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.
DETERMINING GROUNDWATER LEVEL AND SALT COMPOSITION
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.
Because 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.
DATA LOGGERS WITH CONDUCTIVITY MEASUREMEN TS
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
