Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
6~76
Di~2-ethyl-hcxyl phosplloric acid i5 UsO(:I commercially as
a cationic oxchal1gcr in tho extraction of hcxaval(3nt uranium from sulrate
solutions~ in thc scparation of uranium and vanaclium, in tl--c scparatior
and purification of rarc earths, in thc separation of coba]t and nickcl,
in the extraction of beryllium from sul~ate solutions, in the separation
o-~ zinc, iron, manganese, and cobalt, in the extraction o~ zinc, and in
many other applications that are in the course of development.
In all these proc¢sses the fluids processed as aqueous feed
usually contain various ionic impurities, one of the most common being
iron. The affinity of di-2-ethyl-hexyl phosphoric acid for iron is so high
that even in very low concentrations it is extracted quantitatively forming a
complex that p~lymerizes in the organic phase, reaching molecular
polymerization weights of the order of 2,000. This phenomenon, in time,
produces a marked decrease o~ the load capacity oÇ the cationic exchanger
as well as a considerable increase in viscosity in the organic phase that
makes dif-ficult and even prevents its utilization as an extraction agent
in a very large number of possible applications
It is well known that there are two possible processes to eliminate
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iron from these organic phases
The first consists in washing it with a strong alka1ine solution of
hydroxide or sodium carl~onate. This treatment achieves thc rupture of
the
the polymer forming ferric hydroxide/sodium salt of di-2-ethyl-l1exyl
phosphorio acid. The presence of the precipitate of ferric hydroxide in the
aqueous sta~e and the high degree of disassociation of the sodium salt
frorrl the acid causes the carrying alony and the solubility of the di-2-ethyl-
hoxyl phosphoric acid to bo so high that thcy malce its application on an
industrial scale prohibitive economically speaking.
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~~ The second process consists in washing it with an
aqueous solution of 6M hydrochloric acid. This treatment also
achieves the rupture of the polymer by the formation of the
anionic complex from the ferric ion in a chloride medium, C~4Fe ,
that displaces the cationic exchange between the F ions of
the organic stage and the H ions of the aqueous stage. This
process is not very attractive from the economic point of view
because of the high consumption of acid necessary.
In this second process the consumption of hydrochloric acid
is determined by the balance existing between the two phases
during the treatment with respect to the ferric ion, which makes
it necessary to purify the acid aqueous solution when a given
concentration of iron is reached but which always represents an
insignificant fraction of the acid equivalents utilized so that
the consumption of acid normally represents from 10 to 20 times
the stochiometry of the iron.
The subject of the present invention is a proce~ss for the
elimination of iron accumulated in the organic stages that contain
di-2-ethyl-hexyl phosphoric acid by means of an acid aqueous
` 20 solution containing chloride ions and the subsequent treatment o-
the regeneration liquid in order, by means of the elimination of
the iron, to reuse it.
In one particular aspect the present invention provides
in a process for the removal of iron from an iron contaminated
cll-2-ethyl-he~yl phosphoric acid containing organic phase
of n Eluid-fluid extraction process, the steps of directly
con~acting said iron contaminated di-2-ethyl-hexyl phosphoric
nc:ld containing organic phase with a regeneration fluid
comprising an acidic aqueous solution containing chloride
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- ions to effect cationic exchange of ferric ions and yield a
: regenerated di-2-ethyl-hexyl phosphoric acid containing
: organic phase and an iron containing regeneration fluid
phase, contacting the iron containing regeneration fluid
phase with an anionic ion exchanger containing organic phase
to extract the iron from the iron containing regeneration
fluid phase, treating the anionic ion exchanger containing
organic phase containing extracted iron with water and
recovering iron in the form of a relatively concentrated
: 10 aqueous solution of ferric chloride.
. The process that is the subject of the present invention
therefore consists of three stages:
In the first stage the organic phase containing di-2-ethyl-
; hexyl phosphoric acid "poisoned" by iron is placed in contact ..
with an acid solution containing chloride ions in concentrations
, such as produce the exchange of ~1+ ions for ~e+ ions between
the aqueous phase and the organic phase, achieving the
"regeneration" of the organic phase.
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The sc~cond ';t;~CJC consists oE tlle oxtr~ction of tl,c iron c-~r~t.~ c~l
in the rccJeneration ~lui~l of tho proc~din~3 sta~e by mcans of its contact
with an or~anic solution containin~3 an anionic ion exchan~or in
such a way that the rc~eneration liquid i5 rcutilized in thc first st.l~3c
after the replacement of the stochiometric hydrochloric acid equivalcnt
to the iron eliminated.
