How a gold-stibnite restoration in Idaho could add antimony to the U.S. supply chain
The results of an independent feasibility study published last year envision the project to become one of the largest and richest surface gold mines in the United States with more than 4 million ounces of gold. gold in reserve – and the country’s only primary producer of antimony, a critical and strategic mineral.
There is currently no national source of antimony and 90% of the world’s supply is controlled by China, Russia and Tajikistan, an increasingly untenable narrative when it comes to sourcing minerals. essential to the North American supply chain.
“[Antimony] deserves a lot more credit than he gets – at the end of the day, he’s the unsung hero, ”Mckinsey Lyon, vice president of external affairs, Perpetua Resources, told MINING.COM.
“Right now it is essential in energy technology, whether it is the glass clarifying component in solar panels or the metal strengthening component in bearings in wind turbines and water turbines – it is also used in large capacity storage batteries. “
“It’s a missing piece in a renewable network. You have to be able to store that energy, and the technology that focuses on antimony as the nucleus is a liquid metal battery, ”she said.
Perpetua Resources has signed an agreement with US Antimony to explore the potential for processing antimony from stibnite at US Antimony facilities.
US Antimony, which received a grant of $ 510,500 from the US Department of Defense, has the only primary antimony processing facilities in North America and the Stibnite Gold project is poised to be the only US source of d antimony mined, because stibnite is the main mineral of antimony. .
According to Perpetua’s MSDS, the project has a total measured and indicated resource of 104.5 million metric tonnes with 1.42 g / t of antimony and 1.63 g / t of gold. This resource is based on a gold price of $ 1,250 / troy ounce. The expected average annual gold production is 466,000 ounces during the first four years of operation.
Hallgarten & Company has published a white paper which positions antimony as the “new metal in mass storage”.
“Most of the buzz in the mainstream media is about battery options that extend the life of cell phones or laptops and other PDAs or when it comes to hybrid or electric vehicles. However, the real economic leap forward is in mass storage devices that integrate with power grids to provide off-peak electricity storage, ”the report says.
Antimony extracted from Perpetua’s Stibnite Gold project would be the only national supply – 35% of national requirements for six years of production.
A rich mining history
The Stibnite mining district in Idaho has been mined since 1899, first for silver and gold as part of the Thunder Mountain Gold Rush.
Almost overnight, what was a tiny operation turned into a city of 1,000 people. A whole community has grown up around war production. In the 1940s and 1950s, a blockade in the Pacific cut off the United States’ supply of tungsten and antimony, all of which came from Asia.
During this time, it was essential for ammunition and as a primer in painting battleships and airplanes. Antimony is one of the reasons the United States government and entities during World War II and the Korean War aligned with the current location of the Perpetua project.
“With the blockade of the Pacific, on the eve of WWII, we had no more source of tungsten and antimony – so the US government set out to find it, and they found it in Stibnite. , Idaho, ”Lyon said.
“The US government then commissioned the smaller mining operations there – specifically the Bradley Mining Company to produce tungsten and antimony for the war effort. “
Mining continued throughout the end of the Korean War, in a way before the onset of stricter environmental regulations.
In the 1990s, after mining for gold and stibnite, the site was left in a mess.
A sustainable ESG plan
Perpetua has submitted a restoration and operations plan to the US Forest Service for review, including restoration of legacy impacts – from the first year of construction. The 2020 SF confirmed the economic benefits for communities in Idaho, providing $ 1.3 billion in initial investment and creating 550 direct jobs.
In August 2020, the US Forest Service released a draft Environmental Impact Statement (EIA).
Of the 10,000 comments received, 85% were in favor of the project. Lyon said Perpetua has reviewed and submitted improvements, and the Forest Service’s EIA is expected later this year.
“We understand the importance of this project to Idaho, and that the Idahoans are in charge and leading the way,” said Lyon.
Significant environmental restoration is required where the eastern fork of the south fork of a salmon river flows into an abandoned on-site mining pit, where chinook salmon and bull trout move up the river, this which means miles of critical habitat.
With fish out of their natural habitat in a degraded area and 10.5 million tonnes of mine tailings affecting water quality, the Perpetua team has their work cut out for them.
“When we got to Stibnite it was very clear from day one that if we were to have modern mining for gold and antimony, we needed to bring in the necessary environmental solutions,” Lyon said. .
“Our project was conceived, in the first years of construction, [that] we enter and repair this source of sedimentation which degrades habitat and water quality, we recover the legacy tailings, reprocess and store them safely, and remove them from interaction with ground and surface water .
Perpetua’s plan is to improve water quality and build a fish passage tunnel.
“We’re going to re-mine the yellow pine pit – it’s the biggest source of gold, and redirect the river to a redesigned fish passage based on scientific knowledge of the fish migration route… to make sure that the adults can get up the river, and the juveniles can go down, ”said Lyon.
“There is a full responsibility to bring these migratory fish species back to critical habitat that they currently cannot access, and to do so as soon as mining begins. We don’t wait until the end to bring them to their critical habitat.
Restoring the Stibnite River will add an additional seven to 11 miles to the migration route for fish from the habitat they are stranded for, Lyon said.
“We can bring the resources, the technology and the expertise to solve a problem that has been around for a very long time. “
The draft EIS indicated a 23% increase in stream functional units and a 40% increase in wetland functional units.
“It tells a great story of what modern mining can do on a brownfield site if we bring this technology to lift that river,” Lyon said.
“In Idaho, the story of the back swimming salmon is heroic. “