1. PARTICLE SIZE ANALYSIS
Nupoor Agrawal , Shwetanshu Suman
2nd year, Metallurgical and Materials Science Engineering
National Institute Of Technology ,Jamshedpur
Under the supervision of
Professor Ranjit Prasad

2. Table of contents Introduction Methods
How we choose a particular method?
Explanation of methods
Graphical representation of sizing analyses
Applications
References

3. INTRODUCTION
Particle size analysis is the collective name of the technical procedures, or laboratory techniques which determines the size range or mean size of the particles in a powder or liquid sample.
In order to keep manufacturing costs low and to ensure the product itself is of a high quality, the particle size distribution of required material needs to be measured and controlled.
Particle-size analysis helps in increasing the effectiveness of materials being processed in an operation . As oversize materials will cause damage to equipment and slow down production.
 unwanted materials will contaminate products if they are not detected.
Various methods have been discovered till now to do particle size analysis.

4. METHODS FOR DETERMINING THE PARTICLES SIZE
Test sieving
Sedimentation
Laser diffraction
Electro resistance counting
Elutriation
Electron Microscopy
Classification of Powder
d50 Sieve Opening (µm)
Very Coarse
> 1000
Coarse
355–1000
Moderately Fine
180–355
Fine
125–180
Very Fine
90–125

5. How we choose a particular method?
Criteria for selection
Nature of the material to be analyzed like estimated particle size and their range, solubility ,toxicity ,flow ability ,intended use , ease of handling etc.
Economic factors
Specified requirements
Time factors
Methods
Approximate useful range(microns)
Test sieving
100,000-10
Elutriation
40-5
Microscopy (optical)
Sedimentation (gravity)
40-1
Sedimentation (centrifugal)
5-0.05
Electron microscopy

6. Sieve analysis
It is accomplished by passing a known weight of sample successively through finer sieves and weighing the amount collected on each sieve to determine the percentage weight in each size fraction.
The effectiveness of a sieving test depends on the amount of material put on the sieve and the type of movement imparted to the sieve.
Equations used:- % Retained = Wsieve X 100 %
Wtotal
% Passing = W below X 100%
W total

7. Results of a typical sieve test
Sieve size range (µm)
Sieve wt fractions(g)
Sieve % wt fractions
Nominal aperture size (µm)
Cumulative % undersize
Cumulative % oversize
+250
0.02
0.1
250
99.9
1.32
2.9
180
97.0
3.0
4.23
9.5
125
87.5
12.5
9.44
21.2 90
66.3
33.7
13.10
29.4 63
36.9
63.1
11.56
26.0 45
10.9
89.1
-45
4.87

8. Sedimentation method
A single solid sphere settling in a fluid has a terminal velocity which is related to its diameter.
Terminal velocity of a particle in a fluid increases with size.
Stokes's Law :
It is based on the measurement of the rate of settling of the powder particles uniformly dispersed in a fluid .the principle used is beaker’s decantation.

9. Laser diffraction method
Laser diffraction analysis, also known as laser diffraction spectroscopy, is a technology that utilizes diffraction patterns of a laser beam passed through any object ranging from nanometres to millimetres in size to quickly measure geometrical dimensions of a particle.
This process does not depend on volumetric flow rate, the amount of particles that passes through a surface over time.
The angle of diffraction increases as particle size decreases and so the method is best for measuring ultrafine particles.

10. Electroresistance counting
It measures the momentary changes in the conductivity of a liquid passing through an orifice that take place when individual non conducting particles pass through.
The particle count is obtained by counting pulses ,and the size is dependent on the size of each pulse. Example :-coulter counter
A Coulter counter  is an apparatus for counting and sizing particles suspended in electrolytes. It is used for cells, bacteria, prokaryotic cells and virus particles.

11. Elutriation
Elutriation is a process for separating particles based on their size, shape and density, using a stream of gas or liquid flowing in a direction usually opposite to the direction of sedimentation. 
All elutriators consist of one or more “sorting columns” in which the fluid is rising at a constant velocity.
 The smaller or lighter particles rise to the top (overflow) because their terminal sedimentation velocities are lower than the velocity of the rising fluid.
The terminal velocities of any particle in any medium can be calculated using Stokes' Law if the particle Reynolds number is below 0.2.

12. Graphical representations of sizing analyses

14. Applications
The coulter counter technique has been used to diagnose a variety of diseases, and is the standard method for obtaining red blood cell counts (RBCs) and white blood cell counts (WBCs).
The laser diffraction technique is used to observe distribution of sediments such as clay , mud, with an emphasis on silt and the sizes of bigger samples of clay.
 particle size distribution can change mechanical, transport and densification properties of ceramics accordingly as per the requirement.
polystyrene a type of plastic requires particle size analysis.
 the Coulter Principle has been adapted to the nanoscale to produce a novel nanoparticle characterization technique called Tunable Resistive Pulse Sensing, or TRPS.
Having properly sized particles allow aggregate companies to create long- lasting roads and other products.

15. References Principle of mineral dressing by A.M Gaudin
Mineral processing technology by Barry .A.Wills

16. Thank you