Electrolytic aluminum prebaked anode anti-oxidation coating as well as preparation method and application thereof

Abstract

The invention relates to the field of electrolytic aluminum anti-oxidation coatings, in particular to an electrolytic aluminum prebaked anode anti-oxidation coating and a preparation method and application thereof. The anti-oxidation coating comprises 55-75 wt% of an adhesive, 15-40 wt% of a base material, 1-10 wt% of an antioxidant, 1-10 wt% of a reinforcing agent and 1-5 wt% of an additive. The anti-oxidation coating has excellent anti-oxidation performance and high temperature resistance, effectively prolongs the service life of the anode, reduces the oxidation loss, improves the electrolysis efficiency, reduces the energy consumption, has good adhesion and environmental protection characteristics, and is suitable for various aluminum electrolysis production environments. The application of the coating can remarkably improve the quality and purity of aluminum products and reduce the maintenance cost, so that the market competitiveness of enterprises is enhanced, and an innovative solution is provided for sustainable development of the aluminum smelting industry.

Description

Technical Field

[0001] The present invention relates to the field of anti-oxidation coatings for electrolytic aluminum, and particularly to an anti-oxidation coating for pre-baked anodes of electrolytic aluminum, its preparation method and application. Background Art

[0002] During the production process of electrolytic aluminum, pre-baked anodes are undoubtedly one of the most critical raw materials. Its main function is to provide the required current for the aluminum electrolysis process and bear the chemical reactions during electrolysis. Therefore, the structure of the anode not only needs to have good electrical conductivity but also withstand high temperatures and chemical corrosion. However, when the anode works in an electrolysis environment at up to 950°C, its surface will react with the electrolyte to form various oxides. This process inevitably leads to changes in the anode structure and a decline in performance. Specifically, the oxidation reaction in the transaction will consume the anode material, gradually causing it to lose electrical conductivity and stability, thus affecting the overall production efficiency of electrolytic aluminum and the quality of the final product. Therefore, it is particularly urgent and necessary to develop and apply a new type of anti-oxidation coating.

[0003] In current technological applications, although there are some anti-oxidation coatings, these coatings generally have a series of problems such as insufficient adhesion, poor high-temperature resistance, insufficient durability, and short service life. Therefore, it is urgent to develop a new type of anti-oxidation coating to improve the durability and production efficiency of pre-baked anodes and ensure the smooth progress of the aluminum electrolysis process.

[0004] During the research and development of this new anti-oxidation coating, multiple aspects were considered to ensure the improvement of its performance. First of all, the coating must be able to firmly adhere to the anode surface, with excellent adhesion, preventing peeling caused by high temperature or chemical erosion. To achieve this goal, the formulation design of the coating should adopt components that can form chemical bonds to enhance the bonding force with the anode material. At the same time, by improving the coating technology, the uniformity and thickness of the coating are increased, promoting the formation of a tight protective film. Secondly, during the production process of electrolytic aluminum, the temperature can reach up to 950 °C, so the coating material needs to have excellent high-temperature resistance to ensure its stable performance under extreme conditions. Therefore, advanced ceramic coating technology was borrowed, making the developed anti-oxidation coating not only have excellent high-temperature resistance but also effectively resist oxidation and corrosion. In addition, the service life of the anti-oxidation coating is also a factor that needs special attention. A long-lasting anti-oxidation coating can not only reduce the maintenance frequency but also reduce production interruptions and economic losses caused by frequent coating replacement. Therefore, researching new polymers or composite materials and utilizing their durability and anti-oxidation characteristics are effective ways to improve the coating life. Finally, considering the requirements of environmental protection and sustainable development, choosing non-toxic, renewable, and environmentally friendly raw materials as much as possible should be an important direction for the development of new coatings. Only by protecting the ecological environment and improving the efficiency and product quality of aluminum production can the coordinated development of technology, environment, and economy be achieved.

