Method for preparing prebaked anode for aluminum electrolysis by doping with waste cathode

Abstract

This invention relates to a method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes, comprising the steps of "ball milling activation of waste cathodes – calcination activation of waste cathodes – preparation of prebaked anodes by doping waste cathodes". The waste cathodes are dried, crushed, and then dry-milled in a ball mill for activation; the milled material is calcined in a box-type resistance furnace for activation; the activated material is then mixed with petroleum coke, asphalt, and residual anodes, etc., through batching, kneading, molding, drying, and calcination to prepare the prebaked anode. Using waste cathodes as dopants to prepare prebaked anodes not only fully utilizes the carbonaceous materials within them, but also allows the electrolyte components such as aluminum fluoride, sodium fluoride, and cryolite to be returned to the electrolytic cell along with the prebaked anode, achieving self-disposal of hazardous waste. This invention does not alter the prebaked anode preparation process, has good process integration, and effectively solves the environmental hazards caused by waste cathodes, reduces the manufacturing cost of prebaked anodes, and is of great significance for energy conservation, emission reduction, comprehensive resource utilization, and environmental protection in the aluminum electrolysis industry.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization of solid waste from aluminum electrolysis, specifically involving the comprehensive utilization of waste cathodes and the preparation technology of prebaked anodes for aluminum electrolysis. Background Technology

[0002] Carbon materials are used as anodes and cathodes in aluminum electrolysis. It is the second largest consumable raw material in the production of electrolytic aluminum. Producing one ton of aluminum requires about 500 kg of prebaked anode and 30-50 kg of carbon cathode.

[0003] The main components of waste cathodes are carbon, fluoride salts and alumina. The carbon content (expressed as fixed carbon) is about 50% to 70%, and the degree of graphitization is as high as 80% to 90%. The fluoride salts are about 10% to 20%, and the main components are aluminum fluoride, sodium fluoride, cryolite, etc., and there are also 0.1% to 0.2% cyanide. It is classified as hazardous solid waste.

[0004] Currently, the main methods for treating waste cathodes include flotation, sulfuric acid hydrolysis, and direct use in the production of anode protection rings, or treatment for use in steel smelting, refractory material production, cement production, etc.

[0005] 1. Flotation method. Waste cathodes are crushed, ground, and classified. The classified material is mixed evenly with water, flotation agent, and additives and added to a flotation cell. Repeated flotation is carried out to achieve maximum separation of carbonaceous materials and electrolytes. Then, the filtrate and solid phase are obtained by filtration. The solid phase is further separated to obtain two products: one mainly composed of carbonaceous materials and the other mainly composed of electrolytes.

[0006] 2. Sulfuric acid hydrolysis method. Waste cathodes are crushed and ground, then added to a reaction vessel with a certain concentration of sulfuric acid solution for acid hydrolysis. The gas produced in the process is repeatedly washed with distilled water to recover hydrofluoric acid; the filter residue is used to produce graphite powder and industrial Al(OH)3 and alumina.

[0007] 3. Production of anode protection rings. Waste cathodes are crushed and ground into dry material, and starch is used as the binder. After the two are mixed evenly, they are directly tamped and installed on the anode steel claws through a mold, and the protective ring is formed by self-combustion.

[0008] 4. Applications in iron and steel metallurgy, building materials, and other fields. Waste cathodes are crushed, ground, and water-immersed. The carbonaceous materials in the water-immersed slag are used as a heat source for iron and steel metallurgy, or cyanide is removed through high-temperature combustion. The slag is then used for road paving, cement manufacturing, or direct landfill.

[0009] In summary, both mineral processing and sulfuric acid hydrolysis methods have drawbacks, including long and complex processes, large volumes of difficult-to-treat wastewater, severe equipment corrosion during treatment, and secondary pollution from the generated exhaust gases. Other applications essentially involve incomplete removal of harmful fluorides and cyanides through solidification or direct utilization, failing to fully utilize the electrolytes and carbonaceous materials, and not thoroughly addressing the harmless disposal and resource utilization of waste cathodes. Summary of the Invention

[0010] Based on the current research status at home and abroad and the research foundation of the research group, this invention proposes a solution to the above-mentioned bottlenecks. By ball milling and calcination activation of waste cathodes, the waste cathodes are used as additives in the prebaked anode preparation process to replace part of the fine residual anodes, thereby achieving the harmless treatment of waste cathodes.

