Abstract: By optical microscopic analysis, electron probs micro-analysis and Mössbauer effect, the existing state of Mgo and its effecf on the properties of sinter and pellet were studied, from optical microscopic observation, it was shown that as the Mgo content in sinter increased, the content of hematite and calciumferrite obviously decreased, when it reached more than 4%, some magnesiosilicate salt minerals in sinter slag was occured It was also found by electron probe micro-analysis that the Mgo mainly presented in iron oxide compound except hematite,such as magnesiomagnetite in sinter and magnesioferrite in pellet, and a small part of Mgo existed in slag phase. Large amount of Mg²⁺ entered in octahedron sites of magnetite of pellet of Hangchow stael works during induration period has been examined by use of Mossbausr effect which was ascertaind the mechanism of Mgo concentrated into iron oxide compound and changed the mineral constitasnts of iron ore agglomerates
from avove investigation the effect of Mgo on the metallurgical properties of iron ore agglomerates was abtained.