U.S. patent application number 17/644535 was filed with the patent office on 2022-04-07 for processes for producing lithium compounds using forward osmosis.
This patent application is currently assigned to Terralithium LLC. The applicant listed for this patent is Terralithium LLC. Invention is credited to Brian J. Dougherty, Stephen Harrison, Dennis L. Howe.
Application Number | 20220105466 17/644535 |
Document ID | / |
Family ID | 1000006027437 |
Filed Date | 2022-04-07 |
![](/patent/app/20220105466/US20220105466A1-20220407-D00000.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00001.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00002.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00003.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00004.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00005.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00006.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00007.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00008.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00009.png)
![](/patent/app/20220105466/US20220105466A1-20220407-D00010.png)
View All Diagrams
United States Patent
Application |
20220105466 |
Kind Code |
A1 |
Harrison; Stephen ; et
al. |
April 7, 2022 |
PROCESSES FOR PRODUCING LITHIUM COMPOUNDS USING FORWARD OSMOSIS
Abstract
Systems, methods and apparatuses to concentrate lithium
containing solutions using forward osmosis units are provided,
which, for example, can include providing at least one forward
osmosis unit having at least one lithium containing solution
chamber having at least one first inlet and at least one first
outlet, at least one brine chamber having at least one second inlet
and at least one second outlet, and at least one selectively
permeable membrane positioned between the at least one lithium
containing solution chamber and the at least one brine chamber, and
conveying a lithium containing solution through the at least one
lithium containing solution chamber and a concentrated brine
solution through the at least one brine chamber, said conveying
causing water from the lithium containing solution to be drawn
through the at least one selectively permeable membrane and into
the concentrated brine solution, such that a concentrated lithium
containing solution exits through the first outlet and a less
concentrated brine solution exits through the second outlet.
Inventors: |
Harrison; Stephen; (Benicia,
CA) ; Howe; Dennis L.; (The Woodlands, TX) ;
Dougherty; Brian J.; (Emeryville, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Terralithium LLC |
Houston |
TX |
US |
|
|
Assignee: |
Terralithium LLC
Houston
TX
|
Family ID: |
1000006027437 |
Appl. No.: |
17/644535 |
Filed: |
December 15, 2021 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
16688967 |
Nov 19, 2019 |
11235282 |
|
|
17644535 |
|
|
|
|
16297476 |
Mar 8, 2019 |
11174532 |
|
|
16688967 |
|
|
|
|
62769266 |
Nov 19, 2018 |
|
|
|
62640898 |
Mar 9, 2018 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 61/005 20130101;
B01D 2313/90 20130101; B01D 15/08 20130101; C01D 15/00
20130101 |
International
Class: |
B01D 61/00 20060101
B01D061/00; C01D 15/00 20060101 C01D015/00; B01D 15/08 20060101
B01D015/08 |
Claims
1-6. (canceled)
7. A method of increasing lithium concentration in a lithium
containing solution, the method comprising: providing a lithium
containing solution comprising lithium, silica, and divalent ions;
providing a brine solution; processing the lithium containing
solution in a silica management process to remove silica; providing
at least one forward osmosis unit having: at least one lithium
containing solution chamber having at least one first inlet and at
least one first outlet; at least one brine chamber having at least
one second inlet and at least one second outlet; and at least one
selectively permeable membrane positioned between the at least one
lithium containing solution chamber and the at least one brine
chamber; conveying the lithium containing solution through the at
least one lithium containing solution chamber to concentrate the
lithium containing solution; conveying the brine solution is
through the at least one brine chamber, wherein water from the
lithium containing solution is drawn through the at least one
selectively permeable membrane and into the brine solution, such
that a concentrated lithium containing solution exits through the
first outlet and a less concentrated brine solution exits through
the second outlet; and extracting lithium from the concentrated
lithium containing solution in a lithium capture step to obtain a
lithium rich stream.
8. The method of claim 7, wherein an amount of silica in the
lithium containing solution after the silica management process is
less than about 150 ppm.
9. The method of claim 7, wherein the lithium capture step
comprises contacting the concentrated lithium containing solution
with a sorbent.
10. The method of claim 9, wherein a portion of eluate obtained
from the sorbent is recycled to the sorbent to increase a ratio of
lithium to sodium in the lithium rich stream.
11. The method of claim 7, wherein the concentrated lithium
containing solution exiting the at least one first outlet has a
concentration of lithium chloride of at least about 15 weight %
based on the total weight of the concentrated lithium containing
solution.
12. The method of claim 7, further comprising the step of supplying
the less concentrated brine solution exiting the at least one
second outlet to a recycling unit.
13. The method of claim 7, further comprising recovering lithium
from the lithium capture step to produce the lithium rich
stream.
14. The method of claim 7, further comprising purifying the lithium
rich stream to remove divalent ions and borate ions.
15. The method of claim 7, further comprising concentrating the
lithium rich stream to produce a twice concentrated lithium rich
stream.
16. The method of claim 15, further comprising purifying the twice
concentrated lithium rich stream by removing sodium and potassium
ions to produce a concentrated lithium rich solution having reduced
sodium and potassium ion concentrations.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. Ser. No.
16/688,967, filed Nov. 19, 2019, which claims priority to U.S.
Provisional Application 62/769,266, filed on Nov 19, 2018, and is a
continuation-in-part of U.S. Ser. No. 16/297,476, filed Mar. 8,
2019. U.S. Ser. No. 16/297,476 claims priority to U.S. Ser. No.
62/640,898, filed Mar. 9, 2018. The entire contents and disclosure
of each of these applications are incorporated herein for all
intents and purposes.
FIELD OF THE INVENTION
[0002] The present disclosure relates to the extraction and
concentrating of lithium containing solutions, and in particular to
concentrating lithium chloride brines by forward osmosis.
BACKGROUND OF THE INVENTION
[0003] Brine sources exist naturally, for instance, brine sources
include brine deposits like the Salar de Atacama in Chile, Silver
Peak Nevada, Salar de Uyuni in Bolivia, or the Salar de Hombre
Muerte in Argentina. The term "brines" is used in the broad sense
and includes, in addition to geothermal brines, brines obtained as
waste or by-product steams characteristic of industrial processes.
Other common brine sources are geothermal, oilfield, smackover, and
relict hydrothermal brines. Lithium-enriched brines can also be
found in some deep oil reservoirs. These brines, however, have not
previously been commercially exploited.
[0004] Geothermal brines are of particular interest for a variety
of reasons. First, geothermal brines provide a source of power due
to the fact that hot geothermal pools are stored underground at
high pressure, which when released to atmospheric pressure, can
provide a flash-steam. The flash-steam can be used, for example, to
run a power plant. Additionally, geothermal brines typically
contain various useful metals, such as lithium, lead, manganese,
silver, and zinc, each of which can be recovered from the brine for
further use. These various metal ions, particularly alkali and
alkaline earth metals, as well as silica, iron, lead, silver, zinc,
and manganese, are present in varying concentrations, depending
upon the source of the brine. Recovery of these metals is
potentially important to the chemical, pharmaceutical, and
electronics industries. Typically, the economic recovery of desired
metals from natural brines, which may vary widely in composition,
depends not only on the specific concentration of the desired
metal, but also upon the concentrations of interfering ions,
particularly silica, calcium and magnesium, because the presence of
the interfering ions will increase recovery costs as additional
steps must be taken to remove the interfering ions, before the
desired metals are recovered.
[0005] Lithium may also be recovered from ores, as the ore may be
roasted with sulfuric acid, and the product leached with water. The
resulting lithium sulfate solution is treated with lime and soda
ash to remove calcium and magnesium, and lithium is then
precipitated as a carbonate. Other known methods for recovering
lithium from ores include alkaline methods and ion-exchange
methods, each of which can yield solutions of lithium as hydroxide,
chloride or sulfate. These methods may also include the removal of
calcium and magnesium by treatment with lime and soda ash.
Generally, lithium extraction from brine sources has proven more
economical than production from hard-rock ore.
[0006] Typically, the economic recovery of lithium from natural,
predominantly chloride, brines (which may vary widely in
composition), depends not only on the overall lithium content, but
also upon the concentrations of interfering ions, particularly
calcium and magnesium, which can greatly affect the performance and
economics of the lithium recovery. Product solutions from lithium
extraction processes tend to have very low concentrations of
lithium. Conventional techniques to concentrate the
lithium-containing solutions have generally involved evaporation
with steam or solar energy. Concentrating the solutions by
evaporation requires relatively large capital investment and high
operating costs due to steam requirements. Concentrating the
solutions by forward osmosis requires high pressure and high energy
requirement, and may also cause serious issues with membrane
fouling. The size and operating costs of conventional evaporation,
and the physical and chemical limits of forward osmosis, prompted a
search for alternatives.
SUMMARY OF THE INVENTION
[0007] In some embodiments, the present disclosure relates to
systems, devices, and methods for isolation and concentration of
lithium from various sources. In some embodiments, a lithium
containing solution (e.g., from a geothermal brine) is pretreated
to reduce or eliminate silica and then further processed to render
the solution suitable for concentration by forward osmosis. In
other embodiments, the processing utilizes a lithium-specific
sorbent that preferentially binds lithium, and particular loading,
recycling, and elution profiles are employed to significantly and
specifically enrich lithium ions over other ions (e.g., sodium,
calcium, manganese, etc.). The osmotic pressure in the obtained
solutions is almost entirely a function of lithium ion
concentration, and lithium can be further processed in various
manners to lithium hydroxide or lithium carbonate.
[0008] The present disclosure recognizes the importance of
concentrating lithium containing solutions during the recovery of
lithium from a variety of brine sources. Various embodiments of
methods and apparatuses for concentrating lithium containing
solutions are provided herein. Some embodiments of the present
disclosure include methods of concentrating lithium chloride
containing solutions during the process of lithium extraction from
brines. Other embodiments of the present disclosure include methods
of concentrating lithium chloride containing solutions by removing
water, and also concentrating other metal salt solutions like
manganese, zinc, and other metals to facilitate their recovery from
brines.
[0009] In other embodiments, a method of extracting lithium from a
lithium containing solution includes: supplying a lithium
containing solution to a lithium capture step, the lithium capture
step being operable to capture lithium from the lithium salt
containing solution; recovering lithium from the lithium capture
step to produce a lithium rich stream; optionally purifying the
lithium rich stream to remove divalent ions and borate ions; and
concentrating the lithium rich stream by supplying the lithium rich
stream to a forward osmosis step to produce a concentrated lithium
rich stream.
[0010] In yet another embodiment, a method of extracting lithium
from a lithium containing solution, includes: supplying a lithium
containing solution to a lithium capture step, the lithium capture
step being operable to capture lithium from the lithium salt
containing solution; recovering lithium from the lithium capture
step to produce a lithium rich stream; purifying the lithium rich
stream to remove divalent ions and borate ions; concentrating the
lithium rich stream by supplying the lithium rich stream to a
forward osmosis step to produce a concentrated lithium rich stream;
purifying the concentrated lithium rich stream by removing sodium
and potassium ions to produce a concentrated lithium rich stream
having reduced sodium and potassium ion concentrations.
[0011] In some embodiments, a method of extracting lithium from a
lithium containing solution, includes: supplying a lithium and
silica containing solution to a silica management process to
produce a silica lean lithium containing solution; supplying the
silica lean lithium containing solution to a lithium capture step,
the lithium capture step being operable to capture lithium from the
lithium salt containing solution, and where at least a portion of
eluate obtained from a sorbent in the lithium capture step is
recycled to the sorbent to increase a ratio of lithium to sodium in
a lithium rich stream; recovering lithium from the lithium capture
step to produce the lithium rich stream; purifying the lithium rich
stream to remove divalent ions and borate ions; concentrating the
lithium rich stream by supplying the lithium rich stream to a
forward osmosis step to produce a concentrated lithium rich stream;
further concentrating the concentrated lithium rich stream to
produce a twice concentrated lithium rich stream; and purifying the
twice concentrated lithium rich stream by removing sodium and
potassium ions to produce a concentrated lithium rich stream having
reduced sodium and potassium ion concentrations.
[0012] In some embodiments, the present disclosure is related to
methods of increasing lithium concentration in a lithium containing
solution. In some embodiments, the method includes providing at
least one forward osmosis unit, that has (i) at least one lithium
containing solution chamber having at least one first inlet and at
least one first outlet, (ii) at least one brine chamber having at
least one second inlet and at least one second outlet; and (iii) at
least one selectively permeable membrane positioned between the at
least one lithium containing solution chamber and the at least one
brine chamber; and conveying a lithium containing solution through
the at least one lithium containing solution chamber and a
concentrated brine solution through the at least one brine chamber.
Conveying the solutions through the two chambers causes water from
the lithium containing solution to be drawn through the at least
one selectively permeable membrane and into the concentrated brine
solution. A concentrated lithium-containing solution exits through
the first outlet and a less concentrated brine solution exits
through the second outlet. In certain embodiments, the method
further includes a step of supplying the concentrated lithium
containing solution exiting the at least one first outlet to a
lithium extraction step. In certain embodiments, the method further
includes a step of supplying the less concentrated brine solution
exiting the at least one second outlet to a recycling unit.
[0013] In some embodiments, the concentrated lithium containing
solution exiting the at least one first outlet has a concentration
of lithium chloride of at least about 15 weight % of the total
concentrated lithium containing solution. In certain embodiments,
the concentrated lithium containing solution exiting the at least
one first outlet has a concentration of lithium chloride of at
least about 10 weight % of the total concentrated lithium
containing solution. In certain embodiments, the concentrated
lithium containing solution exiting the at least one first outlet
has a concentration of lithium chloride of at least about 20 weight
% of the total concentrated lithium containing solution.
[0014] Exemplary embodiments of the present disclosure include
systems of increasing lithium concentration in a lithium containing
solution using a forward osmosis unit. In some embodiments, the
system includes a lithium containing solution, said lithium
containing solution derived from a geothermal brine; a concentrated
brine solution, and at least one forward osmosis unit having at
least one first input stream of the lithium containing solution and
at least one first output stream of concentrated lithium containing
solution and configured to increase the lithium concentration in
the lithium containing solution; and at least one second input
stream of the concentrated brine solution and at least one second
output stream of less concentrated brine solution.
