KR102700038B1 - Apparatus and method for separating rare earth element - Google Patents

Abstract

The rare earth separation device according to the present invention is characterized by including: a lower container accommodating a rare earth aqueous solution having rare earth elements dissolved therein; an upper container accommodating an organic solution for separating the rare earth elements from the rare earth aqueous solution; a connecting column connecting the lower container and the upper container; an organic solution discharge unit discharging the organic solution upward within the connecting column; and an aqueous solution discharge unit discharging the rare earth aqueous solution downward within the connecting column.

Description

{Apparatus and method for separating rare earth element}

The present invention relates to a device for extracting rare earth elements, and more specifically, to a small-sized, fast-processing, and environmentally friendly rare earth separation device and method.

Rare earth elements including Nd are used in various fields of advanced industries today. Magnets with Nd as the main component are used in computers, vehicle motors, magnetic separators, power generation motors, medical equipment, etc. In particular, demand for them as main components of electric vehicles is increasing day by day.

However, the mining and processing of rare earth elements causes serious environmental pollution and industrial accidents. That is, a lot of strong chemicals are used to extract rare earth elements, which causes a large amount of toxic wastewater to be generated during the extraction process. In addition, rare earth elements have the characteristic of being clustered together with radioactive elements (mainly thorium and europium), so when searching for rare earth elements, radioactivity is measured, and a large amount of radioactive contaminants are also generated during the extraction process. As such, since the mining and extraction of rare earth elements causes serious environmental pollution, the reprocessing and purification processes are very expensive.

In addition, since there is no domestic production of rare earth resources including Nd, we depend entirely on imported products, and thus the supply is unstable compared to the high demand. Most of the rare earths imported and manufactured in this way are processed as scrap after use and re-exported overseas. Therefore, in order to stabilize the supply and demand of rare earth resources, a technology to recycle rare earth resources that have been used and turned into scrap is needed.

Prior patent: Korean Patent Publication No. 10-2021-0069878

The problem to be solved by the present invention relates to a rare earth separation device and method for extracting rare earth materials through an emulsion flow process for a rare earth aqueous solution.

A rare earth separation device for solving the above problem is characterized by including: a lower container accommodating a rare earth aqueous solution having rare earth elements dissolved therein; an upper container accommodating an organic solution for separating the rare earth elements from the rare earth aqueous solution; a connecting column connecting the lower container and the upper container; an organic solution discharge unit for discharging the organic solution upward within the connecting column; and an aqueous solution discharge unit for discharging the rare earth aqueous solution downward within the connecting column.

The organic solution discharge unit is characterized by including an organic solution discharge nozzle which is arranged at the inner upper portion of the lower container and discharges the organic solution in the upper direction of the connection column; an organic solution circulation pipe which has one end connected to the organic solution discharge nozzle and the other end connected to the upper container; and an organic solution circulation pump which is connected to the organic solution circulation pipe and supplies the organic solution contained in the upper container to the organic solution discharge nozzle through the organic solution circulation pipe.

The above organic solution discharge nozzle is characterized in that the height of a filter guide extended from a nozzle filter provided in the nozzle is 4 [mm] or more and 6 [mm] or less.

The above organic solution discharge nozzle is characterized by including a metal nozzle that is a full cone-shaped spray nozzle and can spray droplets of a certain size at a spray angle of 60 degrees or more and 180 degrees or less.

The above organic solution circulation pipe is characterized in that the first end penetrates the interior of the lower container and is connected to the organic solution discharge nozzle, and the second end is connected to the interior of the upper container.

The above-mentioned aqueous solution discharge unit is characterized by including: an aqueous solution discharge nozzle which is arranged at the inner lower part of the upper container and discharges the rare earth aqueous solution in the downward direction of the connection column; an aqueous solution circulation pipe which has one end connected to the aqueous solution discharge nozzle and the other end connected to the lower container; and an aqueous solution circulation pump which is connected to the aqueous solution circulation pipe and supplies the rare earth aqueous solution contained in the lower container to the aqueous solution discharge nozzle through the aqueous solution circulation pipe.

The above-mentioned aqueous solution circulation pipe is characterized in that a first end is connected to the aqueous solution discharge nozzle by penetrating the interior of the upper container, and a second end is connected to the interior of the lower container.

The above connecting column is a cylindrical structure, and is characterized in that the widthwise cross-sectional size of the cylindrical structure is relatively smaller than the widthwise cross-sectional sizes of the lower container and the upper container.

