Method for reducing the amount of aluminum dross and hazardous waste components in an aluminum electrolysis process

Abstract

The present application belongs to the technical field of hazardous waste control of aluminum electrolysis, and particularly relates to a method for reducing the amount of aluminum dross and hazardous components in the aluminum electrolysis process. Based on the whole process kinetics mechanism of heterogeneous phase induced heterogeneous nucleation, interface oxidation / nitridation reaction and high-temperature slag continuous reaction in the aluminum dross formation process, the present application controls the influencing factors in the aluminum dross formation process by using at least one of the following measures in view of the heterogeneous nucleation, interface oxidation and nitridation reaction process of aluminum dross formation in the aluminum melt out of aluminum, heat preservation and slag cooling process, so as to achieve the goal of reducing the amount of aluminum dross and hazardous components. The present application can reduce the amount of aluminum dross and AlN by more than 40%, and the amount of fluorine in the aluminum dross is reduced by 99.38% at most. The present application does not need to make large-scale modification to the existing electrolytic cell main structure, and has the advantages of simple process, low modification cost, suitability for industrial continuous promotion, and remarkable green environmental protection benefits.

Description

Technical Field

[0001] This invention belongs to the field of hazardous waste control technology in aluminum electrolysis, specifically relating to a method for reducing the volume of aluminum ash and hazardous waste components during aluminum electrolysis. Background Technology

[0002] During aluminum electrolysis production, the high-temperature molten aluminum is typically in an open or semi-open environment during processes such as tapping, heat preservation, and slag removal. This environment makes it susceptible to oxidation and nitriding reactions with oxygen and nitrogen in the air, resulting in aluminum ash. According to incomplete statistics, approximately 10-50 kg of aluminum ash is generated for every ton of primary aluminum produced. Aluminum ash not only causes significant loss of metallic aluminum but also contains harmful components such as fluorides and aluminum nitride, exhibiting leaching toxicity and reactive hazards. It has been classified as hazardous waste in my country and has become a major obstacle to the green and low-carbon development of the aluminum electrolysis industry.

[0003] For a long time, the industry has generally believed that the generation of aluminum ash from molten aluminum in an open environment is an unavoidable process, a necessary byproduct of the intrinsic oxidation reaction between molten aluminum and air, and cannot be avoided at the source. Therefore, related technological research and development has mainly focused on end-of-pipe treatment and resource utilization after aluminum ash generation. For example, pyrometallurgical or wet processes are used to reduce the content of aluminum nitride and fluorides in aluminum ash, or co-processing is used to achieve resource utilization of aluminum ash. Although such technologies can mitigate the harmfulness of aluminum ash to some extent, since they only treat aluminum ash that has already been generated, they cannot reduce the amount of aluminum ash generated at the source. Therefore, problems such as large aluminum loss, high treatment costs, and heavy pressure on hazardous waste disposal still exist. Currently, there are no reports on source reduction of aluminum ash.

[0004] In summary, existing technologies mainly focus on end-of-life treatment after aluminum ash formation, and have not yet addressed the kinetic mechanism of aluminum ash formation to achieve comprehensive and coordinated control of key processes such as heterogeneous nucleation, interfacial atmosphere, and sustained high-temperature reaction of molten slag. In particular, a stable aluminum ash reduction technology solution that can be implemented under industrial conditions is lacking. Therefore, there is an urgent need to provide a method that addresses aluminum ash formation at its source to reduce the volume of aluminum ash and its hazardous components, thereby simultaneously reducing the amount of aluminum ash generated and the content of its hazardous components. Summary of the Invention

[0005] Objective: To address the problem that existing technologies for aluminum ash mainly rely on end-of-pipe treatment and fail to reduce the amount of aluminum ash generated and the content of hazardous waste components in it at the source, this invention provides a method for reducing the amount of aluminum ash and hazardous waste components during aluminum electrolysis. This method starts from the kinetic mechanism of aluminum ash formation and controls key processes such as heterogeneous nucleation, interfacial oxidation and nitriding reactions, and the high-temperature continuous reaction of molten slag during aluminum ash formation, thereby achieving a simultaneous reduction in the amount of aluminum ash and its hazardous waste components such as fluorides and aluminum nitride.

