Note: Descriptions are shown in the official language in which they were submitted.
~ h-Ls invention relate~ to a procesa of recovering
indium and, more particularly, to a proce~ of obtaining
lndium by 3electively extracting indium ions from an
aqueous solution containing indium ions by a liquid-
liquid ion-exchange proce~s and then back-extracting the indium
ions into an aqueous solution acidified by sulfuric acid.
Indium does not occur as ores by itself but
exists in very ~mall quantities in ores mainly for zinc
and lead. Therefore, a~ industrial raw material for
indium is mainly an intermedi~ta product containing
concentrated indlum by-produced in a smelting step for
zinc, etc., from the ores described above~ A ~eneral
process o~ recovering indium includes a wet process
wherein a raw material for indium, i. e., the above-de~cribed
intermediate by-product i~ leached by a mineral acid, etc.,
and an indium component ln the leached solution is
separated from components of other metals and purified
into a concentrated ~orm. As a conventional wet process~
there is included a neutralization process for the leached
solution, an ion-echange process, and a liquid-liquid ion-
exchange process.
The neutralization process is mainly composed of a
technique for precipitating indium hydroxide from an aqueous
leaching solution of the above-described ores but since the
product obtained by such a process is poor in purity, it is
~ 3 --
required for obtaining the commercial grade product to repeat
the purification of the indium product. The purification
entails many steps such as a crude neutralization, filtration,
dissolution, copper removal, neutralization for purification,
etc., and hence the process is complicated and lacking in
economic value.
The ion-exchange process uses an ion-exchange resin
but in the process the separation efficiency between indium
and iron is poor and the concentration ratio of indium is low.
Furthermore, since the process requires a highly concentrated
acid solution containing hydrochloric acid or a halide sllch
as chloride for eluting indium from the ion-exchange resin,
the process is unsuitable for the treatment of indium-
containing solution employed in a general wet-system zinc
smeltery. In other words, intermixing of a halide or a
halogen acld in the wet-system zinc smelting system
~ (sulfuric acid system) causes various troubles in the zinc
`~ electrolysis step and others.
- The liquid-liquid ion-exchange proce~ a ~olvent extraction process using an organic solvent immi~cible with
water and as the-organic 301uvent used for the process,
: there are known ether~ i~obutyl methyl ketone (MI~K),
tributylphosphorlc acid (TBP), a tertiary fatty acid, a
monoalkylpho~phoric acid, and a dialkylpho~phoric acid.
The ether extraction process and MIBK extraction
process amorlg the liquid-liquid ion-exchange processes
described above cannot be applied to the extraction of
' ' .1
.
~4~7~i~
-- 4 ~
indium from a sulfuric acid~acidic solution containing
indium but an aqueous halogenic acid solution containing
indium is mainly treated by these processes. There are
problems in the application of these processes to a
general wet-type zinc smelting system. Also, in these
processes there is a fault in that a large amount of
ether or MIBK is dissolved in an aqueous solution treated,
which results in increasing the loss of the solvent as
well as causing a problem that the solvent dissolved in
the aqueous solution has undesirable effects on other steps.
The tributylphosphoric acid (TBP) extraction
process is mainly employed for the extraction of
indium from a hydrochloric acid-acidic ~olution since the
extraction efficiency of indium from a sulfuric acld-
acidic solution by the proceYs is very low and the
process i9 relatively widely used in the field without
causing the di~solution of the ~olvent in the aqueous
solution. IIowever, the solvents also extract all metals
which are able to form chlorocomplex saits and hence in
20 order to recover indium alone? additional positive
separation ~teps are required, which restrlct~ the
utilization of the proces~. .
The extraction process u~ing a tertiary fatty acid
: can be applied to extract indium ~rom aqueous ~olution
other than an aqueous halogenic acid-acidic solution, such
as an aqueous sulfuric acid-acidic solution but Rince
- s -
the solvent extracts ferric ions (Fe ) more preferentially
~han indium ions, it is necessary first to reduce ferric
ions in the aqueous solution to ferrous ions (Fe ). Also,
the pH at which the solvent extracts indium is limited to
a relatively narrow range of 2.5-3.5 and the separation
efficiency of indium from other heavy metal ions is low;
the purity of indium in a back-extracted solution obtained
tends to be easily reduced. Consequently, for purifying
the back-extracted solution, other processes such as the
above described TBP extraction process must be also employed
~: together.
