Water-containing organic phase coalescence separation system and method in rare earth extraction process

Abstract

The invention discloses a water-containing organic phase coalescence separation system and method in a rare earth extraction process. The system comprises a pre-filtering unit and a coalescence separation unit, the pre-filtering unit comprises a pre-filter, and the coalescence separation unit comprises a horizontal coalescence separator; the pre-filter is used for pre-filtering the water-containing blank organic phase to remove solid particles so as to obtain a pre-filtered water-containing blank organic phase; wherein the water-containing blank organic phase is obtained through hydrochloric acid reverse extraction and pure water washing in the rare earth extraction process; the horizontal coalescence separator comprises a horizontal coalescence separator body and a coalescence filter element; the outer layer of the coalescence filter element is a fluorinated ethylene propylene fiber layer, and the inner layer of the coalescence filter element is a polytetrafluoroethylene fiber layer; and the theoretical use flow of the single coalescence filter element is less than or equal to 1.5 m < 3 > / h. The system can remove trace water in a water-containing blank organic phase generated in the rare earth extraction process, and the water removal efficiency is greater than 80%.

Description

Technical Field

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

[0002] In the extraction and separation process of rare earth elements, the organic phase extractant and the aqueous phase rare earth feed liquid undergo complexation reaction after high-intensity stirring in the mixing chamber, and then overflow into the clarification section, where the incomplete mutual solubility and density difference of the two phases are used for stratification and phase separation. However, the organic phase after short-term clarification still contains entrained water and a small amount of emulsified water, which are difficult to precipitate in a short time, resulting in a certain amount of water entrained in the loaded organic phase. These water phases not only reduce the extraction efficiency, but also cause the loss of rare earth elements and the increase of 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] At present, there are many reports on devices and methods for oil-water separation in oil-water systems.

[0004] CN113074168B discloses a hydraulic oil dewatering system and method for a thruster. The dewatering system includes a dewatering component, a first valve body, a buffer tank, a delivery pump and an oil return pipe. The dewatering component includes a treatment tank, a heater, a liquid inlet pipe and a water outlet pipe. The heater is arranged in the treatment tank for heating the hydraulic oil in the treatment tank. The treatment tank is connected to the thruster through the liquid inlet pipe. The gravity oil tank for supplying oil to the thruster is located at a higher height than the treatment tank. The first valve body is arranged on the liquid inlet pipe. The treatment tank 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 oil return pipe. The location height of the gravity oil tank is the same as that of the buffer tank. The system and method adopt a vacuum heating method to vaporize the water vapor in the hydraulic oil so that water and oil are separated. The system and method are not suitable for the aqueous organic phase produced by rare earth extraction. The organic phase of rare earth extraction contains about 50% of low-ignition-point solvent oil, which is easy to be dangerous if heated.

[0005] CN112121647A discloses an application of a super-hydrophilic and super-oleophobic oil-water separation ceramic membrane. The 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, cleaning is difficult, and the operating cost is high. Moreover, the oil-water separation ceramic membrane is not suitable for the separation of trace water in the aqueous organic phase produced by rare earth extraction.

[0006] CN109295302A discloses an emulsion treatment device and method in the rare earth extraction production process, the treatment device comprises: 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. The device and method can be applied to the oil-water separation of the aqueous organic phase generated in the rare earth extraction production process, but are more suitable for oil-in-water systems with higher water content, and are not applicable to the oil-water separation containing trace water.

[0007] CN117732109A discloses a method for removing hydrochloric acid entrained after organic stripping in industrial rare earth extraction, comprising adding wash water to the last two extraction tanks after adding hydrochloric acid in the lanthanum, cerium, praseodymium and neodymium separation line, so that the wash water and organic are countercurrently stripped. This method can basically solve the problem that a large amount of hydrochloric acid is entrained in the organic phase after stripping, and it is difficult to separate and recover the hydrochloric acid even if it is left to stand and clarified, resulting in a large amount of waste of hydrochloric acid. It also does not solve the problem of emulsified water in the organic phase, but is not suitable for removing trace water in the aqueous blank organic phase generated in the rare earth extraction process.

