Multifunctional binder for aluminum electrolysis, preparation method therefor and use thereof

Abstract

Disclosed is a multifunctional binder for aluminum electrolysis, the binder comprising the following chemical components by parts by mass: 5-20 parts of polyimide, 8-20 parts of sodium hydroxide, 22-45 parts of sodium silicate, 40-60 parts of a solvent, 0.5-8 parts of succinic acid and 0.5-5 parts of propylene oxide-ethylene oxide block copolymer.

Description

A multifunctional binder for aluminum electrolysis, its preparation method and application Cross-references to related applications

[0001] This application claims priority to Chinese patent application No. 202510276195.0, filed on March 10, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of aluminum electrolysis technology, and in particular to a multifunctional binder for aluminum electrolysis, its preparation method, and its application. Background Technology

[0003] The aluminum electrolysis cell is the core equipment in aluminum electrolysis production. Its design needs to meet the requirements of heat preservation, insulation, oxidation resistance and weak magnetization. These requirements are closely related to electrolysis efficiency, safety and equipment life.

[0004] Aluminum electrolysis primarily involves the electrolysis of alumina to obtain metallic aluminum, a process typically conducted at high temperatures (approximately 940℃-980℃). Inside the electrolysis cell, alumina (Al₂O₃) must dissolve in molten cryolite (Na₃AlF₆) to form ionic states. The presence of an insulation layer in the electrolysis cell reduces heat loss, ensuring the electrolyte (cryolite) remains in a molten state. Electrolysis is an energy-intensive process (accounting for 30%–40% of production costs); effective insulation reduces the need for external heating and lowers energy consumption. Insufficient electrolysis temperature can lead to electrolyte solidification, forming a crust that hinders the flow of molten aluminum and the reaction process, potentially even causing production accidents.

[0005] Aluminum electrolytic cells are supplied with direct current (up to hundreds of kiloamperes). If the cell material is conductive, the current will bypass the electrolyte and flow directly into the cell, leading to short circuits and energy waste. Installing an insulating lining (such as a carbon cathode or alumina layer) inside the aluminum electrolytic cell ensures that all current flows through the electrolyte, promoting the effective reduction of aluminum ions (Al). 3+ →Al). In addition, the insulation inside the aluminum electrolysis cell can also prevent the aluminum electrolysis cell from being electrified and causing electric shock risk to the operators.

[0006] The interior of an aluminum electrolytic cell contains high-temperature fluoride gases (such as CF4 and COF2) and molten salts, which are highly corrosive to the metal tank materials (such as steel shells). Applying an anti-oxidation coating (such as alumina or silicon carbide) to the aluminum electrolytic cell can slow down the oxidation and corrosion of the metal tank materials, preventing structural damage or leakage. Impurities generated from the oxidation of the metal tank materials can contaminate the electrolyte, affecting the purity of the molten aluminum (e.g., impurities such as iron and silicon from the metal tank materials may mix into the molten aluminum).

[0007] A large current (e.g., 500kA) flowing through a conductor generates a strong magnetic field, which may affect the stability and current distribution of the molten aluminum layer, leading to fluctuations or even short circuits. For example, by symmetrically arranging the anode conductors and busbars, or by employing a reverse current compensation design, the magnetic field strength can be weakened, ensuring stable deposition of the molten aluminum. A weak magnetic field environment can reduce eddy current losses in the molten aluminum and improve electrolysis efficiency (under ideal conditions, current efficiency can reach over 95%).

[0008] Therefore, aluminum electrolytic cells need to be well-insulated, electrically insulating, oxidation-resistant, and weakly magnetized to reduce energy waste and lower electricity consumption per ton of aluminum; to ensure long-term, safe, and stable operation of the equipment; and to improve product quality. Currently, most research focuses on single-function coatings such as insulating and anti-oxidation coatings, failing to meet the needs of other parts of the aluminum electrolytic cell for oxidation resistance, insulation, and weak magnetization. Furthermore, the application of binders in related technologies is limited to the bonding of carbon materials and is not suitable for metal-to-metal or metal-to-ceramic bonding. Summary of the Invention

[0009] One or more embodiments of this disclosure address how to improve the bonding strength between metals or between metals and ceramics.

[0010] In a first aspect, the multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure comprises, by weight, the following chemical components: 5 to 20 parts of polyimide, 8 to 20 parts of sodium hydroxide, 22 to 45 parts of sodium silicate, 40 to 60 parts of solvent, 0.5 to 8 parts of succinic acid, and 0.5 to 5 parts of propylene glycol block polyether.