[0005] In summary, the pre-baked anode plays an irreplaceable role in the production of electrolytic aluminum, and the improvement of its performance is directly related to production efficiency and product quality. The deficiencies of the existing anti-oxidation coatings make the research and development of new anti-oxidation coatings extremely urgent. By improving adhesion, high-temperature resistance, and service life, and ensuring its environmental protection characteristics, it will surely be able to effectively improve the durability and production efficiency of the pre-baked anode, thus promoting the sustainable development and technological progress of the electrolytic aluminum industry. With the continuous in-depth research, these efforts will provide a solid foundation for the improvement of electrolytic aluminum production technology, helping the aluminum industry move towards a more efficient and environmentally friendly direction. Summary of the Invention

[0006] Aiming at the problems existing in the background technology, a pre-baked anode anti-oxidation coating for electrolytic aluminum, its preparation method, and application are proposed. The anti-oxidation coating of the present invention exhibits excellent anti-oxidation performance and high-temperature resistance, can effectively extend the service life of the anode, reduce oxidation loss, improve electrolysis efficiency, and reduce energy consumption.

[0007] The present invention provides an anti-oxidation coating for pre-baked anodes in electrolytic aluminum production. The formulation includes 55-75 wt% of adhesive, 15-40 wt% of matrix material, 1-10 wt% of anti-oxidant, 1-10 wt% of reinforcing agent, and 1-5 wt% of additive. The adhesive includes 40-70 wt% of sodium silicate solution, 25-50 wt% of silica sol, and 5-10% of epoxy resin. The matrix material includes 30-50 wt% of α-aluminum oxide, 20-40 wt% of potassium feldspar, 0-20 wt% of quartz, 0-20 wt% of magnesium oxide, and 0-10 wt% of zirconium oxide. The anti-oxidant includes 40-60 wt% of ammonium molybdate and 40-60 wt% of butylated hydroxytoluene. The reinforcing agent includes 0-20 wt% of glass fiber, 30-40 wt% of silicon carbide, 20-40 wt% of calcium carbonate, and 10-20 wt% of talcum powder. The additive is aluminum hydroxide.

[0008] Preferably, the formulation includes 75 wt% of adhesive, 15 wt% of matrix material, 4 wt% of anti-oxidant, 4 wt% of reinforcing agent, and 2 wt% of aluminum hydroxide. The adhesive includes 55 wt% of sodium silicate solution, 40 wt% of silica sol, and 5% of epoxy resin. The matrix material includes 30 wt% of α-aluminum oxide, 20 wt% of potassium feldspar, 20 wt% of quartz, 20 wt% of magnesium oxide, and 10 wt% of zirconium oxide. The anti-oxidant includes 40 wt% of ammonium molybdate and 60 wt% of butylated hydroxytoluene. The reinforcing agent includes 5 wt% of glass fiber, 40 wt% of silicon carbide, 35 wt% of calcium carbonate, and 20 wt% of talcum powder.

[0009] Preferably, the formulation includes 65 wt% of adhesive, 25 wt% of matrix material, 5 wt% of anti-oxidant, 4 wt% of reinforcing agent, and 1 wt% of aluminum hydroxide. The adhesive includes 65 wt% of sodium silicate solution, 25 wt% of silica sol, and 10% of epoxy resin. The matrix material includes 40 wt% of α-aluminum oxide, 40 wt% of potassium feldspar, 10 wt% of quartz, 10 wt% of magnesium oxide, and 0 wt% of zirconium oxide. The anti-oxidant includes 60 wt% of ammonium molybdate and 40 wt% of butylated hydroxytoluene. The reinforcing agent includes 10 wt% of glass fiber, 30 wt% of silicon carbide, 40 wt% of calcium carbonate, and 20 wt% of talcum powder.

