Coalescence separation system and method for water-containing organic phase in rare earth extraction process

Abstract

The present invention discloses a coalescence separation system and method for aqueous organic phase in the rare earth extraction process. The system includes a pre-filtering unit and a coalescence separation unit; the pre-filtering unit includes a pre-filter, and the coalescence separation unit includes a horizontal coalescence separator; the pre-filter is configured to pre-filter the aqueous blank organic phase to remove solid particles, obtaining the pre-filtered aqueous blank organic phase; wherein, the aqueous blank organic phase is obtained by hydrochloric acid back-extraction and pure water washing during the rare earth extraction process; the horizontal coalescence separator includes a horizontal coalescence separator body and coalescence filter elements; the outer layer of the coalescence filter element is a perfluoroethylene-propylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer; the theoretical flow rate of a single coalescence filter element is less than or equal to 1.5 m<supgt;3< / supgt> / h. This system can remove trace water in the aqueous blank organic phase generated during the rare earth extraction process, and the water removal efficiency is greater than 80%.

Description

Technical Field

[0001] The present invention relates to the technical field of rare earth element extraction and separation, and particularly to a coalescence separation system and method for water-containing organic phase in the rare earth extraction process. Background Art

[0002] In the extraction and separation process of rare earth elements, after the organic phase extractant and the aqueous phase rare earth feed liquid undergo a complexation reaction through high-intensity stirring in the mixing chamber, they overflow into the clarification section, and are separated into layers by using the incomplete miscibility and density difference of the two phases. However, the organic phase after short-time clarification still contains entrained water and a small amount of emulsified water, and it is difficult for these waters to precipitate in a short time, resulting in a certain amount of aqueous phase being entrained in the loaded organic phase. These aqueous phases will not only reduce the extraction efficiency, but also cause losses of rare earth elements and an increase in acid and alkali consumption. Therefore, it is necessary to separate a certain amount of water entrained in the organic phase (i.e., the oil phase).

[0003] Currently, there are also many reports on devices and methods for oil-water separation in water-in-oil systems.

[0004] CN113074168B discloses a water removal system and method for thruster hydraulic oil. The water removal system includes a water removal component, a first valve body, a buffer tank, a delivery pump and a return oil pipe. The water removal component includes a treatment cabinet, a heater, a liquid inlet pipe and a water outlet pipe. The heater is arranged in the treatment cabinet for heating the hydraulic oil in the treatment cabinet. The treatment cabinet is connected to the thruster through the liquid inlet pipe, and the position height of the gravity oil tank for supplying oil to the thruster is higher than that of the treatment cabinet; the first valve body is arranged on the liquid inlet pipe; the treatment cabinet is connected to the buffer tank through the water outlet pipe; the delivery pump is arranged on the water outlet pipe; the buffer tank is connected to the gravity oil tank through the return oil pipe, and the position height of the gravity oil tank is the same as that of the buffer tank. This system and method adopt the method of vacuum heating for treatment, so that the water vapor in the hydraulic oil vaporizes, and the water and oil are separated. This system and method are not applicable to the water-containing organic phase generated by rare earth extraction. The organic phase of rare earth extraction contains about 50% of low flash point solvent oil, and it is easy to cause danger if heated.

[0005] CN112121647A discloses the application of a super-hydrophilic and super-oleophobic oil-water separation ceramic membrane. This oil-water separation ceramic membrane has super-hydrophilic and super-oleophobic properties and can achieve oil-water separation. However, the preparation process of the oil-water separation ceramic membrane is cumbersome, the service life of the membrane is limited, it is difficult to clean, and the operating cost is high. Moreover, this oil-water separation ceramic membrane is not applicable to the separation of trace water in the water-containing organic phase generated by rare earth extraction.

[0006] CN109295302A discloses an emulsion treatment device and method during the production process of rare earth extraction. The treatment device includes: a vacuum filter, a vacuum pump, a buffer tank, and a transfer pump; the vacuum pump is connected to the buffer tank through a pipeline, a vacuum gauge and a vent valve are arranged on the buffer tank, the buffer tank is connected to the receiving cavity of the vacuum filter through a pipeline, and the transfer pump is arranged on the pipeline at the outlet end of the receiving cavity. This device and method can be applied to the oil-water separation of the water-containing organic phase generated during the production process of rare earth extraction, but are more suitable for the water-in-oil system with a higher water content and not applicable to the oil-water separation with trace water.

[0007] CN117732109A discloses a method for removing hydrochloric acid entrained after organic back-extraction in industrial rare earth extraction, including adding washing water to the last two extraction tanks where hydrochloric acid is added in the lanthanum, cerium, praseodymium, and neodymium separation line, and making the washing water and the organic phase flow countercurrently for back-extraction. This method can basically solve the problem that a large amount of hydrochloric acid is entrained in the organic phase after back-extraction, and it is difficult to separate and recover hydrochloric acid even after standing and clarification, resulting in a large waste of hydrochloric acid. It also does not solve the problem of emulsified water in the organic phase and is not applicable to the removal of trace water in the water-containing blank organic phase generated during the rare earth extraction process.

[0008] CN103664629A discloses a nitrobenzene washing and separation system, which adopts a pipeline co-current washing method and adds a coalescence separator during the pipeline co-current washing process. This system is mainly used to remove sodium salts and phenol salts in crude nitrobenzene. How to use the coalescence filter element is not mentioned in this system, and this nitrobenzene system is different from the water-containing blank organic phase generated by rare earth extraction.

[0009] The coalescence separation method adopted in the present invention utilizes the hydrophilic property of the coalescence material to make small water droplets aggregate and form larger water droplets on its surface. Under the action of gravity and the impact force of the oil flow, the water droplets with increased particle size break away from the surface of the coalescence material and sink, thereby separating oil and water.

[0010] So far, there has been no report on removing trace water in the water-containing organic phase generated during the rare earth extraction process by the coalescence separation method. Summary of the Invention

[0011] In view of this, an object of the present invention is to provide a coalescence separation system for water-containing organic phase during the rare earth extraction process, which can remove trace water in the water-containing blank organic phase generated during the rare earth extraction process, and the water removal efficiency is greater than 80%, preferably greater than or equal to 81%. Another object of the present invention is to provide a method for removing water in the water-containing blank organic phase generated during the rare earth extraction process by using the above-mentioned coalescence separation system.

[0012] The present invention adopts the following technical solutions to achieve the above objects.

