Method for regenerating aluminum material chemical polishing waste liquid

Abstract

The present application relates to the technical field of hydrometallurgy and waste acid resource processing, and particularly relates to a regeneration method of aluminum material chemical polishing waste liquid. The present application is based on organic complex precipitation method, and specific organic complexing agent is used to regenerate the aluminum material chemical polishing waste liquid, so that aluminum ions are efficiently removed from the aluminum material chemical polishing waste liquid, and phosphoric acid and sulfuric acid are recovered, the dual goals of efficient aluminum removal and acid recovery are achieved, and the defects of introducing fluorine ions, high cost and complex operation of the existing method are overcome. The regeneration method provided by the present application has a single-stage aluminum removal rate of 75% to 82% for the aluminum material chemical polishing waste liquid with an aluminum ion concentration of 3 to 10 g / L, and the two-stage precipitation rate is above 85% if two-stage precipitation is performed, fluorine ions are not introduced, acid loss is small, operation is simple, the precipitation product can be resourcefully utilized, and the method is suitable for waste acid recovery and regeneration in the aluminum profile processing industry.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgy and waste acid resource utilization technology, and in particular to a method for regenerating waste liquid from chemical polishing of aluminum materials. Background Technology

[0002] During the chemical polishing process of aluminum profiles, aluminum ions continuously accumulate in the polishing solution. When the concentration of aluminum ions reaches 5-12 g / L, the polishing ability of the polishing solution decreases significantly, forming aluminum-containing waste acid. This type of waste acid typically contains 60%-70% phosphoric acid, 20%-30% sulfuric acid, and dissolved aluminum ions (Al). 3+ (and metal salts.) Direct discharge would not only pollute the environment but also waste valuable resources such as phosphoric acid and sulfuric acid.

[0003] Initially, acidic polishing slurries were mixtures of three strong acids: sulfuric acid, nitric acid, and phosphoric acid. Nitric acid played a major role in oxidation, while sulfuric acid acted primarily as an oxidizing agent and activator. Phosphoric acid and the aluminum phosphate produced in subsequent reactions mainly increased the viscosity of the polishing slurry. A high-viscosity slurry could reduce the corrosion rate of metal surfaces, preventing excessive corrosion that could damage metal components. With increasingly stringent environmental protection requirements, acidic polishing slurries gradually evolved into diacid polishing slurries, namely a mixture of phosphoric acid and sulfuric acid.

[0004] Currently, common technologies for recovering polishing waste acid include crystallization, solvent extraction, chemical precipitation, resin exchange, and membrane methods. Among these, crystallization is a method of removing impurities by separating and crystallizing the solubility of a particular solvent in a mixed solvent, or the solubility difference at different temperatures. It analyzes the different solubilities of aluminum ions, phosphate ions, nitrate ions, etc., in the waste liquid at different temperatures or concentrations, thereby crystallizing out aluminum ions and removing them from the solution. While crystallization can separate high concentrations of phosphoric acid and sulfuric acid solutions, it usually involves complex operating conditions, a long processing time, and is highly sensitive to other impurity elements (such as Fe, Si, Pb, or Zn), thus limiting its applicability.

[0005] Solvent extraction utilizes the difference in solubility of a compound in two immiscible or slightly soluble solvents to transfer it from one solvent to another. This process involves multiple extractions to separate the compound from other substances. However, this method requires multiple extractions to obtain a high-concentration acid solution, and the extractant must be properly treated.

[0006] Chemical precipitation involves reacting certain compounds with impurity ions in a solution to produce a precipitate, which is then separated by filtration. While this method offers advantages such as simple operation and high aluminum ion removal rates, it also increases the number of ions that need to be treated, requiring the removal of most fluoride ions and thus raising processing costs.

[0007] The principle of resin exchange is to exchange functional groups on the resin, usually acidic groups, with aluminum ions in the solution through ion exchange. This method can precisely remove aluminum ions from the solution, and the use of sulfonic acid resins does not introduce other impurities into the solution. However, the resin needs to be regenerated after use, and the regeneration cost is usually high, and the resin processing capacity is also limited.

