CA1312207C - Recovery of germanium from aqueous solutions by solvent extraction - Google Patents
Recovery of germanium from aqueous solutions by solvent extractionInfo
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- CA1312207C CA1312207C CA000548084A CA548084A CA1312207C CA 1312207 C CA1312207 C CA 1312207C CA 000548084 A CA000548084 A CA 000548084A CA 548084 A CA548084 A CA 548084A CA 1312207 C CA1312207 C CA 1312207C
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- organic phase
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- d2ehpa
- oxime
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
ABSTRACT OF THE DISCLOSURE
An improved method for selectively recovering Ge from acidic solution containing Ge and typically Zn, As, Cd, Sb, In, Cu and Fe (II) by multistage, countercurrent liquid-liquid extraction is described. The extractant used in the organic phase is an oxime, for example 5,8-diethyl-7-hydroxy-6-dodecanone oxime, mixed with at least one alkylphosphoric acid, for example either di-2-ethylhexyl phosphate alone or admixed with mono-2-ethylhexyl phos-phate, dissolved in a hydrocarbon diluent. This mixed system shows better selectivity for germanium than known systems using either oximes or alkylphosphoric acids separately.
An improved method for selectively recovering Ge from acidic solution containing Ge and typically Zn, As, Cd, Sb, In, Cu and Fe (II) by multistage, countercurrent liquid-liquid extraction is described. The extractant used in the organic phase is an oxime, for example 5,8-diethyl-7-hydroxy-6-dodecanone oxime, mixed with at least one alkylphosphoric acid, for example either di-2-ethylhexyl phosphate alone or admixed with mono-2-ethylhexyl phos-phate, dissolved in a hydrocarbon diluent. This mixed system shows better selectivity for germanium than known systems using either oximes or alkylphosphoric acids separately.
Description
The possibility of using oximes, alXylphosphoric acids and oxines to extract a range of metals has been the subject of much study. Typical references concerning work on germanium extraction are as follows:
U.S. 3,760,060 (1973, Morgan) and U.S. 3,764,652 (1973, Morgan) disclose germanium extraction from alum solutions. The organic ~hase used contained a mixture of substituted phosphoric acids. The preferred extractant was mono-2-ethylhexylphosphoric acid. Di-2-ethylhexylphosphoric acid was found to be ineffective.
The organic phase contained about 20 weight % mono-2-ethylhexyl-phosphoric acid. The feed solution had a free sulphuric acid concentration of 0.05 to 0.60 molar, corresponding to about 5 to 60 g/L H2S4 U.S. 3,883,634 (1975, ~eSchepper, et al) discloses extraction of germanium from acid solutions using hydroxyoximes.
The preferred extractant is one known as LIX 63* which contains as active ingredient in a hydrocarbon diluent the compound 5,~-di-ethyl-7-hydroxy-6-dodecanone oxime. The germanium extraction capacity increases with the acidity of the feed solution. In the examples quoted, the acidity ranges from 13U to 460 g/L H2S04. No information is given on the co-extraction of cadmium, antimony or indium.
U.S. 4,389,379 (1983, Rouillard, et al) discloses selective extraction of germanium from acidic solutions, contain-ing zinc and other species, with oxine derivatives, the one known commercially as Kelex 100** being preferred. In the only example * Trade Mar~ of Henkel Corporation ** Trade Mark of Sherex Chemical Company ~ 3 1 2 2 o 7 2278-2~l given which demonstrates selective germanium extraction in the presence of zinc, the acidity is quite high, at 150 g/L H2S04. A
disadvantage of the process claimed in this patent is that -the temperature of the stripping stage must be relatively high, at least 40C. The rate of disengagement of the aqueous and organic phases is inherently slow.
U.S. 4,432,951 (1984, DeSchepper, et al) discloses germanium extraction from acid solutions carried out at tempera-tures above 40C with substituted oxines, such as Kelex 100 or LIX 26*.
U.S. 4,432,952 (1984, DeSchepper, et al) discloses germanium extraction at low acidity with a mixture of an alpha-hydroxyoxime (e,g. LIX 63) and a substituted 8-hydroxyquinoline (e.g. Kelex 100 or LIX 26). This patent clearly states that the aqueous feed solution must be almost free of copper, otherwise the alpha-hydroxyoxime becomes poisoned. No information is given on co-extraction of zinc, cadmium, antimony, or indium.
U.S. 4,568,526 (1986, Rouillard, et al), a continuation of U.S. 4,389,379, discloses germanium extraction by means of an organic solid medium containing an oxine derivative.
U.S. 4,666,686 (1987, Krajewski, et al) discloses extraction of gallium, germanium or indium from basic or acidic solution with an organic phase containing at least Kelex 100 and LIX 26. The organic phase may also contain tri-n-octylphosphine oxide.
A. DeSchepper, in 'iLiquid-Liquid Extraction of Germanium by LIX 63" Hydrometallurgy, Vol. 1, 291-298 (1976) describes the * Trade Mark Henkel Corporation 1 3 1 2 2 0 7 2278-24l extraction of germanium with LIX 63 in the presence of various impurities. No information is given on the impurities cadmium, antimony or indium. In a second paper, "Liquid-Liquid Extraction of Germanium by LIX 63" Chloride Hydrometall. Proc. (Int. Symp.) 1977, 357-367, the same author describes germanium extraction with LIX 63. No information is given on the deportment of cad-mium, antimony or indium. These papers contain much the same data as U.S. patents 3,~83,634 and 4,432,~52, above.
G. Cote and D. Bauer, in !'Liquid-Liquid Extraction of Germanium with Oxine Derivatives" Hydrometallurgy, 5, 1~9~160, (19~0), describe a survey of ten germanium extractants. Of those surveyed, oxine derivatives were found to be among the most effi-cient. Di-2-ethylhexylphosphoric acid was found to be a poor extractant for germanium.
R. Tian, et al, in "New Technology for Indium, Germanium and Gallium Recovery in an Electrolytic Zinc Plant", Miner. Proc.
Extr. Metall., Pap. Int. Conf. 1984, 615-624, describe extraction of germanium with a mixture of di-2-ethylhexylphosphoric acid and YW 100. The latter extractant i5 not identified. A search of the Chemical Abstracts Service database using the Registry No. [94336-45-5] for YW 100 disclosed no other references to this extract-ant.
This invention is directed to a method for the recovery of germanium and, more particularly, is directed to a method for the selective recovery of germanium from acidic aqueous solutions by countercurrent liquid-liquid extraction.
Germanium may be present in intermediate products 1 31 2207 227~-24l obtained in the processing oF ores and metal concentra-tes. A
typical source of such intermediate products is in the processing of zinc sulphide ores to ohtain zinc metal by the electrol~sis route. Such intermediate products can be in the form of ger-manium-containing solutions or solid residues. The latter may be solubilized to give germanium-containing solutions. The ger-manium-containing solutions usually contain one or more of a large number of other metals.
Although the invention will be described with specific reference to solutions obtained from the sulphuric acid leaching of zinc-bearing intermediate products, it is understood that -the method of the invention is also suitable for the recovery of germanium from other germanium-containing solutions.
According to the invention, germanium is substantially separated from the other metal constituents in an aqueous feed solution which may also contain significant amounts of any of the following: sulphuric acid, zinc, arsenic, cadmium, antimony, indium, copper and iron (ferrous) in addition to germanium. Thus the method of this invention is suitable for the efficisnt extrac tion of germanium from acid solutions containing the following ranges of metallic species concentrations, expressed in g/L:
Ge 0.005 - 5 Sb 0.01 - 1 Zn 0.5 - 160 In 0.01 - 2 As 0.005 - 4 Cu 0.001 - 0.1 Cd 0.005 - 5 Fe 0.01 - 50 (as ferrous~
Briefly, this invention utilizes the following standard steps:
~ ~ 2~ 2278-241 (1) Contacting the aqueous feed solution in an extrac-tion s-tep with an organic phase containing an extractant;
~2) Separating the loaded organic phase containing the ma~or portion of the germanium from the aqueous extraction raffin-ate which is substantially depleted in germanium:
(3) Contacting the loaded organic phase in a scrubbing step with a scrub solution containing a mineral acid, such as sulphuric acid;
(4) Separating the scrubbed organic phase, containing sub-stantially all of the germanium, from the scrub raffinate;
(5) Contacting the scrubbed organic phase in a stripping step with an aqueous alkaline solution to transfer substantially all of the germanium into the strip liquor;
(6) Separating the stripped organic phase from the strip liquor which contains substantially all o~ the extracted Ge.
(7) Contacting the stripped organic phase with an acidic regen-erant solution to restore the organic phase to its original condition;
(8) Recycling the regenerated organic phase to the extraction step; and (9) Treating the strip liquor to recover a germanium product.
Each of the mixed phase contacting steps (i.e., steps (1), (3), (5) and (7)~ ~ay comprise several stages connected in series, with countercurrent flow of the aqueous and organic phases in each sta~e.
This extraction system is thus seen to follow, in its broad outlines, essentially conventional practice. This invention is primarily concerned with one of the most important features of this system, namely the composition of the organic extractant phase used in step (1).
We have now found that an efficient separation o~
germanium, ~rom an aqueous solution containing yermanium and other metal elements including at least one of zinc, arsenic, cadmium, antimony, indium, copper and errous iron, and which also may contain sulphuric acid, can be achieved by a multistage counter-current liquid-liquid extraction system wherein the organic phase comprises a solution of an alpha-hydroxyoxime and at least one alkyl phosphoric acid in a hydrocarbon diluent.
To this organic phase may also be added, if desired, conventional additives to suppress foam formation and -to suppress emulsion formation, thus aiding phase separa-tion.
Preferably, the alpha-hydroxyoxime is 5,8-diethyl-7-hydroxy-6-dodecanone oxime, which is available commercially under the designation "LIX 53" as a 70% by volume solution in a hydxo-carbon diluent.
The preferred alkylphosphoric acid is a 2-ethylhexyl-phosphoric acid. It is preferred to use di-2~ethylhexylphosphoric acid (D2EHPA), or, more preferably, a mixture of D2EHPA and mono-2-ethylhexylphosphoric acid (M2EHPA).
The amount of each of these reagents used in the organic phase depends to some extent on whether a single alkylphosphoric acid, for example D2EHPA~ is used, or whether a mixture is used.
When D2EHPA is used alone with LIX 63, then the organic phase suitably contains from about 20 to about 30, preferably ~rom 1312207 2278~
about 20 to about 25, volume percent LIX 63 and a relatively small amount of D2EHPA, of about 3 to about 10, preferably about 4 to about 5 volume percent, the remainder being hydrocarbon diluent, and modifier (if required).
When D2EHPA alone is used with LIX 63, suitable diluents include kerosene, aliphatic hydrocarbons (e.g., Isopar M*) and aromatic hydrocarbons (e.g., Solvesso 100*). With kerosene diluent, in the absence of modifiers, stable emulsions form during extraction when the organic phase is conditioned by methods C-l or C-2, (see below for explanation of conditioning methocls), or with dilute sulphuric acid (150 g/L H2S04). Acceptable rates of phase separation can be achieved with kerosene without using a modifier if the organic phase is conditioned by methods C-3 or C-4. With-out conditioning, satisfactory phase separation with kerosene can be obtained by addition of long-chain alkanol modifiers, for example, 5 to 20 volume % of either l-decanol or 2-ethylhexanol.
The formation of stable emulsions with unconditioned organic phase using kerosene diluent cannot be preven-ted by addition of dibutyl-butylphosphonate or tributylphosphate. With Isopar M diluent and conditioning methods C-l, C-2 or C-4, addition of alkanol modi~
fiers, for example, 5~to 20 volume % of either l-decanol or 2-ethylhexanol~ prevents formation of stable emulsions. With Solvesso 100 diluent and conditionin~ method C-2, an acceptable rate of phase separation is achieved without using a modifier.
The efficiency of germanium extraction is influenced by the nature of the diluent, the addition of modifiers and by the method used to condition the organic phase. When D2EHPA alone is used wi~h Trade MarX of Exxon Chemical _ 7 ~
227~-2~1 LIX 63, the preferred diluent is a subs-tantially alipha-tic hydro-carbon, such as Isopar M, with an alkanol modifier, l-decanol being preEerred. The preferred concen-tration of l-decanol in the organic phase is about 10 volume ~. Less preferably, a substan-tially aromatic hydrocarbon diluent, such as Solvesso 100, may be used without a modifier. The preferred conditioning method is either C-l or C-2.
When both M2EHPA and D2EHPA are used together with LIX 63, ~hen the organic phase suitably contains from about 20 to about 30, preferably from about 20 to about 25, volume per cent LI~ 63, together with a total of from about 1 to about 25 volume percent of the combined M2EHPA and D2EHPA. Preferably, the amount of M2E~PA is from about 1 to about 12, particularly from about 2 to about 10 volume percent. Similarly, preferably the amount of D2EHPA is from about 1 to 10, more particularly from about 2 to about 6 volume percent.
The remainder of the organic phase, which is combined with the extractants LIX 63, M2EHPA and D2EHPA, is a hydrocarbon diluent. Kerosene, Isopar M and Solvesso 100 have been found to be suitable diluents. Kerosene is the preferred diluent. ~o modifier is required provided the organic phase is suitably condi~
tioned prior to use. Rapid phase separation is obtained when the organic phase is conditioned by methods C-l, C-2 or C-3. There is no significant difference in Ge extraction efficiency with these three conditioning methods. It is preferred to use conditioning methods C-l or C-2 ~ith no modifier.
