United States Patent [19]
Goren et al.
[II] 3,927,169
[45] Dec. 16, 1975
[54] ION EXCHANGE PROCESS FOR THE
RECOVERY OF COPPER
[52] U.S. CI. 423/24; 75/101 BE; 252/182
[51] Int. CP C01G 3/00
[58] Field of Search 423/24; 75/101 BE, 117;
260/438.1, 526.5, 539
[75] Inventors: Mayer B. Goren, Denver; Enzo L.
Coltrinari, Arvada, both of Colo.
[73] Assignee: Hazen Research, Inc., Golden, Colo.
[22] Filed: Mar. 11, 1974
[21] App\. No.: 450,058
Primary Examiner-Oscar R. Vertiz
Assistant Examiner-Brian E. Hearn
Attorney, Agent, or Firm-Sheridan, Ross & Fields
Swanson 75/l17
Cook et al. 75/117
Kane et aI... 75/1 0 1 BE
2/1969
5/1972
5/1974
3,428,449
3,666,446
3,810,827
[57] ABSTRACT
A process for recovering copper values from an acidic
aqueous medium which comprises contacting the medium
with an organic solvent having dissolved therein
a copper extraction reagent comprising a 2-hydroxy
benzophenoxime or mixtures thereof and as an extraction
accelerating agent therefor an a-halo carboxylic
acid or a thioglycolic acid or oxidation product of the
latter. The invention includes the compositions comprised
of 2-hydroxy benzophenoximes and the copper
extraction accelerating agents.
17 Claims, 2 Drawing Figures
References Cited
UNITED STATES PATENTS
7/1949 Carson 260/438.1
9/1951 Morway et al... 260/526.5
11/1957 Westfahl 260/526.5
2,475,350
2,567,023
2,812,345
[56]
EFFECT OF REAGENT C3 AND C4 ADDITION TO
10% L1X64N ON COPPER EXTRACTION RATE
90
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it:
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IU
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0
~ 70
.
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0<l 60
0
...J
!::!
z
<l 50 (!) a::
0
40
30
0 2 3
OF PASSES
100
u.s. Patent Dec. J6, 1975 Sheet 1 of 2 3,927,169
EFFECT OF REAGENT C3 AND C4 ADDITION TO
10% L1X64N ON COPPER EXTRACTION RATE
30
100
1
90
~
-:::> L1X64N+C3
0:::
e-n
-....J :::> 80 L1X64N + C4
0w
LL
0
~ 70
0
.,.
(!) z-
0 « 60
0
....J
U
Z«
50 L1X64N ONLY (!)
0:::
0
40
o 1 2
NO. OF PASSES
3
u.s. Patent Dec. 16, 1975 Sheet 2 of 2 3,927,169
(\J 0
fw
Z f-
0 <I: CJ w
0::: Cf) f-
<I:
0 Q I 0 0 a..
<I: Z
Cl.. U
<:t a..
- Z U 0::: <I: I- 0
(J) cq 0::: 0 C\I
Z 0::: 0 0
<I: w Z ~ a..
If) a..
fJ 0::: (,) 0
(,) W
~ f- a.. Z Z a..
W 0 0 0
~ (,)
<I: Z
W ~ IJ..
0::: 1D 0
X
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0 -l -l
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3,927,169
1
ION EXCHANGE PROCESS FOR THE RECOVERY
OF COPPER
BACKGROUND OF THE INVENTION
The solvent extraction process is finding increasing
application in the field of extractive metallurgy. It is
commercially used for the recovery of uranium, copper,
tungsten, molybdenum, rare earths, beryllium, and
other metals. Its wide application is because of the
availability of organic solvents with specifically selective
properties for a given element. The specific organicsolvent
can be used. to extract from an aqueous
solution and purify one metal element from a mixture
containing many contaminants.
The most recent wide use of solvent extraction is for
the recovery of copper from dilute sulfuric acid solutions
such as those obtained by leaching a copper oxide
ore. This use has been made possible principally by the
development of specifically copper selective solvents
such.as the extractants sold by Ashland Chemical Co.
under the trade name Kelex, and those sold by General
Mills Co. under the trade names, LIX 63, LIX 64, LIX
64N and LIX 70, the latter three including substituted
2-hydroxy benzophenoximes as the active extractant.
The copper selective solvent sold under the trade
name LIX 63, an alpha hydroxy oxime, is not operative
in solutions of the acidity normally encountered in acid
leaching while certain other types such as the sulfonates
and organo phosphates are non-selective and thus
have no present use in copper recovery.
The equipment for the application of solvent extraction
to extractive metallurgy has usually consisted of
multiple stage counter-current mixer-settler systems in
which the barren organic solvent and the pregnant
aqueous stream (usually a leach liquor) are mixed together
for a given period of time after which they are
permitted to separate in a settling reservoir. The solvent
and aqueous then flow in opposite directions to
the next stage of contact.
During the mixing step in conventional systems for
copper recovery, the driving force for the transfer of
the copper from the aqueous to the organic phase (or
in the case ofstripping, the transfer from the organic to
the aqu~ous phase) depends upon the difference in
concentration of copper in the aqueous and the organic
phases. If agitated long enough, eventually a chemical
equilibrium is achieved and no further transfer of copper
takes place between the aqueous and the organic.
