STEEL GRIPS online - Studies on the decarburization of MgO-C refractories during ladle preheating

STEEL GRIPS online
ISSN 1866-8453

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May 10, 2012

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Ismail Kasimagwa, Voicu Brabie, and Pär G. Jönsson:
Studies on the decarburization of MgO-C refractories during ladle preheating

Refractories, reduction-oxidation (redox) corrosion, antioxidants, preheating, decarburization, decarburization rate, slagline

The effect of ladle preheating conditions on the wear of MgO-C refractories at different steel plants has been investigated. The focus has been on refractories used in the slag zone, some including which contain antioxidants. This investigation shows that the wear/corrosion of the slagline refractories is already initiated during ladle preheating under real industrial conditions. The degree of the decarburization process is dependent on the refractory composition, time and the preheating fuel or environment. For refractories without antioxidants, the refractory decarburization is 3.8 times slower when coal gas is used in ladle preheating, compared to a mixture of oil and air. Ladle preheating of the refractories without antioxidants leads to direct wear of the slagline refractories due to total loss of matrix strength, resulting in a sand-like product independent of the preheating method. When the refractories containing antioxidants are compared to each other, the decarburization rate was lower when coal gas was used during ladle preheating, compared to electrical preheating. The cracking tendency of the refractories is enhanced by the increasing size of antioxidants. The refractory containing coarser grains of antioxidants (< 3000 um) cracked much earlier than those containing finer grains (< 100 um). For example, after 6 weeks in storage, the crack thickness was 1.5 mm for large-grained refractory, whereas it was 0.3 mm for the fine-grained refractory.