Fundamental investigation on removal of copper from molten iron with Na₂CO₃-FeS fluxes

In order to promote utilization of scrap procured in the market and reduction of energy consumption in iron- and steelmaking, it is necessary to develop a practical method of Cu removal. In this study, Cu removal from hot metal by sulfidation of Cu was identified as a potential candidate for industrial use and was investigated in laboratory experiments using ferrous sulfide (FeS) and sodium carbonate (Na₂CO₃) as commercially-available fluxes. A laboratory experiment on removal of Cu from hot metal was carried out using a 10 kg-scale furnace. Cu removal occurred while feeding the Na₂CO₃-FeS fluxes, and stopped after the end of flux feed. In the experimental temperature range, lower temperatures were advantageous for Cu removal, reflecting the exothermic nature of Cu sulfidation. The dependence of Cu removal on the composition of the hot metal was also confirmed based on an analysis focusing on the Cu partition ratio. The difference in the Cu partition ratio in the present study and in the literature, in which pure Na2S was used as a Na source, was interpreted in terms of the optical basicities of the components in the melt.