The inventors have found that a mixed solvent of
a monoalkylphosphoric acid and/or a dialkylphosphoric acid
and a trialkylphosphoric acid in a definite ratio has an
extracting property for heavy metal ions and a back-extractive
property never previously attained in the use of the
monoalkylphosphoric acid, dialkylphosphoric acid, or
trialkylphosphoric acid individually, and have discovered the
present invention as the result of investigations on the
utilization of the properties of the solvent mixture for
the effective recovery of indium from an aqueous solution
- containing indium.
The object of this invention is, therefore, to
provide a process of obtaining a substantially pure indium
concentrate by a liquid -liquid ion-exchange process wherein
. indium ions are effectively extracted with an organic solvent
7~
-- 6 --
solution from an aqueous ~olution contalning indium ions
and back-extracting the indium ions with an aqueous
sulfuric acid-acidic solution.
Thus, according to this invention, there ~a
provided a procesa of recov~ring indium including the
steps o~ ad~usting the pH of an aqueou~ solution containing
indium lons to 0,2~-4.5~ mixing the aqueous solution with
an organlc solvent ~nlutlon prepared by diluting an
extracting reagent co~taining a monoalkylpho~phoric acid
and/or a diQlkylphosphoric acid and a trialkrlphosphoric
acid in 1 : 2-~ by volume ratio with a phase-stabilizing
water-immiscible organi.c solvent to extract the indium
ions into the organic solvent solution, and then mixing
the organic ~ol~ent soiution with an aqueou~ sulfuric
acid-acidic solution containing 100-500 g/liter of free
sulfuric acid, so that the indium ions are back-extracted
from the organic solvent solution into the aqueous sulfuric
~: acid-acidic solution to provide a substantially pure aqueous
sulfuric acid-acidic solution containing indium in
concentrated state.
In the accompanying drawings:
Eig. 1 is a graph showing the extraction equilibrium
curves of In3 , Fe3 , and Zn2+ from an aqueous sulfuric acid
solution by a D2EHPA solvent solution,
1~4~'7~ ~
-- 7 --
P`ig. 2 i8 ~I graph showing the extraction
equllibrium curves of In3~, Fe3+, and Zn2+ from an aqueous
~ulfurio acid ~olution by the organic ~olvent solution
ln thi~ invention, and
Fig, 3 and Fig. 4 are gre.ph~ ~howlng the relation
between the extractabilities of In3+ and Fe3+ re~pectively
from an aqueous sulfuric acid solution by the organic solvent
solution of this inventlon and the extraction tlme required
for the extractions
By the convent~ onal extraction process using
a monoalkylphosphoric ~cid and/or a dialkylpho~phoric
acid, indium ions can be recovered by extraction from an
,
aqueous solution thereof having a relatlvely high sulfuric
acid concentration, i. e., the aqueou~ sulfuric acid
solution (sulfuric acid content of 500-12 g/liter) having a
pH of --10 to 0 6 pH as shown in Fig. 1 of th~3 accompanying
drawings. FigD 1 i9 ~I graph showing thet extraction .
equilibriums of` indium ions, ferric ion~ and zinc ions in the
case of mixing 100 ml of each aqueou~ sulfuric acid--acidic
~0 solution having each different sulfuric acid concentration
containing 52~-588 mgi/liter of indlum ion~ (In3+), 122--225
mg/liter of ferric ions (Fa3+) and 246--250mg/liter of
: zinc ions (Zn2+) with 100 ml of each organic solvent
solution comprising a mixture of di(Z--ethylhexyl)phosphoric
acid (D2E~PA~ and a para$`finic organic solvent, MSB 210
: .
,
~ 2
(t~ade name, made by Shell Chemical Co.) in 5 : 95 by volume
ratio as an extractiny solution. In Fig. 1, the ordinate
axis indicates the extractability and the abscissa the pH
of a sulfuric acid-acidic solution.
As can be seen from the Fig.!l, under the pH
condition for extracting indium ions in the above described
prior art process, ferric ions are simultaneously extracted
and hence one should first reduce the ferric ions dissolved
in an aqueous solution to ferrous ions. However, it is not
always easy to effect comple~e reduction of the ferric ions
in an aqueous solution, the accumulation of ferric ions in the
solvent repeatedly used in practical steps is unavoidable,
and hence the employment of back-extraction or stripping
must be considered. For the back-extraction of ferric ions
from an extracted solvent solution, an aqueous sulfuric acid-
acidic solution cannot be substantially used and hence a
halogenic ~olution, intermixing of which in an indium
extraction system is undesirable, must be employed at
,- . .
present in a wet-sy~tem zinc 4meltery as de~cribed above.
