Method and apparatus for mixing two liquid phases.

Abstract

To provide a method of phase mixing of two liquid phases, capable of arbitrarily setting, a ratio of volume of each liquid phase which is subjected to phase mixing, completely independently from a ratio of a liquid feeding speed of each liquid phase in a practical functional relationship with respect to an extraction ratio and a reverse extraction ratio.SOLUTION: In operation for feeding two liquid phases into one reaction vessel for performing phase mixing, in the reaction vessel, a region of a phase mixing and a region of a phase separation are made coexist in a constant range.SELECTED DRAWING: Figure 6

Description

【Technical Field】 【0001】 The present invention relates to a phase mixing method and an apparatus therefor, characterized in that the ratio of the volumes of each liquid phase involved in phase mixing in one reaction vessel can be arbitrarily set completely independently of the ratio of the liquid feeding rates of each liquid phase, which is in an effective functional relationship with the extraction rate and the back-extraction rate. 【Background Art】 【0002】 Two-liquid phases composed of two immiscible liquid phases are widely used as a chemical technique such as solvent extraction. For example, as a method for separating and purifying metal elements and organic compounds, it supports the core industries such as the metal industry and the chemical industry, and is also one of the most important technologies as a technique for separating and purifying rare metals indispensable in the high-tech industry. 【0003】 On the other hand, in solvent extraction, entrainment (entrainment of droplets) of oil in the wastewater is likely to occur, and it is regarded as a method with a large environmental load. Also, depending on the conditions of the volume ratio of the aqueous phase and the oil phase to be mixed, the region involved in phase mixing (referred to as the mixed phase) may be unstable, the mixed phase may be difficult to flow, or phase separation after the extraction reaction may be difficult, resulting in inefficient progress of solvent extraction in some cases. 【0004】 Note that phase mixing is to mix two liquid phases that are immiscible with each other and form an interface by stirring, shaking, etc. As a result, if each liquid phase is refined and the area of the interface increases, an emulsion state is reached. In the emulsion state, the mass transfer between phases is promoted, so it becomes easier to reach the chemical equilibrium of the extraction reaction. As methods of phase mixing, stirring and shaking are common, but recently, a method of phase mixing by droplet ejection until an emulsion state is reached is also known (for example, Patent Document 1 and Patent Document 2). Phase separation is to separate the two liquid phases that have been phase mixed back into each liquid phase again. Natural separation using gravity and buoyancy, and mechanical separation using centrifugal force, etc. are common. 【0005】 In a batch test, where an aqueous phase containing the target component and an oil phase mainly composed of a solvent immiscible with water are placed in a fixed volume ratio in a container such as a test tube and shaken thoroughly until the extraction reaction reaches chemical equilibrium, the extraction rate of the target component into the oil phase depends on the volume ratio of the two phases at that time (here, the volume ratio of the oil phase to the aqueous phase at this time is called the effective oil phase / aqueous phase volume ratio). That is, at the chemical equilibrium of the extraction reaction, the extraction rate (=E%) and the effective oil phase / aqueous phase volume ratio (=R) are related. V The relationship between E% and R is given by the distribution ratio (the ratio of the concentration of the solute in the oil phase to the concentration of the solute in the aqueous phase = D), where E% = 100 × R V ×D / (R V This is a function represented by (×D+1). For example, to increase the extraction rate of the target component, you should increase the effective oil phase / aqueous phase volume ratio. 【0006】 In industrial processes where solvent extraction is performed continuously while supplying aqueous and oil phases, the ratio of the oil phase supply rate to the aqueous phase supply rate (referred to as the oil phase / aqueous phase supply rate ratio) usually corresponds to the oil phase / aqueous phase volume ratio involved in phase mixing (referred to as the oil phase / aqueous phase volume ratio in the mixed phase), and this coincides with the effective oil phase / aqueous phase volume ratio mentioned in relation to the batch test. In other words, in conventional continuous solvent extraction methods and apparatuses, the relationship is: oil phase / aqueous phase supply rate ratio = oil phase / aqueous phase volume ratio in the mixed phase = effective oil phase / aqueous phase volume ratio. 