The deposit type is a brine aquifer within a salar basin. The conceptual model for the Hombre Muerto basin, and for its brine aquifer, is based on exploration of similar salar basins in Chile, Argentina, and Bolivia. Salar basins are characterized by closed topography and interior drainage. The lowest exposed portions of these basins may contain salt encrusted playas, or “salars”. Typically, no significant groundwater discharges from these basins as underflow. All groundwater discharge that occurs within the basin is evaporated. All surface water that flows into the basin is either evaporated directly or enters the groundwater circulation system and is evaporated at a later time.

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 typically contain thin to thickly bedded evaporite deposits in the deeper, low-energy portion of the basin, together with thin to thickly bedded low-permeability lacustrine clays. Coarser-grained, higher permeability deposits associated with active alluvial fans can typically be observed along the edges of the salar. Similar alluvial fan deposits, associated with ancient drainages, may occur buried within the basin-fill deposits. Other permeable basin-fill deposits which may occur within salar basins include pyroclastic deposits, ignimbrite flows, lava-flow rocks, and spring deposits.

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 dominated by Precambrian metamorphic and crystalline rocks. Volcanic tuff and reworked tuffaceous sediments, together with tilted Tertiary rocks, are common along western and northern basin margins. In the Sal de Vida project area, dip angle of Tertiary sandstone is commonly about 45 degrees to the southeast. Porous travertine and associated calcareous sediments can occur in the subsurface and are flat lying. These sediments form a marker unit that is encountered in some locations. Five boreholes located near basin margins have completely penetrated the flat-lying basin-fill deposits. These boreholes, at their maximum depths, reach tilted Tertiary sandstone, volcanic tuff, or micaceous schist.

Metamorphic and crystalline bedrock along the east basin margin are expected to have low hydraulic conductivity and should approximate a “no-flow” groundwater boundary during extraction of brine from basin fill deposit aquifers by pumping wells. Tertiary sediments along the west and north basin boundaries exhibit drainable porosity, and conceptually approximate “low-flow” boundaries that are expected to contribute brine to the basin fill deposit aquifers.

Fine-grained lacustrine deposits are common throughout the exposed basin floor of Salar del Hombre Muerto. These deposits are interpreted to have low hydraulic conductivity. In many parts of the basin, this surface is believed to restrict downward flow of freshwater from the Rio de los Patos that enters the basin from the southeast and flows across the salar toward the north and west. In addition, hydraulic conductivity in the vertical direction of groundwater flow (Kz) is typically less than hydraulic conductivity in the horizontal direction (Kh). For layered sediments, such as occur in Salar del Hombre Muerto, the ratio Kz/Kh is commonly 0.01 or less (Freeze and Cherry, 1979, p. 34). The low vertical permeability of the salar sediments, combined with the density difference between surface water inflow and deep brine, restrict the vertical circulation of fresh water entering the salar from Rio de los Patos.

Well holes with internal pumps will be used to transfer brine to one of three pre-concentration ponds located near the processing plant. At present there are two holes on the property that are drilled to 400 m depth and are suitable for production brine pumping. An estimated 100 L/s of brine will be required to feed the ponds and processing plant sufficiently to achieve the targeted production rate of 5,000 t/a of Li2CO3. Three well holes will be required to achieve this rate. An additional four holes will be drilled during the pre-production period, bringing the total to six and providing double the well requirement as a contingency.

A production rate of 5,000 t/a of Li2CO3 has been targeted for the project. This rate was selected as a reasonable starting level of production, with the potential for expansion once commercial production and/or payback has been achieved.

A 30-year production forecast was assumed for the Project. A production rate of 3,750 t/a was assumed for the first operating year (75% of full production) and a rate of 4,500 t/a was assumed for the second year of operations (90% of full production). All remaining years were scheduled at the full production rate.

The production forecast therefore contemplates a total extraction of 148 kt of Li2CO3 equivalent, approximately 56% of the resource.

The recovery method consists of classic lithium salar concentration and pre-purification through solar evaporation followed by advanced hydrometallurgical processing where the brine is further purified, and the lithium is recovered as a high-purity Li2CO3.
The process involves the following main steps:
- Brine production from wells
- Pre-concentration through solar evaporation in shallow ponds
- Bulk-impurity removal by liming
- Concentration through solar evaporation
- Chemical adjustment prior to boron removal
- Boron removal by solvent extraction
- Advanced impurity removal by polishing precipitation
- Li2CO3 precipitation by carbonation with sodium carbonate (Na2CO3)
- Li2CO3 purification by re-dissolution with carbon dioxide and re-precipitation by desorption
- Li2CO3 drying, conditioning and packaging.

Details on Metallurgical Modelling
Using the methodology above, the concentration area and hydrometallurgi ........