Recovery of iron from hazardous tailings using fluidized roasting coupling technology

Iron ore tailings have proved to be one of the most hazardous solid wastes. This paper presents an innovative technological method for recycling iron from tailings that involves coupling the magnetic separation preconcentration with fluidized roasting followed by low-intensity magnetic separation. After analyzing the separation index and chemical composition, on the basis of the basic theory, the influences of different conditions on iron recovery were determined. Moreover, a high-quality iron concentrate assaying 65.91% Fe with a recovery rate of 94.60% was obtained under the following optimum parameters: gas flow rate of 500 mL/min, CO concentration of 25%, roasting time of 2.5 min, roasting temperature of 600 degrees C, grinding fineness of approximately 90 wt% passing 23 mu m, and magnetic intensity of 104 kA/m. In addition, XRD analyses and iron chemical phase, optical metallographic microscope and magnetic property measurements revealed that hematite was converted to magnetite successfully after roasting. Using this method, a large amount of iron can be recycled, and this hazardous solid waste can be transformed into a valuable resource. At the same time, this research promotes and provides a research basis for integrated utilization of such solid wastes. (C) 2019 Elsevier B.V. All rights reserved.