The concentrations at which equilibrium is reached will
be dependent on the ion exchange agent, the acidity of
the solution, temperature, etc. In order to achieve maximum
efficiency in the system, it is highly desirable to
. have each mixer come as close as possible to this chemical
equilibrium before the material leaves the mixer
and flows to the settling tanks.
The size of the mixing equipment which is required to
achieve chemical equilibrium within a given time will
depend fundamentally on the extraction rate of the
particular ion exchange agent being used. It is known
that those ion exchange agents which have been developed
specifically for the extraction of copper are much
slower in their extraction rate than is the ion exchange
agent used specifically for extraction of some other
metals, as for example, uranium. The extraction of
uranium with a tertiary amine in acid solution of pH 1.5
is very fast, a matter of seconds, whereas the extraction
2
of copper from acid solution of that pH by LIX 64, (a
2-hydroxy substituted benzophenoxime) is quite slow,
commonly requiring as long as 4 minutes to reach equilibrium
in a batch agitated system at room temperature.
5 Because the solution flow rates in a copper leaching
plant are very large, the size of the mechanically agitated
vessels required for a mixing system to contain
and mix the required solvent and aqueous for this long
a time are large and expensive. In addition, in a contin-
10 uous mixing system it is not possible to achieve the true
chemical equilibrium that·is achieved when materials
are agitated in a batch. This is because of the well
known phenomenon of short circuiting. In fact, as a
practical matter; a mixer designed for continuous cop-
IS per extraction is calculated on the basis of only 80
percent of the extraction equilibrium that would be
achieved in a batch tank having the same residence
time.
The dollar value per unit volume of a copper leach
20 solution containing a few grams per liter of copper is
very low, thus the capital investment for an appropriate
mixing system is quite high for the amount of copper
which is being treated. The depreciation costs, therefore,
per pound of copper are high and this diminishes
25 the value of the solvent extraction process for the copper
industry. Further contributing to the diminished
value of the process is the fact that large amounts of
expensive reagents are tied up for prohibitive times.
Much of this disadvantage would be overcome if it
30 were possible to accelerate the rate of transfer of copper
from an aqueous leach liquor to the ion exchange
agent and its reverse, the stripping of copper from ion
exchange agent into an acid electrolyte. This objective
is achieved by the present invention through which the
35 rate of extraction of copper from an acid solution by
the specified copper extractants, LIX 64, LIX 64N and
LIX 70, is enormously accelerated by the addition of
small quantities of an a-halo carboxylic acid or a thioglycolic
acid or an oxidation product of a thioglycolic
40 acid, the latter three components being referred to
hereinafter as copper extraction accelerating agents.
SUMMARY OF THE INVENTION
The invention relates to the use of the copper extrac-
45 tion acceleration agents as additives to the 2-hydroxy
benzophenoximes represented by the trade name products
LIX 64, LIX 64N and LIX 70 sold by General
Mills, Inc., to greatly increase the rate at which these
latter products extract copper when used as ion ex-
50 change extractants to recover copper from acid solution.
It comprises a method for recovering copper values
from acidic aqueous solutions by contacting the
solution with a water-immiscible organic phase having
a density different from that of the aqueous phase com-
55 prised of an organic solvent having dissolved therein as
an active extractant a 2-hydroxy benzophenoxime or
mixtures thereof with one or more of the extraction
accelerating agents. The invention includes the composition
comprised of 2-hydroxy benzophenoximes and
60 the copper extraction accelerating agents.
DETAILED DESCRIPTION OF THE INVENTION
2-hydroxy benzophenoximes operative for the invention
include those disclosed in U.S. Pat. No. 3,428,449
65 issued to Ronald F. Swanson on Feb. 18, 1969. These
compounds are ion exchange extractants for copper
values in acid solutions. Individual compounds or mixtures
thereof may be used. Methods for making these
3,927,169
H 0 I ~
R-S-C-C-OH k
~o
are CH,,-(CH,)x-S-CH,-C-OH
wherein X is 7-20,
55
in which R is an aliphatic group, aryl or an araliphatic
60 group.
Representative of the above compounds which are
operative
4
groups are pentenyl, hexenyl, octenyl, decenyl,
dodecenyl, octadecenyl and the like. It is preferred that
such groups contain less than about 2 double bonds and
more preferably a single double bond. The R" portion
5 of the ether groups can be the saturated and ethylenically
unsaturated aliphatic groups as described above.
The R" portion of the said ether groups is preferably an
alkyl group. In addition, the saturated, ethylenically
unsaturated and ether groups may contain inert substit-
10 uents such as halogen, ester, amide, and the like. Likewise,
the aromatic nuclei can contain inert substituents.
By inert is meant that the said constituents do not affect
the solubility, stabiliity or extraction efficiency of the
compounds to any significant extent.
