Low-cement-bonded alumina-chromia castables are used in the ferroalloy industry. However, the presence of Cr2O3 in these refractories can lead to the formation of water-soluble hexavalent chromium-containing alkali chromate salts, which are carcinogenic and pose environmental and health hazards.
Alumina-spinel castables, which combine alumina and spinel/MgO, offer a balance of properties including good thermal shock resistance, corrosion resistance, and mechanical strength. These materials are widely used for steel ladles.
Four alumina spinel castables were developed and tested in the laboratory, including three low-cement-bonded castables and one non-cement-bonded castable.
The low-cement-bonded castables had higher compressive strength and porosity compared to the non-cement castable.
This study demonstrates that alumina spinel castables are a viable alternative to alumina-chromia castables.
Subsequently, both low-cement and non-cement castables were field-tested.
The results showed that the non-cement castable did not exhibit the expected service life, whereas the low-cement-bonded castable with calcium magnesium aluminate cement showed promise as a replacement for the alumina-chromia castable.