Deposit Types
Evaporites and brines form a group of industrial mineral deposits where the commercially valuable commodities are either in solution (brines) or are potentially soluble (evaporites) with the addition of water. This style of deposit typically shows broad lateral continuity, but narrow vertical extents.

Brines are found throughout the Andes region in closed basins (salars) where inflowing waters containing low concentrations of metal are concentrated over time due to evaporation, until they become saturated and begin to precipitate out to form evaporites. Various thermodynamic constraints determine the order in which minerals precipitate.

The Mariana Project is a typical salar brine, containing lithium, potassium and boron within permeable aquifers.

Mineralization
The mineral commodities sought at the Mariana Project are metal ions dissolved within brines. Lithium salts are much more soluble than potassium and sodium, which tend to precipitate forming halite units.
The brines are subject to hydrogeological flow regimes allowing replenishment of brines that are extracted from the system.

The observation of brine within all drillholes across Salar de Llullaillaco basin suggests the existence of a connected unconfined brine-bearing system. The spatial distribution of lithology, lithological description and grain size distribution plus other associated elements, such as secondary porosity, were the most rele ........

Mining Method
Early phase hydrogeological tests in 2015, and current on-going long-term pump tests, indicate the brine extraction from the Salar de Llullaillaco will involve installing and operating a conventional brine production well field. The conceptual model for mineral recovery from brine reservoirs is a combination of brine extraction well field with brine pumped to a series of solar evaporation ponds and preliminary in-field brine treatment.

The production process starts when brine is pumped from the aquifer beneath the Salar, using electrical pumps, placed in bores (wells) that are completed in the Salar. The extracted brine is pumped from each well to a main distribution pipeline and then to the evaporation ponds.

Brine Well Field
Early phase hydrogeological tests in 2015, carried out at low, approximately 3 L/s pumping rates, concluded that pumping at rates greater than 97 L/s was not advisable, as drawdown at higher rates was estimated to be excessive and could potentially draw below the well filter. This was based on the upper aquifer limits and is therefore considered conservative. On-going pump test work, at higher pumping rates in the order of 60 L/s, indicate a similar to, or steeper, predicted flow rate to drawdown curves as the early tests. Given the final assessment of the on-going longterm pump tests is not finalized, the original interpolation has been used in the current conceptual design of the brine well field.

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