Electrodialysis device for concentrating and recycling nitric acid waste liquid in aluminum material surface treatment process

Abstract

The utility model relates to an electrodialysis device for concentrating and recycling nitric acid waste liquid in an aluminum material surface treatment process. The electrodialysis device comprises an electrodialysis membrane stack, a control system, a conductivity / pH meter, an electrode liquid tank, a nitric acid waste liquid tank, a dilute nitric acid tank and a direct-current power supply. The device provided by the utility model overcomes the defects in the traditional method by improving the problem of uniform dispersion of liquid in the net-shaped body part of the chamber frame in the electrodialysis device, can effectively reduce the membrane resistance, prolong the service life of the membrane, improve the equipment efficiency, reduce the production cost and reasonably utilize resources, and is simple to operate and low in cost. The method can better solve the problem of treatment of nitric acid wastewater, and has good environmental benefits and economic benefits.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to an electrodialysis device for concentrating and recovering nitric acid waste liquid during the surface treatment process of aluminum materials. Background Technology

[0002] During electrodialysis, a treatment solution is introduced into the desalination chamber. However, the ions in the treatment solution in the desalination chamber are transferred to the adjacent concentration chamber as electrodialysis progresses. Therefore, the ion concentration of the treatment solution in the desalination chamber gradually decreases, leading to increased impedance. Conversely, the liquid ion concentration in the concentration chamber continuously increases, resulting in decreased resistance. Currently, electrodialysis devices using ion exchange membranes have cation exchange membranes and anion exchange membranes alternately stacked and sandwiched between the anode and cathode electrodes within a chamber frame. The upper and lower ends are fixed by a fastening frame, thus alternately forming concentration and desalination chambers internally. The chamber frame used in such electrodialysis devices typically includes a frame section with a central opening and a mesh structure placed within the open frame section to maintain the spacing between the cation exchange membranes and anion exchange membranes. If the liquid is not uniformly dispersed within the mesh structure, water is prone to electrolysis, making the solution alkaline. Hydroxides such as aluminum hydroxide precipitate and adhere to adjacent ion exchange membranes, leading to increased membrane resistance, reduced membrane life, and other problems.

[0003] Therefore, how to improve the uniform dispersion of liquid in the mesh portion of the chamber frame of an electrodialysis device, and design a device that can effectively reduce membrane resistance, extend membrane life, and achieve high-efficiency electrodialysis, is an urgent problem to be solved. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] The technical problem to be solved by this utility model is to provide an electrodialysis device for concentrating and recovering nitric acid waste liquid in the surface treatment process of aluminum materials, in light of the current state of the technology.

[0006] (II) Technical Solution

[0007] This utility model is achieved through the following technical solution: This utility model proposes an electrodialysis device for concentrating and recovering nitric acid waste liquid during the surface treatment process of aluminum materials, including an electrodialysis membrane stack, a control system, a conductivity / pH meter, an electrode liquid tank, a nitric acid waste liquid tank, a dilute nitric acid tank, and a DC power supply. The anode terminal of the electrodialysis membrane stack is electrically connected to the positive terminal of the DC power supply, and the cathode terminal is electrically connected to the negative terminal of the DC power supply. The sensor probe of the conductivity / pH meter is installed in the pipe of the concentrate outlet of the electrodialysis membrane stack and is electrically connected to the control system, transmitting the data measured by the sensor to the control system.

[0008] Furthermore, the electrode liquid tank is connected to the electrode liquid inlet of the electrodialysis membrane stack via an inlet pipe equipped with an inlet pump three. The inlet pipe is equipped with a valve three and a pressure gauge one. The electrode liquid outlet of the electrodialysis membrane stack is connected to the electrode liquid tank via an outlet pipe.

[0009] Furthermore, the nitric acid waste tank is connected to the desalination chamber inlet of the electrodialysis membrane stack via an inlet pipeline equipped with an inlet pump II, and the inlet pipeline is equipped with valve II and pressure gauge II.

[0010] Furthermore, the dilute nitric acid tank is connected to the inlet of the concentration chamber of the electrodialysis membrane stack via an inlet pipeline equipped with an inlet pump, and the inlet pipeline is equipped with a valve and a pressure gauge.

[0011] Furthermore, the electrodialysis membrane stack includes end cap one, end cap two, cathode plate, anode plate, chamber frame, cation exchange membrane and anion exchange membrane. Between the cathode plate and the anode plate, multiple layers of cation exchange membrane and anion exchange membrane are alternately arranged through the chamber frame, thereby forming an electrodialysis device with a desalination chamber and a concentration chamber.

