A device for deep removal of sodium ions from a tungstate solution and a method of using the same

Abstract

The application belongs to the field of high-purity material preparation and specifically relates to a device and method for deep removal of sodium ions in a tungstate solution, wherein the removal device comprises a sodium ion removal membrane group, graphite plates, a direct current power supply, a peristaltic pump, a raw material pool, a purification pool, a cleaning pool and pipelines. The sodium ion removal membrane group is composed of alternately stacked Nasicon membranes and conductive membranes, water distribution plates are arranged between the Nasicon membranes and the conductive membranes, the two ends of the membrane group are connected with the graphite plates, and water distribution plates are arranged between the membrane group and the graphite plates, wherein the water distribution plates are alternately arranged in positive and negative directions. By adjusting the flow rate of the peristaltic pump and the voltage of the direct current power supply, the tungstate and the cleaning liquid can be sequentially introduced into the sodium ion removal membrane group through the pipelines and the graphite plates under the cooperation of the electric field at a certain flow rate, the sodium ions in the tungstate can be migrated into the cleaning liquid through the channels on the Nasicon membranes under the driving of the electric field, the deep removal of the sodium ions is realized, the tungstate with a sodium ion content lower than 0.1 ppm is obtained, the device is simple to operate, low in energy consumption, free of secondary pollution and reusable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-purity material preparation, and particularly relates to a device for deep removal of sodium ions in a tungstate solution and a use method thereof. BACKGROUND

[0002] Tungsten, as a strategic metal with extremely high melting point (3410 ℃) and boiling point (5700 ℃), is widely used in aerospace, military, medicine and other fields due to its high strength, high hardness and corrosion resistance. The impurity content in tungsten directly affects the performance of tungsten products. When the purity of tungsten reaches 99.999% or above, it has excellent properties such as high resistance, high temperature stability and formation of stable silicides, and is widely used as gate electrode material, wiring material and shielding metal material for semiconductor large-scale integrated circuits. With the rapid development of science and technology and semiconductors, many industries have put forward more stringent requirements for the purity of tungsten. The performance of conventional tungsten products cannot meet the needs of the semiconductor industry. Therefore, it is of great practical significance to develop preparation technology of ultra-high purity tungsten raw materials.

[0003] At present, among the many impurities in tungsten, it is difficult to selectively remove sodium ions from tungstate due to the similar chemical properties of sodium ions and ammonium ions, and the high content of ammonium ions in tungstate. The traditional methods for removing sodium ions from tungstate mainly include extraction, ion exchange, chemical precipitation and electrodialysis. Although these methods can remove sodium ions from tungstate, they have the disadvantages of complicated process, low efficiency, low impurity removal rate, non-reusable and the like, which are greatly limited in practical application. SUMMARY

[0004] The present application aims to overcome the problems in the prior art and provide a device for deep removal of sodium ions in a tungstate solution and a use method thereof. The removal device has novel structure, reasonable design, convenient operation, improved sodium ion removal efficiency, low energy consumption, no secondary pollution, reusability and strong practicality.

[0005] The technical scheme of the present application is as follows: a device for deep removal of sodium ions in a tungstate solution, comprising a sodium ion removal membrane group, a graphite plate, a direct current power supply, a peristaltic pump, a raw material pool, a purification pool, a cleaning pool and pipelines; the graphite plate comprises a water inlet end graphite plate and a water outlet end graphite plate; the sodium ion removal membrane group is composed of Nasicon membranes and conductive membranes which are alternately stacked, and the two ends of the sodium ion removal membrane group are connected with the water inlet end graphite plate and the water outlet end graphite plate respectively; the water inlet end graphite plate and the water outlet end graphite plate are connected with the wires on the positive and negative electrodes of the direct current power supply respectively; there are water distribution plates between the Nasicon membranes and the conductive membranes and between the sodium ion removal membrane group and the graphite plate, and the water distribution plates are arranged in a positive-negative alternating manner.