[0008] Membrane methods are a relatively new treatment approach that works by using special membranes to selectively trap unwanted ions under acidic conditions in acidic polishing solutions. However, the membrane surface needs to be cleaned and maintained after use.

[0009] Therefore, developing a new method for regenerating chemical polishing waste liquid that is fluorine-free, cost-effective, easy to operate, and can effectively recover acid liquid has significant industrial application value. Summary of the Invention

[0010] In view of this, the present invention provides a method for regenerating aluminum chemical polishing waste liquid. The regeneration method provided by the present invention achieves the dual goals of efficient aluminum removal and acid recovery, overcoming the shortcomings of existing methods such as the introduction of fluoride ions, high cost and complicated operation.

[0011] This invention provides a method for regenerating waste liquid from chemical polishing of aluminum materials, comprising the following steps: (1) After mixing aluminum chemical polishing waste liquid and organic complexing agent to carry out complexation precipitation reaction, solid-liquid separation is performed to obtain acid liquid and complex precipitate; (2) The acid solution is evaporated, concentrated and mixed in sequence to obtain the regenerated polishing solution.

[0012] Preferably, the organic complexing agent includes benzoic acid (C6H5COOH), terephthalic acid (C8H6O4), cyclohexanecarboxylic acid, and salicylic acid; the mass ratio of benzoic acid to terephthalic acid is 1:1~3; the mass ratio of benzoic acid to cyclohexanecarboxylic acid is 1:1~5; and the mass ratio of benzoic acid to salicylic acid is 1:1~3.

[0013] Preferably, the molar ratio of the organic complexing agent to aluminum ions in the chemical polishing waste liquid of aluminum material is 1:2~5.

[0014] Preferably, the temperature for the complexation precipitation reaction is 50-70 degrees Celsius, and the time is 30-90 minutes.

[0015] Preferably, the solid-liquid separation is performed by vacuum filtration or plate and frame filtration.

[0016] Preferably, the evaporation concentration is mechanical vapor recompression evaporation or negative pressure evaporation concentration; the pressure of negative pressure evaporation concentration is -0.10 to -0.09 MPa; the temperature of evaporation compression is 60 to 90 degrees Celsius, and the time is 11 to 13 hours.

[0017] Preferably, the formulation is determined based on the composition of the acid solution after evaporation and concentration, as well as the usage requirements of the chemical polishing solution.

[0018] Preferably, after obtaining the complex precipitate, the complex precipitate can be acid-hydrolyzed to obtain a regenerated organic complexing agent.

[0019] Preferably, the acid used for acidolysis is sulfuric acid; the acidolysis temperature is 68~72 degrees Celsius, and the time is 2~4 hours.

[0020] Preferably, after obtaining the complex precipitate, the complex precipitate can be calcined to obtain an aluminum-based material.

[0021] Compared with the prior art, the present invention has achieved the following beneficial effects: This invention is based on the organic complexation precipitation method, which uses a specific organic complexing agent to regenerate the chemical polishing waste liquid of aluminum materials. It efficiently removes aluminum ions from the chemical polishing waste liquid of aluminum materials and recovers phosphoric acid and sulfuric acid, achieving the dual goals of efficient aluminum removal and acid recovery. It overcomes the shortcomings of existing methods, such as the introduction of fluoride ions, high cost and complicated operation.

[0022] The regeneration method provided by this invention achieves a single-stage aluminum removal rate of 75% to 82% for aluminum chemical polishing waste liquid with an aluminum ion concentration of 3 to 10 g / L. With secondary precipitation, the removal rate exceeds 85%, and no fluoride ions are introduced. Acid loss is minimal, the operation is simple, and the precipitated products can be utilized as resources. This method is suitable for waste acid recovery and regeneration in the aluminum profile processing industry. Specifically, this invention has the following advantages: (1) The regeneration method provided by the present invention has high aluminum removal efficiency. For aluminum chemical polishing waste liquid with aluminum ion concentrations of 3.06 g / L, 6.5 g / L and 9.43 g / L, the single-stage precipitation aluminum removal rate reaches 75.2%, 82.3% and 79.8% respectively. The present invention can further introduce secondary precipitation, and the total aluminum removal rate can be increased to more than 85% through secondary precipitation.

