JPH07138670A - Method for separating and recovering nickel and/or cobalt - Google Patents

Abstract

PURPOSE:To effectively separate and recover Ni and Co by bringing an extraction solvent contg. a dialkyl phosporic acid and hydoxyoxime compd. and an aq. soln. in which Ni, Co and Al coexist into contact with each other in a specific pH range. CONSTITUTION:The extraction solvent contg. the dialkyl phosporic acid expressed by formula I and the hydoxyoxime compd. expressed by formula II and the aq. soln. in which the Ni and/or and Al coexist are brought into contact with each other in the range of pH <=2. In the formula I, the formula II, R1, R2, R3, R4 are alkyl groups having 4 to 25C straight chains or side chains. As a result, the Ni and/or the Co are selectively and efficiently separated and recovered from the aq. soln. in which a large amt. of the Al coexists. The ratio of the dialkyl phosporic acid to the hydoxyoxime compd. is preferably in a range of about 0.05 to 2.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating and recovering nickel and / or cobalt by a solvent extraction method and a separating and extracting agent used in the separating and recovering method. In particular, a relatively large amount of aluminum and a relatively small amount of nickel and / or
Or, from an aqueous solution containing cobalt, nickel and / or
Alternatively, the present invention relates to a solvent extraction method for selectively and efficiently separating and recovering cobalt and a separation-extracting agent used in the extraction method.

[0002]

2. Description of the Related Art Cobalt has heat resistance and wear resistance, and particularly alloys of cobalt with tungsten, chromium, nickel, etc. have strong resistance. For this reason, cobalt is widely used as a raw material for high speed steels, heat resistant alloys and cemented carbide tool materials. It is also widely used as a raw material for magnetic materials and catalysts. On the other hand, nickel is widely used as a special steel, a special alloy, and a plating material, and is also an essential metal for batteries, catalysts, hydrogen storage, shape memory alloys, and the like. As described above, both metals are indispensable to the present industrial society, but their production areas are ubiquitous, and the political and social conditions of the producing countries are always plagued by the instability of supply. Therefore, in Japan, which does not have resources of these metals, it is required to recover these metals from various industrial wastes as secondary resources. Used waste desulfurization catalyst is one of such secondary resources. Since the waste desulfurization catalyst has an active metal supported on an alumina carrier, it is necessary to always consider the presence of aluminum when recovering the metal from the waste desulfurization catalyst. Currently, carboxylic acid compounds and D2EHPA [di-] are used to recover these metals from aqueous sulfuric acid solutions containing nickel, cobalt, etc.
(2-ethylhexyl) phosphoric acid] and other acidic phosphorus compounds and the like are used as extractants. However, since these extractants have a pH range of about 3 to 4 or more for extracting nickel and / or cobalt, a relatively large amount of nickel and / or cobalt such as the sulfuric acid leaching aqueous solution of the waste desulfurization catalyst is used. It is not suitable for separating and recovering nickel and cobalt from an aqueous solution containing aluminum. That is, since aluminum precipitates as a hydroxide in such a pH range, a part of nickel and cobalt also co-precipitates with this precipitation. Furthermore, when the above acidic extractant is used,
Aluminum is preferentially extracted over nickel or cobalt, that is, p is lower than nickel or cobalt.
The purpose cannot be achieved because it is extracted in the H region. Amax
The patent of the company (JP-A-53-86621) is a mixture of 5,8-diethyl-7-hydroxy-6-dodecanone oxime which is an α-hydroxy oxime compound and a sulfonic acid compound such as dinonylnaphthalene sulfonic acid. It is described that nickel and cobalt can be selectively extracted with respect to aluminum even from an acidic aqueous solution having a pH range of 2 or less by using as an extractant. However, sulfonic acid compounds are very strong acidic compounds,
The 5,8-diethyl-7-hydroxy-6-dodecanone oxime compound has a problem that it deteriorates and loses its function when coexisting with a strongly acidic substance for a long time, and such an extractant is not always satisfactory. It wasn't good enough.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides nickel and / or cobalt after removing molybdenum, vanadium, etc. from an aqueous sulfuric acid solution containing a metal component obtained by treating a waste desulfurization catalyst with an aqueous sulfuric acid solution. Nickel and / or from an aqueous solution of pH 2 or less containing aluminum, etc.
Another object of the present invention is to provide a method for efficiently separating and recovering cobalt and using a chemically stable specific extractant.

