Method for co-processing firework and cracker production waste residues and aluminum ash residues

Abstract

The invention relates to the technical field of solid waste treatment and resource utilization, in particular to a firework and cracker production waste residue and aluminum ash co-processing method which comprises the following steps: mixing firework and cracker production waste residue and aluminum ash, adding alkali liquor, reacting, and releasing SO2 gas in the reaction process; carrying out solid-liquid separation to obtain a leaching solution and leaching residues; the released SO2 gas is introduced into the leachate, pH is adjusted, solid-liquid separation is conducted, and aluminum-rich slag and aluminum-removed liquid are obtained; the molten aluminum is subjected to heavy metal removal and hardness removal treatment, and purified slag and purified liquid are obtained; performing triple-effect countercurrent evaporation on the purified liquid to obtain sodium chloride, potassium chloride and a potassium mother solution, and returning the potassium mother solution to the step S2 for size mixing; and S3, condensate water and the leaching residues obtained in the step S3 are mixed, slurrying and washing are conducted, washing liquid and washing residues are obtained, and the washing liquid is returned to the step S2 to be used for slurry mixing. Green circulation of the solid waste can be achieved through cooperation of the two kinds of solid waste, and no new waste is generated.

Description

Technical Field

[0001] This invention relates to a method for disposing of solid waste, specifically a method for the co-disposal of waste residue from fireworks and firecracker production and aluminum ash residue, belonging to the field of solid waste treatment and resource utilization technology. Background Technology

[0002] Waste from fireworks and firecracker production mainly originates from discarded or fallen fireworks and firecracker products during the production process. It often contains perchlorates, aluminum powder, aluminum-magnesium alloy powder, sulfur, etc. Currently, the common method for dealing with this type of waste is to first separate most of the soluble pollutants through water-soluble sedimentation, and then dry and incinerate the sediment to stabilize and solidify sulfur, metal dust, and other contaminants in the solid waste. While this method is simple, it is prone to causing secondary pollution, especially since highly oxidizing perchlorates can cause water pollution.

[0003] Aluminum ash slag is a hazardous solid waste generated during aluminum electrolysis and aluminum processing. Its main components include Al, AlN, fluorides, and chlorides. During storage, it easily produces harmful substances such as ammonia and hydrogen, posing significant environmental pollution and storage safety issues. Currently used methods such as ash-frying result in severe secondary pollution and low product added value, while direct wet processing of aluminum ash generates polluting gases such as ammonia, also posing secondary pollution problems.

[0004] Regarding the disposal of fireworks and firecracker waste, Chinese patent CN115254916A discloses a method for treating hazardous waste from fireworks and firecrackers. The method primarily involves first preparing the waste residue into a slurry, then subjecting it to washing, flotation, and filtration to separate sulfur powder from charcoal powder and metal powder, as well as pulp residue, mud, and sand. Finally, the charcoal powder is separated from the metal powder, achieving resource recovery. However, this method suffers from the problem that sulfur powder and metal powder tightly bind with other components of the slurry, resulting in a low recovery rate. Furthermore, Chinese patent CN108787703A discloses a method for treating fireworks waste, including slurry preparation, cooking, antistatic treatment, ultrasonic treatment, and solid-liquid separation steps. This method primarily utilizes the addition of sodium hydroxide during the cooking process to cause alkaline leaching of the metal components in the waste residue, followed by resource recovery. However, this method faces the challenge of disposing of the leachate. For example, Chinese patent CN120133297A discloses a device and process for recovering and utilizing perchlorate from fireworks and firecracker waste. The process includes primary water washing, primary solid-liquid separation, concentration, secondary water washing, secondary solid-liquid separation, and crystallization steps. It can separate, recover, and utilize perchlorate, aluminum powder, and other substances from solid waste, while simultaneously treating the waste residue to reduce environmental pollution. The main method utilizes multi-stage washing and membrane concentration to achieve the enrichment and crystallization of perchlorate, thereby realizing resource recovery. However, this method only recovers perchlorate.

[0005] Regarding the disposal of aluminum ash slag, Chinese patent CN115947359A discloses a method for preparing aluminum hydroxide from aluminum-containing waste. This method uses aluminum ash slag as raw material and employs a two-stage alkaline leaching + carbonation process. Through alkaline washing, concentrated alkaline leaching, filtrate preparation, carbonation, and water washing purification steps, impurities and harmful components in the aluminum ash are removed, and aluminum hydroxide product is recovered. However, the alkaline decomposition process of aluminum ash slag inevitably leads to ammonia nitrogen pollution. Chinese patent CN117920724A discloses a method for denitrifying aluminum ash slag using acid treatment at room temperature. This method uses an acid treatment method at room temperature, grinding aluminum ash slag with a grinding aid in a ball mill, soaking it in tap water, and introducing carbon dioxide gas to form a saturated carbon dioxide solution to absorb ammonia. Then, citric acid and hydrochloric acid are used for impurity removal, converting it into aluminum chloride, thus achieving denitrification and resource reuse of the aluminum ash slag. This method can effectively prevent ammonia nitrogen from escaping, but the acid method easily causes the dissolution of many harmful components in the aluminum ash slag, making aluminum purification difficult. Summary of the Invention

[0006] Addressing the core pain points of existing technologies for the co-processing of fireworks and firecracker waste and aluminum ash slag, such as low recovery rates, high risks of secondary pollution, and limited resource utilization pathways, this invention provides a green circular process for the joint resource utilization of fireworks and firecracker production waste and aluminum ash slag through chemical synergistic reactions. First, the two types of solid waste are mixed and pulped. Then, through alkaline leaching, oxidizing components such as perchlorate and sulfur in the fireworks and firecracker waste and reducing and amphoteric components such as Al, AlN, and Al2O3 in the aluminum ash slag undergo an in-situ synergistic reaction in an alkaline medium: perchlorate (ClO4) - ) by Al 0 Or the NH3 produced by the hydrolysis of AlN is reduced to Cl. - Simultaneously, heat is released to promote leaching; Al2O3 and metallic aluminum selectively dissolve under alkaline conditions to form sodium aluminate; the filtrate obtained in step S1 is transported to an SO2 absorption tower, and SO2 gas generated in the leaching process is introduced, making countercurrent contact in the packing layer inside the tower, while hydrochloric acid is simultaneously introduced to neutralize excess OH. - The mother liquor after solid-liquid separation directly enters the S3 multi-stage solid-liquid separation process. S3: The mother liquor obtained in S2 is sent to a triple-effect countercurrent evaporation system. The concentrate is cooled, crystallized, and centrifuged to preferentially precipitate high-purity sodium chloride crystals. The mother liquor is further cooled to precipitate potassium chloride crystals for the second time. The remaining condensate and centrifuged mother liquor are all returned to step S1 for slurry preparation, realizing the closed-loop reuse of water and sodium / potassium resources.

