Eggersdorf bei Graz, Austria – Mechanical recycling machinery manufacturer Redwave has reported on its progress as part of the Puresmart project (styled PUReSmart), an initiative supported by the EU Horizon 2020 research and innovation programme. Puresmart aims to stimulate the development of technology for end of life (EoL) treatments, including both chemical and mechanical recycling techniques.
Until recently, discarded mattresses were considered unrecyclable: 60% ended up in landfill, and the remaining 40% were incinerated.
In 2019, the Puresmart consortium set out to find ways to make the life cycle of PU circular. Puresmart has investigated not just how to recycle mattresses, but also how to manufacture mattresses in a way that supports more efficient material recovery at EoL. From its foundation, Puresmart recognised that effective PU recycling would require a reliable mechanical sorting process before the chemolysis (chemical recycling) process.
Austria-based Redwave has announced the development of the first near-infrared (NIR) sensor-based sorting technology for flexible PU foam. NIR reflectance spectroscopy is a technology that has already proven itself in the recycling of thermoplastics (PET, PE). The Redwave sorting machine takes this technology and uses it to identify and sort PU foams. Currently it is able to identify and sort between 20-30 different types of PU, including MDI-based foam, conventional PU foam and HR-based foam, as well as foams containing additives including flame retardants.
This mechanical sorting will make it easier to recover polyols and isocyanates from EoL PU foam in the downstream chemolysis processes.
Redwave’s PU sorting machine, features an acceleration belt which feeds material to a detection unit comprised of halogen lights, a spectral sensor, and an ejection unit that separates the material into one of two shafts. The company says extensive tests have been performed on comminution and screening equipment to define pre-processing steps for EoL flexible PU foams that allow the highest throughput, yield and sorting quality.
Redwave’s partners in the Puresmart consortium include French consultancy company Benkei, Covestro, Italian circular economy consultancy Eco Innovazione, Belgium’s KU Leuven, Recticel Engineered Foam, Spain’s Universidad de Castilla – La Mancha, Belgium’s Universiteit Gent, and WeylChem Innotec of Germany.
The project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 814543.
