CA1179145A - Process for selective liquid-liquid extraction of germanium - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A process for selective liquid-liquid extraction of germanium from an aqueous acidic liquor containing, be-sides germanium, at least one other metal selected from the group which comprises cadmium, zinc, cobalt, iron, ar-senic and nickel. This process includes extracting germa-nium from said aqueous liquor by contacting said liquor with an organic medium containing a diluent and an extrac-tant, said diluent being immiscible with said aqueous li-quor. The major part of germanium passes from said aqueous liquor to an organic phase which is subsequently submitted to a stripping step by contacting with an alkaline medium, with formation of an aqueous phase containing the major part of germanium from said aqueous liquor.

Description

FIELD OF THE INVENTION
The invention relates to extraction of metals from aqueous acidic 1iquors, and more particularly to a process for selective extraction of germanium from aqueous acidic liquors containing also at least one metal selected from the group which comprises cadmium, zinc, cobalt, iron, arsenic, aluminum, gallium and nickel.
BACKGROU_D OF THE INVENTION
The separation of germanium from acidic leach liquors has attracted great attention because of its eco-nomic implication, especially in zinc production. The electrolysis of zinc can be achieved with a good yield on-ly when germanium has been completely eliminated from the electrolyte. This separation is therefore a preliminary operation to the recovery of zinc metal from solutions.
Moreover, the recovery of germamium from such solutions constitutes the main available source of this metal, ap-plications of which are essential in many areas such as electronics, infrared optics, fiber optics, ionized par-ticles detection and polymer chemistry.
The leaching treatment of minerals is performed with sulphuric acid for economic reasons and leads to li-quors containing chiefly zinc sulphate (about 100 9/1), germanium (IV) (0,1-1 g/l ) and other elements such as cad-mium, magnesium, etc. As these metals do not interfere with the electrolysis of zinc or are easily removed, a se-lective separation of germanium from the acid liquor would be advantageous for isolation of this metal.
PRIOR ART
Conventional processes for separating germanium from acidic leach liquors ~precipitation with tannin, dis-tillation of GeCl4, etc.) are very complicated. Conse-quently, liquid-liquid extraction and resin separation me-thods appear to be attractive and have been widely stu-died. Various solvents such as carbon tetrachloride, chlo-roForm and tributylphosphate, and extractants such as long chain amines, alkylphosphoric acids, phosphinic acids, oxine, hydroxamic acids and alkylpyrocatechol as well as , many resins have been proposed. However, the low capacity of most resins and extractants, their prohibitive costs and the strict separation conditions they sometimes impo-se, have often limited their application. The d-hydr mine coumpounds, recently introduced~ appeared until re cently to be the most suitable reagents from the prepara-tive solvent extraction of germanium. Their application for industrial germanium recovery have been studied and pilot plant experiences have been carried out, as descri-bed by De Schepper, A. Hydrometallurgy, 1 (1976) 291.
Though they are very interesting, these compounds still require severe conditions (e.g. very high acidity of the aqueous solution and high extractant concentration) to be efficient.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a process for selective liquid-liquid extraction of germa-nium from aqueous acidic liquors containing at least an ~other metal selected from the group which comprises cad-mium, zinc, cobalt, iron, arsenic, aluminum, gallium and nickel.
Another object of this invention is to provide a process for selective extraction of germanium from aqueous acidic leach liquors containing zinc metal.
Another object of this invention is the selecti-ve extraction of germanium ~rom such a liquor by contac-ting said liquor with an organic medium containing a par-ticular extractant. Said organic medium may be a station-nary phase.
It is another object of this invention to provi-de such a process for extraction of germanium from such liquors with a yield of about 100 %.
It is another object of this invention to provi-de a process for selective extraction of germanium from such liquors requiring only very short time for contacting said liquors with an organic medium.
It is another object of this invention to provi-de a process for extraction of germanium from such liquors ~ 7~3~

