(Reuters) -Teck Resources ( TECK ) beat third-quarter profit estimates on Wednesday, lifted by higher copper and zinc prices, even as production at its Quebrada Blanca copper mine in Chile remained constrained by tailings work.

U.S.-listed shares of Teck rose 2% in pre-market trading.

The results come as Teck advances a merger with Anglo American, announced in September, to form Anglo Teck, a top-five global copper producer headquartered in Canada.

The deal aims to unlock synergies between Teck's Quebrada Blanca mine and Anglo's nearby Collahuasi project in Chile and deliver roughly $800 million in annual savings.

The Canadian miner reported adjusted earnings of 76 Canadian cents per share for the quarter ended September 30, above analysts' average estimate of 49 Canadian cents, according to LSEG data.

Teck said third-quarter profit rose on stronger base metals prices, higher sales from the Red Dog zinc mine in Alaska, lower smelter processing charges and improved performance at its Trail Operations in British Columbia.

Quarterly realized copper prices rose nearly 6% to $4.45 per pound while zinc prices increased 3.2% to $1.29 per pound, from last year.

However, copper production dropped 9.1% to 104,100 tonnes in the third quarter, as output at the Quebrada Blanca mine fell 24.6% to 39,600 tonnes, constrained by ongoing work to raise the tailings dam crest.

The company said the development of the tailings management facility at the site remains the main constraint on production, though improvements in sand drainage and dam construction are underway.

Teck maintained its 2025 copper output outlook for the Quebrada Blanca mine at 170,000-190,000 tonnes at net cash costs of $2.65-$3.00 per pound.