~urthermore, the back-extraction of indium lon itself
require~ two kind3 of halogen acld solutions each having
different concentration and thus, two stage~ of back-
extraction steps for ferric ion~ and indium ions are
ultimately required. : -
~ .
~L4~ 2
The tcrm "monoalkylphosphoric ac~d" and/or"dlalkylphosphorlc acid" include~ ~n alkylpyrophosphoric
acid, a monoalkylphosphinic ac~d, and a dialkylphosphinic
acid in ~ddition to a monoalkylphosphoric acid and a
dialkylpho~phoric acid~ and it is preferred a~ an oil-
soluble compo~md that the molecular welght of the alkyl
--
substituent be sufficiently large and the carbon number
thereof be 8-20.
Practical examples of the preferred monoalkyl-
phosphoric acids or dialkylphosphoric acids used in thisinvention are di(2-ethylhexyl)phosphoric acid (D2EHPA)~ di(l-
methylheptyl)phosphoric acid, 2-ethylhexylpyropho~phoric
acid, octylpyrophosphoric acid, 1,2-methylpropyl-395-
dimethylhexylphosphoric acid, 2-ethylhexylphosphoric acid,
and mixtures of the abo~e-described organic phosphoric
acids
The trialkylphosphoric acids used in this
in~ention include a trialkylphosphate, a trialkylphosphine
oxide, an alkyldialkylphosphinate, and a dialkylalkylphospho-
nate. It is preferred that the carbon number of thealkyl substituent be 4-8~ Practical examples of the
preferred trialkylphosphoric acid are tributylphosphoric
acid (TBP), trioctylphosphoric acid9 tripentylphosphoric
acid, trihexylphosphoric acid, triheptylphosphoric acid,
dibutylbutyl phosphonate, butyldibutyl phosphinate, and
mixtures of them.
.
-- 10 --
~67~Z
The extraction reagent containing the above-described
organic phosphoric acids is diluted by a phase-stabilizing
water-immiscible organic solvent. The diluting solvent is
insoluble in water and acts to dissolve an organic phosphoric
acid and an organic phosphorus compound in a stable manner
and reduce the viscosity thereof. Other necessary factors for
solvent are chemical stability, low toxicity, and high flash
point. Thus, there are aliphatic hydrocarbons, aromatic
hydrocarbons, and alkylaromatic hydrocarbons induced from
petroleum sources which comprise useful solvents. Practical
examples of solvents are toluene, xylene, kerosene, various
flash naphtha cuts, and mixtures of them. A particularly
preferred solvent is a deodorized mineral spirit which is a
mixture of higher paraffin hydrocarbons. (Commercially
available solvents used in this invention are MSB 210,
MSB 210L, DOSB-X, HAWS, Shell Sole A, Shell Sole AB,
Eskaid 100, etc., and trade names, made by Shell Chemical Co.).
The properties of the organic solvent solution
(hereinafter referred to as "organic phase A") formed by
diluting the extraction reagent with the above-described
organic solvent are described below in detail~
Fig, 2 is a gra~h showing the extraction
equilibrium of indium ions (In3 ), ferric ions (Fe3 ), and
zinc ions (Zn +) b~ the organic phase A in the experiment
'
- lOa -
7~;~
of thi~ invention, The equilibrlum curves are ln the
case of mixing 100 ml of each aqueous sulfuric acld solution
containing 478-613 mg/liter of In3+~ 60-2Z5 mg/liter of ~e3 ,
and 246-2go mg/liter of Zn2+ with 100 ml o~ an organic phase
A formed by mixing di(2-ethylhexyl)phosphoric acid (D2EHPA),
tributylphosphoric acid (TBP), and solvent paraffin MSB 210
(trade name, made by Shell Chemical Co.) in 3 : 12 : 85 by
volume ratio and th~ axis of ordinate indicate~ extractability
and the axis of abscissa the pH value of an aqueous suifuric
10 acid-acidic solution ,
As is shown in ~ig. 2, the organic phase A
shows a substantial indium extraction effect at pH higher
than 0.25 Also, indium ions precipitate a9 the hydroxide
at pH higher than 4.~ and hence the upper limit in the liquid-
liquid ion-exchange for indium is pH 4 5. That is, the
pH range for the extraction of indium by the organic phase
A is o,25-4.5. The pH range i9 shifted to a lower acid
side than the pH range for the extraction of indium in the
case of using a monoal~ylphosphoric acid or dialkylphosphoric
lO acid alone and hence the extraction treatment can be
per~ormad easily. The particularly remarkable feature of
the organic phase A is that it has a selective extracting
property for indium ions and the use of an aqueous sulfuric
acid solution ~or the back-extraction of indium ions becomes
possible by the u9e of the organic phase A of this invention
as will be described later, thereby the practicability of
