Twin-Screw Compounder Reduces Energy Consumption in Recycling

For recycling of postconsumer recyclate (PCR), or any highly contaminated polymer, Coperion has developed the ZSK FilCo filtration compounder. The system enables filtration and compounding in a single production step, avoiding the need for the additional energy requirement of a second melt step.

The ZSK FilCo makes it possible to melt, filter, compound and pelletize recyclate in a single production system. Waste plastic is fed into the ZSK extruder in the form of regrind, fiber pellets, film flakes or agglomerate, and is melted, homogenized and devolatilized there, together with all its components. Next, the melt is fed through an integrated filter that removes contaminants. Reintroduction into the ZSK extruder process section follows, where reinforcing materials such as glass, wood and carbon fibers, or fillers such as talc, CaCO₃ or ground PEX, are added, after which the recompound is pelletized.

The ZSK FilCo’s space requirement is comparatively low. All product streams are added gravimetrically to the process with no fluctuations. The recyclate needs to be melted only once. According to Coperion, the ZSK FilCo consistently achieves a higher product quality than multipart systems that have been typically used for this recycling process.

Energy consumption and emissions for the extrusion process are markedly reduced. Thanks to the twin-screw extruder’s high mechanical energy input, the melting process is more energy efficient when compared to that of a single-screw extruder. In addition, the second melting process for compounding is completely eliminated in the ZSK FilCo solution, and pelletizing of the intermediate compounds is also omitted.

“The ZSK FilCo is one more result of our targeted efforts to optimize the recycling of plastics and to further increase the sustainability of the overall process. The ZSK FilCo’s excellent energy economy and the high-end product quality that it achieves are important benefits that will once again make PCR and polymer recycling a bit more attractive for many companies,” says Marina Matta, team leader process technology recycling at Coperion.