[0006] The water inlet end graphite plate is provided with a water inlet I and a water inlet II, the water inlet I is connected with the raw material pool through a pipeline and a peristaltic pump, and the water inlet II is connected with the cleaning pool through a pipeline; the water outlet end graphite plate is provided with a water outlet I and a water outlet II, the water outlet I is connected with the raw material pool through a pipeline, and the water inlet II is connected with the cleaning pool through a pipeline.

[0007] Preferably, the thickness of the graphite plate is 5-30 mm, and the size is 1.1-1.5 times the size of the sodium ion removal membrane group; the outer diameter sizes of the Nasicon membrane, the conductive membrane and the water distribution plate are the same, and the four corners are provided with through holes with the same hole diameter as the water inlet and outlet hole diameters of the graphite plate.

[0008] Preferably, the thickness of the Nasicon membrane is 0.2-1.0 mm, the Nasicon membrane is composed of a Nasicon material, a binder and a dispersant, and the Nasicon material is uniformly distributed on the Nasicon membrane.

[0009] Preferably, the general formula of the Nasicon material is AM2(PO4)3, wherein A is one of Li + , Na + , K + , Cs + , NH4 + , Ag + ; M is one of Zr 4+ , Ti 4+ , Mn 4+ , Sn 4+ , Ge 4+ , Hf 4+ , the Nasicon material is in powder form, and the particle size is less than 1 µm.

[0010] Preferably, the conductive membrane is a graphite fiber membrane, a carbon fiber membrane or a carbon membrane.

[0011] Preferably, the water distribution plate includes upper and lower clamping pieces and a nylon net fixed between the clamping pieces, the clamping pieces are provided with a square hole at the center, the square hole is in communication with a group of diagonal through holes provided on the water distribution plate; the thickness of the clamping piece is 0.05-0.5 mm, the thickness of the nylon net is 0.02-0.2 mm; the clamping piece is a silica gel piece, a tetrafluoroethylene piece or a polyester piece.

[0012] Preferably, the outer side of the graphite plate is fixed with the sodium ion removal membrane group through a stainless steel plate and a bolt.

[0013] The application discloses a method for using a device for deeply removing sodium ions in a tungstate solution, and the method comprises the following steps: preparing a tungstate solution with a concentration of 40-300 g / L by using industrial-grade ammonium paratungstate as raw material, placing the tungstate solution in a raw material pool, placing deionized water in a cleaning pool, setting the flow rate of a peristaltic pump to be 1-20 ml / min, setting the voltage of a direct current power supply to be 8-50 V, and sequentially passing the tungstate solution in the raw material pool and the deionized water in the cleaning pool into a sodium ion removal membrane group through a connecting pipeline and a graphite plate respectively; under the driving of an electric field, the sodium ions in the tungstate solution migrate into the deionized water through channels on the Nasicon membrane, and when the content of the sodium ions in the tungstate solution treated by the removal device does not reach the standard, the peristaltic pump switch is turned on, the tungstate solution in the purification pool is transported to the raw material pool, the sodium ion removal is realized in a cycle, and the content of the sodium ions is less than 0.1 ppm.

[0014] The application has the following beneficial effects: the application provides a device and a method for deeply removing sodium ions in a tungstate solution. The sodium ion removal membrane group is assembled by alternately stacking Nasicon membranes and conductive membranes layer by layer, the sodium ion removal rate is significantly improved under the premise that the Nasicon membrane has the function of selectively permeating sodium ions, and the sodium ion removal rate is significantly improved in combination with the synergistic effect of an electric field. By adjusting the flow rate of the peristaltic pump, the applied voltage and the number of chambers and other conditions, the sodium ion removal rule can be effectively explored, and the sodium ions in the tungstate solution can be deeply removed, thereby laying a foundation for the preparation of 5 N or 6 N high-purity tungsten products. The whole device is simple to operate, low in energy consumption, free of secondary pollution and reusable. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 Fig. 1 is a structural schematic diagram of the device of the application;