[0004]

The present invention provides a dialkyl phosphoric acid represented by the following general formula [I] in a method for separating and recovering nickel and / or cobalt from an aqueous solution in which nickel and / or cobalt coexist with aluminum.

[Chemical 4] (Wherein R ₁ and R ₂ are alkyl groups having a straight chain or a side chain having 4 to 25 carbon atoms) and the following general formula [II]
A hydroxyoxime compound represented by

[Chemical 5] (Provided that R ₃ and R ₄ are alkyl groups having a straight chain or a side chain having 4 to 25 carbon atoms) as an extractant and the aqueous solution are brought into contact with each other in a pH range of 2 or less. The present invention relates to a method for separating and recovering nickel and / or cobalt, which is characterized by selectively extracting nickel and / or cobalt.

In the general formula [I], R ₁ and R ₂
When the number of carbon atoms is less than 4, the dialkyl phosphoric acid is easily dissolved in water and is eluted into the aqueous solution during extraction, which is not preferable from the viewpoint of water treatment. Further, if the carbon number of R ₁ and R ₂ is larger than 25, the liquid becomes very viscous and the extraction operation becomes difficult, which is not preferable. Examples of the dialkyl phosphoric acid used in the present invention include di-2-ethylhexyl phosphoric acid ester, di-isodecyl phosphoric acid ester, di-3,4-
Dimethylpentyl Phosphate, Tridecyl Hexadecyl Phosphate, 3,4-Dimethylpentyl-4,4-
Examples thereof include dimethylbutyl phosphate ester and 2,3-dimethylbutylhexyl phosphate ester. R ₁ and R ₂
Are not necessarily the same groups. At least _one of R ₁ and R ₂ is preferably a branched alkyl group, and more preferably both are branched alkyl groups. Examples of such a dialkyl phosphoric acid having an alkyl group include a dialkyl phosphoric acid having a highly branched alkyl group represented by the branched alkyl represented by the above formula [III]. In particular, TR-83 containing a branched alkyl group diphosphate represented by the above formula [III], which is used as an industrial extractant, as a main component
[Trade name, manufactured by Daihachi Chemical Industry Co., Ltd.] is preferable in terms of cost. As R ₁ and R ₂ , an alkenyl group, a cycloalkyl group, an aryl group, an aralkyl group or the like may be used.

In the hydroxyoxime compound represented by the above general formula [II], when R ₃ and R ₄ have a carbon number of less than 4, the compound is easily dissolved in water and is eluted in an aqueous solution at the time of extraction. Also, it is not preferable in terms of treatment of wastewater after extraction. When the carbon number of R ₃ and R ₄ is larger than 25, it becomes insoluble in a commonly used diluent, which is not preferable. The hydroxyoxime compound used in the present invention includes 5,8-diethyl-7-hydroxy-6-
Dodecanone oxime, 5,10-diethyl-8-hydroxy-7-tetradecanone oxime, 7-hydroxy-
Examples thereof include 6-dodecanone oxime and 5,8-dimethyl-7-hydroxy-6-dodecanone oxime. Particularly, LIX63 (manufactured by Henkel, trade name) containing 5,8-diethyl-7-hydroxy-6-dodecanone oxime as an industrial extractant is preferable in terms of cost.