the solvent extraction can be greatly increased. f
It is preferred that the mixing ratio of a
monoalkylphosphoric acid or a dialkylphosphoric acid to a
20 trialkylphosphoric acid in the organic phase A used in this
invention be 1 to 2-5. If the proportion o~ the trialkylphosphoric
acid is higher than the mixing ratio, the extracting property
for indium ions reduces, while if the proportion is lower
than the mixing ratio, the back-extracting property by an
aqueous sulfuric acid solution reduce9 In either case,
the use of such organic solvent solution causes undesirable
problems
- 12 -
~L~4~62
Also, as i9 clear rrom Fig~ 2, the organie phase
A does not extract zinc lons at pH lower than 1.5 and
henee when an aqueous solution contain9 zinc ions together
with indium ions, indium ions only can be extracted by
selecting the pH range for the extraction to 0.25-1,5,
An indium raw material usually eontains iron, in
particular iron in ferrie state in addition to zinc and the
aqueous leached solution thereof contains ferric ions.
The separation of the ferrie ions and indium ions ean be
easily practiced in the pH ran~e of this invention, whieh
is one o~ the novel features of this invention.
As i9 clear from the extraetion equilibrium
eurves of indium ions and ferrie ions in Fig. 2, the
extracting property for ferric ions becomes greatly poor
in the organic phase A when the pH of the aqueou~ solution
is lower than 1.0, in particular, lower than 0.7 and hence
indium ions can be selectively extracted in the pH range of
0.25-1.0, preferably 0.2~-0.7.
The results shown in Fig. 2 are in equilibrium
~0 states and in practical extraction the extraction rates also
take part in the extraction. The organic phase A of this
lnvention possesse~ a property that the extractien rate for
indium ions i~ far higher than that for ferric ions even
in an aqueous solution containing a considerable amount of
ferric ions. Therefore, it becomes possible by the use of
the organic phase A to substantially completely separate
indium ions from ferric ions.
3 --
~4f~7~i2
This i9 clear from ~lg. 3 and ~ig. 4. Fig. 3 and
Fig. 4 are the experimental results made by the inventors 9
which sho~ the relation~ between the extraction time and
the extractabilities for indium lons and ferric ions in
case of using the organic phase A.
The original aqueous solution used for obtainin~
the above results is 500~ml of an aqueous sulfuric acid-
acidic solution having a pH of 0,7 containing 90 mg/li-ter
of In3~ and 140-154 mg/liter of Fe3~ and the organic
phase A as the extracting reagent i~ 50 ml of an organic
solution consisting of 3% by volume D2EHPA, 12~o by weight
TBP, and 85% by volume MS~ 210.
As is understood from these figures, the indium
ions are extracted into the organic phase A in an amount
of about 60-70~ thereof by the mixing contact for 10 minutes,
while the ferric ions are not in the least extracted for
the first 5 minutes and about 0. 2% only of the ion~ are
extracted after the mixing contact of 10 minutes. ~urthermore,
the extraction rate for ferric ions is lgw even after then
and the extractability for ferric iohs after 60 minutes is
about 1% only.
As described above, the organic phase A shows an
excellent effect for the separation of indium ions from
ferric ions by the separability by the extraction equilibrium
and the difference in extraction rate and ~uch an effect
has never been attained by a conventional organic solvent.
Then, the back-extraction or stripping of indium
- 14 -
~ons extracted in the organic phase A i9 explai~ed below.
As described above, the extraction of total
indium ion~ can also be practiced by a conventionally known
extracting reagent containing a monoalkylphosphoric acid
or dialkylphosphoric ~cid individually but when the
indium ions are back-extracted ~rom the solution using an
aqueous sulfuric acid solution, the back-extraction is still
- imperfect even using a highly concentrated sulfuric acid
solution containing 490 g/liter of 9ulfuric aicd. Also,
in the mixing contact with a sulfuric acid 901ution
containing over 500 g/liter of sulfuric acid, a third
phase form~ between the solvent solution and the sulfuric
acid solution to reduce the phase separation and hence an
aqueous sulfuric acid-acidic solution cannot substantially
be used for the back-extraction of indium ions from the
solvent solution. This is al90 true in case of ferric ions
in the solvent solution.
