Chloride-assisted electrochemical conversion of Fe-Cr-Ni alloy scrap into oxide powders for enhanced acid leaching
Abstract
This study investigates a chloride-assisted electrochemical conversion process for transforming compact, passivated Fe-Cr-Ni alloy scrap into recoverable oxide powders with enhanced acid leachability. The scrap contained 69.94 wt% Fe, 17.16 wt% Cr, and 6.90 wt% Ni. Electrochemical analyses showed that hydroxide electrolytes promoted the formation of compact oxide/hydroxide passive films, whereas chloride electrolytes induced passive film destabilization and sustained anodic dissolution. In KCl electrolyte, anodically released metal species subsequently precipitated and were recovered as oxide powders containing Fe 2 O 3 , Cr 2 O 3 , and NiO. Increasing the KCl concentration from 1 to 4 mol/L increased ionic conductivity and lowered the anode potential required to maintain the imposed current density. Among the examined conditions, 4 mol/L KCl provided the lowest and most stable anode-potential response while maintaining a powder yield comparable to those obtained at 2–3 mol/L. The electrochemically formed oxide powders exhibited an average particle size of 144.2 nm at 4 mol/L KCl. Under identical leaching conditions of 4 mol/L H 2 SO 4 at 50 °C for 30 min, dissolution efficiencies increased from 10.46%, 8.13%, and 9.23% for Fe, Cr, and Ni in untreated bulk scrap to 93.47%, 92.41%, and 96.64%, respectively, for the electrochemically formed oxide powders. This comparison indicates that the improved leaching response resulted from coupled electrochemical phase conversion and powder formation, rather than from an isolated particle-size reduction effect. These results demonstrate that chloride-assisted electrochemical conversion serves as an upstream activation step for downstream hydrometallurgical processing of passivated Fe-Cr-Ni alloy scrap.
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BibTeX
@article{kim2026chlorideassisted,
title = {{Chloride-assisted electrochemical conversion of Fe-Cr-Ni alloy scrap into oxide powders for enhanced acid leaching}},
author = {Myungsuk Kim and Namhun Kwon and Soong Ju Oh and Kyoung-Tae Park and Jae Hong Shin},
journal = {Electrochemistry Communications},
year = {2026},
month = oct,
doi = {10.1016/j.elecom.2026.108267},
url = {https://linkinghub.elsevier.com/retrieve/pii/S1388248126001633},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Chloride-assisted electrochemical conversion of Fe-Cr-Ni alloy scrap into oxide powders for enhanced acid leaching
AU - Myungsuk Kim
AU - Namhun Kwon
AU - Soong Ju Oh
AU - Kyoung-Tae Park
AU - Jae Hong Shin
PY - 2026
DA - 2026/10/30
JO - Electrochemistry Communications
DO - 10.1016/j.elecom.2026.108267
UR - https://linkinghub.elsevier.com/retrieve/pii/S1388248126001633
AB - This study investigates a chloride-assisted electrochemical conversion process for transforming compact, passivated Fe-Cr-Ni alloy scrap into recoverable oxide powders with enhanced acid leachability. The scrap contained 69.94 wt% Fe, 17.16 wt% Cr, and 6.90 wt% Ni. Electrochemical analyses showed that hydroxide electrolytes promoted the formation of compact oxide/hydroxide passive films, whereas chloride electrolytes induced passive film destabilization and sustained anodic dissolution. In KCl electrolyte, anodically released metal species subsequently precipitated and were recovered as oxide powders containing Fe 2 O 3 , Cr 2 O 3 , and NiO. Increasing the KCl concentration from 1 to 4 mol/L increased ionic conductivity and lowered the anode potential required to maintain the imposed current density. Among the examined conditions, 4 mol/L KCl provided the lowest and most stable anode-potential response while maintaining a powder yield comparable to those obtained at 2–3 mol/L. The electrochemically formed oxide powders exhibited an average particle size of 144.2 nm at 4 mol/L KCl. Under identical leaching conditions of 4 mol/L H 2 SO 4 at 50 °C for 30 min, dissolution efficiencies increased from 10.46%, 8.13%, and 9.23% for Fe, Cr, and Ni in untreated bulk scrap to 93.47%, 92.41%, and 96.64%, respectively, for the electrochemically formed oxide powders. This comparison indicates that the improved leaching response resulted from coupled electrochemical phase conversion and powder formation, rather than from an isolated particle-size reduction effect. These results demonstrate that chloride-assisted electrochemical conversion serves as an upstream activation step for downstream hydrometallurgical processing of passivated Fe-Cr-Ni alloy scrap.
SN - 1388-2481
SN - 1873-1902
ER -