Preparation method of high bulk density prebaked anode and application thereof

Abstract

The present application relates to the technical field of aluminum electrolysis, in particular to a preparation method of high-bulk-density prebaked anode and application thereof. The preparation method comprises: (1) mixing, (2) kneading, (3) forming and (4) baking. The modified filler is added in the kneading process, so that the bulk density can reach 1.95 g·cm ‑3 The high-bulk-density prebaked anode prepared by the present application has high bulk density, good conductivity and high voltage strength, and has great practical significance for aluminum electrolysis production.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolysis technology, and in particular to a method for preparing a high-volume-density prebaked anode and its application. Background Technology

[0002] Prebaked anodes are a crucial component of the aluminum electrolysis process, directly impacting electrolysis efficiency and product quality. Traditional prebaked anodes are primarily composed of a mixture of calcined coke and coal tar pitch. However, current technology suffers from a significant problem: the bonding strength between the calcined coke and coal tar pitch is limited. During the bonding process, insufficient interfacial interaction leads to a low bulk density in the prebaked anode, consequently affecting its conductivity and heat resistance. This lower bulk density not only reduces the anode's mechanical strength but may also cause anode disintegration and shorten its lifespan during electrolysis. This issue poses a challenge to energy consumption and production efficiency in the aluminum electrolysis industry.

[0003] Patent document CN201710003876.5 discloses an aluminum electrolysis prebaked anode and its production process. The raw materials, by weight percentage, include: 82-86% of additive components and 14%-18% of binder. The additive components, by weight percentage, include 80%-84% calcined petroleum coke, 14%-16% of residual anode material with an ash content of less than 1%, and 2%-4% of cathode milling flour generated during the processing of the aluminum electrolysis cathode. The binder includes coal tar pitch and additives, including one or more of epoxy resin, phenolic resin, furfural resin, and furan resin. This invention uses a resin-coated coal tar pitch binder to improve the bulk density of the aluminum electrolysis prebaked anode. However, the resin distribution and calcination process may lead to uneven bonding strength, thus affecting the mechanical strength and conductivity of the anode. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for preparing a prebaked anode with high bulk density and its application, so as to solve the problem that the limited bonding strength between calcined coke and coal tar pitch leads to a low bulk density of the prebaked anode.

[0005] To achieve the above objectives, the present invention provides a method for preparing a prebaked anode with high bulk density, comprising the following steps:

[0006] (1) Mixing: The calcined coke and coal tar pitch are mixed to form a mixture;

[0007] (2) Mixing: Dry the mixture at 120-130℃ for 20-24 hours, then knead for 5-10 minutes, raise the temperature to 165-170℃, add the modified filler, and continue kneading for 10-15 minutes to obtain the modified material.

[0008] (3) Molding: The modified material is placed in a mold and vibrated to form a green body;

[0009] (4) Calcination: The green blank is placed in a calcination furnace and calcined by gradient heating to obtain a prebaked anode with high bulk density;

[0010] Furthermore, the preparation method of the modifier is as follows:

[0011] S1: Graphene quantum dots are dispersed in a mixture of ethanol and deionized water, then triethoxyvinylsilane is added, and the mixture is stirred in an ice-water bath for 30-40 min. The temperature is then raised to 60-70℃, and the mixture is stirred for 1-2 h. After washing and drying, alkenylated quantum dots are obtained.

[0012] S2: Add sulfur to dimethyl sulfoxide and heat at 160-165℃ for 30-40 min. Then add alkenylated quantum dots and methoxy-polyethylene glycol-mercapto, stir for 9-10 h, filter, wash, and dry to obtain the modified filler.

[0013] Preferably, in step S1, the weight ratio of graphene quantum dots, ethanol, deionized water and triethoxyvinylsilane is 5-10:10-20:50-100:0.5-2.

[0014] Preferably, in step S2, the weight ratio of sulfur, dimethyl sulfoxide, alkenylated quantum dots and methoxy-polyethylene glycol-mercapto are 1-2:50-100:5-10:0.1-0.5.

