Lucideon Develops Custom PSD Analysis Method

Background

Many industrial operations and products rely on processing powder slurries. Knowledge and control of the particle size distribution (PSD) in slurries is critical to ensure consistent down-stream processing. For example, changes to PSD can impact on suspension viscosity and so the ability to pump the suspension around the factory or spray dry the suspension. Whilst laser diffraction is the analytical technique of choice for many powders or powder suspensions in the 0.1-2000 um size range, a different approach is needed for broader size ranges.

The Challenge

A client approached Lucideon for help with their PSD analysis.  The particle size range extended beyond typical parameters (it contained sub 0.1µm fractions and fractions larger than 2000µm (2mm)).  The client required knowledge of their slurry’s PSD to assess the effects of particle size on their product.  They needed a test which would be reproducible, easy to perform and reliable.  Lucideon was asked to develop an effective system whereby the whole range of the particle distribution could be accurately measured.

What We Delivered

Laser diffraction is incompatible with particle sizes above 2000um. In this case, a protocol was developed to sieve out material above 2000 um into different size fractions. By weighing the total oversize material (and knowing the specific gravity of the material) and performing sieve separation between 2000 um and the upper size fraction, a vol% particle size distribution (PSD) can be generated. This PSD can then be stitched onto the sub-2000um material PSD recorded by laser diffraction.

For particles below ~0.1 um in size there was a similar, although perhaps less critical, issue. Laser Diffraction generates a PSD below 100 nm (0.1 um) but the quality of data is questionable. There are superior analytical techniques available for accurately measuring nano-size particles.  400 nm syringe filters were used to produce a suspension containing only nano-particles. Using dedicated nano-sizing techniques reliable nano-particle size distributions are created. Once again these can be stitched onto laser diffraction distributions.

Value to Client

Lucideon was able to provide an effective system of achieving reliable PSD measurements of the client’s material.  This allowed the client to better regulate their materials to ensure that the right particle distribution was present when mixing into a slurry.  Having the right material from the start made the downstream processes more consistent, reducing issues in the process and the final product.

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