Aluminum electrolyte recycling system

Abstract

The embodiment of the present application provides a recycling system for aluminum electrolyte, including: an electrolytic reactor for providing a reaction site for the electrolytic reaction of aluminum electrolyte; a collecting device for collecting molten salt slag produced by the aluminum electrolyte in the electrolytic reactor; a pretreatment unit for performing solid-liquid separation on the molten salt slag to obtain a first solution; a separation unit for separating impurities in the first solution to obtain a second solution, the separation unit including a membrane separation device and an extraction device connected in sequence; a distillation unit for extracting a target component of the aluminum electrolyte from the second solution; a storage device for storing the target component; a recycling unit for transporting the target component to the electrolytic reactor; and a control unit for regulating the operating parameters of the recycling system during operation. The technical solution provided by the embodiment of the utility model can improve the separation efficiency of aluminum electrolyte and impurities in molten salt slag without polluting the environment.

Description

Technical Field

[0001] The present application relates to the technical field of electrolytic aluminum, and in particular to a recycling system for aluminum electrolyte. Background Art

[0002] In aluminum electrolysis production, a molten salt system of cryolite (Na3AlF6) and alumina (Al2O3) is often used as an aluminum electrolyte. The aluminum electrolyte is continuously consumed during the electrolysis process because the aluminum liquid produced by the cathode reacts with the oxygen produced by the anode, causing components in the aluminum electrolyte such as Na3AlF6 to be continuously decomposed and consumed. In addition, the anode reaction also produces some impurity ions such as oxide ions, which enter and pollute the aluminum electrolyte. Therefore, in the traditional aluminum electrolysis process, fresh raw materials such as cryolite and alumina need to be continuously replenished to replenish the aluminum electrolyte consumed during the electrolysis process. This not only causes a waste of resources, but also the molten salt slag produced contains unused electrolytes and impurity ions, which will cause serious environmental pollution problems if directly discharged.

[0003] At present, the methods of recycling aluminum electrolyte mainly include direct melting of molten salt slag and water leaching process. Among them, the method of directly melting molten salt slag cannot efficiently separate electrolyte and impurities, has high energy consumption and will introduce new smoke pollution; the water leaching process is to use water to dissolve the electrolyte salts in the molten salt slag, which requires a large amount of water resources, produces salt-containing wastewater pollution, and the leaching efficiency is not high.

[0004] Based on this, how to provide an environmentally friendly way to improve the separation efficiency of aluminum electrolyte and impurities in molten salt slag is a technical problem that needs to be solved urgently. Utility Model Content

[0005] The embodiments of the present application provide a system for recycling aluminum electrolyte. Based on the technical solution provided in the present application, the separation efficiency of aluminum electrolyte and impurities in molten salt slag can be improved without polluting the environment.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0007] According to an embodiment of the present application, a recycling system for aluminum electrolyte is provided, and the system includes: an electrolytic reactor, which is arranged in an aluminum electrolytic cell, and the electrolytic reactor is used to provide a reaction site for the electrolytic reaction of the aluminum electrolyte; a collecting device, which is connected to the electrolytic reactor, and the collecting device is used to collect molten salt slag produced by the aluminum electrolyte in the electrolytic reactor; a pretreatment unit, which is connected to the collecting device, and the pretreatment unit is used to perform solid-liquid separation on the molten salt slag to obtain a first solution; a separation unit, which is connected to the pretreatment unit, and the separation unit includes a membrane separation device and an extraction device connected in sequence, and the separation unit is used to separate impurities in the first solution to obtain a second solution; a distillation unit, which is connected to the separation unit, and the distillation unit is used to extract a target component of the aluminum electrolyte from the second solution; a storage device, which is connected to the distillation unit, and the storage device is used to store the target component; a recycling unit, which is respectively connected to the storage device and the electrolytic reactor, and the recycling unit is used to transport the target component to the electrolytic reactor; a control unit, which is used to adjust the operating parameters of the recycling system during operation.

[0008] In some embodiments of the present application, based on the aforementioned scheme, the collecting device is connected to the electrolytic reactor through a first conveying pipe, and a first valve is arranged on the first conveying pipe; the collecting device is equipped with a first liquid level sensor, and the first liquid level sensor is used to collect the first liquid level height of the molten salt slag in the collecting device; the control unit is respectively connected to the first liquid level sensor and the first valve, and when the first liquid level height is greater than the first preset height, the first valve is controlled to be closed, and when the first liquid level height is less than the second preset height, the first valve is controlled to be opened, and the first preset height is greater than the second preset height.

[0009] In some embodiments of the present application, based on the aforementioned scheme, the pretreatment unit includes a filtering device and a centrifugal separator connected in sequence; the filtering device is configured with a first temperature sensor and a first heating module, and the first temperature sensor is used to collect the filtering temperature of the filtering device; the control unit is respectively connected to the first temperature sensor and the first heating module, and when the filtering temperature exceeds the first preset temperature range, the first heating module is regulated to keep the filtering temperature within the first preset temperature range.