【0007】 In this case, the volume ratio of the two phases at the time of phase mixing, i.e., the volume ratio of the two phases in the mixed phase, is determined by the ratio of the fluid and oil flow rates. On the other hand, the physical properties of the mixed phase (stability, phase separation, fluidity, ease of entrainment, etc.) depend on the volume ratio of the fluid and oil phases that form the mixed phase. In other words, in conventional methods and apparatuses, the physical properties of the mixed phase are left to the ratio of the fluid flow rates of the two phases. [Prior art documents] [Patent Documents] 【0008】 [Patent Document 1] Patent No. 5305382 [Patent Document 2] Patent No. 5565719 [Overview of the Initiative] [Problems that the invention aims to solve] 【0009】 When two liquid phases are mixed in different volumes within a single reaction vessel, the smaller volume of liquid phase is more likely to be mixed with the other liquid phase as fine droplets. In other words, the smaller volume of liquid phase is more prone to what is known as entrainment (droplet entrainment). 【0010】 Furthermore, the physical properties of a mixed phase consisting of two liquid phases often differ significantly depending on the mixing ratio. For example, in the case of a mixed phase consisting of two liquid phases, an aqueous phase and an oil phase, the stability of the mixed phase, its flowability, the likelihood of entrainment, and the time required for phase separation can differ greatly depending on whether it is aqueous-phase rich or oil-phase rich. 【0011】 In particular, in multi-stage devices that repeat unit operations by setting multiple stages, the aforementioned susceptibility to entrainment and differences in the physical properties of the mixed phase greatly affect whether the device or plant can be operated. Specifically, problems may arise such as being unable to proceed to the next stage due to reasons such as inability to separate phases or flow, or being unable to remove impurities according to the set number of stages due to the effects of entrainment. 【0012】 In conventional phase mixing methods that create a phase-mixed region (mixed phase) throughout a single reaction vessel, the ratio of the volumes of the liquid phases forming the mixed phase within the vessel is equal to the ratio of the supply rates of each liquid phase. That is, liquid phases with slow supply rates have a smaller volume in the mixed phase, making them more susceptible to entrainment. Furthermore, depending on the ratio of the supply rates of each liquid phase, the mixed phase may become unstable or flow poorly, potentially causing operational problems. In addition, increased likelihood of entrainment or prolonged phase separation may lead to problems with wastewater treatment. 【0013】 In actual solvent extraction processes, it is often necessary to increase the flow rate of the oil phase to improve the extraction rate into the oil phase, or to increase the flow rate of the aqueous phase to improve the back extraction rate into the aqueous phase. Each time such adjustments are made, the aforementioned problems arise. Furthermore, these problems cannot always be solved, and in some cases the solvent extraction process itself may become unfeasible. 【0014】 Therefore, in order to solve these problems, after diligent research, we discovered that by utilizing a mechanism in which phase mixing and phase separation occur simultaneously in a single reaction vessel, even when the ratio of the volumes of each liquid phase involved in phase mixing is set arbitrarily and completely independently of the ratio of the liquid phase delivery rates, the ratio of the liquid phase delivery rates has an effective functional relationship with the extraction rate or back extraction rate. 【0015】 In other words, by adjusting the liquid delivery rate ratio, the extraction rate or back-extraction rate can be improved, and the volume ratio of the aqueous phase and oil phase involved in phase mixing can be arbitrarily set to a ratio that provides high stability, fluidity, and phase separation of the mixed phase, and is less prone to entrainment. 【0016】 Therefore, the object of the present invention is to provide a method and apparatus for two-liquid phase mixing in which the ratio of the volumes of each liquid phase involved in phase mixing can be arbitrarily set completely independently of the ratio of the liquid flow rates of each liquid phase, which is in an effective functional relationship with respect to the extraction rate and back extraction rate. Furthermore, the apparatus is designed with a strong focus on multi-stage systems, where the effects of the ease of entrainment and differences in the physical properties of the mixed phases become more pronounced. [Means for solving the problem] 【0017】 By utilizing a mechanism in which phase mixing and phase separation occur simultaneously in a single reaction vessel, the volume ratio of each liquid phase involved in phase mixing can be arbitrarily set completely independently of the flow rate ratio of each liquid phase, and the flow rate ratio of each liquid phase can be made to have an effective functional relationship with the extraction rate or back extraction rate. 