Many electronic items you use daily, including your laptops, chargers, and smartphones, contain a tiny amount of gold. This is because gold is an excellent conductor of electricity and doesn’t rust or corrode over time, making it an ideal material for small, high-performance connections within electronic circuits.
The amount of gold in each device is very small, though, but when added up across millions of used and discarded gadgets, this collective amount makes electronic waste a surprisingly valuable source of gold. However, extracting this gold isn’t easy and usually requires toxic chemicals like mercury and cyanide harm both people and the environment.
But this could soon change. In a world-first breakthrough, researchers at Flinders University in Australia have developed a clean, low-cost method to recover gold from electronic waste as well as from ore without using toxic chemicals. Their method uses a commonly used disinfectant and a reusable material, offering a greener solution to an old problem.
“The aim is to provide effective gold recovery methods that support the many uses of gold, while lessening the impact on the environment and human health,” Justin Chalker, one of the study authors and a professor at Flinders University, said.
The way to non-toxic gold recovery
The traditional way of separating gold from ore or electronic components can leak chemicals like cyanide and mercury into soil and water, affecting wildlife and people living nearby. Mercury is still used in many small gold mines, especially in developing countries, and it’s a major source of toxic pollution worldwide.
The new method, developed by Chalker and his team, starts with a safer chemical, trichloroisocyanuric acid (TCCA). It’s the same substance used in swimming pools to disinfect water. The researchers discovered that when this chemical is mixed with salt water, it can dissolve gold from ore or broken-down circuit boards.
Once the gold is in solution, they use a second tool—a specially designed polymer that’s rich in sulfur. Think of it like a soft sponge that only absorbs gold, even if other metals or materials are present. The gold sticks to the polymer, which can then be separated.
What’s even more amazing is that the polymer is recyclable. After it collects the gold, it can be triggered, chemically, to break apart and release the metal. Then the polymer can be reassembled and used again. Even the process of making this polymer is eco-friendly, relying on UV light to start the chemical reaction that forms it.
The researchers tested this method not just in the lab, but also on piles of real-world electronic waste like computer parts and RAM sticks. They were able to recover high-purity gold from even complex, mixed-up materials. In some cases, they were even able to extract trace amounts of gold from waste left over from scientific experiments.
“We dived into a mound of e-waste and climbed out with a block of gold! I hope this research inspires impactful solutions to pressing global challenges,” Harshal Patel, one of the study authors, and a research associate at Flinders, said.
A golden boon for the environment
Currently, the demand for gold is growing in electronics, medical devices, space tech, and beyond, and safer extraction methods are urgently needed. The newly proposed technique offers a non-toxic, low-cost, and repeatable way to recover gold.
It’s especially promising for small-scale mining operations that currently heavily rely on cyanide and mercury. For instance, according to a report from the US Environmental Protection Agency, mercury pollution from artisanal and small-scale gold mining (ASGM) is the largest source of global mercury emissions, about 38% of total human-caused mercury pollution.
All of this can be prevented with the TCCA-based approach. Moreover, traditional gold mining involves drilling, blasting, crushing, and chemical processing, all of which consume large amounts of energy, often from fossil fuels, contributing heavily to carbon emissions.
According to a report, mining just one kilogram of gold releases more than 20,000 kilograms of CO2 emissions. However, recovering gold from e-waste using the proposed method does not require any of these steps. Therefore, it could greatly reduce both energy use and CO2 pollution from gold mines.
The next challenge is scaling up the method. The Flinders University team already has plans to work with industry and recycling companies to test their method on larger quantities of e-waste and mined material. Plus, they have partnered with researchers in Peru and the US to test the method on real ore from artisanal mines.
Hopefully, these efforts will change the way gold is extracted from mines and e-waste around the world, and save our planet from mercury pollution and cyanide spills.
The study is published in the journal Nature Sustainability.