[0011] The technical problem to be solved by this invention is to provide a method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes. This method is a way to fully utilize the carbonaceous materials and electrolytes in waste cathodes. By using waste cathodes as additives in the preparation of prebaked anodes, not only are the carbonaceous materials fully utilized, but also the aluminum fluoride, sodium fluoride, cryolite, etc., contained therein are returned to the electrolytic cell along with the prebaked anode, and enter the electrolyte as secondary resources during the aluminum electrolysis process, accompanying the anode reaction.

[0012] This invention consists of "ball milling activation of waste cathode - calcination activation of waste cathode - preparation of prebaked anode by doping of waste cathode". The waste cathode, after being dried and crushed, is activated by dry ball milling in a ball mill; the ball milled material is activated by calcination in a box-type resistance furnace; the activated material is mixed with petroleum coke, asphalt, residual anode, etc., and then mixed, shaped, dried and calcined to prepare prebaked anode.

[0013] This invention addresses the environmental hazards and resource recovery of valuable components from hazardous waste—used cathodes. It comprehensively utilizes electrolyte components such as carbon, sodium, fluorine, aluminum, and lithium, achieving "reduction, resource recovery, and harmlessness" of used cathodes. This not only effectively solves the environmental pollution caused by used cathodes but also reduces the manufacturing cost of prebaked anodes, enabling sustainable development for enterprises. It is of great significance for energy conservation, emission reduction, resource utilization, and environmental protection in the aluminum electrolysis industry.

[0014] This invention discloses a method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes, the steps of which are as follows:

[0015] (1) Dry the waste cathode at 100℃ until the water content is <5%, and crush it to <10mm.

[0016] (2) The crushed material was activated by dry ball milling using a planetary high-energy ball mill. Stearic acid was used as a ball milling aid, and the amount of stearic acid added was 5-15% of the mass of the waste cathode. The mass ratio of grinding balls to waste cathode was 5-15:1. 5mm, 10mm, and 20mm stainless steel balls were selected as grinding balls. The ball milling activation was carried out under the conditions of controlling the ball milling speed at 100-200r / min and the ball milling time at 1-3h. The particle size of the powder after ball milling activation was required to be <300 mesh.

[0017] (3) The ball milling activated material is calcined and activated in a box-type resistance furnace at a temperature of 500-800℃ for 1-4 hours.

[0018] (4) Batching ①: Batching is carried out according to the following proportions: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 1-7% activated waste cathode, and the remainder is fine residual anode. This is recorded as material A.

[0019] (5) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0020] (6) After mixing material B evenly, stir and knead at 160℃ for 35 minutes to form a uniform paste.

[0021] (7) The paste is pressed in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form a finished product. The anode sample was allowed to cool naturally to room temperature.

[0022] (8) The anode sample was calcined in a tube furnace under nitrogen protection at a temperature of 1150℃ for 32 hours.

[0023] (9) After calcination, the anode sample was naturally cooled to room temperature and then analyzed.

[0024] The advantages of this invention are: 1. Ball milling activation of waste cathodes. Under the repeated impact of the grinding media, the waste cathodes undergo collision, impact, shearing, and extrusion, resulting in fully homogenized and refined materials. Simultaneously, the carbon encapsulated in the electrolyte is completely released, which helps the carbon in the prebaked anode to play an effective role in the aluminum electrolysis process. 2. Calcination activation of waste cathodes. Thermodynamic methods are used to disrupt the composition and microstructure of the waste cathodes, increasing the contact surface and contact opportunities between them and the prebaked anode raw materials, thus improving interpenetration and uniformity. 3. Replacing fine residual anodes with waste cathodes that have undergone ball milling and calcination activation increases the carbon content in the prebaked anode, contributing to ash reduction. The advantages of ball milling activation and calcination activation of waste cathodes are illustrated in the comparative examples.

