Steel, as one of the most important engineering materials, forms the foundation of many industries. Its production depends on the reliable supply of key elements such as iron an‎d manganese. Iron, as the main constituent of steel, an‎d manganese, as an essential alloying an‎d desulfurizing agent that improves the mechanical properties of steel, both play crucial roles in this industry. The depletion of high-grade deposits an‎d the increasing proportion of complex ores have made the investigation of advanced beneficiation methods increasingly important. In this study, the process of magnetic roasting in a fixed-bed reactor followed by low-intensity magnetic separation was investigated for two different ore types: a Fe–Mn-bearing ore an‎d a hematitic ore. For the Fe–Mn-bearing sample, the effects of temperature an‎d residence time were studied using methane an‎d hydrogen as reducing gases, whereas for the hematitic sample, only methane was used an‎d temperature was the main variable. Phase an‎d microstructural transformations were characterized an‎d verified by XRF, XRD, VSM, SEM–EDS, an‎d reflected-light microscopy on thin-polish sections.The results indicated that in the Fe–Mn-bearing sample, although hematite was successfully reduced to magnetite an‎d pyrolusite to manganosite, the strong microstructural interlocking between Fe an‎d Mn phases, along with the formation of spinel-type structures, restricted complete selec‎tive separation. The best process performance was achieved at 550 °C, a residence time of 45 minutes, under hydrogen atmosphere, an‎d for particle sizes below 75 µm. Under these conditions, the manganese grade changed from 23.77 % in the feed to 20.52 % in the concentrate an‎d 26.53 % in the tailing, while the iron grade changed from 24.86 % in the feed to 36.7 % in the concentrate an‎d 24.47 % in the tailing. The manganese recovery in the non-magnetic tailing was 51.89 %, an‎d the iron recovery in the magnetic concentrate was 71.7 %, confirming the successful selec‎tive separation of iron into the concentrate an‎d manganese into the tailing, in accordance with the objective of this research.In the hematitic sample, due to its simpler mineralogical composition an‎d silica-dominated gangue, magnetite liberation was more effective, an‎d the magnetic roasting–separation process yielded favorable results. Optimum conditions were obtained at 600 °C, for particle sizes below 38 µm, using a three-stage magnetic separation circuit (rougher–cleaner–scavenger). Under these conditions, the iron grade increased from 30.55 % in the feed to 65.48 % in the concentrate, with an iron recovery of 88 % an‎d a total weight recovery of 41.28 %, indicating the effectiveness of multi-stage magnetic separation in improving fine liberation an‎d recovery.Overall, this study demonstrated that magnetic roasting can serve as an effective method for upgrading hematitic iron ores, whereas in Fe–Mn-bearing ores, microstructural interlocking an‎d spinel formation act as inherent limitations preventing complete selec‎tive separation. Therefore, optimization of roasting an‎d magnetic separation parameters should be ore-specific an‎d designed according to the mineralogical an‎d textural characteristics of each ore type.

مهدي نصيري سروي

مهين منصوري اصفهاني

علي احمدي عامله , محمد نوع پرست