A method for treating waste vitamin a sulfuric acid

Abstract

The application discloses a treatment method of waste sulfuric acid of vitamin A, and comprises the following steps: extracting the waste sulfuric acid of vitamin A by using a mixed extractant, and standing and separating; evaporating and concentrating the waste sulfuric acid liquid layer, and reusing the concentrated waste acid after treatment by using an oxidizing agent and an adsorbent; twice flash evaporation of the extractant layer; and reusing the obtained extractant after supplementing a formula. The application can comprehensively treat the waste sulfuric acid in the production process of vitamin A, solve the problem of difficult treatment of COD, achieve the purpose of emission reduction, save investment cost and waste disposal cost, and reuse the treated waste sulfuric acid and extractant, so that the resource utilization of waste is realized.

Description

Technical Field

[0001] This invention relates to a method for treating waste sulfuric acid containing vitamin A, and more particularly to a method for deep treatment of waste sulfuric acid containing vitamin A and the resource recycling of raw materials, belonging to the field of resource-based disposal and reuse of industrial waste sulfuric acid. Background Technology

[0002] Sulfuric acid is an essential substance in industrial production processes worldwide. However, the disposal of waste sulfuric acid generated during these processes, often used as a raw material or catalyst, presents a significant challenge. Faced with ever-increasing demand, the amount of waste sulfuric acid produced is growing daily. Within chemical industrial parks, most waste sulfuric acid requires outsourcing for specialized treatment.

[0003] Currently, the main methods for treating waste sulfuric acid in the industry are adsorption, chemical oxidation, and incineration pyrolysis. Adsorption is mainly used to remove organic matter from waste sulfuric acid, but the equipment used is large, the adsorbent has limited adsorption capacity, and the adsorbent is expensive to use and cannot be recycled after being contaminated. Chemical oxidation and incineration pyrolysis are cumbersome to treat waste sulfuric acid, have low efficiency in treating organic matter, and require high equipment construction and costs.

[0004] For vitamin A products, the preparation process typically employs BASF technology: using β-ionone as a raw material, vitamin A is produced through Grignard reaction, Wittig reaction, and cyclization reaction. Concentrated sulfuric acid, as the catalytic atmosphere for the cyclization reaction, is required in large quantities, and the process involves complex and diverse side reactions. The organic matter mainly includes ionone, acetone, tar, and other intermediate byproducts. Therefore, the production process generates large quantities of waste sulfuric acid, which is difficult to treat and has high outsourcing disposal costs. This not only consumes significant amounts of raw material and waste disposal costs but also poses significant safety hazards during transportation.

[0005] The pollutants in waste sulfuric acid from vitamin A are complex, and there is limited research on it. The treatment methods suitable for this waste acid differ from those for other types of waste acid and need to be tailored to local conditions. This is an urgent problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a method for treating waste sulfuric acid containing vitamin A. Through simple, efficient, and low-cost treatment methods such as extraction, evaporation concentration, and adsorption oxidation, it is possible to treat large quantities of complex pollutants in waste sulfuric acid containing vitamin A. This provides a treatment method for waste acid produced in the vitamin A industry chain and successfully solves the current problem of treating waste sulfuric acid containing vitamin A.

[0007] The vitamin A waste sulfuric acid refers to the waste sulfuric acid generated during the preparation of vitamin A from β-ionone through Grignard reaction, Wittig reaction and cyclization reaction. It usually contains organic matter such as ionone, acetone, tar and other intermediate products.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] S1. Add a mixed extractant to the waste sulfuric acid containing vitamin A for extraction and separate the solutions. The upper layer is a mixed solution of the extractant and organic matter in the waste acid, and the lower layer is the waste acid solution.

[0010] S2. The waste acid solution separated in S1 is evaporated and concentrated at high temperature to obtain concentrated waste sulfuric acid;

[0011] S3. Add hydrogen peroxide and adsorbent to the concentrated waste sulfuric acid in S2, oxidize it at high temperature and further concentrate it.

[0012] Furthermore, the method also includes:

[0013] S4. Flash evaporate the extractant layer mixture separated in S1, and then flash evaporate the solution again.

[0014] S5. The extraction solvent obtained from the secondary flash evaporation in S4 can be re-adjusted and reused.

[0015] In the method of the present invention, in step S1, the mixed extractant includes n-butanol, n-butyl ether, and trimethyl phosphate; after n-butanol and n-butyl ether are mixed in a mass ratio of 3:1 to 1:1, trimethyl phosphate is added at a mass ratio of 1% to 3% (based on the sum of the masses of n-butanol and n-butyl ether) and mixed evenly; studies have found that the mixed extractant of the present invention has a very strong extraction effect on organic substances such as ionone and tar in vitamin A waste sulfuric acid, and its solubility in waste sulfuric acid is 1% to 3%. Compared with single n-butanol or n-butyl ether and other extractants, the extraction efficiency of this extractant is 3 to 5 times that of single extractants, and the solubility is reduced by nearly 3 to 5%.

