Plastic Recycling With Pelletron Technology0 pages

Leading Technology
STRANDPHASE® conveying
DeDuster® cleaning
V-shaped Rotary Valve
Pellbow® pipe bend

Plastic Recycling – with
Pelletron Technology
Specialized processes for production of virgin
grade PET resins made from recycled PET bottles
were initiated by the PET bottle and PET recycling industries.
It is common practice for plastics processing
companies to grind plastic scrap for reuse.
The regrind is dusty and needs to be cleaned
before reprocessing in a molding machine or
extruder. The Pelletron ­ eDuster is the most
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efficient dust removal machine on the market
for this purpose. The quality of the cleaned
regrind is nearly as good as virgin resin. Pelletron
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­ eDuster systems are available in many sizes
and configurations making them the obvious
choice for a variety of applications in a broad
range of capacities.
Recycling of PET Bottles
One of the most challenging tasks in recycling
is the transformation of PET bottles into resins
of high enough quality to yield superior
fi
­ nished products. Large scale recycling plants
are being built around the world to address this
challenge. For these plants, Pelletron developed a rotary valve with special inlet geometry
and a ­ -shaped rotor. Pelletron uses this valve
V
in conjunction with the unique pellcon3 conveying technology for efficient transfer of the
bottle regrind and finished pellets, along with
the DeDuster , the ideal machine for separation
of impurities from the PET flakes.
Typical PET Recycling Plant Design
PET bottles of all colors and shapes typically
arrive at recycling plants compacted and in
bales. The bales are cut open and the bottles
are processed through an intense rinse cycle.
This is followed by a number of ­ roprietary
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processes for flattening, sorting and distribution into clear and green flake ­ ines. After
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being divided, the bottles go through additional
processing steps including initial grindng, a
final wash cycle, and the separation of

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­ olyolefin (PO) materials from metal contaminants. The PO material passes through secondary grinders to produce a relatively uniform,
sellable flake product. Before storage, this
material passes through a series of quality
checks, a special cone blend silo to achieve
homogeneous product quality, a Pelletron
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­ eDuster for removal of fines and streamers, and a final sorter to assure the best
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­ olor purity.
Repelletizing PET
Some plants are designed to convert these
regrind flakes into high, virgin-quality PET
pellets for the production of food grade
p
­ ackaging. In order to get high quality PET
r
­ esins, the removal of paper, labels and other
contaminants is critical. The flakes then go
through a proprie­ ary pelletizing process
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where the intrinsic viscosity (IV) of the flakes
is increased and the material is transformed
into a uniform pellet shape for easy handling.
Before reaching the storage silos, the pellets
go through a series of quality checks to ensure
the highest standards in uniformity and quality.
Today, the industry standard for accepted dust
content in good quality plastic pellets is well
below 100ppm. To achieve this standard, the
pellets are typically transferred pneumatically
in the plant by using either slow motion conveying technology or Pelletron’s pellcon3
process. The pellcon3 process consists of
STRANDPHASE conveying with in-line Pellbow

Flakes before cleaning

pipe elbows and a DeDuster . This combination is specifically designed to achieve the
highest quality standard in the industry. The
shipment of flakes or pellets to the end user
is eventually done via truck, big-bags or railcar.
The Cleaning Process
All ­ eDuster systems are equipped with one
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or more electromagnetic flux field coils located
at the product inlet and/or outlet. These coils
produce a low level electromagnetic flux field
to break the electro static bond between fine
dust and finished product. The flux field covers
the entire cleaning area, called the wash deck.
Pressurized wash air flows through the wash
decks and the Venturi Zone which removes
dust and other contaminants. This combination
of electromagnetic flux field and air flow effectively removes fines to a level well below the
industry standard. The pictures below show
the contaminated flakes before cleaning in a
DeDuster , the removed contaminants, the
cleaned flakes and the finished PET resin.

Removed contaminants

Cleaned flakes

PET resin