Coeur Mining expects commercial production from the world’s largest open pit/heap leach expansion
project in early 2024. Construction began in August 2020. (Photo: Coeur Mining)

Metal production from the new Stage VI leach pad and Merill-Crowe process plant leach began mid-month with initial doré poured on September 18. Approximately one-third of the 8 million tons of ore on the new pad are currently under leach. The Merrill-Crowe plant is achieving a flow rate of roughly 3,500 gallons per minute (gpm) of solution. Full rampup to commercial production of around 13,000 gpm is expected to be achieved in early 2024.

With the primary gyratory crusher now installed, construction of the new threestage crushing circuit is now substantially complete. Once fully ramped-up, throughput is expected to average 32 million tons per year, which is approximately 2.5 times higher than historical levels, making Rochester one of the world’s largest open pit heap leach operations.

A multi-day test of truck and loading capacity was completed earlier this month to ensure that the mine can support the higher throughput rates associated with the newly-configured Rochester circuit. This test confirmed the mine’s ability to safely support the designed capacity of up to 100,000 tons per day (t/d) in 2023 and up to 132,000 t/d in 2024. Data gathered during the test will be used to refine processes and identify opportunities for additional efficiencies in cycle and load counts.

“The achievement of these three critical milestones marks the beginning of a new growth phase for Coeur,” said Mitch Krebs, president and CEO, Coeur Mining. “The focus is now shifting to commissioning, ramp-up, and mine optimization initiatives as well as prioritizing several adjacent exploration targets located on Rochester’s prospective 69-square-mile land package. Coeur’s project team has overcome numerous challenges over the last three years to arrive at this key inflection point and deserves thanks for their resilience and commitment.”