Minera del Altiplano S.A. (MdA), Livent’s Argentine operating subsidiary, owns and operates lithium brine production facilities and related chemical processing plants in the Western Subbasin of Salar del Hombre Muerto (SdHM). The operation is referred to as Project Fenix.
On January 4, 2024, Allkem and Livent Corp. officially completed their merger to become Arcadium Lithium plc. Livent Corp. is now a wholly owned subsidiary of Arcadium Lithium plc.
On March 6, 2025, Rio Tinto completed its acquisition of Arcadium Lithium plc. Rio Tinto is now the ultimate parent company of Arcadium Lithium, which will become Rio Tinto Lithium.
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Summary:
The Salar del Hombre Muerto (SdHM) is one of the most important evaporitic basins in the Argentinean Puna and is the first basin to produce lithium from brine in Argentina. It consists of evaporite deposits formed within an isolated endorheic basin, bounded by pre-Paleozoic, Paleozoic, and Cenozoic–age crystalline metamorphic basement rocks. Fault-bounded bedrock hills occur within and along the margins of the salar basin, further subdividing SdHM into two separate subbasins (eastern and western), each with different evaporite sediment compositions. The Western Subbasin is considered a mature salar. Mature salars are dominated by massive central cores of halite with salar-margin sheets of clastic deposits. A transition of primary evaporite minerals is observed from basin margins to basin centres, proceeding from carbonates at margins through borates, sulphates, and ultimately chlorides (halite) in basin centres.
Several key characteristics are required to develop the lithium-rich brines common in the Puna and are present at the SdHM: an endorheic basin, arid climate, tectonically driven subsidence, igneous or geothermal activity, lithium-bearing source rocks, adequate aquifer(s)/reservoir(s), and sufficient time to concentrate the brine (Bradley et al. 2013). The lateral boundary of the evaporite sedimentary deposits of the Western Subbasin of the SdHM is roughly circular in shape, approximately 20 km in diameter, coinciding with the contact between sediment and surrounding bedrock. The deposit is hydraulically unbounded at the saddle where the Eastern and Western Subbasins connect, which allows brine in the Eastern Subbasin and brackish water from the Rio de los Patos to enter the Western Subbasin. The deposit is open to the south where the groundwater flow from the Trapiche Aquifer enters the salar. At both locations, water or lithiumrich brine flows into the deposits of the Western Subbasin. The vertical extent (depth) of the lithium-rich brine deposit is inferred from surface geophysical surveys to approximately 900 m. However, confirmation drilling has not been performed to ground-truth geophysical survey interpretations below 300 m. Based on surface geophysical surveys, and several deep (>200 m) drill holes, the bedrock–halite contact is likely greater than 200 m in most of the Western Subbasin and may exceed 900 m in the northwest.
Salar aquifers at SdHM host lithium-rich brine in the pore space between sediment grains and in primary or secondary fractures. Owing to the depositional environment present at the time the aquifers were formed, these aquifers consist of horizontal to sub-horizontal clastic sediments and evaporites. The package of sedimentary and evaporitic aquifers that host lithium brine beneath the salar surface are collectively referred to as the brine reservoir.
The interconnected nature of pores and fractures governs the ability of brine to drain from the reservoir in response to pumping and is a key factor for assessing the recovery potential of lithium from brine. As evidenced by nearly 30 years of production, the shallow interval (~0 m to 40 m bgs) of the reservoir near the centre of the Western Subbasin of SdHM where all pumping occurs, has exceptionally favourable hydraulic characteristics for brine production.
Lithium in brine has low local variability with relatively consistent or increasing grades in the salar area and with increasing depth.
A fractured halite aquifer contains the bulk of extractable lithium. The fractured halite unit is an unconfined aquifer composed of a thick sequence of halite with an extensive network of primary (physical) and secondary (dissolution) fractures from ground surface to approximately 40 m bgs. Fracture density decreases with depth below 40 m resulting in decreasing drainable (effective) porosity with depth. The fractured halite aquifer ranges in thickness from 40 m at the salar nucleus becoming progressive thinner towards the margins of the salar where clastic materials interbed with evaporites where alluvial fans are present.
Water enters the salar from both streams and groundwater discharges from basin-bounding alluvial fans (and potentially from adjacent rock formations). In the broader SdHM watershed, the dominant surface water inflow is via Rio Los Patos, in the Eastern Subbasin. At times of high flow, surface waters accumulate on the salar in the Laguna Catal, which at times can extend into the eastern portion of the Western Subbasin. In the Western Subbasin, the Trapiche and Penas Blanca rivers provide a source of groundwater inflow. Both rivers coalesce at the head of the Trapiche Aquifer before infiltrating into the alluvium approximately 6 km south of the salar-alluvium boundary. Water inflows from infiltration of precipitation are negligible. Annual average precipitation rates are less than 90 mm and evaporation rates average more than 2.5 m annually.
SdHM is an endorheic basin. Evaporation and plant transpiration are the primary processes for water outflow, followed by groundwater pumping for brine processing. Currently, less than 10 percent of the average annual runoff is used for brine processing. Following brine processing, most of the water is returned to the Western Subbasin along with spent brine where it evaporates or infiltrates back into the salar.