[0007] According to the technical solution provided by the present invention, a method for co-processing waste residue from fireworks and firecracker production and aluminum ash residue is provided.

[0008] A method for co-processing waste residue from fireworks and firecracker production with aluminum ash residue, the method comprising the following steps:

[0009] S1. Mix the waste residue from fireworks and firecracker production with aluminum ash residue, stir evenly to obtain a mixture;

[0010] S2. Add alkaline solution to the mixture to carry out the reaction, during which SO2 gas is released;

[0011] S3. The reacted slurry is subjected to solid-liquid separation to obtain leachate and leachate residue;

[0012] S4. The SO2 gas released in step S2 is introduced into the leachate obtained in step S3, the pH is adjusted, and solid-liquid separation is performed to obtain aluminum-rich slag and aluminum-removing liquid.

[0013] S5. The aluminum removal liquid is subjected to heavy and hard removal treatment, and solid-liquid separation is performed to obtain purified residue and purified liquid.

[0014] S6. Perform triple-effect countercurrent evaporation on the purified liquid to obtain sodium chloride, condensate and sodium mother liquor;

[0015] S7. Flash-cool the sodium mother liquor to obtain potassium chloride and potassium mother liquor. Return the potassium mother liquor to step S2 for slurry preparation.

[0016] S8. Mix the condensate obtained in step S6 with the leaching residue obtained in step S3, slurry and wash, and separate the solid and liquid to obtain washing liquid and washing residue. The washing liquid is returned to step S2 for slurry preparation.

[0017] In this invention, in step S1, the mixing weight ratio of fireworks and firecracker production waste residue to aluminum ash residue is 0.1~0.4:1, preferably 0.2~0.3:1.

[0018] In this invention, in step S2, the added alkaline solution is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.

[0019] In this invention, the concentration of the added alkali solution is 5-20%.

[0020] In this invention, the amount of alkali solution added is sufficient to raise the pH of the solution to above 12.

[0021] In this invention, the reaction time in step S2 is 1 to 4 hours, preferably 2 to 3 hours.

[0022] In this invention, in step S2, the reaction temperature is 20~80℃, preferably 60~80℃, and the liquid-solid ratio is 3~8:1, preferably 3~6:1.

[0023] Preferably, the reaction system is aerated during the reaction process; the gas introduced is air; the aeration rate is 0.5~2.0 L / min·L slurry to ensure that SO2 escapes in a timely manner.

[0024] In this invention, the solid-liquid separation is achieved through filtration, pressure filtration, vacuum filtration, or centrifugation.

[0025] In this invention, step S4 specifically involves adjusting the pH of the leachate to 6-8 using hydrochloric acid.

[0026] Preferably, the concentration of hydrochloric acid is 5-20%.

[0027] As a preferred option, the resulting aluminum-rich slag is used as a raw material for aluminum smelting.

[0028] In this invention, step S5 specifically involves adding a softener and a de-weighting agent to the aluminum removal liquid and stirring to carry out the reaction.

[0029] Preferably, the softener is sodium carbonate. The amount of softener added is 0.1% to 10% of the solution weight.

[0030] Preferably, the sludge remover is at least one selected from sodium sulfide, organic sulfur, and calcium polysulfide. The amount of the sludge remover added is 0.1% to 10% of the solution weight.

[0031] Preferably, the purified residue obtained in step S5 is a mixture of calcium carbonate and heavy metal sulfides; used as an additive in sintering aluminum smelting.

[0032] In this invention, in step S6, the triple-effect countercurrent evaporation specifically involves passing the purified liquid sequentially through a triple-effect reactor, a second-effect reactor, and a first-effect reactor. The temperature in the triple-effect reactor is 20–60°C (preferably 30–50°C), the temperature in the second-effect evaporation is 40–90°C (preferably 50–80°C), and the temperature in the first-effect evaporation is 70–105°C (preferably 80–100°C). Condensate is obtained during the evaporation process. After concentration, the purified liquid is discharged from the first-effect reactor into a thickener, producing sodium chloride crystals and sodium mother liquor.

[0033] In this invention, step S7 specifically involves processing the sodium mother liquor through a flash evaporator, controlling the negative pressure of the flash evaporator to be greater than 85 kPa, and the flash temperature to be 40~80℃.

[0034] Preferably, the water-washed residue obtained in step S8 is used as a building material raw material.

[0035] This invention provides a specific technical solution, a method for the co-processing of waste residue from fireworks and firecracker production and aluminum ash residue. The specific process flow is as follows: 1) The waste residue from fireworks and firecracker production and aluminum ash residue are thoroughly mixed in a certain proportion to obtain a mixture; 2) The mixture is added to a stirring tank containing a certain concentration of alkaline solution for reaction. The reaction process requires heating, and aeration helps to improve the reaction effect. SO2 will be generated during the reaction process; 3) The slurry obtained in step 2) is subjected to solid-liquid separation to obtain leachate and leach residue; 4) SO2 gas generated in step 2) is introduced into the leachate obtained in step 3), and aluminum-rich residue and aluminum-removing liquid are obtained through solid-liquid separation. The aluminum-rich residue can be used as a raw material for alumina production; 5) Add a softener and a de-heavy agent to the aluminum removal solution obtained in step 4) to remove residual calcium and magnesium hardness and a small amount of heavy metals from the solution. Separate the solid and liquid to obtain sludge and purification liquid. The sludge containing heavy metals is transported off-site for disposal. 6) Perform triple-effect countercurrent evaporation on the purification liquid to obtain sodium chloride product, condensate and sodium mother liquor. 7) Perform flash cooling on the sodium mother liquor obtained in step 6) to obtain potassium chloride product and potassium mother liquor. Return the potassium mother liquor to step 2) for slurry preparation. 8) Mix the condensate obtained in step 6) with the leaching residue obtained in step 3). Perform slurry washing on the residual salt in the leaching residue. Separate the solid and liquid to obtain washing liquid and washing residue. Return the washing liquid to step 2) for slurry preparation. The washing residue can be used for building material utilization.

