KraussMaffei Group GmbH says it has developed the world’s most modern recompounding line featuring a proprietary cutter-compactor unit for pre-treating post-consumer waste of any type and a turnkey module for recycling it.
The Hanover, Germany-based machine engineering firm says its EdelweissCompounding technology offers a two-stage extrusion system comprised of two twin-screw extruders arranged in a series for melt processing and compounding.
The use of two twin-screw extruders is a novelty compared to past combinations of a single-screw and a twin-screw extruder, according to KraussMaffei, which says the benefits include high degassing capacities, odor removal, ideal dispersive and dispersing mixing effects, and gentle melt treatment with almost no limits of throughput rate.
The new EdelweissCompounding line is composed of two ZE 65 BluePower twin-screw extruders and designed for a maximum output rate of 2,000 kg/h, according to KraussMaffei.
In the first stage, the twin-screw extruder degasses the starting material and removes any adhering substances with odors, which KraussMaffei says is important when recycling post-consumer waste. The odor abatement can be intensified by using water, nitrogen or carbon dioxide as entrainer for degassing, the company also says.
“In addition, the first twin-screw extruder ensures optimum homogenization of the input material that is often characterized by rather inhomogeneous quality,” Carl-Philip Poepel, director of extrusion product management, said in a news release.
The melt is then conveyed by pipe into the second twin-screw extruder where the 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, fibers and liquids,” Poepel added.
KraussMaffei says its twin-screw extruders have gravimetric metering systems for various media and downstream equipment such as fine filters, pumps and pelletizing units from BKG-Systems from Nordson Corp.
The cutter-compactor unit, which KraussMaffei has recently integrated into its portfolio, easily feeds rigid fractions into the first twin extruder while light and fluffy material fractions, such as fiber and film scrap, need to be prepared for further processing, according to the company.
The material fraction is first dehumidified, compacted and homogenized in the cuter compactor and then it is transferred into the ZE 65 BluePower extruder.
The new cutter-compactor unit is operated offline and the agglomerate material produced is discharged onto a belt weigher, which Poepel says enables gravimetric metering with an accuracy of 99.8 percent.
By eliminating metering variations, KraussMaffei says all post-consumer low density polyethylene, high density PE, polypropylene or polystyrene fractions can be easily processed into high-quality recompounds and used as a substitute for new material in both injection molding and extrusion applications.
In addition, the new turnkey module can be installed in any facility. When delivered, the line only needs to be connected to the local power, water and compressed air supply and production can be started immediately.
If the line has to be moved, KraussMaffei says the module can be transported as a whole and is immediately ready for production without any changes required.
“Interested customers can carry out industrial-scale trials on the new state-of-the-art EdelweissCompounding line in our R&D center and convince themselves of the benefits offered by the overall modular-design plant concept,” Poepel said.