JPH10328502A - Countercurrent multistage liquid-liquid extractor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely and effectively perform separating operation of a lot of mixture by simple operation. SOLUTION: In this countercurrent multistage liquid-liquid extractor, an agitating vessel 2 equipped with an agitating means for agitating a light liquid and a heavy liquid for liquid-liquid extraction is provided with a light liquid separating and sending part 3 for separating the heavy liquid and sending the light liquid, a heavy liquid separating and sending part 4 for separating the light liquid and sending the heavy liquid, a light liquid introducing part 5 into which the light liquid is introduced, and a heavy liquid introducing part 6 into which the heavy liquid is introduced to form a liquid-liquid extraction unit 1. The light liquid separating and sending parts 3 and the light liquid introducing parts 5 in the plural liquid-liquid extraction units 1 are connected in order, and also the heavy liquid separating and sending parts 4 and the heavy liquid introducing parts 6 are connected in order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a countercurrent multistage liquid-liquid extraction device and, more particularly, to a countercurrent multistage liquid-liquid extraction system in which solutes are separated by using two liquid phases that do not mix with each other to separate substances. Related to the device.

[0002]

2. Description of the Related Art Chromatography is generally used as a device for extracting a specific component from a mixture. In this chromatography, a stationary phase solid or a solid in which a stationary phase is supported on a solid which is a stationary phase carrier is packed in a column, and a liquid or gas is flowed as a mobile phase through the column, and the solid is retained on the stationary phase. It separates the mixture according to the difference in force. In order to carry out the separation efficiently in this process, it is required that the column is uniformly filled with a fine filler having a constant particle size and the mobile phase is caused to flow uniformly with respect to the column cross-sectional area. As a result, a large number of virtual plates having a constant mobile phase volume and fixed phase volume are formed in the column, and rapid mass exchange between the mobile phase and the mobile phase is performed in each plate to virtually form an equilibrium state. Is done. It is necessary that this process be performed sequentially on a number of successive plates to achieve multi-stage separation.
Since the driving force of this mass transfer is the natural diffusion of solute molecules in the mobile phase or stationary phase, in order to achieve equilibrium in each plate, the mobile phase and stationary phase must be separated sufficiently finely. Must be in contact.

[0003] If the filler is large, the mobile phase portion in the space between these fillers also becomes large, and the time required to reach equilibrium in the stationary phase or mobile phase by diffusion alone becomes too long, and the normal time is increased. Within the equilibrium, the separation efficiency is also greatly diminished. In addition, when a substance distributed to the stationary phase also diffuses in the stationary phase, the diffusion rate in the stationary phase, which is considered to have a lower diffusion rate than in the liquid phase, increases the mass transfer rate between the mobile phase and the stationary phase. Significantly reduced
Decreases separation efficiency.

[0004] For the above reasons, it is necessary to use a fine packing material in the chromatography, and the chromatography using a column packed with the fine packing material requires mutual separation of a small amount of a mixture containing various components. It can be said that quantification is an extremely effective method. However, for the purpose of adjustment or production, a stationary phase having a weight of several hundred to several hundred thousand times the weight of the mixture to be separated and purified depending on the processing amount is required. The size of the column becomes extremely large in both the inner diameter and the length.

[0005] Further, in the separation by chromatography, it is necessary that the mobile phase flow uniformly in a cross section perpendicular to the longitudinal direction of the column. However, as the diameter of the column increases, the flow path of the mobile phase can be partially formed. And efficient separation tends to be hindered due to so-called channeling. Further, since increasing the length of the column increases the pressure for mobile phase liquid supply, when making a column packed with a fixed packing material, it is necessary to avoid the above-described difficulty in channeling. However, there is a limit to the method of increasing the length by reducing the column diameter.

[0006] Therefore, in a column which needs to be packed with a large amount of packing material, both means of increasing the inner diameter and increasing the length have unavoidable technical limitations.

Another drawback of the conventional chromatography is that during the column development, the part of the column where no mixture is present merely causes an increase in the pressure of the pump for sending the mobile phase, and the separation is difficult. It is not contributing at all. For this reason, the larger the number of theoretical plates of the column, the smaller the portion where the sample is present.

