James E. Funk

Particle-Packing Phenomena and Their Application in Materials Processing

Particle packing is directly controlled by the particle-size distribution of a material being processed. For this reason, particle packing is important to all particulate/fluid systems. After the solids fraction of a body is defined, interparticle chemistry controls how the body will pack and flow. A system of powders can never pack better than the maximum possible level defined by the particle-size distribution alone. Proper control of interparticle chemistry however can help achieve maximum packing, can be used to open the structure, and/or can be used to modify rheological or other process properties. The main goals of particle-packing research have been to determine how systems of particles pack, to develop algorithms for calculating packing densities and porosities for any distribution of particles (spherical or nonspherical, rough or smooth, wet or dry), and to determine how packing and its properties affect the variety of industrial operations that utilize particulate/fluid systems.

Viscosity and Rheology

Viscosity and rheology are often confused in the literature although they are significantly different concepts. The viscosity of a fluid or suspension is an indication of its fluidity. “Heavy” or “thick” fluids such as heavy oils, or molasses, are recognized as those having high viscosity. Water, many lubricating and cooking oils, coffee, and tea have low viscosities. Air is a fluid with very low viscosity.

Derivation of the Dinger-Funk Particle Size Distribution Equation

This chapter details the derivation of the three parameter particle size distribution equation shown as Equation 4-5:

Computer Modelling of Particle Packing Phenomena

The previous four chapters reviewed the literature of particle packing, both within monodisperse systems and within polydisperse systems, and showed the similarities between the two foundation equations in the field of particle packing after minor modifications to each. This chapter presents the results of our particle packing computer modelling runs.

Mineral Analysis of Clays

The objectives of this analysis are: 1. Identify the mineralogical analysis of clay samples. 2. Determine the total amount of clay mineral and free quartz in the sample. 3. Determine the particle Shape Factor of a clay sample for use in the PCI program.

Introduction to the Rheology of Crowded Suspensions

Rheology is the study of viscous behavior as a function of shear rate. An atomizer, or a nozzle on a garden hose, for example, is a high shear device. A spoon, with which one stirs coffee, is a low shear device. The behavior of fluids and suspensions over these extremes of shear rate forms the subject of rheology.

Introduction to Predictive Process Control

Predictive Process Control (PPC) is a method for predicting the performance of a crowded particulate suspension by separate measurements of selected fundamental properties of each raw material ingredient before their assembly into a body.

Introduction to Ceramic Forming Processes

Most ceramic articles are formed from some variation of the “wet process” which begins with a fluid, highly loaded suspension of a powder composition containing a very specific amount of colloidal particles. This suspension also contains a process and powder specific chemical additive package which determines the solids content and the rheology of the suspension or the plastic cake. The powders must first be mechanically dispersed (blunged) in a liquid medium which is usually water, but which very frequently is some organic nonpolar liquid.

Test Specifications for PPC Measurements

We believe we have developed methods of separately measuring the effect of particle physics and the rheological response of that powder in suspension. These tests must be further evaluated to increase our confidence that they do indeed predict the plant performance of any body composition prepared into a casting slip.

Porosity and Pore Size Distribution

Two other particle physics parameters of interest are porosity and pore size distribution. They are listed separately and distinctly because they are separate and distinct. Certainly they are related, but they each give different information and they apply to different processing phenomena.