U.S. patent application number 14/344632 was filed with the patent office on 2015-06-04 for processing of lithium containing material.
The applicant listed for this patent is Reed Industrial Minerals Pty Ltd., Yatendra SHARMA. Invention is credited to Yatendra Sharma.
Application Number | 20150152523 14/344632 |
Document ID | / |
Family ID | 50101101 |
Filed Date | 2015-06-04 |
United States Patent
Application |
20150152523 |
Kind Code |
A1 |
Sharma; Yatendra |
June 4, 2015 |
PROCESSING OF LITHIUM CONTAINING MATERIAL
Abstract
A process (10) for the treatment of a lithium containing
material, the process comprising the steps of: (i) Preparing a
process solution from the lithium containing material (12); (ii)
Passing the process solution from step (i) to a series of impurity
removal steps (36) thereby providing a substantially purified
lithium chloride solution; and (iii) Passing the purified lithium
chloride solution of step (ii) to an electrolysis step (70) thereby
producing a lithium hydroxide solution.
Inventors: |
Sharma; Yatendra; (West
Perth, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHARMA; Yatendra
Reed Industrial Minerals Pty Ltd. |
Hillarys, WA
West Perth, WA |
|
AU
AU |
|
|
Family ID: |
50101101 |
Appl. No.: |
14/344632 |
Filed: |
August 1, 2013 |
PCT Filed: |
August 1, 2013 |
PCT NO: |
PCT/AU2013/000857 |
371 Date: |
March 13, 2014 |
Current U.S.
Class: |
423/179.5 |
Current CPC
Class: |
C01D 15/04 20130101;
C22B 3/44 20130101; C25B 1/16 20130101; C22B 26/12 20130101; C22B
3/42 20130101; C22B 3/10 20130101; C01D 15/02 20130101; C01D 15/08
20130101; Y02P 10/20 20151101; C22B 4/02 20130101 |
International
Class: |
C22B 26/12 20060101
C22B026/12; C22B 3/42 20060101 C22B003/42; C22B 3/10 20060101
C22B003/10; C22B 4/02 20060101 C22B004/02; C22B 3/44 20060101
C22B003/44 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 13, 2012 |
AU |
2012903483 |
Claims
1. A process for the treatment of a lithium containing material,
the process comprising the steps of: (i) Preparing a process
solution from the lithium containing material; (ii) Passing the
process solution from step (ii) to a series of impurity removal
steps thereby providing a substantially purified lithium chloride
solution; and (iii) Passing the purified lithium chloride solution
of step (ii) to an electrolysis step thereby producing a lithium
hydroxide solution.
2. The process of claim 1, wherein the process solution of step (i)
is prepared in the form of a pregnant leach solution.
3. The process of claim 2, wherein the pregnant leach solution is
formed by passing a lithium containing material to a leach step in
which the material is leached with hydrochloric acid.
4. The process of any one of the preceding claims, wherein the
impurity removal step (ii) further comprises a concentration step
such that the process solution is concentrated to near saturation
of lithium chloride.
5. The process of any one of the preceding claims, wherein the
lithium hydroxide solution produced in step (iii) is thickened by
evaporation of water to provide lithium hydroxide monohydrate
crystals.
6. The process of any one of the preceding claims, wherein the
lithium hydroxide solution produced in step (iii) is carbonated by
passing compressed carbon dioxide through the solution, thereby
producing a lithium carbonate precipitate.
7. The process of any one of the preceding claims, wherein the
lithium containing material is an alpha-spodumene ore or ore
concentrate and the process further comprises a first step in which
that alpha-spodumene ore or ore concentrate is calcined to produce
beta-spodumene.
8. The process of any one of claims 1 to 6, wherein the lithium
containing material is a lithium containing brine.
9. The process of claim 6, wherein a first portion of the lithium
hydroxide solution produced in step (iii) is thickened by
evaporation/crystallisation to provide lithium hydroxide
monohydrate crystals and a second portion thereof is carbonated by
passing compressed carbon dioxide through the solution, thereby
producing a lithium carbonate precipitate.
10. The process of any one of the preceding claims, wherein the
impurity removal steps of step (ii) include one or more of
hyrdropyrolysis of Al and Fe chlorides, pH increase to precipitate
hydroxides of Al, Fe, Mg and Mn, lithium carbonate precipitation
for removal of Ca, and fractional crystallisation for the removal
of Na and K.