[0008] CN103664629A discloses a nitrobenzene washing and separation system, which adopts a pipeline parallel flow washing method and adds a coalescing separator in the pipeline parallel flow washing process. The system is mainly used to remove sodium salts and phenol salts in crude nitrobenzene. The system does not mention what kind of coalescing filter element is used, and the nitrobenzene system is different from the aqueous blank organic phase produced by rare earth extraction.

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

[0010] So far, there is still no report on removing trace water from the aqueous organic phase produced during rare earth extraction by coagulation separation. Summary of the invention

[0011] In view of this, one object of the present invention is to provide a water-containing organic phase coalescence separation system in a rare earth extraction process, which can remove trace water in a water-containing blank organic phase generated in 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 from a water-containing blank organic phase generated in a rare earth extraction process using the above coalescence separation system.

[0012] The present invention adopts the following technical solutions to achieve the above-mentioned purpose.

[0013] In one aspect, the present invention provides a system for coalescing and separating an aqueous organic phase in a rare earth extraction process, comprising a pre-filtration unit and a coalescing and separating unit;

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

[0015] The coalescence separation unit comprises a horizontal coalescence separator; the horizontal coalescence separator comprises a horizontal coalescence separator body and a coalescence filter element; the coalescence filter element is arranged in the horizontal coalescence separator body;

[0016] The horizontal coalescing 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 coalescing separator body; the water outlet is located at the bottom of the horizontal coalescing separator body and is away from the liquid inlet; the organic phase outlet is located at the top of the horizontal coalescing separator body and is away from the liquid inlet;

[0017] The horizontal coalescing separator is connected to the pre-filter through the liquid inlet, and is used to receive the pre-filtered aqueous blank organic phase, and separate the water in the pre-filtered aqueous blank organic phase, and the separated blank organic phase is discharged from the organic phase outlet, and the separated aqueous phase is discharged from the water outlet;

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

[0019] According to the aqueous organic phase coalescence and separation system in the rare earth extraction process of the present invention, preferably, the pre-filter comprises 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, and its filtration accuracy is 0.2-10 μm, the diameter is 55-70 mm, and the length is 250-1000 mm; the pre-filter body is made of carbon steel, and a sodium-treated polytetrafluoroethylene plate is used as an inner lining.

[0020] According to the aqueous organic phase coalescence separation system in the rare earth extraction process of the present invention, preferably, it also includes a first centrifugal pump, a first electric regulating valve, a first flow meter 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 regulating valve is disposed on the pipeline between the first centrifugal pump and the pre-filter, and is used to control the flow rate of the aqueous blank organic phase entering the pre-filter;

[0023] The first flow meter is disposed on the pipeline between the first electric regulating valve and the pre-filter, and is used to measure the flow rate of the aqueous blank organic phase entering the pre-filter;

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

[0025] According to the aqueous organic phase coalescence separation system in the rare earth extraction process of the present invention, preferably:

[0026] The horizontal coalescing separator also includes a liquid collecting tank for collecting the separated water phase;

[0027] The coalescence separation system further comprises a liquid level meter, which is used to measure the liquid level of the liquid collecting tank; the liquid level meter is electrically connected to the PLC control unit.

[0028] According to the aqueous organic phase coalescing and separation system in the rare earth extraction process described in the present invention, preferably, the horizontal coalescing separator body is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder; the coalescing filter element is a high-efficiency liquid-liquid coalescing filter element of Hangzhou Kebet Filter Equipment Co., Ltd., with a brand name of PH-FPF.

[0029] According to the aqueous organic phase coagulation and separation system in the rare earth extraction process of the present invention, preferably, it also includes a separated water phase recycling unit, which includes a second centrifugal pump, a second electric regulating valve and a second flow meter; wherein the second centrifugal pump is used to pump the water phase separated by the horizontal coagulation separator into the rare earth extraction separation tank; the second flow meter is arranged on the pipeline between the second centrifugal pump and the rare earth extraction separation tank, and is used to measure the flow rate of the separated water phase pumped into the rare earth extraction separation tank; the second electric regulating 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 separation tank, or the second electric regulating valve is arranged on the pipeline between the horizontal coagulation separator and the second centrifugal pump.