[0025] An aluminum electrolysis company with an annual production capacity of 200,000 tons of primary aluminum produces approximately 6,000-10,000 tons of waste cathodes annually, consuming about 100,000 tons of prebaked anodes. This demonstrates that by incorporating 6-10% waste cathodes into the prebaked anode preparation process, the hazardous waste can be self-disposed. Attached Figure Description

[0026] Figure 1 This is a process flow diagram used in the research process of this invention. Detailed Implementation

[0027] The specific method of this invention is as follows:

[0028] (1) Add 5-15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5-15:1. Use stainless steel balls of 5mm, 10mm and 20mm, and ball milling activation is carried out at a speed of 100-200r / min and a ball milling time of 1-3h.

[0029] (2) The ball-milled activated material is placed in a box-type resistance furnace and calcined and activated at a temperature of 500-800℃ for 1-4 hours.

[0030] (3) Ingredients ①: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 1-7% activated waste cathode, and the balance being fine residual anode. This mixture is called ingredient A.

[0031] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0032] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0033] The analytical results of the anode samples were as follows: ash content of 0.42-0.58%, and true density of 1.98-2.13 g / cm³. 3 Its bulk density is 1.51-1.58 g / cm³. 3 The resistivity is 56.71-62.88 μΩ·m, the withstand voltage is 31.1-35.8 MPa, and the air reactivity (residual) is 89.78-94.63%.

[0034] Prebaked anodes are prepared by doping waste cathodes. First, the waste cathodes are ball-milled and calcined for activation. The activated material is then mixed with petroleum coke, pitch, and residual anodes, and kneaded, shaped, dried, and calcined to form prebaked anode samples. The following, in conjunction with the accompanying drawings, provides a more detailed description of the invention, "A Method for Preparing Prebaked Anodes for Aluminum Electrolysis by Doping Waste Cathodes." The waste cathodes are waste cathodes generated from aluminum electrolysis production systems, with the following main components (wt%): C 87.06, Al 1.23, F 4.38, Na 4.57, Ca 1.02, Si 1.21, and others 0.53. The raw material consists of petroleum coke and residual anodes, with coarse coke comprising 6%, medium coke 25%, fine coke 17%, calcined petroleum coke powder 36%, coarse residual anodes 9.5%, and fine residual anodes 6.5%; the amount of pitch is 15% of the total mass of the raw material. All calculations involving the doping amount of waste cathodes are based on the total mass of the original material.

[0035] Example 1:

[0036] (1) Add 5% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5:1. Use 5mm stainless steel balls to ball mill and activate the cathode under the conditions of 100r / min rotation speed and 1h ball milling time.

[0037] (2) The ball milled activated material was placed in a box-type resistance furnace and calcined and activated at a temperature of 500℃ for 1 hour.

[0038] (3) Ingredients ①: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 1% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0039] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0040] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0041] The analytical results of the prebaked anode sample were as follows: ash content was 0.5%, and true density was 1.98 g / cm³. 3 Its bulk density is 1.51 g / cm³. 3It has a resistivity of 56.71 μΩ·m, a withstand voltage of 33.45 MPa, and an air reactivity (residual) of 90.87%.

[0042] Example 2:

[0043] (1) Add 10% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5:1. Use 15mm stainless steel balls to ball mill and activate the material at a speed of 150r / min and a time of 2h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 600℃ and a time of 4h.

[0044] (3) Ingredients ①: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 2% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0045] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0046] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0047] The analytical results of the prebaked anode sample were as follows: ash content was 0.49%, and true density was 2.06 g / cm³. 3 Its bulk density is 1.54 g / cm³. 3 It has a resistivity of 61.36 μΩ·m, a withstand voltage of 31.3 MPa, and an air reactivity (residual) of 94.63%.

[0048] Example 3:

[0049] (1) Add 15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 5mm stainless steel balls to ball mill and activate the cathode under the conditions of 200r / min rotation speed and 3h ball milling time.

[0050] (2) The ball milled activated material was placed in a box-type resistance furnace and calcined and activated at a temperature of 700℃ for 2 hours.

[0051] (3) Ingredients ①: The following ingredients are mixed: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 3% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0052] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0053] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0054] The analytical results of the prebaked anode sample were as follows: ash content was 0.53%, and true density was 2.11 g / cm³. 3 Its bulk density is 1.53 g / cm³. 3 It has a resistivity of 60.4 μΩ·m, a withstand voltage of 35.2 MPa, and an air reactivity (residual) of 91.91%.

