Consolidation mechanism of fluxed hematite pellets

Fluxed pellets are becoming a popular burden for the blast furnace in China. The basicity (wCaO/wSiO2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$w_{\text{SiO}_2}$$\end{document}) ranging from 0.33 to 1.33 was prepared by adding CaO analytical reagent. The phase change of pellets during roasting was analyzed by the FactSage software, and the consolidation mechanism of fluxed hematite pellets was also investigated. The results show that the increase in basicity gradually increases the diameter, volume, and porosity of pellets. The diameter, volume, and porosity of pellets change slightly when the basicity is greater than 0.83. The increase in roasting temperature gradually decreases the volume and porosity of pellets. With the increase in pellet basicity, the compressive strength of pellets reaches the maximum at the basicity of 0.83. The higher the roasting temperature is, the more the slag phase is produced, thereby accelerating Fe3+ diffusion and promoting Fe2O3 recrystallization. In addition, the consolidation effect of the slag phase after cooling improves the consolidation strength of fluxed pellets. When the basicity is higher than 0.83, the slag phase decreases with the increase in basicity, and the high-temperature solid solution, such as melilite and spinel, increases, thereby hindering Fe2O3 recrystallization.