Introduction

Abstract

A great variety of industrial products is based on particulate materials. Behavior and performance of such products depend upon particle size and shape in the base materials, in addition to chemical and structural characteristics. An overview of the major production and handling processes of particulate materials as well as the basic characteristics for their design, monitoring and control is presented in this book. It is meant to facilitate easy comparison and good choices of production and handling processes and of equipment. Topics for particulate production comprise size enlargement – crystallization, precipitation, granulation and extrusion – as well as size reduction, viz. comminution, atomization and emulsification. In the chapters on handling, mixing and segregation, filtration and sedimentation, flotation, classification, storage and transport are discussed. The quality of batches of base materials and products is assessed through measurements in samples. Adequate care of the sampling process to obtain representative samples is required, especially in cases where the batches show segregation, i.e. when the composition is different at different locations in the batch. Then, deviations in non-representative samples may be substantial. The quality of products is often described in terms of PSD parameters in addition to descriptors that are more closely related to behavior. Unfortunately, the choice of PSD parameters is often made without good reasoning, causing the chosen parameters to be sub-optimal. Therefore, suggestions are given for optimum choices. The behavior of bulk powders and concentrated dispersions depends in addition to particle characteristics upon the degree of particle packing and the inter-particle forces, and for dispersions also upon the particulate concentration, the surface type and the zeta-potential. Optimum rheological behavior of such concentrated systems, powders as well as liquid dispersions, is of prime importance, during processing as well as for product quality. Some examples are presented for the parameters that have an empirical relationship to practical situations. The choice of PSD parameters that are typically used for control of processes is easier than that for product quality, since usually only adequate repeatability and instrument robustness are important for good control. This chapter gives an introduction to the general background and the challenges of selecting adequate processes and to the relevant particulate parameters.