Mining tailings are the waste byproduct of mining, consisting of ground rock, water, and processing chemicals that remain after extracting valuable minerals. They have been disposed of for thousands of years, but the industrial mining in the late 19th and 20th centuries is responsible for most of what occupies large, engineered dams. Estimates are that there are over 8,000 active and inactive tailings facilities storing nearly 220 billion cubic meters of material. They pose many environmental dangers, some catastrophic in nature.
But tailings can also be quite valuable. A process developed by researchers at West Virginia University and Virginia Tech is being used to clean up acidic leakage from tailings. The method captures rare earths liberated by the sulfuric acid in the tailings. It not only cleans the streams that would otherwise be polluted by the acid mine drainage but also generates revenue to pay for the cleanup.
Three pilot facilities in West Virginia are each currently producing four to five tons of rare earth oxides a year. A larger facility is under construction in Butte, Montana that hopes to produce 40 tons of rare earths a year from its shuttered copper mine’s toxic wastewater.
Re-mining operations like these could obviate the need for new mines. Rare earths are increasingly a critical need for electric vehicles, wind turbines, and other technologies propelling the global transition from fossil fuels.
However, re-mining is not an environmental panacea. Its potential environmental impacts could be as harmful as ordinary mining. There is much we need to learn.
