United States Patent Office 3,676,106
Patented July 11, 1972
1 2
(Iud
R.
"NH
R,/
wherein Rh R2, and R3 are aliphatic chains (straight or
branches) having from 6 to 18 carbon atoms.
The invention is illustrated by the following examples
which are illustrative but not limiting thereof as the increased
by the exchange of metal ions in the solution for
hydrogen ions on the exchange agent as the process
proceeds. For effective recovery of metal ions from the
solution its acidity must be held at a low value, so that
5 additional procedure is necessary to maintain the acidity
below a certain point. Using copper as an example, UX64
will effectively extract copper from solutions having a
pH value of more than 1.5 (acid c~mtent lowe: than about
5 grams per litre), but the effiCiency of thiS agent de-
10 creases at lower pH values. Like conditions govern the
recovery of other metals from their aqueous solutions
by ion exchange techniques using a hydrogen ion exchange
agent.
Control of the acidity of the solution of metal ions has
15 been accomplished in the past by neutralizing the solution
by the addition of alkaline reagents, such as, ammonia or
lime. This increases the overall cost of the recovery
process due to the cost of the neutralizing reagents which
are added and also because of the loss of acid through
20 neutralization.
In accordance with this invention, the acidity of the
leach solution is controlled during the ion exchange recovery
process by contacting the leach solution with a
solvent extractant for acid when the acidity of the leach
25 solution has reached a point at which the recovery of
metal ions is no longer efficient. In other words, the process
of the invention comprises alternately contacting the
leach solution with a cation exchange agent and a solvent
extractant for hydrogen ions until substantially all of the
30 metal ions are removed from the solution. The metal can
be recovered from the ion exchange agent and the agent
reused in the process. The recovered acid is stripped from
the solvent extractant with water and the solvent extractant
reused. The water strip containing acid is returned to
35 the process for further leaching of copper ore, after first
concentrating it if necessary.
The present invention can be utilized to control the
acidity of the leach solution for any metal which can be
recovered therefrom with a hydrogen ion exchange agent.
40 Obviously, if a metal is not recoverable from leach solutions
by a cation exchange agent which exchanges hydrogen
ion for metal ion, the invention has no application.
The cation or hydrogen ion exchange agent for the particular
metals will vary depending upon the efficiency re-
45 quired. For example, for the recovery of copper, LIX-64
is presently preferred. Other cation ion exchange agents
may be used for various metals. Liquid cation exchangers
may be used, such as, di-2-ethyl-hexyl phosphoric acid
and other organic esters of phosphoric acid, carboxylic
50 acids with various hydrocarbon chains, di-nonyl naphthalene
sulfonic acid and strong, intermediate and weak
cation exchange resins, such as Doulite C-20, Dowex
50W, Amberlite 200, Amberlite IRC-84 and Doulite
E8--63, all of these resins being capable of exchanging
55 hydrogen ions for the metal ions in solution.
rrhe ion exchange agent used should, of course, be immiscible
with the leach solution and must not form interfering
complexes with the required metal complexes.
The preferred solvent extractants for hydrogen ions are
60 the long chain secondary and tertiary amines used conventionally
for extracting acids from solution. They conform
generally to the formulas:
3,676,106
ION EXCHANGE PROCESS FOR mE RECOVERY
OF METALS WIm CATION EXCHANGE AGENTS
Wayne C. Hazen, Denver, Colo., assignor to
Hazen Research, Inc., Golden, Colo.
No Drawing. Filed Sept. 10, 1970, Ser. No. 71,278
Int. CI.C22f 15/08,59/00
U.S. CI. 75-101 R 12 Claims
ABSTRACT OF mE DISCLOSURE
A method for recovering metal values from aqueous
solution with a hydrogen ion exchange agent in which the
acidity of the aqueous solution is controlled without
neutralizing the acid formed therein, the method comprising
alternately contacting the aqueous solution with
(1) the hydrogen ion exchange agent to replace hydrogen
ions on the agent by metal ions and (2) a solvent extractant
for hydrogen ions to recover hydrogen ions from
the aqueous solution until substantially all of the metal
values are recovered from the aqueous solution.
