Multi-process coupling recovery method for die-casting aluminum dross

Abstract

This invention discloses a multi-process coupled recycling method for die-cast aluminum ash, including the following steps: S1, pretreatment: The die-cast aluminum ash is crushed, graded and screened, magnetically separated for impurity removal, and dried and degassed at low temperature in sequence to obtain graded pretreated aluminum ash. The grading and screening separates the die-cast aluminum ash into coarse aluminum ash with a particle size > 5 mm, medium aluminum ash with a particle size of 1 mm-5 mm, and fine powder aluminum ash with a particle size < 1 mm. The magnetic separation for impurity removal uses a permanent magnet separator to separate ferromagnetic impurities, with an iron impurity removal rate ≥ 99%. The low temperature closed-loop drying and degassed temperature is controlled at 80℃-120℃. This invention integrates multiple processes, including physical pretreatment, short-process pyrometallurgical treatment, high-temperature melting, full-scale wet processing, and high-value utilization of tailings, to perform targeted graded treatment on die-cast aluminum ash with different particle sizes and metal contents. This achieves the resource utilization of all components, including metallic aluminum, alumina, salt components, and ammonium salts. The recovery rate of metallic aluminum exceeds 98%, the hydrolysis rate of aluminum nitride exceeds 95%, the recovery rate of salt components exceeds 98%, the deammoniation rate is ≥99%, and no secondary solid waste is generated.

Description

Technical Field

[0001] This invention belongs to the field of hazardous solid waste recycling and treatment technology, and particularly relates to a multi-process coupled recycling method for die-cast aluminum ash. Background Technology

[0002] Die-cast aluminum ash is a typical hazardous solid waste (HW48) generated during the die-casting production process. Its composition is complex, containing recyclable resources such as metallic aluminum and alumina, as well as harmful components such as aluminum nitride and fluorides. If it is piled up indiscriminately or improperly disposed of, it can easily cause soil and water pollution and lead to a serious waste of aluminum resources.

[0003] In existing technologies, combining physical separation with single pyrometallurgical or wet processes still suffers from low process coupling, low resource utilization, and incomplete removal of harmful substances. Some aluminum ash treatment methods only employ magnetic separation and pyrometallurgical melting, failing to utilize fine aluminum ash through wet processes, leading to resource waste. Some wet processes do not incorporate short-process pyrometallurgical technology, resulting in low aluminum recovery efficiency and high processing costs due to non-recycling of reagents. Therefore, a multi-process coupled recycling method for die-casting aluminum ash is urgently needed. Summary of the Invention

[0004] To address the problems in the prior art, the present invention proposes the following technical solution: A multi-process coupled recycling method for die-cast aluminum ash includes the following steps: S1. Pretreatment: The die-cast aluminum ash is crushed, graded and screened, magnetically separated to remove impurities, and then dried and degassed at low temperature in sequence to obtain graded pretreated aluminum ash. The grading and screening separates the die-cast aluminum ash into coarse particles with a particle size >5mm, medium particles with a particle size of 1mm-5mm, and fine powder aluminum ash with a particle size <1mm. The magnetic separation uses a permanent magnet separator to separate ferromagnetic impurities, with an iron impurity removal rate ≥99%. The low temperature closed-loop drying and degassed temperature is controlled at 80℃-120℃ to remove moisture while collecting trace amounts of harmful gases that escape, preventing secondary pollution. S2, Pyrometallurgical Co-processing Recycling: Coarse aluminum ash particles with a diameter >5mm from S1 are fed into a rotary kiln for a short-process pyrometallurgical reaction. Industrial waste alkali is added as a co-reactant. The reaction temperature is controlled at 850℃-950℃ using precise temperature control technology in the rotary kiln, achieving the recycling of aluminum and sodium resources. The recovery rate of flue dust and salt is ≥99%. The recovered aluminum is directly returned to the die casting process for reuse. Medium-sized aluminum ash particles with a diameter of 1mm-5mm are subjected to high-temperature melting treatment. After crushing and impurity removal, a low-melting-point eutectic is formed at 1000℃-1100℃, achieving phase separation of metal and impurities. The energy consumption of the melting process is reduced by more than 25% compared with traditional technology. S3, wet full-scale utilization: Fine aluminum ash with a particle size <1mm from S1 and residues after pyrometallurgical treatment are subjected to wet reaction. First, the aluminum ash is washed with water to remove ammonia and pretreated by sieving. Then, alkaline solution is added for wet hydrolysis. The hydrolysis temperature is controlled at 70℃-90℃ to ensure that the hydrolysis rate of active components such as aluminum nitride is ≥95%. The combustible gas, ammonia and hydrogen released during the process are recovered in stages. The salt components are separated and the recovery rate is ≥98%. For wet reaction liquid with more impurities, an acid dissolution-sedimentation assisted process is used. After the acid dissolves the alumina, the impurities are removed by sedimentation to prepare polyaluminum sulfate and aluminum hydroxide products. The metallic aluminum content in the residue is reduced to below 2%. S4. High-value transformation of tailings: The tailings after wet treatment in S3 are tested. If the tailings meet the standards, they can be used directly as cement admixtures and roadbed fillers. If the tailings contain trace pollutants, they can be mixed with slag and fly ash to prepare cementitious materials through alkali activation and solidification technology. At the same time, the alumina component in the tailings is used to prepare magnesium aluminum spinel refractory materials, which are suitable for the production of refractory parts for die casting molds.