by treating said liquors about at ambient temperature.
It is another object of this invention to sepa-rate germanium from aqueous liquors containing zinc by a low cost process.
SUMMAR~ OF THE INVENTION
According to the invention, a process for selec-tive extraction of germanium from an aquevus acidic liquor containing, besides germanium, at least one other metal selected from the group comprising cadmium, zinc, cobalt, iron9 arsenic, aluminium, ~allium and nickel, inclu~es:
- extracting germdnium from said aqueous liquor by contacting said liquor with an organic medium which contains a diluent and an extractant, said diluent being immiscible with said aqueous liquor, said extractant being selected from the oxine (8-hydroxy-quinoline) derivatives having a long hydrocarbon chain, said contacting step for-ming an aqueous phase containing the major part of said at least one other metal, and an organic phase containing the major part of germanium from said aqueous liquor, and ~ stripping germanium from said organic phase by contacting said phase with an aqueous medium, said strip-ping step forming an aqueous phase c:ontaining the major part of germanium from aqueous liquor and an organic phase containing said diluent and said exl:ractant.
According to the invention, the long hydrocarbon chain of said extractant includes at least eight carbon atoms, preferably up to sixteen carbon atoms, and has ad-vantageously at least onc ethylenical insaturation. Prefe-rably, said extractant is ~-dodecenyl 8-hydroxyquinoline, but other positions of said chain are in the scope of the invention.
The pH of said aqueous acidic liquor is advanta-geously lower than 2, preferably lower than 0,5. If said aqueous liquor is nat sufficiently acidic, said liquor is preferably acidified, by example by addition of sulphuric acidO Said diluent is preferably selected in the group comprising pure and mixed aliphatic compounds and petro-leum fractions and such compounds and fractions mixed with -7~ 5 a minor proportion (5 to 20 % v/v) of a polar liposoluble compound such as an alcohol or a phenol having preferably 5 to 15 carbon atoms, trialkyl phosphate (e.g. T.B.P.) and the case being the tensioactive sulfonate from 8 to 30 carbon atoms 9 by example n-octanol.
Said aqueous medium used in the stripping step is preferably an alkaline medium such that the pH is grea-ter than 10.
Said aqueous medium may be also diluted hydro-fluoric acid (1 to 10 % ~IF W/W) preferably 2 to 5 ~.
During the extracting step, the temperature is preferably ambient or lower, but it does not mind if the temperature reaches 80C, and, during the stripping step, the temperature is preferably ambient or greater.
The concentration of extractant in organic me-dium used in extracting step is preferably such that there are at least 4 moles of extractant for 1 mole of germanium from said aqueous acidic liquor.
Said diluent may be a resin wherein the extrac-tant either alone or with other diluents is present in the form of a gel or the like thus forming a stationnary pha-se.
Other objects and features of this invention will be apparent in the following description and claims in which the principles of the invention are set forth to-gether with details directed to those skilled in the art to enable them to practice the invention, all in connec-tion with the best mode presently comtemplated.
BRIEF D~SCRIPTIGN OF DRAWING
In the drawings :
- figure 1 is a graph illustrating the variation of germanium extracted from acidic leach liquors, accor-ding to acidity of medium , - figure ~ is a graph illustrating the influence of the temperature on the stripping in a process according to the invention ; and - figure 3 is a diagram illustrating the main steps of a process according to the invention.

A process according to the invention includes essentially two main steps, an extracting one and a strip-ping one.
The extracting step includes extracting germa-nium from said aqueous liquor by contacting said liquor with an organic medium which contains a diluent and an ex-tractant. The stripping step includes stripping germanium from an organic phase formed during said extraction step, by contacting with an alkaline medium.
However, said process may include other steps.
By example, if said aqueous acidic liquor is not suffi-ciently acidic, it is preferable to acidify said liquor, by example by addition of sulphuric acid. However, other mineral non complexing acids well known by those skilled in the art may be used. Sulphuric acid is preferable, es pecially because it is very cheap and easily available, but it possesses also some advantages indicated in the following, and specially the fact that some sulphate or hydrogeno-sulphate ion is helpfull for extraction.
Moreover, between extracting and stripping steps, said process includes preferably at least one scrubbing step in which the organic phase formed during said extracting step is contacted with water which removes the greatest part of the small remaining part of said other metals, by example zinc. Such a scrubbing step remo-ves at least partly the small proportion of H+ which may be remaining in said organic phase. It has also been sur-prinsingly observed that such a scrubbing step provides for purification of said organic phase.
The scrubbing medium is preferably water if vo-lumes are not too important, said water being acidified by H+ (H2S04) removed during said step, or a sulphuric acid solution having a concentration between 0,1 and 0,5 N, preferably about 0,2 N. If a good impurity removing is de-sired it is possible to use higher sulfuric acid concen tration up to 2 N.
Moreover, after the stripping step, said aqueous phase may be treated for the recovery of germanium metal ~75~

