The use of steelmaking slag as protection for oxidation of MgO-C refractories

MOLINÉ MARCOS N.; CALVO, WALTER A.; GASS, SEBASTIÁN E.; TOMBA MARTINEZ, ANALÍA G.; GALLIANO, PABLO G.; GUTIERREZ-CAMPOS D.

Congreso; 2022 Pan American Ceramics Congress and Ferroelectrics Meeting of Americas; 2022

The American Ceramic Society

MgO-C is one of the most important refractories for steelmaking ladles. Carbon is a key component which allows the refractory to have high resistance to thermal shock and to slag attack. However, C oxidizes in air; this risk is currently found during the pre-heating of the ladle (at the beginning and between production cycles).During the operation, the liquid steel is evacuated through ladle bottom leaving a slag layer adhered to the working lining which serves as protection against oxidation of refractories’ carbon. Nevertheless, this layer could suffer degradation by ambient humidity which affects its role as an oxygen diffusion barrier.This work analyzes how the refractory composition (graphite content, type of binder) and the slag degradation affect the oxidation resistance of MgO-C materials. For testing, a slag layer was generated over one of the plane surface of the refractory cylinder (25x25 mm2) by treatment at 1400°C (graphite bed). Only this face was exposed to air (unidirectional test) at 1000°C (2 h). Variations in weight, depth of decarburized layer and graphite content were used as oxidation indicators. To evaluate the effect of slag weathering, tests were carried out after 2 and 10 weeks from the sample conditioning.