Effect of MgO content on strength of high alumina iron ore pellets
LIU Tong1, LI Xingwang2, ZHANG Junjie1, JIA Laihui1, LEI Jie2, LONG Hongming2,3
1. Zhongtian Iron and Steel Group (Nantong) Co., Ltd., Nantong 216100, Jiangsu, China; 2. School of Metallurgical Engineering, Anhui University of Technology, Ma'anshan 243032, Anhui, China; 3. Anhui Province Key Laboratory of Metallurgy Engineering and Resources Recycling, Anhui University of Technology, Ma'anshan 243032, Anhui, China
Abstract：Magnesite pellets were prepared using high alumina hematite as the main raw material and magnesite as the magnesium-containing additive to study the effect of MgO content on strength of high alumina iron ore pellets. The results show that the drop strength of green pellets slightly decreases with the increase of MgO content, but it is still within the range of production requirements, while the compressive strength of roasted pellets exhibits a trend of decreasing initially, then increasing and finally decreasing again, and it is helpful to reduce the adverse effect of MgO on roasted pellet strength when MgO mass fraction is around 1.80%. Only calcined magnesite can be used for the production of magnesium-based pellets since direct addition of magnesite into pellets will significantly deteriorate the compressive strength. The influence mechanism of MgO content on the roasted pellet strength was explored by various characterization methods, such as calculating the liquid phase mass of pellets under different roasting temperatures by FactSage thermodynamic software, observing the microstructures of pellets combined with porosity testing. The analysis result of thermodynamics and microstructures of pellets reveals that the roasted pellet strength is closely related to the generation amount of liquid phase during roasting. The amount of liquid phase reaches the peak when MgO mass fraction is around 1.80%, and appropriate liquid phase mass accelerates the diffusion of crystalline particles and fills the pores in the pellets, which is conducive to the improvement of roasted pellet strength. Appropriate addition of magnesia flux to high alumina iron ore pellets can effectively reduce the adverse effects caused by MgO. This conclusion can provide an important reference for the study of high alumina magnesia pellets.
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LIU Tong, LI Xingwang, ZHANG Junjie, JIA Laihui, LEI Jie, LONG Hongming. Effect of MgO content on strength of high alumina iron ore pellets[J]. China Metallurgy, 2023, 33(10): 17-23.
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2023, Vol. 33 
