Experimental Compressive Strength and Microstructure Analysis of Magnesium Fluxed Pellets

Abstract

In this paper, Zhong Guan iron ore is used as raw material. By adjusting the content of lime, raw magnesium powder and bentonite, the effect law of different SiO₂, MgO content and alkalinity on the compressive strength of pellet ore under low silicon conditions was studied, And the pellet strength change law was systematically analyzed from the microscopic morphology and structure perspective. The results of the study show that increasing the roasting temperature and alkalinity can effectively improve the compressive strength of pellets. At low SiO₂ content, the pellet ore is mainly cemented by hematite continuous crystals and the change in strength is not obvious. With the increase of alkalinity, the amount of liquid phase of low silicon flux pellets increases during roasting, and the liquid phase of calcium ferrite system with strength higher than hematite eutectic appears, which improves the pellet strength; With the increase of MgO mass fraction, magnesium ferrite increases, which not only inhibits the formation of liquid phase in pellets, but also inhibits the oxidation of magnetite. Because the strength of magnesium ferrite system is greater than that of magnetite and hematite, the pellet strength increases, but too much magnesium ferrite will also affect the liquid phase bonding inside the pellet, lead to structural deterioration and reduce the pellet strength. Therefore, the compressive strength of pellet increases first and then decreases. The above study provides theoretical guidance and reference for the investigation of low-silica magnesia fluxed pellets.