Electric flocculation equipment for continuously purifying cleaning water for passivating surface of aluminum material

Abstract

The utility model discloses electric flocculation equipment for continuously purifying cleaning water for passivating the surface of an aluminum product, which comprises a raw water storage tank, a mechanical stirrer, a water inlet pump, an electric flocculation tank, a power supply, a polar plate, an overflow tank and a discharge tank, after the treatment is completed, discharging into a discharge tank, and returning the obtained supernatant liquid to a production line for recycling. According to the utility model, the electric flocculation technology is used for long-term continuous treatment, and the electric flocculation tanks are connected in series or in parallel, or a plurality of electric flocculation tanks are connected in series and then are connected in parallel with other electric flocculation tanks, so that the problems of the existing electric flocculation equipment can be solved; in other words, high-concentration metal cations are generated on an anode after electrification electrolysis, an ion concentration gradient is formed between the ion concentration of a solution near an electrode and a body solution, and concentration polarization affects the electrolytic efficiency of a polar plate.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, and in particular to an electrocoagulation device for continuously purifying cleaning water used in passivation treatment of aluminum surfaces. Background Technology

[0002] Because aluminum alloys have good acid resistance, introducing fluoride (F-) into the phosphating solution can promote the growth of the film on the metal surface. The content of F- significantly affects the final film quality. Therefore, in current aluminum phosphating technology, most manufacturers use fluorine-boron phosphating solutions, resulting in a high fluoride ion content in the phosphating solution. Furthermore, a large amount of phosphoric acid is commonly used. During aluminum phosphating, the dissolved aluminum ions are generally around 0.6–1.0 g / m². These dissolved aluminum ions are carried out by the aluminum material and enter the cleaning tank. When the aluminum ions in the cleaning tank accumulate to a certain concentration, they react at a low pH to form aluminum phosphate precipitate. This precipitate easily adheres to the product surface, affecting the surface quality. Measures must be taken to remove the dissolved aluminum ions from the phosphating tank as quickly as possible to reduce the impact of aluminum ions.

[0003] The cleaning water used for phosphating aluminum surfaces contains high levels of phosphorus and fluoride ions, causing serious environmental pollution and making wastewater treatment difficult. Currently, the main methods for treating phosphorus-containing wastewater both domestically and internationally include chemical phosphorus removal, biological phosphorus removal, and combined chemical-biological phosphorus removal. These methods all require significant consumption of reagents / materials and have low treatment efficiency. Therefore, there is a need for a treatment device that consumes less material and is cleaner and more efficient. Utility Model Content

[0004] The main purpose of this invention is to provide an electrocoagulation device for continuously purifying cleaning water used in the passivation treatment of aluminum surfaces.

[0005] The objective of this utility model can be achieved by adopting the following technical solution:

[0006] An electrocoagulation device for continuously purifying cleaning water used in passivation treatment of aluminum surfaces includes a raw water storage tank, a mechanical stirrer, an inlet pump, an electrocoagulation tank, a power supply, electrode plates, an overflow tank, and a discharge tank.

[0007] Preferably, the electrocoagulation tank is connected to the raw water storage tank and the discharge tank respectively via pipelines.

[0008] Preferably, the number of electrocoagulation tanks provided between the raw water storage tank and the discharge tank is 1 to 20, and the electrocoagulation tanks are connected in series, in parallel, or by connecting multiple electrocoagulation tanks in series and then connecting them in parallel with other electrocoagulation tanks.

[0009] Preferably, the inlet pump is installed on the pipeline connecting the electrocoagulation tank and the raw water storage tank.

[0010] Preferably, the electrocoagulation tank is provided with the electrode plate, which is divided into an anode plate and a cathode plate. The anode plate is connected to the positive terminal of the power supply, and the cathode plate is connected to the positive terminal of the power supply. The raw water storage tank is provided with the mechanical agitator, which includes a drive motor and a stirring frame.

[0011] Preferably, the electrode plates in the electrocoagulation tank are composed of multiple sets of anode and cathode plates connected in parallel, and the anode and cathode plates are adjacent to each other in pairs.

