Electrodialysis device for resourceful treatment of alkaline aluminum-containing waste liquid and enrichment method thereof

Abstract

The invention discloses an electrodialysis device for resourceful treatment of alkaline aluminum-containing waste liquid and an enrichment method of the electrodialysis device, and relates to an electrodialysis device for treating aluminum-containing waste liquid and a treatment method. The technical problem that an existing electrodialysis method for the alkaline aluminum-containing waste liquid is poor in separation effect is solved. The electrodialysis device comprises an anode and a cathode which are oppositely arranged, and an anode membrane, at least one group of repeated membrane units, a third separation net and a cathode membrane which are sequentially arranged between the cathode and the anode, wherein the repeated membrane unit consists of a second separation net, a bipolar membrane, a first separation net and a cationic membrane which are arranged in sequence. The treatment method comprises the following steps: introducing alkali liquor into the anode chamber and the cathode chamber to serve as anode liquor and cathode liquor respectively, and inputting the alkali liquor or pure water into the recovery chamber to serve as recovery initial liquor; inputting the alkaline aluminum-containing waste liquid to be treated into the stock solution chamber; circulating liquid in each chamber, and starting a direct-current power supply to form a direct-current electric field for enrichment; the concentration of the concentrated alkali liquor can reach 6-10%. The method is used in the field of aluminum-containing waste liquid treatment.

Description

Technical Field

[0001] The invention relates to an electrodialysis device for resource treatment of aluminum-containing waste liquid and an enrichment method thereof, belonging to the technical field of electrochemical separation. Background Art

[0002] When the aluminum alloy extrusion die is repaired, it needs to be hoisted into the alkaline washing tank of saturated sodium hydroxide solution by crane for hot boiling. After the aluminum alloy adhering to the die cavity is completely dissolved, the die is hoisted into the clean water tank for cleaning and then sent to the die repair area. A large amount of alkaline aluminum-containing waste liquid will be generated during the alkaline washing process of the aluminum alloy extrusion die. This waste liquid is mostly discharged and treated by the process of adjusting pH-flocculation precipitation, but this process will cause a large amount of acid consumption, and at the same time cause a waste of alkali and aluminum resources in the waste liquid, and at the same time bring considerable environmental pressure on aluminum.

[0003] In alkaline aluminum-containing waste liquid, aluminum ions exist in the solution in the form of aluminate anions. However, due to the limited selectivity of anion membranes, the separation of hydroxide and aluminate ions is not complete, the product purity is low, etc., which limits the further promotion and popularization of electrodialysis technology in this field. The Chinese patent "A method for separating alkaline liquid in alumina production" with application number CN201410261119.4 discloses a method for separating sodium hydroxide and sodium aluminate using anion membranes and cationic membranes. Since aluminate ions are easily polarized and precipitated, the anion membrane in this method is very likely to have precipitation attached to the surface, thereby affecting the overall separation performance. Summary of the invention

[0004] The present invention aims to solve the technical problem that the existing electrodialysis method for alkaline aluminum-containing waste liquid has poor separation effect, and to provide an electrodialysis device and an enrichment method for resource treatment of alkaline aluminum-containing waste liquid. The present invention uses a bipolar membrane in combination with a cationic membrane. Under the action of an external DC electric field, the bipolar membrane acts as a H + and OH - The ion generator produces OH - ions combine with alkali metal ions to form bases, and on the other hand, H + Neutralize OH in the stock solution - , thereby achieving efficient separation of aluminum ions and alkali liquor in alkaline aluminum-containing waste liquid.