[0013] On the one hand, the present invention provides a coalescence separation system for aqueous organic phase in the rare earth extraction process, comprising a pre-filtering unit and a coalescence separation unit;

[0014] The pre-filtering unit includes a pre-filter, which is configured to pre-filter the aqueous blank organic phase to remove solid particles, obtaining the pre-filtered aqueous blank organic phase; wherein, the aqueous blank organic phase is obtained by hydrochloric acid back-extraction and pure water washing during the rare earth extraction process;

[0015] The coalescence separation unit includes a horizontal coalescence separator; the horizontal coalescence separator includes a horizontal coalescence separator body and coalescence filter elements; the coalescence filter elements are arranged inside the horizontal coalescence separator body;

[0016] The horizontal coalescence separator body has a liquid inlet, a water outlet and an organic phase outlet; the liquid inlet is located at one end of the horizontal coalescence separator body; the water outlet is located at the bottom of the horizontal coalescence separator body and is far away from the liquid inlet; the organic phase outlet is located at the top of the horizontal coalescence separator body and is far away from the liquid inlet;

[0017] The horizontal coalescence separator is connected to the pre-filter through the liquid inlet, and is used for receiving the pre-filtered aqueous blank organic phase, separating the water in the pre-filtered aqueous blank organic phase, and discharging the separated blank organic phase from the organic phase outlet and the separated water phase from the water outlet;

[0018] The outer layer of the coalescence filter element is a polyperfluoroethylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer; the theoretical use flow rate of a single coalescence filter element is less than or equal to 1.5m 3 / h.

[0019] According to the coalescence separation system for aqueous organic phase in the rare earth extraction process of the present invention, preferably, the pre-filter includes a pre-filter body and a pre-filter element, and the pre-filter element is detachably arranged inside the pre-filter body; the pre-filter element is formed by a polypropylene fiber membrane, with a filtration accuracy of 0.2 - 10μm, a diameter of 55 - 70mm, and a length of 250 - 1000mm; the pre-filter body is made of carbon steel and uses a sodium-treated polytetrafluoroethylene plate as the inner lining.

[0020] According to the coalescence separation system for aqueous organic phase in the rare earth extraction process of the present invention, preferably, it further includes a first centrifugal pump, a first electric control valve, a first flowmeter and a PLC control unit; wherein,

[0021] The first centrifugal pump is configured to pump the aqueous blank organic phase from the rare earth extraction separation tank into the pre-filter;

[0022] The first electric control valve is arranged on the pipeline between the first centrifugal pump and the pre-filter, and is used to control the flow rate of the water-containing blank organic phase entering the pre-filter;

[0023] The first flowmeter is arranged on the pipeline between the first electric control valve and the pre-filter, and is used to measure the flow rate of the water-containing blank organic phase entering the pre-filter;

[0024] The first centrifugal pump, the first electric control valve and the first flowmeter are respectively electrically connected to the PLC control unit.

[0025] For the water-containing organic phase coalescence and separation system in the rare earth extraction process according to the present invention, preferably:

[0026] The horizontal coalescence separator further includes a liquid collection tank for collecting the separated aqueous phase;

[0027] The coalescence and separation system further includes a liquid level gauge for measuring the liquid level of the liquid collection tank; the liquid level gauge is electrically connected to the PLC control unit.

[0028] For the water-containing organic phase coalescence and separation system in the rare earth extraction process according to the present invention, preferably, the body of the horizontal coalescence separator is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder; the coalescence filter element is a high-efficiency liquid-liquid coalescence filter element of Hangzhou Cobetter Filter Materials Co., Ltd., with the brand number PH-FPF.

[0029] For the water-containing organic phase coalescence and separation system in the rare earth extraction process according to the present invention, preferably, it further includes a separated aqueous phase reuse unit, which includes a second centrifugal pump, a second electric control valve and a second flowmeter; wherein, the second centrifugal pump is used to pump the aqueous phase separated by the horizontal coalescence separator into the rare earth extraction and separation tank; the second flowmeter is arranged on the pipeline between the second centrifugal pump and the rare earth extraction and separation tank, and is used to measure the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank; the second electric control valve is arranged on the pipeline between the second centrifugal pump and the second flowmeter, and is used to control the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank, or the second electric control valve is arranged on the pipeline between the horizontal coalescence separator and the second centrifugal pump.

[0030] For the water-containing organic phase coalescence and separation system in the rare earth extraction process according to the present invention, preferably, it further includes a separated organic phase reuse unit, which includes a third flowmeter, and the third flowmeter is used to measure the flow rate of the separated blank organic phase discharged from the organic phase outlet of the horizontal coalescence separator to the rare earth extraction and separation tank.

[0031] On the other hand, the present invention also provides a method for removing water from a water-containing blank organic phase produced during a rare earth extraction process using the above-mentioned coalescence separation system, comprising the following steps:

[0032] 1) transporting the aqueous blank organic phase to the pre-filter, pre-filtering the aqueous blank organic phase through the pre-filter to remove solid particles, and obtaining a pre-filtered aqueous blank organic phase; wherein the water content in the aqueous blank organic phase is 8×10 3 ppm or more; the aqueous blank organic phase includes P507 or P204;

[0033] 2) introducing the pre-filtered aqueous blank organic phase obtained in step 1) into the horizontal coalescing separator for coalescing separation to obtain a separated aqueous phase and a separated blank organic phase; wherein the separated blank organic phase is discharged from the organic phase outlet, and the separated aqueous phase is discharged from the water outlet.

[0034] According to the method of the present invention, preferably, the organic phase in the aqueous blank organic phase is selected from any one of the following:

[0035] (a) A mixture of P507 and kerosene, wherein the volume ratio of P507 to kerosene is 1:1 to 2;

[0036] (b) A mixture of P204 and kerosene, wherein the volume ratio of P204 to kerosene is 1:1 to 2.

[0037] According to the method of the present invention, preferably, the water content of the aqueous blank organic phase is 1×10 4 ~5.5×10 4 ppm; the theoretical flow rate of a single coalescing filter element is 0.4 to 1.5 m 3 / h.