[0055] Example 4:

[0056] (1) Add 10% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5:1. Use 15mm stainless steel balls to ball mill and activate the material at a speed of 150r / min and a time of 2h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 800℃ and a time of 3h.

[0057] (3) Ingredients ①: The following ingredients are mixed in proportion: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 4% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0058] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0059] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0060] The analytical results of the prebaked anode sample were as follows: ash content was 0.51%, and true density was 2.09 g / cm³. 3 Its bulk density is 1.56 g / cm³. 3 It has a resistivity of 62.88 μΩ·m, a withstand voltage of 34.61 MPa, and an air reactivity (residual) of 92.37%.

[0061] Example 5:

[0062] (1) Add 15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 5mm stainless steel balls to ball mill and activate the cathode under the conditions of 200r / min rotation speed and 3h ball milling time.

[0063] (2) The ball milled activated material was placed in a box-type resistance furnace and calcined and activated at a temperature of 800℃ for 3 hours.

[0064] (3) Ingredients ①: The following proportions are used to prepare the ingredients: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 5% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0065] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0066] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0067] The analytical results of the prebaked anode sample were as follows: ash content was 0.52%, and true density was 2.13 g / cm³. 3 Its bulk density is 1.52 g / cm³. 3 It has a resistivity of 61.07 μΩ·m, a withstand voltage of 31.9 MPa, and an air reactivity (residual) of 93.04%.

[0068] Example 6:

[0069] (1) Add 10% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 15:1. Use 10mm stainless steel balls and ball milling activation at a speed of 150r / min and a time of 1h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine it at a temperature of 500℃ and a time of 4h.

[0070] (3) Ingredients ①: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 6% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0071] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0072] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... Prebaked anode samples were prepared and allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis. The analytical results of the prebaked anode samples were as follows: ash content 0.58%, true density 2.09 g / cm³. 3 Its bulk density is 1.55 g / cm³. 3 It has a resistivity of 59.74 μΩ·m, a withstand voltage of 33.78 MPa, and an air reactivity (residual) of 89.78%.

[0073] Example 7:

[0074] (1) Add 15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 5mm stainless steel balls to ball mill and activate the cathode under the conditions of 200r / min rotation speed and 3h ball milling time.

[0075] (2) The ball milled activated material was placed in a box-type resistance furnace and calcined and activated at a temperature of 800℃ for 3 hours.

[0076] (3) Ingredients ①: The following ingredients are mixed: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 7% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0077] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0078] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0079] The analytical results of the prebaked anode sample were as follows: ash content was 0.49%, and true density was 2.04 g / cm³. 3 Its bulk density is 1.57 g / cm³. 3 It has a resistivity of 62.41 μΩ·m, a withstand voltage of 34.83 MPa, and an air reactivity (residual) of 92.56%.

[0080] Example 8:

[0081] (1) Add 5% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 15:1. Use 10mm stainless steel balls to ball mill and activate the material at a speed of 100r / min and a time of 1h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 700℃ and a time of 3h.

[0082] (3) Ingredients ①: The following ingredients are mixed: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 3% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0083] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0084] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0085] The analytical results of the prebaked anode sample were as follows: ash content was 0.5%, and true density was 2.12 g / cm³. 3 Its bulk density is 1.56 g / cm³. 3 It has a resistivity of 57.4 μΩ·m, a withstand voltage of 34.95 MPa, and an air reactivity (residual) of 93.22%.

[0086] Example 9:

[0087] (1) Add 10% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5:1. Use 15mm stainless steel balls to ball mill and activate the material at a speed of 150r / min and a time of 2h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 600℃ and a time of 2h.

[0088] (3) Ingredients ①: The following ingredients are mixed in proportion: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 4% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0089] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0090] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0091] The analytical results of the prebaked anode sample were as follows: ash content was 0.48%, and true density was 2.01 g / cm³. 3 Its bulk density is 1.54 g / cm³. 3 It has a resistivity of 61.85 μΩ·m, a withstand voltage of 32.62 MPa, and an air reactivity (residual) of 91.46%.