[0030] According to the aqueous organic phase coagulation and separation system in the rare earth extraction process of the present invention, preferably, it also 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 coagulation separator to the rare earth extraction 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] The aqueous organic phase coalescence separation system in the rare earth extraction process of the present invention can remove trace water in the aqueous blank organic phase generated in the rare earth extraction process, 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 obviously turbid and unclear, while the separated blank organic phase is clear, transparent and bright, and the aqueous phase is clear and oil-free, containing 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 in the rare earth extraction process. In addition, the blank organic phase separated by the method of the present invention can be directly reused in the saponification section or extraction section of the rare earth extraction process, improve the load concentration during extraction, reduce the loss of saponifiers and rare earths, and extend the service life of the blank organic phase extractant; the separated aqueous phase containing a small amount of hydrochloric acid can be reused in the stripping section of the rare earth extraction process to reduce acid consumption. In addition, the method of the present invention has a short process flow and is relatively simple to operate, which is conducive to improving production efficiency and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a schematic structural diagram of an aqueous organic phase agglomeration and separation system in a rare earth extraction process.

[0040] The following are the descriptions of the reference numerals:

[0041] 10-pre-filter unit, 11-pre-filter, 12-first centrifugal pump, 13-first electric regulating valve, 14-first flow meter;

[0042] 20-coalescing and separation unit, 21-horizontal coalescing and separation device, 22-liquid level gauge;

[0043] 30-PLC control unit;

[0044] 50 - separated water phase recycling unit, 51 - second centrifugal pump, 52 - second electric regulating valve, 53 - second flow meter;

[0045] 60-separation organic phase recycling unit, 61-third flow meter;

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

[0047] N refers to the last rare earth extraction and separation tank, and N is a natural number greater than 10; Nm refers to the mth rare earth extraction and separation tank before the last rare earth extraction and separation tank, and m is a natural number greater than 1 and less than N. DETAILED DESCRIPTION

[0048] The present invention is 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 reports on the research of coalescence separation, there has been no report on the application of coalescence separation to the removal of trace water (mainly entrained water and emulsified water) in the aqueous blank organic phase generated during the rare earth extraction process. Therefore, the technical solution of removing trace water in the aqueous blank organic phase under specific conditions by using a horizontal coalescence separator with a specific coalescence filter element in the present application is not a conventional choice.

[0050] <Aqueous organic phase coalescence separation system in rare earth extraction process>

[0051] The present invention provides a water-containing organic phase coalescence separation system in a rare earth extraction process, comprising a pre-filtration unit, a coalescence separation unit and a PLC control unit. Optionally, it also comprises a rare earth extraction separation tank, a separation water phase recycling unit and a separation organic phase recycling unit. The system is described in detail below.

[0052] Pre-filtration unit and PLC control unit

[0053] The pre-filtration unit of the present invention comprises a pre-filter, a first centrifugal pump, a first electric regulating valve and a first flow meter. In this way, solid particles can be removed in advance, which is beneficial to the subsequent coalescence separation of the organic phase and water, and is beneficial to prolonging the life of the coalescence filter element in the horizontal coalescence separator. In addition, it can also be beneficial to the automatic control of the system and improve production efficiency.

[0054] The pre-filter of the present invention is configured to pre-filter the aqueous blank organic phase to remove solid particles, thereby obtaining the pre-filtered aqueous blank organic phase, wherein the aqueous blank organic phase is obtained by hydrochloric acid stripping and pure water washing during the rare earth extraction process.

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

[0056] According to one embodiment of the present invention, the pre-filter comprises a pre-filter body and a pre-filter element, wherein the pre-filter element is detachably disposed in the pre-filter body. According to one specific embodiment of the present invention, the pre-filter element is formed of a polypropylene fiber membrane, which is a fiber membrane formed of a polypropylene material.

[0057] The number of pre-filter cartridges may be one or more, preferably two or more, for example, 2 to 25. Multiple pre-filter cartridges may be used in parallel to improve the processing capacity.

[0058] The filtration accuracy of a single pre-filter element is 0.2-10 μm, preferably 0.4-5 μm, further preferably 0.4-1.0 μm, more preferably 0.45-0.8 μm, and even more preferably 0.45-0.6 μm. The diameter of a single pre-filter element is 55-70 mm, preferably 60-70 mm, and more preferably 63-68 mm. The length of a single pre-filter element is 250-1000 mm, preferably 500-1000 mm, more preferably 700-900 mm, and more preferably 750-850 mm. There is no particular restriction on the source of the pre-filter element. According to a specific embodiment of the present invention, the pre-filter element is purchased from Hangzhou Kebet Filter Equipment Co., Ltd., with the brand name 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 an inner lining.