[0038] In the coalescence separation system of the aqueous organic phase during the rare earth extraction process of the present invention, trace water in the aqueous blank organic phase generated during the rare earth extraction process can be removed, and the water removal efficiency is greater than 80%, preferably greater than or equal to 81%, and even greater than or equal to 85%. The aqueous blank organic phase before treatment is significantly turbid and unclear, while the separated blank organic phase is clear, transparent, and bright. The aqueous phase is clear, oil-free, contains a small amount of hydrochloric acid and rare earth ions. Further, the coalescence separation system of the present invention has a high degree of automation and can continuously and stably remove impurities and trace water (including entrained water and emulsified water) in the aqueous blank organic phase generated during the rare earth extraction process. Moreover, the blank organic phase separated by the method of the present invention can be directly recycled to the saponification section or extraction section of the rare earth extraction process, improving the loading concentration during extraction, reducing the loss of saponifying agent and rare earth, and also extending the service life of the blank organic phase extractant; the separated aqueous phase containing a small amount of hydrochloric acid can be recycled to the stripping section of the rare earth extraction process, reducing acid consumption. In addition, the method of the present invention has a short process flow and is relatively simple to operate, which is beneficial to improving production efficiency and safety. Brief Description of the Drawings

[0039] Figure 1 It is a schematic structural diagram of a coalescence separation system of the aqueous organic phase during the rare earth extraction process of the present invention.

[0040] The descriptions of the reference numerals are as follows:

[0041] 10 - Prefiltration unit, 11 - Prefilter, 12 - First centrifugal pump, 13 - First electric control valve, 14 - First flowmeter;

[0042] 20 - Coalescence separation unit, 21 - Horizontal coalescence separator, 22 - Liquid level gauge;

[0043] 30 - PLC control unit;

[0044] 50 - Separated aqueous phase recycling unit, 51 - Second centrifugal pump, 52 - Second electric control valve, 53 - Second flowmeter;

[0045] 60 - Separated organic phase recycling unit, 61 - Third flowmeter;

[0046] 1 refers to the first - stage rare earth extraction and separation tank;

[0047] N refers to the last - stage rare earth extraction and separation tank, where N is a natural number greater than 10; N - m refers to the m - th rare earth extraction and separation tank in front of the last - stage rare earth extraction and separation tank, where m is a natural number greater than 1 and less than N. Detailed Embodiments

[0048] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0049] So far, although there have been many research reports on the coalescence separation method, there is no report on applying the coalescence separation method to remove trace water (mainly entrained water and emulsified water) in the water-containing blank organic phase generated during the rare earth extraction process. Therefore, the technical solution of removing trace water in the water-containing blank organic phase by using a horizontal coalescer with a specific coalescence filter element under specific conditions in this application does not belong to a conventional choice.

[0050] <Coalescence Separation System for Water-Containing Organic Phase in Rare Earth Extraction Process>

[0051] A coalescence separation system for water-containing organic phase in rare earth extraction process provided by the present invention includes a pre-filtering unit, a coalescence separation unit and a PLC control unit. Optionally, it further includes a rare earth extraction and separation tank, a separated aqueous phase recycling unit, and a separated organic phase recycling unit. The following is a detailed description.

[0052] Prefiltration unit and PLC control unit

[0053] The pre-filtering unit of the present invention includes a pre-filter, a first centrifugal pump, a first electric control valve and a first flow meter. This can remove solid particles in advance, which is beneficial to the subsequent coalescence separation of the organic phase and water, and is beneficial to extending the service life of the coalescence filter element in the horizontal coalescer. In addition, it is also beneficial to the automatic control of the system and improves production efficiency.

[0054] The pre-filter of the present invention is arranged to pre-filter the water-containing blank organic phase to remove solid particles, and obtain the pre-filtered water-containing blank organic phase. Among them, the water-containing blank organic phase is obtained by hydrochloric acid stripping and pure water washing during the rare earth extraction process.

[0055] In some embodiments, the pre-filter is a vertical pre-filter.

[0056] According to an embodiment of the present invention, the pre-filter includes a pre-filter body and a pre-filter element, and the pre-filter element is detachably arranged in the pre-filter body. According to a specific embodiment of the present invention, the pre-filter element is formed by a polypropylene fiber membrane, and the polypropylene fiber membrane is a fiber membrane formed by polypropylene material.

[0057] The number of pre-filter elements can be more than 1, preferably more than 2, for example, it can be 2 to 25. The pre-filter elements can be used in parallel, which can improve the processing capacity.

[0058] The filtration accuracy of a single pre-filter element is 0.2 to 10 μm, preferably 0.4 to 5 μm, more preferably 0.4 to 1.0 μm, still more preferably 0.45 to 0.8 μm, and even more preferably 0.45 to 0.6 μm. The diameter of a single pre-filter element is 55 to 70 mm, preferably 60 to 70 mm, more preferably 63 to 68 mm. The length of a single pre-filter element is 250 to 1000 mm, preferably 500 to 1000 mm, still more preferably 700 to 900 mm, and even more preferably 750 to 850 mm. The source of the pre-filter element is not particularly limited. According to a specific embodiment of the present invention, the pre-filter element is purchased from Hangzhou Cnpt Filter Co., Ltd., and the product number is JHPPWC.

[0059] According to a specific embodiment of the present invention, the pre-filter body is made of carbon steel, formed by welding, and uses a sodium-treated polytetrafluoroethylene plate as the inner lining.

[0060] In the present invention, the first centrifugal pump is arranged to pump the water-containing blank organic phase from the rare earth extraction and separation tank (the rare earth extraction and separation tank storing the water-containing blank organic phase, which can be, for example, the last-stage rare earth extraction and separation tank) into the pre-filter. The first electric control valve is arranged on the pipeline between the first centrifugal pump and the pre-filter to control the flow rate of the water-containing blank organic phase entering the pre-filter. The first flowmeter is arranged on the pipeline between the first electric control valve and the pre-filter to measure the flow rate of the water-containing blank organic phase entering the pre-filter.

[0061] The first centrifugal pump, the first electric control valve, and the first flowmeter are respectively electrically connected to the PLC control unit. This is beneficial for automatic control. The first centrifugal pump can be a magnetic drive centrifugal pump. The first flowmeter can be an electromagnetic flowmeter or a clamp-on flowmeter.

[0062] Coalescence separation unit and PLC control unit

[0063] The coalescence and separation unit of the present invention includes a horizontal coalescence separator and a liquid level gauge.

[0064] In the present invention, the horizontal coalescence separator includes a horizontal coalescence separator body, coalescence filter elements, and also includes a liquid collection tank.

[0065] The horizontal coalescence separator body has a liquid inlet, a water outlet, and an organic phase outlet. The liquid inlet is located at one end of the horizontal coalescence separator body, near the end close to the pre-filter. The water outlet is located at the bottom of the horizontal coalescence separator body and is far from the liquid inlet. The organic phase outlet is located at the top of the horizontal coalescence separator body and is far from the liquid inlet.