15 The benzophenoximes, which may be used in the
present invention, are those which have sufficient solubility
in one or more of the solvents disclosed below or
mixtures thereof to make about a 2% solution and
which are essentially insoluble or immiscible with wa-
20 ter. At the same time, the benzophenoxime should
form a complex with the metal, such as copper, which
complex, likewise, is soluble in the organic solvent to at
least the extent of about 2% by weight. These characteristics
are achieved by having alkyl, ethylenically
25 unsaturated aliphatic or ether substituents as described
on either ring. It is necessary to have substituents which
total at least 3 carbon atoms. This minimum may be
obtained by means of a total of 3 methyl groups distributed
on either one or on the two rings, by means of a
30 methyl and an ethyl group, by means of a propyl group,
etc. Usually it is prefered not to have more than 25
carbon atoms total in the substituents since these substituents
contribute to the molecular weight of the
oxime without improving operability. Large substitu-
35 ents, therefore, increase the amount of oxime for a
given copper loading capacity. In general, the branched
chain alkyl substituents effect a greater degree of solubility
of the reagent and of the copper complex and,
40 accordingly, these are preferred.
The 2-hydroxy benzophenoximes are suitable as a
copper ion exchange extractant component of the
mixed ion exchange reagent of the present invention
which includes at least one of the copper extraction
45 accelerating agents as the other component. Aliphatic
substituted thioglycolic acids and oxidation products
thereof, and a-halo substituted aliphatic carboxylic
acids are used as representative members of the extraction
accelerating agents to illustrate the· invention.
50 The thioglycolic acids which are operative as copper
extracting accelerators for the LIX compounds are
represented by the following formula:
OH NOH
O/ -cII -O
OH NOH
o-[~-o
/- "R.
R n
In
in which Rand R' may be individually alike or different
and are saturated aliphatic groups, ethylenically unsaturated
aliphatic groups or saturated or ethylenically
unsaturated ether groups (i.e. -OR") and m and n are
0, I, 2, 3 or 4 with the proviso that m and n are not both
O. The total number of carbon atoms in Rill and R'1l is
from 3-25. Rand R' contain I to 25 carbon atoms
when saturated aliphatic and 3 to 25 carbon atoms
when they are ethylenically unsaturated groups. Preferably,
the position ortho to the phenolic OH substituted
carbon atom is unsubstituted and also preferably the
positions ortho to the oxime carbon atom on the other
aromatic nucleus are unsubstituted. Branched chain
saturated aliphatic hydrocarbon substituents are preferred.
Compounds of the above type useful in the
present invention include the following:
2-hydroxy-3'-methyl-5-ethylbenzophenoxime
2-hydroxy-5-( I, I-dimethylpropyl )-benzophenoxime
2-hydroxy-5-( 1, I-dimethylethyl )-benzophenoxime
2-hydroxy-5-octylbenzophenoxime
2-hydroxy-5-nonyl-benzophenoxime
2-hydroxy-5-dodecyl-benzophenoxime .
2-hydroxy-2',4'-dimethyl-5-octylbenzophenoxlme
2-hydroxy-2',3',5'-trimethyl-5-octylbenzophenoxime
2-hydroxy-3,5-dinonylbenzophenoxime
2-hydroxy-4'-( l,l-dimethylethyl )-5-( 2-pentyl )-benzophenoxime
2-hydroxy-4'-( 1, I-dimethylethyl)-5-(2-butyl )-benzophenoxime
2-hydroxy-4-dodecyloxybenzophenoxime
2-hydroxy-4'-( 1, I-dimethylethyl )-5-methylbenzophenoxime
2-hydroxy-4',5-bis-( 1, I-dimethylethyl)benzophenoxime
As indicated from the above representative compounds,
various alkyl groups can be used as Rand R'.
And as set forth above, such groups may be branched 65
or straight chain. Various ethylenically unsaturated
groups can also be used as ~ and R' and th~ same may
be branched or straight cham. RepresentatIve of such
3
compounds are disclosed in the same patent. As disclosed
in the above patent, 2-hydroxy benzophenoximes
have the basic structure,
and are tailored with substituents to provide the required
solubility in suitable organic solvents. The extractants
include 2-hydroxy benzophenoximes in which
the substituents are alkyl radicals, ethylenically unsaturated
aliphatic radicals and alkyl or ethylenically unsaturated
aliphatic ether radicals.
The preferred 2-hydroxy benzophenoximes are those
represented by the formula:
5
~H" 0
~
CH3- -(CH,lx-S-CH,-C-OH
wherein X is 7-20,
o
-7'
CH,=CH-(CH,)x-S-,CH,-C-OH
wherein X is 7-20,
H,-C1\H . 0
/ ~-(CH'h-S-CH.-C -7' OH . -
H,-C
wherein X is 2-17,
3,927,169
6
the fully reduced and in the sulfoxide (e.g. partially
oxidized analogs), with their potential for weakly chelating
the copper ions; and finally, the enhanced acidity
of the hydrogens on the alpha carbon atom as corn-
S pared with those on simple aliphatic carboxylic acids.
This acidity again increases as one progresses from the
fully reduced (S-alkyl thioglycolic acid) through the
alkyl sulfinyl- and thence to the alkyl sulfonyl-acetic
acids. Although these substances have only meager
10 ability to extract copper from acidic aqueous solutions
of the pH ranges disclosed herein, they nevertheless are
apparently capable of rapidly forming weak copper
complexes which serve to transfer the Cu++ from the
aqueous to the organic phase, where a stronger interac-
IS tion with, and transfer to, the hydroxy phenoxime occurs
with concomitant regeneration of the transfer
accelerating agent.
