By measurement and control of particle size distribution one can control product and particle behaviour. Process control of powder products is highly dependent on particle size. Generation of dust can be reduced by size control, improved powder conveying can be obtained, less wastage can be achieved by reducing the amount of under and over-size product. The size and size distribution of fine powders affects product end-use in many important ways. For example, it determines the setting time of cement, the hiding powder of pigments, the activity of chemical catalysts, the efficacy of drugs and the taste of chocolate.
Representative samples are crucial in obtaining accurate size data.
The quality of many tons of material may be assessed on the basis of measurement taken on milligram samples. The objective of this course is to give participants an understanding of the available measurement techniques and their capabilities, how to present and interpret data and the limitations of commercial equipment including accuracy and reproducibility. Measurements made on a sample containing a few milligrams of powder are often used to define a bulk consisting of many tons. It is essential that the sample is representative of the bulk. In this lecture we will cover the requirements for obtaining a representative sample from stationary and from moving streams of powders.