A method for producing high-purity aluminum chloride

Abstract

The invention discloses a method for producing high-purity aluminum chloride, which uses industrial aluminum hydroxide and 31% industrial synthetic hydrochloric acid as raw materials, and uses low-basicity polyaluminum chloride solution as electrolyte. When the basicity of the static electrolyte reaches the expected value, the low-basicity polyaluminum chloride solution is pumped from the storage tank into the electrolytic cell by a metering pump to start continuous dynamic electrolysis; after the electrolysis equipment discharges the liquid, it is clarified or filtered by a plate-frame filter press to obtain a transparent, colorless or light-colored liquid finished product polyaluminum chloride. The invention overcomes the problem of low basicity of the existing acid-soluble product; overcomes the problem of too high sodium chloride content in the alkali-soluble product; the electrode is not prone to passivation during the electrolysis process, and at the same time solves the problem of increasing the iron content of the product due to the corrosion of the iron negative electrode, causing the product color to turn yellow, increases the conductive area, and can improve the electrolysis efficiency by more than one time.

Description

Technical Field

[0001] The invention belongs to the technical field of coagulant polyaluminium chloride production, and specifically relates to a method for producing high-purity polyaluminium chloride by combining a chemical acid dissolution method and an electrochemical method. Background Art

[0002] With the development of the national economy and the improvement of living standards, people have put forward higher requirements for the quality of drinking water. In order to meet the requirements for improved drinking water quality, in 2020, the state revised the standards for polyaluminium chloride products for drinking water and promulgated the new national "Polyaluminium Chloride Standard for Drinking Water" (GB15892-2020), which has been implemented since August 1, 2021. Compared with the original standard, the new standard has higher requirements for product appearance, iron content, heavy metal content, water insolubles and other indicators, and requires that the production of polyaluminium chloride for drinking water must use aluminium hydroxide as the main raw material.

[0003] At present, the main methods for producing polyaluminium chloride using aluminium hydroxide as raw material are acid dissolution method, alkali dissolution method, electrodialysis method and electrochemical method. All of the above methods can produce polyaluminium chloride products for drinking water that meet the requirements of the new standards, but they are not perfect and have problems:

[0004] 1. Acid dissolution method: The raw materials are aluminum hydroxide and industrial hydrochloric acid, which are added to the reactor in a certain proportion. Under high temperature and high pressure reaction conditions, polyaluminum chloride solution can be produced. However, the basicity index of the product is generally below 40%, which does not meet the standard and the water purification effect of the product is also poor.

[0005] 2. Alkali dissolution method: Aluminum hydroxide is used as raw material, reacted with sodium hydroxide to form sodium aluminate, and citric acid is added at the same time, and then reacted with hydrochloric acid to form polyaluminum chloride. The advantages of this technology are that it reacts at room temperature and the basicity of the product can be adjusted, but the production cost is high, the product is impure, and the product contains a large amount of sodium chloride.

[0006] 3. Electrodialysis: Using aluminum chloride as raw material, the synthesized polyaluminum chloride product has high purity, is technically feasible, and is easy to operate, but the product concentration is low, and the anion exchange membrane is difficult to replace, and the cost is also high, so it cannot be actually produced and used in large quantities.

[0007] 4. Traditional electrolysis: With aluminum chloride solution as electrolyte, aluminum plate as anode, iron plate as cathode, direct current is used for electrolysis in the electrolytic cell. The basicity of the generated product is adjustable and the product is stable. However, there are problems such as severe chemical corrosion of the cathode, iron content in the product, large anode consumption, short life, and the need for regular replacement and difficulty in replacement. There are also problems such as corrosion and consumption of electrodes, thinning of electrodes, increasing spacing, low electrolysis efficiency, and easy short circuit and discontinuous production at the end of consumption. Summary of the invention

[0008] The purpose of the present invention is to provide a method for producing high-purity polyaluminium chloride by using aluminium hydroxide as raw material, acid dissolving chemical reaction and electrochemistry. The method for producing high-purity aluminium chloride of the present invention is to heat industrial aluminium hydroxide and 31% hydrochloric acid to 120-135°C in a mass ratio of 1:3.0-4.5 in an enameled reactor under pressure and for 3-4 hours to generate a transparent polyaluminium chloride solution having an aluminium oxide content of 10-13% and a basicity of 5-40%; then use a low-basicity aluminium chloride solution as an electrolyte; use a titanium mesh plated with a rare metal as a frame and a multi-dimensional electrode filled with aluminium particles with a diameter of 4-20 mm as a cathode; The electrolytic cell is provided with a direct current power supply, the electrolysis voltage is 0.8-15V, and the current density is 50-120A / m2; the cathode and the anode are switched every 1-5 minutes; aluminum particles are added regularly according to consumption, and the production is continuous; the obtained liquid polyaluminum chloride product has the appearance of a colorless or light-colored translucent solution; after clarification or pressure filtration, the obtained product is a colorless and transparent polyaluminum chloride liquid product with a basicity in the range of 50-85% and an alumina content in the range of 10-23%, which is adjustable and controllable.

