Bonding Mechanisms of Basic Refractories for RH Snorkels

doi:10.19691/j.cnki.1004-4493.2020.04.006

China's Refractories ›› 2020, Vol. 29 ›› Issue (4): 29-34.DOI: 10.19691/j.cnki.1004-4493.2020.04.006

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Bonding Mechanisms of Basic Refractories for RH Snorkels

GUO Zongqi¹^,^*(), MA Ying²

1 Trasteel International SA, Lugano CH-6900, Switzerland
2 RHI Magnesita (Dalian) Co., Ltd., Dalian 116600, China

Online:2020-12-15 Published:2020-12-15
Contact: GUO Zongqi
About author:Dr. Guo Zongqi studied the major of refractories in Xi’an University of Architecture and Technology, China, and received his Ph.D. degree in Ecole Polytechnique, University of Montreal, Canada. For more than 10 years, he worked on the syntheses of chromia raw materials and pioneering research and development of high chrome refractories for slagging coal gasifiers, which was awarded with Second Grade Technical Advance Prize by the Ministry of Chemical Industry. Dr. Guo has gained broad research experiences on a few of international refractory platforms in Canada, Austria, Poland and China. His recent investigations and industrial practice include great progress of high purity, high density sintered magnesia from natural magnesite. He has been involving in long-term continuous studies of burnt basic bricks and carbon-containing bricks for cement rotary kilns and steel-making process.

Abstract

Abstract:

Magchrome bricks, as the inner lining of RH snorkels, have played a vital role in the operation of RH degassers for a long term. In chrome-free campaigns, resin-bonded, Al-containing magnesia bricks have been an alternative of magchrome bricks with a comparable performance in the last decade. It is important to have found whisker formation in the matrix of Al-containing magnesia bricks above 1 100 °C and in the correlation to their high performance of RH snorkels. In this paper, the bonding mechanisms of both refractories are investigated to differentiate from other refractories. In magchrome bricks, the bonding modes of fused magchrome grains are characterized by the reactions between magnesia and chrome ore at different burning temperatures. At 1 500 °C, liquid forms around chromite grains. It is sucked into surrounding magnesia and a gap forms around chromite grains at 1 600 °C. Plenty of Fe₂O₃, Cr₂O₃ and Al₂O₃ have diffused from chrome ore into magnesia at 1 670 °C. A complete dissolution of the chrome ore takes place at 1 750 °C, with chromite precipitating entirely. In unburnt, Al-containing magnesia bricks, a dense network of whiskers is formed during heating, which is a prevailing bonding feature, instead of traditional particle growing and merging. It is believed that the whiskers are formed by vapour-solid mechanism since there is no liquid droplet observed at the tip of whiskers. In most stringent working conditions of RH snorkels, the bonding mechanisms are emphasized for their application, instead of chromia component.

Key words: magnesia-chromite brick, unburnt basic brick, bonding mechanism, RH snorkel, whisker, vapour-solid mechanism

GUO Zongqi, MA Ying. Bonding Mechanisms of Basic Refractories for RH Snorkels[J]. China's Refractories, 2020, 29(4): 29-34.

Figures/Tables 8

References 10

[1]	Chen Rongrong, He Pingxian, Mou Jining, Wang Ning. Research of slag corrosion resistance of chrome free refractories for RH vessel lining. Naihuo Cailiao (Refractories, in Chinese), 2005, 39(5): 357-359.
[2]	Somnath Mandal, C. J. Dileep Kumar, Sukumar Adak, Devendra Kumar, Arup Kumar Chattopadhyay. Phase evolution, microstructure and thermo-mechanical characteristics of titania bearing spinel-periclase refractories for RH degasser. Proceedings of UNITECR’15, Vienna, Austria, 2015: No. 144.
[3]	In-Kyung Bae, Moo-Chul Kim, Dae-Hun Chung, Man-Dong Shin. The improvement of MgO-C bricks toughness for RH snorkels. Proceedings of UNITECR’05, Orlando, Florida, USA, 2005: No. 65.
[4]	Guo Zongqi, Ma Ying, Neuboeck Rainer, Koeck Andreas. Thermal evolution of Al-containing magnesia refractory for RH snorkels. China’s Refractories, 2019, 28(1): 1-6.
[5]	H. Barthel, F. Kassegger, F. Soucek. The use of magnesia chromite refractories made from sintered Co-clinker in secondary steelmaking and open-hearth furnace. Proceedings of International Symposium on Refractories, Hangzhou, China, 1988: 489-504.
[6]	Y. Bi, I. A. Smith, K. Andreev. Development of degasser snorkel refractories and the effect of the process parameters on wear rate. Proceedings of UNITECR’13, Victoria, British Columbia, Canada, 2013: 692-696.
[7]	Zhao Ming, Chen Rongrong, Shen Zhongming, Jin Congjin. Realization of chrome-free refractories for RH degasser. Naihuo Cailiao (Refractories,in Chinese), 2013, 47(6): 433-436.
[8]	Rainer Telle. The role of whisker for the reinforcement of refractories. Proceedings of Eurogress, Aachen, 2012: 199-204.
[9]	Hans Georg Wiedemann, Jörg Nerbel, Armin Reller. Structuring and texturing aluminum oxides. Thermochemica Acta, 1998, 318(1-2): 71-82.
[10]	Akira Yamaguchi, Shinobu Hashimoto. Growth of magnesia whiskers. Ceramics International, 1992, 18(5): 301-305.