It is also to be noted that as LIX 63, as purchased, is a 70~ solution of oxime in hydrocarbon, the ~IX 63 also contri~
butes to the ~otal hydrocarbon amount. Thus 20 volume percent of LIX 63 corresponds to about 1~% of oxime, and 30 volume percent corresponds to about 21% of oxime. The hydrocarbon present in LIX
63 as purchased is alleged to be about 11% aromatic and about 49%
paraffinics, with about 40% naphthenes~
Process steps (1) through (8) as noted above may be carried out at any convenient temperature in the range of from 0C
(freezing, obviously, needs to be avoided) up to about 55C.
Unlike some of the reported procedures for germanium recovery, elevated temperatures are not necessary, and a preferred tempera-ture range is 20 - 40C; in other words, the system can be allowed to reach its own thermal balance essentially in a "room tempera-ture" environment.
Some broad consideration will now be given to the steps detailed above.
As regards apparatus, conventional mixer-settler units of an appropriate size are suitable, for each of the mixed phase contacting steps (i.e. steps (1), (3) (5) and (7)).
In step (3), scrubbing, a mineral acid i5 used as the scrub solution~ It is convenient to use the same acid as is present in the aqueous feed solution. As this is often a sul-phuric acid solution, for example in an electrolytic recovery plant, it is convenient to use sulphuric acid in this step.
Conveniently when using sulphuric acid the concentration is from 50 ~o 300 g/L, with a preferred range at 100 to 200 gjL. The presence of zinc sulphate in the scrub solution, for example at 30 to 70 g/L zinc, also can be tolerated.
The alkaline strip solution for the stripping step (5) is preferably a sodium hydroxide solution containing 20 to 250 g/L
NaO~. The optimum concentration range is 120 to 200 g/L NaOH~ A
similar potassium hydroxide solution may also be used for stripping.
Regeneration of the organic phase in step (7) is effected by contacting the stripped organic phase with an acidic regenerant solution. The regenerant solution should contain 50 to 250 g/L H2SO~, preferably 100 to 200 g/L. It may also contain a salt such as zinc sulphate or sodium sulphate. The preferred salt is zinc sulphate, to provide a Zn concentration in the regenerant solution of 40 to 100 g/L.
A germanium product may be obtained ~rom the strip liquor by known means. For example, the strip liquor may be neutralized with acid to precipitate solids which contain the germanium. These solids may then be ~iltered off, dxied, and sold as germanium concentrate, or they may be dissolved in hydrochloric acid to produce a solution from which GeC14 may be distilled, with the impurities remaining in the distillation residue. It i5 desirable for arsenic to be absent because of the dif~iculty in separating arsenic and germanium chlorides by distillation.
GeC14 may be converted to electronic-grade elemental Ge by known methods.
There are some surprising and unexpected benefits to be gained in the use of this invention~
A high acid concentration is not required in the aqueous t312207 feed solution. The aqueous feed may contain 50 to 150 y/L H2S04, and although a hiyher acid concentration will not be harmful, it is no~ necessary. Alpha-hydroxyoximes alone are known ex-tractants for germanium, as disclosed in U.S. patent 3,8~3,~34. The acid concentrations in the examples quoted in this patent are high, ranging from 130 to 460 g/L. It is known that ~IX ~3 is an effec-tive extractant Eor germanium only at higher acidities (~ 90 g/L
H2S04). When LIX 63 alone is used for germanium extraction, a significant amount of acid is co-extracted along with the german-ium, and the acid co-extraction increases with increasing acid concentration in the aqueous feed solution. The co-extracted acid may be partially removed by scrubbing the organic phase with water prior to stripping. If water scrubbing is not implemented, the extracted acid remains in the organic phase until the stripping stage is reached, where the acid is neutralized and the germanium is stripped with alkaline strip solution. This results in both a relatively low germanium concentration in the strip liquor, and a high consumption of alkaline strip solution, which increases process operating costs.
With the process of -this invention, it has surprisingly been found that addition of relatively minor proportions of M2EHPA
and D2EHPA, or of D2EHPA alone, to LIX 63 gave improved germanium extraction, even with a comparatively low acid concentration in the aqueous feed. This finding is especially interesting in view of the fact that D2EHPA by itself is reported to be a poor extrac-tant for germanium at low acidities and only becomes eEficient when the concentration of sulphuric acid in the feed solution exceeds several hundred grams per litre. In the present inven-tion, aside from a favourable overall reduction in acid consump-tion, relatively little acid is co-extracted. The need for water scrubbing is eliminated and also alkali wastage as, for example, sodium sulphate, in the stripping stage is minimized. Further, a higher germanium concentration is obtained in the strip liquor, which in turn greatly facilitates efficient recovery of a germanium product.
Another surprising feature o~ this invention is that alkyl esters oE phosphoric acid, including ~2EHPA and D2EHPA, are reported to extract both zinc and indium -from acidic aqueous phases. It was surprisingly found that zinc and indium extraction is suppressed when alpha-hydroxyoxime is used in combination with alkyl esters of phosphoric acid.
Additionally, it is reported that the efficient extrac-tion of germanium with alpha-hydroxyoximes alone requires a high extractant concentration in the organic phase, i.e. 70 to 100%.
In the case of LIX 63, 100~ means that the LIX 63 is used as pur-chased for the organic pha.se. In contrast, efficient germanium extraction is obtained in the present invention with considerably lower alpha-hydroxyoxime concentrations, leading to a favourable reduction both in extractant inventory, and in organic phase vis-cosity. Low viscosity enhances extraction kinetics, aids phase separation and reduces settler area requirements. A further benefit of lower extractant concentrations in the organic phase is less conversion of the oxime and alkyl esters of phosphoric acid to their corresponding alkali metal salt forms during the alkaline stripping step. The advantages of this are lower alkali consump-tion during stripping, less dilution o~ the germanium content in the strip liquor, lower acid requirement in regenerating the solvent and less production of waste sulphate salt during both stripping and regeneration.
In the Examples, which are set Eorth below, several different methods of conditioning -the fresh organic phase were used. In ~ach case, the organic phase was contacted with the indicated acidic solution(s) for about 15 minutes, and then separated therefrom prior to use in extraction. The four most fre~uently used methods were:
C-l Treatment with solution containing 150 g/L H2SO4 and 140 g/L
Na2SO~ . ~
C-2 Treatment with "return acid". So-called "return acid" is the solution remaining after electrowinning zinc from a zinc sulphate solution. Return acid contains about 150 g/L H2S04 and about 50 g/L Zn, present as ZnSO4, plus a range of other elements in varying amounts.
C-3 Two-stage treatment, the first stage consis-ting o~ treatment with "neutral" zinc sulphate electrolyte solution containing about 150 g/L Zn and having a pH of about 4.8, and the second stage consisting oP treatment with return acid.
C-4 Treatment with aqueous feed solution of specified composi-tion.
The main purpose of conditioning was to pre-load the organic phase with acid, to help ensure equilibration of the aqueous and organic phases during extraction. Another benePit of 1 31 2207 2z7~ 241 conditioning is -that it may remove undesired water-soluble impurities from the organic phase. As described previously, con-ditioning also had an impact on phase separation. In general it was found that conditioning methods employing solutions having a high ionic strength gave higher phase disengagement rates. Condi-tioning methods C-l and C-2 are preferred because the solutions used would be appropriate regenerant solutions in the regeneration step prior to extraction in a continuous process for germanium recovery from a sulphate-based zinc h~drometallurgical circuit.
LIX 63 was obtained from Henkel Corporation. One lot of LIX 63 was found to be impure, containing a small amount of aro-matic compounds, such as benzophenone oxime. This lot gave slower Ge extraction rates than pure lots. Pure LIX 63 was used in the Examples, except for Examples 1, 3 and 5, when the impure material was used.
The 2-ethylhexylphosphoric acid esters used in the Examples were obtained from several sources. The mono-ester M2EHPA is not available commercially in a pure state. It is always admixed with at least some di-ester, D2EHPA, and sometimes even with the tri-ester in small amounts. The M2EHPA used was obtained from Albright ~ Wilson, Ltd., Hodag Chemical Corporation, Stauffer Chemical Company and Pfaltz & Bauer, Inc., under names such as "OAP" (octyl acid phosphate), or "EHAP" (ethyl hexyl acid phosphate). As supplied, the material varies from lot to lot to a small de~ree. The material used in these Examples contained from about 54 to about 60% by volume of M2EHPA, and from about 40 to about 46% by volume D2EHPA~ The fact that M2EPHA is a mixture 1 3 1 2 2 0 7 2278-24l with D2EHPA is allowed for in the Examples when amounts of M2EHPA
and D2EHPA are given. Commercial-grade D2EHPA was obtained as a 97-98% pure liquid from Albright & Wilson, Ltd., and from AZS Corporation.
Kerosene, designated No. 3Cl-101-47, containing par-affins, naphthenes and about 15~ aromatic hydrocarbons (obtained from Shell Chemical Co.) was used in the Examples unless otherwise indicated. Isopar M, a diluent containing ~99% aliphatic hydro-carbons, and Solvesso 100, a diluent containing ~9~ aromatic hydrocarbons, were obtained from Exxon Chemical and Imperial Oil, Ltd., respectively.
l-Decanol was obtained from Exxon Chemical and C-I-L Inc. 2-Ethylhexanol was obtained from Fisher Scientific Co.
Dibutylbutylphosphonate and tributylphosphate were obtained from Albright & Wilson, Ltd.
~ eayent-grade ~aOH and NA2SO4 were used. Reagent-grade H2SO4 was used except where otherwise indicated.
Unless otherwise indicated, the tests described in the following Examples were conducted at room temperature.
Example 1 Extraction of Ge with LIX 63 Alone An organic phase consisting of, by volume, 25~ LIX 63 and 75~ kerosene, was conditioned by method C-l. The LIX 63 contained aromatic impurities. A portion of aqueous feed solution containing 0.63 g/L Ge and 75 g/L H2SO4 was contacted for 18 min-utes in a mixer unit with the conditioned organic phase at an organic phase to aqueous phase volume ratio of 1/1. After phase 1 3 1 2 2 0 7 2278-2~1 separation, the aqueous extraction raf-finate was analyzed and found to contain 0~34 g/L Ge. The organic phase was calculated to contain 0.29 g/L Ge corresponding to 46~ Ge extraction. Example 1-shows that LIX 63 by itself extracts Ge from solutions having relatively low acid concentrations, as expected.
Example 2 Extraction of Ge with D2EHPA Alone An organic phase consisting of, by volume, 5% D2EHPA and 95% kerosene, was conditioned by method C-l. A portion of aqueous feed solution containing 0.63 g/L Ge and 75 glL H2S0~ was contact-ed for 18 minutes in a mixer unit with the conditioned solvent at a phase volume ratio of l/l. Upon anal~sis of the aqueous extrac-tion raffinate, it was found that no Ge has been extractedO
Example 2 demonstrates that an organic phase containing D2EHPA by itself is ineffective for extracting Ge from sulphate solution containing a relatively low H2S04 concentration, in accordance with the teaching of U.S. patents 3,760,050 and 3,764,652.
Example 3 Extraction of Ge with Combined LIX 63 and D2~HPA
A series of tests was carried out using organic phases containing both LIX 63 and D2EHPA as combined extractants, to-gether with various diluents, modifiers and solvent conditioning methods. The LIX 63 contained aromatic impurities. The results are shown in Table l. In each test, aqueous feed solution con-taining 0.66 g/L Ge and 75 g/L H2S04 was contacted for 18 minutes in a mixer unit with conditioned organic phase at a phase volume ratio of 1/1. Organic phase composition is expressed in volume %.
Organic Phase Test Cond. Ge No. LIX 63 D2EHPA Diluent Modifier Method Extr'n _ _ _ _ 3(a) 25~ 5~ 70~ nil C-4 56%
3~b) 25% 5% kerosene nil C-3 60%
3(c) 20~ 4% Isopar M 2-ethyl- C-2 67 56% hexanol .
3(d) 25% 5% Isopar M l-decanol C-4 74%
60~ 10%
3(e) 25~ 5% Solvesso 100 nil C-2 83%
.
3(f) 25% 5% Isopar M l-decanol C-l 89%
_ 60% 10%
This Example shows that an organic phase containing a combination of LIX 63 and D2EHPA gives better Ge extraction than LIX 63 alone, although D2EHPA by itself does not extract Ge under the test conditions used, as is shown above in Example 2.
Example 3 also indicates that Ge extraction efficiency with com-bined L,IX 63 and D2EHPA is influenced by the nature oE the hydro-carbon diluent, by the addition of modifiers, and by the methodused to condition the organic phase. Higher Ge extraction was obtained with the diluents Isopar M (substantially aliphatic) and Solvesso 100 (substantially aromatic) than with kerosene. A
satisfactory rate o phase disengagement was observed in all the tests listed in Table 1. With kerosene or Solvesso 100, adequate phase separation was attained without addition of a modi-fier, provided the organic phase was properly conditioned prior to ex-traction. Conditioning methods C-3 and C-4 were suitable for kerosene, and method C-2 was suitable for Solvesso lO0. With Isopar M, using conditioning methods C-l, C-2 or C-4, addition of a modifier was necessary to prevent stable emulsions. The alkanol modifiers l-decanol and 2-e-thylhexanol both proved satisfactory.
