Chemical Engineering June 2023 - 15

making XRF impractical to use in the
field, explains Sackett. The Z-9 uses a
technique called laser-induced breakdown
spectroscopy (LIBS), which
fires a focused laser at a material,
delivering an extremely high instantaneous
power to vaporize the material,
creating an electron plasma. " As
the plasma cools over a microsecond
time scale, the electrons recombine
with the atoms, causing characteristic
wavelengths of light to be emitted
in the infrared, visible and ultraviolet
spectral regions, " notes Sackett. The
wavelengths are unique to specific
atoms, forming the foundation for
measuring concentration.
The Z-9 has a built-in spectrometer
to measure the wavelength and intensity
of the emitted light, which can
be used to produce a concentration
measurement for lithium and other elements
in the brine. Notably, the device
requires only 1-2 mL of sample
per test, and no dilution is required, so
tests can be completed very quickly.
" In order to make the device work
properly, SciAps scientists had to
modify the LIBS design to aerosolize
the brine liquid, causing the plume of
liquid to be injected in front of the focused
laser to generate the plasma, "
adds Sackett. The Z-9 has been operating
at large brine-processing operations
in Chile and the U.S. Gulf Coast,
as part of an extensive field-testing
effort. Commercial units are currently
under production.
Sorbent materials
One of the key technological considerations
in lithium extraction is
the selection of adsorbent method.
Since there are so many physical
considerations, from the temperature
of the brine to the dilute lithium
concentrations (brines will sometimes
have more than 10,000 times higher
sodium concentration than lithium),
finding an optimal material to perform
with high selectivity is challenging.
Researchers at Oak Ridge National
Laboratory (ORNL; Oak Ridge, Tenn.)
have seen very promising perforOther
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mance in extracting
lithium
from geothermal
brine using
iron-doped
lithium-aluminum-layered
double
hydroxide
chloride
(LDH)
sorbent and
forward osmosis.
" LDH sorbents
can opSciAps
FIGURE
3. The ability to
rapidly analyze brine concentration
in the field will
help to streamline lithium
extraction
erate perfectly under geothermal
brine conditions, around 95°C. Also,
there is no need to add any reagents
to adjust the pH for lithium extraction.
It is a low-cost sorbent material with
lithium-recovery rates greater than
95%, " explains Parans Paranthaman,
corporate fellow at ORNL. In partnership
with the Critical Materials Institute
at Ames National Laboratory (Ames,
Iowa; www.ameslab.gov), ORNL has
run column extraction using LDH
sorbents for more than 500 h with
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Chemical Engineering June 2023

Table of Contents for the Digital Edition of Chemical Engineering June 2023