[0016] Fig. 2 Fig. 2 is a sectional structural schematic diagram of the sodium ion removal membrane group;

[0017] Fig. 3 Fig. 3 is a structural schematic diagram of the water distribution plate, wherein the left drawing is the front view, and the right drawing is the back view;

[0018] In the drawings: 1 is the sodium ion removal membrane group, 2 is the direct current power supply, 3 is the peristaltic pump, 4 is the raw material pool, 5 is the purification pool, 6 is the cleaning pool, 7 is the water inlet end graphite plate, 8 is the water outlet end graphite plate, 9 is the Nasicon membrane, 10 is the conductive membrane, 11 is the water distribution plate, 12 is the through hole, 13 is the clamping piece, and 14 is the nylon net. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: A device for deep removal of sodium ions from tungstate solutions, such as... Figs. 1-3 As shown, the system includes a sodium ion removal membrane assembly 1, graphite plates, a DC power supply 2, a peristaltic pump 3, a raw material tank 4, a purification tank 5, a washing tank 6, and pipelines. The graphite plates include an inlet graphite plate 7 and an outlet graphite plate 8. The sodium ion removal membrane assembly 1 is composed of alternating stacks of Nasicon membranes 9 and conductive membranes 10. Both ends of the sodium ion removal membrane assembly 1 are connected to the inlet graphite plate 7 and the outlet graphite plate 8, respectively. The inlet graphite plate 7 and the outlet graphite plate 8 are connected to the positive and negative wires of the DC power supply 2, respectively. The Nasicon membrane 9 and the conductive membrane 10... Water distribution plates 11 are located between the sodium ion removal membrane group 1 and the graphite plate. These plates are arranged in an alternating pattern, serving not only to allow the solution to flow but also to effectively block the transport of other solutions. The graphite plate 7 at the inlet end has inlet I and inlet II. Inlet I is connected to the raw material tank 4 via a pipe and a peristaltic pump 3, while inlet II is connected to the cleaning tank 6 via a pipe. The graphite plate 8 at the outlet end has outlet I and outlet II. Outlet I is connected to the raw material tank 4 via a pipe, while inlet II is connected to the cleaning tank 6 via a pipe. The graphite plate thickness is 5-30 mm, and its size is 1.1-1.5 times the size of the sodium ion removal membrane group 1. The outer diameters of the Nasicon membrane 9, conductive membrane 10, and water distribution plates 11 are the same, and each of the four corners has through holes 12 with the same diameter as the inlet and outlet holes of the graphite plate. The Nasicon membrane has a thickness of 0.2~1.0 mm and is composed of Nasicon material, a binder, and a dispersant. The Nasicon material is uniformly distributed on the Nasicon membrane. The general formula of the Nasicon material is AM2(PO4)3, where A is Li. + Na + K + Cs + NH4 + Ag + One of them; M is Zr 4 + Ti 4+ Mn 4+ Sn 4+ 、Ge 4+ Hf 4+One of the Nasicon materials is in powder form and has a particle size of less than 1 µm. The conductive film is a carbon film. The water distribution plate 11 comprises upper and lower clamping pieces 13 and a nylon mesh 14 fixed between the clamping pieces, the clamping pieces are provided with a square hole in the center, the square hole is communicated with a group of diagonal through holes provided on the water distribution plate; the thickness of the clamping piece 13 is 0.05-0.5 mm, and the thickness of the nylon mesh 14 is 0.02-0.2 mm; the clamping piece 13 is a silica gel piece, a Teflon piece or a polyester piece. The outer side of the graphite plate is fixed with the sodium ion removal film group through a stainless steel plate and a bolt.