[0012] Furthermore, the chamber frame includes a porous mesh main body and a frame portion surrounding the porous mesh main body; the porous mesh main body has a porous mesh structure with hemispherical protrusions and hemispherical depressions on its surface, the height of the hemispherical protrusions being 1.1 to 3 times that of the porous mesh main body; the frame portion has an inlet and an outlet for liquid inlet and outlet of the chamber where the chamber frame is located; and opening one and opening two are used to communicate with the corresponding inlet and outlet of the chamber frames of two adjacent chambers; the opening one and opening two at the corresponding positions of the frame portions of multiple chamber frames constitute the internal liquid channels of the electrodialysis membrane stack.

[0013] Furthermore, the cathode plate, anode plate, chamber frame, cation exchange membrane, and anion exchange membrane are disposed between end cap one and end cap two, and are fixed by fastening bolts on end cap one and end cap two.

[0014] Furthermore, the average pore diameter of the porous mesh main body is 0.5-50 mm.

[0015] (III) Beneficial Effects

[0016] Compared with the prior art, this utility model has the following advantages:

[0017] The device provided by this utility model overcomes the shortcomings of traditional methods by improving the uniform dispersion of liquid in the mesh part of the chamber frame in the electrodialysis device. It can effectively reduce membrane resistance, extend membrane service life, improve equipment efficiency, reduce production costs, make reasonable use of resources, and is simple to operate. It can effectively solve the treatment of nitric acid wastewater and has good environmental and economic benefits.

[0018] This invention incorporates hemispherical protrusions and depressions in the porous mesh main body of the chamber frame. These hemispherical protrusions and depressions form the cavities and liquid circulation channels within the desalination and concentration chambers of the electrodialysis membrane stack. When liquid flows through the hemispherical protrusions of the porous mesh main body, it bypasses the protrusions and is distributed into the surrounding pores. This periodic turbulence causes the liquid to continuously split and mix during its flow within the desalination and concentration chambers. The fluid constantly changes its velocity and direction within the pore channels, causing it to propagate further and occupy an increasingly larger flow area. Under sufficient fluid pressure, this allows for a more uniform distribution of the electrolyte, reducing or eliminating local stagnation zones and preventing water electrolysis, hydroxide precipitation, and problems such as increased membrane resistance and decreased equipment efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an electrodialysis device system for concentrating and recovering nitric acid waste liquid during the surface treatment process of aluminum materials, according to an embodiment of this utility model.

[0020] Figure 2 This is a schematic diagram of the structure of the electrodialysis membrane stack in an embodiment of this utility model.

[0021] Figure 3 This is a front view of the chamber frame in the electrodialysis membrane stack in an embodiment of this utility model.

[0022] Figure 4 This is a cross-sectional schematic diagram of the chamber frame in the electrodialysis membrane stack of this utility model embodiment.

[0023] The annotations in the attached figures are explained as follows:

[0024] 1. Electrodialysis membrane stack; 2. Control system; 3. Conductivity / pH meter; 4. Electrode solution tank; 5. Nitric acid waste tank; 6. Dilute nitric acid tank; 7. DC power supply; 8. Fastening bolts; 9. Anode terminal; 10. Cathode terminal; 11. Inlet pump 1; 12. Inlet pump 2; 13. Inlet pump 3; 14. Pressure gauge 1; 15. Pressure gauge 2; 16. Pressure gauge 3; 17. Valve 1; 18. Valve 2; 19. Valve 3; 20. Electrode solution inlet; 21. Desalination chamber inlet; 22. Concentration chamber inlet; 23. Electrode solution outlet; 24. Desalinated solution outlet; 25. Concentrated solution outlet; 26. End cap one; 27. End cap two; 28. Cathode plate; 29. ​​Anode plate; 30. Chamber frame; 31. Cation exchange membrane; 32. Anion exchange membrane; 33. Desalination chamber; 34. Concentration chamber; 35. Cathode chamber; 36. Anode chamber; 37. Frame section; 38. Porous mesh main body section; 39. Liquid inlet; 40. Liquid outlet; 41. Opening one; 42. Opening two; 43. Hemispherical protruding structure; 44. Hemispherical concave structure. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model. Example

[0026] like Figure 1 The electrodialysis device shown is for concentrating and recovering nitric acid waste liquid during the surface treatment of aluminum materials. It includes an electrodialysis membrane stack 1, a control system 2, a conductivity / pH meter 3, an electrode liquid tank 4, a nitric acid waste liquid tank 5, a dilute nitric acid tank 6, and a DC power supply.

[0027] The anode terminal 9 of the electrodialysis membrane stack 1 is electrically connected to the positive terminal of the DC power supply 7, and the cathode terminal 10 is electrically connected to the negative terminal of the DC power supply 7.

