North of 60 Mining News – May 6, 2026 Original Article: The mining newspaper for Alaska and Canada’s North
Is evaluating a pyrite concentrate circuit and tailings processing initiative that would increase metal output and reduce reclamation liabilities.
Greens Creek is already the largest silver-producing mine in North America and a cornerstone asset for Hecla Mining Company. Now, the Idaho-based miner believes substantially more value can be extracted from both the ore and tailings at the Southeast Alaska operation while also reducing long-term environmental management and reclamation costs.
To achieve this, Hecla is evaluating two initiatives that could increase precious and critical metals recoveries while lowering future closure liabilities at the underground mine about 20 miles southwest of Alaska’s capital city of Juneau:
• Greens Creek Tailings Reprocessing Project – a program targeting recovery of billions of dollars worth of silver, gold, and critical minerals contained within decades of dry-stack tailings.
• Greens Creek Pyrite Concentrate Circuit – a proposed mill upgrade designed to capture additional gold and silver currently reporting to pyrite-rich material.
Neither initiative is expected to require major capital expenditures, but both have the potential to further improve the economics of a mine that already generates substantial free cash flow.
During the first quarter, Greens Creek produced 2.18 million ounces of silver at an all-in sustaining cost of negative $8.39/oz, meaning byproduct revenues from gold, zinc, lead, and copper more than covered operating costs. As a result, the mine generated $125.5 million in free cash flow during the quarter.
Enormous tailings opportunity
Seeing substantial value in the historic tailings at Greens Creek, Hecla has partnered with Vancouver, British Columbia-based EnviroGold Global Ltd. to evaluate a new method for recovering metals and sulfides from the material.
Based on current metal prices, Hecla estimates the Greens Creek tailings contain roughly $6.8 billion of metals accumulated over more than 35 years of operations.
The company estimates these tailings host approximately 50 million oz of silver, 567,000 oz of gold, 309 million lb of zinc, 203 million lb of lead, 27 million pounds of copper, and 1.3 million lb of nickel.
In addition to these primary metals, the already mined and milled material also contains 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,” said Mike Satre, Hecla’s director of government affairs.
Beyond the additional silver and gold recoveries, the initiative aligns with a broader industry push to recover critical minerals from previously mined material. Tailings reprocessing and secondary recovery projects are increasingly viewed as ways to strengthen domestic mineral supply chains while reducing the environmental footprint associated with developing entirely new mines.
New tech applied to old tailings
The tailings reprocessing project centers on evaluating EnviroGold’s proprietary NVRO Process, a hybrid leaching technology designed to break sulfide bonds under relatively moderate conditions while avoiding the high temperatures and pressures associated with conventional pressure oxidation systems.
According to EnviroGold, this lower-intensity approach could reduce both energy consumption and the environmental footprint associated with metals extraction.
Initial phase-one and phase-two testing demonstrated strong recovery rates from Greens Creek tailings samples, including recovery of 98.1% of the silver and 99.5% of the gold, along with nearly all oxide materials contained in the samples provided by Hecla.
Separate testing also indicated the process can recover roughly 95% of secondary metals, such as copper, and between 60% and 90% of various tertiary critical minerals.
By removing metals and oxidizing up to 96% of sulfides, the process also has the potential to reduce long-term environmental risks associated with acid-generating material while producing residual aggregate suitable for backfill or construction applications.
Under the concept currently being evaluated, Greens Creek tailings would be shipped to an off-site processing facility where the NVRO system would recover both metals and sulfides, potentially transforming historic waste into a new revenue-generating stream.
Hecla says early testing indicates the project could become a new cash-flow generator at Greens Creek with relatively modest capital requirements.
Hecla Vice President of Operations Brian Erickson, however, cautioned that the initiative remains in the evaluation stage.
“We’ll make a development decision once the test work is done,” he said.
Advancing toward commercial validation
Encouraged by the initial results, Hecla and EnviroGold have advanced the Greens Creek tailings reprocessing initiative into phase-three testing – a milestone both companies say is critical to determining commercial viability.
This next stage of testing began after a larger bulk sample of Greens Creek tailings arrived at EnviroGold’s testing and commercialization facility in Fremantle, Western Australia, on April 21.
“The arrival of Greens Creek tailings in Fremantle enables the commencement of our pilot and demonstration campaigns, marking the next stage of validation for the NVRO Process on one of the most significant opportunities in our pipeline,” said EnviroGold CEO Grant Freeman.
The phase-three validation program will begin with the operation of a micro-pilot NVRO plant capable of processing roughly 50 kilograms of tailings per day.
This will be followed by a larger phase-four commercial demonstration campaign designed to process approximately 300 metric tons annually, or roughly 820 kilograms per day.
Beyond scaling the process itself, the testing campaigns are expected to generate material for quality assessment, market evaluation, and analysis of potential revenue streams from both primary and byproduct metals.
EnviroGold expects the phase-three program to advance the NVRO Process to Technology Readiness Level 8 (TRL 8) by late August – a benchmark indicating the system has been proven at near-commercial scale and is approaching full deployment.
“This program defines a clear pathway to TRL 9 and full commercial deployment, supporting EnviroGold’s strategy to deliver an industrial-scale process and advance projects to revenue-generating operations,” Freeman said.
For Hecla, successful validation of the process could unlock additional value from Greens Creek tailings while reducing long-term closure liabilities at its Southeast Alaska operation.
“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,” Satre said.
EnviroGold Global Ltd.
Extracting pyrite value
As EnviroGold evaluates the potential of extracting value from the $6.8 billion of metals stored in Greens Creek tailings, Hecla is evaluating the feasibility and economic potential of developing a pyrite concentrate circuit at the mill.
Under the concept being evaluated, the new circuit would separate pyrite-rich material into a dedicated concentrate stream capable of capturing additional silver and gold currently lost during processing.
In addition to improving recoveries, the circuit could also reduce the amount of sulfide-bearing material reporting to tailings storage, lowering long-term management concerns.
Like the tailings reprocessing initiative, the pyrite circuit is being viewed as a relatively low-capital opportunity to further optimize one of the most profitable silver mines in North America.
“If successful, this project would generate an additional marketable concentrate stream, boosting overall silver and gold recoveries from the mill, while potentially reducing the mine’s reclamation liability significantly,” said Erickson.
Hecla’s VP of operations said that on the ore side of the mill, adding a pyrite circuit could also expand mineable reserves through the inclusion of new areas with lower-grade silver or high sulfur content.
“The project is currently estimated to be low in capital intensity and could provide cash flow in about two years,” he said.
The pyrite circuit and tailings program at Greens Creek demonstrates the potential to squeeze more value and improve the environmental performance at existing mines – even at a mine that has been a major silver producer for more than 35 years.