Reducing bentonite usage in iron ore pelletization through a novel polymer-type binder: Impact on pellet induration and metallurgical properties

Abstract

Bentonite causes a severe decrease in total iron grades (TFe) of pellets, requiring effective organic binders urgently to reduce its dosage in pelletizing. However, the consolidation mechanism of pellets remains unclear when partially replacing bentonite with organic binders. Herein, the effect of a novel polymer-type binder (PTB) on the oxidative consolidation and metallurgical properties of pellets after reducing bentonite dosage is investigated. Compared to pellets with 2.0 wt% bentonite (configuration I), pellets with 1.0 wt% bentonite and 0.01 wt% PTB (configuration II) facilitate oxygen laminar diffusion due to the porous structure resulting from PTB's decomposition, leading to better oxidation and larger average hematite grains (4.31 μm). After preheating at 1000 °C for 11 min, configuration II reached an excellent cold compressive strength (CCS) of 556 N/p. Despite the lower CCS of roasted pellets in configuration II compared to configuration I due to reduced silicoaluminate slag bonding, it still reached 2879 N/p after roasting at 1250 °C for 11 min. Moreover, configuration II exhibits a superior TFe grade (64.35 wt%) and reduction index (67.92 wt%), making it more suitable for industrial production. This work is expected to offer valuable support for the development and application of polymer-type binders.

Keywords

• Pellets
• Bentonite
• Polymer-type binder
• Oxidative consolidation behavior
• Metallurgical properties