[0015] In some embodiments, a lithium containing solution is
pretreated to reduce or eliminate silica and then further processed
to recover lithium from the lithium containing solution via the use
of a sorbent or some other ion selective means such as ion exchange
or solvent extraction and once recovered from the ion selective
material render the solution suitable for further concentration by
forward osmosis. Exemplary embodiments of the present disclosure
include systems of increasing lithium concentration in a lithium
containing solution using a forward osmosis unit after a
pretreatment step to remove silica from the lithium containing
solution. In some embodiments, the system includes a lithium
containing solution, said lithium containing solution derived from
a geothermal or other lithium containing brine; a silica management
unit to produce a lithium containing solution that is free of
silica and thus rendering the brine suitable to extract lithium
from the brine and then be further concentrated lithium containing
solution, and at least one forward osmosis unit having at least one
first input stream of the lithium containing solution and at least
one first output stream of concentrated lithium containing solution
and configured to increase the lithium concentration.
[0016] In some embodiments, a method of preparing concentrated
lithium solutions from a lithium containing solution, includes:
supplying a lithium and silica containing solution to a silica
management process to produce a silica lean lithium containing
solution; supplying the silica lean lithium containing solution to
a lithium capture step, the lithium capture step being operable to
capture lithium from the lithium salt containing solution;
recovering lithium from the lithium capture step to produce the
lithium rich stream; purifying the lithium rich stream to remove
divalent ions and borate ions; concentrating the lithium rich
stream by supplying the lithium rich stream to a forward osmosis
step to produce a concentrated lithium rich stream; and purifying
the concentrated lithium rich stream by removing sodium and
potassium ions to produce a concentrated lithium rich stream having
reduced sodium and potassium ion concentrations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The present disclosure will be better understood in view of
the following non-limiting figures, in which:
[0018] FIG. 1 is a schematic block diagram of an exemplary forward
osmosis system according to some embodiments.
[0019] FIG. 2 is a schematic block diagram of another exemplary
forward osmosis system according to some embodiments.
[0020] FIG. 3 is a graphical representation of the method of the
present disclosure according to some embodiments.
[0021] FIG. 4 is a flow chart of a method for producing lithium
hydroxide from a geothermal brine according to one embodiment.
[0022] FIG. 5 is a flow chart of a method for producing lithium
carbonate from a geothermal brine according to one embodiment.
[0023] FIG. 6 is a flow chart of a method for concentrating a
stream from a lithium capture step in a process of producing
lithium hydroxide according to one embodiment.
[0024] FIG. 7 is a flow chart of a method of using forward osmosis
to concentrate a stream from a lithium capture step in a process of
producing lithium carbonate according to one embodiment.
[0025] FIG. 8 is a schematic diagram of a system for producing
lithium carbonate from a geothermal brine according to one
embodiment.
[0026] FIG. 9 is a schematic diagram of a first embodiment of
system for producing lithium carbonate from a geothermal brine
according to one embodiment.
[0027] FIG. 10 is a schematic diagram of a second embodiment of
system for producing lithium carbonate from a geothermal brine
according to one embodiment.
[0028] FIG. 11 is a schematic diagram of a third embodiment of
system for producing lithium carbonate from a geothermal brine
according to one embodiment.
[0029] FIG. 12 shows an exemplary series of elution profiles for
lithium from a sorbent according to one embodiment.
[0030] FIG. 13 shows an exemplary series of elution profiles for
lithium and other ions from a sorbent during load, wash, and strip
cycles.
[0031] FIG. 14 shows an exploded view of a portion of FIG. 13.
[0032] FIG. 15 shows an exemplary series of elution profiles for
lithium and other ions from a sorbent during load, wash, and strip
cycles according to one embodiment.
[0033] FIG. 16 shows an exploded view of a portion of FIG. 15.
[0034] FIG. 17 shows a system for extracting lithium in a column
according to one embodiment.
DETAILED DESCRIPTION OF THE INVENTION
[0035] I. Introduction
[0036] The present invention will now be described more fully
hereinafter with reference to the accompanying drawings, which
illustrate various embodiments of the invention. This invention,
however, may be embodied in many different forms and should not be
construed as limited to the embodiments set forth herein. Rather,
these embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. It is to be fully recognized
that the different teachings of the various embodiments discussed
below may be employed separately or in any suitable combination to
produce desired results. The various characteristics mentioned
above, as well as other features and characteristics described in
more detail below, will be readily apparent to those skilled in the
art upon reading the following detailed description of the various
embodiments, and by referring to the accompanying drawings. In the
drawings and description that follow, like parts are marked
throughout the specification and drawings with the same reference
numerals, respectively. The prime notation, if used, indicates
similar elements in alternative embodiments. The drawings are not
necessarily to scale. Certain features of the disclosure may be
shown exaggerated in scale or in somewhat schematic form and some
details of conventional elements may not be shown in the interest
of clarity and conciseness.
[0037] Where the specification or the claims provide a range of
values, it is understood that the interval encompasses each
intervening value between the upper limit and the lower limit as
well as the upper limit and the lower limit. The invention
encompasses and bounds smaller ranges of the interval subject to
any specific exclusion provided. Where the specification and claims
reference a method comprising two or more defined steps, the
defined steps can be carried out in any order or simultaneously
except where the context excludes that possibility.
[0038] As used herein, a unit refers to the set of equipment,
structures, processes, materials, and other components that perform
a specific operation in a chemical processing plant. A chemical
process plant can have one or more units to process the raw
materials and obtain the desired products. The various units are
usually connected to one another directly or indirectly by a
variety of means including but not limited to electrical,
mechanical, or fluid means, in a way that allow materials to be
transported from one unit to the next when each operation is
complete.
[0039] As used herein, a brine solution refers to a solution of
alkali and/or alkaline earth metal salt(s) in water, wherein the
concentration of salts can vary from trace amounts up to the point
of saturation. Generally, brines suitable for the methods described
herein can be aqueous solutions that may include alkali metal or
alkaline earth chlorides, bromides, sulfates, hydroxides, nitrates,
and the like, as well as natural brines. Brines can be obtained
from natural sources, such as, Chilean brines or Salton Sea
geothermal resource brines, geothermal brines, sea water, mineral
brines (e.g., lithium chloride or potassium chloride brines),
alkali metal salt brines, and industrial brines, for example,
industrial brines recovered from ore leaching, mineral dressing,
and the like. The present methods are equally applicable to
artificially prepared lithium chloride containing brine
solutions.
[0040] In certain embodiments, a brine solution may be a geothermal
brine solution. In certain other embodiments, a brine solution may
be a geothermal brine solution that has been subjected to silica
removal processes. In some embodiments, the concentrated brine
solution serves as the draw solution to a forward osmosis unit. The
draw solution is any solution that provides for the higher osmotic
pressure in a forward osmosis unit. As a result of forward osmosis,
the draw solution is diluted due to the introduction of water. The
draw solution is usually a highly concentrated solution on the
permeate side of a selectively permeable membrane. In certain
embodiments, the draw solution has a concentration of dissolved
solids from about 5 to 30 weight %, preferably greater than about
10 weight %, more preferably greater than about 15 weight %, based
on the total weight of the draw solution. In certain embodiments,
the draw solution has a concentration of dissolved solids at about
20 weight % of the draw solution. In certain embodiments, the draw
solution may be a geothermal brine. In certain embodiments, the
draw solution may be a geothermal brine after removal of some
elements such as iron, arsenic, silicon, and maybe zinc and
manganese. In certain embodiments, the geothermal brine may contain
a mixture of primarily sodium chloride, calcium chloride and
potassium chloride with minor amounts of other salts. In certain
embodiments, the geothermal brine may have a sodium chloride
concentration from about 15 to about 20 weight %, calcium chloride
concentration from about 6 to about 12 weight %, and potassium
chloride concentration from about 2 to about 5 weight %, based on
the total weight of the geothermal brine. In certain embodiments,
the geothermal brine may have total dissolved salts concentration
from about 25 to about 30 weight % based on the total weight of the
geothermal brine. In certain embodiments, the draw solution may be
a solution of essentially saturated sodium chloride. In certain
embodiments, the draw solution may be a solution of about 20 to
about 40 weight % of lithium chloride based on the total weight of
the draw solution.
[0041] As used herein, a lithium containing solution refers to any
aqueous media containing lithium ions or lithium salts, as the term
is known and understood by those skilled in the art. The lithium
containing solution serves as the feed solution to a forward
osmosis unit. The feed solution is any solution that contains
lithium ions or lithium salts and is subject to concentration by a
forward osmosis unit. In certain embodiments, a lithium containing
solution may be a lithium salt solution. In certain embodiments, a
lithium containing solution may be a lithium halide solution. In
another embodiment, a lithium containing solution may be a lithium
chloride solution. In another embodiment, a lithium containing
solution may be a lithium carbonate solution. In another
embodiment, a lithium containing solution may be a lithium
hydroxide solution. In another embodiment, a lithium containing
solution may be a combination of any of the lithium halides,
lithium carbonate, and lithium hydroxide solutions.
[0042] A lithium containing solution may have a concentration of
lithium chloride between about 0.1 and 10 weight %, preferably less
than about 8 weight %, more preferably less than about 6 weight %,
based on the total weight of the lithium containing solution. In
alternate embodiments, the lithium containing solution may have a
concentration of lithium chloride less than about 5 weight %. A
lithium chloride solution may have a concentration of lithium
between about 0.1 and 10 weight %, preferably less than about 8
weight %, more preferably less than about 6 weight %, based on the
total weight of the lithium chloride solution. In alternate
embodiments, a lithium chloride solution may have a concentration
of lithium of less than about 5 weight %. In certain embodiments,
the lithium containing solution can be a solution of lithium
chloride containing from about 2 to about 6 weight % lithium
chloride, with less than 2 weight % sodium chloride and potassium
chloride, based on the total weight of the lithium containing
solution. In certain embodiments, the concentration of sodium and
potassium chloride is preferably less than about 1 weight %, based
on the total weight of the lithium containing solution. In certain
embodiments, silica may be present in the lithium containing
solution or geothermal brine, and may be removed by a variety of
known methods (e.g., U.S. Pat. No. 4,016,075), prior to use in the
methods described herein. Thus, in certain embodiments, the methods
for the preparation of lithium carbonate described herein can
include a silica management step. In some embodiments, the brine is
supplied to a silica management step, wherein silica is removed
from the brine to produce a silica-free brine or lithium containing
solution.
[0043] As used herein, a forward osmosis unit refers to a unit
configured to carry out a separation process in which the osmotic
pressure difference serves as a driving force for the transfer of
molecules and at least one selectively permeable membrane acts as
separator. A difference in solute concentrations across the
membrane allows the passage of water, but rejects most solute
molecules or ions. In certain embodiments, a forward osmosis system
may include one or more forward osmosis units. Membranes
contemplated for this system include forward osmosis membranes,
ultrafiltration, and microfiltration membranes.
[0044] The selectively permeable membranes provide high water
permeability, high rejection of solutes, and high chemical and
mechanical stability. These membranes are usually resistant to
fouling and adverse effects of high temperatures. In certain
embodiments, the selectively permeable membranes can be compatible
with high chloride brines. The selectively permeable membranes may
be arranged in a variety of configurations. In certain embodiments,
the selectively permeable membranes may be in a flat-sheet
configuration. In certain embodiments, the selectively permeable
membranes may be flat-sheet membranes in plate and frame
configurations. In certain embodiments, the selectively permeable
membranes may be arranged to increase packing density, for example,
in a hollow-fiber or a capillary configuration. In certain
embodiments, the selectively permeable membranes may be in a
tubular configuration. In certain embodiments, the selectively
permeable membranes may be multilayered. For example, the
selectively permeable membrane may comprise an active layer
adjacent to a support layer. In certain embodiments, the
selectively permeable membranes may comprise polymer meshes. In
certain embodiments, the selectively permeable membranes may
comprise cellulose esters. In certain embodiments, the selectively
permeable membranes may comprise cellulose acetate. In certain
embodiments, the selectively permeable membranes may comprise
cellulose triacetate. In certain embodiments, the selectively
permeable membranes may comprise aromatic polyamide polymers.
[0045] In certain embodiments, the flow regime in the forward
osmosis unit is counter current flow, where the flow direction of
the feed solution is opposite to the flow direction of the draw
solution in the forward osmosis units. In certain embodiments, the
flow regime in the forward osmosis unit is co-current flow, where
the flow direction of the feed solution is the same as the flow
direction of the draw solution in the forward osmosis units. In
certain embodiments, the flow regime in the forward osmosis unit
may include different flow rates for the feed solution and the draw
solutions. In certain embodiments, the flow regime in the forward
osmosis unit may include one or more pumping units that regulate
the flow rates and directions of flow of the feed and draw
solutions.
[0046] In certain embodiments, the feed solution is introduced to
the forward osmosis unit at about 300 gallons per minute, and
comprises about 4-6 weight % lithium chloride, 1 weight sodium
chloride, 0.5 weight % potassium chloride, and small amounts of
other impurities. In certain embodiments, the draw solution is
about 750 gallons per minute of geothermal brine containing about
17 weight % sodium chloride, 10 weight % calcium chloride, and
about 3.5 weight % potassium chloride along with smaller amounts of
other salts. About 200 gallons per minute of water pass through the
selectively permeable membrane to the concentrated brine solution.
In certain embodiments, the concentrated lithium chloride solution
flow rate is reduced to about 100 gallons per minute and contains
from about 15 to 20 weight % lithium chloride. The concentrated
brine solution is diluted to about 13 weight % sodium chloride, 8
weight % calcium chloride, and 3 weight % potassium chloride, and
the volume is increased to about 950 gallons per minute. In some
embodiments, the brine can be used to effectively pull water from
the lithium side of the membrane. In this way, it could be possible
to enhance the forward effect by applying a pressure to the lithium
side of the membrane to enhance the water flux and/or the
concentration effect.
[0047] The following methods and method steps are in no particular
order and may not be sequential.
[0048] Provided in FIG. 1 is an exemplary method and system for the
concentration of lithium containing solution using a forward
osmosis unit 11. In certain embodiments, this method and system may
be placed as the ultimate process in the concentration of lithium
containing solutions. In certain embodiments, this method and
system may function as a pre-treatment step before mineral
extraction or recovery processes. In one embodiment, the forward
osmosis unit 11 has at least two chambers 12 and 13, separated by a
selectively permeable membrane 14. A lithium containing solution
enters chamber 12 through at least one inlet 15 and exits through
at least one outlet 16. A concentrated brine solution enters
through at least one inlet 17 and exits through at least one outlet
18. The selectively permeable membrane 14 allows the passage of
water from the lithium containing solution chamber 12 to the brine
chamber 13. By placing a more concentrated brine on the permeate
side of the membrane, the osmotic pressure is forward, and water is
drawn from the lithium containing solution to the concentrated
brine solution.