[0006] The present invention also aims to provide a source reduction technology for aluminum ash that does not require large-scale modification of the existing electrolytic cell structure and is suitable for continuous industrial application, so as to reduce the pressure of subsequent aluminum ash disposal and environmental risks, and improve the green level of the electrolytic aluminum production process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention proposes a method for reducing the volume of aluminum ash and hazardous waste components during aluminum electrolysis. Based on the kinetic mechanism of heterogeneous nucleation induced by heterogeneous phases, interfacial oxidation / nitriding reactions, and continuous reactions of high-temperature molten slag during aluminum ash formation, this invention addresses the heterogeneous nucleation, interfacial oxidation, and nitriding reactions of aluminum ash during aluminum tapping, heat preservation, and slag cooling. At least one of the following measures is employed to control the influencing factors in the aluminum ash formation process, thereby achieving the goal of reducing the volume of aluminum ash and hazardous waste components: Measures a. Reduce the entry of heterogeneous phases into the aluminum melt, control the destructive effect of heterogeneous phases on the oxide film on the surface of the aluminum melt, and inhibit heterogeneous nucleation; Measure b. Regulate the atmosphere composition in the surface area of ​​the molten aluminum to inhibit the continuous oxidation and nitriding reactions on the surface of the molten aluminum; Measure c. Regulate the atmosphere and cooling rate in the high-temperature aluminum slag cooling environment to reduce further oxidation and nitriding reactions of aluminum carried in during slag removal.

[0008] Furthermore, the heterogeneous phase is a substance that can serve as a heterogeneous nucleation core for aluminum ash while reducing the stability of the oxide film on the surface of the aluminum melt, including one or more of electrolytes, carbon particles, and refractory material debris.

[0009] Furthermore, in measure a, a physical barrier device is installed during the aluminum tapping process to reduce the entry of heterogeneous phases into the molten aluminum.

[0010] Furthermore, the physical barrier device is a fusible structure, which maintains its structural integrity when passing through the electrolyte layer, and melts and fuses with the molten aluminum after contacting it.

[0011] Furthermore, the fusible barrier device is made of pure aluminum.

[0012] Furthermore, in measure b, a protective gas is introduced into the area above the surface of the molten aluminum to suppress oxidation and nitriding reactions on the surface of the melt.

[0013] Furthermore, the protective gas is introduced into the surface of the molten aluminum through a gas distribution device installed on the mixing furnace, holding furnace, or ladle to form a protective atmosphere covering layer.

[0014] Furthermore, the gas distribution device is distributed along the circumferential or length direction of the molten aluminum surface, and its gas distribution method is one or more combinations of annular gas distribution, strip gas distribution, and multi-point array gas distribution.

[0015] Furthermore, in measure c, the oxygen partial pressure and nitrogen partial pressure in the cooling environment are reduced by rapid cooling under negative pressure, and the aluminum slag is cooled to below 500°C at a cooling rate of not less than 30°C / min.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Achieve simultaneous reduction of aluminum ash and hazardous waste components. This invention significantly reduces the generation of aluminum ash and its hazardous waste components such as fluorides and AlN by controlling heterogeneous nucleation, interfacial oxidation and nitriding reactions, as well as the high-temperature continuous reaction of slag throughout the entire aluminum ash formation process. Industrial test results show that after adopting this invention, the yield of aluminum ash and the amount of AlN are reduced by more than 40%, and the amount of fluorine in aluminum ash is reduced by up to 99.38%.

[0017] 2. Construct a comprehensive control system for aluminum ash production. This invention breaks through the traditional end-of-pipe treatment technology path for aluminum ash. For the first time, it starts from the heterogeneous nucleation mechanism and interfacial oxidation and nitridation kinetics of aluminum ash formation, and synergistically regulates the key reaction conditions in the entire process of aluminum ash formation. It constructs a whole-process control system that combines source blocking, atmosphere control and rapid cooling to achieve source reduction of aluminum ash and hazardous waste components.