Comparisons of Test 3(a) with 3(b) and 3(d) with 3(f) indicate that the conditioning method has an effect on the efficiency of Ge extraction. With kerosene diluent, C-3 appears preferable to C-4.
With Isopar M diluent in the presence of lO volume ~ l-decanol, C-l appears preferable to C-4. The highest Ge extraction efficiency was obtained with Isopar M diluent in the presence of 10 volume ~ l-decanol. Solvesso lO0 with no modifier was next best. It is believed that the relative ranking of the results shown in Table l was not substantially affected by the presence of small amounts of aromatic impurities in the LIX 63.
Example 4 Extraction of Ge with Combined D2EHPA and M2EHPA
An organic phase consisting of, by volume, 2.3% D2EHPA, 2.7~ M2EHPA and 95~ kerosene was conditioned b~ method C-l. A
portion of aqueous feed solution containing 0.63 glL Ge and 75 g/L
H2S04 was contacted for 18 minutes in a mixer uni-t with the con-ditioned organic phase at a phase volume ratio of 1/l. Extraction of Ge was 52%.
This result demonstrates that a mixture of M2EHPA and D2EHPA is capable of extracting Ge under relatively low acid conditions.
Example 5 Extraction of Ge with Combined LIX 63, D2EHPA and M2EHPA
, Portions of conditioned organic phase were prepared containing varying proportions of LIX 63, M2EHPA and D2EHPA, with Xerosene diluent. The LIX 63 contained aromatic impurities, Portions of an aqueous feed solution containing 0~590 g/L Ge and 75 g/L H2S04 were contacted with conditioned organic phase for 18 minutes in a mixer at an organic phase to aqueous phase volume ratio of l/l. The results for Ge extraction are given in Table 2.
~ . .
Test LIX 63 D2EHPA M2EHPA Kerosene Cond. Ge No. Vol. ~ Vol. % Vol. % Vol. % Method Extr'n . _____ . . .
5(a) 25 0.9 l.l 73 C-l 84%
5(b) 25 2.3 2.7 70 C-l 96%
5(c) 25 2.3 2.7 70 C-2 97%
5(d) 25 2.3 2.7 70 C-3 95%
5(e) 25 2 3 70 C-l 99%
5(f) 25 2 3 70 C-2 97%
5(g) 25 4.6 5.4 65 C-2 96%
5(h) 25 6.9 8.1 60 C-2 95~
5(i) 25 6 9 60 C-2 97%
5(j) 20 9 11 60 C-2 93%
. .__ _ . . . .
Example 5 shows that addition of M2EHPA -to the LIX 63- -D2EHPA extractant system provides highly efficient Ge extraction from relatively low-acid feed solution. Rapid phase separation was obtained with the three conditioning methods tested.
The conditioning method used had no significant effect on the overall efficiency of Ge extraction. It is noticeable that the ratio of the amount of LIX 63 (and thus by inference the -- lg --1 ~t 2~07 amount of actual oxime) to the total amount of phosphoric acid esters present does appear to influence the efficiency of extrac-tion of Ge. With 25 volume % LIX 63, optimum efficiency appears to be obtained at a LIX 63 to total phosphoric acid esters ra-tio in the region of 4 - 5 to 1, on a volume percent basis.
Example 6 Effect of Acid Concentration in Aqueous Feed Solution on Extraction of Ge,As,Cd, Sb and In with Combined LIX 63, D2EHPA and M2EHPA
Portions of aqueous feed solutions containing Ge, As, Cd, Sb, In and various concentrations of H2S04 were contacted with unconditioned organic phase by shaking them together for ~
minutes in separatory funnels. The organic phase contained, by volume, 25% LIX 63 2.3% D2EHPA, 2.7% M2EHPA and 70% kerosene. -This ratio of LIX 63 to total phosphate esters is thus in the range in which optimum Ge extraction (Cf Ex 5) can be expected~
The organic phase to aqueous phase volume ratio was 1/1, Phase separation was rapid. After phase separation, the extraction raffinates were analyzed. The concentrations of solutes in the organic phases were calculated from the raffinate analyses. The results are summarized in Table 3.
.
H2SO4 Solute Aqueous Raffinate Organic Test Conc. Feed Phase Phase Extraction No.g/L g/L g/L g/L
6~a)49.5 Ge 0.72 0.245 0.475 66 As 1.35 1.30 0.05 4 Cd 3.7 3.7 0.0 0 Sb 0.4 0.17 0.23 57 In 0.9 0.6 0.3 33 6(b)75 Ge 0.68 0.165 0.515 76 As 0.94 0.94 0.0 0 Cd 3.0 3.0 0.0 0 Sb 0.25 0.13 0.12 48 In 1.0 0.67 ~.33 33 6(c)125 Ge c=~ == 0.087 0.593 87 As 0.94 0.94 0.0 0 Cd 3.0 3.0 0.0 0 Sb 0.25 0.13 0.12 48 In 1.0 0.84 0.16 16 __ __ ,_ , 6(d)150 Ge 0.575 0.041 0.534 93 As 1.35 1.3 0.05 Cd 3.7 3.7 0.0 0 Sb 0.4 0.16 0.24 60 In 0.9 0.88 0.02 ;
This Example shows that Ge ex_raction with combined LIX 63, D2EHPA and M2EHPA improves with increasing acid concentra-tion in the aqueous feed solution. There is little or no ex-trac-tion of As and no extraction of Cd. Sb extraction is significan-t at all feed acid concentrations. Extraction from the aqueous phase of In ranged from moderate at low aqueous phase acid concen-tration, to very low at higher acid concentrations. This rela-tively low In extraction is particularly surprising in view of the fact that D2EHP~ by itself extracts In efficiently under the test conditions, as will be shown in Example 7. By comparing the extremely high In extraction efficiency obtained in Example 7 with - 21 ~
2278-2~1 the rather modest extraction in Example 6, it is evident that considerable suppression of In extraction can be achieved by suit-able selection of the organic phase composition. However it should also be noted, as can be seen from Exam~le 8, that the level of In extraction depends on the total amount of phosphate esters present: increasing their amount increases In extraction, although the total extracted is still not as high as the reportad capabilities of D2EHPA would suggest.
Example 7 Extraction of In with D2EHPA
A portion of aqueous feed solution containing 0.950 g/L
In and 146 g/L H2SO4 was contacted with an equal volume of uncon-ditioned organic phase containing, by volume, 5% D2EHPA and 95~
kerosene, by shaking for ~ minutes in a separatory funnel. Phase separation was slow. The extraction raffinate was found to con--tain 0.006 g/L In, corresponding to 0.944 g/L in the organic phase. The percent In extracted was thus ~ 99%.
Example 7 shows that D2EHPA by itself is a very effi-cient extractant for In under acid conditions, although phase separation is difficult. It is possible that addition of an alkanol modifier might assist in phase separation. It was later found that formation of stable emulsions could be prevented, with-out using a modifier, by conditioning the D2EHPA-kerosene organic phase by method C-l or C-2 prior to extraction.
2278~241 Example 8 Effect of Concentration of Extractants on Extraction of Ge, As, Cd, Sb and In -~ portion of aqueous feed solution containing Ge, ~s, Cd, Sb, In and 125 g/L H2SO4 was contacted with an equal volume of unconditioned organic phase containing, by volume, 30~ LIX 63, 4.6~ D2EHPA, 5.4% M2E~IPA and 60% kerosene, by shaking for 4 min~
utes in a separatory funnel. The results of the test are shown ln Table 4.
H2SO4 Solute Aqueous RaffinateOrganic Conc. Feed PhasePhaseExtraction g/L g~L g/L g/L
.. _ _ ..... ~ ..... _ 125 Ge 0.68 0.0470.633 93 As 0.94 0.9 0.04 4 Cd 3.0 3.0 0.0 0 ~b 0.25 0.14 0.11 44 In 1.0 0.21 0.79 79 The results in Example 8 are directly comparable with the results of Test 6(c) in Example 6, all the variables, except the organic phase composition, being the same in both tests.
Example 8 shows some improvement in Ge extraction and increased As extraction. Cd is not extrac-ted, as before. Sb extraction is slightly lower. Extraction of In increased greatly, possibly as a consequence of the total amount of phosphate esters being doubled (i.e. 5% in Ex. 6, 10% in Ex.8).
1 3 1 2207 2278-~41 Exa~ple g Selective Ge Extraction in the presence of Zn, As, Cd, Sb, In, Cu and Fe (II) To simulate a continuous multistage extraction, an aqueous feed solution containing, (in g/L), ~2~4 75, Zn 41, Ge 0.68, As 0.94, Cd 3.0, Sb 0.25, In 1.0, Cu 0.011 and Fe (II) 34.7, was subjected -to batch countercurrent 3-stage 5-cycle extraction as described in the Fifth ~dition (1973) of "Chemical Engineers' Handbook", (McGraw-Hill BooX Company) Section 15, page 15. The fresh organic phase was not conditioned, and contained, by volume, 25~ LIX 63, 2.3~ D2EHPA, 2.7% M2EHPA and 70~ deodorized kerosene (obtained from J.T. Baker Chemical Co.). The organic to aqueous phase volume ratio was 1/1. Separa-tory funnels were used, with a shaking time of 4 minutes. The resulting organic phase con~
tained, (in g/L), Ge 0.68, Cd 0.14, Sb 0.15 and In 0.90. Ex-trac-tion of Zn, As, Cu and Fe was insignificant. This organic phase was then subjected to 9 successive contacts with fresh port-ons of the aqueous feed solution using a separatory funnel with a shaking time of 4 minutes for each contact, and an organic to aqueous phase volume ratio of 1/1. The 9 aqueous raffinates were analyzed and the composition of the organic phase after each contact was calculated. There was no significant transfer of Zn, As, Cu or Fe to the organic phase. The results for Ge, Cd, Sb and In are shown in Table 5.
1 3 ~ 2 2 0 7 2278-241 Raffinate PhaseOr~anic Phase (g/L) (g/L) Ge CdSb In Ge Cd Sb In Initial Organic Phase - - - - 0.68 0.14 0.15 0.90 After Contact " " ~o. 1 0.110 3.13 0.130 l.O0 1.25 0.01 0.27 0.9 " " No. 2 0.130 3.01 0.129 1.04 1.80 0 0.39 0.86 " " No. 3 0.150 3.00 0.130 1.04 2.33 0 0.51 0.82 " " ~o. ~ 0.160 3.00 0.132 1.04 2.85 0 0.63 0.78 " " No. 5 0.160 3.00 0.159 1.125 3.36 0 0.72 0.655 " " No. 6 0.165 3.00 0.169 1.05 3.865 0 0~81 0.605 " " ~o. 7 0.205 3.00 0.162 1.025 4.33 0 0.90 0.58 " " No . 8 0.205 3.00 0.162 1.025 4.795 0 0.9g 0.555 " " No. 9 0.245 3.00 0.162 1.05 5.22 0 1.07 0.505 Example 9 indicates that the Ge loading capacity of the solvent is surprisingly high, and at 5.2 g/L Ge has still not reached its maximum capacity. The Cd initially present in the organic phase was selectively and completely removed by contact with the aqueous feed solution. Sb continued to be extracted in nearly constant increments during each contact. The selectivity ratio for Ge extraction over Sb extraction is estimated to be between 3.2 and 5.5 under the conditions of this test. The In content of the organic phase steadily declined during repeated contacts, indicating that it would be possible to minimize In extraction through careful selection of the organic to aqueous phase volume ratio and the number countercurrent of extraction stages.
Exam~le 10 Reductlon of Cu and Ferric Iron Content in Aqueous Feed Solution The organic phase of this invention was found to be capable of extracting a significant amount o~ Cu and ferric iron 2278-24~
from acidic aqueous solutions if the concentrations of these species are sufficiently high. For feed solutions containing more than 0.03 g/L Cu and 0.10 g/L ferric iron, the ~ollowing steps were taken. The feed solution was heated to 90C, lead sulphide concentrate was added in the amount of 2 to 3 g for every gram of ferric iron present per litre of solution, and the mixture was agitated for 30 minutes. Then iron grit was added, 1.5 g per litre of solution, and the agitation was continued for a further 15 minutes. Upon cooling and separation of the solids, the H2SO~
concentration was adjusted as required to provide a feed solution suitable for Ge extraction. Using this procedure on a particular batch of solution, the Cu concentration was lowered from 0.105 g/L
to 0.011 g/L and the ferric iron concentration was lowered from 4.2 g/L to virtually zero. The ~errous iron concentration in-creased from an initial value of 29.0 g/L to a final value of 34.7 g/L. Since As was also present in the solution, precautions were taken to deal with ~ossible arsine generation, ~owever no arsine was observed. Example 10 demonstrates an efficient and inexpensive means of lowering the copper and ferric lron concen-trations in the aqueous feed to manageable levels prior to liquid-liquid extraction.
Example 11 Scrubbin~ of the Loaded Organic Phase Following the extraction step, Cd and In are selectively removed from the loaded organic phase by scrubbing with an acidic aqueous solution.
