JPS63205103A - Mixer settler extractor with porous wall - Google Patents

Abstract

PURPOSE:To reduce the volume of a setter to shorten extraction time and, obtain an extractor with high extraction efficiency by forming a porous wall of porous material in a partition between a mixer room and a settler room. CONSTITUTION:A mixer settler extractor with a porous wall 1 is composed of a mixer room 2, a settler room 3 and a porous material layer 4 which is arranged between both rooms and filled with, for instance, cubic particles of less than 1cm diameter in a laminar form. A stirrer 5 is provided in the mixer room 2. Subsequently, the residence time of an extract liquid in an extractor 1 becomes short by reduction of the volume of the settler room 3. Thus a continuous multi-stage extractor is operated efficiently.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a porous walled mixer settler extractor.

(Prior art) In general, a mixer-settler extractor includes a mixer chamber that performs a mixing and stirring operation between two different liquid phases to extract the target substance in one liquid phase into the other phase, and a mixer chamber that is connected to the mixer chamber and mixes and disperses the target substance in one liquid phase in order to extract the target substance in the other phase. It consists of a settler chamber that separates the liquid phase into the original two liquids. This type of extractor has the advantage that extraction equilibrium is achieved relatively easily due to sufficient stirring in the mixer chamber, and the stage efficiency per unit is over 95% in extraction equilibrium achievement rate. ing. For this reason, mixer-settler extractors have been used on a particularly large scale in nuclear fuel refining and reprocessing, etc., and include the gravity type, which has the simplest structure, the pump-type mixer-settler extractor, which has a large processing flow rate, and even the high-speed processing type. A centrifugal mixer and one spatula extractor have been developed.

In order to use a mixer settler as a multi-stage continuous extractor, it is necessary to select the optimal type in terms of structure and operability. Generally speaking, the gravity type is difficult to multistage, and the centrifugal type has a too complicated structure, so the pump type is often used. However, the pump-type mixer-settler-extractor has hitherto had a drawback in that the volume of the settler chamber is 3 to 10 times larger than that of the mixer chamber.

Incidentally, the increase in the amount of the extractor and the amount of solvent contained therein poses the following problems, particularly in the reprocessing of nuclear fuel. Specifically, the residence time in the extractor becomes longer and the organic solvent undergoes radiolysis, and the amount of nuclear fuel material that accumulates in the equipment increases, requiring greater attention to criticality safety. However, problems such as the increase in the size of the shield that envelops the entire extraction device, etc., have been a cause of reducing the economic efficiency of reprocessing plants using mixer cement. In addition, in principle, the mixer settler extraction method should be as effective as the ion exchange column method for the purpose of analysis and separation of general chemical samples, but the large settler portion makes it difficult to use as a separator. This reduces efficiency and is therefore not widely used in practice.

In conventional mixer settler extractors, the overflow passes over a partition plate that separates the mixer and settler chamber, or a window is opened in the partition plate, and this window serves as a passage for the mixed liquid. It has become. In the extraction operation, two different phases, such as an aqueous phase and an organic phase, are first supplied to the mixer chamber, mixed by a stirrer, and one phase is dispersed in the other phase as droplets, forming a so-called dispersed phase. . Another role of stirring is to create a circulating flow within the mixer chamber. Since the extraction reaction progresses while the dispersed phase circulates within the mixer chamber, one way to increase the efficiency of extraction is to increase the rotational speed of the stirrer and increase the circulating flow rate. As the rotation speed of the stirrer increases, the dispersed phase droplets become smaller, but if the dispersed phase droplets become too small, the time required for the droplets to coagulate in the settling chamber and separate into the original two phases becomes longer and the extractor Overall efficiency decreases. Roughly speaking, when the droplets become small and become emulsified, they do not easily return to the original two-phase state and simply flow out of the extractor, making separation impossible. Therefore, the liquid in the settler chamber-
An appropriate stirring speed is selected depending on the ability of liquid phase separation.

