The results of geophysical survey suggest that the deepest part of the basin is in the center, where salar deposits may reach up to 300 m thick.

The results indicate that the eastern and northern basins of the Salar de Hombre Muerto are floored largely by clastic material with thin horizons of precipitated borax, halite, gypsum, and calcite.

Field observations indicated groundwater associated with each of the sand units, so that they may be termed aquifers. The clay units did not produce water and in each case they created a confining bed to the underlying sand unit, so that they may be termed aquicludes, or possibly aquitards (the latter implies the possibility of slow leakage across the bed). Unconfined groundwater in sand unit 1 occurs between 0.7- 0.9 m depth. Sand unit 2 averages 1.8-2.3 m depth. Both these units produced relatively small quantities of fluid. Sand unit 3 produced greater quantities of fluid between 4.1 to >4.7 m depth, and is thus likely to have higher permeability. Sand unit 4 occurred at only a few locations towards the south of the area investigated.

The base of the second clay unit has a distinctive black, organic horizon that can be correlated across the salar. Two depocenters can be identified in the central southern part of the eastern basin, and towards the north, with the source of the sediment infill, looking to be sourced from the Rio Los Patos delta region.

The total sand thickness of all Sand Units in the pits is greatest along the toe of the Rio Los Patos delta, where it reaches >4 m in total. Towards the northern depocenter, the Sand Units reach 3 m thickness. The sand fraction again emphasizes the importance of the input of sediment from the Rio Los Patos and the northern depocenter, both of which show >80% sand content in the pit sections.

Mineralization.
Brine prospects differ from solid phase industrial mineral prospects by virtue of their fluid nature. Therefore, the term ‘mineralization’ is not strictly relevant to a brine play, so that here the brine is considered; its flow regime, and its physical and chemical properties.

The distribution of density in the eastern part of the salar shows a general increase away from the Rio Los Patos delta, where relatively fresh water (density ~1.0 gram per centimeter cubic to minus the third degree) enters. As the fluid moves through the more permeable units away from the delta, concentrations, and hence density, rapidly increase to >1.1 grams per centimeter cubic to minus the third degree. This increase is the result of evaporation around the toe of the delta where groundwater is relatively close to the surface. Over much of the eastern basin the density is greater than 1.15 grams per centimeter cubic to minus the third degree, although a tongue of slightly lower density extends from the delta north of the Farralon Catal.

Groundwater enters the salar from the Rio Los Patos delta, from where flow bifurcates with a significant flow extending towards the northwest. Low fluid elevations, or sinks, are seen towards the north and towards the southwest.

The chemistry of the fluids confirms that there is only one brine type within the salar, originating from the evaporation of influent waters.

As calcium reaches a concentration of approximately 40 mmol/l in minus first degree gypsum starts to precipitate and the fluid becomes enriched in sulphate. Throughout the brine evolution sodium and chloride react conservatively, gradually increasing in concentration, and halite saturation which by analogy with other salars in the region occurs at approximately 280 gm/l in minus first degree NaCl.

The distribution of lithium and potassium in the eastern basin at Hombre Muerto are shown that maximum concentrations are associated with the areas of higher density, > 1000 mg/l minus first degree Li, and >10,000 mg/l minus first degree K in the central south, with subsidiary peaks of >800 mg/l minus first degree Li and >8,000 mg/l minus first degree K towards the north.

The area is underlain by the extensive APVC (the Altiplano-Puna Volcanic Complex magma) chamber at depths of only 4 km and it seems likely that this could be the ultimate source, being transferred to the surface via volcanic activity, especially hydrothermal vents. However it is not known whether such transference was direct, or indirect as a result of the leaching of lithium-bearing volcano-clastic sediments, or by the recycling of trapped lithium-bearing solutions. It is known that several hot springs bordering the salar drain directly into the basin. Another possible source of lithium may be related to the borate deposits in the area.

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.

Nine wells will be available for Stage 1, of which seven wells will be operational during the maximum brine pumping season, and two will be on stand-by. Wellfield drilling commenced in late 2020 and to date two production wells have been installed successfully with the remainder scheduled for completion by year end. All wells will be connected through pipelines to a booster station that will be situated in a central location to the wellfield. The average flow from the brine wells to the first evaporation ponds will be approximately 110 litres per second

Evaporation ponds
The first process step will consist of pumping brine into the ponds followed by concentration of lithium brine through evaporation. The evaporation area of 284 hectares (”ha”) for Stage 1 was determined based on the expected evaporation rates from halite and muriate ponds, the well flow rates and required production rate.

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 brine will be fed to another series of evaporation ponds and will be further concentrated. These concentrated brine storage ponds act as buffer ponds before the process plant, to accommodate seasonal flow variations and provide consistent feed to the process plant.

Lithium car ........