[0005] As a preferred option of the above technical solutions, the S2 rotary kiln precision temperature control technology adopts a segmented temperature control mode, with the kiln head temperature controlled at 900-950℃, the kiln middle temperature controlled at 850-900℃, and the kiln tail temperature controlled at 800-850℃, so as to achieve a full synergistic reaction between die-cast aluminum ash and industrial waste alkali and avoid the release of harmful gases when aluminum ash comes into contact with water.

[0006] As a preferred embodiment of the above technical solution, the mixing mass ratio of coarse aluminum ash with a particle size > 5 mm in S2 to industrial waste alkali is 3-5:1, and the rotation speed of the rotary kiln is controlled at 0.8 r / min-1.2 r / min, with the material residence time in the kiln being 2h-3h, to ensure that the material and the reactant are in full contact and react.

[0007] As a preferred embodiment of the above technical solution, the alkaline solution in S3 is a sodium hydroxide solution with a mass concentration of 20%-30%, and the acid solution used in the acid dissolution-sedimentation auxiliary process is dilute sulfuric acid with a mass concentration of 15%-20%. Both the alkaline solution and the acid solution adopt a recycling system with a recycling rate of ≥90%, thereby reducing the cost of reagent consumption.

[0008] As a preferred embodiment of the above technical solution, the wet reaction solution in S3 is purified by high-precision filtration using a ceramic membrane. The ceramic membrane has a pore size of 50nm-100nm, which improves the purity of the wet product and ensures that the prepared polyaluminum sulfate and aluminum hydroxide products meet industrial standards.

[0009] As a preferred embodiment of the above technical solution, the S3 water washing deammoniation process adopts a three-stage countercurrent water washing method, with a water washing liquid-solid ratio of 4-6:1, a water washing temperature of 40℃-60℃, and a deammoniation rate of ≥99%, effectively removing soluble ammonium salts and some easily soluble impurities from die-cast aluminum ash.

[0010] As a preferred embodiment of the above technical solution, the curing agent of the S4 alkali-activated curing technology is a composite system of water glass and sodium hydroxide, with a water glass modulus of 1.0-1.5, a sodium hydroxide content of 3%-5% of the tailings mass, a curing reaction temperature of 60-80℃, and a reaction time of 24h-48h.

[0011] As a preferred embodiment of the above technical solution, the operating pressure of the ceramic membrane filtration is controlled at 0.2MPa-0.4MPa, the filtration temperature is 50℃-70℃, and the cross-flow velocity is 3m / s-5m / s, so as to achieve efficient separation and purification of solid and liquid in the feed liquid.

[0012] The beneficial effects of this invention are as follows: 1. This invention integrates multiple processes, including physical pretreatment, short-process pyrometallurgical treatment, high-temperature melting, full-scale wet processing, and high-value utilization of tailings, to perform targeted graded treatment on die-cast aluminum ash with different particle sizes and metal contents. This achieves the resource utilization of all components, including metallic aluminum, alumina, salt components, and ammonium salts. The recovery rate of metallic aluminum exceeds 98%, the hydrolysis rate of aluminum nitride exceeds 95%, the recovery rate of salt components exceeds 98%, the deammoniation rate is ≥99%, and no secondary solid waste is generated. 2. This invention achieves deep removal of harmful components such as aluminum nitride and fluorides through pyrometallurgical high-temperature decomposition and wet hydrolysis. The low-temperature closed-loop drying and degassing in the pretreatment stage, the gas cascade recovery in the wet stage, and the alkaline absorption of the tail gas prevent the leakage of harmful gases and secondary pollution from the source. 3. This invention not only recovers high-purity metallic aluminum and returns it directly to die-casting production, but also prepares industrial chemical products such as polyaluminum sulfate and aluminum hydroxide, chemical raw materials such as ammonia and ammonium salts, as well as high-value-added materials such as magnesium aluminum spinel refractory materials, cementing materials, and non-fired bricks, which greatly improves the economic benefits of die-casting aluminum ash treatment. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Example 1

