U.S. patent application number 14/386133 was filed with the patent office on 2015-04-16 for processes for recovering rare earth elements and rare metals.
The applicant listed for this patent is ORBITE ALUMINAE INC.. Invention is credited to Richard Boudreault, Carsten Dittrich, Heinz Krivanec, Marie-Maxime Labrecque-Gilbert, Denis Primeau.
Application Number | 20150104361 14/386133 |
Document ID | / |
Family ID | 49221738 |
Filed Date | 2015-04-16 |
United States Patent
Application |
20150104361 |
Kind Code |
A1 |
Boudreault; Richard ; et
al. |
April 16, 2015 |
PROCESSES FOR RECOVERING RARE EARTH ELEMENTS AND RARE METALS
Abstract
There are provided processes for recovering at least one rare
earth element. Such processes comprise obtaining an acidic
composition comprising (i) at least one rare earth element and
optionally at least one rare metal; and reacting the composition
with a precipitating agent so as to substantially selectively
precipitate a first rare earth element and optionally a first rare
metal. For example, various rare earth elements (such as scandium,
yttrium, lanthanum, cerium, praseodymium, neodymium, promethium,
samarium, europium, gadolinium, terbium, dysprosium, holmium,
erbium, thulium, ytterbium, lutetium, etc) and various rare metals
(such as indium, zirconium, lithium, gallium, etc.) can be
extracted by using such processes.
Inventors: |
Boudreault; Richard;
(St-Laurent, CA) ; Primeau; Denis; (Ste-Julie,
CA) ; Krivanec; Heinz; (Oberwaltersdorf, AT) ;
Dittrich; Carsten; (Aachen, DE) ; Labrecque-Gilbert;
Marie-Maxime; (Laval, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ORBITE ALUMINAE INC. |
St-Laurent |
|
CA |
|
|
Family ID: |
49221738 |
Appl. No.: |
14/386133 |
Filed: |
March 13, 2013 |
PCT Filed: |
March 13, 2013 |
PCT NO: |
PCT/CA2013/000226 |
371 Date: |
September 18, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61703219 |
Sep 19, 2012 |
|
|
|
61705807 |
Sep 26, 2012 |
|
|
|
Current U.S.
Class: |
423/21.5 ;
423/21.1 |
Current CPC
Class: |
C22B 3/42 20130101; C22B
59/00 20130101; C22B 3/20 20130101; Y02P 10/234 20151101; C22B
58/00 20130101; Y02P 10/20 20151101 |
Class at
Publication: |
423/21.5 ;
423/21.1 |
International
Class: |
C22B 59/00 20060101
C22B059/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2012 |
CA |
PCT/CA2012/000253 |
May 3, 2012 |
CA |
PCT/CA2012/000419 |
Claims
1-295. (canceled)
296. A process for recovering at least one rare earth element, said
process comprising: obtaining an acidic composition comprising (i)
at least one rare earth element and optionally at least one rare
metal and (ii) at least one iron ion; at least partially removing,
from said acidic composition, said least one iron ion by means of
an extracting agent, an ion exchange resin, hydrolysis and/or by
reacting said composition with a reducing agent, thereby obtaining
a composition having a reduced content in said at least one iron
ion; and reacting said composition having said reduced content in
said at least one iron ion with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and optionally a first rare metal that are comprised in a so-formed
precipitate, and recovering said precipitate.
297. The process of claim 296, wherein said acidic composition
comprises (i) said at least one rare earth element and optionally
said at least one rare metal and (ii) FeCl.sub.3.
298. The process of claim 297, wherein said extracting agent is
chosen from tri-butyl phosphate, di-2-ethylhexyl phosphoric acid
(HDEHP), bis(2,4,4-trimethylpentyl) phosphinic acid and
2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester).
299. The process of claim 296, wherein said acidic composition is
reacted with Fe(0), thereby obtaining a composition having a
reduced content in Fe.sup.3+.
300. The process of claim 296, wherein said first rare earth
element is scandium.
301. The process of claim 300, wherein said first rare metal is
gallium and said first rare metal is substantially selectively
precipitated with said first rare earth element.
302. The process of claim 296, wherein said precipitating agent is
chosen from oxalic acid, NaOH, MgO, CaCO.sub.3 and mixtures
thereof.
303. The process of claim 301, wherein said precipitating agent is
chosen from oxalic acid, NaOH, MgO, CaCO.sub.3 and mixtures
thereof.
304. The process of claim 301, wherein said precipitating agent is
CaCO.sub.3.
305. The process of claim 304, wherein said first rare earth
element and said first rare metal are substantially selectively
precipitated by maintaining a pH value below 2.
306. The process of claim 296, further comprising leaching said
precipitate and obtaining a leaching solution, wherein said
leaching solution is further extracted with an extracting agent so
as to substantially selectively extract said first rare earth
element and said first rare metal and obtain a loaded organic
phase.
307. The process of claim 306, further comprising scrubbing said
loaded organic phase with a scrubbing solution so as to recover
said first rare earth element and obtained a scrubbed organic
phase.
308. The process of any one of claim 307, further comprising
stripping said scrubbed organic phase with a stripping solution so
as to recover said first rare metal.
309. The process of claim 296, wherein said process further
comprises, pre-treating or treating said acidic composition with an
ion exchange resin so as to remove impurities.
310. The process of claim 302, wherein said first rare earth
element and said first rare metal are substantially selectively
precipitated by maintaining Redox potential of about Eh +380
mV.
311. A process for recovering at least one rare earth element, said
process comprising: obtaining an acidic composition comprising (i)
at least one rare earth element and at least one rare metal; and
(ii) at least one metal ion; at least partially removing, from said
acidic composition, said least one metal ion by means of an
extracting agent, an ion exchange resin, hydrolysis and/or by
reacting said composition with a reducing agent, thereby obtaining
a composition having a reduced content in said at least one metal
ion; and reacting said composition having said reduced content in
said at least one metal ion with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and a first rare metal.
312. The process of claim 311, wherein said at least one metal ion
comprises at least one aluminum ion, at least one zinc ion, at
least one copper ion, at least one nickel ion, at least one
magnesium ion, at least one titanium ion and/or at least one iron
ion.
313. A process for recovering at least one rare earth element, said
process comprising: obtaining an acidic composition comprising (i)
at least one rare earth element and optionally at least one rare
metal and (ii) at least one iron ion; at least partially removing,
from said acidic composition, said least one iron ion by means of
an extracting agent, an ion exchange resin and/or by reacting said
composition with a reducing agent, thereby obtaining a composition
having a reduced content in said at least one iron ion; and
reacting said composition having said reduced content in said at
least one iron ion with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and a first rare metal by maintaining a pH value below 2, wherein
said composition having said reduced content in said at least one
iron ion being reacted with said precipitating agent so as to
obtain a liquid comprising at least one further rare earth element
and said precipitate comprising said first rare earth element and
said first rare metal, said process further comprising separating
said liquid from said precipitate.
314. The process of claim 313, wherein said first rare earth
element and said first rare metal is/are substantially selectively
precipitated by maintaining a pH at a value of about 1 to about
2.
315. A process for recovering at least one rare earth element, said
process comprising: obtaining an acidic composition comprising (i)
at least one rare earth element and at least one rare metal; and
reacting said composition with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and a first rare metal that is gallium.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority on PCT/CA2012/000253
filed Mar. 19, 2012, on PCT/CA2012/000419 filed on May 3, 2012; on
U.S. 61/703,219 filed on Sep. 19, 2012; and on U.S. 61/705,807
filed on Sep. 26, 2012. These documents are hereby incorporated by
reference in their entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to improvements in the field
of chemistry applied to the recovery, extraction and/or isolation
of rare earth elements (REE) and rare metals (RM). For example,
such processes are useful for obtaining rare earth elements from
various materials and derivatives thereof such as
aluminum-containing materials and derivatives, iron-containing
materials and derivatives, zinc-containing materials and
derivatives thereof, copper-containing materials and derivatives
thereof, nickel-containing materials and derivatives thereof, and
titanium-containing materials and derivatives thereof.
BACKGROUND OF THE DISCLOSURE
[0003] In various technologies, there is an increasing need for
rare earth elements. In few countries, efforts to reestablish
mining of rare earth elements have been undertaken. In the future,
supplies of rare earth elements will considerably depend upon
economic viability of the extraction and production processes and
technological innovations requiring such rare earth elements.
[0004] There is thus a need for providing an alternative to the
existing solutions for extracting rare earth elements.
SUMMARY OF THE DISCLOSURE
[0005] According to one aspect, there is provided a process for
recovering at least one rare earth element, the process
comprising:
[0006] obtaining an acidic composition comprising (i) at least one
rare earth element and optionally at least one rare metal; and
reacting the composition with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and optionally a first rare metal.
[0007] According to another aspect, there is provided a process for
recovering at least one rare earth element, the process
comprising:
[0008] obtaining an acidic composition comprising (i) at least one
rare earth element and optionally at least one rare metal and (ii)
at least one metal ion;
[0009] at least partially removing, from the acidic composition,
the least one metal ion by means of an extracting agent, an ion
echange resin and/or by reacting the composition with a reducing
agent, thereby obtaining a composition having a reduced content in
the at least one metal ion; and
[0010] reacting the composition having the reduced content in the
at least one metal ion with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and optionally a first rare metal.
[0011] According to another aspect, there is provided a process for
recovering at least one rare earth element, the process
comprising:
[0012] obtaining an acidic composition comprising (i) at least one
rare earth element and optionally at least one rare metal and (ii)
at least one iron ion;
[0013] at least partially removing, from the acidic composition,
the least one iron ion by means of an extracting agent, an ion
echange resin and/or by reacting the composition with a reducing
agent, thereby obtaining a composition having a reduced content in
the at least one iron ion; and
[0014] reacting the composition having the reduced content in the
at least one iron ion with a precipitating agent so as to
substantially selectively precipitate a first rare earth element
and optionally a first rare metal.
[0015] According to another aspect, there is provided a process for
recovering at least one rare earth element from at least one
material, the process comprising:
[0016] leaching the at least one material with at least one acid so
as to obtain a leachate comprising at least one metal ion, and the
at least one rare earth element;
[0017] substantially selectively precipitating, extracting and/or
isolating the at least one metal ion from the leachate and
optionally obtaining a precipitate; and
[0018] substantially selectively precipitating, extracting and/or
isolating the at least one rare earth element from the leachate
and/or the precipitate.
[0019] According to another aspect, there is provided a process for
extracting at least one rare earth element from at least one
material, the process comprising:
[0020] leaching the at least one material with at least one acid so
as to obtain a leachate comprising at least one metal ion, and the
at least one rare earth element; and
[0021] selectively precipitating at least one member chosen from
the at least one rare earth element, and the at least one metal
ion.
[0022] According to one aspect, there is provided a process for
recovering at least one rare earth element from at least one
material, the process comprising:
[0023] leaching the at least one material with at least one acid so
as to obtain a leachate comprising at least one metal ion, and at
least one rare earth element;
[0024] optionally substantially selectively precipitating,
extracting and/or isolating the at least one rare earth element
from the leachate and/or the precipitate.
[0025] substantially selectively precipitating, extracting and/or
isolating the at least one metal ion from the leachate and
optionally obtaining a precipitate; and
[0026] substantially selectively precipitating, extracting and/or
isolating the at least one rare earth element from the leachate
and/or the precipitate.
[0027] According to another example, there is provided a process
for recovering at least one rare earth element from at least one
material, the process comprising:
[0028] leaching the at least one material with at least one acid so
as to obtain a leachate comprising at least one metal ion, the at
least one rare earth element, and a solid, and separating the
leachate from the solid;
[0029] substantially selectively removing at least one metal ion
from the leachate and optionally obtaining a precipitate; and
[0030] substantially selectively removing the at least one rare
earth element from the leachate and/or the precipitate.
[0031] According to another example, there is provided process for
recovering at least one rare earth element from at least one
material, the process comprising:
[0032] leaching the at least one material with at least one acid so
as to obtain a leachate comprising at least one metal ion and the
at least one rare earth element, and a solid, and separating the
leachate from the solid; and
[0033] substantially selectively removing at least one member
chosen from the at least one rare earth element and the at least
one metal ion from the leachate.
BRIEF DESCRIPTION OF DRAWINGS
[0034] In the following drawings, which represent by way of example
only, various embodiments of the disclosure:
[0035] FIG. 1 shows a bloc diagram of an example of a process for
preparing alumina and various other products including rare earth
elements, according to the present disclosure;
[0036] FIG. 2 shows a bloc diagram of another example of process
for preparing alumina and various other products including rare
earth elements, according to the present disclosure;
[0037] FIGS. 2A and 2B show a bloc diagram of a process similar to
the process shown in FIG. 2;
[0038] FIG. 3 shows a bloc diagram of another example of process
for extracting rare earth elements according to the present
disclosure;
[0039] FIG. 3A shows a bloc diagram of a process similar to the
process shown in FIG. 3;
[0040] FIGS. 4A and 4B show a bloc diagram of another example of a
process for extracting rare earth elements according to the present
disclosure;
[0041] FIGS. 4C and 4D show a bloc diagram of processes similar to
those shown in FIGS. 4A and 4B;
[0042] FIGS. 5A, 5B, 5C, 5D show a bloc diagram of another example
of a process for extracting rare earth elements according to the
present disclosure;
[0043] FIGS. 5E, 5F, 5G and 5H show a bloc diagram of processes
similar to those shown in FIGS. 5A, 5B, 5C, and 5D;
[0044] FIGS. 6 to 11 represents precipitation yields (%) obtained
for various rare earth elements and rare metals, during processes
according to the present disclosure;
[0045] FIGS. 12 to 25 represent curves showing various results
obtained when carrying out extractions of compounds, during
processes according to the present disclosure; and
[0046] FIG. 26 shows a bloc diagram of another example of process
for extracting rare earth elements according to the present
disclosure.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
[0047] Further features and advantages will become more readily
apparent from the following description of various embodiments as
illustrated by way of examples.
[0048] It was found that that the rare earth element(s) recovery
can be made, for example, in the processes described in the present
disclosure at various stages. Moreover, it was found that such
processes can be useful even if the rare earth elements are only
found as traces. It was also found that such processes can be
particularly useful for extracting rare earth elements from a
solution that is substantially refined or purified. For example,
these processes can be useful since they can be applied to
solutions from which several of the main components have been
removed They can also be applied to solutions before removal of
several of the main components.
[0049] The expression "at least one metal ion", as used herein
refers, for example, to at least one type of ion chosen form all
possible forms of ions of such a metal. For example, if the metal
"M" can be M.sup.2+ or M.sup.3+, the at least one metal ion for the
metal M can be either M.sup.2+ or M.sup.3+. For example, the metal
can be chosen from aluminum, iron, zinc, copper, nickel, magnesium,
titanium etc.
[0050] The expression "at least one aluminum ion", as used herein
refers, for example, to at least one type of aluminum ion chosen
from all possible forms of Al ions. For example, the at least one
aluminum ion can be Al.sup.3+.
[0051] The expression "at least one iron ion", as used herein
refers, for example, to at least one type of iron ion chosen from
all possible forms of Fe ions. For example, the at least one iron
ion can be Fe.sup.2+, Fe.sup.3+, or a mixture thereof.
[0052] The expression "at least one zinc ion", as used herein
refers, for example, to at least one type of zinc ion chosen from
all possible forms of Zn ions. For example, the at least one zinc
ion can be Zn.sup.2+.
[0053] The expression "at least one copper ion", as used herein
refers, for example, to at least one type of copper ion chosen from
all possible forms of Cu ions. For example, the at least one copper
ion can be Cu.sup.1+ or Cu.sup.2+, or a mixture thereof.
[0054] The expression "at least one nickel ion", as used herein
refers, for example, to at least one type of nickel ion chosen from
all possible forms of Ni ions. For example, the at least one nickel
ion can be Ni.sup.2+ or Ni.sup.3+, or a mixture thereof.
[0055] The expression "at least one magnesium ion", as used herein
refers, for example, to at least one type of magnesium ion chosen
from all possible forms of Mg ions. For example, the at least one
magnesium ion can be Mg.sup.2+.
[0056] The expression "at least one titanium ion", as used herein
refers, for example, to at least one type of titanium ion chosen
from all possible forms of Ti ions. For example, the at least one
titanium ion can be Ti.sup.3+ or Ti.sup.4+, or a mixture
thereof.
[0057] The expression "at least one rare earth element", as used
herein refers, for example, to at least one type of rare earth
element chosen from all the rare earth elements described in the
present disclosure in all their possible forms.
[0058] The expression "at least one rare metal", as used herein
refers, for example, to at least one type of rare metal chosen from
all the rare metals described in the present disclosure in all
their possible forms.
[0059] The expression "Ga-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of gallium.
[0060] The expression "Ce-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of cerium.
[0061] The expression "Sc-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of scandium.
[0062] The expression "Sm-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of samarium.
[0063] The expression "Eu-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of europium.
[0064] The expression "Gd-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of gadolinium.
[0065] The expression "Y-free solution", as used herein refers, for
example, to a solution that comprises about less than 5%, 2% or 1%
w/v of yttrium.
[0066] The expression "Pr-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of praseodymium.
[0067] The expression "Nd-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of neodymium.
[0068] The expression "La-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of lanthanum.
[0069] The expression "Er-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of erbium.
[0070] The expression "Dy-free solution", as used herein refers,
for example, to a solution that comprises about less than 5%, 2% or
1% w/v of dysprosium.
[0071] The expression "rare earth element" as used herein refers,
for example, to a rare element chosen from scandium, yttrium,
lanthanum, cerium, praseodymium, neodymium, promethium, samarium,
europium, gadolinium, terbium, dysprosium, holmium, erbium,
thulium, ytterbium, and lutetium. The acronym "REE" can be used in
the present disclosure as a synonym for "rare earth element".
[0072] The expression "rare metal" as used herein refers, for
example, to a rare metal chosen from indium, zirconium, lithium,
and gallium. These rare metals can be in various form such as the
elemental form (or metallic form), under the form of halides (for
example chlorides), oxides, sulfates, oxalates, hydroxides etc. The
acronym "RM" can be used in the present disclosure as a synonym for
"rare metal".
[0073] The term "REEO or REE-O" as used in the present disclosure
refers to rare earth element oxide(s).
[0074] The term "RMO or RM-O" as used in the present disclosure
refers to rare metal oxide(s).
[0075] Terms of degree such as "about" and "approximately" as used
herein mean a reasonable amount of deviation of the modified term
such that the end result is not significantly changed. These terms
of degree should be construed as including a deviation of at least
.+-.5% or at least .+-.10% of the modified term if this deviation
would not negate the meaning of the word it modifies.
[0076] In the processes of the present disclosure, after the
leaching, the substantially selectively removing of the at least
one member chosen from the at least one rare earth element and the
at least one metal from the leachate can be made in various
manners. The at least one metal ion (or a second metal ion) can be
removed and then, a first metal ion can be removed and finally, the
at least one rare earth element can be removed. Alternatively, the
first metal ion can be removed, then the second metal ion can be
removed and finally, the at least one rare earth element can be
removed. According to another example, the at least one rare earth
element can be removed, then, the first metal ion can be removed,
and finally the second metal ion can be removed. Also, the at least
one rare earth element can be removed, then, the second metal ion
can be removed, and finally the first metal ion can be removed.
Various other possible combinations can also be envisaged.
[0077] The at least one acid used for leaching the at least one
material can be HCl, H.sub.2SO.sub.4, HNO.sub.3 or mixtures
thereof. More than one acid can be used as a mixture or separately.
