Effect of Barun concentrate ratio on strength of finished pellets

In order to give full play to the characteristics of Barun iron concentrate with high iron grade, concentrated particle size distribution and excellent pellet-forming performance, while suppress the weakness of high content of K₂O, Na₂O and F, how to improve the utilization rate of Barun ore on the basis of ensuring the strength of finished oxidized pellets by reasonably matching it with the ore in the region with low content of harmful elements was studied. In the research process, the influencing factors on strength of finished ball under different ratios of Barun iron concentrate were analyzed by FactSage7.3 thermodynamic software calculation, oxidation roasting, compressive strength detection, chemical composition detection, mineral phase analysis, SEM-EDS analysis and other experimental research methods. The results show that the iron concentrate in the area has a wider particle size range than the Barun iron concentrate, with the average particle size of 53.21 μm and 32.01 μm, respectively. The mineral powder particles smaller than 0.043 mm(<300 mesh) of iron concentrate in the area is accounting for 78.65%, while the mineral powder particles of Barun iron concentrate is accounting for 84.70%. The strength of finished ball with 40% ratio of Barun iron concentrate is the highest, which is 4 602.2 N /P. Thermodynamic calculation shows that with the increase of Barun iron concentrate ratio, the slag phase in the finished ball increases. In the process of oxidizing roasting and cooling, pyroxene and quartz are the main precipitates of finished ball slag phase for 40% Barun iron concentrate, while calcium iron olivine is the main precipitates of 100% Barun iron concentrate. In terms of mineral phase structure, with the increase of Barun iron concentrate ratio, the hematite intercrystal effect decreases, but the slag phase distribution is uniform at 40% ratio, which plays a good role of bonding phase. One of the reasons for low compressive strength of magnesium-bearing magnetite particles formed by MgO content of 1.05% in 100% Barun finished ball is its poor intercrystal.