Powder Characterization

Particle Science and Technology Laboratory

POWDER CHARACTERIZATION

Prof. B. PitchumaniParticle Science and Technology Laboratory

Department of Chemical Engineering

Indian Institute of Technology, Delhi, INDIA


Bio-Data

Subject Institute Year

Fine grinding in Jet Mill

Ph.D. IIT Madras 1974

Cyclone Separator Institut fur Mechanische Verfahren Technik, Karlsruhe

1980

Size and shape analysis of powder

Particle Analysis Center,West Virginia University

May-July1983 &

June 1985

Flowabilty of powdersAnd high temperature

cyclone

Chemical Engineering Department

Technical University, DelftThe Netherlands

1990

Development of filter Chemical Engg Dept.Technical University Erlangen, Nurenberg

Germany

2000


INTERACTIONSGermanyUniversity of KarlsruheBerlin UniversityUniversity of StuttgartUniversity of KonstanzUniversity of AachenUniversity of ErlangenUniversity of BraunsweigUnited KingdomUniversity of Kent, CanterburyUniversity of SwanseaUniversity of LoughboroughThames PolytechnicUnited States of AmericaWest Virginia University, Morgentown University of Illinois, Chicago University of Pittsburgh, University of Utah .University of Iowa, Iowa city University of Florida, Gainesville, University of HoustonSwitzerland ETH, ZurichThe Netherlands Technical University, Delft Technical University , EindovenJapan Univ. of Tokyo, Doshisa Univ,. Nagoya university Hakoida university


PARTICLE

Solid – Powder, granules, pellets

Liquid – Droplet, Suspension

Gas-Bubble, Foam, Emulsion


Powder Characterization Size, Size distribution

Shape (Morphology)

Surface area

Bulk density

Flowability

Zeta potential


DEFINITION OF PARTICLE SIZEDiameter Definition

Feret's diameter dH The mean value of the distance between pairs of parallel tangents ;to the projected outline of the particle.

Martin's diameter dM The mean chord length of the projected outline of the particle.

Projected area diameter, dpr

Diameter of a circle having the same area as the projected area of the particle (1) resting in a stable position (2) in random orientation.

Sieve diameter, dSie The width of the minimum square aperture through which the particle will pass.

Stokes diameter, dstk

The falling diameter of a particle in the laminar flow region.

Surface diameter, dS

Diameter of a sphere having same surface as the surface of particle.

Volume diameter, dV Diameter of a sphere having the same volume as the particle.

Aerodynamic diameter, dae

Diameter of an unit density sphere with the same settling velocity as the particle in question.


Significance of Size Distribution

0

20

40

60

80

100

120

0 5 10 15 20 25 30 35

Particle Size [microns]

Cu

mu

lati

ve U

nd

ersi

ze [

wt

%]

Sample-1

Sample-2

Sample-3


Sample Bulk Density Dustiness Dispersion

1 Lowest maximum lowest

2 Moderate tolerable Fair

3 Highest Minimum Very good

0

20

40

60

80

100

120

0 5 10 15 20 25 30 35

Particle Size [microns]

Cu

mu

lati

ve U

nd

ers

ize [

wt

%]

Sample-1

Sample-2

Sample-3

Significance of Size Distribution


DISTRIBUTION EQUATIONS

The distribution function can be represented either as a probability density function, qr(x) or as a cumulative distribution function Qr(x), both of which are the functions of the particle size `x'.


RELATIONSHIP IN DISTRIBUTION EQUATIONS

q (x) = dQ (x)

dxrr



TABLE : Definition of ‘r’

S.No.