[0012] Preferably, the distance between adjacent anode plates and cathode plates in the electrocoagulation tank is 2 to 40 cm.

[0013] Preferably, an overflow trough is provided above the electrocoagulation tank, and the height of the overflow trough is 1 / 10 to 1 / 4 of the height of the main body of the electrocoagulation tank.

[0014] In electrocoagulation, the coagulant is generated in situ via electrolytic oxidation of Fe or Al electrodes, serving as the anode material and continuously producing ions within the system. The released ions neutralize the charge of the particles, thus initiating coagulation. These ions can then be removed through chemical reactions and precipitation, or by aggregating colloidal materials, followed by electrolytic flotation to remove unwanted pollutants (metal hydroxides and metal phosphate flocs generated in wastewater).

[0015] During electrolysis, phosphates and aluminum in the washing water can be removed through three main mechanisms:

[0016] (1) Chemical precipitation: forming insoluble compounds, such as Al(OH)3, Fe(OH)2, Fe(OH)3, AlPO4, FePO4.

[0017] (2) Coprecipitated compounds are formed, such as AlZn(PO4).

[0018] (3) Adsorption: Soluble phosphate and aluminum ions are electrostatically bonded to the outer surface of insoluble metal hydroxide.

[0019] The primary reactions at the cathode in the electrocoagulation cell are the generation of hydrogen bubbles and the formation of hydroxide ions, while at the anode, aluminum or iron dissolves. These observations highlight the removal mechanisms of aluminum and phosphate ions. Furthermore, the direct reduction of metal cations at the cathode surface, and the formation of precipitated metal hydroxides from OH- ions at the cathode, increase the pH near the cathode surface, promoting the precipitation of aluminum and phosphate ions.

[0020] The beneficial effects of this technology are:

[0021] Using electrocoagulation technology for long-term continuous processing, with electrocoagulation tanks connected in series, parallel, or a series connection followed by parallel connection of other electrocoagulation tanks, can solve the problems existing in current electrocoagulation equipment. Specifically, after electrolysis, a high concentration of metal cations is generated at the anode, creating an ion concentration gradient between the solution near the electrode and the bulk solution. This concentration polarization affects the electrolysis efficiency of the electrode plates. The reason is:

[0022] 1. When the electrocoagulation tanks are connected in series, the flocs in the previous stage settle downwards and flow from the overflow tank to the water treated by the next electrocoagulation tank. The soluble phosphate and aluminum ions are lower, so the next stage of electrocoagulation tank can use a smaller current density for electrolysis to reduce concentration polarization near the electrodes and improve treatment efficiency.

[0023] 2. When the electrocoagulation cells are connected in series, the parallel electrocoagulation cells can allow for a larger water flow. The increased water flow can increase the water velocity between the anode and cathode plates in the electrocoagulation cell, which plays a role in strong stirring. It can also reduce concentration polarization near the electrodes and improve the treatment efficiency.

[0024] 3. The method of connecting multiple electrocoagulation tanks in series and then connecting them in parallel with other electrocoagulation tanks has the advantages mentioned above, which can further improve the treatment efficiency of electrocoagulation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a preferred embodiment of an electrocoagulation device for continuously purifying cleaning water for passivation treatment of aluminum surfaces according to the present invention.

[0026] Figure 2 This is a schematic diagram of an electrocoagulation tank connected in series in an electrocoagulation device for continuously purifying cleaning water for passivation treatment of aluminum surfaces according to this utility model.

[0027] Figure 3 This is a schematic diagram of the electrocoagulation tanks connected in parallel in an electrocoagulation device for continuously purifying cleaning water for passivation treatment of aluminum surfaces according to this utility model.

[0028] Figure 4 This is a schematic diagram of multiple electrocoagulation tanks connected in series and then connected in parallel with other electrocoagulation tanks in an electrocoagulation device for continuously purifying aluminum surface passivation treatment cleaning water according to the present invention.