The a-halo substituted carboxylic acids which may
be used as copper extraction accelerating agents for the
20 2-hydroxy benzophenoximes are represented by the
formula:
H 0
I~ ~
CH"-(CH'h-~-~-S-CH'-C_OH
25
R' 0
I ~
R-(CH.h-C-C-OH
- ~
wherein X is 5-17,
wherein R represents an aliphatic, aryl or an araliphatic
group, R' is a halogen atom, and X is a number from
30 7-20.
Compounds of the above type which are operative
are:
40 where X is 7-20,
where Xis 2-19,
~ 0 ~ ~
C 3 I·~ CH,-(CH,h-S-CH,-C_OH
35 !f OH
~
CH..-(CH.h- -C-OH
o _ ~
CH" <[I 0
CH3-1-(CH,h-i-c -7' OH
H,-\ H. If 0
'\ ~
C-(CH,h- -C-OH I . ~
H,-C
where X is 7-20,
where X is 7-20,
where X is 5-20,
~ ~H 0 V CH~CJ-ceH,)~'-CH,C -P OH .l<re X , 5-20.
Operative oxidation products of the thioglycolic 50
acids are the above compounds in which the sulfur
atom has one or two oxygen atoms attached to it. In the
first stage oxidation one oxygen atom is attached to the
sulfur atom and in the second stage oxidation two
atoms of oxygen an;: attached to the sulfur atom. 55
The preferred thioglycolic acids are S-tert-octyl thioglycolic
acid and S-tert-dodecyl thioglycolic acid, referred
to herein as C3 and C4 , respectively. The preferred
oxidation products are the sulfoxides and sul- h' X' 7 20
fones of C3 and C4
. . 60 w erem IS - ,
It is believed that the activity of the S-alkyl thioglycolic
acids and their oxidation products rests upon
three features: First, the significantly higher ionization
constants (Ka ) which increase from about 1-2 X 10-4
for the former to 1-2 X 10-3 for the fully oxidized alkyl 65
sulfonyl acetic acids, as compared with Ka of about 1-2
X 10-5 for simple carboxylic acids; secondly, the contribution
of the available electrons on the sulfur atom in
3,927,169
4.9
11.0
15
18
Copper Transfer Rate
Diluent Mg Cu/m'/sec.
EXAMPLE I
o
0.25
0.5
1.0
Reagent C,
Addition Vol. 'it
8
from leaching of an ore. During the extraction phase
the mixed extractant becomes loaded with copper or
other desired metal.
It is well known that LIX 64, LIX 64N and LIX 70
5 exhibit a selectivity for copper over other metals at pH
values below about 4. The most efficient organic to
aqueous ratio can be arrived at in accordance with
procedures well known in the art. After separation of
the loaded organic phase from the aqueous phase, cop-
10 per is stripped from it with a mineral acid, such as
sulfuric, in a stripping circuit.
The liquid ion exchange process may be performed
by continuous countercurrent or batch methods.
The extraction with the extractant mixture is per15
formed at a pH in the acid range. Leach solutions of
copper ores ordinarily have a pH range from about 1.7
to 3.0.
The invention is illustrated by the following comparative
examples, and the graphs of FIGS. 1 and 2 ilIustrat20
ing the effect of the additives C3 and C4 on loading and
stripping rates, respectively, of copper with LIX 64N.
Example 4 was performed as a blank to evaluate the
C3 and C4 reagents as copper extractants.
In all of the other examples the LIX 64N content of
25 the organic phase was 10 volume percent based on the
volume of the organic solvent, and the volume ratio of
additive to LIX 64N was I to 10. The solution from
which the copper was extracted in the examples had a
pH of 2.
30 Examples I and 5 were performed using what is referred
to as a "drop" test. This test comprises introducing
the organic phase drop by drop at the bottom of a
container holding the aqueous phase. The amount of
copper transferred to the organic phase is measured as
35 milligrams of copper per square meter of organic phase
transferred per second. The stripping test of Example I
was performed in a baffled beaker with a rotating mixing
element. All other examples, extracting and stripping,
including those on which the graphs of FIGS. 1
40 and 2 are based, were performed using a pipe extractor
as disclosed in U.S. Pat. Ser. No. 175,948 filed by
Wayne C. Hazen in the U.S. Pat. Office on Aug. 30,
1971 entitled "Solvent Extraction Method and Apparatus."
In accordance with this procedure the aqueous
45 and organic phases are flowed together through the
mixing section contail,ling baffled mixing elements in a
closed pipe at a velocity to mix the phast;s in the shortest
time without the formation of too Hiany small bubbles
with the dispersion formed being transferred to a
50 settling area where the aqueous and organic phases
separate by gravity. The pipe extractor used for the
examples was 6.5 feet long x % inch in diameter and
contained 105 mixing elements.
The example which follows using the drop test proce-
SS dure wa~ performed to illustrate the increase in extraction
rate of copper by LIX 64N obtained by the addition
of various amounts of C2 to LIX 64N. The organic
solvents for the extractant were Isopar Land Amsco
175. The aqueous phase was a copper sulfate solution
60 containing 2.0 gil of copper.
where X is 7-20.