[0016] The mass ratio of waste sulfuric acid to mixed extractant for vitamin A is 7:1-3:1.

[0017] In the method of the present invention, in step S2, the evaporation and concentration temperature is 120-190°C and the evaporation and concentration time is 1-3 hours; through the evaporation and concentration operation, acetone, alcohols and other light organic components that are easily soluble in water can be removed from waste sulfuric acid.

[0018] In the method of the present invention, in step S3, the concentration of hydrogen peroxide added is 27.5-30 wt%, and the amount added is 0.5%-2.5% of the initial waste sulfuric acid mass;

[0019] The adsorbent used is silica adsorbent, and the amount added is 0.5%-3% of the initial waste sulfuric acid mass;

[0020] The oxidation and concentration temperature is 150-230℃, and the reaction time is 1-3 hours.

[0021] After the above reaction is completed, the resulting waste sulfuric acid is clear and transparent, and the TOC of the waste sulfuric acid is reduced to 100-200 mg / L, which can be reused as a catalyst in the VA production process.

[0022] In the method of the present invention, in step S4, the flash evaporation temperature is 85-105°C, and the flash evaporation time is 15-45 min.

[0023] The extraction flash distillate was a mixed solution of n-butanol, butyl ether and a small amount of organic matter, with trimethyl phosphate and a large amount of undistilled organic matter at the bottom;

[0024] The secondary flash evaporation temperature is 50-70℃, the duration is 15-45 min, and the mixed extraction solvent containing n-butanol and butyl ether is retained at the bottom;

[0025] After S4 treatment, a mixed extractant containing n-butanol and butyl ether can be obtained, allowing n-butanol and butyl ether to be recycled.

[0026] In the method of the present invention, n-butanol, butyl ether, and trimethyl phosphate can be added in proportion during step S5, and then used as an extractant.

[0027] The beneficial effects of this invention are as follows: the method of this invention is simple, has a good effect on the treatment of organic matter, and has a high degree of industrial safety; the mixed extractant has a strong extraction effect on organic matter such as ionone and tar in vitamin A waste sulfuric acid, and its solubility in waste sulfuric acid is 1%-3%. The waste sulfuric acid treatment method is convenient, reliable, has a high recovery rate and low treatment cost, and is suitable for the purification of vitamin A waste sulfuric acid system. Detailed Implementation

[0028] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are only for illustrative purposes, but the scope of protection of the present invention is not limited to the following description.

[0029]

Example 1

[0030] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0031] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:1 to obtain a mixed extractant.

[0032] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid separation operation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extractant layer enters step S4.

[0033] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0034] S3. Add 0.1 parts of silica adsorbent to the waste acid in S2, then add 0.1 parts of 30% hydrogen peroxide, and oxidize and concentrate at 200℃ for 2 hours;

[0035] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0036] S5. After adding trimethyl phosphate to the bottom liquid of the column in S4 in a certain proportion, it can continue to be used as an extractant.

[0037] This example achieves a COD removal efficiency of 97.4% for waste acid, and the recycling rate of both waste acid and extractant can reach over 94.6%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0038]

Example 2

[0039] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0040] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:50:1 to obtain a mixed extractant.

[0041] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid separation operation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extractant layer enters step S4.

[0042] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 130℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0043] S3. Add 0.3 parts of silica adsorbent to the waste acid in S2, then add 0.1 parts of 30% hydrogen peroxide, and oxidize and concentrate at 220℃ for 2 hours;

[0044] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0045] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0046] This example achieves a COD removal efficiency of 96.1% for waste acid, and the recycling rate of both waste acid and extractant can reach over 92.5%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0047]

Example 3

[0048] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0049] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:1 to obtain a mixed extractant.

[0050] Add 3 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid separation operation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extractant layer enters step S4.

[0051] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0052] S3. Add 0.1 parts of silicon dioxide to the waste acid in S2, then add 0.1 parts of 30% hydrogen peroxide, and oxidize and concentrate at 180℃ for 2 hours;

[0053] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0054] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0055] This example achieves a COD removal efficiency of 95.2% for waste acid, and the recycling rate of both waste acid and extractant can reach over 88.9%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0056]

Example 4

[0057] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0058] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:1 to obtain a mixed extractant.

[0059] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid separation operation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extractant layer enters step S4.