[0011] Secondly, according to some embodiments of this disclosure, the preparation method of the above-mentioned multifunctional binder for aluminum electrolysis includes: obtaining each raw material of the multifunctional binder for aluminum electrolysis; under stirring conditions, sequentially adding the sodium hydroxide, the sodium silicate and the polyimide to the solvent having a set temperature to obtain a mixture; adding the succinic acid and the propylene glycol block polyether to the mixture to obtain the multifunctional binder for aluminum electrolysis.

[0012] Thirdly, the application of the multifunctional adhesive for aluminum electrolysis according to some embodiments of this disclosure includes: applying the multifunctional adhesive for aluminum electrolysis between metals or between metals and ceramics for bonding between metals or between metals and ceramics.

[0013] Fourthly, the application of the multifunctional binder for aluminum electrolysis according to some embodiments of this disclosure includes: mixing the multifunctional binder for aluminum electrolysis with functional powder to obtain a mixture; applying the mixture to a designated area of ​​an aluminum electrolysis cell and curing the mixture for heat preservation, insulation, oxidation resistance and weak magnetization of the designated area. Attached Figure Description

[0014] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0015] To more clearly illustrate the technical solutions in the embodiments or related technologies of this disclosure, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0016] Figure 1 shows a schematic flowchart of a method for preparing a multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure;

[0017] Figure 2 shows a schematic flowchart of a method for preparing a multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0019] Various embodiments of this disclosure may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this disclosure; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0020] Furthermore, in the description of this disclosure, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships may exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation" such as parts by weight or parts by mass indicates the proportional relationship between components. In the proportional relationships discussed in this article, the parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, and the proportion number should be understood as the second term. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion number in the proportion in the order of description, that is, the mass of substance A : the mass of substance B : the mass of substance C = 1:2:3.

[0021] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this disclosure are available on the market or can be prepared by existing methods.

[0022] The multifunctional binder for aluminum electrolysis according to some embodiments of this disclosure comprises, by weight, the following chemical components: 5 to 20 parts polyimide, 8 to 20 parts sodium hydroxide, 22 to 45 parts sodium silicate, 40 to 60 parts solvent, 0.5 to 8 parts succinic acid, and 0.5 to 5 parts propylene glycol block polyether.

[0023] The multifunctional binder for aluminum electrolysis according to some embodiments of this disclosure has the following advantages compared to related technologies:

[0024] According to some embodiments of this disclosure, a multifunctional adhesive for aluminum electrolysis comprises, by weight, the following chemical components: 5-20 parts polyimide, 8-20 parts sodium hydroxide, 22-45 parts sodium silicate, 40-60 parts solvent, 0.5-8 parts succinic acid, and 0.5-5 parts propylene glycol block polyether. Through the rational design of the chemical composition of the multifunctional adhesive for aluminum electrolysis, polyimide exhibits superior high-temperature resistance while simultaneously imparting insulation and weak magnetization properties. The interaction of sodium hydroxide, sodium silicate, and solvent yields water glass, allowing polyimide and the water glass matrix to form an interpenetrating network, maintaining the integrity and mechanical strength of the bonded layer even at 900°C. Simultaneously, the silica tetrahedra of the water glass fill the pyrolysis voids in the polyimide, reducing thermal stress concentration and preventing high-temperature cracking or peeling. Succinic acid possesses water resistance and enhances adhesion to the substrate. Propylene glycol block polyether acts as an antifoaming agent. This multifunctional binder for aluminum electrolysis can improve the bonding force between metals or between metals and ceramics. When mixed with functional powder and coated on the required parts of the electrolytic cell, it can meet the requirements of heat preservation, insulation, oxidation resistance and weak magnetization during the operation of the aluminum electrolytic cell.

[0025] In some embodiments, the solvent may be deionized water or an analogue of deionized water.

[0026] According to some embodiments of the present disclosure, a multifunctional binder for aluminum electrolysis has been rationally designed with the following components, and the functions of each component are as follows:

[0027] Polyimide: Provides structural stability under high-temperature conditions for the adhesive layer formed by multifunctional adhesives used in aluminum electrolysis. At temperatures up to 900°C, it maintains the integrity and mechanical strength of the adhesive layer while imparting insulation and weak magnetization properties. The aromatic heterocyclic structure of polyimide suppresses electron conduction, thereby achieving the insulation and weak magnetization of the adhesive layer. For example, the mass fraction of the polyimide can be 5 parts, 7 parts, 10 parts, 12 parts, 16 parts, 18 parts, 20 parts, etc.