【0018】 The fundamental feature of the present invention is that, in the operation of mixing two liquid phases while supplying them into a single reaction vessel, by allowing a phase mixing region and a phase separation region to coexist within a certain range in the reaction vessel, the oil phase / aqueous phase volume ratio in the mixed phase, in which the aqueous phase and oil phase participate in phase mixing in the phase mixing region (mixed phase), can be arbitrarily set completely independently of the oil phase / aqueous phase supply rate ratio. Here, the key point of the present invention is that the oil phase / aqueous phase supply rate ratio can ideally be considered identical to the effective oil phase / aqueous phase volume ratio, which is a parameter in the chemical equilibrium function with respect to extraction rate and back extraction rate. [Effects of the Invention] 【0019】 Conventionally, in terms of the stability, fluidity, phase separation, or entrainment of the mixed phase, it is often necessary to set the volume ratio of the aqueous phase to the oil phase involved in phase mixing under unfavorable conditions. However, with the method and apparatus of the present invention, it becomes possible to arbitrarily set the volume ratio under favorable conditions that do not cause these problems. 【0020】 Conventional methods utilize a mechanism in which the aqueous phase and oil phase are phase-mixed throughout the entire reaction vessel, and the mixed phase flows into a standing container located next to the reaction vessel, where gravity separates the two phases. In contrast, the method of the present invention eliminates the need for a standing container and eliminates the need to wait for the mixed phase to separate by gravity, as the mixed phase and the phase-separated aqueous and oil phases coexist within a certain range in the reaction vessel. 【0021】 Further, the gist of the present invention is as follows. In the conventional method, when changing the liquid feeding rate of the aqueous phase, the oil phase, or both, the volume ratio of the aqueous phase and the oil phase in the mixed phase also changes. Accordingly, the physical properties of the mixed phase and the state of entrainment also change. Therefore, in order to cope with this change, operations such as adjusting the interface position in the stationary container are essential. On the other hand, in the method of the present invention in which the volume ratio of the aqueous phase and the oil phase in the mixed phase is not affected by the liquid feeding rates of both phases, the physical properties of the mixed phase and the state of entrainment are always constant. Therefore, various adjustment operations (for example, adjusting the interface position in the stationary container) associated with the change in the liquid feeding rate, which are essential in the conventional method, are unnecessary. 【0022】 Furthermore, in the conventional method, since the aqueous phase and the oil phase are mixed throughout the entire reaction vessel, inevitably, the mixed phase (the region disturbed by phase mixing) comes into contact with air. On the other hand, in the method of the present invention, since the mixed phase is always located below the phase-separated oil phase (the undisturbed region), the disturbed mixed phase does not come into contact with air. Therefore, for example, when the target component that is easily oxidized (susceptible to the influence of oxygen in the air) is the subject of solvent extraction, the extraction operation can be performed while suppressing the influence. 【Brief Description of the Drawings】 【0023】 [Figure 1(A)] Relationships of the extraction rates of Tb, Dy, and Ho with respect to the effective oil phase / aqueous phase volume ratio in the batch test or the oil phase / aqueous phase liquid feeding rate ratio in the continuous flow test. [Figure 1(B)] Relationships of the extraction rates of Er, Tm, Yb, and Lu with respect to the effective oil phase / aqueous phase volume ratio in the batch test or the oil phase / aqueous phase liquid feeding rate ratio in the continuous flow test. [Figure 2] A mechanically stirred phase mixing unit having a structure that introduces the light liquid phase from above and discharges it from above while introducing the heavy liquid phase from below and discharging it from below, and having stirring liquid flow blocking plates above and below. [Figure 3]This is a mechanically agitated phase mixing unit that introduces a light liquid phase from below and discharges it from above, and introduces a heavy liquid phase from below and discharges it from below, with a stirring liquid flow shutoff plate only at the bottom. [Figure 4] A mechanically agitated phase mixing unit that introduces a light liquid phase from below and discharges it from above, and introduces a heavy liquid phase from below and discharges it from below, with agitated liquid flow shut-off plates at the top and bottom. [Figure 5] Figure 2 shows the distribution of phase mixing and phase separation regions in a unit of mechanically stirred phase mixing. [Figure 6] This is a three-stage mechanical agitation phase mixing device with agitation liquid flow shutoff plates at the top and bottom, which introduces and discharges the light liquid phase from the top and the heavy liquid phase from the bottom. [Figure 7] This is a three-stage mechanically agitated phase mixing device that introduces a light liquid phase from below and discharges it from above, and introduces a heavy liquid phase from below and discharges it from below, with a stirring liquid flow shutoff plate only at the bottom. [Figure 8] Figure 7 shows the distribution of phase mixing region and phase separation region in a