RECYCLING LINES | TECHNOLOGY


fillers and fibres, requires high performance, especially in the mixing and degassing stages. This is why the use of twin-screw machines for re-extru- sion into granules offers significant advantages, in terms of greater flexibility in the formulation to reach the required result. Furthermore, the pres- ence of contaminants, which represents one of the primary difficulties in the regeneration of the PVC, can be reduced by a specifically designed filter change system. Bausano says that its MD Plus and MD Nextmover twin-screw extrusion lines are also suitable for recycling processes because they are able to process and remove impurities of plastic materials, such as PVC resulting from scraps or post-consumer waste. Davis-Standard offers extruders and associated technology that allows for broad flexibility in handling post-industrial and post-consumer film recyclate. The company says that it focuses on supplying systems with excellent versatility for turning low-bulk density film waste into a useable product. Systems typically include an extruder, melt filtration device, pelletiser and materials handling system. Material size reduction and transfer conveyors can be customised depending on the application. A machine widely used in this area is the


Ram-Stuffer single screw extruder, says the com- pany. This extruder can handle everything from light bulk density fluff to shredded flakes, and even materials with varied bulk densities. The Ram- Stuffer uses a pneumatically actuated plunger to force material into the feed section of the screw. The feed section has grooved technology to enhance the conveying of the feed material into the extruder barrel. Clean and dry, size-reduced, post-consumer material with less than 1% residual moisture can be processed on this extruder as well as mixed plastic materials for non-traditional applications like chemical recycling and direct processing into plastic lumber. Davis-Standard adds that the Ram-Stuffer is


mature technology that has performed well for recyclers for decades. It is simple to clean and maintain and supports lower costs upfront and during operation. Secondly, it has the versatility to handle a wide range of materials from fluff to pellet without changes to the machine itself. Processors can decouple the shredding and extrusion opera- tions to provide greater flexibility during downtime. If another component of the line unexpectedly shuts down, the machine can be easily restarted without a lengthy cleanout process. In addition to the Ram-Stuffer, the company has other options for the direct utilisation of reclaimed


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film material in sheet extrusion. Selecting the right extruder and roll stand is key to this process because bulk density/weight and free flow versus non-free flow (meaning the materials move with or without assistance) must be considered. Selection of the right extruder is according to material characteristics, as well as filtration options based on contamination levels of the reclaimed material. Roll stand capabilities to support material type, thickness, width, and outputs required for the application are also all-important factors. Most reclaimed films are light bulk density


materials, which are well suited for the Ram-Stuffer. However, there are also scrapper-extruder models, wide-mouth models and co-rotating twin-screw models that can be considered depending on the application. Direct reclaim sheet extrusion also requires the use of filtration systems and melt pumps to optimise processing. There are different levels of filtration depending on material contami- nation, and a melt pump is essential to reduce output pressure variability to the downstream feed block and die. Another piece of equipment to consider in direct reclaim sheet extrusion is the compactor. Compactors enable recycling and compounding of low bulk density materials with high residual moisture.


CLICK ON THE LINKS FOR MORE INFORMATION: � www.erema-group.com � www.starlinger.com � www.ecoblue.co.th � www.farrel-pomini.com � www.coperion.com � www.kraussmaffei.com � www.luigibandera.com � www.leistritz.com � www.sysplast.de � www.binovapm.it � www.bausano.com � www.davis-standard.com


October 2021 | PLASTICS RECYCLING WORLD 37


Above: The Ram Stuffer from Davis- Standard


IMAGE: DAVIS-STANDARD


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