or of other useful products.
One of the main features of the invention is theused extractant which is selected from the oxine derivati-ves having a long hydrocarbon chain. Preferably, said long chain includes at least 8 and up to 16 carbon atoms. It has advantageously by not necessarily at least one ethyle-nical insaturation.
Preferably, the extractant comprises a compound of the formula CH2-~ CH - CH
~ \N~
OH
wherein R is alkyl having 5 to 18 carbon atoms, the total carbon atoms in R being at least sufficient to ensure that the germanium chelate of said compound is soluble in hy-drocarbon.
A compound very useful is 7-~3-(5,5,7,7-tetra-methyl-1-octenyl)~ -8-hydroxyquinone, a ~-alkenyl derivati-ve of 8-hydroxyquinoline which has the structure :
~H3 C~H3 CH3 - C- CH3 ~ C - CH3-- CH
CH3 CH3 6H ~ ~/ ~N
, CH3 OH
Said compound is made by reacting 8-hydroxyqui-noline ~sodium salt) with dodecenyl chloride and distil-ling the resulting alkenyl ether, after pouring into wa-ter, separating and washing, the dodecenyl chloride being 1-chloro-5,5,7,7-tetramethyl-2-octene.
Other compounds very useful are 7- C3-(5,5 dime~
thyl-1-hexenyl ~ -8-hydroxyquinoline and 7-1-(5,5,7,7-te-tramethyl-2-octenyl)~ -8-hydroxyquinoline.
Such compounds and their preparation are descri-bed in U.S. Patent N 3,637,711 to W.M. BUDDE and al. and in Australian Patent N 57,173/69 to ASHLAND OIL INC.
A preferable extractant is ~-dodecenyl 8-hydro-xyquinoline having the formula -;

7~

CgHlg CH
CH OH

The following description relates essentia1ly to detailled data where the said particular extractant, which is called " oxH extractant" is given as example. It is commercially available as KELEX 100 from SCHEREX.
The influence of the acidity on the extracting step is now considered. Figure 1 presents the percentage of extracted germanium obtained for different acidities.
The results of figure 1 are obtained during an extracting step in kerosene + 10 % of octanol with different concen-trations of ~oxH. Curves a, b, c and d are respectively for concentration of ~oxH of 2,2.10-2 M, 3,1.1~-2 M, 8,6.10-2 M and 0,42 M. The concentration of germanium (IV) was 1,4.10-2 M. The pH was obtained by addition of H2S04, or by partial neutralization of H2S04 by NaOH.
The examination of figure 1 reveals that the ex-traction of the germanium (IV) is not uniform insides all the range of pH. In particular, extraction is the most ef-ficient at high acidity (p~l~ 1), though a slight decrease appears for sulphuric acid concentration higher than 2 M
(curves a and b). At weak ac~dity and in neutral media (pH
from 2 to 8), the extraction is f~r less e-Fficient but it becomes independent from the pH (the pH has no influence on the extraction ratio and remains itself constant during the extract;on)~ No extraction is observed from alkaline solutions (pH ~ 12) at any concentration of~ oxH. So, the domain of acidity can be divided in three parts correspon-ding to high, low and non-extraction. For the invention, the only interesting part is the high extraction one, that is for pH under 2.
The maxima oF curves a and b also show that the molar amount of extracted germanium is not far from a quarter of the molar amount of~ oxH present. So, to obtain the extraction of substantially all germanium, the molar amount of~ oxH extractant shall be at least four times the molar concentration of germanium. In practically opera-~'7~

