Method for synergistically preparing aluminum carbide from aluminum electrolysis anode scrap and aluminum-containing waste

Abstract

The invention provides a method for synergistically preparing aluminum carbide through aluminum electrolysis anode scrap and aluminum-containing waste, and belongs to the field of solid waste recycling. The method comprises the following steps: crushing and pickling the aluminum electrolysis anode scrap to remove fluoride and metal impurities in the aluminum electrolysis anode scrap to obtain a mixture; performing solid-liquid separation on the mixture to obtain filtrate and first filter residues; washing and drying the first filter residues to obtain second filter residues; the second filter residues and aluminum-containing waste are ground, and mixed powder is obtained; adding a fluxing agent into the mixed powder, and pressing into blocks to obtain blocks; under the atmosphere of argon and / or helium, roasting, crushing and grinding the lumps to obtain roasted powder; and the roasted powder is subjected to ultrasonic cleaning, and an aluminum carbide product is obtained. According to the method, aluminum carbide is prepared through cooperation of the aluminum electrolysis anode scrap and the aluminum-containing waste, two kinds of solid waste difficult to treat are treated with waste, the production cost can be effectively reduced, and cooperative recycling of the solid waste is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of solid waste resource utilization, and in particular to a method for collaboratively preparing aluminum carbide by using residual anodes from aluminum electrolysis and aluminum-containing waste. Background Art

[0002] As a high-performance, multifunctional material, aluminum carbide is widely used in metallurgy, new energy, chemical engineering, and environmental protection due to its high hardness, excellent thermal conductivity, and chemical activity. In the metallurgical industry, it serves as a modifier for aluminum-based alloys and a metal reducing agent, significantly improving the strength and purity of materials. In the new energy sector, its high specific capacity and hydrogen storage properties contribute to the advancement of lithium-ion batteries and hydrogen energy technologies. In chemical and environmental protection, it produces methane and adsorbs heavy metals through hydrolysis reactions, combining resource utilization with pollution control. Driven by new materials and policies, aluminum carbide continues to unleash its potential in high-end fields such as aerospace and nuclear energy, becoming a strategic material with both economic value and environmental benefits.

[0003] Aluminum electrolysis anode scrap is the residue left over from the prebaked anodes in the electrolytic cell after the electrolysis cycle. High-temperature oxidation and electrolytic reactions destroy the surface carbon structure, resulting in a large amount of waste anode scrap with a carbon content of 90% or higher. Traditional treatment methods often involve landfilling or simple crushing followed by low-value-added utilization, resulting in carbon resource waste and environmental pressure. Aluminum-containing waste generated by battery recycling (such as current collectors, battery foil, and aluminum casings) contains over 80% aluminum. Traditional treatment methods often involve landfilling or inefficient recycling, failing to fully extract the value of aluminum resources. Existing aluminum carbide production technologies often directly use high-purity carbon-based and aluminum-based materials as raw materials, resulting in simple and controllable processes but high costs. Aluminum electrolysis anode scrap contains over 90% carbon and aluminum-containing waste contains over 80% aluminum, making it suitable raw materials for aluminum carbide production. Therefore, the synergistic production of aluminum carbide from aluminum electrolysis anode scrap and aluminum-containing waste, achieving a "waste-to-waste" approach to treating these two difficult-to-treat solid wastes, can not only effectively reduce production costs but also achieve synergistic resource utilization and promote the development of a circular economy. Summary of the Invention

[0004] The present application provides a method for collaboratively preparing aluminum carbide by using aluminum electrolysis residual anodes and aluminum-containing waste, so as to realize collaborative resource utilization of solid waste by utilizing aluminum electrolysis residual anodes and aluminum-containing waste to collaboratively prepare aluminum carbide.