SUMMARY OF THE INVENTION
It has become important to recover metals from their
ores in high purity form as inexpensively as possible to
meet present commercial standards. Furthermore, as ores
become scarcer, processes for high yield recovery of
metals from low grade ores must be highly efficient to
make them economically feasible. These requirements
have led to the use of highly refined solvent extraction
and ion exchange techniques for the recovery of metals
from their ores.
The feed solution for many recovery processes is
ordinarily an aqueous solution formed by dissolving the
metal ore in dilute acid. In the ion exchange recovery
processes, ordinarily the solution is contacted with a
liquid-liquid or liquid-solid cationic exchange agent, the
hydrogen ions on the agent being exchanged for metal
ions in solution with the metal being deposited on the ion
exchange agent. The metal is then stripped from the ion
exchange agent and recovered by standard techniques
from the stripping solution. The regenerated ion exchange
agent is then returned to the process.
In the case of copper, for example, it has been common
practice to dissolve the copper mineral with dilute sulfuric
acid. The resulting leach liquor is commonly run through
tanks containing iron scrap or tin cans, thereby precipitating
the copper as a sludge called "cement copper."
This impure product must then be smelted and refined to
make the standard high purity copper sold commercially.
A method for producing high purity copper and avoiding
the smelting and refining steps is the use of a cationic ion
exchange agent to remove copper from the impure leach
liquor and concentrate it to a copper sulfate solution
strong enough (30 to 50 grams per litre of copper) so
that it may serve directly as feed to an electrolytic cell.
Cation exchange agents for accomplishing this are available
on the market, an example being a material sold by 65
the General Mills Company under the trade name of
"LIX-64," a 2-hydroxy benzophenoxime. The method for
making these compounds is disclosed in U.S. Patent No.
3,428,449.
One of the disadvantages of processes for extracting 70
metal from acid leach liquors with a cationic exchange
agent is that the acidity of the solution is progressively in-
The invention relates to the recovery of metal ions in
solution with a hydrogen ion exchange agent; more particularly,
it relates to an improvement in such ~ process
which provides for control of the pH of the solutIOn.
3,676,1.06
Distribution
pH coefficient
Distribution
pH coefficient
4.1 .
1.3 0.29
1.05 0.09
1. 00 0.05
Extract, Aqueous,
g./!. Cu g.!1. Ou
TABLE 1
[Extraction of Cu with LIX-64]
TABLE 2
[Extraction of Ou with LIX-64 and intermediate contacts with
Adogen 368]
Contact
4
solvent. This was repeated three times and the results are
shown in Table 1.
Extract, Aqueous,
Contact g./!. Cu g./!. Cu
It can be seen that as the pH becomes lower the solvent
extracts a lesser amount of copper. This is reflected in
15 the smaller distribution coefficient after each contact. The
total Cu extracted was 78.6%.
The above test {Table 1) was repeated and after each
contact with the copper extractant the raffinate was contacted
with a 10% kerosene solution of Adogen 368
20 (a tertiary amine mixture of 8, 10 and 12 carbon chains),
also containing 10% isodecanol to improve phase disengagement.
The results are presented in Table 2.
Feed............................... 5.0
1st...................... 0.59 2.02
2nd..................... 0.12 1.30
10 3Dd..................... 0.05 1.07
In the following a copper leach solution was prepared
by leaching a one percent copper ore containing oxide
copper minerals with dilute sulfuric acid and filtering the
slurry to obtain clear solution. The solution analyzed
7.5 grams per litre of copper, 10.0 grams per litre of free
H2S04, and 2.4 grams per litre of iron as ferrous sulfate.
