Innovative utilization of refractory iron ore via suspension magnetization roasting: A pilot-scale study

In this study, an innovative suspension magnetization roasting (SMR) technology was developed and utilized for the recovery of iron from a typical refractory iron ore. The effects of the roasting temperature, CO reducing gas flow rate, N-2 fluidizing gas flow rate, and feeding rate on the iron recovery were investigated. Under the optimal roasting conditions, a continuous and stable pilot scale SMR test was conducted for 72 h, and a staged grinding and staged low-intensity magnetic separation (LIMS) process was designed to upgrade the roasted product. The results showed that with the appropriate SMR conditions - a roasting temperature of 520 degrees C, CO flow rate of 4.0 m(3)/h, N-2 flow rate of 2.0 m(3)/h, and feeding rate of 100 kg/h - an iron concentrate with a total iron grade (TFe) of 60.18% and iron recovery of 90.17% could be obtained. Compared to the traditional process of shaft furnace magnetization roasting (SFMR) followed by LIMS, the novel technique developed here could improve the TFe and iron recovery of the iron concentrate by 12-14% and 17-22%, respectively, with well-functioning equipment. During the SMR process, hematite and siderite were transformed into magnetite, which enhanced the magnetism of the iron minerals. The utilization of the SMR method has the potential to provide a significant technological advance in the field of refractory iron ore recovery in China and globally. (C) 2019 Elsevier B.V. All rights reserved.