London-listed Antofagasta has completed a review of the project schedule and costs for an expansion of its flagship Los Pelambres copper mine in Chile, and on Thursday reported a revised capital cost estimate of $2.2-billion.

This is a 30% increase from the previous estimate of $1.7-billion and was mainly owing to the impact of Covid-19 on costs and the construction schedule, as well as generation inflation, including increased input prices, wages, labour incentives and logistics costs.

Antofagasta in early 2021 raised the capex estimate from an original $1.3-billion to $1.7-billion, owing to revised marine works that were needed to enable the future expansion of the desalination plant.

Antofagasta stated that the completion schedule for the expansion project remained unchanged with the desalination plant expected to be completed in the second half of this year and the expanded concentrator plant in early 2023. At the end of March, the project was about 73% complete.

The expansion will add an average of 60 000 t/y of copper to the mine’s production over the first 15 years. Throughput at the plant will be increased from 175 000 t/d of ore to an average of 190 000 t/d of ore.

Antofagasta, meanwhile, reported first-quarter production of 138 800 t, which is 24% lower than the same quarter of 2021 and 22% lower than the fourth quarter’s output. However, this is in line with the company’s previous guidance and was because of the temporary reduction in throughput at Los Pelambres as a result of drought and lower grades at Centinela Concentrates.

Throughput at Los Pelambres was 39.9% lower than in the corresponding period and 27.7% lower than the preceding quarter. The grades at Centinela were 26.7% and 25.4% lower, respectively.

Gold production was 38 400 oz in the first quarter, which was 35% lower than a year earlier and 40% lower than in the fourth quarter, owing to lower grades at Centinela.

Antofagasta said its guidance for the year remained unchanged. The group’s copper production would be between 660 000 t to 690 000 t, at a cash cost of $2/lb before and $1.55/lb after by-product credits.