three-stage mechanically agitated phase mixing apparatus. [Figure 9] This droplet-type phase mixing unit has upper and lower flow path cross-sectional area changing plates and operates by introducing a light liquid phase from below and discharging it from above, while introducing a heavy liquid phase from below and discharging it from below. [Figure 10] Figure 9 shows the distribution of phase mixing region and phase separation region in a unit of droplet-type phase mixing. [Figure 11] This is a three-stage droplet-type phase mixing device with flow path cross-sectional area changing plates at the top and bottom, which works by introducing a light liquid phase from below and discharging it from above, and introducing a heavy liquid phase from below and discharging it from below. [Figure 12] The distribution of phase mixing region and phase separation region in a three-stage droplet-type phase mixing apparatus shown in Figure 11. [Modes for carrying out the invention] 【0024】 Typically, the volume ratio of the aqueous phase to the oil phase in a phase mixing region during solvent extraction is equal to the ratio of the fluid delivery rates of the aqueous and oil phases into that phase mixing region. For example, in the mixer section of a mixer-settler, a typical device for industrial solvent extraction, the entire section constitutes a phase mixing region (mixed phase), and the mixed volume ratio (volume ratio of both phases in the mixed phase) and the fluid delivery rate ratio (ratio of fluid delivery rates of both phases) are equal. 【0025】 Furthermore, in this case, the oil phase / water phase delivery rate ratio is equal to the oil phase / water phase volume ratio in the phase mixing region (mixed phase), and can be considered identical to the effective oil phase / water phase volume ratio (oil phase / water phase volume ratio in the batch test mentioned above), which is functionally related to the extraction rate and back extraction rate. In fact, when the liquid in the phase mixing region (mixed phase) is sampled using a dispenser such as a pipette and then separated into phases, the oil phase / water phase volume ratio at that time coincides with the oil phase / water phase delivery rate ratio. 【0026】 On the other hand, if the phase mixing region within the reaction vessel in which the aqueous and oil phases participate in phase mixing is partial and remains within a certain range, then the relationship that the mixing volume ratio and the liquid delivery rate ratio are equal does not hold. In other words, in a system where phase mixing and phase separation proceed simultaneously within a single reaction vessel, and each region coexists within a certain range, the ratio of the liquid delivery rates of the aqueous and oil phases can be freely changed while maintaining a constant volume ratio of the aqueous and oil phases in the phase mixing region. 【0027】 In this case, when the liquid in the phase-mixed region (mixed phase) was actually sampled using a pipette or other dispenser and then separated into phases, the oil phase / aqueous phase volume ratio remained constant, independent of the oil phase / aqueous phase delivery rate ratio. Therefore, the oil phase / aqueous phase delivery rate ratio has not been discussed in relation to the effective oil phase / aqueous phase volume ratio (the oil phase / aqueous phase volume ratio in the batch test mentioned above). In other words, the oil phase / aqueous phase volume ratio in the mixed phase is maintained independently of the oil phase / aqueous phase delivery rate ratio, remaining the same as the volume ratio of both phases installed in the apparatus container. Consequently, it was difficult to imagine that a difference in the "mixing method"—specifically, a difference in delivery rate—could cause a difference in the effective oil phase / aqueous phase volume ratio, which should conventionally be the same as the oil phase / aqueous phase volume ratio in the mixed phase, while the oil phase / aqueous phase volume ratio in the mixed phase remained unchanged. 【0028】 For example, if the volume ratio of the oil phase to the water phase in the phase mixing region (the oil phase / water phase volume ratio in the mixed phase) is set to 1 / 1, and the water phase delivery rate is kept the same while only the oil phase delivery rate is increased, the extraction rate will indeed increase. However, this was interpreted as a phenomenon that occurred because phase mixing was promoted and the mixture approached chemical equilibrium. In other words, in the above, it was assumed that the effective oil phase / water phase volume ratio was always 1 / 1. Therefore, in a mechanism where phase mixing and phase separation coexist within a certain range in the same reaction vessel, the relationship between the effective oil phase / water phase volume ratio and the oil phase / water phase delivery rate ratio had never been considered until now. 【0029】 On the other hand, even if the oil / water volume ratio in the mixed phase remains constant, if, for example, the oil phase's fluid rate ratio relative to the water phase increases, the oil phase will have more opportunities to come into contact with the water phase at a frequency corresponding to that fluid rate ratio. Therefore, while the oil / water volume ratio in the mixed phase remains constant, it is also possible to consider the oil / water fluid rate ratio as corresponding to the effective oil / water volume ratio mentioned above. 