[0023] (2) The regeneration method provided by the present invention has low acid loss. During the precipitation process, the loss rate of phosphoric acid is no higher than 17.4% and the loss rate of sulfuric acid is no higher than 17.8%. During the concentration process, the acid loss rate is further reduced to less than 10%.

[0024] (3) The regeneration method provided by the present invention is free of fluorine, which can effectively solve the problems of fluoride corrosion of equipment and the burden on subsequent wastewater treatment caused by fluoride in the traditional precipitation method.

[0025] (4) The regeneration method provided by the present invention is simple to operate, requires no extractant, ion exchange resin or special membrane equipment, has low investment cost and threshold, and has broad industrialization prospects.

[0026] (5) The regeneration method provided by the present invention can realize resource utilization. The precipitated product can be acid-hydrolyzed to recycle the organic complexing agent, or calcined to prepare alumina, thus realizing the whole process of resource recovery. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of this invention, the accompanying drawings used in the embodiments of this invention or in the prior art are briefly described below. For those skilled in the art, other drawings can be derived from the following drawings without creative effort, and all such drawings are within the protection scope of this invention.

[0028] Figure 1 A schematic diagram of the process flow for the regeneration method of aluminum chemical polishing waste liquid provided by the present invention; Figure 2 The graph shows the effect of benzoic acid, terephthalic acid, cyclohexane, and salicylic acid on the removal efficiency of aluminum ions at different mixing ratios. Figure 3 This is a mass balance diagram of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 3.06 g / L after being treated by the regeneration method of this invention. Figure 4 This is a mass balance diagram of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 6.5 g / L after being treated by the regeneration method of this invention. Figure 5 This is a mass balance diagram of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 9.43 g / L after being treated by the regeneration method of this invention. Detailed Implementation

[0029] This invention provides a method for regenerating waste liquid from chemical polishing of aluminum materials, comprising the following steps: (1) After mixing aluminum chemical polishing waste liquid and organic complexing agent to carry out complexation precipitation reaction, solid-liquid separation is performed to obtain acid liquid and complex precipitate; (2) The acid solution is evaporated, concentrated and mixed in sequence to obtain the regenerated polishing solution.

[0030] This invention involves mixing aluminum chemical polishing waste liquid with an organic complexing agent, performing a complexation precipitation reaction, and then separating the solid and liquid phases to obtain an acid solution and a complex precipitate. In this invention, the organic complexing agent may include benzoic acid (C6H5COOH), terephthalic acid (C8H6O4), cyclohexanecarboxylic acid, and salicylic acid; the mass ratio of benzoic acid to terephthalic acid can be 1:1 to 3, specifically 1:2; the mass ratio of benzoic acid to cyclohexanecarboxylic acid can be 1:1 to 5, specifically 1:2, 1:3, or 1:4; the mass ratio of benzoic acid to salicylic acid can be 1:1 to 3, specifically 1:2.

[0031] In this invention, the molar ratio of the organic complexing agent to aluminum ions in the aluminum chemical polishing waste liquid can be 1:2 to 5, specifically 1:3 or 1:4.

[0032] In this invention, the temperature of the complexation precipitation reaction can be 50-70 degrees Celsius, specifically 55 degrees Celsius, 60 degrees Celsius, or 65 degrees Celsius, and the time can be 30-90 minutes, specifically 50 minutes or 70 minutes. During the complexation precipitation reaction, aluminum ions in the aluminum chemical polishing waste liquid react with the organic complexing agent to form an insoluble complex.

[0033] In this invention, solid-liquid separation can be achieved through vacuum filtration or plate and frame filtration. This invention separates the generated complex precipitate (aluminum-organic acid) using either vacuum filtration or plate and frame filtration.