On the other hand, there is a countercurrent chromatography in which a stationary phase solid is not contained in the system. In this countercurrent chromatography, one of two equilibrium liquid phases that are not mixed with each other is used as a stationary phase and the other as a mobile phase, and the specific gravity difference is used in the stationary phase held by gravity or centrifugal force. In this process, a mobile phase is caused to flow, and in this process, solutes are distributed between the stationary phase and the mobile phase, whereby chromatographic separation is performed.

[0009]

In the above-mentioned countercurrent chromatography, since no stationary phase solids are contained in the system, there are naturally no disadvantages or limitations of chromatography related to solids, but the distribution of solutes is limited. When the droplets of the mobile phase pass through the stationary phase, they are promoted in the process of contacting the surfaces. Therefore, when the droplets are small, it is difficult to uniformly pass through the cross sections of the stationary phase having a large cross section. . In addition, if the diameter of the droplet is increased to a diameter equivalent to the cross-section of the stationary phase, the droplet will pass uniformly, but it will take time for the solute to move, and in both cases, the factors that hinder mass transfer between the stationary phase mobile phase And the separation efficiency was reduced.

In order to avoid this, the inner diameter of the column holding the stationary phase may be reduced, and at the same time, the operation may be performed under strong centrifugal force to reduce the diameter of the droplet. However, the volume of the stationary phase is reduced, and the amount of sample that can be processed is reduced.

An apparatus for extracting a large number of samples on an industrial scale in a multistage manner has been known for a long time in the field of chemical engineering.
Mixer settler tower, Schebel Column
Or Podbi, which is said to perform countercurrent multistage extraction in a centrifugal force field
Although there is elniak or the like, the extraction efficiency expressed by the number of theoretical stages is mostly two or three stages, and rarely exceeds five or six stages.

Accordingly, an object of the present invention is to provide a countercurrent multistage liquid-liquid extractor capable of reliably and efficiently separating a large amount of a mixture by a simple operation.

[0013]

In order to achieve the above object, a countercurrent multistage liquid-liquid extraction device according to the present invention is provided with a stirring device provided with stirring means for stirring a light liquid and a heavy liquid for performing liquid-liquid extraction. In a container, a light liquid separation / delivery unit that separates the light liquid and the heavy liquid and sends out the light liquid, a heavy liquid separation / delivery unit that separates the light liquid and the heavy liquid and sends the heavy liquid, A light liquid introduction unit for introducing a light liquid and a heavy liquid introduction unit for introducing a heavy liquid in a stirring vessel are provided to form one liquid / liquid extraction unit, and the light liquid separation / delivery in a plurality of liquid / liquid extraction units is provided. And a light liquid introducing section are sequentially connected, and the heavy liquid separating / sending section and the heavy liquid introducing section are sequentially connected.

[0014]

1 and 2 show an embodiment of a countercurrent multistage liquid / liquid extraction apparatus according to the present invention. FIG. 1 is a front view of a liquid / liquid extraction unit, and FIG. 2 is a countercurrent multistage. It is a system diagram of a liquid extraction device.

First, as shown in FIG. 1, a liquid-liquid extraction unit 1, which is one unit of a countercurrent multistage liquid-liquid extraction device,
A light liquid separation and delivery section 3 for sending out a light liquid (upper phase) from the inside of the stirring vessel to a stirring vessel 2 provided with stirring means, a heavy liquid separation and delivery section 4 for sending out a heavy liquid (lower phase), It is provided with a light liquid introduction section 5 for introducing a light liquid into a stirring vessel and a heavy liquid introduction section 6 for introducing a heavy liquid. Further, in the stirring vessel 2, a rotor 7 of a magnetic stirrer is supplied as stirring means for stirring the light liquid and the heavy liquid to promote liquid-liquid extraction. In addition, stirring vessel 2
Is provided with a sealable lid 8.

The light liquid separation / delivery section 3 and the heavy liquid separation / delivery section 4 project obliquely upward or downward from the intermediate portion of the peripheral wall of the stirring vessel 2, and are separated from the stirring state in the stirring vessel. The liquid separation sections 3a and 4a are formed so that a light liquid and a heavy liquid can be separated by a difference in specific gravity. That is, the light liquid separated by the liquid separation unit 3a is
The heavy liquid flowing out from the outlet 3b provided at the upper end of the light liquid separation / delivery unit 3 and separated by the liquid separation unit 4a flows out from the outlet 4b provided at the lower end of the heavy liquid separation / delivery unit 4.