[0014] A multi-process coupled recycling method for die-casting aluminum ash, designed for small and medium-sized die-casting enterprises with an annual processing capacity of 20,000 tons, utilizes small-capacity modular equipment with a 92% automation level. The specific steps are as follows: S1. Pretreatment: The die-cast aluminum ash is crushed to a particle size ≤20mm by a jaw crusher, and then screened into coarse aluminum ash (particle size >5mm), medium aluminum ash (1-5mm), and fine aluminum ash (particle size <1mm) by a three-layer vibrating grading and screening equipment. The ash is then magnetically separated by a high-efficiency permanent magnet magnetic separator with a magnetic field strength of 13000Gs to remove impurities, achieving an iron impurity removal rate of 99.2%. The aluminum ash is then sent to a low-temperature closed-loop drying equipment, where it is dried and degassed at 100℃ and a vacuum degree of -0.07MPa to remove moisture and collect trace amounts of harmful gases. After absorption by a 5% sodium hydroxide solution, the ash is discharged in compliance with emission standards.

[0015] S2. Pyrometallurgical Co-processing: Coarse aluminum ash and industrial waste alkali are mixed at a mass ratio of 4:1 in a twin-shaft mixer and then fed into a rotary kiln at a rotation speed of 1.0 r / min. Precise segmented temperature control is used (kiln head 920℃, kiln middle 880℃, kiln tail 820℃). The material stays in the kiln for 2.5 hours, achieving a dust and salt recovery rate of 99.5%. Energy consumption is reduced by 28% compared to traditional technologies. The recovered aluminum metal is refined to a purity of 99.1% and directly returned to the die-casting process. Medium-sized aluminum ash is crushed a second time to a particle size of ≤3mm by a cone crusher and then melted at high temperature in a medium-frequency induction melting device at 1050℃. The metal and impurities are efficiently separated by gravity sedimentation, and the recovered aluminum metal has a purity of 99.0%.

[0016] S3. Wet Process Full Utilization: Fine aluminum ash and pyrometallurgical residues are deammonified using a three-stage countercurrent water washing process. The water-to-solid ratio is 5:1, the washing temperature is 50℃, and the deammoniation rate is 99.3%. The water washing filtrate is evaporated and crystallized to recover ammonium chloride. The water washing filter residue is added to a 25% sodium hydroxide solution and hydrolyzed at 80℃ and 250 r / min for 3.5 h with stirring. The aluminum nitride hydrolysis rate is 96.3%. The gas generated by hydrolysis is collected through a cascade recovery device. Ammonia gas is used to prepare 20% ammonia water for sale, and combustible gas is reused as fuel for rotary kilns. The liquid was purified by filtration through an 80nm ceramic membrane at an operating pressure of 0.3MPa, a filtration temperature of 60℃, and a cross-flow velocity of 4m / s. The salt component recovery rate was 98.5%. 18% dilute sulfuric acid was added to the impurity-containing liquid, and the mixture was stirred and dissolved at 65℃ for 2 hours. 0.1‰ polyacrylamide flocculant was added for sedimentation and impurity removal. The polyaluminum sulfate prepared by concentration and crystallization of the supernatant met the industrial standard GB / T15892-2020. The residual aluminum content was 1.8%. The alkali and acid solutions were recycled after filtration and regeneration, with a recycling rate of 92%.

[0017] S4. High-value conversion of tailings: The wet process tailings meet the GB18599-2020 standard after testing. 30% is supplied to surrounding cement plants as cement admixture, and 70% is mixed with light calcined magnesia powder at a mass ratio of 2.8:1, with 1.5% boric acid sintering aid added. The mixture is sintered in a high-temperature shuttle kiln at 1550℃ for 3.5 hours. The resulting magnesium-aluminum spinel refractory material has a refractoriness of 1820℃ and is supplied to die-casting mold manufacturers. The comprehensive utilization rate of tailings is 100%.