The extractant used in the present invention is a mixed extractant of the dialkyl phosphoric acid represented by the formula [I] and the hydroxyoxime compound represented by the formula [II]. The volume ratio of the dialkyl phosphoric acid to the hydroxyoxime compound is 0.05 to 2.0, preferably 0.1 to 1.0. If this ratio is less than 0.05, the extraction rate of nickel and cobalt will be small, and if it is more than 2.0, the extraction rate of nickel and cobalt will be reduced, and aluminum will be mixed with nickel and cobalt. It is not preferable because it is extracted into.

The above-mentioned extractant may be used alone or as a solvent for extraction without being mixed with a diluent or the like, or by dissolving it in an appropriate diluent. As the diluent, an aliphatic diluent such as kerosene, benzene, an organic diluent that is usually used such as an aromatic diluent such as toluene can be used, but an organic solvent insoluble in water can be used. It is known that group-type diluents are oxidized by cobalt for long-term use to form aromatic carboxylic acids such as benzoic acid, which causes various troubles such as difficulty in two-phase separation. It is preferable to use an aliphatic diluent. The mixing ratio of the above-mentioned extractant and diluent is preferably in the range of 1:99 to 99: 1, and particularly preferably in the range of 5:95 to 50:50.

In the present invention, in order to separate and recover nickel and / or cobalt, first, the above-mentioned extraction solvent and an aqueous solution containing these metals are brought into liquid-liquid contact within a pH range of 2 or less. In this case, if the pH of the aqueous solution is higher than 2, it will be hydrolyzed when a large amount of coexisting aluminum is present in the aqueous solution to cause precipitation, which makes smooth extraction operation difficult. Alternatively, it is not preferable because it is extracted together with cobalt. In the present invention, the pH is preferably 0.5 to 2.0, more preferably 0.8 to 1.5.
As the liquid-liquid contact method, any of the well-known methods used in the solvent extraction method can be used. The volume ratio of the extraction solvent and the aqueous solution at the time of extraction is not particularly limited, but is usually in the range of 1:10 to 10: 1. This volume ratio is determined in consideration of the concentration of the extractant in the extraction solvent, the concentrations of nickel and / or cobalt and aluminum in the aqueous solution, the liquid-liquid contact method, and the like. Then, the extraction solvent from which nickel and / or cobalt has been extracted in the above extraction step is separated from the aqueous solution, and the separated extraction solvent is back-extracted with a mineral acid such as sulfuric acid, hydrochloric acid, nitric acid or perchloric acid having a pH of about 5 or less. Nickel and / or cobalt are easily back-extracted into this aqueous solution by contact with a liquid. The volume ratio of the extraction solvent and the back extraction liquid at the time of back extraction is not particularly limited, but is usually in the range of 10: 1 to 1:10. In this way, the extraction solvent can be regenerated by the back extraction step, and the extraction solvent can be repeatedly used. Also, nickel and / or back-extracted in the aqueous solution
Alternatively, cobalt is, for example, nickel sulfate (NiSO ₄
· 6H ₂ O), nickel nitrate [Ni (NO _{3) 2} · 6H
₂ O] and / or cobalt sulfate (CoSO ₄ · 6H ₂
O) and cobalt nitrate [Co (NO ₃ ) ₂ .6H ₂ O]. If desired, nickel and cobalt can be separately separated and recovered by a known method.

In the present invention, the reason why nickel and / or cobalt is selectively extracted by the synergistic effect of the mixed extractant by the combination of the specific compounds is not clear, but the acidity is weaker than that of the sulfonic acid compound. ,
Since a mixture of a specific acidic phosphorus compound and a hydroxyoxime compound is used as an extractant, there is no fear that the extraction function will deteriorate even if it is used for a long period of time.