[0018] 3. Low modification cost, suitable for industrial application. This invention does not require large-scale modifications to the existing electrolytic cell structure. It only requires the addition of auxiliary structures or control devices in the aluminum tapping, heat preservation, and slag cooling stages, offering advantages such as simple structure, convenient implementation, and suitability for continuous production. Furthermore, all technical measures of this invention can be modularly configured according to existing production line conditions, facilitating its application on electrolytic aluminum production lines of varying scales and demonstrating promising industrial application prospects.

[0019] 4. Significant green and environmentally friendly benefits This invention reduces the generation of aluminum ash at its source, and simultaneously reduces the generation of hazardous components such as fluorides and AlN, effectively lowering the difficulty of subsequent aluminum ash disposal and reducing environmental risks. It also facilitates the subsequent resource utilization of aluminum ash and reduces secondary pollution problems such as ammonia and waste liquid generated during aluminum ash storage and treatment. This method aligns with the development direction of green, low-carbon, and hazardous waste reduction at the source in the electrolytic aluminum industry, and has significant environmental, economic, and social benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow of the present invention; Figure 2 A schematic diagram of the heterogeneous nucleation mechanism of aluminum ash; Figure 3The image shows the XRD pattern of aluminum ash generated before the modification of the aluminum extraction process. Figure 4 The image shows the XRD pattern of aluminum ash generated after the modification of the aluminum extraction process. Figure 5 SEM morphology and elemental surface scans of aluminum ash before modification; Figure 6 This is a SEM morphology elemental surface scan of aluminum ash after the collaborative control of the present invention. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0022] This invention, based on long-term research on the formation, disposal, and resource utilization of aluminum ash during aluminum electrolysis, reveals that the formation of aluminum ash is influenced by the coupled effects of multiple factors, including heterogeneous phases, reaction atmosphere, melt disturbance, temperature, and cooling methods. Among these, the heterogeneous phase that enters the molten aluminum during the electrolytic aluminum tapping process is a significant factor promoting aluminum ash formation. This heterogeneous phase is a substance capable of serving as a heterogeneous nucleation core for aluminum ash while simultaneously reducing the stability of the oxide film on the surface of the molten aluminum. It includes one or more of electrolytes, carbon particles, and refractory material debris. When the heterogeneous phase enters the molten aluminum, it adheres to the surface, disrupting the alumina film and exposing the molten aluminum to the surrounding atmosphere. This significantly accelerates the oxidation and nitridation kinetics on the surface of the molten aluminum, leading to the continuous formation of Al2O3 and AlN particles. Simultaneously, the heterogeneous phase acts as a heterogeneous nucleation core for Al2O3 and AlN particles, promoting the formation, growth, and aggregation of oxidation and nitridation products on their surface, ultimately forming aluminum ash. In an open, high-temperature system, the metallic aluminum entrained in the aluminum ash will further react to generate new aluminum ash. This forms a cyclical process of "oxide film damage (heterogeneous nucleation) — oxidation / nitridation reaction — aluminum ash generation," leading to the continuous generation of aluminum ash. Furthermore, during the aluminum molten metal holding process, equipment such as mixing furnaces (holding furnaces) are usually in an open or periodically open state, with the aluminum molten surface exposed to air for extended periods. This makes it prone to oxidation and nitridation reactions, causing the continuous generation of Al2O3 and AlN particles on the aluminum molten surface, which gradually accumulate into aluminum ash. During the aluminum slag cooling stage, traditional natural cooling methods keep the high-temperature aluminum slag in an oxidation and nitridation sensitive temperature zone for a long time. At this time, the metallic aluminum entrained in the slag continuously undergoes exothermic reactions with oxygen and nitrogen in the air at high temperatures. The released heat further maintains the local high-temperature environment, promoting the oxidation and nitridation reactions of aluminum, leading to the continuous generation of Al2O3 and AlN, thereby increasing the total yield of aluminum ash and the content of its hazardous components.