[0036] The principle of the technical solution of this invention is as follows:

[0037] 1. Perchlorate in fireworks waste is used for aluminum nitride in alumina ash: Fireworks waste contains high concentrations of perchlorate, which has strong oxidizing properties and is easily soluble, causing water pollution. Aluminum nitride in alumina ash releases ammonia nitrogen upon contact with water, also causing environmental pollution. Alkali leaching of fireworks waste and alumina ash utilizes the oxidizing properties of perchlorate to generate nitrogen gas from the low-valence nitrogen in the alumina ash, which is then reduced to harmless chloride ions. This process achieves the green decomposition of both types of waste.

[0038] 3ClO 4－ + 8OH － + 8AlN = 4N2↑ + 3Cl － + 8AlO2 － + 4H2O

[0039] 2. Resource utilization of aluminum and magnesium: The redox reaction of elemental aluminum and aluminum nitride in aluminum and magnesium powder, aluminum powder and aluminum ash slag in fireworks solid waste is realized through alkaline leaching. Aluminum can be dissolved in water in the form of soluble aluminate, and magnesium precipitates into the slag in the form of magnesium hydroxide along with calcium and other components. The slag can be used to prepare building materials such as lightweight bricks. The aluminum-containing solution is neutralized by hydrochloric acid to hydrolyze and precipitate aluminum. The resulting aluminum-rich slag can be used as a raw material for alumina production.

[0040] 3. Resource utilization of salt: Soluble salts in fireworks solid waste mainly exist in the form of potassium perchlorate. Potassium chloride can be obtained through oxidation-reduction. Low-melting-point soluble salts such as potassium chloride and sodium chloride are also added during the ash-making process of aluminum ash to form a liquid phase. Therefore, the main components of the solution obtained after co-processing and precipitation of aluminum are high-concentration potassium chloride and sodium chloride. Potassium and sodium salts can be recovered through triple-effect countercurrent evaporation coupled with flash cooling, achieving zero discharge of wastewater.

[0041] Technical challenges exist in the conventional disposal of waste residue and aluminum ash from fireworks and firecracker production. Waste residue contains perchlorate, aluminum powder, aluminum-magnesium alloy powder, sulfur, and other components. When using water-soluble sedimentation for separation, the highly oxidizing perchlorate easily pollutes water bodies; simultaneously, sulfur powder and metal powder are often tightly bound to other components, resulting in low separation efficiency. Aluminum ash contains aluminum nitride, fluorides, chlorides, and other compounds, which easily generate ammonia and hydrogen during stockpiling. Existing ash-frying or wet disposal methods not only cause secondary pollution but also result in high concentrations of pollutants in the leachate, making disposal difficult. Furthermore, the stabilization and solidification processes of sulfur and metal dust in the solid waste are disrupted, affecting resource recovery efficiency.

[0042] If the above problems are not addressed, the solid waste disposal process will continue to generate environmental risks, including expanded water pollution, increased emissions of harmful gases, and safety hazards from stockpiling. Low resource recovery efficiency will result in the ineffective utilization of elements such as sulfur and aluminum, leading to resource waste. The challenges in disposing of leachate may further trigger wider environmental pollution and hinder the promotion of solid waste resource utilization technologies.

[0043] Therefore, a method for co-processing fireworks and firecracker production waste and aluminum ash is provided, the method comprising the following steps:

[0044] S1. Mix the waste residue from fireworks and firecracker production with aluminum ash residue, stir evenly to obtain a mixture;

[0045] S2. Add alkaline solution to the mixture to carry out the reaction, during which SO2 gas is released;

[0046] S3. The reacted slurry is subjected to solid-liquid separation to obtain leachate and leachate residue;

[0047] S4. The SO2 gas released in step S2 is introduced into the leachate obtained in step S3, the pH is adjusted, and solid-liquid separation is performed to obtain aluminum-rich slag and aluminum-removing liquid.

[0048] S5. The aluminum removal liquid is subjected to heavy and hard removal treatment, and solid-liquid separation is performed to obtain purified residue and purified liquid.

[0049] S6. Perform triple-effect countercurrent evaporation on the purified liquid to obtain sodium chloride, condensate and sodium mother liquor;

[0050] S7. Flash-cool the sodium mother liquor to obtain potassium chloride and potassium mother liquor. Return the potassium mother liquor to step S2 for slurry preparation.

[0051] S8. Mix the condensate obtained in step S6 with the leaching residue obtained in step S3, slurry and wash, and separate the solid and liquid to obtain washing liquid and washing residue. The washing liquid is returned to step S2 for slurry preparation.

[0052] In this invention, fireworks and firecracker production waste refers to the waste generated during the production of fireworks and firecrackers. Its composition is complex, typically containing perchlorate, aluminum powder, aluminum-magnesium alloy powder, sulfur, and other substances. This waste poses a certain degree of hazard and, if not properly disposed of, can easily pollute the environment. Aluminum ash slag refers to the solid waste generated during aluminum electrolysis and aluminum processing, primarily composed of aluminum, aluminum nitride, fluorides, chlorides, etc. This waste slag may release harmful gases during storage, posing a threat to the environment and safety.

[0053] In this invention, the mixture refers to the material formed by mixing and stirring waste residue from fireworks and firecracker production with aluminum ash residue, which is the starting material for subsequent processing steps. Alkali solution refers to a solution with alkaline properties, used in this method to react with the mixture to achieve the leaching of specific components. Slurry refers to a mixture formed by solid particles dispersed in a liquid; in this method, it specifically refers to the solid-liquid mixture after the reaction. Solid-liquid separation refers to the operation of separating the solid components from the liquid components in the slurry, which can be achieved using various physical methods. Leachate refers to the liquid portion obtained after solid-liquid separation, containing dissolved soluble substances leached from the waste residue. Leaching residue refers to the solid portion obtained after solid-liquid separation, containing undissolved solid residues. Aluminum-rich slag refers to the aluminum-rich solid product separated from the leaching residue through specific steps in subsequent processing. Aluminum-removing solution refers to the liquid portion obtained after separating the aluminum-rich slag, in which the aluminum content is significantly reduced. Heavy metal and hardness removal treatment refers to the process of treating aluminum removal liquid to remove heavy metal ions and hardness ions (such as calcium and magnesium ions).