Solutions made with these acids can be used at various
concentration. For example, concentrated solutions can be used. For
example, 6 M or 12 M HCl can be used. For example, up to 98% or
100% wt H.sub.2SO.sub.4 can be used. For example, 18 wt % or 32 wt
% can be used
[0078] For example, the at least one material can be leached with
HCl having a concentration of about 15 to about 45 weight %, of
about 20 to about 45 weight %, of about 25 to about 45 weight %, of
about 26 to about 42 weight %, of about 28 to about 40 weight %, of
about 30 to about 38 weight %, or between 25 and 36 weight %.
[0079] Leaching can also be carried out by adding dry highly
concentrated acid (for example, 85%, 90% or 95%) in gas phase into
the aqueous solution. Alternatively, leaching can also be carried
out by using a weak acid solution (for example <3 wt %).
[0080] For example, leaching can be carried out by using HCl having
a concentration of about 18 to about 32 wt % in a first reactor and
then, by using HCl having concentration of about 90 to about 95% in
a second reactor.
[0081] For example, the at least one material can be leached at a
temperature of about 125 to about 225.degree. C., about 150 to
about 200.degree. C., about 160 to about 180.degree. C., or about
165 to about 170.degree. C.
[0082] For example, the leaching can be carried out under pressure.
For example, the pressure can be about 100 to about 300 or about
150 to about 200 psig. The leaching can be carried out for about 30
minutes to about 5 hours. For example, the leaching can be carried
out at a temperature of about 60.degree. C. to about 200.degree.
C.
[0083] For example, the leaching can be carried out under pressure
into an autoclave. For example, it can be carried out at a pressure
of 5 KPag to about 850 KPag, 50 KPag to about 800 KPag, 100 KPag to
about 750 KPag, 150 KPag to about 700 KPag, 200 KPag to about 600
KPag, or 250 KPag to about 500 KPag.
[0084] For example, the leaching can be carried out at a
temperature of at least 80.degree. C., at least 90.degree. C., or
about 100.degree. C. to about 110.degree. C. In certain cases it
can be done at higher temperatures so as to increase extraction
yields of rare earth elements in certain ores. For example, the
leaching can be carried out at a temperature of at least
100.degree. C., at least 120.degree. C., at least 130.degree. C.,
at least 140.degree. C., or about 140.degree. C. to about
175.degree. C.
[0085] For example, in the leachate, the at least one rare earth
element can be in the form of an ion.
[0086] For example, after the leaching, the at least one rare earth
element can be solubilized into the solution and can be found as a
soluble ion, associated to chlorine, a sulfate, a nitrate, or
hydrates thereof. etc.
[0087] For example, after the leaching, (if required) various bases
can be used for raising up the pH such as KOH, NaOH, Ca(OH).sub.2,
CaO, MgO, Mg(OH).sub.2, CaCO.sub.3, Na.sub.2CO.sub.3, NaHCO.sub.3,
CO.sub.2, or mixtures thereof.
[0088] For example, the at least one material can be chosen from
aluminum-containing materials and derivatives, iron-containing
materials and derivatives, zinc-containing materials and
derivatives thereof, copper-containing materials and derivatives
thereof, nickel-containing materials and derivatives thereof,
magnesium-containing materials and derivatives thereof and
titanium-containing materials and derivatives thereof.
[0089] For example, the at least one aluminum-containing material
can be at least one aluminum-containing ore.
[0090] For example, the at least one iron-containing material can
be at least one iron-containing ore.
[0091] For example, the at least one zinc-containing material can
be at least one zinc-containing ore.
[0092] For example, the at least one copper-containing material can
be at least one copper-containing ore.
[0093] For example, the at least one nickel-containing material can
be at least one nickel-containing ore.
[0094] For example, the at least one magnesium-containing material
can be at least one magnesium-containing ore.
[0095] For example, the at least one titanium-containing material
can be at least one titanium-containing ore.
[0096] For example, the at least one metal ion can comprise at
least one aluminum ion, at least one zinc ion, at least one copper
ion, at least one nickel ion, at least one magnesium ion, at least
one titanium ion and/or at least one iron ion.
[0097] For example, the at least one metal ion can comprise a first
metal ion and a second metal ion.
[0098] For example, the first metal ion can comprise at least one
aluminum ion, at least one zinc ion, at least one copper ion, at
least one nickel ion, at least one titanium ion and/or at least one
iron ion.
[0099] For example, the second metal ion can comprise at least one
aluminum ion, at least one zinc ion, at least one copper ion, at
least one nickel ion, at least one titanium ion and/or at least one
iron ion.
[0100] For example, the first metal ion can be at least one
aluminum ion.
[0101] For example, the second metal ion can be at least one iron
ion.
[0102] For example, the at least one metal ion can be removed by
using an ion exchange resin or ion exchange system. For example,
such an ion exchange resin or system can be effective for allowing
only chlorides of rare earth elements and chlorides rare metals to
pass therethrough, while capturing the at least one metal ion.
[0103] For example, the at least one iron ion can be precipitated.
When precipitating the at least one iron ion, it can be
precipitated by means of an ionic precipitation and it can
precipitate in the form of various salts, hydroxides, chlorides or
hydrates thereof. For example, the at least one iron ion can be
precipitated as FeCl.sub.2, FeCl.sub.3, Fe(OH).sub.3, Fe(OH).sub.2,
hematite, geotite, jarosite or hydrates thereof.
[0104] For example, after the precipitation of the at least one
iron ion, the at least one rare earth element can be solubilized
into the solution and can be found as a soluble ion, associated as
an hydroxide or a salt, or hydrates thereof.
[0105] For example, the at least aluminum ion can be precipitated.
When precipitating the at least aluminum ion, it can be
precipitated by means of an ionic precipitation and it can
precipitate in the form of various salts, (such as chlorides,
sulfates) or hydroxides or hydrates thereof. For example, the at
least one aluminum ion can be precipitated as Al(OH).sub.3,
AlCl.sub.3.6H.sub.2O, Al.sub.2(SO.sub.4).sub.3, or hydrates
thereof.
[0106] For example, after the precipitation of the at least one
metal ion, the at least one rare earth element can be solubilized
into the solution and can be found as a an ion associated to an
hydroxide or a salt or hydrates thereof.
[0107] For example, after precipitation of the at least one metal
ion, the residual and substantially purified or refined solution
can contain the at least one rare earth element into a mixture of
residual soluble ions, such as Cl.sup.-, SO.sub.4.sup.2-,
Na.sup.+.
[0108] The processes of the present disclosure can be effective for
treating various materials. The at least one material can be an
aluminum-containing material, The aluminum-containing material can
be an aluminum-containing ore. For example, clays, argillite,
mudstone, beryl, cryolite, garnet, spinel, bauxite, or mixtures
thereof can be used as starting material. The aluminum-containing
material can also be a recycled industrial aluminum-containing
material such as slag. The aluminum-containing material can also be
red mud.
[0109] The processes of the present disclosure can be effective for
treating various nickel-containing ores. For example, niccolite,
kamacite, taenite, limonite, garnierite, laterite, pentlandite, or
mixtures thereof can be used.
[0110] The processes of the present disclosure can be effective for
treating various zinc-containing ores. For example, smithsonite,
warikahnite, sphalerite, or mixtures thereof can be used.
[0111] The processes of the present disclosure can be effective for
treating various copper-containing ores. For example,
copper-containing oxide ores, can be used. For example,
chalcopyrite, chalcocite, covellite, bornite, tetrahedrite,
malachite, azurite, cuprite, chrysocolla, or mixtures thereof can
also be used.
[0112] The processes of the present disclosure can be effective for
treating various magnesium-containing materials. For example, the
serpentine can be treated by such processes. Moreover, antigorite,
chrysotile and lizardite can also be treated by such processes as
well as various magnesium waste materials and reject such as
industrial or mining wastes and mixtures thereof.
[0113] The processes of the present disclosure can be effective for
treating various titanium-containing ores. For example,
ecandrewsite, geikielite, pyrophanite, ilmenite, rutile or mixtures
thereof can be used.
[0114] For example, the at least one rare earth element can be
chosen from scandium, yttrium, lanthanum, cerium, praseodymium,
neodymium, promethium, samarium, europium, gadolinium, terbium,
dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.
[0115] For example, the at least one rare metal can be chosen from
indium, zirconium, lithium, and gallium.
[0116] For example, rare earth elements can sometimes be divided
into two categories, light rare earth elements (LRE) and heavy rare
earth elements (HRE). The light rare earth elements can comprise
lanthanum, cerium, praseodymium, neodymium, and samarium (atomic
numbers 57-62), and they are usually more abundant than heavy
ones.
[0117] For example, the at least one rare element can be extracted
under the form of various salts, oxides, hydroxides, and hydrates
thereof.
[0118] For example, the at least one rare earth element can be
chosen from scandium, gallium, yttrium, lanthanum, cerium,
praseodymium, neodymium, promethium, samarium, europium,
gadolinium, dysprosium, erbium, ytterbium and mixtures thereof.
[0119] For example, the at least one rare earth element is chosen
from scandium, gallium, yttrium, lanthanum, cerium, praseodymium,
neodymium, promethium, samarium, europium, gadolinium, dysprosium
and mixtures thereof.
[0120] For example, the at least one rare earth element is chosen
from scandium, gallium, yttrium, cerium and mixtures thereof.
[0121] For example, the at least one rare earth element can be
yttrium.
[0122] For example, the at least one rare earth element can be
scandium.
[0123] For example, the at least one rare earth element can be
gallium.
[0124] For example, the at least one rare earth element can be
cerium.
[0125] For example, the processes can comprise:
[0126] leaching the at least one material with HCl so as to obtain
the leachate comprising the at least one metal ion, and the at
least one rare earth element, and the solid and separating the
leachate from the solid;
[0127] substantially selectively removing the at least one metal
ion from the leachate, thereby obtaining a composition comprising
the metal ion, and the at least one rare earth element; and
[0128] substantially selectively at least partially removing the at
least one metal ion from the composition, thereby obtaining a
liquor comprising the at least one rare earth element.
[0129] For example, the at least one metal ion can be substantially
selectively removed from the leachate by substantially selectively
precipitating it from the leachate and removing it therefrom by
carrying out a solid-liquid separation.
[0130] For example, the at least one metal ion can be substantially
selectively removed from the leachate by substantially selectively
precipitating it under the form of AlCl.sub.3.6H.sub.2O and
removing it therefrom by carrying out a solid-liquid
separation.
[0131] For example, the composition can comprise HCl, the at least
one metal ion, and the at least one rare earth element.
[0132] For example, the composition can be an acidic composition
that comprises, the at least one metal ion, and the at least one
rare earth element.
[0133] For example, the acidic composition can comprises (i) the at
least one rare earth element and optionally that least one rare
metal and (ii) FeCl.sub.3.
[0134] For example, the at least one iron ion can be substantially
selectively removed from the composition by carrying out an
hydrolysis so as to convert the at least one iron ion into
Fe.sub.2O.sub.3 and removing the precipitated Fe.sub.2O.sub.3 from
the composition by carrying out a solid-liquid separation, thereby
obtaining the liquor comprising the at least one rare earth
element.
[0135] For example, after the removal of the precipitated
Fe.sub.2O.sub.3, the liquor containing the at least one rare earth
element is recirculated back for being further concentrated by
being used in precipitating the at least one aluminum ion.
[0136] For example, after the removal of the precipitated
Fe.sub.2O.sub.3, the liquor containing the at least one rare earth
element is recirculated back for being further concentrated by
being used in precipitating the at least one aluminum ion under the
form of AlCl.sub.3.6H.sub.2O.
[0137] For example, the at least one iron ion can be Fe.sup.3+ and
it can be substantially selectively partially removed from the
composition, and wherein the composition can be further treated
with a reducing agent so as to convert Fe.sup.3+ into Fe.sup.2+ and
then, Fe.sup.2+, under the form of FeCl.sub.2, can be removed from
the composition by carrying out a solid-liquid separation, thereby
obtaining the liquor comprising the at least one rare earth
element.
[0138] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
from the liquor by means of a liquid-liquid extraction.
[0139] For example, the at least one rare earth element can be
extracted from the liquor by means of liquid-liquid extraction.
[0140] For example, the at least one rare earth element can be
recovered from the liquor by means of liquid-liquid extraction.
[0141] For example, the at least one extracting agent can be chosen
from di-(2-ethylhexyl) phosphoric acid (HDEHP),
mono(2-ethylhexyl)2-ethylhexyl phosphonate (HEH/EHP),
bis(2,4,4-trimethylpentyl)monothiophosphinic acid), octyl phenyl
phosphate (OPAP), 2-ethylhexylphosphonic acid mono-2-ethylhexyl
ester (PC88A) and optionally toluene, tributyl phosphate,
di-isoamylmethyl phosphonate,
7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline, di-(2-ethylhexyl)
phosphinic acid, bis(2,4,4-trimethylpentyl) phosphinic acid,
8-hydroxyquinoline, and (2-ethylhexyl)phosphonic acid, and mixtures
thereof.
[0142] For example, the at least one extracting agent can be
di-(2-ethylhexyl) phosphoric acid.
[0143] For example, the at least one extracting agent can be
2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.
[0144] For example, the at least one extracting agent can be octyl
phenyl phosphate.
[0145] For example, the at least one extracting agent can be
tributyl phosphate.
[0146] For example, the at least one extracting agent can be chosen
from diethylenetriamine-penthaacetic acid (DTPA),
ethylenediaminetetraacetic (EDTA),
1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA),
bis(2,4,4-trimethylpentyl)monothiophosphinic acid and mixtures
thereof.
[0147] According to one example, when substantially selectively
precipitating, extracting and/or isolating the at least one rare
earth element from the leachate and/or the precipitate, the at
least one rare earth element found as an ion in the leachate can be
precipitated.
[0148] For example, scandium can be precipitated in the form of
Sc(OH).sub.3, ScCl.sub.3, ScF.sub.3, and/or [ScF.sub.6].sup.3-
(cation), wherein the cation can be sodium, potassium, magnesium,
calcium etc
[0149] Scandium can be precipitated at a pH of about 7 to about 9,
or about 7 to about 8.
[0150] For example, the leaching can be carried out at a pH of
about 0.5 to about 2.5, about 0.5 to about 1.5, or about 1; then
the second metal ion can be precipitated at a pH of at least about
9.5, 10, 10.5, 11, or 11.5; and then the first metal ion can be
precipitated at a pH of about 8 to about 9.
[0151] For example, the second metal ion can be precipitated at a
pH of about 10 to about 12.5, 10.5 to about 11.5, about 10.8 to
about 11.2, about 11.5 to about 12.5, or between 10 and 11.
[0152] For example, the precipitation of the first metal ion can be
carried out at a pH of about 7 to about 11, about 8 to about 10.5,
about 8.5 to 10 or about 9 to about 10.
[0153] For example, the precipitation of the second metal ion can
be carried out at a pH of about 3 to about 6, about 3.0 to about
5.5, about 3 to about 5, about 3 to about 4, about 3.0 to about
3.5, about 3.5 to about 4.0, about 4.0 to about 5.0, about 4.0 to
about 4.5, or about 4.5 to about 5.0.
[0154] For example, the precipitation of the first metal ion can be
carried out at a pH of about 5 to about 6, about 5.0 to about 5.5,
or about 5.5 to about 6.0.
[0155] For example, when precipitating AlCl.sub.3, highly
concentrated dry gaseous HCl at about 90 to about 98% can be
bubbled into the composition comprising the at least one iron ion,
the at least one aluminum ion and the at least one rare earth
element.
[0156] For example, when carrying out the hydrolysis of the at
least one iron ion so as to convert the at least one iron ion into
Fe.sub.2O.sub.3 and removing the Fe.sub.2O.sub.3, the pH during the
hydrolysis can be about below 2.5, 2.0, 1.5 or 1.0.
[0157] According to another example, the liquor can comprise the at
least one rare earth element under the form of a chloride, and
wherein the liquor can be reacted with an extracting agent in order
to substantially selectively extract gallium therefrom, thereby
obtaining a Ga-free solution and an extracted gallium solution, and
separating the solutions from one another. For example, gallium in
the liquor can be under the form of GaCl.sub.3. For example, the
extracting agent can be octyl phenyl phosphate,
2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and toluene,
tri-butyl phosphate or mixtures thereof. For example, the extracted
GaCl.sub.3 can then be precipitated and then converted into
Ga.sub.2O.sub.3. The latter can be further processed through a
plasma torch for purification above 99.5%.
[0158] For example, the Ga-free solution can then be reacted with
another an extracting agent in order to substantially selectively
extract cerium therefrom, thereby obtaining a Ce-free solution and
an extracted cerium solution, and separating the solutions from one
another. For example, the cerium in the Ga-free solution can be
under the form of CeCl.sub.3. For example, the another extracting
agent can be tri-butyl phosphate, di-isoamylmethyl phosphonate,
di-(2-ethylhexyl) phosphoric acid,
7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline or mixtures thereof.
For example, the process can further comprise converting the
extracted cerium into Ce.sub.2O.sub.3. For example, the extracted
cerium can be calcinated into Ce.sub.2O.sub.3. If the extracted
cerium in under the form of a chloride, HCl can be recovered (or
regenerated) from such a calcination process. For example, HCl can
be regenerated at its azeotropic concentration.
[0159] For example, the process can further comprise reacting the
Ce-free solution with a further extracting agent in order to
substantially selectively extract scandium therefrom, thereby
obtaining a Sc-free solution and an extracted scandium solution,
and separating the solutions from one another. For example,
scandium in the Ce-free solution. can be under the form of
ScCl.sub.3. For example, the further extracting agent can be
di-(2-ethylhexyl) phosphoric acid, di-(2-ethylhexyl) phosphinic
acid or a mixture thereof. For example, the process can further
comprise converting the extracted scandium into Sc.sub.2O.sub.3.
For example the extracted scandium can be converted into
Sc.sub.2O.sub.3 by means of NaOH. The extracted scandium can be
calcined so as to obtain Sc.sub.2O.sub.3. If the extracted scandium
is under the form of a chloride, HCl can be recovered (or
regenerated) from such a calcination process. For example, HCl can
be regenerated at its azeotropic concentration.
[0160] For example, the process can further comprise reacting the
Sc-free solution with still a further extracting agent in order to
substantially selectively extract samarium, europium or a mixture
thereof, thereby obtaining a Sm-free solution and/or Eu-free
solution and extracted samarium and/or europium solution, and
separating the solutions from one another. For example, the still a
further extracting agent can be chosen from
bis(2,4,4-trimethylpentyl) phosphinic acid, di-(2-ethylhexyl)
phosphoric acid and a mixture thereof.
[0161] For example, the process can further comprise reacting the
Sm-free solution and/or Eu-free solution with still another
extracting agent in order to substantially selectively extract
gadolinium, thereby obtaining a Gd-free solution and an extracted
gadolinium solution, and separating the solutions from one another.
For example, the still another extracting agent can be
8-hydroxyquinoline.
[0162] For example, the process can further comprise reacting the
Gd-free solution with yet another extracting agent in order to
substantially selectively extract yttrium, thereby obtaining a
Y-free solution and an extracted yttrium solution, and separating
the solutions from one another. For example, the yet another
extracting agent can be (2-ethylhexyl)phosphonic acid,
di-(2-ethylhexyl)phosphonic acid or a mixture thereof.
[0163] For example, the process can further comprise reacting the
Y-free solution with still yet another extracting agent in order to
substantially selectively extract dysprosium and/or erbium, thereby
obtaining a Dy-free solution and/or an Er-free solution and an
extracted dysprosium and/or erbium solution, and separating the
solutions from one another.
[0164] According to another example, the liquor can be reacted with
a first extracting agent in order to substantially selectively
extract gallium therefrom, thereby obtaining a Ga-free solution and
an extracted gallium solution, and separating the solutions from
one another.