[0023] In summary, the formation of aluminum ash is not solely determined by the intrinsic oxidation reaction between molten aluminum and air, but is closely related to the heterogeneous phase-induced nucleation process. (See attached diagram.) Figure 2As shown, when a heterogeneous phase enters the aluminum melt, it disrupts the alumina film on the surface of the melt, exposing it to air. Simultaneously, it acts as a heterogeneous nucleation site, promoting the preferential deposition of Al₂O₃ and AlN particles on its surface. The combined effect of these two factors promotes the formation, growth, and aggregation of oxidation and nitridation products, ultimately resulting in aluminum ash.

[0024] As attached Figure 1 As shown, under the premise of existing processes, this invention addresses the key influencing factors of aluminum ash formation in the aluminum tapping, heat preservation, and slag cooling stages of aluminum electrolysis production by adopting heterogeneous phase blocking, atmosphere protection, and negative pressure rapid cooling technology measures to achieve full-process coordinated control of aluminum ash formation, thereby reducing the amount of aluminum ash and hazardous waste components.

[0025] It should also be noted that the statistical scope of "aluminum ash production" in this embodiment of the invention covers aluminum ash generated during the aluminum casting process. The aluminum ash generated in the above processes is collected and weighed daily, then divided by the daily primary aluminum production to obtain the amount of aluminum ash produced per ton of aluminum (unit: kg / t-Al). All relevant data are derived from actual weighing and operation records at the production site.

[0026] Unless otherwise specified, the process conditions in the following embodiments are conventional process conditions in the art. Meanwhile, the aluminum ash samples in the embodiments of the present invention are tested using the following methods: (1) The fluorine content in aluminum ash was determined in accordance with the standards HJ / T 299-2007 and HJ 999-2018; (2) The AlN content was determined by chemical titration according to the YS / T 1179.3-2023 standard; (3) The phase composition was analyzed by X-ray diffraction (XRD); (4) The microstructure was observed using a scanning electron microscope (SEM).

[0027] Example 1 Heterogeneous phases that enter the molten aluminum during the electrolytic aluminum tapping process not only act as heterogeneous nucleation sites, promoting aluminum ash formation, but also disrupt the stability of the oxide film on the surface of the molten aluminum, leading to continuous oxidation and nitriding reactions. (See attached image) Figure 2 As shown, heterogeneous phases entering the molten aluminum will accumulate on the surface of the molten aluminum. On the one hand, heterogeneous phases will reduce the stability of the oxide film and cause the oxide film to break down, exposing fresh molten aluminum to the air; on the other hand, heterogeneous phases can also serve as heterogeneous nucleation sites for Al2O3 and AlN particles, promoting the generation, growth and aggregation of oxidation and nitridation products on their surface, ultimately forming aluminum ash.

[0028] This embodiment is used to verify the effect of setting a fusible barrier device (measure a) in the aluminum tapping process on reducing the entry of electrolyte into the aluminum melt, reducing the production of aluminum ash and the amount of hazardous waste components generated in the aluminum ash.

[0029] 1. Process conditions An industrial trial was conducted on a 320kA prebaked anode electrolytic cell production line, producing approximately 1000 tons of primary aluminum per day. Except for the modifications described in this embodiment, all other process conditions remained consistent with the existing production process. During aluminum tapping, a fusible barrier device made of pure aluminum was installed outside the tapping tube and operated continuously for 15 days. During this period, only measure a was used; measures b and c were not combined.

[0030] The fusible barrier device in this embodiment adopts an external sealing structure, which maintains structural integrity when passing through the electrolyte layer and melts and fuses with the high-temperature molten aluminum upon contact. The following two structural forms can be referenced for details.

