Chile's national mining company Enami chose Anglo-Australian Rio Tinto as its partner to explore and develop the Altoandinos project, the largest undeveloped lithium deposit in the country.
The agreement — a public-private concession — gives Rio Tinto a 51pc stake in the project, with Enami holding the remaining 49pc. Both parties will invest a combined $3bn into the project, with Rio Tinto paying $425mn, according to Enami.
Enami's board unanimously chose Rio Tinto out of a pool including China's BYD, French Eramet and South Korea's Posco.
The miner will be responsible for the project's entire operation, which will be based on its proprietary direct lithium extraction (DLE) technology. DLE does not require brine to be evaporated and allows for a much faster, more environmentally friendly operation, the company said.
Rio Tinto will also help Enami finance the project until it reaches financial operation and will contribute to all necessary expenses to conduct a pre-feasibility study.
Rio Tinto's DLE expertise helped close the deal because its Rincon plant in Argentina will be used as a demonstration and pilot plant for the Chileans since both brines have similar compositions, Enami said.
The Altoandinos salt flar, or salar, has more than 15mn metric tonnes (t) of lithium carbonate equivalent (LCE) and production can reach 75,000t/yr, according to Enami. There is no time set yet for the project to start operating.
This comes less than a week after Chilean copper giant Codelco chose Rio Tinto as its partner to explore the Maricunga salt flat, the second largest undeveloped lithium deposit in Chile.