[0009] The specific scheme of the present invention is: a method for producing high-purity aluminum chloride, comprising the following steps:

[0010] Step 1: using industrial aluminum hydroxide and 31% industrial synthetic hydrochloric acid as raw materials, adding aluminum hydroxide to hydrochloric acid in a mass ratio of 1:3.0-4.5, stirring and heating the reaction, and reacting for 2-3 hours after the reaction pressure reaches 0.3-0.38 MPa and the reaction temperature reaches 130-135° C., to obtain a colorless and transparent polyaluminum chloride solution with an aluminum oxide content of 10-13% and a basicity content of 5-40%, cooling the solution to room temperature, and injecting the solution into a low basicity polyaluminum chloride solution storage tank for standby use;

[0011] Step 2: using a low-basicity polyaluminium chloride solution as an electrolyte, placing it in an electrolysis device, wherein the electrolysis device comprises a DC power supply, an electrolytic cell, cathode and anode multi-dimensional electrodes, a circulation pump, an online precision density meter, an online precision pH meter and an automatic control device; the anode and cathode are filled with aluminium particles, the electrolytic cell circulation pump is turned on, the DC power supply is turned on, the electrolysis parameters are set, and static electrolysis is started;

[0012] Step 3: When the basicity of the static electrolyte reaches the expected value, the low basicity polyaluminium chloride solution is pumped from the storage tank into the electrolytic cell by a metering pump to start continuous dynamic electrolysis; the process parameters of the dynamic electrolysis process are set the same as the static electrolysis process; the product quality is monitored and controlled by the online precision density meter and the online precision pH meter;

[0013] Step 4: Turn on the automatic control system of the electrolysis equipment, give values ​​through the online precision density meter and precision pH meter at the electrolyte outlet, and link with the industrial controller (PLC) to control the pumping flow of the metering pump to achieve automatic control of product quality in the production process;

[0014] Step 5: After the liquid comes out of the electrolysis equipment, it is clarified or filtered in a plate and frame filter press to obtain a transparent, colorless or light-colored liquid finished product polyaluminium chloride.

[0015] Furthermore, the electrolysis equipment also includes an electrocatalytic device, which includes: a box, a feed area, an electrolysis area for loading multiple electrode plates, a discharge area and an overflow area, the feed area, the electrolysis area, the discharge area and the overflow area are all arranged in the box, the feed area, the electrolysis area, the discharge area and the overflow area are connected in sequence, the feed area is located on one side of the box, the overflow area is located on the other side of the box, the electrolysis area and the discharge area are located between the feed area and the overflow area, the electrolysis area is adjacent to the feed area, the discharge area is adjacent to the overflow area, and multiple electrode plates correspond to the multi-dimensional electrode.

[0016] Furthermore, the electrolysis zone includes: the multiple electrode plates, a feed component and a discharge component, the feed component and the discharge component are both vertically installed in the box body, the feed component is installed between the feed zone and the electrolysis zone, the discharge component is installed between the electrolysis zone and the discharge zone, a plurality of electrode plates are vertically installed in the electrolysis zone, and a plurality of electrode plates are located between the feed component and the discharge component.

[0017] Furthermore, a feed pump access flange and a first circulation pump access flange are provided on the top of one side of the box body, the first circulation pump access flange is located below the feed pump access flange, and the feed pump access flange and the first circulation pump access flange are both connected to the feed area, and a discharge pump access flange and a second circulation pump access flange are provided on the other side of the box body, the second circulation pump access flange is located below the discharge pump access flange, the discharge pump access flange and the second circulation pump access flange are both connected to the overflow area, and the first circulation pump access flange is located below the discharge pump access flange.

[0018] Furthermore, an overflow plate is provided between the discharge area and the overflow area, and the overflow plate is vertically installed in the box body, and the box body is made of polypropylene.

[0019] Furthermore, the electrolysis zone also includes: multiple groups of first fixing anchors for fixing the electrode plates, multiple groups of second fixing anchors for fixing the electrode plates, and multiple groups of raised platforms for supporting the electrode plates, multiple groups of first fixing anchors are vertically installed on the feeding component, and there is a gap between two adjacent groups of first fixing anchors, multiple groups of second fixing anchors are vertically installed on the discharging component, and there is a gap between two adjacent groups of second fixing anchors, multiple groups of raised platforms are installed on the bottom of the box, one side of the electrode plate is installed between two adjacent groups of first fixing anchors, and the other side of the electrode plate is installed between two adjacent groups of second fixing anchors, the bottom end of the electrode plate is abutted against the raised platform, and the end faces of the feeding component and the discharging component are covered with through holes.

[0020] Furthermore, the electrolysis process parameters are set to an electrode current density of 50-120A / m2, a voltage of 0.8-15V, and a positive and negative electrode switching frequency of 1-10min / time; the expected value is 60-85%; the aluminum particle diameter is 2-12mm; and the rated flow rate of the electrolytic cell circulation pump is 5-15 times the equipment volume.

[0021] Furthermore, the multidimensional electrode includes: metal particles, a body for loading the metal particles, and a power connection titanium plate for connecting a power source. The body is a hollow structure with an opening on one side, and both ends of the body are mesh structures. The power connection titanium plate is installed on the side wall of the body, and the metal particles are arranged in the body.

[0022] Furthermore, the main body includes: a pair of titanium plate frames, a pair of titanium meshes and three titanium plate side plates, the pair of titanium plate frames are arranged in parallel, a gap is arranged between the pair of titanium plate frames, the three titanium plate side plates are installed one by one on the three side walls of the pair of titanium plate frames, and the pair of titanium meshes are installed one by one on the pair of titanium plate frames.

