Flotation Performance Monitoring By Acoustic Emissions

This project has provided proof-of-concept for monitoring of washery Jameson cell and Microcel column process state by passive acoustic emission (AE) methodology. Successful trials of an AE monitoring system developed at CSIRO were undertaken on a Jameson cell at Mt Thorley-Warkworth washery and a Microcel column at Peak Downs washery. Both surface and volumetric AE sensors distributed in and around the pulp and froth regions of each cell recorded AE responses linked to bubble characteristics. These AE characteristics were found to strongly vary with operating conditions such as aeration rate, frother and collector addition and for the Microcel column, wash water addition rate. The characteristics of the AE signals are strongly varying with monitoring location.

In general, this study finds that passive AE signatures sensed in washery flotation cells may be interpreted to determine bubble- and solids-related process characteristics including:

· Pulp bubble size distribution;

· Froth stability;

· Froth/pulp interface height;

· Total solids concentration in the concentrate and tailings; and

· Ash content in the concentrate and tailings.

It is recommended that passive AE be further investigated and developed as an on-line process performance monitoring tool for both Jameson cells and Microcel columns in Australian coal washeries. For particular process performance variables this may require further model formulation and validation, some of which can be achieved in the laboratory and some requiring further plant work. An investigation of AE monitoring of mechanical flotation cell performance may also be fruitful.