[0010] In some embodiments of the present application, based on the aforementioned scheme, the filtering device is configured with a speed sensor and a motor, and the speed sensor is used to collect the speed of the filtering device; the control unit is connected to the speed sensor and the motor respectively, and when the speed of the filtering device exceeds the preset speed range, the motor is regulated to keep the speed of the filtering device within the preset speed range.

[0011] In some embodiments of the present application, based on the aforementioned scheme, the membrane separation device is configured with an anion exchange membrane; the extraction device is configured with an extractant supply module, and the extractant supply module is used to provide trioctylmethylammonium chloride extractant to the extraction device.

[0012] In some embodiments of the present application, based on the aforementioned scheme, the distillation unit includes a first distillation device, a crystallization device and a second distillation device connected in sequence; the first distillation device is used to vaporize impurities in the second solution to obtain a third solution; the crystallization device is used to precipitate the solid electrolyte in the third solution; the second distillation device is used to vaporize the target component in the solid electrolyte.

[0013] In some embodiments of the present application, based on the aforementioned scheme, the first distillation device is configured with a second temperature sensor and a second heating module, and the second temperature sensor is used to collect the first distillation temperature of the first distillation device; the control unit is respectively connected to the second temperature sensor and the second heating module, and when the first distillation temperature exceeds the second preset temperature range, the second heating module is regulated to keep the first distillation temperature within the second preset temperature range.

[0014] In some embodiments of the present application, based on the aforementioned scheme, the crystallization device is configured with a third temperature sensor and a third heating module, and the third temperature sensor is used to collect the crystallization temperature of the crystallization device; the control unit is respectively connected to the third temperature sensor and the third heating module, and when the crystallization temperature exceeds the third preset temperature range, the third heating module is regulated to keep the crystallization temperature within the third preset temperature range.

[0015] In some embodiments of the present application, based on the aforementioned scheme, the second distillation device is configured with a fourth temperature sensor and a fourth heating module, and the fourth temperature sensor is used to collect the second distillation temperature of the second distillation device; the control unit is respectively connected to the fourth temperature sensor and the fourth heating module, and when the second distillation temperature exceeds the fourth preset temperature range, the fourth heating module is regulated to keep the second distillation temperature within the fourth preset temperature range.

[0016] In some embodiments of the present application, based on the aforementioned scheme, the electrolytic reactor is configured with a second liquid level sensor, and the second liquid level sensor is used to collect the second liquid level height of the aluminum electrolyte in the electrolytic reactor; the recycling unit includes a mixing tank, and a second conveying pipeline connected to the mixing tank and the storage device respectively, and a third conveying pipeline for conveying other components in the aluminum electrolyte except the target component, and a fourth conveying pipeline connected to the mixing tank and the electrolytic reactor respectively, a second valve is provided on the second conveying pipeline, a third valve is provided on the third conveying pipeline, and a fourth valve is provided on the fourth conveying pipeline, and the mixing tank is used to uniformly mix the target component and other components of the aluminum electrolyte to obtain the aluminum electrolyte; the control unit is respectively connected to the second liquid level sensor, the second valve, the third valve and the fourth valve, and when the second liquid level height is less than the third preset height, the second valve is controlled to be opened for a first time, and the third valve is controlled to be opened for a second time, and after the target component and other components of the aluminum electrolyte are uniformly mixed in the mixing tank, the fourth valve is controlled to be opened.

[0017] The technical solution of the present application provides an aluminum electrolyte recycling system including an electrolytic reactor for providing a reaction site for the electrolytic reaction of the aluminum electrolyte; and a collecting device for collecting molten salt slag produced by the aluminum electrolyte in the electrolytic reactor; and a pretreatment unit for performing solid-liquid separation on the molten salt slag to obtain a first solution; and a separation unit for separating impurities in the first solution to obtain a second solution, the separation unit including a membrane separation device and an extraction device connected in sequence; and a distillation unit for extracting a target component of the aluminum electrolyte from the second solution; and a storage device for storing the target component; a recycling unit for transporting the target component to the electrolytic reactor; and a control unit for regulating the operating parameters of the recycling system during operation.

[0018] In the technical solution of the present application, the pretreatment unit can remove most of the solid impurities in the molten salt slag. After that, a membrane separation device and an extraction device are used to separate impurities from the first solution, which can efficiently separate most of the impurities in the first solution. The second solution obtained is an electrolyte solution with higher purity. Furthermore, the second solution is deeply purified by a distillation unit to remove stubborn impurities in the second solution and obtain an electrolyte with very high purity, that is, the target component of the aluminum electrolyte. Therefore, in the present application, the electrolyte and impurities in the molten salt slag can be efficiently separated, and the separation efficiency of the electrolyte and impurities in the molten salt slag can be improved. Since the purity of the target component of the aluminum electrolyte obtained is very high, the target component is added to the electrolysis reactor to improve the electrolysis efficiency of the electrolysis reactor.

[0019] Since the recycling system provided in the present application does not need to consume a large amount of energy in the process of recycling aluminum electrolyte, the energy consumption is low, resources can be saved, and no by-products that pollute the environment are produced in the process of recycling aluminum electrolyte. It can improve the separation efficiency of electrolyte and impurities in molten salt slag without polluting the environment.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0022] Figure 1 A schematic diagram of the architecture of an aluminum electrolyte recycling system according to an embodiment of the present application is shown;

[0023] Figure 2 A detailed schematic diagram of an aluminum electrolyte recycling system according to an embodiment of the present application is shown.