[0015] Preferably, the preparation method of calcined coke in step (1) is as follows: the calcined petroleum coke raw material is ground and sieved, and the weight percentage of each particle size in the calcined coke after sieving is as follows: 14wt% for particles with a diameter of 6-8mm, 20wt% for particles with a diameter of 3-6mm, 40wt% for particles with a diameter of 0.05-3mm, and 26wt% for particles with a diameter less than 0.05mm.

[0016] Preferably, the coal tar pitch in step (1) is modified pitch.

[0017] Preferably, the modified asphalt has a softening point of 100-115℃, a toluene-insoluble content of 30-34wt%, a quinoline-insoluble content of 8-10wt%, a β-resin content of 20-25wt%, a coking value of 55-58wt%, and an ash content of less than 0.3wt%.

[0018] Preferably, the weight ratio of calcined coke to coal tar pitch in step (1) is 4:1.

[0019] Preferably, the weight ratio of the mixture to the modified filler in step (2) is 10:0.5-1.

[0020] Preferably, in step (3), the excitation force for vibration molding is 300-400KN, the molding temperature is 160-170℃, and the vibration time is 120-140s.

[0021] Preferably, the gradient heating calcination step (4) is as follows: the calcination furnace is heated to 650°C at a heating rate of 5°C / h, preheated for 2-3 hours, then heated to 1250°C at a heating rate of 15°C / h, held for 80-90 hours, and then cooled before being removed from the furnace.

[0022] Preferably, the weight-average molecular weight of the methoxy-polyethylene glycol-mercapto group in step S2 is 500.

[0023] Furthermore, the present invention also provides a high-volume-density prebaked anode, obtained by the above-described method for preparing a high-volume-density prebaked anode.

[0024] Furthermore, the present invention also provides an application of a high-volume-density prebaked anode in aluminum electrolysis.

[0025] The beneficial effects of this invention are:

[0026] This invention provides a prebaked anode with high bulk density, wherein a modified filler is added during the mixing process, enabling its bulk density to reach 1.95 g·cm³. -3 Furthermore, it possesses low porosity, resistivity, and high withstand voltage, which is of great practical significance for aluminum electrolysis production.

[0027] The modified filler provided by this invention is obtained by modifying graphene quantum dots with an alkenyl silane coupling agent and simultaneously grafting sulfur polymer and polyether. The sulfur polymer and polyether can synergistically change the surface properties of graphene quantum dots, enabling them to be effectively dispersed in the prebaked anode. Furthermore, the sulfur polymer can further vulcanize coal tar pitch, enhancing the interaction between graphene quantum dots and coal tar pitch, thereby increasing the bulk density of the prebaked anode and reducing porosity and resistivity. Moreover, due to the reinforcing effect of graphene quantum dots, the compressive strength of the prebaked anode is as high as 64 MPa. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0029] In the specific embodiments of this invention, the graphene quantum dots have a sheet diameter of 3-6 nm; the weight-average molecular weight of the methoxy-polyethylene glycol-thiol group is 500; the weight percentage of each particle size in the calcined coke is as follows: 14 wt% for particles with a diameter of 6-8 mm, 20 wt% for particles with a diameter of 3-6 mm, 40 wt% for particles with a diameter of 0.05-3 mm, and 26 wt% for particles with a diameter less than 0.05 mm; the softening point of the modified asphalt is 108 °C, the toluene-insoluble content is 32 wt%, the quinoline-insoluble content is 8.5 wt%, the β-resin content is 22 wt%, the coking value is 56 wt%, and the ash content is 0.2 wt%.

[0030] Preparation Example 1:

[0031] S1: Disperse 5g of graphene quantum dots in a mixture of 10g of ethanol and 50g of deionized water, then add 0.5g of triethoxyvinylsilane, stir in an ice-water bath for 30min, then heat to 60℃ and stir for 1h, wash and dry to obtain alkenylated quantum dots.