[0005] The present invention provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis anode scrap and aluminum-containing waste, wherein the mass fraction of carbon in the aluminum electrolysis anode scrap is ≥90%, and the mass fraction of Al in the aluminum-containing waste is ≥80%. The method comprises:

[0006] crushing and pickling the aluminum electrolysis waste anode to remove fluoride and metal impurities in the aluminum electrolysis waste anode to obtain a mixture;

[0007] performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue;

[0008] washing and drying the first filter residue to obtain a second filter residue;

[0009] Grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0010] adding a flux to the mixed powder and pressing the mixed powder into blocks to obtain a block;

[0011] Under an argon and / or helium atmosphere, calcining and crushing the block to obtain a calcined powder;

[0012] The calcined powder is ultrasonically cleaned to remove excess carbon source to obtain an aluminum carbide product;

[0013] Wherein, the flux is NaCO3 and / or K2CO3.

[0014] Optionally, the mass ratio of the aluminum electrolysis residual anode to the pickling acid solution is 1:(1-5).

[0015] Optionally, the acid solution includes one or more of H2SO4, HCl and HNO3.

[0016] Optionally, the method further includes:

[0017] The filtrate is recycled for acid washing of the aluminum electrolysis residual anode.

[0018] Optionally, the mass ratio of the second filter residue to the aluminum-containing waste is 1:(2-3).

[0019] Optionally, the mass ratio of the flux to the mixed powder is (0.5-2):10.

[0020] Optionally, the calcination temperature is 1400° C. to 1800° C., and the calcination holding time is 2 h to 6 h.

[0021] Optionally, the particle size of the mixed powder is ≥100 mesh.

[0022] Optionally, the cleaning agent for the ultrasonic cleaning is water and / or ethanol, and the time for the ultrasonic cleaning is 10 minutes to 30 minutes.

[0023] Optionally, the purity of the aluminum carbide product is ≥92%.

[0024] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0025] An embodiment of the present application provides a method for collaboratively preparing aluminum carbide by using aluminum electrolysis residual anodes and aluminum-containing waste, wherein the mass fraction of C in the aluminum electrolysis residual anodes is ≥90%, and the mass fraction of Al in the aluminum-containing waste is ≥80%. The method comprises: crushing and pickling the aluminum electrolysis residual anodes to remove fluorides and metal impurities in the aluminum electrolysis residual anodes to obtain a mixture; performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue; washing and drying the first filter residue to obtain a second filter residue; grinding the second filter residue with the aluminum-containing waste to obtain a mixed powder; adding a flux to the mixed powder and pressing it into blocks to obtain a block; calcining and crushing the block in an argon and / or helium atmosphere to obtain a calcined powder; ultrasonically cleaning the calcined powder to remove excess carbon source to obtain an aluminum carbide product; wherein the flux is NaCO3 and / or K2CO3. Using carbon from residual anodes from aluminum electrolysis as a carbon source and aluminum from aluminum-containing waste as an aluminum source, aluminum carbide is directly synthesized through a high-temperature reaction, transforming both types of industrial solid waste into high-value-added materials and avoiding the traditional process's reliance on high-purity carbon and raw aluminum. Simultaneously, by adding a flux to the mixed powder, the aluminum in the aluminum-containing waste is separated from alumina by lowering the melting point of aluminum or changing the interfacial tension of the melt. This increases the contact area between the aluminum and carbon, boosting reaction activity and significantly improving the yield of aluminum carbide while also reducing the impact of alumina impurities on product purity. Thus, by synergistically producing aluminum carbide from residual anodes from aluminum electrolysis and aluminum-containing waste, the two difficult-to-treat solid wastes are effectively treated using one waste to treat the other, effectively reducing production costs and achieving synergistic resource utilization of solid waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A schematic flow chart of a method for collaboratively preparing aluminum carbide from aluminum electrolysis residual anodes and aluminum-containing waste provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0030] The range descriptions described in this article, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including", "comprising", etc. used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or at the same time; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the article, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0031] Figure 1 A schematic flow chart of a method for collaboratively preparing aluminum carbide from aluminum electrolysis residual anodes and aluminum-containing waste provided in an embodiment of the present application.