【0030】 The first significance of the present invention lies in the discovery that, even in cases where the volume ratio of the oil phase to the aqueous phase in the phase mixing region (the oil phase / aqueous phase volume ratio in the mixed phase) is always kept constant regardless of the pumping rates of both phases, the oil phase / aqueous phase pumping rate ratio corresponds to the effective oil phase / aqueous phase volume ratio (the oil phase / aqueous phase volume ratio in the batch test described above). In fact, in a mechanism where phase mixing and phase separation proceed simultaneously within a single reaction vessel, it was found that even though the oil phase / aqueous phase volume ratio in the mixed phase is constant, the oil phase / aqueous phase pumping rate ratio corresponds to the effective oil phase / aqueous phase volume ratio, and the extraction rate of rare earth elements changes according to this pumping rate ratio. The results are shown in Example 1. [Examples] 【0031】 Rare earth extraction test using droplet ejection unit. 【0032】 As the aqueous phase, a pH 2 aqueous nitric acid solution containing Tb, Dy, Ho, Er, Tm, Yb, and Lu at concentrations of 100 ppb each was prepared. As the oil phase, an organic solution was prepared by dissolving 35 mM (2-ethylhexyl)phosphonate 2-ethylhexyl (PC88-A) in a mixed solvent of 90 vol% D70 (alkane solvent) and 10 vol% 2-ethylhexanol. These solutions were used in the rare earth extraction test described below. The rare earth elements extracted into the oil phase were back-extracted with a 0.5 M aqueous nitric acid solution, and their concentrations were measured using an inductively coupled plasma atomic emission spectrometer (ICP-OES). 【0033】 Continuous flow tests using droplet-type unit spraying were conducted to determine the extraction rate (%) of the rare earth elements relative to the oil phase / water phase flow rate ratio. This was then compared with the extraction rate (%) of the rare earth elements relative to the effective oil phase / water phase volume ratio obtained in batch tests. In other words, the study verified whether the change in the oil phase / water phase flow rate ratio in the continuous flow tests corresponds to the change in the effective oil phase / water phase volume ratio in the batch tests, and whether changing the oil phase / water phase flow rate ratio yields the same rare earth element extraction rate (%) as when the effective oil phase / water phase volume ratio is changed. 【0034】 First, in the continuous flow test, the oil phase flow rate was fixed at 30 mL / min, and the water phase flow rate was varied to 7.5, 15, 30, 60, and 90 mL / min. In this case, the oil phase / water phase flow rate ratio (= oil phase flow rate / water phase flow rate) was 4, 2, 1, 1 / 2, and 1 / 3, respectively. 【0035】 Furthermore, in this continuous flow test, the oil phase / water phase volume ratio in the phase mixing region (mixed phase) was set to 1 / 1. That is, the droplet ejection unit was equipped with equal volumes of water phase and oil phase. Note that the oil phase / water phase volume ratio in the mixed phase can be arbitrarily set by the volume ratio of the water phase and oil phase installed. 【0036】 On the other hand, in the batch test, the effective oil phase / aqueous phase volume ratio (the actual oil phase / aqueous phase volume ratio added to the test tube) was set to 4, 2, 1, 1 / 2, and 1 / 3, similar to the continuous flow test, and the mixture was shaken thoroughly until the extraction reaction reached chemical equilibrium. 【0037】 Furthermore, in the continuous flow test, each time the oil phase / aqueous phase transfer rate ratio was changed, a sample of the mixed phase was taken with a pipette to confirm that the oil phase / aqueous phase volume ratio remained unchanged from the set value of 1 / 1. 【0038】 Figures 1(A) and 1(B) show a comparison of the results of the continuous flow test and the batch test. Figure 1(A) shows the results for Tb, Dy, and Ho, while Figure 1(B) shows the results for Er, Tm, Yb, and Lu. 【0039】 The extraction rate (%) of each rare earth element in the continuous flow test is slightly lower than that in the batch test because the extraction reaction does not reach chemical equilibrium. However, the relationship between the oil phase / water phase flow rate ratio in the continuous flow test and the effective oil phase / water phase volume ratio in the batch test is in good agreement with the rare earth element extraction rate (%). In other words, it has been shown that, ideally, the oil phase / water phase flow rate ratio can be considered equivalent to the effective oil phase / water phase volume ratio. 【0040】 In conventional continuous phase mixing (for example, phase mixing in a mixer-settler), the oil phase / water phase transfer rate ratio, which can be considered the effective oil phase / water phase volume ratio, uniquely coincides with the oil phase / water phase volume ratio in the mixed phase. However, the results shown in Example 1 show that, according to the method of the present invention, the effective oil phase / water phase volume ratio can be freely changed by the oil phase / water phase transfer rate ratio while arbitrarily setting the oil phase / water phase volume ratio in the mixed phase (for example, 1 / 1). 