[0034] After obtaining the acid solution and the complex precipitate, the present invention sequentially evaporates, concentrates, and adjusts the acid solution to obtain a regenerated polishing solution. In the present invention, the evaporation and concentration can be mechanical vapor recompression evaporation or negative pressure evaporation and concentration; the pressure of negative pressure evaporation and concentration can be -0.10 to -0.09 MPa; the temperature of evaporation and compression can be 60 to 90 degrees Celsius, specifically 70 degrees Celsius or 80 degrees Celsius, and the time can be 11 to 13 hours, specifically 12 hours.

[0035] In this invention, the formulation can be determined based on the composition of the concentrated acid solution and the usage requirements of the chemical polishing solution. Through formulation, this invention yields a reusable recycled polishing solution.

[0036] After obtaining the acid solution and the complex precipitate, the present invention can further acid-hydrolyze the complex precipitate to obtain a regenerated organic complexing agent; or, calcine the complex precipitate to obtain an aluminum-based material.

[0037] This invention involves acid hydrolysis of a complex precipitate to obtain a regenerated organic complexing agent. In this invention, prior to acid hydrolysis, the complex precipitate may also be subjected to sequential water washing and drying; the water used for washing may be deionized water.

[0038] In this invention, the drying temperature can be 40-60 degrees Celsius, specifically 50 degrees Celsius, and the drying time can be more than 1 hour.

[0039] In this invention, the acid used for acidolysis can be sulfuric acid; the acidolysis temperature can be 68-72 degrees Celsius, specifically 70 degrees Celsius, and the time can be 2-4 hours, specifically 3 hours. This invention obtains a regenerated chemical polishing solution through acidolysis.

[0040] Alternatively, the present invention calcines the complex precipitate to obtain an aluminum-based material. In this invention, the process may further include washing and drying the complex precipitate sequentially with water before calcination; the water used for washing may be deionized water.

[0041] In this invention, the drying temperature can be 40-60 degrees Celsius, specifically 50 degrees Celsius, and the drying time can be more than 1 hour.

[0042] In this invention, the calcination temperature can be 590~610 degrees Celsius, specifically 600 degrees Celsius, and the time can be 2~4 hours, specifically 3 hours. This invention, through calcination, yields aluminum-based materials (alumina).

[0043] like Figure 1 As shown, the method for regenerating aluminum chemical polishing waste liquid provided by the present invention includes, in sequence, a complexation precipitation reaction, solid-liquid separation, acid evaporation concentration and preparation, and resource utilization treatment of complex precipitation. Specifically, an organic complexing agent is added to the aluminum chemical polishing waste liquid to carry out a complexation precipitation reaction, so that Al 3+ A sparingly soluble aluminum-organic acid complex precipitate is formed; then solid-liquid separation is performed, the resulting acid solution (filtrate) is concentrated by evaporation, and the components are adjusted according to the usage requirements of the chemical polishing solution to obtain a regenerated chemical polishing solution. The complex precipitate is then recycled through calcination or acid hydrolysis.

[0044] In this invention, the aluminum removal rate is calculated according to Formula 1: Aluminum removal rate = [(C0-C1) / C0]×100% (Equation 1) Wherein, C0 is the aluminum ion concentration in the aluminum chemical polishing waste liquid before treatment, and C1 is the aluminum ion concentration in the acid solution obtained from solid-liquid separation.

[0045] To further illustrate the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0046] In a specific embodiment of the present invention, the aluminum chemical polishing waste liquid is aluminum profile polishing waste acid and electronic factory polishing waste acid, and the specific components are shown in Table 1.

[0047] Table 1. Composition and content of waste liquid from chemical polishing of aluminum materials: Unless otherwise stated, each group of experiments was conducted in triplicate.