[0165] For example, gallium in the liquor can be under the form of
GaCl.sub.3. For example, the first extracting agent can be
tri-butyl phosphate optionally in kerosene.
[0166] For example, the Ga-free solution can be reacted with a
precipitating agent for precipitating at least one rare earth
element present in the Ga-free solution, thereby obtaining a
precipitate containing the at least one rare earth element and
recovering the precipitate via a solid-liquid separation.
[0167] For example, the process can further comprise leaching the
precipitate with at least one acid so as to obtain a leach solution
comprising the at least one rare earth element. For example the
acid can be HCl. For example, the leach solution can be reacted
with a second extracting agent so as to substantially selectively
extract a first group of rare earth elements, thereby obtaining a
solution comprising the extracted rare earth elements of the first
group and a raffinate comprising a second group of rare earth
elements, and separating the solution from the raffinate. For
example, the first group can comprise yttrium and scandium. For
example, the second group can comprise cerium, neodynium, europium
and praseodymium. For example, the second extracting agent can be
chosen from di-(2-ethylhexyl)phosphoric acid and
2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.
[0168] For example, the process can further comprise reacting the
solution comprising the extracted rare earth elements of the first
group with HCl at least once so as to remove impurities therefrom.
For example, HCl can be at azeotropic concentration or it can be a
very high concentration such as 95 wt %.
[0169] For example, the process can further comprise stripping the
solution comprising the extracted rare earth elements of the first
group with at least one acid so as to obtain a first group strip
liquor. For example, the at least one acid can be HCl.
[0170] For example, the process can further comprise repeating at
least once the extraction with the second extracting agent.
[0171] For example, the first group strip liquor can be reacted
with a third extracting agent so as to substantially selectively
extracting at least one of scandium, erbium and dysprosium from the
first group strip liquor, thereby obtaining a solution comprising
the extracted at least one of scandium, erbium and dysprosium, and
an yttrium raffinate, and separating the solution from the
raffinate. For example, the third extracting agent can be tri-butyl
phosphate.
[0172] For example, the process can further comprise stripping the
solution comprising the extracted at least one of scandium, erbium
and dysprosium solution with at least one acid so as to obtain
another first group strip liquor. For example, the at least one
acid can be HCl.
[0173] For example, the another first group strip liquor can be
reacted with a fourth extracting agent so as to substantially
selectively extracting erbium and dysprosium from the another first
group strip liquor, thereby obtaining a solution comprising the
extracted erbium and dysprosium, and a scandium raffinate, and
separating the solution from the raffinate.
[0174] For example, the another first group strip liquor can be
reacted with a fourth extracting agent so as to substantially
selectively extracting scandium from the another first group strip
liquor, thereby obtaining a solution comprising the extracted
scandium, and raffinate comprising erbium and dysprosium, and
separating the solution from the raffinate.
[0175] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
by means of an adsorption on activated charcoal optionally modified
with tributyl phosphate or on a polyurethane polyether foam
(PUF).
[0176] For example, the at least one rare earth element can be
substantially selectively removed by means of a liquid-liquid
extraction. For example, the liquid-liquid extraction can be
carried out by using an extracting agent.
[0177] For example, the process can comprise selectively
precipitating at least two members chosen from the at least one
rare earth element that is in the form of ions, the second metal
ion and the first metal ion. For example, each of the members can
be precipitated separately or together.
[0178] According to another example, the processes can
comprise:
[0179] leaching the at least one material with HCl so as to obtain
the leachate comprising a first metal ion a second metal ion and
the at least one rare earth element, and the solid and separating
the leachate from the solid;
[0180] substantially selectively removing the second metal ion from
the leachate, thereby obtaining a composition comprising the first
metal ion, and the at least one rare earth element; and
[0181] substantially selectively at least partially removing the
first metal ion from the composition, thereby obtaining a liquor
comprising the at least one rare earth element.
[0182] According to another example, the processes can
comprise:
[0183] leaching the at least one material with HCl so as to obtain
the leachate comprising a first metal ion, a second metal ion, and
the at least one rare earth element, and the solid and separating
the leachate from the solid;
[0184] substantially selectively removing the second metal ion from
the leachate, thereby obtaining a composition comprising the first
metal ion, and the at least one rare earth element; and
[0185] substantially selectively at least partially removing the
first metal ion from the composition, thereby obtaining a liquor
comprising the at least one rare earth element.
[0186] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 2.5, then the second metal ion
can be precipitated at a pH of at least about 9.5, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then at least one scandium ion can be precipitated at a pH of about
7 to about 8.
[0187] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 1.5, then the second metal ion
can be precipitated at a pH of at least about 10.5, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then at least one scandium ion can be precipitated at a pH of about
7 to about 8.
[0188] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 1.5, then the second metal ion
can be precipitated at a pH of at least about 11, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then at least one scandium ion can be precipitated at a pH of about
7 to about 8.
[0189] For example, scandium can be precipitated from a by-product
generated during the process.
[0190] For example, scandium can be precipitated from a solution
generated during the process. For example, scandium can be
precipitated using HNO.sub.3.
[0191] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
by at least one technique chosen from ion exchange resin,
extraction by means of solvent(s) and adsorption.
[0192] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
by means of an ion exchange resin.
[0193] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
by means of a liquid-liquid extraction.
[0194] For example, the at least one rare earth element can be
substantially selectively precipitated, extracted and/or isolated
by means of an electrowinning process.
[0195] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 2.5, then the second metal ion
can be precipitated at a pH of at least about 9.5, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then and then the at least one rare earth element can be
substantially selectively extracted.
[0196] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 1.5, then the second metal ion
can be precipitated at a pH of at least about 10.5, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then the at least one rare earth element can be substantially
selectively extracted.
[0197] According to another example, the leaching can be carried
out at a pH of about 0.5 to about 1.5, then the second metal ion
can be precipitated at a pH of at least about 11, then the first
metal ion can be precipitated at a pH of about 8 to about 9, and
then the at least one rare earth element can be substantially
selectively extracted.
[0198] For example, the at least one material/acid ratio can be
about 1/10 in weight by volume.
[0199] According to another example, the processes can further
comprise at least one of
[0200] at least partially removing the second metal ion from the
leachate by substantially complexing the second metal ion with an
extracting agent;
[0201] selectively precipitating the second metal ion;
[0202] selectively precipitating the first metal ion; and
[0203] at least partially removing the first metal ion from the
leachate by substantially complexing the first metal ion with
another extracting agent.
[0204] According to another example, the processes comprise:
[0205] leaching the at least one material with HCl so as to obtain
a leachate comprising a first metal ion and a second metal ion and
a solid residue, and separating the leachate from the solid
residue;
[0206] at least partially removing the second metal ion from the
leachate by substantially selectively precipitating the second
metal ion by reacting the leachate with a base so as to obtain an
aqueous composition rich in the first metal ion and comprising the
at least one rare element and a precipitate, and removing the
precipitate from the composition;
[0207] purifying the aqueous composition by substantially
selectively precipitating the first metal ion, thereby obtaining
another composition comprising the at least one rare element and
another precipitate, removing the precipitate from the composition;
and
[0208] substantially selectively extracting the at least one rare
element from the another composition.
[0209] According to another example, the processes can
comprise:
[0210] leaching the at least one material with HCl so as to obtain
a leachate comprising a first metal ion and a second metal ion and
a solid residue, and separating the leachate from the solid
residue,
[0211] at least partially removing the second metal ion from the
leachate by substantially selectively precipitating the second
metal ion by reacting the leachate with a base so as to obtain an
aqueous composition rich in the first metal ion and comprising the
at least one rare element and a precipitate, and removing the
precipitate from the composition;
[0212] substantially selectively extracting the first metal ion
from the aqueous composition by means of a hollow fiber membrane,
or by a liquid-liquid extraction, and removing the extracted first
metal ion, thereby obtaining an aqueous composition depleted in the
first metal ion comprising the at least one rare element; and
[0213] substantially selectively extracting the at least one rare
element from the aqueous composition.
[0214] According to another example, the processes can
comprise:
[0215] leaching the at least one material with HCl so as to obtain
a leachate comprising a first metal ion and a second metal ion and
a solid residue, and separating the leachate from the solid
residue;
[0216] at least partially removing the second metal ion from the
leachate by substantially selectively complexing the second metal
ion with an extracting agent so as to obtain an aqueous composition
rich in the first metal ion comprising the at least one rare earth
element;
[0217] purifying the aqueous composition by substantially
selectively precipitating the first metal ion, thereby obtaining
another composition comprising the at least one rare element and
another precipitate, removing the precipitate from the composition;
and
[0218] substantially selectively extracting the at least one rare
element from the another composition.
[0219] According to another example, the processes can
comprise:
[0220] leaching the at least one material with HCl so as to obtain
a leachate comprising a first metal ion and a second metal ion and
a solid residue, and separating the leachate from the solid
residue;
[0221] at least partially removing the second metal ion from the
leachate by substantially selectively complexing the second metal
ion with an extracting agent so as to obtain an aqueous composition
rich in the first metal ion comprising the at least one rare earth
element;
[0222] substantially selectively extracting the first metal ion
from the aqueous composition by means of a hollow fiber membrane,
or by a liquid-liquid extraction, and removing the extracted first
metal ion, thereby obtaining an aqueous composition depleted in the
first metal ion comprising the at least one rare element; and
[0223] substantially selectively extracting the at least one rare
element from the aqueous composition depleted in the first metal
ion.
[0224] According to another example, the processes can
comprise:
[0225] leaching the at least one material with HCl so as to obtain
a leachate comprising a first metal ion and a second metal ion and
a solid residue, and separating the leachate from the solid
residue;
[0226] at least partially removing the first metal ion from the
leachate by substantially selectively precipitating the first metal
ion so as to obtain an aqueous composition rich in the second metal
ion comprising the at least one rare element and a precipitate, and
removing the precipitate from the composition;
[0227] substantially selectively precipitating the second metal ion
from the aqueous composition rich in the second metal ion, and
removing the precipitate therefrom, thereby obtaining thereby
obtaining an aqueous composition depleted in the second metal ion
and comprising the at least one rare element; and
[0228] substantially selectively extracting the at least one rare
element from the aqueous composition depleted in the second metal
ion.
[0229] For example, the first metal ion can comprises at least one
aluminum ion.
[0230] For example, the second metal ion can comprise at least one
iron ion.
[0231] For example, the at least one aluminum ion can be
precipitated under the form of AlCl.sub.3.6H.sub.2O in a
crystallizer, for example, by sparging gaseous HCl.
[0232] For example, the at least one aluminum ion can be
precipitated under the form of AlCl.sub.3.6H.sub.2O in a
crystallizer, for example, by adding HCl having a concentration of
about 26 to about 32 wt %.
[0233] For example, the at least one iron ion can be precipitated
under the form of Fe.sub.2O.sub.3 by means, for example, of an
hydrolysis.
[0234] For example, the aqueous composition rich in the first metal
ion can be purified by complexing the first metal ion with an
extracting agent so as to obtain a complex, separating the complex
form the composition and precipitating the first metal ion.
[0235] For example, the aqueous composition rich in the first metal
ion can be purified by complexing impurities contained in aqueous
composition rich in the first metal ion with an extracting agent,
at least partially removing the complexed impurities from the
composition and precipitating the first metal ion.
[0236] For example, the rare earth elements and rare metals
obtained by the processes of the present disclosure can be further
purified by means of a plasma torch. For example, the rare earth
elements and rare metals, once isolated, can be individually
injected into a plasma torch so as to further purify them. Examples
of such optional purification steps can be seen in FIGS. 4C, 4D,
5F, 5G and 5H.
[0237] For example, the acidic compositions of the present
disclosure can be treated by means of an ion exchange resin prior
to extraction of the at least one rare earth element and/or at
least rare metal. Examples of such steps can be seen, for example,
in FIGS. 3A, 4C, 5E and 5F.
[0238] For example, the acidic composition can be reacted with
Fe(0), thereby obtaining a composition having a reduced content in
Fe.sup.3+.
[0239] For example, the first rare earth element can be
scandium.
[0240] For example, the acidic composition can comprise at least
one rare metal.
[0241] For example, the processes can comprise reacting the
composition having the reduced content in the at least one iron ion
with the precipitating agent so as to substantially selectively
precipitate the first rare earth element and the first rare
metal.
[0242] For example, the first rare metal can be gallium.
[0243] For example, the precipitating agent can be chosen from
oxalic acid, NaOH, MgO, CaCO.sub.3 and mixtures thereof.
[0244] For example, the precipitating agent can be CaCO.sub.3.
[0245] For example, the first rare earth element and optionally the
first rare metal is/are substantially selectively precipitated by
maintaining a pH value below 2, or a pH at a value of about 1 to
about 2.
[0246] For example, the first rare earth element and optionally the
first rare metal is/are substantially selectively precipitated by
maintaining Redox potential of about +380 mV.
[0247] For example, the processes can comprise reacting the
composition having reduced content in the at least one iron ion
with the precipitating agent so as to substantially selectively
precipitate a first rare earth element and first rare metal that
are comprised in a so-formed precipitate, and recovering the
precipitate.
[0248] For example, the processes can further comprising leaching
the precipitate and obtaining a leaching solution.
[0249] For example, the precipitate can be leached with HCl.
[0250] For example, HCl can have a concentration of about 5 to
about 15 mol/L.
[0251] For example, the leaching solution can be further extracted
with an extracting agent so as to substantially selectively extract
the first rare earth element and the first rare metal and obtain a
loaded organic phase.
[0252] For example, the extracting agent can be tri-butyl
phosphate, tri-butyl phosphate in kerosene or tri-butyl phosphate
in kerosene and in the presence of isodecanol.
[0253] For example, the processes can further comprising scrubbing
the loaded organic phase with a scrubbing solution so as to recover
the first rare earth element and obtained a scrubbed organic
phase.
[0254] For example, the scrubbing solution can be an acidic aqueous
solution comprising HCl at a concentration of about 2 to about 12
mol/L.
[0255] For example, the scrubbing solution can be used in a ratio
scrubbing solution:loaded organic phase of about 1:1.
[0256] For example, the processes can further comprise stripping
the scrubbed organic phase with a stripping solution so as to
recover the first rare metal.
[0257] For example, the stripping solution can be water.
[0258] For example, the stripping solution can be used in a ratio
stripping solution:loaded organic phase of about 1:2.
[0259] For example, the composition having a reduced content in the
at least one iron ion can be reacted with the precipitating agent
so as to obtain a liquid comprising at least one further rare earth
element and the precipitate comprising the first rare earth element
and the first rare metal, the process further comprising separating
the liquid from the precipitate.
[0260] For example, the process can further comprise reacting the
liquid with another precipitating agent so as to obtain another
precipitate, and recovering the another precipitate.
[0261] For example, the liquid can be reacted with the another
precipitating agent at a pH of about 7.8 to about 8.2 or about 7.9
to about 8.1.
[0262] For example, the liquid can be reacted with the another
precipitating agent by maintaining Redox potential at about +340 mV
or at about +380 mV.
[0263] For example, the liquid can be reacted with the another
precipitating agent by maintaining a temperature of about 50 to
about 70.degree. C.
[0264] For example, the another precipitating agent can be chosen
from oxalic acid, NaOH, MgO, CaCO.sub.3 and mixtures thereof.
[0265] For example, the another precipitating agent can be
CaCO.sub.3.
[0266] For example, the processes can further comprise leaching the
another precipitate and obtaining a leaching solution comprising a
second rare earth element.
[0267] For example, the another precipitate can be leached with
HCl.
[0268] For example, the leaching solution comprising the second
rare earth element can be extracted with an extracting agent so as
to substantially selectively extract the second rare earth element
and obtain a loaded organic phase comprising the second rare earth
element and an aqueous phase comprising at least one light rare
earth element.
[0269] For example, the extracting agent di(ethylhexyl)phosphonic
acid or di(ethylhexyl)phosphonic acid in kerosene.
[0270] For example, the processes can further comprise at least
partially removing a third rare earth element from the loaded
organic phase comprising the second rare earth element.
[0271] For example, the processes can further comprise at least
partially removing a third rare earth element from the loaded
organic phase comprising the second rare earth element by treating
the loaded organic phase with an acidic scrubbing solution. For
example, the scrubbing solution can comprise 1 N HCl.
[0272] For example, the third rare earth element can cerium.
[0273] For example, the processes can further comprise treating the
loaded organic phase comprising the second rare earth element with
an acidic stripping solution so as to obtain a strip liquor
comprising the second rare earth element and recovering the strip
liquor. For example, the strip liquor can comprise 3.5 N HCl.
[0274] For example, the processes can comprise treating the strip
liquor comprising the second rare earth element with an extracting
agent so as to substantially selectively extract a fourth rare
earth element and optionally a fifth rare earth element from the
strip liquor and obtaining a raffinate comprising the second rare
earth element. For example, the extracting agent can be tri-butyl
phosphate or tri-butyl phosphate in kerosene.
[0275] For example, the fourth rare earth element can be
dysprosium.
[0276] For example, the fifth rare earth element is erbium.
[0277] For example, the processes can further comprise reacting an
organic phase comprising the fourth rare earth element and
optionally the fifth rare earth element with a strip solution so as
to obtain a strip liquor comprising the fifth rare earth element
and optionally the fifth rare earth element. For example, the strip
solution can be water.
[0278] For example, the second rare earth element is yttrium.
[0279] For example, the leaching solution comprising the second
rare earth element can be extracted with an extracting agent so as
to substantially selectively extract the second rare earth element
and obtain a loaded organic phase comprising the second rare earth
element and a raffinate comprising at least one light rare earth
element. For example, the extracting agent can be
di(ethylhexyl)phosphonic acid or di-(2-ethylhexyl) phosphoric
acid.
[0280] For example, the processes can further comprise at least
partially removing a third rare earth element from the loaded
organic phase comprising the second rare earth element.
[0281] For example, the processes can further comprise at least
partially removing a third rare earth element from the loaded
organic phase comprising the second rare earth element by treating
the loaded organic phase with an acidic scrubbing solution. For
example, the scrubbing solution comprises about 1 N to about 2 N
HCl.
[0282] For example, the processes can further comprise treating the
loaded organic phase comprising the second rare earth element with
a stripping solution so as to obtain a strip liquor comprising the
second rare earth element. The stripping solution can comprise
about 3 M to about 4M HCl.
[0283] For example, the strip liquor comprising the second rare
earth element can be extracted with an extracting agent so as to
remove a fourth rare earth element and optionally a fifth rare
earth element, thereby obtaining a raffinate comprising the second
rare earth element and a loaded organic phase comprising the fourth
rare earth element and optionally the fifth rare earth element. For
example, the extracting agent is tri-butyl phosphate or tri-butyl
phosphate in kerosene.
[0284] For example, the processes can comprise recovering the
raffinate comprising the second rare earth element.
[0285] For example, the second rare earth element can be
yttrium.
[0286] For example, the fourth rare earth element can be
dysprosium.
[0287] For example, the fifth rare earth element can be erbium.
[0288] For example, the processes can further comprise reacting the
loaded organic phase comprising the fourth rare earth element and
the fifth rare earth element with a stripping solution so as to
obtain strip liquor comprising the fourth rare earth element and
the fifth rare earth element. For example, the stripping solution
can be water.
[0289] For example, the processes can further comprise reacting the
strip liquor with an extracting agent so as to substantially
selectively extract the fifth rare earth element from the strop
liquor, thereby obtaining a raffinate comprising the fourth rare
earth element and a loaded organic phase comprising the fifth rare
earth element. For example, the extracting agent can be
di(ethylhexyl)phosphonic acid or di-(2-ethylhexyl) phosphoric
acid.
