lithium brine production

Measurement in Lithium Brine Production

Keller measuring equipment is used by mining company Rockwood Litio to determine groundwater level and saltt composition at Salar de Atacama

Salar de Atacama is a salt pan situated at the foot of the Cordillera de los Andes in the Atacama Desert. Created by the evaporation of a primeval lake, it is estimated to contain 27 per cent of global lithium reserves, as well as borax and potassium salt, which is why it is one of the world's most important sites for the production of lithium brine.The valuable lithium is extracted by pumping up groundwater containing dissolved salts and guiding it into flat basins. Potassium chloride and potassium sulphate precipitate in the process, while lithium and boron remain in the solution.

This brine is then sent through pipelines for further processing.The mining company Rockwood Litio that operates in Salar de Atacama uses a network of KELLER DCX-22AA-CTD data loggers in its wells.

Keller sensor

The measuring equipment determines the groundwater level and the composition of the salts it contains. Here, variations in the groundwater level are measured and compared with the volume of water extracted from the wells in order to monitor aquifer recovery following extraction as required by Chilean authorities.This procedure is necessary because Salar de Atacama is a unique and sensitive ecosystem, and excessive groundwater extraction would result in irreparable environmental damage.

Conductivity is also measured, as it is directly related to the water's salinity, which in turn makes it possible to draw conclusions regarding mineral content (e.g. lithium content) in the water.

Keller sensing equipmentBecause the properties of the water in Salar can damage even stainless steel over time, KELLER recommended the use of special corrosion-resistant titanium sensors for the project in Salar de Atacama.The AA measurement method (absolute-absolute) was chosen due to the strong temperature fluctuations that occur.

With AA measurements, changes in air pressure are measured by a separate barometer and subtracted from the hydrostatic pressure in order to calculate the exact water level. Unlike relative pressure measurements, where air pressure must be channelled up to the measuring cell in the sensor, AA measurements do not require the use of a reference tube, in which condensation would form due to the rapid alternation between high daytime temperatures and nighttime frost.The condensed water could then clog the capillary tubes and lead to incorrect measurement results.

The CTD versions of the DCX-22 series are autonomous, battery-operated, low-maintenance data collectors which, along with the,water level (pressure) and temperature, also record conductivity values over long periods of time.

October 2020

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