Episode 36 : What is Powder Technology? All the technology which concerns itself with the handling or processing of powders, or materials in particulate form - production, storage, transportation, mixing, dusting, characterization, packing, crushing and milling Important role for medicines, food stuffs, plastics, metals, fertilizer, cement and etc. A prominent academic discipline The roots of powder technology - in the areas of material handling and processing. SAJJAD KHUDHUR ABBAS Ceo , Founder & Head of SHacademy Chemical Engineering , Al-Muthanna University, Iraq Oil & Gas Safety and Health Professional – OSHACADEMY Trainer of Trainers (TOT) - Canadian Center of Human Development

1. SAJJAD KHUDHUR ABBAS
Ceo , Founder & Head of SHacademy
Chemical Engineering , Al-Muthanna University, Iraq
Oil & Gas Safety and Health Professional – OSHACADEMY
Trainer of Trainers (TOT) - Canadian Center of Human
Development
Episode 36 : What is Powder
Technology?

2. What is Powder Technology?
♦All the technology which concerns itself
with the handling or processing of powders, or
materials in particulate form
- production, storage, transportation,
mixing, dusting, characterization,
packing, crushing and milling
♦Important role for medicines, food stuffs,
plastics, metals, fertilizer, cement and etc.
♦A prominent academic discipline
♦The roots of powder technology
- in the areas of material handling and
processing.

3. What is Powder?What is Powder?
♦ We define powders as materials consisting of particles in the size
range 0-10 mm.
♦ Like fluids and gas, powders can exhibit many complex physical and
chemical characteristics, which play an important role in the
selection of powder processing technologies.
grain
detergent

4. TABLE 1: The important powder characteristics required for the selection orTABLE 1: The important powder characteristics required for the selection or
dimensioning of equipments (CEMA, 1971)dimensioning of equipments (CEMA, 1971)
Density/Bulk density Attritability
Dustiness Electrical properties
Size distribution Corrosivity
Plasticity Stability/Reactivity
Shape Hygroscopicity
Aeratability Moisture content
Flow properties Hardness
Explosivity Compressibility
Erisivity Combustibility
Stickiness Frictional properties
Coating tendency Cohesiveness

5. Why is Powder TechnologyWhy is Powder Technology
important?important?
♦ Proper design and handling of these fine particles often makes the
difference between success and failure.
♦ Failure to consider the particle science involved in a process can
result in very expensive or unpleasant consequences.
♦ Some 75% of chemical manufacturing processes involve small solid
particles (fine particles) at some point.

6. Chapter 1: Particle Size
Distribution
3.1: Selecting a Method and
Sampling
♦Regular shaped particles can be accurately
described by giving the shape and a number of
dimrnsions: e.g. Sphere-radius, Cube-side
length etc.
♦However, no single physical dimension can
adequately describe the size of an irregularly
shaped particle. Thus we need to make a
selection.

7. a) Tepung pulut b) Tepung ubi c) Tepung beras
Rajah 1: Gambar daripada analisis imbasan
mikroskop elekrtron bagi zarahan tepung.

8. Selecting the method for determining particle size
(or size distribution)
i) Select a definition of particle size that is
appropriate for the application.
E.g. for pneumatic conveying -- where the
appropriate definition is the diameter of a sphere
with the same settling velocity -- use a
sedimentation method (Stoke’s diameter)
* For flow though packed or fluidised beds --
where the appropriate definition is the diameter of
a sphere having the same surface to volume ratio
as the particle -- measure the specific surface area.

9. ii) Select a method of measurement that is
appropriate to the definition;
Some alternative definitions of particle size are:
Diameter of a sphere which has the same property as
the particle itself -- that is, the same volume, same
settling velocity, etc.
Diameter of a circle which has the same property as
the projected outline of the particle -- that is, the
same projected area or same perimeter
Linear dimension measured parallel to a particular
direction

10. Equivalent circle
diameter
Cirle with area
equaled to
projected area
of particle.
Martin’s
diameter
Line bisecting
projected area
Feret’s diameter
Parallel
tangents
Figure 3.1: Some diameters used in microscopy

11. Volume
diameter, dv
Actual particle
Surface diameter,
ds
Surface –volume diameter,
dsv
Fig. 3.2: Comparison of equivalent sphere
diameters.

