An Investigation into the Pelletizing Performance of Blends Comprising Brazilian Hematite and Chinese Magnetite Concentrates

Abstract

The carbon emissions from the pelletizing process are much lower than those from the sintering process. Moreover, increasing the proportion of fired pellets in the feedstock fed into the blast furnace can reduce carbon emissions, augment the capacity (the ability of a blast furnace to produce molten iron using the same weight of iron ore) and decrease slag generation. Therefore, much more attention has been paid to the pelletizing process. However, the shortage of high-quality feeds remains a bottleneck in the pelletization industry. Supplying more hematite for fired pellet production is of significant importance. In this study, the physicochemical properties and mineralogical characteristics of Brazilian hematite concentrate (BHC) were systematically analyzed. We simulated the traveling grate process and investigated the effect of BHC dosage on the balling behavior of mixed concentrates, the firing performance of the dry balls and the metallurgical properties of the fired pellets. The results indicate that substituting 20–30% BHC with magnetite concentrates improves the drop number and thermal stability of green balls with a slightly higher dosage of bentonite. The firing characteristics of the dry balls and the reduction index and reduction degradation index of the fired pellets were enhanced, although a slightly adverse effect on the reduction swelling index of the fired pellets was observed. Overall, the mechanical and metallurgical properties of the fired pellets can meet the requirements for blast furnace operations. Substituting magnetite concentrates with 20–30% hematite concentrate in the traveling grate for the pelletization process is technically feasible.