Recycle any form of different mixed plastics without sorting them and without the result being nothing but a filthy polluting and unusable soup : here is the idea defended by this South Korean team, from the Korea Institute of Machinery and Materials (KIMM). The researchers, in their press release, claim to have developed “ the world’s first technology capable of chemically recycling mixed plastic waste into raw materials, in a highly selective manner, without requiring strict sorting or removal of labels ».
Any solution is good to take (like bacteriological recycling) in view of the health disaster represented by plastic today. A miracle material from the 1950s, it has become, in just a few decades, an unbearable burden for ecosystems and human health. Since the recycling sector is not the most virtuous and ethical there is, it is impossible not to feel a hint of skepticism in the face of this type of announcement. But if we are to believe the data and facts put forward by the team, it is just as impossible not to take a closer look.
A dazzling reaction that transforms plastics in 0.01 seconds
The team was led in its work by Dr Young-Hoon Song, in collaboration with several national institutes (KRICT, KITECH, KIST) and several universities. She focused her attention on one of the worst categories of plastics there is (besides microplastics): mixed plastic waste (hard plastics, films, thermal polymers, organic residues, etc.). Impossible to separate correctly, they saturate sorting centers, which prefer to evacuate them for incineration rather than jeopardize the quality of the recyclable batches that can actually be used.
Using a plasma torch (a gas heated to extreme temperatures), this process breaks the molecular bonds in plastics at a phenomenal speed. Powered entirely by hydrogen, it burns plastics at a temperature of between 1,000 and 2,000°C, and breaks down plastics in less than 0.01 seconds.
Installed in a closed reaction chamber (a tube in which hydrogen is ionized by an electric arc), it propels a jet of incandescent gas which directly strikes the waste. Brought to this temperature, plastics do not even have time to melt, because their molecular chains burst instantly under the effect of the plasmaas if the matter were “ dissolved » before reaching its melting point.
The advantage of this technique compared to pyrolysis (combustion without oxygen carried out at 450 – 600 °C) is that the reaction with the plasma is so brief that it blocks the formation of solid carbon. The polymers do not transform into carbon residues and are converted into simple molecules such as ethylene and benzene, with a selectivity that exceeds 70%. This means that, out of 100 kilos of mixed plastics, more than 70 kilos immediately become useful molecules to remanufacture new plastic.
This concentration on a small number of products then makes the purification particularly efficient, to the point that the final material reaches more than 99% purity. In the recycling of mixed plastics, it’s very simple: this is a rate that has never been reached.
Even residual waxes, usually impossible to recover in pyrolysis, are here converted with more than 80% selectivity. Thick, sticky masses (the nightmare of plastic recycling by-products), which become, thanks to this plasma technique, a resource that can be exploited again.
Is it economically viable?
Today, chemical recycling is almost non-existent and rrepresents less than 1% of the sector because it is too expensive : sorting plastics, sometimes heating them for a very long time, to end up managing dozens of by-products. An economically untenable chain for most players in the sector, who prefer to stay with more conventional and polluting techniques.
The KIMM process precisely circumvents these weak points: no prior sorting is necessary and the molecules resulting from the reaction are very easy to sell. Ethylene, in particular, is one of the cornerstones of the plastics industry; if it can be produced at a cost comparable to that of petrochemicals, plasma recycling should interest more than one industrialist. Precisely, the researchers claim to have successfully validated their first pilot tests economically, to the point of obtaining an ethylene whose cost already aligns with market standards.
This KIMM team therefore everything to succeed and prove that their technique is viable economically and that it could perfectly satisfy both plastic and recycling manufacturers. It will nevertheless be necessary to demonstrate that it is just as effective on a larger scalewhich is why the researchers plan to install a first demonstration line in 2026. If the performances announced in the press release are maintained (and if the energy to power the torches is renewable), their process could become the biggest competitor to incineration and pyrolysis. Which hasn’t happened since… the 1990sa time when the first depolymerization processes saw the light of day, before being rejected en masse by the industry because the yields were far too low. Sincerely hope that the KIMM plasma torch hold the second round !
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