An interdisciplinary team at Flinders University has developed a major, environmentally-friendly method for extracting and recovering gold from ore and electronic waste, offering a promising alternative to the hazardous chemicals traditionally used in gold mining and recycling.
Published in Nature Sustainability, the new technique significantly reduces toxic waste and demonstrates the ability to recover high-purity gold from a variety of sources, including printed circuit boards from discarded computers and even trace amounts found in scientific waste streams.
Led by Professor of Chemistry Justin Chalker, the team’s approach features several key innovations.
“The study featured many innovations, including a new and recyclable leaching reagent derived from a compound used to disinfect water,” said Professor Chalker.
“The team also developed an entirely new way to make the polymer sorbent, or the material that binds the gold after extraction into water, using light to initiate the key reaction.”
The process uses trichloroisocyanuric acid, a compound widely employed in water sanitation, as a benign and cost-effective reagent.
Activated by salt water, this compound dissolves gold without the toxic byproducts associated with cyanide or mercury.
The dissolved gold is then selectively captured by a novel sulfur-rich polymer developed by the Flinders team.
This polymer not only binds gold with high selectivity — even in complex waste mixtures — but can also be triggered to break down, allowing both the gold and the polymer to be efficiently recovered and recycled.
The research addresses the urgent need for safer alternatives to the mercury and cyanide methods that dominate gold extraction worldwide, particularly in artisanal and small-scale mining, which remains a major source of global mercury pollution.
“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,” Professor Chalker emphasised.
The technique’s versatility was demonstrated across electronic waste, mixed-metal scraps, and ore concentrates.
The team now plans to collaborate with mining and e-waste recycling industries to trial the method at larger scales.
Lead authors Dr Max Mann, Dr Thomas Nicholls, Dr Harshal Patel, and Dr Lynn Lisboa extensively tested the method on electronic waste, aiming to advance circular economy solutions.
Dr Mann highlighted the collaborative nature of the project, stating: “This paper shows that interdisciplinary collaborations are needed to address the world’s big problems managing the growing stockpiles of e-waste.”
Dr Nicholls added: “The newly developed gold sorbent is made using a sustainable approach in which UV light is used to make the sulphur-rich polymer.
“Then, recycling the polymer after the gold has been recovered further increases the green credentials of this method.”
Dr Patel remarked: “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.”
Dr Lisboa concluded: “With the ever-growing technological and societal demand for gold, it is increasingly important to develop safe and versatile methods to purify gold from varying sources.”
Professor Chalker underscored the importance of industry partnerships: “We are especially grateful to our engineering, mining, and philanthropic partners for supporting translation of laboratory discoveries to larger-scale demonstrations of the gold recovery techniques.”
This innovation marks a significant step toward cleaner mining and recycling practices, with the potential to transform gold recovery processes globally.