[0048] Example 1: (1) Complexation precipitation reaction: Add an organic complexing agent to the aluminum chemical polishing waste liquid. The organic complexing agent is a mixture of benzoic acid, terephthalic acid, cyclohexane, and salicylic acid, wherein the mass ratio of benzoic acid, terephthalic acid, cyclohexane, and salicylic acid is 1:1.2:1.5:1.5. The amount of organic complexing agent added is calculated based on the aluminum ion content in the aluminum chemical polishing waste liquid, so that the molar ratio of benzoic acid, cyclohexane, and salicylic acid to aluminum ions is 1:3, and the molar ratio of terephthalic acid to aluminum ions is 1:2. The complexation precipitation reaction is carried out at a temperature of 70 degrees Celsius for 45 minutes.

[0049] (2) Solid-liquid separation: The system after the complex precipitation reaction is filtered to obtain acid solution and complex precipitate.

[0050] (3) Acid concentration: The acid solution is evaporated and concentrated at 60 degrees Celsius and -0.10~-0.09 MPa for 12 hours, and then mixed to obtain a regenerated chemical polishing solution.

[0051] Example 2: The regeneration method in this embodiment is the same as that in Example 1, except that the mass ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid is adjusted to 1:1.5:1.5:1.5.

[0052] Example 3: The regeneration method in this embodiment is the same as that in Example 1, except that the mass ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid is adjusted to 1:1:1.5:1.5.

[0053] Comparative Example 1: The regeneration method in this comparative example is the same as that in Example 1, except that the mass ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid is adjusted to 1.5:1:1.5:1.5.

[0054] Comparative Example 2: The regeneration method in this comparative example is the same as that in Example 1, except that the mass ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid is adjusted to 1.2:1:1.5:1.5.

[0055] Test Example 1: The aluminum ion concentration of the acid solutions from Examples 1-3 and Comparative Examples 1-2 was tested, and the aluminum removal rate was calculated. The results are as follows: Figure 2 As shown. Figure 2 The bar chart corresponds to the remaining aluminum ion concentration in the acid solution, and the line chart corresponds to the aluminum ion removal rate.

[0056] according to Figure 2 It can be seen that the ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid, and salicylic acid significantly affects the complexation and precipitation effect of aluminum ions. With changes in the mixing ratio, the average removal rate of aluminum ions increased from 68.93% to 81.11%, then decreased to 71.58%, with the remaining aluminum ion concentration in the acid solution below 5 g / L, allowing for recovery through evaporation and concentration. In comparison, the aluminum removal effect was superior when the mass ratio of benzoic acid, terephthalic acid, cyclohexanecarboxylic acid, and salicylic acid in Example 1 was 1:1.2:1.5:1.5.

[0057] Example 4: In this embodiment, aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 3.06 g / L is used for regeneration: (1) Complexation precipitation reaction: Take 1 ton of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 3.06 g / L, sulfuric acid of 56.23 g / L, and phosphoric acid of 87.47 g / L and place it in a reactor. Mix benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid in a mass ratio of 1:1.2:1.5:1.5 to prepare an organic complexing agent. The molar ratio of benzoic acid, cyclohexanecarboxylic acid and salicylic acid to aluminum ions is 1:3, and the molar ratio of terephthalic acid to aluminum ions is 1:2. Stir the reaction at 70 degrees Celsius for 45 minutes.

[0058] (2) Solid-liquid separation: After the complex precipitation reaction is completed, the generated complex precipitate is separated by vacuum filtration and the acid solution is collected.

[0059] (3) Acid analysis and concentration: The aluminum ion concentration of the acid solution was reduced to 0.76 g / L, and the aluminum removal rate was 82.3%; the concentration of sulfuric acid was 56.22 g / L, and the concentration of phosphoric acid was 91.63 g / L. The acid solution was evaporated and concentrated at 60°C and -0.10 to -0.09 MPa for 12 hours. The resulting concentrate had an aluminum ion concentration of 3.82 g / L, a sulfuric acid concentration of 453.99 g / L, and a phosphoric acid concentration of 891.31 g / L. Based on the requirements of the "Standard for Acids for Aluminum Chemical Polishing" (T / NBEA 002—2019)—phosphoric acid (calculated as H3PO4) ≥55%, sulfuric acid (calculated as H2SO4) ≥43%, and aluminum (Al) ≤1.00%—221.3 g (approximately 135 mL) of 98% concentrated sulfuric acid was added per liter to obtain the regenerated chemical polishing solution. The final composition of this solution was: phosphoric acid 55.00%, sulfuric acid 43.00%, water approximately 2.0%, and aluminum ions approximately 0.2%, meeting the standard requirements. The overall process mass balance in this embodiment is as follows: Figure 3 As shown, the distribution and recovery of aluminum, sulfuric acid, and phosphoric acid at each stage are illustrated.