[0049] In certain embodiments of this process, the lithium
containing solution is a lithium chloride solution. For example,
without limitation, it may be commercially desirable to concentrate
a lithium chloride solution from about 0.5 weight % lithium
chloride to about 20 weight %, based on the total weight of the
lithium chloride solution. This is achieved by using a concentrated
brine solution in a forward osmosis unit that may include, for
example, a geothermal brine, salt brine, or concentrated lithium
chloride solutions from subsequent processing steps. In certain
embodiments, a concentrated lithium containing solution may have a
concentration of lithium from about 2 to 20 weight %, preferably
greater than about 8 weight %, more preferably greater than about
10 weight %, based on the total weight of the concentrated lithium
chloride solution. In alternate embodiments, the concentrated
lithium containing solution may have a concentration of lithium
greater than about 15 weight %.
[0050] FIG. 2 illustrates an exemplary method for the concentration
of lithium containing solution from a brine or other lithium
containing solution. As an initial step of the method, the brine
may be supplied to a silica management step, wherein silica is
removed from the brine to produce a silica-free lithium containing
solution. Then, the silica-free lithium containing solution is a
diluted to produce lithium containing solution 21, and may be
concentrated using a forward osmosis unit 26 to produce a
concentrated lithium ion containing solution. The lithium
containing solution 21 is supplied via a line 22 to a pump 23. As
used herein, a pump is an apparatus for transferring fluids from
one location to another according to set conditions. Such
conditions include, without limitations, a set flow rate, time
intervals, flow direction, and combinations thereof. The outlet
pressure of the pump can be increased to further enhance the amount
of water passing through the membrane. Pump 23 delivers the lithium
containing solution through an inlet 24 to a chamber 25 of a
forward osmosis unit 26. While in this chamber 25, the lithium
containing solution is in contact with a selectively permeable
membrane 27 that separates the chamber 25 from a concentrated brine
containing chamber 24. Due to the osmotic pressure difference
between the fluids in the two chambers 25 and 214, water moves from
the lithium containing solution through the selectively permeable
membrane 27 to the concentrated brine solution. A concentrated
lithium containing solution exits the forward osmosis unit 26
through the outlet 28 to further lithium processing steps 29,
including but not limited to, lithium extraction by electrochemical
means, by physical adsorption means, by chemical means, or
combinations thereof. Other exemplary lithium processing steps may
include solvent extraction, intercalated lithium absorbent columns,
electro-dialysis, forward osmosis, steam evaporation, or solar
evaporation. In certain embodiments, a lithium containing solution
contains lithium chloride, and the concentrated lithium chloride
solution can be subsequently processed to produce lithium
carbonate, lithium hydroxide, and other lithium salts.
[0051] In some embodiments, the lithium containing solution is
supplied to silica management step which operates to significantly
reduce the amount of silica that may be present in lithium
containing solution, such that silicate precipitate and silica-lean
lithium chloride containing solution are produced. Preferably,
after the silica management step, the silica concentration in
silica-lean lithium chloride containing solution is less than about
150 ppm, more preferably the concentration is less than about 100
ppm, even more preferably the concentration is less than about 50
ppm, and even more preferably the concentration is less than about
25 ppm. In certain embodiments, the concentration of silica in
silica-lean lithium chloride containing solution is less than about
20 ppm, less than about 10 ppm, or even less than about 5 ppm. It
is understood that the silica management step may be omitted from
the process for brines that do not include silica, or brines that
have a substantially low initial silica concentration.
[0052] In certain embodiments, the silica management step can
include the step of contacting lithium chloride containing solution
with activated alumina to remove at least a portion of the silica
present. Alumina that includes silica bound thereto can be
regenerated by contacting the alumina with sodium hydroxide.
Alternatively, the lithium containing solution can be contacted
with aluminum chloride, which is converted to aluminum hydroxide,
and can be used to precipitate silica present in the lithium
chloride containing stream. In a further embodiment, iron (II) that
may be present in certain lithium containing brines can be oxidized
with an oxidant, such as air, hypochlorite, hydrogen peroxide,
oxygen, ozone, or a like oxidizing agent, to generate iron (III)
chloride, which after adjustment of the pH to above about 5, from
an initial pH of about 2.5 to 3.5, will precipitate ferric
hydroxide. The ferric hydroxide can adsorb silica from the lithium
containing brine. In some embodiments, the pH is adjusted to
between about 5 and 6 to induce precipitation of silica and iron.
In alternate embodiments, the pH is adjusted to above at least
about 4.5 to induce precipitation of silica and iron. In certain
embodiments, the pH is not increased above about 6, to prevent the
precipitation of other ionic species present in the lithium
containing brine. In yet another embodiment, iron (II) can be added
to the lithium chloride containing solution and oxidized by known
means to iron (III), such as with by contacting the iron (II) with
an oxidant, such as air, oxygen, ozone, hypochlorite, hydrogen
peroxide, or other suitable oxidizing agent. Contacting silica
present in the lithium chloride containing solution with the iron
(III) compound forms a precipitate when the pH is adjusted to
between about 4.5 and 6 with the addition of lime or similar base.
It a preferred embodiment, the pH is adjusted to between about
between about 5 and 6. In alternate embodiments, the pH must be
adjusted to above at least about 4.5 for the silica and iron to
precipitate. In certain embodiments, it is preferred the pH is not
increased above about 6, to prevent the precipitation of other
ionic species.
[0053] In addition, the silica management step can include any
known means for removing a portion of the silica present in the
feed stream, while at the same time maintaining the initial
concentration of lithium. In one embodiment, lithium containing
solution can be contacted with aluminum chloride, iron chloride,
aluminum hydroxide, or the like, to form a precipitate with the
silica. Contacting can be facilitated by known means, such as a
mixing device. Solid silica precipitate removed from lithium
chloride containing solution can be collected and removed from the
mixing or like device, by known means, such as screening or
filtering, to yield lithium chloride containing stream that is
substantially free of silica.
[0054] In certain embodiments, concentrated brine solution 30 can
be fresh geothermal brine, depleted brine from extraction
processes, or brine made from water, or brine with added salt.
Concentrated brine solution 30 is delivered via line 31 to pump 32
that then delivers the concentrated brine solution through an inlet
33 to a chamber 34 of the forward osmosis unit 26.
[0055] As discussed above, due to the forward osmosis process,
water from the lithium containing solution moves through the
selectively permeable membrane 27 to the concentrated brine
solution, thereby diluting the concentration of the brine. In
certain embodiments, the concentration of dissolved solids in the
concentrated brine solution entering the forward osmosis unit is
about 20% weight by weight. In certain embodiments, the
concentration of dissolved solids in the less concentrated brine
solution 35 exiting the forward osmosis unit is less than about 20%
weight by weight. The less concentrated brine 36 can be recycled to
the forward osmosis system or can be mixed with salt to increase
the concentration before being recycled to the forward osmosis
system. In certain embodiments, the less concentrated brine 36 can
be advanced to other metal extraction processes; or it can be
returned to the geothermal brine aquifer.
[0056] In some embodiments, a lithium containing solution (e.g.,
from a geothermal brine) is pretreated to reduce or eliminate
silica and then further processed to render the solution suitable
for concentration by forward osmosis. In certain embodiments, the
method includes the step of supplying the concentrated lithium
containing solution to a forward osmosis apparatus to concentrate
the Li.sub.2CO.sub.3, wherein the forward osmosis apparatus is
operable to remove CO.sub.2 from the solution and cause
Li.sub.2CO.sub.3 to precipitate. In certain embodiments, the
precipitated Li.sub.2CO.sub.3 has a purity of at least about
99.999%. In alternate embodiments, the precipitated
Li.sub.2CO.sub.3 has a purity of at least about 99.9999%. In
certain embodiments, the method includes the step of supplying the
concentrated lithium containing solution to a forward osmosis
apparatus, wherein the forward osmosis apparatus is configured to
operate at high pressures, thereby concentrating the
Li.sub.2CO.sub.3.
[0057] In further embodiments, the lithium concentration is
increased by forward osmosis. In such methods, the forward osmosis
apparatus is fed a lithium containing solution substantially free
of silica. In some embodiments, the lithium containing solution
that is fed to the forward osmosis apparatus has at least 1% wt.
lithium chloride. In some embodiments, the lithium containing
solution that is fed to the forward osmosis apparatus has at least
2% wt. lithium chloride. In further embodiments, the lithium
containing solution has no greater than 1000 mg/kg sodium chloride.
In further embodiments, the lithium containing solution has no
greater than 100 mg/kg calcium equivalents.
[0058] In further embodiments for an exemplary forward osmosis
system, the lithium containing solution (e.g., from the silica
management step) is fed to a forward osmosis system using a pump.
From forward osmosis system, water is fed to the permeate. The
concentrated lithium containing solution is fed to the concentrate.
The permeate can then be fed back to the forward osmosis system
using the pump. In some embodiments, where the forward osmosis
system involves a cascade system, the lithium containing solution
is fed to a first forward osmosis system using a first pump. From
first forward osmosis system, first water stream is fed to the
permeate and first concentrated lithium containing solution is fed
to a second forward osmosis system using a second pump. From the
second forward osmosis system, the second water stream is fed to
permeate and the second concentrated lithium containing solution is
fed to third osmosis system using a third pump. From the third
forward osmosis system, the third water stream is fed to permeate
and the third concentrated lithium containing solution is fed to
the concentrate.
[0059] In some embodiments, the present disclosure relates to
processes for producing lithium hydroxide and lithium carbonate
from a lithium salt-containing brine. In some embodiments, the
processes include a step that concentrates lithium via a sorbent
that allows for selective lithium retention and recovery, and
further steps that concentrate the recovered lithium product via
forward osmosis. In some embodiments, the present methods include
the preparation and recovery of lithium carbonate from solutions
that include, in addition to lithium, other various monovalent,
divalent, and multivalent cations (e.g., potassium, sodium,
calcium, barium, magnesium, manganese, etc.), as well as various
monovalent, divalent, and multivalent anions (e.g., sulfate,
chloride, phosphate, etc.)
[0060] FIG. 4 shows a flow chart of a method for producing lithium
hydroxide from a geothermal brine according to one embodiment. The
method 100 generally includes processing a lithium salt containing
brine, such as for example, a geothermal brine, in the following
steps: a silica management step 110, a lithium capture step 120
(lithium salt extraction step), an optional concentration of
lithium containing solution step 130, an electrochemical production
of lithium hydroxide step 140, an evaporation/crystallization step
150, and a lithium hydroxide isolation and drying step 160. The
term "lithium" as used herein refers to ionic forms of lithium and
as such will include, for example, lithium salts such as lithium
halides, lithium sulfates, and lithium nitrates, or some
combination thereof. In some embodiments, the lithium salt is
lithium chloride.
[0061] FIG. 5 shows a flow chart of a method for producing lithium
carbonate from a geothermal brine according to one embodiment. The
method 200 for producing lithium carbonate generally includes a
step of processing a lithium salt containing brine, such as for
example, a geothermal brine, in the following steps: silica
management step 210, lithium capture step 220 (lithium salt
extraction step), electrochemical production of lithium hydroxide
step 240, carbonation of lithium hydroxide step 250, and lithium
carbonate isolation step 260. In this method 200, lithium hydroxide
is converted to lithium carbonate.
[0062] In some embodiments, after lithium capture step 220, the
method can optionally include concentration of lithium containing
solution step 230. In some versions of method 200, after optional
step 230, the lithium containing solution may be reacted with
sodium carbonate to produce lithium carbonate.
[0063] Referring to FIG. 6, provided is a method 300 for the
isolation and concentration of lithium ions from a brine or other
lithium containing solution, and the optional subsequent production
of lithium carbonate therefrom, according to another embodiment.
The brine is supplied to silica management step 310, wherein silica
is removed from the brine to produce a silica-free brine or lithium
containing solution. After silica management step 310, lithium ions
are removed from the silica-free brine or lithium containing
solution in lithium capture step 320 to form a lithium ion
containing solution. The lithium ion containing solution produced
from lithium capture step 320 is concentrated via forward osmosis
step 330 to produce a concentrated lithium ion containing solution.
After forward osmosis step 330, there can be optional further
concentration of the lithium containing solution, followed by an
optional purification step to remove sodium and potassium before
the solution is fed to electrochemical production of lithium
hydroxide step 340.
[0064] Methods to remove sodium and potassium from lithium chloride
solutions are well known and include those described in: U.S. Pat.
No. 4,920,588; Nakajima, Yasushi et al, "Sodium Selective
Ion-Exchange Properties of Zirconium Phosphate,
HZr.sub.2(PO.sub.4).sub.3, and Its Application for the Removal of
Sodium Ions," Analytical Sciences Vol. 12, December 1996, pp.
935-940; and Sun, Jian-Zhi, "Synthesis and Absorption Properties of
Novel Na Specific Sorbent," Journal of Chilean Chemical Society
v.53(4), 2008 pp. 1682-1683. Additionally, gains in purity of
lithium hydroxide monohydrate can be made by employing a sorbent to
remove potassium and sodium impurities.
[0065] Optionally, the concentrated lithium ion containing solution
from the forward osmosis step 330 can then be fed through
additional process steps to produce lithium hydroxide. In this
optional process, the concentrated lithium ion containing solution
from forward osmosis step 330 is fed to electrochemical production
of lithium hydroxide step 340 to produce a lithium hydroxide
containing solution. The lithium hydroxide containing solution can
optionally be processed in an evaporation/crystallization step 350
to remove water from the lithium hydroxide containing solution to
crystallize at least a portion of the lithium hydroxide. In an
optional lithium hydroxide isolation and drying step 360, the
lithium hydroxide is isolated, recovered, and dried.
[0066] Optionally, the lithium ion containing solution from the
lithium capture step 320 can also be fed to purification of the
lithium ion containing solution step before forward osmosis step
330, or purification of the lithium ion containing solution could
occur after forward osmosis step 330. This optional purification of
the lithium ion containing solution can include removal of divalent
ion impurities. Purification of lithium ion containing solution is
optional because it will be dependent on the lithium ion
concentration from lithium capture step 320. If the lithium ion
containing solution from lithium capture step 320 is sufficiently
pure for feeding to forward osmosis step 330, then the optional
purification will not be necessary.