[0024] The following are the descriptions of the reference numerals:

[0025] 10—aluminum electrolysis cell, 20—electrolysis reactor,

[0026] 21—Second liquid level sensor,

[0027] 30 - first delivery pipeline, 31 - first valve,

[0028] 40 - collecting device, 41 - first liquid level sensor,

[0029] 50—pretreatment unit, 51—filtering device,

[0030] 511 - first temperature sensor, 512 - first heating module,

[0031] 52 - centrifugal separator,

[0032] 60—separation unit, 61—membrane separation device,

[0033] 611—anion exchange membrane, 62—extraction device,

[0034] 621—Extractant supply module,

[0035] 70 - distillation unit, 71 - first distillation device,

[0036] 711—second temperature sensor, 712—second heating module,

[0037] 72—crystallization device, 721—third temperature sensor,

[0038] 722—third heating module, 73—second distillation device,

[0039] 731 - a fourth temperature sensor, 732 - a fourth heating module,

[0040] 80 - storage device,

[0041] 90 - recycling unit, 91 - second delivery pipeline,

[0042] 92 - second valve, 93 - mixing tank,

[0043] 94—the fourth delivery pipeline, 95—the fourth valve,

[0044] 96 - flow meter, 97 - third delivery pipeline,

[0045] 98—the third valve,

[0046] 100—Control unit. DETAILED DESCRIPTION

[0047] Typical implementations that embody the features and advantages of the present application will be described in detail in the following description. It should be understood that the present application can have various changes in different implementations without departing from the scope of the present application, and the descriptions and illustrations therein are essentially used for illustrative purposes rather than for limiting the present application.

[0048] In the description of the present application, it should be noted that the terms "vertical", "up", "down", "horizontal", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0050] Some embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0051] It should be noted that, generally, the aluminum electrolyte is a molten salt system composed of cryolite and alumina. The aluminum electrolyte may also be a molten salt system composed of cryolite, alumina, and other salt additives (such as AlF3, CaF2, MgF2, LiF). In the following embodiments of the present application, the aluminum electrolyte is a molten salt system composed of cryolite and alumina as an example for description.

[0052] The aluminum electrolyte recycling system provided in the present application is used to recycle the electrolyte in the molten salt slag produced by the aluminum electrolyte in the electrolytic reactor, wherein the electrolyte is a target component of the aluminum electrolyte, and the target component is cryolite (Na3AlF6).

[0053] See also Figure 1 , showing a schematic diagram of the architecture of an aluminum electrolyte recycling system according to an embodiment of the present application.

[0054] In the present application, a recycling system for aluminum electrolyte is provided, which includes: an electrolytic reactor 20, a collecting device 40, a pretreatment unit 50, a separation unit 60, a distillation unit 70, a storage device 80, a recycling unit 90, and a control unit 100.

[0055] Combine the following Figure 2 The recycling system of aluminum electrolyte is elaborated in detail.

[0056] In the present application, the electrolytic reactor 20 is disposed in the aluminum electrolysis cell 10, and the electrolytic reactor 20 is used to provide a reaction site for the electrolytic reaction of the aluminum electrolyte.

[0057] During the electrolysis of aluminum electrolyte, the aluminum electrolyte is continuously consumed, among which Na3AlF6 and Al2O3 are converted into NaF and AlF3, resulting in changes in the composition and properties of the aluminum electrolyte. At the same time, the CO2 produced by the anode reaction and the liquid Al precipitated at the cathode will introduce some impurities.

[0058] When impurities in the aluminum electrolyte accumulate to a certain level, or the main components of the aluminum electrolyte (such as Na3AlF6) are lost in large quantities, the melting point, electrical conductivity and other properties of the aluminum electrolyte will drop significantly. Continuing to use it will lead to reduced current efficiency and aggravated erosion of the anode and cathode.

[0059] Therefore, it is necessary to regularly discharge the deteriorated aluminum electrolyte from the electrolytic reactor 20. Usually, the inferior aluminum electrolyte in the electrolytic reactor 20 can be discharged through the slag discharge system of the aluminum electrolytic cell 10. The discharged inferior aluminum electrolyte is molten salt slag. The main components of the discharged molten salt slag are NaF, AlF3, CaF2 and a small amount of impurities such as Al2O3 and Al.

[0060] In the present application, the collecting device 40 is connected to the electrolytic reactor 20 , and the collecting device 40 is used to collect the molten salt slag generated by the aluminum electrolyte in the electrolytic reactor 20 .

[0061] In some embodiments, the collecting device 40 is connected to the electrolytic reactor 20 via a first delivery pipeline 30 , and a first valve 31 is disposed on the first delivery pipeline 30 .

[0062] In some embodiments, the collecting device 40 is equipped with a first liquid level sensor 41, which is used to collect the first liquid level height of the molten salt slag in the collecting device 40. The first liquid level sensor 41 can be an online measuring instrument such as a radar level meter.

