Freeze-Lining Formation in Submerged Arc Furnaces Producing Ferrochrome Alloy in South Africa

摘要

In 2016, a 63 MVA sub-merged arc furnace producing ferrochrome in South Africa was shut down and partially excavated for partial repair of its refractory lining as part of the annual maintenance activities. No significant evidence of the formation of a freeze-lining was found, although the lining design philosophy applied was of the conductive type typically applied. The paper presented here, investigate the possibility that the slag practice applied prior to excavation was not conducive to the formation and maintenance of a stable freeze-lining. The study included identification of the slag regimes under which the SAF was operated in the 12 months prior to the excavation, using data science techniques, and studying the effect of different regimes on freeze-lining behaviour, using transient one-dimensional heat transfer and thermodynamic models. Where available, temperature dependent properties for slag and refractory were utilised in the heat transfer calculations.