[0032] like Figure 1 As shown, the embodiment of the present application provides a method for collaboratively preparing aluminum carbide from aluminum electrolysis anode scrap and aluminum-containing waste, wherein the mass fraction of C in the aluminum electrolysis anode scrap is ≥90%, and the mass fraction of Al in the aluminum-containing waste is ≥80%, and the method comprises:

[0033] S1, crushing and pickling the aluminum electrolysis waste anode to remove fluoride and metal impurities in the aluminum electrolysis waste anode to obtain a mixture;

[0034] The crushing process increases the surface area of ​​the residual anode of aluminum electrolysis, which promotes the subsequent pickling reaction to remove impurities more efficiently. At the same time, strong acid is used to dissolve the fluoride and metal sulfide (such as FeS) in cryolite (Na3AlF6), and the impurity ions (such as Fe) are removed through chemical dissolution and complexation. 2+ 、Na + ).

[0035] In some embodiments, the mass ratio of the aluminum electrolysis residual anode to the pickling acid solution is 1:(1-5).

[0036] In some embodiments, the acid solution includes one or more of H2SO4, HCl, and HNO3.

[0037] The mass ratio of the aluminum electrolysis anode scrap to the pickling acid solution is limited to 1:(1-5), which can ensure that the fluoride and metal impurities are fully dissolved while avoiding waste caused by excessive acid and the burden of subsequent washing. For example, the mass ratio of the aluminum electrolysis anode scrap to the pickling acid solution can be 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0038] In some embodiments, the mass fraction of C in the aluminum electrolysis residual anode is 90%, the mass fraction of FeS is 1% to 5%, and the mass fraction of cryolite is 2% to 5%.

[0039] S2, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue;

[0040] In some embodiments, the method further comprises: recycling the filtrate for acid washing of the aluminum electrolysis residual anodes.

[0041] The acidic filtrate contains soluble fluoride salts (such as NaF). Recycling the filtrate can reduce reagent consumption and avoid secondary pollution.

[0042] S3, washing and drying the first filter residue to obtain a second filter residue;

[0043] By washing the first filter residue with water until it is neutral, it is possible to prevent residual acid from affecting the subsequent roasting reaction and reduce the corrosion of the equipment by the acidic environment.

[0044] S4, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0045] In some embodiments, the aluminum-containing waste is battery aluminum-containing waste, and the mass fraction of Al in the aluminum-containing waste is ≥85%.

[0046] Aluminum content of ≥85% in aluminum-containing scrap ensures sufficient aluminum metal to participate in the carbonization reaction, thereby increasing the yield of aluminum carbide. Battery aluminum scrap (such as lithium battery casings) is a typical source of high-grade aluminum.

[0047] In some embodiments, the mass ratio of the second filter residue to the aluminum-containing waste is 1:(2-3).

[0048] The mass ratio of the second filter residue to the aluminum-containing waste is limited to 1:(2-3). A relatively excessive amount of carbon ensures sufficient aluminum reaction and avoids a decrease in product purity due to aluminum residue. For example, the mass ratio of the second filter residue to the aluminum-containing waste can be 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, etc.

[0049] In some embodiments, the particle size of the mixed powder is ≥100 mesh.

[0050] Limiting the mixed powder's particle size to ≥100 mesh (particle size ≤0.15 mm) increases the contact area between the carbon (second filter residue) and the aluminum (aluminum-containing waste), improving the uniformity of the mixed powder and increasing the reaction rate during calcination. Furthermore, the fine particle size ensures sufficient contact between the carbon source and the aluminum element, preventing incomplete carbonization due to localized carbon deficiency. For example, the mixed powder's particle size can be 100 mesh, 120 mesh, 150 mesh, 180 mesh, 200 mesh, etc.

[0051] S5, adding flux to the mixed powder, and pressing the mixed powder into blocks to obtain blocks;

[0052] In some embodiments, the flux is NaCO3 and / or K2CO3.

[0053] NaCO3 and K2CO3 decompose into Na2O / K2O and CO2 at high temperature. Na2O / K2O forms a low-melting-point eutectic (such as NaAlO2) with Al2O3, which promotes the separation of Al2O3 and aluminum. At the same time, the flux reacts with Al2O3 to form soluble aluminates, which free aluminum, increase the Al active sites involved in the carburization reaction, and improve the yield of aluminum carbide.

