A further study on the interaction between one of organic active fractions of the MHA binder and iron ore surface

Binder is essential in the iron ore agglomeration. Fulvic acid (FA) is one of organic active fractions of the MHA binder. A further study of the interaction between FA and iron ore surface was conducted via elemental analysis, chemical group analysis, batch adsorption experiments, X-ray photoelectron spectroscopy (XPS) investigation, zeta potential measurements and scanning electron microscope (SEM) imaging. It is found that the adsorption amount of FA onto iron ore surface obviously increases with increasing the solution pH. X-ray photoelectron spectroscopy (XPS) analysis indicates that ligand exchange (coordination) as a special chemical adsorption occurs at the interface of iron ore and FA. Zeta potential results display that the adsorption of FA onto iron ore surface can be characterized by specific ligand exchange and electrostatic forces. Scanning electron microscope (SEM) imaging shows that flocculation sedimentation is observed during the adsorption process. Ball-shaped FA–mineral colloidal complex with a diameter of 20–100 μm is presented in the SEM micrograph of FA-coated mineral granules. Ligand exchange, hydrophobic interactions and electrostatic force are contributive to the adsorption, with ligand exchange and hydrophobic interactions predominant.

► Adsorption amount of FA onto magnetite granules increases as solution pH increases.
► Flocculation sedimentation is accompanied with the FA adsorption onto magnetite.
► Ligand exchange makes charge of magnetite surface reverse.
► A real picture of magnetite–FA colloidal complex is presented in the SEM micrograph.
► Ligand exchange, hydrophobic and electrostatic attraction dominates the interactions.