[0028] Sodium hydroxide, sodium silicate, and solvent: Sodium hydroxide can form a Na₂O·nSiO₂ type water glass matrix with sodium silicate and solvent. Simultaneously, the alkaline environment provided by sodium hydroxide promotes the formation of the silicate network and adjusts the pH of the system. Sodium silicate can form an inorganic ceramicized structure within the Na₂O·nSiO₂ type water glass matrix, whose coefficient of thermal expansion can match that of the metal substrate. Furthermore, the polyimide molecular chains form an interpenetrating network with the inorganic ceramicized structure of the Na₂O·nSiO₂ type water glass matrix, while the silicon-oxygen tetrahedra in the Na₂O·nSiO₂ type water glass matrix can fill the pyrolysis voids of the polymer, achieving gradient heat resistance. For example, the mass fraction of sodium hydroxide can be 8 parts, 10 parts, 12 parts, 14 parts, 18 parts, 20 parts, etc., the mass fraction of sodium silicate can be 22 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, etc., and the mass fraction of solvent can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, etc.

[0029] Succinic acid: The carboxyl groups of succinic acid can complex with the hydroxyl groups on the metal surface, which can increase the interfacial bonding energy and thus improve the adhesion to the substrate. Simultaneously, succinic acid also has water resistance, thereby improving the water resistance of the multifunctional adhesive for aluminum electrolysis. For example, the mass fraction of succinic acid can be 0.5 parts, 1 part, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc.

[0030] Propylene glycol block polyether: Propylene glycol block polyether can reduce the surface tension of multifunctional binder systems used in aluminum electrolysis and eliminate micron-sized bubbles. Simultaneously, the decomposition temperature of propylene glycol block polyether is >250°C, and a protective volatile layer can be formed at high temperatures. For example, the mass fraction of this propylene glycol block polyether can be 0.5 parts, 1 part, 2 parts, 3 parts, 4 parts, or 5 parts.

[0031] In some embodiments, the multifunctional binder for aluminum electrolysis, by weight, further includes at least one of the following chemical components: 2 to 10 parts of silicone, 0.01 to 1 part of nonionic polyacrylamide, and 0.01 to 1 part of polyferric sulfate.

[0032] Alternatively, the functions of the above components are as follows:

[0033] Silicone: The nanoscale pores of silicone enable a physical anchoring effect, enhancing shear strength. The silanol groups on the silicone surface and the amino groups of polyimide can form a hydrogen bond network. Simultaneously, partial melting of silicone at 900°C forms a SiO2 transition layer, thereby reducing the thermal stress concentration factor of the multifunctional binder system for aluminum electrolysis. Furthermore, silicone has good adsorption capacity, which can supplement the adhesive effect during the preparation of the multifunctional binder for aluminum electrolysis. For example, the mass fraction of the silicone can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 9 parts, 10 parts, etc.

[0034] Nonionic polyacrylamide: The viscosity of the multifunctional binder system for aluminum electrolysis can be increased through the polymer chain entanglement of nonionic polyacrylamide. Simultaneously, nonionic polyacrylamide can form three-dimensional steric hindrance, achieving dynamic stability of the zeta potential during the mixing of the multifunctional binder for aluminum electrolysis with functional powders. Furthermore, nonionic polyacrylamide exhibits good adhesion and dispersing properties. If a higher viscosity multifunctional binder for aluminum electrolysis is required, the mass fraction of nonionic polyacrylamide can be appropriately added or increased. For example, the mass fraction of nonionic polyacrylamide can be 0.01 parts, 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, etc.

[0035] The zeta potential refers to the potential of the shear plane, also known as the electrodynamic potential or zeta potential (ζ-potential or ζ-potential), and is an important indicator for characterizing the stability of colloidal dispersions.

[0036] Polyferric sulfate: Fe in polyferric sulfate 3+ Hydrolysis produces [Fe(OH)] 2+ As a colloid, polyferric sulfate can passivate metal substrates. Simultaneously, it can form Fe-OOCR complexes with succinic acid, improving the dispersion of powder components. Polyferric sulfate can react with sodium silicate at high temperatures to generate Fe2(SiO3)3, which can reduce the overall porosity of the multifunctional binder for aluminum electrolysis. Furthermore, polyferric sulfate also has a certain dispersing effect; when corrosion-resistant powders need to be added to the multifunctional binder for electrolysis, polyferric sulfate can effectively fill the corrosion-resistant powders, thereby improving the corrosion resistance of the multifunctional binder for electrolysis. For example, the mass fraction of polyferric sulfate can be 0.01 parts, 0.1 parts, 0.2 parts, 0.4 parts, 0.6 parts, 0.8 parts, 1 part, etc.