[0031] Method 1: Cylindrical structure The cylindrical structure is a round or square tube that matches the outer diameter of the aluminum tube. The gap between the tube and the aluminum tube is controlled at 0.5-2mm, the wall thickness is 1-4mm, and the height is >50cm. Method 2: Snap-on sealing cap The snap-on sealing plug is shaped to match the inner diameter of the bottom end of the aluminum tube, with a wall thickness of 1-5mm and a height of >2cm. This invention is not limited to the two methods described above. Any fusible barrier device that can achieve "maintaining structural integrity during passage through the electrolyte layer and melting upon contact with the molten aluminum" falls within the scope of protection of this invention. This embodiment selects the structure of method one for experimentation.

[0032] 2. Implementation Results Aluminum ash collected over 15 days was weighed and its nitrogen and fluorine content was determined. The results are shown in Table 1.

[0033] Table 1. Changes in indicators before and after the aluminum extraction process modification

[0034] The results show that by installing a fusible barrier device during the aluminum tapping process, the aluminum ash yield was reduced by 19.05%, the fluorine content in the aluminum ash was reduced by 99.24%, and the AlN content in the aluminum ash was reduced by 22.20%. (See attached...) Figure 3 With appendix Figure 4 The XRD pattern shows that the characteristic diffraction peaks of cryolite (Na3AlF6) in the modified aluminum ash disappeared. These results indicate that the fusible barrier device can effectively prevent electrolytes from entering the molten aluminum and reduce the amount of aluminum ash generated.

[0035] Example 2 This embodiment is used to verify the effect of using atmosphere protection (measure b) during the aluminum melt heat preservation stage on inhibiting the continuous oxidation and nitriding reaction on the surface of the aluminum melt, reducing the aluminum ash production and the amount of hazardous waste components generated in the aluminum ash.

[0036] 1. Process conditions An industrial trial was conducted in the same electrolytic aluminum plant mixing furnace insulation section as in Example 1. Except for the modifications implemented in this example, all other process conditions remained consistent with the existing production process. An annular gas distribution device was installed below the top of the mixing furnace. The diameter of the annular pipe of the annular gas distribution device matched the furnace opening size, and multiple gas outlets were evenly arranged along the circumference of the annular pipe. The diameter of the gas outlets was 1–3 mm, and the spacing between adjacent gas outlets was 50–150 mm, so that the protective gas could evenly cover the surface area of ​​the molten aluminum.

[0037] The protective gas in this embodiment is not limited to argon, CO2, or a mixture thereof. This embodiment preferably uses argon as the protective gas. During the heat preservation process, argon gas with a purity ≥99.99% is continuously introduced into the liquid surface area of ​​the mixing furnace, and the flow rate is controlled at 0.8 m³ / s. 3 / (h·m 2 It ran continuously for 15 days, during which only measure b was used, without the combined use of measures a and c.

[0038] 2. Implementation Results Aluminum ash collected over 15 days was weighed and its nitrogen and fluorine content was determined. The results are shown in Table 2.

[0039] Table 2 Changes in Insulation Performance Before and After Modification

[0040] The results show that after continuously introducing protective gas into the liquid surface area using an annular gas distribution device during the aluminum melt heat preservation stage, the aluminum ash production decreased by 16.19%, the fluorine content in the aluminum ash decreased by 1.17%, and the AlN content in the aluminum ash decreased by 36.45%.

[0041] Example 3 This embodiment is used to verify the effect of using negative pressure rapid cooling (measure c) in the aluminum slag cooling process on inhibiting further oxidation and nitriding reactions of aluminum slag, reducing aluminum ash production and the amount of hazardous waste components generated in aluminum ash.

[0042] 1. Process conditions An industrial trial was conducted in the slag removal section of the mixing furnace in the same electrolytic aluminum plant as in Example 1. Except for the modifications implemented in this example, all other process conditions remained consistent with the existing production process. A negative pressure rapid cooling device was installed below the slag removal port of the mixing furnace. This device included a negative pressure cooling tank, a sealed inlet / outlet mechanism, a vacuum system, a circulating cooling system, and a temperature measurement and control system. The removed high-temperature molten aluminum slag was rapidly transferred into the cooling tank. After closing the sealed door, the vacuum system was activated to control the pressure inside the tank at -0.02 to -0.06 MPa. Simultaneously, the circulating cooling system was activated to cool the molten aluminum slag to below 500°C at a cooling rate of not less than 30°C / min. The system operated continuously for 15 days, during which only measure c was used; measures a and b were not combined.

