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Journal of Sustainable Metallurgy

, Volume 3, Issue 4, pp 772–781 | Cite as

Slag Chemistry of High-Alumina Iron Silicate Slags at 1300 °C in WEEE Smelting

  • Lassi Klemettinen
  • Katri Avarmaa
  • Pekka TaskinenEmail author
Research Article

Abstract

New fluxing chemistries are appearing in secondary copper smelters, where the use of raw materials from various waste electric and electronic equipment sources as significant copper feedstocks associate greatly increased fractions of alumina in the slag, compared with the conventional raw materials utilized in primary copper smelting processes. In extreme cases, alumina concentrations close to the saturation level may be reached, and the practical alumina loads to the slag may be above 10 wt% (Al2O3). This affects the physical properties of the molten slag and enhances stabilities of the solid primary phases, thus having an impact on its saturation boundaries and solubilities. We examined fundamental phase-equilibrium data of high-alumina slags by an equilibration-quenching method in equilibrium with metallic copper at 1300 °C, in the oxygen pressure range of P(O2) = 10−10–10−5 atm. We measured the chemical compositions of the molten slag and copper, and solid alumina-iron spinel directly by the Electron X-ray Microprobe technique and provide novel phase-equilibrium data for the poorly known intermediate oxygen pressure range from air to iron saturation.

Keywords

Copper Pyrometallurgy Phase equilibria Thermodynamics Circular economy 

Notes

Acknowledgements

CLIC Innovation Oy and Tekes supported this research through ARVI programme (Tekes Funding  Decision #379/14). The authors are indebted to Mr. Lassi Pakkanen, the Geological Survey of Finland, for his kind assistance in the EPMA measurements.

Supplementary material

40831_2017_141_MOESM1_ESM.docx (24 kb)
Supplementary material 1 (DOCX 23 kb)

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Copyright information

© The Minerals, Metals & Materials Society 2017

Authors and Affiliations

  1. 1.Thermodynamics and Modelling Research Group, School of Chemical EngineeringAalto UniversityAaltoFinland

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