Effect of Pre-reduction Degree on Softening Behavior of Simulant Sinter Iron Ore

Reduction test under load is normally applied to evaluate softening and melting behaviour of ferrous burdens at simulated condition in cohesive zone in blast furnace. Outcomes from this test are very complex because they depend on reduction degree, chemical composition, basicity, melts physical property, etc. One of the reasons to make complex this test is sample for the test provided as particle packed bed. In order to comprehend softening and melting behaviour of cohesive zone, focus on behaviour of single particle as a component of particle packed bed in this study. For simplification, a pre-reduced simulant sinter iron ore was prepared as single tablet sample. The samples were made from mixture of reagent oxides and they were pre-reduced to control their reduction degree to several reduction levels. The tablet sample was rapidly heated up to 900 degrees C, and then gradually heated up with 10 degrees C/min under inert gas atmosphere and 0.1 MPa load. Shrinkage degree of the sample was measured during the softening and melting test, and quenched sample was made at certain temperature when the sample shows a characteristic tendency. Cross-sectioning observation of the quenched sample provided mineral phases distribution in the tablet sample. The observation indicated that peripheral structure has a significant effect on deformation resistance. Especially in there, existence of molten slag phase could make easy to deform the sample particle shape, and metallic solid Fe phase helped to strengthen the particle's deformation resistance.