On the other hand, when using the organic phase A,
it is possible almost completely to baek-extract the indium
20 ions extracted in the organic phase A with an aqueous sulfurie
acid-acidie solution and by inereasing the treatment eycle
times, the back-extraction of indium ions with 100 g/liter
(pH-0.3) of an aqueous sulfurie acid-acidie solution beeomes
possible. When using an aqueous solution of a low
proportion of sulfurie aeid, it is effieient to operate the
proeess in a multi-stage contact hy a eounter-eurrent system.
7~2
However, even when using the organic phase A, a third
phase forms in the mixing contact with an aqueous sulfuric acid-
acidic solution containing over 500 g/liter of sulfuric acid as
in the case of using a monoalkylphosphoric acid or a
dialkylphosphoric acid and hence the concentration of the
sulfuric acid-acidic solution used for the back-extraction of
indium ions from the organic phase A is in the sulfuric acid
range of 100-500 g/liter.
In other words, it is an important feature of this
invention that by using the organic phase A as an extracting
solution for indium, an aqueous sulfuric acid-acidic solution
can be used for the back-extraction of the indium ions from the
extracting solution and ultimately, a sulfuric acid-acidic
indium concentrate can be obtained, thereby the practicabiliLy
of the extraction process of indium is greatly improved.
The condition for the sulfuric acid concentration
in the back-extraction from the organic phase A is 100-500
g/liter as described above. Within that range the back-
extracting property of indium ions is better when the
concentration of sulfuric acid is as high as possible and
also the back-extraction property is better when the ratio
of a trialkylphosphoric acid to a monoalkylphosphoric acid
- and/or dialkylphosphoric acid is higher but if the back-
extraction is repeatedly practiced, the back-extraction
can be performed effectively even by employing the lower
- 16 ~ 7~
range in each cass In this invention the above--
described ratio is defined in the range of 1: 2-5
eonsidering the seleetive extraeting property of indium
ions from an original aqueous 901ution eontaining them
and the workability in the repeating baek-extraetlon of
indium ions with an aqueous sulfurie aeid solution.
Prior to extraetion of indium ions, the ferrie ions
in the organie phase A are baek-extraeted under sueh a baek-
extraetion eondition for indium ions. This means that the
lO organie phase A ean be regenerated by the baek-extraetion treat-
ment with the same sulfurie aeid solution, whieh is one of the
merits of this invention.
As described above, sinee the extraeting property
for ferric ions with the organic phase A from an original
aqueous solution is poor~ the amount of` ferrie ions
contained in the organic phase A is very small and henee
the amount of ferric ions entering the aqueous sulfuric acid
solution in the back--extraetion i9 also very small and the
existence of such a small amount of ferrie ions gives no
20 bad influences on the praeticability of the proeess of this
invention.
In addition, when the reeovery of the indium ions
from the back-ex-tracted sulfurie acid solution is praeticed
by a cementation process with aluminum, the ferric ions in
the sulfuric acid solution are easily reduced into ferrous
ions, whieh remain, in situ, in the solution, and henee
they give almost no had influenees on the purity of indium
- 17 -
~ ~7
metal reco~ered.
The cementation spent ~olution from which indium
has been recovered can be backed, as it i9, into the leaching
step in a ~.inc smeltery or indium extraction step That
is, ferrous ions in the cementation spent solution are
not extracted in the indium e~traction system together
with zinc and aluminum, when the solution i9 returned,
and there i9 no problem about the accumulation of ferrous
and ferric ion in the indium extraction system.
~urthermore, as an effect by the liquid-liquid
ion-exchange process of this invention using the organic
phase A, there is the advantageous separating property of
indium ions from other element ions than iron and zinc ions.
That is 9 the process of this invention can be suitably applied
to the recovery of indium from an indium-containing solution
which contains also other elements than iron and zinc, for
example dusts containing such elements as -tin, chlorine,
fluorine, arsenlc, etc., which al~o means that the proces3
of this inventioh can be utilized for the recovery of a
very small amount of indium.
Among the above-described element~, tin has a strong
affinity with indium and the separation of it is very
difficult even by other ion-exchange process as well as
general chemical treatment. Ho~ever, the organic phase A
extracts almost no tin ion~ in the condition range~ for
extracting indium ions of this invention.