[0037] In some embodiments, the propylene glycol block polyethers include at least one of the following: L35, L45, L64, and L65.

[0038] It should be noted that propylene glycol block polyethers are a type of nonionic surfactant, belonging to the polyether polymer family. Their designations (such as L35, L45, L64, L65, etc.) typically reflect the difference in the block ratio and molecular weight of ethylene oxide and propylene oxide in their molecular structure. L35 has a low ethylene oxide content and strong hydrophobicity; L45 has a slightly higher ethylene oxide content than L35, a moderate HLB value, and a good hydrophilic-hydrophobic balance; L64 has a higher ethylene oxide content, an HLB value of approximately 18-20, and significantly enhanced hydrophilicity; L65 has the highest ethylene oxide content, a high HLB value (20-24), and strong hydrophilicity.

[0039] Figure 1 shows a schematic flowchart of a method for preparing a multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure. As shown in Figure 1, the method for preparing the multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure includes:

[0040] S11. Obtain the various raw materials for the multifunctional binder for aluminum electrolysis;

[0041] S12. Under stirring conditions, sodium hydroxide, sodium silicate and polyimide are added sequentially to a solvent at a set temperature to obtain a mixture.

[0042] S13. Succinic acid and propylene glycol block polyether are added to the mixture to obtain a multifunctional binder for aluminum electrolysis.

[0043] In some embodiments, when adding succinic acid and the propylene glycol block polyether to the mixture, silica gel, nonionic polyacrylamide and polyferric sulfate may be added to the mixture.

[0044] Figure 2 shows a schematic flowchart of a method for preparing a multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure. As shown in Figure 2, the method for preparing the multifunctional binder for aluminum electrolysis according to some embodiments of the present disclosure includes:

[0045] S21. Obtain the various raw materials for the multifunctional binder for aluminum electrolysis;

[0046] S22. Under stirring conditions, sodium hydroxide, sodium silicate and polyimide are added sequentially to a solvent at a set temperature to obtain a mixture;

[0047] S23. Succinic acid, propylene glycol block polyether, silica gel, nonionic polyacrylamide and polyferric sulfate are added to the mixture to obtain a multifunctional binder for aluminum electrolysis.

[0048] In some implementations, the temperature is set to 60°C to 80°C.

[0049] During the preparation of the multifunctional binder for aluminum electrolysis, constant temperature heating is required during the stirring and dissolution process. A heating temperature range of 60–80°C can improve the dissolution efficiency of polyimide and prevent solvent evaporation. Simultaneously, this temperature range can balance the hydrolysis rate of sodium silicate and the acid-base neutralization rate, preventing gelation. Furthermore, a heating temperature range of 60–80°C can prevent the high-temperature precipitation of propylene glycol block polyethers (such as L64) or polymer degradation. For example, this set temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, etc.

[0050] In some embodiments, the feeding rate of each raw material of the multifunctional binder for aluminum electrolysis is 2 g / min to 10 g / min.

[0051] In the preparation of the multifunctional binder for aluminum electrolysis, the raw materials are added in small, uniform amounts, with the addition rate of each raw material maintained between 2 g / min and 10 g / min. This ensures uniform dispersion of the raw materials and reduces undissolved particles or agglomeration. Simultaneously, it delays the heat release from the neutralization reaction of succinic acid and NaOH. Furthermore, maintaining the addition rate of each raw material at 2 g / min to 10 g / min allows the silica gel and polyacrylamide to gradually form a uniform network, avoiding abrupt viscosity changes. For example, the addition rates of the various raw materials in the multifunctional binder for aluminum electrolysis can be 2 g / min, 4 g / min, 6 g / min, 8 g / min, 9 g / min, 10 g / min, etc.

[0052] The product prepared by the preparation method of the multifunctional binder for aluminum electrolysis is the aforementioned multifunctional binder for aluminum electrolysis. The chemical composition of the multifunctional binder for aluminum electrolysis prepared by the preparation method can be referred to the above embodiments. Since the preparation method of the multifunctional binder for aluminum electrolysis adopts some or all of the technical solutions of the embodiments of the multifunctional binder for aluminum electrolysis, it has at least all the beneficial effects brought about by the technical solutions of the embodiments of the multifunctional binder for aluminum electrolysis, which will not be elaborated here.

