A Novel Metallurgical Technique for the Preparation of Soft Magnetic Iron Carbide from Low-Grade Siderite

Iron carbide (Fe3C) has attracted widespread attention as a functional material, catalyst, and magnetic material. In this study, soft magnetic Fe3C was prepared by carburization roasting, magnetic separation, and acid leaching using low-grade siderite as the raw material. The effects of carburization, subsequent magnetic separation, and acid leaching of the carburized samples on their magnetic properties were studied using a vibrating sample magnetometer (VSM), and the mechanisms of these methods were also studied. The final samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), VSM, and Mossbauer spectroscopy. Under optimized conditions, an iron carbide material comprising assaying 92.08% Fe and 6.94% C with a corresponding iron recovery rate of 73.50% was obtained. The saturation magnetization, the remanence, and coercivity values of the obtained iron carbide were 136.10 emu/g, 1.84 emu/g, and 39.11 Oe, respectively. Furthermore, Na2SO4 and NaOH were found to be useful additives for improving the carburization efficiency of iron carbide, enlarging iron carbide particles, improving the embedding relationship between iron carbide and gangue, and enhancing the dissolution of gangue in acid. The proposed technique is promising for the preparation of magnetic iron carbide materials with good soft magnetic performance. (c) 2022 Elsevier B.V. All rights reserved.