Electroreduction of Magnetite for Steel Production from Ceramic Suspensions Containing Metallic Iron

The presence of impurities in the iron oxides feedstock introduces significant challenges during the electrowinning process for green steelmaking, leading to unpredictable effects. In the present study, the impact of metallic iron content on the Faradaic efficiency and microstructure of iron deposits obtained through the electroreduction of iron-magnetite powders in alkaline suspensions (10 M NaOH) at low temperature (80 °C) was evaluated. The findings reveal that the presence of metallic iron may negatively impact the reduction process. A comparative analysis of suspensions with and without iron content showed that the Faradaic efficiency for iron-free samples (63%–76%) significantly exceeds that of iron-containing suspensions (37%–57%). This demonstrates that the presence of metallic iron in the suspension can hinder the electroreduction of magnetite to Fe, with the effect becoming more pronounced at higher Fe concentration. Changes were observed in the microstructure of iron deposits, with the dendrites becoming less sharp and more disordered in iron-containing suspensions. Particle size distribution analysis further revealed that larger metallic iron particles may contribute to the sedimentation and entrapment of magnetite particles, which negatively affect the current density and Faradaic efficiency.