11. The process of claim 10, wherein the fractional crystallisation
for the removal of Na and K is conducted immediately after the
concentration step.
12. The process of claim 10 or 11, wherein the impurity removal
steps further comprises an ion exchange step.
13. The process of claim 12, wherein the ion exchange step removes
substantially all calcium, magnesium and other multivalent cations
remaining in the process solution.
14. The process of claim 13, wherein such multivalent cations are
removed to a level of less than about 10 ppm.
15. The process of claim 13 or 14, wherein such multivalent cations
are removed to a level of about 1 ppm.
16. The process of any one of claims 9 to 15, wherein water
evaporated from the solution in evaporation/crystallisation is
recompressed, combined with make-up steam and utilised in
evaporation/crystallisation.
17. The process of any one of claims 9 to 16, wherein the
evaporation/crystallisation step utilises a vacuum evaporative
crystalliser.
18. The process of any one of claims 7 to 17, wherein the
beta-spodumene is cooled and milled prior to the leach step.
19. The process of claim 18, wherein the beta-spodumene is milled
to less than about 300 .mu.m.
20. The process of claim 18 or 19, wherein the beta-spodumene is
milled to a P.sub.80 of about 75 .mu.m.
21. The process of any one of claims 3 to 20, wherein the leach of
step (ii) is conducted at elevated temperature.
22. The process of any one of claims 3 to 21, wherein the
hydrochloric acid solution used in the leach step is about 20% HCl
w/w.
23. The process of claim 22, wherein the elevated temperature of
the leach of step is about the boiling point of the hydrochloric
acid solution used in the leach step.
24. The process of any one of claims 3 to 23, wherein the leach
step is conducted at atmospheric pressure.
25. The process of any one of claims 3 to 24, wherein the leach
step is conducted in a chlorination kiln at about 108.degree. C.
over a residence time of about 6 to 10 hours.
26. The process of claim 25, wherein the leach step is conducted
over a residence time of about 8 hours.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the treatment of lithium
containing material.
[0002] More particularly, the present invention relates to a
process for the treatment of a lithium containing material and the
production of lithium hydroxide and lithium carbonate. The process
utilising the electrolysis of a lithium chloride solution obtained
from either a spodumene ore or concentrate, or from brines. In one
form, the process of the present invention is intended to provide a
high purity or battery grade lithium hydroxide and lithium
carbonate product.
[0003] The process of the present invention may further provide a
hydrochloric acid product. Still further, the process of the
present invention, in one form, utilises precious metal containing
mixed metal oxide (MMO) electrodes to heighten the efficiency of an
electrochemical portion of the process.
BACKGROUND ART
[0004] Known processes for the production of lithium carbonate from
lithium containing ores or concentrates typically utilise the
thermal treatment of an alpha-spodumene ore or concentrate. This
thermal treatment can be referred as decrepitation and transforms
the alpha-spodumene to beta-spodumene which is in turn able to be
solubilised by acid. The step in which the beta-spodumene is
solubilised in acid takes place in a kiln and produces soluble
lithium salt. The lithium salt is passed to one or more tanks in
which the lithium salt is purified. Leached crude lithium salt is
subsequently passed to a step in which the pH of the slurry is
adjusted, whereby certain impurities, including iron and magnesium
are intended to be precipitated. Thus purified lithium salt is
treated with soda ash to produce lithium carbonate. This lithium
carbonate can be further treated with hydrated lime to produce
lithium hydroxide.
[0005] Processes for the production of lithium carbonate and
lithium hydroxide from brines typically involves the use of
evaporation ponds to increase the concentration of the salts
contained therein before being passed to a series of steps aimed to
reduce the impurities present.
[0006] The above described processes of the prior art are
relatively inefficient in the removal of impurities remaining in
the pregnant leach solution, which results in a relatively impure
lithium hydroxide and lithium carbonate product. This is
particularly problematic when attempting to produce high quality or
battery grade lithium hydroxide and lithium carbonate products.
[0007] The process of the present invention has as one object
thereof to overcome substantially one or more of the above
mentioned problems associated with prior art processes, or to at
least provide a useful alternative thereto.
[0008] The preceding discussion of the background art is intended
to facilitate an understanding of the present invention only. This
discussion is not an acknowledgement or admission that any of the
material referred to is or was part of the common general knowledge
as at the priority date of the application.
