Slag Cleaning Equilibria in Iron Silicate Slag–Copper Systems

Research output: Contribution to journalArticle


Research units

  • Geological Survey of Finland
  • Boliden Kokkola Oy


In this study, the equilibrium distributions of selected trace elements between molten iron-saturated copper alloy and selected iron silicate slags were measured, and the effects of silica fluxing on them. In addition to the copper and iron main components of the system, trace elements like antimony, gallium, germanium, gold, indium, and silver were added in experiments that spanned the temperature range of 1473–1573 K (1200–1300 °C). Experimental charges were quenched and prepared in polished mounts. In situ analyses of the resulting phases were made directly on the mounts without the need of phase separation prior to analysis. Electron probe X-ray microanalysis was used for concentrations at or above approximately 100 ppmw, and laser ablation-inductively coupled plasma-mass spectrometry for the lower concentrations in the slags. The very low slag concentrations of germanium, antimony, and indium obtained indicate that these elements can be removed from the slag by reduction, whereas gallium concentrations in the slag were high. Consequently, gallium removal from iron residues, such as zinc smelting jarosite, is difficult without volatilization. Based on the present observations, the industrial reduction processes for the treatment of smelting and refining slags as well as for the processing of iron residues, and extracting the reducible metal oxides and their metal values can be optimized. The target in fluxing should be to maintain the slag compositions with a silica concentration higher than about 28 wt%.


Original languageEnglish
Number of pages11
JournalJournal of Sustainable Metallurgy
Early online date31 Jul 2019
Publication statusPublished - 2019
MoE publication typeA1 Journal article-refereed

    Research areas

  • fayalite slag, Jarosite, slag cleaning, antimony, Gallium, germanium, gold, indium, silver

ID: 36645486