Phase equilibria of FeOx-SiO2-Al2O3 slag system at 1200 °C and pO2 of 10−8.6 atm

Miao Tian, Xingbang Wan, Min Chen, Pekka Taskinen, Mia Tiljander, Ari Jokilaakso*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
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The increasing concentrations of metallic Al or Al2O3 in secondary copper resources like electronic wastes motivate research into the slag chemistry of high-Al2O3 iron silicate slags for optimizing the industrial smelting process. In this study, the effect of Al2O3 in slag on the phase equilibria of the FeOx-SiO2-Al2O3 slag system was experimentally investigated at 1200 °C and pO2 of 10−8.6 atm. The high-temperature experiments were undertaken in silica and spinel crucibles in a controlled CO–CO2 gas atmosphere, followed by rapid quenching and Electron Probe Microanalysis. The equilibrium compositions of liquid slags in the tridymite primary phase field, spinel primary phase field, and the three-phase invariant point were determined. The 1200 °C isothermal section was constructed for the FeOx-SiO2-Al2O3 system, and the results showed that Al2O3 can dissolve in the liquid slags to a maximum concentration of 17 wt%. The present experimental results were compared with the predictions by MTDATA and FactSage. It was found that the present experimentally determined liquid domain agreed well with the calculations by FactSage except the invariant point. However, the present isotherm in the spinel primary phase field of spinel displayed lower Al2O3 concentrations. The present results help regulating fluxing strategies of FeOx-SiO2-Al2O3 slags and optimizing smelting operations of recycling high-alumina concentration copper resources.

Original languageEnglish
Article number102502
Number of pages12
JournalCalphad: Computer Coupling of Phase Diagrams and Thermochemistry
Early online date16 Nov 2022
Publication statusPublished - Dec 2022
MoE publication typeA1 Journal article-refereed


  • Copper smelting
  • Equilibria
  • High-AlO slag
  • Thermodynamic


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