[0060] (4) Precipitate treatment: The collected complex precipitate was washed with deionized water, dried at 50 degrees Celsius for 1 hour, and then calcined at 600 degrees Celsius for 3 hours to obtain alumina.

[0061] Example 5: The regeneration method in this embodiment is the same as that in embodiment 4. The difference is that in step (4), the collected complex precipitate is washed with deionized water, dried at 50 degrees Celsius for 1 hour, and then acidified at 70 degrees Celsius (sulfuric acid) for 3 hours to recover the organic complexing agent for recycling.

[0062] Example 6: In this embodiment, aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 6.50 g / L is used for regeneration: (1) Complexation precipitation reaction and solid-liquid separation: Take 1 ton of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 6.5 g / L, sulfuric acid of 127.03 g / L, and phosphoric acid of 274.89 g / L and place it in a reactor. Mix benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid in a mass ratio of 1:1.2:1.5:1.5 to prepare an organic complexing agent. The molar ratio of benzoic acid, cyclohexanecarboxylic acid and salicylic acid to aluminum ions is 1:3, and the molar ratio of terephthalic acid to aluminum ions is 1:1. The reaction is carried out at 70 degrees Celsius with constant stirring for 45 minutes. The precipitate is separated by filtration to obtain the complex precipitate and acid solution.

[0063] Test results showed that the aluminum ion concentration in the acid solution decreased to 1.15 g / L, with an aluminum removal rate of 82.3%; the concentration of sulfuric acid was 142.30 g / L, and the concentration of phosphoric acid was 280.45 g / L.

[0064] (2) The acid solution was evaporated and concentrated at 60°C and -0.10~-0.09MPa for 12 hours. The resulting concentrate had an aluminum ion concentration of 3.06 g / L, a sulfuric acid concentration of 578.94 g / L, and a phosphoric acid concentration of 987.11 g / L. Based on the requirements of the "Standard for Acids for Aluminum Chemical Polishing" (T / NBEA 002—2019) (phosphoric acid (calculated as H3PO4) ≥ 55%, sulfuric acid (calculated as H2SO4) ≥ 43%, and aluminum (Al) ≤ 1.00%), 168.1 g of 98% concentrated sulfuric acid was added per liter to obtain the regenerated chemical polishing solution. The final composition of this solution was 55.00% phosphoric acid, 43.00% sulfuric acid, approximately 2.0% water, and approximately 0.2% aluminum ions, meeting the standard requirements. The corresponding overall process mass balance is as follows: Figure 4 As shown.

[0065] Example 7: In this embodiment, aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 9.43 g / L is used for regeneration: (1) Complexation precipitation reaction and solid-liquid separation: Take 1 ton of aluminum chemical polishing waste liquid with an initial aluminum ion concentration of 9.43 g / L, sulfuric acid of 222.83 g / L, and phosphoric acid of 320.71 g / L. Mix benzoic acid, terephthalic acid, cyclohexanecarboxylic acid and salicylic acid in a mass ratio of 1:1.2:1.5:1.5 to obtain an organic complexing agent. The molar ratio of benzoic acid, cyclohexanecarboxylic acid and salicylic acid to aluminum ions is 1:3, and the molar ratio of terephthalic acid to aluminum ions is 1:1. The reaction is carried out at a constant temperature of 70 degrees Celsius and stirred for 45 minutes. The precipitate is separated by filtration to obtain the complex precipitate and acid solution.