tions, it is preferable for the molar amount of oxH ex-tractant to be at least 5 to 10 times that of germanium.
In these conditions, figure 1 shows that 100 %
o~ germanium may be extracted according to the invention.
However, the total extracked amount is not the only inte-resting parameter because, commercially, the rate of the reaction has a considerable importance.
The rate of extraction depends on the extractant concentration and on the germanium concentration. To de-termine the total rate of extraction, tests have been run with the same concentrations of~ oxH extractant on the one part and of Ge (IV) on the other part, but for different pH. The ~ oxH extractant concentration was 200 g/l, and that of Ge (IV) was 1,0 9/1. In a first run, the pH was very acidic, because the medium contained H2S04 0,5 M, and in a second run, the pH was equal to 4. In the first test (with commercial Kelex and 20 ~ of octanol~, more than 50 7O of germanium was extracted after 2 minutes only and, in the second run, a time of more than 20 minutes was ne-cessary for extraction of 50 % of germanium. (Kelex puri-fied by distillation gives a slower reaction rate).
These experiments show that the rather highly acidic media necessary to a high extraction percentage are also necessary for great rates of extraction.
So, the extracting step of the process according to th~ invention is very rapid and about quantitative, be-cause susbstantially all germanium is extracted very quickly.
The particular acid used in the extracting step is a non-complexing one, by example sulphuric acid and ni-tric acid. Halohydric acids and strong oxydant acids are not suitable. So, nitric acid is suitable only at a con-centration at which it does not oxidize reactants (e.g.
extractant). Sulphuric acid may be used at level of 25 up to 42Bé at least.
Figure 1 shows also that, for concentrations of oxH equal to 2,2.10-2 (a), 3,1.10-2 (b), 8,6.10-2 (c) and 4,2.10-1 M (d), germanium is re-extracted when acidity in-~ l - 9 - ~`v~

creases from H2S04 2M to H2S04 4M. However, such re-ex-traction is limited and the stripping step uses preferably an alkaline mediumn The influence of the concentration of ~ oxH ex-tractant is now considered. It has been above mentionned that a minimum amount of extractant was necessery for the extraction of substantially all germanium, said amount being at least 4 times and preferably at least 5 to 10 times more~ However, when the concentration of poxH is in creased, the rate of extract10n is also increased. That is a very trivial result which is well known by those skilled in the art.
A great advantage of the invention is to be em-phasi~ed relating to said extractant concentration. Said extractant is an expensive product, but its concentration is low , so, the physical losses of organic medium corres-pond to small losses of extractant. By contrast, in pro-cesses using such extractants as LIX 63*(from General Mills Inc.) which are present at very high concentrations, extractant losses are very important and costly~
The influence of diluent is now considered. In order to lnvestigate the role of diluent on the extraction of germanium in the organic phase, experiments were per-formed at two different acidities of the aqueous phase :
on the one hand at H2S04 1,5M, and on ~he other hand at pH = 5 ~ 0,5. In- all test runs, the contact ti~e of the two phases was long enough to ensure the attainment of equilibrium. The concentrations of~ oxH used were 15 9/1 and 40 9/1, giving accurately measurable values of the ex-traction lneither too high nor too low).
The used diluents were kerosene with 10 % v/v of octanol, n-octanol, a petroleum fraction containing mainly aliphatic molecules (Escaid 100~ and a petroleum fraction-con~aining mainly aromatic molec~les (Solvesso 150~.
The examination of the results showed a signifi-cant variation of extraction when one di1uent was replaced by another. The hierarchy among the diluents was not the same for the two different acidities. At pH 5, n-octanol * .Trademark s 7~

was the most efficient. However, at low pH (that is in the conditions used according to the invention), the best di-luent was kerosene with 10 % v/v of octanol, which is slightly more favourable than the petroleum fraction con-tdi ning main1y aliphatic molecules (Escaid 100).
The diluent contained a minor proportion of n-alcanol (10 ~ v/v) essentially because such addition pre-vents the formation of a third phase during the liquid-li-quid extraction. However, such addition of n-alcanol ha-ving 5 to 12 carbon atoms, and more generally of a polar lipophilic dissolving agent, has an other effect on reac-tions. In fact, such addition changes interfacial tension between aqueous and organic phases and speeds extraction which progresses essentially at the interface (as indica-ted by the distribution coefficient of~ oxH between aqueous and organic phases, said coefficient being about 107).
Experiments show that the rate of extraction is slightly slowed when the temperature is increased. So, am-bient or lower temperature is preferable for the extrac-ting step.
An important aspect for commercial application is the selectivity of the separation. Litterature data show that the extraction of germanium (IV) by ~oxH extrac-tant can be selective towards cadrnium, zinc, cobalt and nickel, but poorly selective towards copper and iron. A
quantitative evaluation of such selectivity is indicated in the following e~ample.
An extraction step ha~ been effectued with Kelex 100 at 10 % in kerosene with 10 % of octanol~ at ambient temperàture, with a ratio organic/aqueous of 1. The ini-tial aqueous solution A and the aqueous phases after a first and a second extraction B and C respectively had the following concentrations in grams per liter :

