Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The relationship between the chemical composition and sinter body strength was discussed. Moreover, sinter-pot tests were performed. The effects of sinter body strength on the sintering indexes were then elucidated, and the bottom limit of sinter body strength of blending ores was confirmed. In the results, the compressive strengths (CSs) of iron ores are observed to decrease with the increasing of the contents of loss on ignition (LOI), SiO 2 , and Al 2 O 3 ; however, LOI of less than 3wt% does not substantially influence the CSs of fine ores. In the case of similar mineral composition, the porosity, in particular, the ratio between the number of large pores and the total number of pores, strongly influences the sinter body strength. With an increase of the blending-ore CSs used in sinter-pot tests, the yield, productivity, and tumbler strength increase, and the solid fuel consumption decreases. The CSs of the blending ores only slightly affect the sintering time. The CS bottom limit of the blending ores is 310 N. When the CSs of the blending ores increase by 10%, the yield, productivity, and tumbler index increase by 1.9%, 2.8%, and 2.0%, respectively, and the solid fuel consumption decreases by 1.9%.

Gangue existing states largely affect the high-temperature characteristics of iron ores. Using a micro-sintering method and scanning electron microscopy, the effects of gangue content, gangue type, and gangue size on the assimilation characteristics and fluidity of liquid phase of five different iron ores were analyzed in this study. Next, the mechanism based on the reaction between gangues and sintering materials was unraveled. The results show that, as the SiO 2 levels increase in the iron ores, the lowest assimilation temperature (LAT) decreases, whereas the index of fluidity of liquid phase (IFL) increases. Below 1.5wt%, Al 2 O 3 benefits the assimilation reaction, but higher concentrations proved detrimental. Larger quartz particles increase the SiO 2 levels at the local reaction interface between the iron ore and CaO, thereby reducing the LAT. Quartz-gibbsite is more conductive to assimilation than kaolin. Quartz-gibbsite and kaolin gangues encourage the formation of liquid-phase low-Al 2 O 3 -SFCA with high IFL and high-Al 2 O 3 -SFCA with low IFL, respectively.

Sintering with large amount of limonite generally requires higher fuel consumption, either due to the dehydration of combined water or the evaporation of more added water. Although limonite can accelerate melt formation, the sintering strength indexes are in lower level on the contrary, proved to have much to do with the excessive assimilation.In order to improve the sintering behavior of sintering mix when large amount of limonite were used, a simplified method named separating large particles of limonite from granulation was investigated by measuring the bonding strength using quasi-particles on the base of confirming influence of excessive assimilation on effective liquid phase of limonite, and calculating changes in properties of sintering mix for moisture transferring. The results obtained were summarized as follows:Limonite nuclei adversely influenced bonding strength of quasi-particles mainly by the effective liquid phase, which was determined by volume decrease for penetration and viscosity increment by less fluxed melt, separation of limonite nuclei to reduce the contact interface is helpful in improving bonding of sintered body, and the separation ratio was suggested be within certain range by melt distribution in the whole bed. Less accumulation of condensed water and partial absorption by ungranulated dry limonite resulted in smaller increment in effective mean size and less decrement in void fraction, indicating better bed permeability.

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