[0053] Based on a general inventive concept, the application of the multifunctional binder for aluminum electrolysis according to any of the above embodiments of some implementations of this disclosure includes:

[0054] A multifunctional adhesive for aluminum electrolysis is applied between metals or between metals and ceramics for bonding between metals or between metals and ceramics.

[0055] Based on a general inventive concept, the application of the multifunctional binder for aluminum electrolysis according to any of the above embodiments of some implementations of this disclosure includes:

[0056] A multifunctional binder for aluminum electrolysis is mixed with functional powder to obtain a mixture;

[0057] The mixture is applied to a designated area of ​​the aluminum electrolytic cell and then cured for use in heat preservation, insulation, oxidation resistance, and weak magnetization of the designated area.

[0058] It should be noted that the coating can be applied manually or using a spraying machine.

[0059] In some embodiments, the particle size of the functional powder is 0.5 μm to 35 μm, and the functional powder includes at least one of the following: alumina powder, aluminum silicate powder, silica aerogel powder, zirconium oxide powder, silicon carbide powder, aluminum nitride powder, graphite powder, mica powder, nickel powder, nickel-chromium alloy powder, nickel-chromium-iron alloy powder, nickel-aluminum powder, copper powder, cobalt powder, and iron powder.

[0060] The functional powder exhibits optimal performance when its particle size is between 0.5 μm and 35 μm. If the particle size of the functional powder is larger than 35 μm, the cured mixture will have surface unevenness; if the particle size is smaller than 0.5 μm, the mixture is prone to agglomeration, which will affect its overall performance after curing. For example, the particle size of the functional powder can be 0.5 μm, 3 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 35 μm, etc.

[0061] In some implementations, curing is performed at room temperature or by heating.

[0062] The curing time at room temperature can be 3 hours;

[0063] The curing temperature can be 60℃~200℃, and the curing time can be 0.5h~3h.

[0064] In some implementations, the heat curing process can be one or both of an infrared heating module and a far-infrared heater to ensure that the mixture coating can be completely cured.

[0065] The multifunctional adhesive for aluminum electrolysis prepared in this embodiment can be directly applied for bonding; or functional powder can be added, and the mixture obtained after uniform mixing can be applied to the required parts of the aluminum electrolysis cell to play the roles of heat preservation, insulation, anti-oxidation, and weak magnetization.

[0066] In summary, the multifunctional binder for aluminum electrolysis, its preparation method, and its application according to some embodiments of this disclosure have the following advantages:

[0067] (1) Excellent high-temperature performance: Polyimide forms an interpenetrating network with the water glass matrix (Na2O·nSiO2), which can maintain the integrity and mechanical strength of the bonding layer formed by the multifunctional adhesive for aluminum electrolysis at 900℃, which is significantly better than traditional organic adhesives. At the same time, the silicon-oxygen tetrahedra of the water glass matrix (Na2O·nSiO2) can fill the pyrolysis voids of polyimide, reduce thermal stress concentration, and avoid high-temperature cracking or peeling.

[0068] (2) Multifunctional synergistic effect: The aromatic heterocyclic structure of polyimide can suppress electron conduction, endowing the multifunctional binder for aluminum electrolysis with insulation and weak magnetization properties, making it suitable for electromagnetically sensitive environments (such as aluminum electrolysis cells). At the same time, succinic acid can enhance the interfacial bonding energy by complexing with the hydroxyl groups on the metal surface through carboxyl groups; the nanopores of silicone achieve physical anchoring and improve shear strength.

[0069] (3) Environmental protection and process controllability: Using deionized water as the main solvent can avoid volatile organic compound pollution and meet environmental protection requirements. At the same time, in the preparation process of the multifunctional binder for aluminum electrolysis, the constant temperature control of 60℃~80℃ combined with a uniform feeding rate of 2g / min~10g / min can ensure that the raw materials of the multifunctional binder for aluminum electrolysis are evenly dispersed, avoid gelation or thermal degradation, and improve the yield of finished products.

[0070] (4) Application flexibility and adaptability: It can be directly applied to metal / metal or metal / ceramic interfaces. At the same time, it can be mixed with functional powders such as alumina and silicon carbide to produce coatings with heat preservation, insulation and anti-oxidation functions.