A rare earth separation method for solving the above problem is characterized by including the steps of: filling the rare earth aqueous solution to the middle height of the connecting column and filling the organic solution to the upper end of the upper container; driving the aqueous solution discharge unit and the organic solution discharge unit to circulate the rare earth aqueous solution and the organic solution, respectively; and adjusting the driving conditions of the aqueous solution discharge unit and the organic solution discharge unit according to the emulsion state formed in the connecting column.

According to the present invention, it has the advantages of fast processing speed even with a small device, simple structure, low cost since there is no separate power device, and short process time. In addition, it has an extraction rate of 90% or more with one extraction. Therefore, when applied to the Nd, Dy recovery process, it can achieve the effects of cost reduction and process time reduction.

In particular, in the case of the rare earth separation device of the present invention, since a high extraction rate of 90% or more can be achieved by using only an extractant that does not use a saponification reaction or an emulsifier, it enables more environmentally friendly and economical rare earth extraction by not using additional physical stirring inside the solution or emulsification and de-oiling processes for mixing and separating phases to increase the extraction rate in the existing commercially used solvent extraction process.

FIG. 1 is a configuration diagram of one embodiment for explaining a rare earth separation device according to the present invention.
Figure 2 is an enlarged perspective view showing the lower container illustrated in Figure 1.
Figure 3 is an enlarged perspective view showing the upper container illustrated in Figure 1.
Figure 4 is an enlarged perspective view showing the connecting column illustrated in Figure 1.
Figure 5 is a reference drawing exemplifying the types of organic solution discharge nozzles.
Figure 6 is a reference drawing exemplifying the types of organic solution discharge nozzles made of metal material in the shape of a full cone according to the injection angle.
Figure 7 is a flow chart of one embodiment for explaining a rare earth separation method using a rare earth separation device according to the present invention.
Figure 8 is a graph comparing the extraction rates of different types of organic solution discharge nozzles.
Figure 9 is a graph comparing the extraction rate according to the injection angle of the organic solution discharge nozzle.
Figure 10 is a graph comparing the extraction rate according to the material of the organic solution discharge nozzle.
Figure 11 shows the change in extraction rate and separation coefficient of rare earth elements according to the filter pore size of the nozzle.
Figure 12 shows the change in extraction rate and separation coefficient of rare earth elements according to the shape of the nozzle.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the embodiments below can be modified in various different forms, and the scope of the present invention is not limited to the embodiments below. Rather, these embodiments are provided to more faithfully and completely convey the idea of the present invention to those skilled in the art.

The terminology used herein is used to describe particular embodiments and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" include plural forms unless the context clearly dictates otherwise. Also, when used herein, the words "comprise" and/or "comprising" specify the presence of stated features, numbers, steps, operations, elements, elements and/or groups thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, elements, elements and/or groups thereof. As used herein, the word "and/or" includes any and all combinations of one or more of the listed items.

Currently, technology to recycle rare earths, including Nd, is being actively studied. Looking at the rare earth recovery process, first, since waste Nd magnet scrap still has strong magnetism, a demagnetization process is performed to remove the magnetism. Then, the scrap is crushed, dissolved in strong acid, precipitated with sodium sulfate to separate it from Fe, converted the separated rare earth precipitate into a hydroxide, dissolved the rare earth hydroxide in hydrochloric acid again, separated light rare earth and heavy rare earth by solvent extraction of the rare earth hydrochloric acid solution, and precipitated again to powderize the rare earth solution.

Among these processes, the solvent extraction process is a process for separating/purifying light rare earth elements (Nd, Pr, Ce, La) and heavy rare earth elements (Tb, Dy) from a hydrochloric acid solution. Since there is a large difference in properties between light rare earth elements and heavy rare earth elements and a price difference of about 10 times, a technology for separating them using the most optimal solvent extraction process is required considering economic and environmental aspects. Solvent extraction usually refers to separating target substances existing in the water phase into the oil phase by utilizing the property that water (aqueous phase) and oil (oil phase), two phases, do not mix with each other.

There are various methods for solvent extraction depending on the type of extraction equipment. The pulse column method mixes the aqueous phase and the oil phase by pulsating with up and down vibration. It has the advantage that the droplet dispersion is uniform in the radial direction and the extraction efficiency does not depend on the column diameter, but if the pulsation is insufficient or too large, a flooding phenomenon occurs, so appropriate pulsation conditions are required. The spray column method has a very simple principle and structure that simply sprays the oil phase and the aqueous phase from above and below. Therefore, it has a great advantage in terms of cost, but there is a problem of reduced extraction rate due to back mixing. The centrifugal extractor method uses centrifugal force, and has excellent mixing efficiency and short process time, but has the disadvantage of very high equipment costs and operating costs. The mixer-settler method is the most widely used solvent extraction method, and is widely used in mass production because it can process a large amount of capacity at one time, is easy to control the flow rate, and is easy to increase the number of stages. However, the amount of solution including the aqueous phase and the oil phase that are basically required for extraction is large, process control is difficult, and the initial equipment cost and operating cost are high. The process time is long and requires a lot of extraction steps, so it takes up a lot of space. Accordingly, a new method for extracting rare earth elements is required.