[0032] S2: Add 1g of sulfur to 50g of dimethyl sulfoxide and heat at 160℃ for 30min. Then add 5g of alkenylated quantum dots and 0.1g of methoxy-polyethylene glycol-mercapto. Stir for 9h, filter, wash, and dry to obtain the modified filler.

[0033] Preparation Example 2:

[0034] S1: Disperse 7.5g of graphene quantum dots in a mixture of 15g of ethanol and 85g of deionized water, then add 1g of triethoxyvinylsilane, stir in an ice-water bath for 35min, then heat to 65℃ and stir for 1.5h, wash and dry to obtain alkenylated quantum dots.

[0035] S2: Add 1.5g of sulfur to 80g of dimethyl sulfoxide and heat at 160℃ for 40min. Then add 7.5g of alkenylated quantum dots and 0.3g of methoxy-polyethylene glycol-mercapto. Stir for 10h, filter, wash, and dry to obtain the modified filler.

[0036] Preparation Example 3:

[0037] S1: Disperse 10g of graphene quantum dots in a mixture of 20g of ethanol and 100g of deionized water, then add 2g of triethoxyvinylsilane, stir in an ice-water bath for 40min, then heat to 70℃, stir for 2h, wash, and dry to obtain alkenylated quantum dots.

[0038] S2: Add 2g of sulfur to 100g of dimethyl sulfoxide and heat at 165℃ for 40min. Then add 10g of alkenylated quantum dots and 0.5g of methoxy-polyethylene glycol-mercapto. Stir for 10h, filter, wash, and dry to obtain the modified filler.

[0039] Preparation Example 4:

[0040] S1: Add 1.5g of sulfur to 80g of dimethyl sulfoxide and heat at 160℃ for 40min. Then add 7.5g of graphene quantum dots and 0.3g of methoxy-polyethylene glycol-mercapto, stir for 10h, filter, wash, and dry to obtain the modified filler.

[0041] Preparation Example 5:

[0042] S1: Disperse 7.5g of graphene quantum dots in a mixture of 15g of ethanol and 85g of deionized water, then add 1g of triethoxyvinylsilane, stir in an ice-water bath for 35min, then heat to 65℃ and stir for 1.5h, wash and dry to obtain alkenylated quantum dots.

[0043] S2: Add 1.5g of sulfur to 80g of dimethyl sulfoxide and heat at 160℃ for 40min. Then add 7.5g of alkenylated quantum dots, stir for 10h, filter, wash, and dry to obtain the modified filler.

[0044] Example 1:

[0045] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0046] (2) Mixing: Place 50g of the mixture at 120℃ and dry for 20h, then knead for 5min, raise the temperature to 165℃, add 2.5g of the modified filler prepared in Preparation Example 1, and continue kneading for 10min to obtain the modified material;

[0047] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 300KN, the molding temperature is 160℃, and the vibration time is 120s.

[0048] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2 hours and then heated to 1250°C at a heating rate of 15°C / h. It is held for 80 hours and then cooled to obtain a prebaked anode with high bulk density.

[0049] Example 2:

[0050] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0051] (2) Mixing: Place 50g of the mixture at 125℃ and dry for 22h, then knead for 8min, raise the temperature to 170℃, add 4g of the modified filler prepared in Preparation Example 2, and continue kneading for 12min to obtain the modified material.

[0052] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 350KN, the molding temperature is 165℃, and the vibration time is 130s.

[0053] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2.5h and then heated to 1250°C at a heating rate of 15°C / h. It is held for 85h and cooled to obtain a prebaked anode with high bulk density.

[0054] Example 3:

[0055] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0056] (2) Mixing: Place 50g of the mixture at 130℃ and dry for 24h, then mix for 10min, raise the temperature to 170℃, add 5g of the modified filler prepared in Preparation Example 3, and continue to mix for 15min to obtain the modified material.

[0057] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 400KN, the molding temperature is 170℃, and the vibration time is 140s.