[0071] (5) Corrosion resistance and long-term stability: The colloid generated by the hydrolysis of polyferric sulfate can passivate the metal substrate. Polyferric sulfate can also form Fe-OOCR complex with succinic acid, which improves the corrosion resistance of the adhesive layer formed by the multifunctional adhesive for aluminum electrolysis. At the same time, the propylene glycol block polyether volatilizes at high temperature to form a protective layer, thereby maintaining the bonding strength of the multifunctional adhesive for aluminum electrolysis.

[0072] (6) Significant economic benefits: The multifunctional binder for aluminum electrolysis disclosed herein has a high proportion of inorganic raw materials such as sodium silicate and sodium hydroxide, which can reduce material costs by 40% to 50% compared to a fully organic binder system. At the same time, when the multifunctional binder for aluminum electrolysis is used in aluminum electrolysis cells, the lifespan of the formed anti-oxidation coating is increased by 2 to 3 times, which can reduce the frequency of downtime maintenance.

[0073] The present disclosure is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the disclosure. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0074] Example 1

[0075] Eight parts of sodium hydroxide were added to 50 parts of deionized water at 65°C under stirring at a rate of 10 g / min. After complete dissolution, 10 parts of sodium silicate were added at a rate of 5 g / min and stirred until completely dissolved. Then, 20 parts of polyimide (CAS No.: 26023-21-2) were added at a rate of 10 g / min and dissolved until completely dissolved. Next, 8 parts of silica gel (CAS No.: 14808-60-7), 2 parts of succinic acid (CAS No.: 110-15-6), 1 part of propylene glycol block polyether (L64), 0.5 parts of nonionic polyacrylamide (CAS No.: 62649-23-4), and 0.5 parts of polyferric sulfate (CAS No.: 10028-22-5) were added sequentially and stirred until homogeneous to obtain a multifunctional binder for aluminum electrolysis.

[0076] The prepared multifunctional adhesive for aluminum electrolysis was brushed onto two clean iron sheets measuring 100mm × 50mm × 2mm. The two iron sheets were then bonded together and placed in a constant temperature drying oven at 100℃ for 1 hour. After removal, the two iron sheets were firmly bonded together with strong adhesion, achieving an adhesion grade of 0 (GB / T 9286).

[0077] Example 2

[0078] Ten parts of sodium hydroxide were added to 60 parts of deionized water at 70°C under stirring at a rate of 10 g / min. After complete dissolution, eight parts of sodium silicate were added at a rate of 5 g / min and stirred until completely dissolved. Then, ten parts of polyimide were added at a rate of 10 g / min and dissolved until completely dissolved. Next, ten parts of silica gel, one part of propylene glycol block polyether (L64), and one part of succinic acid were added sequentially, and the mixture was stirred until homogeneous to obtain a multifunctional binder for aluminum electrolysis.

[0079] The prepared multifunctional binder for aluminum electrolysis was mixed with alumina powder and mica powder in a mass ratio of 1:1:1 and stirred evenly. The mixture was then coated onto a clean ordinary aluminum alloy tank cover plate with a coating thickness of 1 mm and cured at room temperature for 2 hours.

[0080] The prepared insulated ordinary aluminum alloy tank cover plate has a smooth surface without peeling or cracking, strong bonding force, and an adhesion grade of 0 (GB / T 9286). The weight of the prepared insulated ordinary aluminum alloy tank cover plate is comparable to that of ordinary tank cover plates. After being used on aluminum electrolysis tanks, the surface temperature is equivalent to 3 / 4 of the original ordinary surface temperature, effectively reducing heat dissipation from the upper part of the aluminum electrolysis tank.

[0081] Example 3

[0082] Eight parts of sodium hydroxide were added to 40 parts of deionized water at 60°C under stirring at a rate of 10 g / min. After complete dissolution, 15 parts of sodium silicate were added at a rate of 5 g / min and stirred until completely dissolved. Then, 16 parts of polyimide were added at a rate of 10 g / min and dissolved until completely dissolved. Next, 10 parts of silica gel, 8 parts of succinic acid, and 3 parts of propylene glycol block polyether (L64) were added sequentially, and the mixture was stirred until homogeneous to obtain a multifunctional binder for aluminum electrolysis.

[0083] The prepared multifunctional binder for aluminum electrolysis was mixed with nickel powder and iron powder at a mass ratio of 2:1:1 and stirred evenly. The mixture was then coated onto a clean ordinary aluminum alloy tank cover plate with a coating thickness of 0.5 mm and cured at room temperature for 2 hours.

