A method for cleaning 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor

Abstract

The present invention relates to the field of 1,4-dihydroxyanthraquinone dilution and hydrolysis mother liquor treatment, specifically a kind of cleaning treatment method of 1,4-dihydroxyanthraquinone dilution and hydrolysis mother liquor. Its steps mainly include: decolorization, cooling, neutralization and dissolution in ammonia water, solid-liquid separation, acidification, crystallization, drying pyrolysis, evaporation concentration, decolorization, quicklime reaction. The present invention can reclaim the excess phthalic anhydride added during the production of 1,4-dihydroxyanthraquinone in the dilution and hydrolysis mother liquor, can save resources, while reducing the production cost of the enterprise, meet the basic requirements of clean production, can extract boric acid by evaporation concentration hydroxyl mother liquor, centrifugation, drying, and then reclaim sulfuric acid by adding calcium oxide, truly achieve the unity of wastewater treatment and resource recovery, and realize clean production.

Description

Technical Field

[0001] The invention relates to the field of treatment of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor, and in particular to a method for clean treatment of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor. Background Art

[0002] 1,4-Dihydroxyanthraquinone is a dark orange powder soluble in sulfuric acid, sodium hydroxide solution, chlorobenzene, and dichlorobenzene. It is an important dye intermediate and itself a key dye. Currently, the main domestic synthesis route uses phthalic anhydride as the primary raw material. In actual production, excessive amounts of phthalic anhydride are intentionally added, often exceeding the rated amount by 20-50%, resulting in significant waste.

[0003] Currently, patent application number 200410013484.X discloses a method for treating 1,4-dihydroxyanthraquinone process wastewater to recover phthalic acid and sulfuric acid using concentration, cooling, crystallization, separation, and drying. This method can recover most of the phthalic acid and sulfuric acid in the wastewater, but concentrating low-concentration waste acid requires very high equipment requirements and is relatively expensive. The phthalic acid content separated after cooling and crystallization is relatively low because it contains a high amount of sulfuric acid, which is easily carbonized during the drying process. The recovered sulfuric acid is high in organic matter, making it difficult to effectively utilize.

[0004] Patent application number 00112386.6 discloses a method for recovering phthalic acid by adsorbing 1,4-dihydroxyanthraquinone wastewater at 0-60°C through a styrene-divinylbenzene copolymer macroporous resin. This method involves direct filtration of the wastewater or adjusting the pH to 3-4 before filtration. There is no cooling or crystallization process, and phthalic acid extraction relies entirely on resin adsorption. The high phthalic acid content in the wastewater reduces resin adsorption efficiency. Furthermore, adjusting the pH to 3-4 consumes a large amount of alkali, increasing costs. The recovered phthalic acid must undergo dehydration and sublimation at 200°C to obtain phthalic anhydride, which is then reused in the synthesis process. This method is difficult to commercialize and requires high energy consumption.

[0005] Therefore, how to effectively treat the acidic wastewater, recover phthalic acid and sulfuric acid, and reduce environmental pollution is an urgent issue that needs to be solved. Summary of the Invention

[0006] In order to solve the above problems, a method for cleaning the mother liquor of 1,4-dihydroxyanthraquinone dilution hydrolysis is provided, which is characterized by comprising the following steps:

[0007] Step ①: adding a decolorizing flocculant to the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone, and adding seed crystals for crystallization, while stirring, and cooling for a period of time to a temperature of 40 to 50° C. to obtain a mixture A;

[0008] Furthermore, the mixture A is a mixed system of phthalic acid, water, 1,4-dihydroxyanthraquinone and boric acid.

[0009] Step ②: cooling the mixture A to 25-30° C. and filtering the mixture A to obtain filtrate A and filter cake A;

[0010] Furthermore, the filtrate A is a mixed solution of sulfuric acid and boric acid with a total acid content of 18% to 20%, and the filter cake A is a mixed system of phthalic acid and 1,4-dihydroxyanthraquinone.

[0011] Step ③: adding water to the filter cake A, and then adding 20% ​​ammonia water to adjust the pH value. After the pH value reaches 6.5-7.5, the material is heated to 95° C. to obtain liquid B, and the temperature is kept for a period of time;

[0012] Among them, the reaction formula of phthalic acid and ammonia is:

[0013]

[0014] Furthermore, the liquid B is a mixed system of ammonium phthalate, water, and 1,4-dihydroxyanthraquinone.

[0015] Step ④: Liquid B is filtered, the filter cake is 1,4-dihydroxyanthraquinone, and the filtrate is ammonium phthalate;

[0016] Step 5: adding dilute sulfuric acid and water to the filtrate ammonium phthalate obtained in step 4, adjusting the pH value to 1-2, and cooling to 25-30° C. to obtain a slurry;

[0017] Among them, the reaction formula of ammonium phthalate and sulfuric acid is:

[0018]

[0019] Step ⑥: The slurry is subjected to filter pressing, the filter cake is phthalic acid, and the filtrate is ammonium sulfate;

[0020] Step 7: vacuum drying the phthalic acid filter cake to obtain phthalic anhydride;

[0021] Among them: the chemical formula of phthalic anhydride formed by drying and pyrolysis of phthalic acid is:

[0022]

[0023] The reaction conditions are: vacuum drying at 160-200°C for 3 hours.