In the first test, recorded in Table 1, the free acidity of
the solution was lowered to about 7 grams per litre by
addition of ammonia. The solution was then fed to a
four-stage countercurrent solvent extraction unit countercurrent
to an organic phase composed of ten percent 25
LIX-64 dissolved in kersosene. The analyses of the aqueous
phase in each stage are shown in the following table.
3
vention is not restricted in its application to recovery
of any particular metal ion.
The following example illustates the use of the invention
as applied to the recovery of copper from a dilute
sulfuric acid leach liquor, the pH being maintained at 5
the required level without neutralization of acid. "LIX-64"
was used as the cation exchange agent.
In the examples which follow and throughout the specification
metal percentages are given in weight percentages
while solution percentages are based on volume
percentages, i.e., "10% LIX~64 in kerosene" means 10%
by volume of LIX-64 to kerosene.
EXAMPLE I
TABLE 1
Analysis of aqueous
phase, g./!.
Stage Copper
Sulfuric
acid
Feed............................... 5.0 4.1 ...•••••...•
30 1st LIX-64............. 0.59 2.08 1.3 0.28
1st Adogen..................................... 3.0 ••...•.•...•
2nd LIX-64............ 0.28 0.69 1.2 0.41
2nd Adogen.................................... 2.9 ..•.•••.....
3rd LIX-64............. 0.12 0.08 .......••••• 1. 5
L_•••....•• 35
2•••...•••••
3.•..•.....•
4••••••..•••
6.5
3.2
2.4
2.2
5.3
10.1
11. 7
n.8
When the results of Table 1 are compared with the
results of Table 2, it can be seen that the higher pH in
the aqueous solution results in higher extraction. Thus,
after contacts with the LIX-64 between three stages,
40 98.4% of the Cu had been extracted.
EXAMPLE HI
wherein R1 and R2 are hydrocarbon chains of three and
four carbon atoms. The test was carried out in a man75
ner similar to that described in Example II. The results
An aqueous solution of rare earth nitrates was prepared
containing 45.8 g./l. of R~Oa. This solution was
65 contacted at a phase ratio of 1.0 with a 50% kerosene
solution of a carboxylic acid known as Versatic 9-11 with
a formula:
70
In the following example the feed solution used was a
nitrate solution of rare earth metals having the follow45
ing analysis:
La20a Perce1n.2t
Ce02 2.0
PraOu 3.4
Nd
2
0
a
18.0
Sm203 48.1
EU20a ,___ 1.1
Gd
2
0
a
17.7
Tb
4
0
7
-____________________ 0.9
55 HDY020 a -------------------------------------- 1.3
2
0
a
' 0.6
Er20a 0.4
Tm20a ' Trace
Yb
2
0
a
0.2
60 YLU20a --------------------------'--- ,_ rr"race
2
0
a
5.1 5.1>
4.6
4.2
3.8
Sulfuric
acid
6.6
2.8
.9
.2
Copper
Analysis of aqueous
phase, g./!.
TABLE 2
Biage
L .
2•• _••••••••
3.••...•.•..
4•••••.•••••
EXAMPLE H
A copper sulfate solution containing 5 g.ll. Cu was
used in a series of shakeout tests. This solution was contacted
with 10% LIX-64 in kerosene at an organic to
aqueous phase ratio of 5.0. After the first contact the
raffinate was again contacted with a fresh solution of the
The results show that the removal of acid from each
stage with the amine solvent substantially improve the
recovery of copper, about 97 percent of the copper being
recovered.
The results reported in the table show that the sulfuric
acid content of the solution increased as the copper concentration
decreased because of the exchange of copper
ions for hydrogen ions. It can also be seen that only
about 70 percent of the copper was extracted.
The same feed solution was fed to a four·stage ion
exchange·solvent extraction system in which each copper
ion exchange stage was preceded by an acid extraction
stage except stage 1. The acid extractant used was a tertiary
amine, N-benzyl·di(2·ethyl hexyl) amine. The analyses
of the aqueous phase in each of the stages of the 50
copper recovery are shown in Table 2.