[0029] The annotations in the attached figures are explained as follows:

[0030] 1. Raw water storage tank; 2. Mechanical agitator; 3. Inlet pump; 4. Electrocoagulation tank; 5. Power supply; 6. Electrode plate; 7. Overflow tank; 8. Discharge tank. Detailed Implementation

[0031] To enable those skilled in the art to understand the technical solution of this utility model more clearly, the present utility model will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of this utility model is not limited thereto.

[0032] Example 1

[0033] like Figure 1 The electrocoagulation device shown is for continuously purifying the cleaning water for passivation treatment of aluminum surfaces, and includes a raw water storage tank 1, a mechanical stirrer 2, an inlet pump 3, an electrocoagulation tank 4, a power supply 5, an electrode plate 6, an overflow tank 7, and a discharge tank 8.

[0034] The electrocoagulation tank 4 is connected to the raw water storage tank 1 and the discharge tank 8 through pipelines respectively. There is one electrocoagulation tank 4 between the raw water storage tank 1 and the discharge tank 8. The pipeline connecting the electrocoagulation tank 4 and the raw water storage tank 1 is equipped with an inlet pump 3.

[0035] Raw water storage tank 1 stores the cleaning water used for passivation treatment of aluminum material surface. The water is pumped into electrocoagulation tank 4 by water inlet pump 3 for purification treatment. The water inlet flow rate is set to 0.5~1m3 / h. After treatment, it is discharged into discharge tank 8. The resulting supernatant can be returned to the production line for reuse or further treatment can be carried out.

[0036] The electrocoagulation tank 4 is made of PP and measures 1500mm×1200mm×1000mm, with an effective volume of approximately 1.3m3. The electrocoagulation tank 4 is equipped with electrode plates 6, which are divided into two anode plates and two cathode plates. Aluminum and iron are used as sacrificial electrodes, serving as the anode and cathode respectively. Both are made of aluminum plates with a purity of 99.53% or iron plates with a purity of 99.50%. The electrode plates 6 measure 1100mm×900mm×10mm and have an effective area of ​​0.85m2.

[0037] The anode plate is connected to the positive terminal of power supply 5, and the cathode plate is also connected to the positive terminal of power supply 5; the electrode gap is 11 mm. Current is applied through DC digital power supply 5, and in this embodiment, the current density applied to the electrode plate 6 is 0.5 A / dm2.

[0038] The raw water storage tank 1 is equipped with a mechanical stirrer 2, which has a stirring speed of 100 rpm.

[0039] After treatment, water from discharge tank 8 was taken and left to stand for more than 30 minutes to measure the total phosphorus content. The total phosphorus content was compared with that in the raw water storage tank 1, and the total phosphorus removal rate was found to be 90.3%.

[0040] Example 2

[0041] like Figure 2As shown, in this embodiment, the electrocoagulation tank 4 consists of three tanks connected in series to form a group of electrocoagulation tanks 4. This group of electrocoagulation tanks 4 is connected to the raw water storage tank 1 and the discharge tank 8 respectively through pipelines. The number of electrocoagulation tanks 4 between the raw water storage tank 1 and the discharge tank 8 is 1. The pipeline connecting the electrocoagulation tank 4 to the raw water storage tank 1 is equipped with an inlet pump 3.

[0042] The remaining components are the same as in Embodiment 1. Using an electrocoagulation device for continuously purifying aluminum surface passivation treatment cleaning water in this embodiment, the cleaning water for aluminum surface passivation treatment in the raw water storage tank 1 is treated. After treatment, water is taken from the discharge tank 8 and allowed to stand for more than 30 minutes to measure the total phosphorus content. The total phosphorus content is compared with that in the raw water storage tank 1, and the total phosphorus removal rate is found to be 96.2%.

[0043] Example 3

[0044] like Figure 3 As shown, in this embodiment, the electrocoagulation tank 4 consists of three tanks connected in parallel to form a group of electrocoagulation tanks 4. This group of electrocoagulation tanks 4 is connected to the raw water storage tank 1 and the discharge tank 8 respectively through pipelines. The number of electrocoagulation tanks 4 set between the raw water storage tank 1 and the discharge tank 8 is 1. The pipeline connecting the electrocoagulation tank 4 to the raw water storage tank 1 is equipped with an inlet pump 3.