[0005] The electrodialysis device for recycling alkaline aluminum-containing waste liquid of the present invention comprises an anode 1 and a cathode 2 arranged opposite to each other, an anode membrane 3 arranged in sequence between the cathode and the anode, at least one set of repeated membrane units 4, a third separator 5, and a cathode membrane 6;

[0006] The repeating membrane unit 4 is composed of a second separator 4-1, a bipolar membrane 4-2, a first separator 4-3, and a cationic membrane 4-4 arranged in sequence; wherein the positive layer of the bipolar membrane 4-2 faces the direction of the cathode 2, and the negative layer faces the direction of the anode 1;

[0007] A recovery chamber is formed between the anode membrane 3 and the second separator 4-1, between the cathode membrane 6 and the third separator 5, and between the cation membrane 4-4 and the third separator 5;

[0008] The anode chamber is between the anode membrane 3 and the anode 1; the cathode chamber is between the cathode membrane 6 and the cathode 2; the anode chamber and the cathode chamber are connected and conducted;

[0009] The original liquid chamber is between the cationic membrane 4-4 and the first separator 4-3;

[0010] The first separator 4-3, the second separator 4-1 and the third separator 5 are separators which are continuous and dense on all sides, hollow in the middle effective area, and can form a turbulent layer when the solution flows through, and the thickness of the separator body is 0.2mm-1mm;

[0011] Furthermore, the number of the repeated membrane units is 1 to 200 groups.

[0012] Furthermore, the anode chamber and the cathode chamber are connected in series or in parallel.

[0013] The method for using the electrodialysis device for resource treatment of alkaline aluminum-containing waste liquid of the present invention is carried out according to the following steps:

[0014] 1. Alkali solution with a mass percentage concentration of 1% to 4% is prepared and placed in a cathode liquid tank, which is connected to the anode chamber and cathode chamber of the electrodialysis device through a first pump; the effluent from the anode chamber and cathode chamber is returned to the cathode liquid tank through a water pipe, and the alkaline solution is introduced into the anode chamber and cathode chamber as the anode liquid and cathode liquid respectively;

[0015] 2. Alkali solution or pure water with a mass percentage concentration of 0.1% to 2% is placed in a recovery liquid tank, the recovery liquid tank is connected to the recovery chamber of the electrodialysis device through a second pump, the water outlet of the recovery chamber is returned to the recovery liquid tank through a water pipe, and the alkaline solution or pure water with a mass percentage concentration of 0.1% to 2% is input into the recovery chamber as the recovery initial liquid;

[0016] 3. placing the alkaline aluminum-containing waste liquid to be treated in a stock liquid water tank, which is connected to the stock liquid chamber of the electrodialysis device through a third pump; the water out of the stock liquid chamber is returned to the stock liquid water tank through a water pipe;

[0017] 4. Connect the anode (1) and cathode (2) of the electrodialysis device to a DC power supply; start the first pump, the second pump and the third pump for circulation, and simultaneously turn on the DC power supply to form a DC electric field for enrichment; after the enrichment is completed, the liquid in the raw liquid water tank is the aluminum-containing residual liquid with the alkali removed, and the liquid in the recovery liquid tank is the concentrated alkali liquid with increased concentration, thereby completing the resource recovery treatment of the alkaline aluminum-containing waste liquid.

[0018] Furthermore, the volume ratio of the alkaline aluminum-containing waste liquid to be treated in the raw liquid water tank to the recovered initial liquid in the recovery liquid tank is 1: (1 to 20).

[0019] Furthermore, the operating current density of the electrodialysis device is 10 to 400 A / m 2 , the operating voltage of a single group is 1~2.5V.

[0020] Furthermore, the pH of the alkaline aluminum-containing waste liquid to be treated in step three is ≥13.