[0018] In this embodiment, the total aluminum recovery rate is 98.6%, the annual direct economic benefit of a single production line is 15.6 million yuan, and no secondary solid waste, waste gas or waste liquid is generated during the production process. All emission indicators meet the national emission standards. Example 2

[0019] For large-scale aluminum processing enterprises with an annual processing capacity of 560,000 tons, high-capacity modular equipment with a 95% automation level is adopted. The specific steps are as follows: S1. Pretreatment: The die-cast aluminum ash is crushed to a particle size of ≤20mm by a jaw crusher, and then classified by a multi-layer vibrating grading and screening equipment. It is then magnetically separated by a high-efficiency permanent magnet magnetic separator with a magnetic field strength of 15000Gs to remove impurities, with an iron impurity removal rate of 99.5%. The aluminum ash is then sent to a low-temperature closed-loop drying equipment to dry and degas at 90℃ and a vacuum degree of -0.06MPa, removing moisture and collecting harmful gases. After absorption and treatment with 8% sodium hydroxide solution, it meets the emission standards.

[0020] S2. Pyrometallurgical Coupling Recycling: Coarse aluminum ash and industrial waste alkali are mixed at a mass ratio of 3:1 and fed into a rotary kiln. The rotary kiln rotates at 0.8 r / min and is temperature-controlled in stages (900℃ at the kiln head, 850℃ in the kiln middle, and 800℃ at the kiln tail). The material stays in the kiln for 3 hours, and the dust and salt recovery rate is 99.8%. Energy consumption is reduced by 30% compared with traditional technology. Medium-sized aluminum ash is crushed twice to a particle size of ≤3mm and then melted at high temperature in a medium-frequency induction melting device at 1000℃. The recovered metallic aluminum has a purity of 99.2% and is all returned to the enterprise's die-casting production line.

[0021] S3. Wet Process Full Utilization: Fine aluminum ash and pyrometallurgical residues are deammonified using a three-stage countercurrent water washing process with a liquid-to-solid ratio of 4:1 and a washing temperature of 40℃. The deammoniation rate is 99.1%. The water washing filtrate is evaporated and crystallized to recover ammonium sulfate. The water washing filter residue is added to a 20% sodium hydroxide solution and hydrolyzed at 70℃ with stirring at 200 r / min for 4 hours, achieving a aluminum nitride hydrolysis rate of 95.8%. The gas generated during hydrolysis is recovered in stages, and the ammonia gas is used to prepare ammonia water. The combustible gas is then supplied to the plant's boilers. The liquid is filtered through a 50nm ceramic membrane. Purification was carried out at an operating pressure of 0.2 MPa, a filtration temperature of 50℃, and a cross-flow velocity of 3 m / s. The salt component recovery rate was 98.8%. The acid dissolution-sedimentation process used 15% dilute sulfuric acid, which was stirred and dissolved at 60℃ for 1.5 h. 0.08‰ polyacrylamide flocculant was added for sedimentation and impurity removal. The prepared aluminum hydroxide met the GB / T4294-2010 industrial standard. The aluminum content of the residue was 1.5%. The recycling rate of alkali and acid solutions was 95%, saving more than 20 million yuan in reagent costs annually.

[0022] S4. High-value conversion of tailings: Approximately 15% of wet-process tailings contain trace amounts of fluorides. Through alkali-activated curing technology, a mixture of tailings, slag, and fly ash in a ratio of 5:3:2 is added, along with water glass (modulus 1.2) and a 4% sodium hydroxide composite curing agent. The mixture is then cured at 60℃ for 48 hours. The resulting cementitious material has a compressive strength ≥30MPa, meeting GB / T175-2023 standards and is used to produce non-fired bricks. The remaining 85% of the compliant tailings are used as roadbed filler in some projects and mixed with lightly calcined magnesia powder at a mass ratio of 2.5:1, with the addition of 1% boric acid sintering aid. This mixture is then sintered at 1500℃ for 4 hours to produce magnesium-aluminum spinel refractory materials. The overall utilization rate of the tailings is 100%.

[0023] In this embodiment, the total aluminum recovery rate is 98.9%, and the annual processing of 560,000 tons of die-cast aluminum ash generates comprehensive economic benefits of over 420 million yuan. This effectively solves the enterprise's solid waste disposal problem, while realizing the recycling of aluminum resources and promoting the enterprise's green and low-carbon development. Example 3

[0024] For medium-sized die-casting processing enterprises with an annual processing capacity of 100,000 tons, a medium-capacity modular equipment with an automation level of 93% is adopted. The specific steps are as follows: S1. Pretreatment: The die-cast aluminum ash is crushed to a particle size ≤20mm, graded and screened, and then magnetically separated by a 14000Gs permanent magnet separator to remove impurities. The iron impurity removal rate is 99.3%. The ash is then dried and degassed in a low-temperature closed loop at 110℃ and -0.08MPa vacuum to remove moisture and collect harmful gases.

