Utah’s massive open-pit copper mine wants to expand. Here’s a look inside.

From a viewpoint at about 6,190 feet above sea level, a giant hole in the Oquirrh Mountains stretches two and a half miles wide and ¾ of a mile deep.

Trucks with tires bigger than a sedan look like small bugs as they climb switchbacks to bring copper ore up from the bottom of the open-pit Bingham Canyon Mine.

A hole Rio Tinto Kennecott has been digging for more than a century.

And though there aren’t plans to make the current pit any deeper, Australia-based Rio Tinto is contemplating expanding its width to extend the life of the mine.

The current plan for the mine has it staying open through about 2033, said Nate Foster, the managing director of Rio Tinto Kennecott.

The plan, known as Apex, would push the mine’s walls to the north about 1,000 feet and, along with underground mining, extend mining operations for about a decade. The project is still going through internal approval processes.

The mine life matters for employees, Foster said, of whom around a handful are part of the fifth generation in their family to work there.

But environmental groups have concerns about extending the life of the mine.

Dr. Brian Moench, president of Utah Physicians for a Healthy Environment, said the downsides of expanding the mine are “significant increased health hazards for everyone, but in particular for children and their neurodevelopment.” A number of the heavy metals in the mine are also carcinogens, he said.

There’s a “real problem” defending an extension of the mine’s life while also protecting public health, Moench said.

Jane Putnam, communications manager for Rio Tinto Kennecott, said via email that the mine has a history of “proactive and continuing work with regulators involved in reclamation and remediation,” or actions that help lessen current and long-term environmental impacts.

More than 120 years of digging

The Bingham Canyon Mine opened in 1903 and has produced thousands and thousands of tons of copper and precious metals.

Kennecott produced 193,000 metric tons of refined copper in 2024, including production from the underground mine, Putnam said.

Most of that is still from above-ground mining, Foster said. The ore is coming from the middle and lower areas of the pit, he said, and runs out in 2027. But Rio Tinto is still studying whether the project is feasible, Putnam said, including how much an expansion would cost.

There is still more ore to get at after 2027. Mining is a constant game of leapfrog, Foster said, and there’s work going on now to get to the ore in the upper pit currently covered by waste rock.

Worldwide demand for copper is growing, largely due to its electrical conductivity. As energy moves away from fossil fuels to cleaner sources, electricity becomes the primary method for transferring and using energy. Electric motors and power lines rely on copper. The average electric vehicle requires two and a half times the copper that a comparable gas-powered car uses.

Bingham Canyon Mine also produces smaller amounts of molybdenum – used in alloys like stainless steel and cast iron – as well as gold, silver and other precious metals. ​​And in 2022, the company started separating and selling tellurium, an element used to produce solar panels.

Foster said Kennecott is looking at extracting more metals but needs to figure out how to do that efficiently and while breaking even on cost.

Brian Somers, CEO of the Utah Mining Association, highlighted Bingham Canyon Mine in a recent presentation to legislators and said the area around the mine is “still the biggest and most productive” for minerals in the state.

The mine is among those that can produce minerals Somers highlighted as being banned or limited in export by China, like Tellurium and Molybdenum.

He also said it can produce many other critical minerals “in very short order” after more study and investment from its waste streams or tailings pile.

From rock to copper

Those tailings are one end product of the mining process that starts in the massive pit and underground.

Trucks bring the ore up from the bottom of the pit to the crusher – about a 45-minute drive. At that point, the ore is about 0.4% copper if it’s coming from the pit and about 2% to 3% copper if it’s coming from underground.

The crusher pulverizes the ore, taking it from the size of a basketball or bigger to softball size.

Those smaller pieces of ore then travel five miles on a conveyor belt to the concentrator.

Four feeders can further grind up the ore and pull it into the concentrator, where it’s mixed with air, water and chemical reagents that grab the metal while bubbling to the surface.

That process transforms part of the ore into 25% copper concentrate that goes to the smelter.

The smelter – one of the only ones left in the country – flash melts the ore into liquid copper and produces 99.5% copper that’s then sent as 800-pound plates to the refinery and transformed into cathodes.

