Microwaves used to recycle plastic/aluminium laminate cartons

A new and innovative process by which plastic and aluminium laminate cartons, such as those used for fruit juice, are broken down using microwaves, separating the aluminium and plastic so that they can be recovered, has been honoured at an awards ceremony at the London Science Museum.

The process, which won the Institute of Chemical Engineers’ (IChemE) BOC Environment Award, was developed by scientists at Cambridge University, and uses a technique known as microwave-induced pyrolysis. A bed of particulate carbon is first irradiated until it reaches 500-600°C. The plastic laminate waste is added to the bed, where it is heated by conduction and undergoes pyrolysis, with the polymers cracking to form linear hydrocarbons that can be recycled, and leaving clean aluminium foil, which can also be recovered.

The process, which produces no toxic emissions, and uses microwave heating as an efficient way of converting electricity to heat, is currently being moved to pilot plant scale.

“Chemical engineers are playing a major role in tackling the world’s waste problems,” said Andrew Furlong of IChemE, the organisation that runs the Environment Awards. “Our annual awards programme sets out to recognise their contribution – not only to waste management, but to safety and all-round engineering excellence.”

Other innovations that were commended by the awards ceremony includes a method of destroying highly-toxic organic compounds with an efficiency greater than 99.99%, which was awarded second place. The Silver II electrochemical process, developed by Accentus, is a low-temperature process that, its developers say, is very attractive for chemical weapons disposal.

Third place was shared by a silicone manufacturing site in South Wales which has focused on reducing its environmental impact through processes such as recycling of spent sulphuric acid and a 70% reduction in VOC emissions; and a form of membrane extraction technology, which recovers aromatic acids and bases from effluent.

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