The refractory used in this case was a 90% alumina, 10% magnesia refractory
. Examination of the XRD pattern in Fig.
thick dry vibrated magnesia refractory with 25% porosity will have a calculated depth of the saturation network of 3.2 in., which more closely approximated field observations of spent inductors.
To understand what is occurring, the leading edge of the saturation network must be viewed, When molten metal enters a magnesia refractory, the iron displaces air from the voids around the refractory grains.
The high alumina brick lining wears from slag attack while the dry vibrated magnesia refractory
in the inductor shows no wear and virtually no buildup over the entire life of an inductor.
Another example for consideration is a channel furnace inductor lined with a magnesia refractory melting cast iron.
The melting point of the magnesia refractory drops further to less than 3000F in the presence of silica that can easily be circulated through the channel as a derivative of uncleaned returns.