The current study investigates hydrogen reduction of low-grade iron ore (∼37 % Fe) containing dispersed bands of hematite and jasper/quartzite phases. Gaseous hydrogen reduction is carried out at isothermal conditions in a custom-made tubular furnace, followed by magnetic separation. The reduction temperature (300–600 °C), time (30–90 min), particle size (0.5–3.3 mm), and hydrogen flow rate (0.5–1.5 LPM) were optimized by statistical design of experiments to maximize the saturation magnetization, degree of reduction and metallization. Complete reduction of hematite was achieved in 2 h at 600 °C; however, the separation of quartz from reduced ferrite was inefficient evidenced by the lower saturation magnetization. The association of impurities with hematite does not affect the reduction rate; however, the trapped quartz particles in the reduced phases deteriorate the magnetic separation efficiency. Temperature and time synergize the reduction rate, improving reduction and metallization degree; meanwhile, flow rate and particle size have minimal effect. Reduction below 450 °C restricted the reduction to magnetite, and the optimal conditions; 600 °C, 60 min, 0.5 LPM H_2, and 3.3 × 2 mm particle size yielded ferrite concentrate possessing saturation magnetization of 134.6 emu/g (68 % Fe_M) with 97.9 % DOR, 88.8 % DOM and 47.3 % yield. The reduction of hematite results in generation of micro cracks and porous morphology of the ferrite. Iron oxide reduction follows the Fe₂O₃ → Fe₃O₄ → Fe, evidenced by the absence of wustite (FeO) or fayalite (FeO.SiO₂) phases in the product. The ferrite particles form a fused and porous layer trapping the silica particles.

目前的研究调查了含有分散的赤铁矿和碧玉/石英相的低品位铁矿石（~37% Fe）的氢还原。气态氢还原在等温条件下在定制的管式炉中进行，然后进行磁选。还原温度（300–600 °C）、时间（30–90 分钟）、粒度（0.5–3.3 mm）和氢气流速（0.5–1.5 LPM）通过实验的统计设计进行优化，以最大化饱和磁化强度，还原度和金属化程度。赤铁矿在 600 °C 下 2 小时内完全还原；然而，较低的饱和磁化强度证明了石英与还原铁氧体的分离效率低下。杂质与赤铁矿的结合不影响还原率；然而，在还原相中捕获的石英颗粒会降低磁选效率。温度和时间协同还原率，提高还原度和金属化度；同时，流速和粒径的影响很小。450℃以下还原限制了磁铁矿的还原，最佳条件；600 °C，60 分钟，0.5 LPM H₂和 3.3 × 2 mm 的粒径产生的铁氧体精矿具有 134.6 emu/g (68% Fe _M ) 的饱和磁化强度，具有 97.9% DOR、88.8% DOM 和 47.3% 收率。赤铁矿的还原导致铁素体的微裂纹和多孔形态的产生。氧化铁还原遵循 Fe ₂ O ₃  → Fe ₃ O ₄  → Fe，由产品中不存在方晶石 (FeO) 或铁橄榄石 (FeO.SiO ₂ ) 相证明。铁氧体颗粒形成一个融合的多孔层，捕获二氧化硅颗粒。