The quest to turn e-waste into metals

University of Auckland PhD researcher William Sheard is on a mission to figure out how to extract the wealth of metals in e-waste.

More than 50 million tonnes of electronic and electrical waste are produced globally each year, he says.

An estimated $100 billion of recyclable materials in electronics are dumped annually.

“The more metals we can get out of e-waste, the fewer new mining projects you need.

“If you can mine e-waste instead of the ground, there’s less environmental damage and less risk to human health from mine runoff,” Sheard says.

Electronic waste contains more than 40 metals. Some, like gold, are precious, while others, such as lithium and cobalt, are running out fast. And some, like mercury, are toxic to humans and other species.

As a masters student studying chemistry in 2021, Sheard started investigating the possibility of extracting iron from a “soup” containing finely ground e-waste.

In 2023, the University’s Centre for Climate, Biodiversity and Society granted a PhD scholarship to Sheard to continue his quest to turn waste into gold, mercury, iron, or whatever else he can produce.

Aiming to have a real-world impact, he consulted e-waste recycling organisations to learn the secrets of large-scale operations.

It soon became apparent the batch brewing processes conducted in the university laboratory were not going to work on a bigger scale. A system was needed where dissolved metals would flow through a filter that traps them.

Metals easily bond onto sulphur polymers, so Sheard’s research has focused on using these as a filtering agent.

“Sulphur is a great material, because it’s a petrochemical waste product that gets stock-piled,” he says.

He’s looking into the links holding polysulphide chains together, to see how different mixtures react with different metals.

“The next step is figuring out how to get the metal off again, after it has bonded with the sulphur polymer.

“Ideally, we want to re-use the polysulphide too.”

Growing up in Alberta, Canada, Sheard was aware from an early age about the environmental harm caused by oil production and other industries.

“Most e-waste ends up in landfills and the metals leach into the soil and water, so we end up with environmental damage and contaminated drinking water.

“It would be awesome if we can get the valuable metals out of e-waste and create a lovely circular economy.

“The dream of making something that has an impact in the sustainability field is what keeps me doing chemistry,” says the 29-year-old.