JPH0568806A - Extraction of metal ions by emulsion method - Google Patents

Abstract

PURPOSE:To improve the efficiency of a mixer-settler by increasing the extraction rate and the phase separation rate when making extractive separation of metal ions in water solution. CONSTITUTION:When making extractive separation of metal ions in water solution, extraction operation is done by using extraction solvent to which a water-insoluble surfactant is added. The emulsion thus obtained is phase separated in an electric field to extract metal ions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the extraction of metal elements from aqueous solutions such as the production of metals by hydrometallurgy and the recovery of metals from wastewater. In particular, it exerts a great effect on separation and refining of rare earth metals and rare metals by AC multistage extraction.

[0002]

2. Description of the Related Art Conventionally, an ion exchange method has been known as a method for separating and refining an aqueous solution containing a rare earth metal or a rare metal, but this method treats these metals as an extremely dilute aqueous solution. Therefore, the concentration of the purified metal aqueous solution is low and a large-scale facility is required, and the flow rate of the eluent passing through the ion exchange resin tower is low, so that the productivity is low.

A solvent extraction method has been proposed as a method for improving the drawbacks of the above ion exchange method. The following various extraction solvents are used for separation and purification of rare earth metals and rare metals by the solvent extraction method. A) Ion exchange solution Carboxylic acid such as naphthenic acid and versatic acid, and acidic phosphoric acid ester such as D2EHPA.

B) Ion pair forming reagents: amines such as TOA, neutral phosphates such as TBP, MIB
Ketones such as K. C) Extraction of Metals with Chelating Reagents Since these extraction solvents have high viscosities, they are used by diluting with an organic solvent in order to reduce the viscosity and facilitate the extraction operation.

The aqueous solution containing the target metal contains nitrate,
A salt having a high solubility such as chloride is used, and if necessary, a complexing agent, a salting-out agent and the like are added. Industrial separation and purification of rare earth metals and rare metals is usually carried out by countercurrent multistage extraction, and the number of extraction stages depends on the separation efficiency of the extraction system and the target purity,
In the case of rare earth metal, 30 to 50 steps are required. As the extraction device, a mixer settler equipped with a mixer (stirring tank) for mixing an organic phase and an aqueous phase with a stirring blade attached to the tank and a settler (static tank) for separating the following two phases by gravity is often used. Has been. A pair of the stirring tank and the stationary tank corresponds to one extraction stage. And since each stage is arranged in a plane, in the case of a high number of stages, a large occupied floor area is required and
A large amount of organic phase remains in the mixer settler.

That is, a rare earth metal by a solvent extraction method,
In the production of rare metals, there is a drawback that a large equipment area is required for the production amount and a large amount of expensive extraction solvent is required. Therefore, it is industrially important to improve the efficiency of the mixer settler and reduce the size of the mixer settler.

[0007]

[Means for Solving the Problems] As a result of intensive studies made by the present inventors in order to solve such problems of the prior art, when the metal in the aqueous solution is extracted by the solvent extraction method, the organic phase is insoluble in the aqueous solution. By adding a surfactant and performing an extraction operation in a state of forming an emulsion, and then performing phase separation of an organic phase and an aqueous phase using an electric demulsification method using a high voltage, an extraction rate, The present invention has been completed by finding that the phase separation speed can be increased and the efficiency of the mixer settler can be improved.

The present invention will be described in detail below. The object of the present invention is to reduce the size by improving the efficiency of the mixer-settler when extracting the metal in the aqueous solution using an extractor such as a mixer-settler, to reduce the floor occupancy of the equipment, and to reduce the initial charge of the extraction solvent. To achieve savings. Therefore, the target metal is not particularly limited, but it exerts a particularly great effect when a large number of extraction stages are required for separation and refining such as rare earth metals. However, even if the number of extraction stages is small, when extracting from a low-concentration solution such as extraction of precious metals or recovery of metals from waste liquid, and when metals such as nickel, cobalt, and copper that require a large-scale extraction device are used. It is also effective for extraction. In carrying out the present invention, addition of a water-insoluble surfactant to the extraction solvent, addition of a voltage-applying device for demulsification to the settler are required, and the emulsion formed is
Must be O. However, other than that, basically, it is not necessary to change the conventional extraction operation and conditions.

That is, as the extraction solvent, the above-mentioned extraction solvent for the ion exchange liquid, the ion pair formation and the chelating reagent may be selected and used according to the target metal. In order to lower the viscosity and facilitate the extraction operation, petroleum fractions such as kerosene, aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene, xylene, and ethylbenzene to a predetermined concentration, as in the past. Can be diluted. The concentration of the extraction solvent used is 0.1 to 1.5 mol as in the conventional case.
A concentration of 1 / l is preferred.