[0092] Example 10:

[0093] (1) Add 5% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 10mm stainless steel balls to ball mill and activate the material at a speed of 150r / min and a time of 2h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 700℃ and a time of 3h.

[0094] (3) Ingredients ①: The following proportions are used to prepare the ingredients: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 5% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0095] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0096] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0097] The analytical results of the prebaked anode sample were as follows: ash content was 0.49%, and true density was 2.06 g / cm³. 3 Its bulk density is 1.55 g / cm³. 3 It has a resistivity of 58.71 μΩ·m, a withstand voltage of 35.7 MPa, and an air reactivity (residual) of 93.72%.

[0098] Example 11:

[0099] (1) Add 15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 15:1. Use 15mm stainless steel balls and ball milling activation at a speed of 200r / min and a time of 3h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine it at a temperature of 800℃ and a time of 4h.

[0100] (3) Ingredients ①: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 6% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0101] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0102] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0103] The analytical results of the prebaked anode sample were as follows: ash content was 0.53%, and true density was 2.05 g / cm³. 3 Its bulk density is 1.56 g / cm³. 3 It has a resistivity of 61.93 μΩ·m, a withstand voltage of 33.79 MPa, and an air reactivity (residual) of 90.24%.

[0104] Example 12:

[0105] (1) Add 15% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 5:1. Use 5mm stainless steel balls to ball mill and activate the cathode under the conditions of 100r / min rotation speed and 1h ball milling time.

[0106] (2) The ball milled activated material was placed in a box-type resistance furnace and calcined and activated at a temperature of 500℃ for 3 hours.

[0107] (3) Ingredients ①: The following ingredients are mixed: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 7% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0108] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0109] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0110] The analytical results of the prebaked anode sample were as follows: ash content was 0.56%, and true density was 2.09 g / cm³. 3 Its bulk density is 1.58 g / cm³. 3 It has a resistivity of 60.44 μΩ·m, a withstand voltage of 35.8 MPa, and an air reactivity (residual) of 94.21%.

[0111] Comparative implementation methods for preparing prebaked anodes by doping before and after activation of waste cathodes

[0112] Comparative Example 1:

[0113] (1) After drying and crushing, the waste cathodes are sieved, and waste cathodes with a particle size of less than 1 mm are selected for batching.

[0114] (2) Ingredients ①: The following ingredients are mixed in proportion: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 5% activated waste cathode, and the remainder is fine residual anode. This is called ingredient A.

[0115] (3) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0116] (4) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were naturally cooled to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were naturally cooled to room temperature before analysis. The analytical results of the prebaked anode samples were: ash content of 0.53% and true density of 1.99 g / cm³. 3 Its bulk density is 1.52 g / cm³. 3 It has a resistivity of 61.47 μΩ·m, a withstand voltage of 33.28 MPa, and an air reactivity (residual) of 92.34%.

[0117] Comparative Example 2:

[0118] (1) Add 5% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 10mm stainless steel balls to ball mill and activate the cathode at a speed of 150r / min and a grinding time of 2h. (2) Batching ①: The following proportions are used to mix crude petroleum coke 6%, medium petroleum coke 25%, fine petroleum coke 15%, calcined petroleum coke powder 35%, crude residual anode 9%, activated waste cathode 5%, and the remainder is fine residual anode. This is recorded as material A.

[0119] (3) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0120] (4) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... Prebaked anode samples were prepared and allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis. The analytical results of the prebaked anode samples were as follows: ash content 0.52%, true density 2.02 g / cm³. 3 Its bulk density is 1.53 g / cm³. 3 It has a resistivity of 59.02 μΩ·m, a withstand voltage of 33.97 MPa, and an air reactivity (residual) of 92.55%.

[0121] Comparative Example 4:

[0122] (1) Add 5% stearic acid to the dried and crushed waste cathode. The mass ratio of grinding balls to waste cathode is 10:1. Use 10mm stainless steel balls to ball mill and activate the material at a speed of 150r / min and a time of 2h. (2) Place the ball-milled activated material in a box-type resistance furnace and calcine and activate it at a temperature of 700℃ and a time of 3h.

