To investigate the role of Al2O3, in iron are sinters, constitutional analysis of high Al2O3 and low Al2O3 contained iron ore sinters was carried out by applying EPMA random sampling method. Measured compositions were mainly located around the two tie lines of CaO·SiO2-CaO·3(Fe, Al)2O3 and 2CaO·SiO2-(Fe, Al)2O3. It was found that Al2O3 had a tendency to concentrate in calcium ferrite, especially in that of composition of Fe2O3 from 40% to 60%. MgO content in sinter are decreased with SiO2, but CaO content increased with SiO2. This reverse tendency suggests that the role of CaO and MgO in iron ore sinters can be different.