The formation of a dispersed phase by stirring is interpreted as the kinetic energy imparted to a fluid by stirring partially becoming surface energy to form droplets.

Therefore, in order for the mixed solvent containing the dispersed phase to quickly return to its original two-phase state, it is important to quickly remove the kinetic energy of the dispersed phase and the surface energy of the liquid layer released from the mixture.

In the conventional method, the dispersed phase directly brings the kinetic energy and surface energy obtained in the mixer chamber into the settling chamber, so I'! is required for the release of these energies in the settling chamber. It took 1 minute. That is, in order to secure the release time, it was necessary to lengthen the residence time of the molten W in the settling chamber. If the retention time is not long enough, a so-called flooding phenomenon occurs in which the mixed dispersed phase does not separate into two phases and flows out of the extractor. This was the reason why the settler volume was large in conventional mixer settler extractors. Conventionally, a baffle plate has been placed in the settling chamber to suppress the spread of the dispersed phase, but the effect of the baffle plate is to allow the dispersed phase to accumulate in a part of the settling chamber, and essentially prevents the spread of the dispersed phase itself. It is known that it does not reduce volume.

Next, the particle size of the droplets generated by the rotation of the stirrer in the mixer chamber is widely distributed from small to large, and larger droplets have a slower rate of achieving extraction equilibrium, which is the rate-limiting factor for the extraction reaction in the mixer chamber. Become. In addition, if the rotational speed of the stirrer is increased to eliminate large droplets, very fine droplets will be generated, and although the extraction time will be shortened, there is a problem that it will take time for the droplets to coagulate in the settler.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and its purpose is to provide a mixer settler extractor that reduces the settler volume, shortens the extraction time, and has high extraction efficiency. be.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a pump-type mixer-settler extractor equipped with a mixer chamber having an agitator and a settler that communicates with the mixer chamber. The mixer-settler extractor with porous walls is characterized in that a porous wall made of porous material is formed in at least a part of the partition between the mixer chamber and the settler, and the mixer-settler extractor with porous walls Another feature is that the vessels are constructed in multiple stages.

Next, the principle of the present invention will be explained.

If a partition wall made of an appropriate porous material is provided between the mixer chamber and the settler chamber instead of leaving it open, this porous wall will provide appropriate resistance to the flow of the two-phase mixed liquid containing the dispersed phase, which is different from the conventional method. Unlike baffles, they absorb the kinetic energy of fluid. Furthermore, the porous walls form narrow channels within them and thus have a large surface area, and while the dispersed phase droplets flow through these narrow channels, they collide with the surrounding walls and lose surface energy of the droplets. This causes the droplets to aggregate into larger droplets.

Absorption of kinetic energy and aggregation due to droplet collisions described above are the main functions of the porous walls.

In addition, as another function, there is a classification (sieving) function of the porous walls on the dispersed phase liquid). That is, among the droplets that reach the porous wall surface in the mixer chamber, droplets with a cross section smaller than the surface pore cross section immediately flow into the pore, but droplets with a cross section larger than the pore also flow into the mixer chamber. A portion of the particles that have been split into small particles flows into the porous wall, and the remainder returns to the mixer chamber and circulates. Therefore, in order to eliminate large liquid particles, it is not necessary to increase the rotational speed of the stirring mold so high, and there is no need to create extremely small droplets.

Roughly speaking, if the inside of the porous wall has a structure of a filled layer or a stack of perforated plates, the dispersed mixed phase flows through the packed phase with a large surface area, so mixing contact between the two phases is promoted here. As a side effect, the extraction reaction can be expected to proceed as quickly as in a packed column.

The pore size of the porous wall is important for the reasons mentioned above. Note that if it is too large, it will not function as a porous wall.

