Influence of oxygen partial pressure on synthetic coal slag infiltration into porous Al ₂ O ₃ refractory

The infiltration characteristics of synthetic coal slag into Al ₂s ₃ refractory material with a temperature gradient induced along the slag's penetration direction were investigated with respect to time and oxygen partial pressure of the experimental atmosphere. Synthetic slag, which is representative of an average of the ash contents from United States coal feedstock, was melted in either an oxidizing air atmosphere or a reducing CO/CO ₂ gas mixture with a ratio of 1.8. The experiments were conducted with a hot-face temperature of 1450°C, and the slags were deposited onto refractory samples in the same atmospheres as they were originally melted. A comparison between the infiltrations in the CO/CO ₂ and air atmospheres revealed that differences in oxygen partial pressure changed the mode in which the slag interacted with the refractory. While infiltrations in CO/CO ₂ atmosphere demonstrated elevated Al ₂O ₃ concentrations in the slag owing to refractory dissolution, infiltrations in air atmosphere showed enrichment of SiO ₂ and Al ₂O ₃ in the slag because iron-oxide from the slag incorporated into the corundum refractory. For both cases, the reactions led to increases in viscosity, but the effect was more profound in the air atmosphere, where penetrations were found to be shallower. The oxygen partial pressure's influence on the slag's composition, primarily with iron-oxide species, and on viscosity played a pivotal role in governing the effective penetration into the refractory.