Centinela unions threaten strike as Chilean copper producer expands capacity
Workers demand equal pay and benefits while mandatory mediation leaves room for a settlement.
A contract dispute at Chile’s Centinela copper mine moved into mediation as two unions warned they were prepared to strike, putting pay and benefits at the center of negotiations over a major industrial operation.
The Minera Esperanza and Distrito Centinela unions said on September 29 that they still wanted a settlement, Reuters reported. Together they represented 708 members. Their rejection of the company’s offer triggered a mandatory mediation process, with the possibility of an extension by agreement.
A statement published by the Distrito Centinela union said representatives demonstrated outside Antofagasta Minerals’ Santiago offices that day. Their principal demand was equal treatment for workers who, the unions argued, performed the same functions but received different remuneration and benefits.
The statement reported overwhelming support for strike action in a membership ballot. That account comes from a party to the dispute and should be understood as the unions’ description, rather than an independent audit of the vote.
Union leaders called for senior company executives to help resolve the disagreement. The same statement said the company had requested mandatory mediation, leaving a negotiating route open.
A strike vote is not the same as a stoppage. The reporting did not confirm that production had halted on September 29. The next material developments would be a settlement, an extension of talks or a legally effective walkout, each with different consequences for workers and output.
The dispute comes while Centinela is central to Antofagasta's growth plans. In its half-year results, the company said work on a second concentrator continued toward commissioning in 2027. It reported that group copper output in the first half of 2026 was 285,000 tonnes, down 9% from a year earlier, largely because of lower output at Los Pelambres and Centinela.
Those figures predate the September negotiations. They do not measure a strike's impact or demonstrate that the pay dispute caused the production decline. They do show that the company was managing current operational performance at the same time as a major expansion.
Antofagasta's published financing announcement identifies its ownership of Centinela at 70%, with Japan's Marubeni holding the remaining 30%. The expansion was designed to add an average of 144,000 tonnes of copper a year over its first decade, alongside gold and molybdenum by-products.