[0290] For example, the processes can further comprise separating
the raffinate from the loaded organic phase comprising the fifth
rare earth element, treating the loaded organic phase with a
scrubbing solution so as to remove impurities therefrom and then
treating the loaded organic phase with a stripping solution so as
to obtain a strip liquor comprising the fifth rare earth element.
For example, the scrubbing solution can comprise about 2 M to about
4 M HCl.
[0291] For example, the raffinate can be reacted with an oxidation
agent so as to oxidize the third rare earth element. For example,
the oxidation agent can comprise sodium hypochlorite. For example,
the raffinate can be reacted with an oxidation agent at a pH of
about 0.5 to about 1.5.
[0292] For example, the processes can further comprise removing,
from the raffinate, the oxidized third rare earth element that is
under the form of a precipitate, thereby obtaining a filtrate
comprising a sixth rare earth element.
[0293] For example, the processes can further comprise reacting the
filtrate with an extracting agent so as to substantially
selectively extracting the sixth rare earth element from the
filtrate, thereby obtaining a loaded organic phase comprising the
sixth rare earth element and another raffinate comprising a seventh
rare earth element and an eight rare earth element, and separating
the loaded organic phase comprising the sixth rare earth element
from the raffinate. For example, the extracting agent can be
di(ethylhexyl)phosphonic acid or di-(2-ethylhexyl) phosphoric
acid.
[0294] For example, the processes can further comprise treating the
loaded organic phase with a scrubbing solution so as to remove
impurities therefrom and then treating the loaded organic phase
with a stripping solution so as to obtain a strip liquor comprising
the sixth rare earth element. For example, the scrubbing solution
can comprise about 0.5 M to about 1.5 M HCl. For example, the
stripping solution can comprise about 2 M to about 3 M HCl.
[0295] For example, the sixth rare earth element can europium.
[0296] For example, the seventh rare earth element can be
praseodymium.
[0297] For example, the eighth rare earth element can be
neodymium.
[0298] For example, the processes can further comprise reducing the
sixth rare earth element by means of a reducing agent. For example,
the reducing agent can be zinc (0).
[0299] For example, the processes can further comprise reacting the
sixth rare earth element with sodium sulphate so as to obtain a
sulphate derivative thereof under the form of a precipitate and
recovering the precipitate.
[0300] For example, the processes can further comprise reacting the
raffinate comprising the seventh rare earth element and the eight
rare earth element with an extracting agent so as to substantially
selectively extracting the eight rare earth element from the
raffinate, thereby obtaining a loaded organic phase comprising the
eight rare earth element a raffinate comprising the seventh rare
earth element, and separating the loaded organic phase comprising
the eight rare earth element from the raffinate. For example, the
extracting agent can be di(ethylhexyl)phosphonic acid or
di-(2-ethylhexyl) phosphoric acid.
[0301] For example, the processes can further comprise treating the
loaded organic phase with a scrubbing solution so as to remove
impurities therefrom and then treating the loaded organic phase
with a stripping solution so as to obtain a strip liquor comprising
the eight rare earth element. For example the scrubbing solution
can comprise about 2 M to about 3 M HCl. For example, the stripping
solution can comprise about 3 M to about 4 M HCl.
[0302] For example, the processes can further comprise,
pre-treating or treating the acidic composition with an ion
exchange resin so as to remove impurities.
[0303] For example, the processes can further comprise, before
extracting at least one rare earth element and optionally at least
one rare metal from the acidic composition, treating the acidic
composition with an ion exchange resin so as to at least partially
remove impurities therefrom.
[0304] For example, the processes can further comprise treating the
at least one rare earth element and optionally the at least one
rare metal extracted by the process by means of a plasma torch so
as to further purify the at least one rare earth element and
optionally the at least one rare metal.
[0305] According to another example the processes can comprise:
[0306] 1--leaching argillite with at least one acid (for example a
solution of HCl or gaseous HCl (for example at pH of about 0.5 to
about 1.5 or about 0.8 to about 1.2). The leaching can also be
carried out under pressure;
[0307] 2--removing iron by ionic precipitation by raising th at pH
of about 10 to about 12 or about 11 to about 12 (or extracting it
with extracting agents) and filtering out all non-soluble
hydroxides;
[0308] 3--precipitating aluminum at a pH of about 7.5 to about 9.0
or about 7.8 to about 8.2 and filtering aluminium hydroxide as a
solid;
[0309] 4--optionally purifying aluminum (Al(OH).sub.3) using at
least one of a liquid-liquid extraction, a membrane and an
extracting agent suitable for complexing aluminum ions; and
[0310] 5--precipitating, extracting and/or isolating at least one
rare earth element can be carried out after at least one of steps
1, 2, 3 and 4.
[0311] For more details and explanations regarding at least certain
portions of steps 1 to 4, WO2008141423, which is hereby
incorporated by reference in its entirety, can be referred to.
[0312] According to another example the processes can comprise:
[0313] 1--leaching argillite with an acid (for example a solution
of HCl 18-32 wt %. The leaching can also be carried out under
pressure such as about 350 KPag to about 500 KPag during about 4 to
about 7 hours;
[0314] 2--removing iron by ionic precipitation by raising the at pH
of about 10 to about 12 or about 11 to about 12 (or extracting it
with extracting agents) and filtering out all non-soluble
hydroxides;
[0315] 3--precipitating aluminum at a pH of about 7.5 to about 9.0
or about 7.8 to about 8.2 and filtering aluminium hydroxide as a
solid;
[0316] 4--optionally purifying aluminum (Al(OH).sub.3) using at
least one of a liquid-liquid extraction, a membrane and an
extracting agent suitable for complexing aluminum ions; and
[0317] 5--precipitating, extracting and/or isolating at least one
rare earth element can be carried out after at least one of steps
1, 2, 3 and 4.
[0318] According to another example as shown in FIG. 1, the
processes can involve the following steps (the reference numbers in
FIG. 1 correspond to the following steps):
[0319] 1--The aluminum-containing material is reduced to an average
particle size of about 50 to about 80 .mu.m.
[0320] 2--The reduced and classified material is treated with
hydrochloric acid which allows for dissolving, under a
predetermined temperature and pressure, the aluminum with other
elements like iron, magnesium and other metals including rare
earth. The silica (and optionally titanium) remains totally
undissolved.
[0321] 3--The mother liquor from the leaching step then undergoes a
separation, a cleaning stage in order to separate the purified
silica from the metal chloride in solution. The purified silica can
then undergo one or two additional leaching stages (for example at
a temperature of about 150 to about 160.degree. C.) so as to
increase the purity of silica above 99.9%. TiO.sub.2 contained in
silica can be separated from silica through a leach made by using
HCl and MgCl.sub.2 as a lixiviant composition.
[0322] 4--The spent acid (leachate) obtained from step 1 is then
brought up in concentration with dry and highly concentrated
gaseous hydrogen chloride by sparging this one into a crystallizer.
This results into the crystallization of aluminum chloride
hexahydrate (precipitate) with a minimum of other impurities.
Depending on the concentration of iron chloride at this stage,
further crystallization step(s) can be required. The precipitate is
then separated from the liquid.
[0323] 5--The aluminum chloride hexahydrate is then calcined (for
example by means of a rotary kiln, fluid bed, etc) at high
temperature in order to obtain the desired alumina. Highly
concentrated gaseous hydrogen chloride is then recovered and excess
is brought in aqueous form to the highest concentration possible so
as to be used (recycled) in the acid leaching step. Acid can also
be directly sent in gas phase to the acid purification stage to
increase HCl concentration from about 30 wt % to about 95 wt %.
This can be done, for example, during drying stage or
distillation.
[0324] 6--Iron chloride, rare earth elements and rare metals (the
liquid obtained from step 4) is then pre-concentrated and
hydrolyzed at low temperature in view of the Fe.sub.2O.sub.3
(hematite form) extraction and acid recovery from its hydrolysis.
All heat recovery from the calcination step (step 5), the leaching
part exothermic reaction (step 1) and other section of the process
is being recovered into the pre-concentrator.
[0325] 10--After the removal of hematite and internal recirculation
to crystallizer, a solution rich in rare earth elements can be
processed by using any one of the processes described in the
present disclosure for recovering rare earth elements from
aluminum-containing materials. For example, the recovered rare
earth elements can be in various forms such oxides, chlorides,
hydroxides etc. As previously indicated in the present disclosure,
the expression "rare earth element" can also encompass "rare metal"
and thus, in step 10, rare metals can also be recovered. For
example, rare metals can be under the form of rare metals oxides.
Thus, in FIGS. 1 and 2, the step 10 can be, for example, the
processes shown in FIG. 3 or in FIGS. 4a and 4b.
Other non-hydrolyzable metal chlorides (Me-Cl) such as MgCl.sub.2
and others then undergo the following steps:
[0326] 7--The solution rich in magnesium chloride and other
non-hydrolyzable products at low temperature is then brought up in
concentration with dry and highly concentrated gaseous hydrogen
chloride by sparging it into a crystallizer. This results into the
precipitation of magnesium chloride as an hexahydrate.
[0327] 8--Magnesium chloride hexahydrate is then calcined (either
through a rotary kiln, fluid bed, etc.) and hydrochloric acid at
very high concentration is thus regenerated and brought back to the
leaching step.
[0328] 9--Other Me-Cl undergo a standard pyrohydrolysis step where
mixed oxides can be produced and hydrochloric acid at the
azeotropic point (20.2% wt.) is regenerated.
[0329] For example, the liquid can be concentrated to a
concentrated liquid having an iron chloride concentration of at
least 26% by weight; and then the iron chloride can be hydrolyzed
at a temperature of about 155 to about 350.degree. C. while
maintaining a ferric chloride concentration at a level of at least
65% by weight, to generate a composition comprising a liquid and
precipitated hematite, and recovering the hematite.
[0330] For example, the liquid can be concentrated to a
concentrated liquid having an iron chloride concentration of at
least 26% by weight; and then the iron chloride can be hydrolyzed
at a temperature of about 155 to about 350.degree. C. while
maintaining a ferric chloride concentration at a level of at least
65% by weight, to generate a composition comprising a liquid and
precipitated hematite; recovering the hematite; and recovering rare
earths from the liquid. For example, the process can further
comprise, after recovery of the rare earths, reacting the liquid
with HCl so as to cause precipitation of MgCl.sub.2, and recovering
same.
[0331] As previously indicated, various aluminum-containing
materials can be used as starting material of the processes
disclosed in the present disclosure. Examples with clays and
bauxite have been carried out. However, the person skilled in the
art will understand that the continuous processes can handle high
percentages of silica (>55%) and impurities as well as
relatively low percentages of aluminum (for example as low as about
15%) and still being economically and technically viable.
Satisfactory yields can be obtained (>93-95%) on Al.sub.2O.sub.3
and greater than 75%, 85% or 90% on rare earth elements and rare
metals. No pre-thermal treatment in most cases are required. The
processes disclosed in the present disclosure involve special
techniques on leaching and acid recovery at very high strength,
thereby offering several advantages over alkaline processes. No
solid residues as per alkaline processes are generated by that
process which benefits from the totally integrated HCl recovery
loop.
[0332] In step 1 the mineral, whether or not thermally treated is
crushed, milled, dried and classified to have an average particle
size of about 50 to about 80 .mu.m.
[0333] In step 2, the milled raw material is introduced into the
reactor and will undergo the leaching phase.
[0334] The leaching hydrochloric acid used in step 2 is a recycled
or regenerated acid from steps 5, 6, 8 and 9 and its concentration
can vary from 15% to 45% weight. percent. Higher concentration can
be obtained using a membrane separation, a cryogenic and/or high
pressure approach. The acid leaching can be carried out under
pressure and at temperature close to its boiling point thus,
allowing a minimal digestion time and extended reaction extent
(90%-100%). Leaching (step 2) can be accomplished in a
semi-continuous mode where spent acid with residual free
hydrochloric acid is replaced by highly concentrated acid at a
certain stage of the reaction or allowing a reduced acid/mineral
ratio, thereby reducing reaction time and improving reaction
kinetics. For example, kinetic constant k can be: 0.5-0.75 g/moleL,
or 0.75-1.10 g/moleL.
[0335] As previously indicated, alkali metals, iron, magnesium,
calcium, potassium, rare earth elements and other elements will
also be in a chloride form at different stages. Silica and titanium
can remain undissolved and will undergo (step 3) a liquid/solid
separation and cleaning stage. The processes of the present
disclosure tend to recover maximum amount of free hydrochloric acid
left and chlorides in solution in order to maximize hydrochloric
acid recovery yield, using techniques such as rake classifying,
filtration with band filters, centrifugation, and others. Mother
liquor free of silica is then named as spent acid (various metal
chlorides and water) and goes to the crystallization step (step
4).
[0336] In step 4, the spent acid (or leachate) with a substantial
amount of aluminum chloride is then saturated with dry and highly
concentrated gaseous hydrogen chloride obtained or recycled from
step 5, which results in the precipitate of aluminum chloride
hexahydrate (AlCl.sub.3.6H.sub.2O). The precipitate retained is
then filtered or centrifuged before being fed to the calcination
stage (step 5). The remaining of the spent acid from step 4 is then
processed to acid recovery system (steps 6 to 8) where pure
secondary products will be obtained.
[0337] In step 5, aluminum oxide (alumina) is directly obtained
from high temperature conditions. The highly concentrated hydrogen
chloride in gaseous form obtained can be fed to steps 4 and 7 for
crystallization. The excess hydrogen chloride is absorbed and used
as regenerated acid to the leaching step 2 as highly concentrated
acid, higher than the concentration at the azeotropic point
(>20.2%). For example, such a concentration can be about 25 to
about 45 weight % or between 25 and 36 weight %. Acid can also be
redirected in gas phase directly (>30 wt %) to acid
purification.
[0338] After step 4, various chlorides derivatives of (mainly iron
chlorides, magnesium chloride and rare earth element in the form of
chlorides) are next subjected to an iron extraction step. Such a
step can be carried out for example by using the technology
disclosed in WO 2009/153321, which is hereby incorporated by
reference in its entirety. Moreover, hematite can be seeded for
crystal growth.
[0339] In step 6, a hydrolysis at low temperature (155-350.degree.
C.) is carried out and pure Fe.sub.2O.sub.3 (hematite) is being
produced and hydrochloric acid of at least 15% concentration is
being regenerated. The method as described in WO 2009/153321 is
processing the solution of ferrous chloride and ferric chloride,
possible mixtures thereof, and free hydrochloric acid through a
series of steps pre-concentration step, oxidation step where
ferrous chloride is oxidized into ferric form, and finally through
an hydrolysis step into an operational unit called hydrolyser where
the ferric chloride concentration is maintained at 65 weight % to
generate a rich gas stream where concentration ensures a hydrogen
chloride concentration of 15-20.2% and a pure hematite that will
undergo a physical separation step. Latent heat of condensation is
recovered to the pre-concentration and used as the heating input
with excess heat from the calcination stage (step 5).
[0340] The mother liquor left from the hydrolyser (step 6), after
iron removal, is rich in other non-hydrolysable elements and mainly
comprises magnesium chloride or possible mixture of other elements
(various chlorides) and rare earth elements.
[0341] Rare earth elements in form of chlorides are highly
concentrated in percentage into the hydrolyser operational unit
(step 6) and are extracted from the mother liquor (step 10) where
the processes defined in the present disclosure for recovering rare
earth elements from aluminum-containing materials can be employed.
For example, rare earth elements under various forms can thus be
extracted. For example, it can be under the form of oxides. REO.
The processes of the present disclosure for recovering rare earth
elements can allow, for example, to concentrate to a high
concentration the following rare earth elements, within the
hydrolyser recirculation loop: scandium (Sc), galium (Ga), yttrium
(Y), dysperosium (Dy), cerium (Ce), praseodynium (Pr), neodynium
(Nd), europium (Eu), samarium (Sm), gadolinium (Gd), lanthanum
(La), erbium (Er). Of course, the at least one rare earth element
that will be recovered will depend upon the nature of the starting
material (aluminum-containing material).
[0342] The spent acid liquor from steps 6 and 10 rich in value
added metals, mainly magnesium, is processed to step 7. The
solution is saturated with dry and highly concentrated gaseous
hydrogen chloride from step 5, which results in the precipitation
of magnesium chloride hexahydrate. The precipitate retained, is fed
to a calcination stage step 8 where pure MgO (>98% wt.) is
obtained and highly concentrated hydrochloric acid (for example of
at least 38%) is regenerated and diverted to the leaching step
(step 2). An alternative route for step 7 is using dry gaseous
hydrochloric acid from step 8.
[0343] In step 9, metal chlorides unconverted are processed to a
pyrohydrolysis step (700-900.degree. C.) to generate mixed oxides
and where hydrochloric acid from 15-20.2% wt. concentration can be
recovered.
[0344] According to another example as shown in FIG. 2, the
processes can be similar to the example shown in FIG. 1 but can
comprise some variants as below discussed.
[0345] In fact, as shown in FIG. 2, the process can comprise (after
step 6 or just before step 10) an internal recirculation back to
the crystallization step 4. In such a case, The mother liquor from
the hydrolyser (step 6) can be recirculated fully or partially to
the crystallization of step 4 where a concentration increase will
occur with respect to the non-hydrolyzable elements including rare
earth elements.
[0346] Such a step can be useful for significantly increasing the
concentration of rare earth elements, thereby facilitating their
extraction in step 10.
[0347] With respect to step 7, the solution rich in magnesium
chloride and other non-hydrolyzable products at low temperature is,
as previously discussed, then brought up in concentration with dry
and highly concentrated gaseous hydrogen chloride by sparging it
into a crystallizer. This can result into the precipitation of
magnesium chloride as an hexahydrate (for example after sodium and
potassium chloride removal).
[0348] As shown in FIG. 2, an extra step 11 can be added. Sodium
chloride can undergo a chemical reaction with sulfuric acid so as
to obtain sodium sulfate and regenerate hydrochloric acid at the
azeotropic point. Potassium chloride can undergo a chemical
reaction with sulfuric acid so as to obtain potassium sulfate and
regenerate hydrochloric acid at the azeotropic point.
[0349] The process shown in FIG. 2A is similar to the process shown
in FIG. 2, with the exception of the fact that it comprises an
additional step between stage 12 and stage 2 for using the purified
acid obtained.
[0350] The process shown in FIG. 2B is similar to the process shown
in FIG. 2, with the exception of the fact that it comprises an
additional step of SiO.sub.2 purification by separating TiO.sub.2
therefrom and an optional step 5a in which a low temperature
decomposition of alumina chloride can be carried out.
[0351] Between steps 6 and 10 and/or steps 7 and 10 in FIGS. 1 and
2, it is possible to further purify the composition comprising rare
earth elements and/or rare metals. In fact, such a composition can
be treated with an ion exchange column so as to remove impurities
that are not rare earth elements and rare metals. For example, such
a composition that comprises chlorides of rare earth elements
and/or rare metals will be treated so as to remove impurities such
as iron, aluminum or other metals. Then, once the treatment with
such columns is done, the earth elements and/or rare metals can be
extracted as indicated in the processes of the present
disclosure.
[0352] Certain examples are hereby provided in the present
disclosure for substantially selectively recovering, precipitating,
extracting and/or isolating at least one rare earth element. This
can be done, for example from the leachate and/or the precipitate
and any other downstream derivatives, solutions, precipitates,
compositions or liquors.
[0353] For example, recovering, precipitating, extracting and/or
isolating at least one rare earth element can be carried out by:
[0354] precipitating least one rare earth element (for example at a
pH of about 6 to about 8, 7 to about 8, or 7 to about 7.5); [0355]
using an ion exchange resin (for example, as described in U.S. Pat.