[0024] Step ⑧: The filtrate A obtained in step ② is evaporated and concentrated to an acid content of 35-40%, and then cooled to 10-20° C., at which time boric acid is crystallized and the remaining liquid is a 40% sulfuric acid solution;

[0025] Step ⑨: adding activated carbon to the sulfuric acid solution in step ⑧ for decolorization and adsorption, and adding ammonium sulfate solution to the solution after decolorization and adsorption to obtain liquid C;

[0026] Furthermore, the liquid C is a mixed system of ammonium sulfate and sulfuric acid.

[0027] Step (10): mixing quicklime with the liquid C, adjusting the pH value to 6-7.5, and drying to obtain calcium sulfate dihydrate crystals.

[0028] a2(NH4)2S04CaSO42H2O+2NH31

[0029] Among them, quicklime turns into calcium hydroxide when it meets water, and the reaction formula of calcium hydroxide and ammonium sulfate is:

[0030] Furthermore, the cooling time in step ① is within 4 hours.

[0031] Furthermore, the decolorizing flocculant in step ① is 3853 organic polymer flocculant, and the dosage of the decolorizing flocculant is 1‰ to 2‰ of the total amount of the 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor.

[0032] Furthermore, the type of seed crystal in step ① is wet phthalic acid.

[0033] Furthermore, in step ③, the insulation time is 15 minutes.

[0034] Furthermore, in step ⑦, the drying temperature is 160-200°C.

[0035] Furthermore, the activated carbon in step ⑨ is powdered activated carbon.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention can recover excess phthalic anhydride added during the production of 1,4-dihydroxyanthraquinone from the hydrolysis mother liquor, thereby saving resources and reducing the production cost of the enterprise, meeting the basic requirements of clean production. The invention can concentrate the hydroxyl mother liquor by evaporation, centrifuge, and dry to extract boric acid, and then recover sulfuric acid by adding calcium oxide, thereby truly achieving the unity of wastewater treatment and resource recovery and utilization, and realizing clean production. DETAILED DESCRIPTION

[0038] The present invention and its effects will be further described below through examples.

[0039] Example 1:

[0040] 200 kg of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor at a temperature between 70-80°C was added to a cooling kettle, 180 g of phthalic acid solid was added as seed crystals, and 200 g of 3853 organic polymer flocculant was added. Stirring was started at the same time. After cooling to 40°C for 4 hours, a mixture A with flocculent material was obtained. The mixture A was a mixed system of phthalic acid, water, 1,4-dihydroxyanthraquinone, and boric acid.

[0041] The mixed substance A was put into a secondary water-cooled kettle, cooled to 25°C after 20 minutes, and put into a filter press. 6.78 kg of filter cake A was obtained by filtration, which was a mixed system of phthalic acid and 1,4-dihydroxyanthraquinone, and a filtrate A of a mixed solution of sulfuric acid and boric acid with a total acid content of 18% to 20%.

[0042] Water and 20% ammonia water were added to filter cake A to adjust the pH to 6.5 to obtain liquid B. In this process, the ammonia water not only adjusted the pH value but also dissolved the filter cake A. The main component of liquid B was ammonium phthalate solution.

[0043] Liquid B is subjected to filter press to separate the solid and liquid to obtain a 1,4-dihydroxyanthraquinone solid filter cake and an ammonium phthalate solution.

[0044] Water and dilute sulfuric acid were added to the obtained ammonium phthalate solution to adjust the pH value to 1, and then cooled to 25° C. and subjected to solid-liquid separation by filter press again to obtain 5.19 kg of phthalic acid filter cake, and the filtrate was transferred to the subsequent step.

[0045] In this process, the water added can be the filtrate obtained during the second filter press.

[0046] The phthalic acid mixture was heated and dried to crack it, and finally 4.18 kg of phthalic anhydride was obtained.

[0047] The waste liquid generated during the first filter press was evaporated and concentrated to an acid content of 35%, and then cooled to 10°C, at which time a solid was crystallized and 0.75 kg of boric acid was obtained after solid-liquid separation.

[0048] Powdered activated carbon was added to the waste liquid after the precipitation of boric acid as a decolorizing agent. After decolorization and adsorption, the waste liquid from the precipitation of phthalic acid was added, and quicklime was added to adjust the pH value to 6. Then, solid-liquid separation and evaporation drying were carried out to obtain 5.32 kg of calcium sulfate dihydrate.