[0054] In this invention, triple-effect countercurrent evaporation is a multi-effect evaporation technology that utilizes the latent heat of steam to concentrate the solution and recover the solvent (water) in multiple evaporators, thereby improving energy efficiency. Flash cooling is a technique that rapidly evaporates and cools a liquid by reducing pressure, often used in crystallization processes. Slurry washing refers to the process of mixing solid materials with water to form a slurry, followed by washing to remove soluble impurities from the solid surface.

[0055] This embodiment provides a method for the co-processing of waste residue from fireworks and firecracker production and aluminum ash residue. Through a series of steps, this method achieves the harmless treatment of waste residue and the recovery of valuable components.

[0056] In step S1, waste residue from fireworks production and aluminum ash are mixed and stirred evenly to obtain a mixture. This mixing can be done manually, by piling the two types of waste residue together in a certain proportion and then turning them over with tools. Alternatively, it can be done mechanically, such as using a forklift or mixer to mix the waste residue, ensuring uniform material distribution. The purpose of mixing is to ensure that the two types of waste residue come into full contact, laying the foundation for subsequent reactions.

[0057] In step S2, an alkaline solution is added to the mixture, and a reaction is initiated. During the reaction, SO2 gas is released. The alkaline solution can be added manually by slowly pouring the pre-prepared solution into the mixture. The reaction can be carried out in an open container, and the occurrence of the reaction can be determined by observing the generation of bubbles. The release of SO2 gas is one of the characteristics of this reaction, indicating that sulfides or sulfur-containing substances in the waste residue have undergone transformation under alkaline conditions.

[0058] In step S3, the reacted slurry undergoes solid-liquid separation to obtain leachate and leachate residue. Solid-liquid separation can be achieved through simple gravity sedimentation, allowing the slurry to stand for a period of time, after which the solid particles naturally settle to the bottom, and the clear liquid on top is the leachate. Alternatively, a filter cloth can be used for filtration; the slurry is poured into the filter cloth, allowing the liquid to pass through while the solids are retained.

[0059] In step S4, the SO2 gas released in step S2 is introduced into the leachate obtained in step S3 to adjust the pH, and solid-liquid separation is performed again to obtain aluminum-rich slag and aluminum-removing solution. SO2 gas can be directly introduced into the leachate through a pipeline, and the absorption of SO2 is determined by observing changes in the solution's color or pH value. pH adjustment can be achieved by adding an acidic substance (e.g., dilute sulfuric acid), and the pH value of the solution is monitored using a pH meter until the target range is reached. Solid-liquid separation can be performed in a similar manner to step S3, such as through a simple filtration operation.

[0060] In step S5, the aluminum removal liquid undergoes heavy metal and hard metal removal treatment, followed by solid-liquid separation to obtain purified slag and purified liquid. Heavy metal and hard metal removal can be achieved by adding a general-purpose precipitant to the aluminum removal liquid, such as sodium carbonate to precipitate calcium and magnesium ions, or sodium sulfide to precipitate heavy metal ions. After adding the precipitant, thorough stirring is required to promote the reaction, followed by settling to allow precipitate formation. Solid-liquid separation can be achieved by centrifugation, using high-speed rotation to separate the solid precipitate from the liquid.

[0061] In step S6, the purified liquid undergoes triple-effect countercurrent evaporation to obtain sodium chloride, condensate, and sodium mother liquor. Triple-effect countercurrent evaporation can be carried out in a multi-effect evaporator, where the purified liquid passes sequentially through three evaporators connected in series, concentrating under different temperature and pressure conditions. During evaporation, water vapor is condensed and recovered as condensate, and sodium chloride crystallizes out of the concentrated solution. Sodium chloride is obtained through separation, and the remaining concentrated liquid is the sodium mother liquor.

[0062] In step S7, the sodium mother liquor is flash-cooled to obtain potassium chloride and potassium mother liquor. The potassium mother liquor is then returned to step S2 for slurry preparation. Flash cooling can be achieved by introducing the sodium mother liquor into a low-pressure vessel. Due to the sudden pressure drop, some of the solvent evaporates rapidly, causing the solution temperature to decrease, thereby promoting the crystallization of potassium chloride. The crystallized potassium chloride is obtained through solid-liquid separation, and the remaining liquid is the potassium mother liquor. This potassium mother liquor is collected and transported back to step S2, either as part of the alkali solution or for adjusting the composition of the slurry.

[0063] In step S8, the condensate obtained in step S6 is mixed with the leaching residue obtained in step S3 for pulp washing. Solid-liquid separation is then performed to obtain washing liquid and washing residue. The washing liquid is returned to step S2 for pulp preparation. The mixing of condensate and leaching residue can be carried out in a stirred tank by adding an appropriate amount of condensate and stirring thoroughly to dissolve soluble substances in the leaching residue into the water. Solid-liquid separation can be performed using a filter press to separate the washing liquid from the washing residue. The resulting washing liquid is collected and returned to step S2 for adjusting the pulp composition or as part of the alkali solution.

[0064] Through the aforementioned co-processing method, harmful components in fireworks and firecracker production waste and aluminum ash slag are effectively removed, while valuable components such as sodium chloride, potassium chloride, and aluminum-rich slag are recycled, achieving waste reduction, harmlessness, and resource recovery. The method provided in this embodiment, by co-processing fireworks and firecracker production waste and aluminum ash slag, effectively solves the problems of secondary pollution, low resource recovery rate, and high processing costs associated with single waste treatment in existing technologies. For example, in existing technologies, the disposal of fireworks and firecracker waste often faces problems of perchlorate water pollution and difficulties in leachate disposal, while the disposal of aluminum ash slag easily generates harmful gases such as ammonia, and aluminum purification is difficult. In summary, the method provided in this embodiment, through co-processing, SO2 recycling, multi-stage purification, and internal circulation, overcomes many technical difficulties faced by the separate treatment of fireworks and firecracker production waste and aluminum ash slag in existing technologies, achieving deep harmlessness and high-value resource recovery of waste, demonstrating significant technological progress and economic benefits.

