The deposit model is summarized from Munk et al. (2016) and Houston et al. (2011).

Lithium is found in four main types of deposits:
• Pegmatites;
• Continental brines;
• Hydrothermally-altered clays;
• Oil-petroleum deposits within salty and brine waters underneath hydrocarbons reservoirs.

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 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.

The majority of important lithium-rich brines are located in the “lithium triangle” of the Altiplano–Puna region of the Central Andes of South America and are classified either as “immature clastic” or “mature halite” types.

Houston et al. (2011) note that a key input is the relative significance of aquifer permeability which is controlled by the geological and geochemical composition of the aquifers. Munk et al. (2016) observe that immature salars may contain easily extractable lithium-rich brines simply because they are comprised of a mixture of clastic and evaporite aquifer materials that have higher porosity and permeability.

In the Salar del Hombre Muerto, a mature sub-basin exists to the west as a result of moderately evolved brines decanting from an immature eastern sub-basin over a subsurface bedrock barrier (Houston et al., 2011).

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 belonging to Pachamama formation. Volcanic tuff and reworked tuffaceous sediments, most likely from Cerro Galan complex, 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.

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. 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. Metamorphic and crystalline bedrock along the east basin margin is 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.

The most notable source of fresh water to the 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 show 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 property where aquifer water quality may have a future effect on long-term pumping of the proposed East Wellfield.

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 the Salar del Hombre Muerto, the ratio Kz/Kh is commonly 0.01 or less (Freeze and Cherry, 1979). 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 the Río de los Patos.

Density is typically observed to increase with depth. Fresh or brackish 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 because 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.

Sal de Vida’s brine chemistry has a high lithium grade, low levels of magnesium, calcium and boron impurities and readily upgrades to battery grade lithium carbonate. Dense brine was observed as the interstitial fluid at all depths in the basin, typically increasing brine density with depth. In addition, although there is no borehole data currently to support this, it is anticipated that dense brine will also be located in the lower parts of the older rock units that form the margins of the basin.

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.

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.

Brine operations are not conventional mining operations — the resource is recovered by pumping from deep wells rather than recovering the mineral as a solid ore. The East Wellfield will be located directly above the east sub-basin of the Salar del Hombre Muerto, over the salt pan. The brine distribution will traverse the salar towards to where the evaporation ponds will be located. The production plant will be sited adjacent to Stage 1´s evaporation ponds that will be directly situated to the south on colluvial sediments. The waste disposal areas will surround the evaporation ponds to the north, east, and southeast.

Mobile equipment will be required for plant and pond operations. Some transport services would be supplied to Galaxy under contract with local companies; however, in most cases the equipment would be owned and operated by Galaxy. Galaxy will provide fuel and servicing for all vehicles, with the exception of reagent and product logistics.

Wells and Wellfields
There are two wellfields being considered for production: one in the East and one in the Southwest. For Stage 1, only wells from the East Wellfield will be used, while Stage 2 will utilise the Southwest Wellfield. All production wells will be connected through pipelines to centrally positioned booster ponds. Stage 1 will utilise nine wells, eight of which will be operational during peak brine pumping season, with one on standby.

The production well locations were selected to reduce long-term freshwater level drawdown and maintain as high a brine grade as possible, given each well location and the potential for brine dilution. During wellfield construction, each production well will be tested and analysed immediately after construction.

Well depths, well filters, and well casing blind intervals sealed from pumping were designed based on the following factors:
• Location of lithium-bearing brine zones;
• Location of aquifer zones with comparatively large hydraulic conductivity;
• Location of existing fresh or brackish water zones, and/or future potential for brackish water to enter the wellfield.

The average production well depth in the proposed wellfields is approximately 280 m, and the screened interval of the well where brine can enter the well ranges from 100 – 300 m below surface. However, because substantial areas of the wellfields require additional infill characterization, actual depths and completion zones will be determined in the field based on observation of geotechnical conditions at each proposed well location. Therefore, modifications to individual well construction plans will be undertaken as necessary during construction drilling, based on the actual conditions observed.