[0009] Throughout the specification and claims, unless the context
requires otherwise, the word "comprise" or variations such as
"comprises" or "comprising", will be understood to imply the
inclusion of a stated integer or group of integers but not the
exclusion of any other integer or group of integers.
[0010] The term "battery grade lithium carbonate" refers to a
product having a purity of about 99.5% or higher. Similarly, the
term "battery grade lithium hydroxide" refers to a product having a
purity of about 99% or higher.
Disclosure of the Invention
[0011] In accordance with the present invention there is provided a
process for the treatment of a lithium containing material, the
process comprising the steps of: [0012] (i) Preparing a process
solution from the lithium containing material; [0013] (ii) Passing
the process solution from step (i) to a series of impurity removal
steps thereby providing a substantially purified lithium chloride
solution; and [0014] (iii) Passing the purified lithium chloride
solution of step (ii) to an electrolysis step thereby producing a
lithium hydroxide solution; and [0015] (iv) Carbonating the lithium
hydroxide solution produced in step (iii) by passing compressed
carbon dioxide through the solution, thereby producing a lithium
carbonate precipitate.
[0016] Wherein the lithium containing material is an
alpha-spodumene ore or ore concentrate and the process further
comprises a first step in which that alpha-spodumene ore or ore
concentrate is calcinated to produce beta-spodumene.
[0017] In one form of the present invention, the process solution
of step (i) is prepared in the form of a pregnant leach solution.
Preferably, the pregnant leach solution is formed by passing a
lithium containing material to a leach step in which the material
is leached with hydrochloric acid.
[0018] Preferably, the impurity removal step (ii) further comprises
a concentration step wherein the pregnant leach solution is
concentrated to near saturation of lithium chloride.
[0019] The lithium hydroxide solution produced in step (iii) may be
thickened by evaporation of water to provide lithium hydroxide
monohydrate crystals.
[0020] In a further form of the present invention a first portion
of the lithium hydroxide solution produced in step (iii) is
thickened by evaporation/crystallisation to provide lithium
hydroxide monohydrate crystals and a second portion thereof is
carbonated by passing compressed carbon dioxide through the
solution, thereby producing a lithium carbonate precipitate.
[0021] Preferably, the impurity removal steps of step (ii) include
one or more of hyrdropyrolysis of Al and Fe chlorides, pH increase
to precipitate hydroxides of Al, Fe, Mg and Mn, lithium carbonate
precipitation for removal of Ca, and fractional crystalisation for
the removal of Na and K.
[0022] Still preferably, the fractional crystallisation for the
removal of Na and K is conducted immediately after the
concentration step.
[0023] The impurity removal steps preferably further comprises an
ion exchange step. Preferably, the ion exchange step removes
substantially all calcium, magnesium and other multivalent cations
remaining in the pregnant leach solution. Still preferably, such
multivalent cations are removed to a level of less than about 10
ppm.
[0024] Still preferably, water evaporated from the solution in
evaporation/crystallisation is recompressed, combined with make-up
steam and utilised in evaporation/crystallisation. The
evaporation/crystallisation step preferably utilises a vacuum
evaporative crystalliser.
[0025] Preferably, the beta-spodumene is cooled and milled prior to
the leach step. The beta-spodumene is preferably milled to less
than about 300 .mu.m. Still preferably, the beta-spodumene is
milled to a P.sub.80 of about 75 .mu.m.
[0026] Preferably, the leach step is conducted at elevated
temperature.
[0027] The hydrochloric acid solution used in the leach step is
preferably about 20% HCl w/w.
[0028] Still preferably, the elevated temperature of the leach step
is about the boiling point of the hydrochloric acid solution used
in the leach step.
[0029] The leach step is preferably conducted at atmospheric
pressure.
[0030] In one form of the present invention the leach step is
conducted in a chlorination kiln at about 108.degree. C. over a
residence time of about 6 to 10 hours. Preferably, the residence
time is about 8 hours.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The process of the present invention will now be described,
by way of example only, with reference to one embodiment thereof
and the accompanying drawing, in which:
[0032] FIG. 1 is a schematic flow-sheet depicting a process for the
treatment of a lithium containing material in accordance with a
first embodiment of the present invention in which the lithium
containing material is an alpha-spodumene concentrate.
