DE2810281A1 - METHOD FOR SELECTIVE EXTRACTION OF METALLIONS FROM AQUEOUS SOLUTIONS AND EXTRACTION AGENTS SUITABLE FOR THIS - Google Patents

Description

Dr. F. Zumstein $ -eri. - Dr. E. Assmarm - Or. R. ICoenigsberger Dipl.-Phys. R. Holzbauer - ΰΐρί.-ing. K KSingseSsen - Dr. F. Zunpstein | un.

PATENT LAWYERS 28IU28

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Stamicarbon B.V., Geleen, The Netherlands

Process for the selective extraction of metal ions from aqueous solutions and suitable extraction agents

The invention relates to a process for the selective extraction of metal ions belonging to groups IB, IIB, IIIB, IVB, ¥ B, VIB, VIIB and VIII of the periodic table from an aqueous solution of the same with the aid of an organic medium.

Such processes are used on an industrial scale in the extraction of metals from ores. The metals are introduced into an aqueous solution, after which the desired metal ions are extracted from the solution. In addition, this process is also used in the recovery of metals from waste streams that arise, for example, in the galvanic industry, catalyst processing, etc.

Several substances are known as isolating agents, such as thiobenzoylmethane dissolved in benzene or chloroform, which is used together with a pyridine derivative for the extraction of nickel. Pyrophthalone or 5-nitropyrophthalone can be used for the extraction of Ca _{9 Ni and Co.} In addition, many extractants based on an α or ß-Hydroxoxyoxime are known. A characteristic of these substances is that they have a high level of usage

Require expense and furthermore that several of these substances are undesirable have toxic properties.

The object of the present invention is now to provide a low-cost, non-toxic and simple extraction agent.

Surprisingly, it was found that selective extraction of metal ions from a solution thereof wasserigen is possible, if one carries out the extraction with an extraction agent based on an unsaturated fatty acid or a mixture of unsaturated fatty acids. This extraction is preferably carried out with one or more unsaturated aliphatic carboxylic acids. However, a mixture has the advantage that at least 50% consists of oleic acid and the rest, for example, of linoleic and / or linolenic acid. In addition to the constituents mentioned, the fatty acid or the fatty acid mixture can also contain an amount of saturated fatty acids, as is the case in particular with oleic acid of technical quality.

In a particular embodiment of the present invention, the above-mentioned extractant is still an amount of oxime, e.g. (Cyclo) aliphatic oxime and especially cyclohexanone oxime added. The weight ratio between fatty acid and oxime is preferably between J and 50.

Adding an oxime to the extractant has an impact on the 'partition coefficient'. This term is used in the following: ■ Text of this application the ion concentration of a particular metal in the organic medium divided by the ion concentration of the same metal in the Water phase, understood after equilibrium has been established. The oxime has a positive effect on the selectivity; also the separation between the organic and the aqueous phase improved after extraction.

A pH in the range between 4 and 9 is preferably used for the extraction of metal ions from aqueous solutions. Especially Cu ions and Ni ions go mostly into the at a pH value between 5.5 and 9 organic medium over while at a pH between 4 and 5.5 mainly Cu ions pass into the organic medium. In a strongly acidic medium, i.e. at pH values below approx. 2, all metal ions go back into the water phase, so that the organic medium is then almost completely free of metal ions is. This circumstance will be used in the practical implementation of the

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must make use of the present procedure.

The pH value during the extraction is not critical and per se

is largely determined by the extractants used and the ones to be extracted Metal ions conditional. The exact value can only be determined experimentally after the extraction agent has been selected. With regard to the fatty acid reactions is a pH above 8 is not recommended.

The extraction process is usually carried out at room temperature; however, the temperature of the various liquids also plays a role here. The minimum value is generally determined by the viscosity of the organic medium, which must not be too high. On the other hand, the temperature must not rise too high in order to avoid one of the Components evaporated too much. Of course, the choice of temperature also influences the kinetics of the extraction and the separation between the organic and the aqueous phase after extraction.