3,676,106
TABLE 1
[Stripping of sulfuric acid from a 10% kerosene solution of Adogen 368 50
loaded with sulfuric acidl
TABLE 2
[Extraction of rare earths with Versatic 9-11 and intennediate contacts 25
with Adogen 3681
6
impurities being removed and the acid being recovered
from solution by alternate treatment of the solution with
cation exchange agent and acid solvent throughout the
recovery process. As an example, the process has been
5 found to be particularly effective in the recovery of phosphoric
acid from phosphate ores.
I claim:
1. A process for the recovery of metal ions from solution
with a hydrogen ion exchange agent which com-
10 prises: alternately contacting the solution with a hydrogen
ion exchange agent to exchange hydrogen ions on the hydrogen
ion exchange agent for the metal ions in solution
and with a solvent extractant for hydrogen ions to remove
hydrogen ions from the solution.
2. The process of claim 1 in which the pH is in the
acid range when the solution is contacted with the solvent
extractant and the solvent extractant is maintained in contact
with the solution until the pH decreases.
3. The process of claim 1 in which the metal ion is
selected from the group consisting of ions of copper and
rare- earth metals.
4. The process of claim 3 in which the hydrogen ion
exchange agent is a 2-hydroxy benzophenoxime, and the
metal ion is the copper ion.
5. The process of claim 3 in which the metal ion is a
rare earth metal ion and the hydrogen ion exchange agent
is a carboxylic acid.
6. A process for the recovery of metal ions from aqueous
solutions with a hydrogen ion exchange agent which
30 comprises: alternately contacting the solution with a
hydrogen ion exchange agent to exchange hydrogen ions
on the hydrogen ion e~change agent for the metal ions in
solution until the pH of the aqueous solution reaches a
given point so low that effective removal of more metal
35 ions is substantially precluded and then contacting the
aqueous solution with a solvent extractant for hydrogen
ions in an organic phase until the pH of the aqueous solution
reaches a given point so high that metal can be
effectively recovered; and repeating the alternate contact
40 of the aqueous solution with the hydrogen ion exchange
agent and the solvent extractant until substantially all of
the metal ion is removed from solution; stripping the
metal and acid from the hydrogen ion exchange agent and
the solvent extractant, respectirvely; and recovering the
45 acid and the metal.
7. The process of claim 6 in which the metal ion is a
member of the group consisting of copper and rare earth
metal ions.
8. The process of claim 7 in which the hydrogen ion
exchange agent is a 2-hydroxy -benzophenoxime and the
metal ions are copper ions.
9. The process of claim 6 in which the solvent extractant
for hydrogen ions is an amine.
10. The process of claim 6 in which the pH of the
55 aqueous solution is in the acid range when it is contacted
with the solvent extractant for hydrogen ions.
11. In the process of recovering metal ions from aqueous
solution in which the metal ions are exchanged for
hydrogen ions on a hydrogen ion exchange agent, the im-
60 provement in controlling the pH of the solution without
neutralizing the acid therein which comprises: alternately
contacting the aqueous solution with a hydrogen ion exchange
agent until the acidity of the aqueous solution is
substantially increased and with a solvent extractant for
65 acid until the acidity of the aqueous solution is substantially
decreased; and repeating the alternate contact of
the aqueous solution with hydrogen ion exchange agent
and organic extractant until substantially all of the metal
is recovered from the aqueous solution.
