|Dr. Anita Parbhakar-Fox during lab work on South American tailings.
Source: Anita Parbhakar-Fox
Researchers' success in Tasmania, Australia, in extracting hitherto unknown commodities from tailings where acid mine drainage has occurred has attracted the attention of miners in South America seeking to prevent future dam failings.
Researchers from the University of Queensland and the University of Tasmania have been working with a number of miners, including Grange Resources Ltd., MMG Ltd. and Vedanta Ltd., to see whether tailings can provide the "next generation of deposits," according to Dr. Anita Parbhakar-Fox, who has worked with both universities.
Researchers have been characterizing tailings materials at various deposits to see how mineralogy affects chemical and physical stability, which in turn reduces risk and liabilities and could even increase profits as new commodities have been revealed to exist in the tailings that operators previously did not know were there.
Parbhakar-Fox, currently a senior research fellow at the University of Queensland's Sustainable Minerals Institute, told S&P Global Market Intelligence that the aim is to "re-purpose" the material, and in doing so minimize the amount of tailings waste produced. She also flagged the possibility of a "zero waste mine" being developed in the future.
After tailings dam failures at Mount Polley in 2014, Samarco in 2015 and Feijao in January 2019, the Church of England Pensions Board and the Swedish Council on Ethics urging 683 listed miners to publicly release information on all of their tailings dams was a "game-changing moment" for tailings research, she said.
Parbhakar-Fox said re-evaluating upstream tailings design has been talked about much more particularly since the most recent two disasters, which were on an "epic, global scale," particularly given tailings characterization and re-characterization for re-purposing had not previously gained much traction.
However, her work at Grange's Savage River iron ore project, among others, has attracted the interest of mid-tier miners in South America to send her group tailings samples for them to investigate, not only for metal recovery but also for things that can be developed further downstream like building construction material.
Parbhakar-Fox recently presented findings from that work, which suggested that 2,660 tonnes of cobalt could be extracted from the 2.66 million tonnes of pyrite that could be taken from the 38 million tonnes of tailings at Savage River.
Based on a cobalt metal price of US$38,000/tonne, a 90% recovery rate could generate about US$90 million in extra revenue from the contained metal.
While those are admittedly "very conceptual" given it is only based on sampling from the upper 2 meters of the tailings deposit, Parbhakar-Fox said such work "opens up a whole new avenue of thought" in terms of additional recoveries — "but only if it makes financial sense."
She said the Samarco and Feijao events in particular were a "wake-up call" for miners, as she is now being approached by geologists, mineral processors and business development people from such companies, as opposed to the environmental consultants she used to engage with.
She also has a Masters student looking at indigenous bacteria found in Vedanta's old Mt Lyell copper mine, where previous operators discharged smelter slag and mill tailings into the river system until smelting stopped in 1970, and discharge of tailings to the river ceased in 1994, according to Tasmania's Environmental Protection Authority.
While there are over 200 inactive mine sites in Tasmania that have caused acid mine drainage, Parbhakar-Fox said the bacteria at Mt Lyell, for example, are adapted to that particular ore deposit and can therefore be harnessed to improve metal recovery via bio-leaching.
This revelation has "given birth to a whole new area of research looking at bacteria in mining," she said.
Tasmanian Minerals, Energy and Manufacturing Council strategic adviser Wayne Bould said in an interview the mining industry's involvement in such research was firstly about finding new ways to deal with an existing problem, rather than any potential commercial benefits.
While educating communities early and using science and empirical data helps foster social license to operate, Bould said environmental concerns were no longer so much in the public eye in the state, though acid mine drainage was a legacy of "what was [previously] best practice at the time."