Observations of freeze layer formation during heat balance shifts in cryolite-based smelting bath

Abstract

Abstract The responses of a cryolite-based bath to shifts in heat input/output balance have been investigated in previous work. The effect of such heat balance shifts on bath superheat and on the frozen ledge, protecting the cell walls, is of most interest and has been investigated primarily in an experimental analogue to a smelting cell. In this paper, the microstructure and morphology of the freeze itself, as a function of the applied heat balance shift is investigated. Different layers were detected in the freeze, showing that both the freeze morphology and the phases present vary depending on bath conditions. The phase composition change was also analysed and compared with the bulk bath in different thermal states, created when the heat balance was shifted. Based on the investigation, a freeze growth mechanism is proposed.