Iamgold (TSX: IMG; NYSE: IAG) shares fell Thursday after it cut 202,300 oz., or 17%, off the December 2023 Westwood Complex reserve estimate in Quebec.
The downgrade follows new classification criteria and changes to the mine plan. These reflect lessons learned from past challenges at the seismically active operation. Iamgold has extended Westwood’s mine plan to 2032 from 2025, forecasting production of 925,000 oz. over the period, averaging 146,000 oz. during the first three years of the rejigged plan.
CEO Renaud Adams noted the new reserve figure but highlighted the mine’s transformation.
After a serious seismic event attributed to mining activity in 2015, Westwood faced its worst seismic event in October 2020. This forced Iamgold to suspend operations and redesign its mining approach.
“The updated mine plan demonstrates Westwood’s ability to sustainably produce gold with a refined focus on safety and efficiency,” he said in a Thursday release. Adams also said that better methods have halved seismic events since the mine’s major disruptions in 2020.
The new reserve base totals 2.6 million tonnes grading 11.45 grams gold per tonne for to 1.2 million contained oz., spread across the Westwood and Grand Duc deposits. The company pegged reserves to a US$1,500 gold price, with resources modelled at US$1,800.
Despite the reserve reduction, Iamgold sees Westwood as a core asset with high-grade potential. The company says underground resources are to remain open at depth and along lateral extensions.
Iamgold is to spend US$260.7 million on sustaining capital over the mine’s life. It estimates average operating costs at US$239.91 per tonne processed.
Shares fell as much as 2.25%, or 18¢, to an intra-day low of $7.80, before climbing back to around $7.84 in the early afternoon. It has a market capitalization of $4.5 billion.
Seismic hazard
Iamgold began developing Westwood in 2009 as an underground extension of the Doyon mine, which closed the same year. Commercial production started in 2014, using the existing Doyon mill and infrastructure.
Westwood’s new mine plan uses long-hole open stoping and a pillarless approach to reduce seismic risks. The updated method aims to manage stress distribution and enhance mine stability. Since implementing these measures, seismic activity has dropped by half.
The mine plan forecasts a 95% recovery at the Doyon mill, which has a 1-million-tonne annual capacity. The Grand Duc open pit contributes an additional 56,300 oz. of gold in reserves, with mining set to end in 2025 and batch processing concluding in 2027.
Iamgold said that exploration at Grand Duc continues. There is potential for more resources along open extensions.
Reclamation
The company has committed US$223.7 million for closing and reclaiming the Westwood Complex. This includes US$54.2 million in financial guarantees for the Westwood mine.
Iamgold aims to cut costs. It plans to do this by advancing rehabilitation and studying better remediation methods, it said.