Fresh and brackish water zones occur in both proposed wellfield areas. In addition to the upper zones being brackish water in the eastern part of the basin, there are nearby wells to the east of the proposed southwest wellfield where brackish water was also observed in the upper aquifer zones. Therefore, in both wellfields, production wells are designed to seal off the upper part of the aquifer system and in effect, reduce the downward movement of fresh and brackish water into the production zones of wells. Although some subsurface variations exist between the two wellfields, the general design is to seal off approximately the upper 60 m of aquifer at each production well in the Southwest wellfields and approximately the upper 100 m of aquifer in the East wellfield.

The East Wellfield (Stage 1) is designed with 8 operating wells plus one on standby (at peak flowrate seasons). These wells will be equipped with pumps and manifolds to the distribution pipeline. Wells will be cycled on and off as needed to reduce the potential for over-pumping at any given well that could result in excessive drawdown, increased pumping lift, and extra energy costs. Wells on standby will be ready to be turned on when well maintenance or pump repair/replacement is required at other wells.

The materials considered for the brine well area pipelines are HDPE and cross-linked polyethylene (PEX). The maximum capacity of the brine well pumps for this area will be 115 m3/hr each. Each wellfield pump will have a wireless data link to the process plant data acquisition system (SCADA) with remote start/stop capability. Each pump will also have its own dedicated diesel generator and diesel storage tank with three days storage capacity.

Well Pads and Infrastructure
Infrastructure in the wellfield will include well pads, access roads and power generation. Each brine well will have its own generator and diesel storage tank, and each tank will have a residence time of 72 hr. A diesel truck will feed the diesel tanks to keep the diesel generators running. All wells will be connected by road to the booster station. Drilling pads will be elevated to as much as 1.5 m above the salar surface to mitigate flooding risks. Drill pad dimensions will have a platform area sufficient to house the required diesel generators and control instrumentation.

Equipment
Mobile equipment will be required for plant operations. Some transport services will be contracted out to local companies; however, in most cases the equipment will be owned and operated by Galaxy. Galaxy will provide fuel and servicing for all vehicles, except for reagent and product logistics.

All ponds will be harvested using specialized, Galaxy-owned machinery, such as:
• Excavator CAT 330 or equivalent: perimeter trenches and cut trenches;
• Front loader CAT 980 or CAT 990 or equivalent: stacking and loading;
• Trucks CAT 730 or Mercedes Benz Actros 4144 or 3336 or equivalent: 3 – 4 per front loader, depending on the stockpile distance;
• Motor grader CAT 140H or equivalent: brine management control, finishing;
• Roller CAT CS-431 or equivalent: finishing.

The lithium carbonate product will be packed into 1-m3 big bags and loaded onto semi-trailers with side lifters. Trucks will transport the lithium carbonate to the port of Antofagasta in Chile. Lithium carbonate and reagent transport logistics will be outsourced to a local company.

During the first 2 years of operation, Galaxy-owned trucks with a 30-t load capacity, designed for loose bulk wet solids, will be used to transport the magnesium hydroxide and calcium sulphate that will be precipitated as discards from different areas of the lithium carbonate plant. This material will be transported to the co-disposal area. To move the total amount of solids, several bins will be used to alternate bin loading. Trucks for discard transport will be necessary from Year 2 onward.

Thirty-tonne trucks will be used for maintenance and general freight movement around the site. Mobile cranes with 20-t load capacity will be retained at the site for general maintenance. Forklift trucks will be used at the plant for loading lithium carbonate, handling reagents, maintenance workshop and for the general store. Front-end loaders with backhoe will be required for general site maintenance, such as clearing drains. Water trucks (for dust suppression), graders and rollers will be required for road maintenance on the site and for roads leading into the site.

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 process will commence with brine extracted from wells extending to a depth of up to 300 m into the salar. Brine will be pumped to a series of evaporation ponds at a seasonal rate ranging from 53 L/s in winter to 154 L/s in summer, where it will be evaporated to increase the salt concentration beyond the NaCl saturation point. NaCl will precipitate as halite solids that will collect at the bottom of the ponds.

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(OH)2) and borate salts. The solids will ........