بررسي فرآيند تشويه مغناطيسي در رآكتور بستر ثابت و جدايش مغناطيسي شدت پايين در پرعيارسازي كانسنگ‌ منگنز آهن‌ دار و ارزيابي تطبيقي با كانسنگ هماتيتي

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