The form of the salt of the aqueous solution containing the desired metal is not limited in the present invention, but nitrates and chlorides are generally used, and the metal ion concentration is usually 0.1 to 2.0.
mol / l. If necessary, a complexing agent, a salting-out agent, etc. can be added. The following are points to be considered in carrying out the present invention. The surfactant used in the present invention needs to be insoluble in water because it needs to be present in the organic phase, and its solubility in water is 0.01.
It is preferably not more than mol / l.

As the type of the surfactant, any of anions other than the cation type which interferes with metal extraction, nonionic type and amphoteric type can be used. As typical surfactants thereof, the following general formulas (1), (2), (3) and (4)
Alternatively, an anionic compound represented by (5) and an alkali metal salt thereof, a nonionic compound represented by (6), (7) and (8), and an amphoteric compound represented by (9), (10) and (11) Is raised.

[0012]

[Chemical 1]

(However, R ₁ and R ₂ are saturated or unsaturated hydrocarbon groups having 8 or more carbon atoms and may be the same or different.)

[0014]

[Chemical 2]

(However, R ₃ and R ₄ are saturated or unsaturated hydrocarbon groups having 12 or more carbon atoms and may be the same or different. L is an integer of 1 to 10.)

[0016]

[Chemical 3]

(However, R ₅ and R ₆ are saturated or unsaturated hydrocarbon groups having 8 or more carbon atoms and may be the same or different.)

[0018]

[Chemical 4]

(However, R ₇ is a saturated or unsaturated hydrocarbon group having 8 or more carbon atoms.)

[0020]

[Chemical 5]

(However, R ₈ is a saturated or unsaturated hydrocarbon group having 10 or more carbon atoms.)

[0022]

[Chemical 6]

(However, R ₉ is a saturated or unsaturated hydrocarbon group having 10 or more carbon atoms.)

[0024]

[Chemical 7]

(However, R ₁₀ is a saturated or unsaturated hydrocarbon group having 12 or more carbon atoms.)

[0026]

[Chemical 8]

(However, R ₁₁ is a saturated or unsaturated hydrocarbon group having 10 or more carbon atoms, and n is an integer of 1 to 15.)

[0028]

[Chemical 9]

(However, R ₁₂ and R ₁₃ are saturated or unsaturated hydrocarbon groups having 12 or more carbon atoms and may be the same or different. A and b are integers of 1 to 10, and They may be the same or different. X represents a halogen atom.)

[0030]

[Chemical 10]

(However, R _{14 to} R ₁₇ are saturated or unsaturated hydrocarbon groups having 2 or more carbon atoms and may be the same or different from each other.)

[0032]

[Chemical 11]

(However, R _{18 to} R ₂₁ are saturated or unsaturated hydrocarbon groups having 2 or more carbon atoms and may be the same or different from each other.) The amount of the surfactant added is the extraction solvent used at the same time. 0.03 to 3 mol%, preferably 0.05
~ 1.0 mol% is required. When it is 0.03 mol% or less, a stable emulsion is not formed. Again 3mo
Even if added in an amount of 1% or more, the effect is not particularly enhanced.

As an example of the present invention, the continuous extraction apparatus of FIG. 1 will be described. An organic phase supply tank containing an extraction component and a surfactant (<1>) and an aqueous phase supply tank containing a metal component (<2>) and pump (<3>) for stirring tank (<4
The emulsion formed by being guided by
5>) to the demulsifier (<6>) and formed by the high-voltage electrode of <7> (wherein <8> is a high-voltage converter, <9> is a slidac, and <10> is a ground). ) Is led to a high piezoelectric field The effective applied voltage is 0.5 to 10 kV, preferably 1 to 5 kV. When it is 0.5 kV or less, the efficiency of demulsification decreases. Further, when the voltage is 10 kV or more, the demulsification efficiency reaches a peak, and conversely, the organic phase and the aqueous phase are mixed by the electric field, which hinders phase separation. How to create this electric field is not specified. For example, it may be an electrode rod or plate for a cathode or an anode, or one of the electrodes may be an aqueous phase in a settler. In addition, the electric field may be alternating current or direct current. However, in order to perform demulsification under an electric field, the emulsion must be of W / O type. W / O emulsions are not always formed under conventional extraction conditions. In some cases, it is an O / W emulsion. In this case, the W / O type can be easily changed by adjusting the ratio of the organic phase and the aqueous phase in the mixer. That is, the O / W type can be changed to the W / O type by increasing the ratio of the organic phase to the water phase. However, this does not mean an increase in the amount of organic phase used. The reason is that the ratio of the organic phase in the mixer can be increased by circulating the organic phase staying in the settler through the mixer in the same stage. After demulsification, the organic phase may be taken out from the upper part of the demulsifier and the aqueous phase may be taken out from the lower part. If the apparatus of FIG. 1 is used, the position of the boundary between the organic phase and the aqueous phase can be adjusted outside the stirrer by the leveler <11>.

