The Preheating and Roasting Properties of Fluorine-Bearing Iron Concentrate Pellets and Main Influence Factors

This study addresses the challenges associated with fluorine-bearing iron concentrate pellets, particularly their unfavorable roasting properties at elevated temperatures, limited roasting temperature ranges, and low compressive strength of the resulting products. The objective was to identify methods to enhance these properties. Through experimentation, it was found that extending the preheating duration significantly improved the compressive strength of both preheated and roasted pellets. Moreover, the presence of calcium fluoride in the iron concentrate led to the formation of a liquid phase during roasting, with the amounts reaching 13% and 16% at temperatures of 1100 °C and 1250 °C, respectively. An increase in liquid phase content correlated with a decrease in the compressive strength of the pellets at higher roasting temperatures. Notably, the addition of chromite was found to significantly enhance the roasting characteristics, with the compressive strength reaching 3100 N/P when 2% chromite was included at a roasting temperature of 1150 °C, yielding an increase of 700 N/P compared to the pellets without chromite, and expanding the feasible roasting temperature range by 170 °C.