[0058] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 3 hours and then heated to 1250°C at a heating rate of 15°C / h. It is held for 90 hours and then cooled to obtain a prebaked anode with high bulk density.

[0059] Comparative Example 1:

[0060] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0061] (2) Mixing: Place 50g of the mixture at 125℃ and dry for 22h, then mix for 8min, raise the temperature to 170℃, add 4g of graphene quantum dots, and continue to mix for 12min to obtain the modified material.

[0062] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 350KN, the molding temperature is 165℃, and the vibration time is 130s.

[0063] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2.5h and then heated to 1250°C at a heating rate of 15°C / h. It is held for 85h and then cooled to obtain a prebaked anode.

[0064] Comparative Example 2:

[0065] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0066] (2) Kneading: Place 50g of the mixture at 125℃ and dry for 22h, then knead for 8min, raise the temperature to 170℃, add 4g of the modified filler prepared in Preparation Example 4, and continue kneading for 12min to obtain the modified material.

[0067] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 350KN, the molding temperature is 165℃, and the vibration time is 130s.

[0068] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2.5h and then heated to 1250°C at a heating rate of 15°C / h. It is held for 85h and then cooled to obtain a prebaked anode.

[0069] Comparative Example 3:

[0070] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0071] (2) Mixing: Place 50g of the mixture at 125℃ and dry for 22h, then knead for 8min, raise the temperature to 170℃, add 4g of the modified filler prepared in Preparation Example 5, and continue kneading for 12min to obtain the modified material.

[0072] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 350KN, the molding temperature is 165℃, and the vibration time is 130s.

[0073] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2.5h and then heated to 1250°C at a heating rate of 15°C / h. It is held for 85h and then cooled to obtain a prebaked anode.

[0074] Comparative Example 4:

[0075] (1) Mixing: Mix 40g of calcined coke and 10g of modified asphalt to form a mixture;

[0076] (2) Mixing: Place 50g of the mixture at 125℃ and dry for 22h, then mix for 8min, raise the temperature to 170℃ and continue mixing for 12min to obtain the modified material;

[0077] (3) Molding: The modified material is placed in the mold and vibrated to form a green body. The vibration force is 350KN, the molding temperature is 165℃, and the vibration time is 130s.

[0078] (4) Calcination: The green blank is placed in a calcining furnace and the furnace is heated to 650°C at a heating rate of 5°C / h. It is preheated for 2.5h and then heated to 1250°C at a heating rate of 15°C / h. It is held for 85h and then cooled to obtain a prebaked anode.

[0079] Performance testing:

[0080] Bulk density: determined according to GB / T6154-1985; Porosity: determined according to YB / T 908-1978; Compressive strength: determined using a universal testing machine; Resistivity: determined using a resistivity meter; Reactivity: Air reactivity was determined using an air reactivity meter, and CO2 reactivity was determined using a CO2 reactivity meter. The results are shown in Table 1.

[0081] Table 1 Performance Test Data

[0082]

[0083]

[0084] Data Analysis:

[0085] As can be seen from the performance test data of Examples 1-3, the high-volume-density prebaked anode prepared by the present invention has a high volume density, reaching 1.95 g·cm³. -3 Furthermore, the low porosity, high bulk density, and low porosity indicate that the modified filler effectively fills the pores formed by the pyrolysis and condensation of coal tar pitch during roasting. It also has a certain reinforcing effect, enabling the compressive strength to reach over 61 MPa. It is worth mentioning that the modified filler can further reduce the resistivity.

[0086] The performance test data from Examples 2 and Comparative Examples 1-4 show that surface modification of graphene quantum dots is crucial for improving the performance of prebaked anodes, especially the increase in bulk density. Directly adding graphene quantum dots to the raw materials of prebaked anodes can increase the bulk density, mainly due to the filling effect of graphene quantum dots. After alkenylation of graphene quantum dots, polyether and sulfur polymer can be grafted onto their surface simultaneously. Polyether and sulfur polymer change the surface properties of graphene quantum dots, thereby enabling them to play a more effective filling role. Furthermore, the sulfur polymer itself can vulcanize modified asphalt, building a strong interaction between modified asphalt and graphene quantum dots, thereby further increasing the bulk density.