The invention also covers the extractants used in this process. The extractants can be used as such or in the form of a Solution can be used. As the solvent, the usual, essentially non-polar solvents such as kerosene, hexane, isobutane, perchlorethylene or special solvents developed for extraction agents. Use less non-polar solvents such as methyl isobutyl ketone and the like is also possible, without that anything has an unfavorable effect on the extraction. The solvent consumption increases in this case because the solvents dissolve in the water phase. An extractant that is per liter is preferred of 5-40 g of cyclohexanone oxime, 20-250 g of fatty acid mixture, essentially consisting of oleic acid, and also mainly of non-polar solvents composed.

The weight ratio between fatty acid and oxime can be between \ and 50. These values relate to extractants with such an oxime content that the oxime has a significant effect on the selectivity of the extraction. However, it is possible that with certain compositions of the extractants, in which only fatty acids are assumed, the phase separation does not proceed as well after the extraction. In such a case, this phase separation can be significantly improved by adding a small amount of oxime to the fatty acid. There can be a weight ratio between fatty acid and oxime

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fc

in the order of 50 to a good 500.

The advantage of using the extraction agents according to the invention is to be seen in particular as the fact that simple, less valuable chemical compounds can be used, the toxicity of which is usually lower than that of the known extraction agents. In addition, especially with nickel ions, the extraction rate is higher than with other known extraction agents, where it is generally low.

The process according to the invention and the extraction agents according to the invention are extremely suitable for the selective extraction of Cu and Ni ions from aqueous solutions in which there are also Cr and Zn ions .

The invention is explained with reference to a drawing. It shows:

1 shows an embodiment of the inventive method for separating for example from the electroplating industry stemming Fe, Ni, Zn, and Cu ions by means of fatty acids and oxime.

Fig. 2 is essentially the same embodiment, in which an additional concentration and purification step is provided for Ni ions;

Is removed in the present invention with the use of extracting agents, the pH versus the ratio of the distribution coefficients of Cu and Ni ion between the organic and the aqueous phase Fig. 3 is a graph.

The present invention is not limited to this embodiment .

Based on F.ig. 1 describes a method for separating Fe, Cu, Ni, Zn and Cr. The following scheme provides a brief description. It is then assumed that a mixture of solid hydroxides of the metals mentioned.

-A-

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Hydroxides of Fe, Cr, Cu, Ni, Zn dissolved in acid (pH 2-3)

! solid Fe + Cr hydroxides I

Cu, Ni, Zn, Cr aqueous solution

Extraction (pH: 5.5-8)

Cu, Ni (organic phase) extraction (pH: -2 - +1) Cu, Ni (water phase) Extraction (pH: 4-5.5)

Cr , Zn j Cr (OH) Jj Zn ions in

aqueous solution

Cu (org.)

INi (watery)

Extraction (pH: -2 - +1)

j Cu (aqueous)

1 shows a device which essentially consists of a solution vessel A and 4 'mixer-settler' units B, C, D and E. See for a description of such a combination of mixing and settling vessels the journal Chemical Engineering of January 19, 1976, pages and 97. However, other apparatus suitable for extraction purposes can also be used can be used, such as a pulsation column. A representation of this type of extraction column can be found in the Dutch patent specification 123.177.

A quantity of solid material is introduced into A through line 1, which consists of a mixture of Fe, Cr, Zn, Ni and Cu hydroxides. So much acid, e.g. sulfuric acid, enters through line 2 that the pH adjusts to a value between 2 and 3, whereby Cu, Ni and Zn ions pass into the dissolved form together with some of the Cr ions. The remaining solid, essentially Fe hydroxide, is used for further Processing drained through line 3. The resulting acidic solution containing Cu, Zn, Cr and Ni ions becomes the mixture part through line 4 the unit B supplied. Through line 5, an organic phase originating from unit C enters, which consists of a solution of cyclohexanone oxime and

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a mixture of fatty acids in hexane. This fatty acid is commercially available under the name 'technical oleic acid ¹ '. Sufficient lye is added through line 6 so that the pH adjusts to a value between 5.5 and 5.5. As a result, the Cu and Ni ions are absorbed into the organic phase. The Zn and Cr ions remain in the water phase, while Cr (III) hydroxide precipitates when the very small solubility product is exceeded.

