automobiles were mostly hand built one by one…a work of art. Not
many consumers could afford one. Cars ended up as toys for the rich
in the beginning. Then came Henry Ford, who figured out how to
build high quality automobiles quickly and inexpensively using an
assembly line. Car prices went down and suddenly the common man
could afford a car. The art and craftsmanship that went into
constructing one car at a time, was no longer needed.
THE ART OF SEED
If you remember
the SeedTech Newsletter, “Putting Pellets Around Seed – A Science and an Art”
I explained how pelleting seed in a rolling pan involved some art.
How much adhesive to spray, how much powder to add, how long to let
the pellets roll, are all part of what pelleters need to decide each
time they pellet a new batch of seed. Well….much like Henry Ford’s
assembly line, the rotary coater takes the art out of seed
pelleting, and lowers the cost of production. Lowering the cost to
pellet seed can make it a viable option for less expensive agronomic
seed like field corn.
A ROTARY COATER WORKS
Seed mixes evenly
Seed is placed
into a spinning bowl. Centrifugal force pushes the seed upward and
outward against the inside walls of the bowl. A wedge or some other
obstacle is located in front of the moving seed. The wedge peels
the seed off the wall as it spins and guides it into the center of
the bowl where centrifugal force again moves it back to the
outside. Place several of these obstacles in the spinning bowl and
you have nice mixing action. Below is a picture of sweet corn
mixing in a small rotary coater.
In the center of
the spinning bowl, a small dish rotates in the opposite direction of
the bowl. Pump liquid seed treatments (or adhesives for pelleting)
down a tube directly on top of the spinning dish. The liquid falls
onto the spinning dish and is flung outward hitting the mixing
seed. Here’s a picture of the liquid being dispersed
A powder feeder is
positioned on the coater dropping powder on top of the mixing seed
while the liquid adhesive is dispersed. Here’s a picture of a
Continuous Batch Systems
liquid and powder can be measured very precisely and automatically
in a Continuous Batch System. At the push of a button, a certain
weight of seed is added to the spinning bowl, a certain amount of
liquid is added to the spinning dish, and a certain amount of powder
is added to the mixing seed. When everything is done, the door on
the spinning bowl automatically opens and the seed is dumped onto a
conveyor and to the drier to dry. New seed automatically is dumped
into the bowl to start the process all over again. In the picture,
the rotary coater dumps onto a conveyer and over a gravity table
which has been modified to blow heated air on the moving seed to
remove any tackiness before going to the dryer to be fully dried.
becomes an assembly line that need only be monitored periodically.
What would normally take about 2 to 3 hours in a pelleting pan may
take 5 to 15 minutes in the rotary coater. Some agronomic seed
companies are starting to use the rotary coater to increase the
weight of small seeded field corn as noted in these two articles on
seed companies, seed technology companies and greenhouses have also
started to set up systems to pellet seed using rotary coaters.
Pelleting seed in a rotary coater seems to be the wave of the
That’s all for
If you’d like
more information on rotary
coaters check out this Web article from Incotec:
Next time we’ll
talk about “How DNA Techniques Help the Seed Industry” .
See you then.