[0060] In the present invention, the first centrifugal pump is configured to pump the aqueous blank organic phase from the rare earth extraction separation tank (the rare earth extraction separation tank storing the aqueous blank organic phase, for example, the last stage rare earth extraction separation tank) into the pre-filter. The first electric regulating valve is disposed on the pipeline between the first centrifugal pump and the pre-filter to control the flow rate of the aqueous blank organic phase entering the pre-filter. The first flow meter is disposed on the pipeline between the first electric regulating valve and the pre-filter to measure the flow rate of the aqueous blank organic phase entering the pre-filter.

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

[0062] Coalescing and separation unit and PLC control unit

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

[0064] In the present invention, the horizontal coalescing separator comprises a horizontal coalescing separator body and a coalescing filter element, and also comprises a liquid collecting tank.

[0065] The horizontal coalescing 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 coalescing separator body, close to one end of the pre-filter. The water outlet is located at the bottom of the horizontal coalescing separator body and away from the liquid inlet. The organic phase outlet is located at the top of the horizontal coalescing separator body and away 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 aqueous blank organic phase. The water in the pre-filtered aqueous 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 aqueous 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 is formed by welding, and 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 is provided with a drain port. The liquid level meter is used to measure the liquid level of the liquid collecting tank; the liquid level meter is electrically connected to the PLC control unit, and can control the start and stop of the delivery pump.

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

[0070] According to a specific embodiment of the present invention, the coalescing filter element is a multi-layer gradient pore structure. The inner layer of the coalescing filter element serves as a demulsifying layer, and the inner layer material is folded to form a demulsifying layer, and the outer layer serves as a coalescing layer, and the outer layer material is wound to form a coalescing layer. The outer layer of the coalescing filter element is a polytetrafluoroethylene propylene fiber layer, and the outer layer is in a wound state, wound on the outside of the inner layer, and the cross-section of the outer layer is annular. The polytetrafluoroethylene propylene fiber layer is formed of polytetrafluoroethylene material FEP. The inner layer is a polytetrafluoroethylene fiber layer, and the cross-section of the inner layer is annular. The polytetrafluoroethylene fiber layer is formed of 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 more than 5μm. The use of such a coalescing filter element is conducive to improving the water removal efficiency.

[0071] The number of coalescing filter elements may be one or more, preferably two or more, and more preferably five or more, for example, 5 to 45. Multiple coalescing filter elements are arranged in parallel in the horizontal coalescing separator body. More coalescing filter elements can improve the processing capacity of the coalescing filter.

[0072] The length of a single coalescing filter element may be 100-1000 mm, preferably 125-1000 mm, for example, 125 mm, 250 mm, 500 mm, 750 mm, 1000 mm. The diameter of a single coalescing filter element may 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. 25L / min), preferably 0.4-1.5m3 / h, for example, 1.5m 3 / h、1.0m 3 / h、0.6m 3 / h、0.5m 3 / h. The actual usage flow is less than or equal to the theoretical usage flow.

[0074] According to one embodiment of the present invention, the theoretical flow rate of a single coalescing filter element is less than or equal to the theoretical flow rate of 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 with a brand name of PH-FPF produced by Hangzhou Kebet Filter Equipment Co., Ltd. The present invention has found through extensive research and experiments that the use of such a coalescing filter element is conducive to improving water removal efficiency.

[0076] Separation water phase recycling unit

[0077] The separated water phase recycling unit of the present invention comprises a second centrifugal pump, a second electric regulating valve and a second flow meter, so that the water phase separated by the horizontal coalescing separator can be returned to the stripping section more quickly and accurately.

