Particle Size

Particle Size Analysis

Determination of the particle size distribution of a sample

Which analytical method is used to determine the particle size distribution of a sample depends strongly on the source material and the general question. For example, a sieve tower with inserts of different mesh sizes is a good choice if you are interested in a quantitative analysis of particles ranging from < 63 mm (coarse gravel) to > 20 µm (medium silt) in diameter. For an analysis of the fine silt and clay fraction of a rock or sediment sample, however, other methods must be used, as conventional sieves would ultimately only become clogged with the fine particles. Analyses using laser diffraction or acoustic spectroscopy on well-dispersed suspensions are widely used methods. In our laboratory, we use acoustic sensors to analyse the particle size distribution. The advantage here is on the one hand the large measuring range of particle sizes (5 nm to 1000 µm) and on the other hand the possibility to calculate further rheological parameters such as longitudinal viscosity, compressibility or modulus of elasticity from the raw data.

Figure 1: This graph illustrates the particle size distribution of the clay fraction of a sediment sample with particles ranging from 0.1 to 5 µm. The cumulative volume in vol.% of the analysed sample is plotted as a function of particle diameters in µm determined by acoustic spectroscopy. The curve reflects a bimodal particle size distribution.

Applications

Particle size distributions are important parameters for finding the right material for your application. For example, the rheological properties of clay suspensions are related to the particle size distribution in addition to the general mineralogical composition. If your samples show bimodal particle size distributions, very small particles can occupy the space between larger particles, so that the rheologic properties change significantly compared to unimodal distributions. Below are some other applications of particle size distribution analysis:
  • Quality control in the preparation of raw materials
  • Analysis of particle sizes of additives for building materials and fillers
  • Determination of rheological properties of suspensions
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