[0066] The horizontal coalescing separator is connected to the pre-filter through the liquid inlet, and is used to receive the pre-filtered water-containing blank organic phase. The water in the pre-filtered water-containing blank organic phase can be separated through the coalescing filter element. The separated blank organic phase is discharged from the organic phase outlet, and the separated water phase is discharged from the water outlet.

[0067] According to a specific embodiment of the present invention, the body of the horizontal coalescing separator is made of carbon steel and formed by welding. The inner wall of the body of the horizontal coalescing separator is sprayed with polytetrafluoroethylene powder.

[0068] In the present invention, the liquid collecting tank is connected to the water outlet, and the liquid collecting tank is used to collect the separated water phase discharged from the water outlet. The bottom of the liquid collecting tank has a drain port. The liquid level gauge is used to measure the liquid level of the liquid collecting tank; the liquid level gauge is electrically connected to the PLC control unit and can control the start and stop of the transfer pump.

[0069] In the present invention, the coalescing filter element is detachably fixed in the body of the horizontal coalescing separator.

[0070] According to a specific embodiment of the present invention, the coalescing filter element has a multi-layer gradient pore structure. The inner layer of the coalescing filter element serves as a demulsification layer, and the inner layer material is folded to form the demulsification layer. The outer layer serves as a coalescing layer, and the outer layer material is wound to form the coalescing layer. The outer layer of the coalescing filter element is a perfluoroethylenepropylene fiber layer, and the outer layer is in a wound state and wound outside the inner layer. The cross-section of the outer layer is circular. The perfluoroethylenepropylene fiber layer is formed by perfluoroethylenepropylene material FEP. The inner layer is a polytetrafluoroethylene fiber layer, and the cross-section of the inner layer is circular. The polytetrafluoroethylene fiber layer is formed by polytetrafluoroethylene material PTFE. The inner layer material and the outer layer material can be obtained by electrospinning and surface modification. The surface modification is preferably surface grafting modification to improve the hydrophilic and oleophobic characteristics. The average precision of the coalescing filter element is not greater than 5μm. Using such a coalescing filter element is beneficial to improving the water removal efficiency.

[0071] The number of coalescing filter elements can be more than 1, preferably more than 2, more preferably more than 5, for example, 5 to 45. Multiple coalescing filter elements are arranged in parallel in the body of the horizontal coalescing separator. More coalescing filter elements can improve the processing capacity of the coalescing filter.

[0072] The length of a single coalescing filter element can be 100 - 1000 mm, preferably 125 - 1000 mm, for example, it can be 125 mm, 250 mm, 500 mm, 750 mm, 1000 mm. The diameter of a single coalescing filter element can be 55 - 70 mm, preferably 60 - 70 mm, more preferably 63 - 68 mm.

[0073] In the present invention, the theoretical flow rate of a single coalescing filter element is less than or equal to 1.5 m 3 / h (i.e., 25 L / min), preferably 0.4 - 1.5 m3 / h, for example, it can be 1.5 m 3 / h, 1.0 m 3 / h, 0.6 m 3 / h, 0.5 m 3 / h. The actual flow rate used is less than or equal to the theoretical flow rate used.

[0074] According to an embodiment of the present invention, the theoretical flow rate used for a single coalescing filter element is less than or equal to the theoretical flow rate used for a single pre-filter element.

[0075] According to a specific embodiment of the present invention, the coalescing filter element is a high-efficiency liquid-liquid coalescing filter element of Hangzhou Cobetter Filter Co., Ltd., with the brand number PH-FPF. Through a large amount of research and experiments in the present invention, it is found that using such a coalescing filter element is beneficial to improving the water removal efficiency.

[0076] Separated aqueous phase reuse unit

[0077] The separated water phase reuse unit of the present invention includes a second centrifugal pump, a second electric control valve, and a second flow meter. This can return the water phase separated by the horizontal coalescing separator to the stripping section more quickly and accurately.

[0078] In the present invention, the second centrifugal pump is used to pump the water phase separated by the horizontal coalescing separator into the rare earth extraction and separation tank. Since it contains a certain amount of hydrochloric acid, it can be used for the stripping section. According to actual needs, the water phase separated by the horizontal coalescing separator can be pumped into the corresponding rare earth extraction and separation tank in the stripping section. For example, the water phase separated by the horizontal coalescing separator can be pumped into the N-mth stage rare earth extraction and separation tank, but it is not limited to the N-mth stage rare earth extraction and separation tank. It should be noted here that the last stage rare earth extraction and separation tank can be denoted as the Nth stage rare earth extraction and separation tank, where N is a natural number greater than 10; m is a natural number greater than 1 and less than N.

[0079] In the present invention, the second flow meter is arranged on the pipeline between the second centrifugal pump and the rare earth extraction and separation tank, and is used to measure the flow rate of the separated water phase pumped into the rare earth extraction and separation tank.

[0080] In some embodiments, the second electric control valve is arranged on the pipeline between the second centrifugal pump and the second flow meter, and is used to control the flow rate of the separated water phase pumped into the rare earth extraction and separation tank. In other embodiments, the second electric control valve is arranged on the pipeline between the second centrifugal pump and the horizontal coalescing separator, and is used to control the flow rate of the separated water phase pumped into the rare earth extraction and separation tank.

[0081] In the present invention, the second centrifugal pump may be a magnetically driven centrifugal pump. The second flow meter may be an electromagnetic flow meter or a clamp-type flow meter. The second centrifugal pump, the second electric regulating valve and the second flow meter are electrically connected to the PLC control unit respectively. This is conducive to automatic control.

[0082] Separated organic phase reuse unit

[0083] The separated organic phase recycling unit of the present invention includes a third flowmeter, which is used to measure the flow rate of the separated blank organic phase discharged from the organic phase outlet of the horizontal coalescing separator to the rare earth extraction separation tank. The third flowmeter is arranged on the pipeline between the horizontal coalescing separator and the rare earth extraction separation tank of the extraction section. The rare earth extraction separation tank is a rare earth extraction separation tank of the extraction section using an organic phase as an extractant. For example, it can be a first-stage rare earth extraction separation tank, but is not limited to a first-stage rare earth extraction separation tank.

[0084] In the present invention, the third flow meter is electrically connected to the PLC control unit. The third flow meter may be an electromagnetic flow meter or a clamp-type flow meter.

