Hecla positions for silver upswing; Lucky Friday remains essential part of portfolio - ME Feature Article

Founded in 1891, Hecla Mining Company is the oldest precious metals company on the New York Stock Exchange and the largest primary silver producer in the United States and Canada. An innovative mining method at its historic Lucky Friday Mine in Idaho coupled with a low-cost, high-margin operation at its Greens Creek Mine in Alaska and production growth opportunity at the Keno Hill Mine in Canada’s Yukon Territory has positioned Hecla well for a period in which silver has retraced from its January all-time high but continues to hold above the previous cycle’s peak pricing. And while some precious metal producers have looked for expansion into other commodities, Hecla has turned its focus to its core identity as North America’s premier primary silver producer. In April, Mining Engineering had the opportunity to visit the Lucky Friday Mine. For more than eight decades, Lucky Friday has operated in one of North America’s most productive and geologically challenging silver districts, Idaho’s famed Silver Valley. As mining advanced deeper into the vein system, the same geological forces that created exceptional mineralization also produced increasing seismic hazards at the mine. This challenged the company to find a new way to manage the growing stresses associated with depth. Hecla found its answer with the deployment of the underhand closed bench (UCB) mining method, which was developed and implemented at Lucky Friday. The UCB method uses large-scale, deephole blasts to proactively trigger seismic events. The blasts destress the zone while fracturing the ore. More than 90 percent of the area’s seismic energy is released within a 12-hour window. “The constraint that resulted in the development of UCB was seismicity related to a corner geometry between two stopes,” Chris Neville, vice president and general manager of the Lucky Friday Mine, told Mining Engineering. “It was a well-understood seismically active area and was being managed by a common technique by withholding miners from the area after a blast. A very similar situation in the Lucky Friday vein in the 1990s had been managed using a destressing technique. The destressing would eliminate the need to withhold miners to keep them safe and return the stope back to double-shift rather than single-shift production. A blast pattern was executed and achieved the desired effect but also led to the question “What would happen if there were just a few more holes in the blast?” Hence, the UCB concept was sparked, which eventually spread to the rest of the seismically problematic mining areas and the main mining front on the Gold Hunter 30 Vein.” The UCB method changed the way things were done at Lucky Friday and the method received a number of industry accolades, including the prestigious Robert E. Murray Innovation Award from the Society for Mining, Metallurgy & Exploration (SME) in 2022. The story of UCB is one of the most recent advancements in a decades-long effort to push deeper into one of the world’s most complex underground mining environments while improving safety, productivity and workforce utilization.