In April 2013 a 48 MVA submerged arc furnace producing silicomanganese
was excavated in South Africa. Since the high shell temperatures recorded
in the tap-hole area resulted in the furnace being switched out for relining,
the tap-hole area was excavated systematically. A refractory wear profile
of the tap-hole area with affected hearth and sidewall refractory was
obtained in elevation. The carbon ramming paste in front of, above, and
below the tap-hole was worn, as was the SiC with which the tap-hole was
built. A clay mushroom formed but was detached from the refractories.
Thermodynamic and mass-transfer calculations were conducted to
quantify the potential for wear by chemical reaction between refractory
and slag and refractory and metal in the tap-hole area. It was found that
chemical reaction between refractory and slag or metal could offer only a
partial explanation for the wear observed; erosion is expected to contribute
significantly to wear.