1 Engineering in Chemical and Pharmaceutical Processes Particle sizing, Compaction, Extrusion Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization Compaction „Dry-granulation“ Principle Compressing the powder between two surfaces Cohesive forces van der Waals mechanical interlocking solid bridges (instantneous melting of the particles’ surfaces)
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Engineering in Chemical and Pharmaceutical Processes
Particle sizing, Compaction, Extrusion
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Compaction
„Dry-granulation“
Principle
Compressing the powder between two surfaces
Cohesive forces
van der Waals
mechanical interlocking
solid bridges (instantneous melting of the particles’ surfaces)
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Compaction
Categories of materials
compactable
compactable with fragmentation
non-formable (glass, sand)
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Materials compactability
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Mechanism of compaction
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Energy analysis of compaction
Analysis of force required per displacement during compression and decompression
Energy = force * length
Energy = area under curve
EP = plastic deformation
EE = elastic deformation
EF = rearangement /friction
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Mathematical model of compation
Heckel equation one of many equations
assumes the compaction takes place by reducing porosity as the first order process
rel
solid
B
k
p
rel d
drel
B
solid
B
solidB
V
V
V
VV
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relrel kP
1d
d
Akprel
1
1ln
A
01
1ln
ρ0 = rel. density at low pressure
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Types of compaction behavior
Compacting different size fractions of the same material
rel1
1ln
P
rel1
1ln
P
mostly plastic fragmentation
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Compaction equipment
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Roller compaction
Compacting powder between rollers
Powder is fed by gravitation or using screw conveyor
Powder is pulled into the gap by action of friction force between the roller surface and the powder
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Critical parameters of roller compaction
ω … angular speed
α … nip angle
γ … angle of max pressure pmax
δ … elastic expansion angle
e … gap size
e1 … size of product ribbon
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Zones between the rollers
Entry zone
powder is not entrained by the rollers
Slip zone
powder is pulled into the gap, but moving more slowly than roller surface
Nip zone
powder is pulled into the gap at the roller surface velocity
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Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization
Regions of different material motion
α given by pressure,
layer height and
material properties
Engineering in Chemical and Pharmaceutical Processes Compaction, Extrusion, Spheronization