- - - -- - - - -H+ Ge In Fe Cu Zn As ¦ A ¦ 3,08 ~ 0,32 ¦ 1,8 ¦ 0,93 ¦ 48 ¦ 11 ¦
¦ B ¦ 2,72 ~ 0,05 ¦ 0,32 ¦ 1,8 ¦ 0,895 ~ 45 ¦ 11 1 C 1 2,30 1 1 0,32 1 1,8 1 09963 1 50 1 1 Such results show the excellent selectivity of the extracting step, even against iron. To obtain such se-lectivity it is necessary to be in sulphate medium (at least 1 M) allowing the formation of the assumed complex of Ge (pox) 3HS04.
The stripping step of the process according to the inve~tion is now considered. During such step, said organic phase formed during the extraction step, is con-tacted with an alkaline medium, said stripping step for-ming an aqueous phase containing the major part of germa-nium From said aqueous liquor3 and an organic phase con-taining said diluent and extractant so recovered are re-cycled to the first extracting step.
The influence o-f the alkalinity on the stripping step is now considered.
Effect of the nydroxide ion concentration on the stripping of said organic phase extracted at the acidities of the industrial leaching baths is complex. When the or-ganic phase is contacted with an alkaline aqueous solu-tion, the overall stripping reaction forms the free ~oxH
extractant in at least two steps. Firstly, OH- anions are extracted from the aqueous solution into the organic phase where they react to produce a dark red coloured compound.
The coloration appears a few seconds after both phases ha-ve been brought into contact and increases in about one minute after that. Secondly, the dark colour disappears s10wly by decomposition and germanium (IV) is stripped. In the first step9 the higher the hydroxide ion concentration and the slower the reaction is. During the second step, the process is reversed.
Experiments show that a high pH is preferable ~ 3 - 12 ..

and the aqueous alkaline solution is preferably a NaOH so-lution because NaOH is a strong alkaline medium, cheap and easily available. The pH of said alkaline medium is prefe-rably greater than 10 and said alkaline medium is prefera-bly NaOH 1 to 3,0 M. pH between 13 and 14,7 are especial-ly advantageous.
Alkaline solutions other than NaOH also re-ex-tract germanium during the stripping steps. Good results are obtained with NH40H 3N and Na2C03 3N.
The influence of the temperature on the strip-p;ng of germanium is now considered, referring to figure

2. Figure 2 shows curves representing variations of per-centage of stripped germanium according to time. The ini-tial germanium concentration was 9,5.10-3 M and that of ~oxH extractant 5jO.10-2 M. The alkaline medium was an aqueous solution of sodium hydroxide 1,2 M. Curves a, b, c, d, e and f are for temperatures of 25C, 30C, 40~C, 50C, 60C and 70C respectivelly. Figure 2 shows that the temperature has a great influence on the stripping step.
So, it is preferable for the stripping step to be used at a temperature of at least 40C. Such temperature may be easily obtained with waste heat. However, such heating in-i creases the temperature of the organic phase which may be cooled before use for the extracting step.
When temperature is at least 40C, it is highlypreferable to shake the stripping medium, because the reaction rate is then h;gh enough to be greater to that allowed by the limited interface of the two quiet phases.
The nearly complète and easy re-extraction of germanium with alkaline solution, as NaOH 3 N, according to the invention, is a great advantage. Experiments with solutions containing 3, 5, 7, 5 and 10 70 of Kelex in kero-sene with 10 70 of octanol regularly give re-extraction ra-- tios greater than 99 %.
A continuous experiment during a long period (102 h at 70-80C) in a closed loop pilot plant showed no degradation of Kelex and very small losses of such extrac-tant.

.