[0010] Preferably, the formulation includes 55 wt% of adhesive, 32 wt% of matrix material, 10 wt% of anti-oxidant, 1 wt% of reinforcing agent, and 2 wt% of aluminum hydroxide. The adhesive includes 70 wt% of sodium silicate solution, 25 wt% of silica sol, and 5% of epoxy resin. The matrix material includes 45 wt% of α-aluminum oxide, 30 wt% of potassium feldspar, 5 wt% of quartz, 10 wt% of magnesium oxide, and 10 wt% of zirconium oxide. The anti-oxidant includes 50 wt% of ammonium molybdate and 50 wt% of butylated hydroxytoluene. The reinforcing agent includes 15 wt% of glass fiber, 35 wt% of silicon carbide, 35 wt% of calcium carbonate, and 15 wt% of talcum powder.

[0011] The present invention further provides a method for preparing an anti-oxidation coating for pre-baked anodes in electrolytic aluminum, and the steps are as follows: Prepare an adhesive and powder combination according to the above formula; Stir the mixture of the adhesive and the powder to obtain the finished coating.

[0012] The present invention further provides an application of the anti-oxidation coating for pre-baked anodes in electrolytic aluminum, and the application method is as follows: Apply the anti-oxidation coating prepared according to the above formula on the surface of the pre-baked anode.

[0013] Preferably, the curing thickness is controlled at 0.3 - 0.5 mm, and it is naturally dried for 24 h.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects: Through experimental verification, the anti-oxidation coating of the present invention has excellent anti-oxidation performance and high temperature resistance, effectively extends the service life of the anode, reduces oxidation loss, improves electrolysis efficiency, reduces energy consumption, and at the same time has good adhesion and environmental protection characteristics, and is applicable to various aluminum electrolysis production environments. The application of this coating can significantly improve the quality and purity of aluminum products, reduce maintenance costs, thereby enhancing the market competitiveness of enterprises, and providing an innovative solution for the sustainable development of the aluminum smelting industry. In addition, the formula of this coating has been optimized and designed, with good stability and controllability, can work stably under different process conditions, and is compatible with the existing production process, and is easy to be promoted and applied in large-scale production. Specific Embodiments

[0015] Example 1

[0016] This example provides an anti-oxidation coating for pre-baked anodes in electrolytic aluminum, its preparation method and application. The coating preparation includes the following steps:

[0017] S1: Prepare the anti-oxidation coating according to the formula design, and the specific steps are as follows:

[0018] S11: Prepare the adhesive: accounting for 75% of the total amount of the coating. Add the required amount of sodium silicate powder to an appropriate amount of deionized water, heat and stir at 100 °C in a single-layer glass reaction kettle for 15 h until completely dissolved to prepare a sodium silicate solution with a concentration of about 25%. Then mix 55 wt% of the sodium silicate solution and 40 wt% of the silica sol, stir at 200 r at room temperature in a single-layer glass reaction kettle for 10 h, and then add 5% of epoxy resin and stir at 200 r at room temperature for 5 h to prepare the required adhesive for standby;

[0019] S12. Prepare the powder mixture: It accounts for 25% of the total amount of the coating. Specifically, it is refined to 15wt% of the matrix material, 4wt% of the antioxidant, 4wt% of the reinforcing agent, and 2wt% of the additive in the total amount of the coating. Among them, the matrix material includes 30wt% α-aluminum oxide, 20wt% potassium feldspar, 20% quartz, 20wt% magnesium oxide, and 10wt% zirconium oxide; the antioxidant includes 40wt% ammonium molybdate and 60wt% butylated hydroxytoluene (BHT); the reinforcing agent includes 5wt% glass fiber, 40wt% silicon carbide, 35wt% calcium carbonate, and 20wt% talc powder; the additive is aluminum hydroxide; weigh them and mix them in a Raymond mill for fine grinding for 1 hour to make them fully mixed and ready for use;

[0020] S13. Place the mixture of the adhesive and the powder in a stirring kettle at room temperature and stir evenly for 1 hour to obtain the finished coating.

[0021] S2. Pretreatment of the pre-baked anode surface: Ensure that the surface of the pre-baked anode is clean and free of other impurities such as oil stains.

