Lithium is found in three main types of deposits:
- Pegmatites;
- Continental brines;
- Hydrothermally-altered clays.

Continental brine deposits typically share the following characteristics:
- Located in semi-arid, arid, or hyper-arid climates in subtropical and mid-latitudes;
- Situated in a closed basin with a salar or salt lake. Salars or salt crusts are common where brines exist in shallow subsurface aquifers;
- Occur in basins that are undergoing tectonically driven subsidence;
- Basins show evidence of hydrothermal activity;
- Have a viable lithium source (e.g., high-silica volcanic rocks, pre-existing evaporites and brines, hydrothermally-derived clays, and hydrothermal fluids). The nearly 5,900 m high resurgent dome of the Cerro Galán caldera may be an important recharge area for Salar del Hombre Muerto at ~4,000 m elevation;
- Have an element of time-stability to allow the leach, transport, and concentration of lithium in continental brines.

Playa (salar) basins typically display closed topography and interior drainage. Generally, no significant groundwater discharges from these basins as underflow. All groundwater discharge that occurs within the basin is by evapotranspiration, which is a combination of direct evaporation and transpiration from vegetation. Surface waters that flow into the basin are either directly evaporated or enter the groundwater circulation system and are subsequently evaporated. The evaporation concentrates solutes, and over time, highly concentrated brines are produced.

Within the salar, the brine concentration is typically most concentrated in the centre of basin, within the evaporite core. Groundwater tends to be more diluted along the margins where fresh water enters the basin and becomes more brackish as the freshwater mixes with brines.

Salar basin locations and basin depths are typically structurally controlled but may be influenced by volcanism that may alter drainage patterns. Basin-fill deposits within salar basins generally contain thin to thickly bedded evaporite deposits in the deeper, low-energy portion of the basin, together with thinly- to thickly-bedded lowpermeability lacustrine clays.

The salar system in the Hombre Muerto basin is considered to be typical of a mature salar. Such systems commonly have a large halite core and are characterised by having brine as the main aquifer fluid at least in the centre and lower parts of the aquifer system.

Conceptual hydrogeological sections were prepared incorporating the results of exploration drilling. The Hombre Muerto basin has an evaporite core that is dominated by halite. Basin margins are steep and are interpreted to be fault controlled. The east basin margin is predominantly Pre Cambrian metamorphic and crystalline rocks. Volcanic tuff and reworked tuffaceous sediments, together with tilted Tertiary rocks, are common along the western and northern basin margins. In the Sal de Vida Project area, the dip angle of Tertiary sandstone is commonly about 45º to the southeast. Porous travertine and associated calcareous sediments are common in the subsurface throughout the basin and are flat lying; these sediments appear to form a marker unit that is encountered in most core holes at similar altitudes. Several exploration boreholes located near basin margins completely penetrated the flat-lying basin-fill deposits, and have bottoms in tilted Tertiary sandstone, volcanic tuff, and micaceous schist.

The most notable source of fresh water to Salar del Hombre Muerto is the Río de los Patos drainage that enters the basin from the southeast. Depth-specific sampling from core holes in this area shows brackish water from the water table to around 60 m depth, and brine concentrations comparable to other parts of the basin below 80 m depth. Because field data in this area are sparse, the density profile of the aquifer is uncertain in the farthest southeast part of the Project area.

Previous work within the Salar del Hombre Muerto basin has shown that brine concentration and chemistry vary both laterally within the salar basin and vertically through the basin sediments. There is a strong positive linear relationship between the density of the brine and the amount of total dissolved solids (TDS).

Other chemical constituents including lithium and potassium generally also increase linearly with density, although the exact relationships vary somewhat throughout the basin. For this reason, the pattern observed for density also applies to TDS and other brine constituents. Density is typically observed to increase with depth. Fresh or brackish meteoric waters are observed within the uppermost 50 m of the aquifer in some locations, typically near the margins of the salar and in the south where the Río de los Patos enters the basin. Results of exploration activities suggests that most of the brackish and fresh water in the system stays in the upper part of the aquifer system, partly given it is less dense, and also because fine-grained lacustrine sediments restrict downward flow. It is possible that there is some deeper fresh water input into the basin, but no fresh or brackish water zones have been observed at depth in any of the exploration holes sampled to date.

The process commences with brine extracted from wells extending to a depth of up to 280m in the salar. Brine will be pumped to a series of evaporation ponds, where it will be evaporated and processed at the onsite lithium carbonate plant. Project facilities are divided into four main areas including wellfield and brine distribution, evaporation ponds, the lithium carbonate plant and discard stockpiles.

The Stage 1 pumping from the East wellfield is expected to produce 10,752 t of lithium carbonate equivalent (LCE) per year while Stage 2 and Stage 3 will generate an additional 10,752 t of LCE per year (totalling 21,504 t and 32,256 t of LCE per year, respectively), with active pumping from both wellfields. Due to seasonal changes in pond evaporation and maintaining the lithium carbonate target for each stage, the modelled production pumping rates are time-variable on monthly and annual timeframes. The process efficiency is assumed to be 68.7% and the expected life of mine (LOM) is 44 years.

The process plant will operate year-round, with a planned plant availability of 8,000 hours per year. The surge capacity of the buffer ponds will allow the plant throughput to remain constant, while the evaporation rate and pond throughput will vary seasonally

The evaporated brine will be fed into the process plant liming circuit, where it will be combined with a slaked lime (Ca(OH)2) slurry. The lime will react with magnesium and boron ions in the brine, removing these impurities as solid magnesium hydroxide (Mg(OH2)) and borate salts. The solids will be separated from the brine and report to a discard facility.

Liming
The buffer ponds will feed evaporated brine to the liming stage to partially remove magnesium. A solution of milk-of-lime will be added to the brine inside mixing tanks, precipitating magnesium and removing other impurities such as boron and sulphates. The solids will be separated from the brine and pumped to a discard facility. The limed brin ........