Metal Tech News | March 2, 2026
EnviroGold tests NVRO as a sustainable process to recover critical metals from tailings at U.S.’s largest silver mine.
– (Hecla Mining Company)
While most companies view mine tailings as a liability that must be managed through the operations and closure, EnviroGold Global Ltd. sees an economic and environmental opportunity, and is well on its way to demonstrating that opportunity at Hecla Mining Company’s Greens Creek mine – the largest silver producer in the United States.
Located within the Admiralty Island National Monument about 20 miles southwest of Alaska’s capital city of Juneau, Greens Creek has steadily produced more than 8 million ounces of silver annually – along with gold, zinc, and lead – for more than 35 years.
As part of its implementation of the highest environmental safeguards, Hecla dry stacks its tailings – a sustainable but more costly storage method that involves squeezing the water out of the mine waste and then compacting the material for stable storage.
Hecla estimates that the tailings at Greens Creek host $6.8 billion worth of silver (50 million oz), gold (567,000 oz), zinc (309 million lb), lead (203 million lb), copper (27 million lb), and nickel (1.3 million lb). In addition, this already mined and ground resource hosts arsenic, barium, bismuth, cadmium, chromium, gallium, germanium, manganese, and vanadium.
“There is no question that the tailings at Greens Creek contain a significant amount of in-situ metal, and we are actively evaluating opportunities to reprocess our tailings and maximize the extraction of silver and other critical minerals from the material,” Mike Satre, Hecla’s director of government affairs, told Metal Tech News. “In the meantime, we will continue to manage the dry stack tailings facility as permitted and plan for full reclamation and closure of the facility at the end of mine life.”
This includes evaluating the potential of shipping the tailings to an off-site location where EnviroGold’s proprietary NVRO Process would be used to extract both the metals and acid-generating sulfides – creating a new revenue stream and transforming the tailings into a benign aggregate product suitable for backfill.
“We are grateful to Hecla for the opportunity to assess their tailings and the potential commercial opportunity,” said EnviroGold CEO Grant Freeman.
EnviroGold Global Ltd.
Metals without mining strategy
EnviroGold’s NVRO Process uses a hybrid leaching system designed to break sulfide bonds under relatively moderate conditions, avoiding the high temperatures and pressures associated with traditional pressure oxidation – factors critical to minimizing the environmental and carbon footprint. According to the company, the process has demonstrated recoveries of:
• Up to 99% of the contained gold and silver.
• Approximately 95% of secondary metals, such as copper.
• 60-90% of tertiary metals.
• Up to 96% oxidation of sulfides.
Recovered metals and oxidized sulfides are concentrated for potential shipment to a smelter, while the treated tailings are upgraded into a material suitable for backfill or aggregate use.
EnviroGold sees its NVRO process as a means of sustainably producing gold, silver, copper, and other energy and high-tech metals from already mined and crushed tailings found at mining operations around the world.
The company refers to this strategy as “metals without mining,” a technology-led pathway to enhancing the metals production and environmental profile of mining operations.
“EnviroGold’s ‘metals-without-mining’ model offers a scalable solution to one of the industry’s most persistent challenges,” said Executive Chairman David Cam. “With strong economics for clients and a clear path to recurring revenue, we are now entering a transformative, sustainable growth phase.”
Unlocking Greens Creek potential
EnviroGold’s sustainable growth phase includes working with Hecla to investigate the potential of recovering precious and critical metals locked up in the tailings at Greens Creek.
While the metals recovery tech company has been working with Hecla for a while, it agreed to keep the working relationship confidential. Now, following the success of the first two phases of Greens Creek tailings testing, EnviroGold can more openly talk about the work.
On March 2, the company reports that NVRO recovered up to 98.07% of the silver and 99.46% of the gold from Greens Creek tailings during the first two phases of testing. Equally significant, the process demonstrated near-complete oxidation of sulfide minerals, an important factor in mitigating long-term acid-generation risks.
“The test work results clearly demonstrate the NVRO Process has the potential to unlock significant metal production from mineralization contained in Greens Creek’s tailings facility, material that was not recovered in prior milling activities over the facility’s 35-year operational history,” said Freeman.
To follow up on the early success, EnviroGold is shipping a bulk sample of Greens Creek tailings to its development facility in Western Australia for phase-three pilot plant optimization and phase-four demonstration-scale processing.
These next phases will focus on optimizing the process, validating the quality and value of the metal concentrates produced, and evaluating the waste stream characteristics at scale. These are critical steps in determining whether tailings reprocessing can be economically integrated into Greens Creek’s operation.
“If offsite reprocessing of our tailings is ultimately found to be feasible, this could add significant value to Greens Creek through additional metal production and reducing our environmental obligations,” Satre said.
It would also help demonstrate the potential of EnviroGold’s NVRO Process to deliver similar win-win tailings management and monetization opportunities to other mining operations across North America and around the world.
Author: Shane Lasley, Metal Tech News
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