PureCycle has selected KraussMaffei to supply the extrusion technology it will use at the flagship it is currently constructing in Ohio.
The plant, which is scheduled to begin operating at scale in 2022, will be equipped with several extruders delivered by Hannover-based KraussMaffei Extrusion, which is acting as a ‘full-line provider of various extrusion technologies’, according to Carl Philip Pöpel, Director of Product Management at KraussMaffei.
PureCycle uses proprietary solvent purification technology licensed from The Procter & Gamble Company (P&G) to convert carpet scraps based on polypropylene (PP) composite material into high-purity pellets that are equivalent to virgin material.
The core component of the new PureCycle line is the extraction process. The technique eliminates dye residues, foreign plastics and odours from the melted PP composite material . What remains is a pure PP melt and a recycled, re-usable co-product. The circulating solvent is then purified and returned to the process.
The technology has been shown to remove all impurities, odours, and dye residues from carpet remnants, producing PP pellets that are equivalent to virgin material, both in terms of appearance and mechanical properties. Hence, the next step, having successfully passed the pilot phase, is the construction of the world's ‘most modern PP recycling line’, as Brett Hafer, VP Manufacturing at PureCycle described it.
The dry PP carpet scraps that are the feedstock for the PureCycle process are fed into two twin-screw extruders from KraussMaffei. Thanks to their high torque density of up to 16 Nm/cm³, they plasticise the starting material even at moderate temperatures and low speed and thus ensure optimum material homogenisation and minimum energy consumption. Both extruders supply up to 8 metric tons of processed feedstock per hour via a melt pipe into the PureCycle process.
After passing PureCycle’s first processing stage, the cleaned melt is fed into the degassing extruder, specifically designed to effectively remove any high-molecular residual monomers. Volatile matter like solvent residues and other impurities, such as adhering odorous substances and low-molecular compounds, are gently separated from the melt.
The process yields pure PP pellets that are suitable for a wide range of injection moulded or extrusion coating applications.
“The collaboration and support we received from KraussMaffei has been exceptional. Collectively, we achieved real technical innovations and developed an exceptional solution for our process. We look forward to continuing this relationship as we scale our Ultra-Pure Polypropylene Technology globally,” said Scott Brown, Vice President of Program Management at PureCycle.
The complete installation of the plant will be an important milestone in the plastics recycling. landscape.