[0078] In the present invention, the second centrifugal pump is used to pump the aqueous phase separated by the horizontal coalescing separator into the rare earth extraction separation tank. Since it contains a certain amount of hydrochloric acid, it can be used in the stripping section. According to actual needs, the aqueous phase separated by the horizontal coalescing separator can be pumped into the rare earth extraction separation tank of the corresponding stripping section. For example, the aqueous phase separated by the horizontal coalescing separator can be pumped into the Nm-th rare earth extraction separation tank, but is not limited to the Nm-th rare earth extraction separation tank. It should be noted here that the last-stage rare earth extraction separation tank can be recorded as the Nth-stage rare earth extraction 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 regulating valve is disposed on the pipeline between the second centrifugal pump and the second flowmeter to control the flow rate of the separated water phase pumped into the rare earth extraction separation tank. In other embodiments, the second electric regulating valve is disposed on the pipeline between the second centrifugal pump and the horizontal coalescing separator to control the flow rate of the separated water phase pumped into the rare earth extraction 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] Separation and recycling unit of organic phase

[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 an organic phase without rare earth loading. The water content of the aqueous blank organic phase is preferably 1×10 4 ~5.5×10 4 ppm, more preferably 1.1×10 4 ~3.5×10 4 ppm, preferably 1.2×10 4 ~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 phosphate (mono-2-ethylhexyl) ester, and the molecular formula is C 16 H 35 O 3 P is a colorless or light yellow transparent oily liquid. The name of P204 is di(2-ethylhexyl) phosphate, and its chemical formula is C 16 H 35 O 4 P.

[0094] According to one 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 1.5m 3 / h (i.e. 25L / min), preferably 0.4-1.5m 3 / h, for example, 1.5m 3 / h, 1.0m 3 / h, 0.6m 3 / h, 0.5m 3 / h. The actual usage flow rate is less than or equal to the theoretical usage 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 Kebet Filter Equipment Co., Ltd., with a brand name of 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 or 3.12 mol / L.

[0096] According to a specific embodiment of the present invention, the actual use flow rate of the horizontal coalescing separator is the same as the actual use flow rate 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, 0.1 MPa or 0.07 MPa. If the ambient temperature is ≤10°C, external heating and heat preservation measures 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 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] The step of recycling the separated water phase specifically includes: the separated water phase passes through the water outlet of the horizontal coalescing separator body and is finally discharged from the drain outlet of the liquid collecting tank, and then is pumped into the stripping section of the rare earth extraction separation tank through the separated water phase recycling unit for recycling. The rare earth extraction separation tank of the stripping section here can be the Nm-th rare earth extraction separation tank, but is not limited to the Nm-th rare earth extraction separation tank.

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

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

[0103] Moisture content: measured by Karl Fischer titrator.

[0104] Example 1

[0105] Figure 1 The present invention is a schematic structural diagram of an aqueous organic phase agglomeration and separation system in a rare earth extraction process. Figure 1 In the figure, the dotted lines indicate electrical connections and the arrows indicate the direction of liquid flow. Figure 1 In the figure, there are multiple rare earth extraction and separation tanks distributed between the first rare earth extraction and separation tank 1 and the last rare earth extraction and separation tank N. N is a natural number greater than 10, for example, N is 40, and the last rare earth extraction and separation tank N can be the 40th rare earth extraction and separation tank. Nm refers to the mth rare earth extraction and separation tank before the last rare earth extraction and separation tank N, and m is a natural number greater than 1 and less than N, for example, m is 6 (Nm=34) or m is 7 (Nm=33).

[0106] like Figure 1 As shown, the aqueous organic phase coagulation and separation system in the rare earth extraction process of this embodiment includes a pre-filtration unit 10, a coagulation and separation unit 20, a PLC control unit 30, a separated aqueous phase recycling unit 50 and a separated organic phase recycling unit 60, and may also include a rare earth extraction separation tank (the rare earth extraction separation tank is arranged in multiple stages, and in this embodiment, the first-stage rare earth extraction separation tank 1, the last-stage rare earth extraction separation tank N, and the Nm-th-stage rare earth extraction 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 regulating valve 13 and a first flow meter 14 .