[0063] In the present application, the pretreatment unit 50 is connected to the collecting device 40, and the pretreatment unit 50 is used to perform solid-liquid separation on the molten salt slag to obtain a first solution.

[0064] In some embodiments, the pretreatment unit 50 includes a filtering device 51 and a centrifugal separation device connected in sequence.

[0065] The filter device 51 may be a high-temperature rotary vacuum filter, which can remove most of the solid particle impurities in the molten salt slag. After the molten salt slag is filtered by the filter device 51, the obtained solution is transported to the centrifugal separator 52, which centrifuges the filtered solution to separate the liquid phase and the solid phase. The liquid phase separated by the centrifugal separator 52 is the first solution, and the solid phase separated by the centrifugal separator 52 is a small amount of residue.

[0066] In some embodiments, the filter device 51 is equipped with a first temperature sensor 511 and a first heating module 512, and the first temperature sensor 511 is used to collect the filtering temperature of the filter device 51. The first temperature sensor 511 may be a thermocouple.

[0067] In some embodiments, the filter device 51 is further configured with a rotation speed sensor and a motor, and the rotation speed sensor is used to collect the rotation speed of the filter device 51 .

[0068] It is understandable that when the filter device 51 is a high-temperature rotary vacuum filter, when the filter device 51 is filtering the molten salt slag, it is necessary to adjust the filtering temperature and rotation speed of the filter device 51 so that the molten salt slag is accurately filtered to achieve the best filtering effect. Among them, the rotation speed of the filter device 51 is the rotation speed of the drum of the filter device 51. If the rotation speed is too low, the filtering efficiency of the filter device 51 is low. If the rotation speed is too high, it is easy to cause the filter cake to break.

[0069] In the present application, the separation unit 60 is connected to the pretreatment unit 50, and the separation unit 60 includes a membrane separation device 61 and an extraction device 62 which are connected in sequence. The separation unit 60 is used to separate impurities in the first solution to obtain a second solution.

[0070] In some embodiments, the membrane separation device 61 is configured with an anion exchange membrane 611 .

[0071] In some embodiments, the extraction device 62 is equipped with an extractant supply module 621 , and the extractant supply module 621 is used to provide trioctylmethylammonium chloride extractant to the extraction device 62 .

[0072] The first solution obtained after being treated by the pretreatment unit 50 is rich in F - anions, and Na + , Al 3+ The principle of using an anion exchange membrane 611 in the membrane separation device 61 to separate the first solution is as follows:

[0073] The surface of the membrane material of the anion exchange membrane 611 has fixed positive charge groups, which can react with anions such as F in the first solution. - Exchange occurs, and for Na + The cations have a repulsive effect, thus achieving the separation of anions and cations.

[0074] Specific to the separation process of NaF / AlF3 electrolyte solution:

[0075] (1) F in solution - Exchange with the fixed positive charges on the surface of the anion exchange membrane 611 and enter the membrane phase;

[0076] (2)Na + and Al 3+ The cations are repelled by the surface of the anion exchange membrane 611 and remain in the solution phase;

[0077] (3) With F - Continuously adsorbed by anion exchange membrane 611, F in the solution phase - As the concentration decreases, NaF / AlF3 is continuously decomposed, releasing new F - Make up for membrane adsorption loss;

[0078] (4) The final solution phase is enriched with Na + and Al 3+ , membrane phase enriched F - Therefore, the anion exchange membrane 611 can effectively separate the NaF / AlF3 electrolyte solution, thereby obtaining a relatively pure NaF / AlF3 electrolyte solution.

[0079] In the extraction device 62, since the configured extractant supply module 621 can provide trioctylmethylammonium chloride extractant (a special extractant Aliquat336) to the extraction device 62, the relatively pure NaF / AlF3 electrolyte solution is mixed with Aliquat336, and the electrolyte part can be separated from the solution by utilizing the high selective extraction ability of Aliquat336 for NaF / AlF3, and then the electrolyte is back-extracted from the Aliquat336 phase with deionized water to obtain a NaF / AlF3 electrolyte solution with higher purity, that is, the second solution.

[0080] In the present application, the distillation unit 70 is connected to the separation unit 60, and the distillation unit 70 is used to extract the target component of the aluminum electrolyte from the second solution.

[0081] Among them, the target component is Na3AlF6.

[0082] In some embodiments, the distillation unit 70 includes a first distillation device 71, a crystallization device 72, and a second distillation device 73 connected in sequence; the first distillation device 71 is used to vaporize impurities in the second solution to obtain a third solution; the crystallization device 72 is used to precipitate a solid electrolyte in the third solution; and the second distillation device 73 is used to vaporize a target component in the solid electrolyte.

[0083] In some embodiments, the first distillation device 71 is equipped with a second temperature sensor 711 and a second heating module 712 , and the second temperature sensor 711 is used to collect the first distillation temperature of the first distillation device 71 .