In one case, the organic phase used for extraction 1 3 1 2 2 0 7 227~-241 contained, by volume, 30% LIX 63, 4~6~ D2EHPA 5.4% M2E~PA and 60 kerosene. After extraction, the solu-te concentrations in the loaded organic phase were: Ge Q.68 g/L, Cd 0.27 g/L, Sb 0.15 g/L
and In 0~99 g/L. Scrubbing was carried out by shaking the loaded organic phase with an equal volume of dilute H2S04 (50 g/L) for ~
minutes in a separatory funnel. Phase separation was rapid. The scrub raffinate was analyzed and the solute concentrations in the scrubbed organic phase were calculated to be: Ge 0.664 g/JJ, Cd 0.134 g/~, Sb 0.150 g/L and In 0.984 g/L. Scrubbing removed a substantial amount of Cd from the loaded organic phase, however, In removal was insignificant. No Sb was removed.
In a second case, the organic phase used for extraction contained, by volume, 25% LIX 63, 2.3% D2EHPA, 2.7% M2EHPA and 70%
kerosene. A~ter extraction, the solute concentrations in the loaded organic phase were: Ge 0.68 g/L, Cd 0.25 g/L, Sb 0.145 g/L
and In 0.75 g/L. Scrubbing was carried out as described in the first case, except that the scrub solution consisted of return acid. Rapid phase separation was obtained. The soLute concen-trations in the scrubbed organic phase wQre found to be: Ge 0~674 20 g/L, Cd 0.060 g/L, Sb 0.141 g/L and In 0.32 g/L. Thus, a higher acid concentration in the scrub solution improved the Cd removal even further and gave, in addition, substantial In removal. Very little Sb was removed.
Example 11 shows that co-extracted Cd and In can be selectively scrubbed from the loaded organic phase with return acid.
Example 12 Stripping Ge and Sb from the ~crubbed Organic Phase Following the scrubbing step, Ge and Sb are stripped from the organic phase wi~h an aqueous alkaline strip solution.
Two-stage stripping was tested, at two temperatures, 20C and 55C. Ex~raction of an aqueous feed solution was carried out with organic phase containing, by volume, 25~ LIX 63, 2.3~ D2EHPA, 2.7%
M2EHPA and 70~ kerosene. The resulting loaded organic phase was scrubbed with return acid. The organic phase, after scrubbing, contained: Ge 0.666 g/L, Sb 0.116 g/L and In 0.320 g/L.
In a stripping test at 20C, a portion of the scrubbed organic phase was contacted with fresh aqueous strip solution containing 200 g/L NaOH, in a beaker agitated with a magnetic stirrer. The organic to aqueous phase volume ratio was 2/1. After 4 minutes of stirring, the resulting emulsion was transferred to a separatory funnel and the phases were allowed to disengageO The aqueous phase, or first strip liquor, was analyzed. The composi-tion of the organic phase, or "first stripped organic phase", was calculated by difference. The first stxipped organic phase was then subjected to a second stage of stripping, using fresh strip solution, under the same conditions as in the first stage. The resulting aqueous phase, or "second strip liquor", was analy~ed, and the composition of -the stripped organic phase, or "second stripped organic phase" was calculated. The results are shown in Table 6.
A second stripping test was carried out at 55C, in a manner similar to the preceeding test, but with the ~ollowing - 2~ -differences in procedure. The organic phase and strip solution were separately preheated to 55C, then contacted in a beaker on a stirring hot plate at 55C, and finally the emulsion was trans-ferred to a separatory funnel placed in a water bath at 55C for phase disengagement. The results are shown in Table 60 First Strip First Stripped Stripping Liquor (g/L)Organic Phase (g/L) % Stripped Temp.
_ Sb In Ge Sb In Ge Sb In- - - - _ _ _ _ 20C1.100 ~.202 0.180 0.116 0.015 0.230 83~ 87% 28 55C1.150 0.199 0.031 0.091 0.017 0.304 86% 85~ 5%
Second Strip Second Stripped Total Liquor (g/L)Organic Phase (g/L) ~ Stripped Ge Sb InGe Sb In Ge Sb In 20C0.065 0.031 0.0350.083 0.0 0.212 87% 100~ 34%
55C0.038 0.021 0.0230.072 0.007 0.292 89% 94% 9%
A white amorphous precipitate formed in the first stage of stripping at both temperatures. The amount formed at 55C was less than at 20C. X ray analysis showed that the precipitate consisted of In(OH)3. Formation of troublesome amounts of the precipitate can be avoided by minimizing In co-extraction. Phase separation was rapid at both temperatures.
Example 12 shows that Ge and Sb can be efficiently stripped from the scrubbed organic phase by means of 2-stage alkaline stripping. In is partially stripped. Raising the stripping temperature from 20C to 55C has only a slight ef~ect on Ge and Sb stripping. Substantially less In is stripped at 55C than at 20C.
Example 13 Continuous Pilot-Scale Test ~ 58-hour continuous test including extraction scrubbing, stripping and solvent regeneration was carried out using small pilot scale equipment. The total volume of aqueous feed treated was 105 litres~ To prepare the aqueous feed, zinc plant leach solution was treated as described in ~.xample lO to lower the Cu and ferric iron content. The resulting aqueous feed had the following composition, expressed in g/L:
H2SO4 llO As 0.545 In 0.~40 Zn 85 Cd 0.940 Cu 0.006 Ge 0.590 Sb 0.195 Fe 15 (as ferrous) The organic phase contained, by volume, 25~ LIX 63, 2.1~ D2EHPA, 2.9~ M2EHPA and 70% kerosene. The organic phase was initially conditioned with return acid (method C-2). In the extraction step, the aqueous feed was contacted countercurrently with the organic phase recycled from solvent regeneration in 3 series-connected mixer/settlers, at an organic phase to aqueous phase volume ratio of l/3. In the scrubbing step the loaded organic phase was contacted countercurrently with scrub solution in 3 series-connected mixer/settlers at an organic phase to aqueous phase volume ratio of l/l. The scrub solution, comprising return acid fortified with technical grade 93% H2S04, contained about 50 g/L Zn and 200 g/L H2S04. In the stripping step, the scrubbed organic phase was contacted countercurrently with strip solution in 3 series-connected mixer/settlers at an organic phase 1312~07 2278-241 to aqueous phase volume ratio of 5/1. The strip solution con-tained 200 g/L NaOH. In the organic phase regeneration step, the stripped organic phase was contacted with regenerant solution in one mixer/settler at an organic to aqueous phase volume ratio of 1/1. The regenerant solution comprised return acid. Regenerated organic phase was recycled to the extraction step. In all the mixer/settlers the appropriate phase was recycled in order to maintain an organic phase to aqueous phase volume ratio of close to one in each mixer. The organic phase made about 5 cycles through the equipment during the course of the test. The raffin-ates, strip liquor and regenerated organic phase were analyzed.
The solute concentrations in the loaded organic, scrubbed organic and stripped organic phases were calculated by difference. The Ge, Sb and In concentrations are given in Table 7.
1 3 1 2207 2278-24l Table 7 Ge Sb In ~/L g/L g/L
ExtractionIn Aqueous Feed 0.590 0.195 0.940 Regenerated Organic 0.040 0.065 0.001 Out Extraction Raffinate 0.030 0.01~ 0.925 Loaded Organic 1.720 0.596 0.046 ScrubbingIn Scrub Solution 0 0 0 Loaded Organic 1.720 0.596 0.046 Out Scrub Raffinate 0.025 0.038 0.043 Scrubbed Organic 1.695 0.558 0.003 StrippingIn Strip Solution 0 0 0 Scrubbed Organic 1.695 0.558 0.003 Out Strip Liquor 14.00* 0.830* 0.008*
Stripped Organic 0.041 0.195 0.002 Regeneration In Regenerant Solution 0 0 0 Stripped Organic 0.041 0.19S 0.002 Out Regeneration ~affinate 0.001 0.130 0.001 Regenerated Organic 0.040 0.065 0.001 * These values were higher than expected, due to volume reduction of the aqueous phase.
The recovery of Ge was excellent. About 95~ of the ~e in the aqueous feed was extracted. The loss of Ge in scrubbing was very low. About 9~ of the Ge in the loaded organic was stripped. The deportment of Sb was more complex. About 91% of the Sb entering the extraction step was co-extracted. About 6% of the Sb in the loaded organic reported to the scrub raffinate, 16%
reported to the strip liquor, 44% precipitated in the stripping mixer/settlers as a white precipitate containing sodlum antimon-ate, 23~ reported to the regeneration raffinate, and 11~ remained in the regenerated organic phase. The sodium antimonate precipi-tate did not impede phase separation. Less than 2% of the In in the aqueous feed was co-extracted. Of the extracted In, 93~ was removed from ~he organic phase during scrubbing. There was no significant co~extraction of 2n, As, Cd, Cu and Fe.
Example 13 shows that an organic phase including a LIX 63-D2EHPA-M2EHPA mixed extractant provides efficient and selective Ge extraction from solutions containing a variety of other metal ions. The selectivity with respect to Sb is lower than with other species; but is still more than adequate. The formation of an antimony-containing precipitate in the stripping stage is not a serious problem. The precipitate could be easily removed by settling, filtering or centrifu~ing or other known methods, or by a combination of these methods. Although scrubbing and organic phase regeneration were carried out at an organic phase to aqueous phase volume ratio of 1/1 for convenience during the test, this ratio could be raised to 5/1 in bo-th of these steps.
Note In the preceding discussion, and in the following claims, terms are used to describe various esters of orthophos-phoric acid, H3PO4. Whilst proper schematic names for these com-pounds, according to the I.U.P.A.C. Rules, exist they are not used in commercial practice. To avoid any doubt as to the nomenclatur~
used herein, the following definitions are provided; in each of them the group R is an alkyl group, for example the 2-ethylhexyl group referred to extensively herein.
~ ~ 1 2 ~ ~ 1 2278-241 I RO
HO - P = O : Monoalkylphosphoric acid HO
II RO
RO - P = O : Dialkylphosphoric acid HO /
III RO
RO - P = O : Trialkylphosphate RO
U.S. 3,760,060 (1973, Morgan) and U.S. 3,764,652 (1973, Morgan) disclose germanium extraction from alum solutions. The organic ~hase used contained a mixture of substituted phosphoric acids. The preferred extractant was mono-2-ethylhexylphosphoric acid. Di-2-ethylhexylphosphoric acid was found to be ineffective.
The organic phase contained about 20 weight % mono-2-ethylhexyl-phosphoric acid. The feed solution had a free sulphuric acid concentration of 0.05 to 0.60 molar, corresponding to about 5 to 60 g/L H2S4 U.S. 3,883,634 (1975, ~eSchepper, et al) discloses extraction of germanium from acid solutions using hydroxyoximes.
The preferred extractant is one known as LIX 63* which contains as active ingredient in a hydrocarbon diluent the compound 5,~-di-ethyl-7-hydroxy-6-dodecanone oxime. The germanium extraction capacity increases with the acidity of the feed solution. In the examples quoted, the acidity ranges from 13U to 460 g/L H2S04. No information is given on the co-extraction of cadmium, antimony or indium.
U.S. 4,389,379 (1983, Rouillard, et al) discloses selective extraction of germanium from acidic solutions, contain-ing zinc and other species, with oxine derivatives, the one known commercially as Kelex 100** being preferred. In the only example * Trade Mar~ of Henkel Corporation ** Trade Mark of Sherex Chemical Company ~ 3 1 2 2 o 7 2278-2~l given which demonstrates selective germanium extraction in the presence of zinc, the acidity is quite high, at 150 g/L H2S04. A
disadvantage of the process claimed in this patent is that -the temperature of the stripping stage must be relatively high, at least 40C. The rate of disengagement of the aqueous and organic phases is inherently slow.
U.S. 4,432,951 (1984, DeSchepper, et al) discloses germanium extraction from acid solutions carried out at tempera-tures above 40C with substituted oxines, such as Kelex 100 or LIX 26*.
U.S. 4,432,952 (1984, DeSchepper, et al) discloses germanium extraction at low acidity with a mixture of an alpha-hydroxyoxime (e,g. LIX 63) and a substituted 8-hydroxyquinoline (e.g. Kelex 100 or LIX 26). This patent clearly states that the aqueous feed solution must be almost free of copper, otherwise the alpha-hydroxyoxime becomes poisoned. No information is given on co-extraction of zinc, cadmium, antimony, or indium.
U.S. 4,568,526 (1986, Rouillard, et al), a continuation of U.S. 4,389,379, discloses germanium extraction by means of an organic solid medium containing an oxine derivative.
U.S. 4,666,686 (1987, Krajewski, et al) discloses extraction of gallium, germanium or indium from basic or acidic solution with an organic phase containing at least Kelex 100 and LIX 26. The organic phase may also contain tri-n-octylphosphine oxide.
A. DeSchepper, in 'iLiquid-Liquid Extraction of Germanium by LIX 63" Hydrometallurgy, Vol. 1, 291-298 (1976) describes the * Trade Mark Henkel Corporation 1 3 1 2 2 0 7 2278-24l extraction of germanium with LIX 63 in the presence of various impurities. No information is given on the impurities cadmium, antimony or indium. In a second paper, "Liquid-Liquid Extraction of Germanium by LIX 63" Chloride Hydrometall. Proc. (Int. Symp.) 1977, 357-367, the same author describes germanium extraction with LIX 63. No information is given on the deportment of cad-mium, antimony or indium. These papers contain much the same data as U.S. patents 3,~83,634 and 4,432,~52, above.
G. Cote and D. Bauer, in !'Liquid-Liquid Extraction of Germanium with Oxine Derivatives" Hydrometallurgy, 5, 1~9~160, (19~0), describe a survey of ten germanium extractants. Of those surveyed, oxine derivatives were found to be among the most effi-cient. Di-2-ethylhexylphosphoric acid was found to be a poor extractant for germanium.
