Abstract:Metal droplets sticking to spinel solids, present in metallurgical slag systems, play an important role in hindering the sedimentation of copper in slags. To understand this phenomenon, the interaction between spinel particles with Cu on one hand and with slag, on the other hand, was evaluated. A dedicated approach was applied, using an industrially relevant synthetic slag system PbO-FeO-SiO₂-CaO-Al₂O₃-Cu₂O-ZnO, pure copper and MgAl₂O₄ substrates to represent the industrial slag, the entrained copper droplets and the spinel solids, respectively. Both the copper-MgAl₂O₄ and the slag-MgAl₂O₄ interaction were studied using sessile drop measurements, combined with an extensive microstructural analysis. Additionally, the effect of time on the slag-MgAl₂O₄ interaction was studied using immersion experiments. Copper displayed a non-wetting behaviour on MgAl₂O₄, whereas slag displayed a reactive wetting and an interaction layer of (Mg,Fe,Zn)(Al,Fe)₂O₄ spinel was formed at the interface, which was also observed in the immersion experiments. Moreover, the diffusion of MgO and Al₂O₃ from the spinel substrate into the slag droplets was noted.

Key words: sessile drop; copper; spinel; slag