The brine deposits of the Salar de Atacama, a salt-encrusted depression in the Atacama Desert in northern Chile, contain high concentrations of lithium and potassium as well as significant concentrations of sulfate and boron.

Deposit Types
The Salar de Atacama brine deposit is contained within porous media filled with interstitial brine rich in Li, K, and boron among other ions.

The Salar de Atacama nucleus is constituted by a thick section of evaporites over a surface area of 1,100 square km and up to a depth of 900 m (Bevacqua, 1992; Xterrae, 2011). It is surrounded by a marginal zone of clastic sediments over an area of about 2,000 square km of extension (Díaz del Río, et al., 1972). The nucleus is mainly constituted by halite (>90%) with sulfate and a minor percentage of clastic sediments as well as some interbedded clay sediments and sulfates. Therefore, the Salar de Atacama is classified as a mature salt flat, according to the site geology and Houston, et al. (2011) classification.

Property Geology
Upper Halite
This unit comprises pure halite and halite with clastic sedimentary material and/or gypsum. The clastic sedimentary material comprises clay, silt, and sand, which are more abundant near surface and decrease with increasing depth. The Upper Halite has a mean thickness of 17 m in the West Block and 23 m in the East Block. In the West Block, the Upper Halite is underlain by a clay lens, gypsum, or carbonate units, depe ........

SQM’s mining operation at Salar de Atacama utilizes brine extraction from pumping wells. Brine extraction is characterized by the construction of vertical pumping wells capable of pumping brine from the subsurface reservoir. The brine is accumulated in different gathering ponds for distribution to the evaporation ponds and metallurgical plants.

The utilized mining method of brine extraction by pumping wells does not require the development of geotechnical studies, because operations are executed without significant excavation. Furthermore, the dominant lithology in the salt flat nucleus (massive evaporites) is typically stable from a geotechnical perspective. However, the mining process includes some salt dumps. These salt dumps have a maximum height of 30 m (environmental restriction). SQM undertook a geotechnical analysis, concluding that the design of the dumps is stable according to the current operating conditions.

Integrated production process can be classified according to natural resources: brines from the Salar de Atacama, which contain potassium, lithium, sulfate, boron and magnesium.

Brines are pumped from depths of 15 to 150 meters below surface, through a field of wells that are located in the Salar de Atacama, distributed in areas authorized for exploitation, and which contain relatively high concentrations of potassium, lithium, sulfates, boron and other minerals. The brines are estimated to cover a surface of approximately 2,80 ........

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