Dispersed/flocculated size characterization of alumina particles in highly concentrated slurries by ultrasonic attenuation spectroscopy

In recent years, several advances have been made in ultrasonic attenuation spectroscopy for monitoring particle size distributions of highly concentrated slurries. This paper presents experimental proof that ultrasonic attenuation spectroscopy is capable of characterizing dispersed or flocculated particle size in highly concentrated slurries. Well-characterized alumina was used for testing the theory. The instrument for measuring ultrasonic attenuation spectra covers a wide frequency range from 1 to 100 MHz and converts them into particle size distributions. It is shown that the particle size distribution obtained before sonication indicates a bimodal distribution, but that after ultrasonication the distribution is reduced to a log-normal for which the median size agrees quite well with a priori known particle size. Hence we confirmed that this technique can differentiate well-dispersed and flocculated particle size in slurries without dilution. (C) 1998 Elsevier Science B.V. All rights reserved.