[0060] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 190℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0061] S3. Add 0.3 parts of silicon dioxide to the waste acid in S2, then add 0.2 parts of 30% hydrogen peroxide, and oxidize and concentrate at 150℃ for 2 hours;

[0062] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0063] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0064] This example achieves a COD removal efficiency of 98.5% for waste acid, and the recycling rate of both waste acid and extractant can reach over 94.7%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0065]

Example 5

[0066] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0067] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:2 to obtain a mixed extractant.

[0068] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid separation operation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extractant layer enters step S4.

[0069] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 130℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0070] S3. Add 0.2 parts of silicon dioxide to the waste acid in S2, then add 0.05 parts of 30% hydrogen peroxide, and oxidize and concentrate at 220℃ for 2 hours;

[0071] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0072] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0073] This example achieves a COD removal efficiency of 96.6% for waste acid, and the recycling rate of both waste acid and extractant can reach over 92.4%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0074]

Example 6

[0075] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0076] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:1 to obtain a mixed extractant.

[0077] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid-liquid separation. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extraction layer enters step S4.

[0078] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 180℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0079] S3. Add 0.1 parts of silicon dioxide to the waste acid in S2, then add 0.1 parts of 30% hydrogen peroxide, and oxidize and concentrate at 200℃ for 2 hours;

[0080] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0081] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0082] This example achieves a COD removal efficiency of 97.4% for waste acid, and the recycling rate of both waste acid and extractant can reach over 87.3%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0083]

Example 7

[0084] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0085] n-Butanol, butyl ether and trimethyl phosphate were mixed evenly in a mass ratio of 50:25:1 to obtain a mixed extractant.

[0086] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid-liquid separation. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extraction layer enters step S4.

[0087] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0088] S3. Add 0.2 parts of silicon dioxide to the waste acid in S2, then add 0.1 parts of 30% hydrogen peroxide, and oxidize and concentrate at 200℃ for 2 hours;

[0089] S4. Flash evaporate the extractant layer in S1 at 105°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 70°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0090] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0091] This example achieves a COD removal efficiency of 96.8% for waste acid, and the recycling rate of both waste acid and extractant can reach over 89.6%. This not only improves treatment efficiency and reduces treatment costs, but also ensures that the conditions used throughout the implementation process can be used for production, making it economically and resourcefully significant.

[0092] [Comparative Example 1] The extractant was n-butanol.

[0093] S1. Take 10 parts of vitamin A waste sulfuric acid; add 2 parts of n-butanol to the waste sulfuric acid and shake vigorously; after extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid-liquid separation on the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is a waste acid solution. The waste acid in the lower layer enters step S2, and the upper extraction layer enters step S4.

[0094] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0095] S3. Add 0.1 parts of silicon dioxide to the waste acid in S2, and then add 0.1 parts of hydrogen peroxide with a concentration of 30%, and oxidize and concentrate at 200℃ for 2 hours;

[0096] S4. Flash distill the extractant layer in S1 at 95°C for 30 min to distill off the n-butanol extractant. The macromolecular organic matter remains in the bottom of the column. Flash distill the distillate containing n-butanol at 60°C for 30 min. The separated n-butanol is then placed in the bottom of the column.

[0097] The comparative example showed a COD removal efficiency of 83.8% for waste acid and a solvent reuse rate of 80.6%, which was worse than the example.

[0098] [Comparative Example 2] The extractants were n-butanol and butyl ether.

[0099] S1. Take 10 parts of vitamin A waste sulfuric acid; mix n-butanol and butyl ether at a mass ratio of 2:1; add 2 parts of mixed extractant to the waste sulfuric acid and shake vigorously; after extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid-liquid separation. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is a waste acid solution. The lower waste acid layer enters step S2, and the upper extraction layer enters step S4.

[0100] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0101] S3. Add 0.1 parts of silicon dioxide to the waste acid in S2, and then add 0.1 parts of hydrogen peroxide with a concentration of 30%, and oxidize and concentrate at 200℃ for 2 hours;

[0102] S4. Flash distill the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. The macromolecular organic matter remains in the bottom of the column. The distillate containing n-butanol and butyl ether is flash distilled again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column.

[0103] The comparative example showed a COD removal efficiency of 88.3% for waste acid and a solvent reuse rate of 84.9%, which was worse than the example.

[0104] [Comparative Example 3] No oxidant added

[0105] S1. Take 10 portions of waste sulfuric acid containing vitamin A;

[0106] Take n-butanol, butyl ether and trimethyl phosphate and mix them evenly in a mass ratio of 50:25:1;

[0107] Add 2 parts of mixed extractant to waste sulfuric acid and shake vigorously. After extraction, let stand for 10 minutes. After the layers are clearly separated, perform liquid-liquid separation. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is waste acid solution. The lower waste acid layer enters step S2, and the upper extraction layer enters step S4.