[0021] In the present invention, a bipolar membrane is used in combination with a cationic membrane, and the pH of the stock solution is monitored in real time during the process, which can effectively control the precipitation attachment on the surface of the membrane. The bipolar membrane is composed of a cation transport layer and an anion transport layer. Under the action of a DC electric field, H and OH ions can be continuously generated, and migrate to the outside of the membrane from the cation transport layer and the anion transport layer under the action of the electric field. The generated OH radical migrates to the recovery chamber and forms a base with the alkali metal ions migrated from the cation membrane; at the same time, the generated H ions migrate into the stock solution chamber to compensate for the charge loss caused by the migration of alkali metal ions and ensure the electrical neutrality of the stock solution. During the process, the pH of the stock solution is strictly controlled to avoid the formation of aluminum hydroxide precipitation by aluminate ions. The recovery of alkali solution in the waste liquid is achieved as a whole, and the concentration of concentrated alkali solution in the recovery liquid water tank after treatment can reach 6% to 10%.

[0022] The present invention has the following advantages:

[0023] (1) The waste liquid generated by the aluminum industry is highly alkaline, with a concentration of more than 30%. Under this condition, aluminum elements exist in the system in the form of aluminate anions together with hydroxide. In the bipolar membrane, the anode faces the raw liquid chamber and has a high retention rate for aluminate, which will retain the aluminate ions in the original solution. Finally, a high-purity alkaline solution with a mass percentage concentration of 6% to 10% will be obtained in the recovery chamber, which can be returned to the front-end process for reuse, saving the cost of purchasing raw materials and avoiding the waste of a large amount of alkali solution.

[0024] (2) After the alkali solution is removed from the original solution, the end point pH value is maintained at 10-12. At this time, the aluminum ions still exist in the form of aluminate, which prevents precipitation from adhering to the membrane, thereby causing the membrane performance to decay.

[0025] In addition, the aluminum-containing solution after removing the alkali solution can be further refined by adding a small amount of acid solution to adjust the pH to obtain an aluminum hydroxide product.

[0026] The device of the present invention can be used in the field of aluminum-containing waste liquid treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a schematic structural diagram of an electrodialysis device for resource processing of alkaline aluminum-containing waste liquid; in the figure, 1 is anode 1, 2 is cathode, 3 is anode membrane, 4 is a repeating membrane unit, 4-1 is a second separator, 4-2 is a bipolar membrane, 4-3 is a first separator, 4-4 is a cationic membrane, 5 is a third separator, and 6 is a cathode membrane. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] Example 1: The electrodialysis device for recycling alkaline aluminum-containing waste liquid in this example is composed of an anode 1 and a cathode 2 arranged opposite to each other, an anode membrane 3 arranged in sequence between the cathode and the anode, 10 sets of repeated membrane units 4, a third separator 5, and a cathode membrane 6;

[0030] The repeating membrane unit 4 is composed of a second spacer 4-1, a bipolar membrane 4-2, a first spacer 4-3, and a cationic membrane 4-4 arranged in sequence; the positive layer of the bipolar membrane 4-2 faces the direction of the cathode 2, and the negative layer faces the direction of the anode 1;

[0031] A recovery chamber is formed between the anode membrane 3 and the second separator 4-1, between the cathode membrane 6 and the third separator 5, and between the cation membrane 4-4 and the third separator 5;

[0032] The anode chamber is between the anode membrane 3 and the anode 1; the cathode chamber is between the cathode membrane 6 and the cathode 2; the anode chamber and the cathode chamber are connected in series;

[0033] The original liquid chamber is between the cationic membrane 4-4 and the first separator 4-3;

[0034] The first separator 4-3, the second separator 4-1 and the third separator 5 are separators which are continuous and dense on all sides, hollow in the middle effective area, and can form turbulent layers when the solution flows through. The thickness of the separator body is 0.8 mm.

[0035] The method for recycling alkaline aluminum-containing waste liquid using the electrodialysis device of Example 1 is carried out according to the following steps:

[0036] 1. 3L of sodium hydroxide solution with a mass percentage concentration of 4% is placed in the cathode liquid tank, which is connected to the anode chamber and cathode chamber of the electrodialysis device through a first pump; the effluent from the anode chamber and cathode chamber is returned to the cathode liquid tank through a water pipe, and the alkali solution is introduced into the anode chamber and cathode chamber as the anode liquid and cathode liquid respectively;

[0037] 2. Place 5L of 1% sodium hydroxide solution in a recovery liquid tank, which is connected to the recovery chamber of the electrodialysis device via a second pump. The effluent from the recovery chamber is returned to the recovery liquid tank via a water pipe, and the 1% sodium hydroxide solution is input into the recovery chamber as the recovery initial liquid.

