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Considerations for steering particle size

28 July 2011 No Comment

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Through this blog you will find postings that talk about how particle size influences product quality: the bioavailability of a drug; the stability of a paint; and the mouth feel of chocolate; for example. Many manufacturing sectors monitor and control particle size to reach product quality goals, and focusing on product performance is clearly critical.

Reading through a recent article though,  ‘Considerations for Steering Particle Size’, by Roger A. Barnum and James K. Prescott of Jenike & Johanson, Inc, I was reminded of a closely related but somewhat separate reason for measuring particle size which is to control and optimize in-process behavior.

Control particle size, control the process

There is a tendency to insufficiently scrutinize the effect of particle size on the overall performance of a powder processing system because of the lack of clear understanding of the impact of particle size on process behaviour. It is common knowledge, however, that particle size has an influential role in all sorts of potentially troublesome process behaviour, including:

  • Powder flow
  • Segregation
  • Fluidisation
  • Dusting
  • Build-up and blinding during sizing operations

‘Considerations for Steering Particle Size’ provides an excellent rationale for measuring particle size and analyzing the interactions of powder and process, in an effort to minimize potential manufacturing problems. Laser diffraction systems, such as the Insitec from Malvern Instruments can certainly help here and may, in some cases, allow the automatic control of production to avoid the problems that can come from a failure to properly appreciate the importance of particle size. Problems that can include: compromised yield, efficiency and throughput, excessive manual intervention, product loss, poor product uniformity and housekeeping issues.

Find out more

One of our customers, Norsk Hydro has done some interesting work in this area, looking at how changes in alumina particle size distribution impact control of the smelting process, so if you are interested in finding out more this could be a good starting point. Alternatively we are happy to hear about any of the challenges you face in processing – we’re always happy to help if we can.