12. A continuous process for the recovery of a metal
from its ore which comprises:
(a) leaching the ore with acid to form an aqueous solution
containing ions of the metal;
(b) contacting the aqueous solution with a hydrogen
ion exchange agent to exchange hydrogen ions on the
4.8 _
1.0 0.07
0.9 0.02
0.9 0.02
Distribution
coellipH
cient
45.8
42.8
41.9
41.1
14.2 _
11.3 28.6
9.9 13.9
9.2 7.3
8.7 4.6
8.4 3.2
8.2 2.4
Organic Aqueous
phase, phase,
g./!. H,SO, g./!. H,SO,
EXAMPLE IV
Extract, Aqueous,
g./!. RE,03 g./!. RE,03
TABLE 1
[Extraction of rare earths with Versatlc 9-111
Contact
Extract _
1st. • _
2nd _
3rd _
4th _
5th _
6th _
5
are shown in Table 1. It can be seen that 10.26% of the
total rare earths were extracted with this carboxylic acid.
Contact
Feed _
1st__________________ 3.0
2nd_________________ 0.9
3rd_________________ 0.8
The same aqueous feed was used for a test where the
acid generated during the contact with the Versatic acid 15
was extracted with the tertiary amine described in Example
II (Adogen 368). The results are tabulated in
Table 2 of Example III. It may be noticed that because
of the intermediate extraction of the acid the total extraction
of rare earths after three contacts was 16.6% 20
as compared with the 10.26% obtained when no Adogen
was used.
The following example was performed to illustrate that
reusable sulfuric acid can be effectively stripped from
the solvent.
The Adogen 368 solvent was loaded with acid by contacting
it with a 2 N sulfuric acid solution. The extract
was then contacted several times at a phase ratio of 10.0
with plain water. The results presented in Table 1 show
that the acid can be stripped from the extract to yield
reusable sulfuric acid.
D1stribn-
Extract, Aqueous, tlon coeffi-
Contact g./!. RE,03 g./!. RE,03 pH clent
Feed__________________________ 45.8 4.8 _
1st VersatIc_________ 3.0 42.8 1.0 0.07
1st Adogen_____________________________________ 5. 0 _
2nd VersatIc________ 2.3 40.5 0.06
2nd Adogen_____________________________________ 5.0 •• _
Srd Versatic_________ 2.3 38.2 _••• __._____ 0.06
Although the process of the invention is illustrated by
its application in controlling the pH of leach solutions in
which the metal ions being recovered happen to be copper
or rare earth metals, it is not limited in its application
to leach solutions containing any particular metal
ion or ions as the metal ion present has no effect whatsoever
on the removal of acid with the solvent. The process
is effective for use in ion exchange ,processes in which
ions of more than one metal are in solution, such as 70
leach solutions formed from mixed metal ores provided
the cation exchange agent is operative for the metals.
IThe invention is equally effective for recovery of acids
in processes wherein recovery of pure acid free from
metal compound impurities is the objective, the metal 75
3,676,106
8
References Cited
UNITED STATES PATENTS
3,479,378 11/1969 Orlandini et al. 75-117
3,211,526 10/1965 Crouse 23-172
3,514,267 5/1970 Sherrington et al. __ 23-19 R-X
3,455,677 7/1969 Litz .:. 23'-'-19 R-X
3,259,472 7/1966 Rice 23-22 X
2,992,894 7/1961 Hazen et al. 75-101 BE UX
3,3'33,924 8/1967 Hazen et ai. 23-172 X
3,558,288 1/1971 Burrows 75-101 BE UX
GEORGE T. OZAKI, .Primary Examiner
10
US. Cl. X.R.
15 75-101 BE, 117, 121; 23-19, 312 ME; 210-24, 38
7
hydrogen exchange agent for metal ions in· solution
until the pH of the aqueous solution reaches a given
point;
(c) contacting the aqueous solution with a solvent extractant
for hydrogen ions in an organic phase until 5
the acidity is substantially decreased to a given point;
(d) repeating alternate contact of the aqueous solution
with hydrogen ion exchange agent and solvent extractant
until substantially all of the metal ions are
removed from the aqueous solution;
(e) stripping acid from the organic extractant and returning
it to the system to leach ore; and
(f) stripping the metal from the hydrogen ion exchange
agent and recovering it with the hydrogen ion
exchange agent being purified for reuse.