[0065] This application further proposes that in the above method, in step S1, the mixing weight ratio of fireworks and firecracker production waste residue to aluminum ash residue is 0.1-0.4:1. Here, the mixing weight ratio refers to the relative proportion of the masses of the fireworks and firecracker production waste residue and the aluminum ash residue during mixing. This ratio is a key parameter for determining the initial concentration of reactants, directly affecting the rate of subsequent chemical reactions, product yield, and impurity content. Controlling the mixing weight ratio within the range of 0.1-0.4:1 aims to optimize the synergistic treatment effect of the two waste residues. For example, when the proportion of fireworks and firecracker production waste residue is too low, it may not provide enough active components to effectively react with the alumina in the aluminum ash residue, resulting in a low aluminum leaching rate; while when the proportion of fireworks and firecracker production waste residue is too high, it may introduce too many impurities, increasing the difficulty and cost of subsequent purification treatment, and may also lead to insufficient utilization of the effective components in the aluminum ash residue. Therefore, this specific weight ratio range ensures that the effective components in both waste residues are fully utilized while avoiding the introduction of excessive impurities, thereby improving the overall efficiency and economy of the process.

[0066] This application further proposes that in step S2, the added alkaline solution can be at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; the concentration of the added alkaline solution can be 5-20%; and the amount of added alkaline solution can be sufficient to raise the pH of the solution to above 12.

[0067] The selected alkaline substances, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, can provide the hydroxide or carbonate ions required for the reaction, promoting the dissolution and transformation of specific components in fireworks and firecracker production waste and aluminum ash. For example, sodium hydroxide and potassium hydroxide are strong bases that can effectively increase the pH of the solution, promoting the dissolution of aluminum compounds; while sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate can provide alkalinity while forming precipitates with certain metal ions through carbonate ions, or acting as buffers to stabilize the solution pH. Furthermore, the concentration of the alkaline solution is a key factor affecting the reaction rate and dissolution efficiency. Lower concentrations may lead to slow reactions requiring longer reaction times; while excessively high concentrations may increase reagent consumption and potentially trigger side reactions or adversely affect subsequent separation processes. Therefore, controlling the concentration within an appropriate range helps optimize reaction kinetics and economics. Moreover, maintaining a high pH is a crucial condition for ensuring the full dissolution of amphoteric oxides such as alumina in the aluminum ash, and also helps promote the decomposition of certain components in the fireworks and firecracker waste. Too low a pH value may lead to incomplete dissolution, while too high a pH value may result in wasted resources or increase the burden of subsequent neutralization treatment.

[0068] This application further proposes that in the above method, the reaction temperature in step S2 can be controlled at 20-80℃, preferably 60-80℃; the liquid-solid ratio can be controlled at 3-8:1, preferably 3-6:1; as a preferred embodiment, aeration can be introduced into the reaction system during the reaction process; the introduced gas can be air.

[0069] The reaction temperature refers to the system temperature maintained during the reaction of the mixture and the alkali solution in step S2. This temperature can be controlled in various ways. For example, a reactor with a heating jacket can be used, and the temperature of the reaction system can be adjusted and maintained by circulating a heating medium (such as hot water, steam, or heat transfer oil). Alternatively, precise temperature control can be achieved by installing heating coils inside the reactor, combined with a temperature sensor and an automatic control system. The liquid-to-solid ratio refers to the weight ratio between the added alkali solution (liquid phase) and the mixture (solid phase) in step S2. This ratio has a significant impact on the mass transfer efficiency between the solid and liquid phases, the concentration of reactants, and the rheological properties of the slurry. A suitable liquid-to-solid ratio ensures sufficient contact between the solid particles and the liquid alkali solution, promoting the leaching of effective components, while maintaining good slurry flowability for easy stirring and subsequent processing. The liquid-to-solid ratio can be controlled by accurately measuring the weight of the solid mixture and the amount of liquid alkali solution added. For example, a weighing sensor can be used to weigh the solid phase, and a flow meter or metering pump can be used to accurately deliver the liquid phase to ensure that the preset liquid-to-solid ratio is achieved. Aeration refers to the introduction of gas into the reaction system during the reaction process, dispersing it as bubbles in the liquid-solid slurry. The main function of aeration is to enhance the mixing effect of the slurry, promote mass transfer between the solid and liquid phases, and may provide necessary reactants for certain redox reactions. Aeration can be achieved by installing gas diffusers or aeration heads at the bottom or side walls of the reactor, through which the gas is uniformly dispersed into the slurry. Alternatively, specially designed mechanical agitators can be used to simultaneously draw in and disperse the gas into the system. The gas introduced is air, specifically ambient air. Air, as an readily available and inexpensive gas, is mainly composed of nitrogen and oxygen. During aeration, oxygen in the air can act as an oxidant, participating in the oxidation reactions of certain components in the waste residue, for example, promoting the decomposition of sulfides or organic matter, thereby helping to improve the leaching rate of the target components or the quality of the leachate. Simultaneously, inert components such as nitrogen in the air also play a role in stirring and mixing. Air supply can be achieved through an air compressor. After pretreatment such as filtration and drying, the compressed air is delivered to the reaction system through pipelines.

[0070] This application further proposes that the de-weighting and de-hardening treatment in step S5 specifically involves: adding a softener and a de-weighting agent to the aluminum removal solution and stirring to carry out the reaction; preferably, the softener is sodium carbonate; the amount of softener added is 0.1~10% of the solution weight; the de-weighting agent is at least one of sodium sulfide, organic sulfur, and calcium polysulfide; the amount of de-weighting agent added is 0.1~10% of the solution weight.

[0071] The heavy metal removal and hardness removal processes aim to remove any heavy metal ions (such as lead, cadmium, and mercury) and hardness ions (such as calcium and magnesium) that may be present in the solution. If these ions are not removed, they may cause scaling, clogging, and other problems in the subsequent evaporation and crystallization processes, affecting the purity of the final product. The softening agent reacts with the hardness ions (mainly calcium and magnesium ions) in the solution to form insoluble precipitates, thereby removing them from the solution. Besides sodium carbonate, commonly used softening agents can also be alkaline substances such as sodium hydroxide, potassium hydroxide, sodium bicarbonate, and potassium carbonate, or combinations thereof. The heavy metal removal agent reacts with the heavy metal ions in the solution to form precipitates with extremely low solubility, thus separating the heavy metal ions from the solution. Besides sodium sulfide, organic sulfur compounds, and calcium polysulfides, other substances that can form stable precipitates or complexes with heavy metal ions can also be used, such as dithiocarbamate compounds or certain chelating agents. The purpose of stirring is to ensure that the added softener and deweighting agent can be fully mixed with the aluminum removal solution, promote the reaction, improve the reaction efficiency and precipitation effect, and avoid excessively high local concentrations or uneven reactions.