[0043] 2. Implementation Results Aluminum ash collected over 15 days was weighed and its nitrogen and fluorine content was determined. The results are shown in Table 3.

[0044] Table 3 Changes in indicators before and after the cooling system modification

[0045] The results showed that after adopting negative pressure rapid cooling, the aluminum ash production decreased by 11.43%, the fluorine content in the aluminum ash decreased by 0.88%, and the AlN content in the aluminum ash decreased by 25.76%.

[0046] Example 4 This embodiment is used to verify the effect of using a fusible barrier device (measure a), atmosphere protection (measure b), and negative pressure rapid cooling (measure c) in combination throughout the aluminum tapping, heat preservation, and slag cooling processes on the comprehensive reduction of aluminum ash and hazardous waste components.

[0047] 1. Process conditions An industrial trial was conducted at the same aluminum electrolysis plant as in Example 1, with the following technical measures employed during the production process: (1) During the aluminum tapping process, a fusible barrier device is installed at the aluminum tapping tube to reduce the entry of heterogeneous phases into the aluminum melt. The specific structure is the same as in Example 1.

[0048] (2) During the heat preservation stage of the mixing furnace, high-purity argon gas is continuously introduced into the surface area of ​​the aluminum melt to form a protective atmosphere layer above the liquid surface, so as to inhibit the continuous oxidation and nitriding reaction on the surface of the aluminum melt. The specific process parameters are the same as in Example 2.

[0049] (3) During the slag removal and cooling stage, a negative pressure rapid cooling device is used to rapidly cool down the high-temperature aluminum slag in order to reduce the continuous oxidation and nitriding reaction of aluminum entrained under high temperature conditions. The specific process parameters are as shown in Example 3.

[0050] Run continuously for 15 days. Except for the measures mentioned above, all other process conditions remain unchanged.

[0051] 2. Implementation Results Aluminum ash collected over 15 days was weighed and its nitrogen and fluorine content determined. The results are shown in Table 4. Scanning electron microscopy (SEM) was used to observe the aluminum ash obtained before and after the modification.

[0052] Table 4. Changes in Indicators Before and After the Full-Process Collaborative Transformation

[0053] The results show that by synergistically controlling the key influencing factors in the entire process of aluminum ash formation, the aluminum ash yield was reduced by 40.95%, the fluorine content in the aluminum ash was reduced by 99.38%, and the AlN content in the aluminum ash was reduced by 44.58%.

[0054] The aluminum ash obtained before and after the modification was analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results are attached. Figure 5 and attached Figure 6 As shown in the figure, before the modification, in addition to Al, O, and N elements, there were obvious Na and F enrichment regions in the aluminum ash, indicating that there were many residual electrolyte phases in the aluminum ash. After adopting the whole-process synergistic control measures of this invention, Na and F elements were basically undetectable in the aluminum ash, with only Al, O, and a small amount of N elements remaining, indicating that the electrolyte was effectively blocked and the fluoride hazardous waste component was significantly reduced.

[0055] In summary, this invention addresses three key stages in the aluminum ash formation process: heterogeneous nucleation, interfacial oxidation / nitriding reactions, and continuous reactions in the high-temperature slag. It proposes measures a (blocking heterogeneous phases), b (atmosphere protection), and c (rapid cooling under negative pressure), respectively. These measures can be implemented individually or in combination of any two or three. It is particularly noteworthy that when the three measures are combined synergistically, they complement each other in their mechanism of action: measure a blocks the nucleation triggering conditions of aluminum ash at the source; measure b inhibits continuous oxidation and nitriding during the heat preservation process; and measure c blocks the continued reaction path during the cooling stage. Each measure acts on different nodes in the aluminum ash formation chain, producing a significant synergistic effect. The industrial test results of Example 4 confirm that the synergistic combination can reduce aluminum ash yield by 40.95%, fluorine content in aluminum ash by 99.38%, and AlN content by 44.58%, with a comprehensive effect significantly better than the sum of the effects of implementing each measure individually (Examples 1-3).