【0041】 As mentioned above, the present invention is based on phenomena that occur in a mechanism in which phase mixing and phase separation proceed simultaneously within a single reaction vessel. Therefore, examples of apparatus in which phase mixing and phase separation proceed simultaneously within a single reaction vessel are shown below with specific diagrams, but this is not limited to these examples. 【0042】 In the diagrams shown below, the distinction between heavy liquid phase and light liquid phase is used, rather than between aqueous phase and oil phase. This is because, in the mechanism of the apparatus of the present invention, it is important to know which liquid phase has a higher specific gravity and is located below it across the interface. In many cases, the oil phase is lighter than the aqueous phase, but conversely, there are also oil phases that are heavier than the aqueous phase. In other words, the oil phase is not necessarily a light liquid phase, and the aqueous phase is not necessarily a heavy liquid phase. 【0043】 There are differences in the phase separation mechanism between a system that mixes phases by mechanical stirring (referred to as the mechanical stirring type) and a system that mixes phases by droplet ejection (referred to as the droplet ejection type). 【0044】 When phase mixing is performed by mechanical stirring, phase separation can be promoted by altering the flow generated by the rotation of the stirring blades. Examples of such apparatus are shown in Figures 2, 3, and 4, but are not limited to these. 【0045】 Figure 2 shows a mechanical agitator phase mixing device in which the agitator blades are positioned slightly below the device container, and the light liquid phase is introduced from above by pump and discharged from above, while the heavy liquid phase is introduced from below by pump and discharged from below. The device has two agitation liquid flow shutoff plates at the top and bottom. This device is a unit that can be connected in series and can be assembled as a multi-stage device with any number of stages (see Figure 6). 【0046】 Figure 3 shows a mechanical agitator with the same arrangement of agitator blades as in Figure 2. It is a mechanical agitator-type phase mixing device that pumps in the light liquid phase from below and discharges it from above, while simultaneously pumping in the heavy liquid phase from below and discharges it from below. It has two agitated liquid flow shutoff plates only at the bottom. This device, like Figure 2, is a unit that can be connected in series and can be assembled as a multi-stage device with any number of stages (see Figure 7). 【0047】 Figure 4 shows a mechanical agitator with the same arrangement of agitator blades as in Figures 2 and 3. It is a mechanical agitator-type phase mixing device that pumps in the light liquid phase from below and discharges it from above, while simultaneously pumping in the heavy liquid phase from below and discharges it from below. It has two agitation liquid flow shutoff plates at the top and bottom. This device, like Figures 2 and 3, is a unit that can be connected in series and can be assembled as a multi-stage device with any number of stages (not shown). 【0048】 Below, as Example 2, we show an example of the distribution of coexisting phase-mixing regions and phase-separating regions within a mechanically stirred unit device. [Examples] 【0049】 Distribution of phase mixing region and phase separation region in a mechanically agitated unit device 【0050】 Figure 5 shows the results of investigating the distribution of phase mixing and phase separation regions when the apparatus shown in Figure 2 was selected as a representative example, and heavy liquid phase and light liquid phase were placed in the apparatus in equal volumes and operated as described above. Water containing inorganic salts was used as the heavy liquid phase, and D70 (an alkane solvent) was used as the light liquid phase. The impeller of the mechanical stirrer was positioned slightly below the liquid-liquid interface. It was found by actually sampling the mixed phase with a pipette that the volume ratio of the light liquid phase to the heavy liquid phase in the mixed phase generated by mechanical stirring was always 1 / 1, regardless of the light liquid phase / heavy liquid phase transfer rate ratio. Note that if the position of the mechanical stirrer's impeller is raised or lowered too much, the volume ratio of the light liquid phase to the heavy liquid phase in the mixed phase will not be 1 / 1, so the impeller needs to be positioned appropriately. 【0051】 As shown in Figure 5, in the apparatus of Figure 2, a phase mixing region occurred in a cross shape in the center of the apparatus container. Due to the action of the stirring liquid flow blocking plates, two each installed above and below, the stirring liquid flow generated by the rotation of the stirring blades was blocked, resulting in the appearance of two phase separation regions in the lower part of the apparatus container (right and left) and three in the upper part of the apparatus container (right, left, and upper center). Furthermore, although the ratio of the phase mixing region to the phase separation region fluctuated slightly by changing the rotation of the stirring blades, the ratio of these two regions was not affected by the light liquid phase / heavy liquid phase transfer rate ratio. 