Extrusion International 6-2025

61 Extrusion International 6/2025 Odour Reduction in Plastic Recycling Every day, large quantities of post-consumer plastic waste are generated from packaging, household appli- cations, and more. Despite the costly processing of this waste through sorting stations and wet washing, the output from these material ows often cannot be re - used for high-quality applications due to remaining un- pleasant and pungent odours in the granulate. Current recycling processes are inadequate for removing these odorous substances, which have migrated into the ma- terial during the product's life cycle. A multi-stage treatment is required to eliminate these odours suf ciently, allowing the pellets to be processed into high-quality end products for applications in in- dustries such as packaging, automotive, and consumer goods. Next Generation Recyclingmaschinen (NGR) and Krey- enborg have announced a strategic collaboration to sustainably enhance the quality of the recycled prod- uct through innovative technologies aimed at reducing odours and emissions. This partnership combines NGR's know-how in ef cient recycling of plastic waste streams with Kreyenborg's innovations in heat treatment of re - cycled pellets. A modular, energy-ef cient system has been developed that minimizes unpleasant odours in post-consumer plastics, thereby increasing the accep- tance and potential applications of recyclables in high- quality applications. Maximum Cleaning in the Melting Phase of Plastic The process begins with an exceptionally ef cient re - granulation step based on NGR’s proven C:GRAN cas- cade technology. An initial cleaning step occurs in the cutter compactor, where warm exhaust air from the cylinder cooling system ows through the preheated material. Optionally, a degassing zone can already be integrat- ed before the melt lter to remove volatile contami - nants. In the subsequent melt lter, all solid particles are removed from the melt stream. After ltration, the melt is fed into a high-performance degassing zone within a cascade extruder. This "power venting section" acts as a surface genera- tor and, along with an ef cient vacuum system, facili - tates maximum degassing performance. The goal is to remove volatile impurities from the melt as thoroughly as possible. After passing through the cascade, the melt is granulated, and the granules are transported to the Kreyenborg IR-Fresh Conditioner for post-treatment. Thermal-Physical Post-Cleaning using the Kreyenborg IR-Fresh Conditioner In the second crucial step for overall process quality, remaining low-molecular impurities are reliably removed through a thermal-physical cleaning process in the IR- Fresh Conditioner. This specially designed container maintains the material at the optimal temperature range for decontamination using a stream of hot air. The precise interaction of the process parameters en- sures consistently excellent deodorization and decon- tamination results, as evidenced by numerous successful tests conducted on various material streams. For extremely stubborn volatile contaminants, the ground material can also be pre-treated before the ex- trusion step. This treatment removes odorous substanc- es from the surface before they are incorporated into the melt during the extrusion process. Kreyenborg's proven infrared technology quickly brings the material to the ideal temperature for the respective plastic. The continuous rotation of the IR drum ensures a homo- geneous mass ow with a de ned dwell time ( rst-in/ rst-out principle), whilst integrated rotation and mix - ing elements guarantee constant surface exchange. This pre-treatment, in combination with the IR-Fresh Conditioner, signi cantly enhances odour removal in a short residence time, greatly contributing to the overall success of the recycling process and improving energy ef ciency. C:GRAN – Cascade with „Power Venting Section“ + Kreyenborg Conditioner