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

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 degrees C. However, the conversion rate of MgFe2O4 decreases and part of beta-C2S is converted to alpha-C2S above 1050 degrees 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.

Automated summary

The formation of MgFe2O4 is closely related to oxidation temperature, oxidation time, and airflow rate. Within a certain range, with the increase in temperature, oxidation time, and airflow rate, the conversion rate and grade of MgFe2O4 can be enhanced, which is significant for improving the recovery efficiency of slag.