LEI Zuosheng,LI Chuanjun,XUAN Weidong,ZHONG Yunbo,LI Xi. New Study and Development on Electromagnetic Field Technology in Metallurgical Processes[J]. 金属学报, 2020, 56(4): 583-600.
[7]	Qingdong XU, Kejian LI, Zhipeng CAI, Yao WU. Effect of Pulsed Magnetic Field on the Microstructure of TC4 Titanium Alloy and Its Mechanism[J]. 金属学报, 2019, 55(4): 489-495.
[8]	ZHANG Jianfeng,LAN Qing,GUO Ruizhen,LE Qichi. Effect of Alternating Current Magnetic Field on the Primary Phase of Hypereutectic Al-Fe Alloy[J]. 金属学报, 2019, 55(11): 1388-1394.
[9]	Ran TAO, Yutao ZHAO, Gang CHEN, Xizhou KAI. Microstructure and Properties of In-Situ ZrB_{2 np}/AA6111 Composites Synthesized Under an Electromagnetic Field[J]. 金属学报, 2019, 55(1): 160-170.
[10]	Jianfeng ZHANG, Qing LAN, Qichi LE. Investigation on the Change of Thermoelectric Power of Al-Fe Hypoeutectic Alloy Melt Caused by AC Magnetic Field[J]. 金属学报, 2018, 54(7): 1042-1050.
[11]	Sansan SHUAI, Xin LIN, Wuquan XIAO, Jianbo YU, Jiang WANG, Zhongming REN. Effect of Transverse Static Magnetic Field on Microstructure of Al-12%Si Alloys Fabricated by Powder-BlowAdditive Manufacturing[J]. 金属学报, 2018, 54(6): 918-926.
[12]	Qiang WANG, Meng DONG, Jinmei SUN, Tie LIU, Yi YUAN. Control of Solidification Process and Fabrication of Functional Materials with High Magnetic Fields[J]. 金属学报, 2018, 54(5): 742-756.
[13]	Yuan HOU, Zhongming REN, Jiang WANG, Zhenqiang ZHANG, Xia LI. Effect of Longitudinal Static Magnetic Field on the Columnar to Equiaxed Transition in Directionally Solidified GCr15 Bearing Steel[J]. 金属学报, 2018, 54(5): 801-808.
[14]	Yongyong GONG, Shumin CHENG, Yuyi ZHONG, Yunhu ZHANG, Qijie ZHAI. The Solidification Technology of Pulsed Magneto Oscillation[J]. 金属学报, 2018, 54(5): 757-765.
[15]	Qiang WANG, Ming HE, Xiaowei ZHU, Xianliang LI, Chunlei WU, Shulin DONG, Tie LIU. Study and Development on Numerical Simulation for Application of Electromagnetic Field Technologyin Metallurgical Processes[J]. 金属学报, 2018, 54(2): 228-246.

No Suggested Reading articles found!

Viewed

Full text

Abstract

Cited

Shared

Discussed