[0087] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for producing a high-bulk-density prebaked anode, characterized by, Includes the following steps: (1) Mixing: The calcined coke and coal tar pitch are mixed to form a mixture; (2) Mixing: Dry the mixture at 120-130℃ for 20-24 hours, then knead for 5-10 minutes, raise the temperature to 165-170℃, add the modified filler, and continue kneading for 10-15 minutes to obtain the modified material. (3) Molding: The modified material is placed in the mold and vibrated to form a green body; (4) Calcination: The green blank is placed in a calcination furnace and calcined by gradient heating to obtain a prebaked anode with high bulk density; The modified filler is prepared as follows: S1: Graphene quantum dots are dispersed in a mixture of ethanol and deionized water, then triethoxyvinylsilane is added, and the mixture is stirred in an ice-water bath for 30-40 min. The temperature is then raised to 60-70℃, and the mixture is stirred for 1-2 h. After washing and drying, alkenylated quantum dots are obtained. S2: Add sulfur to dimethyl sulfoxide and heat at 160-165℃ for 30-40 min. Then add alkenylated quantum dots and methoxy-polyethylene glycol-mercapto, stir for 9-10 h, filter, wash, and dry to obtain the modified filler. In step S1, the weight ratio of graphene quantum dots, ethanol, deionized water and triethoxyvinylsilane is 5-10:10-20:50-100:0.5-2. In step S2, the weight ratio of sulfur, dimethyl sulfoxide, alkenylated quantum dots, and methoxy-polyethylene glycol-mercapto are 1-2:50-100:5-10:0.1-0.

5.

2. The method for preparing a high-volume-density prebaked anode according to claim 1, wherein the method for preparing calcined coke in step (1) is as follows: the calcined petroleum coke raw material is ground and sieved, and the weight percentage of each particle size in the calcined coke after sieving is as follows: 14wt% for particles with a diameter of 6-8mm, 20wt% for particles with a diameter of 3-6mm, 40wt% for particles with a diameter of 0.05-3mm, and 26wt% for particles with a diameter less than 0.05mm.

3. The method for preparing a high-volume-density prebaked anode according to claim 1, wherein the coal tar pitch in step (1) is modified pitch.

4. The method of producing a high-bulk-density prebaked anode according to claim 3, characterized by, The modified asphalt has a softening point of 100-115℃, a toluene-insoluble content of 30-34wt%, a quinoline-insoluble content of 8-10wt%, a β-resin content of 20-25wt%, a coking value of 55-58wt%, and an ash content of less than 0.3wt%.

5. The method of producing a high bulk density prebaked anode according to claim 1, characterized in that, In step (1), the weight ratio of calcined coke to coal tar pitch is 4:

1.

6. The method of producing a high bulk density prebaked anode according to claim 1, characterized by, In step (2), the weight ratio of the mixture to the modified filler is 10:0.5-1.

7. The method of producing a high bulk density prebaked anode according to claim 1, characterized by, In step (3), the excitation force for vibration molding is 300-400KN, the molding temperature is 160-170℃, and the vibration time is 120-140s.

8. The method for preparing a high-bulk-density prebaked anode according to claim 1, characterized in that, The gradient heating calcination step (4) is as follows: the calcination furnace is heated to 650°C at a heating rate of 5°C / h, preheated for 2-3 hours, then heated to 1250°C at a heating rate of 15°C / h, held for 80-90 hours, and then cooled before being taken out of the furnace.

9. The method for preparing a high-bulk-density prebaked anode according to claim 1, characterized in that, In step S2, the weight-average molecular weight of the methoxy-polyethylene glycol-thiol group is 500.

10. The application of a method for preparing a high-bulk-density prebaked anode according to any one of claims 1-9, characterized in that, Used in aluminum electrolysis.

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