R. Tian, et al, in "New Technology for Indium, Germanium and Gallium Recovery in an Electrolytic Zinc Plant", Miner. Proc.
Extr. Metall., Pap. Int. Conf. 1984, 615-624, describe extraction of germanium with a mixture of di-2-ethylhexylphosphoric acid and YW 100. The latter extractant i5 not identified. A search of the Chemical Abstracts Service database using the Registry No. [94336-45-5] for YW 100 disclosed no other references to this extract-ant.
This invention is directed to a method for the recovery of germanium and, more particularly, is directed to a method for the selective recovery of germanium from acidic aqueous solutions by countercurrent liquid-liquid extraction.
Germanium may be present in intermediate products 1 31 2207 227~-24l obtained in the processing oF ores and metal concentra-tes. A
typical source of such intermediate products is in the processing of zinc sulphide ores to ohtain zinc metal by the electrol~sis route. Such intermediate products can be in the form of ger-manium-containing solutions or solid residues. The latter may be solubilized to give germanium-containing solutions. The ger-manium-containing solutions usually contain one or more of a large number of other metals.
Although the invention will be described with specific reference to solutions obtained from the sulphuric acid leaching of zinc-bearing intermediate products, it is understood that -the method of the invention is also suitable for the recovery of germanium from other germanium-containing solutions.
According to the invention, germanium is substantially separated from the other metal constituents in an aqueous feed solution which may also contain significant amounts of any of the following: sulphuric acid, zinc, arsenic, cadmium, antimony, indium, copper and iron (ferrous) in addition to germanium. Thus the method of this invention is suitable for the efficisnt extrac tion of germanium from acid solutions containing the following ranges of metallic species concentrations, expressed in g/L:
Ge 0.005 - 5 Sb 0.01 - 1 Zn 0.5 - 160 In 0.01 - 2 As 0.005 - 4 Cu 0.001 - 0.1 Cd 0.005 - 5 Fe 0.01 - 50 (as ferrous~
Briefly, this invention utilizes the following standard steps:
~ ~ 2~ 2278-241 (1) Contacting the aqueous feed solution in an extrac-tion s-tep with an organic phase containing an extractant;
~2) Separating the loaded organic phase containing the ma~or portion of the germanium from the aqueous extraction raffin-ate which is substantially depleted in germanium:
(3) Contacting the loaded organic phase in a scrubbing step with a scrub solution containing a mineral acid, such as sulphuric acid;
(4) Separating the scrubbed organic phase, containing sub-stantially all of the germanium, from the scrub raffinate;
(5) Contacting the scrubbed organic phase in a stripping step with an aqueous alkaline solution to transfer substantially all of the germanium into the strip liquor;
(6) Separating the stripped organic phase from the strip liquor which contains substantially all o~ the extracted Ge.
(7) Contacting the stripped organic phase with an acidic regen-erant solution to restore the organic phase to its original condition;
(8) Recycling the regenerated organic phase to the extraction step; and (9) Treating the strip liquor to recover a germanium product.
Each of the mixed phase contacting steps (i.e., steps (1), (3), (5) and (7)~ ~ay comprise several stages connected in series, with countercurrent flow of the aqueous and organic phases in each sta~e.
This extraction system is thus seen to follow, in its broad outlines, essentially conventional practice. This invention is primarily concerned with one of the most important features of this system, namely the composition of the organic extractant phase used in step (1).
We have now found that an efficient separation o~
germanium, ~rom an aqueous solution containing yermanium and other metal elements including at least one of zinc, arsenic, cadmium, antimony, indium, copper and errous iron, and which also may contain sulphuric acid, can be achieved by a multistage counter-current liquid-liquid extraction system wherein the organic phase comprises a solution of an alpha-hydroxyoxime and at least one alkyl phosphoric acid in a hydrocarbon diluent.
To this organic phase may also be added, if desired, conventional additives to suppress foam formation and -to suppress emulsion formation, thus aiding phase separa-tion.
Preferably, the alpha-hydroxyoxime is 5,8-diethyl-7-hydroxy-6-dodecanone oxime, which is available commercially under the designation "LIX 53" as a 70% by volume solution in a hydxo-carbon diluent.
The preferred alkylphosphoric acid is a 2-ethylhexyl-phosphoric acid. It is preferred to use di-2~ethylhexylphosphoric acid (D2EHPA), or, more preferably, a mixture of D2EHPA and mono-2-ethylhexylphosphoric acid (M2EHPA).
The amount of each of these reagents used in the organic phase depends to some extent on whether a single alkylphosphoric acid, for example D2EHPA~ is used, or whether a mixture is used.
When D2EHPA is used alone with LIX 63, then the organic phase suitably contains from about 20 to about 30, preferably ~rom 1312207 2278~
about 20 to about 25, volume percent LIX 63 and a relatively small amount of D2EHPA, of about 3 to about 10, preferably about 4 to about 5 volume percent, the remainder being hydrocarbon diluent, and modifier (if required).
When D2EHPA alone is used with LIX 63, suitable diluents include kerosene, aliphatic hydrocarbons (e.g., Isopar M*) and aromatic hydrocarbons (e.g., Solvesso 100*). With kerosene diluent, in the absence of modifiers, stable emulsions form during extraction when the organic phase is conditioned by methods C-l or C-2, (see below for explanation of conditioning methocls), or with dilute sulphuric acid (150 g/L H2S04). Acceptable rates of phase separation can be achieved with kerosene without using a modifier if the organic phase is conditioned by methods C-3 or C-4. With-out conditioning, satisfactory phase separation with kerosene can be obtained by addition of long-chain alkanol modifiers, for example, 5 to 20 volume % of either l-decanol or 2-ethylhexanol.
The formation of stable emulsions with unconditioned organic phase using kerosene diluent cannot be preven-ted by addition of dibutyl-butylphosphonate or tributylphosphate. With Isopar M diluent and conditioning methods C-l, C-2 or C-4, addition of alkanol modi~
fiers, for example, 5~to 20 volume % of either l-decanol or 2-ethylhexanol~ prevents formation of stable emulsions. With Solvesso 100 diluent and conditionin~ method C-2, an acceptable rate of phase separation is achieved without using a modifier.
The efficiency of germanium extraction is influenced by the nature of the diluent, the addition of modifiers and by the method used to condition the organic phase. When D2EHPA alone is used wi~h Trade MarX of Exxon Chemical _ 7 ~
227~-2~1 LIX 63, the preferred diluent is a subs-tantially alipha-tic hydro-carbon, such as Isopar M, with an alkanol modifier, l-decanol being preEerred. The preferred concen-tration of l-decanol in the organic phase is about 10 volume ~. Less preferably, a substan-tially aromatic hydrocarbon diluent, such as Solvesso 100, may be used without a modifier. The preferred conditioning method is either C-l or C-2.
When both M2EHPA and D2EHPA are used together with LIX 63, ~hen the organic phase suitably contains from about 20 to about 30, preferably from about 20 to about 25, volume per cent LI~ 63, together with a total of from about 1 to about 25 volume percent of the combined M2EHPA and D2EHPA. Preferably, the amount of M2E~PA is from about 1 to about 12, particularly from about 2 to about 10 volume percent. Similarly, preferably the amount of D2EHPA is from about 1 to 10, more particularly from about 2 to about 6 volume percent.
The remainder of the organic phase, which is combined with the extractants LIX 63, M2EHPA and D2EHPA, is a hydrocarbon diluent. Kerosene, Isopar M and Solvesso 100 have been found to be suitable diluents. Kerosene is the preferred diluent. ~o modifier is required provided the organic phase is suitably condi~
tioned prior to use. Rapid phase separation is obtained when the organic phase is conditioned by methods C-l, C-2 or C-3. There is no significant difference in Ge extraction efficiency with these three conditioning methods. It is preferred to use conditioning methods C-l or C-2 ~ith no modifier.
It is also to be noted that as LIX 63, as purchased, is a 70~ solution of oxime in hydrocarbon, the ~IX 63 also contri~
butes to the ~otal hydrocarbon amount. Thus 20 volume percent of LIX 63 corresponds to about 1~% of oxime, and 30 volume percent corresponds to about 21% of oxime. The hydrocarbon present in LIX
63 as purchased is alleged to be about 11% aromatic and about 49%
paraffinics, with about 40% naphthenes~
Process steps (1) through (8) as noted above may be carried out at any convenient temperature in the range of from 0C
(freezing, obviously, needs to be avoided) up to about 55C.
Unlike some of the reported procedures for germanium recovery, elevated temperatures are not necessary, and a preferred tempera-ture range is 20 - 40C; in other words, the system can be allowed to reach its own thermal balance essentially in a "room tempera-ture" environment.
Some broad consideration will now be given to the steps detailed above.
As regards apparatus, conventional mixer-settler units of an appropriate size are suitable, for each of the mixed phase contacting steps (i.e. steps (1), (3) (5) and (7)).
In step (3), scrubbing, a mineral acid i5 used as the scrub solution~ It is convenient to use the same acid as is present in the aqueous feed solution. As this is often a sul-phuric acid solution, for example in an electrolytic recovery plant, it is convenient to use sulphuric acid in this step.
Conveniently when using sulphuric acid the concentration is from 50 ~o 300 g/L, with a preferred range at 100 to 200 gjL. The presence of zinc sulphate in the scrub solution, for example at 30 to 70 g/L zinc, also can be tolerated.
The alkaline strip solution for the stripping step (5) is preferably a sodium hydroxide solution containing 20 to 250 g/L
NaO~. The optimum concentration range is 120 to 200 g/L NaOH~ A
similar potassium hydroxide solution may also be used for stripping.
Regeneration of the organic phase in step (7) is effected by contacting the stripped organic phase with an acidic regenerant solution. The regenerant solution should contain 50 to 250 g/L H2SO~, preferably 100 to 200 g/L. It may also contain a salt such as zinc sulphate or sodium sulphate. The preferred salt is zinc sulphate, to provide a Zn concentration in the regenerant solution of 40 to 100 g/L.
A germanium product may be obtained ~rom the strip liquor by known means. For example, the strip liquor may be neutralized with acid to precipitate solids which contain the germanium. These solids may then be ~iltered off, dxied, and sold as germanium concentrate, or they may be dissolved in hydrochloric acid to produce a solution from which GeC14 may be distilled, with the impurities remaining in the distillation residue. It i5 desirable for arsenic to be absent because of the dif~iculty in separating arsenic and germanium chlorides by distillation.
GeC14 may be converted to electronic-grade elemental Ge by known methods.
There are some surprising and unexpected benefits to be gained in the use of this invention~
A high acid concentration is not required in the aqueous t312207 feed solution. The aqueous feed may contain 50 to 150 y/L H2S04, and although a hiyher acid concentration will not be harmful, it is no~ necessary. Alpha-hydroxyoximes alone are known ex-tractants for germanium, as disclosed in U.S. patent 3,8~3,~34. The acid concentrations in the examples quoted in this patent are high, ranging from 130 to 460 g/L. It is known that ~IX ~3 is an effec-tive extractant Eor germanium only at higher acidities (~ 90 g/L
H2S04). When LIX 63 alone is used for germanium extraction, a significant amount of acid is co-extracted along with the german-ium, and the acid co-extraction increases with increasing acid concentration in the aqueous feed solution. The co-extracted acid may be partially removed by scrubbing the organic phase with water prior to stripping. If water scrubbing is not implemented, the extracted acid remains in the organic phase until the stripping stage is reached, where the acid is neutralized and the germanium is stripped with alkaline strip solution. This results in both a relatively low germanium concentration in the strip liquor, and a high consumption of alkaline strip solution, which increases process operating costs.
With the process of -this invention, it has surprisingly been found that addition of relatively minor proportions of M2EHPA
and D2EHPA, or of D2EHPA alone, to LIX 63 gave improved germanium extraction, even with a comparatively low acid concentration in the aqueous feed. This finding is especially interesting in view of the fact that D2EHPA by itself is reported to be a poor extrac-tant for germanium at low acidities and only becomes eEficient when the concentration of sulphuric acid in the feed solution exceeds several hundred grams per litre. In the present inven-tion, aside from a favourable overall reduction in acid consump-tion, relatively little acid is co-extracted. The need for water scrubbing is eliminated and also alkali wastage as, for example, sodium sulphate, in the stripping stage is minimized. Further, a higher germanium concentration is obtained in the strip liquor, which in turn greatly facilitates efficient recovery of a germanium product.
Another surprising feature o~ this invention is that alkyl esters oE phosphoric acid, including ~2EHPA and D2EHPA, are reported to extract both zinc and indium -from acidic aqueous phases. It was surprisingly found that zinc and indium extraction is suppressed when alpha-hydroxyoxime is used in combination with alkyl esters of phosphoric acid.
Additionally, it is reported that the efficient extrac-tion of germanium with alpha-hydroxyoximes alone requires a high extractant concentration in the organic phase, i.e. 70 to 100%.
