Fluidization Roasting Technology of Jingtieshan Iron Ore in the Absence of Carbon Additives

This study presents a fluidization roasting technology for siderite-bearing iron ore without the use of carbon additives. Samples of Jingtieshan iron ore were subjected to fluidization magnetization roasting, and the effects of roasting temperature, time, and N2 flow rate on the magnetic separation performance were explored. An iron concentrate with an iron grade of 57.40% and recovery of 91.17% was acquired at a roasting temperature of 700 °C, roasting time of 10.0 min, an N2 flow rate of 600 mL/min, grinding particle size of −125 μm, and constant magnetic intensity of 99.47 kA/m. The samples were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy–energy dispersive spectroscopy, and vibrating sample magnetometry. The results revealed that hematite and goethite were reduced to magnetite by the CO generated during siderite decomposition; meanwhile, siderite was transformed into magnetite with the consumption of CO during the reduction process. The saturation magnetization of the roasted ore significantly increased owing to the formation of ferrimagnetic magnetite, which was easily recovered in the subsequent magnetic separation.