Commercial production was reached at the end of September, slightly ahead of target and midway through the previously stated six to seven-month ramp-up period.
Gruyere is expected to produce 300,000oz/y at average all-in sustaining costs of A$1,025 (US$697) an ounce over 12 years.
Management declared commercial production based on a pre-determined minimum total process plant throughput rate of 70% of nameplate capacity, and a minimum average gold recovery of 85% of expected life of mine metallurgical recovery, measured over a month, with the expectation that these metrics will continue to be met or exceeded in the future.
As throughput rates and gold recoveries during ramp-up have been above expectations, the JV now anticipates gold production for 2019 to be at the upper end of guidance of 75,000-100,000oz of gold.