Magnetization Roasting of Siderite Ore in a Low-Oxygen Atmosphere

Siderite ore is difficult to treat using conventional processing methods such as gravity, magnetic separation, and froth flotation owing to its low iron grade, complex mineral composition, and easy sliming in the grinding process. In this study, magnetization roasting in a low-oxygen atmosphere without carbon additives has been carried out for the treatment of siderite ore. An iron concentrate with an iron grade of 60.12% and a recovery of 80.06% was obtained with a raw ore assaying 22.99% iron. The samples were characterized by X-ray diffraction, Mössbauer spectroscopy, vibrating sample magnetometry, and scanning electron microscopy. The results indicated that the siderite (FeCO₃) and hematite (α-Fe₂O₃) were primarily transformed into magnetite (Fe₃O₄) and maghemite (γ-Fe₂O₃) at a roasting temperature of 650°C with an O₂ concentration of 1.0%. The saturation magnetization of the raw ore increased from 2.04 to 20.89 A m²/kg after magnetization roasting owing to the formation of ferrimagnetic magnetite and maghemite. This study is conducive to exploiting siderite ore resources using low-carbon magnetization roasting technology.