1. Particle Agglomeration
Objectives
To understand the mechanism of agglomeration
To study key rate processes of agglomeration
To illustrate the different types of agglomeration equipments

2. What is Agglomeration?

3. Agglomeration
Agglomeration happens when small particles stick together, forming aggregates which are of larger sizes.

4. Scaled up agglomerates (Source: NIZO food research)

5. What are the Objectives of Agglomeration?

6. 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
A briquette (or briquet) is a block of flammable matter used as fuel to start and maintain a fire.

7. Objectives of Agglomeration
Improved flow properties  Pharmaceutics, ceramics
Increased bulk density for storage  Detergents
Control of solubility
Control of porosity and surface-to-volume ratio
Improvement of heat transfer
Removal of particles from liquid

8. 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

9. 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

10. 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.

11. 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

12. 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

13. 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