[0022] S3. Mix the coating: Stir the antioxidant coating evenly with a stirring paddle before use to ensure the coating is uniform;

[0023] S4. Coating: Use tools such as brushes, rollers or spray guns to apply the antioxidant coating on the anode surface. During application, it should be kept uniform to avoid the appearance of bubbles or sagging. The method of multi-layer coating can be adopted, and it should be ensured that it is dry between each layer;

[0024] S5. Drying and curing: After coating, check the integrity and performance of the coating. The thickness is controlled within 0.3 - 0.5mm. It can be used after natural drying for 24 hours.

[0025] Drying and curing test: The film-forming property of the surface of the coating after natural drying is excellent. The coating is firmly bonded to the surface of the sample. Scratch the surface of the coating with a hard object, and there is no peeling or falling off.

[0026] Calcination oxidation test: The sample with the coating is subjected to high-temperature oxidation calcination in an air atmosphere at 900°C for 10 hours. The burn-off rate is 0.05%. After calcination, the surface shows white, the coating has not fallen off, there are a small number of cracks on the surface, and the coating protection effect is good.

[0027] Example 2

[0028] This example presents an antioxidant coating for pre-baked anodes in electrolytic aluminum, its preparation method and application. The coating preparation includes the following steps:

[0029] S1. Prepare the antioxidant coating according to the formula design, as shown below:

[0030] S11. Preparation of Adhesive: It accounts for 65% of the total amount of the coating. Add the required amount of sodium silicate powder to an appropriate amount of deionized water, heat and stir it at 100 °C in a single-layer glass reactor for 15 h until it is completely dissolved to prepare a sodium silicate solution with a concentration of about 30%. Then mix 65 wt% of the sodium silicate solution and 25 wt% of silica sol, stir at room temperature at 200 r in a single-layer glass reactor for 10 h, and then add 10% epoxy resin and stir at room temperature at 200 r for 5 h to prepare the required adhesive for standby;

[0031] S12. Preparation of Powder Mixture: It accounts for 35% of the total amount of the coating. It is refined into 25 wt% of matrix material, 5 wt% of antioxidant, 4 wt% of reinforcing agent and 2 wt% of additive in the total amount of the coating. Among them, the matrix material includes 40 wt% of α-aluminum oxide, 40 wt% of potassium feldspar, 10% of quartz, 10 wt% of magnesium oxide, and 0 wt% of zirconia; the antioxidant includes 60 wt% of ammonium molybdate and 40 wt% of butylated hydroxytoluene (BHT); the reinforcing agent includes 10 wt% of glass fiber, 30 wt% of silicon carbide, 40 wt% of calcium carbonate, and 20 wt% of talc powder; the additive is aluminum hydroxide; weigh them and mix them in a Raymond mill and finely grind them for 0.5 h to make them fully mixed for standby;

[0032] S13. Place the mixture of the adhesive and the powder in a stirring kettle at room temperature and stir evenly for 2 h to obtain the finished coating.

[0033] S2. Surface Treatment of Prebaked Anode: Ensure that the surface of the prebaked anode is clean and free of other impurities such as oil stains;

[0034] S3. Mix the Coating: Stir the antioxidant coating evenly with a stirring paddle before use to ensure the uniformity of the coating;

[0035] S4. Coating: Use tools such as brushes, rollers or spray guns to apply the antioxidant coating on the surface of the anode. During coating, it should be kept uniform to avoid the appearance of bubbles or sagging. The multi-layer coating method can be adopted, and it should be ensured to be dry between each layer;

[0036] S5. Drying and Curing: After coating, check the integrity and performance of the coating. The thickness is controlled at 0.3 - 0.5 mm, and it can be used after natural drying for 24 h.

[0037] Drying and Curing Test: The film-forming property of the surface of the coating after natural drying is excellent, the coating is firmly bonded to the surface of the sample, and when the surface of the coating is scratched with a hard object, there is no peeling or falling off.

[0038] Calcination Oxidation Test: The sample with the coating is subjected to high-temperature oxidation calcination in an air atmosphere at 900 °C for 10 h. The burning loss rate is 0.07%. After calcination, the surface shows white, the coating has not fallen off, there are a small number of cracks on the surface, and the coating protection effect is good.

