15.05.2019 change 15.05.2019

A new method of recovering raw materials from multi-material packaging

Photo: Fotolia Photo: Fotolia

A new method of recovering raw materials from multi-material packaging, in which, for example, fruit juices are sold, has been developed by scientists from the Silesian University of Technology. Compared to previous solutions, the method allows to achieve better quality of recycled plastic.

The Gliwice Municipal Office informed in its bulletin about the patented technology from the Faculty of Chemistry of the Silesian University of Technology. It concerns the recovery and reuse of so-called tetra paks, as the laminated cartons, for example for beverages, are colloquially called.

They consist of paper, a layer of polyethylene (a plastic) and aluminium. Each component has a specific function: cardboard provides durability, polyethylene protects against moisture, and thanks to aluminium, juices and milk have longer shelf life. Paper, accounting for 75% the whole packaging, is currently most often recovered for re-use.

"It is much more complicated to recover the remaining raw materials: aluminium and polyethylene from the laminate, which remain after separating the paper. In Poland, it is still an unsolved problem" says Prof. Jan Zawadiak from the Faculty of Chemistry of the Silesian University of Technology.

His team has developed a new method of recovery of raw materials from tetra paks. The laminate is crushed and mixed with a hot solvent. Aluminium does not react with it, so it can be centrifuged. Then, after evaporation of the solvent, polyethylene precipitates in the form of granules.

"Previously used solvent recovery methods allow to recover polyethylene in the form of a solution of high viscosity, which it is difficult to separate from the solvent. The advantage of our technology is that we obtain polyethylene powder with properties similar to a pure raw material" - explains Prof. Zawadiak.

The technology has been submitted to the Patent Office, and the Paper and Cardboard Factory in Wadowice is interested in its implementation. The factory recycles packaging materials of this type.

Researchers have already tested a pilot installation at the paper mill. "Polyethylene, which we can recover, is a product that sells very well" - emphasises Szymon Wojciechowski, a PhD student working in Prof. Zawadiak`s team.

"Such polyethylene can be used for the production of foil packaging in which transparency is not crucial, for example garbage bags. It is suitable for the production of pots or garden furniture. Recovered aluminium can be used in metallurgy" - adds Wojciechowski.

The invention named "The method of processing waste foils and laminated foils separated in the defibering process from TetraPak-type multi-material packaging for liquid food" - was submitted to the Patent Office in 2017. The authors include: Prof. Jan Zawadiak, Szymon Wojciechowski, Beata Orlińska, Tomasz Piotrowski, Adam Marek, Mateusz Data and Iwona Szmidt. The company Altempo from Wadowice was registered as a co-investor.

PAP - Science in Poland, Mateusz Babak

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