Insight into mechanisms of CaCl2 for improving reduction disintegration of iron ore sinter: An experimental and DFT investigation

• Published in: Journal of molecular liquids Vol. 366; p. 120334
• Main Authors: Xu, Liangping, Liu, Huibo, Cheng, De, Zhong, Qiang, Rao, Mingjun, Li, Guanghui
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-11-2022
• Subjects: CaCl2 Adsorption mechanism; DFT; Iron ore sinter; Reduction disintegration; Reduction disintegration; DFT; CaCl2 Adsorption mechanism; Iron ore sinter
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2022.120334

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•A film-like structure on the surface of sinter was formed in CaCl2 solution.•The adsorbed CaCl2 film hinders the reduction of sinter by CO gas.•Two stable positive coordination bonds were the mechanism of adsorption.•The bonds were stable below 500 ℃, but loses efficacy > 500 °C.
The metallurgical performance of iron ore sinter, the primary feedstock for blast furnace (BF), particularly the reduction disintegration index (RDI) of sinter, has a significant impact on the BF ironmaking. Spraying CaCl2 is one of the most practical measures to improve the RDI of sinter, while the mechanisms have yet to be identified. In this work, reduction tests were conducted in a shaft furnace and DFT calculations were performed, and the mechanism of CaCl2 adsorption on the sinter was elucidated theoretically and experimentally. The adsorbed CaCl2 was combined with magnetite and hematite within the sinter through two positive coordination bonds with the formation of CaCl2 film on the surface. The film-like structure hinders the reduction of hematite by CO at low temperatures (＜500 oC), and the suitable concentration of CaCl2 acting on the sinter is 5%.