[0023] Furthermore, the main body also includes: a plurality of titanium columns for supporting the titanium mesh, the two ends of the plurality of titanium columns are connected to the titanium plate frame one by one, and the middle parts of the plurality of titanium columns are cross-connected accordingly.

[0024] Furthermore, the power connection titanium plate is installed on one of the three titanium plate side plates, the metal particles are aluminum particles, the main body is a rectangular structure, and the power connection titanium plate is an "L"-shaped structure.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] 1) It overcomes the problem of low basicity of existing acid-soluble products; it overcomes the problem of excessively high sodium chloride content of alkali-soluble products; all indicators of the finished product fully meet and exceed the requirements of the new national standard "Polyaluminum Chloride Standard for Drinking Water" (GB15892-2020).

[0027] 2) Compared with the existing electrolysis method, the electrolyte uses low-basicity polyaluminium chloride, the anode consumes aluminium particles, the electrolysis process is faster, and the operation is simplified and convenient; at the same time, a dedicated power supply is used to perform positive and negative pole reversal production, the consumption of anode and cathode aluminium particles is uniform, the electrode area and electrode spacing remain stable for a long time, and the electrolysis parameters are stable and reliable;

[0028] 3) Compared with the existing electrolysis method, the electrodes do not need to be replaced regularly, and the production does not need to be interrupted. It is only necessary to replenish the aluminum particles on time according to the consumption of aluminum particles, which can achieve long-term continuous and stable production;

[0029] 4) Compared with the existing electrolysis method, iron plate is not used as cathode, and cathode and anode are multi-dimensional special electrodes of the same specification. Due to the timed reversal of the positive and negative electrodes, the electrodes are not prone to passivation during the electrolysis process. At the same time, the problem of increasing the iron content of the product and causing the product color to turn yellow due to the corrosion of the iron negative electrode is solved;

[0030] 5) Compared with the existing electrolysis method, the consumable material is metal aluminum particles instead of aluminum plates, which increases the conductive area and can increase the electrolysis efficiency by more than double;

[0031] 6) Compared with the existing polyaluminium chloride production method using aluminium hydroxide as raw material, the production process does not produce "waste water", "waste gas" or "waste residue", and the hydrogen produced at the cathode can be recycled and used as new energy.

[0032] 7) The production process is highly replicable, can be scaled up for production, and has a high degree of automation.

[0033] 8) High electrolysis efficiency, minimal passivation, easy replacement and long electrode life. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is one of the structural schematic diagrams of the electrocatalytic device in the present invention;

[0035] Figure 2 This is the second structural schematic diagram of the electrocatalytic device in the present invention;

[0036] Figure 3 This is the third structural schematic diagram of the electrocatalytic device in the present invention;

[0037] Figure 4 This is the fourth structural schematic diagram of the electrocatalytic device in the present invention;

[0038] Figure 5 This is the fifth structural schematic diagram of the electrocatalytic device in the present invention;

[0039] Figure 6 This is the sixth structural schematic diagram of the electrocatalytic device in the present invention;

[0040] Figure 7 This is one of the structural schematic diagrams of the catalytic electrode of the present invention;

[0041] Figure 8 This is the second structural schematic diagram of the catalytic electrode of the present invention;

[0042] Fig. 9 The third structural schematic diagram of the catalytic electrode of the present invention;

[0043] Fig.10 It is a trend chart of the change of the effective content and basicity of the product during the continuous production process of the present invention;

[0044] Fig.11 It is a graph showing the changing trend of voltage and pH during the continuous production process of the present invention;

[0045] Fig.12 It is the effect diagram of coagulation experiment of different products of the present invention;

[0046] Fig.13 It is a three-party product testing report.

[0047] Explanation of the accompanying drawings: 1. Box body; 2. Feed area; 3. Electrode plate; 4. Electrolysis area; 5. Discharge area; 6. Overflow area; 7. Feed component; 8. Discharge component; 9. First fixed anchor; 10. Second fixed anchor; 11. Raised platform; 12. Feed pump access flange; 13. First circulation pump access flange; 14. Discharge pump access flange; 15. Second circulation pump access flange; 16. Overflow plate; 17. Main body; 18. Power connection titanium plate; 19. Titanium plate frame; 20. Titanium mesh; 21. Titanium plate side plate; 22. Titanium column. DETAILED DESCRIPTION

[0048] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Specific implementation case 1

[0050] The method of this embodiment uses aluminum hydroxide as raw material, acid dissolution chemical reaction, and electrochemical combined production of high-purity polyaluminum chloride comprises the following steps:

[0051] Step 1: Using industrial aluminum hydroxide and 31% industrial synthetic hydrochloric acid as raw materials, add aluminum hydroxide to hydrochloric acid in a mass ratio of 1:3.0, stir, heat until the reaction pressure reaches 0.36 MPa and the reaction temperature reaches 135°C, and then react for 3 hours to obtain a colorless and transparent polyaluminum chloride solution with an aluminum oxide content of 12.8% and a basicity of 38.5%, which is poured into a low basicity polyaluminum chloride solution storage tank and cooled to room temperature for use.