[0028] Electrode liquid tank 4 is connected to electrode liquid inlet 20 of electrodialysis membrane stack 1 through an inlet pipeline equipped with inlet pump 3 13. Valve 3 19 and pressure gauge 14 are installed in the inlet pipeline. Electrode liquid outlet 23 of electrodialysis membrane stack 1 is connected to electrode liquid tank 4 through outlet pipeline.

[0029] The nitric acid waste liquid tank 5 is connected to the desalination chamber inlet 21 of the electrodialysis membrane stack 1 through an inlet pipeline equipped with an inlet pump 2 12. The inlet pipeline is equipped with a valve 2 18 and a pressure gauge 2 15.

[0030] The dilute nitric acid tank 6 is connected to the desalination chamber inlet 22 of the electrodialysis membrane stack 1 through an inlet pipeline equipped with an inlet pump 11. The inlet pipeline is equipped with a valve 17 and a pressure gauge 16.

[0031] The sensor probe of the conductivity / pH meter 3 is installed in the pipe of the concentrate outlet 24 of the electrodialysis membrane stack 1 and is electrically connected to the control system 2 to transmit the data measured by the sensor to the control system 2.

[0032] DC power supply 7, inlet pump 11, inlet pump 2 12, inlet pump 3 13, pressure gauge 1 14, pressure gauge 2 15, pressure gauge 3 16, valve 1 17, valve 2 18, valve 3 19 are electrically connected to control system 2 to transmit the data measured by the sensor to the control system.

[0033] like Figure 2 As shown, the electrodialysis membrane stack includes end cap 26, end cap 27, cathode plate 28, anode plate 29, chamber frame 30, cation exchange membrane 31, and anion exchange membrane 32. Between cathode plate 28 and anode plate 29, multiple layers of cation exchange membrane 31 and anion exchange membrane 32 are alternately arranged through chamber frame 30, thereby forming an electrodialysis device with desalination chamber 33 and concentration chamber 34. Cathode plate 28 and its adjacent ion exchange membrane form cathode chamber 35, and anode plate 29 and its adjacent ion exchange membrane form anode chamber 36.

[0034] The cathode plate 28, anode plate 29, chamber frame 30, cation exchange membrane 31 and anion exchange membrane 32 are disposed between end cap 1 26 and end cap 27 and are fixed by fastening bolts 8 on end cap 1 26 and end cap 27.

[0035] like Figure 3 As shown, the chamber frame includes a porous mesh main body 38 and a frame part 37 surrounding the porous mesh main body. The frame part 37 is provided with an inlet 39 and an outlet 40 for liquid inlet and outlet of the chamber where the chamber frame is located. Openings 41 and 42 are used to communicate with the corresponding inlet and outlet on the chamber frames of two adjacent chambers. The openings 41 and 42 at corresponding locations on the frame parts of multiple chamber frames constitute the internal liquid channels of the electrodialysis membrane stack. The flow channels formed by the inlet 39 and outlet 40 inside the electrodialysis membrane stack are not interconnected with the flow channels formed by the openings 41 and 42 inside the electrodialysis membrane stack.

[0036] like Figure 4 As shown, the porous mesh main body 38 has a porous mesh structure with a thickness of 0.63 mm and an average pore diameter of 4 mm. Its surface is provided with a hemispherical protrusion structure 43 and a hemispherical recess structure 44. The height of the hemispherical protrusion structure 43 is 0.95 mm.

[0037] The operation steps of the electrodialysis device for concentrating and recovering nitric acid waste liquid in the aluminum surface treatment process according to this utility model are as follows:

[0038] The 0.01 mol / L sodium sulfate in the electrode liquid tank 4 is sent into the electrode liquid inlet 20 of the electrodialysis membrane stack 1 through the inlet pipeline equipped with the inlet pump 313. It enters the cathode chamber 35 and anode chamber 36 of the electrodialysis membrane stack 1 respectively, and flows out from the electrode liquid outlet 23 of the electrodialysis membrane stack through the internal pipeline of the electrodialysis membrane stack.

[0039] Nitric acid waste liquid containing nitric acid and aluminum ions, generated during the aluminum surface treatment process, is filtered and flows into nitric acid waste liquid tank 5. It is then sent to the desalination chamber inlet 21 of the electrodialysis membrane stack 1 through the inlet pipeline equipped with inlet pump 2 12, enters the desalination chamber 33 of the electrodialysis membrane stack 1, and after being processed by the electrodialysis membrane stack, it flows out from the desalination liquid outlet 24 of the electrodialysis membrane stack through the internal pipeline of the electrodialysis membrane stack.

[0040] At the same time, 0.1 mol / L dilute nitric acid in dilute nitric acid tank 6 is sent to the inlet 22 of the concentration chamber of electrodialysis membrane stack 1 through the inlet pipeline equipped with inlet pump 11, enters the concentration chamber 34 of electrodialysis membrane stack 1, and after being processed by the electrodialysis membrane stack, flows out from the concentrate outlet 25 of the electrodialysis membrane stack through the internal pipeline of the electrodialysis membrane stack.