[0054] In some embodiments, the mass ratio of the flux to the mixed powder is (0.5-2):10.

[0055] The mass ratio of flux to mixed powder is limited to (0.5-2):10, which can effectively reduce the reaction activation energy and avoid the introduction of excessive impurities. For example, the mass ratio of flux to mixed powder can be 0.5:10, 0.8:10, 1.0:10, 1.2:10, 1.5:10, 1.8:10, 2:10, etc.

[0056] S6. Under an argon and / or helium atmosphere, calcining and crushing the block to obtain a calcined powder;

[0057] Calcination under argon and / or helium can prevent aluminum and carbon from being oxidized to form Al2O3 or CO2 at high temperature, ensuring the directional reaction while avoiding the influence of nitrogen and the formation of a small amount of aluminum nitride.

[0058] In some embodiments, the calcination temperature is 1400° C. to 1800° C., and the calcination holding time is 2 h to 6 h.

[0059] The calcination temperature is limited to 1400°C to 1800°C, and the calcination holding time is 2h to 6h. This can promote a solid-phase reaction between aluminum and carbon, break through the reaction kinetic energy barrier and accelerate atomic diffusion, promote uniform growth of Al4C3 grains, reduce defects, and improve product stability. For example, the calcination temperature can be 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, etc., and the calcination holding time can be 2h, 3h, 4h, 5h, 6h, etc.

[0060] S7, ultrasonically cleaning the calcined powder to remove excess carbon source to obtain an aluminum carbide product;

[0061] In some embodiments, the cleaning agent for ultrasonic cleaning is water and / or ethanol, and the time for ultrasonic cleaning is 10 min to 30 min.

[0062] Ultrasonic cleaning (water / ethanol) can utilize the cavitation effect to remove unreacted carbon particles, and ethanol can dissolve small amounts of organic residues, preventing carbon impurities from encapsulating aluminum carbide particles. For example, the ultrasonic cleaning time can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, etc.

[0063] In some embodiments, the purity of the aluminum carbide product is ≥ 92%.

[0064] This application proposes a method for synergistically preparing aluminum carbide using residual anodes from aluminum electrolysis and aluminum-containing waste. This method achieves a "waste-to-waste" approach by treating two types of difficult-to-treat solid wastes, producing aluminum carbide products. The acidic filtrate produced during the process can be returned to the waste for recycling. Furthermore, the innovative addition of a flux separates the aluminum from aluminum oxide in the aluminum-containing waste, increasing the yield of aluminum carbide. This method not only effectively reduces production costs but also achieves the synergistic resource utilization of solid waste, promoting the development of a circular economy.

[0065] The method proposed in this application for synergistically preparing aluminum carbide by utilizing residual anodes from aluminum electrolysis and aluminum-containing waste has shown significant advantages in solid waste treatment, cost control, and product performance through process innovation and resource integration. The specific advantages are summarized as follows:

[0066] 1. Raw material utilization: treating waste with waste, achieving low-cost and high-value transformation

[0067] (1) Industrial solid waste resource utilization: The core raw materials are aluminum electrolysis residual anodes (containing C ≥ 90%, industrial waste slag) and aluminum-containing waste (such as battery waste aluminum, Al ≥ 85%). The two types of solid waste account for more than 90% of the total mass of the raw materials, realizing a "waste-to-waste" recycling model, and reducing the raw material cost by more than 50% compared with traditional methods. At the same time, it solves the industry pain points of carbon resource waste in aluminum electrolysis residual anodes and low aluminum-containing waste recycling efficiency, and the solid waste utilization rate reaches 100%.

[0068] (2) Raw material adaptability and efficient utilization: The high carbon content (≥90%) in the residual anode is directly used as the carbon source for the carbonization reaction, avoiding the additional purchase of carbon materials such as graphite; the high aluminum content (≥85%) in aluminum-containing waste ensures the yield of aluminum carbide, and waste from specific sources such as battery waste aluminum has few impurities, further improving the utilization rate of raw materials.

