Antofagasta (LSE:ANTO), the Chilean copper miner, shares fell 2% in early trade, to 3,767p, after announcing it produced 142,000 tonnes of copper in the second quarter, down 1% from the first quarter.
It reported second-quarter cash costs before by‑product credits rose 6% quarter-on-quarter to $2.94 per pound.
The company left full-year guidance unchanged at 650,000-700,000 tonnes of copper.
"Copper fundamentals remain strong, with record prices during the period reflecting robust demand and an increasingly constrained supply outlook," said chief executive Iván Arriagada.
Around 7,000 tonnes processed at its Los Pelambres mine stayed in plant inventory after extended pipeline maintenance and will count as production in the second half.
Cash costs before by-product credits rose 6% quarter-on-quarter to $2.94 per pound, driven by higher diesel and sulphuric acid prices and a one-off labour settlement with the supervisors' union at Centinela.
By-product credits fell 7% to $1.58 per pound on weaker gold pricing, pushing net cash costs up 26% to $1.36 per pound.
Full-year guidance stayed unchanged at 650,000-700,000 tonnes of copper, with output expected to rise through the year as grades and throughput improve at Los Pelambres and Centinela.
The company raised its guidance range for cash costs before by-product credits to $2.40-2.60 per pound, citing fuel and consumable prices still above January levels, while keeping net cash cost guidance at $1.15-1.35 per pound.
Antofagasta approved investment in Zaldívar's water supply project during the quarter, a around $0.9 billion pipeline and pumping system over two years that supports a mine life extension to 2051.
Commissioning of the Centinela Second Concentrator Project remains on track to complete next year.