7
0' Br 0 I CH'-<CH'h-t-c -f' OH
~ H
O'H ~ H Br-f'0 I ~-t=~-(CH")\-~-C-OH
~ ~ -. ~
CH
3
(CH
2
) X - CH/~,,~r- C ~~H
2V ~
where X is 7-20,
where X is 7-20,
The preferred a-halo substituted carboxylic acid is
a-bromo lauric acid referred to hereinafter as C2 . A
process for the recovery of copper using this compound
alone is disclosed in U.S. Pat. 3,251,646 with times
from three minutes to one hour being reported for
significant recoveries.
A problem in the extraction of copper is that the
leach solutions of its ores contain significant amounts
of iron and the extractant used must not extract prohibitive
amounts of iron to contaminate the copper extracted.
It has been found that the extractant mixtures
of this invention are satisfactory in this respect.
The water-immiscible organic solvents in which the
extractant mixture is dissolved to form the organic
phase are the conventional ones, such as, aliphatic
hydrocarbon solvents including petroleum derived liquid
hydrocarbons, either straight chain or branched,
such as, kerosene, fuel oil, etc. Various aromatic solvents
or chlorinated aliphatic solvents may be used,
such as benzene, toluene, xylene, carbon tetrachloride,
perchloroethylene and others. The solvent must be
substantially waterimmiscible, capable of dissolving the
extraction reagent, and must not interfere with the
function of the reagent in extracting the metal values
from acid solution. A suitable solvent is one sold commercially
by Humble Oil and Refining Company under
the trademark "Isopar L". It is a fractionated isoparaffinic
hydrocarbon with a mid-boiling point of approximately
380°F. Another suitable solvent is an aliphatic
naphtha sold by Amsco Division of Union Oil Company
of California under the trade name" 175 Solvent", and
is referred to herein as "Amsco 175". Also found suitable
are hexane, and a hexanetype solvent sold by
Humble Oil and Refining Company under the trademark
"Isopar C".
The benxophenoxime component of the organic extractant
mixture should have a solubility of at least 2%
by weight in the hydrocarbon solvent in the organic 65
phase and is insoluble or immiscible with water.
The aqueous phase from which the desired metal is
extracted is ordinarily the acid leach solution resulting
9
3,927,169
10
Conditions:
25 Organics 5 volume % reagent C-3 or C-4 in kerosene
(Amsco 175), preconditioned with 3N H2S04 then
76
86
93
95
95
95
'K Cu
Stripped
.61
.35
.18
.14
.14
.14
Organic Assav. GIL Cu
Loaded . Stripped
-continued
EXAMPLE 4
0.5
1.0
2.0
5.0
10.0
20.0
Contact
Time
Min.
Reagent C,
Addition
Vol. 'K .
The results show that with the contact time of 0.25
minutes the amount of copper stripped in the presence
of one volume percent of the C2 additive is doubled
over that stripped without the additive in the same
time. With the same volume content of the C2additive
more copper is stripped in two minutes than was
stripped in five minutes with no additive present. The
time to reach equilibrium concentration is decreased
by a factor of at least 4 when the C2additive is present.
The following example was performed to evaluate
the reagents C3 and C4 as copper extractants.
5
4.0
14
15
24
Copper Transfer Rate
Diluent Mg Cu/m'/sec.
-continued
Amsco 175
"
EXAMPLE 2
o
1.0
2.0
5.0
Reagent C,
Addition Vol. %
~t will be ~oted from the test results that copper extractIon
rate IS doubled with the addition of 0.25 volume
percent of C2, is tripled with the addition of more than 10
?~ ,,:olume perc:ent ofC2and at 5 volume percent ofC2
It IS Increased SIX times.
The fol~owing e~ample was performed, again to illustrate
the Increase In the extraction rate effected by the
addition of the reagent C2 to LIX 64N with the ion 15
exchange process being performed in the pipe extractor
described hereinbefore. The solvent for LIX 64N
and the C2 additive in this example was hexane. The
aqueous phase was a copper sulfate solution containing
3.1 gil of copper, 1.7 gil Fe+3 and 2.9 gil Fe+2. The 20
or~anic a~d aqueous ,rhases were flowed through the
mIxer sectIon of the pIpe extractor at a velocity orO.9-1
ft.sec. at a temperature of 23°e. Two passes of the
phases through the mixer were made with the following
results.
Reagent C, Contact
Addition Pass Time G/LCu
Vol. % No. Sec. Organic Raffinate
None I 6.5 .51 2.20
2 6.5 .98 1.69
Equilibrium 20 min. 1.62 .74
l<;l; I 6.7 1.14 1.45
2 7.0 1.49 1.03
Equilibrium 20 min. 1.60 .75
Organic
Cu Loading '7<
Of Equilibrium
32
61
71
93
Results:
Cu
50 Distribution
Aque- Assay, gil Cu <;l; Cu Coefficient
Or- ous Organic Raf- Extracted KOlA
ganic pH finate
C-3 1.0 0.002 2.04 0.1 0.001
2.0 0.026 2.04 1.3 0.013
55
C-4 1.0 0.002 2.02 0.1 0.001
2.0 0.018 2.02 0.9 0.009
It will be observed from the above example that over
twice as·much copper was extracted in the first pass
with the C2additive present than was extracted without 40
the additive in the same period of time. In the two
passes more than one and one-half times as much copper
was extracted with the additive than without the
additive.