~ ~'7~ ~ ~ 5 One of the preferred and most surprinzing embo-diement will be described hereafter. Surprinzingly, it had been found during the studies which issued into the pre-sent patent application that the compounds called extrac-tants and defined above can be used as stationnary phases when adsorbed in the form of a gel or the like into re-sins.
The extraction by resins dif~ers from the one by liquid-liquid extraction on the followings points :
- The best pH range of extraction is O to 2 and preferably 0,5 to 1,5 (it is to be noted that less acidity is needed than in the case of liquid-liquid extraction).
- The rate of extraction is far higher even without agitation.
- The distribution of ~oxH between organic phase and aqueous phase is far better when organic phase is resin, about 10 times, and consequently the concentration of Kelex in aqueous phase is lower, e.g. for 10 % of ~oxH
in the organic phase respectively for liquid phase and for resin the value are at pH 1 10-4 and 10-5, at p~l 7 10-6,5 and 10-7,5 and at pH 13 10-6,2 and 10-6,8.
- lhe influence of polar liposoluble compounds is the same as in the liquid liquid extraction but it is possible to reach a higher proportion of said compound up to 50 % instead of up 20 ~.
The resins used were, on the one hand, the resins produced by the method described by Bayer in his patent and provided by it and, on the other hand, the resins procuded by adsorption on an inert resin skeleton.
The latter method is known per se and is reminded in the example 6.
It has been found that without agitation it was possible to extract and to stripp in the same way as des-cribed for the liquid-liquid extraction the germanium pre-sent in the sulphate solution. The elution by hydrochloric acid (4 to 12 N, preferably 6 to 10 N) in the case of the resins is possible as shown in the examples.
The behaviour of extractant according to the in-7~

vention presents great differences with that of 8-hydroxy-quinoline, called "oxine". The applications of oxine in liquid-liquid extraction are limited because of its high solubility in acidic and alkaline aqueous solutions. By contrast, extractants according to the invention have hy-drophobic substituents which replace one or more hydrogen atoms of the molecule. Such extractants have low solubili-ty in acidic and alkaline aqueous solutions and give high distribution coefficients. The ~-dodecenyl 8-hydroxyqu;no-line (~oxH) is an interesting oxine derivative because, among other interesting derivatives according to the in-vention, it is commercially available as Kelex lOO from SCHEREX. The 7-2-ethyl-hexyl-hydroxyquinoleine, available as Kelex 108 from SCHEREX, and the 7 undecyl-hydroxy-8-quinolines, behave as poxH.

Figure 3 is a diagram illustrating the main steps of a process according to the invention. The leach liquor contains essentially Zn t33 g/l) and H2S04 (150 g/l) and a small amount of germanium (1,22 g/l). Said leach liquor 10 is contacted with an organic medium 12 containing, in a diluent comprising kerosene and 10 % v/v of octanol, 40 g/l of Kelex 100 (~-dodecenyl 8-hydroxyqui-noline). The contacting step 14 between equal volumes of leach liquor and organic medium forms an aqueous phase 16, conta;ning nearly all Zn and a small quantity of germa-nium, and an organic phase containing the greatest part of germanium (87 %) and a very small portion of Zn. The aqueous phase is submitted to a second extraction stage.
The organic phase 18 is contacted with water, in a scrub-bing step 20, in equal volumes. Said scrubbing step forms an aqueous phase 22 containing the major part of Zn of the organic phase, with about all H+. A small portion of Ge is also included in the aqueous phase. The organic phase 24 of the scrubbing step contains 83 ~ of germanium from leach liquor and an insignificant amount of ~n. Said orga-nic phase is contacted with NaOH in a stripping step 26 first without shaking (190 minutes) and after with shaking ~'7~ ~5 (10 minutes). The volume o-f the aqueous phase is smal1er than that oF organic phase (ratio of 24). Said stripping step forms an aqueous phase containing germanium and an organic phase containing the diluent which may be used for the extraction step.
In an other example, the leach liquor 10 contai-ned 1,15 g/l of Ge and 47,8 g of Zn, with 145 g/l of ll2504, said organic medium 12 being the same as in prece-ding example. Contact time was 10 minutes in step 14. The organic phase contained 1,10 9/1 of Ge and the aqueous one less than 0,050 g/l of Ge (extraction ~ 95 %). Subsequent stripping by NaOH 3 N gave a re-extraction greater than 99 % (with shaking).
EXAMPLE 2 : Dependance of the extraction on the acidity -A solution of zinc sulphate containing 119 mg/l of germanium and having various acidities is contacted du-ring 15 minutes with an organic solution containing : Ke-1 ex 5 %, Octanol 10 %, Hexol D 100 85 %. The results of the extraction are summarized in the following table.

