Introduction

Bubble-particle capture is the heart of froth flotation. For efficient capture to occur between a bubble and a hydrophobic particle, they must first undergo a sufficiently close encounter, a process that is controlled by the hydrodynamics governing their approach in the aqueous environment in which they are normally immersed. Should they approach quite closely, within the range of attractive surface forces, the intervening liquid film between the bubble and particle will drain, leading to a critical thickness at which rupture occurs. This is then followed by movement of the three-phase-line contact line (the boundary between the solid particle surface, receding liquid phase and advancing gas phase) until a stable wetting perimeter is established. This sequence of drainage, rupture and contact line movement constitutes the second process of attachment. A stable particle-bubble union is thus formed. The particle may only be dislodged from this state if it is supplied with sufficient kinetic energy to equal or exceed the detachment energy, i.e. a third process of detachment can occur.

The capture (or collection) efficiency E of a bubble and a particle may be defined as:

E=ECxE«xES

This article describes each of the substeps in the bubble-particle capture process. The individual processes and efficiencies are focused upon, since they provide the key to understanding the substeps. Our knowledge of the various efficiencies has been enhanced by six important publications, referred to in Table 1, each of which signalled major advances in our understanding and catalysed further research in this interdisciplinary field of colloid and flotation science.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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