Study on Oxidation Behavior of Industrial Basic Oxygen Furnace Slag and Recovery of Magnetic Iron‐Containing Phase

• Published in: Steel research international 2022-05, Vol.93 (5), p.n/a
• Main Authors: He, Zhanwei, Lan, Mo, Hu, Xiaojun, Xue, Xiangxin, Chou, Kuo-Chih
• Format: Article
• Language: English
• Subjects: Air flow; Basic converters; Chemical analysis; Conversion; Dicalcium silicate; industrial BOF slag; Iron; Magnesium ferrites; magnetic separation; Metallurgy; Oxidation; oxidation behavior; Oxygen steel making; Recovery; Slag
• ISSN: 1611-3683; 1869-344X
• DOI: 10.1002/srin.202100558

The BOF slag contains a lot of iron‐containing species and its efficient recovery is a difficult problem in metallurgy. Herein, the oxidation behavior of industrial BOF slag under air atmosphere is investigated to explore the optimal oxidation conditions for transforming nonmagnetic FeO into magnetic MgFe2O4, including oxidation temperature, oxidation time, and airflow rate. The raw slag and oxidized slags are analyzed using chemical analysis, X‐ray diffraction (XRD) analysis, scanning electron microscope (SEM)‐energy dispersive spectroscopy (EDS) analysis, and Factsage thermodynamic simulation. The results show that the formation of MgFe2O4 phase is closely related to the oxidation temperature, oxidation time, and airflow rate. With the increase in temperature, the conversion rate of MgFe2O4 increases, and reaches the maximum at 1050 °C. However, the conversion rate of MgFe2O4 decreases and part of β‐C2S is converted to α‐C2S above 1050 °C. When the oxidation time and airflow rate increase, the conversion rate of MgFe2O4 increases and reaches the maximum value at 100 min and 1.25 L min−1, respectively. Correspondingly, the grade increased from 16.3% of the raw slag to 27.86% of the magnetic slag, an increase of 11.5%. This is a more convenient and effective method, which can not only bring economic benefits for relevant enterprises but also reduce environmental pollution. The oxidation behavior of industrial BOF slag under air atmosphere is investigated to explore the optimal oxidation conditions for transforming nonmagnetic FeO into magnetic MgFe2O4. With the increase in oxidation time, the grindability of oxidation slag increases. After 100 min of oxidation, the grade and recovery of magnetic slag by magnetic separation are 27.86% and 81.14%, respectively.