The third stage consists of the re-extraction of the iron from
the organic phase containing the anionic exchanger proceeding from the
preeeding stage by means of its contaet with water, so that this or~anie
stage, free from ironJis reeycled for reutilization in the second stage.
In brief, the iron passes from the or~anic phase eontaining the
<li-2-ethyl-hexyl phosphoric acid to the wa~;er by means of two intermediate
vehieles: an acid solution of chloride ions and an organie solution of an
anionie exehan~er, the whole of the proeess which is the subject of this
invention produeing only the eonsumption of hydroehloric acid ecluivalent
to the iron eliminated and the quantityof water necessary to evacuate from
b the system the ferric ions eliminated.
In the first stage, or the regeneration stage, the reaction ~nechanism
is one of eationic exehange and in a simplified ~orm it may be represented
by the following equilibrium:
R Fe() 3Rt (aq) ~ ~ICl ~ (aq) ~ 3 RH(o) ~C14Fe (aq)
RH bein~ the di-2-ethyl-hexyl phosphorie aeid Thus, in prineiple, the
re~eneration reagent may be any mixture of an inorganie mineral aeid and
a sol~lblo choride, hydrochloric aeid bein~ preferable from the practical
point o-f vi~w, alone or mixed Wit}l sodium chloride or calcium ehloridc,
nnd sulfurie :Irid with -odium rhloride
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~8G(~76
The optimum conccntr~tions of thcse roagcnts in tho rcgcllcr~ g
liquid obviously dcpcnd c n the concentration of di-2-cthyl-hcxyl pllosphoric
- ;~cid in the organic pl-aso and on the lcvcl of rcsidual iron that is sc ugllt
in the applic~tion in question.
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For a concentration that is widcly util ized of 10% v/v
; in kerosene, the optimum environment of concentration of hydrochloric
acid in the regenerating liquid is found between 4 and 6 molar.
,~ The regeneration of the di-2-ethyl-hexyl phosphoric acid may be
carried out in any extraction equipment with solvents and preferably in
sedimentator_mixers. This type of apparatus is that which was used in
'. our tests continuously.
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The time required for agitation or contact n order to attain the
equilibrium depends on the concentrations in the organic and aqueous phases
~` and on the degre.e of agitation, In any case it waS less than 10 minutes,
values of less than 3 minutes predominating.
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The separation of phases does not offer any difficulty.
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In a single contact between the re~enerating reagent in the form
of hydrochloric acid 5.5 M and the organic phase with di-2-ethyl-hexyl
~,- , phosphoric acid 10% v/v, with appropriate regulation of the ~'atio of
the flows of both, the elimination of the latter was achieved plus 90~o of
tho iron, an organic phase resulting that contains iron in quantities of
less than 150 mg/l,
l` The temperature compatible with the process varies betwocn 10
`h and 50 C.
The concontrations of D2EHPA in the organic phasc may vary
- between 1% and 50% v/v.
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~86~76 5
Tllo conccntrat;ons of clllori~le ion in the rcgoncr~lting r~{lgcnt
may vary froln 0~1 to 12 M, tho bost results being obtainccl in tho
erlvironmcnt of ~ 0 to 6 0 M.
Another aim of the process of the present invcntion is thc
elimination of iron from thc aqueous reagent used in thc re~cneration of
the di-2-ethyl-llexyl phosphoric acid for the purpose of utilizing it again.
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In order to extract the iron in the second cycle, an organic phase
is employed constituted by three components: an extraction agent, a
modifi er and a diluting agent.
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The extraction agent belongs to the amino groups, and may be
primary, secondary, or tertiary, or on a basis of quaternary ammonium
with long alkylic chains, only slightly soluble in water and with a molecular
weight superior to ~00
The second component of the organic phase - modifier - has the
purpose of facilitating the separation of phases during extraction. Alcchols
of from 8 to 14 carbons give the desired results.
The third component or the diluting agent serves as the carrier
of the other two reagents and causcs the viscosity of the medium to
decrease A hydrocarbon may be used or mixtures of hydrocarbons such
a5 those obtained in the fractionating process in the distillation of petroleum.
`:~ The fixing of the iron on the extraction agent is ba5ed on the ~act
that this element forms in solutions of ehloride ion the ehlorinized comple x
o~ an anionie nature, Cl~Fe, in aeeordance with the equilibrium:
~ICl ~ Fe3~ Cl Fe~
The extraetion of the iron i5 earried out by an ionie exchange
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mcchallismJ bctwccn thc cl-loriclo oF th¢ aminatcd compouncl ancl tl)c ion
complex of the iron. For thc case oF secondary aminc chloride,
(R2H2NCl), the equilibrium may bc reprcserlted by the following eq~lation:
R2NH2Cl ~ C14Fe , > R2NH2Clq.Fe ~ Cl .. .
