Chemical Engineering May 2020 - 9

Ion-exchange beads for lithium extraction
W
ith lithium demand higher than
ever, processors are increasingly
turning toward emerging
technologies and new
resources for lithium extraction. A new
California-based project launched by Controlled
Thermal Resources (CTR; Imperial,
Calif.; www.cthermal.com) and Lilac Solutions
(Oakland, Calif.; www.lilacsolutions.
com) aims to directly extract lithium from
geothermal brines that are 4,000 ft below
the surface in the Salton Sea Geothermal
Field using new ion-exchange (IX) beads.
" Direct lithium extraction from geothermal
brines is a continuous, closed-loop process
that returns spent brine to its original source.
It has a very small physical footprint, is not
weather-dependent and is powered by renewable
energy, " explains CTR principal engineer
Jason Czapla.
Adapted from coating techniques used
in cathode materials, Lilac Solutions' IX
beads incorporate surface nano-coatings
and tailored compositions to selectively absorb
Li+ ions from the brine, explains Lilac
Solutions CEO Dave Snydacker. The Li+ is
then released by the addition of acid. " The
beads' unique crystal structure features
a very strong binding energy for lithium,
enabling high recovery from lower-grade
brines, " adds Snydacker. Lilac has demonstrated
the IX technology in two 1,000-L/h
modules on brines including high concentrations
of Ca+2 and Li+ concentrations as
low as 100 mg/L. Furthermore, the beads'
surface coatings are designed to prevent
degradation and enable a long lifecycle.
The modular nature of Lilac's IX technology
makes it a good candidate for commercial
scaleup - the team has successfully
scaled from 1 L/h up to 1,000 L/h
over the last 18 months. With startup anticipated
later this year, the 1,000-L/h pilot
plant with CTR, in concert with Lawrence
Berkeley National Laboratory, San Diego
State University and Nalco Water, will
demonstrate brine pre-treatment alongside
Lilac's IX process to produce highpurity
lithium chloride, which will be further
processed into lithium hydroxide and lithium
carbonate at offsite facilities. CTR was
recently awarded a $1.5-million grant from
the California Energy Commission to put
toward this piloting effort.
In addition, there have been
concerns that TiO2 could be
harmful to health.
To eliminate the use of TiO2,
the researchers have developed
porous polymer structures
of comparably high
scattering efficiency. The polymer
was inspired by the white
beetle Cyphochilus insulanus,
whose chitin scales appear
white thanks to their special
nanostructure. " Based on this
model, we produce polymerbased
solid, porous nanostructures,
which resemble a
sponge, " says Hölscher. Similar
to the bubbles of shaving
or bathing foam, the structure
scatters light, which makes
the material appear white.
" The polymer foils produced
by our process are extremely
thin, flexible and of low weight,
but are still mechanically stable
and can be applied industrially
to a variety of products, " the
physicist explains. At a thickness
of 9 µm, the polymer foil
reflects more than 57% of the
(Continues on p. 10)
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Chemical Engineering May 2020

Table of Contents for the Digital Edition of Chemical Engineering May 2020
