1. (Fluid-Particles Systems)
Separation II
(Fluid-Particles Systems)
Course Code: CHPE402
Lecturer: Dr Mustafa Saleh Nasser
Office Number: 5D-44
Dr Mustafa Nasser

2. Course Description

3. Learning Outcome

4. Assessment Methods

5. Assignment format
The student required to submit the hard copy of the assignment. The hard copy should not exceed 10 pages A4 size, including front page, appendices, etc.). The text should be made in 12pt font using Times New Roman style with 1.5 line spacing. Finally, references should be written in standard scientific way (check the literature). 5

6. Reviewing Procedure
A peer review practice will be applied to all presentations. The student should submit their presentation 2 days in advance to the reviewing group. The reviewing group should meet and submit not more than 1 page of comments and recommendations. The student should take action on these comments by revising their presentation based on these comments. 6

7. 1. Particle Size Analysis & Measurements.
Particle Characterization
1. Particle Size Analysis & Measurements.
2. Particle Agglomeration
(Chapter 1)
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8. Goals To be able to define different terminology of particle sizes.
To describe general principles and methods of particle size analysis.
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9. What do you need to consider before you select the method for particle size measurement?
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11. Particulate Solids Properties of particulate solids
Define the physical state of the solid materials
Single particle: Its composition; size and shape
Bulk particle: distribution of particle; mean size
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12. Particulate Solids Properties of particulate solids Composition
Determines properties such as density and conductivity for the uniformed particles (non porous particles)
Size and shape
Important in that this affects properties such as the surface per unit volume and the rate at which a particle will settle in a fluid
Regular shape: spherical or cubic  precise definition
Irregular shape: a piece of broken glass  in terms of some particular characteristics of a regular shaped particle (degree of sphericity)
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13. Selecting a Method and Sampling (1)
Selecting the method for determining particle size (or size distribution)
Select a definition of particle size that is appropriate for the application.
(ii) Select a method of measurement that is appropriate to the definition.
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14. Describing Size of A Single Particle
The size of irregular shape particle can be defined in terms of the size of an equivalent sphere such as:
The sphere of the same volume as the particle (Equivalent Volume Sphere Diameter)
The sphere of the same surface areas per unit volume as the particle
( Surface-Volume/ Equivalent Sphere Diameter).
Circle with area equal to projected area of particle
Equivalent circle diameter
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15. Describing Size of A Single Particle
Feret’s diameter (The mean distance apart of two parallel lines which are tangential to the particle in an arbitrarily fixed direction)
Sphericity, : Measure particle shape
Parallel tangents
Feret’s diameter
Asv: Surface area of sphere of same volume as particle
Ap : Surface area of particle
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16. IS CHEMICAL PROPERTY IMPORTANT?
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17. Methods of Particle Size Measurement
Sieving
Microscopy
Sedimentation
Permeability
Laser Diffraction
Electrozone Sensing – For eg. Coulter Counter
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18. Methods of Particle Size Measurement
1) Sieving (> 45 m)
Can be a nest of sieves, each lower size being smaller aperture size
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19. Ratios of aperture sizes on consecutive sieves: 2, 21/2, 21/4
Mounted on a vibrator or hand shaken
Orientation, not only the size, would affect the passed particles
Standard Sieves sizes
US Tyler
UK British Standard
IMM
US ASTM
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21. …Continued 1) Sieving Commonly used and cheap
Though based on a linear dimension, generally assuming spherical particles
Mean particle diameter retained by a screen is the sum of the aperture of the screen on which the material is retained, plus the aperture of the next largest screen, divided by 2.
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22. …Continued 1) Sieving
The results of a sieve analysis may be presented as a plot of:
cumulative percent undersize (falling through) vs aperture size
cumulative percent oversize (retained on screen) vs aperture size
weight or percent retained on each screen used in sequence versus aperture size (or average diameter)
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23. Efficiency of screening
Efficiency of screening: the ratio of the mass of material which passes the screen to that which is capable of passing
If w is the mass of particles of a particular size on the screen at a time t, then:
where k is a constant for a given size and shape of particle and for a given screen
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24. Methods of Particle Size Measurement
2) Microscopic analysis
( m)
Permits measurement of the projected area of the particle
Enable the assessment to be made of its two-dimensional shape
Automatic scanning uses the electron microscope, where the lower limit of size can be reduced to about m
Coupled with image analysis system, microscope can provide number distributions of size and shape.
Image of ash particles taken using SEM
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25. Scanning Electron Microscopy
An insect coated in gold for viewing with a scanning electron microscope.
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26. Different Types of Electron Microscopy
TEM (Transmission Electron Microscopy)
SEM
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27. Methods of Particle Size Measurement
3) Sedimentation methods (> 1m)
Terminal falling velocity of a particle in a fluid increases with size
Pipette method
Samples are abstracted from the settling suspension at a fixed horizontal level at intervals time
Andreason pipette (2-100 m)
Suspension sampling level
Sampling tube
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28. Methods of Particle Size Measurement3)
Elutriation method is a reverse sedimentation process in which the particles are dispersed in an upward flowing stream of fluid.
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29. Methods of Particle Size Measurement
4) Permeability methods (> 1m)
Depends on the fact that at low flowrates the flow through a packed bed is directly proportional to the pressure difference
