PowderPro AB develops, manufactures, markets and sells equipment for Freeze Granulation, i.e. spray freezing and subsequent freeze drying – Spray Freeze Drying. Freeze Granulation was developed in late 1980s at Swedish Ceramic Institute and it is also a development of Spray Freeze Drying (SFD) and Spray Freezing into Liquid (SFL). In mid 70th W.W. Rhodes and S. Prochazka (1975) provided the first publications about Freeze Granulation of ceramic powders without defining the advantage or explaining the positive results. Freeze granulation, spray freezing and subsequent freeze drying (lyophilization or cryodesiccation), a development of Spray Freeze Drying (SFD) and Spray Freezing into Liquid (SFL), was first developed for granulation of ceramic powders at Swedish Ceramic Institute (SCI) in Göteborg in the late 1980′s. It was early shown to be the most suitable method to provide optimal granule properties for lab and research purposes and, later on, also for pilot and production scale processing of ceramics and other powder-based materials. During the 1990′s, Freeze Granulation was successfully applied in material and processing developments within many research projects and commercial contract work. Specific powder systems from various companies were tested with very good results, demonstrated by homogeneous granulates and improved final component/material properties. However, no commercial equipment was available and therefore PowderPro AB was founded in January 2000 with the objective to provide equipment for the process. PowderPro AB develops, manufacture, market and sell granulation equipment and carries out test granulations (standard concept), whereas Swerea IVF conducts developments regarding suspension concepts and granulation methodology. Several companies and research labs around the world have applied the Freeze Granulation process with the support of PowderPro AB. Typical applications for freeze granulation are homogeneous granulation and drying of ceramic powders; oxides (Al2O3, ZrO2, SiO2), nitrides (Si3N4) and carbides (SiC) and also metal oxides, nanomaterials (nanopowders), diamonds, LED Lighting, explosives (igniters, delay elements) and pharmaceuticals like proteins, enzymes and chemicals.

1. Freeze Granulation for
Processing of Nano Materials
Kent Rundgren, President of PowderPro AB
Sweden
NanoMaterials 2010 www.powderpro.se

2. Freeze Granulation Process
Spray freezing Freeze drying
Suspension Air Vacuum
Atomisation Sublimation
Frozen
Instant granules
freezing
Ice Condensation
- 30oC
Liquid nitrogen (- 196oC)
NanoMaterials 2010 www.powderpro.se

3. Freeze Granulation vs Spray Drying
Freeze granulation Spray drying
No shrinkage: density and Suspension Shrinkage during drying
homogeneity retained droplet increases granule density
Void formation
Migration of binder
and small particles
to surface
Formation of
dried shell
Sublimation Liquid transport
NanoMaterials 2010 www.powderpro.se

4. Freeze Granulation
A variety of applications
Atomisation Instant
freezing
Spherical
Homogenous
granules
©Swerea IVF AB
Free flowing
©Swerea IVF AB
Metal powders Bioceramics Ceramics
Explosives Biomaterials
Diamond tools LED-Lighting materials
Grinding wheels
Nanopowders
Composites Catalysts
Chemical Looping Nanomaterials
Combustion
Pharmaceuticals
Material synthesis
Chemicals
Freeze Granulation – NanoMaterialsOptimised Powder Processing!
The Way to 2010 www.powderpro.se
www.powderpro.se

5. Freeze Granulation of nanopowders
Nanopowder
Re-dispersed No Granulated
to nanopowder agglomer nanopowder
ation
Dried to powder
 Unique process to retain nanomaterial particle size
 Nano-particles keep separated
 Re-dispersible end-result
NanoMaterials 2010 www.powderpro.se

6. Freeze Granulation
• Method to preserve nano properties
• Method to produce homogeneous granules and preserve
material homogeneity
• Method to avoid strong bonding and oxidation
• Method to produce granules of nano materials that can be
handled and processed in dry state
• Method to produce granules, easy to re-disperse to
original particle size distribution
NanoMaterials 2010 www.powderpro.se

7. PowderPro AB
Founded in 2000, as a spin-off company from the Swedish
Ceramic Institute, to provide equipment for freeze granulation
- a privately owned, expanding company
- science-based
- affiliated to Swerea IVF AB and Chalmers Industriteknik
- especially experienced in the ceramic and powder metallic fields
- looking to expand into fields where high-quality freeze
granulation can improve processes and output quality
NanoMaterials 2010 www.powderpro.se

