From the Sector

Breaking new ground in plastics recycling means assessing the value chain from end to end. The big opportunities for the future are in fine-tuning the individual process steps; from the collection of recyclable materials to the recycling process and the end product. This is where the cooperation of Lindner and the EREMA Group comes in, officially launched following the 50/50 founding of the holding BLUEONE Solutions in August 2023 to which shares of Lindner Washtech were contributed. The expertise of EREMA, a manufacturer of extruders and filtration solutions for plastics recycling and the largest company within the EREMA Group, has now been combined with the expert know-how from Lindner Washtech, a leading provider of all-in-one solutions for shredding, sorting and washing plastic feed materials.

Data transfer ensures more efficient recycling processes
Process control is an especially important aspect of plastics recycling, which is why standardising the process control system was what the two companies focused on first. "Together, we have developed a platform that allows data to be exchanged between the extruder and the washing system," says Manfred Hackl, CEO of the EREMA Group at IFAT in Munich. "This enables us to analyse the data more precisely so that effective improvement measures can be deduced." All key parameters are taken into account and monitored via a digital interface. For example, it is possible to use information relating to the current throughput of the EREMA Pre Conditioning Unit to optimise the washing process as soon as possible so that it can compensate for fluctuations in capacity and achieve a significant increase in output. This data transfer represents a new step on the roadmap to digitalization.

High efficiency due to smart energy management
"To ensure sustainable recycling, it is necessary to find the right process for each application and to make sure that the individual process steps are perfectly coordinated," emphasizes Michael Lackner, Managing Director of Lindner. Coordinating the process steps has already achieved initial success in energy management, and a clear example of this is heat recovery. "We use the latent heat generated during the extrusion process as an energy source for the washing and drying process," explains Lackner. "This enables our customers to sustainably reduce their energy costs and carbon emissions".

Making the most of synergies along the value chain
Synergies need to be used to establish the quality standards specified for each end application. "The key question is how we can improve the end product and increase the overall efficiency of the recycling process at the same time," agree Manfred Hackl and Michael Lackner. This will only work if companies work together along the value chain. The industry leaders can already point to several examples where together they have improved recycling processes and made it possible to move away from downcycling. "An example of this is the recycling loop of HDPE starting material, which is processed into high-quality, food-safe rHDPE pellets using our two technologies," says Lackner. Lindner Washtech and EREMA continue to work intensively together to develop strategies for upcycling plastics and increase recycling rates.

With the goal of making recycling of lightweight, high-volume fiber and flake recyclate much more economical and, in some cases even possible, Coperion has developed a new version of its ZS-B side feeder. Using the innovative ZS-B MEGAfeed, plastic recyclate with a bulk density under 200 kg/m³, long considered intake-limited and thus not worth recycling, can be reliably fed in large quantities into Coperion’s ZSK twin screw extruder and be concurrently recycled and compounded.

The ZS-B side feeder’s novel design makes it possible to feed very high rates of fiber and flakes, such as PA, PE, PET, and PP. As a result, the ZSK twin screw extruder’s high capacity can be fully exploited when the ZS-B MEGAfeed is used. Very high throughputs in both mechanical and chemical recycling of post-industrial and post-consumer waste are achieved.

Increased Throughput in Numbers
With a ZSK 58 Mc18 twin screw extruder, the throughput increase and thus the potential of the new ZS-B MEGAfeed becomes very clear. When recycling PA fibers with a bulk density of ~40-50 kg/m3, throughputs of 70 kg/h were previously achieved using conventional equipment. When the PA fibers were fed into the ZSK extruder using the ZS-B MEGAfeed, throughputs increased about fourteenfold to 1,000 kg/h. Similar results were achieved recycling carbon fibers with a bulk density of ~50-70 kg/m3; in this case, throughputs increased from 50 kg/h to 2,500 kg/h using the ZS-B MEGAfeed. When recycling PCR (Post-Consumer Recycled) flakes, throughputs increased from 50 kg/h to 700 kg/h, and from 80 kg/h to 1,300 kg/h with multilayer film flakes.

Key to Economical Recycling of A Wide Variety of Plastics
Plastics previously considered not recyclable are becoming a valuable raw material using the new Coperion ZS-B MEGAfeed. For example, PCR flakes or recyclate from carbon fiber-reinforced plastics can now be fed into the ZSK extruder at high feed rates and recycled economically.

In the case of mechanical upcycling, upstream processes necessary for compounding, such as compacting, melting and agglomeration, are completely eliminated using the ZS-B MEGAfeed technology. In this recycling process, flakes and fibers can be fed directly into the ZSK extruder, where they are melted, compounded, devolatilized, and filtered in a single step. In so doing, both investment costs and energy consumption drop. The production process becomes significantly more efficient. Moreover, the thermal product stress is reduced and recyclate quality increases.

Even when recycling PET, the feed rate is no longer a limiting factor. With the ZS-B MEGAfeed, PET flakes and fibers can be fed into the ZSK twin screw extruder in large quantities with no pre-drying or crystallizing, where they can be processed with the highest degree of profitability.

The ZS-B MEGAfeed can also feed large quantities of post-consumer waste, adding appreciable value to the chemical recycling process with the ZSKs. ZSK throughput rates are very high with the ZS-B MEGAfeed. Preheating of the recyclate via mechanical energy input of the twin screws thus becomes even more economical for further processing in the reactor.

Existing Coperion extruders can be retrofitted with ZS-B MEGAfeed technology to greatly expand their spectrum of applications and increase their throughput rates.