Turning e-waste into green gold

Mint Innovation has struck gold – quite literally – in the tonnes and tonnes of electronic waste (e-waste) dumped every year. The precious metal is an integral part of circuit boards used in electrical appliances, mobile phones and computers, but reserves are fast running out. Enter Mint Innovation with a novel solution.

The company uses its technology to extract gold and other critical metals to produce low-carbon ‘green metals’ and help move e-waste towards a circular economy.

The e-waste is ground into a coarse, sand-like material then, using chemistry, Mint Innovation is able to dissolve the metals in a solution and separate out the solids. The next step in the process is where things start to get really interesting.

“You’ve basically got 40-plus metals floating around in the solution, and while gold is the most valuable, it’s also the least abundant,” says Mint Innovation CEO Will Barker. “We then use a biological material that goes into the solution and selectively ‘grabs’ the gold.”

Once the gold has been removed, conventional chemistry takes over to recover other metals such as copper, tin and silver.

Not content with just one material being returned to the economy, Mint Innovation teamed up with Callaghan Innovation to evaluate the feasibility of using the residual powders from e-waste in concrete. The innovation agency’s scientists and engineers were able to use their expertise to better understand how e-waste powders could be used to strengthen cement.

“When we have a byproduct we’re looking to add value to, and we don’t have any expertise around it, it’s really helpful to be able to partner up with Callaghan Innovation. It would have been very expensive for us to do internally,” says Barker.

The company has also benefited from a number of Callaghan Innovation grants since it was established in 2016.


In 10 years’ time I think every investment is going to have a climate focus. So you need to think big and your tech needs to be scalable beyond New Zealand.

Will Barker CEO

“In the early days it was the Project Grant, and then as we grew, we moved into the Growth Grant, which enables you to develop that business-as-usual research and development capability, which most companies without grants can’t do.”

Over the course of his career, Barker has developed many skills that are proving useful for addressing big problems, such as environmental degradation.

“As you get involved in the climate tech space, you learn more and all of a sudden you realise if everyone stands back waiting for someone else to fix it, we’re in big trouble.”

To those getting started in the climate tech industry, Barker has one simple piece of advice: “Think big! In 10 years’ time I think every investment is going to have a climate focus. So you need to think big and your tech needs to be scalable beyond New Zealand. This means it’s going to be a hard road, but you need to get in there and roll your sleeves up.”

Mint Innovation is moving into a much higher growth phase as its Sydney plant ramps up production, following a successful $60 million capital raise.

“This raise is not just about building one commercial plant; it’s developing the internal infrastructure and capability so we can build multiple plants around the world in parallel.”

As the world continues to heavily rely on electronics there’s no shortage of e-waste, and for Mint Innovation, this presents trash-to-treasure opportunities in Europe, the United Kingdom and across the United States. 

At a glance

  • Founded in 2016
  • Founded by Will Barker (CEO) and Ollie Crush (CTO)
  • Headquartered in Auckland
  • Extracts ‘green metals’ from waste using natural biomass and smart chemistry
  • $60 million capital raise to help open cityscale plants around the world
  • Visit website

Callaghan Innovation impact

  • Deep tech problem solving – e-waste in cements
  • Project and Growth Grants
  • Received start-up support and funding through the Deep Tech Incubator programme
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