Canadian miner Teck Resources on Wednesday lowered its copper production outlook for its Quebrada Blanca (QB) and Highland Valley Copper operations following a comprehensive operational review, citing slower tailings facility development and maintenance issues.

QB, in Chile, is expected to produce 170 000 t to 190 000 t of copper in 2025, down from a previous range of 210 000 t to 230 000 t, after downtime in the third quarter to raise the tailings dam crest. For 2026, the company cut its QB guidance to between 200 000 t and 235 000 t, from 280 000 t to 310 000 t.

Teck, which in September agreed to a $53-billion merger with Anglo American, explained that production at QB continued to be constrained by the pace of development of the tailings management facility (TMF), requiring downtime in the concentrator to manage the rate of tailings rise. From 2027 onwards, the TMF should no longer constrain throughput.

QB's net cash unit costs are forecast at $2.65/lb to $3.00/lb in 2025, compared with earlier guidance of $2.25/lb to $2.45/lb, before easing to $2.25/l to $2.70/lb in 2026 as production improves.

“If initiatives to improve sand drainage or the mechanical raises of the TMF are not successful… production for 2026 and 2027 would be further impacted,” Teck cautioned.

At the Highland Valley Copper mine in British Columbia, the 2025 output guidance was lowered to a range of 120 000 t to 130 000 t, from 135 000 t to 150 000 t, after encountering lower grades and unplanned maintenance.

Overall, Teck’s 2025 copper production across all operations is now expected to be 415 000 t to 465 000 t, down from 470 000 t to 525 000 t previously. Zinc production guidance remains unchanged.

Teck also nearly halved molybdenum output guidance for 2026 to between 2 800 t and 3 400 t, from 6 400 t to 7 600 t previously.

OPERATIONAL PROGRESS AND MERGER 

Despite the slower ramp-up, Teck said the “underlying potential of QB remains intact” and that synergies with Anglo American’s nearby Collahuasi mine could unlock additional value.

“We have previously demonstrated that the QB operation is capable of operating at design levels when TMF development is not a constraint,” Teck said, adding that it remains confident of achieving design recovery rates of 86% to 92%.

Teck president and CEO Jonathan Price said the updated plans were based on “realistic performance assumptions and risk assessments".

Anglo said the revisions were consistent with its independent due diligence and did not affect the rationale for the merger.

“While the specific outcome of the operational review that Teck has announced today was not known at the time, the outcome presented by Teck is broadly consistent with Anglo American's independent due diligence and analysis,” Anglo said in a statement.

Anglo said it was “fully supportive of Teck’s more measured approach to the ramp up of the QB operation, noting that its project teams had managed similar challenges at the Quellaveco copper mine in Peru.

Teck’s revised plan “is designed to establish a tailings facility for the long term, which is critical to realise the very significant inherent value of QB over its life-of-mine,” Anglo said.

The miner reaffirmed its expectation that the merger will deliver $1.4-billion in yearly average earnings before interest, taxes, depreciation and amortisation uplift from combining QB and Collahuasi and $800-million in recurring annual synergies, creating a stronger, more resilient copper producer.