On-line Measurement of Particle Size and Shape using Laser Diffraction

Abstract

Particle size and shape play an important role during particle formation and processing as they affect directly the quality of the intermediate and final products. Therefore, appropriate monitoring and control of these processes, preferably using in- or on-line instruments, are much needed in the modern powder industries. Compared with other particle sizing techniques, laser diffraction has the advantage of high speed, good reliability and high reproducibility, it is increasingly applied for particle sizing in many powder processes. Since shape information can be subtracted from azimuthal light intensity distributions, laser diffraction can also be applied for shape measurement. This paper describes a newly developed technique in laser diffraction using a CMOS pixel array. The advantages to use this pixel array are–direct measurement of scattering pattern is possible with its high dynamic range;–the detection areas are easily adjustable to give optimum or high-resolution results for different particle sizes and shapes, and offers more flexibility for the application;–the instrument is robust in operation as no alignment is required. This technique has been applied to measure the crystal particle size and shape in crystallization processes and improve operation control in a jet mill grinding system. The overview of the results is presented to address the feature using this technique.