[0039] Example 3

[0040] This example presents an anti-oxidation coating for pre-baked anodes in electrolytic aluminum, its preparation method and application. The coating preparation includes the following steps:

[0041] S1. Prepare the anti-oxidation coating according to the formulation design, specifically as follows:

[0042] S11. Prepare the adhesive: accounting for 55% of the total coating amount. Add the required amount of sodium silicate powder to an appropriate amount of deionized water, heat and stir at 100°C in a single-layer glass reactor for 15 h until completely dissolved to prepare a sodium silicate solution with a concentration of about 30%. Then mix 70 wt% of the sodium silicate solution and 25 wt% of silica sol, stir at room temperature at 200 r in a single-layer glass reactor for 10 h, and then add 5% epoxy resin and stir at room temperature at 200 r for 5 h to prepare the required adhesive for standby;

[0043] S12. Prepare the powder combination: accounting for 45% of the total coating amount. It is refined into 32 wt% of the matrix material, 10 wt% of the anti-oxidant, 1 wt% of the reinforcing agent, and 2 wt% of the additive in the total coating amount. Among them, the matrix material includes 45 wt% α-aluminum oxide, 30 wt% potassium feldspar, 5% quartz, 10 wt% magnesium oxide, 10 wt% zirconium oxide; the anti-oxidant includes 50 wt% ammonium molybdate, 50 wt% butylated hydroxytoluene (BHT); the reinforcing agent includes 5 wt% glass fiber, 40 wt% silicon carbide, 40 wt% calcium carbonate, 15 wt% talc powder; the additive is aluminum hydroxide; weigh them and mix them in a Raymond mill and grind them finely for 1 h to make them fully mixed for standby;

[0044] S13. Place the mixture of the adhesive and the powder in a stirring kettle at room temperature and stir evenly for 2 h to obtain the finished coating.

[0045] S2. Surface treatment of the pre-baked anode: Ensure that the surface of the pre-baked anode is clean and free of other impurities such as oil stains;

[0046] S3. Mix the coating: Stir the anti-oxidation coating evenly with a stirring paddle before use to ensure the coating is uniform;

[0047] S4. Apply: Use tools such as brushes, rollers or spray guns to apply the anti-oxidation coating on the anode surface. During application, it should be kept uniform to avoid the appearance of bubbles or sagging. The multi-layer application method can be adopted, and drying should be ensured between each layer;

[0048] S5. Drying and curing: After application, check the integrity and performance of the coating. The thickness is controlled at 0.3 - 0.5 mm, and it can be used after natural drying for 24 h.

[0049] Drying and curing test: After natural drying, the film-forming property of the coating surface is excellent, and the coating is firmly bonded to the sample surface. When the coating surface is scratched with a hard object, there is no peeling or falling off.

[0050] Calcination oxidation test: The sample coated with the coating is calcined at high temperature in an air atmosphere at 900 °C for 10 h, and the burn-off rate is 0.1%. After calcination, the surface shows white, the coating has not fallen off, there are a small number of cracks on the surface, and the coating protection effect is good.

[0051] The results show that: The anti-oxidation coating of the present invention exhibits excellent anti-oxidation performance and high temperature resistance, can effectively extend the service life of the anode, reduce oxidation loss, improve electrolysis efficiency and reduce energy consumption. In addition, the coating has good adhesion and environmental protection characteristics, and is suitable for various aluminum electrolysis production environments. Its application significantly improves the quality and purity of aluminum products, while reducing maintenance costs, thereby enhancing the market competitiveness of enterprises and providing an innovative solution for the sustainable development of the aluminum smelting industry.

[0052] In addition, the formula is optimized and designed, with good stability and controllability, can operate stably under different process conditions, and is compatible with the existing production process, which is convenient for popularization and application in large-scale production. The above has made a detailed description of the implementation manner of the present invention, but the present invention is not limited thereto. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the purpose of the present invention.