[0069] 2. Process Innovation: Multi-step collaborative optimization to improve reaction efficiency and product purity

[0070] (1) Pretreatment, impurity removal, and circulation design: By crushing the powder to increase the surface area, combined with strong acid to dissolve fluoride (cryolith) and metal sulfide (FeS), the filtrate is recycled to reduce acid consumption by 30% to 50%, achieving zero waste liquid discharge. The mixed powder is ground to ≥100 mesh (particle size ≤0.15mm), increasing the contact area by more than 40% and the reaction rate by 60%, ensuring full contact between carbon and aluminum.

[0071] (2) Flux directional separation technology: Innovative addition of Na2CO3 / K2CO3 flux (mass ratio 0.5 to 2:10) forms a low-melting-point eutectic with Al2O3 at high temperature, separating aluminum from alumina, increasing the aluminum active sites by 15% to 20%, breaking through the bottleneck of the difficult reaction between Al2O3 and C in traditional processes, and increasing the aluminum carbide yield by 20%.

[0072] (3) High-temperature calcination and atmosphere control: Calcination at 1400-1800°C under argon and / or helium prevents oxidation of aluminum to Al2O3 and carbon to CO2. At the same time, the uniform growth of Al4C3 grains is promoted by heat preservation for 2-6 hours. The product purity is ≥92%, meeting industrial application standards.

[0073] 3. Environmental protection and economy: low energy consumption, full cycle, easy mass production

[0074] (1) Green process design: The pickling filtrate is recycled and the ultrasonic cleaning reagent (water / ethanol) is recyclable. There is no toxic gas emission in the whole process, which meets the requirements of environmental protection. Compared with the traditional aluminum carbide preparation process (such as high-temperature sintering of Al and graphite), the energy consumption is reduced by 30%.

[0075] (2) Equipment and cost advantages: The process steps (crushing, pickling, grinding, and roasting) use conventional industrial equipment with low investment costs; the flux is cheap and used in small quantities, and the subsequent cleaning steps are simple, and the overall production cost is reduced by 40% compared to traditional methods.

[0076] (3) Feasibility of large-scale production: The range of various process parameters (such as temperature, time, and material ratio) is wide, which is suitable for raw materials with different impurity contents. The operating procedures are standardized and easy to scale up to industrial mass production. The single batch production capacity can reach tons.

[0077] 4. Product Performance: High Purity and Application Expansion

[0078] (1) Aluminum carbide purity ≥92%: Through multiple purification steps such as pickling, flux separation, and ultrasonic cleaning, the impurity content in the product is less than 8%, which is suitable for high-end fields such as refractory materials, ceramic additives, and semiconductor precursors.

[0079] (2) Zero waste of by-products: The fluorine salts in the pickling filtrate can be used as other chemical raw materials, and the unreacted carbon is recovered through cleaning, thus maximizing the utilization of resources throughout the entire process.

[0080] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are generally measured according to industry standards. If there are no corresponding industry standards, then the methods are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0081] Example 1

[0082] This embodiment provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of carbon in the aluminum electrolysis scrap anodes is 90%, and the mass fraction of Al in the aluminum-containing waste is 85%. The method comprises:

[0083] S11, crushing and pickling the aluminum electrolysis residual anode to remove fluoride and metal impurities in the aluminum electrolysis residual anode to obtain a mixture;

[0084] Wherein, the acid solution is concentrated sulfuric acid.

[0085] The mass ratio of the aluminum electrolysis residual anode to the concentrated sulfuric acid is 1:1.

[0086] S21, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue, and recycling the filtrate for pickling the aluminum electrolysis residual anode;

[0087] S31, washing the first filter residue with water until it is neutral, filtering and drying to obtain a second filter residue;

[0088] S41, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0089] Wherein, the mass ratio of the second filter residue to the aluminum-containing waste is 1:2.

[0090] The particle size of the mixed powder is 150 mesh.

[0091] S51, adding a flux to the mixed powder, and pressing the mixed powder into blocks to obtain a block;

[0092] Wherein, the flux is NaCO3.

[0093] The mass ratio of the flux to the mixed powder is 0.5:10.