【0052】 Figures 2, 3, and 4 show a mechanically agitated phase mixing apparatus, designed as a unit structure that facilitates multi-stage construction. As examples of multi-stage construction, Figure 6 shows a multi-stage (3-stage) apparatus using Figure 2 as the unit, and Figure 7 shows a multi-stage (3-stage) apparatus using Figure 3 as the unit, but this is not the only example. 【0053】 Figure 6 shows a three-stage apparatus based on the unit shown in Figure 2, with each stage separated by a partition plate. The upper and lower parts of the partition plate are connected, and the light liquid phase moves to the next stage through the upper connecting port, while the heavy liquid phase moves through the lower connecting port. 【0054】 Figure 7 shows a three-stage apparatus with Figure 3 as the unit, and, similar to Figure 6, each stage is separated by a stage partition plate. In Figure 6, the upper and lower parts of the stage partition plate are connected, but in Figure 7, the upper part is not connected, and the light liquid phase moves to the next stage by pumping rather than through a connecting port. On the other hand, the heavy liquid phase moves to the next stage through the lower connecting port, similar to Figure 6. 【0055】 Furthermore, as Example 3, we show an example of the distribution of coexisting phase-mixing regions and phase-separating regions in a mechanically stirred multi-stage apparatus. [Examples] 【0056】 Distribution of phase mixing and phase separation regions in a mechanically agitated multi-stage apparatus 【0057】 As an example of a mechanically agitated multistage apparatus, Figure 8 shows the distribution of phase mixing and phase separation regions in a three-stage apparatus shown in Figure 7, where equal volumes of heavy liquid phase (water containing inorganic salts) and light liquid phase (D70) are placed within the apparatus. The stirring blades of the mechanical agitator were positioned slightly below the liquid-liquid interface in each stage. Furthermore, it was found that, similar to the unit-type apparatus, the volume ratio of light liquid phase to heavy liquid phase in the mixed phase was always 1 / 1 in all stages, regardless of the light liquid phase / heavy liquid phase transfer rate ratio (the mixed phase was actually sampled with a pipette). 【0058】 As shown in Figure 8, in the apparatus of Figure 7, a phase mixing region was generated in the form of a T-shape connected in series. The action of the two stirring liquid flow blocking plates installed below each stage blocked the stirring liquid flow generated by the rotation of the stirring blades, resulting in the creation of two phase separation regions (right and left) below each stage. At the connection points of each stage, the left and right phase separation regions (both heavy liquid phase phase separation regions) are connected via a communication port provided below the stage partition plate. On the other hand, although no stirring liquid flow blocking plates are installed on top of the apparatus, when the light liquid phase was pumped from below, the light liquid phase easily separated. 【0059】 Next, an example of an apparatus where phase mixing is performed by droplet ejection is shown. In the droplet ejection method, phase separation can be promoted by increasing the cross-sectional area of ​​the part through which the flow generated by droplet ejection passes. An example of such an apparatus is shown in Figure 9, but this is not the only example. 【0060】 Figure 9 shows a droplet-type phase mixing device in which a light liquid phase is introduced from below through a droplet ejector and pumped in while being discharged from above, and at the same time, a heavy liquid phase is introduced from below and discharged from below while being pumped in. This device has one flow path cross-sectional area changing plate at the top and one at the bottom. This device is a unit that can be connected in series and can be assembled as a multi-stage device with any number of stages (see Figure 11). 【0061】 Below, as Example 4, we show an example of the distribution of coexisting phase-mixed regions and phase-separated regions within a droplet-type unit device. [Examples] 【0062】 Distribution of phase mixing region and phase separation region in a droplet ejection type unit device 【0063】 Figure 10 shows the results of investigating the distribution of phase mixing regions and phase separation regions when a heavy liquid phase (water containing inorganic salts) and a light liquid phase (D70) were placed in equal volumes within the droplet ejection type unit device shown in Figure 9 and operated as described above. It was found by actually sampling the mixed phase with a pipette that the volume ratio of the light liquid phase to the heavy liquid phase in the mixed phase generated by droplet ejection is always 1 / 1, regardless of the light liquid phase / heavy liquid phase delivery rate ratio. 