Before Forberg introduced its twin-shaft paddle mixing technology, a coefficient of variation (CV) of 10 was acceptable. Today, a CV of five or less is the standard.

1. Digital Re-print - May | June 2010
Feature title: Horizontal twin-shaft paddle mixers
- The ultimate in mixing technology
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2. Mixing Feature Feature Mixing
Liquids can be product is handled after mixing, so it is
Figure 3 added easily recommended to minimize the distance
to the powder between the mixer and the packaging point
mixture. to avoid segregation.
This is can be The benefits of the mechanical fluidizing
done by means zone are gentle mixing, no segregation and
of quick connec- very short mixing time. This gives savings
tion nozzles (single in terms of minimal wear and tear and low
component flat energy consumption. Maintenance costs are
spray nozzles are also very low. The mixer's low energy con-
most commonly sumption is an important consideration in
used) for adding reducing production costs.
oil, fat, water, fla-
vours, etc. Various mixer designs
Spraying of The twin-shaft paddle batch mixer has
liquids requires been developed over several years.
approximately one Today, continuous twin-shaft paddle mix-
minute ensuring ers are available, notably Forberg's latest
the best possible development, the rotating twin-shaft paddle
distribution of the batch mixer.
liquids in the pow- Continuous twin-shaft paddle mixer -
crushed, worn down or can start forming dered material. In this case, total cycle time, The continuous twin-shaft paddle mixer has
Figure 1
lumps. including spraying of liquids, will be as low as many of the same advantages as the twin-
y
ate in mixing technolog
Because the product is fluidized, the 2.5–3.5 minutes. shaft batch mixer. It is very gentle with the
The ultim
Horizontal twin-shaft paddle mixers
twin-shaft paddle mixer is very gentle with Liquid should be sprayed at a specific products, has low energy consumption, high
the product. Extra force must be added, angle and at a specific distance to obtain capacity, little space requirement and flexible
for example with choppers, in case any the best possible distribution. The particles filling. Throughput is very significant as the
lumps in the mixture must be crushed. rotate around their own axes in the fluidized average retention time is approximately one
High speed rotating knives will create the zone, exposing the total particle surface to minute (see Figure 4).
force needed to crush soft lumps in the the liquid during rotation. The liquid will For obtaining good mixing quality in a
mixture. hit the particles and be distributed in the continuous mixer, an accurate feeding of the
mixture. ingredients is demanded. Continuous mixers
by Kees Rodenburg, Market Support Manager, Forberg International, Norway Features of the twin-shaft paddle High melting point liquids, such as fats, are suitable for mixing a limited number of
mixer can be sprayed in free flowing liquid state components, which have similar properties.
Mixing takes place in a very short time. with special nozzle arrangements. One or two different liquids can be sprayed
An average mixing cycle for dry mixing can Homogeneous mixing is achieved in the onto the product mixtures.
B
efore Forberg introduced its The filling level in the twin-shaft mixer is not type products with all shapes and densities be as follows: filling 20-30 seconds, mixing space of a few seconds thanks to the fluidiz- Rotating twin-shaft paddle mixer - The
twin-shaft paddle mixing technol- more that 40 percent above the shafts. can be mixed in the Forberg® twin-shaft 40-60 seconds and discharging 10-20 sec- ing of the material. All particles can be mixed rotating twin-shaft paddle mixer has com-
ogy, a coefficient of variation Thus, there is surplus space in the mixer paddle mixer. onds. This gives a total cycle time of 1.5–2 (small, large, light, heavy, round, etc.) without bined the mixing technology of the standard
(CV) of 10 was acceptable. Today, a to provide air around the particles so they In some conventional mixers, the trans- minutes. A relatively small twin-shaft paddle segregation, since the forces of mixing are Forberg® batch mixer with a new solution
CV of five or less is the standard. can move freely. The twin-shaft paddles lift port of particles is simplified and unidirec- mixer will provide a large output – thus stronger than the forces of segregation dur- for the filling and discharge (see Figure 5).
the particles up in the middle of the mixer in tional, which results in poor-quality mix and giving savings both in investment costs and ing the mixing action in these mixers. Within seconds, the whole machine is tilted
the fluidized zone, where mixing takes place long mixing time. For some materials this space requirements. Segregation only takes place when the from its filling position to its discharging posi-
What led to this dramatic in a weightless state. can even be negative as the particles can be
improvement in mixing accuracy? In this way,
The answer is that the Forberg horizontal the particles are
Figure 2
twin-shaft paddle mixer brought about a moved back
revolution in mixing.
Imagine a chessboard as the image of a
and forth, up
and down and
• The smartest solution where
perfect mixture. How can practical mixing
results get as close as possible to this ideal?
across in all
directions – this
mixing is essential
In the twin-shaft paddle mixer, the
specific speed of the rotor shafts com-
is the freedom
of movement
• The sanitary design meets all
bined with the specific positioning and
angles of the paddle blades provide
that is essential
if particles are to
your expectations to feed safety www.forberg.no
excellent transport of particles (see be mixed as ran-
Figure 1 and 2). domly as possible
All particles in the mixture need air sur- (see Figure 3). Forberg International AS Hegdalveien 77 NO-3261 Larvik Norway Tel +47 33 13 34 34 Fax +47 3313 34 35 sales@forberg.no
rounding them to be able to move freely. All powder-
20 | may - June 2010 Grain &feed millinG technoloGy Grain&feed millinG technoloGy PREVIOUS PAGE NEXT PAGE may - June 2010 | 21

3. Mixing Feature Feature Mixing
Advantages of the rotating twin-shaft mixer: shaft paddle mixer is a versatile machine, in Figure 8 Figure 9
• Completely closed mixing chamber which many processes beyond mixing can
• Only one valve for charg- be performed. Forberg focuses on further
ing and discharging development of industrial processes, in close
• Reduced cleaning surfaces cooperation with customers and research
with integrated hopper institutions. In the field of poultry feed for
• CIP (cleaning in place) is easy to layers conditioning of mash feed has been a
Figure 4
realise. Washing water can eas- new development.