[0084] The purpose of the first distillation device 71 is to vaporize the impurities in the second solution, and the second solution includes NaF / AlF3 and impurities. Therefore, the first distillation temperature that is suitable for the first distillation device 71 can be determined in advance based on the melting point of NaF / AlF3 and the boiling point of the impurity component. Then, during the distillation process of the first distillation device 71, it is necessary to regulate the first distillation temperature of the first distillation device 71 so that the impurities in the second solution are effectively vaporized and thus effectively removed, so that the impurities in the obtained third solution are less than the impurities in the second solution.

[0085] In some embodiments, the crystallization device 72 is configured with a third temperature sensor 721 and a third heating module 722 . The third temperature sensor 721 is used to collect the crystallization temperature of the crystallization device 72 .

[0086] The purpose of the crystallization device 72 is to crystallize the third solution to obtain a solid electrolyte. Since the purpose of the present application is to recover Na3AlF6 from the molten salt slag, the crystallization temperature of the crystallization device 72 needs to be set according to the physical properties of Na3AlF6. If the crystallization temperature is too high, the third solution will not be completely crystallized. If the crystallization temperature is too low, impurities in the third solution will also be precipitated. Therefore, in the crystallization process of the crystallization device 72, the crystallization temperature of the crystallization device 72 needs to be precisely controlled, so as to achieve a solid electrolyte containing Na3AlF6 with a higher purity.

[0087] In some embodiments, the second distillation device 73 is equipped with a fourth temperature sensor 731 and a fourth heating module 732 , and the fourth temperature sensor 731 is used to collect the second distillation temperature of the second distillation device 73 .

[0088] The purpose of the second distillation device 73 is to vaporize Na3AlF6 in the third solution. Therefore, the distillation temperature in the second distillation device 73 needs to be determined according to the boiling point of Na3AlF6. During the distillation of the third solution by the second distillation device 73, the second distillation temperature of the second distillation device 73 needs to be precisely controlled so that the Na3AlF6 in the third solution can be completely vaporized, thereby extracting high-purity Na3AlF6 (purity>99.8%) from the third solution.

[0089] In the present application, a storage device 80 is connected to the distillation unit 70, and the storage device 80 is used to store the target component.

[0090] In the present application, the recycling unit 90 is connected to the storage device 80 and the electrolytic reactor 20 , respectively, and the recycling unit 90 is used to transport the target component to the electrolytic reactor 20 .

[0091] In some embodiments, the electrolytic reactor 20 is configured with a second liquid level sensor 21 , and the second liquid level sensor 21 is used to collect a second liquid level height of the aluminum electrolyte in the electrolytic reactor 20 .

[0092] In some embodiments, the recycling unit 90 includes a mixing tank 93, and a second conveying pipeline 91 connected to the mixing tank 93 and the storage device 80 respectively, and a third conveying pipeline 97 for conveying other components in the aluminum electrolyte except the target component, and a fourth conveying pipeline 94 connected to the mixing tank 93 and the electrolytic reactor 20 respectively, a second valve 92 is provided on the second conveying pipeline 91, a third valve 98 is provided on the third conveying pipeline 97, and a fourth valve 95 is provided on the fourth conveying pipeline 94. The mixing tank 93 is used to uniformly mix the target component and other components of the aluminum electrolyte to obtain the aluminum electrolyte.

[0093] Among them, other components include aluminum oxide.

[0094] In the present application, the control unit 100 is used to adjust the operating parameters of the recycling system during operation.

[0095] The operating parameters regulated by the control unit 100 include but are not limited to: the liquid level of the molten salt slag in the collecting device 40, the liquid level of the aluminum electrolyte in the electrolytic reactor 20, the filtering temperature of the filtering device 51, the rotation speed of the filtering device 51, the first distillation temperature of the first distillation device 71, the crystallization temperature of the crystallization device 72, the second distillation temperature of the second distillation device 73, the opening and closing state of the first valve 31, the opening and closing state of the second valve 92, the opening and closing state of the third valve 98, and the opening and closing state of the fourth valve 95. The operating parameters regulated by the control unit 100 can be achieved by existing technologies.

[0096] The following describes an implementation method for the control unit 100 to regulate the operating parameters of the recycling system.

[0097] For the case where the operating parameters are the liquid level of the collecting device 40 and the open / closed state of the first valve 31:

[0098] The control unit 100 is connected to the first liquid level sensor 41 in the collection device 40 and to the first valve 31 of the first delivery pipe 30. When the first liquid level height is greater than the first preset height, the first valve 31 is controlled to be closed, and when the first liquid level height is less than the second preset height, the first valve 31 is controlled to be opened. The first preset height is greater than the second preset height.

[0099] It can be understood that the control unit 100 can ensure the continuous and effective operation of the recycling system by monitoring the first liquid level, and can continuously recycle and utilize the aluminum electrolyte.

[0100] For the case where the operating parameter is the filtering temperature of the filtering device 51:

[0101] The control unit 100 is connected to the first temperature sensor 511 and the first heating module 512 of the filter device 51 respectively. When the filtering temperature exceeds the first preset temperature range, the first heating module 512 is regulated to keep the filtering temperature within the first preset temperature range.

[0102] In some embodiments, the first preset temperature range is [590° C., 610° C.].

