by LEADVILLE, Colo. — Rust-colored piles of mine tailings and sun-bleached wooden derricks tower over the historic mountain town of Leadville, Colorado, a legacy of gold and silver mining that pollutes the Arkansas River basin more than a century after the town’s heyday.
Meet a startup called CJK Milling that wants to “remine” some of the waste piles to squeeze more gold from ore that was discarded decades ago when it was less valuable. The waste would be trucked to a nearby mill, ground into powder, and bathed in cyanide to extract traces of precious metals.
The proposal comes amid growing global interest in reprocessing waste containing discarded minerals that have become more valuable over time and are now easier to dispose of. These include precious metals and minerals used for renewable energy that many countries, including the US, are trying to secure.
Supporters say the Leadville proposal would speed up a decades-long cleanup effort that shows no sign of slowing down. They speak in ambitious tones of a “circular economy” for mining, in which leftovers are reused.
Still, some residents and officials’ efforts to revive the city’s failing mining sector and clean up tailings piles are reminiscent of a polluted past, when the Arkansas River was detrimental to fishing and sometimes ran red with tailings from Leadville’s mines.
“We’re in a river where 20 years ago the fish couldn’t survive,” said Brice Karsh, owner of a fish farm downstream from the proposed mill, as he tossed fish pellets into a pool teeming with rainbow trout. “Why go back? Why take the risk?”
Leadville — home to about 2,600 people and the National Mining Museum — bills itself as America’s highest city at 10,119 feet (3,0084 meters) above sea level. That distinction has helped the city carve out a new identity as a mecca for extreme athletes. Endurance race courses crisscross nearby hills where millions of tons of discarded mining waste leached lead, arsenic, zinc and other toxic metals into waterways.
The driving force behind CJK Milling is Nick Michael, a 38-year-old mining veteran who describes the project as a way to give back to society. Michael stands on a pile of mine tailings with Colorado’s highest peak, Mount Elbert, in the distance. He says the waste has a higher concentration of gold than many large mines now operating in the U.S.
“It used to not be the case,” he said, “but the tables have turned and that’s what makes this economical… We just clear out these little piles and move on to the next one.”
City Councilman Christian Luna-Leal grew up in Leadville, in a mobile home park with poor water quality, after his parents emigrated from Mexico.
Disadvantaged communities have always borne the brunt of the industry’s problems, he said, dating back to Leadville’s early days when mine owners mistreated Irish immigrants who did much of the work. Nearly 1,300 immigrants, most of them Irish, are buried in pauper graves in a local cemetery.
Luna-Leal said that stirring up old mine tailings could undo decades of cleanup efforts, recontaminating the water and endangering the well-being of residents, many of whom live in mobile homes on the outskirts of town.
“There is a genuine fear … among a large part of our community that this is not being addressed appropriately and that our concerns are not being taken as seriously as they should be,” Luna-Leal said.
The company’s process doesn’t remove the mine tailings. For every ton of ore that’s milled, there’s a ton of waste left over — minus a few ounces of gold. At 400 tons a day, the waste will quickly pile up.
CJK originally planned to use a giant open pit to store the material in a wet slurry. After that was rejected, the company will instead dry the waste to a putty-like consistency and pile it on a hill behind the mill, Michael said. The open pit below would act as a fallback if the pile collapsed.
The size of the world’s mine tailings is staggering, with tens of thousands of waste piles containing 245 billion tons (223 billion metric tons), researchers say. And waste production is increasing as companies build larger mines with lower ore grades, resulting in a higher ratio of waste to product, according to the nonprofit World Mine Tailings Failures.
This month, gold prices hit record highs and demand for key minerals such as lithium, which is used in batteries, has surged.
Economic conditions mean remining has “taken off like wildfire,” says geochemist Ann Maest, who advises environmental groups such as EarthWorks. The advocacy group is a critic of the mining sector but has cautiously embraced remining as a possible way to accelerate cleanups through private investment.
CJK Milling could do that in Leadville, Maest said, but only if it’s done right. “The problem is they want to use cyanide, and when a community hears that there’s cyanide or mercury in it, they’re understandably concerned,” she said.
Greg Teter, manager of the Parkville Water District, who oversees Leadville’s water supply, sees CJK Milling as a possible solution to the water quality problems.
Many of the waste piles sit above the district’s water supply, and Teter recalls a blowout at the Resurrection Mine, which forced residents to boil their water because the district’s sewage treatment plant couldn’t handle the dirt and debris.
A more constant factor is the polluted runoff in spring and summer, when melting snow from the Mosquito Mountains flows through mine dumps and drainage channels from abandoned mines.
An average of 694 gallons of contaminated mine water flows out of the Leadville Superfund site every minute, according to federal data. Most of it is stored or diverted to treatment facilities, including one run by the U.S. Bureau of Reclamation.
Up to 10 percent of water goes untreated — tens of millions of gallons a year contain an estimated six tons of toxic metals, according to data from the U.S. Environmental Protection Agency. For comparison, during the 2015 Gold King Mine disaster in Colorado, which polluted rivers in three states, an EPA cleanup crew inadvertently caused the release of 3 million gallons (11.4 million liters) of mustard-colored mining waste.
As long as Leadville’s waste piles remain, their potential for pollution will remain.
“There are literally thousands of mining claims that overlap,” Teter said. “We don’t want that getting into our water supply. As it stands now, all the mine dumps … are in my watershed, upstream of my watershed, and if they remove them and take them to the mill, that’s going to be in my watershed.”
The EPA has no authority over CJK’s proposed work, but a spokesman said it had “the potential to improve conditions at the site” by supplementing the cleanup work already being done. Moving the mine waste would eliminate sources of runoff and could reduce the amount of contaminated water that needs to be treated, EPA spokesman Richard Mylott said.
Other examples of remining in the Rockies are in East Helena and Anaconda, Montana, and in Midvale, Utah, Mylott said. Projects are proposed in Gilt Edge, South Dakota, and Creede, Colorado, he said.
Despite the ruins of Leadville’s historic mining, Teter spoke proudly of his ties to the industry, including working in two now-closed mines. His son-in-law works in a nearby mine.
“If it wasn’t for mining, Leadville wouldn’t be here. I wouldn’t be here,” the water manager said.
“There are no active mines in our basin, but I have confidence in what CJK has planned,” he said. “And I can keep an eye on everything they do.”