No. 4,816,233 (hereby incorporated by reference in its entirety));
[0356] extraction by means of solvent(s) (for example a
liquid-liquid extraction can be carried out using di-(2-ethylhexyl)
phosphoric acid (HDEHP (also called DEHPA or D2EHPA)),
mono(2-ethylhexyl)2-ethylhexyl phosphonate (HEH/EHP), octyl phenyl
phosphate (OPAP), 2-ethylhexylphosphonic acid mono-2-ethylhexyl
ester (PC88A) and optionally toluene (for example as described in
Kao et al. in Chemical Engineering Journal, Volume 119, Issues 2-3,
Jun. 15, 2006, pages 167-174 (hereby incorporated by reference in
its entirety)) or by means of extracted using an alkyl phosphate
(for example as described in U.S. Pat. No. 3,013,859 (hereby
incorporated by reference in its entirety)); [0357] using an
extracting agent (for example using
bis(2,4,4-trimethylpentyl)monothiophosphinic acid or a derivative
thereof); [0358] adsorption on activated charcoal (activated carbon
adsorption) optionally modified with tributyl phosphate or on a
polyurethane polyether foam (PUF); (for example as described in
Zhou et al. in RARE METALS, Vol. 27, No. 3, 2008, p 223-227 (hereby
incorporated by reference in its entirety)) [0359] extraction with
hollow fiber membranes; and [0360] using an electrowinning
technology (for example as described in US 2004/0042945 (hereby
incorporated by reference in its entirety)).
[0361] For example, scandium can be precipitated (optionally using
HNO.sub.3) from a residual solution generated during the process
(for example when iron is precipitated and/or when aluminum is
precipitated).
[0362] For example, when substantially selectively precipitating,
extracting and/or isolating at least one rare earth element from
the leachate and/or the precipitate and any other downstream
derivatives, various sequences can be carried out i.e. depending on
the nature of the starting material and the rare earth elements
present, a given rare earth element can be more easily extracted
before or after another given rare earth element.
[0363] For example, as shown in FIG. 3, in a mixture or liquor
comprising HCl, water and rare elements in the form of chlorides,
the mixture can be treated with an extracting agent in order to
extract GaCl.sub.3 therefrom, thereby obtaining a Ga-free solution.
Such an extracting agent can be, for example, octyl phenyl
phosphate (OPAP) or 2-ethylhexylphosphonic acid mono-2-ethylhexyl
ester (PC88A) and toluene. GaCl.sub.3 can then be precipitated and
then converted into Ga.sub.2O.sub.3 by heating it, while,
optionally recovering HCl.
[0364] Then, the Ga-free solution can be treated with an extracting
agent (for example SME 529.TM., tri-butyl phosphate or
di-isoamylmethyl phosphonate, di-(2-ethylhexyl) phosphoric acid,
7-(4-ethyl-1-methyloctyl)-8-hydroxyquinoline (Kelex 100.TM.) in
n-heptane with the addition of 10% n-decanol.) for substantially
selectively extracting cerium chloride therefrom so as to obtain a
Ce-free solution. CeCl.sub.3 can be eventually converted into
Ce.sub.2O.sub.3, while, optionally recovering HCl.
[0365] Then, the Ce-free solution can be treated with an extracting
agent such as di-(2-ethylhexyl) phosphoric acid or
di-(2-ethylhexyl) phosphinic acid so as substantially selectively
extract Sc and to provide a Sc-free solution. The extracted Sc can
be treated with an oxidizer (such as NaOH) so as to provide
Sc.sub.2O.sub.3.
[0366] Then, the various remaining rare earth elements (Pr, Nd, Sm,
Eu, La, Gd, Y, Dy, Er etc.) in the Sc-free solution can be
extracted in different possible orders.
[0367] For example, it has to be noted that the process schematized
in FIG. 3 can be used as a component of various other processes
such as the process schematized in FIG. 1 or in FIG. 2. For
example, the step 10 of FIGS. 1 and 2 can be the process
schematized in FIG. 3.
[0368] The process shown in FIG. 3A is similar to the process shown
in FIG. 3, with the exception that it comprises an extra
purification step by using an ion exchange column.
[0369] For example, as shown in FIGS. 4A and 4B, the process for
extracting rare earth elements can comprise:
[0370] Ferric reduction to ferrous using iron;
[0371] Separation of gallium from the ferrous chloride
solution;
[0372] Precipitation and pre-concentration of rare earth elements
from the raffinate;
[0373] Re-leaching and fractioning of the rare earth elements into
light (LRE) and heavy (HRE) groups;
[0374] Separation of yttrium from scandium and heavy rare earth
elements;
[0375] Separation of scandium and heavy rare earth elements;
and
[0376] Leaching with low concentration acid at atmospheric
pressure
[0377] The processes shown in FIGS. 4C and 4D are similar to the
processes shown in FIGS. 4A and 4B, with the exception that they
can comprise an extra purification step by using an ion exchange
column, an optional plasma purification step, an extra acid
regenerations step, and an extra calcination step.
[0378] The reduction of ferric to ferrous with a reducing agent
(such as metallic iron, starch) can be used so as to prevent iron
coextraction or iron precipitation. The reaction time can be very
short and it can generate heat. The general chemical reaction for
reduction of iron(III) is shown below.
2Fe.sup.3++Fe.sup.0+HCl->3Fe.sup.2+H.sub.2
[0379] As long as the feed solution is held under reduced
conditions, no ferric will be present in this liquid solution. As
shown in FIGS. 4a and 4b, The ferric chloride feed solution 101 can
be fed to an agitated reaction tank and a reducing agent (for
example metallic iron 102) can added so as to allow for converting
ferric chloride to ferrous chloride (see "Ferric Removal"). After a
solid-liquid separation (s/I separation), the resulting filtrate
103 can be further treated in a gallium extraction circuit. A
filter cake, containing solid material and iron, can be dewatered
and the resulting slurry can then be prepared for disposal.
[0380] Gallium can then be extracted with an organic solution
containing an extracting agent (for example tri-butyl phosphate
(TBP) dissolved in kerosene) (see "Gallium Recovery"). The rare
earth elements and iron can thus be left in the raffinate. The
extraction can vary as a function of the chloride ion
concentration. For example, the higher chloride ion concentration,
the stronger tendency for gallium complex formation and the better
extraction.
[0381] For example, for gallium (recovery from hydrochloric acid
solutions, reagents such as tri-butyl phosphate or tertiary amines
(e.g. Alamine 336) can be used. For example, when increasing
hydrochloric acid (HCl) concentration, gallium extraction can rise
to a maximum and can then decrease again. For example, HCl
concentration can be increased up to about 4 M HCl for the gallium
extraction. Under these conditions, gallium can be present in the
form of HGaCl.sub.4 complex and TBP extracted gallium as a
trisolvate (HGaCl.sub.4*3TBP) (for example when the extracting
agent is TBP).
[0382] The rise in extraction with increasing acidity is due to the
additional formation of HGaCl.sub.4. The chemical reaction is shown
below.
GaCl.sub.4.sup.-+H++nTBP->HGaCl.sub.4*(TBP).sub.n
[0383] For low acidity or neutral solutions, the extracted species
is GaCl.sub.3 in the form of a hydrated solvate.
GaCl.sub.3+mH.sub.20+nTBP->GaCl.sub.3*(H.sub.20)m*(TBP)n
[0384] Co-extracted iron, accumulated in the organic phase can be
scrubbed with hydrochloric acid (see "Gallium Strip Liquor"). The
resulting organic solution, containing gallium can be fed to a
stripping circuit where gallium is stripped with water 104. The
raffinate 106, containing ferrous chloride and the rare earth
elements, can then be fed to the rare earth precipitation section.
The final strip liquor 105 contains gallium.
[0385] For example, oxalate precipitation of rare earth elements
result in very low solubility of the compounds in aqueous solution.
The precipitation of rare earth oxalates can be achieved by
addition of a precipitation reagent 107. For example, oxalic acid
107 can be used for the precipitation. For example, precipitating
agent that are effective for precipitating rare earth elements of
the trivalent (such as oxalate (from oxalic acid)) can be used. For
example, such precipitating agents can have provide a very low
solubility in aqueous solution to so-formed precipitate.
[0386] The precipitation reaction of trivalent rare earth elements
in aqueous solution is according to the following equation:
2REE.sup.3++3
H.sub.2C.sub.2O.sub.4+xH.sub.2O->[REE.sub.2(C.sub.2O.sub.4).sub.3*xH.s-
ub.2O].sub.s+6H+
[0387] An overflow from the primary rare earth elements
precipitation 109 can be fed to a ferrous treatment circuit. After
filtration, the filter cake, containing the rare earth elements,
can be fed to a washing and dewatering unit. A resulting slurry 108
can then be prepared for re-leaching (see "REE-Re-leaching").
Re-leaching of the rare earth filter cake can be carried out using
hydrochloric acid 110.
[0388] From a pre-concentrated and pH adjusted chloride solution
111, that contains for example about 150 to about 250 g/L, rare
earth elements yttrium, scandium and the heavy rare earth (HRE) are
extracted (see "Primary REE Recovery") with an extracting agent
(for example (di-(2-ethylhexyl)phosphoric acid (D2EHPA) or
2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A (also
called Ionquest.TM. 801) in kerosene)). Scandium, the other HRE and
also yttrium can be extracted and leaving the light rare earth
elements (LRE) in a raffinate 113.
[0389] A loaded organic phase can then be selectively scrubbed with
hydrochloric acid (2 M HCl) to remove the co-extracted LRE. A
secondary scrubbing section can remove europium by using weak
hydrochloric acid (1 to 1.5 M HCl). The extract, containing
yttrium, scandium and the HRE, can then be stripped with strong
acid (3.5 M HCl) 112.
[0390] The HRE strip liquor 114, containing yttrium and scandium,
can be treated further to obtain more than 90% Y.sub.2O.sub.3 and
Sc.sub.2O.sub.3 in a first circuit of a double solvent extraction
purification process. In a first step, the aqueous solution,
containing about 25 g/L (of rare earth elements in the form of
oxides) and 0.4 M HCl, can be brought into contact with an
extracting agent (for example (di-(2-ethylhexyl)phosphoric acid
(D2EHPA) or 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester
(PC88A (also called Ionquest.TM. 801) in kerosene)) (see "Secondary
REE Recovery"). The loaded organic phase is then scrubbed with
diluted hydrochloric acid. Scandium, yttrium and HRE can be
extracted by the reagent and finally stripped with strong
hydrochloric acid 115 at a high oxide/acid ratio. The final strip
liquor would have a concentration in rare earth elements oxides of
about 40 g/L and about 1 M HCl. This solution is partially
neutralized.
[0391] This pre-treated strip liquor 116 can be further extracted
with an extracting agent (for example tri-butyl phosphate (TBP) in
kerosene). The treatment can be done in a multi stage procedure,
and ending up in a final stripping of the loaded organic with water
117. All HRE and scandium can thus extracted, leaving yttrium in a
raffinate 119. A final strip liquor 118, containing HRE, forms the
source for further separation of scandium and heavy rare earth. In
order to do so, various possible extracting agents can be used such
as di-(2-ethylhexyl) phosphoric acid.
[0392] Yttrium can also removed from the strip liquor obtained from
the primary extraction step. For example, the separation can be
carried out at pH 3 after addition of ammonium thiocyanate as
complexion reagent. The procedure can results in an yttrium rich
raffinate, when extracting heavy rare earth elements with tri-butyl
phosphate, Alamine 336 or Aliquat 336.
[0393] The separation of scandium from other HRE, (for example
dysprosium and erbium) can be carried out using a further solvent
extraction purification circuit, similar to the yttrium separation
and purification process and previously described. Thus, the
extracting agent can be the same or a different one (for example
(di-(2-ethylhexyl)phosphoric acid (D2EHPA); 2-ethylhexylphosphonic
acid mono-2-ethylhexyl ester (PC88A (also called Ionquese.TM. 801)
in kerosene) or Bis (2,4,4-Trimethylpentyl) Phosphonic acid
(Ionquest.TM. 290)), the strip solution 120 can be the same than
117, thereby providing a scandium raffinate 121 and a strip liquor
122 comprising europium and erbium.
[0394] As an alternative, yttrium can be extracted as described in
U.S. Pat. No. 3,751,553 (hereby incorporated by reference in its
entirety). In fact, yttrium can be extracted starting from a
xenotime concentrate. It can be done by using three solvent
extraction circuits. In a first step, DEHPA can be used to separate
yttrium. In a second step, tri (caprylmethyl) ammonium nitrate
(Aliquat 336) can be used to extract and separate cerium and leave
yttrium in the raffinate. In a third step, Tm, Yb, and Lu can be
extracted by means of tri (caprylmethyl) ammonium thio cyanate. In
this extraction loop, yttrium behaves like a cerium element. From
this step, high-purity of yttrium oxide can be obtained.
[0395] According to another alternative, yttrium oxide can be
extracted in two steps i.e. tri (caprylmethyl) ammonium nitrate can
be used to separate a mixture La--Er/Y--Lu and then, a purification
of yttrium is carried out using versatic acid.
[0396] Solvent extraction is a selective separation procedure for
isolating and concentrating valuable elements from an aqueous
solution with the aid of an organic solution. In the procedure the
aqueous solution containing the element of interest, often at a low
concentration and together with other dissolved substances
(pollutants), is mixed (extraction) with an organic solvent
containing a reagent. The element of interest reacts with the
reagent to form a chemical compound that is more soluble in the
organic than in the aqueous solution. As a consequence, the element
of interest is transferred to the organic solution.
[0397] Subsequently, in order to recover the extracted substance,
the organic solution is mixed (stripping) with an aqueous solution
whose composition is such that the chemical compound between the
element and the reagent is split and, thus, the element is
recovered in the "new" aqueous solution, in a pure form. The
concentration of the element in the "new" aqueous solution may be
increased, often to 10-100 times that of the original aqueous
solution, through adjustment of the liquid flow rates. Depleted
from the extracted element, the organic solution is returned for
further extraction, either directly or after a fraction of it has
been cleansed of impurities.
[0398] Important factors that govern this solvent extraction
process can be, for example, the number of extraction, scrubbing
and stripping stages, organic solvent concentration and
diluent.
[0399] In a typical solvent extraction process, the aqueous phase,
containing the rare earth elements, can be for example a chloric or
nitric acidic solution. The organic phase comprises an extracting
agent as those recited in the present disclosure or alternatives in
an organic solvent such as an aliphatic diluent.
[0400] Solvent extraction technique can be used as separation and
purification procedure for the rare earth elements. Some of the
following properties are particularly relevant when selecting an
extracting agent or chemical extractant:
[0401] High selectivity over other unwanted metals and acids during
the extraction process,
[0402] High transfer capacity on the extractant,
[0403] Good chemical stability,
[0404] Fast kinetics.
[0405] For example, precipitation denotes the removal of the rare
earth elements from solution by the addition of a chemical reagent
to form a new, less soluble (solid) compound. For example, a
complete precipitation can be carried out by oxalate, hydroxide, or
other compounds.
[0406] Hydroxide precipitation and double sulphate can also be
used. For large scale operation, ammonia can be used for carrying
out hydroxide precipitation from nitrate or chloride solutions. The
double sulphates
RE.sub.2(SO.sub.4).sub.3*Na.sub.2SO.sub.4*nH.sub.2O can be
precipitated by either addition of sodium sulphate to the solution
containing rare earth elements. The precipitation reaction of
trivalent rare earth elements in aqueous solution is according to
the following equation:
REE.sup.3++3H.sub.2O.fwdarw.REE(OH).sub.3+3H.sup.+
[0407] For example, solvent extraction of iron(III) from a chloride
solution can be performed with tri-butyl phosphate (TBP) in
kerosene as iron in this liquid environment is present in the form
of a chloride complex (FeCl.sub.4.sup.-):
FeCl.sub.4.sup.-+H++n->TBP->HFeCl.sub.4*(TBP)n
[0408] The extraction can be highly dependent on the chloride ion
concentration. In fact, the higher chloride ion concentration, the
stronger tendency for iron(III) complex formation and the better
extraction. Iron(II) also forms similar chloride complexes
(FeCl.sub.4.sup.-2), however, the FeCl.sub.4.sup.-2-organic complex
is less inclined for extraction at prevailing conditions.
[0409] To re-extract (strip) iron from the organic solvent, the
organic solvent can be washed with pure water (for example nano
water purity). Iron(III) can then be transferred to the water
(strip solution) according to the expression:
HFeCl.sub.4*(TBP).sub.n->FeCl.sub.3+HCl+nTBP
[0410] Iron can be stripped as iron chloride. An equivalent amount
of hydrochloric acid can also be washed out. The chloride
concentration increases and the stripping of iron stops. Thus, the
concentration of iron in the strip solution is limited by the
simultaneous transfer of chloride ions.
[0411] The below presented examples are non-limitative and are used
to better exemplify the processes of the present disclosure.
Example 1
Preparation of an Aluminum-Containing Material Sample
[0412] The aluminum-containing material (for example argillite) can
be finely crushed in order to help along during the following
steps. For example, micronization can shorten the reaction time by
few hours (about 2 to 3 hours). In order to remove most of the
iron, a leaching step at room temperature is optionally carried out
between the crushing step and the calcination step. This operation
is, for example, carried out with hydrochloric acid HCl (32 wt %)
and an argillite/acid ratio (weight/volume) of 1:5 is used.
Depending on experimental conditions (sizes of the particles, time
of treatment, agitation system), about 65% to about 93% of the iron
can then be dissolved. However, this leaching step can also bring
in a certain percentage of the aluminum (0-5%). The last step of
the preparation of argillite comprises calcining the pretreated
argillite. This can be accomplished at a calcinating temperature
greater than 550.degree. C. for a period of about 1 to 2 hours. For
example, a heat treatment makes it possible to increase the
quantity of extracted aluminum by about 30% to about 40% for the
same period of time. In others words, the quantity of extracted
aluminum is doubled. When leaching at room temperature is carried
out, a phase separation before calcination can be made in order to
recover the acid and reduce heating costs.
Acid Leaching
[0413] Acid leaching can comprise reacting the crushed and roasted
argillite with at least one acid solution (for example HCl) at
elevated temperature during a given period of time. For example,
the argillite/acid ratio can be of about of 1:10 (weight/volume),
the HCl concentration can be of about 6 M or about 18 to 20 wt %,
the temperature can be of about 100.degree. C. to about 110.degree.
C., and the reaction time can be of about 30 minutes to about 7
hours. Under such conditions, more than about 90% of the aluminum
and about 100% of the iron can be extracted in addition to
impurities. Alternatively, the leaching can be carried out at a
temperature of about 150.degree. C. to about 175.degree. C. at a
pressure of about 350 KPag to about 500 KPag during about 4 to
about 7 hours.
[0414] During the second half of such a treatment (for example the
last 2 or 3 hours), a portion of the excess acid can be recovered
by flashing and condensation. Once the extraction is terminated,
the solid (argillite impoverished in metals) can be separated from
the liquid by decantation or by filtration, after which it is
washed. The residual leachate and the washing water may be
completely evaporated. The corresponding residue can thereafter be
counter currently washed many times with water so as to decrease
acidity and to lower the quantities of base used (for example,
NaOH, KOH, Ca(OH).sub.2, Mg(OH).sub.2, etc.) that are required to
adjust the pH during iron removal. The acid recovered can be
re-utilized after having adjusted its titer either by adding either
gaseous HCl, or by adding concentrated HCl (12 M). After the
reaction, the titer of the acid can vary from about 4 M to about 6
M depending on experimental conditions. With respect to the solid,
it represents about 65% to about 75% of the initial mass of
argillite, it can be valorized and be used again either as an ion
exchange resin, or as an adsorbent.
