Reaction Characteristics Between Sinter and Serpentine

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THE metallurgical properties of blast furnace (BF) slag are very important for the stable operation and productivity of BF.[1–4] In recent years, a large amount of low-cost iron ores with high Al2O3 content has been used in the BF ironmaking process due to the depleting of the high Fe-grade and low-Al2O3 iron ore resources. Hence, it has resulted in an increase of Al2O3 content in BF slag. Therefore, the metallurgical properties of BF slag, such as viscosity, desulphurization ability, and melting point, have become off specifications.[5]

XIN JIANG, HAIWEI AN, and FENGMAN SHEN are with the School of Metallurgy, Northeastern University, 313#, No. 11, Lane 3, Wenhua Road, Heping District, Shenyang, Liaoning 110819, China. Contact e-mail: [email protected] HONGSONG HAN is with the School of Metallurgy, Northeastern University and also with the Technology Center, Meishan Iron and Steel Limited Corporation, Nanjing, Jiangsu 210039, China. XIANG DING, and LIAOSHA LI are with the Key Laboratory of Metallurgical Emission Reduction & Resources Recycling, Ministry of Education, Anhui University of Technology, Maanshan, Anhui 243002, China. Manuscript submitted August 11, 2019.

METALLURGICAL AND MATERIALS TRANSACTIONS B

Therefore, the path to maintaining essential metallurgical properties of the BF slag with a high Al2O3 content is a major focus in the ironmaking discipline, in recent years. MgO is one of the essential components of BF slag. An appropriate amount of MgO content can ensure a beneficial level of fluidity and desulphurization ability of the BF slag, especially the slag with a high content of Al2O3.[6–9] Usually, the method of adding MgO into BF slag can be considered as adding MgO-bearing flux into sintering raw materials. However, based on overall indices, MgO has negative effects on the sintering indices and metallurgical properties of the sinter.[10–13] Therefore, the direct addition of appropriate amounts of MgO-bearing flux into BF is considered to be a popular countermeasure to cope with the usage of iron ores with high Al2O3. The purpose of adding MgO is mainly to improve the fluidity and desulphurization ability of BF slag and the permeability in the dripping zone of BF caused by high Al2O3 iron ores.[14–17] Usually, the MgO-bearing flux used in BF are magnesite (MgCO3) and dolomite (CaCO3ÆMgCO3).[18–20] However, in recent years, more and more magnesite and dolomite are used leading to a demand that exceeds supply.

Therefore, the serpentine (magnesium silicate) has become a new kind of MgO-bearing flux used in the BF process. During the use of serpentine, the reaction between sinter and serpentine is inevitable, and the study of it is important for proper BF operation. However, there are only a few reports about this reaction. Therefore, to better understand the fundamentals of the reaction characteristics between sinter and serpentine, a series of experiments, analyses, and discussions were carried out in this work. Those include the phase transition process, phase compositions during the reaction