The proportional constant being proportional to the square of the specific surface (surface: volume ratio) of the powder
Possible to obtain the diameter of the sphere with the same specific surface as the powder
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30. Methods of Particle Size Measurement
5) Laser Diffraction
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32. Methods of Particle Size Measurement
Laser Diffraction
Laser diffraction is the most widely used technique for particle size analysis.
In laser diffraction, a representative cloud or ensemble of particle passes through a broadened beam of laser light which scatters the incident light onto a Fourier lens.
This lens focuses the scattered light onto detector array and, using an inversion algorithm, a particle size distribution is obtained.
Practical range of size  m
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33. Methods of Particle Size Measurement
6) Coulter Counter (Electrozone Sensing Method)
Advanced method for particle size measurement
A Coulter Counter
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34. Coulter Counter (Electrozone Sensing method)
Particles are held in suspension in a dilute electrolyte which is drawn through the orifice with a voltage applied across it.
Voltage pulse is recorded as particles flow through the orifice.
Amplitude of pulse can be related to volume of particle.
Sketch of a coulter counter found online on the homepages of Pulver Technology Ltd (c). folk.uio.no/anderne/research.html
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35. Methods of Particle Size Measurement
Coulter Counter (Electrozone Sensing method)
Not only measure the particle sizes, but also provide the size distribution of the particles
Particle size distribution:
By number
By length
By surface
By mass (or volume)
Reported as:
Frequency or cumulative distributions?
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36. Frequency or cumulative distributions
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49. R-R Equation reduced to
Modified R-R distribution
This function is often used in mineral processing and accurately
describes the distribution of particles from a size reeducation process
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54. Particle Agglomeration
Objectives
To understand the mechanism of agglomeration
To study key rate processes of agglomeration
To illustrate the different types of agglomeration equipments
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55. What is Agglomeration?
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56. Agglomeration
Agglomeration happens when small particles stick together, forming aggregates which are of larger sizes.
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57. Scaled up agglomerates (Source: NIZO food research)
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58. What are the Objectives of Agglomeration?
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59. Objectives of Agglomeration
Production of useful structural forms  For eg. in pressing of intricate shapes in powder metallurgy
Provision of a defined quantity for dispensing and metering  Agricultural chemical granules or pharmaceuticals tablets
Elimination of dust handling hazards or losses  Briquetting of waste fines
Improved product appearance  Food
Reduced caking and lump formation  Fertilizer
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60. Objectives of Agglomeration
Improved flow properties  Pharmaceutics, ceramics
Increased bulk density for storage  Detergents
Creation of non-segregating blends of powder ingredients
Control of solubility
Control of porosity and surface-to-volume ratio
Improvement of heat transfer
Removal of particles from liquid
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61. 1) Agglomeration by Agitation Methods
Will be referred to as granulation, where a particulate feed is introduced to a process vessel and is agglomerated to form a granulated product
Liquid binder used to form interparticle bonds
Agitation of “wet mass” to promote liquid binder dispersion and granule growth
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62. 1) Agglomeration by Agitation Methods
Feeds: a mixture of solid ingredients (formulation), which includes an active or key ingredient, binders, diluents, flow acids, surfactants, wetting agents, lubricants, fillers or end-use aids (e.g. sintering aids, colors or dyes, taste modifiers)
Induction: solvents addition; heat (lead to controlled sintering)
Include fluid-bed, pan, drum, and mixer granulators
Spray drying is an extreme case with no further, intended agglomeration taking place after granule formation
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63. 2) Agglomeration by Compression Methods
X=(x1, x2,..., xn)
Y=(y1, y2,..., yn)
Compression vessel
Feed
P=(p1, p2,..., pj) % x y
Product
(x or y) = (size, voidage, strength,
surface properties, quality metric)
Where the mixture of particulate matter is fed to a compression device which promotes agglomeration due to pressure.
Usually dry, sometimes liquid as lubricant.
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64. 2) Agglomeration by Compression Methods
Products: briquette or tablet
Induction: heat or cooling; carrier fluids (wet extruded)
Processes:
Continuous: roll presses; briquetting machines; extrusion
Batch: tabletting
Semi-continuous: Ram extrusion
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65. 2) Agglomeration by Compression Methods
This is a forming process controlled by mechanical properties of the feed in relationship to applied stresses and strains
Mechanical processes controlled by microlevel processes such as friction, hardness, size, shape and elastic modulus
Particles deform and break during compaction
Compaction processes give the highest density agglomerates and can operate without liquid binder
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66. Agglomeration Circuit
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67. Size-Enlargement methods and Application (Adapted from Table 20-36 in Perry’s Handbook)
Product Size (mm)
Granule Density
Scale of operation
Typical application
Tumbling granulators
0.5 to 20
Moderate
ton/hr
Fertilizers, iron ore, non-ferrous ore, agricultural chemicals
Mixer granulators
Continuous high shear
Batch high shear
0.1 to 2
Low to high
High
Up to 50 ton/hr
Up to 500 kg batch
Chemicals, detergents, clays, carbon black
Centrifugal granulators
0.3 to 3
Moderate to high
Up to 200 kg batch
Pharmaceuticals, agricultural chemicals
Pressure compaction
Extrusion
Roll press
Tablet press
>0.5
>1 10
High to very high
Up to 5 ton/hr
Up to 1 ton/hr
Pharmaceuticals, catalysts, clays, minerals, ceramics, organic and inorganic chemicals
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