The light liquid introducing section 5 and the heavy liquid introducing section 6
Although it can be provided at an appropriate position on the peripheral wall of the stirring vessel 2, usually, the light liquid introduction section 5 is provided above the peripheral wall of the stirring vessel 2.
It is preferable that the heavy liquid introducing portions 6 are respectively provided on the upper part of the peripheral wall of the stirring vessel 2.

When two immiscible liquid phases used for distribution are put into the stirring vessel 2 and agitated, the distribution equilibrium of the solute distributed to the two liquid phases is promoted. In this stirring vessel 2,
When a heavy liquid having a large specific gravity among the two liquid phases from the heavy liquid introducing section 6 and a light liquid having a small specific gravity among the two liquid phases are introduced from the light liquid introducing section 5, the two liquid phases are stirred in the stirring vessel 2, The solute dissolved in the two liquid phases is efficiently partitioned between the two liquid phases. At the same time that the two liquid phases are sent into the stirring vessel 2, a liquid having a volume corresponding to the amount of liquid flowing into the stirring vessel 2 is pushed out of the stirring vessel 2 and sent out to the light liquid separation / delivery section 3 or the heavy liquid separation / delivery section 4. It is. Since the liquid is not agitated in the light liquid separation / delivery section 3 and the heavy liquid separation / delivery section 4, the two liquid phases mixed in the stirring vessel 2 are separated into the light liquid separation / delivery section 3 and the heavy liquid separation / delivery section. In the case of No. 4, separation is carried out by a difference in specific gravity. Therefore, it is the light liquid that is the upper layer that finally flows out of the outlet 3b of the light liquid separation / delivery section 3, and similarly, the outflow port 4 of the heavy liquid separation / delivery section 4
What flows out of b is the heavy liquid that is the lower layer. The heavy liquid flowing into the light liquid separation / delivery section 3 and the light liquid flowing into the heavy liquid separation / delivery section 4 return to the stirring vessel 2 due to a difference in specific gravity.

At this time, if the flow rate of the light liquid or the heavy liquid or both of them is too high, it is not possible to obtain a time for sufficient phase separation in the light liquid separation / delivery section 3 or the heavy liquid separation / delivery section 4.
The flow rate of each liquid is adjusted according to the properties of the two liquid phase system to be used so that the desired phase separation is performed, or the volumes of the liquid separation units 3a and 4a are sufficiently increased, Ensure that sufficient phase separation occurs at a given flow rate.

The liquid-liquid extraction unit 1 thus formed
As shown in FIG. 2, a plurality of the liquid-liquid extraction units 1 and 1 are used in a state in which the light-liquid separation / delivery unit 3 and the light-liquid introduction unit 5 are connected to each other. The heavy liquid separation / delivery section 4 and the heavy liquid introduction section 5 are sequentially connected by a heavy liquid pipe 10. Further, in the liquid-liquid extraction unit 1 at both ends, for example, the liquid-liquid extraction unit 1 at the left end in FIG. 2, a light liquid storage tank 12 is connected to the light liquid introduction unit 5 via a light liquid pump 11, and heavy liquid separation is performed. A heavy liquid recovery unit (lower phase fraction collector) 13 is connected to the delivery unit 4, and a heavy liquid storage tank 15 is connected to the heavy liquid introduction unit 6 via a heavy liquid pump 14 in the right liquid / liquid extraction unit 1. A light liquid recovery unit (upper phase fraction collector) 17 is connected to the light liquid separation / delivery unit 3 via a pump 16.

A sample pump 18 and a sample storage tank 19 for injecting a sample into the stirring vessel 2 are provided at appropriate positions of the plurality of connected liquid-liquid extraction units 1. In addition, each stirring vessel 2 is a magnetic stirrer 2
The light liquid and the heavy liquid in each stirring vessel 2 are stirred by the rotation of the rotor 7 and maintained in an appropriate mixing state.