The porous wall structure of the present invention is the optimum condition determined as a result of such studies. If the tmm waiting time is 1 minute or less, the extraction equilibrium is reached for droplets with a radius of 3 mm or less, so it is necessary that these droplets have a porous wall through which they can pass. That is, the radius is 3 mm or less or the cross-sectional area is 3
Holes of approximately 0 mm2 or less are used. In the case of an extraction process that requires a long temperature time (in the mixer), the diameter of the droplet becomes large, and therefore the large cross section of the pore wall becomes large. For example, if the residence time is about 10 minutes, the maximum cross section of the droplet is 100.
It may be as large as mm2, and holes of this size are useful.

In the actual production of porous walls, it is inevitable that there will be a distribution in the size of beads serving as raw materials and the size of the pores in the porous plate. The amount of beads and holes that fall outside the range stated in the claims is acceptable if the sum of their cross-sectional areas h1 is within 10% of the total cross-sectional area of the beads and holes, and there is no significant deterioration in the characteristics. Ru.

However, in the case of small-sized glass beads, since they are densely packed, the flow resistance of the liquid passing through them is large.

Furthermore, the material of the porous walls may be any material as long as it is physically and chemically stable to the solutions and solvents that come into contact with it; for example, stainless steel, ceramic, glass, fluorocarbon resin, etc. are commonly used and desirable materials. It is the material. Other various metal materials.

Carbon materials, organic plastic materials, etc. may also be used. Roughly speaking, the porous wall is preferably made of one or two or more overlapping nets or cloths, and the average lattice spacing of the octa or ifi mesh is 10 mm or less.

By the way, the results of introducing a porous wall into the mixer-settler extractor are shown in the examples, but the settler chamber, which conventionally required more than three times the volume of the mixer chamber, is now smaller than the mixer chamber, and the settler chamber and the porous wall part are now smaller than the mixer chamber. The combined volume of the equipment is approximately the same or smaller than that of the mixer chamber. Further, the amount of extraction processing liquid held in the porous wall portion and the settler chamber is about half of the amount held within the mixer, making solvent extraction much more efficient. Furthermore, by reducing the volume of the settler chamber, the residence time of the extract in the mixer settler becomes shorter, resulting in 0.0% per stage.
It will also be possible to set it to about 5 to 1 degree. Therefore, a continuous extractor in which 10 to 20 mixer settlers are connected can be operated very efficiently.

(Function) According to the mixer-settler extractor with porous walls of the present invention, the settler chamber is smaller than the mixer chamber, and the residence time of the extract in the mixer-settler is shortened due to the reduction in the volume of the settler chamber of the parentheses, and 10 to 20 stages are connected. The continuous extractor can be operated very efficiently.

(Example) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1(a) is a schematic configuration diagram of an embodiment of the present invention,
In the figure, a mixer settler extractor 1 with a porous wall is composed of a mixer chamber 2, a settler chamber 3, and a porous layer 4 disposed between the two chambers. 5 is provided. Further, the mixer chamber is provided with nozzles 5a and 5b through which liquids of different two phases flow into the mixer chamber.

On the other hand, the settling chamber is provided with a nozzle 7a and a nozzle 7b for taking out the phase-separated two liquids.

The above-mentioned porous layer may be a layer filled with spherical particles having a diameter of 1 cm or less or particles volumetrically equivalent thereto, or a porous layer formed by sintering particles of this shape into a plate shape (first
Figure b), or one or two or more overlapping nets or cloth-like items, with an average mesh lattice spacing of 1
A porous wall with a diameter of 0 mm or less (Figure 1C), or a porous wall with at least one plate or thin film having a large number of penetrating pores with a cross-sectional area of 100 mm or less (Figure 1) d) may also be used.