In the present invention, a device for the 'emulsion flow method' is proposed as a new solvent extraction method. The emulsion flow method forms an emulsion by spraying oil-phase droplets of about 200 μm in size against the flow of an aqueous solution. The emulsion droplets formed in a narrow column rapidly increase their passage area in the upper and lower phase separation sections of the device while their flow rate rapidly decreases. At this time, the droplets rapidly grow and burst when they collide with subsequent emulsion droplets with a high flow rate, causing the emulsion to be quickly resolved.

Figure 1 is a configuration diagram of one embodiment for explaining a rare earth separation device (10) according to the present invention.

Referring to FIG. 1, the rare earth separation device (10) includes a lower container (100), an upper container (200), a connecting column (300), an organic solution discharge unit (400), and an aqueous solution discharge unit (500).

The lower container (100) accommodates a rare earth aqueous solution with rare earth dissolved therein. This lower container (100) may be made of a transparent material, thereby allowing internal observation.

Here, the rare earth element solution may be exemplified by a hydrochloric acid solution in which rare earth elements are dissolved. However, this rare earth element solution is merely exemplary and may include various types of solutions in which rare earth elements are dissolved.

For example, a rare earth element aqueous solution sample can be analyzed using ICP-MASS (Thermofisher Scientific company model: iCAP-Q) to confirm the composition as shown in Table 1 below.

Component La Ce Nd Pr Dy Content (mg/L) 219.6 413.6 868.3 3628.6 88.1

Figure 2 is an enlarged perspective view showing the lower container (100) illustrated in Figure 1.

Referring to FIG. 2, the lower container (100) includes a container body (110), a column connection port (120), an aqueous solution discharge port (130), and a tube insertion port (140).

The container body (110) provides a space for containing a rare earth aqueous solution and may be a cylindrical structure. At this time, the shape of the cylindrical structure may be a cylindrical shape or a polygonal cylinder shape, etc.

The column connection port (120) is a hole formed in the center of the top of the container body (110). The column connection port (120) has an opening formed so that it can communicate with the connection column (300), and may be a hole structure in which screw threads are formed for screw connection with the connection column (300), or may be a hole structure for insertion connection.

The solution discharge port (130) is connected to the solution circulation pipe (520), which is a component of the solution discharge unit (500), and has a hole structure for discharging the rare earth solution stored in the container body (110) to the solution circulation pipe (520). In Fig. 2, the solution discharge port (130) is shown as being formed at the bottom of the container body (110), but this is exemplary, and it may be formed at the lower side of the container body (110).

The tube insertion port (140) includes a hole structure into which the organic solution discharge nozzle (410) and the organic solution circulation pipe (420), which are components of the organic solution discharge unit (400), can be inserted. When the organic solution discharge nozzle (410) and the organic solution circulation pipe (420) are inserted into the tube insertion port (140), the tube insertion port (140) can be sealed to prevent leakage of the rare earth aqueous solution. The tube insertion port (140) can include a sealing member for sealing.

In Fig. 2, the tube insertion port (140) is shown as being formed at the bottom of the container body (110), but this is exemplary, and the tube insertion port (140) may be formed at the side of the container body (110).

The upper container (200) contains an organic solution for separating rare earth elements from a rare earth aqueous solution. The upper container (200) may be made of a transparent material so that the inside can be observed.

The organic solution can be used as an extractant for extracting rare earth elements, and cationic extractants such as PC88A (2-ethylhexyl phosphoric acid mono-2-ethyl-hexyl ester), D2EHPA (Di-2-ethylhexyl phosphoric acid), Cyanex272 (Bis-2,4,4-trimethylpentyl phosphinic acid), and TBP (Tri-butyl-phosphate) can be used. The concentration of the extractant can be adjusted to 5 to 30 wt% by using kerosene as a diluent. Meanwhile, instead of using kerosene as a diluent, the organic solution can be used as a diluent by adjusting the concentration of the extractant to 5 to 30 wt% by using another dearomatized hydrocarbon.

