Distribution of Platinum between the SiO₂–CaO–Al₂O₃–TiO₂ Slag System and Molten Copper

A residue containing TiO₂ and PGMs is generated in the hydrometallurgical process used for recycling platinum-group metals (PGMs). In this study, a pyrometallurgical process was considered in which PGMs from the residue generated in the hydrometallurgical process were concentrated in a molten copper phase as a collector metal and TiO₂ was separated into the SiO₂–CaO–TiO₂ slag phase with SiO₂ and CaO flux. The dissolution of PGMs must be reduced to minimize the loss of PGMs to the slag. Therefore, the distribution ratios of Pt as representative PGMs between the liquid SiO₂–CaO–Al₂O₃–TiO₂ or liquid SiO₂–CaO–TiO₂ slag and molten copper were measured at 1773 K under an oxygen partial pressure of p_O2 ¼ 10-¹⁰. The experimental results showed that the distribution ratio of Pt increased with TiO₂ concentration in the slag, and the distribution ratio of Pt reached a maximum value at a TiO₂ concentration of approximately 10 mass%, and decreased with a further increase in TiO₂ concentration with the SiO₂–CaO–Al₂O₃–TiO₂ slag. However, as TiO₂ concentration in the slag increased, the distribution ratio of Pt decreased with the SiO₂–CaO–TiO₂ slag. Additionally, the experimental results showed that the distribution ratio of Pt between the SiO₂–CaO–Al₂O₃–TiO₂ slag and liquid copper increased with the slag basicity B, defined as B = (mass%CaO)/(mass%SiO₂) when the TiO₂ concentration in the slag was greater than 10 mass%. [doi:10.2320/matertrans.MT-M2024002]