Recycling Laminate Wrapping

New technique broadens the ability to recapture aluminium in packaging.
24 July, 2017
Businesses and environmentally conscious consumers have a common frustration when it comes to packaging that they want to recycle but can't.
While products packaged in aluminium, glass or paper have a straightforward pathway to the reuse of their materials, other items – particularly those wrapped in plastic aluminium laminate – aren't as easy to reclaim. The Enval company in the United Kingdom has developed a new process for separating the materials that now makes it possible to recycle them too.

Plastic aluminium laminates (PAL) are used in familiar products like toothpaste tubes, or shiny pouches filled with tuna, nuts or juice. The popularity of PAL continues to increase, with more than 176,000 tons introduced in the UK each year, because it is lightweight and flexible at the same time that it protects the contents from light, moisture and other damaging influences. The lighter weights mean that companies are reducing their packaging, transport costs and emissions, and it takes 50 percent less energy to make the packaging to begin with. But the inability to recycle the materials has meant that nearly 18,000 tons of aluminium in the UK alone has been headed to the landfill with no other options.
Enval, however, advanced a process first developed in academic research at the University of Cambridge about 15 years ago and brought it to market. It's based on pyrolysis, a process for breaking down organic materials without using any oxygen. It's done by using microwaves – and believe it or not, instead of exotic lab equipment, the researchers started out with a basic 1.2 kW kitchen microwave oven. They put some shredded packaging inside with particulate carbon, replaced the oxygen in the unit with nitrogen, and blasted away at high heat. It took two minutes for the PAL to separate its materials, leaving the research team with a small pile of clean aluminium flakes. It's how the Enval plant still works.

With an entire facility in Cambridgeshire, though, the microwave ovens are much bigger – and hotter. They run at 150 kW in a 100 square meter space, where it reaches 1,000 degrees Celsius and takes three minutes to produce the aluminium. The company says it can process about 350 kilograms per hour.
Images: Enval
Recycling aluminium through the Enval process leads to energy savings of up to 75 percent when compared with other methods, and yields a purity exceeding 98 percent with a minimum metal yield of 80 percent, meaning the aluminium can go directly back to the smelter. What happens to the plastic? It separates into gas and oil. The gas can be used to generate electricity to power the process itself – renewable sources also are an option for power – and the condensed oil is sold for fuel or feedstock.

There are plenty of industry benefits. It's cheaper, for example, to send the industrial scrap to Enval than to the landfill, so the company is working even with PAL manufacturers to recycle their products too.
Image: Enval
Yet the biggest social-impact benefits are for consumers. Companies choose PAL for their products because it's already environmentally friendly, in part because PAL introduces 60 percent less plastic into the environment than traditional packaging. Enval's own appeal to the British public is to pressure their elected officials to begin collecting PAL for recycling at the council level. The company completed three successful trials, but says it needs advocates for the PAL products to be picked up by waste handlers.
Banner image: Enval