As described above, the organic phase A of this
- 18 - i
~ ~ 4~ i2
invention alleviates positively the problems occuring in
case of the indlvidual u9e of A monoalkylphosphoric acid,
dialkylphosphoric acid~ or trialkylphosphoric acid
constituting the organic phase A, i. e., the organic phase
A extracts selectively lndium ions from an aqueous
901ution containing the indium ions together with, in
particular, ferric ions under the conditions defined in
this invention and make~ it possible to back-extract the
indium ions into an aqueou3 sulfuric acid solution.
The indium recovery process of this invention can
be easily applied to the practical operation without any
trouble in addition to the simplification of steps, and
hence the significance of the invention is large.
In addition, in the process of this invention,
an aqueou~ sulfuric acid-acidic solution can be used as the
back-extracting solution but a leached solution of an indium
raw material, i. e., a solution to be treated by the
extraction process of this invention is not limited to a
sulfuric acid-acidic solution but may be a sillcofluoric
acid solution, a hydrochloric acid qolution, a nitric acid
solution or other halogenic acid solution.
Now, the following examples will serve to illustrate
the process of this invention.
.
ExamDle 1
While changing the pH of an indium-containing
aqueous solution, the extraction test for indium ions was
-- 19 --
762
performed
An aqueous sul~uric acid solution having a pH
of 0.70 to -0~30 containing 0.457 g/liter of indium ions
was prepared. Al~o, an organic phase consisting of lO
parts by volume of D2EHP~, 40 parts by volume of TBP, and
40 parts by volume of kerosene was prepared. In a 150
milllliter separa1:ory funnel were placed 50 ml of the aqueous
solution prepared above and 50 ml of the organic phase, the
mixture was shaked for 5 minutes and then allowed to stand.
The ra~finate, i. e., an aqueous ~olution extracted of
the extraction re~t was separated, the indium concentration
in the raffinate was analyzed, and then the extractability
o~ indium ions in the organic phase was determined based on
the concentration of indium in the original aqueous solution
prepared. The results are shown in Table l.
:;
- 20 -
Table 1
, ", , ~
Extracta-
pH in aq. In concn. in In concn. in bility of In
soln. orig. aq. soln. raf~inate in org. phase
g/llter g/liter ~o
. . . _ _ . . . _ _ _
-7 o.457 o.oll 97.6
0.60 lt 0.014 96.g
0.52 ~ 0.020 95.6
o.46 l~ 0.023 95.o
o.40 " 0.029~ 93.5
0-35 " o.o40 91.2
0-30 " o.o40 91.2
0~12 ~' o.o50 89.1
o.oo ll o.o60 86.9
-O.lo " 0.155 66.1
-0.18 l~ 0.169 63.o
-0.24 " o.235 ~8.6
o 30 " 0,26~ 41.3
. . . ~
That is, the indium extractability obtained was
higher than 90% at the pH of the indium-containing aqueous
solution of higher than 0.30 and was 98/ at the pH of 0.~0.
Example 2
While changing the ratio of the organic phase to
the aqueous sulfuric acid solution containing indium ions
and zinc ions, the extraction test was performed.
An aqueous sulfuric acid solution having a pH of
0.60 containing 0. 457 g/liter of indium ions and 100 g/liter
- 21 ~
~4~7~i2
of zinc ions was prepared and also an organic pha~e having
the same composition as in Example 1 was prepared. While
ehanging the ratio o~ the organie phase to the aqueous
solution (~hown by 0/A)~ the extraetabilities of indium and
zlne ln the organic phase were measured by the same ways as
in Example 1. The results obtained are shown in Table 2.
Table 2
/A ratio Concn. in Concn. in Extracability
orig. aq. soln. raffinate in org. phase
_ __ er g/liter % -
In Zn_ In Zn In ¦ ~n _
0.25 0.457 100.0 0.043 100.09U ~ 0.0
0.50 tl l 0.034 100.092.6 0.0
0.75 ~ ~l 0.025 100.094.5 0.0
1.00_ . ,~ 0.020 100~095.5 0.0
That is, at the pH of o.6 the extractability of
indium wa~ increased a~ the amount of the organic phase
brought into contact with the aqueous solution in the range
of 1/4 to 1/1 was larger. The extractability for indium
ions was higher than 90% in each case but the extractability
of zinc was 0, which showed the excellent SepQrating property
of indium from zinc.