[0072] This application's solution involves selectively introducing a softener and a de-lamination agent into the aluminum-removing solution after aluminum removal treatment. This causes hardness ions such as calcium and magnesium in the solution to react with the softener to form insoluble precipitates such as calcium carbonate and magnesium hydroxide. Simultaneously, heavy metal ions such as lead and cadmium in the solution react with the de-lamination agent to form corresponding sulfide precipitates. Thorough stirring ensures that these precipitation reactions proceed efficiently and completely, effectively separating these harmful impurities from the solution. This treatment method, performed before solid-liquid separation, significantly reduces the impurity content in the subsequent purified solution, providing a pure feed solution for subsequent crystallization steps such as triple-effect countercurrent evaporation and flash cooling. This avoids scaling and clogging problems and ensures the quality of the final sodium chloride and potassium chloride products.

[0073] This application further proposes that in step S6, the triple-effect countercurrent evaporation specifically involves sequentially passing the purified liquid through a triple-effect reactor, a second-effect reactor, and a first-effect reactor. Triple-effect countercurrent evaporation is a highly efficient evaporation technology. Its core lies in using a multi-stage series evaporator to utilize the secondary steam generated in the previous effect as heating steam for the next effect, achieving cascaded energy utilization and significantly reducing the overall energy consumption of the evaporation process. The countercurrent operation mode typically refers to the feed liquid entering from the low-temperature, low-pressure final effect (e.g., a triple-effect reactor) and gradually flowing towards the high-temperature, high-pressure first effect (e.g., a first-effect reactor), while the heating steam enters from the first effect and flows sequentially towards the final effect. This design helps optimize heat transfer efficiency and evaporation rate. The evaporator can be a shell-and-tube evaporator, where heating steam flows between the tubes and the feed liquid flows inside the tubes; or a plate evaporator, where heat transfer and evaporation occur through channels between the plates; or a forced circulation evaporator, where a pump forces the feed liquid to circulate, improving the heat transfer coefficient, suitable for high-viscosity or easily scaling solutions.

[0074] This application's solution achieves efficient removal of moisture and effective crystallization separation of sodium chloride by introducing the purified liquid into a triple-effect countercurrent evaporation system. Specifically, the purified liquid first enters the lower-temperature triple-effect reactor for preliminary evaporation. The secondary steam generated in the triple-effect reactor is introduced into the second-effect reactor as a heat source, allowing evaporation to occur at a higher temperature in the second-effect reactor. Similarly, the secondary steam generated in the second-effect reactor is introduced into the first-effect reactor as a heat source, where deep concentration is achieved at the highest temperature. This stepwise heating and countercurrent feeding evaporation method creates a reasonable temperature gradient between the effects, achieving tiered energy utilization and significantly reducing the overall energy consumption of the evaporation process. As the purified liquid gradually concentrates in each effect, the concentration of sodium chloride gradually increases. When it reaches a supersaturated state, sodium chloride begins to crystallize and precipitate. Finally, the high-concentration slurry discharged from the first-effect reactor is sent to a thickener for solid-liquid separation, thereby efficiently separating sodium chloride crystals and obtaining a sodium mother liquor rich in other salts. Simultaneously, the pure condensate generated during the evaporation process is collected, achieving water resource recycling. By combining this refined triple-effect countercurrent evaporation with solid-liquid separation, this application effectively solves the problems of high energy consumption, low separation efficiency, and poor product purity in traditional evaporation processes, ensuring the effective recovery of sodium chloride and providing high-quality raw materials for the subsequent treatment of sodium mother liquor.

[0075] This application further proposes that the sodium mother liquor be flash-cooled by passing the sodium mother liquor through a flash evaporator, controlling the negative pressure of the flash evaporator to be greater than 85 kPa, and the flash temperature to be 40~80℃; and the water-washed residue obtained in step S8 is used as a building material raw material.

[0076] Flash cooling is a technique that achieves cooling by rapidly reducing liquid pressure, causing partial evaporation. This process is commonly used for solution concentration and crystallization; by controlling evaporation conditions, crystal precipitation can be precisely controlled. A flash evaporator is a specialized device for flash cooling, typically consisting of a sealed container where the liquid undergoes rapid decompression. A negative pressure greater than 85 kPa means the absolute pressure inside the flash evaporator is far below atmospheric pressure. This low-pressure environment significantly lowers the boiling point of water, enabling rapid evaporation at lower temperatures and promoting supersaturated crystallization of potassium salts. A flash temperature of 40–80°C is an optimal range selected based on the solubility curve and crystallization kinetics of potassium salts, aiming to ensure effective crystallization while avoiding the co-precipitation of other impurities. Using washed residue as a building material raw material refers to using the solid residue after washing, instead of treating it as waste, as a component in the production of building materials. This can include using it as an admixture in cement, aggregate in concrete, raw material for bricks and tiles, or filler material for road base layers, thus achieving resource utilization of waste.

[0077] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0078] 1. This invention provides a method for the co-processing of waste residue from fireworks and firecracker production and aluminum ash residue. The co-processing of these two types of solid waste can achieve green recycling of solid waste. The co-processing of fireworks solid waste and aluminum ash residue can achieve the synergistic detoxification and resource utilization of perchlorate and aluminum nitride.

[0079] 2. This invention combines the characteristics of two types of solid waste. Both fireworks solid waste and aluminum ash slag contain metallic aluminum, and the resource utilization of aluminum in the two types of solid waste can be achieved through a single process.

[0080] 3. This invention can realize the full resource utilization of waste residue and aluminum ash residue from fireworks and firecracker production without generating new waste. Attached Figure Description

[0081] Figure 1 This is a process flow diagram of a method for the co-processing of waste residue from fireworks and firecracker production and aluminum ash residue according to the present invention. Detailed Implementation

[0082] The technical solution of the present invention will be illustrated below with examples. The scope of protection sought by the present invention includes, but is not limited to, the following embodiments.

