A new study from KU Leuven researchers and collaborators provides high-quality multicomponent phase-equilibria data to improve thermodynamic predictions for industrial copper-recycling slags.
Author(s): Based on the conference contribution by Dieter Verwaest, Maksym Shevchenko, Georgii Khartcyzov, Bart Blanpain & Evgueni Jak.
Published: COPR 2025 – 12th International Copper Conference.
Understanding complex slag chemistry in real recycling conditions
Efficient secondary copper production depends heavily on accurate knowledge of slag–metal equilibria. However, industrial copper-recycling slags contain a broad and highly variable mix of oxides—including Cu, Pb, Zn, Fe, Si, Sn, Ni, Ca, Mg, Al, and Sb—making robust thermodynamic modelling extremely challenging.
In this study, the authors experimentally mapped phase equilibria in an industrially relevant multicomponent system (“CuO₀.₅”–PbO–ZnO–“FeO₁.₅”–SiO₂–“SnO₂”–NiO–(CaO–AlO₁.₅–MgO–SbO₁.₅)) at temperatures between 1170 and 1250 °C and under varying oxygen partial pressures (pO₂).
Using a controlled equilibration–quenching methodology followed by electron-probe X-ray microanalysis, the team quantified the effects of temperature, redox conditions, and the individual contributions of CaO, MgO, AlO₁.₅, and SbO₁.₅ on slag–metal equilibria.
Impact: improving predictive capability for industrial copper recycling
The resulting high-quality dataset provides essential input for refining existing thermodynamic databases. These improvements directly enhance process modelling for secondary copper smelters, supporting:
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better prediction of element distributions (e.g., Pb, Zn, Sn, Ni)
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more accurate slag viscosity and liquidus estimates
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optimised operating temperatures and oxygen potentials
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reduced metal losses to slag
By grounding thermodynamic models in experimentally validated data, the study strengthens the scientific basis for more energy-efficient and environmentally responsible copper-recycling technologies.
Reference
Verwaest, D., Shevchenko, M., Khartcyzov, G., Blanpain, B., & Jak, E. (2025). Multicomponent Phase Equilibria Study for Secondary Copper Recycling Applications. In: 12th International Copper Conference (COPR 2025), pp. 2085–2088. Springer Nature.