[0415] Alternatively, the HCl leaching can be carried out under
pressure (so to increase the reaction temperature) into an
autoclave.
[0416] The rare earth element(s) recovery can be made, for example,
at this stage, after carrying out the above mentioned acid
leaching.
[0417] For example, leaching at ratio 3.1/1.0 with 23 wt % HCl at
180.degree. C. provided 96% extraction rate in terms of metal
chlorides.
Removal of Iron
[0418] Several alternatives are proposed in the present disclosure
for carrying out iron removal. For example, iron removal can be
carried out by substantially selectively precipitating iron ions at
certain pH values. Alternatively, some extracting agents can be
used as described in WO2008141423. A membrane can also be used in
combination with such extracting agents
[0419] For example, removal of iron can be carried out by ionic
precipitation of the latter in basic medium for example at a pH of
at least 10 or at a pH of about 11.5 to about 12.5. The pH can also
be about 3 to about 6, or about 3 to about 5 or about 3 to about 4.
Such a step can be made by adding a solution of NaOH, for example
at a concentration of 10 M. Other bases such as KOH can also be
used. Then, all that is required is to separate the solid portion
from the liquid portion by filtration, decantation or
centrifugation and to rinse the solid by means of a diluted base,
such as a solution of NaOH (for example NaOH at a concentration of
0.01 M to 0.02 M). Then, the solid is washed conter currently with
water. The liquid portion comprises aluminum and alkaline-earths A
substantially complete removal of the iron and of nearly all the
impurities (other metals) can thus be achieved as insoluble and
washed hydroxides. Optionally, it is possible to recover iron by
using a refining step by liquid-liquid extraction through a hollow
fiber membrane.
[0420] Alternatively, removal of iron can be carried out by using
an extracting agent and a hollow fiber membrane. Various extracting
agents that could substantially selectively complex iron ions over
aluminum ions (or aluminum ions over iron ions) could be used in
such a step depending an Al/Fe ratio. For example, extraction can
be carried out by using HDEHP (or DEHPA) di(2-ethylhexyl)phosphoric
acid) as an extracting agent adapted to complex iron ions. A
concentration of about 1 M of HDEHP can be used in an organic
solvent, such as heptane or any hydrocarbon solvent. Such an
extraction can require relatively short contact times (few
minutes). For example, the pH of the order of 2 can be used and
aqueous phase/organic phase ratio can be of about 1:1. It was
observed that is possible to extract from 86% to 98% iron under
such conditions. It will be understood that in the present case,
iron is trapped in the organic phase. To recover iron in an aqueous
phase, a reverse extraction with hydrochloric acid (2 M or 6 M) and
organic phase/acidic phase ratio of about 1:0.5 can then be carried
out. In such a case, the resulting aqueous phase is rich in
Fe.sup.3+ ions.
[0421] The rare earth element(s) recovery can be made, for example,
at this stage, after carrying out the above mentioned iron
recovery.
[0422] With solvent extraction using countercurrent techniques,
hydrochloric acid stripping and then contacting with MgO solution,
therefore precipitating the rare earth elements in the form of
hydroxide and then converting the products into their corresponding
oxide into a calcination device.
Aluminum Recovery
[0423] This step can also be carried in various ways. For example,
aluminum ions can be precipitated under the form of Al(OH).sub.3
(for example an hydrated form of Al(OH).sub.3) at a pH of about 7
to about 9 or about 7.5 to about 8.5 or about 8. Alternatively, the
aluminum ions can be reacted with an extracting agent as descried
in WO2008141423.
[0424] The solution obtained from the previous step using either
the precipitation or the extraction technique is relatively clean
and mainly contains aluminum for example about 90% to about 95% or
even as high as about 90% to about 99.8% (without the
alkaline-earths in the case of precipitation). Recovery of the
latter can be carried out by liquid-liquid extraction for example
by using a same hollow fiber membrane and an extracting agent that
is adapted to complex at least substantially selectively aluminum
over other metals or residues. For example,
bis(2,4,4-trimethylpentyl) phosphinic acid (such as the one sold
under the name Cyanex.TM. 272) can be used as an extracting agent
specific to aluminum. For example, this extracting agent can be
used at a concentration of about 20% v/v in an organic solvent such
as heptane. The ratios between the aqueous phase and the organic
phase can be of about 1:1 to about 1:3. For example, the extraction
temperatures can be of about 40.degree. C. and the pH can be
maintained at about 2.5 to about 3.5. It was observed that such a
technique makes it possible to extract more than 70-90% of the
aluminum. After the aluminum has been trapped in the organic phase,
it can be recovered in the form of a concentrate of Al.sup.3+ ions
by using a back extraction. For example, the reverse extraction can
be carried out at a temperature of about 40.degree. C. with
hydrochloric acid (for example at a concentration of 6 M). Under
this condition, more than 90% of aluminum can be recovered.
[0425] The rare earth element(s) recovery can be made, for example,
at this stage, after carrying out the above mentioned aluminum
recovery.
[0426] Then, Al.sup.3+ can be converted into aluminum hydroxide
(for example an hydrated form of Al(OH).sub.3 by addition of a base
such as NaOH. Finally, Al(OH).sub.3 can be converted into alumina
(alumina Al.sub.2O.sub.3) by calcinating Al(OH).sub.3 for example
at a temperature of about 800.degree. C. to 1200.degree. C.
[0427] Al.sup.3+ can also be converted into AlCl.sub.3.6H.sub.2O
and upon calcination HCl can be recovered and Al.sub.2O.sub.3 be
produced.
[0428] Further purification can be performed by
recrystallization.
Rare Earth Elements Recovery
[0429] Rare earth elements recovery can then be made, for example,
at this stage by using any of the technology previously mentioned
in the present disclosure for doing so. For example, it can be
carried out by using a technology as defined in any one of FIGS. 3,
3A 4A, 4B, 4C, 4D, 5A, 5B, 5C, 5D, 5E, 5F, 5G, 5H and 26.
[0430] The processes shown in FIGS. 5E, 5F, 5G and 5H are similar
to the processes shown in FIGS. 5A, 5B, 5C and 5D, with the
exception that they can comprise an extra purification step by
using an ion exchange column, an optional plasma purification step,
an extra acid regeneration step, and an extra calcination step.
[0431] For example, the at least one rare earth element contained
in the residual solutions obtained from the above-mentioned
process. For example, the at least one rare earth element can be in
low concentration for example at a concentration of less than about
50, about 25, 15, 10, 5, 4, 3, 2 or 1 ppm in the lixiviate or
leachate or a solution obtained during the process. The rare earth
elements can be concentrated in the latter stage of the process
prior to extraction with solvent(s). It was demonstrated that
through an internal concentration loop, concentration can be
significantly increased (for example from 100 to 1000 times)
thereby providing more effective conditions for substantially
selectively precipitating, extracting and/or isolating at least one
rare earth element.
Example 2
[0432] As a starting material a sample of clay (argillite) was
obtained from the Grande Vallee area in Quebec, Canada.
[0433] These results represent an average of 80 tests carried out
from samples of about 900 kg each. These tests were carried out by
a using a process as shown in FIG. 1 and FIG. 2.
[0434] Crude clay in the freshly mined state after grinding and
classification had the following composition:
Al.sub.2O.sub.3: 15%-26%;
SiO.sub.2: 45%-50%;
Fe.sub.2O.sub.3: 8%-9%;
MgO: 1%-2%;
[0435] Rare earth elements: 0.04%-0.07%;
LOI: 5%-10%.
[0436] This material was thereafter leached in a two-stage
procedure at 140-170.degree. C. with 18-32 weight % HCl. The HCl
solution was used in a stoichiometric excess of 10-20% based on the
stoichiometric quantity required for the removal of the acid
leachable constituents of the clay. In the first leaching stage of
the semi-continuous operation (step 2), the clay was contacted for
2.5 hours with required amount or certain proportion of the total
amount of hydrochloric acid. After removal of the spent acid, the
clay was contacted again with a minimum 18 weight % hydrochloric
acid solution for about 1.5 hour at same temperature and
pressure.
[0437] The leachate was filtered and the solid was washed with
water and analyzed using conventional analysis techniques (see step
3 of FIG. 1). Purity of obtained silica was of 95.4% and it was
free of any chlorides and of HCl.
[0438] In another example, the purity of the silica was 99.67%
through an extra leaching step.
[0439] After the leaching and silica removal, the concentration of
the various metal chlorides was:
AlCl.sub.3: 15-20%;
FeCl.sub.3: 4-6%;
FeCl.sub.2: 0.5-2.0%;
MgCl.sub.2: 0.5-2.0%;
REE-CI: 0.1-2%
Free HCl: 5-50 g/I
[0440] Spent acid was then crystallized using about 90 to about 98%
pure dry hydrochloric acid in gas phase in two stages with less
than 25 ppm iron in the aluminum chloride hexahydrate formed. The
concentration of HCl in solution (aqueous phase) was about 22 to
about 32% allowing 95.3% of Al.sub.2O.sub.3 recovery. The recovered
crystallized material (hydrate form of AlCl.sub.3 having a minimum
purity of 99.8%) was then calcined at 930.degree. C. or
1250.degree. C., thus obtaining the .alpha. form of the alumina
(1250.degree. C.). The .delta. form being obtained at 930.degree.
C.
[0441] Another example was carried out at low temperature
(decomposition and calcination at about 350.degree. C.) and the
.delta. form of the alumina was less than 2%.
[0442] HCl concentration in gas phase exiting the calcination stage
was having a concentration of about 21 to about 32% by weight and
was used (recycled) for crystallization of the AlCl.sub.3 and
MgCl.sub.2. Excess of hydrochloric acid is absorbed at the required
and targeted concentration for the leaching steps.
[0443] Iron chloride (about 90% to about 95% in ferric form) is
then sent to a hydrothermal process in view of its extraction as
pure hematite (Fe.sub.2O.sub.3). This can be done by using the
technology described in WO 2009/153321 of low temperature
hydrolysis with full heat recovery from calcining, pyrohydrolysis
and leaching stage.
[0444] Before step 10 (in both processes of FIGS. 1 and 2) it was
demonstrated that about 90 to about 98% by weight of the elements
(Al, Fe, Mg and rare earths elements such as (Sc, Ga, Y, Ce) found
in the starting material were recovered. It can be estimated that
the processes for recovering rare earth elements from an
aluminum-containing material disclosed in the present disclosure
can be efficient for recovering about 90% of the rare earth
elements. Thus, with respect to the examples of processes provided
in FIGS. 1 and 2, it can be estimated that the overall yield for
recovering the at least one rare earth element from the
aluminum-containing material would be about 80% to about 90%.
[0445] Rare earth elements can be extracted from the mother liquor
of the hydrolyzer (where silica, aluminum, iron and a great portion
of water have been removed) following pre-concentration from
crystallization to the hydrolyzer. In the form of chlorides the
rare earth elements (RECl) are considerably concentrated and ready
to be extracted. Rare earth elements have demonstrated to
concentrate by a factor 5 to 10 in average within the hydrolyzer
itself on a single pass through it (without any concentration
loop). The concentration factors obtained for certain elements
within the hydrolyzer (single pass) were as follows: [0446] Ce:
>6 [0447] La: >9 [0448] Nd: >7 [0449] Y: >9
[0450] For example, it can be carried out by using a technology as
defined in any one of FIGS. 3, 4A, 4B, 4C, 4D, 5A, 5B, 5C, 5D, 5E,
5F, 5G, 5H and 26.
[0451] The person skilled in the art would thus clearly understand
that such a concentration could be considerably more increased when
carrying out a concentration loop.
[0452] Remaining magnesium chloride is sparged with dry and highly
concentrated hydrochloric acid and then calcinated to MgO while
recovering acid at its azeotropic point.
[0453] Mixed oxides containing other non-hydrolyzable components
were then undergoing a pyrohydrolysis reaction at 700-800.degree.
C. and recovered acid (15-20.2% wt.) was rerouted for example to
the leaching system.
Overall Yields Obtained:
[0454] Al.sub.2O.sub.3: 93.0-95.03% recovery; Fe.sub.2O.sub.3:
92.65-99.5% recovery; Rare earth elements: 95% minimum recovery
(mixture); MgO: 92.64-98.00% recovery; Material discarded: 0-5%
maximum; HCl global recovery: 99.75% minimum; HCl strength as feed
to leaching 15-32% (aqueous); 95% (gas) Red mud production:
none.
Example 3
[0455] A similar feed material (bauxite instead of clay) was
processed as per in example 2 up to the leaching stage and revealed
to be easily leachable under the conditions established in example
2. It provided an extraction percentage of 100% for the iron and
over 95% for aluminum. The process was found to be economically
viable and no harmful by-products (red mud) were generated. A rare
earth elements recovery (as a mixture) of about 90 to about 95% or
about 91% (by weight as compared to the starting material) was
observed Samples tested had various concentrations of
Al.sub.2O.sub.3 (up to 51%), Fe.sub.2O.sub.3 (up to 27%) and MgO
(up to 1.5%). Gallium extraction of 97.0% was observed. Scandium
extraction was 95%.
Example 4
[0456] Some test have been made so as to validate the processes
described in FIGS. 4A, 4B, 5A, 5B, 5C and 5D.
[0457] Gallium chloride and rare earth chloride hydrates from Alfa
Aesar GmbH & Co KG, Karlsruhe, Germany were used in the
experiments. The products are of chemically pure quality (99.9%).
Chemicals were dissolved in tap water to obtain a stock solution.
Aluminum chloride and iron chloride are of technical grade.
Gallium and Rare Earth Elements Precipitation Tests
[0458] The different gallium and rare earth precipitation tests
were carried out using limestone, magnesium oxide and/or caustic
soda. As precipitation reagent, oxalic acid was used. The pH
adjustment during the oxalate precipitation was carried out with
ammonia (25%). At the end of the experiments, the precipitate was
separated from the aqueous solution by filtration. The equilibrium
solubility of rare earth hydroxides and rare earth oxalates in
chloride media was measured at 25.degree. C.
[0459] Hydroxide precipitation of gallium and scandium with
limestone was carried out from a rare earth solution, containing 15
g/L Al, 180 g/L Fe(II), 220 mg/L Ga, 1.4 g/L Ce, 170 mg/L Y and 70
mg/L Sc. The aqueous solution was neutralized at elevated
temperature to precipitate and remove gallium and rare earth
elements. FIG. 6 shows the gallium and scandium hydroxide
precipitation yield obtained as a function of pH value in aqueous
solution (35 g/L HCl, Eh +380 mV).
[0460] The plotted curves in FIG. 6 show the dependency of gallium
and rare earth precipitation yields as a function of the pH. An
increase in the pH increases the gallium and scandium precipitation
yield and approaches 98% for gallium and scandium at a pH around
2.0. FIG. 6 also shows that there is an increase in aluminum
co-precipitation at pH levels higher than 2.0. No cerium and
yttrium precipitate under these conditions. Therefore, it was shown
that if the pH in the precipitation process is maintained at or
below 2.0, gallium and scandium precipitates with minimizing
aluminum, iron(II) and rare earth elements co-precipitation.
[0461] To investigate the influence on the iron(II) concentration
on the gallium and scandium precipitation, iron(II) chloride in the
order of 100 g/L Fe was added to the gallium and scandium feed
solution. The following test parameters were defined:
Temperature: 25.degree. C.
[0462] Stirrer speed: 400 rpm
Time: 1 h
[0463] Precipitation reagent: limestone
Final pH: 5.3
[0464] FIG. 7 shows, for the precipitation of gallium--the
influence of iron(II) (aqueous solution (270 mg/L Ga, 90 mg/L Sc
and 35 g/L HCl, Eh +380 mV). FIG. 7 above shows that the iron(II)
concentration did not have significant effect on the precipitation
of gallium.
[0465] The curves plotted in FIG. 8 show the influence of iron(II)
contamination of scandium precipitation as a function of pH
(aqueous solution (270 mg/L Ga, 90 mg/L Sc and 35 g/L HCl, Eh +380
mV). The conditions are the same than in FIG. 7 The precipitation
pH of scandium increased from about pH 2 to about pH 3.5 which may
have been due to the absence of iron in the aqueous feed solution.
The final concentration of scandium at pH around 4 achieved 18 mg/L
Sc, equivalent to a precipitation yield of 80%.
[0466] The gallium and scandium rich precipitates were washed with
water and then dried at 105.degree. C. and analysed to determinate
co-precipitated rare earth elements. Table 1 shows the
coprecipitation for aluminium, iron(II), cerium and yttrium and
their concentrations in the resulting gallium and scandium
precipitates achieved during the laboratory leaching test work.
TABLE-US-00001 TABLE 1 Co-precipitation for iron(II), cerium and
yttrium from gallium and scandium hydroxide Leaching Parameter
Items Value Aluminium concentration in precipitate g/kg 4-6
Iron(II) concentration in precipitate g/kg 20-30 Losses of cerium %
<0.5 Cerium concentration in precipitate g/kg 1-2 Losses of
yttrium % <0.5 Yttrium concentration in precipitate g/kg
0.1-0.2
[0467] The results of gallium and scandium removal tests are
summarised in table 2.
TABLE-US-00002 TABLE 2 Summery of gallium and scandium removal
tests Gallium and Scandium Removal Parameter Items Value
Temperature .degree. C. 25 to 35 Time min 15 to 30 Precipitation
reagent -- limestone Initial pH value -- 0 Final pH value -- 2-3
Gallium precipitated % 99.9 Scandium precipitated (containing
Fe(II)) % 98 Scandium precipitated % 80 Rare earth losses in solids
% <1 Final Ga in filtrate mg/l <1 Final Sc in filtrate mg/l
<2 Final Sc in filtrate (containing Fe(II) mg/l <20
Hydroxide Precipitation of Rare Earth Elements
[0468] Hydroxide precipitation of rare the earth elements with
magnesium oxide and caustic soda carried out with a solution,
containing 1.8 g/L Ce, 2.3 g/L Y, 1.8 g/L Er, 2 g/L Nd and 0.5 g/L
Pr. The aqueous solution was neutralized with caustic soda at room
temperature and with magnesium oxide at 65.degree. C. to
precipitate and remove the rare earth elements. To investigate the
influence of pH on the rare earth hydroxide precipitation, the
following test parameters were defined: [0469] Temperature:
25.degree. C. and 60.degree. C. [0470] Stirrer speed 400 rpm [0471]
Time: 1 h [0472] Precipitation reagent: magnesium oxide and caustic
soda [0473] Final pH: 10
[0474] FIG. 9 shows that the precipitation of the rare earth
hydroxides starts at pH 6 and have their maximum at pH around 8.0.
In FIG. 9, an aqueous solution in which the initial pH was 1 and
the Eh was +340 mV.
Oxalate Precipitation
[0475] A pre-neutralized aqueous solution from the hydroxide
precipitation tests, containing 1.8 g/L Ce, 2.3 g/L Y, 1.8 g/L Er,
2 g/L Nd and 0.5 g/L Pr was heated up to 50 to 60.degree. C. Oxalic
acid slurry was added. The pH value was then adjusted by adding
drop wise ammonia solution to precipitate and remove the rare earth
elements. To investigate the influence on the amount of
precipitation reagent, the following test parameters were defined:
[0476] Temperature: 60.degree. C. [0477] Stirrer speed: 400 rpm
[0478] Time: 1 h [0479] Precipitation reagent: oxalic acid as
di-hydrate [0480] Final pH: 1.2
[0481] FIG. 10 below shows the solubility of the rare earth
oxalates with increasing oxalic acid concentration at constant
acidity (pH 1.2). The precipitation concentration ranged from 0.06
mol/L to 1 mol/L oxalic acid. (aqueous solution (LRE and HRE, final
pH 1.2, Eh +340 mV).