In the case of LIX 63, 100~ means that the LIX 63 is used as pur-chased for the organic pha.se. In contrast, efficient germanium extraction is obtained in the present invention with considerably lower alpha-hydroxyoxime concentrations, leading to a favourable reduction both in extractant inventory, and in organic phase vis-cosity. Low viscosity enhances extraction kinetics, aids phase separation and reduces settler area requirements. A further benefit of lower extractant concentrations in the organic phase is less conversion of the oxime and alkyl esters of phosphoric acid to their corresponding alkali metal salt forms during the alkaline stripping step. The advantages of this are lower alkali consump-tion during stripping, less dilution o~ the germanium content in the strip liquor, lower acid requirement in regenerating the solvent and less production of waste sulphate salt during both stripping and regeneration.
In the Examples, which are set Eorth below, several different methods of conditioning -the fresh organic phase were used. In ~ach case, the organic phase was contacted with the indicated acidic solution(s) for about 15 minutes, and then separated therefrom prior to use in extraction. The four most fre~uently used methods were:
C-l Treatment with solution containing 150 g/L H2SO4 and 140 g/L
Na2SO~ . ~
C-2 Treatment with "return acid". So-called "return acid" is the solution remaining after electrowinning zinc from a zinc sulphate solution. Return acid contains about 150 g/L H2S04 and about 50 g/L Zn, present as ZnSO4, plus a range of other elements in varying amounts.
C-3 Two-stage treatment, the first stage consis-ting o~ treatment with "neutral" zinc sulphate electrolyte solution containing about 150 g/L Zn and having a pH of about 4.8, and the second stage consisting oP treatment with return acid.
C-4 Treatment with aqueous feed solution of specified composi-tion.
The main purpose of conditioning was to pre-load the organic phase with acid, to help ensure equilibration of the aqueous and organic phases during extraction. Another benePit of 1 31 2207 2z7~ 241 conditioning is -that it may remove undesired water-soluble impurities from the organic phase. As described previously, con-ditioning also had an impact on phase separation. In general it was found that conditioning methods employing solutions having a high ionic strength gave higher phase disengagement rates. Condi-tioning methods C-l and C-2 are preferred because the solutions used would be appropriate regenerant solutions in the regeneration step prior to extraction in a continuous process for germanium recovery from a sulphate-based zinc h~drometallurgical circuit.
LIX 63 was obtained from Henkel Corporation. One lot of LIX 63 was found to be impure, containing a small amount of aro-matic compounds, such as benzophenone oxime. This lot gave slower Ge extraction rates than pure lots. Pure LIX 63 was used in the Examples, except for Examples 1, 3 and 5, when the impure material was used.
The 2-ethylhexylphosphoric acid esters used in the Examples were obtained from several sources. The mono-ester M2EHPA is not available commercially in a pure state. It is always admixed with at least some di-ester, D2EHPA, and sometimes even with the tri-ester in small amounts. The M2EHPA used was obtained from Albright ~ Wilson, Ltd., Hodag Chemical Corporation, Stauffer Chemical Company and Pfaltz & Bauer, Inc., under names such as "OAP" (octyl acid phosphate), or "EHAP" (ethyl hexyl acid phosphate). As supplied, the material varies from lot to lot to a small de~ree. The material used in these Examples contained from about 54 to about 60% by volume of M2EHPA, and from about 40 to about 46% by volume D2EHPA~ The fact that M2EPHA is a mixture 1 3 1 2 2 0 7 2278-24l with D2EHPA is allowed for in the Examples when amounts of M2EHPA
and D2EHPA are given. Commercial-grade D2EHPA was obtained as a 97-98% pure liquid from Albright & Wilson, Ltd., and from AZS Corporation.
Kerosene, designated No. 3Cl-101-47, containing par-affins, naphthenes and about 15~ aromatic hydrocarbons (obtained from Shell Chemical Co.) was used in the Examples unless otherwise indicated. Isopar M, a diluent containing ~99% aliphatic hydro-carbons, and Solvesso 100, a diluent containing ~9~ aromatic hydrocarbons, were obtained from Exxon Chemical and Imperial Oil, Ltd., respectively.
l-Decanol was obtained from Exxon Chemical and C-I-L Inc. 2-Ethylhexanol was obtained from Fisher Scientific Co.
Dibutylbutylphosphonate and tributylphosphate were obtained from Albright & Wilson, Ltd.
~ eayent-grade ~aOH and NA2SO4 were used. Reagent-grade H2SO4 was used except where otherwise indicated.
Unless otherwise indicated, the tests described in the following Examples were conducted at room temperature.
Example 1 Extraction of Ge with LIX 63 Alone An organic phase consisting of, by volume, 25~ LIX 63 and 75~ kerosene, was conditioned by method C-l. The LIX 63 contained aromatic impurities. A portion of aqueous feed solution containing 0.63 g/L Ge and 75 g/L H2SO4 was contacted for 18 min-utes in a mixer unit with the conditioned organic phase at an organic phase to aqueous phase volume ratio of 1/1. After phase 1 3 1 2 2 0 7 2278-2~1 separation, the aqueous extraction raf-finate was analyzed and found to contain 0~34 g/L Ge. The organic phase was calculated to contain 0.29 g/L Ge corresponding to 46~ Ge extraction. Example 1-shows that LIX 63 by itself extracts Ge from solutions having relatively low acid concentrations, as expected.
Example 2 Extraction of Ge with D2EHPA Alone An organic phase consisting of, by volume, 5% D2EHPA and 95% kerosene, was conditioned by method C-l. A portion of aqueous feed solution containing 0.63 g/L Ge and 75 glL H2S0~ was contact-ed for 18 minutes in a mixer unit with the conditioned solvent at a phase volume ratio of l/l. Upon anal~sis of the aqueous extrac-tion raffinate, it was found that no Ge has been extractedO
Example 2 demonstrates that an organic phase containing D2EHPA by itself is ineffective for extracting Ge from sulphate solution containing a relatively low H2S04 concentration, in accordance with the teaching of U.S. patents 3,760,050 and 3,764,652.
Example 3 Extraction of Ge with Combined LIX 63 and D2~HPA
A series of tests was carried out using organic phases containing both LIX 63 and D2EHPA as combined extractants, to-gether with various diluents, modifiers and solvent conditioning methods. The LIX 63 contained aromatic impurities. The results are shown in Table l. In each test, aqueous feed solution con-taining 0.66 g/L Ge and 75 g/L H2S04 was contacted for 18 minutes in a mixer unit with conditioned organic phase at a phase volume ratio of 1/1. Organic phase composition is expressed in volume %.
Organic Phase Test Cond. Ge No. LIX 63 D2EHPA Diluent Modifier Method Extr'n _ _ _ _ 3(a) 25~ 5~ 70~ nil C-4 56%
3~b) 25% 5% kerosene nil C-3 60%
3(c) 20~ 4% Isopar M 2-ethyl- C-2 67 56% hexanol .
3(d) 25% 5% Isopar M l-decanol C-4 74%
60~ 10%
3(e) 25~ 5% Solvesso 100 nil C-2 83%
.
3(f) 25% 5% Isopar M l-decanol C-l 89%
_ 60% 10%
This Example shows that an organic phase containing a combination of LIX 63 and D2EHPA gives better Ge extraction than LIX 63 alone, although D2EHPA by itself does not extract Ge under the test conditions used, as is shown above in Example 2.
Example 3 also indicates that Ge extraction efficiency with com-bined L,IX 63 and D2EHPA is influenced by the nature oE the hydro-carbon diluent, by the addition of modifiers, and by the methodused to condition the organic phase. Higher Ge extraction was obtained with the diluents Isopar M (substantially aliphatic) and Solvesso 100 (substantially aromatic) than with kerosene. A
satisfactory rate o phase disengagement was observed in all the tests listed in Table 1. With kerosene or Solvesso 100, adequate phase separation was attained without addition of a modi-fier, provided the organic phase was properly conditioned prior to ex-traction. Conditioning methods C-3 and C-4 were suitable for kerosene, and method C-2 was suitable for Solvesso lO0. With Isopar M, using conditioning methods C-l, C-2 or C-4, addition of a modifier was necessary to prevent stable emulsions. The alkanol modifiers l-decanol and 2-e-thylhexanol both proved satisfactory.
Comparisons of Test 3(a) with 3(b) and 3(d) with 3(f) indicate that the conditioning method has an effect on the efficiency of Ge extraction. With kerosene diluent, C-3 appears preferable to C-4.
With Isopar M diluent in the presence of lO volume ~ l-decanol, C-l appears preferable to C-4. The highest Ge extraction efficiency was obtained with Isopar M diluent in the presence of 10 volume ~ l-decanol. Solvesso lO0 with no modifier was next best. It is believed that the relative ranking of the results shown in Table l was not substantially affected by the presence of small amounts of aromatic impurities in the LIX 63.
Example 4 Extraction of Ge with Combined D2EHPA and M2EHPA
An organic phase consisting of, by volume, 2.3% D2EHPA, 2.7~ M2EHPA and 95~ kerosene was conditioned b~ method C-l. A
portion of aqueous feed solution containing 0.63 glL Ge and 75 g/L
H2S04 was contacted for 18 minutes in a mixer uni-t with the con-ditioned organic phase at a phase volume ratio of 1/l. Extraction of Ge was 52%.
This result demonstrates that a mixture of M2EHPA and D2EHPA is capable of extracting Ge under relatively low acid conditions.
Example 5 Extraction of Ge with Combined LIX 63, D2EHPA and M2EHPA
, Portions of conditioned organic phase were prepared containing varying proportions of LIX 63, M2EHPA and D2EHPA, with Xerosene diluent. The LIX 63 contained aromatic impurities, Portions of an aqueous feed solution containing 0~590 g/L Ge and 75 g/L H2S04 were contacted with conditioned organic phase for 18 minutes in a mixer at an organic phase to aqueous phase volume ratio of l/l. The results for Ge extraction are given in Table 2.
~ . .
Test LIX 63 D2EHPA M2EHPA Kerosene Cond. Ge No. Vol. ~ Vol. % Vol. % Vol. % Method Extr'n . _____ . . .
5(a) 25 0.9 l.l 73 C-l 84%
5(b) 25 2.3 2.7 70 C-l 96%
5(c) 25 2.3 2.7 70 C-2 97%
5(d) 25 2.3 2.7 70 C-3 95%
5(e) 25 2 3 70 C-l 99%
5(f) 25 2 3 70 C-2 97%
5(g) 25 4.6 5.4 65 C-2 96%
5(h) 25 6.9 8.1 60 C-2 95~
5(i) 25 6 9 60 C-2 97%
5(j) 20 9 11 60 C-2 93%
. .__ _ . . . .
Example 5 shows that addition of M2EHPA -to the LIX 63- -D2EHPA extractant system provides highly efficient Ge extraction from relatively low-acid feed solution. Rapid phase separation was obtained with the three conditioning methods tested.
The conditioning method used had no significant effect on the overall efficiency of Ge extraction. It is noticeable that the ratio of the amount of LIX 63 (and thus by inference the -- lg --1 ~t 2~07 amount of actual oxime) to the total amount of phosphoric acid esters present does appear to influence the efficiency of extrac-tion of Ge. With 25 volume % LIX 63, optimum efficiency appears to be obtained at a LIX 63 to total phosphoric acid esters ra-tio in the region of 4 - 5 to 1, on a volume percent basis.
Example 6 Effect of Acid Concentration in Aqueous Feed Solution on Extraction of Ge,As,Cd, Sb and In with Combined LIX 63, D2EHPA and M2EHPA
Portions of aqueous feed solutions containing Ge, As, Cd, Sb, In and various concentrations of H2S04 were contacted with unconditioned organic phase by shaking them together for ~
minutes in separatory funnels. The organic phase contained, by volume, 25% LIX 63 2.3% D2EHPA, 2.7% M2EHPA and 70% kerosene. -This ratio of LIX 63 to total phosphate esters is thus in the range in which optimum Ge extraction (Cf Ex 5) can be expected~
The organic phase to aqueous phase volume ratio was 1/1, Phase separation was rapid. After phase separation, the extraction raffinates were analyzed. The concentrations of solutes in the organic phases were calculated from the raffinate analyses. The results are summarized in Table 3.
.
H2SO4 Solute Aqueous Raffinate Organic Test Conc. Feed Phase Phase Extraction No.g/L g/L g/L g/L
6~a)49.5 Ge 0.72 0.245 0.475 66 As 1.35 1.30 0.05 4 Cd 3.7 3.7 0.0 0 Sb 0.4 0.17 0.23 57 In 0.9 0.6 0.3 33 6(b)75 Ge 0.68 0.165 0.515 76 As 0.94 0.94 0.0 0 Cd 3.0 3.0 0.0 0 Sb 0.25 0.13 0.12 48 In 1.0 0.67 ~.33 33 6(c)125 Ge c=~ == 0.087 0.593 87 As 0.94 0.94 0.0 0 Cd 3.0 3.0 0.0 0 Sb 0.25 0.13 0.12 48 In 1.0 0.84 0.16 16 __ __ ,_ , 6(d)150 Ge 0.575 0.041 0.534 93 As 1.35 1.3 0.05 Cd 3.7 3.7 0.0 0 Sb 0.4 0.16 0.24 60 In 0.9 0.88 0.02 ;
This Example shows that Ge ex_raction with combined LIX 63, D2EHPA and M2EHPA improves with increasing acid concentra-tion in the aqueous feed solution. There is little or no ex-trac-tion of As and no extraction of Cd. Sb extraction is significan-t at all feed acid concentrations. Extraction from the aqueous phase of In ranged from moderate at low aqueous phase acid concen-tration, to very low at higher acid concentrations. This rela-tively low In extraction is particularly surprising in view of the fact that D2EHP~ by itself extracts In efficiently under the test conditions, as will be shown in Example 7. By comparing the extremely high In extraction efficiency obtained in Example 7 with - 21 ~
2278-2~1 the rather modest extraction in Example 6, it is evident that considerable suppression of In extraction can be achieved by suit-able selection of the organic phase composition. However it should also be noted, as can be seen from Exam~le 8, that the level of In extraction depends on the total amount of phosphate esters present: increasing their amount increases In extraction, although the total extracted is still not as high as the reportad capabilities of D2EHPA would suggest.