[0025] S2. Pyrometallurgical Co-processing: Coarse aluminum ash and industrial waste alkali are mixed at a mass ratio of 5:1. The rotary kiln rotates at 1.2 r / min, and the temperature is controlled in stages (950℃ at the kiln head, 900℃ in the kiln middle, and 850℃ at the kiln tail). The material is held for 2 hours, and the dust and salt recovery rate is 99.4%, reducing energy consumption by 27%. Medium aluminum ash is melted at 1100℃, and the recovered metallic aluminum has a purity of 99.1%.

[0026] S3. Wet process full utilization: Fine aluminum ash and pyrometallurgical residue are washed in a three-stage countercurrent water process with a liquid-to-solid ratio of 6:1 and a washing temperature of 60℃, achieving a deammoniation rate of 99.5%. A 30% sodium hydroxide solution is added, and the mixture is hydrolyzed at 90℃ with stirring at 300 r / min for 3 hours, achieving an aluminum nitride hydrolysis rate of 96.5%. The solution is filtered through a 100 nm ceramic membrane at an operating pressure of 0.4 MPa, a filtration temperature of 70℃, and a cross-flow velocity of 5 m / s, achieving a salt component recovery rate of 98.6%. Acid dissolution and sedimentation are performed using 20% ​​dilute sulfuric acid, resulting in a polyaluminum sulfate purity of 98.2%, a residual aluminum content of 1.6%, and a 93% recycling rate for both alkali and acid solutions.

[0027] S4. High-value transformation of tailings: Some of the wet process tailings that meet the standards are used as cement admixtures, and some tailings containing trace heavy metals are alkali-activated and solidified (water glass modulus 1.5, sodium hydroxide content 5%, solidified at 80℃ for 24 hours) to prepare cementitious materials. The remaining tailings are used to prepare magnesium aluminum spinel refractory materials. The comprehensive utilization rate of tailings is 100%.

[0028] In this embodiment, the total aluminum recovery rate is 98.7%, with annual direct economic benefits exceeding 80 million yuan, achieving harmless disposal and high-value resource utilization of die-cast aluminum ash.

[0029] This invention presents a multi-process coupled recycling method for die-casting aluminum ash, achieving the dual goals of harmless treatment and resource utilization of die-casting aluminum ash. It solves the technical pain points of existing single-process methods, such as high energy consumption, high cost, and low resource utilization, and offers significant environmental, economic, and social benefits. This method can be flexibly adapted to small, medium, and large modular equipment according to the different production capacity needs of die-casting enterprises. It is suitable for both small and medium-sized die-casting enterprises with an annual processing capacity of tens of thousands of tons, and large-scale aluminum processing enterprises with an annual processing capacity of hundreds of thousands of tons. Furthermore, the process is simple to operate, parameters are precisely controllable, and the equipment is easy to procure and maintain.

[0030] This invention not only effectively solves the problem of aluminum ash solid waste disposal in the die-casting industry, but also enables the recycling of resources such as aluminum, sodium, and sulfur. The resulting refractory materials, cementing materials, and other products can be used to support the die-casting and building materials industries, forming a resource recycling industrial chain. Furthermore, the technology of this invention can be extended to aluminum ash treatment in related industries such as electrolytic aluminum and aluminum processing, which is of great significance for promoting the green and low-carbon development of the aluminum industry and achieving the "dual carbon" goal. It has broad industrial application prospects in the solid waste treatment and aluminum processing industries.