Claims

1. An anti-oxidation coating for prebaked anode of electrolytic aluminum, characterized in that: The ratio includes 55-75wt% adhesive, 15-40wt% base material, 1-10wt% antioxidant, 1-10wt% reinforcing agent and 1-5wt% additive; The adhesive comprises 40-70wt% sodium silicate solution, 25-50wt% silica sol, and 5-10% epoxy resin; The matrix material comprises 30-50wt% α-alumina, 20-40wt% potassium feldspar, 0-20wt% quartz, 0-20wt% magnesium oxide, and 0-10wt% zirconium oxide; The antioxidant comprises 40-60 wt% of ammonium molybdate and 40-60 wt% of butylated hydroxytoluene; The reinforcing agent comprises 0-20wt% glass fiber, 30-40wt% silicon carbide, 20-40wt% calcium carbonate, and 10-20wt% talc; The additive is aluminum hydroxide.

2. The electrolytic aluminum prebaked anode anti-oxidation coating according to claim 1, characterized in that: The ratio includes 75wt% adhesive, 15wt% matrix material, 4wt% antioxidant, 4wt% reinforcing agent and 2wt% aluminum hydroxide; wherein the adhesive includes 55wt% sodium silicate solution, 40wt% silica sol and 5% epoxy resin; the matrix material includes 30wt% α-alumina, 20wt% potassium feldspar, 20wt% quartz, 20wt% magnesium oxide and 10wt% zirconium oxide; the antioxidant includes 40wt% ammonium molybdate and 60wt% butylated hydroxytoluene; the reinforcing agent includes 5wt% glass fiber, 40wt% silicon carbide, 35wt% calcium carbonate and 20wt% talc.

3. The electrolytic aluminum prebaked anode anti-oxidation coating according to claim 1, characterized in that: The ratio includes 65wt% adhesive, 25wt% matrix material, 5wt% antioxidant, 4wt% reinforcing agent and 1wt% aluminum hydroxide; wherein the adhesive includes 65wt% sodium silicate solution, 25wt% silica sol and 10% epoxy resin; the matrix material includes 40wt% α-alumina, 40wt% potassium feldspar, 10wt% quartz, 10wt% magnesium oxide and 0wt% zirconium oxide; the antioxidant includes 60wt% ammonium molybdate and 40wt% butylated hydroxytoluene; the reinforcing agent includes 10wt% glass fiber, 30wt% silicon carbide, 40wt% calcium carbonate and 20wt% talc.

4. The anti-oxidation coating for prebaked anode of electrolytic aluminum according to claim 1, characterized in that: The ratio includes 55wt% adhesive, 32wt% matrix material, 10wt% antioxidant, 1wt% reinforcing agent and 2% aluminum hydroxide; wherein the adhesive includes 70wt% sodium silicate solution, 25wt% silica sol and 5% epoxy resin; the matrix material includes 45wt% α-alumina, 30wt% potassium feldspar, 5wt% quartz, 10wt% magnesium oxide and 10wt% zirconium oxide; the antioxidant includes 50wt% ammonium molybdate and 50wt% butylated hydroxytoluene; the reinforcing agent includes 15wt% glass fiber, 35wt% silicon carbide, 35wt% calcium carbonate and 15wt% talc.

5. A method for preparing an anti-oxidation coating for a prebaked anode of electrolytic aluminum, characterized in that: The steps are as follows: preparing an adhesive and powder combination material according to the formula in claim 1; and stirring the mixture of the adhesive and the powder to obtain a finished coating.

6. Application of anti-oxidation coating for prebaked anode of electrolytic aluminum, characterized in that: The application method is as follows: applying the anti-oxidation coating prepared according to the formula in claim 1 on the surface of the prebaked anode.

7. The use of the anti-oxidation coating for prebaked anode of electrolytic aluminum according to claim 6, characterized in that: The curing thickness is controlled at 0.3-0.5mm and dried naturally for 24 hours.