[0085] <Method>

[0086] The present invention also provides a method for removing water from an aqueous blank organic phase generated in the rare earth extraction process by using the aqueous organic phase coalescence separation system in the rare earth extraction process as described above, comprising the following steps:

[0087] 1) The aqueous blank organic phase is transported to a pre-filter, and the aqueous blank organic phase is pre-filtered by the pre-filter to remove solid particles, thereby obtaining a pre-filtered aqueous blank organic phase; wherein the aqueous blank organic phase is obtained by hydrochloric acid back extraction and pure water washing during the rare earth extraction process; the water content in the aqueous blank organic phase is 8×10 3 ppm or more; the aqueous blank organic phase includes P507 or P204; the H + The concentration is above 1 mol / L, and the concentration of organic matter P507 or P204 is 1 to 1.5 mol / L;

[0088] 2) introducing the pre-filtered blank organic phase into a horizontal coalescing separator and passing through a coalescing filter element for coalescing separation to obtain a separated aqueous phase and a separated blank organic phase; wherein the separated blank organic phase is discharged from the organic phase outlet, and the separated aqueous phase is discharged from the water outlet.

[0089] In the present invention, the organic phase in the aqueous blank organic phase is selected from any one of the following:

[0090] (a) A mixture of P507 and kerosene, wherein the volume ratio of P507 to kerosene is 1:1 to 2;

[0091] (b) A mixture of P204 and kerosene; wherein, the volume ratio of P204 to kerosene is 1:1 to 2.

[0092] In the present invention, the blank organic phase refers to the organic phase not loaded with rare earths. The water content of the aqueous blank organic phase is preferably 1×10 4 to 5.5×10 4 ppm, more preferably 1.1×10 4 to 3.5×10 4 ppm, and still more preferably 1.2×10 4 to 3.0×10 4 ppm.

[0093] In the present invention, the aqueous blank organic phase includes P507 or P204. The chemical name of P507 is 2-ethylhexyl phosphoric acid (mono-2-ethylhexyl) ester, and its molecular formula is C 16 H 35 O3P, which is a colorless or light yellow transparent oily liquid. The name of P204 is bis(2-ethylhexyl) phosphate, and its chemical formula is C 16 H 35 O4P.

[0094] According to a specific embodiment of the present invention, the organic phase in the aqueous blank organic phase is a mixture of P507 and kerosene, wherein the volume ratio of P507 to kerosene is 1:1. According to another specific embodiment of the present invention, the organic phase in the aqueous blank organic phase is a mixture of P204 and kerosene, wherein the volume ratio of P204 to kerosene is 1:2.

[0095] In step 2), the theoretical flow rate of a single coalescing filter element is less than or equal to 1.5 m 3 / h (i.e., 25 L / min), preferably 0.4 to 1.5 m 3 / h. For example, it can be 1.5 m 3 / h, 1.0 m 3 / h, 0.6 m 3 / h, 0.5 m 3 / h. The actual flow rate is less than or equal to the theoretical flow rate. According to a specific embodiment of the present invention, the coalescing filter element is a high-efficiency liquid-liquid coalescing filter element of Hangzhou Kebaite Filter Equipment Co., Ltd., with the brand number PH-FPF. The separated aqueous phase is an aqueous phase containing hydrochloric acid and rare earth ions. In the separated aqueous phase, the concentration of hydrochloric acid is above 2 mol / L. For example, it can be 2.46 mol / L, 3.12 mol / L.

[0096] According to a specific embodiment of the present invention, the actual flow rate of the horizontal coalescing separator is the same as that of the pre-filter.

[0097] In Step 1) and Step 2), the pressure is controlled to be less than or equal to 0.14 MPa, for example, it can be 0.1 MPa or 0.07 MPa. If the ambient temperature ≤ 10 °C, measures such as external heating and heat preservation can be taken to ensure the operation effect of the equipment.

[0098] In the present invention, the water removal efficiency is greater than 80%, preferably greater than or equal to 81%, more preferably greater than or equal to 85%, and even up to greater than or equal to 90%.

[0099] The method of the present invention may further include a step of recycling the separated aqueous phase and a step of recycling the separated blank organic phase.

[0100] Among them, the step of recycling the separated aqueous phase specifically includes: the separated aqueous phase passes through the water outlet of the horizontal coalescing separator body and finally discharges from the drain port of the liquid collection tank, and then is pumped into the stripping section of the rare earth extraction and separation tank through the separated aqueous phase recycling unit for recycling. The rare earth extraction and separation tank in the stripping section here can be the N-mth stage rare earth extraction and separation tank, but is not limited to the N-mth stage rare earth extraction and separation tank.

[0101] Among them, the step of recycling the separated blank organic phase specifically includes: the separated blank organic phase is transported to the rare earth extraction and separation tank in the corresponding extraction section through the separated organic phase recycling unit for recycling. For example, it can be the first stage rare earth extraction and separation tank, but is not limited to the first stage rare earth extraction and separation tank.

[0102] The test methods used in the following examples are described as follows:

[0103] Water content: Measured by a Karl Fischer moisture analyzer.

[0104] Example 1

[0105] Figure 1 It is a schematic structural diagram of a coalescence separation system for water-containing organic phase in a rare earth extraction process of the present invention. Figure 1 In the figure, the dotted line represents an electrical connection, and the arrow represents the liquid flow direction. Figure 1 In the figure, it is shown that there are multiple stages of rare earth extraction and separation tanks distributed between the first stage rare earth extraction and separation tank 1 and the last stage rare earth extraction and separation tank N. N is a natural number greater than 10. For example, N is 40, and the last stage rare earth extraction and separation tank N can be the fortieth stage rare earth extraction and separation tank. N-m refers to the mth rare earth extraction and separation tank in front of the last stage rare earth extraction and separation tank N. m is a natural number greater than 1 and less than N. For example, m is 6 (N-m = 34) or m is 7 (N-m = 33).

[0106] Such as Figure 1As shown in the figure, the coalescence separation system for the aqueous organic phase in the rare earth extraction process of this embodiment includes a pre-filtering unit 10, a coalescence separation unit 20, a PLC control unit 30, a separated aqueous phase recycling unit 50, and a separated organic phase recycling unit 60. It may also include rare earth extraction and separation tanks (multiple stages of rare earth extraction and separation tanks are provided. In this embodiment, the first-stage rare earth extraction and separation tank 1, the last-stage rare earth extraction and separation tank N, and the (N - m)-th stage rare earth extraction and separation tank are used for illustration).