12. Table 3.1: Comparison of equivalent sphere diameters
Shape Sphere passing
the same sieve
aperature, dA
Cuboid
Cylinder
3
3
Sphere having the
same volume, dv
Sphere having the
same surface to
volume ratio, dsv
3.06
2.38
1.95
1.80
Shape
Cuboid
Cylinder
Sphere having the
same surface
area, ds
3.83
2.74
Thus, in practice it is important to use the method of size
measurement which is directly gives the particle size
which is relevant to the situation or process of interest.

13. Some definations and approximations.
3/1
v
V6
d 





=
π
As
= (πdv
2
)/4 η=





sA
A
2/1
s
A
d 





=
η
da
= 1.40 dA
dst
= 0.94 dA
dv
≈ 1.13dA
dsv
≈ 0.87dA
dv
≈ dsv
≈ dA Bagi zarah berbentuk sfera atau hampir
sfera
For particles with, ψ ≈ 0.8, where
(1/η= ψ)

14. ♦A population of particles is described by a particle size distribution (PSD).
♦PSD is often presented as a graph of the logarithm of the total number of particles smaller than
particle diameter d against the diameter itself, d (cumulative curves) or as frequency distribution curves.
♦This plot is based on counting particles in a series of adjacent size ranges often called channels.
♦The distributions can be by number, surface, mass or volume (where particle density does not vary
with size the mass distr. = volume distr.)
Description of populations of particles

15. 0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0 20 40 60 80 100
Particle size, d (µm)dF/ddorf(d)(µm-1)
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100
Particle size, d (µm)
F
Fig. 3.3
Differential
frequency
distribution
(dF/dd) or f(d)
Fig. 3.4
Cumulative
frequency
distribution, F

16. 0
0.1
0.2
0.3
0.4
0.5
0 5 10 15 20
Particle size d, µm
fv(d) (by volume)
fs(d) (by surface)
fN(d) (by number)
f(d)
(µm-1
)
Fig. 3.5: Comparison between distributions
Common methods of displaying size distribution:
1. Arithmetic-normal distribution
2. Log-normal Distribution

17. Describing the population by a single number
•In practice, we require to describe the particle size
of a population of particles (millions of them) by a
single number.
•The options available: the mode, the median and
means.
00
0.2
0.4
0.6
0.8
1
0 20 40 60 80 100
g(d)
F
Area = g(d)
Definations of means
g(d) Means/notations
(d) Arithmetic, da
(d^2) Quadratic, dq
(d^3) Cubic, dc
(log d) Geometric, dg
1/d Harmonic, dh

18. ∑
=
Ai
i
A
d
x
1
d
∑
=
svi
i
SV
d
x
1
d
From differential frequency distributions, the means
can be calculated as:
∑ 





=
T
ii
ln
N
dN
d
∑ 





=
T
ii
lm
M
dM
d
∑ 







=
2/1
T
2
i
sn
N
dN
d
i
∑ 







=
3/1
T
3
i
vn
N
dN
d
i








=
∑
∑
3
ii
4
i
wn
dN
dN
d
i

19. Methods of particle size distribution:Laboratory
sieving
•Commonly used for size analysis, using sieves up to 16
mm aperture, though usually in the range of 50 m to 3 mm.
The size of coarser particles is determined by direct
measurement.
•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.
•Mean particle diameter of a sample is the sum of the mass
fractions retained on each screen multiplied by the mean
diameter of particles retained by that screen.

20. Fig. 3.6: Sieves BS 1377, 1975

21. 3: Particle Size Distribution from sieving analysis --
The results of a sieve analysis (using the example below) may be
presented as a plot of:
•cumulative percent undersize (falling through) vs aperture size
•cumulative percent oversize (retained on screen) vs aperture size

22. •weight or percent retained on each screen used in sequence
versus aperture size (or average diameter)
The horizontal axes (aperture size or average diameter) may be on
an arithmetic or on a logarithmic scale.

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