Experimental method

Type of measurement

r

1 Microscopy counting 0

2 Photo-sedimentation

area 2

3 Sieving and sedimentation

weight 3


Normal distribution

2

250

0 2

x-x-exp

2

1 = (x)q


Log-Normal distribution

Q (x) =

1

2 exp

ln

lnrg

xx

g

2

50

( x50, is the median particle size corresponding to

Q(x) = 50%.

g84

50 = x

x


n

dX

XXQ

exp3

Rosin Rammler Equation


Gaudin - Schumann Equation

m

X

XxQ

max3

Nikiyama- Tanasawa Equation

32

210 exp KXKXKxq


Different type of Size Distribution

0

20

40

60

80

100

0 20 40 60 80 100 120 140 160Particle Size, [µm]

Cum

ulat

ive

unde

rsiz

e, Q

3(x)

, [%

]

Volume Distribution

Number Distribution

Length Distribution

Area Distribution


Different type of Size Distribution


To calculate distribution qt (x) from given distribution qu(x).

q (x) = x q (x)

x q (x) dxt

t - uu

t - uu

x

x

min

max

INTER CONVERSION OF DISTRIBUTION


Shape characterization

Feret Diameter

Sieve Cascadograph

Fractals


INSTRUMENTS FOR

•SIZE AND SIZE DISTRIBUTION

•SHAPE ANALYSIS

•ANGLE OF REPOSE

•BULK AND TRUE DENSTY

•FLOWABILITY

•AIR PERMEALITY

•ZETA POTNTIOAL

•DUSTINESS


SURFACE AREA METER


SURFACEAREA METER


EQUATION

S = k 1

1 -

t

Lv22

2

32 2

2

12

where k is a constant given by

k = S 1 - L

tv1 1 11

1

12

32


Company Name: Aurobindo pharmaceutical Lit. 19.12.2005Sample Name : Aurobino

PCI,Q3(x), [%]01 2 2 42 3 5 93 5 10 204 7 15 325 9 30 566 11 52 717 13 91 828 15 138 889 16 240 96

10 18 363 10015 2720 3525 4230 4835 5440 5945 6463 7775 8390 89106 93125 95150 98212 100250 100

Particle size, µmQ3(x), [%]

Malvern

New Sample 1


Geldart Classification of powders


TO IMPROVE THE FLOWABILITY Larger number of fines cause increased adhesive-cohesive forces in the powder leading to cohesive flow behavior


UNIT OPERATIONS

Crystallization (size and shape control)

Liquid solid separation (filtration/ centrifuging)

Drying (batch or continuous)

Pulverizing (shape and size distribution control)

Coating (nano particle coating)


•There is variation in size distribution

•Potency is high but purity is less

•Morphology of particles produced during crystallization is changed after

final product is produced

•Filtration time is much higher than theoretical time

•Powder when transported for longer time becomes cake and volume of

packed material is reduced

•Drying time is much higher than theoretical time

OBSERVATIONS


The life of filter cloth in centrifuge got reduced The material has to be reground for desired sizeRetrofitting of storage silo to prevent chokingReduce the pressure drop in cyclones and bag houseEstimation of hammer size and shapeInterpretation of size distribution for energy savingSimple method to estimate size distribution in subsieve size rangeSelection of fabric for bag houseFugitive dust control with pipe cyclone

CASE STUDIES


Crystallization i) various types of agitators/agitation

speeds/profiles for obtaining specific particle size distribution (PSD)

ii) characteristic cooling profiles for generating particle size requirements

iii) Impact of heat dissipation on PSD

iv) Use of ultrasonic waves for obtaining uniform PSD

EARLITER DISCUSSIONS


Control of PSD

addition of antisolvent on PSD spraying high velocity jet on PSD. Usage of high frequency dryers to obtain

uniform PSD. Usage of alphine air jet milling to

optimise/control PSD.



Chargeability/Zeta potential

Effect of charge on PSD, dispersion Charge dissipation techniques, especially

usage of photo-deioniser for charge dissipation for powdered products.

formation of agglomeration due to chargeability

accumulation of charge during storage and transportation



a) Containment of micronized /fine milled Powders i) in powder processing areas ii) during storage

b) Effect of repeating milling/size reduction on profile of particle size distribution. Illustrate with Comminution functions such as selection and breakage function.

c) Control of Particle shape during unit operations and particle shape measuring technologies.



Particle Manufacture

By Breakdown

GRINDING (Solids)

SPRAYING (Liquids)


Particle Design

By Growth

PRECIPITATIONCRYSTALLISATION

POYMERISATION

CHEMICAL VAPOURDECOMPOSITION

FromLIQUID

FromGAS

GRANULATIONSINTERING

FromSOLIDS

Powder Characterization

Documents

technical

technology

shape analysis

particle science

projected

cumulative

university

particle