[0108] In this embodiment, the aqueous blank organic phase obtained by hydrochloric acid stripping and pure water washing during the rare earth extraction process is stored in the rare earth extraction separation tank of the stripping section, for example, specifically, stored in the last stage rare earth extraction 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 (for example, from the last rare earth extraction and separation tank N), and pre-filter the aqueous blank organic phase to remove solid particles to obtain a 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 a sodium-treated polytetrafluoroethylene plate is used as an 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 to 1.0 μm. In the present embodiment, the accuracy of the pre-filter element is specifically 0.45 μm. The diameter of the pre-filter element is 55 to 68 mm, and the length is 250 to 850 mm. In the present embodiment, the diameter of the pre-filter element is specifically 68 mm, and the length is 500 mm. In the present embodiment, the pre-filter element is purchased from Hangzhou Kebet Filter Equipment Co., Ltd., and the brand is 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 separation tank N into the pre-filter 11. The first centrifugal pump 12 can be a magnetically driven centrifugal pump. The first electric regulating 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 regulating 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 regulating valve 13 and the first flow meter 14 are electrically connected to the PLC control unit 30 , respectively.

[0113] The coalescence separation unit 20 is used to receive the pre-filtered aqueous blank organic phase from the pre-filtration unit 10 and perform coalescence separation, thereby removing trace amounts of water in the aqueous blank organic phase.

[0114] The coalescing and separating unit 20 includes a horizontal coalescing and separating vessel 21 and a liquid level meter 22 .

[0115] The horizontal coalescing separator 21 comprises a horizontal coalescing separator body, a coalescing filter element and a liquid collecting tank.

[0116] The horizontal coalescing 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 coalescing separator body. The water outlet is located at the bottom of the horizontal coalescing separator body and is far away from the liquid inlet. The organic phase outlet is located at the top of the horizontal coalescing separator body and is far away from the liquid inlet.

[0117] The horizontal coalescing separator 21 is connected to the pre-filter 11 through the liquid inlet, and is used to receive the blank organic phase after pre-filtration, and separate the trace water (mainly entrained water and emulsified water) in the blank organic phase after pre-filtration through coalescing 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 body of the horizontal coalescing separator is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder.

[0119] The coalescing filter element is detachably arranged in the horizontal coalescing separator body. The outer layer of the coalescing filter element is a polytetrafluoroethylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer. The inner layer of the coalescing filter element serves as a demulsifying layer, and the outer layer serves as a coalescing layer. The inner layer material is folded to form a demulsifying layer, and the outer layer material is wound to form a coalescing layer. The outer layer material is wound on the outside of the inner layer. The cross-sections of the inner layer and the outer layer are both ring-shaped. In the present embodiment, the coalescing filter element is specifically a high-efficiency liquid-liquid coalescing filter element of Hangzhou Kebet Filtration Equipment Co., Ltd., with a brand name of PH-FPF. The diameter of the coalescing filter element is 68 mm, the length is 125 mm, and the average precision of the coalescing filter element is 5 μm. The theoretical use flow rate of a single coalescing filter element is less than or equal to 1.5 m 3 / h, for example, less than or equal to 0.5m 3 / h (i.e. about 8.33L / min).

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

[0121] The separated water phase is returned to the rare earth extraction separation tank of the stripping section through the separated water phase recycling unit 50 for stripping. The separated water phase recycling unit 50 includes a second centrifugal pump 51, a second electric regulating valve 52, and a second flowmeter 53. The second centrifugal pump 51 is used to pump the water phase separated by the horizontal coalescing separator 21 into the rare earth extraction separation tank for stripping (i.e., entering the stripping section), for example, it can be the Nm-th level rare earth extraction separation tank. The second centrifugal pump 51 can be a magnetically driven centrifugal pump. The second flowmeter 53 is arranged on the pipeline between the second centrifugal pump 51 and the rare earth extraction separation tank of the stripping section, and is used to measure the flow rate of the separated water phase pumped into the rare earth extraction separation tank of the stripping section. The second flowmeter 53 is an electromagnetic flowmeter. The second electric regulating 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 water phase pumped into the rare earth extraction separation tank of the stripping section.