In the present invention, for forming an emulsion, a motor for additional physical stirring within the solution or chemicals for mixing and separating phases, such as an emulsifier or a defoaming agent, are not used, thereby enabling more environmentally friendly and economical extraction of rare earth elements.

Figure 3 is an enlarged perspective view showing the upper container (200) illustrated in Figure 1.

Referring to FIG. 3, the upper container (200) includes a container body (210), a column connection port (220), an organic solution discharge port (230), and a tube insertion port (240).

The container body (210) provides a space for containing an organic solution and may be a cylindrical structure. At this time, the shape of the cylindrical structure may be a cylindrical shape or a polygonal cylinder shape, etc.

The column connection port (220) is a hole formed in the center of the bottom of the container body (210). The column connection port (220) has an opening formed so that it can communicate with the connection column (300), and may be a hole structure in which screw threads are formed for screw connection with the connection column (300), or may be a hole structure for insertion connection.

The organic solution discharge port (230) is connected to the organic solution circulation pipe (420), which is a component of the organic solution discharge unit (400), and includes a hole structure for discharging the organic solution stored in the container body (210) to the organic solution circulation pipe (420). In Fig. 3, the organic solution discharge port (230) is shown as being formed at the upper end of the container body (210), but this is exemplary, and it may be formed at the upper side of the container body (210).

The tube insertion port (240) includes a hole structure into which the solution discharge nozzle (510) and the solution circulation pipe (520), which are components of the solution discharge unit (500), can be inserted. When the solution discharge nozzle (510) and the solution circulation pipe (520) are inserted into the tube insertion port (240), the tube insertion port (240) can be sealed to prevent the organic solution from leaking. The tube insertion port (240) can include a sealing member for sealing.

In Fig. 3, the tube insertion port (240) is shown as being formed at the top of the container body (110), but this is exemplary, and the tube insertion port (240) may be formed at the side of the container body (210).

A connecting column (300) connects the lower container (100) and the upper container (200).

Figure 4 is an enlarged perspective view showing the connecting column (300) illustrated in Figure 1.

Referring to FIG. 4, the connecting column (300) may be a cylindrical structure. At this time, the shape of the cylindrical structure may be a cylinder or a polygonal cylinder.

The connecting column (300) may have screw threads formed at one end (310) and the other end (320) for screw connection or fitting connection with the lower container (100) and the upper container (200), or may have a step formed for fitting connection.

The connecting column (300) may have a cross-sectional size in the width direction of the cylindrical structure that is relatively smaller than the cross-sectional sizes in the width direction of the lower container (100) and the upper container (200). Accordingly, the emulsion droplets formed in the connecting column (300) having a relatively small cross-sectional size rapidly decrease in velocity as they move to the lower container (100) and the upper container (200) having a relatively large cross-sectional area, thereby colliding with subsequent emulsion droplets having a high velocity. Accordingly, the emulsion may be rapidly resolved as the droplets formed in the connecting column (300) rapidly grow and rupture on the lower container (100) and the upper container (200).

The organic solution discharge unit (400) discharges the organic solution from the bottom to the top within the connection column (300).

As shown in Fig. 1, the organic solution discharge unit (400) includes an organic solution discharge nozzle (410), an organic solution circulation pipe (420), and an organic solution circulation pump (430).

The organic solution discharge nozzle (410) is positioned at a position where the lower vessel (100) and the connection column (300) are connected, and discharges the organic solution from the lower portion of the connection column (300) toward the upper portion. A nozzle filter made of Teflon mesh having a plurality of pores may be provided at the front end of the organic solution discharge nozzle (410). At this time, the pore sizes may vary from 10 to 100 [㎛]. Table 2 below is a table showing examples of pore sizes of the nozzle filter.

P2 P3 P4 Pore size(㎛) 40-100 16-40 10-16

Table 2 shows the types of glass filters used in the production of liquid nozzles. They are usually classified by pore size, and as the number increases from P2 to P4, the pore size of the filter becomes finer, from 100 to 10 ㎛.

Figure 5 is a reference drawing exemplifying the types of organic solution discharge nozzles (410).

Fig. 5 (a) shows a nozzle without a filter guide for controlling the path of droplets in a nozzle filter provided in an organic solution discharge nozzle (410), Fig. 5 (b) shows a nozzle in which the height of a filter guide extended from a nozzle filter is 4 [mm] or more and 6 [mm] or less, and Fig. 5 (c) shows a nozzle in which the height of a filter guide extended from a nozzle filter is 20 [mm] or more.

It is appropriate for the organic solution discharge nozzle (410) to have a filter guide extending from the nozzle filter of 4 [mm] or more and 6 [mm] or less in height, and in particular, a nozzle having a filter guide height of 5 [mm] is preferable.

