The many measures of fine particles

Abstract

Particle size is a critical parameter for a variety of operations in the chemical process industries (CPI). For example, the flow characteristics of granular materials, the sintering behavior of metallurgical powders, and the combustion efficiency of powdered coal are influenced to a major extent by particle size. The big push in the ceramics industry today is toward processing of powders at or below the one-micrometer level because use of such fine-grained materials allows tighter control of product properties. Accurate measurement or estimation of particle size is important because the quality and performance of most powder-based products are closely related to the size distribution of the fine particles. The electro-optic data processing revolution has spawned a new generation of particle-characterization equipment based on laser probing of particles systems. Computer-aided analysis of the data has come to play a dominant role. The paper discusses the critical step of sampling, the use of sieving for larger particles, the significance of particle shape, the use of lasers in size classifiers, particle surface properties, permeability techniques, and the need for instrument calibration.