Posco Holdings has completed construction of its second upstream lithium processing plant at the Salar del Hombre Muerto site in Argentina, adding 23,000 tons of lithium carbonate capacity per year at an investment of roughly US$954 million. The new line lifts the group's total annual lithium processing capacity at the site to about 48,000 tons.

The plant sits on a brine concession that straddles the border of Salta and Catamarca provinces. Posco first acquired mining rights to the salt flat in 2018 and brought its first upstream plant online in 2024. The second line brings site capacity to nearly double the output of that earlier train, with both lines drawing on the same lithium-rich brine resource.

Where does the carbonate go next?

Posco, best known as South Korea's largest steelmaker, has spent the past decade repositioning itself as a battery materials supplier to global cell producers. Lithium carbonate recovered at the new Argentine plant will be shipped to a second downstream processing facility now under construction at the Yulchon Industrial Complex in South Jeolla province, South Korea. There it converts the feedstock into battery-grade lithium hydroxide.

The company described the project as part of its broader push to strengthen its position in the global battery materials supply chain. Posco said it will ship lithium carbonate produced at the second Argentine plant to Yulchon once both lines are operational.

How downstream capacity scales by 2033

Posco plans to build two more downstream lithium processing facilities in South Jeolla province by 2033. Combined with the Yulchon facility and existing assets, that build-out would lift the group's annual battery-grade lithium hydroxide capacity to 100,000 tons.

The 2033 target would consolidate Posco's conversion footprint inside a single Korean province. The integration model — brine extraction at one end, hydroxide conversion at the other, both under Posco Holdings — is the lever the group is using to position for long-term supply contracts.

What is confirmed versus announced

The US$954 million figure and the 23,000-ton capacity addition come from Posco's own announcement. Independent confirmation of the build cost, brine yields, and the identity of any contracted offtake partners remains pending until the plant runs at steady state and discloses utilization data.

The 100,000-ton downstream target by 2033 is a stated ambition rather than a contracted program with named customers. Argentina's Lithium Triangle, covering parts of Jujuy, Salta, and Catamarca, has drawn sustained interest from Asian, North American, and European automakers and battery groups seeking to localize supply outside Chinese-dominated conversion capacity. Posco's vertical integration model parallels strategies at several peers in the region, though royalty revisions and brine chemistry issues have slowed other projects in the area.

What to watch next

• Mechanical completion and commissioning of the second downstream hydroxide line at the Yulchon Industrial Complex
• Posco's progress toward the stated 100,000-ton annual hydroxide target by 2033
• Spot lithium carbonate pricing, which has stayed weak through 2024-2025 and continues to compress converter margins
• Long-term offtake announcements that convert announced capacity into confirmed volumes