Copper volumes and water savings: inside Antofagasta’s Centinela mine expansion

Edited by ad hoc news Flagship & Bestseller Desk. Reviewed before publication on 06/15/2026 at 11:28 AM ET. Details in the imprint.

Antofagasta’s big growth lever in copper right now is not a new greenfield project but the planned expansion of its Centinela mining complex in Chile’s Antofagasta region, where the group is adding a major new concentrator line to lift output and cut freshwater intensity at the same time.

How the Centinela expansion is designed to push copper volumes

The Centinela district combines open-pit mines and processing plants that already produce copper concentrate and cathodes, plus gold as a by-product, but Antofagasta has been working on an expansion that will add a second concentrator with a nameplate capacity of around 95,000 metric tons of ore per day once fully ramped up. According to the company’s description of the project, the new plant will increase annual copper production at Centinela by roughly 170,000 tons in the first ten years of operation, pushing the complex well above the 300,000-ton-per-year mark when combined with existing facilities. The project scope includes a new concentrator, additional grinding and flotation circuits, and associated infrastructure such as tailings handling, a larger water recovery system and power connections that tie into Chile’s national grid.

Centinela is located in Chile’s arid Atacama Desert, so the expansion has to work within tight environmental constraints, notably water use and emissions, that are increasingly central for global copper buyers and regulators. Antofagasta emphasizes that the new plant is configured to process sulphide ore resources at higher throughput while maintaining a relatively low strip ratio in the pits, which matters for both operating costs and land disturbance. In parallel, the company has highlighted that Centinela benefits from existing pipeline and port infrastructure at the nearby port of Michilla, limiting the need for entirely new logistics corridors even as concentrate volumes rise. The expansion has been under detailed engineering and permitting for several years as the company balances capital discipline with the goal of adding low-cost copper tons into what it expects to be a structurally tight market.

Financing and capital intensity are also central to how the Centinela project is framed for investors and offtakers. Antofagasta has previously guided that the total capital cost of the expansion will run into the low single-digit billions of dollars over several years of construction, with spending phased to match cash flow and market conditions rather than front-loaded in a single budget cycle. That approach is meant to keep the group’s balance sheet within its stated net-debt comfort zone even if copper prices weaken temporarily, while still preserving the option value of bringing on a large increment of new production in the late 2020s. The company has noted that, once in operation, the new concentrator should sit in the lower half of the industry cost curve thanks to economies of scale, a high degree of automation and the use of existing site infrastructure.

Water, desalination and the environmental profile of Centinela

Water management is a defining feature of Centinela and its expansion plans because the operation sits in one of the driest regions on the planet and faces strict regulatory expectations on groundwater use. Antofagasta has made a point of shifting its Chilean operations toward seawater and desalinated water, and for Centinela the company states that the mine already operates on a combination of raw and desalinated seawater transported via pipeline from the Pacific coast. The new concentrator is designed to run fully on seawater, with no draw on continental freshwater basins, which aligns with Chilean regulatory trends and with the decarbonization objectives of many large copper consumers who increasingly screen supply chains for water stress indicators. This technical choice requires additional pumping energy, but the group has committed to sourcing 100 percent of its power in Chile from renewable electricity contracts, which partially offsets the higher energy load of seawater use.

Tailings and waste management are another environmental focus, with Antofagasta indicating that Centinela uses thickened tailings technology to reduce water loss and shrink the physical footprint of the tailings storage facility. For the expansion, the company plans to integrate the new plant into the existing tailings system, which is sized for additional capacity and has been designed with what Antofagasta describes as conservative engineering standards after industry-wide scrutiny of tailings storage following high-profile dam failures elsewhere. The company’s sustainability reporting references the Global Industry Standard on Tailings Management as a benchmark and notes that Centinela’s facilities are subject to regular internal and third-party reviews. On air emissions, the mine’s remote desert location and reliance on electricity from the grid rather than onsite fossil-fired generation mean that local air quality impacts center on dust control from open pits and haul roads, areas where the operator deploys watering, surfactants and vehicle speed limits to mitigate particulate emissions.

Social and permitting dynamics around Centinela are shaped by its long history in Chile’s mining corridor and relationships with nearby communities. Antofagasta points out that the operation has frameworks in place for community engagement, contributions to local education and infrastructure projects, and consultation processes around expansion plans, particularly with respect to land use, road traffic and potential cumulative impacts alongside other mines in the region. The company reports that it conducts environmental impact assessments in line with Chilean law and seeks to respond to public comments and requests for additional mitigation measures, a process that can lengthen permitting timelines but is increasingly important for maintaining a stable social license to operate. At the same time, Centinela is an important provider of direct employment and contractor jobs in the Antofagasta region and contributes to local tax and royalty bases, factors that weigh in political assessments of major mining investments.

From a market perspective, Centinela’s planned additional copper volumes arrive at a time when both automotive electrification and grid infrastructure build-out are driving interest in long-life copper assets with ESG credentials. Antofagasta’s management regularly highlights the company’s exposure to these structural themes and has argued that projects like the Centinela expansion can help narrow an expected supply-demand gap in refined copper, even though the timing and magnitude of that gap remain debated among analysts. For offtakers, the fact that the mine uses seawater and renewable power can be a differentiating attribute in supply agreements as manufacturers and utilities face their own disclosure and decarbonization pressures. Investors, meanwhile, typically weigh the capital intensity and execution risk of a large brownfield expansion against the potential uplift in production, cash costs and mine life, metrics that will only firm up as Centinela moves from engineering into full construction and, eventually, commissioning.

Centinela is one of Antofagasta’s key producing hubs alongside Los Pelambres, Zaldívar and Antucoya, and the expansion is central to the group’s medium-term growth pipeline as it seeks to maintain or expand market share among large copper miners. Antofagasta is headquartered in London and its shares trade on the London Stock Exchange under the ticker ANTO; according to the exchange’s latest data, the company’s stock closed at 4,044 pence on 06/12/2026.

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