freeze granulation of nanomaterials from powderpro sweden
DESCRIPTION
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.TRANSCRIPT
NanoMaterials 2010 www.powderpro.se
Freeze Granulation for
Processing of Nano Materials
Kent Rundgren, President of PowderPro AB
Sweden
NanoMaterials 2010 www.powderpro.se
Freeze Granulation Process
Spray freezing Freeze drying
Air Suspension Vacuum
Sublimation
- 30oC Ice
Frozen
granules
Atomisation
Liquid nitrogen (- 196oC)
Condensation
Instant
freezing
NanoMaterials 2010 www.powderpro.se
Suspension
droplet
Freeze granulation
No shrinkage: density and
homogeneity retained
Sublimation
Shrinkage during drying
increases granule density
Void formation
Spray drying
Migration of binder
and small particles
to surface
Formation of
dried shell
Liquid transport
Freeze Granulation vs Spray Drying
NanoMaterials 2010 www.powderpro.se
Freeze Granulation A variety of applications
Nanopowders
Ceramics
Diamond tools
Explosives Biomaterials
Metal powders
Pharmaceuticals
Grinding wheels
Chemicals
Composites
Nanomaterials
Catalysts
Homogenous
granules
Freeze Granulation – The Way to Optimised Powder Processing!
Bioceramics
LED-Lighting materials
Chemical Looping Combustion
Material synthesis
Instant
freezing Spherical
Free flowing ©Swerea IVF AB
©Swerea IVF AB
www.powderpro.se
Atomisation
NanoMaterials 2010 www.powderpro.se
Freeze Granulation of nanopowders
No
agglomer
ation
Nanopowder
Granulated nanopowder
Dried to powder
Re-dispersed to nanopowder
Unique process to retain nanomaterial particle size
Nano-particles keep separated
Re-dispersible end-result
NanoMaterials 2010 www.powderpro.se
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
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
Freeze Granulator
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
Models: LS-2
and LS-6
NanoMaterials 2010 www.powderpro.se
Capacity to dry ca 2 litre of
granules that is achieved from ca 1
litre powder suspension
Heated trays for quick drying
Driers with much higher capacity
exist on the market
Freeze drier GT-2
NanoMaterials 2010 www.powderpro.se
• 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
Aspects in processing of small units of matter
NanoMaterials 2010 www.powderpro.se
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
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
0.01
0.1
1
1 10 100 1000
Shear rate (s-1
)
Vis
cosity
(Pa s
)
Planetary milled (pH=9.8)
Impeller stirred (pH=9.2)
Freeze granulated/freeze-dried powders can be re-dispersed with impeller
stirring to the same de-agglomerated state as with planetary ball milling
Re-dispersibility of submicron powders - 1
NanoMaterials 2010 www.powderpro.se
0.01
0.1
1
10
100
1 10 100 1000
Shear rate (s-1
)
Appare
nt vi
scosity
(Pa s
) 44 vol% As-received
44 vol% Pre-treated
48.4 vol% Pre-treated
Si3N4 (UBE E10) water
suspensions at pH 10
Powders, difficult to deagglomerate, can be dispersed at low concentrations,
freeze granulated/freeze-dried and re-dispersed at higher concentrations
Re-dispersibility of submicron powders - 2
NanoMaterials 2010 www.powderpro.se
Granules of ”nano”powders
Granule based on 10-30 nm
particles at low concentration
Granule based on 500 nm particles
at high concentration
NanoMaterials 2010 www.powderpro.se
Freeze Granulation of nanopowders
No
agglomer
ation
Nanopowder
Granulated nanopowder
Dried to powder
Re-dispersed to nanopowder
Unique process to retain nanomaterial particle size
Nano-particles keep separated
Re-dispersible end-result
NanoMaterials 2010 www.powderpro.se
• 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
Various aspects and uses
NanoMaterials 2010 www.powderpro.se
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
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
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