[0021] The sodium ion removal device is built as follows: first, the Nasicon film and the conductive film are alternately and symmetrically stacked on the graphite plate to form a sodium ion removal film group, wherein the water distribution plate is placed between the films. Second, the film group is connected to the graphite plate at both ends, and the water distribution plate is placed between the film group and the graphite plate, and all the water distribution plates in the device are placed in an alternating manner. Subsequently, the two ends of the graphite plate are pressed tightly with a stainless steel plate, and are fixed with a bolt. The water distribution plate and the Nasicon film form a concentrated chamber, and the water distribution plate and the conductive film form a dilute chamber, and the solution does not flow between the two chambers. Third, the connecting pipeline is placed in the solution pool, the purification pool and the cleaning pool respectively, and is connected with the peristaltic pump, and then is connected with the water inlet and outlet of the graphite plate in the sodium ion removal film group, so as to ensure the flow of the solution in the whole device. Finally, the wires on the positive and negative electrodes of the direct current power supply are connected with the holes on the graphite plate in the sodium ion removal film group, and the whole device is built.

[0022] A method for using a device for deeply removing sodium ions in a tungstate solution, comprising the following steps: using industrial-grade ammonium paratungstate as raw material to prepare a tungstate solution with a concentration of 40-300 g / L, placing the tungstate solution in a raw material pool, placing deionized water in a cleaning pool, setting the flow rate of the peristaltic pump to 1-20 ml / min, setting the voltage of the direct current power supply to 8-50 V, and making the tungstate solution in the raw material pool and the deionized water in the cleaning pool pass through the connecting pipeline and the graphite plate into the sodium ion removal film group in sequence; under the driving of the electric field, the sodium ions in the tungstate solution migrate to the deionized water through the channels on the Nasicon film; when the sodium ion content in the tungstate solution treated by the removal device does not meet the standard, the peristaltic pump switch is turned on, the tungstate solution in the purification pool is transported to the raw material pool, the sodium ion is removed in a cycle, and the sodium ion content is less than 0.1 ppm.

[0023] The method for removing sodium ions from the specific tungstate is as follows: 2 L of tungstate with a concentration of 40 g / L and 2 L of deionized water are placed in the solution pool and the cleaning pool. Then, the direct current power supply and the peristaltic pump are turned on, the voltage is set to 12 V, and the solution flow rate is set to 3 ml / min. At this time, the tungstate raw material solution and the deionized water flow through the water distribution plate at a flow rate of 3 ml / min through the water inlet of the graphite plate. Since there are only two diagonal holes on the water distribution plate that are in communication with the nylon net, when the tungstate flows through the holes in communication with the nylon net, it will flow to the surface of the nylon net and cover the entire concentration chamber, and the tungstate will be in full contact with the NaZr2(PO4)3 membrane. At this time, the sodium ions in the tungstate migrate through the channels on the NaZr2(PO4)3, achieving the removal of sodium ions. At the same time, the remaining two holes on the water distribution plate cannot transport the solution because they are not in communication with the nylon net, so the deionized water can only flow to the next chamber (the dilute chamber). Since the water distribution plate in this chamber (the dilute chamber) is placed in the opposite direction of the upper layer, the deionized water can flow through the water distribution plate in this cycle, while the tungstate cannot. In this way, the sodium ions in the tungstate migrate into the deionized water, achieving the selective and deep removal of sodium ions from the tungstate. Since the volume of each chamber is fixed, when the volume of the solution is greater than the volume of the chamber, the tungstate and the deionized water will flow out through the two water outlets of the graphite plate and enter the purification pool and the cleaning pool, respectively. By testing the sodium ion content in the tungstate in the solution pool, it is found that the sodium ion content is 0.32 ppm, which is higher than 0.1 ppm. Then the switch of the peristaltic pump connecting the purification pool and the raw material pool is turned on, and the flow rate of the peristaltic pump is set to 3 ml / min. At this time, the tungstate solution in the purification pool will be transported to the raw material pool and the device in turn, achieving the removal of sodium ions from the tungstate again. After two cycles of detection, the sodium ion content in the tungstate is 0.085 ppm, which meets the sodium ion content standard of 5 N or 6 N high-purity tungsten.