. ..
The displacement oF this reaction towards the right - the direction
of extraction _ to the extent that it is made by the conccntrations of Fe ~
and Cl , on all the latter~ which intervenes in the constant of formation of
the anionic complex of the iron.
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The extraction of iron may be carried out in any extraction equipment
with solvents, preferably in sedimentator-mixers
This type of apparatus is that which has been used continuously in
our tests.
The time required for agitation or contact in order to attain
equilibrium depends on the concentrations in the organic and aqueous phases
and on the degree of agitation. In any case it was lèss than 10 minutes,
values of from between 2 and 5 minutes being predominant.
YVhen there is a modifier in the organic phase the separation of
phases does not present any difficulty.
In a sin~le contact between the organic phase containing the aminc
c~nd the regenerating reagent, appropriately regulating the ratio of the
llow of both, an climination was achieved of more than 95% oF the iron From
tho latter, an aclueous cxtract resulted with a concentration of iron inFerior
to ~0 mg/l
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Thc tcmpcraturc compatil)lc witll thc proccss varics bctwccn
10 and 50 C.
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- Thc concentrations of amine in the organic phasc may vary l~twecn
1,and 50%, and thc concentration of aliphatic alcohol fr~m 0 to 25%
depending on the concentration of iron and chlorides in thc regenerating
reagent
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- The re-extraction of iron from the organic phase that contains
the amine is carried out with waterJ being based on the disassociation of
the anionic complex of iron ~14Fe in the absence of chloride ions.
Depending on the !ratios of the flows of the organic phase and water,
more or less concentrated solutions of ferric chloride may be obtained
as well as a greater or less discharge of the organic phase.
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After re-extraction, the organic phase is practically free of iron,
SO that it is re-utilized in the process.
Losses of regenerating reagent (hydrochloric acid) using this method
are reduced to the stochiometric consumption corresponcling to the iron plus
the small amount of purifying necessary to maintain the balance of ~;ater in
the system,
This method may also be used for regenerating the di-2-ethyl-hexyl
phosphoric acid of other ions that form anionic complexes in chloride
cnvironments such as: chrome, aluminium, etc.
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The invention is illustrated by means Or a number of exarnples
that are not limitative, and in order to facilitate the interpretation a drawingi~ is also attached.
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8~i~76;
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Ex~lrnr>l~ N 1
An illustrative examplo is given bclow, which is not limitative, of thc
rcgcncration of the D2E~IPA. An organic pllase is establislled whose eom,oosition
is the following:
D2EHPA : 10% v/v
Petroleum (CAMPSA) : 90% v/v
This organic phase ;s charged with iron to a concentration of 0. 338 g/l . In what
follo~Ars the above~mentioned organic phase is subjected to a contact, in a single
stage, with a solution of hydrochloric acid 5.9M. The ratio . of the flot~s in
those
the organic phase to/ Of aqueous phase was 10.
The results were the following:
- Iron in the organic phase : 0.110 g/l
- Iron in the aqueous phase : 2.19 g/l
Example N 2
A new demonstrative and non limitative example is given in what follows
.. in whieh all the coneentrations of the regenerating reagent that have been
enumerated may be used to regenerate the D2EHPA.
The organie phase has a eomposition the same as that utilized in
example N 1.
The eoneentrations of iron in the organie phase, the eoncentrations of
re~eneratin~ reagent and th6~: ratio . of the flows in the or~anic phase to those of
aqueous phase are tho following:
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Tcst ~rganic phasc r:egcnor;lt;ng solution Ral;io Or f]ows
qFc/l Cl~ M/lorclonic/~q-leous
1 0. 240 s . 0 30
2 0, 240 5 . 0 20
3 0 . 338 5, 0 10
0~338 5.0 5
0.2~0 ~.0 5
6 0.338 3,9 S
7 0, 338 3 . 0 10
Both phases were subjected to a contact in a single sta~e,
the following results being produced:
Test Organic resultantAqueous resu.ltent
gFe/l qFe/l
0. 110 3.57
2 0,090 2.60
3 0, 055 2 . 45
0. 068 1 . 37
0.120 ~,23
6 0 . 063 1 . 34
7 0. 190 1.48
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Ex~mple N 3
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Another demonstrative and non-l;mitative example is given
below in which all the compositions of the regenerating reagent enumerated
:l` may be used in order to regenerate the D2EHPA.