[0103] When the control unit 100 monitors that the filtering temperature of the filtering device 51 is less than 590°C or greater than 610°C, the control unit 100 adjusts the heating power of the first heating module 512 so that the filtering temperature of the filtering device 51 can be maintained within the temperature range of [590°C, 610°C], thereby ensuring the filtering effect of the filtering device 51 on the molten salt slag.

[0104] For the case where the operating parameter is the rotation speed of the filter device 51:

[0105] The control unit 100 is connected to the speed sensor and the motor of the filter device 51 respectively. When the speed of the filter device 51 exceeds the preset speed range, the motor is regulated to keep the speed of the filter device 51 within the preset speed range.

[0106] In some embodiments, the preset speed range is [20 rpm, 30 rpm].

[0107] When the control unit 100 detects that the rotation speed of the filtering device 51 is lower than 20 rpm or higher than 30 rpm, the motor speed can be adjusted by adjusting the frequency converter of the motor, thereby keeping the rotation speed of the filtering device 51 within the speed range of [20 rpm, 30 rpm], thereby ensuring the filtering effect of the filtering device 51 on the molten salt slag.

[0108] For the case where the operating parameter is the first distillation temperature of the first distillation device 71:

[0109] The control unit 100 is connected to the second temperature sensor 711 and the second heating module 712 of the first distillation device 71 respectively. When the first distillation temperature exceeds the second preset temperature range, the second heating module 712 is regulated to keep the first distillation temperature within the second preset temperature range.

[0110] In some embodiments, the second preset temperature range is [695° C., 705° C.] The second preset temperature range is optimized based on the melting point of NaF / AlF3 and the boiling point of the impurity components.

[0111] When the control unit 100 monitors that the first distillation temperature is lower than 695°C or higher than 705°C, the control unit 100 adjusts the heating power of the second heating module 712 so that the first distillation temperature of the first distillation device 71 is always maintained within the temperature range of [695°C, 705°C], thereby effectively removing impurities in the second solution treated by the first distillation device 71.

[0112] For the case where the operating parameter is the crystallization temperature of the crystallization device 72:

[0113] The control unit 100 is respectively connected to the third temperature sensor 721 and the third heating module 722 in the crystallization device 72. When the crystallization temperature exceeds the third preset temperature range, the third heating module 722 is regulated to keep the crystallization temperature within the third preset temperature range.

[0114] In some embodiments, the third preset temperature range is [548° C., 552° C.] The third preset temperature range is determined according to the crystallization temperature of Na3AlF6.

[0115] When the control unit 100 detects that the crystallization temperature of the crystallization device 72 is lower than 548°C or higher than 552°C, the heating power of the third heating module 722 of the crystallization device 72 is adjusted so that the crystallization temperature of the crystallization device 72 is always maintained within the temperature range of [548°C, 552°C], and Na3AlF6 in the third solution can be accurately precipitated.

[0116] For the case where the operating parameter is the second distillation temperature of the second distillation device 73:

[0117] The control unit 100 is respectively connected to the fourth temperature sensor 731 and the fourth heating module 732 of the second distillation device 73. When the second distillation temperature exceeds the fourth preset temperature range, the fourth heating module 732 is regulated to keep the second distillation temperature within the fourth preset temperature range.

[0118] In some embodiments, the fourth preset temperature range is [890° C., 910° C.], and the fourth preset temperature range is determined according to the boiling point of Na 3 AlF 6 .

[0119] When the control unit 100 monitors that the second distillation temperature of the second distillation device 73 is lower than 890°C or higher than 910°C, the heating power of the fourth heating module 732 of the second distillation device 73 is adjusted so that the second distillation temperature of the second distillation device 73 is always maintained at [890°C, 910°C], so that the second distillation device 73 can separate high-purity Na3AlF6 from the solid electrolyte.

[0120] For the case where the operating parameters are the liquid level of the aluminum electrolyte in the electrolytic reactor 20, the opening and closing state of the second valve 92, the opening and closing state of the third valve 98, and the opening and closing state of the fourth valve 95:

[0121] The control unit 100 is respectively connected to the second liquid level sensor 21 in the electrolytic reactor 20, the second valve 92 on the second delivery pipe 91, the third valve 98 on the third delivery pipe 97 and the fourth valve 95 on the fourth delivery pipe 94. When the second liquid level height is less than the third preset height, the second valve 92 is controlled to be opened for a first time length, and the third valve 98 is controlled to be opened for a second time length. After the target component and other components of the aluminum electrolyte are evenly mixed in the mixing tank 93, the fourth valve 95 is controlled to be opened.

[0122] According to production experience and process calculations, the second liquid level height of the aluminum electrolyte in the electrolytic reactor 20 needs to be within a reasonable range, such as 60%-80% of the height of the electrolytic reactor 20. If the second liquid level height is too high or too low, it will affect the electrolysis efficiency of the electrolytic reactor 20 and the product quality of the aluminum electrolytic cell 10.

[0123] In some embodiments, the third preset height is 60% of the height of the electrolytic reactor 20 .