[0067] Referring to FIG. 7, provided is a method 400 for the
isolation of lithium ions from a brine or other lithium containing
solution and the subsequent production of lithium carbonate
therefrom, according to another embodiment. A brine is supplied to
silica management step 410, wherein silica is removed from the
brine to produce a silica-free brine or lithium containing
solution. The silica-free brine or lithium containing solution is
then processed in lithium capture step 420. In lithium capture step
420, lithium ions are removed from the silica-free brine or lithium
containing solution to obtain a lithium ion containing
solution.
[0068] The lithium ion containing solution obtained from the
lithium capture step 420 may undergo further optional processing to
obtain lithium carbonate. In an optional forward osmosis step 430,
the lithium ion containing solution can be concentrated to produce
a concentrated lithium ion containing solution via forward osmosis.
In an optional electrochemical production of lithium hydroxide step
440, the concentrated lithium ion containing solution is supplied
to an electrochemical cell to produce lithium hydroxide. Then, the
lithium hydroxide can be supplied to carbonation of lithium
hydroxide step 450, where lithium hydroxide is converted to lithium
carbonate. Finally, in lithium carbonate isolation step 460,
lithium carbonate is isolated and recovered.
[0069] Referring to FIG. 8, provided is a multistep process for the
isolation and concentration of lithium ions from a brine or other
lithium containing solution according to one embodiment. A brine is
supplied to a silica management step (not shown), wherein silica is
removed from the brine to produce a silica-free brine or lithium
containing solution 500. The silica-free brine or lithium
containing solution 500 is then supplied to lithium capture step
510. In lithium capture step 510, lithium ions are removed from the
silica-free brine or lithium containing solution 500 to form a
lithium ion containing solution 520. The lithium ion containing
solution 520 from lithium capture step 510 is then concentrated in
forward osmosis step 530 to produce a concentrated lithium ion
containing solution 540. The forward osmosis permeate (line 505),
which essentially comprises water, is recycled back to lithium
extraction as the condensate stream (line 590) produced by the
concentration of lithium chloride due to the evaporation of water.
Line 600 represents the concentrated lithium chloride stream.
[0070] The concentrated lithium ion containing solution 540 can
optionally undergo further processing. In an optional
electrochemical production of lithium hydroxide step, the
concentrated lithium ion containing solution 540 is supplied to an
electrochemical cell to produce lithium hydroxide. The lithium
hydroxide can be supplied to an optional carbonation of lithium
hydroxide step where lithium hydroxide is converted to lithium
carbonate. In an optional lithium carbonation isolation step,
lithium carbonate is isolated and recovered. The lithium ion
containing solution from the lithium capture step can also be fed
to an optional purification of lithium ion containing solution step
before a forward osmosis step 530 (not shown), or the purification
of lithium ion containing solution step 550 could occur after the
forward osmosis step 530.
[0071] This optional purification of lithium ion containing
solution step 550 can include removal of divalent ion impurities
580. Purification of lithium ion containing solution is optional
because it will be dependent on the lithium ion concentration from
the lithium capture step 510. If the lithium ion containing
solution 520 from lithium capture step 510 is sufficiently pure for
feeding to the forward osmosis step 530, then the optional
purification step 550 will not be necessary. After the optional
purification step 550, the purified lithium ion containing solution
560 can undergo optional further concentration of lithium
containing solution 570, followed by an optional purification step
to remove sodium and potassium before the solution is fed to
electrochemical production of lithium hydroxide.
[0072] Referring to FIG. 9, in one embodiment of the present
method, lithium salt containing solution 610 is provided. As noted
above, lithium salt containing solution 610 can be obtained from a
variety of sources, including geothermal brines. The lithium salt
containing solution is supplied to silica management process 612,
which operates to significantly reduce the amount of silica that
may be present in lithium salt containing solution 610, such that
silicate precipitate 616 and silica-lean lithium salt containing
solution 614 are produced. Preferably, after silica management
process 612, the silica concentration in silica-lean lithium salt
containing solution 614 is less than about 150 ppm, more preferably
the concentration is less than about 100 ppm, even more preferably
the concentration is less than about 50 ppm, and even more
preferably the concentration is less than about 25 ppm. In certain
embodiments, the concentration of silica in silica-lean lithium
salt containing solution 614 is less than about 20 ppm, less than
about 10 ppm, or even less than about 5 ppm. It is understood that
silica management process 612 may be omitted or replaced from the
process for brines that do not include silica, or brines that have
a substantially low initial silica concentration.
[0073] In certain embodiments, silica management process 612 can
include the step of contacting lithium salt containing solution 610
with activated alumina to remove at least a portion of the silica
present. Alumina that includes silica bound thereto can be
regenerated by contacting the alumina with sodium hydroxide.
Alternatively, the lithium salt containing solution can be
contacted with aluminum chloride, which is converted to aluminum
hydroxide when brought into contact with the brine, and can be used
to precipitate silica present in the lithium salt containing
stream. In a further embodiment, iron (II) that may be present in
certain lithium containing brines can be oxidized with an oxidant,
such as air, hypochlorite, hydrogen peroxide, oxygen, ozone, or a
like oxidizing agent, to generate iron (III) chloride, which after
adjustment of the pH to above about 5, from an initial pH of about
2.5 to 3.5, will precipitate ferric hydroxide. The ferric hydroxide
can adsorb silica from the lithium containing brine. In a preferred
embodiment, the pH is adjusted to from about 5 to 6 to induce
precipitation of silica and iron. In alternate embodiments, the pH
is adjusted to above at least about 4.5 to induce precipitation of
silica and iron. In certain embodiments, it is preferred the pH is
not increased above about 6, to prevent the precipitation of other
ionic species present in the lithium containing brine. In yet
another embodiment, iron (II) can be added to the lithium chloride
containing solution and oxidized by known means to iron (III), for
example, by contacting the iron (II) with an oxidant, such as air,
oxygen, ozone, hypochlorite, hydrogen peroxide, or other suitable
oxidizing agent. Contacting silica present in the lithium chloride
containing solution with the iron (III) compound forms a
precipitate when the pH is adjusted to between about 4.5 and 6 with
the addition of lime or similar base. In a preferred embodiment,
the pH is adjusted to from about 5 to about 6. In alternate
embodiments, the pH must be adjusted to above at least about 4.5
for the silica and iron to precipitate. In certain embodiments, it
is preferred the pH is not increased above about 6, to prevent the
precipitation of other ionic species.
[0074] In addition, silica management process 612 can include any
known means for removing a portion of the silica present in the
feed stream, while at the same time maintaining the initial
concentration of lithium. In one embodiment, lithium chloride
containing solution 610 can be contacted with aluminum chloride,
iron chloride, aluminum hydroxide, or the like, to form a
precipitate with the silicon dioxide. Contacting can be facilitated
by known means, such as a mixing device. Solid silica precipitate
616 removed from lithium chloride containing solution 610 can be
collected and removed from the mixing device (or other device), by
known means, such as screening or filtering, to yield lithium
chloride containing stream 614 that is substantially free of
silica.
[0075] Various membranes can be used to selectively remove specific
undesired ions from lithium containing solution 614.
[0076] Silica-lean lithium chloride containing stream 614, which is
substantially free of silica (measured as SiO.sub.2), can be
supplied to lithium capture (or lithium extraction) step 618. In
certain embodiments, silica-lean lithium chloride containing stream
614 can be supplied to lithium capture process 618 that includes at
least one intercalated lithium sorbent column, which can be
configured to absorb and isolate lithium chloride from the
silica-lean lithium chloride containing solution, while at the same
time allowing other ions, such as calcium, magnesium, and/or
sodium, or the like, to pass with waste water stream 622, through
the use of a selective molecular sieve, membrane, or other like
materials. In embodiments that include more than one intercalated
lithium sorbent column, the bulk of the lithium can be removed in
the first intercalated lithium sorbent column, with any subsequent
"polishing" intercalated lithium sorbent columns being used to
minimize overall lithium loss during the recovery process.
[0077] In certain embodiments, the intercalated lithium sorbent
column can be operated as follows. In some embodiments, the lithium
alumina intercalate particles have an average diameter of less than
800 .mu.m. In some embodiments, the lithium alumina intercalate
particles have an average diameter of less than 700 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of less than 600 .mu.m. In some embodiments, the
lithium alumina intercalate particles have an average diameter of
less than 500 .mu.m. Lithium alumina intercalate particles having
an average diameter of less than 400 .mu.m. In some embodiments,
the lithium alumina intercalate particles have an average diameter
of less than 300 .mu.m. In some embodiments, the lithium alumina
intercalate particles have an average diameter of less than 200
.mu.m. In some embodiments, the lithium alumina intercalate
particles have an average diameter of less than 100 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 100 and 150 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 150 and 200 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 200 and 250 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 250 and 300 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 300 and 350 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 350 and 400 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 400 and 450 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 450 and 500 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 500 and 550 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 550 and 600 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 600 and 650 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 650 and 700 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 700 and 750 .mu.m. In some
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 750 and 800 .mu.m. In certain
embodiments, the lithium alumina intercalate particles have an
average diameter of between about 200 and 800 .mu.m. Alternatively,
lithium alumina intercalate particles have an average diameter of
between about 300 and 500 .mu.m, alternatively between about 400
and 700 .mu.m, alternatively between about 350 and 650 .mu.m.
[0078] In some embodiments, the lithium alumina intercalate
particles can be added to a column, having a particle size of less
than about 400 microns. The column may be jacketed, insulated or
may include means to provide heating or cooling to the column. The
column may include a method of distributing liquid and support for
the extraction media and can include fritted ends having a pore
size of between approximately 25 and 50 .mu.m. although other like
means, such as supports of glass wool or perforated plates, and
fractal fluid distributors, can also be used instead of fritted
ends. In some embodiments, the operating temperature of the column
can be maintained at a temperature that is greater than room
temperature (20.degree. C.), and is preferably maintained at a
temperature above about 70.degree. C., more preferably from about
95.degree. C. to about 110.degree. C.
[0079] The column is maintained wet and is unloaded before first
use by circulating at least about 1 bed volume, preferably about 2
bed volumes, of deionized strip water 20 that includes
approximately 1000 ppm lithium chloride (or other lithium salt), at
a flow rate of between approximately 1 and 4 bed volumes/hour,
preferably between about 1.5 and 2.5 bed volumes/hour. The column
is then contacted with approximately one bed volume of saturated
sodium chloride solution containing approximately 200 ppm lithium
chloride and is then operated.
[0080] In some embodiments, during loading of the column (i.e.,
during the step of capturing desired lithium salt), high ionic
strength solution 614 containing lithium chloride (or other lithium
salt) is supplied to lithium capture process 618 and the lithium
concentration of the effluent at waste water stream 622 is measured
to determine the point at which the column becomes saturated with
the lithium chloride. During the lithium ion capture step, the
lithium concentration at waste water stream 622 remains fairly
constant and relatively low, for example, approximately from 0 to
100 ppm. At this point, the lithium capture process 618 reaches or
nears the point of saturation with lithium ions, however, the
concentration of the lithium in the effluent increases, thus
indicating that the column has either little or no capacity for
additional lithium ions. Upon reaching this point of saturation,
flow of the solution that includes lithium chloride to lithium
capture process 618 is stopped, and the column is flushed with
between about 1 and 5 bed volumes of deionized water, preferably
between about 1 and 2.5 bed volumes, and most preferably between
about 1 and 1.5 bed volumes, to produce a lithium chloride-rich
stream 624. It is understood that the apparatus can include various
valves and control devices for controlling the flow of the lithium
containing solution or the strip solution to the column.
[0081] In certain embodiments, after loading the column, but before
collection of the captured lithium chloride (or other lithium
salt), the column may be flushed with about 1 bed volume of a 26%
saturated sodium chloride solution that includes about 200 ppm
lithium chloride.
[0082] After the removal of lithium chloride (or other lithium
salt) from the lithium containing feed stream during lithium
capture process 618, which in some embodiments isolates lithium
chloride, intercalated lithium sorbent columns can be regenerated
and the lithium chloride recovered therefrom. Specifically, at
least about 0.5 equivalents of strip water 620 may be supplied to
column(s) used in lithium capture process 618 to remove absorbed
lithium chloride and produce lithium chloride rich solution 624. In
certain embodiments, between about 1 to 2 equivalents of strip
water 620, or more equivalents, may be used during the regeneration
of the columns. In preferred embodiments, the strip water may
include lithium ions for the regeneration of the columns.
Optionally, low ionic strength liquids, such as alcohols and
water/alcohol mixtures can be used to regenerate the columns. In
general, the amount of water utilized from the lithium chloride
recovery from the column is minimized by recycling the product
streams to maximize lithium content, without affecting the capacity
of the extracting media. In this context, it is noted that strip
solution exiting the column (typically enriched with lithium) is
also referred to herein as eluate.
[0083] Lithium chloride-rich stream 624 may have a lithium
concentration of between about 1% and 6% by weight, preferably
greater than about 1% by weight, more preferably greater than about
3% by weight, based on the total weight of the lithium
chloride-rich stream 624. In alternate embodiments, lithium
chloride-rich stream 624 may have a lithium concentration of
greater than about 0.5% by weight. Lithium chloride-rich stream 624
can undergo lithium concentration 626 by various means including
evaporation, forward osmosis, solvent extraction or a combination
of these processes to produce a concentrated lithium chloride
stream 630 having lithium in the range of 10 wt. % to 42 wt. %,
based on the total weight of the concentrated lithium chloride
stream 630. In preferred embodiments, concentrated lithium chloride
stream 630 has a lithium concentration of at least 20 wt. %, more
preferably 30 wt. %, and still more preferable 42 wt. %, based on
the total weight concentrated lithium chloride stream 630. In the
most cases, the concentration of sodium and potassium in the
concentrated lithium chloride stream 630 are less than 1 wt. % of
stream 630.
