Clean utilization of high-iron red mud by suspension magnetization roasting

Abstract

High-iron red mud could potentially become a valuable resource if the iron could be extracted efficiently. A novel method for iron recovery from red mud using suspension magnetization roasting (SMR) followed by low-intensity magnetic separation has recently been developed. In this study, the effects of SMR operation parameters on its ability to extract iron from red mud were investigated. Under the optimized conditions, determined to be a roasting temperature of 540 °C, reaction time of 15 min, total gas-flow rate of 500 mL/min, and CO concentration of 30%, an iron grade of 56.41% and iron recovery of 88.45% was achieved. The saturation magnetization and specific magnetic susceptibility of the roasted sample under the optimal conditions studied were 37.17 A·m2/kg and 30.72 × 10−5 m3/kg, respectively. X-ray diffraction, chemical iron phase, and Mössbauer spectroscopy analyses were conducted on the raw and roasted samples, and the results indicate that hematite and goethite phases present in the raw red mud were transformed into magnetite and maghemite during the SMR process.