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Optimized processing for closing the recycling loop
Source:    Author:By Victor Cheng    Date:20.Sep.2018

Plastics are increasingly becoming the dominant materials of the modern economy, but only 9% of the world's plastics ever produced have been collected for recycling. Therefore, the recycling industry strives to optimize the recycling processes, increase throughput and improve the quality of end products, so that a better closed-loop recycling can be achieved.

Recycling system with high performance degassing

During the EREMA Discovery Days 2018, EREMA had its patented extruder system INTAREMA TVEplus with double filtration running in the R&D Center for live demonstration.

The system sets new standards in the recycling of materials that are difficult to process such as heavily printed films, very moist materials.

Typical materials can be processed by the system include heavily printed PE and PP films, washed PE film flakes, PE films with paper contamination, metallized BOPP films, etc.

The basic principle of TVEplus technology is that melt filtration takes place upstream of extruder degassing, improving the characteristics of the melt. As a result, end products can be produced with the best quality and the highest possible recyclate content even with difficult to process materials.

According to EREMA, feeding is automatic based on customer requirements. In the Preconditioning Unit, the material is cut, mixed, heated, dried, pre-compacted and buffered. Next, the tangentially connected extruder is filled continuously with hot, pre-compacted material.

In the extruder screw the material is plasticized and degassed in reverse. At the end of the plasticizing zone, the melt is directed out of the extruder, cleaned in the fully automatic, self-cleaning filter and returned to the extruder again. The final homogenization of the melt takes place after the melt filter. In the subsequent degassing zone, the filtered and homogenized material is degassed.

Following this, and with the help of the discharge zone, the melt is conveyed to the respective tool (e.g. pelletizer) at extremely low pressure.

A groundbreaking innovation that is noteworthy is the Counter Current technology which enables enhanced material intake, greater flexibility and higher throughput rate.

In the past, the material inside the cutter/compactor turned in the same forward direction in the same direction as the extruder. The patented Counter Current technology now changes the direction of rotation to opposite direction to that of the extruder screw. The relative speed of the material increases to such an extent that the extruder acts in the same way as a sharp edge which literally “cuts up” the plastic.

As a result, the extruder handles more material in a shorter time and at lower temperatures at a high throughput.

The INTAREMA TVEplus system is also equipped with Smart Start and ecoSAVE features, which facilitates extremely easy operation and reduces energy consumption by up to 12% repectively.

Efficient plastic direct recycling in one step

Repro-Flex is Polystar's high efficiency, all-in-one plastic recycling machine designed for reprocessing HDPE, LDPE, LLDPE and PP flexible packaging material, printed and non-printed. In addition to in-house (post-industrial) film waste, the system is also able to process washed flakes, scraps and regrind (pre-crushed rigid plastic waste from injection and extrusion).

The Repro-Flex all-in-one plastic recycling machine.The integrated machine combines cutting, extrusion and pelletizing into one compact and efficient recycling line. The cutter/compactor pre-conditions the material into an ideal condition for the extrusion process and feed the material directly into the extruder with a centrifugal force.

As a separate crusher is not required, it eliminates the problem of over or insufficient feeding. The tangentially connected extruder is continuously filled with pre-compacted material, and results in a high production output.

In addition, the stable material feeding together with the hot die face pelletizer produce round-shaped, uniformed size pellets that are higher in value and optimal for reproduction (extrusion processes).

On average, post-industrial waste makes up 5% or more of the entire production line, making in-house recycling very important as it can significantly reduce the cost of raw material purchasing.

The pellets produced from in-house waste by the Repro-Flex are almost like-new and can be put directly back into the production line, in most cases for blown film or pipe extrusion processes, according to Polystar.

The Repro-Flex is also designed to work with washed, post-consumer and used agricultural film. The recycled pellets can be used again in extrusion process, whether 100% (such as garbage bag, LDPE pipe production, etc.) or as part of the mixture to reduce raw material cost. The pellets quality can also be improved by direct dosing of masterbatch and additives.

New technology for separating PET trays

Brand new sorting application for recycling has been made possible by higher light intensity. TOMRA Sorting Recycling introduced a new technology called TOMRA SHARP EYE, which helps to separate single-layer PET trays from PET bottles. This enhances the previous capability of the company’s AUTOSORT machine to separate multi-layer trays.

The company says this breakthrough is commercially significant because PET food trays and PET bottles have small but critical differences in chemical properties, meaning that they have to be separated for equivalent-product recycling.

According TOMRA, the key to the new TOMRA SHARP EYE technology is an enhancement of its FLYING BEAM sensor technology. As a near-infrared (NIR) scan system with point-scanning (and no need for external lamps), this focuses only on the area of the conveyor belt being scanned. Allowing a wide range of calibration possibilities, this can distinguish even the finest molecular differences in materials flowing down the recycling line. As TOMRA SHARP EYE introduces a bigger lens for higher light intensity, it is possible to detect even the most difficult to distinguish properties.

During the preparation for sorting mixed plastics into different polymers, packaging material collected or pre-sorted from municipal solid waste (MSW) first runs through a mechanical treatment process which reduces voluminous materials, mainly soft items such as plastic, film, and non-plastic products.

To then separate mixed PET into different polymers, TOMRA AUTOSORT machine functions as a combined system, detecting material and color in combination with grain size. As said, even with a very mixed material input, this process achieves an impressive sorting efficiency of 95% or greater.

The new TOMRA SHARP EYE technology is expected to be welcomed by collection-and-sorting plants and by PET regeneration centers, as the widening adoption of on-the-go lifestyles is pushing-up the use of plastic drink bottles and trays for food.



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