[0084] In certain embodiments, lithium chloride-rich stream 624
and/or concentrated lithium chloride stream 630 can optionally
undergo a purification or concentration step prior to being
provided to electrolytic process 632. Optionally, a purification
step can be employed to remove calcium, magnesium, or other
divalent ions such as zinc and manganese that may be present in
lithium chloride (or other lithium salt)-rich stream 624 and/or
concentrated lithium chloride stream 630. Removal of calcium,
magnesium, and/or other alkaline earth metals can be achieved by
known means, such as, by increasing the pH and treating the
solution with ion exchange, preferably using selective chelating
ion exchange resins, or by the addition of a base, such as lime,
sodium hydroxide, lithium hydroxide, or the like, and or by the
addition of lithium carbonate, sodium carbonate, potassium
carbonate, ammonium carbonate, or other suitable carbonate, which
can precipitate magnesium and iron hydroxide, as well as calcium
carbonate. In alternate embodiments, ion exchange means can be
employed to facilitate the removal of calcium, magnesium, and/or
other alkaline earth metals. Other bases, such as sodium hydroxide
and other hydroxides of alkali metals, can also be used. In certain
brines, it may be beneficial to remove boron from the product
stream at this point process by known means, such as by
precipitation, solvent extraction, or ion exchange. Methods for the
isolation and purification of lithium chloride (or other lithium
salt) from brines, including geothermal brines, are known in the
art, for example, as described in U.S. Pat. Nos. 4,036,713 and
5,951,843, each of which is herein incorporated by reference in its
entirety. In some embodiments, such as those focused on removal
magnesium ions, the removal of divalent ions step should occur with
lithium chloride-rich stream 624.
[0085] This optional purification lithium chloride-rich stream 624
and/or concentrated lithium chloride stream 630 can include removal
of sodium and potassium before the concentrated lithium chloride
stream 630 is fed to electrochemical cell 632.
[0086] In certain embodiments, the process can optionally include
one or more filter or separation-purification step(s) prior to the
step of supplying concentrated lithium chloride solution 630 or
brine to electrochemical cell 632.
[0087] Optionally, the process can include steps for increasing the
concentration of the lithium chloride stream. Specifically, lithium
concentration step 626 can be utilized for the removal of a portion
of the water in the lithium chloride stream, for example, by
evaporation, thereby producing a more concentrated lithium chloride
(or other lithium salt) solution 630. Exemplary concentration
methods can include solvent extraction, electrodialysis, steam
evaporation, or solar evaporation. In further embodiments, the
lithium concentration is by forward osmosis. In such methods, the
forward osmosis apparatus is fed lithium chloride-rich stream 624.
In some embodiments, the lithium chloride-rich stream that is fed
to the forward osmosis apparatus has at least 1% wt. lithium
chloride. In some embodiments, the lithium chloride-rich stream
that is fed to the forward osmosis apparatus has at least 2% wt.
lithium chloride. In further embodiments, the lithium chloride-rich
stream has no greater than 1000 mg/kg sodium chloride. In further
embodiments, the lithium chloride-rich stream has no greater than
100 mg/kg calcium equivalents. Calcium equivalents includes
divalent cations, such as calcium, manganese, magnesium, strontium,
and barium. Sodium equivalents include sodium and potassium. In
order to calculate equivalents, the molecular weight of the
component was assessed. For instance, in order to calculate the
calcium equivalent of manganese, the concentration of manganese was
divided by the molecular weight of manganese and then multiplied by
the molecular weight of calcium.
[0088] In further embodiments, the lithium chloride-rich stream has
no greater than 30 mg/kg boron. In further embodiments, the forward
osmosis apparatus is also fed recycle streams from either the strip
water stream from a lithium sorbent column, or from the depleted
brine.
[0089] In further embodiments, the lithium capture process includes
the step of supplying the silica-lean lithium chloride to a lithium
sorbent material for the capture of lithium until the lithium
sorbent material is saturated with lithium to produce a saturated
lithium sorbent material. In some embodiments the lithium sorbent
material is an intercalated lithium sorbent. In further
embodiments, the recovering lithium salt step comprises stripping
the saturated lithium sorbent material with water to produce the
lithium rich stream. In some embodiments, the saturated lithium
sorbent material is stripped with between about 1 to 4 bed volumes
of water. In some embodiments, the saturated lithium sorbent
material is stripped with between about 1 to 3 bed volumes of
water. In some embodiments, the saturated lithium sorbent material
is stripped with between about 1 to 2 bed volumes of water. In some
embodiments, the water is a purified water. In some embodiments,
the water is deionized water. In some embodiments, the water is
recycled from downstream process such as the lithium chloride
concentration step.
[0090] In some embodiments, water 628 removed from the lithium
chloride solution can be recovered, for example by evaporation and
subsequent condensation, and resupplied to intercalated lithium
sorbent column(s) of lithium capture step 618, or can be supplied
to any other step in this or an associated process that requires
the supply of water. Alternatively, water 628 can be supplied to a
geothermal well. In embodiments employing a concentration step,
overall concentration of concentrated lithium chloride-rich
solution 630 can be increased to greater than 25% lithium chloride
by weight, preferably up to about 40% lithium chloride by
weight.
[0091] Concentrated lithium chloride-rich solution 630 can be
supplied to electrochemical cell 632, which includes at least one
anode, one cathode and a permeable membrane, for the
electrochemical preparation of lithium hydroxide. Electrochemical
cells suitable for large scale production are commercially
available from companies, such as, Ineos, DeNora, Chlorine
Engineers, and Asahi Glass, to name a few. Specifically, chloride
ions are oxidized to chlorine at the anode and water is reduced to
hydroxide ions and hydrogen gas at the cathode. Preferably,
concentrated lithium chloride-rich solution 630 is substantially
free of other ions, particularly ions that may interfere with the
electrochemical reaction. Optionally, a lithium chloride-rich
stream can supplied directly to the electrochemical reaction,
without being first being subjected to the silica management and
lithium ion sequestration steps, provided that the lithium
chloride-rich stream is substantially free of non-lithium ions,
particularly non-lithium ions that may interfere with the
electrochemical reaction, for example silica, calcium, and
magnesium. In certain embodiments, the concentration of sodium
and/or potassium ions in concentrated lithium chloride-rich
solution 630 is less than about 5% by weight, preferably less than
about 3% by weight, more preferably still less than 1%. Cations
such as calcium, magnesium, and the like, if at all present,
preferably have a total concentration of less than about 20 ppb by
weight, more preferably less than about 10 ppb by weight, and even
more preferably less than about 5 ppb by weight. Higher
concentrations of the interfering ions does not necessarily
preclude operation of the electrochemical cell, but instead may
reduce the overall life of the cell components, particularly the
membrane and/or the overall effectiveness of the production of
lithium hydroxide solution.
[0092] Similar to that which is noted above with respect to the
presence of non-lithium interfering cations, electrochemical cell
632 preferably has a total non-chloride anion content of less than
about 5% by weight, preferably less than about 3% by weight, and
even more preferably less than about 1% by weight.
[0093] The cathode of electrochemical cell 632 can be any suitable
material, including nickel, catalyzed nickel, stainless steel,
coated stainless steel, mild steel, and the like. Other exemplary
catalysts can include mixed ruthenium and nickel compounds,
platinum and other similar compounds that have low hydrogen over
potential. The total area of the cathode can be adjusted based upon
reactor size and desired production. The catholyte feed to the
electrochemical cell 632 can be any suitable material having
sufficient ions to carry a current. While water may be employed,
and in certain embodiments, the addition of lithium carbonate or
lithium hydroxide to water may be beneficial to the operation of
the cell.
[0094] The anode of electrochemical cell 632 can be any suitable
material, such as titanium mesh coated with ruthenium oxide,
titanium mesh coated with platinum, carbon, or the like.
Preferably, the anode is a dimensionally stable anode, allowing for
reduced power consumption. Dimensionally stable ruthenium-iridium
oxide on titanium or similar corrosion resistant metal anodes are
particularly well-suited for chlorine environments as the titanium
substrate is resistant to corrosion. In some embodiments, the anode
is a dimensionally stable anode selected from much coated with
ruthenium oxide, platinum, or carbon. The total area of the anode
can be adjusted based upon reactor size and desired production. The
anolyte of electrochemical cell 632 can be any suitable material,
including a lithium chloride solution having a concentration of
between of about 1% by weight to saturation, preferably between 5%
and 40% by weight, more preferably between about 10% and 35% by
weight and most preferably between 15 and 25% by weight.
[0095] The materials for construction of electrochemical cell 632
can be any material that is chemically resistant to chlorine,
activated chlorine, oxygenated chlorine species, and other
dissolved species that may exist in brine solutions on the anolyte
side and lithium hydroxide on the cathode side. Exemplary materials
for the construction of electrochemical cell 632 include
polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF),
HALAR (alternating co-polymers of ethylene and
chlorotrifluoroethylene (CTFE)), and other fluorinated or partially
fluorinated materials.
[0096] The membrane of electrochemical cell 632 can be any suitable
semi-permeable cation selective membrane that selectively passes
cations and inhibits the passage of anions. Such membranes are
known in the art. One exemplary membrane is Nafion.RTM. (E.I.
DuPont de Nemours & Co..RTM.), particularly the Nafion.RTM.
300, 400, and 900/9000 series of materials. Other suitable
membranes can be supplied by Flemion.RTM., however any suitable
membrane material can be used provided the material is chemically
resistant to both chlorine and lithium hydroxide. The membrane may
be placed between the anolyte being electrolyzed and the
catholyte.
[0097] During operation of electrochemical cell 632, a current
density of between about 500 and 10,000 A/m.sup.2 can be applied at
a voltage of between about 1.5 and 5 volts. In some embodiments, a
current density of between about 2000 and 7000 A/m.sup.2 is
applied. In further embodiments, a current density of between about
between 2000 and 4000 A/m.sup.2 is applied.
[0098] Electrochemical cell 632 may be operated at a temperature of
between about 60.degree. and 100.degree. C., preferably between
about 70.degree. and 95.degree. C., and more preferably between
about 80.degree. and 90.degree. C. Cell 632 can be operated at
atmospheric pressure, or slightly above atmospheric pressure.
[0099] Operation of electrochemical cell 632 produces lithium
hydroxide in solution, and also evolves chlorine and hydrogen gas
by products, which can be removed from the electrochemical cell via
lines 634 and 636, respectively.
[0100] The current efficiency of electrochemical cell 632 can be
described in several ways, for the production of lithium hydroxide
it is at least about 60%, preferably at least about 70%, more
preferably at least about 80%, more preferably at least about 90%,
more preferably at least about 95%, and even more preferably at up
to about 99.9%. The electrolysis can be operated continually until
the lithium hydroxide content reaches about 17% by weight, at which
time the lithium hydroxide solution may be removed and supplied to
a carbonation reactor. At lithium hydroxide concentrations greater
than about 17% by weight, the lithium hydroxide monohydrate in
solution can begin to precipitate. Electrochemical cell 632 can
also be operated under conditions designed to produce lower
concentration lithium hydroxide solutions and the lower
concentration lithium hydroxide solution can be recycled to and
from the carbonation reactor. In certain embodiments,
electrochemical cell 632 can also include a feed line (not shown)
for supplying water, low concentration lithium hydroxide, low
concentration lithium carbonate, or combinations thereof to the
cell. The preferred range of operating conditions lies between 2
and 1% wt. as lithium hydroxide and most preferably in the range of
3 to 8 wt. %.
[0101] After lithium chloride-rich stream 624 and/or concentrated
lithium chloride stream 630 is processed in the electrochemical
cell 632, lithium hydroxide solution 636 is supplied from
electrochemical cell 632 to carbonation reactor/absorber 638 and
can be contacted with carbon dioxide gas 644, for example, in an
up-flow fashion. Carbonation reactor/absorber 638 can include a
series of trays or other like means that are designed to allow
lithium hydroxide 636 to be supplied to the top of the reactor and
flow in a downward fashion through the reactor, thereby contacting
up-flowing carbon dioxide gas 644, which can be introduced near the
bottom of carbonation reactor/absorber 638. In alternate
embodiments, carbonation reactor/absorber 638 can include various
mixing means designed to facilitate the efficient mixing of liquids
and gases. Optionally, carbonation reactor/absorber 638 can be a
jacketed batch reactor having thermostatic heating. The reaction
produces lithium carbonate solids. The concentration of the lithium
carbonate slurry is preferably at least about 1.5% by weight
lithium carbonate, more preferably at least about 6% by weight
lithium carbonate. Carbon dioxide can be captured and recycled to
carbonation reactor/absorber 638 via line 642.
[0102] In certain embodiments, the lithium carbonate can be
produced by reaction of lithium chloride with sodium carbonate in
water, wherein the mixture is heated, preferably to a temperature
of between about 90.degree. C. and 95.degree. C., with stirring.
The reaction produces solid lithium carbonate and a sodium chloride
solution, wherein the sodium chloride solution can be separated by
filtration from the desired lithium carbonate solids.
[0103] In certain embodiments, the product of the process is a
concentrated solution of lithium chloride, which is produced
according to silica management process 612, lithium capture process
618, and lithium concentration 626. It is preferable that the
solution produced has a concentration of lithium chloride between
30 wt. % and 42 wt. %, preferably about 36 wt. %. That lithium
chloride can be further concentrated to produce crystalline lithium
chloride by known evaporation process in the art.
[0104] Lithium carbonate containing slurry 640 can be supplied to
filter 646, which is operable to separate lithium carbonate
containing slurry 640 into water stream 652, which may optionally
be resupplied to filter 646, and solid lithium carbonate product
650. Filter 646 can, for example, include a series of screens or
filters and water supply 648. Optionally, water can be recycled to
the process via line 652. Optionally, lithium carbonate can be
concentrated from the lithium carbonate containing slurry 640 by
centrifugation or decantation thickening. Water collected during
the separation of the solids from the lithium carbonate containing
slurry 640 via filter 646 can be supplied to the electrochemical
cell 632, or may be recycled to the optional purification steps, or
even added back to silica management 612 as a base to increase the
pH. In certain embodiments, lithium carbonate solid can be retained
on a band or belt filter and supplied to a wash step, wherein hot
water, preferably having a temperature of between about 90.degree.
C. and 95.degree. C. is used to wash the solids. In certain
embodiments, the aqueous solution collected via filter 646 can have
a pH of greater than about 9, most likely having a pH between about
10-12. Alternatively, sufficient acid can be added to the aqueous
solution to achieve a pH of between about 5 and 8.5, and the
acidified water can then be supplied to the intercalated lithium
sorbent column(s). Alternatively, the solution can be returned
directly to the cathode side of the electrolysis cell without prior
neutralization. Still further recycling possibilities include using
the strip water in the regeneration of the ion exchange processes
to purify the lithium chloride stream.
[0105] In some embodiments, the solid lithium carbonate 650 is
supplied to a drying station 654, which can optionally include
heating means, as well as lines for supplying nitrogen or other
inert gases to the drier. Dried lithium carbonate product 656 can
then be collected, packaged and transported for further use.
