Zeta potential of inorganic fine particle-Na-bentonite binder mixture systems

Abstract

The zeta potential of single and multi-inorganic fine particle mixtures (hematite and gangues, i.e., SiO₂ + Al₂ O₃ ) with Na-bentonite was investigated to understand and properly control the mineral surface properties relevant to pelletization of low-grade fine iron ores. The zeta potential of hematite-bentonite mixture showed more negative charge up to 1 wt.% bentonite dosage and became constant. In the multiparticle mixture systems with bentonite, the SiO₂ amount in the system controlled the changes in zeta potential due to its high negative charge (-54.9 mV at natural pH) and the bentonite attachment on its surface based on the electrostatic interaction while Al₂ O₃ had no effect due to its negligible surface charge (-1.6 mV at natural pH). This article reports the new insight into the characterization of surface chemistry of inorganic/mineral mixture systems to understand their surface charge properties in relation to fine mineral particle processing, and to show a direction toward the elucidation of particle dispersion/aggregation mechanism in complex ore systems aiming for their beneficiations.

Keywords: DLVO theory; Electrostatic interaction; Heterocoagulation; Low-grade ore; Surface charge.