Effects of low-quality ores blending structure on the sintering and metallurgical properties

Based on the ironmaking status of serious deterioration of iron ore and obvious fluctuation of sinter performance, the effects of limonite/hematite (L/H) ratio (0.33∼1.96) on the sintering performance of mixed ore and metallurgical properties of sinter were analysed combined with X-ray diffraction, scanning electron microscope with an energy dispersive spectrometer and metallographic microscope in this study for the application of actual low-quality ore blending. With L/H increasing, the basic characteristics of mixed ore are optimised, the maximum exhaust gas temperature, tumbler index and yield first decreased and then increased, the productivity exhibited the opposite trend. The porosity of sinter increases and the amounts of silico-ferrite of calcium and aluminium and kirschsteinite decrease. Besides, the reduction degree (RI) and low temperature reduction degradation index (RDI+3.15) of sinter are above 80% and 73%, respectively. The permeability index increases first and then decreases slightly with L/H increasing. The dropping interval is positively correlated with the maximum pressure drop and the permeability index. The decrease of the permeability index deteriorates the soft melt dripping performance of sinter. The recommended L/H ratio should not be higher than 1.02 under the prerequisite of guaranteeing the sintering performance and the metallurgical properties of sinter.