[0106] Referring now to FIG. 10, an another embodiment for the
production of lithium carbonate is provided. In some embodiments,
lithium chloride stream 730 is provided by the process described
above and as shown in FIG. 9. In other embodiments, a sodium
chloride stream 760 is provided to electrochemical cell 732, which
is as described above. Sodium chloride stream 760 is then subjected
to electrolysis to produce sodium hydroxide stream 762 and chlorine
gas stream 764 and hydrogen gas stream 765. Reaction conditions for
the production of sodium hydroxide by electrolysis of sodium
chloride are known in the art.
[0107] In certain embodiments, the efficiency of the electrolysis
of sodium chloride to produce sodium hydroxide is at least about
70%, alternatively at least about 80%, alternatively at least about
90%, or alternatively at least about 95%. In certain embodiments,
sodium hydroxide solution 762 is produced in at a concentration of
at least about 10% by weight, more preferably at least about 30% by
weight, and most preferably about 32 to 35% by weight.
[0108] Chlorine gas stream 764 and hydrogen gas stream 765 from
electrochemical cell 732 can be combusted and scrubbed with water
to generate hydrochloric acid, which may be used within the
process, or alternately may be purified, compressed, and sold
commercially.
[0109] Sodium hydroxide stream 762 is supplied to carbonation
reactor/absorber 738, wherein the sodium hydroxide stream 762 is
contacted with carbon dioxide steam 744, for example, in an up-flow
fashion. Carbonation reactor/absorber 738 can include a series of
trays, designed to allow sodium hydroxide stream 762 to be supplied
to the top of the reactor and flow in a downward fashion through
the reactor, thereby contacting up flowing carbon dioxide gas 744,
which can be introduced near the bottom of the reactor, to produce
sodium carbonate solution or slurry 766. In alternate embodiments,
carbonation reactor/absorber 738 can include various mixing means
designed to facilitate mixing of liquids and gases. The
concentration of the solution is preferably at least 15% by weight
sodium carbonate, more preferably at least 25% by weight sodium
carbonate. Carbon dioxide can be captured and recycled to
carbonation reactor/absorber 738 via line 742.
[0110] Sodium carbonate solution or slurry 766 is supplied to
reactor 768 wherein the solution is contacted with lithium chloride
solution 730 to produce slurry 770, which includes lithium
carbonate and sodium chloride solution. The step of contacting
sodium carbonate solution 766 and lithium chloride solution 730 in
the reaction vessel can be at a temperature greater than about
60.degree. C., preferably greater than about 80.degree. C., and
even more preferably between about 90.degree. C. and 95.degree. C.
In certain embodiments, reaction vessel 768 can be a stirred tank
reactor. Alternatively, reaction vessel 768 can be a standard
crystallizer. In some embodiments, lithium carbonate is present as
a precipitate, while sodium chloride remains in aqueous
solution.
[0111] Slurry 770, which includes solid lithium carbonate and
aqueous sodium chloride, is supplied to separator 772, which can
include various means for the separation of solids from liquids
including, for example, centrifuge, settling tank, filters,
screens, and the like, to produce lithium carbonate product stream
774 and sodium chloride brine solution 776. In order to attain
improved product quality, the lithium carbonate can be treated to
remove sodium, potassium, and/or chloride ions trapped in the
interstitial space of the lithium carbonate precipitate, such as by
washing with water, preferably hot water, or by like means. In
certain embodiments, separator 772 can be a band filter or rotary
drum, and can optionally be fed through a counter current wash
system for the removal of residual sodium chloride. Separator 772
can also include water inlet 778 to provide water for the washing
of the separated solid lithium carbonate. Separator 772 can also
include means for drying and/or the removal of water from the solid
lithium carbonate, including for example, centrifuge, heaters,
blowers, presses, and the like. Separator 772 can include a vacuum
filter for removal of water. In certain embodiments, it is
desirable to optimize the washing step to both maximize purity of
the lithium carbonate while minimizing the amount of water used for
washing. Sodium chloride solution 776 can be recycled to
electrochemical cell 732 for electrolysis. Lithium carbonate
product 774 can have a moisture content of less than about 5% by
weight, preferably less than about 2% by weight, and even more
preferably less than about 0.5% by weight.
[0112] The brine solution 776 from separator 772 can include sodium
chloride and lithium carbonate. Generally, depending upon the
amount of water utilized in the process and during the wash
process, the ratio of sodium chloride to lithium carbonate is at
least about 20:1, more preferably at least about 25:1, and even
more preferably at least 30:1. In certain embodiments, the ratio of
sodium chloride to lithium carbonate in the brine solution can be
about 35:1.
[0113] In certain embodiments, brine solution 776 can be acidified
with hydrochloric acid (not shown) to a pH of less than about 4,
preferably about 3, and recycled to electrochemical cell 732. The
hydrochloric acid can be supplied from electrochemical cell 732.
Such lithium carbonate production method is advantageous because
the process eliminates, or nearly eliminates, the production of
waste products. Specifically, in certain embodiments, the recycle
of unused metal salts, for example sodium chloride, and carbon
dioxide, the overall yield can be quantitative or nearly
quantitative. Brine solution 776, if required, can be subjected to
purification to achieve the desired specifications for sodium
chloride anolyte feed to the electrochemical cell 732. As with the
process described in detail above in FIG. 9, in certain
embodiments, lithium chloride-rich stream 724 and/or concentrated
lithium chloride stream 30 can optionally undergo a purification or
concentration step prior to being provided to electrochemical cell
732.
[0114] Referring now to FIG. 11 another alternate embodiment for
the production of lithium carbonate is provided. The method is a
single step process wherein sodium carbonate is produced and
reacted with recovered lithium chloride, however may require
additional input and produces a waste lithium chloride stream that
may include small amounts of lithium carbonate entrained
therein.
[0115] A lithium chloride stream is provided as described above. In
some embodiments, sodium chloride stream 860 is provided to
electrochemical cell 832. Sodium chloride stream 860 is subjected
to electrolysis to produce sodium hydroxide stream 862, chlorine
gas stream 864 and hydrogen gas stream 865, respectively.
[0116] Sodium hydroxide stream 862 is supplied to mixer 880,
wherein the sodium hydroxide stream is combined and mixed with
lithium chloride stream 830. Mixing of sodium hydroxide stream 862
and lithium chloride stream 830 can be done by known means, such as
by agitators or mixers, with ultrasonic waves, or by the like.
Mixer 880 produces mixed stream 882, which includes sodium
hydroxide and lithium chloride in aqueous solution. In certain
embodiments, it may be preferred that lithium chloride stream 830
has a concentration of lithium chloride of at least about 20% by
weight, more preferably at least about 28% by weight, and even more
preferably about 42% by weight. Similarly, in certain embodiments,
it may be preferred that sodium hydroxide stream 862 has a
concentration of sodium hydroxide of at least about 15% by weight,
more preferably at least about 25% by weight, and even more
preferably about 35% by weight.
[0117] Mixed stream 882 is then supplied to carbonation
reactor/absorber 884, which can include a series of trays, designed
to allow the mixed stream, which includes lithium chloride and
sodium hydroxide, to be supplied to the top of the reactor and flow
in a downward fashion through the reactor, thereby allowing the
mixed stream to sufficiently contact up-flowing carbon dioxide gas
844, which can be introduced near the bottom of the reactor, to
produce a lithium carbonate slurry 890. Preferably, carbonation
reactor/absorber 884 is maintained at a temperature of between
about 90.degree. C. and 100.degree. C. In alternate embodiments,
carbonation reactor/absorber 884 can include various mixing means
designed to facilitate mixing of liquids and gases. The
concentration of the lithium carbonate, e.g., in stream 890, is
preferably at least 4% by weight, more preferably at least 8% by
weight lithium carbonate. Carbon dioxide can be recycled to
carbonation reactor/absorber 884 via line 842.
[0118] Lithium carbonate solution 890 is supplied to separator 892
wherein solid lithium carbonate is predicated out via line 894. A
solution that includes sodium chloride and possibly a small amount
of lithium carbonate is produced as stream 896. Sodium carbonate
solution 890, which includes solid lithium carbonate and aqueous
sodium chloride, is supplied to separator means 892, which can
include various means for the separation of solids from liquids
including, for example, centrifuge, settling tank, filters,
screens, and the like. Separator means 892 can also include water
inlets and outlets (not shown) for the washing of the separated
solid lithium carbonate. Separator 892 can also include means for
drying and/or the removal of water from the solid lithium
carbonate, including for example, centrifuge, heaters, blowers,
presses, and the like. A solid sodium carbonate product is
collected via line 894. Optionally, a portion of sodium chloride
stream 896 can be recycled to electrochemical cell 832. Optionally,
the sodium chloride solution can be recycled to the washing step of
the lithium extraction media. In certain embodiments, the sodium
chloride required for the process can be generated by the selective
crystallization of sodium chloride from the geothermal, Smackover,
or other brine.
[0119] In certain embodiments, contemplated processes may include
means for the neutralization of any lithium carbonate that is
included in the sodium chloride solution, such as by neutralizing
the solution by adding an effective amount of hydrochloric acid or
like acid. In embodiments wherein the lithium carbonate can be
effectively removed, the solution can be recycled to the
electrochemical cell, however, any lithium carbonate included
therein may cause problems with the performance of the
electrochemical cell.
[0120] In further embodiments for an exemplary forward osmosis
system, the lithium containing solution from the lithium capture
process is fed to a forward osmosis system using a pump. From
forward osmosis system, water is fed to the permeate. The
concentrated lithium containing stream is fed to the concentrate.
The permeate can then be fed back to the forward osmosis system
using the pump. Additionally, the concentrated lithium containing
stream can be fed back through the lithium capture process, and to
further processing using the forward osmosis system. Where the
forward osmosis system involves a cascade system, the lithium
containing solution from the lithium capture process is fed to a
first forward osmosis system using a first pump. From first forward
osmosis system, first water stream is fed to the permeate and first
concentrated lithium containing stream is fed to a second forward
osmosis system using a second pump. From the second forward osmosis
system, the second water stream is fed to permeate and the second
concentrated lithium containing stream is fed to third osmosis
system using a third pump. From the third forward osmosis system,
the third water stream is fed to permeate and the third
concentrated lithium containing stream is fed to the concentrate.
Various embodiments of the present invention can include any number
of forward osmosis systems in cascade function. In some
embodiments, there are three forward osmosis systems in cascade. In
some embodiments, there are four forward osmosis systems in
cascade. In some embodiments, there are five forward osmosis
systems in cascade. In some embodiments, there are six forward
osmosis systems in cascade. In some embodiments, there are seven
forward osmosis systems in cascade. In some embodiments, there are
eight forward osmosis systems in cascade. In some embodiments,
there are nine forward osmosis systems in cascade. In some
embodiments, there are ten forward osmosis systems in cascade.
[0121] A person of ordinary skill in the art will understand how to
select appropriate forward osmosis membranes to use in the present
invention. Forward osmosis membranes can include those supplied by
Dow Chemical (Filmtec), Hydranautics, Osmonics (Desal) and Toray.
Suitable forward osmosis membranes include those that are typically
spiral wound. Suitable forward osmosis membranes are also described
in Table 1. The list provided in Table 1 is provided by way of
example and is not intended to limit the forward osmosis membranes
used in embodiments of the present invention. Potential suppliers
along with membrane descriptions are given in Table 1 below. Less
preferred membranes are made of cellulose triacetate due to low
flux.
TABLE-US-00001 TABLE 1 Membrane manufacturer, type and maximum
pressure rating. Salt Rejection TYPE Membranes Material Max
pressure (NaCl) FILMTEC SW30-2540 Polyamide Thin- 68.9 bar 99.4%
SW30-4021 Film Composite 68.9 bar 99.4% SW30-4040 68.9 bar 99.4%
SW30HRLE-4040 82.7 bar 99.75% SW30HR-380 68.9 bar 99.70% SW30-380
68.9 bar 99.40% Extra low energy SW30XLE-400i 82.7 bar 99.70%
SW30HRLE-400i 82.7 bar 99.75% ultra low energy SW30ULE-400i 82.7
bar 99.70% Boron removal SW30XHR-400i 82.7 bar 99.75% GE-Osmonics
AD 2540 FF 68.9 bar DESAL AD 4040 FF 82.7 bar 99.6% AD 8040F 82.7
bar 99.6% TORAY TM810 Cross-linked 68.9 bar 99.75% TM820-370 Fully
aromatic 68.9 bar 99.75% TM820-400 polyamide 68.9 bar 99.75% TM810L
68.9 bar 99.70% TM820L-370 68.9 bar 99.70% TM820L-400 68.9 bar
99.70% TM820H-370 82.7 bar 99.75% Nitto Denko SU810 Cross-linked
68.9 bar 99.75% SU820 Fully aromatic 68.9 bar 99.75% SU820-FA
polyamide 68.9 bar 99.75% SU820L 68.9 bar 99.75% SU-820 BCM 98 bar
99.7% HYDRANAUTICS SWC1-4040 Composite 6.89 bar 99.5% SWC3+
Polyamide 82.7 bar 99.8% SWC4+ 82.7 bar 99.8% SWC5-LD 82.7 bar
99.8%
[0122] In further embodiments, the lithium capture process is
optimized by a series of recycle steps associated with the lithium
capture process. For instance, a portion of the strip can be
recycled. Additionally, a portion of the load can be recycled. The
intention of the recycling is to improve the product lithium
chloride purity and maximize its concentration prior to
purification or concentration steps.
EXAMPLES
Example 1
[0123] In a laboratory set-up of an embodiment, two peristaltic
pumps were set up to direct the flow of a feed solution and a draw
solution through a forward osmosis unit. The selectively permeable
membrane used was an AD membrane element from GE Osmonics. The feed
solution was a lithium containing solution with the following
composition: 2 weight % LiCl and 0.1 weight % NaCl. The draw
solution was concentrated brine solution with the following
composition: 20% NaCl. Experimental conditions include but are not
limited to counter current flow rate of 79-85 mL/min and a
temperature of both feed and draw solutions were at room
temperature.
[0124] Table 2 below describes the experimental flow, volume,
lithium chloride concentration, and sodium chloride concentration
in the feed and draw solutions. FIG. 3 is a graphical
representation of the concentration of lithium chloride exiting the
forward osmosis unit.