In addition, the organic solution discharge nozzle (410) may be a full cone-shaped spray nozzle that can be a metal nozzle capable of spraying droplets of a certain size at a spray angle of 60 degrees or more and 180 degrees or less.

Figure 6 is a reference drawing exemplifying the types of organic solution discharge nozzles (410) made of metal material in the shape of a full cone according to the injection angle.

Fig. 6 (a) shows an organic solution discharge nozzle having an organic solution spray angle of 90 [degrees], and Fig. 6 (b) shows an organic solution discharge nozzle having an organic solution spray angle of 120 [degrees]. The flow rate sprayed per minute differs depending on the organic solution spray angle.

The organic solution circulation pipe (420) has one end connected to the organic solution discharge nozzle (410) and the other end connected to the upper container (200). The material of the organic solution circulation pipe (420) may be a Teflon tube, etc.

As illustrated in FIG. 1, the first end (420-1) of the organic solution circulation pipe (420) is positioned to penetrate the pipe insertion port (140) of the lower container (100), and is connected to the organic solution discharge nozzle (410) positioned at the position where the lower container (100) and the connection column (300) are joined.

In addition, the second end (420-2) of the organic solution circulation pipe (420) is connected to the interior of the upper container (200). The second end (420-2) of the organic solution circulation pipe (420) passes through the organic solution discharge port (230) of the upper container (200) and is disposed inside the upper container (200). Accordingly, the organic solution present in the upper container (200) is introduced into the second end (420-2) of the organic solution circulation pipe (420) by the organic solution circulation pump (430), and the organic solution introduced in this way can be delivered to the organic solution discharge nozzle (410).

The organic solution circulation pump (430) is connected to the organic solution circulation pipe (420) and supplies the organic solution contained in the upper container (200) to the organic solution discharge nozzle (410) through the organic solution circulation pipe (420). A tubing pump (peristaltic pump), etc. may be used as the organic solution circulation pump (430). The organic solution circulation pump (430) may include a controller capable of controlling the flow rate, a tube pipe for transporting the organic solution, and a pump head with a roller capable of squeezing the tube pipe.

The aqueous solution discharge unit (500) discharges the rare earth aqueous solution downward within the connecting column (300).

As shown in Fig. 1, the aqueous solution discharge unit (500) includes an aqueous solution discharge nozzle (510), an aqueous solution circulation pipe (520), and an aqueous solution circulation pump (530).

The aqueous solution discharge nozzle (510) is placed at the lower part inside the upper container (100) and discharges the rare earth aqueous solution downward from inside the connecting column (300). The shape and size of the aqueous solution discharge nozzle (510) can be changed in design as needed. For example, the front end of the aqueous solution discharge nozzle (510) may be equipped with a Teflon mesh filter having 12 holes with a diameter of 0.3 [mm].

The aqueous solution circulation pipe (520) has one end connected to the aqueous solution discharge nozzle (510) and the other end connected to the lower container (100). The material of the aqueous solution circulation pipe (520) may be a Teflon tube, etc.

As illustrated in FIG. 1, the first end (520-1) of the aqueous solution circulation pipe (520) is positioned to penetrate the pipe insertion port (240) of the upper container (200), and is connected to the aqueous solution discharge nozzle (510) positioned at the position where the upper container (200) and the connecting column (300) are joined.

In addition, the second end (520-2) of the aqueous solution circulation pipe (520) is connected to the interior of the lower container (100). The second end (520-2) of the aqueous solution circulation pipe (520) is arranged to be connected to the aqueous solution discharge port (130) of the lower container (100). Accordingly, the rare earth aqueous solution present in the lower container (100) is introduced into the second end (520-2) of the aqueous solution circulation pipe (520) by the aqueous solution circulation pump (530), and the rare earth aqueous solution introduced in this way can be delivered to the aqueous solution discharge nozzle (510).

The aqueous solution supply pump (530) is connected to the aqueous solution circulation pipe (520) and supplies the rare earth aqueous solution contained in the lower container (100) to the aqueous solution discharge nozzle (510) through the aqueous solution circulation pipe (520). The aqueous solution circulation pump (530) may use a tubing pump (peristaltic pump), etc. The aqueous solution circulation pump (530) may include a controller capable of controlling the flow rate, a tube for transporting the aqueous solution, and a pump head with a roller capable of squeezing the tube.

Figure 7 is a flow chart of one embodiment for explaining a rare earth separation method using a rare earth separation device according to the present invention.