[0107] The pre-filtering unit 10 includes a pre-filter 11, a first centrifugal pump 12, a first electric control valve 13, and a first flowmeter 14.

[0108] In this embodiment, the aqueous blank organic phase obtained by hydrochloric acid back-extraction and pure water washing during the rare earth extraction process is stored in the rare earth extraction and separation tank in the back-extraction section. For example, specifically, it is stored in the last-stage rare earth extraction and separation tank N.

[0109] The pre-filter 11 is used to receive the aqueous blank organic phase from the rare earth extraction and separation tank (such as from the last-stage rare earth extraction and separation tank N), and pre-filter the aqueous blank organic phase to remove solid particles, obtaining the pre-filtered aqueous blank organic phase.

[0110] The pre-filter 11 includes a pre-filter body and a pre-filter element. The pre-filter body is made of carbon steel and uses a sodium-treated polytetrafluoroethylene plate as the inner lining. The pre-filter element is detachably arranged in the pre-filter body. The pre-filter element is formed by a polypropylene fiber membrane, and its filtration accuracy is 0.45 - 1.0 μm. In this embodiment, the accuracy of the pre-filter element is specifically 0.45 μm. The diameter of the pre-filter element is 55 - 68 mm, and the length is 250 - 850 mm. In this embodiment, the diameter of the pre-filter element is specifically 68 mm, and the length is 500 mm. In this embodiment, the pre-filter element is purchased from Hangzhou Cobetter Filter Materials Co., Ltd., with the brand number JHPPWC.

[0111] In this embodiment, the first centrifugal pump 12 is used to pump the aqueous blank organic phase from the last-stage rare earth extraction and separation tank N into the pre-filter 11. The first centrifugal pump 12 can be a magnetic drive centrifugal pump. The first electric control valve 13 is arranged on the pipeline between the first centrifugal pump 12 and the pre-filter 11, and is used to control the flow rate of the aqueous blank organic phase entering the pre-filter 11. The first flowmeter 14 is arranged on the pipeline between the first electric control valve 13 and the pre-filter 11, and is used to measure the flow rate of the aqueous blank organic phase entering the pre-filter 11. The first flowmeter 14 is an electromagnetic flowmeter.

[0112] The first centrifugal pump 12, the first electric control valve 13, and the first flowmeter 14 are respectively electrically connected to the PLC control unit 30.

[0113] The coalescence separation unit 20 is used to receive the pre-filtered water-containing blank organic phase from the pre-filter unit 10 and perform coalescence separation, so as to remove the trace water in the water-containing blank organic phase.

[0114] The coalescence separation unit 20 includes a horizontal coalescence separator 21 and a liquid level gauge 22.

[0115] The horizontal coalescence separator 21 includes a horizontal coalescence separator body, coalescence filter elements, and a liquid collection tank.

[0116] The horizontal coalescence separator body has a liquid inlet, a water outlet, and an organic phase outlet. The liquid inlet is located at one end of the horizontal coalescence separator body. The water outlet is located at the bottom of the horizontal coalescence separator body and is far away from the liquid inlet. The organic phase outlet is located at the top of the horizontal coalescence separator body and is far away from the liquid inlet.

[0117] The horizontal coalescence separator 21 is connected to the pre-filter 11 through the liquid inlet, used to receive the pre-filtered blank organic phase, and separates the trace water (mainly entrained water and emulsified water) in the pre-filtered blank organic phase through coalescence separation. The separated blank organic phase is discharged from the organic phase outlet, and the separated water phase is discharged from the water outlet.

[0118] The horizontal coalescence separator body is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder.

[0119] The coalescence filter elements are detachably arranged in the horizontal coalescence separator body. The outer layer of the coalescence filter element is a perfluoroethylenepropylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer. The inner layer of the coalescence filter element serves as a demulsification layer, and the outer layer serves as a coalescence layer. The inner layer material is folded to form the demulsification layer, and the outer layer material is wound to form the coalescence layer. The outer layer material is wound outside the inner layer. The cross-sections of the inner layer and the outer layer are both circular rings. In this embodiment, the coalescence filter element is specifically the high-efficiency liquid-liquid coalescence filter element of Hangzhou Cnpt Filter Co., Ltd., with the model number PH-FPF. The diameter of the coalescence filter element is 68 mm, the length is 125 mm, and the average precision of the coalescence filter element is 5 μm. The theoretical flow rate of a single coalescence filter element is less than or equal to 1.5 m 3 / h, for example, less than or equal to 0.5 m 3 / h (i.e., about 8.33 L / min).

[0120] The liquid collection tank is arranged below the horizontal coalescence separator body, and the water outlet is connected to the liquid collection tank. A drain port is provided at the bottom of the liquid collection tank. The liquid collection tank is used to collect the separated water phase, and the separated water phase is finally discharged through the drain port. The liquid level gauge 22 is used to measure the liquid level of the liquid collection tank. The liquid level gauge 22 is electrically connected to the PLC control unit 30.

[0121] The separated aqueous phase returns to the rare earth extraction and separation tank in the stripping section through the separated aqueous phase reuse unit 50 for stripping use. The separated aqueous phase reuse unit 50 includes a second centrifugal pump 51, a second electric control valve 52, and a second flowmeter 53. The second centrifugal pump 51 is used to pump the aqueous phase separated by the horizontal coalescer 21 into the rare earth extraction and separation tank for stripping (i.e., entering the stripping section), for example, it can be the N-mth stage rare earth extraction and separation tank. The second centrifugal pump 51 can be a magnetic drive centrifugal pump. The second flowmeter 53 is arranged on the pipeline between the second centrifugal pump 51 and the rare earth extraction and separation tank in the stripping section, and is used to measure the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank in the stripping section. The second flowmeter 53 is an electromagnetic flowmeter. The second electric control valve 52 is arranged on the pipeline between the second centrifugal pump 51 and the second flowmeter 53, and is used to control the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank in the stripping section.

[0122] The second centrifugal pump 51, the second electric control valve 52, and the second flowmeter 53 are respectively electrically connected to the PLC control unit 30.

[0123] The separated blank organic phase returns to the rare earth extraction and separation tank in the extraction section through the separated organic phase reuse unit 60, for example, returns to the first-stage rare earth extraction and separation tank 1 for extracting the rare earth feed solution. The separated organic phase reuse unit 60 includes a third flowmeter 61. The third flowmeter 61 is used to measure the flow rate of the separated blank organic phase discharged from the organic phase outlet of the horizontal coalescer 21 to the first-stage rare earth extraction and separation tank 1. The third flowmeter 61 is electrically connected to the PLC control unit 30.