[0083] Example 1

[0084] A method for co-processing waste residue from fireworks and firecracker production with aluminum ash residue, the method comprising the following steps:

[0085] S1. Mix the waste residue from fireworks and firecracker production with aluminum ash residue, stir evenly to obtain a mixture;

[0086] S2. Add alkaline solution to the mixture to carry out the reaction, during which SO2 gas is released;

[0087] S3. The reacted slurry is subjected to solid-liquid separation to obtain leachate and leachate residue;

[0088] S4. The SO2 gas released in step S2 is introduced into the leachate obtained in step S3, the pH is adjusted, and solid-liquid separation is performed to obtain aluminum-rich slag and aluminum-removing liquid.

[0089] S5. The aluminum removal liquid is subjected to heavy and hard removal treatment, and solid-liquid separation is performed to obtain purified residue and purified liquid.

[0090] S6. Perform triple-effect countercurrent evaporation on the purified liquid to obtain sodium chloride, condensate and sodium mother liquor;

[0091] S7. Flash-cool the sodium mother liquor to obtain potassium chloride and potassium mother liquor. Return the potassium mother liquor to step S2 for slurry preparation.

[0092] S8. Mix the condensate obtained in step S6 with the leaching residue obtained in step S3, slurry and wash, and separate the solid and liquid to obtain washing liquid and washing residue. The washing liquid is returned to step S2 for slurry preparation.

[0093] Example 2

[0094] Repeat Example 1, except that in step S1, the mixing weight ratio of fireworks and firecracker production waste residue to aluminum ash residue is 0.25:1. In step S2, the added alkali solution is a 10% sodium hydroxide solution, and the amount of alkali solution added is enough to raise the pH of the solution to 12.

[0095] Example 3

[0096] Repeat Example 2, except that in step S2, the reaction time is 2 hours, the reaction temperature is 50°C, and air is introduced into the reaction system during the reaction; the gas introduced is air; the aeration rate is 1.0 L / min·L slurry to ensure that SO2 escapes in time.

[0097] Example 4

[0098] Repeat Example 3, except that in step S4, the pH adjustment specifically involves using 6% hydrochloric acid to adjust the pH of the leachate to 7.

[0099] Example 5

[0100] Example 4 is repeated, except that in step S5, the heavy metal and hard metal removal treatment specifically involves adding sodium carbonate and sodium sulfide to the aluminum removal solution and stirring to allow for reaction. The amount of sodium carbonate added is 3% of the solution weight. The amount of sodium sulfide added is 1% of the solution weight. The purified slag obtained in step S5 is a mixture of calcium carbonate and heavy metal sulfides; it is used as an additive in sintering aluminum smelting.

[0101] Example 6

[0102] Repeat Example 5, except that in step S6, the triple-effect countercurrent evaporation specifically involves passing the purified liquid sequentially through a triple-effect reactor, a second-effect reactor, and a first-effect reactor. The temperature in the triple-effect reactor is 30°C, the temperature in the second-effect evaporation is 60°C, and the temperature in the first-effect evaporation is 100°C. During the evaporation process, condensate is obtained. After concentration, the purified liquid is discharged from the first-effect reactor into a thickener, producing sodium chloride crystals and sodium mother liquor.

[0103] Example 7

[0104] Repeat Example 6, except that in step S7, the flash cooling specifically involves processing the sodium mother liquor through a flash evaporator, controlling the negative pressure of the flash evaporator to be 100 kPa and the flash temperature to be 50°C.

[0105] Application Example 1

[0106] 0.5 kg of fireworks and firecracker production waste residue was mixed with 2 kg of aluminum ash residue. The fireworks and firecracker waste residue contained 15% potassium perchlorate, 22% magnesium aluminum powder, and 8% sulfur, while the aluminum ash residue contained 18% metallic aluminum, 2.5% AlN, and 35% Al2O3. A 10% NaOH solution was added at a liquid-to-solid ratio of 5:1, and the mixture was stirred and leached at 75°C for 2.5 hours, while simultaneously aerating at a slurry rate of 1.2 L / min·L. The leachate was then filtered to obtain a leaching residue (Al2O3 32.5%, NaCl 4.5%). 1.2%) and leachate; the pH of the leachate is adjusted to 7.2 with 15% hydrochloric acid, and filtered to obtain aluminum-rich slag (Al2O3≥65%) and liquid after aluminum precipitation. Then, 0.8% sodium carbonate and 0.6% sodium sulfide by mass of the solution are added, and the reaction is carried out at 60℃ for 3 minutes to obtain purified slag (CaCO3≥70%, PbS+CuS≤3%) and purified liquid; the purified liquid is evaporated by triple-effect countercurrent evaporation (triple effect 35℃, second effect 65℃, first effect 90℃), and the condensate is recycled for slurry preparation in step S1; the concentrated liquid is flash cooled (negative pressure 92kPa, temperature 55℃) and then enters the thickener to obtain sodium chloride crystals (NaCl≥98.5%, SO42-20%). 2- ≤0.15%) and sodium mother liquor; the sodium mother liquor is returned to step S2 for aluminum ash slurry preparation, and the water-washed slag (SiO2+Al2O3≥78%) obtained after leaching is used as aggregate for autoclaved aerated concrete blocks after pressure filtration and drying.

[0107] Application Example 2

[0108] Take 1.2 kg of fireworks and firecracker waste residue (KClO4 18.3%, S 6.7%, MgAl2O4 14.5%) and 3.5 kg of aluminum ash residue (Al 0A mixture of Al₂O₃ (21.6%), AlN (2.8%), Al₂O₃ (41.2%), and CaO (5.3%) was added to an 8% NaOH solution at a liquid-to-solid ratio of 6:1. The mixture was leached at 85°C for 3.0 hours with an aeration rate of 1.5 L / min·L, yielding leaching residue (Al₂O₃ 28.7%, NaCl 0.7%) and leachate. The pH of the leachate was adjusted to 7.5 and then filtered to obtain aluminum-rich slag (Al₂O₃ 68.4%, NaCl 0.93%) and aluminum-removing solution. 0.5% Na₂CO₃ and 0.4% NaOH solution were added to the aluminum-removing solution. Na₂S was reacted at 70℃ for 2 minutes, and the residue was filtered to obtain purified residue (CaCO₃≥70%, PbS+CuS≤3%) and purified liquid. The purified liquid was subjected to triple-effect countercurrent evaporation (triple-effect 40℃, second-effect 70℃, first-effect 95℃), and the condensate was reused in step S1 for slurry preparation. The concentrated liquid was flash-cooled at a negative pressure of 95 kPa and a temperature of 52℃, and then separated in a thickener to obtain potassium chloride crystals (KCl≥98.2%, Cl₂). - SO4 2- ≥1200) and potassium mother liquor; the potassium mother liquor is returned to step S2 for aluminum ash slurry preparation, and the water-washed slag (SiO2 52.6%, Al2O3 25.3%, Fe2O3 4.1%) obtained after leaching slag is dried at 105℃ for 2h and then used as ceramic body material.

