In the Hall–Héroult process for primary aluminum production, alumina is continuously injected into molten cryolite. Heat and mass transfer within the powder lead to the formation of alumina raftsAlumina raft at the bath-gas interface. These rafts disintegrate and dissolve within minutes after injection, but the extreme thermal and corrosive conditions make direct observation nearly impossible, even in laboratory settings. To overcome these limitations, an optical diagnostic setup was developed, combining schlieren imaging, shadowgraphy, and particle image velocimetry (PIV). By injecting alumina onto molten cryolite, we were able to observe the progressive disintegration of the rafts, flow disturbances induced by the injection, and the dynamics of the dissolutionDissolution boundary layer. Optical methods provides valuable data for validating numerical models and deepening the understanding of alumina raftAlumina raft behavior. Improved control of these mechanisms could enhance process efficiency, reduce energy consumption, and lower greenhouse gas emissions in aluminum production.