Interfacial reaction between humic acid and Ca-Montmorillonite: Application in the preparation of a novel pellet binder

Abstract

Abstract In this study, a comparative study of adsorption characteristics of humic acid (HA) onto Ca-montmorillonite and Na-montmorillonite were carried out to guide the preparation of a novel composite binder for iron ore pellets, namely humic acid modified bentonite (HAMB). Using Ca-montmorillonite (Ca Mt) as a representative, the adsorption mechanisms of HA onto montmorillonite were studied by XRD, zeta potential, FTIR and XPS analyses. The results indicated that HA was adsorbed onto Ca Mt mainly via complexation and H-bonds. The DFT calculation and molecular dynamics simulation were also carried out to further determine the adsorption mechanisms of HA onto Ca Mt. Molecular dynamics simulation analyses showed that the complexation reaction between carboxyl, hydroxyl groups of HA and Ca ions in Ca Mt is dominant in HA adsorption. And the pelletizing experiments indicated that the HAMB binder prepared at a pH value of 7 had excellent application effect in iron ore pelletization.