In a further operation, Cr-r and Zn ions can then be separated from each other be separated. The organic phase is then fed to the mixing part of unit C through the line. Through the line 9 is so much Acid added so that the pH now adjusts to a value between -2 and +1, whereby both the Cu and the Ni ions in the water phase be included. A large part of this water phase is rolled back through the line IO from the settling vessel of C into the mixture part. One advantage is that Cu and Ni sulfate crystallize out. You can continuously or discontinuously precipitate crystals and feed them through line 11 to the 'mixer-settler' D. This creates a additional cleaning stage built into the process. Through the crystallization this prevents any impurities that may have been extracted, such as Fe ions, from having a disruptive effect in the further process or even contaminating the end products. Because the water phase in unit D does not have to be neutralized, the consumption of lye is reduced to a minimum.

Through line 12, an organic extractant is fed from unit E, which consists essentially of the same, in hexane dissolved fatty acid mixture, which has already been mentioned. In order to achieve a good separation of the two phases, a little oxime can be added may be required for the fatty acid mixture. Sufficient alkali is added through line 13 so that the pH of the solution is between 4 and 5.5. As a result With this change in pH, all Cu ions migrate after the organic one. Phase. The water phase then only contains Ni ions, which can be deposited in a known manner.

The organic phase enters the mixture part through line 14 of E one, which through line 15 also contains a quantity of acid and a portion the water phase from the settling vessel of unit E. Because of the strong

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Acidification of the liquid, the Cu ions migrate to the water phase. the organic phase, which then no longer contains any metal ions, is rolled back to D, while the water phase is discharged through line 16, from which the Cu ions are then obtained, possibly after crystallization by CuSO. duroh recirculation of the water phase.

In FIG. 2, the same method is described as in FIG. 1; the meaning of the symbols is also the same. But there are two more 'mixer-settler units F and G added.

The solution of Ni ions emerging from unit D is carried through the line 22 is fed to the unit F together with an organic phase originating from the unit G, which is essentially composed of the above-mentioned fatty acid mixture and from cyclohexanone oxime dissolved in hexane composed. Lye is fed in through line 17 so that the pH of the solution is adjusted to a value between 5.5 and 8. This will be the Ni ions are absorbed into the organic phase, after which this organic phase is fed through the line 8 to the unit G. This unit is added so much acid through line 19 that the pH is at a value set between -2 and +1. This makes the organic phase of Ni ions freed. This phase is then rolled back into the unit F through the line 21. Part of the water phase is from the 'settler part in the 'mixer' part returned, reducing the concentration of Ni ions in the Unit G increases. If the solubility of the Ni salt is exceeded, then you can remove 20 crystals through the line.

In the above-described embodiments of the inventive The procedure was based on the assumption that organic medium losses do not occur. In practice, however, there will always be a small part of the organic Dissolve the medium in the water phase so that the addition of the organic medium is still necessary.

In Figure 3, for Cu and Ni ions, the pH is versus the ratio the distribution coefficient between the water and organic phase is plotted. In the experiments, the results of which are represented by curve a, the organic phase consisted of 90% by weight of hexane and 10% by weight Oleic acid mixture (70% by weight oleic acid, 10% by weight hexane and 20% by weight saturated Fatty acids, such as pentadecanecarboxylic acid, tridecanecarboxylic acid and undecanecarboxylic acid

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acid). Passed the test results shown by curve b the organic phase of 90 wt.% hexane, 9 wt.% oleic acid mixture and 1 wt.% Cyclohexanone oxime. It is clear from the figure that the Extracting agents are ideal for the selective extraction of Cu and Ni ions.

The invention will now be explained using a few experimental examples, she does not, however, tend to it.

example

You have Cu ions in a concentration of 4.9 g / l with the aid of a Extracting agent of varying composition at different pH values extracted. The phase ratio is 1: 1.

In Table 1 below, the distribution coefficient (m) of Cu ions is given as a function of pH.

10 ml of oleic acid mixture, as mentioned above, were used as the extractant and 90 ml of methyl butyl ketone, in which 1 g of cyclohexanone oxime has been dissolved, used.

Tabel 1 PH m No. of Attempt 3.7 1.8 1 4.2 3.9 2 6.3 118.3 3

In the next experiments, in which Cu ions with the same concentration have been extracted, one has the distribution coefficients for three different extractants in the same phase ratio as in experiments 1-3 certainly.

