Effect of boron-containing magnetite on properties of ultrafine-grained magnetite pellets
WEN Bao-liang1, ZHANG Xiao-ping1,2, LIU De-lou3, LI Jia-xin1, WU Hong-liang1,2, YANG Jia-long1
1. School of Metallurgical Engineering, Anhui University of Technology, Ma'anshan 243032, Anhui, China; 2. Ma'anshan Iron and Steel Co., Ltd., Ma'anshan 243003, Anhui, China; 3. Technical Center, Fushun New Steel Co., Ltd., Fushun 113001, Liaoning, China
Abstract：The pelletization of ultra-fine iron ore has special significance for the application of lean ore resources in China. However, there are some problems such as difficulty in pelletizing, poor quality of green pellets, and low strength of finished pellets. Boron and iron in borax are closely disseminated and difficult to apply. However, its addition is beneficial to improving the performance of pellets. The specific surface area was measured by the BET method, and the microstructure of iron concentrate and roasted pellets was evaluated by scanning electron microscopy (JSM6490). The effect of adding boron-bearing magnetite on pelletizing performance, pellet quality, and preheating roasting strength of superfine magnetite was studied. The following results were obtained: after adding 30 % borax to the ultra-fine magnetite, the balling property of the mixed concentrate was improved to reach the medium balling index. The drop strength of the green ball increased from 2.4 times/0.5 m to 4.0 times/0.5 m, the compressive strength increased from 15.38 N/individual to 19.08 N/individual, and the burst temperature increased from 340 ℃ to 410 ℃. Under the optimized ore blending, the burst temperature could be increased to 460 ℃, the preheating and roasting time of the pellet was shortened, and the temperature was reduced. Under the conditions of the same preheating time and temperature, the same roasting time, and the roasting temperature of 1 175 ℃, the strength of the pellets (compared with 100% superfine concentrate) is increased by about 900 N/individual, reaching more than 3500 N/individual. Under the same strength, the roasting temperature can be reduced by nearly 100 ℃. The reason that adding boron-containing magnetite can improve the performance of pellets is that the morphology of boron-containing magnetite particles is complex, the content of alkaline substances is large, and the particle size is coarse, which can effectively help the intercalation between particles, increase the molecular water content of powder, improve the ballability, improve the strength of green ball and the temperature of explosion. MgO and B2O3 will generate a low melting point liquid phase inside the pellets, fill the pores, promote the reduction of calcination temperature, enhance the uniform grid connection between particles, and improve the strength of the calcined pellets.
温宝良, 张晓萍, 刘德楼, 李家新, 吴宏亮, 杨佳龙. 含硼磁铁矿对超细粒级磁铁矿球团性能的影响[J]. 钢铁, 2022, 57(11): 33-41.
WEN Bao-liang, ZHANG Xiao-ping, LIU De-lou, LI Jia-xin, WU Hong-liang, YANG Jia-long. Effect of boron-containing magnetite on properties of ultrafine-grained magnetite pellets[J]. Iron and Steel, 2022, 57(11): 33-41.
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2022, Vol. 57 
