Flotation Froth Phase Bubble Size Measurement

In this work, methods to measure froth phase bubble sizes in mineral froth flotation are reviewed. For each method, the state of development, the equipment set-up, bubble size estimation procedure, and the pros and cons are discussed. Further, techniques that have typically been applied in the study of foams in non-mineral processing fields that have a potential for use in the study of bubble sizes in mineralized froths are also discussed. The review shows that flotation machine vision is available for industrial froth phase bubble size estimation. It, however, provides bubble sizes on the surface of the froth only i.e. the so-called surface film distribution. Surface film distributions are suitable for process control and grade estimation but are limited in quantitative modeling of important froth performance measures such as water recovery. The conventional photographic method (videoing from the sides of a transparent vessel) is limited to laboratory settings or transparent systems and is therefore typically used for calibrating other bubble size measurement methods. Methods to overcome the need for transparent systems and to measure bubble sizes within the froth/foam have also been suggested. These methods include those based on electrical, optical, and magnetic resonance properties of foams. Most of these methods have either not been tested in an industrial setting or the assumptions adopted to reconstruct bubble sizes are unrealistic. These methods require further testing to ascertain their efficacy in flotation froth phase bubble size estimation.