Corrosion of five corundum-mullite refractories with the different porous aggregates and the same matrix by the blast furnace slag was conducted using the static crucible test. Effects of properties of corundum-mullite aggregates on the slag resistance of refractories were investigated through X-ray diffractometer (XRD), scanning electron microscopy (SEM), and mercury porosimetry measurement, etc. It is found that the porous corundum-mullite aggregates have different slag absorbing capacity, which affects the composition of the corroded aggregates and matrices at slag/refractory interface, and thus affects the slag corrosion and penetration resistances. Comparing with the dense corundum-mullite refractory, the porous corundum-mullite aggregate with 31.6% apparent porosity (AP) substituting the dense aggregates in the refractories does not make the slag resistance degenerate and reduces the bulk density by 16.7 wt%; whereas, when the APs of aggregates increase to 41.6-44.8%, the slag resistance sharply deceases. It is a successful case that the developed lightweight refractory with high slag resistance has a potential application for working lining of high-temperature furnace.

Keywords: Lightweight corundum-mullite refractories, Porous aggregates, Slag resistance, Pore characteristics, Phase compositions.