The following example was performed to show the 45
effect of the presence of the additive C2 on the rate of
stripping copper from LIX 64N. The solvent used for
LIX 64N and the additive was Arnsco 175. The stripping
solution was a 3N H2S04solution containing 20 gil
of copper as copper sulfate. The propeller in the baffled
beaker in which the process was performed was
rotated at 900 RPM. An organic to aqueous ratio of 3: I
was used. The experiment was performed at a temperature
of 30°C with samplings being taken at various
intervals.
20 gil Na2S04
Aqueous Synthetic sulfate solution containing 2.06
gil Cu, and 2 gil Na2S04
Contact 01A ratio 1/1
Contact time 5 minutes at pH
Aqueous pH Adjusted with IN NaOH
Temperature 23°C
EXAMPLE 3
Reagent C,
Addition
Vol. "k
None
"
1.0
Contact
Time
Min.
o
0.25
0.5
1.0
2.0
5.0
10.0
20.0
o
0.25
Organic Assay, GIL Cu
Loaded Stripped
2.22
1.50
1.45
1.32
1.00
.44
.17
.15
2.58
.84
<;l; Cu
Stripped
32
35
41
55
80
92
93
67
The results show that the C3 and C4 reagents do not
appreciably extract copper under the conditions set
60 forth.
The following example was performed to illustrate
the effect of the reagents C3 and C4 on the copper
extraction rate of LIX 64N, the experiment being performed
by the drop test described hereinabove. The
65 solvent for the LIX 64N and the C3 and C4 additives
was Arnsco 175. The aqueous phase, i.e., the copper
sulfate solution, contained 1.9 gil copper, 2 gil Fe+3
and 2 gil sodium sulfate.
11
EXAMPLE 5
3,927,169
12
EXAMPLE 7
Reagent Addition Copper Transfer Rate Contact Assa\'. GIL
Mg Cu/M'/Sec. 5 Reagent Pass Time Org,mic . Raffinate
Addition No. Sec. Cu Fe Cu
None 4
0.5 Vol. 'Il c;-,a 20 None I 6.5 .57 .003 2.38
1.0 30 2 .88 .005 1.88
2.0 41 3 1.16 .006 1.59
0.5 C, 13 I'll C" I 5.9 1.22 .004 1.19
1.0 15 2 6.5 1.49 .007 .89
2.0 12 10 3 5.9 1.60 .009 .81
I'll C, I 5.9 1.07 .003 1.42
2 6.5 1.43 .006 .98
3 5.9 1.59 .008 .85
Organic
Cu Loading 'Il
Of Equilibrium
The results show that, in the same times, as compared
to copper extraction with no additive present, extraction
rates were increased by factors of 5, 7.5, and 10 15
with, respectively, 0.5, I, and 2 volume percent of C3
present. Likewise, extraction rates were increased by
factors of 3, 3.8, and 3, respectively, with the use of
0.5, I and 2 volume percent of C4 additive.
The following example was performed, again, to iIIus- 20
trate the effect on copper extraction rate of the presence
of the reagent C3. The solvent for LIX 64N and
the reagent was Amsco 175. The aqueous phase comprised
a copper sulfate solution containing 3.1 gil of
copper, 1.7 gil Fe+3 and 2.9 gil Fe+2 . A pipe extractor 25
was used. A flow velocity of 0.9 ft/sec of the liquids was
used. An organic to aqueous ratio of 1.5: I and a temperature
of 23°C were used.
EXAMPLE 6
Reagent C" Contact
Addition Pass Time Assa\,. GIL Cu
Vol. 'Il No. Sec. Organic - Raffinate
None I 6.9 .55 2.20
2 6.8 .85 1.67
Equilibrium 20 Min. 1.54 .73
I'll I 7.0 1.24 1.15
2 6.8 1.39 .85
Equilibrium 20 Min. 1.50 .76
The example shows that with essentially the same
contact time, the amount of copper extracted using 1
volume percent ofCa was almost doubled in two passes
over that extracted with no additive present.
The example shows that using essentially the same
contact time, the amount of copper extracted was increased
by a factor of 1.7 by the addition of I volume
percent of reagent C3 . Likewise, copper extraction
increased by a factor of 1.6 in the same time by the
addition of I volume percent ofC4 additive. The example
also illustrates that the presence of either of the
reagents C3 or C4 does not increase iron extraction to
any appreciable extent.
The following example was performed to illustrate
the effect ofCa and C4 additives on the rate of stripping
copper from LIX 64N. The organic solvent used was
Isopar C. The strip solution was a 3N sulfuric acid
solution containing 20 gil copper as copper sulfate. A
pipe extractor was used. The velocity of liquids through
35
55
83
93
the mixing section of the pipe extractor was I ft/sec. An
organic to aqueous ratio of 1: 1 and a temperature of
23°C were used.
EXAMPLE 8
Organ ic Assay. GIL Cu
Reagent Pass Loaded Stripped 'Il Stripped Stripping Rate
Addition No. Cu Fe Cu Fe Cu Fe GIL Cu/Sec.
