AGGLOMERATION
Combining the resources of
K-G
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RIETZ
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SCHUGI
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STRONG-SCOTT
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Outline
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Introduction
Binder Overview
Pressure Agglomeration / Compaction
Wet Agglomeration Overview
Tumbling Agglomeration / Instant Mixing
Extrusion Agglomeration
Thermal Agglomeration
Batch vs Continuous Processing
Selection of an Agglomeration System
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Defining Agglomeration
The process of transforming
finely divided particles
into particles of a larger size
by the introduction of outside forces.
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Reasons For Agglomeration
• Minimize or eliminate dust
• Improve flowability
• Improve storage and handling characteristics
• Improve metering and dosing characteristics
• Formulation stability, prevent segregation
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Reasons For Agglomeration
• Increase or control bulk density
• Defined shape, size, or weight
• Solubility control, dispersability
• Improved appearance
• Increased product value
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Industrial / Consumer Applications
•Salt Pellets, Charcoal Briquettes
•Laundry / Dishwasher Detergents
•Agricultural Chemicals
•Feed Supplements
•Instant Drink Mixes
•Nutraceuticals / Functional Foods
•Many others
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Binding Mechanisms
(According To Pietsch)
- Solid Bridges
- Chemical Reactions
- Sintering
- Adhesion Forces
-Crystallization of Soluble - Highly Viscous Binders
Substances
- Adsorption Layers
-Hardening of melted subs.
-Cohesion Forces
- Matrix Binder
- Capillary Forces
(conglomerates saturated
with liquid)
- Interlocking
-Form Closed Bonds
- Liquid Bridges
-Capillary Pressure
- Interfacial Forces
- Molecular Forces
- Electrical Forces
- Magnetic Forces
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Agglomeration Methods
Pressure Agglomeration
- Briquetting
- Compacting
- Tableting
- Piston Press
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Agglomeration Methods
Tumbling Agglomeration
- Mechanical
- Tumbling
High/Low Speed
- Pneumatic
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Agglomeration Methods
Extrusion Agglomeration
- Low Pressure Extruder
- Gear Pelletizing
- Pellet Mill
- High Pressure Extruder
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Agglomeration Methods
Thermal Agglomeration
Hot Melting/Forming
- Flakes/Pastilles
- Prilling
Sintering
- Rotary Kiln
- Traveling Grate
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Pressure Agglomeration
Application of High Pressure to:
• Densify powder feed material
• Partially crush incoming particles
• Force particles into close proximity
• Rely on interparticular forces
• Rely on particle molding
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Advantages of
Pressure Agglomeration
• Little or no binders required
• Drying or curing post treatment not required
• High capacity with low energy input
• Wide range of feed sizes acceptable
• High product density achieved
• Robust design promotes extended equipment
life
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Pressure Agglomeration
Product Characteristics
•Densify powder feed material
•High density products
•High strength
•Uniform shape and size
•Large product size possible
•Possibility for no binder addition
•Limited dispersability
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Double Roll Compaction
•Material drawn between counter rotating rolls
•Force feeders usually used
•High pressure applied in the nip
•Roll surface dictates product shape
•End product: Briquettes, or sheets for
granulation
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Feed Limitations for
Double Roll Compaction
•Aerated feed materials require special features
to deaerate or minimize vibration
•Only “dry” feed acceptable
•Abrasiveness, elasticity, plasticity, and
brittleness need to be considered
•Heat and pressure sensitive materials not
compatible
•Toxic materials are difficult to contain
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Double Roll Compactors
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Products Produced In Roll Compactors
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Wet Agglomeration Process
Dry Particles
Wet Particles
Effective Collision
Forming of Liquid Bridge
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Wet Agglomeration Model
Less liquid
Small agglomerates
More liquid
Larger agglomerates
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Particle Size
Influence of Moisture on Particle Size
Mixing
Agglomeration
% Liquid
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Increasing Solid:Liquid Ratio
• Very little liquid 
powder
coating
• More liquid
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agglomerates
• A lot of liquid
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paste
• Mainly liquid
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slurry
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Wet Agglomeration
General Flow Sheet
Liquid Feed
Solids Feed
PreMix
Agglomeration
Conditioning
Size
Reduction
Oversize
Sizing
Final
Product
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Tumbling Agglomeration
•Feedstock must be a fine powder
•Binder or moisture must be added
•Typical for capacity to be high
•Good alternative for dedusting / disposal
•Capital and operating costs are low
(without post-drying)
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Tumbling Agglomeration
