Effects of Interfacial Hydroxylation Microstructure on Quartz Flotation by Sodium Oleate

Area of Science:

• Mineral processing and beneficiation
• Surface chemistry of inorganic materials
• Computational materials science

Background:

• Quartz flotation typically involves beneficiation processes like froth flotation.
• Quartz's inherent surface polarity leads to hydroxylation, hindering flotation with collectors like sodium oleate (OL) alone.
• Pre-activation with Ca2+ followed by OL collection is an established method for quartz flotation.

Purpose of the Study:

• To investigate the influence of surface hydroxylation on sodium oleate (OL) adsorption on quartz.
• To elucidate the adsorption mechanisms before and after Ca2+ activation using computational methods.
• To understand the role of Ca2+ in improving the flotation of hydrophilic quartz.

Main Methods:

• Density functional theory (DFT) calculations were employed to model quartz surface interactions.
• Analysis of adsorption thermodynamics and binding mechanisms of OL- on hydroxylated quartz.
• Investigation of Ca2+ adsorption and its effect on subsequent OL- adsorption.

Main Results:

• Thermodynamically unfavorable displacement adsorption of OL- by surface hydroxyl groups was observed.
• OL- adsorption on hydroxylated quartz occurs weakly via hydrogen bonding to surface hydroxyls.
• Ca2+ ions adsorb readily onto the hydroxylated quartz surface, creating active sites for enhanced OL- adsorption.

Conclusions:

• Surface hydroxylation significantly weakens OL- adsorption on quartz due to electrostatic repulsion and steric hindrance.
• Ca2+ activation provides a viable mechanism to overcome these limitations, facilitating effective quartz flotation.
• The findings offer fundamental insights into the flotation of hydrophilic oxide minerals, aiding process optimization.