Accordingly, the light liquid introduced into the liquid-liquid extraction unit 1 on the left end is sequentially introduced into the liquid-liquid extraction unit 1 on the right side, and finally collected from the liquid-liquid extraction unit 1 on the right end into the light liquid recovery unit 17. Is done. Similarly, the heavy liquid introduced into the liquid-liquid extraction unit 1 on the right end is sequentially introduced into the liquid-liquid extraction unit 1 on the left, and is finally collected from the liquid-liquid extraction unit 1 on the left end into the heavy liquid recovery unit 13. . When the flow rates of the light liquid and the heavy liquid from both ends are made equal, among the components in the sample injected from the sample storage tank 19 into the liquid-liquid extraction unit 1 at the center, the sample that is easily distributed to the light liquid is On the right side, the sample that is easily distributed to the heavy liquid moves to the left.

Here, the distribution of the two liquids is equal, in other words, a sample having a distribution coefficient of 1 does not move from the center, the concentration at the center becomes highest over time, and shows a symmetric distribution on both sides. Further, even with a sample having a distribution coefficient of 1, the light liquid moves to the right when the flow rate of the heavy liquid is larger than that of the heavy liquid, and moves to the left when the flow rate of the heavy liquid is increased. The movement of the substance in the extraction device
The direction is determined by whether the number (extraction coefficient) obtained by multiplying the distribution coefficient by the flow ratio of the light and heavy liquids is greater or smaller than 1, and the moving speed is determined by the magnitude of the number. When the sample is continuously introduced into the central part, when the extraction coefficient is larger than 1, the whole moves to the right, and when the extraction coefficient is smaller than 1, it moves to the left. When the extraction coefficient is 1, the sample concentration shows a distribution in which the center is high and spreads symmetrically on both sides.

To describe this situation in detail, first, in FIG. 2, each liquid-liquid extraction unit 1 is considered to be a unit that has reached a complete equilibrium. There are also an arbitrary number of similar units on both sides of the central unit, and n
And m units on the right side. Further, the sample is continuously added to the central unit, and a new upper phase is supplied at a flow rate FU from the left end, and a new lower phase is supplied at a flow rate FL from the right end.
Let's add When a steady state is reached by operating such a system, the amounts of the samples eluted from the leftmost unit and the rightmost unit in a unit time are β and ω, respectively, and the ratio value [β / ω] is as follows. It is represented by the following equation. β / ω = (εm−1). εn + 1 / (εn + 1−1) In the equation, ε is an extraction coefficient, and is represented by ε = KFU / FL. K at this time is the distribution coefficient of the sample (K = CU
/ CL: CU and CL are the concentrations of the upper phase and the lower phase when the sample is divided into two liquid phases and equilibrated.

Therefore, of the added samples, the ratio eluted from the leftmost unit and the ratio eluted from the rightmost are:
Β / (β + ω) and ω / (β + ω), respectively. When these are expressed by extraction coefficients, the ratio eluted from the left end is (ε
n + 1−1) / εm · εn + 1−1, and the ratio eluted from the right end is (εm−1) · εn + 1 / εm · εn +
1-1.

Therefore, if ε is not 1, the sample elutes from the left end or the right end at a fixed ratio by setting n and m to appropriate sizes. Furthermore, if n and m are sufficiently large, samples with ε greater than 1 are virtually all eluted from the right end, and samples with ε less than 1 are all eluted from the left end.

This means that when there are two or more mixtures in the sample, some of which have ε greater than 1 and some of which are smaller than 1, this mixture will have two Will be separated.

The required magnitudes of n and m are determined according to the magnitudes of the extraction coefficients ε1 and ε2 of the two components to be separated.
When 1, and ε2 are far apart from each other, n, m
May be small, but when it is close to 1, n and m must be increased. For these two substances,
Adjusting the flow rates of the upper and lower phases so that the square root of ε1 × ε2 becomes 1 is one method of selecting the separation efficiency. This condition is optimal for a mixture in which the two components to be separated are present in the same amount, such as a racemate, but even when the composition ratio is different, select an efficient flow ratio according to the above formula. be able to.

The above is a method of separating a mixture into two parts with an extraction coefficient of 1 as the center. When a single substance is purified with high purity, the extraction coefficient of the target substance should be close to 1. By operation, impurities having an extraction coefficient larger than 1 can be moved toward the right end and impurities smaller than 1 can be moved toward the left end, and can be finally eluted from the system.

