POSCO's 2nd Hombre Muerto Lithium Plant in Argentina Aims for Q4 2026 Completion, Adding 25,000 t/y Capacity

POSCO Group's second lithium plant at the Hombre Muerto salt flat in Salta Province, northwestern Argentina, is targeted for completion in the fourth quarter of 2026, with an annual production capacity of approximately 25,000 tonnes. The company's first plant at the site began operations in 2024. POSCO holds mining rights across 287 km² of the salt flat, with an estimated resource of approximately 3 million tonnes of lithium, following a $280 million investment in 2018 and a further $65 million this year. Brine is drawn from up to 700 metres below ground, at a reported concentration of roughly 92g of lithium per 100L, then evaporated over approximately four months before phosphate compounds are added to precipitate lithium phosphate, which is processed into lithium hydroxide at a refinery on site.

POSCO reported its first quarterly operating profit from the Argentine lithium business in Q2 2026 (April–June), at 11 billion Korean won ($8 million), which the company attributes to rebounding EV demand and rising lithium prices linked to increased ESS demand from AI data centers. POSCO Argentina head Park Hyun said that if the current trend continues, the company expects an operating profit margin above 30% next year a company projection, not a reported result. POSCO plans to add three further plants at the site by 2033, with the second plant now in its final construction phase.

SMM View: The concrete, verifiable event here is a capacity addition a second 25,000 t/y lithium hydroxide plant reaching completion on a Q4 2026 timeline, adding to the roughly 3-million-tonne resource base POSCO holds at Hombre Muerto. That is a specific, dated increment to non-Chinese-owned brine-derived lithium hydroxide supply out of Argentina, distinct from the profitability commentary in the same report, which reflects a single quarter's result plus forward guidance from company management rather than a confirmed margin trend. The China supply-concentration figure cited in the source is the report's own framing rather than an independently verified current market share, and this article does not itself establish any effect on CIF China pricing or on Chinese lithium chemical capacity POSCO's hydroxide is refined and sold outside that pricing benchmark. The one durable, trackable data point going forward is whether Plant 2 commissions on the stated Q4 2026 timeline and reaches nameplate output, since that is what would actually confirm the capacity addition rather than the current construction-stage guidance.