[0024] Example 2: Compared with example 1, the difference between example 2 and example 1 is the method for removing sodium ions from the tungstate.

[0025] The method for removing sodium ions from the specific tungstate is as follows: 2 L of tungstate with a concentration of 40 g / L and 2 L of deionized water are placed in the solution pool and the cleaning pool. Then, the direct current power supply and the peristaltic pump are turned on, the voltage is set to 48 V, and the solution flow rate is set to 3 ml / min. At this time, the tungstate raw solution and the deionized water flow through the water distribution plate at a flow rate of 3 ml / min through the water inlet of the graphite plate. Since there are only two diagonal holes on the water distribution plate that are in communication with the nylon net, when the tungstate flows through the holes in communication with the nylon net, it will flow to the surface of the nylon net and cover the entire concentration chamber, and the tungstate will fully contact the NaZr2(PO4)3 membrane. At this time, the sodium ions in the tungstate migrate through the channels on the NaZr2(PO4)3, achieving the removal of sodium ions. At the same time, the remaining two holes on the water distribution plate cannot transport the solution because they are not in communication with the nylon net, so the deionized water can only flow to the next chamber (the dilute chamber). Since the water distribution plate in this chamber (the dilute chamber) is placed in the opposite direction of the upper layer, the deionized water can flow through the water distribution plate in this cycle, while the tungstate cannot. In this way, the sodium ions in the tungstate migrate into the deionized water, achieving the selective and deep removal of sodium ions in the tungstate. Since the volume of each chamber is fixed, when the volume of the solution is greater than the volume of the chamber, the tungstate and the deionized water will flow out through the two water outlets of the graphite plate and enter the purification pool and the cleaning pool, respectively. By testing the sodium ion content in the tungstate in the solution pool, it is found that the sodium ion content is 0.098 ppm, which meets the sodium ion content standard of 5 N or 6 N high-purity tungsten.

[0026] Example 3: The difference between Example 3 and Example 1 is that the Nasicon material is NaTi2(PO4)3.

[0027] The method for removing sodium ions from the specific tungstate is as follows: 2 L of tungstate with a concentration of 40 g / L and 2 L of deionized water are placed in a solution pool and a cleaning pool. Then, a direct current power supply and a peristaltic pump are turned on, and the voltage is set to 12 V and the solution flow rate is set to 3 ml / min. At this time, the tungstate raw material solution and the deionized water flow through the water distribution plate at a flow rate of 3 ml / min through the water inlet of the graphite plate. Since there are only two diagonal holes on the water distribution plate that are in communication with the nylon net, when the tungstate flows through the holes in communication with the nylon net, it will flow to the surface of the nylon net and cover the entire concentration chamber, and the tungstate is in full contact with the NaTi2(PO4)3 film. At this time, the sodium ions in the tungstate migrate through the channels on the NaTi2(PO4)3, achieving the removal of sodium ions. At the same time, the remaining two holes on the water distribution plate cannot transport the solution because they are not in communication with the nylon net, so the deionized water can only flow to the next chamber (the dilute chamber). Since the water distribution plate in this chamber (the dilute chamber) is placed in the opposite direction of the upper layer, the deionized water can flow through the water distribution plate in this cycle, while the tungstate cannot. In this way, the sodium ions in the tungstate migrate into the deionized water, achieving the selective and deep removal of sodium ions in the tungstate. Since the volume of each chamber is fixed, when the volume of the solution is greater than the volume of the chamber, the tungstate and the deionized water will flow out through the two water outlets of the graphite plate and enter the purification pool and the cleaning pool, respectively. By testing the sodium ion content in the tungstate in the solution pool, it is found that the sodium ion content is 0.40 ppm, which is higher than 0.1 ppm. Then, the peristaltic pump switch between the purification pool and the raw material pool is turned on, and the flow rate of the peristaltic pump is set to 3 ml / min. At this time, the tungstate solution in the purification pool will be transported to the raw material pool and the device in turn, achieving the removal of sodium ions in the tungstate again. After two cycles of detection, the sodium ion content in the tungstate is 0.093 ppm, which meets the sodium ion content standard of 5 N or 6 N high-purity tungsten.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the present application. Any modification, equivalent replacement, improvement, etc. made within the scope of the present application should be included in the protection scope of the present application.