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

[0123] The separated blank organic phase is returned to the rare earth extraction separation tank of the extraction section, for example, to the first-stage rare earth extraction separation tank 1, through the separated organic phase recycling unit 60, for extracting rare earth feed liquid. The separated organic phase recycling 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 agglomeration separator 21 to the first-stage rare earth extraction 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 an aqueous organic phase using the aqueous organic phase coalescing and separation system in the rare earth extraction process of embodiment 1, comprising the following steps:

[0126] The first centrifugal pump 12 is used to pump the aqueous blank organic phase (the aqueous blank organic phase contains P204 and kerosene, the volume ratio of P204 and kerosene is 1:2, the water content is 51250ppm, and it is relatively turbid) generated during the extraction process of the rare earth sulfate liquid from the last stage rare earth extraction separation tank N into the pre-filter 11. In the pre-filter 11, a single pre-filter filter element is used. The flow rate is adjusted by the first electric regulating valve 13, and the flow rate of the aqueous blank organic phase pumped into the pre-filter 11 is measured by the first flowmeter 14. The actual use flow rate of the pre-filter 11 is controlled to be 1.5L / min. The solid particles are filtered and removed by the pre-filter 11 to obtain the aqueous blank organic phase after pre-filtration.

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

[0128] Example 3

[0129] The difference between this embodiment and embodiment 2 is that the source of the aqueous blank organic phase is different and the water content is different. In this embodiment, the aqueous blank organic phase is the aqueous blank organic phase produced in the La-Ce-PrNd linkage extraction process, which contains P507 and kerosene, the volume ratio of P507 to kerosene is 1:1, the water content is 19480ppm, and it is relatively turbid.

[0130] The separation was performed using the coalescence separation system of Example 1. The separated aqueous phase was water containing hydrochloric acid, and the concentration of hydrochloric acid was 2.46 mol / L. The separated blank organic phase had a water content of 3563 ppm and was clear and transparent.

[0131] Comparative Example 1

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

[0133] Example 4

[0134] The difference from Example 1 is that in this embodiment, multiple pre-filter cartridges and multiple coalescing cartridges are used in parallel, and the lengths of the pre-filter cartridges and the coalescing cartridges are different, which can increase the processing capacity.

[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 / min. 3 / h (i.e. about 8.33L / min).

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

[0137] Example 5 (scale up)

[0138] This embodiment provides a method for removing water from an aqueous organic phase using the aqueous organic phase coalescing and separation system in the rare earth extraction process of embodiment 4, comprising the following steps:

[0139] The first centrifugal pump 12 is used to pump the aqueous blank organic phase (the aqueous blank organic phase contains P204 and kerosene, the volume ratio of P204 and kerosene is 1:2, the water content is 28654ppm, and it is relatively turbid) generated during the extraction process of the rare earth sulfate liquid from the last stage rare earth extraction separation tank N into the pre-filter 11. The flow rate is adjusted by the first electric regulating valve 13, and the flow rate of the aqueous blank organic phase pumped into the pre-filter 11 is measured by the first flowmeter 14, and the actual use flow rate of the pre-filter 11 is controlled to be 250L / min (the actual use flow rate of a single pre-filter filter element is 10L / min). The solid particles are filtered out by the pre-filter 11 to obtain the aqueous blank organic phase after pre-filtration.

[0140] The pre-filtered aqueous blank organic phase is introduced into the horizontal coalescing separator 21 for coalescing separation, and the actual use flow rate of the horizontal coalescing separator 21 is controlled to be 250L / min (the actual use flow rate of a single coalescing filter element is about 6L / min), to obtain a separated aqueous phase and a separated blank organic phase. The separated aqueous phase passes through the water outlet and is finally discharged from the drain outlet of the sump, and is pumped into the rare earth extraction separation tank of the stripping section through the separated aqueous phase recycling unit 50 for recycling, for example, it can be pumped into the Nm-th rare earth extraction separation tank for stripping. The separated aqueous phase contains hydrochloric acid, and the concentration of hydrochloric acid is 2.14mol / L. The separated blank organic phase is transported to the first-stage rare earth extraction separation tank 1 for recycling through the separated organic phase recycling unit 60. The water content of the separated blank organic phase is 2835ppm, and it is clear and transparent.