FIG. 2 is a schematic configuration diagram of another embodiment of the present invention, and this figure shows a case where uranium is purified using the porous wall mixer settler extractor 1. Mixer chamber 2 has an effective volume of 101
The settler chamber 3 has an effective volume 41, and between them, glass beads 4a (average diameter 2ml) are filled to a thickness of 1cm, and in contact with it, large glass beads 4b (average diameter 5mm) are filled to a thickness of 1.3cm. A porous layer 4 is provided. Hexavalent uranium (uranyl nitrate) O,17/
3mnf7/β nitric acid aqueous solution containing β concentration and TBP30
1 oe of n-dodecane solvent containing V% for both aqueous solution and solvent
The mixture was supplied to the mixer chamber 2 at a flow rate of /min. The agitator 5 in the mixer chamber 2 has four blades with a pitch of 10 cm and a rotation speed of 500 r.
It was pm.

Under these conditions, the dispersed phase did not cause flooding, and the aqueous solution and solvent were separated into each phase from the settler chamber 3 and taken out of the extractor 1. In addition, in a single-stage extraction operation under these operating conditions, the uranium extraction efficiency is 95%, and the processing time (residence time from entering the mixer chamber to exiting the settling chamber)
was about 45 seconds.

FIG. 3 is a schematic diagram showing the structure of the porous wall mixer-settler extractor 1 in multiple stages.

Mixer extractor with porous wall IA, 1B, IC, II
) b<4 The extractor is connected via a pump 8 that transfers two-phase liquid between the extractors. Each mixer settler extractor 1
8. IB, IC, 1 [) is a mixer chamber 28 with an effective volume of 500 m1.

2B, 2C, 2D and settling room 3 with effective volume of 200d
, 38.3C.

Five 0.1 mm thick stainless steel perforated plates (holes with a diameter of 0.2 mm are actually bored) are stacked at 1 mm intervals between them, and are connected to each other with a diameter of 1 mm. Porous layers 4A, 48.4C, and 40 are provided by stacking stainless steel plates with holes of 2, 3, and 4.5 mm in this order at 1 mm intervals. 0.5m0f for the first stage extractor 1A! /j! 3 mnj7 / containing uranyl nitrate (U 120 (] /! )
mixer with a flow of 1 nitric acid aqueous solution 500d/min. 2A, the same phase is handled by the pump 8 from the settler chamber 3^, and sent to the mixer ¥2B of the second stage extractor 1B. On the other hand, n-dodecane solvent containing 30 V% of TBP is supplied to the fourth stage mixer chamber 2D at a flow rate of 5007/min, and the same phase is bagged from the fourth stage's third stage mixer chamber 3D. Send to 2C. In this way, uranium was extracted by countercurrent contact using a four-stage mixer settler extractor.

As a result, the uranium concentration of the aqueous solution discharged from the mixer settler extractor in the fourth stage was 0.01 cl/! = 10 ppm, and the uranium concentration in the organic solvent coming out of the first stage mixer settler extractor is 0.4 moN/f! Met.

The uranium extraction efficiency at each stage was as high as 95% of the equilibrium value.

FIG. 4(a) shows a schematic configuration diagram of another example in which the porous wall mixer settler extractor of the present invention is used in multiple stages. In this example, the mixer chamber 11 of the porous wall mixer settler extractor 10 is shown in FIG.
is equipped with an agitator 15, and a multi-stage continuous extractor incorporating a transfer pump 14 is shown in the settler chamber 12.

In the figure, each mixer chamber 11 has a volume of 150 d, the settler chamber 12 has a volume of 50 d, and a porous wall 13 placed between them.
The section has a volume of 50 m1. Each settling chamber pump outlet is a three-way valve, and the extract separated in the settling chamber 12 is sent to the next stage or is sent out of the extractor as a treated liquid. Each mixer chamber 11 is supplied with an extract from an adjacent settler chamber 12, and an inlet 1 for supplying an extract from the outside.
It has a 6 on it.

Through these ports, it is possible to exchange the extract liquid or change the composition of the solution at any stage.

Between the mixer chamber 11 and the settler chamber 12, three sheets of 200 mesh stainless steel mesh are stacked at intervals of 4 mm, and a plate made of two layers of sintered stainless steel beads each having a diameter of 2 mm is inserted between the base meshes. Furthermore, graphite beads with a diameter of 4 mm are sintered on the outlet side of the porous wall made of the net and beads, and the thickness is 8 mm.
Attach the board.