[0482] For the given acidity, the solubility of the rare earth
oxalates decreases as oxalic acid concentration increase and
reached a precipitation yield of more than 99% all of the
investigated rare earth elements if the added oxalic acid
concentration is 0.15 mol/L or more.
[0483] To investigate the influence of iron(II) concentration on
the precipitation of the rare earth elements, the following test
parameters were defined: [0484] Temperature: 60.degree. C. [0485]
Stirrer speed: 400 rpm [0486] Time: 1 h [0487] Precipitation
reagent: oxalic acid [0488] Iron(II) concentration: 100 [0489]
Final pH: 1.2
[0490] The curve plotted in FIG. 11 shows the rare earth elements
and iron precipitation as a function of oxalic acid concentration
at constant acidity (pH 1.2). The figure indicates that
precipitation of the rare earth elements do not proceed at high
iron(II) contamination.
The results of the rare earth elements removal tests are summarised
in table 3.
TABLE-US-00003 TABLE 3 Summary of rare earth elements precipitation
tests REE Precipitation Parameter Items Value Temperature .degree.
C. 60 Time min 60 Precipitation reagent -- limestone Initial pH
value -- 3 Final pH value -- 8 Yttrium precipitated (as HRE) %
>99 Cerium precipitated (as LRE) % >99 Final Y in filtrate
mg/l <5 Final Ce in filtrate mg/l <5
Solvent Extraction Tests
[0491] To simulate a counter current solvent extraction operation,
metal equilibrium tests were performed. All experiments are carried
out at 25.degree. C. All investigations are carried out in
bench-scale laboratory equipment.
[0492] The organic solutions were contacted for about 10 to 15
minutes in shaking funnels or in stirred beakers under fairly high
speed mixing at different organic to aqueous (O/A) ratios.
[0493] The pH adjustment during the solvent extraction is carried
out using caustic soda solution (10%). After phase separation, the
resulting aqueous and organic phases were saved and analysed.
Gallium and Scandium Solvent Extraction Results
[0494] Based on the selectivity for gallium and scandium over
yttrium, other trivalent rare earth, and aluminium, the reagent
tri-butyl phosphate (TBP) was chosen. On the other hand, iron(III)
was being co-extracted with TBP. Thus, before recovering gallium
and scandium, iron(III) was removed either by solvent extraction or
pre-treated by metallic iron in order to remove of iron(III) by the
reduction. FIG. 12 shows equilibrium data for extraction of iron
from a iron(III) chloride solution. The organic solution contained
90 vol.-% TBP in aromatic kerosene (Solvesso150).
[0495] Co-extraction of gallium by tri-butyl phosphate from
iron(III) chloride solution is indicated in table 4.
TABLE-US-00004 TABLE 4 Gallium co-extraction Org. solution (90
vol.-% TBP in kerosene) Aqueous solution (40% FeCl.sub.3, 270 mg/l
Ga, Eh 500 mV) Organic Aqueous Aq/Org Org.-Ga Aq.-Ga D.sub.Ga
P.sub.Ga ml ml -- mg/l mg/l C.sub.o/C.sub.a % 101.5 8.5 0.08 6.9
188 0.037 30.4 71.5 8.5 0.12 9.5 190 0.050 29.6 51.3 8.7 0.17 12.4
197 0.063 27.0 41 19 0.46 43.6 176 0.248 34.8 43 38 0.86 124 130
0.952 51.9 20 60 3.00 453 119 3.807 55.9
[0496] Co-extracted gallium can be partially removed by scrubbing
with water at high phase ratio. This scrubbing reduces the gallium
losses from the loaded organic solution. Equilibrium data for
scrubbing of gallium from the loaded organic solution is shown in
FIG. 13 (equilibrium curve. org. solution (90 vol.-% TBP,
containing 110 g/L Fe, 0.13 g/L Ga) aqueous solution (water).
[0497] The equilibrium data for stripping of iron from the loaded
organic solution is shown in FIG. 14 (org. solution (90 vol.-% TBP,
containing 110 g/L Fe, 0.13 g/L Ga) Aqueous solution (water).
[0498] The gallium and scandium feed solution was prepared by
dissolution of the gallium/scandium precipitate from a hydrochloric
acid solution, containing 10 mol/L HCl. The experiments were
carried out with 50 vol.-% TBP diluted in aliphatic kerosene (D85).
Isodecanol was used in the experiments as modifier to prevent third
phase formation. Equilibrium data for gallium and scandium
extraction is shown in FIG. 15 (org. solution (50 vol.-% TBP in
kerosene; aq. solution 6 g/L Ga, 2.2 g/L Sc and 10 mol/L HCl).
[0499] FIG. 16 shows the co-extraction of hydrochloric acid during
the gallium and scandium extraction (org. solution (50 vol.-% TBP
in kerosene; aq. solution (6 g/L Ga, 2.2 g/L Sc and 10 mol/L HCl).
The organic solvent is then further loaded with gallium and
scandium for conducting scandium scrubbing and gallium stripping
experiments.
[0500] To remove scandium from the loaded organic solution, 5
mol/L, 6 mol/l and 7 mol/L HCl solutions at 0/A ratio of 1 to 1
were used. This scrubbing significantly reduces the quantity of
scandium from the loaded organic solution. The influence on the
hydrochloric acid scrub solution of scandium scrubbing efficiency
is shown in table 5.
TABLE-US-00005 TABLE 5 Scandium scrubbing tests Org. solution (50
vol.-% TBP, containing 1.3 g/l Ga, 1.2 g/l Sc, initial Ga/Sc ratio
1.07). Aq. solution (Hydrochloric acid solution) Scrub sol Aq/Org
D.sub.Ga D.sub.Sc S Ga/Sc ratio mol/l HCl -- C.sub.o/C.sub.a
C.sub.o/C.sub.a D.sub.Ga/D.sub.Sc [C.sub.Ga/C.sub.Sc].sub.org 5 1.0
266 0.034 7704 31.9 6 1.0 710 1.553 514 1.75 7 1.0 799 5.667 125
1.25
[0501] Equilibrium data for scandium scrubbing from the loaded
organic solution is shown in FIG. 17. (org. solution (50 vol.-%
TBP, 7.3 g/L Ga, 1.6 g/L Sc); aqueous solution (Water).
[0502] Equilibrium data for gallium stripping from the loaded
organic solution is shown in FIG. 18 (org. solution (7.5% TBP in
kerosene, 0.4 g/L Ga; aqueous solution (water).
[0503] The composition of aqueous feed and raffinate during the
solvent extraction tests are summarised in Table 6.
TABLE-US-00006 TABLE 6 Composition of the aqueous feed and
raffinate Org. solution (50 vol.-% TBP in kerosene)Aq. solution (6
g/L Ga, 2.2 g/L Sc and 10 mol/L HCl) Aqueous feed Raffinate
Extraction Efficiency Metal g/l mg/l % Gallium 66 <5 99 Scandium
2.2 <5 99
[0504] First, scrubbing of scandium and co-extracted hydrochloric
with water at very high O/A ratio resulted in a scandium chloride
solution. Scrubbing is selective for scandium and leaving gallium
in the scrubbed organic solution. Gallium was than stripped from
the resulting scrubbed organic solution by water at O/A ratio of 2
to 1.
Extraction of Light and Heavy Rare Earth Elements
[0505] As previously shown, the extraction of rare earth elements
can be depending on the hydrogen ion (H+) concentration.
Consequently organo-phosphorus extractants are pH dependent
extractants. Commercial reagents available such as
di(ethylhexyl)phosphoric acid (D2EHPA), di(ethylhexyl)phosphonic
acid (Ionquest 801) can be used. The selectivity is calculated as
the quotient of the distribution factors of yttrium to that of
cerium. As shown in FIG. 19 (org. solution (10 vol.-% reagent in
kerosene; aq. solution (6.4 g/L Y, 107 g/L Ce, initial pH 1.5, Eh
+430 mV. below, the yttrium/cerium selectivity for Ionquest 801 is
raising until pH 1 and then falling.
[0506] Based on the selectivity for yttrium over cerium,
di(ethylhexyl)phosphonic acid (Ionquest 801) was chosen. The
experiments were carried out with 10 vol.-% Ionquest 801 diluted in
aliphatic kerosene (D85). No modifier was used in the experiments.
Yttrium and cerium extraction dependency of pH in chloride media is
shown in FIG. 20 (extraction of cerium and yttrium in chloride
solution with di(ethylhexyl)phosphonic acid (Ionquest 801) and
di(ethylhexyl phosphoric acid (D2EHPA.)
Extraction of Yttrium
[0507] The reagent di(ethylhexyl)phosphonic acid (Ionquest 801) was
chosen. The experiments were carried out with 10 vol.-% Ionquest
801 diluted in aliphatic kerosene (D85). No modifier was used in
the experiments. The pH value during the yttrium extraction was
kept constant at pH 1.4 by adjusted drop wise with sodium hydroxide
solution (2 mol/L NaOH). Equilibrium data for yttrium extraction
from an aqueous solution containing yttrium and cerium is shown in
FIG. 21 (org. solution (10 vol.-% Ionquest 801 in kerosene; aq.
solution (6.4 g/L Y, 107 g/L Ce, initial pH 1.5, Eh +430 mV).
[0508] The yttrium recovery rate was more than 99%. The maximum
yttrium loading of 10% vol.-% Ionquest 801 reagent was about 10 g/L
yttrium.
[0509] Smaller quantities of co-extracted cerium were removed by
scrubbing with diluted hydrochloric acid. This measure
significantly reduces the quantity of cerium from the loaded
organic. Equilibrium data for cerium scrubbing from the loaded
organic solution is shown in FIG. 22 (org. solution (10 vol.-%
Ionquest 801, containing 0.1 g/I Ce; aq. solution 1 mol/1 HCl).
[0510] Measured concentrations in aqueous feed and raffinate in the
yttrium extraction experiments are shown in table 7.
TABLE-US-00007 TABLE 7 Composition of the aqueous feed and
raffinate Org. solution (10 vol.-% lonquest 801 in kerosene) Feed
solution (6.4 g/l Y, 107 g/l Ce, initial pH 1.5, Eh +430 mV)
Aqueous feed Raffinate Extraction|Efficiency Metal g/l g/l %
Yttrium 6.4 0.1 98 Cerium 107 107 0.2
[0511] Equilibrium data for yttrium stripping from loaded organic
solution is shown in FIG. 23 (org. solution (10 vol.-% Ionquest 801
in kerosene, containing 1 g/L Y); aqueous solution (3.5 mol/L
HCl).
Separation of Dysprosium and Erbium
[0512] The feed solution was prepared by dissolution of dysprosium
chloride, erbium chloride and yttrium chloride in tap water. The
experiments were carried out with tri-butyl phosphate (TBP),
Alamine.RTM. 336 and Aliquat.RTM. 336 diluted in aliphatic kerosene
(D85). The pH value was adjusted at pH 3 by drop wise addition of
ammonia solution (25%). The organic solutions were contacted for
about 10 to 15 minutes in stirred beakers. The organic to aqueous
(0/A) ratio was 1/1. The separation and purification of dysprosium
and erbium by TBP, Alamine.RTM. 336 and Aliquat.RTM. is shown in
Table 8.
TABLE-US-00008 TABLE 8 Dysprosium and erbium separation tests Org.
solution of TBP, Alamine .RTM. 336 and Aliquat .RTM. 336 Aq.
solution (6.7 g/l Dy, 7.1 g/l Er, 6.2 g/l, Y, initial pH 3 in 1
mol/ l NH.sub.4SCN) Extractant S (D.sub.Dr/D.sub.Y) S
(D.sub.Er/D.sub.Y) TBP 7.2 5.7 Alamine .RTM. 336 0.6 0.8 Aliquat
.RTM. 336 1.1 2.3
[0513] Based on the selectivity for dysprosium and erbium over
yttrium, the reagent tri-butylphosphate (TBP) was chosen. The
experiments were carried out with 80 vol.-% TBP diluted in
aliphatic kerosene (D85). No modifier was used in the experiments.
The influence of ammonium thiocyanate concentration on the
extraction and separation of dysprosium and erbium from yttrium was
tested. Equilibrium data for dysprosium and erbium extraction are
shown in table 9.
TABLE-US-00009 TABLE 9 Dysprosium and erbium separation tests Org.
solution (80 vol.-% TBP in kerosene) Aq. solution (6.7 g/l Dy, 7.1
g/l Er, 6.2 g/l Y, initial pH 3 in 1 mol/ l NH.sub.4SCN)
NH.sub.4SCN S S mol/l (D.sub.Dr/D.sub.Y) D.sub.Er/D.sub.Y) 0 7.9 24
0.3 2.9 2.3 0.5 2.6 2.4 0.75 2.5 2.4 1.0 2.5 2.3
[0514] Co-extracted yttrium is removed by scrubbing with water at
high 0/A ratio. This scrubbing significantly reduces the yttrium
losses from the TBP loaded organic solution. Equilibrium data for
yttrium scrubbing from the loaded organic solution is shown in FIG.
24 (org. solution (80 vol.-% TBP in kerosene, 1.2 g/L Y); aqueous
solution (Water).
[0515] Finally, equilibrium data for dysprosium stripping with
water are shown in FIG. 25 (org. solution (80 vol.-% TBP in
kerosene, 8.4 g/I Dy); aqueous solution (water).
Summary of the Solvent Extraction Tests
[0516] The tests have resulted in the following examples of
extraction conditions, applicable for the iron(III) aqueous feed
solution (Table 10).
TABLE-US-00010 TABLE 10 Selected conditions for iron(III) removal
Iron Removal Selected conditions TBP concentration %| 90 Modifier
(Isodecanol) concentration % -- Aromatic kerosene (Solvesso 150) %
10 Surface loading, aqueous continuous m/h 2-3 (35.degree. C.) Iron
loading g/l 100 Iron extraction yield % 90 Iron raffinate
concentration g/l 20 Gallium co-loading mg/l 100-130
[0517] The tests have resulted in the following examples of
extraction conditions, applicable for the gallium and scandium
aqueous solution (Table 11).
TABLE-US-00011 TABLE 11 Selected conditions for extraction of
gallium and scandium. Gallium and Scandium Recovery Selected
conditions TBP concentration % 50 Modifier (Isodecanol)
concentration % 15-20 Aliphatic kerosene % 30-35 Surface loading,
aqueous continuous m/h 2-3 (25.degree. C.) Gallium loading g/l
30-35 Gallium extraction yield % >99 Gallium raffinate
concentration mg/l <1 Scandium loading g/l 10-15 Scandium
extraction yield % 99 Scandium raffinate concentration mg/l
10-20
[0518] Gallium was calcined and the purity of the obtained
Ga.sub.2O.sub.3 was 99.99+%. The impurities were CI at 8.9 ppm and
Al at 1.1 ppm.
[0519] Scandium was also calcined and the obtained purity of Sc2O3
was greater than 99.9%. The main impurities were S at 260 ppm and
Zr at 390 ppm
[0520] The tests have resulted in the following examples of
extraction conditions, applicable for the rare earth aqueous
solution (Table 12).
TABLE-US-00012 TABLE 12 Selected conditions for extraction of rare
earth (yttrium) Yttrium Recovery Selected conditions lonquest 801
concentration % 10 Aliphatic kerosene(D85) % 90 Surface loading,
aqueous continuous m/h 2-3 (25.degree. C.) Yttrium loading g/l 10
Yttrium extraction yield % >98 Yttrium raffinate concentration
mg/l 10-20
[0521] The tests have resulted in the following proposed extraction
conditions, applicable for the separation of heavy rare earth from
yttrium strip liquor (Table 13).
TABLE-US-00013 TABLE 13 Selected conditions for extraction of heavy
rare earth (Dy, Er) HRE (Dy, Er) Removal Selected conditions TBP
concentration % 80 Aliphatic kerosene(D85) % 20 Surface loading
aqueous continuous (25.degree. C.) m/h 3-4 HRE loading g/l 10 HRE
extraction yield % 99 HRE raffinate concentration mg/l 5-10
[0522] The recovery procedure of gallium, yttrium and scandium
precedeed by iron(III) removal, followed by neutralization and
precipitation of gallium and scandium has been demonstrated. To
prevent and/or reduce iron coprecipitation, remaining iron(III) can
beto by further treated (reduced) by using iron metal.
[0523] The following six main process sections were
investigated:
Section 1: Iron(III) Removal. Removal of iron(III) from feed
solution by solvent extraction using tri-butyl phosphate (TBP) in
kerosene; Section 2: Final Iron Removal. Removal of iron by
reduction using metallic iron; Section 3: Gallium and Scandium
Precipitation. Removal of gallium and scandium using limestone or
magnesium oxide; Section 4: Gallium and Scandium Separation.
Separation and recovery of gallium and scandium from re-leach
solution containing 10 moth hydrochloric acid and based on solvent
extraction using the tri-butyl phosphate (TBP) in kerosene; Section
5: Yttrium and other rare earth precipitation. Removal of yttrium
and other rare earth elements by neutralization and precipitation
using limestone, followed by re-leaching in diluted hydrochloric
acid; Section 6: Yttrium Recovery. Separation and recovery of
yttrium from the resulting solution in section 5 by solvent
extraction using di(ethylhexyl) phosphonic acid (Ionquest 801); and
Section 7: Yttrium Separation from HRE. Separation and recovery of
yttrium from heavy rare earth, mainly dysprosium and erbium by
solvent extraction using tri-butyl phosphate (TBP) in kerosene.
Iron(III) Removal
Iron(III) Solvent Extraction
[0524] The prepared aqueous feed solution, containing 40% iron(III)
chloride and 270 mg/L of gallium (201) was fed to the iron removal
circuit. Iron was counter-currently extracted with an organic
solution containing 90% TBP dissolved in aromatic kerosene
(Solvesso150) (202). The achieved iron extraction yield was 90%.
Co-extracted gallium was accumulated in the organic phase to 0.13
g/L gallium. The resulting organic solution (203), containing iron
and small amounts of gallium, was fed to the scrubbing circuit.
Here, gallium was counter-currently scrubbed with an aqueous water
solution (204) at high phase ratio. The organic solvent was then
sent to a stripping circuit. Here, iron (206) is counter-currently
stripped with water (207) before the organic solution (205) was
returned back to the extraction circuit.
Iron(III) Reduction
[0525] Co-extraction of iron(III) can be prevented and/or by prior
reduction to iron(II) using iron (0). The resulting raffinate
(209), containing aluminum, gallium, scandium, rare earth elements
and extracted iron(III) was treated with stoichiometric amounts of
iron powder (210) to eliminate the iron(III) ions. Starch can also
be used for carrying out the reduction.
Gallium and Scandium Recovery
Gallium and Scandium Precipitation
[0526] The precipitation and recovery of gallium and scandium was
introduced to separate gallium and scandium from other rare earth
elements and to pre-concentrate both gallium and scandium for
further treatment. Depleted from iron(III), the resulting filtrate
(211) was then fed to a primary gallium and scandium removal step.
Here limestone (212) was added as neutralization reagent. In this
step, the solution was maintained at constant pH during 15 to 30
min and under controlled RedOx conditions at low pH level. A
precipitation yield of 99% of the gallium and scandium was
achieved. The rare earth elements were detected with very low
concentration in the gallium and scandium precipitate. The filter
product (225) was fed to a dewatering system. The resulting slurry
(213) was then prepared for re-leaching in concentrated
hydrochloric acid solution (214).
Gallium and Scandium Solvent Extraction
[0527] The resulting filtrate (215) from the gallium and scandium
re-leaching step was fed to the gallium and scandium separation
circuit. Gallium and scandium are counter-currently extracted with
an organic solution containing 50 vol.-% TBP dissolved in aliphatic
kerosene (D85) (216). The achieved gallium and scandium extraction
yield was more than 99%.
