MEASUREMENT OF SOLID PARTICLE SIZE DISTRIBUTION AND CONCENTRATION BY A LASER DIFFRACTION TECHNIQUE.

A laser diffraction technique originally devised for determining droplet size distributions in sprays has been further developed in conjunction with Malvern Instruments Ltd. as a generally applicable particle sizing instrument. The technique is non-intrusive and is capable of making 'in situ' measurements in many applications if optical access can be provided. The instrument normally covers a two decade size range for each configuration which may be changed by changing a lens, thus allowing a total range of 1-1800 mu m. Data acquisition takes 10 mu sec with a maximum repetition rate of 30 Hz which allows time histories of particle size and concentration to be obtained. The theoretical background and experimental application of the technique are described and results are presented for a variety of solid particulate systems. The effect of particle shape is discussed and is illustrated with reference to crystal samples of various shapes. 10 refs.