[0045] The remaining components are the same as in Embodiment 1. Using an electrocoagulation device for continuously purifying the cleaning water for aluminum surface passivation treatment in this embodiment, the cleaning water for aluminum surface passivation treatment in the raw water storage tank 1 is treated. After treatment, water is taken from the discharge tank 8 and left to stand for more than 30 minutes to measure the total phosphorus content. The total phosphorus content is compared with that in the water in the raw water storage tank 1, and the total phosphorus removal rate is found to be 97.8%.

[0046] Example 4

[0047] like Figure 4 As shown, in this embodiment, three tanks are first connected in series to form a group of electrocoagulation tanks 4. Then, the three groups of connected electrocoagulation tanks are used to form an electrocoagulation tank 4 matrix. The electrocoagulation tank 4 matrix is ​​connected to the raw water storage tank 1 and the discharge tank 8 through pipelines. The number of electrocoagulation tanks 4 between the raw water storage tank 1 and the discharge tank 8 is 1. The pipeline connecting the electrocoagulation tank 4 and the raw water storage tank 1 is equipped with an inlet pump 3.

[0048] The remaining components are the same as in Embodiment 1. An electrocoagulation device for continuously purifying aluminum surface passivation treatment cleaning water, as described in this embodiment, is used to treat the aluminum surface passivation treatment cleaning water in the raw water storage tank 1. After treatment, water is taken from the discharge tank 8 and allowed to stand for at least 30 minutes to measure the total phosphorus content. The total phosphorus content is compared with that in the raw water storage tank 1, and the total phosphorus removal rate is found to be 99.7%.

[0049] In some embodiments of this utility model, if multiple electrocoagulation tanks 4 are connected in series or in parallel due to the large volume of water to be treated, the following advantages can be achieved: the flocculants are dispersed into each electrocoagulation tank 4, reducing the accumulation of excessive flocculants in one electrocoagulation tank 4, and facilitating slag discharge.

[0050] The above are merely further embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope disclosed by this utility model, based on the technical solution and concept of this utility model, shall fall within the protection scope of this utility model.

Claims

1. An electrocoagulation device for continuously purifying cleaning water used in passivation treatment of aluminum surfaces, characterized in that: The system includes a raw water storage tank (1), a mechanical stirrer (2), an inlet pump (3), an electrocoagulation tank (4), a power supply (5), an electrode plate (6), an overflow tank (7), and a discharge tank (8). The electrocoagulation tank (4) is connected to the raw water storage tank (1) and the discharge tank (8) respectively through pipelines. The number of electrocoagulation tanks (4) between the raw water storage tank (1) and the discharge tank (8) is 1 to 20. The electrocoagulation tanks (4) are connected in series, in parallel, or by connecting multiple electrocoagulation tanks (4) in series and then connecting them in parallel with other electrocoagulation tanks (4). The inlet pump (3) is installed on the pipeline connecting the tank (4) and the raw water storage tank (1). The electrode plate (6) is provided inside the electrocoagulation tank (4). The electrode plate (6) is divided into an anode plate and a cathode plate. The anode plate is connected to the positive terminal of the power supply (5), and the cathode plate is connected to the positive terminal of the power supply (5). The mechanical stirrer (2) is provided inside the raw water storage tank (1). The mechanical stirrer (2) includes a drive motor and a stirring frame. The electrode plate (6) in the electrocoagulation tank (4) is composed of multiple sets of anode and cathode plates connected in parallel. The anode and cathode plates are adjacent to each other in pairs.

2. The electrocoagulation equipment for continuously purifying cleaning water for passivation treatment of aluminum surfaces according to claim 1, characterized in that: The distance between adjacent anode plates and cathode plates in the electrocoagulation tank (4) is 2 to 40 cm.

3. The electrocoagulation equipment for continuously purifying cleaning water for passivation treatment of aluminum surfaces according to claim 1, characterized in that: An overflow trough (7) is provided above the electrocoagulation tank (4), and the height of the overflow trough (7) is 1 / 10 to 1 / 4 of the height of the main body of the electrocoagulation tank (4).

Images