[0528] Co-extracted iron was accumulated in the organic phase to
0.2 g/L Fe. The resulting organic solution (218), containing
gallium and scandium and small amounts of iron was fed to the
scrubbing circuit. Here, scandium was counter-currently scrubbed
with an aqueous water (219) solution at high phase ratio so as to
provide product (221). The organic solvent (220) was then sent to a
stripping unit where gallium was counter-currently stripped with
water (222) before the organic solution (223) is returned back to
the extraction circuit and gallium (224) is recovered. A raffinate
of hydrochloric acid is also recovered (217).
[0529] Yttrium Recovery
Rare Earth Hydroxide Precipitation
[0530] The filtrate (225) from the gallium and scandium
precipitation step was fed to a further neutralization circuit.
Here, rare earth elements are precipitated with limestone (226) by
raising the pH to 8 during 60 min under controlled RedOx potential
and at elevated (60.degree. C.) temperature. A precipitation of
more than 99% of the investigated rare earth elements was achieved.
Remaining iron(II) will precipitate together with the rare earth
elements. The precipitate (227) was then prepared for re-leaching
in concentrated hydrochloric acid solution (228).
Primary Yttrium Solvent Extraction
[0531] The resulting product (229) from the gallium and scandium
precipitation step will be fed to the extraction circuit for
yttrium. Yttrium is counter-currently extracted with an organic
solution (230) containing 10 vol.-% Ionquest 801 dissolved in
aliphatic kerosene (D85). The achieved yttrium extraction yield was
more than 99%. Co-extracted cerium was accumulated in the organic
phase to 0.1 g/L Ce.
[0532] Due to the high cerium concentration in the aqueous
solution, cerium could be transferred to the strip liquor by
aqueous entrainment of leach solution. Therefore an extra single
scrubbing step can be included to avoid cerium contamination. For
example, the organic phase (232) can be treated with a scrub
solution (233) such as 1 N HCl so as to remove cerium and obtain
composition (234). The raffinate of LRE (Ce, Nd, Eu, Pr) (231) can
eventually be treated so as to separate them from one another and
optionally purify them (see FIG. 5G).
[0533] The resulting organic solution (235), containing yttrium is
fed to the stripping circuit. Here, yttrium is counter-currently
stripped with a solution, containing 3.5 mol/L hydrochloric acid
(236). Finally, before returning the organic solution back to the
primary yttrium extraction, part of the organic reagent has to be
washed with diluted caustic soda solution in one mixersettler stage
for organic regeneration and scandium removal.
Final Yttrium Solvent Extraction
[0534] In the second solvent extraction process, dysprosium and
erbium are removed from the yttrium strip liquor (237) after
neutralization. Dysprosium and erbium are counter-currently
extracted with an organic solution containing 80 vol.-% tri-butyl
phosphate (TBP), dissolved in aliphatic kerosene (D85) (238),
thereby yielding the raffinate of yttrium (239). A heavy rare earth
extraction yield of more than 99% is achieved under controlled pH
conditions. The resulting organic solution (240), containing heavy
rare earth and small amounts of yttrium, is fed to the scrubbing
function. Here, the yttrium (242) is scrubbed with water (241) at
high phase ratio, counter-currently in multistage mixersettler
equipment. The scrubbing liquor (242) is returned to the feed
solution. The organic solvent, depleted from yttrium (243) is
stripped with water (244) and returned to the extraction loop. The
dysprosium and erbium strip liquor (245), is the feed solution for
dysprosium and erbium separation.
[0535] The obtained yttrium was calcined into Y.sub.2O.sub.3 and a
purity of 99.9+% was obtained. The impurities were Si at 26 ppm, Dy
at 51 ppm and Al at 6.2 ppm.
Example 5
[0536] Other tests have been made by using a process as shown in
FIG. 26. Leaching of the rare earth hydroxide filter cake (327) was
carried out using hydrochloric acid (328). The person skilled in
the art would recognize that the process shown in FIG. 26 can be
used for treating various compositions including the precipitate
(227) of FIG. 5c. For example, the precipitate (327) of FIG. 26 can
be the same than the precipitate (227) from FIG. 5c.
[0537] The pregnant leach solution (329) (after fine filtration)
was the feed solution to the rare earth separation steps. The
present aqueous feed solution comprises cerium, praseodymium,
neodymium, europium, dysprosium, erbium and yttrium is contacted
with D2EHPA or Ionquest 801 in kerosene. Alkali is used to adjust
the pH during the extraction procedure. Dysprosium, erbium and also
yttrium (HRE) are extracted and leaving cerium, praseodymium,
neodymium and europium (LRE) in the raffinate (331).
[0538] The loaded organic phase is then selectively scrubbed with
hydrochloric acid (1 to 2 M HCl) to remove the co-extracted LRE.
The extract, contained dysprosium, erbium and yttrium, is then
stripped with hydrochloric acid (3 to 4 M HCl) (336).
[0539] The separation of yttrium from the strip liquor (337) can be
done by extracting it with tri-butyl phosphate (TBP) in kerosene.
The treatment can be done in a multi stage procedure, and ending up
in a final stripping of the loaded organic with water (344). All
HRE substantially selectively extracted, leaving yttrium in the
raffinate (339). The strip liquor (345), containing HRE, forms the
source for further separation of the heavy rare earth elements
(HRE).
Separation of Erbium from Dysprosium
[0540] The final strip liquor from the yttrium separation process
(345) containing dysprosium and erbium was treated by solvent
extraction using D2EHPA or Ionquest 801 in kerosene, leaving
dysprosium in the raffinate (347). Alkali is used to adjust the pH
during the extraction circuit. The loaded organic phase is then
scrubbed with hydrochloric acid (2 to 3 M HCl) to remove the
co-extracted dysprosium. The extract, containing erbium, is then
stripped with hydrochloric acid (3 to 4 M HCl) (346) so as to yield
the strip liquor of erbium (348).
[0541] The so-obtained dysprosium was calcined in order to produce
Dy.sub.2O.sub.3 having a purity of 99.9+%. Other impurities were
mainly Yb at 440 ppm and Ca at 100 ppm.
[0542] The so-obtained erbium was calcined in order to produce
Er.sub.2O.sub.3 having a purity of 99.9+%. Other impurities were
mainly Y at 390 ppm and Al at 140 ppm.
Separation of Cerium by Oxidation and Cerium Precipitation
[0543] The raffinate (331A) from the primary separation is fed to
oxidation and cerium precipitation unit. The oxidation of cerium is
achieved by addition of an oxidation reagent. For example, sodium
hypochlorite (349) can be used. The precipitation of cerium
hydroxide can be carried at a pH of about 0.5 to about 1.5 or pH of
about 1 after adding of alkali (350). The outflow from the cerium
oxidation (352) is fed to the europium separation circuit. The
filter cake (351), containing cerium hydroxide was washed with
acidic water, dewatered and stored for further processing.
[0544] The so-obtained cerium was calcined into Ce.sub.2O.sub.3 and
a purity of 99.5+% was obtained. The impurities were K at 330 ppm,
Pr at 280 ppm and Y at 50 ppm.
Separation of Europium
[0545] The resulting filtrate (352) from the cerium recovery step
was used to separate europium from praseodymium and neodymium. The
aqueous feed solution was contacted with D2EHPA or Ionquest 801 in
kerosene. Europium was extracted and leaving praseodymium,
neodymium in the raffinate (354). Alkali was used to adjust the pH
during the extraction circuit. A scrubbing section removed
co-extracted praseodymium and neodymium by using weak hydrochloric
acid (0.5 to 1.5 M HCl). The extract, containing europium, was then
stripped with hydrochloric acid (2 to 3 M HCl) (353).
Reduction and Precipitation of Europium
[0546] The reduction of europium(III) was achieved by addition of
an reduction reagent. For example, europium (355) can be reduced by
zinc powder or alternatives (361). The precipitation of europium
sulphate can be carried out after addition of sodium sulphate
(362). The outflow from the europium reduction circuit was fed to
the effluent treatment. The filter cake (363), containing europium
sulphate was washed with acidic water, dewatered and stored for
further processing.
Separation of Neodymium from Praseodymium
[0547] The raffinate (354) from the europium separation consists
mainly of praseodymium and neodymium. The separation of
praseodymium and neodymium was carried out with D2EHPA or Ionquest
801 in kerosene. Neodymium was extracted, leaving praseodymium in
the raffinate (357). Alkali was used to adjust the pH during the
extraction circuit. The loaded organic phase was then scrubbed with
hydrochloric acid (2 to 3 M HCl) (356) to remove the co-extracted
praseodymium. The organic extract (358), presently containing
neodymium, was then stripped with hydrochloric acid (3 to 4 M HCl)
(359) so as to obtain the strip liquor of neodymium (360).
[0548] The so-obtained neodymium was calcined into Nd.sub.2O.sub.3
and a purity of 99.9+% was obtained. The impurities were K at 330
ppm, Pr at 280 ppm and Y at 50 ppm.
[0549] In order to demonstrate the versatility of the processes of
the present disclosure, several other tests have been made so as to
shown that these processes can be applied to various sources of
starting material.
Example 6
[0550] Another starting material has been used for preparing acidic
compositions comprising various components. In fact, a material
that is a concentrate of rare earth elements and rare metals
(particularly rich in zirconium) has been tested. Table 14 shows
the results of the leaching carried out on such a starting material
using a similar process as shown in FIGS. 1 and 2 and as detailed
in Examples 1-3. It can thus be inferred from the results shown in
Table 14 that the rare earth elements and rare metals extracted and
present in the obtained leaching composition can eventually be
isolated by the processes of the present disclosure such as, for
example, by those presented in Examples 4 and 5. The results
obtained were superior by at least 20% as compared to leaching
carried out with H.sub.2SO.sub.4.
TABLE-US-00014 TABLE 14 Tests made on a zirconium rich material.
Composition Average Extraction rate O All Orbite measure and/or
measured for measured (ALP) process Raw material evaluated (% wt.)
testing (% wt.) (%) recovery (%) Al.sub.2O.sub.3 6.12 6.12 89.65
86.97 Fe.sub.2O.sub.3 15.80 15.80 99.50 97.51 SiO.sub.2 36.00 36.00
0.000 99.997 MgO 3.08 3.08 99.75 92.66 Na.sub.2O 1.13 1.13 99.50
99.50 K.sub.2O 2.12 2.12 99.50 99.50 CaO 6.10 6.10 99.50 99.00 S
total 0.22 0.22 100.00 F 1.98 1.98 99.50 99.00 TiO.sub.2 0.13 0.13
0.000 99.03 V.sub.2O.sub.5 0.00 0.00 98.00 96.04 P.sub.2O.sub.5
1.10 1.10 98.00 96.04 MnO 0.43 0.43 98.00 96.04 ZrO.sub.2 12.43
12.43 22.70 20.43 Cr.sub.2O.sub.3 0.00 0.00 0.00 0.00
Ce.sub.2O.sub.3 3.05 3.045 97.31 92.98 La.sub.2O.sub.3 1.34 1.337
99.55 92.68 Nd.sub.2O.sub.3 1.55 1.551 98.40 94.79 Pr.sub.2O.sub.3
0.37 0.375 99.75 97.52 Sm.sub.2O.sub.3 0.15 0.151 88.75 84.80
Dy.sub.2O.sub.3 0.09 0.089 80.35 76.77 Er.sub.2O.sub.3 0.03 0.030
72.60 69.37 Eu.sub.2O.sub.3 0.03 0.027 85.57 81.76 Gd.sub.2O.sub.3
0.21 0.205 82.85 79.16 Ho.sub.2O.sub.3 0.01 0.013 77.10 73.67
Lu.sub.2O.sub.3 0.00 0.003 60.15 57.47 Tb.sub.2O.sub.3 0.02 0.022
78.05 74.58 Th 0.02 0.022 88.10 84.18 Tm.sub.2O.sub.3 0.00 0.004
66.85 63.88 U 0.01 0.014 81.90 78.26 Y.sub.2O.sub.3 0.30 0.300
72.70 69.46 Yb.sub.2O.sub.3 0.02 0.023 62.80 60.01 Ga.sub.2O.sub.3
0.02 0.016 96.90 92.59 Sc.sub.2O.sub.3 0.00 0.003 95.00 90.77 LOI
(inc. water) 6.122023973 6.12
Example 7
[0551] Other tests have been made in a similar manner as described
in Example 6. In the present example, carbonatite has been used as
a starting material. (see table 15 below).
TABLE-US-00015 TABLE 15 Tests made on carbonatite Composition
Average Extraction rate O All Orbite measure and/or measured for
measured (ALP) process Raw material evaluated (% wt.) testing (%
wt.) (%) recovery (%) Al.sub.2O.sub.3 0.70 0.70 84.31 81.61
Fe.sub.2O.sub.3 11.22 11.22 94.14 92.15 SiO.sub.2 2.11 2.11 0.00003
99.997 MgO 6.50 6.500 100 96.25 Na.sub.2O 0.07 0.07 92.54 90.55
K.sub.2O 0.18 0.181 37.33 37.33 CaO 16.51 16.51 100 98.00 TiO.sub.2
0.00 0.000 0.00000 100.000 V.sub.2O.sub.5 0.00 0.000 0 100.000
P.sub.2O.sub.5 0.00 0.000 0 100.000 MnO 0.00 0.000 0 100.000
ZrO.sub.2 0.00 0.000 0 100.000 Cr.sub.2O.sub.3 0.00 0.000 0 100.000
Ce.sub.2O.sub.3 1.19 1.195 64.04 61.190 La.sub.2O.sub.3 0.46 0.463
63.86 61.018 Nd.sub.2O.sub.3 0.45 0.448 81.46 77.835
Pr.sub.2O.sub.3 0.14 0.142 67.59 64.582 Sm.sub.2O.sub.3 0.03 0.033
65.32 62.413 Dy.sub.2O.sub.3 0.00 0.000 78.12 74.644
Er.sub.2O.sub.3 0.00 0.000 86.15 82.316 Eu.sub.2O.sub.3 0.01 0.007
66.45 63.493 Gd.sub.2O.sub.3 0.01 0.013 54.46 52.037
Ho.sub.2O.sub.3 0.00 0.000 83.12 79.421 Lu.sub.2O.sub.3 0.00 0.000
88.86 84.906 Tb.sub.2O.sub.3 0.00 0.001 41.42 39.577 Th 0.06 0.065
Tm.sub.2O.sub.3 0.00 0.000 90.70 86.664 U 0.01 0.007 Y.sub.2O.sub.3
0.00 0.000 84.68 80.912 Yb.sub.2O.sub.3 0.00 0.000 85.11 81.323
Ga.sub.2O.sub.3 0.00 0.000 0 0.000 Sc.sub.2O.sub.3 0.00 0.000 0
0.000 LOI (inc. water) 60.33
Example 8
[0552] Another series of tests was performed on argillite using
processes as per previous examples. The initial composition
measured was:
TABLE-US-00016 TABLE 16 Raw material initial composition Element
Composition measured (wt.) Al.sub.2O.sub.3 24.00% Fe.sub.2O.sub.3
8.51% MgO 1.33% Na.sub.2O 1.06% K.sub.2O 2.86% Ce.sub.2O.sub.3 176
ppm La.sub.2O.sub.3 88 ppm Nd.sub.2O.sub.3 82 ppm Pr.sub.2O.sub.3
22 ppm Sm.sub.2O.sub.3 15 ppm Dy.sub.2O.sub.3 11.5 ppm
Er.sub.2O.sub.3 6.3 ppm Ece.sub.2O.sub.3 2.9 ppm Gd.sub.2O.sub.3
15.0 ppm Y.sub.2O.sub.3 67.0 ppm Ga.sub.2O.sub.3 51 ppm
Sc.sub.2O.sub.3 28 ppm
The samples were leached in batch mode at about 150 to about
160.degree. C. for a 6 hour duration with 18.0 wt .degree. AD
HCl+5% excess. The following extraction yields were measured at the
leaching stage.
TABLE-US-00017 TABLE 17 Leaching extraction yield measured Raw
Element Extraction measured (%) Al.sub.2O.sub.3 97.9
Fe.sub.2O.sub.3 100 MgO 96.4 Na.sub.2O 92.8 K.sub.2O 94.0 RE-O
incl. Sc and Ga 96.7
After processing through main steps of continuous process, the
following yield were measured.
TABLE-US-00018 TABLE 18 Global recovery yield Element Global
recovery (%) Al.sub.2O.sub.3 96.20 Fe.sub.2O.sub.3 98.01 MgO 92.64
Na.sub.2O 90.77 K.sub.2O 93.97 RE/RM-O 90.04
After the ion exchange and solvent for the extraction steps the
individual recovery measured for the rare earths and rare metals
were:
TABLE-US-00019 TABLE 19 Element Recovery measured (%)
Ga.sub.2O.sub.3 83.58 Sc.sub.2O.sub.3 95.16 Ce.sub.2O.sub.3 93.63
La.sub.2O.sub.3 86.81 Nd.sub.2O.sub.3 91.00 Pr.sub.2O.sub.3 96.00
Sm.sub.2O.sub.3 87.14 Dy.sub.2O.sub.3 93.00 Er.sub.2O.sub.3 91.38
Eu.sub.2O.sub.3 93.83 Gd.sub.2O.sub.3 95.89 Y.sub.2O.sub.3
82.95
From the material balance measured, the consumption of chemical
reagents into the solvent extraction were: Iron powder:
0-Fe.sub.2O.sub.3 removed from hydrolysis; HCl (32% wt): 0.75 Kg/h
as a strip solution ion REE 5.times. separation and releaching ree
oxalates; Nano water: 10 kg/h for solution strip and washing of
precipitation; Oxalic acid: 325 g/h for precipitation of ree
oxalates; DEHPA 5.times. solutions: Few grams per hour; TBP
5.times. organic solution: 6.5 g/h for gallium records and yttrium
separation;
Kerosene: <5 g/h.
[0553] It can thus be inferred from the results shown in Table 15
that the rare earth elements and rare metals extracted present in
the obtained leaching composition can eventually be isolated by the
processes of the present disclosure such as, for example, those
presented in Examples 4 and 5.
[0554] The processes of the present disclosure provide a plurality
of important advantages and distinction over the known
processes
[0555] The person skilled in the art would understand that
processes described in the present disclosure for extracting rare
earth elements and rare metals can be used for treating various
starting materials. For example, any compositions comprising at
least one rare earth element and/or at least one rare earth metal
can be used as a starting material. For example, any compositions
comprising at least one iron ion and at least one rare earth
element can be used as a starting material.
[0556] The person skilled in the art will thus understand that the
processes of the present disclosure can be used in combination with
various processes for treating aluminum-containing materials, and
derivatives, zinc-containing materials and derivatives thereof,
copper-containing materials and derivatives thereof,
nickel-containing materials and derivatives thereof,
magnesium-containing materials and derivatives thereof, and
titanium-containing materials.
[0557] In fact, various different treatments can be carried out to
the aluminum-containing materials and derivatives, iron-containing
materials and derivatives, zinc-containing materials and
derivatives thereof, copper-containing materials and derivatives
thereof, nickel-containing materials and derivatives thereof,
magnesium containing materials and titanium-containing materials
and derivatives thereof.
[0558] It was thus shown that the processes of the present
disclosure are effective for providing to the existing solutions
for extracting rare earth elements. Moreover, ti was shown that
such an alternative provided by the processes is an alternative
that is a cost effective and environmentally friendly solution.
[0559] While a description was made with particular reference to
the specific embodiments, it will be understood that numerous
modifications thereto will appear to those skilled in the art.
Accordingly, the above description and accompanying drawings should
be taken as specific examples and not in a limiting sense.
* * * * *