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'-' ' Th¢ organ;c phase has a cornposition the same as that utilized
in tho preceding examples.
Tho concentrations of iron in the organic phase, the cornposition
of the rcgen~ratin~ solution and the ratio of flows in the organic phase to
those o~ the aqucous pllase are thc following:
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~i~ Rc~cncrant solution
Tcst Or~1anic pln~s~ I</l Ratio of flows
~FC/I CIH ClMa SO~H2 Or(~anic/aqucous
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1 O. 338 5.0 1.0 ~ 10
2 0.338 ~.0 1.1 ~ 15
3 0.240 ~.0 1.1 ~ 20
4 0.338 2.9 2.2 - 10
0.338 2.0 3.3 _ 1n
6 0.338 2.0 2.0 2.0 10
Both phases were sub~ected to a contact in a single stage,
the following results being produced:
Test Organic resultant Aqueous resultant
__ ~Fe/l _ ~Fe/l _
1 ' O. 098 2, 3~
2 O. 115 3.~0
3 0.095 2.70
~ , 0.115 2.2
O, 165 1.6~
6 0,123 2,13
Example N 4
A non~limitative illustrative example is given below of the
elimination of iron from the liquid for regeneration of D2EHPA. The
composition of the organic phase is the following:
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~' Amberlite - LA-2 (commercial secondary amine) 15%
Isodecanol ........... ,.,.. ,,.. ,... ~........... 6%
, Petroleum C~PSA) ... , 79%
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~; The above-mcntioned organic phase was then subjected t,o a
!''`~ contact, in a sin~le sta~e, with the regenereration effluent from thcD2EHPA.
'' The organic stage char~ed with iron was re-extracted with water in one
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The concentrati~ns of iron in the effluent fram the regeneration
and the ratio of flows in ~he organic phase to those in the aqueous phase
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in extraction an~ re-extraction are the following:
Regenerant solution Ratio of flows Ratio of flows
Test gFe/l extraction re-extraction
crgam c/aqueous organic/aqueous
1 3.24 1.80 7O20
2 3.04 0~67 3.23
3 3.20 1.25 5.59
4 3.48 2.54 10.06
2.6g 1.98 10.23
6 2.97 2.50 17.12
The results were the ~ollowingO
Test Aqueous ex~ract. Organic extract. Aqeuous re-extract. Orangic ~e-extract
_gFe/l ~Fe/l gFe/l ~Fe~l
, 1 0.20 1.81 12.20 0,12
2 0.63 3.77 11.60 0.18
3 0.43 2.79 12.40 0.58
4 0.20 1,47 13.00 0.18
; 5 0.08 2.54 13.50 1,22
6 0.27 2,53 18.50 1.~5
Exampi~ NQ 5
This exa~ple sums up the results of the regeneration o DZEHPA
~; and o the elimination of iron rom the effluent from regeneration, carried
out continuously on the scale oE a pilot study, The stages of the process
ar2 identified with Roman numerals and the main flows are identified in the
Figure wi-th arabic numerals.
In these tests the prooess consists of the follow1ng s~ages:
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Rc~cneration o~ D2EI-IPA
Extraction witll LA-2 II
. Re-extr~ction with w~t~r III
An organic extract was available proceeding from a previous
extraction stage. The or~anic extract had the followinc~ composition:
Iron 0 . 29 g/l
Zinc 0 . 26 g/l
ClH Acids < 0.5 g/l
The regeneration reagent utilized was a solution of hydrochloric
acid with a concentration of 4.9 M/l.
;~ A summary is given below of the flows and compositions of th;~
- ~- main flows of the process, which flows are detailed on the sheet of drawings
attached to this memorandum.
- N" Flow . . . Flow Composition in g/l
Identlflcatlon ,, . ~ f~ll l
Figure m~ n ~e ~.n
:~: 1 Organic feed (D2EHPA) 1119 0.29 0.26 0.5
' 2 Or~anic extract1119 0.08 0.013 0.5
3 Regenerant solution 114 0.014 1.70 161.0
4 Regeneration effluent 114 2.00 3.40 161.0
.`. l 5 Re-extracted org~nic
-~ . phase (LA-2) 224 0.0~0 1.20
.: 6 Charged organic phase 224 1.10 2.20
7 Rc-extraction water 46
;~/; ' 8 Aqueous extract 46 5.50 4.20 4.00
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