~ 2~ -
76;~:
Example ~
The back-extraction test of indium from the
organic phase containing indium wa9 performed by aqueous
~ulfuric acid solutlon for back-extraction while changing the
concentration of the aqueous solution.
An organic phase having the same composition a~
in Example l was prepared and the content of indium was
o.424 g/liter. Then, 100 ml of the organic phase were
vigorously mixed with 40 ml of a back-extracting solution
10 con~isting of an aqueous sulfuric acid solution in a
separatory funnel for 5 minutes. The results obtained on
the back-extractabilities of the organic phase to back-
extracting solution having different sulfuric acid
concentrations are shown in Table 3.
~ ' .
Concn. of_ Concn. of
sulfuric acid Concn. of In in
in back- In in org. extracted' Back-extrac-
extracting soln. phase soln. tability
g/liter g/liter g/liter o~
_ _ _
130 o.424 0.860 84.7
180 ll 0.874 94,2
210 1~ 1~022 96.2
240 ~ 1.040 96.3
270 ~l 1.02Z 96.2
300 " 1.072 lO0.0
33 ., 1.072 100.0
360 ll 1.072 100.0
. _ _
,
- 23 -
~L4~7~;2
That is, the back-extractability by one mixing
contact of both ~olution~ was higher than 90~o when the
eoncentration of ~ulfuric aeid wa~ higher than 180 g/llter
and became 100% when the concentration was over 300 g/liter.
Example 4
Back-extraction test was performed whi~e changing
the ~olume ratio (0/A) of a charged organic phase (0) to a
back-extracting sulfuric acid solution (A),
A back-extracting solution having a constant
sulfuric acid solution of 180 g/liter was used and the
composition of an organic phase was same as in Example 1
and the indium concentration in the org~anio phase was
0.444 g/liter. The ~tirring period of time for back-
extraction was 5 minutes. The results obtained are shown in
Table 4.
~ - ~
Table 4
0/A In concn. in In concn. in In concn. in Back
ratio loaded org. org. phase back-extracted extrac-
phase after back- qoln. tability
g/liter extn,
g/liter g/liter %
__ , ._ .. ... __ _ .
0.1 0.444 0.084 3.60 81.1
O.Z 1. 0.032 2.06 92.8
0.4 l l I o,0~3 1 1.08 1 97
,
'
- 24 -
~67~%
That is, lndium can be easily recovered with a
smaller amount of a back-extracting solution in a concentrated
state.
Example 5
Repeating test of a back-extraction was performed.
A back-extracting sulfuric acid solution having a
constant sulfuric acid concentration of 183 g/liter was
used and the mixing volume ratio 0/A in the back-extraction
was kept at a constant value of 10/1. A back-extractability
of indium from the loaded organic phase was measured when
the back-extraction was performed thrice.
Each back-extraction was performed fo~ 10 minutes.
The organic phase composed of 3 parts by volume of D2EHPA7
12 parts by volume of TBP, and 8$ parts by volume of MSB 210
- made by Shell Chemical Co. and loaded with 2.36 g/liter of
indium, The result~ are shown in Table 5.
~ ' i
Table ~
!
_ ___ . . . _ __ . -- _ . __ . . _ .... _ __ .. ~
Back~extraction
repeating no. 0 1 2 3
.
Concn. of In in back-
g/liter 0 l9.0 4.60 4.60
. ... ., __ l
phase g/liter 2.36 o.46 0.00 0.00
Integrated back-
extractability % 0 80.5 10.00 10.00
. . ..
- 25 -
~4~t7~2
That is, when the sulfuric acid concentration of
a back-extracting solution is low, a sufficient back-
extract could be practiced by repeating the back-extracting
operation.
Example 6
Indium, zinc and iron were di3solved in an aqueous
sulfuric acid solution together with dusts containing
fluorine~ chlorine, tin and ar~enic to provide an aqueous
solution having a sulfuric acid concentration of 9.36
g/liter (pH 0.72) and u9ing the organic phase of this invention,
a 3 stage counter current continuous extraction was performed
by means of a mixer settler. The organic phase used in the
back-extraction was composed of 3 parts by volume of D2EHPA,
12 part3 by volume of TBP, and 85 parts by volume of MSB 210
made by Shell Chemical Co. The extraction and back-extraction
were repeated several times.