[0141] Table 1

[0142]

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

[0144] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be thought of by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A system for coalescing and separating aqueous organic phases in a rare earth extraction process, characterized in that: It includes a pre-filtration unit and a coalescence separation unit; The pre-filtration unit comprises a pre-filter, which is configured to pre-filter the aqueous blank organic phase to remove solid particles, thereby obtaining a pre-filtered aqueous blank organic phase; wherein the aqueous blank organic phase is obtained by hydrochloric acid stripping and pure water washing during the rare earth extraction process; The coalescence separation unit comprises a horizontal coalescence separator; the horizontal coalescence separator comprises a horizontal coalescence separator body and a coalescence filter element; the coalescence filter element is detachably arranged in the horizontal coalescence separator body; The horizontal coalescing 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 coalescing separator body; the water outlet is located at the bottom of the horizontal coalescing separator body and is away from the liquid inlet; the organic phase outlet is located at the top of the horizontal coalescing separator body and is away from the liquid inlet; The horizontal coalescing separator is connected to the pre-filter through the liquid inlet, and is used to receive the pre-filtered aqueous blank organic phase, and separate the water in the pre-filtered aqueous blank organic phase, and the separated blank organic phase is discharged from the organic phase outlet, and the separated aqueous phase is discharged from the water outlet; The outer layer of the coalescing filter element is a polytetrafluoroethylene fiber layer, and the inner layer is a polytetrafluoroethylene fiber layer; the theoretical flow rate of a single coalescing filter element is less than or equal to 1.5m 3 / h.

2. The coalescence separation system according to claim 1, characterized in that: The pre-filter comprises a pre-filter body and a pre-filter element, wherein 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 0.2 to 10 μm, its diameter is 55 to 70 mm, and its length is 250 to 1000 mm; the pre-filter body is made of carbon steel, and a sodium-treated polytetrafluoroethylene plate is used as an inner lining.

3. The coalescence separation system according to claim 1, characterized in that: It also includes a first centrifugal pump, a first electric regulating valve, a first flow meter and a PLC control unit; wherein, The first centrifugal pump is configured to pump the aqueous blank organic phase from the rare earth extraction separation tank into the pre-filter; The first electric regulating valve is disposed on the pipeline between the first centrifugal pump and the pre-filter, and is used to control the flow rate of the aqueous blank organic phase entering the pre-filter; The first flow meter is disposed on the pipeline between the first electric regulating valve and the pre-filter, and is used to measure the flow rate of the aqueous blank organic phase entering the pre-filter; The first centrifugal pump, the first electric regulating valve and the first flow meter are electrically connected to the PLC control unit respectively.

4. The coalescence separation system according to claim 3, characterized in that: The horizontal coalescing separator also includes a liquid collecting tank for collecting the separated water phase; The coalescence separation system further comprises a liquid level meter, which is used to measure the liquid level of the liquid collecting tank; the liquid level meter is electrically connected to the PLC control unit.

5. The coalescence separation system according to claim 4, characterized in that: The horizontal coalescing separator body is made of carbon steel, and its inner wall is sprayed with polytetrafluoroethylene powder; the coalescing filter element is a high-efficiency liquid-liquid coalescing filter element produced by Hangzhou Kebet Filter Equipment Co., Ltd., with a brand name of PH-FPF.

6. The coalescence separation system according to claim 3, characterized in that: It also includes a separated water phase recycling unit, which includes a second centrifugal pump, a second electric regulating valve and a second flow meter; wherein the second centrifugal pump is used to pump the water phase separated by the horizontal coalescing separator into the rare earth extraction separation tank; the second flow meter is arranged on the pipeline between the second centrifugal pump and the rare earth extraction separation tank, and is used to measure the flow rate of the separated water phase pumped into the rare earth extraction separation tank; the second electric regulating 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 separation tank, or the second electric regulating valve is arranged on the pipeline between the horizontal coalescing separator and the second centrifugal pump.

7. The coalescence separation system according to claim 1, characterized in that: It also includes a separated organic phase recycling unit, which includes a third flow meter, and the third flow meter is used to measure the flow of the separated blank organic phase discharged from the organic phase outlet of the horizontal agglomeration separator to the rare earth extraction separation tank.

8. A method for removing water from a water-containing blank organic phase produced during rare earth extraction using the coalescence separation system of claim 1, characterized in that: The following steps are involved: 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; 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.

9. The method according to claim 8, characterized in that 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 to 2; (b) A mixture of P204 and kerosene, wherein the volume ratio of P204 to kerosene is 1:1 to 2.

10. The method according to claim 8, 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 to 1.5 m 3 / h.

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