【0064】 As shown in Figure 10, the apparatus in Figure 9 can generate a wide-ranging phase-mixed region. The mixed phase generated by droplet ejection can be separated by increasing the cross-sectional area of ​​the part through which the flow passes. Furthermore, the phase-separated region appears on either the upper or lower left or right side of the apparatus container. Moreover, even when the delivery rate of the heavy liquid phase, the light liquid phase, or both was changed, the ratio of the phase-mixed region to the phase-separated region hardly changed as long as the delivery rate was within an appropriate range (as long as the delivery rate was not too fast relative to the apparatus size). Similarly, the ratio of these two regions was hardly affected by the light liquid phase / heavy liquid phase delivery rate ratio as long as the delivery rate was within an appropriate range. 【0065】 Figure 9 shows a droplet-type phase mixing apparatus, designed as a unit with a structure that facilitates multi-stage construction. As an example of multi-stage construction, Figure 11 shows a multi-stage (3-stage) apparatus using Figure 9 as the unit, but this is not the only example. 【0066】 Figure 11 shows a three-stage apparatus with Figure 9 as the unit, where each stage is separated by a partition plate. However, the upper parts of the partition plates are not connected, only the lower parts are connected. In other words, the light liquid phase moves to the next stage by pumping rather than through a connecting port, while the heavy liquid phase moves to the next stage through a connecting port at the bottom. 【0067】 Furthermore, as Example 5 below, we show an example of the distribution of coexisting phase-mixed regions and phase-separated regions within a droplet-type multi-stage device. [Examples] 【0068】 Distribution of phase mixing and phase separation regions in a droplet-type multi-stage device 【0069】 As an example of a droplet-type multistage apparatus, Figure 12 shows the distribution of phase mixing regions and phase separation regions when equal volumes of heavy liquid phase (water containing inorganic salts) and light liquid phase (D70) are placed inside the multistage (3-stage) apparatus shown in Figure 11. It was found that, similar to the unit-type apparatus, the volume ratio of light liquid phase to heavy liquid phase in the mixed phase is always 1 / 1 in all stages, regardless of the light liquid phase / heavy liquid phase delivery rate ratio (the mixed phase was actually sampled with a pipette). 【0070】 As shown in Figure 12, it was found that even with a multi-stage apparatus, a wide area of ​​phase mixing can be generated, similar to a single unit. The mixed phase generated by droplet ejection at each stage can be separated by increasing the cross-sectional area of ​​the part through which the flow passes, and the phase separation area appears either on the upper or lower left or right side of each stage. The separated heavy liquid phase moves to the next stage through a communication port provided at the bottom of the stage partition plate separating each stage, while the light liquid phase moves to the next stage not through the communication port, but by pumping. [Industrial applicability] 【0071】 This invention relates to a novel method for mixing two liquid phases and an apparatus (particularly a multi-stage apparatus) utilizing this method, and is expected to be used in a wide range of industrial fields, such as solvent extraction and oil-water separation. For example, it is expected to be used as a separation and purification technology in key industries such as the metal industry and the chemical industry, as well as in the manufacture of high-tech components that require rare metals, such as lithium-ion batteries and neodymium magnets, and in rare metal recycling. [Explanation of symbols] 【0072】 1: Stirring liquid flow shutoff plate 2: Flow channel cross-sectional area changing plate 3: Mechanical stirrer 4: Tier divider 5: Droplet ejector

Claims

[Claim 1] A phase mixing method in which, while continuously flowing a light liquid phase and a heavy liquid phase that do not mix with each other into a container, the two phases are continuously mixed in a desired volume ratio by continuous flow, and at the same time, the two phases are separated to perform solvent extraction, and in which a region of phase mixing is generated between the regions where the light liquid phase has been separated, or between the regions where the heavy liquid phase has been separated, or both, A phase mixing method characterized in that the rate ratio of the light liquid phase to the heavy liquid phase in the continuous flow transfer can be effectively identified with the light liquid phase to heavy liquid phase volume ratio included in a function of the extraction rate or back extraction rate in a state where extraction equilibrium is reached in a batch, regardless of any arbitrary volume ratio in the phase mixing by the continuous flow. [Claim 2] A method of phase mixing according to claim 1, characterized in that the phase mixing region is formed below or to the side of the phase-separated light liquid phase, or both, and above or to the side of the phase-separated heavy liquid phase, or both. [Claim 3] A method for phase mixing according to claim 1 or 2, characterized in that the phase mixing is performed by mechanical stirring or droplet ejection.

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