Efficient enrichment of iron concentrate from iron tailings via suspension magnetization roasting and magnetic separation

Iron ore tailings are industrial solid wastes generated from mineral processing. The disposal of iron ore tailings leads to environmental threat and serious security because of their tiny particle size and large storage. In this paper, suspension magnetization roasting and magnetic separation technology were utilized to recover iron tailings. The results showed that iron concentrates with iron grade of 65.01% and recovery of 89.07% could be obtained under conditions of CO concentration 30%, roasting temperature 520 °C, roasting time 20 min, grinding particle size of roasted products with 94% mass fraction of − 38 μm and magnetic field strength 1800 Oe. The vibration sample magnetometer, X-ray diffraction, specific surface area detector, scanning electron microscope and energy-dispersive spectrometer showed that unit mass magnetic moment, specific magnetization coefficient and saturation value of magnetization intensity of magnetic concentrate were all significantly improved. Weak magnetic iron ore was selectively transformed into strong magnetic magnetite. Compared with raw ore, there was porous and cracked structure on the surface of roasted ore and magnetic concentrate, which was conducive to magnetization reaction, magnetism and phase transformation of iron ore.