Mechanism for suspension magnetization roasting of iron ore using straw-type biomass reductant

As an alternative reductant for fossil fuel in the future, straw-type biomass contributes to emission reduction and green utilization in the suspension roasting process. In this study, the influences of the roasting time, roasting temperature and dose of straw-type biomass after suspension magnetization roasting (SMR) and separation were investigated. The optimal conditions were determined to be a roasting time of 7.5 min with a straw-type biomass dose of 20 wt% and a roasting temperature of 800 ℃, in which an iron grade of 71.07% and recovery of 94.17% were obtained for the iron concentrate. The maximum saturation magnetization under optimal conditions was 35.05 A·m²·g⁻¹, and the gaseous regulation of the biomass revealed that cumulative reducing gas volume was 293.93 mL at the optimal roasting time of 450 s. The transformation of hematite to magnetite was detected by X-ray diffraction (XRD). During microstructure evolution, the outer layer consisting of fissures and tiny holes continuously deepened toward the core.