On the other hand, a substance having an extraction coefficient of 1 is ideally distributed near a normal distribution centering on the sample injection unit. As a result, if the sample is continuously injected, the sample will be accumulated in the system, so that after the sample is injected to the extent that the change in the extraction coefficient due to the increase in concentration is not remarkable, the injection of the sample is stopped and the operation is continued. Thereby, the distribution of the target substance gradually expands, but the impurities gradually elute out of the system. As a result, the purity of the target substance increases as the operation time increases. However, if n and m are small, the target substance gradually elutes from the system during this period. To prevent this and increase the yield of the target substance, n and m must be sufficiently large.

Another method of extracting one target substance from the mixture can be performed as follows using the above operation twice. For example, when the components in the mixture are arranged in the order of the distribution coefficient, they can be arranged as "... substance p, target substance, substance q, ...". Therefore, conditions are set so that the extraction coefficient can be divided into two groups, that is, the group of “substance p” and the group of “target substance, substance q,...” In the first separation operation. , After separating each substance whose partition coefficient is up to substance p, in a second operation,
By changing the flow rate of the liquid phase so as to be divided into two, “target substance” and “substance q,.
Only the target substance can be taken out.

Further, the number of units constituting the system and the resolving power are as follows when compared with the resolving power of chromatography taking the separation of two components as an example. Assuming that the mass distribution ratio of chromatography and the extraction coefficient of the present apparatus are the same for the two components of interest, and elution is carried out at k = 2 in chromatography, at n = m = 5, about 100 theoretical plates are obtained. In the following, about 700 stages for n = m = 15, about 1600 stages for n = m = 25, and n = m
At = 50, a corresponding separation is obtained at about 5800 stages. Further, n and m do not have to be equal and can be increased or decreased according to the purpose. For example, when only the purity of one component is required in a two-component system and the yield may be slightly sacrificed, Depending on the extent, one can be significantly reduced.

As described above, the apparatus of the present invention can eliminate all problems caused by the presence of a solid, since the system does not contain a solid as compared with the chromatography using a stationary phase solid. This eliminates managing the solid to have uniform physicochemical properties and its cost, including the solid itself. In addition, since the possibility of sample loss due to irreversible adsorption of solids and the possibility of sample decomposition that may occur on the surface of an active solid are eliminated, there is no need to consider sample loss due to separation operations.

Further, as compared with the countercurrent chromatography, since the distribution of the substance between the two liquid phases is promoted and the relative flow rate due to the countercurrent of the two liquid phases is independently controlled, the distribution of the solute by the promotion of the distribution is improved. Does not spread. That is, because the solute does not move to the next unit due to stirring,
It is easy to create operating conditions such that each unit has one theoretical stage, and even if the volume of the unit is increased to increase the processing amount, the stage efficiency of the unit does not decrease. Thus, an increase in throughput does not accompany a decrease in resolution.

In addition, since any chromatography is chromatography, the separation is performed only in the portion where the sample exists in the system, and the sample does not exist in the column or the tube at a certain time during the operation. The portions do not contribute to the separation, and the portions without the sample are relatively large, requiring a large separation system relative to the throughput. In the present apparatus, after reaching the steady state, the sample is distributed in all parts of the system, so that the useless part can be reduced. Further, since the sample is always supplied into the system in a steady state, the throughput is increased as compared with the case where the sample must be added intermittently as in chromatography. In addition, when trying to process more than the analytical amount of sample by chromatography, overloading (adding the sample at a concentration higher than the dilute solution where the distribution coefficient between the stationary phase and the mobile phase is kept constant) often occurs. This can be avoided by increasing the capacity.

Moreover, the countercurrent multistage extraction device widely used in the field of chemical engineering is originally intended for extraction and not for separation, and therefore, in many cases, the number of theoretical stages is 5 or less. In some cases, the purpose is satisfied, and a device having more than 5 stages is rare, and a system having 10 or more stages is usually not found. On the other hand, in the present apparatus, since there is no difficulty in adding a unit, it can be said that the separation ability is far superior to the ordinary multi-stage countercurrent extraction apparatus.

Further, in the present apparatus, the situation during separation, which is difficult with any of the above methods, can be measured by taking out a sample from an arbitrary unit.
From the results, it is possible not only to finely adjust the separation conditions, that is, the flow ratio of the two liquid phases, but also to increase or decrease the number of units in some cases.

In FIG. 2, the effect on the multistage extraction is the same even if the right and left are reversed. Although five units are illustrated in FIG. 2, the system can sequentially connect the units in a similar manner.
There is no limit on the number of units as a system.

