Copper production fell to 153,800 tonnes from 171,900 tonnes, due mostly to lower grades at the company's Centinela and Los Pelambres mines.
Antofagasta PLC Mining News
Chile-focused miner is raising its dividend by 177%.
Unionized workers company’s latest offer for a collective labour agreement.
Chile-focused miner also expects costs to rise on tailings dam expenditure.
This is the second deal the Chilean miner signs with Vancouver-based Evrim Resource.
Representatives of major mining companies believe the global copper market will be balanced for the foreseeable future even as mine supplies tighten and demand from China, the world's top consumer, remains strong.
Despite the quarterly increase in net cash costs Antofagasta said the 2017 costs would be below the $1.30 per pound previously forecast.
The miner believes a tightening global supply of copper will keep prices on the high-end of the spectrum this year and next.
Miner said country offers more favourable conditions to start new projects than Chile, where Antofagasta has majority stakes in four copper mines and has just opened a new one — Antucoya.
Workers at Zaldivar are set to vote on a strike this week, while supervisors at Centinela mine have already decided it, but expect a government mediation mechanism to extend negotiations for at least five more days.
The International Center for Settlement of Investment Disputes (ICSID) said Pakistan violated several provisions of its bilateral investment treaty with Australia, where the joint venture between Barrick and Antofagasta is incorporated.
The company expects demand to increase 3% this year, while no new mines are scheduled to come online in the short-term and supply disruptions continue.
Chile's environmental regulator has drawn up nine charges against the copper mine for mismanaging water resources and nearby flora.
The Chilean copper miner said full-year production would be at the lower end of the 710,000 to 740,000 tonnes it predicted in January.
The miner expects an output of 710,000-740,000 tonnes for 2016 as it ramps up production at its Antucoya and Centinela Concentrates mines, as well as from its share in Zaldivar mine, which co-owns with Barrick Gold.
Locals claim the dam has diverted the course of a local estuary, causing water shortages at a time of drought.
The proceeds of the sale will be used to reduce a debt pile of $13 billion with a target of wiping out $3 billion this year.
The ongoing slump in copper prices spells trouble for Chile's mining industry, where most medium-sized producers are already unable to make a profit.
Worries over China's growth and its impact on commodity prices prompted broker downgrades for some of the industry’s biggest names.
This is the second time this year that the London-listed miner slashes its annual copper production guidance.
The recurring phenomenon — a warming of the Pacific Ocean as part of a complex cycle linking atmosphere and ocean — has in the past affected mine output, triggering price spikes.
Torrential rain in Chile's desert region and environmental protests dented first-quarter output, forcing the miner cut its annual production forecast.
La Serena appeals court unanimously rejected a lawsuit presented by locals, which claimed the massive tailing dam had dried up a nearby stream and contaminated underground water.
Mostly due to a lower estimate from Anglo American's projects and the Zaldivar mine, which is operated by Barrick.
This is the second warehouse in less than two days the court suspends due to health risks from nearby particles.