Abstract: The mini-sintering test was introduced. The experiments of specimens of rich hematite with lowering SiO₂ content were carried out by the mini-sintering test. The strength and mechanism of agglomeration were studied mainly when silica content in sintered specimens was decreased gradually. The relationships between SiO₂ volume and morphology of sinter were also investigated. It is considered that high grade sinter can be developed by raising sinter basicity so as to enhance complex calcium ferrite content or lowering sinter basicity so as to make Fe₂O₃ bonding for strength.