Particle Technology and Characterisation

Particle Technology
Professor Richard Holdich
R.G.Holdich@Lboro.ac.uk
Watch this lecture at http://www.vimeo.com/9936959.
Also visit; http://www.midlandit.co.uk/particletechnology.htm for further resources.

Format
1 Lecture per week,
1 Problem Class – tutorials & self study
1 hour on: Moodle/Learn – tutorials & self study
Laboratories (oral, report & experimental)
Two hour exam (75% module mark)

Exam
Two hour exam
3 questions from 5
Question 1 obligatory PSD
Previous answers old papers on Learn
Tutorial problems (& book on:www.particles.org.uk)

Lecture topics
Particles & Characterisation
Dilute particulate systems
Hindered systems
Fluid flow in porous media/Fluidisation
Filtration
Membranes & colloids
Emulsions, surfaces & dispersions
Centrifugal separation
Two phase flow, rheology & powders
Gas cleaning
Comminution & mixing

Problem Classes
See:
http://learn.lboro.ac.uk/
www.particles.org.uk
References:
614.83 , 620.43, 621.54, 660.283 & 660.2842
Coulson & Richardson Vol 2;
Fundamentals of Particle Tech – free pdf book
Rhodes, Introduction to Particle Technology

Particles & Characterisation
Introduction to Particle Technology
Equivalent spherical diameters
Shape factors
Specific surface area
Size ranges and grades
Normalised distributions
Particle size analysis

What is Particle Technology?
Study, characterisation, prediction of properties during the processing of particle dispersions ranging down to sub-microscopic material. It is the extension of mechanics (fluids and solids) into particle containing systems. The term 'particles' includes liquid emulsions, drops, foams, oils, dusts, bubbles, fogs, etc…
N.B. The definition of a micron, and
human hair is 70 microns,
blood cells are 8 microns,
bacteria are bigger than 0.2 microns
- all are particles

What’s the problem?
Viscosity
Density
Molecular size
Heat capacity
Flow regime
Easy to define for a fluid
How do these change with particles?

To equate some property of the irregular shaped particle to a sphere with the same property, e.g. same volume as particle:
Has the same volume as a sphere - hence:
Note use of x for diameter.

It is possible to measure volume of a particle by displacement, or electrical resistance of suspension, and equate to that of sphere of same volume.
Some other equivalences include projected area, surface area and mass

Shape factors
Volume of a sphere:
Hence volume shape factor is:
The volume shape factor for a cube is?

Specific surface
Specific surface area per unit volume - usually abbreviated to specific surface is the surface area over volume:
Hence Sv=6/x as is commonly used.
Use density to convert to SMASS

Median size 9.2 m
Specific surface: 0.944x105 m-1
Sauter mean diameter: 6.4 m

All techniques measure property and relate it to the equivalent spherical diameter.
Select your technique to be the most appropriate for the end use of the data.
The Coulter Counter
The image above is provided by Beatop (OMEC) Instruments Limited. As found at Beatop (OMEC) Instruments Limited http://www.beatop.com/Particle_Counter/principle_illustration.html

Malvern
Sedimentation/Sedigraph

Summary
Shape factors
Specific surface area

Particle Tech Labs
Think design not laboratory
Problem given by boss
Might use Perry, C&R 6, etc.
But lab exp to check model, equations…
Model could be good, just your material…
Report to boss ‘model no good’ is NOT GOOD ENOUGH, so what – we still need it

Particle Tech Labs
So, design is it over or under?
Does dodgy model matter?
How to improve MODEL, not experiment
2nd week, you tell us what you want to do
Repeating experiments only checks on reproducibility of experiment, nothing else
Data analysis – assume data until known

Particle Tech Labs
References, use Harvard system and minus 6 marks for a Bibliography rather than a Reference section – minus 4 for no references at all. For example,
Bloggs, F., 2008, An anti-gravity machine, Journal of Good Ideas, 123, pp 22-33.
Orals: use PICTURES, do NOT derive equations. Do show flow diagram, etc.

This resource was created by Loughborough University and released as an open educational resource through the Open Engineering Resources project of the HE Academy Engineering Subject Centre. The Open Engineering Resources project was funded by HEFCE and part of the JISC/HE Academy UKOER programme.
© 2009 Loughborough University
This work is licensed under a Creative Commons Attribution 2.0 License.
The name of Loughborough University, and the Loughborough University logo are the name and registered marks of the Loughborough University. To the fullest extent permitted by law the Loughborough University reserves all its rights in its name and marks, which may not be used except with its written permission.
The JISC logo is licensed under the terms of the Creative Commons Attribution-Non-Commercial-No Derivative Works 2.0 UK: England & Wales Licence. All reproductions must comply with the terms of that licence.
The HEA logo is owned by the Higher Education Academy Limited may be freely distributed and copied for educational purposes only, provided that appropriate acknowledgement is given to the Higher Education Academy as the copyright holder and original publisher.

Particle Technology and Characterisation

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