Abstract:
Within ilmenite smelters, the slag is at a temperature just above its liquidus (because the furnace
operates with a slag freeze lining), and the metal bath is at a temperature which is approximately
150°C lower than the slag temperature. As a result, solidification of the slag in contact with the
metal is expected, and was indeed detected with sounding bars in operating furnaces. Samples of
the solidified layer were obtained from a DC ilmenite smelter which had cooled with its contents
intact. Analysis showed parts of the layer to be close to anosovite (Ti3O5) in composition; in all
cases, the solid contained much less FeO than the primary pseudobrookite which forms during
bulk slag solidification after tapping. Equilibrium calculations show that these compositions can
result from reaction of initially FeO-rich pseudobrookite with dissolved carbon in the metal bath.
The presence of this layer of near-anosovite material in the furnace has possible implications for
settling of metal and for the furnace energy balance; the latter was explored with thermodynamic
calculations.