[0052] Step 2: dilute the low basicity solution obtained in step 1 with water in a mass ratio of 2:1;

[0053] Step 3: Place the diluted electrolyte in an electrolysis device, which includes a DC power supply, an electrolytic cell, cathode and anode multi-dimensional electrodes, a circulation pump, an online precision density meter, an online precision pH meter, and an automatic control device; fill the anode and cathode with aluminum particles, turn on the electrolytic cell circulation pump, connect the DC power supply, and the hourly flow rate of the circulation pump is 8 times the volume of the electrolysis device. Set the electrolysis parameters and start static electrolysis;

[0054] Step 4: Set the process parameters: current density: 50A / m2, voltage: 5V, positive and negative electrode switching frequency is 3min / time, and start electrolysis;

[0055] Step 5: After the static electrolysis is completed, the electrolyte diluted in step 2 is pumped into the equipment by a metering pump to enter the dynamic continuous electrolysis;

[0056] Step 6: Use the precision density meter and pH meter installed at the outlet of the electrolysis equipment to adjust the inlet flow rate and control the parameters of the finished product;

[0057] Step 7: After the electrolysis equipment discharges the drug, it enters the plate and frame filter press for filtration to obtain the finished polyaluminium chloride solution. The main indicators of the finished product are basicity 72.8% and alumina content 11.6%;

[0058] Specific implementation case 2

[0059] Step 1: Same as step 1 in case 1

[0060] Step 2: dilute the low basicity solution obtained in step 1 with water at a mass ratio of 2:1;

[0061] Step 3: Same as step 3 in case 1;

[0062] Step 4: Set the process parameters: current density: 80A / m2, voltage: 8V, positive and negative electrode switching frequency is 4min / time, and start electrolysis;

[0063] Step 5: Same as step 5 in case 1;

[0064] Step 6: Same as step 6 in case 1;

[0065] Step 7: After the electrolysis equipment discharges the drug, it enters the plate and frame filter press for filtration to obtain the finished polyaluminium chloride solution. The main indicators of the finished product are basicity 76.8% and alumina content 11.96%;

[0066] Specific implementation case three

[0067] Step 1: Same as step 1 in case 1;

[0068] Step 2: Same as step 2 in case 1;

[0069] Step 3: Same as step 3 in case 1;

[0070] Step 4: Set the process parameters: current density: 120A / m2, voltage: 12V, positive and negative electrode switching frequency is 5min / time, and start electrolysis;

[0071] Step 5: Same as step 5 in case 1;

[0072] Step 6: Same as step 6 in case 1;

[0073] Step 7: After the electrolysis equipment discharges the drug, it enters the plate and frame filter press for filtration to obtain the finished polyaluminium chloride solution. The main indicators of the finished product are basicity 84.3%, alumina content 12.85%;

[0074] Specific implementation case 4

[0075] Step 1: Same as step 1 in case 1;

[0076] Step 2: directly placing the electrolyte obtained in step 1 in an electrolysis device without dilution, turning on a circulation pump with an hourly flow rate of 10 times the volume of the device, and starting static electrolysis;

[0077] Step 3: Set the process parameters: current density: 120A / m2, voltage: 15V, positive and negative electrode switching frequency is 5min / time, and start electrolysis;

[0078] Step 4: Same as step 5 in case 1;

[0079] Step 5: Same as step 6 in case 1;

[0080] Step 6: After the electrolysis equipment discharges the drug, it is clarified to obtain the finished polyaluminium chloride solution. The main indicators of the finished product are basicity 80.5% and alumina content 23.37%.

[0081] The electrolysis device in the above embodiment also includes an electrocatalytic device, see Figure 1-6The electrocatalytic device comprises a housing 1, a feed area 2, an electrolysis area 4 for loading a plurality of electrode plates 3, a discharge area 5 and an overflow area 6, wherein the feed area 2, the electrolysis area 4, the discharge area 5 and the overflow area 6 are all arranged in the housing 1, and the feed area 2, the electrolysis area 4, the discharge area 5 and the overflow area 6 are connected in sequence, the housing 1 is a rectangular parallelepiped structure with an open top, the polyaluminium chloride can be high-purity polyaluminium chloride, and the electrocatalytic device can be a multi-dimensional electrocatalytic device, comprising: a base and a feed area, an electrolysis area, a discharge area and an overflow area arranged on the base. The feed area, the electrolysis area, the discharge area and the overflow area are connected in sequence, and the feed area is connected to the overflow area through a circulation pump. The feed area comprises a feed pump and a circulation pump, and the access position of the circulation pump is lower than the horizontal height of the access position of the feed pump. The electrolysis zone includes an electrode plate, a raised platform, a fixed anchor, a feed component, and a discharge component. The electrolysis zone is behind the feed zone. The electrode plate is inserted into the electrolysis zone perpendicular to the horizontal direction and placed on the raised platform. The fixed anchor is fixed on both sides of the electrolysis zone in the horizontal direction to fix the electrode plate. The feed component and the discharge component are on both sides of the electrolysis zone in the horizontal direction. The feed component and the discharge component are covered with small holes with uniform diameters. The discharge zone discharges the material through the discharge component of the electrolysis zone. The overflow zone includes an overflow plate, a discharge pump and a circulation pump. The upper end of the overflow plate is designed with a tooth groove lower than the overall liquid level to facilitate the overflow of the discharge liquid to the overflow zone. The access position of the circulation pump is lower than the horizontal height of the access position of the discharge pump. The device can be used for the research of multiple electrolysis projects. It has multiple electrodes to form multiple groups of positive and negative alternating electrode structures, which greatly improves the electrolysis efficiency and saves production costs. At the same time, the precise feed pump, discharge pump and circulation pump ensure the uniformity of the discharge product.

