Highlights of the compounding line are the new proprietary cutter-compactor unit for pre-treating post-consumer waste of any type, and the two-stage extrusion system composed of two twin-screw-extruders arranged in series for melt processing and compounding.
KraussMaffei’s unique Edelweiss Compounding technology stands out for excellent recompound quality at high throughput rates of several tonnes per hour. This technology is based on an established process that has been further optimized and extended by the machine engineering company.
“The Edelweiss compounding line is now available for customer trials in our R&D centre and convinces not only by its innovative technical features, but also by the turnkey concept,” says Carl-Philip Poepel, Director of Product Management Extrusion Technology at KraussMaffei.
KraussMaffei is currently investing to substantially extend its capacities for customer trials and its own testing activities associated with recycling and recompounding processes. For some months now, the R&D centre at the Hanover site has been equipped with the most advanced industrial-scale recompounding system worldwide. The new Edelweiss Compounding line is composed of two ZE 65 BluePower twin-screw extruders and designed for a maximum output rate of 2,000 kg/h. While it was common practice in the past to combine a single-screw and a twin-screw extruder for this purpose, the use of two twin-screw extruders is a real novelty. The benefits of this solution speak for themselves: high degassing capacities, efficient odour removal, ideal dispersive and dispersing mixing effect, gentle melt treatment – and all this with almost no limits in terms of throughput rate.
In the first stage, the ZE65 BluePower twin-screw extruder degasses the starting material and removes any adhering odorous substances. This is particularly important when recycling post-consumer waste. Odour minimization can be intensified by using water, nitrogen or even carbon dioxide as entrainer for degassing, which is easily possible thanks to the wide range of metering and degassing options offered by KraussMaffei’s twin-screw extruders.
“In addition, the first twin-screw extruder ensures optimum homogenization of the input material that is often characterised by rather inhomogeneous quality,” says Carl-Philip Poepel highlighting a decisive benefit of the new machine combination. Via a melt pipe, the melt is conveyed into the second twin-screw extruder where the actual compounding process takes place. “Filling, reinforcing, pigmenting and incorporation of additives – the twin-screw extruder is designed for any given process task. This is why our extruders are equipped with all auxiliary units for metering pellets, powder, fibres and liquids,” adds Poepel.
It goes without saying that KraussMaffei’s twin-screw extruders are provided with gravimetric metering systems for various media as well as with the appropriate downstream equipment such as fine filters, pumps and pelletizing unit from BKG®-Systems from the Nordson Corporation.
Proprietary cutter-compactor unit
Another new feature of the Edelweiss line is the cutter-compactor unit, which KraussMaffei has recently integrated into its portfolio. While rigid fractions with an apparent density of over 0.3 kg/l can be easily fed directly into the first twin-screw extruder, particularly light and fluffy material fractions need to be prepared for further processing. The new cutter-compactor unit is the ideal solution for these light fractions, such as fibre and film scrap with high input moisture contents of up to 10%. In the cutter-compactor, the material fraction is first dehumidified, compacted and homogenized before it is transferred into the ZE 65 BluePower extruder.
In contrast to known concepts that have been available on the market so far, the new cutter-compactor unit is operated offline and the agglomerate material produced is discharged onto a belt weigher. “This enables gravimetric metering with an accuracy of 99.8 %,” says Poepel, to emphasise the decisive difference to volumetric metering used up to now. Metering variations that tend to occur with light fractions are thus excluded. With this solution, all post-consumer LDPE, HDPE, PP or PS fractions can now be easily processed into high-quality recompounds and used as a substitute for new material in both injection moulding and extrusion applications.
Turnkey module for recycling post-consumer waste
Last but not least, the EdelweissCompounding line installed in the R&D centre is completely integrated into a turnkey module. The essential benefits for the owner are easy installation without any preparation, rapid set-up and start-up and well as flexible use. The new turnkey module can be installed in any hall. Neither different levels of installation nor a special hall construction are required, as the module of well-conceived design contains all elements required for recompounding. When delivered, the line only needs to be connected to the local power, water and compressed air supply and production can be started immediately. In the event of relocation, the module can be transported as a whole and is immediately ready for production without any changes being required.
In-depth plant engineering competence meets extensive formulation know-how
“Interested customers can carry out industrial-scale trials on the new state-of-the-art EdelweissCompounding line in our R&D centre and convince themselves of the benefits offered by the overall modular-design plant concept.” KraussMaffei’s Director of Product Management invites customers to get in touch for joint development projects.
Thanks to the unique combination of unparalleled mechanical engineering expertise with an enormous wealth of experience in the creation of specific formulations for the production of high-quality compounds and recompounds from post-consumer and post-industrial waste, the Hannover-based company is an ideal partner for up-cycling projects of any type. A well-equipped analytical laboratory and an injection moulding machine for the production of first product samples from the compounds produced on the EdelweissCompounding line perfectly round off the package solution.