TABLE-US-00002 FEED 2.11 0.11 DRAW 0.00 18.38 FEED DRAW Flow Flow
Time Time Volume Rate Volume Rate (min) (s) (mL) (mL/min) Sample %
LiCl % NaCl Time (s) (mL) (mL/min) Sample % LiCl % NaCl 10 29.6 39
79 C1 2.18 0.15 31 43 83 P1 0.01 18.56 47 31.2 38.5 74 C2 2.14 0.14
30.1 42.5 85 P2 0 17.69 52 30.9 43 83 C3 2.16 0.13 30.7 45 88 P3
0.01 18.02 59 30.6 42 82 C4 2.20 0.15 30.6 42.5 83 P4 0.01 19.17 66
32.3 45 84 C5 2.16 0.13 31.2 44 85 P5 0 18.10 FINAL 2.17 0.14 0
18.31
Example 2
Further Optimization of Lithium Chloride Capture Step for Feed to
Forward Osmosis
[0125] The following experiments were conducted to determine an
optimum process for the lithium capture step, and to provide feed
for subsequent forward osmosis process.
[0126] A standard lab column measuring 2.6 cm.times.53 cm was
prepared with a sorbent made as described in U.S. Pat. No.
8,901,032. The resulting sorbent was screened to a mean particle
size of between about 300 and 500 microns and was then slurried
with deionized water and poured into the column and backwashed with
saturated salt solution to remove fines. The column was loaded with
Li from a geothermal brine.
[0127] The geothermal brine was a Hudson Ranch geothermal brine
that had been subjected to a silica management process. The silica
management process was a continuous process for the management of
silica. The silica management system included three stirred
reaction vessels provided in series. To the first reaction vessel a
geothermal brine was provided at a rate of about 6 gpm.
Approximately 30 cfm of air was supplied each reactor and was
dispersed through the geothermal brine. After the addition of the
air to the first reaction vessel, the pH dropped to between about
2.3 and 3.5. The brine supplied to each of the three reactors is
maintained at a temperature of about 95.degree. C.
[0128] The geothermal brine from the first reactor was also
supplied to the second reactor. An aqueous calcium hydroxide slurry
that included between about 15 and 25% by weight calcium hydroxide
was supplied to the second reactor at a rate on a wet basis of
about 0.5 lb/min. This raised the pH in the second reactor to
between about 4.8 and 6.5. The brine in the second vessel in
contact with calcium hydroxide slurry was again contacted with air.
The addition of calcium hydroxide slurry initiates the
precipitation of iron (III) hydroxide and iron silicate. The brine
was then supplied from the second vessel to the third reaction
vessel where it was again contacted with air. The air to all
vessels was supplied at a constant rate, of about 30 cfm. Each of
the three reactors included means for stirring to ensure sufficient
mixing of the brine, base and air oxidant. The continuous addition
of air and base to the reaction vessel results in the precipitation
of the iron and silica at rates up to about 0.5 lb/minute,
depending upon the concentration of iron and silica in the
geothermal brine.
[0129] The geothermal brine, including precipitates of iron (III)
hydroxide and iron silicate, was then supplied from the third
reaction vessel to a clarifier. Water was added to the clarifier.
An aqueous flocculant solution of Magnafloc 351, in a concentration
between about 0.005% and 1% by weight, such as about 0.025% by
weight, was supplied to the clarifier vessel at a rate of about
0.01 gpm.
[0130] From the clarifier were produced two streams. First
clarifier product stream included the geothermal brine having a
reduced concentration of silica and iron, which was then fed to the
lithium capture step. Second clarifier product stream included
solid silica-iron waste, as well as some geothermal brine.
[0131] FIG. 17 shows one embodiment of a system 1400 for extracting
lithium in a column from a sorbent with three regenerant solutions.
The system 1400 includes a column 1410, a load tank 1420, a
depleted brine tank 1425, a recycle cut tank 1430, a product cut
tank 1440, and a strip tank 1460. A load (line 1), e.g., a
lithium-containing brine solution, was sent to the column 1410. The
lithium was stripped from load (line 1) in the column 1410 by
treating the column 140 sequentially with three regenerant
solutions, starting with the Recycle Cut (line 2), which was used
to displace the lithium-containing brine solution from the column
1410, followed by the Recycle Strip (line 5 and line 6), which was
used to begin stripping the column and followed finally by a Strip
Solution (line 7) of freshly prepared from DI water with 500 mg/kg
Li added to complete the elution of Li from the column 1410. Each
cycle includes lithium-containing brine solution (line 1), Recycle
Cut (line 2), Recycle Strip (lines 5 and 6), and Strip Solution
(line 7). The feeds and flow rates are shown in Table 3. This was
repeated through at least 50 cycles.
[0132] The Recycle Cut (line 2) from the column 1410 is recycled to
the load tank 1420. The Recycle Cut (line 3) as shown in Table 3 is
defined as the peak area of the strip, where the lithium is the
highest concentration, but also where the impurities such as
sodium, potassium, calcium, manganese and boron are at their
highest. This is recycled and fed into the column 1410 immediately
following the loading step. The depleted brine (line 3) that exits
from the column 1410 can be sent to depleted brine tank 1425.
[0133] The Product Cut (line 4) from the column 1410 is sent to the
product cut tank 1440 for further processing (e.g., forward osmosis
system). The Product Cut (line 4) as shown in Table 3 is the
portion of the strip that is retained (e.g., in the product cut
tank 1440) for processing by the forward osmosis system. In some
aspects, the Product Cut (line 4) should have an average
concentration greater than 1600 mg/kg Li (about 1%) and less than
1000 mg/kg Na and less than 500 mg/kg divalent ions expressed as Ca
and B less than 100 mg/kg and preferably less than 50 mg/kg.
[0134] The Recycle Strip (line 5) from the column 1410 is sent to
the recycle strip tank 1430 and can then be sent as Recycle Strip
(line 6) to the column 1410. In some embodiments, the Recycle Strip
(line 5) and processed in recycle strip tank 1430 and then sent as
a modified Recycle Strip (line 6) to the column 1410. The Recycle
Strip (lines 5 and 6) as shown in Table 3 is defined as that
portion of the Li strip following the Product Cut (line 4), which
has a lithium concentration in the range of 700 to 1500 mg/kg,
which is too low to be forwarded to the product cut tank 1440 or
forward osmosis system. This Recycle Strip (lines 5 and 6) is
recycled to become the feed to produce the product cut as
impurities such as sodium, potassium, calcium, manganese and boron
are at their lowest.
[0135] A Strip Solution (line 7) can be supplied to the column 1410
from a strip tank 1460. The Strip Solution (line 7) can be added to
the load (line 1), the Recycle Strip (line 6), or can be
independently fed to the column 1410. The Strip Solution (line 7)
may comprise freshly prepared from DI water with 500 mg/kg Li added
to complete the elution of Li from the column 1410.
[0136] The Load Recycle (not shown in FIG. 14) as shown in Table 3
is defined as that portion of the Li loading and strip curves which
contains Li at concentrations from 200 up to about 4000 mg/kg where
impurities such as sodium, potassium, calcium manganese and boron
are at concentrations from about 30% of their concentrations in the
feed brine up to their feed brine concentration, which is recycled
back to the feed tank, mixed with the geothermal brine and fed to
the column during the subsequent load step.
TABLE-US-00003 TABLE 3 Feeds and Flow rates to the lithium capture
step. Flow Rate Column Feed BV/Cycle BV Total (BV/hr) Sample #
Column Exit Load 0.4 0.4 12 1 Recycle Strip (geothermal brine) Load
0.4 0.8 12 2 Load Recycle (geothermal brine) Load 14.2 15 12 3-12
Depleted Brine (geothermal brine) Recycle Cut 0.4 15.4 12 13
Depleted Brine Recycle Strip 0.2 15.6 2 14 Depleted Brine Recycle
Strip 0.3 15.9 2 15-16 Load Recycle Recycle Strip 0.2 16.1 2 17
Recycle Cut Strip 0.3 16.4 2 18-20 Recycle Cut Strip 1.0 17.4 2
21-30 Product Cut Strip 0.7 18.1 2 31-37 Recycle Strip
[0137] Table 4 shows the concentrations of select components in the
geothermal brine before the start of each cycle. This brine was
sampled before lithium extraction.
TABLE-US-00004 TABLE 4 Geothermal Brine Feed Component
concentrations (note: this includes some recycling of the recycle
cut). Cycle Li (mg/kg) Na (mg/kg) Ca (mg/kg) B (mg/kg) 52 320 56000
33000 435 53 310 59000 33500 460 54 340 61000 32900 440 55 300
58000 34600 445 56 300 58000 32600 440 57 375 63000 35500 465 58
360 61000 33700 455 59 380 56000 31700 420 60 380 56000 31300 425
61 355 58000 32700 425 62 350 59000 33000 425 63 330 58000 32700
435
[0138] FIG. 12 shows exemplary lithium loading curves for various
cycles. When the lithium concentration is in the range of about 500
to 800 mg/kg it is considered to be the tail fraction. The tail
fraction can be recycled to be the feed for the product cut. The
product cut is the portion of the strip that is retained for
processing by the forward osmosis system. It has an average
concentration of the order of about 1600 mg/kg Li and less than
about 1000 mg/kg Na and less than about 500 mg/kg and preferably
less than 200 divalent ions expressed as calcium equivalents and
boron is less than about 100 mg/kg and preferable less than about
50 mg/kg. The recycle cut is the peak area of the strip, where the
lithium is the highest concentration, but also where the impurities
such as sodium, potassium, calcium, manganese and boron are at
their highest. This is recycled and fed into the column instead of
the wash step described in the example above.
[0139] Table 5 shows the concentrations in the lithium chloride
product cut post lithium extraction for cycles 52 to 63. This
product cut is fed directly to a forward osmosis process, or to a
purification process, then to forward osmosis process.
TABLE-US-00005 TABLE 5 Component concentrations. Cycle LiCl LiCl
NaCl Ca B number (wt %) (mg/kg) (mg/kg) (mg/kg) (mg/kg) 52 1.5%
15,000 268 174 47 53 1.3% 13,000 334 182 29 54 1.4% 14,000 465 176
31 55 1.2% 12,000 293 127 20 56 1.3% 13,000 77 11 26 57 1.2% 12,000
69 92 16 58 1.4% 14,000 528 188 35 59 1.3% 13,000 703 206 32 60
1.6% 16,000 306 180 44 61 1.4% 14,000 145 131 35 62 1.4% 14,000 144
137 39 63 1.2% 12,000 81 109 28
Example 3
Additional Examples for Optimization of Lithium Chloride Capture
Step for Feed to Forward Osmosis
[0140] Conventional/Comparative: A column was loaded with sorbent
produced by methods described in U.S. Pat. No. 8,901,032 B1 to a
depth of 48 cm the column diameter was 2.64 cm. Lithium was
extracted and recovered from the geothermal brine according to the
following sequence. The flow rate of geothermal brine, the (load),
was 60 ml/min and 5.065 liters of geothermal brine were passed
through the column. This was followed by a solution of sodium
chloride (wash) 62 mol/min until 0.3 liters of solution was passed
and finally a strip solution of water containing 500 mg/kg was
passed through the column at a rate of 12 ml/min until 0.91 of
solution had been passed through the column. The input data to the
column is shown in Table 6, the output data in Table 7 and FIG. 13
(Li Concentration at the outlet read primary Y axis for Li, Mn, Zn,
Ba and Zn, read secondary Y axis to read Na, K and Ca) and FIG.
14.
[0141] FIG. 14 illustrates one embodiment in which the area of peak
lithium concentration includes the most concentrated lithium
solution that is extracted from the sorbent. In some embodiments,
however, the area of peak lithium concentration can also include
impurities. For example, the area of peak lithium concentration may
include a large amount of sodium and potentially other impurities
(e.g., calcium and potassium). The area of peak lithium
concentration may have the highest concentration of the lithium,
but also the impurities such as sodium, potassium, calcium,
manganese and boron are at their highest in this area.
[0142] In some embodiments, the process may include recycling a cut
from the area of peak lithium concentration (also referred herein
as "recycle cut") to remove these impurities to produce a purer
lithium solution. The recycle can be taken from the area peak
lithium concentration during the stripping process. By employing
one or more recycles of the peak lithium concentration solution,
the peak lithium concentration can be shifted to a later time in
the strip cycle. Therefore, the process can produce a purer
concentrated lithium stream (see e.g., FIG. 16 "product cut") which
can be fed to the forward osmosis unit.
[0143] For example, comparing FIG. 14 with FIG. 16, the lithium
concentration is significantly higher in FIG. 16 between Bed Volume
(BV) 13 and 14, whereas a similar position in FIG. 14 (roughly
between BV 19.5 and 20.5) has a lower concertation of lithium and
significantly higher concentration of sodium. The high sodium
content prevents the use of forward osmosis on these solutions as
forward osmosis has limits on operating pressures to about 1000 to
2000 psi. The high sodium content results in a higher osmotic
pressure which has to be overcome for the forward osmosis to have
any practical utility. Thus, by utilizing one or more recycle cuts
of the highly concentrated lithium solution as part of the
stripping process (e.g., stripping lithium from the sorbent), the
area of peak lithium concertation can be shifted in the strip cycle
to produce a purer lithium solution with less impurities which can
now be fed to the forward osmosis unit.