Example 7 Extraction of In with D2EHPA
A portion of aqueous feed solution containing 0.950 g/L
In and 146 g/L H2SO4 was contacted with an equal volume of uncon-ditioned organic phase containing, by volume, 5% D2EHPA and 95~
kerosene, by shaking for ~ minutes in a separatory funnel. Phase separation was slow. The extraction raffinate was found to con--tain 0.006 g/L In, corresponding to 0.944 g/L in the organic phase. The percent In extracted was thus ~ 99%.
Example 7 shows that D2EHPA by itself is a very effi-cient extractant for In under acid conditions, although phase separation is difficult. It is possible that addition of an alkanol modifier might assist in phase separation. It was later found that formation of stable emulsions could be prevented, with-out using a modifier, by conditioning the D2EHPA-kerosene organic phase by method C-l or C-2 prior to extraction.
2278~241 Example 8 Effect of Concentration of Extractants on Extraction of Ge, As, Cd, Sb and In -~ portion of aqueous feed solution containing Ge, ~s, Cd, Sb, In and 125 g/L H2SO4 was contacted with an equal volume of unconditioned organic phase containing, by volume, 30~ LIX 63, 4.6~ D2EHPA, 5.4% M2E~IPA and 60% kerosene, by shaking for 4 min~
utes in a separatory funnel. The results of the test are shown ln Table 4.
H2SO4 Solute Aqueous RaffinateOrganic Conc. Feed PhasePhaseExtraction g/L g~L g/L g/L
.. _ _ ..... ~ ..... _ 125 Ge 0.68 0.0470.633 93 As 0.94 0.9 0.04 4 Cd 3.0 3.0 0.0 0 ~b 0.25 0.14 0.11 44 In 1.0 0.21 0.79 79 The results in Example 8 are directly comparable with the results of Test 6(c) in Example 6, all the variables, except the organic phase composition, being the same in both tests.
Example 8 shows some improvement in Ge extraction and increased As extraction. Cd is not extrac-ted, as before. Sb extraction is slightly lower. Extraction of In increased greatly, possibly as a consequence of the total amount of phosphate esters being doubled (i.e. 5% in Ex. 6, 10% in Ex.8).
1 3 1 2207 2278-~41 Exa~ple g Selective Ge Extraction in the presence of Zn, As, Cd, Sb, In, Cu and Fe (II) To simulate a continuous multistage extraction, an aqueous feed solution containing, (in g/L), ~2~4 75, Zn 41, Ge 0.68, As 0.94, Cd 3.0, Sb 0.25, In 1.0, Cu 0.011 and Fe (II) 34.7, was subjected -to batch countercurrent 3-stage 5-cycle extraction as described in the Fifth ~dition (1973) of "Chemical Engineers' Handbook", (McGraw-Hill BooX Company) Section 15, page 15. The fresh organic phase was not conditioned, and contained, by volume, 25~ LIX 63, 2.3~ D2EHPA, 2.7% M2EHPA and 70~ deodorized kerosene (obtained from J.T. Baker Chemical Co.). The organic to aqueous phase volume ratio was 1/1. Separa-tory funnels were used, with a shaking time of 4 minutes. The resulting organic phase con~
tained, (in g/L), Ge 0.68, Cd 0.14, Sb 0.15 and In 0.90. Ex-trac-tion of Zn, As, Cu and Fe was insignificant. This organic phase was then subjected to 9 successive contacts with fresh port-ons of the aqueous feed solution using a separatory funnel with a shaking time of 4 minutes for each contact, and an organic to aqueous phase volume ratio of 1/1. The 9 aqueous raffinates were analyzed and the composition of the organic phase after each contact was calculated. There was no significant transfer of Zn, As, Cu or Fe to the organic phase. The results for Ge, Cd, Sb and In are shown in Table 5.
1 3 ~ 2 2 0 7 2278-241 Raffinate PhaseOr~anic Phase (g/L) (g/L) Ge CdSb In Ge Cd Sb In Initial Organic Phase - - - - 0.68 0.14 0.15 0.90 After Contact " " ~o. 1 0.110 3.13 0.130 l.O0 1.25 0.01 0.27 0.9 " " No. 2 0.130 3.01 0.129 1.04 1.80 0 0.39 0.86 " " No. 3 0.150 3.00 0.130 1.04 2.33 0 0.51 0.82 " " ~o. ~ 0.160 3.00 0.132 1.04 2.85 0 0.63 0.78 " " No. 5 0.160 3.00 0.159 1.125 3.36 0 0.72 0.655 " " No. 6 0.165 3.00 0.169 1.05 3.865 0 0~81 0.605 " " ~o. 7 0.205 3.00 0.162 1.025 4.33 0 0.90 0.58 " " No . 8 0.205 3.00 0.162 1.025 4.795 0 0.9g 0.555 " " No. 9 0.245 3.00 0.162 1.05 5.22 0 1.07 0.505 Example 9 indicates that the Ge loading capacity of the solvent is surprisingly high, and at 5.2 g/L Ge has still not reached its maximum capacity. The Cd initially present in the organic phase was selectively and completely removed by contact with the aqueous feed solution. Sb continued to be extracted in nearly constant increments during each contact. The selectivity ratio for Ge extraction over Sb extraction is estimated to be between 3.2 and 5.5 under the conditions of this test. The In content of the organic phase steadily declined during repeated contacts, indicating that it would be possible to minimize In extraction through careful selection of the organic to aqueous phase volume ratio and the number countercurrent of extraction stages.
Exam~le 10 Reductlon of Cu and Ferric Iron Content in Aqueous Feed Solution The organic phase of this invention was found to be capable of extracting a significant amount o~ Cu and ferric iron 2278-24~
from acidic aqueous solutions if the concentrations of these species are sufficiently high. For feed solutions containing more than 0.03 g/L Cu and 0.10 g/L ferric iron, the ~ollowing steps were taken. The feed solution was heated to 90C, lead sulphide concentrate was added in the amount of 2 to 3 g for every gram of ferric iron present per litre of solution, and the mixture was agitated for 30 minutes. Then iron grit was added, 1.5 g per litre of solution, and the agitation was continued for a further 15 minutes. Upon cooling and separation of the solids, the H2SO~
concentration was adjusted as required to provide a feed solution suitable for Ge extraction. Using this procedure on a particular batch of solution, the Cu concentration was lowered from 0.105 g/L
to 0.011 g/L and the ferric iron concentration was lowered from 4.2 g/L to virtually zero. The ~errous iron concentration in-creased from an initial value of 29.0 g/L to a final value of 34.7 g/L. Since As was also present in the solution, precautions were taken to deal with ~ossible arsine generation, ~owever no arsine was observed. Example 10 demonstrates an efficient and inexpensive means of lowering the copper and ferric lron concen-trations in the aqueous feed to manageable levels prior to liquid-liquid extraction.
Example 11 Scrubbin~ of the Loaded Organic Phase Following the extraction step, Cd and In are selectively removed from the loaded organic phase by scrubbing with an acidic aqueous solution.
In one case, the organic phase used for extraction 1 3 1 2 2 0 7 227~-241 contained, by volume, 30% LIX 63, 4~6~ D2EHPA 5.4% M2E~PA and 60 kerosene. After extraction, the solu-te concentrations in the loaded organic phase were: Ge Q.68 g/L, Cd 0.27 g/L, Sb 0.15 g/L
and In 0~99 g/L. Scrubbing was carried out by shaking the loaded organic phase with an equal volume of dilute H2S04 (50 g/L) for ~
minutes in a separatory funnel. Phase separation was rapid. The scrub raffinate was analyzed and the solute concentrations in the scrubbed organic phase were calculated to be: Ge 0.664 g/JJ, Cd 0.134 g/~, Sb 0.150 g/L and In 0.984 g/L. Scrubbing removed a substantial amount of Cd from the loaded organic phase, however, In removal was insignificant. No Sb was removed.
In a second case, the organic phase used for extraction contained, by volume, 25% LIX 63, 2.3% D2EHPA, 2.7% M2EHPA and 70%
kerosene. A~ter extraction, the solute concentrations in the loaded organic phase were: Ge 0.68 g/L, Cd 0.25 g/L, Sb 0.145 g/L
and In 0.75 g/L. Scrubbing was carried out as described in the first case, except that the scrub solution consisted of return acid. Rapid phase separation was obtained. The soLute concen-trations in the scrubbed organic phase wQre found to be: Ge 0~674 20 g/L, Cd 0.060 g/L, Sb 0.141 g/L and In 0.32 g/L. Thus, a higher acid concentration in the scrub solution improved the Cd removal even further and gave, in addition, substantial In removal. Very little Sb was removed.
Example 11 shows that co-extracted Cd and In can be selectively scrubbed from the loaded organic phase with return acid.
Example 12 Stripping Ge and Sb from the ~crubbed Organic Phase Following the scrubbing step, Ge and Sb are stripped from the organic phase wi~h an aqueous alkaline strip solution.
Two-stage stripping was tested, at two temperatures, 20C and 55C. Ex~raction of an aqueous feed solution was carried out with organic phase containing, by volume, 25~ LIX 63, 2.3~ D2EHPA, 2.7%
M2EHPA and 70~ kerosene. The resulting loaded organic phase was scrubbed with return acid. The organic phase, after scrubbing, contained: Ge 0.666 g/L, Sb 0.116 g/L and In 0.320 g/L.
In a stripping test at 20C, a portion of the scrubbed organic phase was contacted with fresh aqueous strip solution containing 200 g/L NaOH, in a beaker agitated with a magnetic stirrer. The organic to aqueous phase volume ratio was 2/1. After 4 minutes of stirring, the resulting emulsion was transferred to a separatory funnel and the phases were allowed to disengageO The aqueous phase, or first strip liquor, was analyzed. The composi-tion of the organic phase, or "first stripped organic phase", was calculated by difference. The first stxipped organic phase was then subjected to a second stage of stripping, using fresh strip solution, under the same conditions as in the first stage. The resulting aqueous phase, or "second strip liquor", was analy~ed, and the composition of -the stripped organic phase, or "second stripped organic phase" was calculated. The results are shown in Table 6.
A second stripping test was carried out at 55C, in a manner similar to the preceeding test, but with the ~ollowing - 2~ -differences in procedure. The organic phase and strip solution were separately preheated to 55C, then contacted in a beaker on a stirring hot plate at 55C, and finally the emulsion was trans-ferred to a separatory funnel placed in a water bath at 55C for phase disengagement. The results are shown in Table 60 First Strip First Stripped Stripping Liquor (g/L)Organic Phase (g/L) % Stripped Temp.
_ Sb In Ge Sb In Ge Sb In- - - - _ _ _ _ 20C1.100 ~.202 0.180 0.116 0.015 0.230 83~ 87% 28 55C1.150 0.199 0.031 0.091 0.017 0.304 86% 85~ 5%
Second Strip Second Stripped Total Liquor (g/L)Organic Phase (g/L) ~ Stripped Ge Sb InGe Sb In Ge Sb In 20C0.065 0.031 0.0350.083 0.0 0.212 87% 100~ 34%
55C0.038 0.021 0.0230.072 0.007 0.292 89% 94% 9%
A white amorphous precipitate formed in the first stage of stripping at both temperatures. The amount formed at 55C was less than at 20C. X ray analysis showed that the precipitate consisted of In(OH)3. Formation of troublesome amounts of the precipitate can be avoided by minimizing In co-extraction. Phase separation was rapid at both temperatures.
Example 12 shows that Ge and Sb can be efficiently stripped from the scrubbed organic phase by means of 2-stage alkaline stripping. In is partially stripped. Raising the stripping temperature from 20C to 55C has only a slight ef~ect on Ge and Sb stripping. Substantially less In is stripped at 55C than at 20C.
Example 13 Continuous Pilot-Scale Test ~ 58-hour continuous test including extraction scrubbing, stripping and solvent regeneration was carried out using small pilot scale equipment. The total volume of aqueous feed treated was 105 litres~ To prepare the aqueous feed, zinc plant leach solution was treated as described in ~.xample lO to lower the Cu and ferric iron content. The resulting aqueous feed had the following composition, expressed in g/L:
H2SO4 llO As 0.545 In 0.~40 Zn 85 Cd 0.940 Cu 0.006 Ge 0.590 Sb 0.195 Fe 15 (as ferrous) The organic phase contained, by volume, 25~ LIX 63, 2.1~ D2EHPA, 2.9~ M2EHPA and 70% kerosene. The organic phase was initially conditioned with return acid (method C-2). In the extraction step, the aqueous feed was contacted countercurrently with the organic phase recycled from solvent regeneration in 3 series-connected mixer/settlers, at an organic phase to aqueous phase volume ratio of l/3. In the scrubbing step the loaded organic phase was contacted countercurrently with scrub solution in 3 series-connected mixer/settlers at an organic phase to aqueous phase volume ratio of l/l. The scrub solution, comprising return acid fortified with technical grade 93% H2S04, contained about 50 g/L Zn and 200 g/L H2S04. In the stripping step, the scrubbed organic phase was contacted countercurrently with strip solution in 3 series-connected mixer/settlers at an organic phase 1312~07 2278-241 to aqueous phase volume ratio of 5/1. The strip solution con-tained 200 g/L NaOH. In the organic phase regeneration step, the stripped organic phase was contacted with regenerant solution in one mixer/settler at an organic to aqueous phase volume ratio of 1/1. The regenerant solution comprised return acid. Regenerated organic phase was recycled to the extraction step. In all the mixer/settlers the appropriate phase was recycled in order to maintain an organic phase to aqueous phase volume ratio of close to one in each mixer. The organic phase made about 5 cycles through the equipment during the course of the test. The raffin-ates, strip liquor and regenerated organic phase were analyzed.
