A new way to recycle old IT cables
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How could microwaves be used to tackle our e-waste problem?
Spotted: In 2022, approximately 62 million tonnes of electronic waste were generated worldwide. Although this waste contains valuable materials such as metals, semiconductors, and rare elements, only around 22 per cent was properly recycled. As demand for electronics continues to increase, we need to become more efficient at recovering value from our old devices. A team of researchers believe they may have a solution.
Researchers from Sophia University in Japan and Università di Pavia in Italy have developed an efficient and less labour-intensive method to recover copper wires from PVC cables using microwave-induced pyrolysis. Exposing the wire to microwaves carbonises the plastic-based insulation without damaging the copper inside, enabling it to be easily retrieved for reuse.
Vinyl-sheathed vinyl-insulated flat (VVF) cables are widely used for low-voltage wiring, including in building sockets and lighting systems. At the moment, these wires are rarely recycled.
During tests, the team placed two-core VVF power cables (which contain PVC-covered copper wires) into a glass reactor. These cables, which were cut into different lengths, were then exposed to microwave radiation of various wattages. Nitrogen gas was introduced to prevent combustion during the process.
The PVC insulation around the cables underwent rapid dichlorination and carbonisation, which prevented harmful by-products – such as polycyclic aromatic hydrocarbons (PAHs), dioxins, and tar – from forming. Interestingly, the scientists also found that the method was most effective on the longer cables, because they most closely matched or exceeded the microwave’s wavelength.
In just 12 minutes, under 300 watts of radiation, the 54-centimetre VVF was completely pyrolysed. And unlike many other existing processes, the new method doesn’t require or generate toxic materials, meaning it could be a safer and more efficient way to boost the electronics circular economy.
Written By: Jessica Wallis