Those cathodes are then shipped in box cars, mostly to the Midwest to be made into copper pipes, Foster said.

There are several byproducts of the process, including sulfur from the smelter. Kennecott turns that into sulfuric acid and sells it to a company that makes fertilizer.

Remains from the concentrator are pumped to the tailings pond.

‘Really clean tailings’

Kennecott has one operational tailings impoundment near Interstate 80.

A “slurry” comes through about 12 miles of pipeline to get to the north impoundment, said Paula Doughty, manager of tailings and water services.

Two cyclone stations circulate the material to separate the water and the solids, then split off coarse and fine material. Then, valve stations release the coarse material to the outside, where an earth-moving company compacts it into the embankment.

Water pools and goes into the clarification canal, where there’s further settling, then is recycled back to the concentrator and cyclone stations.

The mine has “really clean tailings,” Doughty said while pointing out double-crested cormorants gathered in the pond to catch fish.

The dirt making up the embankment, she added, is “pretty close in composition to most Western soil.”

Rio Tinto Kennecott also “reclaims” the banks’ outer slope, Doughty said, planting grass and returning the area to a dry savanna that’s home to deer, coyotes and mice.

There’s continuous dust control and suppression using large sprinklers that line the embankment.

‘Ongoing environmental disaster’

Despite the dust suppression efforts, the tailings pond raises concerns from environmental groups.

Everyone along the Wasatch Front is concerned about dust coming off the Great Salt Lake, said Moench with Utah Physicians for a Healthy Environment. But those storms can include dust from the tailings pond that has blown toward the lake, he said.

The mine and smelter are also of concern because of the large quantities of toxic materials produced.

Toxic “releases” from the mine pushed Utah to second in the U.S. Environmental Protection Agency’s Toxic Release Inventory.

That’s because the mine moves “millions of tons” of dirt and rock with naturally occurring trace levels of metals reportable to the federal government each year and must report its waste management as part of the TRI program, spokesperson Putnam said in a statement.

But Moench said it goes beyond that.

“It is certainly not a fair representation of the health hazards for Rio Tinto or anyone else to say it’s just a result of dirt or earth moved as part of the mining process,” the physician said.

The heavy metals aren’t degradable or combustible and sit in the environment “year after year,” he said, and it’ll just keep getting worse.

“It will get in every sort of venue of the environment,” Moench said. “Our water, our air, our soil, our food.”

A study near Butte, Montana, where there’s a toxic lake left in the aftermath of a copper mine, found high levels of newborn exposure to heavy metals, Moench said.

Utahns should insist on a similar study, he said, with a focus on areas close to the mine to determine whether there are similar exposures here. Without that information, he said, people should be aware of the risks of “allowing this kind of an ongoing environmental disaster to continue.”

Even after the mine closes, he said, there are consequences – either the community is left holding the bag for cleanup or “we’ll just let it sit there.”

Remediating the land

Rio Tinto Kennecott, though, is doing things to clean up now.

There’s a “continuous and proactive effort” to reclaim areas where there isn’t active mining, Putnam said, including planting native seeds to “help prevent soil erosion, control dust and gradually return the landscape to a natural habitat.”

Those efforts start long before closure to “ensure the best possible outcome for the land, wildlife, and surrounding communities,” Putnam added in emailed answers.

As operations wind down and Kennecott reclaims or remediates land, some areas may be developable, she said.

Putnam pointed to the 4,200-acre Daybreak development in South Jordan as an example of what could happen. During a driving tour, Foster also pointed out the Copper Club Golf Course, which sits on property leased from the mining company.

Some areas may “remain as open space,” Putnam said.

The biggest exception to possible redevelopment is the pit.

A 30-megawatt solar array under construction now to help power the mine during operations will also keep the pumps going at the bottom of the pit to drain water, Foster said, so the hole is a dry pit instead of a toxic lake like the Berkeley Mine Pit in Butte.

But there’s no practical way to backfill it, he said.

“The hole is gonna remain the hole,” Foster said.

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