The solute concentrations in the loaded organic, scrubbed organic and stripped organic phases were calculated by difference. The Ge, Sb and In concentrations are given in Table 7.
1 3 1 2207 2278-24l Table 7 Ge Sb In ~/L g/L g/L
ExtractionIn Aqueous Feed 0.590 0.195 0.940 Regenerated Organic 0.040 0.065 0.001 Out Extraction Raffinate 0.030 0.01~ 0.925 Loaded Organic 1.720 0.596 0.046 ScrubbingIn Scrub Solution 0 0 0 Loaded Organic 1.720 0.596 0.046 Out Scrub Raffinate 0.025 0.038 0.043 Scrubbed Organic 1.695 0.558 0.003 StrippingIn Strip Solution 0 0 0 Scrubbed Organic 1.695 0.558 0.003 Out Strip Liquor 14.00* 0.830* 0.008*
Stripped Organic 0.041 0.195 0.002 Regeneration In Regenerant Solution 0 0 0 Stripped Organic 0.041 0.19S 0.002 Out Regeneration ~affinate 0.001 0.130 0.001 Regenerated Organic 0.040 0.065 0.001 * These values were higher than expected, due to volume reduction of the aqueous phase.
The recovery of Ge was excellent. About 95~ of the ~e in the aqueous feed was extracted. The loss of Ge in scrubbing was very low. About 9~ of the Ge in the loaded organic was stripped. The deportment of Sb was more complex. About 91% of the Sb entering the extraction step was co-extracted. About 6% of the Sb in the loaded organic reported to the scrub raffinate, 16%
reported to the strip liquor, 44% precipitated in the stripping mixer/settlers as a white precipitate containing sodlum antimon-ate, 23~ reported to the regeneration raffinate, and 11~ remained in the regenerated organic phase. The sodium antimonate precipi-tate did not impede phase separation. Less than 2% of the In in the aqueous feed was co-extracted. Of the extracted In, 93~ was removed from ~he organic phase during scrubbing. There was no significant co~extraction of 2n, As, Cd, Cu and Fe.
Example 13 shows that an organic phase including a LIX 63-D2EHPA-M2EHPA mixed extractant provides efficient and selective Ge extraction from solutions containing a variety of other metal ions. The selectivity with respect to Sb is lower than with other species; but is still more than adequate. The formation of an antimony-containing precipitate in the stripping stage is not a serious problem. The precipitate could be easily removed by settling, filtering or centrifu~ing or other known methods, or by a combination of these methods. Although scrubbing and organic phase regeneration were carried out at an organic phase to aqueous phase volume ratio of 1/1 for convenience during the test, this ratio could be raised to 5/1 in bo-th of these steps.
Note In the preceding discussion, and in the following claims, terms are used to describe various esters of orthophos-phoric acid, H3PO4. Whilst proper schematic names for these com-pounds, according to the I.U.P.A.C. Rules, exist they are not used in commercial practice. To avoid any doubt as to the nomenclatur~
used herein, the following definitions are provided; in each of them the group R is an alkyl group, for example the 2-ethylhexyl group referred to extensively herein.
~ ~ 1 2 ~ ~ 1 2278-241 I RO
HO - P = O : Monoalkylphosphoric acid HO
II RO
RO - P = O : Dialkylphosphoric acid HO /
III RO
RO - P = O : Trialkylphosphate RO
Claims (42)
1. A method for the separation of germanium, from an aqueous acid-containing feed solution containing germanium and other dissolved metal elements including at least one metal chosen from the group consisting of zinc, arsenic, cadmium, antimony, indium, copper, and ferrous iron, which process utilizes multi-stage countercurrent liquid-liquid extraction, comprising using as the organic phase a solution of an effective amount of an alpha-hydroxyoxime together with an effective amount of at least one alkylphosphoric acid in a hydrocarbon diluent.
2. A method according to claim 1, wherein the alpha-hydroxyoxime is 5,8-diethyl-7-hydroxy-6-dodecanone oxime.
3. A method according to claim 2, wherein the alkylphosphoric acid is di-2-ethylhexyl-phosphoric acid.
4. A method according to claim 3, wherein the hydrocarbon diluent is either a mainly aliphatic hydrocarbon mixture or a mainly aromatic hydrocarbon mixture.
5. A method according to claim 4, wherein the hydrocarbon diluent is a mainly aliphatic hydrocarbon mixture.
6. A method according to claim 5, wherein the organic phase further contains a modifier chosen from long chain alkanols, having a straight or branched chain.
7. A method according to claim 6, wherein the modifier is 1-decanol.
8. A method according to claim 4, wherein the hydrocarbon diluent is a mainly aromatic hydrocarbon mixture.
9. A method according to claim 1, wherein the alkyl phosphoric acid is a mixture of mono- and di- alkyl phosphoric acids.
10. A method according to claim 9, wherein the mixture of alkyl phosphoric acid comprises a mixture of mono- and di-2-ethylhexyl-phosphoric acids.
11. A method according to claim 10, wherein the hydrocarbon diluent is one of the members of the group comprising kerosene, mainly aliphatic hydrocarbon mixtures and mainly aromatic hydrocarbon mixtures.
12. A method according to claim 11, wherein the hydrocarbon diluent is kerosene.
13. A process for the separation of germanium from an aqueous sulphuric acid containing feed solution containing germanium and other dissolved metal elements including at lease one metal chosen from the group consisting of zinc, arsenic, cadmium, antimony, indium, copper, and ferrous iron, which process utilizes multi-stage countercurrent liquid-liquid extraction, comprising using as the organic phase a solution in a hydrocarbon diluent of an effective amount of 5,8-diethyl-7-hydroxy-6-dodecanone oxime together with an effective amount of a phosphoric acid chosen from either di-2-ethyl-hexylphosphoric acid or a mixture of mono- and di-2-ethyl-hexylphosphoric acids.
14. A process according to claim 13, wherein the phosphoric acid is di-2-ethylhexylphosphoric acid (D2EHPA).
15. A process according to claim 14, wherein the organic phase contains, in volume percentages, from about 14% to about 21% of oxime, from about 3% to about 10% of D2EHPA, the remainder being hydrocarbon diluent.
16. A process according to claim 14, wherein the organic phase contains, in volume percentages, from about 14% to about
17% of oxime, from about 4% to about 5% of D2EHPA, the remainder being hydrocarbon diluent.
17. A process according to claim 14, wherein the hydrocarbon diluent is either substantially aliphatic or substantially aromatic.
17. A process according to claim 14, wherein the hydrocarbon diluent is either substantially aliphatic or substantially aromatic.
18. A process according to claim 17, wherein the hydrocarbon diluent is substantially aliphatic.
19. A process according to claim 18, wherein the organic phase further contains a modifier chosen from long chain alkanols having a straight or branched chain.
20. A process according to claim 19 wherein the modifier is 1-decanol.
21. A process according to claim 17, wherein the hydrocarbon diluent is substantially aromatic.
22. A process according to claim 13, wherein the phosphoric acid is a mixture of mono-2-ethylhexylphosphoric acid (M2EHPA) and di-2-ethylhexylphosphoric acid (D2EHPA).
23. A process according to claim 22, wherein the organic phase contains, in percentages by volume, from about 14% to about 21% of oxime, from about 1% to about 25% of M2EHPA and D2EHPA combined, the remainder being hydrocarbon diluent.
24. A process according to claim 22, wherein the organic phase contains, in percentages by volume, from about 14% to about 21% of oxime, from about 1% to about 12% of M2EHPA, and from about 1% to about 10% of D2EHPA, the remainder being hydrocarbon diluent.
25. A process according to claim 22, wherein the organic phase contains, in percentages by volume, from about 14% to about 17% of oxime, from about 2% to about 10% of M2EHPA, and from about 2% to about 6% of D2EHPA, the remainder being hydrocarbon diluent.
26. A process according to claim 22, wherein the hydrocarbon diluent is one of the members of the group comprising kerosene, substantially aliphatic hydrocarbon mixtures and substantially aromatic hydrocarbon mixtures.
27. A process according to claim 26, wherein the hydrocarbon diluent is kerosene.
28. An organic phase for use in a multi-stage countercurrent liquid-liquid extraction process for the separation of germanium from an aqueous acid solution containing germanium and at least one metal selected from the group consisting of zinc, arsenic, cadmium, antimony, indium, copper and ferrous iron comprising a solution in hydrocarbon diluent of an effective amount of 5,8-diethyl-7-hydroxy-6-dodecanone oxime together with an effective amount of a phosphoric acid chosen from either di-2-ethylhexylphosphoric acid, or a mixture of mono-2-ethylhexylphosphoric acid and di-2-ethylhexylphosphoric acid.
29. An organic phase according to claim 28, wherein the phosphoric acid is di-2-ethylhexylphosphoric acid (D2EHPA).
30. An organic phase according to claim 29, containing, in percentage by volume, from about 14% to about 21% of oxime and from about 3% to about 10% of D2EHPA.
31. An organic phase according to claim 29, containing, in percentage by volume, from about 14% to about 17% of oxime and from about 4% to about 5% of D2EHPA.
32. An organic phase according to claim 29, wherein the hydrocarbon diluent is either substantially aliphatic or substantially aromatic.
33. An organic phase according to claim 32, wherein the hydrocarbon diluent is substantially aliphatic.
34. An organic phase according to claim 33, further containing a modifier chosen from long chain alkanols having a straight or branched chain.
35. An organic phase according to claim 34, wherein the modifier is 1-decanol.
36. An organic phase according to claim 32, wherein the hydrocarbon diluent is substantially aromatic.
37. An organic phase according to claim 28, wherein the phosphoric acid is a mixture of mono-2-ethylhexylphosphorio acid (M2EHPA) and di-2-ethylhexylphosphoric acid (D2EHPA).
38. An organic phase according to claim 37 containing, in percentage by volume, from about 14% to about 21% of oxime, and from about 1% to about 25% of phosphoric acid, the remainder being hydrocarbon diluent.
39. An organic phase according to claim 37 containing, in percentage by volume, from about 14% to about 21% of oxime, from about 1% to about 12% of M2EHPA, and from about 1% to about 10% of D2EHPA, the remainder being hydrocarbon diluent.
40. An organic phase according to claim 37 containing, in percentage by volume, from about 14% to about 17% of oxime, from about 2% to about 10% of M2EHPA, and from about 2% to about 6% of D2EHPA, the remainder being hydrocarbon diluent.
41. An organic phase according to claim 37, wherein the hydrocarbon diluent is one of the members of the group comprising kerosene, substantially aliphatic hydrocarbon mixtures and substantially aromatic hydrocarbon mixtures.
42. An organic phase according to claim 41, wherein the hydrocarbon diluent is kerosene.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000548084A CA1312207C (en) | 1987-09-29 | 1987-09-29 | Recovery of germanium from aqueous solutions by solvent extraction |
| US07/237,742 US4915919A (en) | 1987-09-29 | 1988-08-29 | Recovery of germanium from aqueous solutions by solvent extraction |
| EP88308263A EP0313201A1 (en) | 1987-09-29 | 1988-09-07 | Recovery of germanium from aqueous solutions by solvent extraction |
| JP63224866A JPH01122925A (en) | 1987-09-29 | 1988-09-09 | Recovery of germanium from aqueous solution by solvent extraction |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000548084A CA1312207C (en) | 1987-09-29 | 1987-09-29 | Recovery of germanium from aqueous solutions by solvent extraction |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1312207C true CA1312207C (en) | 1993-01-05 |
Family
ID=4136544
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000548084A Expired - Lifetime CA1312207C (en) | 1987-09-29 | 1987-09-29 | Recovery of germanium from aqueous solutions by solvent extraction |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1312207C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111206149A (en) * | 2020-03-04 | 2020-05-29 | 北京高能时代环境技术股份有限公司 | Method for centrifugal extraction of germanium |
| CN112662899A (en) * | 2020-12-10 | 2021-04-16 | 衢州华友钴新材料有限公司 | Method for selectively extracting and separating germanium from high-arsenic high-silicon sulfate solution by using Lix-63-based multi-element synergistic extraction system |
-
1987
- 1987-09-29 CA CA000548084A patent/CA1312207C/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111206149A (en) * | 2020-03-04 | 2020-05-29 | 北京高能时代环境技术股份有限公司 | Method for centrifugal extraction of germanium |
| CN112662899A (en) * | 2020-12-10 | 2021-04-16 | 衢州华友钴新材料有限公司 | Method for selectively extracting and separating germanium from high-arsenic high-silicon sulfate solution by using Lix-63-based multi-element synergistic extraction system |
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