Chilean Copper Miner Antofagasta Faces First-Ever Strike at Centinela Mine

Two unions at the Centinela copper mine, operated by Chilean miner Antofagasta Minerals in northern Chile, walked off the job on Wednesday, October 7, 2026, after government-mediated talks ended without a deal. As of October 12, the strike is still underway, but both sides have agreed to return to the negotiating table on Tuesday, October 13, under a new voluntary mediation process. All times in this article are given in Chile local time.

The stoppage began at 08:00 on October 7. It was called by the Minera Esperanza union, which has 420 members, and the Distrito Centinela union, which has 289 members. Together they represent 709 workers, or about 22% of the mine's direct workforce. This is the first strike in the history of Centinela and only the second ever recorded at Antofagasta Minerals, the mining arm of Chile's Luksic group.

Centinela is one of the four copper operations run by London-listed Antofagasta in Chile, alongside Los Pelambres, Antucoya and Zaldivar. The mine is located in the Antofagasta Region, about 21 kilometers from the small town of Sierra Gorda, and produces mainly copper concentrate, with molybdenum and gold as by-products. It delivered 240,400 metric tons of copper in 2025 and 97,100 tons in the first half of 2026.

A dispute over equal treatment rather than pay rises

Unlike most mining labor conflicts, the main demand at Centinela is not a general wage increase. The two unions want all employees doing the same job to receive the same pay and benefits, whatever union they belong to. They accuse the company of keeping long-standing gaps between workers in identical positions and of refusing to put forward a proposal that would close those gaps for good.

The unions entered joint collective bargaining for the first time, a process that formally started on August 1. In late September, 98.73% of union members voted to reject the company's final offer, with every eligible member taking part. According to the company, that offer included a 2% real-terms increase in base pay and a one-off bonus of 22.5 million Chilean pesos per worker, worth roughly $22,900, to be paid at the end of the negotiation.

Antofagasta rejects the accusation of discrimination. The company says that any differences in pay and benefits between unions are the result of separate collective agreements signed at different times, and not of an internal policy. It points out that since 2020 the bargaining calendars of its unions have been separated, which means wage increases have been negotiated at different moments.

How the conflict escalated

After the strike vote, Chilean labor law required a mandatory mediation period overseen by the Labor Inspectorate. That mediation ended on October 6 without agreement, and the unions confirmed the walkout the following morning.

On October 8, around 70 workers set up a protest camp outside Antofagasta Minerals' corporate building on Avenida Apoquindo in the Las Condes district of Santiago. Union leaders then said they had received no response from the company, and on Friday, October 9, two union leaders and one worker began a hunger protest to push management back to the table.

The same day, a labor inspection took place at the mine. Centinela said the inspection went normally and that it had kept the operation running during the strike in compliance with labor law and with the workers' right to strike.

On Saturday, October 10, the company announced that it had accepted a proposal from regional labor authorities to resume talks under voluntary mediation. The meeting is scheduled for Tuesday, October 13, at 10:00 in the city of Antofagasta. Centinela said it welcomed the resumption of dialogue and remained committed to reaching an agreement.

Production impact: union warnings versus company guidance

The two sides give very different views of the strike's effect on output. The unions say they represent more than half of the mine's critical operators and over 60% of equipment maintenance workers. In the first days of the strike, the processing plants can still be fed with ore stockpiles built up before the walkout, but extraction, haulage and mine development work have been disrupted, according to union leaders.

The unions expect the impact to build gradually as waste rock accumulates and needs to be removed. They estimate that production could start to fall after about two weeks of strike and that, if the stoppage continues, Centinela's copper output could be cut by about half in November.

Antofagasta has not confirmed these figures and has declined to comment on the union estimates. The company maintains that, despite the usual effects of a strike, its projected production for the year remains unchanged. Antofagasta's 2026 group guidance stands at 625,000 to 655,000 tons of copper, a range that had already been lowered earlier in the year after a weather-related shutdown at another of its mines. In the first half of 2026, group output fell 9.5%, mainly because of lower production at Los Pelambres and Centinela, and the company had been counting on better ore grades and higher throughput at both mines to lift output in the second half.

The real impact will therefore depend almost entirely on how long the strike lasts. A quick agreement at the October 13 meeting would remove the risk of a sharp drop in November, while a prolonged stoppage would put pressure on the company's annual target.

An already tight copper market

The strike comes at a sensitive moment for the copper market. Chile is the world's largest copper producer, and its output has been held back this year by operational problems, falling ore grades and weather events. In August 2026, Chilean copper production fell 12.8% year on year to 369,500 tons, its lowest monthly level since February 2011. Copper prices are trading close to record levels, and the risk of a strike at Centinela had already been supporting prices before the walkout began.

Labor tensions are also rising elsewhere in the country. At BHP's Escondida, the largest copper mine in the world, the supervisors' union, which has 1,009 members, voted 94.8% in favor of a strike. BHP requested formal government mediation on October 5, which temporarily delays any stoppage at the site but does not remove the risk.

For smelters and buyers of copper concentrate, mostly located in Asia, the Centinela dispute adds another source of uncertainty to fourth-quarter supply from Chile. The conflict also comes as Antofagasta has approved the construction of a second concentrator at Centinela, a major expansion project for the mine.

What comes next

All eyes are now on the voluntary mediation session scheduled for October 13 in Antofagasta. The unions have said they are financially prepared for a long strike and will maintain the stoppage for as long as necessary, while the company insists it is open to dialogue but denies any discriminatory policy. Until an agreement is signed, the strike remains active and the risk of lower Chilean copper concentrate shipments in November cannot be ruled out.