[0035]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 pH was adjusted to 2. with 0.1N nitric acid-0.1N sodium nitrate.
1 mol / m ³ yttrium chloride and 1 m adjusted to 0
An ol / m ³ erbium chloride solution was used as an aqueous phase, and the extraction solvent was adjusted by diluting PC88A manufactured by Daihachi Kogyo to 50 mol / m ³ and the anionic surfactant DOLPA to 1 mol / m ³ with heptane. In addition, an extraction solvent containing no surfactant was also prepared and the extraction rates were compared.
The measurement was performed by the continuous extraction device shown in FIG. 100
In a stirred tank (<4>) with a capacity of ml, the extraction solvent is 60
ml / min, and the rare earth aqueous solution was supplied at 60 ml / min. Therefore, the average residence time in the stirring tank is 50 seconds. The stirring speed was 1000 rpm. As a result, the extraction rates of yttrium and erbium were 59% and 68%, respectively, when DOLPA was not added, but increased to 76% and 84% when DOLPA was added. The water content in the organic phase that passed through the demulsifier (<6>) was measured by the Karl Fischer titration method, and the water content in the organic phase (the water content of the emulsion flowing out from the stirring tank (<4>)) was measured. (Ratio to (0.5)) was 0.8 × 10 ⁻⁵ . The effective applied voltage in the demulsification was 1 kV, and the average retention time in the demulsification tank was 50 seconds.

Example 2 pH = 2.0 with 0.1N acetic acid-0.1N sodium acetate
The 1 mol / m ³ iron chloride solution adjusted to the above was used as the aqueous phase, and the extraction solvent was LIX84 from Henkel at 20 mol /
m ^3, an anionic surfactant DOLPA a 1 mol / m
Was prepared by diluting with heptane so that ^3. Moreover, the extraction solvent containing no surfactant was also adjusted and the extraction rates were compared. The measurement was performed by the continuous extraction device shown in FIG. In a stirring tank (<4>) having a capacity of 100 ml, the extraction solvent was 60 ml / min, and the iron chloride solution was 60 ml / mi.
n. Therefore, the average residence time in the stirring tank is 50 seconds. The stirring speed was 1000 rpm. As a result, the extraction rate was 3.3% when DOLPA was not added, but improved to 30% when DOLPA was added. still,
The water content in the organic phase was 1.0 × 10 ⁻⁵ , the effective applied voltage during demulsification was 2 kV, and the average retention time in the demulsifier was 48.
It was seconds.

Example 3 0.1N acetic acid-0.1N sodium acetate at pH 6.5
Each of the 1 mol / m ³ nickel chloride and cobalt solutions adjusted to the above was used as an aqueous phase, and the extraction solvent was LIX from Henkel.
20 mol / m ³ 84, anionic surfactant DOL
PA was diluted and adjusted with heptane so as to be 0, 0.1, 0.5, 1.0 mol / m ³ , and the extraction rates were compared. The measurement was performed by the continuous extraction device shown in FIG. 10
The extraction solvent is 1 in a stirred tank (<4>) with a capacity of 0 ml.
The mixed chloride solution of 7 ml / min and nickel and cobalt was supplied at 17 ml / min. Therefore, the average residence time in the stirring tank is 180 seconds. The stirring speed is 1000r
pm. The results obtained are shown in FIG.
It can be seen that the addition rate of PA significantly improves the extraction rate. The water content in the organic phase was 8.9 × 10 ⁻⁵ , the effective applied voltage during demulsification was 2 kV, and the average retention time in the demulsifier was 140 seconds.

[0039]

[Effects of the Invention] A water-insoluble surfactant is added to an extraction solvent to form an emulsion, which accelerates the extraction speed and enables reduction of the mixer capacity, and the produced emulsion is electrically demulsified using a high voltage. By the method, it was possible to reduce the settler capacity by performing the phase separation of the organic phase and the aqueous phase. As a result, the mixer settler can be downsized, the equipment can be downsized, and the initial amount of extraction solvent can be reduced.

As described above, the present invention is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a continuous extraction apparatus used in Examples 1 to 3, where <1> is an organic phase supply tank, <2> is an aqueous phase supply tank, and <
3> is a microtube pump, <4> is a stirring tank, <5
> Is a sampling cock, <6> is a demulsifier, <7> is a high-voltage electrode, <8> is a high-voltage converter, <9> is a slidac, <10> is a ground, and <11> is a leveler.

FIG. 2 is a graph showing the relationship between the DOLPA concentration and the extraction rate.

Claims (1)

[Claims] 1. When extracting and separating metal ions from an aqueous solution, extraction operation is performed using an extraction solvent to which a water-insoluble surfactant is added, and the obtained emulsion is phase-separated under an electric field. Method for extracting metal ions