[0056] This invention requires no large-scale modification to the existing electrolytic cell structure; it only requires the addition of auxiliary devices in the aluminum tapping, heat preservation, and slag cooling stages. It boasts advantages such as simple structure, low modification cost, and suitability for continuous industrial application. This method addresses the kinetic source of aluminum ash formation, achieving coordinated control of aluminum ash and its hazardous waste components throughout the entire process. This effectively reduces the pressure of subsequent aluminum ash disposal and environmental risks, aligning with the green, low-carbon development direction and hazardous waste source reduction in the electrolytic aluminum industry. It has promising industrial application prospects and significant environmental and economic benefits.

[0057] The process parameters in the above embodiments can be adjusted according to the specifications of the electrolytic cell, the amount of aluminum liquid processed, and the production conditions. Equivalent substitutions or modifications within the scope of the present invention should fall within the protection scope of the present invention.

Claims

1. A method for reducing the volume of aluminum ash and hazardous waste components during aluminum electrolysis, characterized in that, Based on the kinetic mechanism of heterogeneous nucleation induced by heterogeneous phases, interfacial oxidation / nitriding reactions, and continuous reactions of high-temperature molten slag during aluminum ash formation, at least one of the following measures is adopted to control the influencing factors in the aluminum ash formation process during aluminum tapping, heat preservation, and slag cooling, in order to achieve the goal of reducing the volume of aluminum ash and hazardous waste components: Measures a. Reduce the entry of heterogeneous phases into the aluminum melt, control the destructive effect of heterogeneous phases on the oxide film on the surface of the aluminum melt, and inhibit heterogeneous nucleation; Measure b. Regulate the atmosphere composition in the surface area of ​​the molten aluminum to inhibit the continuous oxidation and nitriding reactions on the surface of the molten aluminum; Measure c. Regulate the atmosphere and cooling rate in the high-temperature aluminum slag cooling environment to reduce further oxidation and nitriding reactions of aluminum carried in during slag removal.

2. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 1, characterized in that, The heterogeneous phase is a substance that can serve as a heterogeneous nucleation core for aluminum ash and simultaneously reduce the stability of the oxide film on the surface of the aluminum melt, including one or more of electrolytes, carbon particles, and refractory material debris.

3. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 1, characterized in that, Measure a involves setting up a physical barrier during the aluminum tapping process to reduce the entry of heterogeneous phases into the molten aluminum.

4. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 3, characterized in that, The physical barrier device is a fusible structure. The fusible barrier device maintains its structural integrity when passing through the electrolyte layer, and melts and fuses with the molten aluminum after contacting it.

5. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 4, characterized in that, The fusible barrier device is made of pure aluminum.

6. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 1, characterized in that, In measure b, a protective gas is introduced into the area above the surface of the molten aluminum to suppress oxidation and nitriding reactions on the surface of the melt.

7. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 6, characterized in that, The protective gas is introduced into the surface of the molten aluminum through a gas distribution device installed on a mixing furnace, holding furnace, or ladle to form a protective atmosphere covering layer.

8. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 7, characterized in that, The gas distribution device is distributed along the circumferential or length direction of the molten aluminum surface, and its gas distribution method is one or more combinations of annular gas distribution, strip gas distribution, and multi-point array gas distribution.

9. The method for reducing aluminum ash and hazardous waste components during aluminum electrolysis according to claim 1, characterized in that, In measure c, the oxygen and nitrogen partial pressures in the cooling environment are reduced by rapid cooling under negative pressure, and the aluminum slag is cooled to below 500°C at a cooling rate of not less than 30°C / min.

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