The volume of the organic phase prepared wa~ 40 liter3
and while performing the continuous extraction, sampling was
performed when the extraction system reached equilibrium and
the 9ample9 were analyzed. The results are shown in Table 6.
-- ~6 ~
3 146'7~2
, __
p~ ~ ~ ~q IJ.
. -
, o~
'1
w ~ l-aq a~ w ~ 1- ~n
. ~ p ~ O
u~ ~ P
~t
~ m P~ ~ ~
o~ag aq ~3 aq aq ag
_
~,
W
~w
:~ ~.~ , ~ ~ .-
. ,
. W O
o ~o ~ ~ ~
o ~n W ~ O O O ~' ~. ~
O ~ ~ ~ O O W 1-~ W Ct~ H
O ~ ~ g W~ O~ p
1-~ OOOOO~
~ ~ ~ 1-- ~O ~D ~O O O ~ ~1 N
. ~ ~ n P~ ..
'O O O ,0 ,W,WW ,OW OD ~ ~ ..
~ ~ ~ O W ~~ O W l_~ ~
1~ 1~1--~ 0~ ~ O
.~ . ~ P
O O O O O O O O O ~_ . ~
CO OD Ot) O O O O O O .tl~
O O O O ~ W ~ O ~ ~nP
~0 ~ ~ ~ O ~ ~0
J O ~ ~ ~ O ~ ~
n O O O O O i~
W ~ ~ ~ C> O ~D
~- ~
O O O O O O O O O 7- .
~ 1~ ~ O ~ O i~ Y ~1
~ ~ ~n ~ W 8 ~ ~D
o o o o ~ ~ ~ o ~ W
O O O O h~ ~ ~ O ~ ~ P
o~ a~ o ~ I_ _ __
- 27 -
~:~4~762
That i8 ~ the extractability for iron wa9 about 10%
and tho~e ~or other elements were greatly low, while that
for indium was 100%. These results show the sufficient
~ep=rat~on e~fect by the ~nvention.
Example 7
An organic phase having the same compo~ition as
in Example 6 was loaded by indium and other elements ions
as in the ~ame example and then the back-extraction of
indium from the loaded organic phase was performed in
counter current 3 9tages by means of a mixer settler
using a sulfuric acid Rolution.
In addition, the concentratio~ of sulfuric acid in
the aqueous ~olution used in the back-extraction wa9 305.2
g/liter and the ratio 0/A in the back-extraction was 10.75.
; The results are shown in Table 7.
.
7~
. -- 28 --
,~, ~ td ~ b
. ~ p~a~ ~ ' p ~
W ~ ~, X ~ y. ~ o
~ 1 ~ ~1 P tn ~ p
P~ P~ - P~ P' ~ as
bO ~ tn to t~
~ ~ ~ ~u. O ~ O
p) ~ ~ O ~ P t~
a~ aq aq P uq ~q cq aq aq P P~
~D
_ . _ ~ _ - I
a
~ ~n a
~ N 1\~ P ~1
. ~
~ . _ _ ~D
~ 1
; ~~ '1 I
Wo :~ - - ~3
~n ~U~
10 ~0
~ O ~_
~ t\) , ~ ~ O 1-- H ..
'~ ~ ~- g o ~ ~ 'ol ~ \n ;l
~ ~ W O ~ O O O O P~
1\7 ~ 1_ . ~ P~
: , Oo ~o O O ~n ~ O ' ~ ~
1~) ~ 00 OQ ~ ~ ~) N
. W O O~ ) (D
GO ~ ~ O O O O O O ~
. ~ 0 0~ ~ O O C~ O : .
.' W ~ I' I' o ~ ~0 ~-
~ O O O O. O O ~
OD 00 00 O O O O O ~
~ ~o ~o ~ $ o o 8: g ~
W ,~ ~ o o o o o o
8 ''
o o ~ ~ o o o ~
~O ~n ~ O O O O O O
~o oo . . . . .
. . . o r~ o o
~ ~ ~O ~ ~ ~ 1V ~D
w ~ ~ o a~
o ~ ~ o o o o o o
o . . o , C:~ o o
'O ~n ~ g ~ P
,'
_
,
- 29 -
That is, the back-extractability for tin was low
R9 well as sufficient back-extractions were obtained on
other elements, ancl th~ recycling use of the organic phase
was sufficiently pos~ible. In addition, since the
extractability for tin from an original aqueous solution was
greatly low and the content thereof in the loaded organic
pha~e was also low, the existence of such a small amount of
tin gave substantially less problems.