[0124] Example 2

[0125] This embodiment provides a method for removing water from the water-containing organic phase in the rare earth extraction process using the water-containing organic phase coalescence and separation system of Embodiment 1, including the following steps:

[0126] Use the first centrifugal pump 12 to pump the water-containing blank organic phase (this water-containing blank organic phase contains P204 and kerosene, the volume ratio of P204 to kerosene is 1:2, the water content is 51250 ppm, and it is relatively turbid) generated during the extraction of the rare earth sulfate feed solution from the last-stage rare earth extraction and separation tank N into the pre-filter 11. In the pre-filter 11, a single pre-filter element is used. Adjust the flow rate through the first electric control valve 13, and measure the flow rate of the water-containing blank organic phase pumped into the pre-filter 11 through the first flowmeter 14, control the actual use flow rate of the pre-filter 11 to be 1.5 L / min, and filter out solid particles through the pre-filter 11 to obtain the pre-filtered water-containing blank organic phase.

[0127] The pre-filtered water-containing blank organic phase is introduced into the horizontal coalescing separator 21 for coalescence separation. In the horizontal coalescing separator 21, a single coalescing filter element is used, and the actual flow rate of the horizontal coalescing separator 21 is controlled at 1.5 L / min to obtain the separated aqueous phase and the separated blank organic phase. The separated aqueous phase passes through the water outlet and finally discharges from the drain outlet of the liquid collection tank, and is pumped into the rare earth extraction and separation tank in the stripping section for recycling through the separated aqueous phase recycling unit 50. For example, it can be pumped into the N-mth stage rare earth extraction and separation tank for stripping. The separated aqueous phase contains hydrochloric acid, and the concentration of hydrochloric acid is 3.12 mol / L. The separated blank organic phase is transported to the first-stage rare earth extraction and separation tank 1 for recycling through the separated organic phase recycling unit 60. The water content of the separated blank organic phase is 4697 ppm, and it is clear and transparent.

[0128] Example 3

[0129] The difference between this embodiment and Embodiment 2 is only that: the sources of the water-containing blank organic phase are different, and the water contents are different. In this embodiment, the water-containing blank organic phase is the water-containing blank organic phase generated during the La-Ce-Pr-Nd combined extraction process, which contains P507 and kerosene. The volume ratio of P507 to kerosene is 1:1, and the water content is 19480 ppm, and it is relatively turbid.

[0130] The separation is carried out using the coalescence separation system of Embodiment 1. The separated aqueous phase is water containing hydrochloric acid, and the concentration of hydrochloric acid is 2.46 mol / L. The water content of the separated blank organic phase is 3563 ppm, and it is clear and transparent.

[0131] Comparative example 1

[0132] The difference between this comparative example and Embodiment 3 is only that the coalescing filter elements used are different. The brand of the coalescing filter element in this comparative example is PH-VF (its inner layer is a polytetrafluoroethylene fiber layer, and the outer layer is a polyvinylidene fluoride fiber layer). The water-containing blank organic phase is the water-containing blank organic phase generated during the La-Ce-Pr-Nd combined extraction process, which contains P507 and kerosene. The volume ratio of P507 to kerosene is 1:1, and the water content is 19480 ppm, and it is relatively turbid. The water content of the separated blank organic phase is 5240 ppm.

[0133] Example 4

[0134] The difference from Embodiment 1 is that in this embodiment, multiple pre-filter filter elements are used in parallel, multiple coalescing filter elements are used in parallel, and the lengths of the pre-filter filter elements and the coalescing filter elements are different. This can increase the throughput.

[0135] In the pre-filter 11 of this embodiment, 25 pre-filter cartridges are used in parallel. The diameter of a single pre-filter cartridge is 68 mm, and the length is 807.5 mm. The theoretical flow rate of a single pre-filter cartridge is 14 L / min. In the horizontal coalescing separator 21, 41 coalescing cartridges are used in parallel. The diameter of a single coalescing cartridge is 68 mm, and the length is 500 mm. The theoretical flow rate of a single coalescing cartridge is 0.5 m 3 / h (i.e., approximately 8.33 L / min).

[0136] The remaining structures and settings are the same as those in Embodiment 1.

[0137] Example 5 (scaled-up)

[0138] This embodiment provides a method for removing water from the water-containing organic phase by using the water-containing organic phase coalescing and separating system in the rare earth extraction process of Embodiment 4, including the following steps:

[0139] Use the first centrifugal pump 12 to pump the water-containing blank organic phase (this water-containing blank organic phase contains P204 and kerosene, the volume ratio of P204 to kerosene is 1:2, the water content is 28654 ppm, and it is relatively turbid) generated during the extraction process of the rare earth sulfate feed liquid from the last-stage rare earth extraction and separation tank N into the pre-filter 11. Adjust the flow rate through the first electric control valve 13, and measure the flow rate of the water-containing blank organic phase pumped into the pre-filter 11 through the first flow meter 14, and control the actual flow rate of the pre-filter 11 to be 250 L / min (the actual flow rate of a single pre-filter cartridge is 10 L / min). Filter out solid particles through the pre-filter 11 to obtain the pre-filtered water-containing blank organic phase.

[0140] Introduce the pre-filtered water-containing blank organic phase into the horizontal coalescing separator 21 for coalescing and separation, control the actual flow rate of the horizontal coalescing separator 21 to be 250 L / min (the actual flow rate of a single coalescing cartridge is approximately 6 L / min), to obtain the separated water phase and the separated blank organic phase. The separated water phase passes through the water outlet, and finally discharges from the drain outlet of the liquid collection tank, and is pumped into the rare earth extraction and separation tank in the stripping section for recycling through the separated water phase recycling unit 50, for example, it can be pumped into the N-mth stage rare earth extraction and separation tank for stripping. The separated water phase contains hydrochloric acid, and the concentration of hydrochloric acid is 2.14 mol / L. The separated blank organic phase is transported to the first-stage rare earth extraction and separation tank 1 for recycling through the separated organic phase recycling unit 60. The water content of the separated blank organic phase is 2835 ppm, and it is clear and transparent.

[0141] Table 1

[0142]

[0143] As can be seen from Table 1, the water removal efficiency of the method for removing trace water in the aqueous organic phase by using the coalescence separation system of the aqueous organic phase in the rare earth extraction process of the present invention is higher.