First, the rare earth aqueous solution is filled to the middle height of the connecting column in the rare earth separation device, and the organic solution is filled to the top of the upper container (step S1000). The rare earth aqueous solution is filled to the middle height of the lower container constituting the rare earth separation device and the connecting column. The organic solution, which is a solvent containing an extractant, is filled to a certain height of the upper container constituting the rare earth separation device. Accordingly, the ratio of the rare earth aqueous solution and the organic solution in the connecting column of the rare earth separation device becomes 1:1.

After step S1000, the aqueous solution discharge unit and the organic solution discharge unit of the rare earth separation device are driven to circulate the rare earth aqueous solution and the organic solution, respectively (step S1010).

By operating the aqueous solution circulation pump of the aqueous solution discharge unit and the organic solution circulation pump of the organic solution discharge unit simultaneously, the emulsion formation behavior formed in the connecting column is observed. At this time, the flow rate of the rare earth aqueous solution can be set to 30 [ml/min], and the flow rate of the organic solution can be set to 240 [ml/min].

After step S1010, the operating conditions of the aqueous solution discharge unit and the organic solution discharge unit are adjusted according to the emulsion state formed in the connecting column of the rare earth separation device (step S1020).

Adjust the rpm of the organic solution circulation pump and the aqueous solution circulation pump to prevent overflow of emulsion droplets in the lower and upper containers. Collect samples of the aqueous solution at each time point when the injected aqueous solution has been circulated 1, 2, and 3 times, and then perform an analysis on the aqueous solution.

When the amount of solution circulated by the aqueous solution circulation pump becomes equal to the amount of rare earth aqueous solution initially injected, a rare earth aqueous solution sample is collected. The collected rare earth aqueous solution sample is analyzed for rare earth components using ICP-MASS, and based on the analysis results, the extraction rate, distribution coefficient (D), and separation coefficient (β) for each condition can be calculated using the following mathematical equations 1 to 3.

Here, C _O represents the concentration of individual rare earth elements in the initial rare earth aqueous solution, and C _eq represents the concentration of individual rare earth elements in the rare earth aqueous solution after solvent extraction.

The rare earth separation device of the present invention is a device for batch-type emulsion flow that extracts solvent using only the initially introduced solution. For example, a connecting column in which an aqueous phase and an oil phase are mixed in an emulsion state is located at the center of the rare earth separation device. An upper container in which a phase-separated oil phase is collected is formed at the upper part of the connecting column, and a lower container in which a phase-separated aqueous phase is collected is provided at the lower part of the connecting column. A nozzle for spraying an aqueous phase exists at the upper part of the connecting column, and a nozzle for spraying an oil phase exists at the lower part. The lower container and the upper aqueous phase nozzle are connected using a Teflon tube or the like to allow the aqueous phase to circulate. In addition, the upper container and the lower oil phase nozzle are connected to allow the oil phase to circulate, so that the solution is structured to continuously circulate without additional input of an external solution.

In the rare earth separation device of the present invention, an emulsion is formed in a connecting column, and the emulsion phase is separated in the upper and lower phase separation units (lower vessel, upper vessel) to perform solvent extraction. Therefore, the formation of a stable emulsion phase in the connecting column is important.

Accordingly, in order to confirm the conditions for forming a stable emulsion phase, various shapes and pore sizes of oil nozzles are used to observe how much of the emulsion layer is formed and filled in the connecting column, and how much of the formed emulsion layer fills the connecting column is evaluated.

Table 3 below quantitatively shows the results of the ratio of the emulsion layer formed according to the shape of the oil nozzle and the pore size of the nozzle filter filling the connecting column.

P2 P3 P4 Type A 100 85< 75< Type B 100 100 100 Type C 100 90< 90<

Here, Type A represents the organic solution discharge nozzle illustrated in (a) of Fig. 5, Type B represents the organic solution discharge nozzle illustrated in (b) of Fig. 5, and Type C represents the organic solution discharge nozzle illustrated in (c) of Fig. 5. In the case of Type B, an emulsion layer is sufficiently formed in the connecting column regardless of the pore size of the filter. In the other cases of Type A and Type C, the emulsion is sufficiently filled to completely fill the connecting column only when the nozzle pore size is P2. Type C shows a tendency for the water droplets formed at the top and descending to flow into the oil nozzle since the nozzle jaw is high. At this time, it is judged that the oil droplets sprayed from the oil nozzle rise along the interface of the water droplets that are tens of times larger than the oil droplets that flowed into the oil nozzle and gather to form droplets larger than the micro level, thereby hindering the formation of the emulsion. Therefore, it is judged that the nozzle of the type B type has the most favorable conditions for emulsion formation.