[0108] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0109] S3. Add 0.1 parts of silicon dioxide to the waste acid in S2 and oxidize and concentrate it at 200℃ for 2 hours;

[0110] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0111] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0112] The comparative example showed a COD removal efficiency of 84.5% for waste acid and a solvent reuse rate of 91.6%, which was worse than the example.

[0113] [Comparative Example 4] No adsorbent added

[0114] S1. Take 10 parts of vitamin A waste sulfuric acid; mix n-butanol, butyl ether and trimethyl phosphate in a mass ratio of 50:25:1; add 2 parts of mixed extractant to the waste sulfuric acid and shake vigorously; after extraction, let stand for 10 minutes. After the layers are distinct, separate the upper and lower layers. The upper layer solution is a mixed solution of extractant and waste acid organic matter, and the lower layer is a waste acid solution. The lower waste acid layer enters step S2, and the upper extraction layer enters step S4.

[0115] S2. The lower layer waste acid solution separated in S1 is evaporated and concentrated at 160℃ for 2 hours to remove the extractant, water and other organic matter from the solution. The remaining waste acid enters S3.

[0116] S3. Add 0.1 parts of 30% hydrogen peroxide to the waste acid in S2, and oxidize and concentrate it at 200℃ for 2 hours;

[0117] S4. Flash evaporate the extractant layer in S1 at 95°C for 30 min to distill off the extractant n-butanol and butyl ether. Trimethyl phosphate and macromolecular organic matter remain in the bottom of the column. Flash evaporate the distillate containing n-butanol and butyl ether again at 60°C for 30 min. The separated n-butanol and butyl ether remain in the bottom of the column, and the bottom liquid is sent to step S5.

[0118] S5. Add trimethyl phosphate to the bottom liquid of the tower in S4 in proportion.

[0119] The comparative example showed a COD removal efficiency of 90.7% for waste acid and a solvent reuse rate of 92.5%, which was worse than the example.

[0120] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used with various materials, environments, and combinations, and can be modified within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and additions made by those skilled in the art do not depart from the spirit and concept of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for disposal of waste sulfuric acid from vitamin A production, characterized by, The method comprises the following steps: S1. Adding a mixed extractant to the waste vitamin A sulfuric acid for extraction and separation, the upper layer being a mixed solution of the extractant and organic matter in the waste acid, and the lower layer being a waste acid solution; the mixed extractant comprises n-butanol, n-butyl ether and trimethyl phosphate; the mass ratio of n-butanol to n-butyl ether is 3:1-1:1, and the mass of trimethyl phosphate is 1%-3% of the sum of the mass of n-butanol and n-butyl ether; S2. Evaporating and concentrating the waste acid solution separated in S1 at high temperature to obtain concentrated waste sulfuric acid; S3. Adding hydrogen peroxide and an adsorbent to the concentrated waste sulfuric acid in S2 for oxidation concentration at high temperature.

2. The treatment method of claim 1, wherein: The mass ratio of the waste vitamin A sulfuric acid to the mixed extractant is 7:1-3:

1.

3. The treatment method of claim 1, wherein: In the step S2, the evaporation and concentration temperature is 120-190°C, and the evaporation and concentration time is 1-3h.

4. The treatment method of claim 1, wherein: In the step S3, the concentration of hydrogen peroxide is 27.5-30wt%, and the added amount is 0.5%-2.5% of the mass of the initial waste sulfuric acid.

5. The treatment method according to claim 1 or 4, characterized in that: In the step S3, the adsorbent is silicon dioxide, and the added amount is 0.5%-3% of the mass of the initial waste sulfuric acid.

6. The treatment method of claim 1, wherein: In the step S3, the oxidation concentration temperature is 150-230°C, and the reaction time is 1-3h.

7. The treatment method according to any one of claims 1 to 4, characterized in that: The method further comprises the following steps: S4. Flashing the mixed solution of the extractant layer separated in S1, and then performing secondary flashing on the flashed solution; S5. Reusing the extractant obtained in S4 after adjusting the formula of the extractant.

8. The treatment method of claim 7, wherein: In the step S4, the flashing temperature is 85-105°C, and the flashing time is 15-45min; the secondary flashing temperature is 50-70°C, and the time is 15-45min.

9. The treatment method of claim 7, wherein: In the step S5, the n-butanol, n-butyl ether and trimethyl phosphate are supplemented in proportion and then used as the extractant.