[0031] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A multi-process coupled recycling method for die-cast aluminum ash, characterized in that, Includes the following steps: S1. Pretreatment: The die-cast aluminum ash is crushed, graded and screened, magnetically separated to remove impurities, and then dried and degassed at low temperature in sequence to obtain graded pretreated aluminum ash. The grading and screening separates the die-cast aluminum ash into coarse particles with a particle size >5mm, medium particles with a particle size of 1mm-5mm, and fine powder aluminum ash with a particle size <1mm. The magnetic separation uses a permanent magnet separator to separate ferromagnetic impurities, with an iron impurity removal rate ≥99%. The low temperature closed-loop drying and degassed temperature is controlled at 80℃-120℃ to remove moisture while collecting trace amounts of harmful gases that escape, preventing secondary pollution. S2, Pyrometallurgical Co-processing: Coarse aluminum ash particles with a diameter >5mm from S1 are fed into a rotary kiln for a short-process pyrometallurgical reaction. Industrial waste alkali is added as a co-reactant. The reaction temperature is controlled at 850℃-950℃ using precise temperature control technology in the rotary kiln. The dust and salt recovery rate is ≥99%. Medium-sized aluminum ash particles with a diameter of 1mm-5mm are subjected to high-temperature melting treatment. After crushing and impurity removal, a low-melting-point eutectic is formed at 1000℃-1100℃, achieving phase separation of metal and impurities. The energy consumption of the melting process is reduced by more than 25% compared with traditional technology. S3, wet full-scale utilization: Fine aluminum ash with a particle size <1mm from S1 and residues after pyrometallurgical treatment are subjected to wet reaction. First, the aluminum ash is washed with water to remove ammonia and pretreated by sieving. Then, alkaline solution is added for wet hydrolysis. The hydrolysis temperature is controlled at 70℃-90℃ to ensure that the hydrolysis rate of active components such as aluminum nitride is ≥95%. The combustible gas, ammonia and hydrogen released during the process are recovered in stages. The salt components are separated and the recovery rate is ≥98%. For wet reaction liquid with more impurities, an acid dissolution-sedimentation assisted process is used. After the acid dissolves the alumina, the impurities are removed by sedimentation to prepare polyaluminum sulfate and aluminum hydroxide products. The metallic aluminum content in the residue is reduced to below 2%. S4. High-value transformation of tailings: The tailings after wet treatment in S3 are tested. If the tailings meet the standards, they can be used directly as cement admixtures and roadbed fillers. If the tailings contain trace pollutants, they can be mixed with slag and fly ash to prepare cementitious materials through alkali activation and solidification technology. At the same time, the alumina component in the tailings is used to prepare magnesium aluminum spinel refractory materials, which are suitable for the production of refractory parts for die casting molds.

2. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, The S2 rotary kiln's precise temperature control technology employs a segmented temperature control mode, with the kiln head temperature controlled at 900-950℃, the kiln middle temperature at 850-900℃, and the kiln tail temperature at 800-850℃. This achieves a full and synergistic reaction between die-cast aluminum ash and industrial waste alkali, preventing the release of harmful gases from aluminum ash upon contact with water.

3. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, The mixing mass ratio of coarse aluminum ash with a particle size >5mm in S2 to industrial waste alkali is 3-5:1, and the rotation speed of the rotary kiln is controlled at 0.8r / min-1.2r / min. The residence time of the material in the kiln is 2h-3h to ensure that the material and the reactant are in full contact and react.

4. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, In S3, the alkaline solution is a sodium hydroxide solution with a mass concentration of 20%-30%, and the acid solution used in the acid dissolution-sedimentation auxiliary process is dilute sulfuric acid with a mass concentration of 15%-20%. Both the alkaline and acid solutions are recycled, with a recycling rate of ≥90%, which reduces the cost of reagent consumption.

5. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, In S3, the wet reaction solution is purified with high precision by filtration using a ceramic membrane. The ceramic membrane has a pore size of 50nm-100nm, which improves the purity of the wet product.

6. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, The S3 water washing and deammoniation process adopts a three-stage countercurrent water washing method, with a water washing liquid-solid ratio of 4-6:1, a water washing temperature of 40℃-60℃, and a deammoniation rate of ≥99%, effectively removing soluble ammonium salts and some easily soluble impurities from die-cast aluminum ash.

7. The multi-process coupled recycling method for die-cast aluminum ash according to claim 1, characterized in that, The curing agent for the S4 alkaline-activated curing technology is a composite system of water glass and sodium hydroxide. The modulus of the water glass is 1.0-1.5, the amount of sodium hydroxide is 3%-5% of the tailings mass, the curing reaction temperature is 60-80℃, and the reaction time is 24h-48h.

8. The multi-process coupled recycling method for die-cast aluminum ash according to claim 7, characterized in that, The operating pressure of the ceramic membrane filtration is controlled at 0.2MPa-0.4MPa, the filtration temperature is 50℃-70℃, and the cross-flow velocity is 3m / s-5m / s, achieving efficient separation and purification of solids and liquids in the feed liquid.