Tailings, mineral waste products produced by mining operations, are a well-known pollutant requiring remediation. Tailings may be dumped in or near water or transported by wind or water to contaminate the surrounding area. Mine sites typically manage tailings by constructing ponds secured by dams.
However, some mining companies are figuring out ways to turn tailings to profits with novel reprocessing technologies to extract valuable metals from the waste. Very small diamonds can be recovered from the residue of the original diamond-bearing ore, and the U.S. Geological Survey found that discarded mine tailings may yield significant amounts of rare earth elements. Several efforts are underway to extract gold and copper from tailings.
Reprocessing mine tailings may also have environmental benefits. A recent project described in Mining.com is a series of experiments carried out by an international group of scientists to produce approximately 30 years of passive carbonation of mine tailings within four weeks. In a paper published in the journal Economic Geology, the researchers explain that this accelerated carbonation of mining waste significantly increases carbon capture for environmental benefit and has the potential to recover valuable battery metals. Establishing a reliable, diversified supply of lithium is a top priority for battery suppliers and vehicle manufacturers.
“If you can integrate carbon capture with the recovery of previously inaccessible minerals, say of nickel and cobalt, you could make some lower grade mines more viable,” said in a media statement Jessica Hamilton, lead author of the study and a researcher at the Australian Nuclear Science and Technology Organisation and Monash University. “According to a recent report in Science, today some 419 million tonnes of ultramafic and mafic (rich in magnesium and calcium) waste are produced annually with the potential, if fully carbonated, to lock up 175 million tonnes of atmospheric CO2 per year.”
The researchers are working on two different approaches. “The choice of approach depends on the resources available at the mine and the local mineralogy,” the lead researcher said. “If there is waste acid available and you don’t have much active brucite, then heap leaching is a great option. If there is a CO2 source, and you have brucite, then you might go for a direct reaction with that gas. But the two can also be used together, for example, heap leaching can be followed by reaction of the magnesium-rich fluids with a CO2 source.”
According to the scientists involved in this project, the approach is suitable for waste from platinum, chromite, diamond, some nickel, copper, and historical chrysotile mines.
For more information about tailings reprocessing, read:
- From Tailings to Treasure? A New Mother Lode
- Mining and the Environment: What Happens When A Mine Closes?
- Determining the Rheological Properties of Mine Tailings
- Correlating Yield Stress with Pumpability of Mining Tailings
- VIDEO: Integrated Tailings Solutions in Mineral Beneficiation Plants
For more information about lithium mining and Li-ion battery production, read:
- Nickel Mining Growing Due to Lithium Ion Batteries
- Li-ion Battery Supply: Can Lithium and Cobalt Meet the Challenge?
- Lithium: From Mineral to Battery
- Lithium Producing Countries Becoming Lithium Battery Producers?
- Lithium Still a Valued Source, Encouraging Old Mines to Re-Open
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