Product Characteristics
•Good dispersability
•Medium to low density and strength
•Rounded shape
•Small, uniform size
•Binder required
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Tumbling Agglomeration Mixers
Rotary Type Mixers
Low Energy
DRUM
CONE
DEEP DISH
STEPPED PAN
Agitator Type Mixer
Medium Energy
PAN or DISC
PIN MIXER
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Turbulizer® Mixer / Agglomerator
Solids
Inlet
Liquid Injection Points
Adjustable
Paddles
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Tumbling Agglomeration for
Instant Mixing
• Combine powder and liquid streams with high
shear
• High level mixing quality required
• High production capacity
• Value added products
• Agglomerate Qualities:
– Relatively porous
– Particle size range 0.1 to 1.5 mm
– Easily dispersed, compressed, dissolved
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Advantages of Instant Mixing
• High capacity, short residence time
• High speed contact yields smaller, more
uniform particles
• Capacity to handle sticky products
• Atomized liquid injection system
• Liquid/steam addition in series
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Instant Mixing Agglomerator
Instant mixing
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Water Dispersible Granule Plant
Flow Diagram
Extrusion Agglomeration
•Feedstock as fine powder, wet cake, or paste
•Moisture or binder may be added
•Curing or post drying may be required
•Improve the drying efficiency of wet cakes
•Capacity to handle sticky and high viscosity
products
•Optional temperature control for high fat or
waxy products
•Further processing possible (spheres)
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Extrusion Agglomeration
Product Characteristics
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Medium density product
Medium dispersability
Good for time release dispersion
Product is cylindrical, with constant cross
section
Typical diameter 1 to 10 mm
Uniform particle size and shape
Product very resistant to breakdown
Binder may need to be added
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Extrusion Process
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Extrusion Agglomeration Product
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Extrusion
Process
1. Powder Weigh Feeder
2. Premixer
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2
3
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3. Liquid Metering
System
4. Extruder
5
5. Continuous Fluid Bed
Dryer
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Extrusion Agglomeration
Further Processing by Spheronization
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Thermal Agglomeration
•Uses heat transfer processes
•Difficult to generalize product properties
•Examples include:
–Prilling
–Drum Flaker
–Sintering
–Rotary Kiln Nodulizing
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Prilling
•Can produce particles up to 1,500 um
diameter, 300 um diameter is more common
•Product is spherical, not ideal sphere
•Hollow sphere in turbulent mixing, indented
sphere in laminar mixing
•Usually followed by Vibratory Fluid Bed to
cool product
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Drum Flaker
•Rotating Drum chills product
•Product hardens on surface
•Product is scraped off to form flakes
•Feed material must be in liquid form
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Batch vs Continuous Processing
•BATCH
•Bad lots easily identified
•More labor with switching
batches
•Low production rates
•Intermittent production
•Frequent product
changeover
•Frequent system clean out
•CONTINUOUS
•More uniform product
•Less labor required
•High production rates
•Few shutdowns
•Few different product
specifications
•Seldom need to stop and
clean out
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Selection of an
Agglomeration System
• Any agglomeration method can be
applied to most materials
–May need to modify feed materials first
• End product functionality
requirements dictate method
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Selection of an Agglomeration System
End Product Characteristics
•Dispersability
•Dissolution rate
•Flowability
•Compressibility
•Density
•Strength
•Shape
•Size
•Size Distribution
•Formulation
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End Product Types
• Multi stage spray drying
• Disc granulation
• Powder clustering by instant mixing
• Form granulation by mechanical force
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Product Comparison
Product Form /
Product Properties
Onion
Skin
Clusters
Extrudate
Hollow
Sphere
Compacted
Granule
Briquette
Flowing Properties
4
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3
2-3
4
2
Bulk Density
3-4
2-3
3
1
4
3
Dispersability
1
4
2-3
3
2
1
Instant
Characteristics
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1-2
1-2
1
1
1-5 mm
0.2-1.2 mm
0.3-5 mm
< 200m
0.1-5 mm
5 mm+
Particle Size
4 – Very good / excellent
3 – good
2 – moderate
1 - poor
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Selection of an Agglomeration System
•Raw material limitations
•Upstream process
•Downstream process
•Formulation flexibility
•Product changeover
•Equipment maintenance
•Capital vs Operating costs
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Examples of Machine Selection
•Charcoal – Briquetting on Double Roll
Compactor
•Instant Drink Mix – Turbulizer and Fluid Bed
•Stearic Acid – Prilling Tower
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Conclusions
•Agglomeration equipment is the key part of
a total agglomeration system
•Various options exist for most feed
materials
•Desired product characteristics will dictate
the method to use
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