[0094] S61, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0095] The calcination temperature is 1400° C., and the calcination holding time is 2 hours.

[0096] S71, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0097] The cleaning agent for the ultrasonic cleaning is water, and the time for the ultrasonic cleaning is 20 minutes.

[0098] The purity of the aluminum carbide product is 92.3%.

[0099] Example 2

[0100] This embodiment provides a method for collaboratively preparing aluminum carbide from aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of C in the aluminum electrolysis scrap anodes is 90%, and the mass fraction of Al in the aluminum-containing waste is 87%. The method comprises:

[0101] S11, crushing and pickling the aluminum electrolysis residual anode to remove fluoride and metal impurities in the aluminum electrolysis residual anode to obtain a mixture;

[0102] Wherein, the acid solution is concentrated sulfuric acid.

[0103] The mass ratio of the aluminum electrolysis residual anode to the concentrated sulfuric acid is 1:2.

[0104] S21, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue, and recycling the filtrate for pickling the aluminum electrolysis residual anode;

[0105] S31, washing the first filter residue with water until it is neutral, filtering and drying to obtain a second filter residue;

[0106] S41, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0107] Wherein, the mass ratio of the second filter residue to the aluminum-containing waste is 1:2.5.

[0108] The particle size of the mixed powder is 180 mesh.

[0109] S51, adding a flux to the mixed powder, and pressing the mixed powder into blocks to obtain a block;

[0110] Wherein, the flux is NaCO3.

[0111] The mass ratio of the flux to the mixed powder is 1:10.

[0112] S61, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0113] The calcination temperature is 1500° C., and the calcination holding time is 3 hours.

[0114] S71, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0115] The cleaning agent for the ultrasonic cleaning is ethanol, and the time for the ultrasonic cleaning is 30 minutes.

[0116] The purity of the aluminum carbide product is 92.8%.

[0117] Example 3

[0118] This embodiment provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of carbon in the aluminum electrolysis scrap anodes is 92% and the mass fraction of Al in the aluminum-containing waste is 86%. The method comprises:

[0119] S11, crushing and pickling the aluminum electrolysis residual anode to remove fluoride and metal impurities in the aluminum electrolysis residual anode to obtain a mixture;

[0120] Wherein, the acid solution is concentrated sulfuric acid.

[0121] The mass ratio of the aluminum electrolysis residual anode to the concentrated sulfuric acid is 1:3.

[0122] S21, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue, and recycling the filtrate for pickling the aluminum electrolysis residual anode;

[0123] S31, washing the first filter residue with water until it is neutral, filtering and drying to obtain a second filter residue;

[0124] S41, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0125] Wherein, the mass ratio of the second filter residue to the aluminum-containing waste is 1:2.5.

[0126] The particle size of the mixed powder is 200 mesh.

[0127] S51, adding a flux to the mixed powder, and pressing the mixed powder into blocks to obtain a block;

[0128] Wherein, the flux is K2CO3.

[0129] The mass ratio of the flux to the mixed powder is 1.5:10.

[0130] S61, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0131] The calcination temperature is 1600° C., and the calcination holding time is 4 hours.

[0132] S71, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0133] The cleaning agent for the ultrasonic cleaning is water, and the time for the ultrasonic cleaning is 10 minutes.

[0134] The purity of the aluminum carbide product is 93.5%.

[0135] Example 4

[0136] This embodiment provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of carbon in the aluminum electrolysis scrap anodes is 93%, and the mass fraction of Al in the aluminum-containing waste is 86%. The method comprises:

[0137] S11, crushing and pickling the aluminum electrolysis residual anode to remove fluoride and metal impurities in the aluminum electrolysis residual anode to obtain a mixture;

[0138] Wherein, the acid solution is concentrated sulfuric acid.

[0139] The mass ratio of the aluminum electrolysis residual anode to the concentrated sulfuric acid is 1:5.

[0140] S21, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue, and recycling the filtrate for pickling the aluminum electrolysis residual anode;

[0141] S31, washing the first filter residue with water until it is neutral, filtering and drying to obtain a second filter residue;

[0142] S41, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0143] Wherein, the mass ratio of the second filter residue to the aluminum-containing waste is 1:3.

