From super fungi to polymers: Rethinking mine tailings

Researchers at the University of Queensland (UQ) are investigating whether engineered fungi could help recover critical minerals from mining waste while also assisting with site remediation.

The project is another demonstration of the innovative ways researchers are searching for new solutions to the challenge of mine tailings, one of the industry’s biggest environmental and operational challenges,

Australia generates an estimated 620 million tonnes of mine waste each year, much of it stored in around 250 active tailings dams. Tailings typically comprise the rock, clay, water and other materials left behind after ore processing, often forming a wet slurry that can account for around 80 per cent of the material extracted from a mine.

With tailings storage carrying ongoing environmental, safety and cost considerations, researchers are developing new approaches to reduce risks while unlocking additional value from mine waste streams.

But instead of seeing mine waste as a problem, researchers and major miners are exploring new ways to turn waste into opportunity.

Fungus power

Environmental engineers at UQ’s Biosustainability Hub are growing fungal strains capable of detoxifying mining tailings and capturing traces of valuable rare earth elements without relying on harsh chemical processes.

Traditional recovery of critical minerals from tailings often involves leaching using acids and solvents. UQ researcher Dr Denys Villa-Gomez has developed an alternative approach that uses fungi to produce organic acids capable of both cleaning mine waste and recovering metals.

“We take fungi that grows naturally in mining and then we engineer them to actually be super, so they can cope with toxic environments and tolerate harsh conditions,” Dr Villa-Gomez said.

“We know the process works well for extracting high-value critical minerals such as vanadium and scandium, key compounds in electronics and microchips.”

The fungal strains are developed through adaptive laboratory evolution, a process that exposes fungi to increasingly challenging conditions over time so the strongest organisms survive and evolve into more effective strains.

“It’s just like how a superhero gets powers because they are exposed to radiation,” Dr Villa-Gomez said.

A concrete solution

While some researchers are focused on recovering minerals from tailings, others are exploring how the material itself can be repurposed.

CSIRO’s Recovering Tailings group, part of the Sustainable Mining Technologies program, is developing geopolymer concrete made from mine waste. The approach aims to transform tailings from a long-term liability into a useful construction material.

CSIRO scientists are converting tailings into geopolymer concrete that can reduce carbon dioxide emissions by up to 90 per cent compared with traditional Portland cement.

Geopolymers replace cement as the binding agent in concrete. Rather than relying on limestone heated to approximately 1400°C, they use aluminosilicates, including clays rich in aluminium and silicon compounds.

“Geopolymers can be substituted for the cement used in most concrete,” CSIRO scientist Clint McNally said.

“By using an aluminosilicate instead of limestone, we can get a significant amount of our clays from mining waste.”

The versatility of geopolymers also allows them to be tailored for different applications, from high-strength road construction products to stable forms for waste disposal.

“It’s a bit like making a cake,” McNally said.

“Change the ratio of eggs, sugar and flour to get the type of cake you want.”

Industry collaboration

Research into tailings management is not confined to universities and government laboratories. Major miners are also investing in new approaches to improve how tailings are handled at scale.

BHP and Rio Tinto have joined forces through the Tailings Management Consortium (TCM), established in 2022 to advance tailings dewatering technologies and improve water recovery from mine waste streams.

The consortium recently released a whitepaper titled Unlocking Large Tonnage Filtered Tailings Stacks: A Geotechnical Perspective, outlining new approaches that could help expand the use of filtered tailings systems at large mining operations.

“Reimagining tailings management will require the industry to explore new ideas, using the new information from emerging research and development,” BHP principal innovation tailings Tony Tran said.

Filtered tailings technology is already used at smaller operations, but the consortium believes further innovation could support wider adoption at large-scale mines, helping reduce water consumption, lower environmental impacts and improve long-term storage outcomes.

The whitepaper identifies opportunities to optimise compaction and stacking techniques, while also examining how upstream processing and material handling could be refined to improve performance.

“Successful innovation requires an agile approach that adjusts to new information,” Rio Tinto principal advisor research and development copper Kaci Jenkins said.

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