Gold from e-waste opens rich veins for miners and the environment

An interdisciplinary team of experts in green chemistry, engineering and physics at Flinders University in Australia has developed a safer and sustainable approach to extracting and recovering gold from ore and e-waste.

In natural sustainability, as explained in this paper, “Sustainable Gold Extraction from Ore and Sustainable Gold Extraction from E-Waste,” shows that gold extraction technology reduces the level of toxic waste from mining and can recover high-purity gold from recycling valuable components of discarded computer printed circuit boards.

The project team led by Professor Justin Chalker of Matthew Flinders has applied this integrated method for high-yield gold extraction from many sources, even recovering traces of gold found in scientific waste streams.

Advances towards safer and sustainable gold recovery have been demonstrated for e-waste, mixed metal waste, and ore concentrates.

“The study featured many innovations, including new recyclable leaching reagents derived from compounds used to disinfect water,” says Justinchalker, professor of chemistry, who heads the Chalker Lab at Flinders University’s Faculty of Science and Engineering.

“The team also developed an entirely new way to make polymer adsorbents, or materials that bind gold after extraction to water, and started a critical reaction using light.”

Extensive research into method mechanisms, scope and limitations has been reported in a new study, and the team is currently working with mining and e-waste recycling operations to experiment with methods at a larger scale.

“The goal is to provide effective gold recovery methods that support the use of gold while reducing its impact on the environment and human health,” says Professor Chalker.

The new process extracts gold using benign compounds at a low cost. This reagent (trichloroisocyanuric acid) is widely used for water sanitation and disinfection. When activated with salt water, the reagent can dissolve gold.

Gold can then be selectively bound to a new sulfur-rich polymer developed by Flinder Steam. The selectivity of polymers allows gold recovery even in highly complex mixtures.

The gold can then be recovered by triggering the polymer. It “makes” itself and converts it into a monomer. This allows you to collect gold and recycle and reuse the polymer.

Global demand for gold is driven by its high economic and monetary value, but it is also a key component of electronics, medicine, aerospace technology, and other products and industries. However, mining previous metals involves the use of highly toxic substances such as cyanide and mercury for gold extraction, and other negative environmental impacts on water, air and land, such as CO2 emissions and deforestation.

The aim of the Flinders-led project was to provide a safer alternative to mercury and cyanide in gold extraction and recovery.

The team also worked with US and Peruvian experts to verify the method of ore and rely on otherwise toxic mercury to fuse gold.

Gold mining usually uses highly toxic cyanides to extract gold from ore, bringing risk to wildlife and is a wider environment if not properly contained. Artisans and small gold mines still use mercury to fuse gold. Unfortunately, the use of mercury in gold mining is one of the largest sources of mercury pollution on the planet.

Professor Chalker says that interdisciplinary research collaboration with industry and environmental groups will help address highly complex issues supporting the economy and the environment.

“We are particularly grateful to our engineering, mining and charity partners for supporting our large demonstrations of gold recovery technology in translation of our laboratory discoveries.”

The lead authors of the leading new research, Dr. Max Mann, Dr. Thomas Nichols, Dr. Hershal Patel and Dr. Lynn Lisbore, Principal Authors of Flinders University Postdoctoral Research Fellows, have extensively tested new technologies in e-waste mountains with the aim of finding more sustainable circular economy solutions.

Many components of e-waste, such as CPU units and RAM cards, contain valuable metals such as gold and copper.

Dr. Mann said, “This paper shows that interdisciplinary collaboration is needed to address the major global issues managing the growing stockpile of e-waste.”

Dr Nicholls, a fellow Arc Decra, said, “The newly developed gold sorbents are made using a sustainable approach that uses UV light to create sulfur-rich polymers. Recycling the polymer after gold recovery will increase the green credentials for this method.”

“We dived into the e-waste mound and climbed on a gold block! We hope this research will affect the global challenges and pressing challenges,” said Dr. Patel.

“The ever-growing technical and social demand for gold has made it increasingly important to develop safe and versatile methods to cleanse gold from a variety of sources,” concludes Dr. Lisboa.