Post consumer PET bottles

Post-consumer PET bottles are doubtless among the most important components of the recycling market. Recycled PET may be used in a wide variety of final applications, with very interesting and remunerable financial returns for the recycling companies.

As the quality of the collected PET bottles varies significantly from country to country, and even within the same country, and as their conditions can be very bad, it is necessary to be continuously updated on the technologies and technical solutions of PET recycling, in order to correctly process the most difficult and contaminated materials and reach the best final quality.

SOREMA, thanks to its worldwide experience in the field of PET bottle recycling, can provide its customers with proper technical solutions and state-of-the art recycling technologies, delivering a response tailored to the frequently changing needs of its customers and of the market.

PET bottle recycling lines

SOREMA has a long experience in the field of PET recycling and has installed hundreds of PET bottle recycling lines all over the world. Its clients can therefore benefit from the most performing recycling technology and a recognized know-how, assuring the best quality rPET flakes.

Thanks to its long and successful experience in PET recycling, SOREMA offers state-of-the-art recycling technologies, with turn-key installations having the widest range and flexibility in production capacity (from 500 to over 9.000 Kg/h outputs).

At present, with hundreds of PET bottle recycling lines active all over the world, SOREMA detains the largest share of the PET recycling market: more than 2 million tons of post-consumer PET bottles are processed yearly by SOREMA PET washing lines around the world.

1. Feeding & bale breaker2. Dry separation3. Delabeler4. Hot/cold prewashing5. Automatic and manual sorting6. Wet grinding7. Hot washing8. Sink/float separation9. Rinsing10. Drying11. Fines separation12. Flakes sorting13. Blending14. Storage and packaging

Incoming PET bottle bales are received, opened and regularly fed into the line for material detection. Bottles are metered into the line flow for steady process control. The inclined conveyor belt is normally position beneath the floor level to accommodate the entire bale. This design gives the operator time to perform other functions in addition to loading.The feeding process can be accomplished very quickly and cleanly.

The bale breaker is equipped with 6 shafts, driven by oleo dynamic motors with slow rotation speeds. The shafts are provided with paddles that break the bales and allow the bottles to fall without breaking.

This section allows the removal of many of the solid contaminants (sand, stones, etc.), and represents the first dry cleaning step of the process.

This module has been engineered by SOREMA to solve the problem of sleeve (PVC) labels. SOREMA has designed and developed a system that can easily open the sleeve labels without breaking the bottles and saving most of the bottles necks. The system, installed in many of SOREMA’s recycling plants, has also proved to be a valid dry cleaning solution for other plastic materials. For more information, see the specific sections of our site: “Dry Cleaning” and “Delabeling System”.

This SOREMA-patented washing step is essential for the line to be able to accept the worst quality PET bottles, continuously removing large and abrasive contaminants. Hot or cold prewashing can be used to partially remove paper or plastic labels, glues, and initial surface contaminations. This is accomplished by using slow moving machines with very few moving parts. This section uses water coming from the washing section, which would otherwise be discharged as waste. For more information, see the specific section of our site: “Bottles Prewashing”.
This section allows the separation of large contaminants, either manually or automatically.

Manual sorting station

The manual sorting station consists of a horizontal conveyor belt with platforms on either side, discharge chutes and a discharge conveyor for centralized contaminant disposal (optional – on demand).

The ergonomic and flexible design allows the presence of a variable number of operators, depending on the requirements of the specific task.

Automatic bottle sorting

Several near infrared (NIR), color, or metal detection systems are engineered into the line, based on local feed stream diversity. Wrong colored PET bottles and bottles of different plastic type or material are removed through the implemented detection technologies, often in combination with manual sorting. Materials which shouldn’t be present are ejected by a compressed air jet.

In this section, PET bottles are cut into smaller pieces to achieve the required size distribution for the washing sections that follow. At the same time, a first washing process is performed in this section, eliminating the worst contaminants and preventing them from entering the more expensive, chemically treated, downstream washing steps.

For more information see the specific section: “Wet Grinding”.

In this section, PET bottles are cut into smaller pieces to achieve the required size distribution for the washing sections that follow. At the same time, a first washing process is performed in this section, eliminating the worst contaminants and preventing them from entering the more expensive, chemically treated, downstream washing steps.

For more information see the specific section: “Dynamic Separation Tanks”.

The target of this section is to remove any polyolefins (polypropylene and polyethylene labels and closures) and other floating material and to conduct a secondary washing of the flakes. The heavier PET material will sink to the bottom of the flotation tank, from where it is removed.

Hot rinsing occurs after friction washing to remove from the flakes the majority of the NaOH initially present. pH is tested at this stage to ensure that proper rinsing has been carried out. If needed, an additional and final rinsing step to ensure high quality rPET flakes, stabilize pH, and conduct the final flake washing could be engineered by SOREMA.
Mechanical drying

Initial mechanical drying through a centrifuge allows the removal of water deriving from the final rinsing process.

Thermal Drying

A second thermal dryer properly treats the flakes with time and temperature to remove surface moisture, achieving a humidity below 0.6%-0.7%.

For more information see our specific section: “Drying modules”.

An elutriation system is used to separate remaining labels, having dimensions close to those of the rPET flakes size, as well as PVC, PET film, dust and fines.

Any final metal, alien material or color is removed thanks to automatic, high quality, flake sorting technologies, ensuring an extremely high quality performance of the final rPET flakes.

Dried, elutriated and purified flakes are then sent to mixing silos where the material is folded and homogenized to smooth out any variability and slugs of alien material that may have not been removed in the previous steps of the process. The finished product is removed and tested in 1-10 kg samples. Fines are also removed in this step (de-dusting).

The dried and separated flakes are then packaged from the storage silos into super sacks with a high density filling system.

The SOREMA Delabeler (patent pending) is a de-labeling system allowing the removal of sleeve labels in post-consumer PET bottles recycling lines.

Thanks to the specific and accurate SOREMA prewashing and washing systems, the properties of the rPET flakes resulting from the SOREMA PET bottle recycling plants are closely comparable to those of virgin PET.

As a matter of fact, SOREMA PET bottle recycling lines can eliminate many of the worst contaminants in the early steps of each process, ensuring a longer life and higher wear resistance of the machineries and increasing the efficiency and performance of the process as a whole.

Plastic recycling: final applications

rPET Flakes resulting from any SOREMA PET bottle recycling line are of the highest quality in the market, making them perfectly suitable for many of the most important applications, such as: