Properties of regenerated MgO–CaO refractory bricks: Impurity of iron oxide

Regenerated MgO–CaO refractory brick samples with 0, 1.5, 3.0 wt% iron oxide (Fe2O3) addition were prepared by using spent MgO–CaO bricks and fused magnesia as raw materials. The microstructure, flexural strength and corrosion resistance to cement clinker were investigated respectively. It is shown that additions of Fe2O3 mainly contributed to forming dicalcium ferrite (C2F) in the final products. Bulk density, flexural strength at room temperature, and corrosion were enhanced, while the flexural strength at 1573 K decreased along with the increasing of Fe2O3 addition, which was beneficial for the improvement in sintering due to the formed C2F and increased amount of liquid phase. The maximum amount of impurity Fe2O3 in regenerated MgO–CaO brick was found to be below 1.57 wt%, considering its flexural strength at high temperature and corrosion resistance property.