BEST MODE(S) FOR CARRYING OUT THE INVENTION
[0033] In FIG. 1 there is shown a process 10 for the treatment of a
lithium containing material in accordance with a first embodiment
of the present invention in which embodiment the lithium containing
material is provided in the form of an alpha-spodumene
concentrate.
[0034] All of the unit operations embodied in the process 10 are
intended to operate continuously with full process instrumentation
and control being provided for.
[0035] An alpha-spodumene concentrate 12 is passed to a calcining
step in which the concentrate 12 is calcined in a calcining furnace
14 at a temperature of between about 1050.degree. C. to
1100.degree. C. to convert the alpha-spodumene to leachable
beta-spodumene. Off-gases from the calciner are directed through a
cyclone (not shown) and an electrostatic precipitator (not shown)
specified to comply with known environmental emissions limits. The
resulting hot calcine is passed to a cooler 16 and indirectly
cooled to about 80.degree. C. It is then dry-milled to less than
300 .mu.m, for example to a P.sub.80 of about 75 .mu.m, in a mill,
for example a closed circuit ball mill 18.
[0036] After storage in a surge bin (not shown), the milled
beta-spodumene is mixed with at least a 40 to 300% stoichiometric
excess of 20% hydrochloric acid w/w 20 in a slurrying step. The
slurrying step feeds a leach step, for example a leach circuit 22,
comprising a first leach stage 24 and a second leach stage 26.
[0037] The leach step is conducted at about 108.degree. C., being
the boiling point of the hydrochloric acid leach solution added in
the slurrying step, for a period of about 6 to 12 hours, for
example about 8 hours, in continuous leach tanks. A pulp density of
about 40% is used in the leach circuit 22 to maximise the leach
concentration and to ensure that the solubility limit of lithium
chloride during leaching is not exceeded. Off-gases are cleaned in
a wet scrubber (not shown). The leach step 22 produces a residue
slurry and a process solution, for example a pregnant leach
solution. The lithium and the aluminosilicate in the beta-spodumene
leaches into solution with other impurities to give a sub-saturated
concentration of lithium chloride in the pregnant leach liquor.
[0038] The pregnant leach solution from the leach circuit 22 is
passed to a thickening circuit 28, preferably comprising two stages
28a and 28b aligned with the stages 24 and 26 of the leach circuit
22. An overflow from the thickening circuit 28 is directed to a
pyrohydrolysis step 30, operating at about 300 oC, and in which
chlorides of Al and Fe present in the pregnant leach solution are
converted into their respective insoluble oxides 32. Any residual
HCl is also recovered in an HCL removal step 34.
[0039] In addition to the Al and Fe described immediately above as
being recovered using the pyrohydrolysis step 30, remaining soluble
iron, aluminium and magnesium are removed in large part from the
leach liquor through a series of impurity removal steps, indicated
in a broad sense by impurity removal steps 36 in FIG. 1. The
impurity removal steps 36 further include a pH modification step 38
through the addition of LiOH 40 to raise the pH to about 9. The
product of step 38 is passed to a belt filter 42 from which Al, Fe,
Mn and Mg containing precipitates are recovered. The impurity
removal steps 36 further include a calcium precipitation step 44
with the addition of either sodium carbonate (soda ash) or lithium
carbonate 46, producing a calcium containing precipitate 48 from a
further belt filter 50.
[0040] A thickener underflow product 52 of the second thickening
step 28b is passed to a drying step 54 before passing to waste 56
and subsequent disposal 58.
[0041] The liquid product of the belt filter 50, being largely LiCl
solution, is passed to a concentration step 60 and in turn to a
fractional crystallisation step 62. In the concentration step 60
the LiCl solution is concentrated to near saturation point, for
example 35 to 40% LiCl w/w, and is cooled to a sub zero
temperature. In the subsequent fractional crystallisation step 62
Na and K impurities 64 are largely removed, as NaCl and KCl
crystals, respectively, by filtration.
[0042] After the removal of substantially all impurities as
described above, the lithium chloride solution is passed through an
ion exchange step 66, comprising an Ion Exchange (IX) column 68 by
which substantially all of any residual calcium, magnesium and
other multivalent cations are removed to a level of less than about
10 ppm, for example 1 ppm.
[0043] The further purified lithium chloride solution is then
heated to 90.degree. C. and pumped to an electrolysis step 70
comprising a number of electrolysers, for example 6 to 20
electrolysers, in which lithium chloride and water are consumed to
produce lithium hydroxide, chlorine and hydrogen.
