Abstract
M.Sc. (Geology)
Particle size and shape are the most important properties when dealing with particulate materials. Laser diffraction and 2D image analysis are most commonly used to determine particle size distribution (PSD). These methods may introduce potential errors, since the particles are three dimensional.
The shape of the particles, in particular, may result in the difference in particle size distribution between particle sizing techniques as each technique uses its own physical properties to estimate size.
The aim of the study was to research the difference in particle size distribution (PSD) between 2D and 3D with different size fractions and demonstrate the effect of shape in these measurements. A quartz sample was classified into different size fractions and analysed using Laser diffraction, QEMSCAN (2D automated image analysis) and X-Ray Microscope (3D automated image analysis).
The measurement results from this study demonstrate that with automated image analysis, there is a good correlation in particle size distribution between 2D and 3D data when the size is based on the equivalent (circle or sphere) diameter data irrespective of the shape of the particles. However when the longest (length) and the shortest (width) dimensions of the particles are used to measure the size of the particles, the samples that consist of high aspect ratio particles give poor correlation in particle size distribution between 2D and 3D data and this is due to the favoured orientation of high aspect ratio particles in the polished blocks.
A spherical sample consisting of glass beads was used in this study to further validate the Laser diffraction and the XRM techniques, this is a standard sample normally used for the calibration of the Laser diffraction instrument. Correlation between Laser diffraction and X-Ray Microscope (XRM) based on equivalent spherical diameter (ESD) is poor with high aspect ratio particles; however the correlation is good when the particles are spherical.
Good correlation between 3D and 2D data implies that the 2D measurements are giving the correct results, the statistics are sufficient and the techniques are compatible.