[0041] The electrodialysis unit is started by controlling the system, and the liquid flow rate in the desalination and concentration chambers is adjusted to 40 L / h, the flow rate in the cathode and anode chambers on both sides is 40 L / h, and the current density is 100 A / m2.

[0042] The nitric acid recovery solution flows out from the concentrate outlet 25 of the electrodialysis membrane stack. After being tested by a conductivity / pH meter, if the concentration of the recovered nitric acid meets the process requirements, it can be supplied to the production line for reuse. If the concentration of the recovered nitric acid is insufficient, it can be returned to the dilute nitric acid tank 6 for further concentration, or passed to the next stage of the electrodialysis membrane stack for further concentration.

[0043] The desalination solution outlet 24 of the electrodialysis membrane stack flows out desalination solution containing aluminum nitrate. If the pH of the desalination solution is low, it can be returned to the nitric acid waste tank 5 for further desalination. If the pH of the desalination solution is high, it indicates that the amount of nitric acid it contains is low, and it can flow into the desalination solution storage tank to recover the aluminum nitrate.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrodialysis device for concentrating and recovering nitric acid waste liquid during the surface treatment of aluminum materials, comprising an electrodialysis membrane stack (1), a control system (2), a conductivity / pH meter (3), an electrode liquid tank (4), a nitric acid waste liquid tank (5), a dilute nitric acid tank (6), and a DC power supply (7), characterized in that: The anode terminal (9) of the electrodialysis membrane stack (1) is electrically connected to the positive terminal of the DC power supply (7), and the cathode terminal (10) is electrically connected to the negative terminal of the DC power supply (7). The sensor probe of the conductivity / pH meter (3) is installed in the pipe of the concentrate outlet (24) of the electrodialysis membrane stack (1) and electrically connected to the control system (2) to transmit the data measured by the sensor to the control system (2).

2. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 1, characterized in that: The electrode liquid tank (4) is connected to the electrode liquid inlet (20) of the electrodialysis membrane stack (1) through an inlet pipeline equipped with an inlet pump three (13). The inlet pipeline is equipped with a valve three (19) and a pressure gauge one (14). The electrode liquid outlet (23) of the electrodialysis membrane stack (1) is connected to the electrode liquid tank (4) through an outlet pipeline.

3. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 1, characterized in that: The nitric acid waste tank (5) is connected to the desalination chamber inlet (21) of the electrodialysis membrane stack (1) through an inlet pipeline equipped with an inlet pump (2) (12). The inlet pipeline is equipped with a valve (2) (18) and a pressure gauge (2) (15).

4. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 1, characterized in that: The dilute nitric acid tank (6) is connected to the concentration chamber inlet (22) of the electrodialysis membrane stack (1) through an inlet pipeline equipped with an inlet pump (11). The inlet pipeline is equipped with a valve (17) and a pressure gauge (16).

5. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 2, characterized in that: The electrodialysis membrane stack includes end cap one (26), end cap two (27), cathode plate (28), anode plate (29), chamber frame (30), cation exchange membrane (31) and anion exchange membrane (32). Between the cathode plate (28) and the anode plate (29), multiple layers of cation exchange membrane (31) and anion exchange membrane (32) are alternately arranged through the chamber frame (30), thereby forming an electrodialysis device with a desalination chamber (33) and a concentration chamber (34).

6. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 5, characterized in that: The chamber frame (30) includes a porous mesh main body (38) and a frame part (37) located around the porous mesh main body (38). The porous mesh main body (38) is a mesh porous structure with a hemispherical protrusion structure (43) and a hemispherical recess structure (44) on its surface. The height of the hemispherical protrusion structure (43) is 1.1 to 3 times that of the porous mesh main body. The frame part (37) is provided with an inlet (39) and an outlet (40) for the inlet and outlet of the chamber in which the chamber frame is located. The opening one (41) and the opening two (42) are used to communicate with the corresponding inlet and outlet on the chamber frame of two adjacent chambers. The opening one (41) and the opening two (42) at the corresponding parts of the frame parts of multiple chamber frames constitute the internal liquid channels of the electrodialysis membrane stack.

7. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 5, characterized in that: The cathode plate (28), anode plate (29), chamber frame (30), cation exchange membrane (31) and anion exchange membrane (32) are disposed between end cap one (26) and end cap two (27) and are fixed by fastening bolts (8) on end cap one (26) and end cap two (27).

8. The electrodialysis device for concentrating and recovering nitric acid waste liquid during aluminum surface treatment according to claim 6, characterized in that: The average pore size of the porous mesh main body (38) is 0.5-50 mm.

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