[0084] The prepared magnetically shielded ordinary aluminum alloy tank cover plate has a smooth surface without peeling or cracking, strong bonding force, and an adhesion grade of 0 (GB / T 9286). The weight of the prepared magnetically shielded ordinary aluminum alloy tank cover plate is comparable to that of an ordinary tank cover plate, and the magnetic field after shielding is equivalent to 1 / 16 of the original magnetic field strength, which can effectively shield the magnetic field above the aluminum electrolysis tank.

[0085] Example 4

[0086] Six parts of sodium hydroxide were added to 50 parts of deionized water at 75°C under stirring at a rate of 10 g / min. After complete dissolution, 10 parts of sodium silicate were added at a rate of 5 g / min and stirred until completely dissolved. Then, 18 parts of polyimide were added at a rate of 10 g / min and dissolved until completely dissolved. Next, 5 parts of silica gel, 5 parts of succinic acid, 5 parts of propylene glycol block polyether (L64), and 1 part of nonionic polyacrylamide were added sequentially, and the mixture was stirred until homogeneous to obtain a multifunctional binder for aluminum electrolysis.

[0087] The prepared multifunctional binder for aluminum electrolysis was mixed with alumina powder and zirconium oxide powder at a mass ratio of 10:7:3 and stirred evenly. The mixture was then coated onto a carbon block with a size of Φ35mm×20mm and a coating thickness of 1mm. The block was then placed in a constant temperature drying oven and kept at 100℃ for 0.5h.

[0088] The prepared antioxidant carbon block has a smooth surface without peeling or cracking, strong bonding force, and an adhesion grade of 0 (GB / T 9286). After the prepared antioxidant carbon block and ordinary carbon block are kept together at a high temperature of 950℃ for 24 hours, the mass loss rate of the antioxidant carbon block is only 4.9%, and the antioxidant performance is 84.1% higher than that of ordinary carbon block, effectively improving the antioxidant performance of the carbon block.

[0089] Comparative Example 1

[0090] Based on the disclosure in Example 1, the following modifications are made:

[0091] Succinic acid is not added to the multifunctional binder for aluminum electrolysis.

[0092] The prepared adhesive was brushed onto two clean iron sheets measuring 100mm × 50mm × 2mm. The two iron sheets were then bonded together and placed in a constant temperature drying oven at 100℃ for 1 hour. After removal, the two iron sheets were firmly bonded, with an adhesion grade of 1 (GB / T 9286).

[0093] Comparative Example 2

[0094] Based on the disclosure in Example 2, the following modifications are made:

[0095] Polyimide is not added to the multifunctional binder for aluminum electrolysis.

[0096] The prepared adhesive was mixed with alumina powder and mica powder in a mass ratio of 1:1:1 and stirred evenly. The mixture was then coated onto a clean ordinary aluminum alloy trough cover plate with a coating thickness of 1 mm and cured at room temperature for 2 hours.

[0097] The prepared thermal insulation aluminum alloy tank cover plate has a smooth surface without peeling or cracking, strong bonding force, and an adhesion grade of 0 (GB / T 9286). Its weight is comparable to that of ordinary tank covers. When used on an electrolytic cell, its surface temperature is equivalent to 4 / 5 of the original temperature, slightly reducing heat dissipation from the top of the electrolytic cell.

[0098] Comparative Example 3

[0099] Based on the disclosure in Example 3, the following modifications are made:

[0100] Propylene glycol block polyether is not added to the multifunctional binder for aluminum electrolysis.

[0101] The prepared adhesive was mixed with nickel powder and iron powder in a mass ratio of 2:1:1 and stirred evenly. The mixture was then coated onto a clean ordinary aluminum alloy tank cover plate with a coating thickness of 0.5 mm and cured at room temperature for 2 hours.

[0102] The prepared magnetically shielded ordinary aluminum alloy tank cover plate has blistering and peeling on its surface, with an adhesion level of 1 (GB / T 9286). Its weight is comparable to that of an ordinary tank cover plate. The magnetic field after shielding is equivalent to 1 / 12 of the original magnetic field strength, which can shield the magnetic field above the electrolytic cell.

[0103] Comparative Example 4

[0104] Based on the disclosure in Example 1, the following modifications are made:

[0105] Polyimide is not added to the multifunctional binder for aluminum electrolysis.