The rare earth extraction behavior according to the type of organic solution discharge nozzle and the pore size of the filter can be confirmed as follows.

Table 4 below provides examples of the specifications of various cone-shaped organic solution discharge nozzles.

There is a difference in the flow rate sprayed per minute depending on the diameter and spray angle of the organic solution discharge nozzles A, B, C, and D. In particular, the organic solution discharge nozzle D has a spray angle of 120 [degrees], which is wider than that of the other organic solution discharge nozzles A, B, and C.

Figure 8 is a graph comparing the extraction rates by type of organic solution discharge nozzle, and Table 5 below is a table showing the extraction rates (%) according to the types.

According to Fig. 8 and Table 5, the extraction rate of the organic solution discharge nozzle A with the smallest sprayed flow rate is the highest. According to this, it is judged that the size of the sprayed droplets is smaller and more uniform because the hole (orifice diameter) of the spray nozzle is small, the sprayed flow rate is small, and the pressure received is higher.

Figure 9 is a graph comparing the extraction rate according to the injection angle of the organic solution discharge nozzle, and Table 6 below is a table showing the extraction rate (%) according to the injection angle.

According to Fig. 9 and Table 6, the extraction rate of the organic solution discharge nozzle D at an injection angle of 120 degrees is higher. According to this, it is judged that this is because the droplets are sprayed widely, and the rate at which the droplets coalesce to form large droplets is lower.

Figure 10 is a graph comparing the extraction rate according to the material of the organic solution discharge nozzle, and Table 7 below is a table showing the extraction rate (%) according to the material.

According to Fig. 10 and Table 7, the extraction rate is better when extracted using a glass filter, but the difference is only 7%, so the purpose is to determine whether replacing the metal nozzle is an effective alternative to the nozzle clogging phenomenon.

According to this, the Dy extraction rate is higher at 94.75% for the glass filter, and the rare earth extraction rate is up to 4% higher for the metal nozzle. This means that rare earth elements can be removed through subsequent processes such as scrubbing and stripping, and considering the nozzle clogging phenomenon, it can be judged that the metal nozzle can be a substitute for the glass filter.

Figure 11 shows the change in extraction rate and separation coefficient of rare earth elements according to the filter pore size of the nozzle.

Fig. 11 (a) shows the change in extraction rate and separation coefficient of rare earth elements according to the pore size of the filter when the organic solution discharge nozzle is Type A, Fig. 11 (b) shows the change in extraction rate and separation coefficient of rare earth elements according to the pore size of the filter when the organic solution discharge nozzle is Type B, and Fig. 11 (c) shows the change in extraction rate and separation coefficient of rare earth elements according to the pore size of the filter when the organic solution discharge nozzle is Type C. The separation coefficient of Fig. 11 is calculated using the distribution coefficient of Nd and the distribution coefficient of Dy.

The extraction rates of Dy according to the change in pore size from P2 to P4 are similar at 94.27, 94.11, and 94.08[%]. However, the extraction rates of rare earth elements La, Ce, Pr, and Nd slightly increase by 2–3[%]. It is judged that as the filter pore size of the organic solution discharge nozzle decreases, the size of the sprayed oil droplets decreases, and the surface area where the oil and water phases react increases. Therefore, it is judged that the mixing reaction of the oil and water phases becomes more active, increasing the extraction rate.

As the pore size of the filter is finer, the extraction rate slightly increases, but the separation efficiency decreases, so it is necessary to select an appropriate pore size. In addition, since impurities accumulate on the filter surface after the extraction process, it is expected that the finer the pores, the easier it is to become clogged. Therefore, it is judged that the P2 filter, which has a high extraction rate and large pore size, is the most suitable size.

Figure 12 shows the change in extraction rate and separation coefficient of rare earth elements according to the shape of the nozzle.

Figure 12 (a) shows the change in extraction rate and separation factor of rare earth elements according to the nozzle shape when the pore size of the filter is P2, and Figure 12 (a) shows the change in extraction rate and separation factor of rare earth elements according to the nozzle shape when the pore size of the filter is P2, and Figure 12 (a) shows the change in extraction rate and separation factor of rare earth elements according to the nozzle shape when the pore size of the filter is P2.

Except for the organic solution discharge nozzle B having a front end of 5 [mm], the emulsion layer was not sufficiently formed. In the rare earth separation device of the present invention, solvent extraction occurs only when an emulsion is formed by mixing micro-level droplets. The extraction rate of Dy was high regardless of the pore size of the nozzle filter. Organic solution discharge nozzles A and B showed an extraction rate of Dy of 90% or more, and organic solution discharge nozzle C showed an extraction rate of 80 to 90%. The separation coefficient values also showed high values in the order of type B > type A > type C.

