Corrosion of MgAl_2O_4 Spinel with Different Al_2O_3 Contents in Iron-Containing Gasifier Slag

摘要

The MgAl_2O_4 spinel ceramic specimens with five different alumina contents (w(Al_2O_3)=66%,72%,78%,85%,90%)were prepared using alumina micropowder and magnesia micropowder as raw materials, after mixing, shaping, drying, and heating at 1800 °C. The crucible specimens were tested for slag corrosion with commercial gasifier slag at 1500 °C for 2 h under oxidazing and reducing atmosphere. The specimens before and after slag test were studied by analyzing the microstructure and element distributions of corroded specimens with XRD, SEM and EDS. The results show that the slow dissolution of spinel into slag was observed because a low melting point material was formed by spinel reacting with CaO and SiO_2 in slag on the surface of the spinel block. Meanwhile, FeO_x in the slag was absorbed around the surface of spinel block to form the multiple solid solution, which was composed of MgO-Al_2O_3-FeO_x and had a denser microstructure. The absorption of FeO_x in slag had contributed to the resistance to slag penetration for the spinel. The relationship between the absorption capacity of spinel on FeO_x and the chemical composition of spinel was discussed.