[0106] After mixing the binder with alumina powder and zirconium oxide powder in a mass ratio of 10:7:3, the mixture is applied to a carbon block with a size of Φ35mm×20mm and a coating thickness of 1mm. The block is then placed in a constant temperature drying oven and kept at 100℃ for 0.5h.

[0107] The prepared antioxidant carbon blocks had a smooth surface without peeling or cracking. After being kept together with ordinary carbon blocks at a high temperature of 950℃ for 24 hours, the mass loss rate was 28.3%, and the antioxidant performance was improved by 60.7% compared with ordinary carbon blocks, thus improving the antioxidant performance of the carbon blocks.

[0108] Furthermore, one or more technical solutions in the embodiments of this disclosure have at least the following technical effects or advantages:

[0109] In this embodiment of the invention, the multifunctional binder for aluminum electrolysis is prepared by a simple method, has strong adhesion, can bond metals, metals and ceramics, etc., and has low production cost.

[0110] In this embodiment, the multifunctional binder for aluminum electrolysis can effectively fill corrosion-resistant powder, heat-insulating powder, insulating powder, and magnetic shielding powder, etc., and be coated on the required parts of the electrolytic cell. It has functions such as heat dissipation prevention, insulation, oxidation resistance, and weak magnetization, promoting the efficient and energy-saving operation of the aluminum electrolytic cell, saving production costs, and improving economic benefits.

[0111] In this embodiment, the multifunctional binder for aluminum electrolysis prepared by adding functional powder has a simple and convenient coating method and can also be applied to other technical fields besides aluminum electrolysis technology, showing broad application prospects.

[0112] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multifunctional binder for aluminum electrolysis, comprising, in parts by mass, polyimide 5 to 20, sodium hydroxide 8 to 20, sodium silicate 22 to 45, solvent 40 to 60, succinic acid 0.5 to 8, and propylene glycol block polyether 0.5 to 5.

2. The multifunctional binder for aluminum electrolysis according to claim 1, wherein, Further comprising, in parts by mass, at least one of silica gel 2 to 10, non-ionic polyacrylamide 0.01 to 1, and polymeric ferric sulfate 0.01 to 1.

3. The multifunctional binder for aluminum electrolysis according to claim 1, wherein, The type of the propylene glycol block polyether comprises at least one of L35, L45, L64, and L65. 4.A method for preparing the multifunctional binder for aluminum electrolysis according to any one of claims 1 to 3, comprising: obtaining each raw material of the multifunctional binder for aluminum electrolysis; adding the sodium hydroxide, the sodium silicate, and the polyimide to the solvent with a set temperature under stirring to obtain a mixed solution; adding the succinic acid and the propylene glycol block polyether to the mixed solution to obtain the multifunctional binder for aluminum electrolysis.

5. The method of claim 4, wherein, When the succinic acid and the propylene glycol block polyether are added to the mixed solution, the silica gel, the non-ionic polyacrylamide, and the polymeric ferric sulfate are added to the mixed solution.

6. The method of claim 4, wherein, The set temperature is 60 to 80℃.

7. The method of claim 4, wherein, The feeding speed of each raw material of the multifunctional binder for aluminum electrolysis is 2 to 10 g / min. 8.Use of the multifunctional binder for aluminum electrolysis according to any one of claims 1 to 3, comprising: applying the multifunctional binder for aluminum electrolysis between metals and metals or between metals and ceramics for bonding between metals and metals or between metals and ceramics. 9.Use of the multifunctional binder for aluminum electrolysis according to any one of claims 1 to 3, comprising: mixing the multifunctional binder for aluminum electrolysis with functional powders to obtain a mixture; applying the mixture to a set position of an aluminum electrolysis cell and curing the mixture for heat preservation, insulation, oxidation resistance, and weak magnetization of the set position.

10. Use according to claim 8, wherein, The functional powders have a particle size of 0.5 to 35 μm and comprise at least one of aluminum oxide powder, aluminum silicate powder, silica aerogel powder, zirconia powder, silicon carbide powder, aluminum nitride powder, graphite powder, mica powder, nickel powder, nickel-chromium alloy powder, nickel-chromium-iron alloy powder, nickel-aluminum powder, copper powder, cobalt powder, and iron powder.

11. Use according to claim 8, wherein, The curing is normal temperature curing or heating curing; The time of the normal temperature curing is 3 h. The temperature of the heating curing is 60 to 200℃, and the time of the heating curing is 0.5 to 3 h.

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