TABLE-US-00006 TABLE 6 Flow Rate Flow Rate Cum. 0.28 kg hr.sup.-1
ml min.sup.-1 Volume 1 B Ba Ca Cu K Li Mg Feed Brine 4.32 59.9
5.090 452 38.7 28900 4.8 13400 290 70.9 Feed Wash 5.10 62.0 0.310
<5.0 <1 <5.0 <0.5 32.3 521 <5.0 Feed Strip 0.72 11.9
0.901 <5.0 <1 <5.0 <0.5 <10.0 491 <5.0 0.28 Mn Na
Pb Rb S Si Sr Zn Feed Brine 1030 41100 97.5 235 318 4.38 500 563
Feed Wash <0.5 91100 <2 <10.0 <20.0 <2 <0.5 <1
Feed Strip <0.5 35.9 <2 <10.0 <20.0 <2 <0.5
<1
TABLE-US-00007 TABLE 7 Cum Flow Rate Volume Time min ml min.sup.-1
ml B Ba Ca Cu K Li Mg Mn 2.5 46.0 115 9.25 <10 412 <0.5 265
914 <5.0 60.4 5 60.0 265 6.51 2.69 3780 <0.5 2250 631 <5.0
40.8 10 60.0 565 159 27.4 29200 0.769 15600 20.9 38 403 20 60.0
1165 424 35.9 35300 3.61 19300 <10.0 65.5 1610 30 60.5 1770 443
37.2 36600 5.11 20300 31 67.8 1730 40 60.0 2370 447 37.2 36800 4.88
20500 132 66.8 1700 50 60.0 2970 457 39.5 38800 4.75 21600 229 70.7
1790 55 60.0 3270 456 39.1 38800 4.95 21800 260 70.1 1800 60 60.0
3570 430 36.3 36200 4.21 20200 253 65.1 1700 65 60.0 3870 444 37.8
37800 4.44 21100 274 67.9 1650 70 60.0 4170 425 36.2 36500 4.65
20300 264 65.7 1680 75 60.0 4470 445 38.1 37400 4.13 20900 259 68
1680 80 60.0 4770 402 33.4 34200 3.8 19100 248 60.6 1590 85 62.0
5080 435 34.8 33500 4.86 18500 286 60.9 1550 89 7.8 5111 253 11.6
10200 3.04 5480 449 19.6 512 93 12.3 5160 195 6.45 5140 2.5 2830
396 10.4 333 97 12.1 5209 119 3.16 2200 2.36 1580 371 <5.0 176
101 12.5 5259 86.5 2.22 1350 1.79 980 396 <5.0 124 105 12.8 5310
68.5 1.83 1060 2.34 838 398 <5.0 104 109 12.6 5360 52.2 1.51 852
1.33 500 2370 5.32 167 113 12.4 5410 36.5 <1.0 348 0.674 107
4550 8.08 258 117 12.5 5460 22 <1.0 127 <0.5 62.4 2920
<5.0 205 121 12.5 5510 15.1 <1.0 115 0.51 78.8 2070 <5.0
173 125 12.4 5559 11.1 <1.0 72.4 <0.5 49.9 1580 <5.0 143
129 5.0 5579 9.1 <1.0 64.5 <0.5 46 1370 <5.0 130 133 12.4
5629 7.09 <1.0 57.6 <0.5 40.8 1230 <5.0 111 137 12.5 5679
6.26 <1.0 51.6 <0.5 39 1070 <5.0 101 141 12.5 5729 <5.0
<1.0 47.2 <0.5 34.7 968 <5.0 85.4 145 12.5 5779 <5.0
<1.0 65.5 <0.5 46.8 881 <5.0 72.4 149 12.5 5829 <5.0
<1.0 55.7 <0.5 41.7 866 <5.0 62.8 153 12.5 5879 <5.0
<1.0 49.2 <0.5 34.2 836 <5.0 55 157 12.3 5928 <5.0
<1.0 47.9 <0.5 33.7 816 <5.0 49.1 161 12.4 5977 <5.0
<1.0 39.5 0.562 27.1 783 <5.0 41.3 6005 <5.0 <1.0 35.7
<0.5 24.8 759 <5.0 39.4 Time min Na Pb Rb S Si Sr Zn 2.5 3130
<2.0 <10.0 <2.0 <2.0 6.19 6.6 Load 5 7420 <2.0 16.5
30.7 <2.0 55.5 2.77 10 48300 48.2 175 256 <2.0 404 233 20
55600 97.3 216 308 <2.0 492 713 30 54100 97.3 224 305 <2.0
504 743 40 54300 102 227 303 <2.0 506 731 50 57600 104 243 318
2.49 536 772 55 57800 107 243 318 2.58 536 777 60 53700 94.5 225
296 2.44 500 742 65 56500 101 231 309 2.66 525 748 70 54300 96.9
223 291 2.79 508 729 75 55700 97.7 234 304 2.95 519 710 80 50600
89.7 203 269 2.23 473 689 85 62600 93.1 212 284 2.82 473 650 89
73400 31.6 62.2 85.8 2.06 141 160 Wash 93 85900 18.7 29.8 45
<2.0 71.5 95.5 97 84700 9.47 11.6 21.3 <2.0 30.9 47.7 101
96100 6.2 <10.0 <20.0 <2.0 18.9 32.7 105 104000 5.63
<10.0 <20.0 <2.0 15.2 29.2 109 64100 2.58 <10.0
<20.0 <2.0 12.1 16.3 Product 113 10300 <2.0 <10.0
<20.0 <2.0 4.56 3.13 Cut 117 2920 <2.0 <10.0 <20.0
<2.0 1.9 1.38 121 1710 <2.0 <10.0 <20.0 <2.0 1.76
1.63 125 1140 <2.0 <10.0 <20.0 <2.0 1.13 <1.0 129
1010 <2.0 <10.0 <20.0 <2.0 0.909 <1.0 133 950
<2.0 <10.0 <20.0 <2.0 0.825 <1.0 137 849 <2.0
<10.0 <20.0 <2.0 0.676 <1.0 141 733 <2.0 <10.0
<20.0 <2.0 0.616 <1.0 Recycle 145 768 <2.0 <10.0
<20.0 <2.0 0.838 <1.0 to Strip 149 606 <2.0 <10.0
<20.0 <2.0 0.748 <1.0 Feed 153 537 <2.0 <10.0
<20.0 <2.0 0.636 <1.0 157 485 <2.0 <10.0 <20.0
<2.0 0.628 <1.0 161 436 <2.0 <10.0 <20.0 <2.0
<0.5 <1.0 405 <2.0 <10.0 <20.0 <2.0 <0.5
<1.0
[0144] Inventive Methods suitable for Combination with Forward
Osmosis: A column was loaded with sorbent produced by methods
described in U.S. Pat. No. 8,901,032 B1 to a depth of 19.3 inches
the column diameter was 1 inch. Lithium was extracted and recovered
from the geothermal brine according to the following sequence. The
flow rate of geothermal brine, the (load), was 50 ml/min and 3.058
liters of geothermal brine were passed through the column.
Subsequently, recycle cut was fed to the column according to flow
diagram in FIG. 8 at the same flow rate for a total of 0.1 liters.
Subsequently, recycle strip was fed to the column at 11 ml/min to a
total of 0.261 and finally feed strip solution was fed to the
column. The results of the extraction and resulting strip procedure
are shown in FIG. 15 (Li Concentration at the outlet read primary Y
axis for Li, Mn, Zn, Ba and Zn, read secondary Y axis to read Na, K
and Ca) and FIG. 16 along with Table 8.
TABLE-US-00008 TABLE 8 Flow Rate/ Cumulative Mg ml min- Volume/l BV
B Ba Ca Cd Cu Fe K Li mg/kg Feed 50.1 3.058 11.4 405 32 34700 3 4
<1.0 18400 259 63 Brine Feed 50.1 0.100 0.4 229 3 1470 <0.5
<0.5 <1.0 613 2750 9 Recycle Cut Feed 10.9 0.261 1.0 29
<1.0 84 <0.5 <0.5 <1.0 40 979 <5.0 Recycle Strip
Feed Strip 9.2 0.519 1.9 <5.0 <1.0 <5.0 <0.5 <0.5
<1.0 <10.0 519 <5.0 3.937 14.7 16 58 Depleted 1.970 7.3
356 30 33000 3 4 <1.0 17500 Brine 144 59 Lag Brine 1.259 4.7 381
29 31800 3 5 <1.0 16900 1400 15 Recycle 0.155 0.6 164 5 4880
<0.5 1 <1.0 2590 Brine 3000 12 Recycle 0.110 0.4 268 4 1850
<0.5 <0.5 <1.0 841 Cut 1800 <5.0 Product 0.327 1.2 102
<1.0 367 <0.5 <0.5 <1.0 149 Cut 1100 <5.0 Recycle
0.219 0.8 40 <1.0 108 <0.5 <0.5 <1.0 47 Strip Mn Na Pb
Rb S Si Sr Zn Feed 1690 57600 82 215 263 3 481 656 Brine Feed 640
1870 <2.0 <10.0 <20.0 <2.0 22 6 Recycle Cut Feed 85 114
<2.0 <10.0 <20.0 <2.0 1 <1.0 Recycle Strip Feed
Strip <0.5 <10.0 <2.0 <10.0 <20.0 <2.0 <0.5
<1.0 Depleted 1530 53100 82 204 245 <2.0 457 648 Brine Lag
Brine 1580 53400 78 198 237 <2.0 444 603 Recycle 551 7420 7 20
35 <2.0 74 54 Brine Recycle 721 2360 <2.0 <10.0 <20.0
<2.0 30 9 Cut Product 241 467 <2.0 <10.0 <20.0 <2.0
6 2 Cut Recycle 114 128 <2.0 <10.0 <20.0 <2.0 1 <1.0
Strip
[0145] Note that the use of a sodium chloride wash is not
economically and results in a solution with too high a sodium
content. Without the wash then the lithium chloride stream is
contaminated with Na, Ca and K at too high an average
concentration. Indeed, it should be appreciated that a very
significant reduction in sodium ions is observed, while ions such
as Mn and Ca are similar in concentration (which can be purified by
known chemical means such as pH adjustment with lithium hydroxide
and carbonate and ion exchange to remove impurities). In the
comparative example, the concentration sodium ions is 16 g/kg or
0.7 Molal where as in the Li concentration is 2.6 g/kg equivalent
to 0.36 Molal. It is shown that the osmotic pressure will be higher
under these conditions and that the high sodium content will
prevent satisfactory concentration by forward osmosis. Furthermore
there is a significant consumption of salt in the salt wash
methodology. In contrast, in the inventive method the amount of
sodium in the product cut is 0.46 g/kg 0.02 Molal against the 1.8
g/kg for Li which is 0.25 Molal. Hence the osmotic pressure is
almost entirely a function of the Li content and not the sodium
content and it will therefore be economically feasible to
concentrate the LiCl from 0.5% to approximately 5 wt. % LiCl. Table
9 provides a typical product composition for the comparative method
(example 101) and the inventive method (example 102).
TABLE-US-00009 TABLE 9 Product Mg Cut B Ba Ca Cd Cu Fe K Li mg/kg
Mn Na Pb Rb S Si Sr Zn Example 17 1 299 1 159 2580 6 183 16123 2 10
20 2 4 5 101 Example 102 <1.0 367 <0.5 <0.5 <1.0 149
1800 <5.0 241 467 <2.0 <10.0 <20.0 <2.0 6 2 102
[0146] Among other benefits, it should therefore be appreciated
that recycling of a lithium rich fraction as described above has
numerous benefits, particularly where the resultant lithium
solution will be subjected to a downstream forward osmosis
concentration step. Among other things, conventional elution
methods that will take advantage of the lithium peak area (and even
areas trailing the peak) as illustrated in FIG. 14 will necessarily
be also rich in sodium. Therefore, high lithium recovery is
associated with high sodium concentrations. Unfortunately, such
high sodium concentrations will adversely affect forward osmosis as
sodium substantially contributes to the osmotic pressure. As can be
seen from the table above, sodium ions are in six-fold excess over
lithium ions using conventional elution. In contrast, when the
product (or fractions at least partially overlapping with the
product cut) is recycled to the sorbent, the ionic strength is
still sufficient to maintain (and even additionally bind) lithium
on the sorbent, in large part due to elevated lithium concentration
relative to sodium. Viewed from another perspective, ionic strength
is gained by an increase in lithium at concomitant decrease of
sodium, which favorably affects the product composition upon
elution with a suitable eluent low or depleted in sodium. As can
also be taken from the table above, the lithium concentration is
now approximately four-fold over the sodium concentration.
Therefore, partial recycle as presented above allows for an
increase in ratio between lithium and undesirable other cations
(and especially sodium) while maintaining overall lithium
recovery.
[0147] The methods described herein are suitable for the recovery
of lithium from brines or solutions having low or high lithium
concentrations, in addition to brines or solutions that include
significant concentrations of other ions, including multivalent
ions.
[0148] As is understood in the art, not all equipment or
apparatuses are shown in the figures. For example, one of skill in
the art would recognize that various holding tanks and/or pumps may
be employed in the present method.
[0149] The singular forms "a", "an" and "the" include plural
referents, unless the context clearly dictates otherwise.
[0150] Optional or optionally means that the subsequently described
event or circumstances may or may not occur. The description
includes instances where the event or circumstance occurs and
instances where it does not occur.
[0151] Ranges may be expressed herein as from about one particular
value, and/or to about another particular value. When such a range
is expressed, it is to be understood that another embodiment is
from the one particular value and/or to the other particular value,
along with all combinations within said range.
[0152] Throughout this application, where patents or publications
are referenced, the disclosures of these references in their
entireties are intended to be incorporated by reference into this
application, in order to more fully describe the state of the art
to which the invention pertains, except when these reference
contradict the statements made herein.
[0153] As used herein, recitation of the term about and
approximately with respect to a range of values should be
interpreted to include both the upper and lower end of the recited
range.
[0154] Although the present invention has been described in detail,
it should be understood that various changes, substitutions, and
alterations can be made hereupon without departing from the
principle and scope of the invention. Accordingly, the scope of the
present invention should be determined by the following claims and
their appropriate legal equivalents.
[0155] Embodiments include many additional standard components or
equipment that enables and makes operable the described apparatus,
process, method and unit. Examples of such standard equipment known
to one of ordinary skill in the art includes heat exchanges, pumps,
blowers, reboilers, steam generation, condensate handling,
membranes, single and multi-stage compressors, separation and
fractionation equipment, valves, switches, controllers and
pressure-, temperature-, level- and flow-sensing devices.
Operation, control and performance of portions of or entire steps
of a process or method can occur through human interaction,
pre-programmed computer control and response units, or combinations
thereof.
[0156] Moreover, the foregoing has broadly outlined certain
objectives, features, and technical advantages of the present
invention and a detailed description of the invention so that
embodiments of the invention may be better understood in light of
features and advantages of the invention as described herein, which
form the subject of certain claims of the invention. It should be
appreciated that the conception and specific embodiment disclosed
may be readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present
invention. It should also be realized that such equivalent
constructions do not depart from the invention as set forth in the
appended claims. The novel features which are believed to be
characteristic of the invention, both as to its organization and
method of operation, together with further objects and advantages
are better understood from the description above when considered in
connection with the accompanying figures. It is to be expressly
understood, however, that such description and figures are provided
for the purpose of illustration and description only and are not
intended as a definition of the limits of the present invention. It
will be apparent to those skilled in the art that various
modifications and changes can be made within the spirit and scope
of the invention as described in the foregoing specification.
* * * * *