[0109] Application Example 3

[0110] 0.5 kg of fireworks and firecracker production waste residue was mixed with 1.5 kg of aluminum ash residue. The fireworks and firecracker waste residue contained 15% potassium perchlorate, 9% magnesium aluminum powder, 27% magnesite, 25% dolomite, 5% quartz, and 1.2% sulfur. The aluminum ash residue contained 13% metallic aluminum, 1.8% aluminum nitride, 35% alumina, and 4% magnesium oxide. 10% liquid alkali and water were added to the mixture. The liquid-to-solid ratio was 4:1, the pH was 12.5, and the reaction temperature was 70℃. Air was blown into the mixture during the reaction. After the reaction, the solid and liquid were separated. The residue did not contain metallic aluminum, aluminum nitride, sulfur, or perchlorate. The leaching residue was washed with water to remove residual soluble salts. The resulting filter residue contained 16% Al2O3, 35% CaO, and 18% SiO2, and could be used as a building material raw material. The resulting washing liquid was returned to the alkaline leaching process. Hydrochloric acid and SO2 generated during the alkaline leaching process are added to the leachate to neutralize its pH to 7. Solid-liquid separation is then performed, and the resulting precipitate contains 78.7% Al2O3, which can be used as a raw material in aluminum metallurgy. 0.2% sodium sulfide and 2% sodium carbonate are added to the post-aluminum precipitation solution, and solid-liquid separation is performed. The resulting precipitate contains 47% CaO, which can be returned to the sintering aluminum smelting process. The resulting filtrate is evaporated using a triple-effect countercurrent evaporation system to produce sodium chloride. The resulting sodium mother liquor is flash-cooled to obtain potassium chloride. The purity of the sodium chloride product is 91.7%, and the purity of the potassium chloride product is 92.5%.

Claims

1. A method for the co-processing of waste residue from fireworks and firecracker production and aluminum ash residue, characterized in that, The method includes the following steps: S1. Mix the waste residue from fireworks and firecracker production with aluminum ash residue, stir evenly to obtain a mixture; S2. Add alkaline solution to the mixture to carry out the reaction, during which SO2 gas is released; S3. The reacted slurry is subjected to solid-liquid separation to obtain leachate and leachate residue; S4. The SO2 gas released in step S2 is introduced into the leachate obtained in step S3, the pH is adjusted, and solid-liquid separation is performed to obtain aluminum-rich slag and aluminum-removing liquid. S5. The aluminum removal liquid is subjected to heavy and hard removal treatment, and solid-liquid separation is performed to obtain purified residue and purified liquid. S6. Perform triple-effect countercurrent evaporation on the purified liquid to obtain sodium chloride, condensate and sodium mother liquor; S7. Flash-cool the sodium mother liquor to obtain potassium chloride and potassium mother liquor. Return the potassium mother liquor to step S2 for slurry preparation. S8. Mix the condensate obtained in step S6 with the leaching residue obtained in step S3, slurry and wash, and separate the solid and liquid to obtain washing liquid and washing residue. The washing liquid is returned to step S2 for slurry preparation.

2. The method according to claim 1, characterized in that, In step S1, the mixing weight ratio of fireworks and firecracker production waste residue to aluminum ash residue is 0.1~0.4:

1.

3. The method according to claim 1, characterized in that, In step S2, the added alkaline solution is at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate: and / or The concentration of the added alkali solution is 5-20%; and / or The amount of alkali solution added is enough to raise the pH of the solution to above 12.

4. The method according to claim 1, characterized in that, In step S2, the reaction temperature is 20~80℃, preferably 60~80℃, and the liquid-solid ratio is 3~8:1, preferably 3~6:1; Preferably, the reaction system is aerated during the reaction process; the aerated gas is air.

5. The method according to claim 1, characterized in that, The solid-liquid separation is performed by filtration, pressure filtration, vacuum filtration, or centrifugation.

6. The method according to claim 1, characterized in that, In step S4, adjusting the pH specifically involves using hydrochloric acid to adjust the pH of the leachate to 6-8; preferably, the concentration of hydrochloric acid is 5-20%; and / or The resulting aluminum-rich slag is used as a raw material for aluminum smelting.

7. The method according to claim 1, characterized in that, In step S5, the de-weighting and de-hardening treatment specifically involves adding a softener and a de-weighting agent to the aluminum removal liquid and stirring to carry out the reaction. Preferably, the softener is sodium carbonate; the amount of softener added is 0.1-10% of the solution weight; the deweighting agent is at least one of sodium sulfide, organic sulfur, and calcium polysulfide; the amount of deweighting agent added is 0.1-10% of the solution weight.

8. The method according to claim 1, characterized in that, The purified residue obtained in step S5 is a mixture of calcium carbonate and heavy metal sulfides; it is used as an additive in sintering aluminum smelting.

9. The method according to claim 1, characterized in that, In step S6, the triple-effect countercurrent evaporation specifically involves passing the purified liquid sequentially through a triple-effect reactor, a second-effect reactor, and a first-effect reactor. The temperature in the triple-effect reactor is 20–60°C (preferably 30–50°C), the temperature in the second-effect evaporation is 40–90°C (preferably 50–80°C), and the temperature in the first-effect evaporation is 70–105°C (preferably 80–100°C). Condensate is obtained during the evaporation process. After concentration, the purified liquid is discharged from the first-effect reactor into a thickener, producing sodium chloride crystals and sodium mother liquor.

10. The method according to claim 1, characterized in that, In step S7, the flash cooling specifically involves processing the sodium mother liquor through a flash evaporator, controlling the negative pressure of the flash evaporator to be greater than 85 kPa, and the flash temperature to be 40~80℃; and / or The water-washed residue obtained in step S8 is used as a building material raw material.

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