[0044] After passing through the electrolysers, the weak or
depleted lithium chloride solution contains dissolved chlorine gas.
Before this weak lithium chloride solution is recycled to the
slurrying step immediately prior to the leach circuit 22, the
dissolved chlorine is removed in two stages. In a first stage
hydrochloric acid is added to the lithium chloride solution to
reduce the pH to<5 which forces some of the chlorine gas out of
solution. The remaining dissolved chlorine gas is then removed by
air stripping the solution (not shown).
[0045] Chlorine and hydrogen produced as by-products are combined
to produce HCl acid which is used in the slurrying step and
leaching circuit 22.
[0046] The lithium hydroxide solution obtained from the
electrolysis step 70 is passed firstly to a holding tank 72, from
which it can either be (i) evaporated and crystallised to produce
lithium hydroxide monohydrate crystals, or (ii) sent to carbonation
step to convert into lithium carbonate, as clearly shown in FIG.
1.
[0047] In the first of these options, the lithium hydroxide in
solution is crystallised in, for example, a vacuum evaporative
crystalliser 80 (Oslo type) operating at a temperature of about
80.degree. C. and pressure of about 45 kPa(a). The residence time
is about 60 minutes so as to achieve a coarse crystal product. The
resulting water vapour is recompressed, combined with make-up steam
and used as the heating medium for the crystalliser 80.
[0048] Lithium hydroxide crystals are washed by cold water (not
shown) achieving a wash efficiency of 99%. The resulting wash
solution is recycled back to the leach circuit 22 as noted above.
Solids from the centrifuge are fed to an indirect-fired kiln or
dryer 82, operating at about 120.degree. C., which dries the
crystals. The crystal product, being battery grade LiOH.H.sub.2O,
is pneumatically conveyed to product bins 84, and cooled to
50.degree. C. in a jacketed screw conveyer 86 as it is conveyed
ultimately to bagging stations (not shown).
[0049] In the second option noted above, lithium carbonate may be
produced by carbonation of lithium hydroxide solution by passing
compressed carbon dioxide gas 88 though the solution of lithium
hydroxide in a carbonation vessel 90 in which lithium carbonate is
precipitated. This slurry is fed to a washer/centrifuge 92 by way
of a filter 94, after which wash water is recycled with any
remaining lithium hydroxide solution or mother liquor to
electrolysis 70. Wet lithium carbonate crystals are fed to a dryer
96 in which hot air is used to dry the crystals. Medium pressure
air is used to heat the air. After drying the battery grade lithium
carbonate may be micronized to a particle size requested by a
customer prior to passing to storage bins 98 and subsequent bagging
(not shown).
[0050] Condensate throughout the process is used as make-up water
for hot process water, cold process water and cooling water. As the
process does not return condensate there is an overall positive
water balance and about 1/10.sup.th of the process water is
discharged to a sewerage system (not shown).
[0051] It is envisaged that tantalite and alumina may also be
recovered using the process of the present invention. The filter
cake from the thickening step may be discharged to a tantalite
recovery plant (not shown). Discharge from the tantalite recovery
plant may be fed onto a belt filter to remove water, which is
returned to the tantalite recovery plant. The filter does not use
washing and has a filtration are of 19 m.sup.2. The filter cake
from the belt filter is dried in a direct-fired kiln. The dry
alumina silicate is cooled to 50.degree. C. in a jacketed screw
conveyor and then pneumatically conveyed to a storage bin prior to
dispatch.
[0052] In accordance with a second embodiment of the present
invention the lithium containing material may be provided in the
form of a lithium containing brine. Brines do not require the
calcining, cooling, milling and leach steps as described for the
first embodiment of the present invention but it is envisaged that
the remainder of the process will be substantially similar to that
of the first embodiment described above.
[0053] As can be seen from the above, the process of the present
invention provides a process by which a high purity or battery
grade lithium hydroxide and lithium carbonate products may be
obtained from an alpha-spodumene ore or concentrate, or from a
lithium containing brine, whilst also allowing the production of a
hydrogen chloride gas product.
[0054] Modifications and variations such as would be apparent to
the skilled addressee are considered to fall within the scope of
the present invention. For example, it is envisaged that the leach
circuit 22 may comprise only a single leach stage/operation without
departing from the scope of the present invention.
* * * * *