8. Freeze Granulator
Models: LS-2
and LS-6
Small scale with capacity to process up to 6 litre suspension per hour
Medium scale with capacity of processing 25 litre per hour is under
development
NanoMaterials 2010 www.powderpro.se

9. Freeze drier GT-2
Heated trays for quick drying
Capacity to dry ca 2 litre of
granules that is achieved from ca 1
litre powder suspension
Driers with much higher capacity
exist on the market
NanoMaterials 2010 www.powderpro.se

10. Aspects in processing of small units of matter
• Difficulties to retain homogeneity during processing
• Difficulties to keep small units separated
• Drying from suspension causes agglomeration,
segregation and oxidation
• Difficulties to obtain handable/processable nanopowders
in dry state
• Difficulties to re-disperse from dry state
NanoMaterials 2010 www.powderpro.se

11. Freeze Granulation Process Benefits
• Homogeneous granules
- No cavity or void formation
- No migration of any substances or small particles to surface
- No, or limited, shrinkage of granules
- No formation of a dried shell
● Granule density controlled by suspension composition
● Vacuum drying minimizes oxidation
● High yield, low waste of material
● Process allows latex (water insoluble polymers) as binder
● Recycling of solvent possible
NanoMaterials 2010 www.powderpro.se

12. Granule properties
Free-flowing granules with a wide granule size distribution (20–500 μm)
Density depends on solids in suspension
Size depends on suspension viscosity and granulation parameters
NanoMaterials 2010 www.powderpro.se

13. Re-dispersibility of submicron powders - 1
Freeze granulated/freeze-dried powders can be re-dispersed with impeller
stirring to the same de-agglomerated state as with planetary ball milling
1
Viscosity (Pa s)
0.1
Planetary milled (pH=9.8)
Impeller stirred (pH=9.2)
0.01
1 10 100 1000
Shear rate (s-1)
NanoMaterials 2010 www.powderpro.se

14. Re-dispersibility of submicron powders - 2
Powders, difficult to deagglomerate, can be dispersed at low concentrations,
freeze granulated/freeze-dried and re-dispersed at higher concentrations
100
Si3N4 (UBE E10) water
suspensions at pH 10 44 vol% As-received
Apparent viscosity (Pa s)
10
1
48.4 vol% Pre-treated
0.1
44 vol% Pre-treated
0.01
1 10 100 1000
Shear rate (s-1)
NanoMaterials 2010 www.powderpro.se

15. Granules of ”nano”powders
Granule based on 10-30 nm Granule based on 500 nm particles
particles at low concentration at high concentration
NanoMaterials 2010 www.powderpro.se

16. Freeze Granulation of nanopowders
Nanopowder
Re-dispersed No Granulated
to nanopowder agglomer nanopowder
ation
Dried to powder
 Unique process to retain nanomaterial particle size
 Nano-particles keep separated
 Re-dispersible end-result
NanoMaterials 2010 www.powderpro.se

17. Various aspects and uses
• All kinds of material in dispersed form can be granulated
• Ideal for preparation of fine powder mixes with suitable
additives for subsequent processing
• Suspension quality always determines and will reflect the
granule quality in terms of homogeneity
• Favorable preparation step for material synthesis owing
to the homogeneity of the granulated material
• Water as medium is preferred but also organic solvents
with suitable freezing point (-25 to +10°C) can be used
NanoMaterials 2010 www.powderpro.se

18. PowderPro: Offers and Services
– Supplies freeze granulation equipments for Lab,
Pilote-scale and production
– Carry out test granulations of customer-supplied
materials
– Supports process implementation and start-up with
customers
PowderPro has close collaboration with Swerea IVF
AB in research related to freeze granulation in a wide
range of material/applications
NanoMaterials 2010 www.powderpro.se

19. Mission
PowderPro's mission is to provide first-class Freeze
Granulation and drying techniques for processing of
ceramic and metal powders, nanomaterials, diamonds,
proteins, enzymes, fine chemicals and pharmaceuticals.
NanoMaterials 2010 www.powderpro.se

20. Freeze Granulation - Summary
• provides a competitive technique for the manufacture of
granules for various purposes
• preserves the material homogeneity
• enhances subsequent processing performance
• enables equally appropriate process for smaller and
larger quantities with equal results
• enables controlled granule density can be
• provides mild drying with low degree of oxidation
NanoMaterials 2010 www.powderpro.se