[0144] The present invention is not limited to the above embodiments. Without departing from the essence of the present invention, any variations, improvements, and substitutions that can be conceived by those skilled in the art fall within the scope of the present invention.

Claims

1. A method for removing water from the water-containing blank organic phase generated during rare earth extraction by using a coalescence separation system for water-containing organic phase in the rare earth extraction process, characterized in that the coalescence separation system for water-containing organic phase in the rare earth extraction process includes a pre-filtering unit and a coalescence separation unit; the pre-filtering unit includes a pre-filter, and the pre-filter is set to pre-filter the water-containing blank organic phase to remove solid particles, obtaining the pre-filtered water-containing blank organic phase; wherein, the water-containing blank organic phase is obtained by hydrochloric acid back-extraction and pure water washing during the rare earth extraction process; the pre-filter includes a pre-filter body and a pre-filter element, and the pre-filter element is detachably arranged in the pre-filter body; the pre-filter element is formed by a polypropylene fiber membrane; the number of pre-filter elements is more than 1; the filtration accuracy of a single pre-filter element is 0.2 - 5 μm, the diameter is 55 - 70 mm, and the length is 250 - 1000 mm; the coalescence separation unit includes a horizontal coalescer; the horizontal coalescer includes a horizontal coalescer body and a coalescence filter element; the coalescence filter element is detachably arranged in the horizontal coalescer body; the horizontal coalescer body has a liquid inlet, a water outlet and an organic phase outlet; the liquid inlet is located at one end of the horizontal coalescer body; the water outlet is located at the bottom of the horizontal coalescer body and is far away from the liquid inlet; the organic phase outlet is located at the top of the horizontal coalescer body and is far away from the liquid inlet; the horizontal coalescer is connected to the pre-filter through the liquid inlet, is used to receive the pre-filtered water-containing blank organic phase, and separate the water in the pre-filtered water-containing blank organic phase. The separated blank organic phase is discharged from the organic phase outlet, and the separated water phase is discharged from the water outlet; The outer layer of the coalescing filter element is a perfluoroethylene propylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer; the inner layer of the coalescing filter element serves as a demulsification layer, and the inner layer material is folded to form the demulsification layer, while the outer layer serves as a coalescing layer, and the outer layer material is wound to form the coalescing layer; the outer layer is in a wound state and is wound outside the inner layer; the cross-section of the outer layer is circular, and the cross-section of the inner layer is circular; the average precision of the coalescing filter element is not greater than 5 μm; there is one or more coalescing filter elements; the diameter of a single coalescing filter element is 55-70 mm, and the length is 100-1000 mm; the theoretical flow rate of a single coalescing filter element is less than or equal to 1.5 m 3 / h; this method includes the following steps: 1) Transport the aqueous blank organic phase to the pre-filter, and pre-filter the aqueous blank organic phase through the pre-filter to remove solid particles, obtaining the pre-filtered aqueous blank organic phase; wherein, the water content in the aqueous blank organic phase is 8×10 3 ppm or more; the organic phase in the aqueous blank organic phase is selected from any one of the following: (a) A mixture of P507 and kerosene; wherein, the volume ratio of P507 to kerosene is 1:1 - 2; (b) A mixture of P204 and kerosene; wherein, the volume ratio of P204 to kerosene is 1:1 - 2; 2) Import the pre-filtered water-containing blank organic phase obtained in step 1) into the horizontal coalescer for coalescence separation, obtaining the separated water phase and the separated blank organic phase; wherein, the separated blank organic phase is discharged from the organic phase outlet, and the separated water phase is discharged from the water outlet.

2. The method according to claim 1, wherein The organic phase in the water-containing blank organic phase is selected from any one of the following: (a) A mixture of P507 and kerosene; wherein, the volume ratio of P507 to kerosene is 1:1; (b) A mixture of P204 and kerosene; wherein, the volume ratio of P204 to kerosene is 1:

2.

3. The method according to claim 1, characterized in that, The water content of the aqueous blank organic phase is 1×10 4 ~5.5×10 4 ppm; the theoretical flow rate of a single coalescing filter element is 0.4~1.5 m 3 / h.

4. The method according to claim 1, wherein The pre-filter body is made of carbon steel and uses a sodium-treated polytetrafluoroethylene plate as the inner lining.

5. The method according to claim 1, wherein The coalescence separation system further includes a first centrifugal pump, a first electric control valve, a first flow meter and a PLC control unit; wherein, the first centrifugal pump is set to pump the water-containing blank organic phase from the rare earth extraction separation tank into the pre-filter; The first electric control valve is arranged on the pipeline between the first centrifugal pump and the pre-filter, and is used to control the flow rate of the water-containing blank organic phase entering the pre-filter; The first flowmeter is arranged on the pipeline between the first electric control valve and the pre-filter, and is used to measure the flow rate of the water-containing blank organic phase entering the pre-filter; The first centrifugal pump, the first electric control valve and the first flowmeter are respectively electrically connected to the PLC control unit.

6. The method according to claim 5, wherein: The horizontal coalescing separator further includes a liquid collection tank for collecting the separated aqueous phase; The coalescing separation system further includes a liquid level gauge for measuring the liquid level of the liquid collection tank; the liquid level gauge is electrically connected to the PLC control unit.

7. The method according to claim 6, wherein The body of the horizontal coalescing separator is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder.

8. The method according to claim 5, wherein The coalescing separation system further includes a separated aqueous phase recycling unit, which includes a second centrifugal pump, a second electric control valve and a second flowmeter; wherein, the second centrifugal pump is used to pump the aqueous phase separated by the horizontal coalescing separator into the rare earth extraction and separation tank; the second flowmeter is arranged on the pipeline between the second centrifugal pump and the rare earth extraction and separation tank, and is used to measure the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank; the second electric control valve is arranged on the pipeline between the second centrifugal pump and the second flowmeter, and is used to control the flow rate of the separated aqueous phase pumped into the rare earth extraction and separation tank, or the second electric control valve is arranged on the pipeline between the horizontal coalescing separator and the second centrifugal pump.

9. The method according to claim 1, wherein The coalescing separation system further includes a separated organic phase recycling unit, which includes a third flowmeter, and the third flowmeter is used to measure the flow rate of the separated blank organic phase discharged from the organic phase outlet of the horizontal coalescing separator to the rare earth extraction and separation tank.

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