VTT Technical Research Centre of Finland Ltd’s new cylindrical extruder is a promising device in processing recyclable materials and promoting a circular economy.
VTT
VTT’s cylindrical extruder
VTT’s cylindrical extruder can be used, for example, to turn problematic textiles and plastics as well as food waste into pellets.
The extruder can be used to turn problematic textiles and plastics into pellets. The first prototype has already exceeded the industrial steering group's expectations during initial testing. VTT is currently looking for a partner to commercialise the technology.
VTT's Principal Scientist Tomi Erho said: “Commercialising the device would create completely new possibilities both in terms of waste processing and novel material combinations.”
VTT's research scientists have been testing the prototype's performance with, for example, pieces of plastic film, mixed plastic waste, various kinds of textiles. In addition to recycling, the device has been used to produce long fibre composites.
VTT's Research Scientist Hannu Minkkinen discovered that materials can rotate around the device's hollow cylinder and designed the prototype with funding from Business Finland's and VTT's funding instrument for commercialisation of research results.
Senior Scientist Pirjo Heikkilä said: "Many textile recycling processes are only suitable for products containing homogeneous fibres. However, textiles are often made of a mix of fibres, and many products are comprised of different layers. The new extruder opens up a revolutionary opportunity to recycle mixed textiles and materials without having to separate fibres or components.”
Extrud-inary
The diameter of the extruder screw determines the size of the feed throat and the kinds of materials that the device is capable of processing. The first prototype has a screw diameter of 30cm instead of the 3-4cm typically found in conventional devices of the same output.
The large diameter combined with a shallow screw channel makes it possible to mix different components of problematic, porous and lightweight materials and to make the mixed mass compatible with the next stage of the production process.
The extruder offers numerous benefits due to its simple design. For example, it is cheaper to make than traditional mixing twin-screw extruders, less than two metres in length, upright mountable and compact, and temperature controllable.