[0039]

EXAMPLE An experiment was conducted in which malonic acid and glutaric acid were separated using a system having five units each of n and m. Each unit was prepared by processing a 100 ml reagent bottle. The solvent used for distribution is an n-butanol-water system in which n-butanol and water are equilibrated. The partition coefficients for the malonic and glutaric acids of the sample in this solvent system are 0.54 and 2.07, respectively, with a separation factor of 3.8.
It is. About 40 ml of the upper phase and the lower phase of this solvent system are added to each unit, and the n-butanol phase as the upper phase is added at a flow rate of 1.0 ml / min from the left end, and at the same time, the flow rate of the upper phase is 1. Pumped at 0 ml / min. Similarly,
An aqueous phase as a lower phase was also added from the right end at a flow rate of 1.0 ml / min, and the lower phase was pumped from the left end at a flow rate of 1.0 ml / min.

In this state, the sample was continuously injected into the central unit. The samples were malonic acid and glutaric acid, one for each.
A solution dissolved in the aqueous phase at a concentration of 0 mmole / l,
The flow rate was 0.1 ml / min. The operation was continued under these conditions, and malonic acid and glutaric acid eluted from the system were quantified. FIG. 3 shows the change in the concentration of each acid with respect to the operation time. After about 20 hours, when the concentrations of malonic acid and glutaric acid were respectively measured when they reached a substantially steady state, 18.8 μmoles of malonic acid were found in the n-butanol phase as the upper phase.
/ L and glutaric acid 851 μmole / l, and in the lower aqueous phase, malonic acid 834 μmole / l and glutaric acid 0.048 μmole / l.

Therefore, the purity of glutaric acid in the upper phase is 9
7.7% and the purity of malonic acid in the lower phase was 99.9% or more. This indicates that the system has a theoretical stage efficiency of at least n = m ≧ 4.

[0042]

As described above, the countercurrent multistage liquid-liquid extraction device of the present invention is obtained by connecting a plurality of units each having a simple structure for promoting the distribution between two liquid phases. The mixture can be separated at a resolution corresponding to chromatography without using a solid, and the throughput is not limited as long as there is a means capable of promoting the distribution of the substance between the two liquid phases by stirring or the like. There are advantages. Therefore, the extraction operation and the separation operation can be performed with high efficiency, and the separation operation of a large amount of the mixture can be performed reliably and efficiently by a simple operation.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a liquid-liquid extraction unit.

FIG. 2 is a system diagram showing an example of a countercurrent multistage liquid extraction device.

FIG. 3 is a graph showing changes in the concentrations of malonic acid and glutaric acid.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Liquid-liquid extraction unit, 2 ... Stirring container, 3 ... Light liquid separation sending part, 3a ... Liquid separation part, 3b ... Outlet, 4 ... Heavy liquid separation sending part, 4a ... Liquid separation part, 4b ... Outlet, 5 ... Light liquid introduction part, 6 ... Heavy liquid introduction part, 7 ... Rotor, 8 ... Lid, 9 ... Light liquid piping, 10 ... Heavy liquid piping, 11 ... Light liquid pump, 12 ... Light liquid storage tank, 13 ... heavy liquid collector, 14 ... heavy liquid pump, 15 ...
Heavy liquid storage tank, 16: pump, 17: light liquid collector, 18: sample pump, 19: sample storage tank, 20: magnetic stirrer

Claims (1)

[Claims] 1. A light liquid separation / delivery section for separating a light liquid and a heavy liquid and sending out the light liquid to a stirring vessel provided with a stirring means for stirring the light liquid and the heavy liquid for performing liquid / liquid extraction. And a heavy liquid separation / delivery section for separating the light liquid and the heavy liquid and sending the heavy liquid, a light liquid introduction section for introducing the light liquid into the stirring vessel, and a heavy liquid introduction for introducing the heavy liquid into the stirring vessel. And a liquid-liquid extraction unit to form a liquid-liquid extraction unit, and sequentially connect the light-liquid separation and delivery unit and the light-liquid introduction unit in a plurality of liquid-liquid extraction units,
A countercurrent multi-stage liquid / liquid extraction device, wherein the heavy liquid separation / delivery section and the heavy liquid introduction section are sequentially connected.