None 0 1.16 .006
I .63 .003 46 50 .082
2 .35 .0008 70 87 .043
3 .18 .0008 84 87 .026
1% C" 0 1.60 .009
I .37 .003 77 67 .19
2 .087 .0006 95 93 .044
3 .058 .0004 96 96 .004
I'll C, 0 1.59 .008
1 .62 .003 61 63 .15
2 .23 .0009 86 89 .060
3 .11 .0005 93 94 .018
The following example using the pipe extractor was
performed to show the effect of the presence of the
reagents C3 and C4 on the copper loading rate of LIX
64N. The organic solvent for the LIX 64N and additives
Ca or C4 was Isopar C. The aqueous phase comprised
copper sulfate solution containing 3.1 gil of
copper, 1.7 gil of Fe+a and 2.9 gil Fe+2 . A flow velocity
of 0.9 ft/sec was used. Three passes were used.
The example shows that in the same contact time,
during the first pass with one volume percent of C3
present, the copper stripping rate was increased by a
factor 2.3, and with one volume percent of C4 present,
stripping rates were increased by a factor of 1.8. Com-
65 parable results were obtained in the second and third
passes.
The final example was performed using as additives
the oxidation products ofC4 , one of the products being
3,927,169
H 0 I ~
R-S-C-C-OH
~
wherein R is an aliphatic, aryl, or an araliphatic group,
and tfte oxidation product of the thioglycolic acids has
the formula:
14
The graph of FIG. 2 shows graphically the accelerated
stripping rate achieved by the addition of Ca and
C4 additives to LIX 64N. A pipe extractor was used.
One percent of the additive based on the amount of
5 solvent was used. The organic solvent was Isopar C. A
flow velocity of I ft/sec was used. The tests were performed
at 22°C. The strip solution was a 3N sulfuric
acid solution containing 20 gil of copper as Cu S04'
It will be noted from the graph of FIG. 2 that the
10 stripping rate was accelerated by factors of 2 and 1.6 by
the presence of C3 and C4 additives, respectively.
The volume percent of the C2 • C3 and C4 type additives
based on the amount of LIX 64N reagent (2hydroxy
benzopnenoxime) can vary from 0.1 to 100
15 percent, with a preferred volume percent of additive to
reagent being about 1 to about 20, The contact time of
the mixed extractants (2-hydroxy benzophenoximes
like LIX 64N plus additive) with the aqueous phase for
20 extraction, irrespective of the type mixing equipment
used, can vary from a few seconds up to about one
minute with satisfactory results being obtained. This is
in contrast to a contact time of at least two minutes
required for satisfactory copper extraction with the
25 LIX compounds alone in commercial operations. The
contact time of the stripping agent with the mixed extractant
loaded with copper is from a few seconds up to
about one minute for satisfactory stripping. Again, this
is in contrast to a time of about two minutes contact
30 time for satisfactory stripping of copper from the LIX
reagents without the additives.
The chief advantages of the process are that the addition
of the copper extraction and stripping acceleration
additives increases the copper extraction rate of the
35 LIX reagents up to a factor of at least 3 and the rate at
which copper can be stripped from them by a factor of
up to at least 2. The result is a decided economic improvement
in that much less capital equipment is required,
and the amount of expensive agent which is tied
40 up and the time it is tied up are drastically reduced
from a comparative economic standpoint.
What is claimed is:
1. A process for recovering copper values from an
aqueous medium comprising contacting the aqueous
45 medium with a water-immiscible organic solvent having
dissolved therein an extractant comprising:
a 2-hydroxy benzophenoxime having a solubility of at
least 2% by weight in the organic solvent and as a
copper extraction accelerating agent for the 2hydroxy
benzophenoxime a compound selected
from the group consisting of thioglycolic acids and
oxidation products of thioglycolic acids.
2. The process of claim 1 in which
the thioglycolic acid has the formula:
55
EXAMPLE 9
o 0
CI2H,,-SII-CH2COOH and CI2H25-"0-CH2COOH
o
Test Control No.1 No.2
Additive (1% C.l (Sulfoxide) (Sulfone)
Contact Time, Sec. 6.9 6.7 6.5
Drop Size, cm3/Drop .041 .029 .026
Surf.Area, cm2/ Drop .58 .46 .42
Temp.,oC 23 25 23
Organic Assay
G/LCu .14 .22 .22
Transfer Rate
Mg Cu/m2/sec. 14.4 20.8 21.0
The results show that the sulfoxide and sulfone are
even better copper extraction accelerators for LIX 64N
than C4. In substantially the same time 45 percent more
copper was exextracted with LIX 64N containing these
additives than was extracted by LIX 64N containing
the C4 additive alone.
Reference is now made to the graph of FIG. 1 depicting
comparative results of experiments performed in
extracting copper with LIX 64N with the addition of
the C3 and C4 reagents and without the addition of any 50
reagents. One volume percent of the reagents C3 and C4
based on the organic solvent was used. This amounts to
a volume ratio of 1:10 of additive to LIX 64N. The
organic solvent was Isopar C. A pipe extractor was
used. The aqueous phase was a copper sulfate solution
containing 3 gil copper, 2 gil Fe+3 and 3 gil Fe+2. The
solution had a pH of 2.0 at the start. A flow velocity of
1 ft/sec was used. An organic to aqueous ratio of 1.5/1
and a temperature of 21 ° - 23° were used. Three passes
were made. Essentially the same contact time for all 60
passes was used.
