Preheating Behaviors of Iron Ore Pellets with Humic Substance-Based Binder

Abstract

Humic substance-based binder (HB) has been found to be an effective substitution for bentonite in the production of iron ore pellets. In this study, it was found that the preheating time needed to be prolonged during the pelletization processing which is a remarkable feature of pellets with HB instead of bentonite. As far as the oxidation behaviors were concerned, a manifest oxidation hysteresis platform was observed in the FeO content vs. preheating time curve during the second minute in the preheating process, which implied that the emission of humic substance noticeably interfered with oxidation process pellets. Consequently, in contrast to bentonite, the magnetite phase could not be completely transformed into hematite until the preheating time reached 16 min. Meanwhile, the SEM-EDS analysis showed that the crystal grains of preheated pellets with HB were well interconnected when the preheating time was 16 min. This also verified that the optimal preheating time of pellets with HB (16 min) was longer than that of pellets with bentonite (10 min).