New method of recovering raw materials from multi-material packaging

A new method of recovering raw materials from multi-material packaging, in which for instance fruit juices are sold, has been developed by researchers at the Silesian University of Technology in Poland. This method results in a better quality – compared to previous methods – of the recovered plastic.

The already patented technology developed by specialists at the Faculty of Chemistry of the Silesian University of Technology was announced last week by the municipality of the town of Gliwice, Poland. The process allows recovery and reuse of so-called TetraPak cartons. The name comes from the name of a large producer of laminated cartons for beverages.

The cartons consist of paper, a layer of polyethylene, which is a plastic material, and aluminium. Each of these components serves a concrete function: the carton ensures durability, polyethylene protects from moisture, and aluminium makes sure the juice or milk remains edible for a long period of time. The component most frequently reused is paper, as it constitutes 75 per cent of the whole packaging.

“Recovery of the other materials, i.e. aluminium or polyethylene laminate left after paper is separated, is much more complicated. In Poland this is still an unresolved problem,” Prof. Jan Zawadiak from the Faculty of Chemistry of the Silesian University of Technology stated in the townhall’s release.

The team led by Prof. Zawadiak has developed a new method for recovering individual materials from TetraPak packaging. The laminate is ground down and mixed with hot solvent. Aluminium does not react with the solvent and thus it may be isolated in the process of centrifugation. Afterwards, while the solvent evaporates, the polyethylene precipitates in the form of granules.

„Methods involving extraction of individual components through dissolving used to date produce polyethylene in the form of a viscid solution, from which it is hard to separate the solvent. The advantage of our technology is that we gain polyethylene powder with features almost identical to the original, clean raw material”, explains Prof. Zawadiak.

The developed technology was submitted to the Polish Patent Office and an entity which became interested in its implementation is the Factory of Paper and Carton in Wadowice, Poland, which specialises in recycling of this type of packaging.

The researchers have already tested a pilot installation in a paper mill. “Polyethylene, which we are able to extract, is a product that sells like hotcakes.”  – stressed Szymon Wojciechowski, who is a PhD student working in Prof. Zawadiak’s team.

„Polyethylene may be used for manufacturing plastic packaging, where transparency is not required, like in garbage bags. It is good for producing flowerpots or even garden furniture. The recovered aluminium may be used in metallurgy,” adds Wojciechowski.

The invention officially called “Processing of waste plastic wrap and laminated films isolated through fibre separation from TetraPak-like multi-material packaging for liquid food” was submitted as a patent application to the Polish Patent Office in 2017. The names of the inventors include: Prof. Jan Zawadiak, Szymon Wojciechowski, Beata Orlińska, Tomasz Piotrowski, Adam Marek, Mateusz Data and Iwona Szmidt. The Altempo company domiciled in Wadowice was recorded as a joint holder.

Source: PAP – Nauka w Polsce, Mateusz Babak