Electronic circuits in discarded computers, mobile phones and other devices could be recycled less harmfully using a technique developed by researchers at the Shanghai Jiao Tong University in China. Unlike current methods, the new technique can be used to reclaim valuable metals such as copper without releasing toxic fumes into the atmosphere, such as occurs when circuit boards are introduced into copper smelters.
The new approach involves crushing boards and using a high-voltage electric field to separate metallic and non-metallic materials. The metals can then be reclaimed by distilling in a vacuum while the non-metal components can be compacted into plates for use as building materials.
Printed circuit boards are made from insulating layers of fibre glass and resin, with electronic components and interconnecting circuitry on top. The number of these boards manufactured worldwide is growing by around 9% per annum, with China and Taiwan alone producing more than 200 million square metres of circuitry each year.
The researchers experimented with 400 kilogrammes of waste boards collected from electronic repair depots and household waste. A machine with rotating cutters crushed the boards and a hammer grinder pulverised them into pieces smaller than 1 millimetre in diameter.
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