[0011]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 (Single system extraction) LIX63 (a specific compound of [II]) was added to EXXSOL D80 (manufactured by Exxon Chemical Co., Ltd., trade name), which is a diluent containing a paraffin component as a main component, to obtain 20% by volume. An acidic phosphorus compound extractant [a specific compound of [I], manufactured by Daihachi Chemical Industry Co., Ltd.], which is commercially available under the trade name of TR-83, is dissolved in a ratio of 7.0% by volume. Using a mixed extraction solvent added and mixed in step 1, 50 mM sodium sulfate and aluminum, or nickel, or cobalt each containing about 10 mM, pH adjusted in the range of 0.5 ~ 2.5 and 40 ℃ When the mixture was shaken at an O / A ratio of 1/1 at 72 ° C for 72 hours, the result of the relationship between the pH of the aqueous solution and the extraction percentage of each metal shown in Fig. 1 was obtained. Where TR
-83 is a mixture containing 2 and 3 phosphoric acid ester having an alkyl chain of the above formula [III] in a ratio of 7: 3.

[Chemical 6] From this result, if the extraction solvent having the above mixing ratio is used, p
It can be seen that in the low pH range of H of 0.5 to 2, only cobalt and nickel can be highly selectively extracted, and aluminum is not extracted.

Example 2 (Extraction of complex system) LIX63 and TR-8 in EXXSOL D80
3 containing 30% by volume and 10% by volume of the mixed solvent, 14200 ppm of aluminum, 1140 ppm of cobalt, 232 ppm of nickel, and p
When an O / A ratio of 1/1 with an aqueous solution of H was shaken at a temperature of 30 ° C. for 72 hours, the results shown in Table 1 were obtained. From this result, it can be seen that by using such a mixed extractant, cobalt and nickel are extracted almost 100% and aluminum is hardly extracted even at a relatively low pH of about 1.5.

Extraction of nickel, cobalt and aluminum with LIX63 / TR-83 mixed extractant

[Table 1] The numerical value in [] is the metal concentration in the aqueous solution (unit: pp
m)

[0015]

[Effect] According to the present invention, nickel and / or cobalt can be separated and recovered extremely selectively from an aqueous solution in which a large amount of aluminum coexists by a new extraction method using a mixed extractant.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the pH of an aqueous solution and the extraction percentage of each metal in the extraction operation of Example 1.

Claims (6)

[Claims] 1. A method for selectively separating and recovering nickel and / or cobalt from an aqueous solution in which nickel and / or cobalt and aluminum coexist by a solvent separation method, wherein a dialkylphosphoric acid represented by the following general formula [I] 1] (Wherein R ₁ and R ₂ are alkyl groups having a straight chain or a side chain having 4 to 25 carbon atoms) and the following general formula [II]
A hydroxyoxime compound represented by: (Provided that R ₃ and R ₄ are alkyl groups having a straight chain or a side chain having 4 to 25 carbon atoms) as an extractant and the aqueous solution are brought into contact with each other in a pH range of 2 or less. A method for separating and recovering nickel and / or cobalt, which comprises selectively extracting nickel and / or cobalt. _2. A dialkylphosphoric acid in which at least one alkyl group of R ₁ and R _{2 in} the above formula [I] is a branched alkyl group having 6 or more carbon atoms is used.
The method for separating and recovering nickel and / or cobalt described. 3. The nickel and / or cobalt according to claim 1, wherein the dialkyl phosphoric acid represented by the above formula [I] is a mixture of 2 and 3 phosphoric acid ester having a branched alkyl group represented by the following formula [III]. Separation and recovery method. [Chemical 3] 4. The hydroxyoxime compound represented by the above formula [II] is 5,8-diethyl-7-hydroxy-6-.
The method for separating and recovering nickel and / or cobalt according to claim 1, 2 or 3, which is dodecanone oxime. 5. The nickel and / or cobalt according to claim 1, 2, 3 or 4, wherein the aqueous solution in which nickel and / or cobalt and aluminum coexist is an aqueous solution obtained by treating a waste desulfurization catalyst with an aqueous sulfuric acid solution. Separation and recovery method. 6. A separating and extracting agent for nickel and / or cobalt, which comprises a dialkylphosphoric acid represented by the formula [I] and a hydroxyoxime compound represented by the formula [II] in a solvent.