The influence of ZnO in fayalite slag on the degradation of magnesia-chromite refractories during secondary Cu smelting

In order to study the role of ZnO in the degradation of magnesia-chromite refractories, the chemical corrosion behaviour in a ZnO-containing fayalite slag (FeO-SiO2-ZnO-Al2O3) is investigated using a rotating magnesia-chromite refractory finger corrosion test under a reducing atmosphere at 1200 °C. The results show that, likewise to ZnO-free fayalite slag, periclase is predominantly corroded. Both ZnO and FeO diffused into the original periclase and chromite grains thereby forming, respectively, (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)[Cr,Al,Fe]2O4 spinel. Concurrently, ZnO and FeO were also incorporated into the (Zn,Fe,Mg)2SiO4 olivine during its formation. None of these phase formations resulted in new crack generation in the refractory. Considering the infiltrated slag is almost completely depleted in ZnO at 4 mm from the hot face, the severe slag penetration up to the centre of the refractory sample is not caused by the ZnO presence in the initial slag.