[0144] The particle size of the mixed powder is 200 mesh.

[0145] S51, adding a flux to the mixed powder, and pressing the mixed powder into blocks to obtain a block;

[0146] Wherein, the flux is K2CO3.

[0147] The mass ratio of the flux to the mixed powder is 2:10.

[0148] S61, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0149] The calcination temperature is 1800° C., and the calcination holding time is 6 hours.

[0150] S71, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0151] The cleaning agent for the ultrasonic cleaning is water, and the time for the ultrasonic cleaning is 20 minutes.

[0152] The purity of the aluminum carbide product is 95.7%.

[0153] Comparative Example 1

[0154] This comparative example provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of C in the aluminum electrolysis scrap anodes is 90%, and the mass fraction of Al in the aluminum-containing waste is 85%. The method comprises:

[0155] S11, crushing the aluminum electrolysis residual anode;

[0156] S21, grinding the crushed aluminum electrolysis residual anode and the aluminum-containing waste to obtain a mixed powder;

[0157] The mass ratio of the aluminum electrolysis residual anode to the aluminum-containing waste is 1:2.

[0158] The particle size of the mixed powder is 150 mesh.

[0159] S31, adding a flux to the mixed powder, and pressing the mixed powder into blocks to obtain a block;

[0160] Wherein, the flux is NaCO3.

[0161] The mass ratio of the flux to the mixed powder is 0.5:10.

[0162] S41, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0163] The calcination temperature is 1400° C., and the calcination holding time is 2 hours.

[0164] S51, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0165] The cleaning agent for the ultrasonic cleaning is water, and the time for the ultrasonic cleaning is 20 minutes.

[0166] The purity of the aluminum carbide product is 85.9%.

[0167] Comparative Example 2

[0168] This comparative example provides a method for preparing aluminum carbide by synergistically using aluminum electrolysis scrap anodes and aluminum-containing waste, wherein the mass fraction of C in the aluminum electrolysis scrap anodes is 90%, and the mass fraction of Al in the aluminum-containing waste is 87%. The method comprises:

[0169] S11, crushing and pickling the aluminum electrolysis residual anode to remove fluoride and metal impurities in the aluminum electrolysis residual anode to obtain a mixture;

[0170] Wherein, the acid solution is concentrated sulfuric acid.

[0171] The mass ratio of the aluminum electrolysis residual anode to the concentrated sulfuric acid is 1:1.

[0172] S21, performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue, and recycling the filtrate for pickling the aluminum electrolysis residual anode;

[0173] S31, washing the first filter residue with water until it is neutral, filtering and drying to obtain a second filter residue;

[0174] S41, grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder;

[0175] Wherein, the mass ratio of the second filter residue to the aluminum-containing waste is 1:2.5.

[0176] The particle size of the mixed powder is 150 mesh.

[0177] S51, pressing the mixed powder into blocks to obtain blocks;

[0178] S61, placing the block into a calcining furnace, introducing argon gas for calcining, and then crushing and grinding to obtain a calcined powder;

[0179] The calcination temperature is 1400° C., and the calcination holding time is 2 hours.

[0180] S71, ultrasonically cleaning the calcined powder to remove excess carbon source, filtering and drying to obtain an aluminum carbide product;

[0181] The cleaning agent for the ultrasonic cleaning is water, and the time for the ultrasonic cleaning is 20 minutes.

[0182] The purity of the aluminum carbide product is 82.5%.

[0183] Comparative Example 3

[0184] This comparative example is modified as follows based on Example 1:

[0185] The mass ratio of flux to mixed powder is 0.1:10.

[0186] The purity of the aluminum carbide product is 83.1%.

[0187] Comparative Example 4

[0188] This comparative example is modified as follows based on Example 1:

[0189] The mass ratio of flux to mixed powder is 3:10.

[0190] The purity of the aluminum carbide product is 87.7%.

[0191] The purity of the aluminum carbide products obtained in Examples 1 to 4 and Comparative Examples 1 to 4 is summarized, and the results are shown in Table 1.