[0124] It should be noted that, during the recycling process of aluminum electrolyte, the ratio of different components in the aluminum electrolyte in the electrolytic reactor 20 will change dynamically. The reasons are: (1) the rates at which the electrolytic reaction consumes Na3AlF6 and Al2O3 are different; (2) the recycled aluminum electrolyte is mainly Na3AlF6, which is different from the newly added Al2O3 component; (3) the ratio of Na3AlF6 and Al2O3 lost by volatilization and leakage of the aluminum electrolyte is different.

[0125] Therefore, it is necessary to dynamically balance the components of the aluminum electrolyte in the electrolytic reactor 20 to ensure that its composition fluctuates within an optimal range. For example, the mass ratio of Na3AlF6 and Al2O3 in the aluminum electrolyte in the electrolytic reactor 20 needs to be controlled to be 1.0-1.2.

[0126] In some embodiments, an online component analyzer, such as an X-ray fluorescence spectrometer or other rapid analysis equipment, may be provided in the recycling system. The online component analyzer is used to analyze the composition of the aluminum electrolyte in the electrolytic reactor 20 to obtain a composition result.

[0127] The control unit 100 is connected to the online component analyzer. When the control unit 100 monitors that the second liquid level height of the aluminum electrolyte in the electrolytic reactor 20 is less than the third preset height, the control unit 100 determines the target mass ratio of the target component and other components of the aluminum electrolyte replenished to the electrolytic reactor 20 based on the composition results analyzed by the online component analyzer. Further, the control unit 100 determines the first mass of the target component that the storage device 80 needs to transport to the mixing tank 93 according to the target mass ratio, and determines the second mass of other components that the third delivery pipeline 97 needs to transport to the mixing tank 93; further, the control unit 100 determines the first time length for opening the second valve 92 according to the first mass, and determines the second time length for opening the third valve 98 according to the second mass.

[0128] It can be understood that, by controlling the second valve 92 and the third valve 98 by the control unit 100, the aluminum electrolyte obtained after uniform mixing in the mixing tank 93 can meet the requirements of the current state of the electrolytic reactor 20, and then the aluminum electrolyte in the mixing tank 93 is transported to the electrolytic reactor 20, so that the ratio of each component of the aluminum electrolyte in the electrolytic reactor 20 is within the optimal range, which can improve the electrolysis efficiency of the electrolytic reactor 20.

[0129] After the control unit 100 opens the fourth valve 95 , there are at least two ways for the control unit 100 to close the fourth valve 95 .

[0130] The first embodiment: a flow meter 96 can be provided on the fourth delivery pipeline 94, and the flow meter 96 is used to collect the flow rate of the aluminum electrolyte transported in the fourth delivery pipeline 94. The flow meter 96 is connected to the control unit 100. The control unit 100 monitors the cumulative delivery amount of the aluminum electrolyte transported by the fourth delivery pipeline 94 to the electrolytic reactor 20 according to the flow rate of the aluminum electrolyte collected by the flow meter 96. When it is monitored that the cumulative delivery amount reaches a preset amount, the fourth valve 95 is controlled to be closed.

[0131] In a second embodiment, when the control unit 100 detects that the second liquid level of the aluminum electrolyte in the electrolytic reactor 20 is greater than a fourth preset height, the fourth valve 95 is controlled to be closed, wherein the fourth preset height can be set to 70% of the height of the electrolytic reactor 20.

[0132] In summary, providing a reuse unit 90 in the recycling system, and replenishing aluminum electrolyte to the electrolytic reactor 20 through a homogenization ratio control scheme, can effectively solve the problem of unbalanced aluminum electrolyte components, provide stable and reliable material guarantee for the electrolysis process, improve electrolysis efficiency and product quality, and is also the key to achieving efficient recycling of electrolytes.

[0133] In the technical solutions provided in some embodiments of the present application, the pretreatment unit 50 can remove most of the solid impurities in the molten salt slag. Afterwards, the membrane separation device 61 and the extraction device 62 are used to separate the impurities from the first solution, which can efficiently separate most of the impurities in the first solution. The second solution obtained is an electrolyte solution with higher purity. Furthermore, the distillation unit 70 is used to deeply purify the second solution, which can remove the stubborn impurities in the second solution and obtain an electrolyte with very high purity, that is, the target component of the aluminum electrolyte. Therefore, in the present application, the electrolyte and impurities in the molten salt slag can be efficiently separated, and the separation efficiency of the electrolyte and impurities in the molten salt slag can be improved. Since the purity of the target component of the aluminum electrolyte obtained is very high, the target component is added to the electrolysis reactor 20, which can improve the electrolysis efficiency of the electrolysis reactor 20.

[0134] Since the recycling system provided in the present application does not need to consume a large amount of energy in the process of recycling aluminum electrolyte, the energy consumption is low, resources can be saved, and no by-products that pollute the environment are produced in the process of recycling aluminum electrolyte. It can improve the separation efficiency of electrolyte and impurities in molten salt slag without polluting the environment.