The graph of FIG. 1 shows that copper extraction
rate with 1 volume percent of C3 present increased by
a factor of about 3 on the first pass, 1,6 on the second
pass and 1.3 on the third pass. Likewise, with one vol- 65
ume percent of C4 present, the rate of copper extraction
increased by a factor of about 2.3 on the first pass,
1.5 on the second pass, and 1.3 on the third pass.
13
a partial oxidation product and the other a complete
oxidation product. The oxidation products were made
in the conventional manner by oxidation with hydrogen
peroxide in the presence of glacial acetic acid, one-half
the stoichiometric amount of hydrogen peroxide for
complete oxidation being used for the partial oxidation
and the complete stoichiometric amount being used for
complete oxidation. The sulfoxide was produced by
partial oxidation and the sulfone by complete oxidation,
and these additives are so identified in the following
table of results. They are represented by the following
chemical formulas:
Using the drop test procedure described above in
separate tests of the sulfoxide and sulfone, 10 volume
percent LIX 64N and one volume percent additive
were mixed in Arnsco 175 as the solvent and contacted
with an aqueous solution containing 2.0 gil Cu, 3 gil
Fe+2, 2 gil Fe+3 , and 2 gil Na2S04 with the following
results which include comparative results obtained on a
control using one volume percent C4 additive.
15
3,927,169
16
30
11. The process of claim 7 in which at least one R
group of the 2-hydroxy benzophcnoxime is in the 5
position.
12. The process of claim 1 in which the thioglycolic
acid is a member selected from the group consisting of
octyl thioglycolic acid and its oxidation products.
13. The process of claim 1 in which the thioglycolic
acid is a member selected from the group consisting of
dodecyl thioglycolic acid and its oxidation products.
14. In the process for recovering copper values from
an aqueous medium which comprises contacting the
aqueous medium with an extractant comprising a 2hydroxy
benzophenoxime followed by stripping the
copper from the loaded extractant to recover the copper,
the improvement which comprises stripping the
copper from the extractant in the presence of a copper
stripping accelerating agent for the 2-hydroxy benzophenoxime
comprising a member selected from the
group consisting of a thioglycolic acid or an oxidation
20 product of a thioglycolic acid.
15. The process improvement of claim 14 in which
the stripping is performed in a time of up to about one
minute.
16. A process for recovering copper values from an
25 aqueous medium comprising contacting the aqueous
medium with a water-immiscible organic solvent having
dissolved therein an extractant comprising:
a 2-hydroxy benzophenoxime having a solubility of at
least 2% by weight in the organic solvent and as a
copper extraction accelerating agent for the 2hydroxy
benzophenoxime an organic compound
containing the group
OH NOH
/o-~-< Z R R'
In n
wherein R is an aliphatic, aryl or araliphatic group, R1
is oxygen and R2 is oxygen or an electron pair.
3. The process of claim 2 wherein the aliphatic group
in all structural formulas has from 7-20 carbon atoms.
4. The process of claim 1 in which the aqueous me- 5
dium is contacted with the extractant for a time up to
about one minute.
5. The process of claim 1 in which the accelerating
agent is present in an amount from about 0.1-100 vol- 10
ume percent of the 2-hydroxy benzophenoxime.
6. The process of claim 1 in which the 2-hydroxy
benzophenoxime is a member selected from the group
consisting of alkyl substituted, ethylenically unsaturated
aliphatic substituted and alkyl or ethylenically 15
unsaturated aliphatic ether substituted 2-hydroxy benzophenoximes.
7. The process of claim 6 in which the 2-hydroxy
benzophenoxime has the formula:
50 * * * * *
in which a sulfur atom is separated from a carboxyl
group only by one lower alkyl group.
17. A process for recovering copper values from an
40 aqueous medium comprising contacting the aqueous
medium with a water-immiscible organic solvent having
dissolved therein an extractant comprising:
a substituted hydroxy benzophenoxime having a solubility
of at least 2% by weight in the organic solvent
and as a copper extraction accelerating agent for
the substituted hydroxy benzophenoxime a compound
selected from the group consisting of thioglycolic
acids and oxidation products of thioglycolic
acids. .
in which Rand R' may be individually alike or different
and are saturated aliphatic groups of 1-25 carbon 35
atoms, ethylenically unsaturated aliphatic groups of
3-25 carbon atoms or -OR" where R" is a saturated
or ethylenically unsaturated aliphatic group as defined,
m and n are.O, I, 2, 3 or 4 with the proviso that both are
not 0 and the total number of carbon atoms in Rill and
R'1l is from 3-25.
8. The process of claim 7 in which R of the 2-hydroxy
benxophenoxime is an ethylenically unsaturated group.
9. The process of claim 7 in which R' of the 2- 45
hydroxy benzophenoxime is an unsubstituted branched
chain aliphatic hydrocarbon group.
10. The process of claim 7 in which R of the 2hydroxy
benzophenoxime is an unsubstituted branched
chain hydrocarbon group.
55
60
65