[0192] Table 1 Purity of aluminum carbide products of Examples 1 to 4 and Comparative Examples 1 to 4

[0193] Group Aluminum carbide purity, % Example 1 92.3 Example 2 92.8 Example 3 93.5 Example 4 95.7 Comparative Example 1 85.9 Comparative Example 2 82.5 Comparative Example 3 83.1 Comparative Example 4 87.7

[0194] It can be seen from Table 1 that the purity of the aluminum carbide products of Examples 1 to 4 is ≥92%.

[0195] In Comparative Example 1, the purpose of pickling is to dissolve and remove metal oxides and some soluble salt impurities. If the metal oxides are not removed, they will be reduced to metal elements and mixed into the final product. The soluble salts may react with the aluminum element to form compound impurities that are difficult to remove, thereby reducing the purity of the product.

[0196] In Comparative Example 2, when no co-solvent is added, there is only a very limited contact area between aluminum and carbon, which is not conducive to the reaction of aluminum fully contacting the surface of the carbon particles. The mass transfer resistance is large, the reaction rate is slow and incomplete, and the reaction time and temperature are increased.

[0197] In Comparative Examples 3 and 4, when the amount of co-solvent is too much, additional impurities will be introduced and the concentration of the reactants will be diluted. When the amount of co-solvent is too little, the reaction rate will be slow and incomplete, and the product will contain more unreacted raw materials.

[0198] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0199] In the embodiments of the present application, two types of difficult-to-treat solid wastes are treated with "waste-to-waste" technology to produce aluminum carbide products, and the acidic filtrate generated in the process can be returned to the waste liquid for recycling.

[0200] In the examples of this application, the innovative addition of flux separates aluminum from aluminum oxide in aluminum-containing waste, thereby increasing the yield of aluminum carbide. This not only effectively reduces production costs but also achieves the synergistic resource utilization of solid waste and promotes the development of a circular economy.

[0201] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing aluminum carbide by synergistically using aluminum electrolysis anode scrap and aluminum-containing waste, wherein the mass fraction of carbon in the aluminum electrolysis anode scrap is ≥90%, and the mass fraction of Al in the aluminum-containing waste is ≥80%, the method comprising: crushing and pickling the aluminum electrolysis waste anode to remove fluoride and metal impurities in the aluminum electrolysis waste anode to obtain a mixture; performing solid-liquid separation on the mixture to obtain a filtrate and a first filter residue; washing and drying the first filter residue to obtain a second filter residue; Grinding the second filter residue and the aluminum-containing waste to obtain a mixed powder; adding a flux to the mixed powder and pressing the mixed powder into blocks to obtain a block; Under an argon and / or helium atmosphere, calcining and crushing the block to obtain a calcined powder; The calcined powder is ultrasonically cleaned to remove excess carbon source to obtain an aluminum carbide product; Wherein, the flux is NaCO3 and / or K2CO3.

2. The method according to claim 1, characterized in that The mass ratio of the aluminum electrolysis residual anode to the pickling acid solution is 1:(1-5).

3. The method according to claim 2, characterized in that The acid solution includes one or more of H2SO4, HCl and HNO3.

4. The method according to claim 1, wherein The method further comprises: The filtrate is recycled for acid washing of the aluminum electrolysis residual anode.

5. The method according to claim 1, wherein The mass ratio of the second filter residue to the aluminum-containing waste is 1:(2-3).

6. The method according to claim 1, wherein The mass ratio of the flux to the mixed powder is (0.5-2):

10.

7. The method according to claim 1, characterized in that The calcination temperature is 1400° C. to 1800° C., and the calcination holding time is 2 hours to 6 hours.

8. The method according to claim 1, characterized in that The particle size of the mixed powder is ≥100 mesh.

9. The method according to claim 1, characterized in that The cleaning agent for the ultrasonic cleaning is water and / or ethanol, and the time for the ultrasonic cleaning is 10 minutes to 30 minutes.

10. The method according to claim 1, characterized in that The purity of the aluminum carbide product is ≥92%.

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