[0082] The inner wall of the electrolysis area is provided with three fixed anchors at equal intervals at the upper, middle and lower positions to fix the electrode plates. A raised platform is provided at the bottom of the electrolysis area. The access position of the circulation pump is lower than the horizontal height of the access of the inlet (outlet) material pump. The box body is made of high temperature resistant and corrosion-resistant material. The device box body is made of thickened PP (Polypropylene, polypropylene) material. The electrolysis project can be a water treatment agent production project, a domestic sewage treatment project, or an industrial wastewater treatment project.

[0083] The feed pump is connected to the flange for the entry of raw materials, and the circulating pump is connected to the flange for the circulation and mixing of the entire system. The feed area is the pre-reaction area, the fixed anchor is used to fix the electrode, the electrolysis area is the electrolysis action area, the feed (discharge) part is a perforated plate, the purpose is to keep the feed and discharge uniform, the overflow plate allows the finished material to flow out uniformly, and the pad is used to support the bottom of the electrode and facilitate the discharge of bottom impurities. The feed liquid can be aluminum chloride solution or polyaluminum chloride solution.

[0084] The working principle of the electrocatalytic device is as follows: the feed pump is turned on, and after the feed liquid fills the feed area, it is evenly distributed in the electrolysis area through the feed component. Multiple electrode plates form multiple groups of positive and negative alternating electrode structures for electrolysis. The electrode plates are fixed by fixed anchors to prevent deformation. The padding platform raises the plates to prevent the electrolytic particles from directly connecting with the plates to form a short circuit. When the electrolyzed feed liquid fills the discharge area through the discharge component, the feed liquid overflows to the overflow area. At this time, the circulation pump is turned on to ensure that the feed liquid fully reacts and the discharge liquid is uniform. When the liquid level reaches a certain height, the discharge pump is turned on.

[0085] The feed zone 2 is located at one side of the housing 1, the overflow zone 6 is located at the other side of the housing 1, the electrolysis zone 4 and the discharge zone 5 are located between the feed zone 2 and the overflow zone 6, the electrolysis zone 4 is adjacent to the feed zone 2, and the discharge zone 5 is adjacent to the overflow zone 6. The position design facilitates the sequential operation of the process, the pre-reaction, electrolysis, discharge, uniform outflow of finished materials and other processes, and improves the reliability of the electrocatalytic device for manufacturing polyaluminium chloride.

[0086] The electrolysis zone 4 includes: a plurality of electrode plates 3, a feed component 7 and a discharge component 8, the feed component 7 and the discharge component 8 are both vertically installed in the box 1, the feed component 7 is installed between the feed zone 2 and the electrolysis zone 4, the discharge component 8 is installed between the electrolysis zone 4 and the discharge zone 5, a plurality of electrode plates 3 are vertically installed in the electrolysis zone 4, and a plurality of electrode plates 3 are located between the feed component 7 and the discharge component 8. The provision of a plurality of electrode plates enables the electrocatalytic device to simultaneously place a plurality of groups of alternating positive and negative electrodes, thereby improving the electrolysis efficiency and saving production costs. The provision of the feed component and the discharge component enables uniform feeding and discharging, thereby improving the stability and reliability of the electrocatalytic device.

[0087] The electrolysis zone 4 also includes: multiple groups of first fixing anchors 9 for fixing the electrode plate 3, multiple groups of second fixing anchors 10 for fixing the electrode plate 3, and multiple groups of raised platforms 11 for supporting the electrode plate 3. The multiple groups of first fixing anchors 9 are vertically installed on the feeding component 7, and there is a gap between two adjacent groups of first fixing anchors 9. The multiple groups of second fixing anchors 10 are vertically installed on the discharging component 8, and there is a gap between two adjacent groups of second fixing anchors 10. The multiple groups of raised platforms 11 are installed at the bottom of the box body 1, one side of the electrode plate 3 is installed between two adjacent groups of first fixing anchors 9, and the other side of the electrode plate 3 is installed between two adjacent groups of second fixing anchors 10. The bottom end of the electrode plate 3 is in contact with the raised platform 11.

[0088] The electrode plate is inserted into the electrolysis zone vertically in the horizontal direction and placed on the raised platform. The fixed anchors are fixed on both sides of the electrolysis zone in the horizontal direction to fix the electrode plate, prevent the electrode plate from deforming, facilitate the installation and removal of the electrode plate, prevent the electrode plate from shaking, and improve the stability and reliability of the electrocatalytic device. The setting of the raised platform is used to support the bottom of the electrode plate on the one hand, and on the other hand, it is convenient for the discharge of impurities at the bottom to prevent the electrolytic particles from directly connecting with the electrode plate to form a short circuit.