[0066] Test results showed that the aluminum ion concentration in the acid solution decreased to 1.15 g / L, with an aluminum removal rate of 82.3%; the concentration of sulfuric acid was 220.75 g / L, and the concentration of phosphoric acid was 320.17 g / L.

[0067] (2) The acid solution was evaporated and concentrated at 60°C and -0.10~-0.09 MPa for 12 hours. The resulting concentrate had an aluminum ion concentration of 2.68 g / L, a sulfuric acid concentration of 608.09 g / L, and a phosphoric acid concentration of 833.00 g / L. Based on the requirements of the "Standard for Acids for Aluminum Chemical Polishing" (T / NBEA 002—2019) (phosphoric acid (calculated as H3PO4) ≥ 55%, sulfuric acid (calculated as H2SO4) ≥ 43%, and aluminum (Al) ≤ 1.00%), 43.3 g of 98% concentrated sulfuric acid was added per liter to obtain the regenerated chemical polishing solution. The final composition was 55.00% phosphoric acid, 43.00% sulfuric acid, approximately 2.0% water, and approximately 0.13% aluminum ions, meeting the standard requirements. The corresponding overall process mass balance is as follows: Figure 5 As shown.

[0068] comprehensive Figures 3-5 The mass balance results shown indicate that when using the regeneration method provided by this invention to treat aluminum chemical polishing wastewater, aluminum ions can be separated from the acid solution along with the complex precipitation, while phosphoric acid and sulfuric acid are mainly retained in the acid solution. During the complex precipitation reaction, the loss rate of phosphoric acid is no higher than 17.4%, and the loss rate of sulfuric acid is no higher than 17.8%. After evaporation, concentration, and blending, the chemical polishing agent can be recovered and recycled, while avoiding the introduction of fluoride ions into the system.

[0069] The embodiments of the present invention have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the above embodiments of the present invention without inventive effort are within the protection scope of the present invention.

Claims

1. A method for regenerating waste liquid from chemical polishing of aluminum materials, characterized in that, Includes the following steps: (1) The aluminum chemical polishing waste liquid and organic complexing agent are mixed and subjected to complexation precipitation reaction, followed by solid-liquid separation to obtain acid liquid and complex precipitate; the organic complexing agent includes benzoic acid, terephthalic acid, cyclohexane, and salicylic acid; (2) The acid solution is evaporated, concentrated and mixed in sequence to obtain the regenerated polishing solution.

2. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, The mass ratio of benzoic acid to terephthalic acid is 1:1~3; the mass ratio of benzoic acid to cyclohexanecarboxylic acid is 1:1~5; and the mass ratio of benzoic acid to salicylic acid is 1:1~3.

3. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, The molar ratio of the organic complexing agent to aluminum ions in the chemical polishing waste liquid of aluminum materials is 1:2~5.

4. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, The temperature for the complexation precipitation reaction is 50-70 degrees Celsius, and the time is 30-90 minutes.

5. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, Evaporation concentration is performed by mechanical vapor recompression evaporation or negative pressure evaporation concentration; the pressure for negative pressure evaporation concentration is -0.10 to -0.09 MPa; the temperature for evaporation compression is 60 to 90 degrees Celsius, and the time is 11 to 13 hours.

6. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, After obtaining the complex precipitate, the complex precipitate can be acid-hydrolyzed to obtain a regenerated organic complexing agent.

7. The method for regenerating aluminum chemical polishing waste liquid according to claim 6, characterized in that, The acid used for acidolysis is sulfuric acid; the acidolysis temperature is 68~72 degrees Celsius, and the time is 2~4 hours.

8. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, After obtaining the complex precipitate, the complex precipitate can be calcined to obtain aluminum-based materials.

9. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, Solid-liquid separation is achieved by vacuum filtration or plate and frame filtration.

10. The method for regenerating aluminum chemical polishing waste liquid according to claim 1, characterized in that, The formulation is determined based on the composition of the acid solution after evaporation and concentration, as well as the usage requirements of the chemical polishing solution.

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