Claims

1. A device for deep removal of sodium ions from a tungstate solution, characterized in that: The application relates to a sodium ion removal membrane group, graphite plates, a direct current power supply, a peristaltic pump, a raw material pool, a purification pool, a cleaning pool and pipelines. The water inlet graphite plate is provided with a water inlet I and a water inlet II, the water inlet I is connected with the raw material pool through a pipeline and the peristaltic pump, and the water inlet II is connected with the cleaning pool through a pipeline; the water outlet graphite plate is provided with a water outlet I and a water outlet II, the water outlet I is connected with the raw material pool through a pipeline, and the water inlet II is connected with the cleaning pool through a pipeline.

2. The device for deep removal of sodium ions from a tungstate solution according to claim 1, characterized in that: The graphite plate has a thickness of 5-30 mm and a size of 1.1-1.5 times the size of the sodium ion removal membrane group; the Nasicon membrane, the conductive membrane and the water distribution plate have the same outer diameter size, and the four corners are provided with through holes with the same hole diameter as the water inlet and outlet hole diameters of the graphite plate.

3. The device for deep removal of sodium ions from a tungstate solution according to claim 1, characterized in that: The Nasicon membrane has a thickness of 0.2-1.0 mm, and is composed of a Nasicon material, a binder and a dispersing agent; the Nasicon material is uniformly distributed on the Nasicon membrane.

4. The device for removing sodium ions in depth from a tungstate solution according to claim 3, characterized in that: The Nasicon material has a general formula AM2(PO4)3, wherein A is one of Li + , Na + , K + , Cs + , NH4 + , Ag + ; M is one of Zr 4+ , Ti 4+ , Mn 4+ , Sn 4+ , Ge 4+ , Hf 4+ , and the Nasicon material is in a powder form and has a particle size less than 1 µm.

5. The device for deep removal of sodium ions from a tungstate solution according to claim 1, characterized in that: The conductive membrane is a carbon membrane.

6. The device for deep removal of sodium ions from a tungstate solution according to claim 1, characterized in that: The water distribution plate comprises upper and lower clamping pieces and a nylon net fixed between the clamping pieces, the clamping piece is provided with a square hole in the center, the square hole is communicated with a group of diagonal through holes arranged on the water distribution plate; the clamping piece has a thickness of 0.05-0.5 mm, the nylon net has a thickness of 0.02-0.2 mm; the clamping piece is a silica gel piece, a tetrafluoro piece or a polyester piece.

7. The device for deep removal of sodium ions from a tungstate solution according to claim 1, characterized in that: The outer side of the graphite plate is fixed with the sodium ion removal membrane group through a stainless steel plate and a bolt.

8. The use of a device for the deep removal of sodium ions from a tungstate solution as claimed in claim 1, characterized in that: The application comprises the following steps: An industrial-grade ammonium paratungstate is used as raw material to prepare a tungstate solution with a concentration of 40-300 g / L, the tungstate solution is placed in a raw material pool, deionized water is placed in a cleaning pool, the flow rate of the peristaltic pump is set to 1-20 ml / min, the voltage of the direct current power supply is set to 8-50 V, the tungstate solution in the raw material pool and the deionized water in the cleaning pool enter the sodium ion removal membrane group through the connecting pipelines and the graphite plates in sequence; under the driving of the electric field, the sodium ions in the tungstate solution migrate to the deionized water through the channels on the Nasicon membrane; when the sodium ion content in the tungstate solution treated by the removal device does not meet the requirements, the peristaltic pump switch is turned on, the tungstate solution in the purification pool is transported to the raw material pool, the sodium ion removal is realized in a cycle, and the sodium ion content is lower than 0.1 ppm.

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