[0089] The raised platform can be a long strip structure extending along the width direction of the box. The end faces of the feed component 7 and the discharge component 8 are covered with through holes. The feed component and the discharge component are covered with small holes with uniform diameters, which are convenient for liquid inlet and outlet, so that the feed and discharge are kept uniform.

[0090] Wherein, the feed component 7 and the discharge component 8 may both be filter plates, and the feed component 7 and the discharge component 8 may have the same structure.

[0091] A feed pump access flange 12 and a first circulation pump access flange 13 are provided on the top of one side of the box body 1. The first circulation pump access flange 13 is located below the feed pump access flange 12. The feed pump access flange 12 and the first circulation pump access flange 13 are both connected to the feed area 2. A discharge pump access flange 14 and a second circulation pump access flange 15 are provided on the other side of the box body 1. The second circulation pump access flange 15 is located below the discharge pump access flange 14. The discharge pump access flange 14 and the second circulation pump access flange 15 are both connected to the overflow area 6. The first circulation pump access flange 13 is located below the discharge pump access flange 14. The setting of the feed pump, the discharge pump and the circulation pump access flange facilitates the connection of the feed pump, the discharge pump and the circulation pump, and ensures the uniformity of the discharge product. The setting of the circulation pump access flange facilitates the connection of the feed area and the overflow area through the circulation pump, ensures that the feed liquid fully reacts, the discharge liquid is uniform, and the liquid level reaches a certain height, and the discharge pump can be turned on.

[0092] An overflow plate 16 is provided between the discharging area 5 and the overflow area 6, and the overflow plate 16 is vertically installed in the box body 1. The upper end of the overflow plate is designed with a tooth groove lower than the overall liquid level, which is convenient for the discharging liquid to overflow to the overflow area, so that the finished product material flows out evenly. Among them, the top of the overflow plate is provided with a tooth groove, also called a convex tooth, which is convenient for the discharging liquid to overflow to the overflow area. The manufacturing material of the box body 1 is polypropylene. The manufacturing material of the box body is polypropylene, which makes the box body have the performance of high temperature resistance and corrosion resistance, reduces the weight of the box body, and reduces the production cost.

[0093] See also Figure 7-9In the above method, the multidimensional electrode comprises metal particles, a body 17 for loading metal particles, and a power connection titanium plate 18 for connecting a power source, the body 17 is a hollow structure with one side opening, the two ends of the body 17 are mesh structures, the power connection titanium plate 18 is installed on the side wall of the body 17, and the metal particles are arranged in the body 17. By designing a catalytic electrode with metal particles, a body and a power connection titanium plate, the electrode can be used as a cathode and an anode respectively, and can be connected to a power source through the power connection titanium plate, thereby increasing the contact area between the metal particles and the current, increasing the electrolysis efficiency, solving the problem of electrode passivation, and extending the service life of the electrode. The electrode is a hollow structure, and metal particles are filled in the middle. The contact area between the metal particles and the electrode frame is increased, and the process of conduction between the metals can increase the release of metal ions. The electrode is a conductive effect, and the ionization order of the metal particles takes precedence over the electrode itself, so that the electrode life is extended, and the effect can be achieved without adding a coating. The two ends of the body are mesh structures, which can not only precipitate metal ions, but also avoid the scattering of metal particles.

[0094] Among them, Figure 7 The structure shown is a reference, and the surfaces facing the reader are the two end surfaces, the front surface and the back surface of the body. Figure 8 and Fig. 9 In the structure shown, the surface facing the reader is the side wall, side surface or side end surface of the body. The body can be an electrode, which is a hollow structure and can be easily filled with aluminum particles at the upper opening.

[0095] The catalytic electrode can be used, but is not limited to, for the manufacture of high-purity polyaluminium chloride. The catalytic electrode can be a multi-dimensional catalytic electrode, including a titanium plate frame, a titanium mesh and a filler of metal particles. The titanium plate frame has a rectangular appearance, with no cover plate on the top. The entire frame is made of 2mm thick titanium plates welded by argon arc welding. The sides and bottom of the titanium plate frame are titanium perforated plates respectively. The titanium mesh is then welded to the front and back sides of the titanium plate frame by full welding, and the middle is filled with metal particles. The catalytic electrode can be used as a cathode and an anode respectively, and the positive and negative power supplies can be reversed through copper busbar connections. The materials used for the catalytic electrodes are all Ti (titanium) materials.

[0096] The titanium plate frame has a square structure, a pore structure of the titanium mesh, and a welding method. The side of the titanium plate frame is a conductive surface as a whole, which increases the conductive area. The thickness of the side of the titanium plate frame is specially 4mm, which is used for electrolytic conduction and is made of pure titanium. The copper busbar is used to connect to the power supply, and the top connection is connected by bending and punching the titanium plate, which is more stable and practical. There is no cover on the top, which is convenient for the replenishment of metal particles and a continuous electrolysis process. The titanium plate is used as the frame, and the titanium mesh is welded on the front and back sides of the frame, which can not only precipitate metal ions, but also avoid the scattering of metal particles. It can significantly increase the contact area between metal particles and current, increase electrolysis efficiency, and secondly, it can effectively solve the problem of electrode passivation and extend the service life of the electrode. After experiments, the electrolysis efficiency can be more than twice the original. The unique frame structure makes the electrode more stable and not easy to deform. At the same time, there is no need to add ruthenium iridium plating, which reduces the cost of electrode production. It can be widely used in the field of electrochemical treatment.