Next, a specific example of separate extraction of uranium and thorium using the above multi-stage continuous extractor will be described with reference to FIG. 4(b).

An aqueous HNO3 solution containing uranium and thorium at a concentration of 0.1 mcj/1 each is supplied to the extractor at one end of this multi-stage continuous extraction device at a flow rate of 50 d/min, and the TBP at the 10th stage of the other end is supplied.
Dodecane containing 30% is fed at a flow rate of 50 ml and a countercurrent extraction is carried out. However, in the sixth stage, the TBP organic phase failed to flow out of the extractor, and in the fifth stage, fresh 30% TBP/'n dodecane was supplied at a flow rate of 50 ml/min. Also, in the sixth stage, add 10 rId of concentrated nitric acid;! Add at a flow rate of /min. In FIG. 4(b), the flow of the extract is shown by arrows. As a result of these operations, 0.1 mJ/
An organic phase from which 19 liters of uranium had been extracted was obtained, and an organic phase from which 0.1 mnj/4 of thorium had been extracted was obtained from the sixth stage exit.

[Effects of the Invention] As explained above, according to the present invention, the retention time of the extract in the mixer-settler extractor is shortened due to the reduction in the volume of the settler chamber, so the continuous extractor connected in multiple stages can operate very efficiently. It has the excellent effect of being able to

[Brief explanation of the drawing]

FIG. 1(a) is a schematic sectional view of one embodiment of the present invention, FIGS. 1(b) to (d) are perspective views of other examples of the porous layer of FIG. 1(a), and FIG. 3 is a schematic configuration diagram of another embodiment of the present invention.
The figure is a schematic diagram of the mixer-settler extractor of the present invention connected in multiple stages, FIG. 4(a) is another schematic diagram of the mixer-settler extractor of the present invention connected in multiple stages, and FIG. 4(b) is the same diagram. (
This is a diagram showing the flow of the extract in a). 1.1A~10.10...Mixer settler extractor with porous wall 2.2A~20.11...Mixer chamber 3.3A~30.12...Settler chamber 4.4A~40.13... Porous wall 5.15...Agitator 8.14...Pump (8733) Agent Patent attorney Yoshiaki Inomata (and others)
1 person) (d) 1 2 3 4 5 6 7 8 9
10 Saishan Toyo Moxibustion Shu (b) Figure 4

Claims (6)

[Claims] (1) In a mixer settler extractor equipped with a mixer chamber having an agitator and a settler chamber communicating with the mixer chamber,
A mixer-settler extractor with a porous wall, characterized in that a porous wall made of porous material is formed in a partition between the mixer chamber and the settler chamber. (2) The porous wall is filled with spherical particles with a diameter of 1 cm or less, or particles volumetrically equivalent thereto, or particles of this shape are sintered into a plate shape.
A mixer settler extractor with porous walls as described in Section 1. (3) A porous wall is made up of one or two or more overlapping nets or cloths, and the mesh lattice spacing of each net or cloth is 1 on average.
A mixer settler extractor with a porous wall according to claim 1, which has a porous wall of 0 mm or less. (4) The porous wall is plate-like or thin-film-like and has a cross-sectional area of 100
2. The mixer-settler extractor with porous walls according to claim 1, wherein at least one plate has a large number of penetrating holes of 2 mm or less. (5) A mixer settler extractor with porous walls according to claim 1, wherein the porous walls are a combination of porous materials according to claims 2 to 4. (6) A mixer settler extractor with a porous wall, which includes a mixer chamber having an agitator, a settler chamber communicating with the mixer chamber, and a porous wall made of porous material formed in a partition between the mixer chamber and the settler chamber. A mixer settler extraction device with a porous wall characterized by a multi-stage configuration.