Interactions of Crucible Materials With an FeOx–SiO2–Al2O3 Melt and Their Influence on Viscosity Measurements

Abstract Viscosity is a critical parameter during metal extraction, influencing the settling of valuable droplets, slag handling, and mass transfer. The viscosity of oxide melts can be measured with high-temperature rheometers. During such measurements, interactions between the crucible and the oxide system can change the chemical composition, melt structure, and thus the viscosity. For increased reliability of viscosity measurements, the influence of crucible and spindle materials on viscosity must be studied. In this study, the viscosity of a synthetic FeO x –SiO 2 –Al 2 O 3 melt was measured using the rotating spindle technique and three different crucible and spindle materials (Mo, Fe, and Ni) to determine the interactions with the melt and the influence on viscosity. The interaction was evaluated by comparing the post-experimental chemical analyses, the Fe/Fe 2+ /Fe 3+ content, visual observations, and using scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS). The results showed that all the crucibles partially dissolved into the melt, affecting the melt structure, composition, and, thus, the viscosities. The viscosity data obtained using the Mo setup interacted the least with the melt, was the most stable, and with the best reproducibility. Graphical Abstract