[0097] Function realization: 1. The electrode is a hollow structure with aluminum particles filled in the middle. The contact area between the metal particles and the electrode frame is increased, and the process of conduction between metals can increase the release of metal ions. The electrode only has a conductive effect. The ionization order of the metal particles takes precedence over the electrode itself, so the electrode life is extended, and the effect can be achieved without adding a coating.

[0098] Furthermore, the body 1 includes: a pair of titanium plate frames 19, a pair of titanium meshes 20 and three titanium plate side plates 21, the pair of titanium plate frames 19 are arranged in parallel, a gap is arranged between the pair of titanium plate frames 19, the three titanium plate side plates 21 are installed one by one on the three side walls of the pair of titanium plate frames 19, and the pair of titanium meshes 20 are installed one by one on the pair of titanium plate frames 19. The frame structure makes the electrode more stable and not easy to deform. At the same time, there is no need to add ruthenium iridium plating, which reduces the cost of electrode production. The side of the titanium plate frame is a conductive surface as a whole, which increases the conductive area. The combination of the titanium mesh welded on the front and back sides of the titanium plate frame can not only precipitate metal ions, but also avoid the scattering of metal particles.

[0099] A pair of titanium plate frames and a pair of titanium plate side plates form a hollow structure with one side open, and a pair of titanium meshes are installed one by one at both ends of the hollow structure to form a mesh structure. Both the titanium plate frames and the titanium plate side plates are rectangular structures.

[0100] The body 17 also includes: a plurality of titanium columns 22 for supporting the titanium mesh 20, and the two ends of the plurality of titanium columns 22 are connected to the titanium plate frame 19 one by one. The setting of the plurality of titanium columns is used to support the titanium mesh, which, on the one hand, facilitates the precipitation of metal ions, and on the other hand, improves the load strength of the catalytic electrode, and improves the stability and reliability of the catalytic electrode. The middle parts of the plurality of titanium columns 22 are correspondingly cross-connected. The middle parts of the plurality of titanium columns are correspondingly cross-connected to provide stable support for the middle part of the titanium mesh, improve the load strength of the catalytic electrode, and improve the stability and reliability of the catalytic electrode. Among them, a part of the plurality of titanium columns can be arranged horizontally, and the other part can be arranged vertically, the horizontally arranged titanium columns and the vertically arranged titanium columns are perpendicular to each other, and the horizontally arranged titanium columns and the vertically arranged titanium columns are connected at the intersection. The two ends of the horizontally arranged titanium columns and the vertically arranged titanium columns are correspondingly connected to the titanium plate frame.

[0101] The power connection titanium plate 18 is installed on one of the three titanium plate side plates 21. The side of the titanium plate frame is a conductive surface as a whole, which increases the conductive area. The setting of the power connection titanium plate facilitates the connection between the catalytic electrode and the power supply and improves the user experience. Among them, the power connection titanium plate and the titanium plate side plate can be integrally formed, and the power connection titanium plate is adjacent to the opening position of the body. The thickness of the titanium plate frame 19 is 2 mm, the thickness of the power connection titanium plate 18 and the titanium plate side plate 21 are both 4 mm, the mesh length of the titanium mesh 4 is 4 mm, the mesh width of the titanium mesh 4 is 3 mm, and the thickness of the titanium mesh 20 is 1.5 mm. The special size design makes the current filling more uniform and the electrolytic ions are released more uniformly. The metal particles are aluminum particles. The electrode is a hollow structure, and aluminum particles are filled in the middle. The contact area between the aluminum particles and the electrode frame is increased, and the process of conduction between the metals can increase the release of metal ions. The electrode is a conductive effect, and the ionization order of the aluminum particles takes precedence over the electrode itself, so that the electrode life is extended, and the effect can be achieved without adding a coating.

[0102] Wherein, the aluminum particles are not shown in the figure, and the aluminum particles can be directly loaded into the cavity of the main body at the opening position of the main body. Those skilled in the art can easily think of how to load the metal particles into the main body, which will not be repeated here.

[0103] The size of the metal particles can be: Φ = 5-8 mm L = 0.8-1.2 cm.

[0104] The body 17 is a rectangular parallelepiped structure, and the power connection titanium plate 18 is an "L"-shaped structure. The power connection titanium plate is an "L"-shaped structure, which is convenient for connecting the power connection titanium plate with the copper bus and the power supply, and improves stability and reliability. Among them, the titanium plate side plate and the power connection titanium plate can be a single plate, and the top of the titanium plate side plate is bent, and the bent part is the power connection part.