ily be discharged through the Steam heat treatment of mash feed - For
washing-docking station many reasons, today’s most common poultry
• High production capac- feed is pelletized, crumbled feed. There are
ity due to short cycle times several possible reasons for using this kind of
• Mixing under vacuum (as an feed. For instance, broilers do need as high as
option) enables the design of new possible energy input in short possible time.
production processes. Oxygen Pelletized feed is cooked and sanitized. This tion, it gives full control of the process feed because of gelatinization and micro tive components. There is no high-pressure
sensitive products can be mixed gives efficient and secure nourishment for and guarantee that the product will be agglomeration. The danger of de-mixing is treatment like in a pellets press.
under an inert atmosphere the birds. Finally, food regulations and the uniformly treated. hereby reduced, and can be reduced further Vitamins and other thermo-sensitive
• Less product damage due to miss- industry are based on established technol- The main achievements of the process are: by spraying of oil. materials like enzymes can be added after
ing edges of discharge doors ogy. • Destruction of salmonellae. For feed with optimum nutritional value heat treatment. There is no need for encap-
Figure 5
• Smaller tolerance (minimised Mash feed is now getting more widely The product is a pathogen free mixing is a basic process. The steam heat sulated vitamins. There is no need for over-
gap) between mixing paddles and used, mainly for layers. feed by reduction of other bac- treatment system also serves as a complete dosing. The thermo-sensitive components
mixer housing can be achieved For layers, mash feed has several advan- teria spores in the mash mixing plant. The feed is always perfectly can be dosed in the exactly needed amount
• In comparison with stationary tages. They are gained by using more time • Production of feed with course mixed. after heat treatment of the product.
batch mixers, the new and innova- to eat. Structure feed is more natural feed structure. The use of a roller mill Additional pre- and post-steam heat
tive F-RM machines combine high and gives better development of the gut. gives good results with mash feed treatment mixing installations are not
mixing quality and short mixing Though the use of mash feed is mainly • Feed with nutritional value that ide- necessary. A modern mixer with mix- Related Companies:
time with the discharge behaviour restricted to layers, mash feed is more ally meets requirements of the layers ing quality CV <5 makes over-dosing of Andritz Feed & Biofuel BV
and convenience of a cone bin natural feed than pelleted feed. The system • Preservation of thermo-sensitive com- ‘minor ingredients’ unnecessary. There Spaarpot 112, 5667 KZ, Geldrop
The well-known rotating vacuum coater, technology offers the possibility to heat ponents during production process is no danger for quality degradation of The Netherlands
F-RVC, has the same design as the F-RM treat big amounts of mash feed without • In production of feed with coarse ingredients. Tel: +31 40 2627777
Figure 6
Fax: +31 40 2627753
but is reinforced and equipped with vacuum taking the detour through a pellets press structure, the use of a roller mill The steam heat treatment system is a
Email: andritz-fb@andritz.com
equipment. This machine gives the optimum and milling the pellets down later on. The gives good results with mash feed. very flexible production method where addi- Website: www.andritz.com
result for deep core vacuum coating as used process is more economical. Generation of fines is also minimal. tion of vitamins and other thermo-sensitive
widely in high fat applications and medication Cooling of pellets is less efficient due to • Steam heat treatment of mash products can take place. More oil or fat Wynveen International BV
lines (see Figure 7). poor heat transfer rate (surface). feed leaves the natural struc- can be added to the mash feed compared PO Box 38, HETEREN, 6666 ZG
tion. This results in a whole list of practical, The steam heat treatment system is ture of the feed unchanged. to pelleted feed. Spraying of acid in order The Netherlands
operational benefits. Research and Development designed as a batch system. It makes it No fibers are destroyed during the treatment to prevent further bacterial growth is also Tel: +31 26 4790699
The rotating mixer (called the F-RM) has Mixing and processing - Mixing processes possible do dose exactly and to achieve due to the gentle mixing in the twin shaft possible. Fax: +31 26 4790698
the correct recipe, hence controlling the mixer. The end product has improved flow The ‘gentle’ steam heat treatment of the Email: info@wynveen.com
one inlet valve in the top where the product will always be one of the core processes
Website: www.wynveen.com
is introduced into the mixer. The valve closes in feed and food manufacturing. The twin- nutritional value of the mash feed. In addi- properties compared to traditional mash feed ensures preservation of thermo-sensi-
and the mixing cycle is started.
After the mixing cycle has finished, the
entire machine is rotated upside down Figure 7
and the product is discharged through the
same opening as for filling. The machine is
then rotated back 180° and is ready for a
new charge. A feature for the F-RM is the
automatic washing and drying of the mixer
(see Figure 6).
The F-RM is designed for the feed,
food, chemical and pharmaceutical
industries where airtight processes are
a must and cleaning is critical. It is also
possible to mix under vacuum, or under
an inert atmosphere to avoid oxidation
of highly sensitive products. Application
of steam or liquid nitrogen for sterilisa-
tion or coating is another interesting
option.
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them, and we will do everything we can to ensure that they continue to improve
your company’s productivity. With fully customized service plans we are able to
provide everything from reliable troubleshooting and original replacement parts
to technology upgrades, preventative maintenance, and consulting services.
Are you satisfied? Then we are too.
Bühler AG, Customer Service, CH-9240 Uzwil, Switzerland, T +41 71 955 30 40,
F +41 71 955 33 03, service.gp@buhlergroup.com, www.buhlergroup.com
The solution behind the solution.
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