Acidity 0,42 N 0,6 N 0,76 N 0,84 N 1,1 N 1,5 N 2 N
O/A
I I I 1 1-- 1 ~ I I
I 1 175,6 %1 - I - I - I - I - I - I
I 0,5 I54,6 % 87,6%198,6 %198,3 % 98,6% 98,2% 99,4%
0,2 1 - - 156,7 %I63,4 % _ 92,2% 99,1%
0,1 I _ ~ 136,3 %143~9 % _ 89,2%195,6%

¦ Extraction yields %

EXAMPLE 3 : STRIPPING BY HYDROFLUORIC ACID
An organic phase loaded with germanium is agita-ted with hydrofluoric acid containing 2 % of hydro~luoric acid during 15 minutes with a ratio organic phase towards aqueous phase equal to 1. At ambient temperature, the yield is rather low, i.e. 15 %. At 50DC, the yield is about 87 %.

.

, , , <3~

EXAMPLE 4 : Action of the temperature on the stripping The stripping depends on the temperature and on the agitation. The table A shows clearly that heating is necessary for a quick stripping. In this example the stripping was studied at various temperatures, with agita-kion during 15 minutes and keeping the contact without stirring during 24 hours. The stripping solution in all the following tests was sodium hydroxide 3 N.
Table A

- ¦ Germanium g/l (aqueous pha Time 30 minutes I 0,34 I 0,39 I 0,48 1 hour ¦ 0,34 I 0,39 I 0,48 2 h 30 I 0,34 I 0,38 I 0,58 5 hours I 0,36 I 0,49 ¦ 0,58 6 h 30 I 0,38 I 0,54 ¦ 0,59 I 21 h 30 I 0,58 ~ 0,58 I 0,60 ¦ 24 hours ¦ 0,60 ¦ 0,60 ¦ 0,63 The following table, Table B, summarizes the re-sults of the stripping at various temperatures, but in this cas, the stirring was permanent. The initial concen-tration of the organic phase in germanium was 0,6 g/l. The stripping is much more quicker.

~17~:~4~

Table B

Time ¦ Germanium g/l (aqueous phase) ¦

22C I 40C I 50C I22C I 40~C I 50C
1- 1 1 1 1 .. . ~ I
¦ 30 mn ¦ 15 mn ¦ 30 mn¦0,14 1 0,56 ¦ 0,61 ¦ 1 h 30¦ 30 mn ¦ 1 h ¦0,56 ¦ 0,59 ¦ 0,63 ¦ 3 h 15¦ 1 h ¦1 h 30¦0,62 ¦ 0,59 ¦ 0,63 ¦ 5 h 301 1 h 301 2 h ¦0,63 ¦ 0,60 ¦ 0,65 ¦ 9 h ¦ 3 h ¦ 3 h ¦ 0,67 ¦ 0,61 ¦ 0,71 ¦21 h 30¦ 4 h 13 h 30¦0,70 ¦ 0~64 ¦ ~,74 ¦ ¦ 6 h ¦ 5 h ¦ ¦ 0,63 ¦ 0,79 ¦ l21 h 3016 h 301 ¦ 0,64 ¦ 0,80 The following table, Table C, shows that at 60C
with stirring, the stripping is complete in less than 30 minutes, the initial germanium content of the organic pha-se being 1.2 g/l. The ratio organic phase to aqueous phase is equal to 1.
Table C
_ Time in minutes Germanium g/l 2 1 0,93 7 1 1,00 12 1 1,15 17 1 1,18 22 1 1,17 I 27 1 1,18 EXAMPLE 5 : Germanium extraction by resin The resin used is a resin produced by Bayer and containing about 3Q0 grams of oxH by liter of resin (no octanol). The parameters of the example are following.
The volume of the bed is 1~ ml. The flow-rate is 4,4 bv/h. The washing is done with sulphuric acid 0,5 M.
The stripping is performed with sodium hydroxide 3 N. Some ~ 18 _ ~

attemps of stripping with hydrochloric acid have been do-ne. The results of these tests are summarized in the fol-lowing table.

¦~nitial ¦ H~ ¦Ge fixed ¦ Stripping ¦solution¦ N t I - 1---- 1 1 i -I
¦ Ge ¦ ¦ bv¦ mg ¦ NaOH 3N ¦yield¦ HCL ¦yield¦
¦ in gtl ¦ I ~ ¦ at 50C ¦ ~ ¦&e mg ¦ ~ ¦