A = 10 ml oleic acid, 90 ml methyl isobutyl ketone with 1 g cyclohexanone oxime B β 25 ml oleic acid, 75 ml kerosene, 1 g cyclohexanone oxime C = 25 ml oleic acid, 75 ml kerosene

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Tabel 2 pH A. B. 1 C. 1 No. of Attempt 3.7 1.8 O, 0 O, 4th 4th 4.0 3.0 1, O, 5 7th 119 20th 39 6th

The extraction of Ni ions at a concentration of 5.0 g / l is based on the the following experiments clearly illustrated. Serve as extractant 90 ml of hexane with 10 ml of oleic acid in a phase ratio of 1: 1. No. of the experiment pH m

7 3.9 0

8 6.5 3.5

9 8 8

Example 2

An aqueous solution containing 10.6 g / l divalent Cu and 1.6 g / l Contains divalent Co, is made up of 10% by weight of oleic acid (technical), 1% by weight of cyclohexanone oxime and 89% by weight of special boiling point gasoline Extractant extracted. The ratio between the organic and the water phase is 1: 1. The table below shows the distribution coefficients for Cu and Co listed at some pH values.

Experiment pH M "M_

* Cu Co

12 4.6 2.24 0.024

13 5.7 17.3 0.03

14 6.6 114.14 0.07

Example 3

An aqueous solution containing 4.6 g of divalent Cu and 2.7 g of divalent Zn is mixed with a 10% by weight oleic acid (technical) and 90 wt .-% special boiling point gasoline extracted existing extractant. The ratio between the organic and the water phase is 1: 1. The result is:

Experiment pH M M

15 5 _S 6 171 0.8

Example 4

An aqueous solution containing 10 g / l divalent Cu and 5 g / l

Contains divalent Ni, is based on that described in Example 2 (Experiment 16) Way extracted. The experiment is then repeated without an oxime (Experiment 17). The results are:

attempt PH M_
Cu «Ni 16 5.7 400 0.09 17th 5.7 230 0.2

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Claims (13)

PATENT CLAIMS 1. A method for the selective extraction of metal ions of groups IB, HB, IHB, IVB, VB, VIB, VIIB and VIII of the periodic table from an aqueous solution of the same with the aid of an organic medium, characterized in that the extraction with an extractant on the Based on an unsaturated fatty acid or a mixture of unsaturated fatty acids takes place. 2. The method according to claim 1, characterized in that the fatty acid mixture consists of at least 50% oleic acid. 3. The method according to claim 1 or 2, characterized in that linoleic acid and / or linolenic acid are also present. 4. The method according to one or more of claims 1-3, characterized in that the fatty acid mixture contains an amount of saturated fatty acids. 5. The method according to one or more of claims 1-4, characterized in that the extractant contains a (cyclo) aliphatic oxime. 6. The method according to claim 5, characterized in that the extractant contains cyclohexanone oxime. 7. The method according to one or more of claims 4-6, characterized in that the weight ratio fatty acid / oxime is between \ and 500. 8. The method according to claim 7, characterized in that the weight ratio fatty acid / oxime is between \ and 50. 9. Extracting agent, suitable for use in the method according to one or several of claims 1-8. 10. A method for the selective extraction of Cu and Ni ions from an aqueous solution, characterized in that an extractant based on one or more unsaturated fatty acids and a (cyclo) aliphatic oxime is used. 11. The method according to claim 10, characterized in that at a pH between 5.5 and 9 Cu and Ni ions are extracted from an aqueous solution, these Cu and Ni ions at a pH between -2 and +1 absorbs from the organic phase into the water phase, at a pH between 4.0 and 5.5 the Cu ions are selectively removed from this water phase and at a pH between -2 and +1 the Cu ions again from the organic absorbs in a water phase. 12. The method according to claim 11, characterized in that after separation of Cu and Ni ions from the organic phase, an additional cleaning in - 10 - 809837/0930 ORIGINAL INSPECTED Form of a crystallization of CuSO ^ and NiSO. 4 4 13. The method ACCORDING to one or more of claims 1 to 8 and / or 10 to 12, characterized in that the extraction is carried out in a pulsation column. rll- 809837 / 093Q