[0135] The above description is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A system for recycling aluminum electrolyte, characterized in that: The system comprises: An electrolytic reactor is arranged in the aluminum electrolytic cell, and is used to provide a reaction site for the electrolytic reaction of the aluminum electrolyte; A collecting device connected to the electrolytic reactor, the collecting device is used to collect molten salt slag produced by the aluminum electrolyte in the electrolytic reactor; A pretreatment unit connected to the collecting device, the pretreatment unit is used to perform solid-liquid separation on the molten salt slag to obtain a first solution; A separation unit connected to the pretreatment unit, the separation unit comprising a membrane separation device and an extraction device connected in sequence, the separation unit being used to separate impurities in the first solution to obtain a second solution; a distillation unit connected to the separation unit, the distillation unit being used to extract a target component of the aluminum electrolyte from the second solution; A storage device connected to the distillation unit, the storage device is used to store the target component; a recycling unit, connected to the storage device and the electrolytic reactor, respectively, and used to transport the target component to the electrolytic reactor; A control unit is used to adjust operating parameters of the recycling system during operation.

2. The system according to claim 1, characterized in that The collecting device is connected to the electrolytic reactor via a first delivery pipeline, and the first delivery pipeline is provided with a first valve; The collecting device is provided with a first liquid level sensor, and the first liquid level sensor is used to collect a first liquid level height of the molten salt slag in the collecting device; The control unit is connected to the first liquid level sensor and the first valve respectively, and controls the first valve to be closed when the first liquid level height is greater than a first preset height, and controls the first valve to be opened when the first liquid level height is less than a second preset height, and the first preset height is greater than the second preset height.

3. The system according to claim 1, characterized in that The pretreatment unit comprises a filter device and a centrifugal separator connected in sequence; The filtering device is equipped with a first temperature sensor and a first heating module, and the first temperature sensor is used to collect the filtering temperature of the filtering device; The control unit is connected to the first temperature sensor and the first heating module respectively, and when the filtering temperature exceeds a first preset temperature range, the first heating module is regulated to keep the filtering temperature within the first preset temperature range.

4. The system according to claim 3, characterized in that The filter device is equipped with a rotation speed sensor and a motor, and the rotation speed sensor is used to collect the rotation speed of the filter device; The control unit is connected to the rotation speed sensor and the motor respectively, and when the rotation speed of the filter device exceeds a preset rotation speed range, the motor is regulated to keep the rotation speed of the filter device within the preset rotation speed range.

5. The system according to claim 1, characterized in that The membrane separation device is equipped with an anion exchange membrane; The extraction device is equipped with an extractant supply module, and the extractant supply module is used to provide trioctylmethylammonium chloride extractant to the extraction device.

6. The system according to claim 1, characterized in that The distillation unit comprises a first distillation device, a crystallization device and a second distillation device connected in sequence; The first distillation device is used to vaporize impurities in the second solution to obtain a third solution; The crystallization device is used to precipitate the solid electrolyte in the third solution; The second distillation device is used to vaporize a target component in the solid electrolyte.

7. The system according to claim 6, characterized in that The first distillation device is equipped with a second temperature sensor and a second heating module, and the second temperature sensor is used to collect the first distillation temperature of the first distillation device; The control unit is connected to the second temperature sensor and the second heating module respectively, and when the first distillation temperature exceeds a second preset temperature range, the second heating module is regulated to keep the first distillation temperature within the second preset temperature range.

8. The system according to claim 6, characterized in that The crystallization device is equipped with a third temperature sensor and a third heating module, and the third temperature sensor is used to collect the crystallization temperature of the crystallization device; The control unit is connected to the third temperature sensor and the third heating module respectively, and when the crystallization temperature exceeds a third preset temperature range, the third heating module is regulated to keep the crystallization temperature within the third preset temperature range.

9. The system according to claim 6, characterized in that The second distillation device is equipped with a fourth temperature sensor and a fourth heating module, and the fourth temperature sensor is used to collect the second distillation temperature of the second distillation device; The control unit is connected to the fourth temperature sensor and the fourth heating module respectively, and when the second distillation temperature exceeds a fourth preset temperature range, the fourth heating module is regulated to keep the second distillation temperature within the fourth preset temperature range.

10. The system according to claim 1, characterized in that The electrolytic reactor is equipped with a second liquid level sensor, which is used to collect a second liquid level height of the aluminum electrolyte in the electrolytic reactor; The recycling unit includes a mixing tank, a second delivery pipeline connected to the mixing tank and the storage device respectively, a third delivery pipeline for delivering other components in the aluminum electrolyte except the target component, and a fourth delivery pipeline connected to the mixing tank and the electrolytic reactor respectively, the second delivery pipeline is provided with a second valve, the third delivery pipeline is provided with a third valve, and the fourth delivery pipeline is provided with a fourth valve, the mixing tank is used to uniformly mix the target component and other components of the aluminum electrolyte to obtain the aluminum electrolyte; The control unit is connected to the second liquid level sensor, the second valve, the third valve and the fourth valve respectively. When the second liquid level height is less than a third preset height, the second valve is controlled to be opened for a first time length, and the third valve is controlled to be opened for a second time length. After the target component and other components of the aluminum electrolyte are evenly mixed in the mixing tank, the fourth valve is controlled to be opened.

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