In the case of the organic solution discharge nozzle C, the aqueous phase emulsion coming down from the upper aqueous solution discharge nozzle did not go to the lower container, but was partially introduced onto the filter of the organic solution discharge nozzle C and became isolated. For this reason, it is judged that the extraction rate decreased due to the instability of emulsification caused by the introduction of aqueous phase droplets due to the high jaw of the nozzle, compared to the stable emulsion flow formation in which the aqueous phase emulsion is absorbed into the aqueous phase in the lower container and the oil phase emulsion is absorbed into the oil phase in the upper container. It is judged that the extraction rate of the organic solution discharge nozzle A was over 90% due to the stable emulsion flow phenomenon even though the emulsion layer was not sufficiently filled in the connecting column during the previous emulsion formation process. The organic solution discharge nozzle B showed the highest extraction rate due to normal flow and sufficient emulsion formation.

Although the embodiments of the present invention have been described above, the embodiments disclosed in the specification of the present invention do not limit the present invention. The scope of the present invention should be interpreted by the following claims, and all technologies within the scope equivalent thereto should also be interpreted as being included in the scope of the present invention.

10: Rare Earth Separation Device
100: Lower container
200: Upper container
300: Connection Column
400: Organic solution discharge part
500: Aqueous solution discharge part

Claims (9)

A lower vessel containing a rare earth aqueous solution with rare earth elements dissolved therein;
An upper container for containing an organic solution for separating the rare earth elements from the rare earth element aqueous solution;
A connecting column connecting the lower container and the upper container;
An organic solution discharge unit for discharging the organic solution upward within the connecting column; and
A rare earth separation device characterized by including a solution discharge unit that discharges the rare earth aqueous solution downward within the connecting column. In claim 1,
The above organic solution discharge unit is,
An organic solution discharge nozzle positioned at the inner upper portion of the lower container and discharging the organic solution in the upper direction of the connecting column;
An organic solution circulation pipe having one end connected to the organic solution discharge nozzle and the other end connected to the upper container; and
A rare earth separation device characterized by including an organic solution circulation pump which is connected to the organic solution circulation pipe and supplies the organic solution contained in the upper container to the organic solution discharge nozzle through the organic solution circulation pipe. In claim 2,
The above organic solution discharge nozzle is,
A rare earth separation device characterized in that the height of a filter guide extended from a nozzle filter provided in a nozzle is 4 [mm] or more and 6 [mm] or less. In claim 2,
The above organic solution discharge nozzle is,
A rare earth separation device characterized by including a metal nozzle capable of spraying droplets of a certain size at a spray angle of 60 degrees or more and 180 degrees or less as a full cone-shaped spray nozzle. In claim 2,
The above organic solution circulation pipe is,
A rare earth separation device characterized in that the first end penetrates the interior of the lower container and is connected to the organic solution discharge nozzle, and the second end is in communication with the interior of the upper container. In claim 1,
The above aqueous solution discharge unit is,
An aqueous solution discharge nozzle disposed at the inner lower part of the upper container and discharging the rare earth aqueous solution in the downward direction of the connecting column;
A solution circulation pipe having one end connected to the solution discharge nozzle and the other end connected to the lower container; and
A rare earth separation device characterized by including an aqueous solution circulation pump which is connected to the aqueous solution circulation pipe and supplies the rare earth aqueous solution contained in the lower container to the aqueous solution discharge nozzle through the aqueous solution circulation pipe. In claim 6,
The above aqueous solution circulation pipe is,
A rare earth separation device characterized in that the first end penetrates the interior of the upper container and is connected to the aqueous solution discharge nozzle, and the second end is in communication with the interior of the lower container. In claim 1,
The above connection column is,
A rare earth separation device characterized in that it is a cylindrical structure, and the widthwise cross-sectional size of the cylindrical structure is relatively smaller than the widthwise cross-sectional sizes of the lower container and the upper container. In a rare earth separation method using the rare earth separation device of claim 1,
A step of filling the rare earth aqueous solution to the middle height of the connecting column and filling the organic solution to the top of the upper container;
A step of driving the aqueous solution discharge unit and the organic solution discharge unit to circulate the rare earth aqueous solution and the organic solution, respectively; and
A rare earth separation method characterized by including a step of adjusting the operating conditions of the aqueous solution discharge unit and the organic solution discharge unit according to the emulsion state formed in the above connecting column.

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