Removal of copper from steel scrap using sulfide salts treatment (RIP2026-00100)

Ankur Kumar, Keyan Matar, Xiaolei Guo, Jianyue Zhang, Gerald Frankel, Alan Luo, Jianxun Hu, Brian Sieger, Yuxuan Shui

The Ohio State University, Colorado School of Mines, The Ohio State University, State of Ohio, Ohio State University, Columbus, Honda Development and Manufacturing of America (HDMA), LLC, Honda Development and Manufacturing of America (HDMA), LLC, The Ohio State University

Steel recycling is an effective strategy to reduce energy use and carbon emissions. However, steel scrap often contains undesirable elements such as copper, which can cause hot shortness during hot working. To mitigate this, the use of sulfide-based salt fluxes and controlled holding times are investigated to convert copper into sulfide, facilitating its removal from molten steel. Thermo-Calc simulations are employed to design a salt mixture with low viscosity for efficient mass transfer, minimal off-gas generation for safety, and high copper solubility to enhance partitioning. The performance of a molten FeS–Na₂S mixture is evaluated with varying copper concentrations in steel. Steel containing 0.12 wt% Cu exhibited a 93% copper reduction after 3 hours, while a 10-minute treatment achieved 82% copper reduction. Electrochemical methods are also being used to further improve copper removal efficiency.