[0105] according to Figure 10-13It can be seen that the method for producing high-purity aluminum chloride of the present invention has achieved remarkable technical effects. Compared with the traditional production method, the aluminum oxide of the present invention has high purity and low turbidity, and various indicators are significantly higher than the technical requirements.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for producing high-purity aluminum chloride, characterized in that: The steps include: Step 1: using industrial aluminum hydroxide and 31% industrial synthetic hydrochloric acid as raw materials, adding aluminum hydroxide to hydrochloric acid in a mass ratio of 1:3.0-4.5, stirring and heating the reaction, and after the reaction pressure reaches 0.3-0.38 MPa and the reaction temperature reaches 130-135°C, reacting for 2-3 hours to obtain a colorless and transparent polyaluminum chloride solution with an aluminum oxide content of 10-13% and a basicity content of 5-40%, cooling to room temperature, and pumping into a low-basicity polyaluminum chloride solution storage tank for standby use; Step 2: using a low-basicity polyaluminium chloride solution as an electrolyte, placing it in an electrolysis device, wherein the electrolysis device comprises a DC power supply, an electrolytic cell, cathode and anode multi-dimensional electrodes, a circulation pump, an online precision density meter, an online precision pH meter and an automatic control device; the anode and cathode are filled with aluminium particles, the electrolytic cell circulation pump is turned on, the DC power supply is turned on, the electrolysis parameters are set, and static electrolysis is started; Step 3: When the basicity of the static electrolyte reaches the expected value, use a metering pump to pump the low-basicity polyaluminium chloride solution from the storage tank into the electrolytic cell to start continuous dynamic electrolysis; The process parameters in the dynamic electrolysis process are set the same as those in the static electrolysis process; The product quality is monitored and controlled by the online precision density meter and the online precision pH meter; Step 4: Turn on the automatic control system of the electrolysis equipment, give values ​​through the online precision density meter and precision pH meter at the electrolyte outlet, and link with the industrial controller PLC to control the pumping flow of the metering pump to achieve automatic control of product quality in the production process; Step 5: After the liquid is discharged from the electrolysis equipment, it is clarified or filtered in a plate and frame filter press to obtain a transparent, colorless or light-colored liquid finished product polyaluminium chloride; The electrolysis equipment also includes an electrocatalytic device, which includes: a box, a feed area, an electrolysis area for loading multiple electrode plates, a discharge area and an overflow area, the feed area, the electrolysis area, the discharge area and the overflow area are all arranged in the box, the feed area, the electrolysis area, the discharge area and the overflow area are connected in sequence, the feed area is located on one side of the box, the overflow area is located on the other side of the box, the electrolysis area and the discharge area are located between the feed area and the overflow area, the electrolysis area is adjacent to the feed area, the discharge area is adjacent to the overflow area, and multiple electrode plates correspond to the multi-dimensional electrodes; The electrolysis zone comprises: the plurality of electrode plates, a feed component and a discharge component, the feed component and the discharge component are both vertically mounted in the box, the feed component is mounted between the feed zone and the electrolysis zone, the discharge component is mounted between the electrolysis zone and the discharge zone, a plurality of electrode plates are vertically mounted in the electrolysis zone, and a plurality of electrode plates are located between the feed component and the discharge component; A feed pump access flange and a first circulation pump access flange are provided on the top of one side of the box body, the first circulation pump access flange is located below the feed pump access flange, the feed pump access flange and the first circulation pump access flange are both connected to the feed area, and a discharge pump access flange and a second circulation pump access flange are provided on the other side of the box body, the second circulation pump access flange is located below the discharge pump access flange, the discharge pump access flange and the second circulation pump access flange are both connected to the overflow area, and the first circulation pump access flange is located below the discharge pump access flange; The multi-dimensional electrode comprises: metal particles, a body for loading the metal particles, and a power connection titanium plate for connecting a power source, wherein the body is a hollow structure with one side open, and both ends of the body are mesh structures, the power connection titanium plate is installed on the side wall of the body, and the metal particles are arranged in the body; The body comprises: a pair of titanium plate frames, a pair of titanium meshes and three titanium plate side plates, the pair of titanium plate frames are arranged in parallel, a gap is arranged between the pair of titanium plate frames, the three titanium plate side plates are mounted one by one on the three side walls of the pair of titanium plate frames, and the pair of titanium meshes are mounted one by one on the pair of titanium plate frames; The body further comprises: a plurality of titanium columns for supporting the titanium mesh, the two ends of the plurality of titanium columns are connected to the titanium plate frame one by one, and the middle parts of the plurality of titanium columns are cross-connected accordingly.

2. The method according to claim 1, characterized in that An overflow plate is arranged between the discharge area and the overflow area. The overflow plate is vertically installed in the box body. The box body is made of polypropylene.

3. The method according to claim 2, characterized in that The electrolysis zone also includes: multiple groups of first fixing anchors for fixing the electrode plates, multiple groups of second fixing anchors for fixing the electrode plates, and multiple groups of raised platforms for supporting the electrode plates. The multiple groups of first fixing anchors are vertically installed on the feeding component, and there is a gap between two adjacent groups of first fixing anchors. The multiple groups of second fixing anchors are vertically installed on the discharging component, and there is a gap between two adjacent groups of second fixing anchors. The multiple groups of raised platforms are installed at the bottom of the box, one side of the electrode plate is installed between two adjacent groups of first fixing anchors, and the other side of the electrode plate is installed between two adjacent groups of second fixing anchors. The bottom end of the electrode plate is in contact with the raised platform, and the end faces of the feeding component and the discharging component are covered with through holes.

4. The method according to claim 1, characterized in that The electrolysis process parameters are set as electrode current density 50-120A / m2, voltage 0.8-15V, positive and negative pole switching frequency 1-10min / time; the expected value is 60-85%; the aluminum particle diameter is 2-12mm; the rated flow rate of the electrolytic cell circulation pump is 5-15 times the equipment volume.

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