Comparison and Mechanism Analysis of Three-Phase Contact Formation onto Hydrophilic/Hydrophobic Mineral Surfaces in the Presence of Cationic/Anionic Surfactants during Flotation Process

Xianyuan Li,Mei Li,Guoyuan Xiang,Jiahui Xie,Ya Gao,Hao Jiang

doi:10.3390/min12020219

Abstract

This article presents the dynamic process of the three-phase contact (TPC) formation by colliding bubbles onto muscovite and talc surfaces in water and two types of solutions including cationic CTAC surfactant (cetyltrimethyl ammoniumchloride) and anionic NaOL surfactant (sodium oleate). The TPC formation process was observed through the high-speed camera between bubbles and layered silicate minerals (hydrophilic muscovite and hydrophobic talc). It was found that the rupture of the liquid film between the bubbles and the mineral surface is a prerequisite for TPC formation. In the case of muscovite, TPC was formed only with cationic CTAC, and as the surfactant concentration increased, the time needed for TPC formation was shortened. Due to electrostatic repulsion, TPC did not occur in water and NaOL. However, for talc, TPC occurred both in water and in surfactant solutions. In contrast to muscovite, the time of TPC formation on the talc surface was prolonged with the increase in the surfactant concentration. It was concluded that hydrophobic attraction and electrostatic attraction between mineral surfaces and bubbles can significantly promote the localized foam film rupture, which was the main reason for the TPC appearance in water and surfactants. For the hydrophilic muscovite, CTAC adsorption improved the surface hydrophobicity; I3/I1 in fluorescence spectroscopy increased, and the micro-polarity faded, making TPC formation need more time. However, for the natural hydrophobic talc, the increasing surfactant adsorption decreased I3/I1 values and enhanced the local micro-polarity, causing the extension of time for TPC. Therefore, TPC formation for different minerals resulted from different reasons.

Highlights

In the froth flotation beneficiation method, the interaction between mineral particles and bubbles is a primary process for collecting valuable components
This research work systematically studied the dynamic process of the three-phase contact formation by colliding bubbles onto muscovite and talc surfaces in water and solutions of two surfactants, cationic cetyltrimethylammonium chloride (CTAC) and anionic
The following major conclusions were drawn from the detailed study: 1. The increasing concentration of CTAC reduced the aspect ratio (AR) of the rising bubble, making it closer to the sphere

Summary

Introduction

In the froth flotation beneficiation method, the interaction between mineral particles and bubbles is a primary process for collecting valuable components. The more hydrophobic the mineral surface, the more unstable the liquid film, the more prone it is to rupture, and the more likely it is that TPC will form. In the case of hydrophobic minerals, the repulsion force was presented in pulp according to the DLVO theory (Derjaguin–Landau–Verwey–Overbeek theory), the liquid film was still very easy to break. This phenomenon has been explained by Deryagin et al [5] through the nucleation mechanism

Methods

Results

Discussion

Conclusion