[0038] 3. 1L of alkaline aluminum-containing waste liquid to be treated with a pH of 13.5 is placed in a stock liquid water tank, which is connected to the stock liquid chamber of the electrodialysis device through a third pump; the water out of the stock liquid chamber is returned to the stock liquid water tank through a water pipe;

[0039] 4. Connect the anode 1 and cathode 2 of the electrodialysis device to the DC power supply; start the first pump, the second pump and the third pump for circulation, and at the same time turn on the DC power supply to form a DC electric field for enrichment; the operating current density during the enrichment process is 250A / m 2 The partial pressure of a single membrane group is 1.2 / group. The pH of the alkaline aluminum-containing waste liquid is enriched to 11. The DC power supply and the water pump are turned off in turn. The liquid in each water tank is collected, and the enrichment is completed. The liquid in the raw liquid tank is the aluminum-containing residual liquid with the alkali removed. The liquid in the recovery liquid tank is the concentrated alkali liquid with increased concentration. The recovered liquid is clear and transparent, with a mass percentage concentration of 6%, and the resource treatment of the alkaline aluminum-containing waste liquid is completed.

[0040] Example 2: A method for recycling alkaline aluminum-containing waste liquid using the electrodialysis device of Example 1 is carried out according to the following steps:

[0041] 1. Prepare 3L of potassium hydroxide solution with a mass percentage concentration of 4% and place it in the cathode liquid tank, which is connected to the anode chamber and cathode chamber of the electrodialysis device through a first pump; the effluent from the anode chamber and cathode chamber is returned to the cathode liquid tank through a water pipe, and the alkali solution is introduced into the anode chamber and cathode chamber as the anode liquid and cathode liquid respectively;

[0042] 2. Put 2L of potassium hydroxide solution with a mass percentage concentration of 2% in a recovery liquid tank, which is connected to the recovery chamber of the electrodialysis device through a second pump, and the effluent of the recovery chamber is returned to the recovery liquid tank through a water pipe, and the potassium hydroxide solution with a mass percentage concentration of 2% is input into the recovery chamber as the recovery initial liquid;

[0043] 3. 1L of alkaline aluminum-containing waste liquid to be treated with a pH of 13.5 is placed in a stock liquid water tank, which is connected to the stock liquid chamber of the electrodialysis device through a third pump; the water out of the stock liquid chamber is returned to the stock liquid water tank through a water pipe;

