abstract
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 degrees 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.
keywords
SIZE DISTRIBUTION; MILL SCALE; REDUCTION; PARTICLES; DIAGRAMS
subject category
Electrochemistry; Materials Science
authors
Fumo, A; Lopes, DV; Starykevich, M; Kovalevsky, AV
our authors
Adélio Fumo
PhD Student
Andrei Kavaleuski
Principal Researcher
Daniela Vanessa Rosendo Lopes
Junior Researcher
Maksim Starykevich
Junior ResearcherProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
The authors acknowledge CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, and LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). Adelio Fumo acknowledges the financial support from the Foundation for Science and Technology-FCT through the grant (PRT/BD/154825/2023). Daniela V. Lopes and Maksim Starykevich acknowledge the support of their Research Employment Contracts from the FCT, 2023.07163.CEECIND and 2020.00625.CEECIND, respectively.