¦ 1900 ¦ 3 ¦ 17¦122,50¦cold 27,51 22,4¦ l l I, 150~C 60,01 43,01 l l 1- 1 1 1 1 ~ ~ ---I
¦ 3 ¦ 11¦ 85~00¦ 30~0 ¦ ~5,3¦5N 48,75¦ 57,5 1,15 1 3 1 141 72~001 68~0 1 94~5 0,119 10,421 701 37,~01 40~0 1 98 0,119 11,~ 1 401 ~8,201 51~7 1 98 ¦ 0,119 11,4 ¦ 441 ~~¦ ¦ ¦ 8 N ¦ 95 ¦ 0,119 ¦1,4 ¦ 351 50,701 39,20 1 77,31 traces ¦
~ IF 2 % ¦
EXAMPLE 6 : Preparation of resin The resin is prepared according to the following way. The starting material is a polystyrenic macroporous resin witilout functionnal groups, e.g. AMBERLITE XAD.7*
The resin is washed with 9~ alcohol, with HCl 1 N and ~then with water until complete elimination of chlo-rlde ion. The resin is then dryed at 110C until its weight remains constant.
A solution ofp oxH is prepared in such a way that the total volume of the solution is sufficient to completely cover the resin, that the concentration in ~ oxH
corresponds to the weight desired, e.g. 30 % of the resin weight ; this corresponds generally to concentration of 10 * Trademark L~i to 50 70. The diluent is preFerably n-heptane~
The resin and the solution are mixed and the suspension is conditionned under vacuum to remove the ga-ses contained in the resin and to facilitate the introduc-tion of ~oxH.
The diluent, heptane, is evaporated. New amount of heptane is added and again evaporated. The resin obtai-ned is submitted to a temperature of llO~C during a night. The resin thus obtained is contacted with acidic solution and is ready for use and gives similar results to the resin provided by Bayer.
According to the same preparation, it is possi-ble to produce mixture of Kelex and polar liposoluble com-pounds.
Obviously, the invention is not limited to the treatment of leach liquors. An other specific application is the extraction of germanium from speissO Said extrac-tion is selective for germanium against iron and arsenic.

Claims

1. Process for selective liquid-liquid extraction of germanium from an aqueous acidic liquor containing, be-sides germanium, at least one other metal selected from the group comprising cadmium, zinc, cobalt, iron, arsenic and nickel, said process including - extracting germanium from said aqueous liquor by contacting said liquor with an organic medium which contains a diluent and an extractant, said diluent being immiscible with said aqueous liquor, said extractant being selected from the oxine derivatives having a long hydro-carbon chain, containing 8 to 16 carbon atoms, said extracting step forming an aqueous phase containing the major part of said at least one other metal and an organic phase containing the major part of germanium from said aqueous liquor, and - stripping germanium from said organic phase by contacting said phase with an aqueous medium, said strip-ping step forming an aqueous phase containing the major part of germanium from said aqueous liquor and an organic phase containing said diluent and said extractant.
2. Process according to claim 1, wherein the long hydrocarbon chain of said extractant has at least one ethylenical insaturation.
3. Process according to claim 1, wherein said ex-tractant is .beta. -dodecenyl-8-hydroxyquinoline.
4. Process according to claim 1, further including, before extracting step, adjusting the pH of said aqueous liquor at a value lower than 2.
5. Process according to claim 4, wherein said ad-justing of the pH includes addition of sulphuric acid.
6. Process according to claim 1, wherein said di luent is selected in the group comprising pure and mixed aliphatic compounds and petroleum fractions.
7. Process according to claim 6, wherein said di luent contains also a minor portion of at least one com-pound selected in the group comprising alcohols and phe-nols. Process according to claim 1, wherein the pH of said aqueous medium used in stripping step is alkaline and is greater than 10.
9. Process according to claim 8, wherein the pH of said alkaline medium used in stripping step is greater than 13.
10. Process according to claim 8, wherein said alkaline medium is NaOH.
11. Process according to claim 1, wherein the temperature of said leach liquor and said organic medium during said extracting step is ambient or lower.
12. Process according to claim 1, wherein the tempera-ture of the aqueous medium used in stripping step is an alkaline medium and said organic phase during stripping step is at least equal to 40°C.
13. Process according to claim 1, wherein the concentra-tion of extractant in organic medium is such that there are at least 4 moles of extractant for l mole of germanium in said aqueous acidic liquor.
14. Process according to claim 1, wherein said extractant is .beta.-dodecenyl 8-hydroxyquinoline, said diluent is kerosene containing a minor portion of octanol, said aqueous acidic liquor is an acidic leach liquor containing zinc, and the pH
during said extraction step is lower than 2.
15. Process according to claim 1, wherein the diluent is a resin.