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ON-LINE DETERMINATION OF ALUMINA PARTICLE SIZE IN BAYER LIQUORS USING ULTRASONIC TECHNIQUES

Coghill, P.J. and Sowerby, B.D.

The CSIRO Division of Minerals is developing two new methods for determining the particle size distribution of fine particles in industrial processes. The methods involve measurements of either ultrasonic attenuation or velocity over a range of ultrasonic frequencies combined with gamma-ray transmission. The ultrasonic attenuation method is best suited to particles larger than about 10 microns and the ultrasonic velocity method to finer particles. Laboratory measurements are reported for the ultrasonic attenuation method on alumina suspensions in both water and caustic solutions. Both methods of particle size analysis have the potential to be developed into on-line immersion gauges for Bayer plants.