Hecla Investigates Greens Creek Upgrades

Why It Matters

Unlocking value from historic tailings and pyrite streams can add multi‑million‑dollar cash flow while mitigating environmental liabilities, strengthening Hecla’s position as a leading North American silver producer.

Key Takeaways

• Hecla estimates tailings hold $6.8 billion in metals
• NVRO process achieved 98% silver and 99.5% gold recovery in tests
• Tailings reprocessing could cut future reclamation liabilities at Greens Creek
• Pyrite concentrate circuit aims to capture additional gold and silver
• Projects require modest capital and could add cash flow within two years

Pulse Analysis

Hecla Mining’s dual focus on tailings reprocessing and a pyrite‑concentrate circuit reflects a broader shift in the mining industry toward extracting value from existing waste streams. Greens Creek, the largest silver mine in North America, holds an estimated $6.8 billion of metals in its dry‑stack tailings, including 50 million ounces of silver and over half a million ounces of gold. By partnering with EnviroGold and testing the NVRO hybrid leaching process, Hecla is positioning itself to turn this legacy waste into a revenue‑generating asset, aligning with growing investor interest in critical‑mineral supply security and reduced environmental footprints.

The NVRO technology, which operates at lower temperatures and pressures than conventional pressure‑oxidation, demonstrated recovery rates of 98.1% for silver and 99.5% for gold in laboratory trials, while also extracting up to 95% of secondary metals such as copper. These results suggest a significant reduction in acid‑generating sulfides, potentially lowering long‑term reclamation costs. Phase‑three testing in Fremantle, Western Australia, will scale the process to a 50‑kg‑per‑day micro‑pilot, with a subsequent commercial demonstration targeting 300 metric tons annually, moving the technology toward TRL 8 by late summer.

If validated, the tailings project and the proposed pyrite‑concentrate circuit could deliver additional cash flow within two years, reinforcing Hecla’s free‑cash‑flow generation without major capex. The pyrite circuit would capture gold and silver currently lost in pyrite‑rich material, further improving overall recoveries and reducing sulfide waste sent to the tailings facility. Together, these initiatives illustrate how legacy mines can extend their economic life, support domestic critical‑mineral supply chains, and meet tightening environmental standards, offering a template for other producers seeking incremental value from existing assets.