[0123] (3) Ingredients ①: The following proportions are used to prepare the ingredients: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 5% activated waste cathode, and the remainder is fine residual anode. This is recorded as ingredient A.

[0124] (4) Batching ②: Add asphalt to material A, the amount of which is 15% of the total mass of material A, and is denoted as material B.

[0125] (5) After mixing material B evenly, heat to 160℃ and stir and knead for 35 minutes to form a uniform paste. Press the paste in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 5 minutes to form... The prebaked anode samples were allowed to cool naturally to room temperature. The anode samples were then calcined in a nitrogen-protected tube furnace at 1150℃ for 32 hours. After calcination, the anode samples were allowed to cool naturally to room temperature before analysis and testing.

[0126] The analytical results of the prebaked anode sample were as follows: ash content was 0.53%, and true density was 2.01 g / cm³. 3 Its bulk density is 1.53 g / cm³. 3 It has a resistivity of 60.37 μΩ·m, a withstand voltage of 34.56 MPa, and an air reactivity (residual) of 92.83%.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes, characterized in that, The specific steps are as follows: (1) Dry and crush the waste cathode; (2) The crushed material was activated by dry ball milling using a planetary high-energy ball mill with stearic acid as a ball milling aid. (3) Waste cathode ball abrasive is activated by calcination in a box-type resistance furnace; (4) The activated material of the waste cathode is mixed with petroleum coke, asphalt and residual anode through batching ① and batching ②; (5) After the prepared ingredients are mixed evenly, stir and knead them into a paste. (6) The paste is pressed into anode blocks in a molding machine; the pressed anode blocks are allowed to cool naturally to room temperature; (7) The anode block is calcined in a tube furnace under nitrogen protection; (8) After calcination, the anode block was allowed to cool naturally to room temperature for analysis and testing; The waste cathodes are waste cathodes generated from the aluminum electrolysis production system, with the following main components by mass fraction: C 87.06wt%, Al 1.23wt%, F 4.38wt%, Na 4.57wt%, Ca 1.02wt%, Si 1.21wt%, and others 0.53wt%. The waste cathodes are dried at 100℃ until the water content is <5% and crushed to <10mm. Ingredients ①: The ingredients are prepared according to the following proportions: 6% crude petroleum coke, 25% medium petroleum coke, 15% fine petroleum coke, 35% calcined petroleum coke powder, 9% crude residual anode, 1-7% activated waste cathode, and the balance being fine residual anode. This is denoted as Ingredient A. Ingredient ②: Add asphalt to material A as described above, the amount of which is 15% of the total mass of material A, and denoted as material B; The calcined activated material is calcined and activated in a box-type resistance furnace at a temperature of 500~800℃ for 1~4h.

2. The method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes as described in claim 1, characterized in that, The crushed material is activated by dry ball milling using a planetary high-energy ball mill; stearic acid is used as a ball milling aid, and the amount of stearic acid added is 5-15% of the mass of the waste cathode; the mass ratio of grinding balls to waste cathode is 5-15:1; 5mm, 10mm, and 20mm stainless steel balls are selected as grinding balls; the ball milling speed is controlled at 100-200 r / min; the ball milling time is 1-3 h; and the particle size of the powder after ball milling activation is required to be <300 mesh.

3. The method for preparing prebaked anodes for aluminum electrolysis by doping waste cathodes as described in claim 1, characterized in that, After the material B is mixed evenly, it is stirred and kneaded at 160°C for 35 minutes to form a uniform paste.

4. The method of preparing a prebaked anode for aluminum electrolysis from a spent cathode doped as claimed in claim 1, characterized in that, The paste is pressed into a prebaked anode block with a diameter of φ20×30mm in a molding machine at a molding temperature of 150℃ and a pressure of 40KN for 1 minute, and then naturally cooled to room temperature.

5. The method of preparing a prebaked anode for aluminum electrolysis from a spent cathode doped as claimed in claim 1, characterized in that The prebaked anode samples were calcined in a nitrogen-protected tube furnace at a temperature of 1150℃ for 32 hours. After calcination, the prebaked anode samples were allowed to cool naturally to room temperature before analysis and testing.

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