Phase transformation assisted reduction roasting of low-grade iron ore via industrial biomass as a reductant

Recent studies have confirmed the application of biomass as an alternate reductant for the fossil fuel-based reduction roasting of low-grade iron ores. The present study examines the biomass collected from a laboratory-based Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor treating slaughterhouse wastewater as an alternative reductant for the reduction roasting of low-grade iron ore assaying ca. 50.47% Fe. The featured characterization studies of the low-grade ore and biomass samples were initially presented. Further, biomass and low-grade iron ore mixtures at a mass ratio of 50:50 were subjected to a reduction roasting process at a temperature range of 550–750 °C. Micro-morphological characteristics, magnetic properties, microstructural changes, and phase transformation of the raw ore and roasted products were methodically studied by X-ray diffraction (XRD)/Rietveld analysis, scanning electron microscope (SEM) analysis, and superconducting quantum interference device (SQUID) magnetometer analysis. It is monitored that the main mineral phase hematite (Fe₂O₃) was converted to magnetite (Fe₃O₄) in the roasted products, and the thermal stress fractures were also observed. The magnetic study identified a considerable conversion of weak ferromagnetic to strong ferromagnetic features in roasted products. It is also observed that the saturation magnetization (M_s) values increase with a rise in roasting temperature. The results in this work offer a featured understanding of the exploitation of industrial sludge as a reductant for the reduction roasting of low-grade iron ore slime and its consequence in achieving sustainable mine practices and green utilization.