B. Temp.	Microstructure	Location	MgO	Al₂O₃	SiO₂	CaO	Cr₂O₃	Fe₂O₃
1 500 °C	Fig. 1	Periclase	81.11	0.92			5.27	12.70
		Boundary	21.14	12.30			26.78	39.78
		Chromite	19.63	14.78		0.64	49.01	15.21
1 600 °C	Fig. 2	Periclase	76.03	3.20			9.79	10.98
		Interstitial	19.06	3.61	20.66	28.60	14.89	10.25
		Peripheral	20.80	8.44			18.43	52.33
		Chromite	19.23	14.12			51.70	14.35
1 670 °C	Fig. 3	Periclase	92.48				2.55	4.96
		Periclase	86.11				3.94	9.95
		Chromite	21.38	14.12		1.09	50.55	9.92
1 750 °C	Fig. 4	Periclase	67.86	4.30			15.74	12.10
		Interstitial	23.58	12.16			40.25	24.00
		Chromite	23.03	15.33			50.57	10.15

B. Temp.	Microstructure	Location	MgO	Al₂O₃	SiO₂	CaO	Cr₂O₃	Fe₂O₃
1 500 °C	Fig. 1	Periclase	81.11	0.92			5.27	12.70
		Boundary	21.14	12.30			26.78	39.78
		Chromite	19.63	14.78		0.64	49.01	15.21
1 600 °C	Fig. 2	Periclase	76.03	3.20			9.79	10.98
		Interstitial	19.06	3.61	20.66	28.60	14.89	10.25
		Peripheral	20.80	8.44			18.43	52.33
		Chromite	19.23	14.12			51.70	14.35
1 670 °C	Fig. 3	Periclase	92.48				2.55	4.96
		Periclase	86.11				3.94	9.95
		Chromite	21.38	14.12		1.09	50.55	9.92
1 750 °C	Fig. 4	Periclase	67.86	4.30			15.74	12.10
		Interstitial	23.58	12.16			40.25	24.00
		Chromite	23.03	15.33			50.57	10.15

Spectrum	C	N	O	Mg	Al	Si
Whisker 1	18.58	20.90	32.64	9.70	16.76	1.43
Whisker 2	7.02	19.82	36.96	11.74	20.67	2.19
Whisker 3	17.43	22.11	34.30	9.29	15.29	1.29
Whisker 4	13.94	21.97	35.33	9.99	16.86	1.56

Spectrum	C	N	O	Mg	Al	Si
Whisker 1	18.58	20.90	32.64	9.70	16.76	1.43
Whisker 2	7.02	19.82	36.96	11.74	20.67	2.19
Whisker 3	17.43	22.11	34.30	9.29	15.29	1.29
Whisker 4	13.94	21.97	35.33	9.99	16.86	1.56

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[1]	GUO Zongqi, MA Ying, NEUBOECK Rainer, KOECK Andreas. Thermal Evolution of Al-containing Magnesia Refractories for RH Snorkels [J]. , 2019, 28(1): 1-6.
[2]	JIN Shengli, HARMUTH Harald. Investigation of Compressive Refractory Creep [J]. , 2018, 27(3): 21-27.
[3]	CHEN Junfeng*,LI Nan,YAN Wen, WEI Yaowu, HAN Bingqiang. Effect of Temperature Schedule on the Morphology of SiC Made From Graphite and Silicon Powder [J]. , 2016, 25(4): 23-28.
[4]	WANG Xian, ZHU Boquan, LI Xiangcheng, MA Zheng, WEI Ying. Effect of Spherical Ni Powder on Microstructure of Secondary Carbon in MgO-C Refractories Matrix [J]. , 2015, 24(2): 42-45.
[5]	XIA Zhongfeng, WANG Zhoufu, WANG Xitang, LIU Hao, MA Yan. In-situ Formation of Silicon Carbide Whisker by Ni-catalyzed Silicon-modified Pitch and Its Mechanism [J]. , 2015, 24(2): 32-35.
[6]	LIANG Feng, LI Nan, LIU Baikuan, HE Zhongyang. Effect of Carbon Source on Crystal Morphology of SiC in-situ Formed in Al2O3-Si-C Matrix [J]. , 2015, 24(2): 11-15.
[7]	Shengli JIN, Harald HARMUTH, Dietmar GRUBER, Roman RÖSSLER. Creep Modeling of Magnesia-chromite Bricks in a RH Snorkel During a Process Cycle [J]. , 2015, 24(1): 22-25.
[8]	ZHANG Ying, JIANG Mingxue, ZHANG Junzhan. Synthesis of SiC Whiskers from Silicon Nitride in Argon Atmosphere [J]. China's Refractories, 2009, 18(1): -.
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