[0044] 4. Connect the anode 1 and cathode 2 of the electrodialysis device to the DC power supply; start the first pump, the second pump and the third pump for circulation, and at the same time turn on the DC power supply to form a DC electric field for enrichment; the operating current density during the enrichment process is 200A / m 2 The partial pressure of a single membrane group is 1V / group. The alkaline aluminum-containing waste liquid is enriched until its pH drops to 10. The DC power supply and the water pump are turned off in turn. The liquid in each water tank is collected, and the enrichment is completed. The liquid in the raw liquid tank is the aluminum-containing residual liquid with the alkali removed. The liquid in the recovery liquid tank is the concentrated alkali liquid with increased concentration. The recovered liquid is clear and transparent, with a mass percentage concentration of 10%, and the resource treatment of the alkaline aluminum-containing waste liquid is completed.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An electrodialysis device for recycling alkaline aluminum-containing waste liquid, characterized in that The device comprises an anode (1) and a cathode (2) arranged opposite to each other, an anode membrane (3) arranged in sequence between the cathode and the anode, at least one group of repeated membrane units (4), a third separator (5), and a cathode membrane (6); The repeating membrane unit (4) is composed of a second separator (4-1), a bipolar membrane (4-2), a first separator (4-3), and a cationic membrane (4-4) arranged in sequence; wherein the positive layer of the bipolar membrane (4-2) faces the cathode (2), and the negative layer faces the anode (1); A recovery chamber is formed between the anode membrane (3) and the second separator (4-1), between the cathode membrane (6) and the third separator (5), and between the cation membrane (4-4) and the third separator (5); The anode chamber is between the anode membrane (3) and the anode (1); the cathode chamber is between the cathode membrane (6) and the cathode (2); the anode chamber and the cathode chamber are connected and conducted; A stock solution chamber is located between the cationic membrane (4-4) and the first separator (4-3); The first separator (4-3), the second separator (4-1) and the third separator (5) are separators which are continuous and dense on all sides and hollow in the middle effective area, and can form a turbulent layer when the solution flows through, and the thickness of the separator body is 0.2mm-1mm; 2. The electrodialysis device for recycling alkaline aluminum-containing waste liquid according to claim 1, characterized in that: The number of repeated membrane units is 1 to 200 groups.

3. An electrodialysis device for recycling alkaline aluminum-containing waste liquid according to claim 1 or 2, characterized in that: The anode chamber and the cathode chamber are connected in series or in parallel.

4. A method for recycling alkaline aluminum-containing waste liquid using the electrodialysis device according to claim 1, characterized in that The method proceeds as follows:

1. Alkali solution with a mass percentage concentration of 1% to 4% is prepared and placed in a cathode liquid tank, which is connected to the anode chamber and cathode chamber of the electrodialysis device through a first pump; the effluent from the anode chamber and cathode chamber is returned to the cathode liquid tank through a water pipe, and the alkaline solution is introduced into the anode chamber and cathode chamber as the anode liquid and cathode liquid respectively; 2. Alkali solution or pure water with a mass percentage concentration of 0.1% to 2% is placed in a recovery liquid tank, the recovery liquid tank is connected to the recovery chamber of the electrodialysis device through a second pump, the water outlet of the recovery chamber is returned to the recovery liquid tank through a water pipe, and the alkaline solution or pure water with a mass percentage concentration of 0.1% to 2% is input into the recovery chamber as the recovery initial liquid; 3. placing the alkaline aluminum-containing waste liquid to be treated in a stock liquid water tank, which is connected to the stock liquid chamber of the electrodialysis device through a third pump; the water out of the stock liquid chamber is returned to the stock liquid water tank through a water pipe; 4. Connect the anode (1) and cathode (2) of the electrodialysis device to a DC power supply; start the first pump, the second pump and the third pump for circulation, and simultaneously turn on the DC power supply to form a DC electric field for enrichment; after the enrichment is completed, the liquid in the raw liquid water tank is the aluminum-containing residual liquid with the alkali removed, and the liquid in the recovery liquid tank is the concentrated alkali liquid with increased concentration, thereby completing the resource recovery treatment of the alkaline aluminum-containing waste liquid.

5. The method for recycling alkaline aluminum-containing waste liquid by using the electrodialysis device according to claim 1 according to claim 4, characterized in that The volume ratio of the alkaline aluminum-containing waste liquid to be treated in the raw liquid water tank to the recovered initial liquid in the recovered liquid tank is 1: (1-20).

6. The method for recycling alkaline aluminum-containing waste liquid by using the electrodialysis device according to claim 1 according to claim 4 or 5, characterized in that: The operating current density of the electrodialysis device is 10-400A / m 2 , the operating voltage of a single group is 1~2.5V.

7. The method for recycling alkaline aluminum-containing waste liquid by using the electrodialysis device according to claim 1 according to claim 4 or 5, characterized in that: The pH of the alkaline aluminum-containing waste liquid to be treated in step three is ≥13.

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