[0049] Compared with the first embodiment, the working processes of the second and third embodiments are basically the same, and the difference lies in the difference between the specific values. The details of the second embodiment are as follows:

[0050] Example 2:

[0051] 200 kg of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor at a temperature between 70-80°C was added to a cooling kettle, 200 g of phthalic acid solid was added as seed crystals, and 190 g of 3853 organic polymer flocculant was added. Stirring was started at the same time. After cooling to 45°C for 3.5 hours, a mixture A with flocculent material was obtained. The mixture A was a mixed system of phthalic acid, water, 1,4-dihydroxyanthraquinone, and boric acid.

[0052] The mixed substance A was put into a secondary water-cooling kettle, cooled to 30°C after 15 minutes, and put into a filter press. 6.19 kg of filter cake A was obtained by filtration, which was a mixed system of phthalic acid and 1,4-dihydroxyanthraquinone, and a filtrate A of a mixed solution of sulfuric acid and boric acid with a total acid content of 18% to 20%.

[0053] Water and 20% ammonia water were added to filter cake A to adjust the pH to 7 to obtain liquid B. In this process, the ammonia water not only adjusted the pH value but also dissolved the filter cake A. The main component of liquid B was ammonium phthalate solution.

[0054] Liquid B is subjected to filter press to separate the solid and liquid to obtain a 1,4-dihydroxyanthraquinone solid filter cake and an ammonium phthalate solution.

[0055] Water and dilute sulfuric acid were added to the obtained ammonium phthalate solution to adjust the pH to 1, and then cooled to 27° C. and subjected to solid-liquid separation by filter press again to obtain 4.97 kg of phthalic acid filter cake, and the filtrate was transferred to the subsequent step.

[0056] In this process, the water added can be the filtrate obtained during the second filter press.

[0057] The phthalic acid mixture was heated and dried to crack it, and finally 3.95 kg of phthalic anhydride was obtained.

[0058] The waste liquid generated during the first filter press was evaporated and concentrated to an acid content of 35%, and then cooled to 15°C, at which time a solid was crystallized and 0.69 kg of boric acid was obtained after solid-liquid separation.

[0059] Powdered activated carbon was added to the waste liquid after the precipitation of boric acid as a decolorizing agent. After decolorization and adsorption, the waste liquid from the precipitation of phthalic acid was added, and quicklime was added to adjust the pH value to 6.5. Then, solid-liquid separation and evaporation drying were carried out to obtain 5.14 kg of calcium sulfate dihydrate.

[0060] Example 3:

[0061] 200 kg of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor at a temperature between 70-80°C was placed into a cooling kettle, 190 g of phthalic acid solid was added as seed crystals, and 210 g of 3853 organic polymer flocculant was added. Stirring was started at the same time. After cooling to 50°C for 3 hours, a mixture A with flocculent material was obtained. The mixture A was a mixed system of phthalic acid, water, 1,4-dihydroxyanthraquinone, and boric acid.

[0062] The mixed substance A was put into a secondary water-cooled kettle, cooled to 30°C after 20 minutes, and put into a filter press. 6.53 kg of filter cake A was obtained by filtration, which was a mixed system of phthalic acid and 1,4-dihydroxyanthraquinone, and a filtrate A of a mixed solution of sulfuric acid and boric acid with a total acid content of 18% to 20%.

[0063] Water and 20% ammonia water were added to filter cake A to adjust the pH to 7.5 to obtain liquid B. In this process, the ammonia water not only adjusted the pH value but also dissolved the filter cake A. The main component of liquid B was ammonium phthalate solution.

[0064] Liquid B is subjected to filter press to separate the solid and liquid to obtain a 1,4-dihydroxyanthraquinone solid filter cake and an ammonium phthalate solution.

[0065] Water and dilute sulfuric acid were added to the obtained ammonium phthalate solution to adjust the pH value to 1, and then cooled to 30° C. and subjected to solid-liquid separation by filter press again to obtain 5.07 kg of phthalic acid filter cake, and the filtrate was transferred to the subsequent step.

[0066] In this process, the water added can be the filtrate obtained during the second filter press.

[0067] The phthalic acid mixture was heated and dried to crack it, and finally 4.09 kg of phthalic anhydride was obtained.

[0068] The waste liquid generated during the first filter press was evaporated and concentrated to an acid content of 40%, and then cooled to 20°C, at which time a solid was crystallized and 0.71 kg of boric acid was obtained after solid-liquid separation.

[0069] Powdered activated carbon was added to the waste liquid after the precipitation of boric acid as a decolorizing agent. After decolorization and adsorption, the waste liquid from the precipitation of phthalic acid was added, and quicklime was added to adjust the pH value to 7.5. Then, solid-liquid separation and evaporation drying were carried out to obtain 5.33 kg of calcium sulfate dihydrate.

[0070] The following comparative examples are formed by changing the working steps of the present invention compared with Example 1. The specific comparative examples are as follows:

[0071] Comparative Example:

[0072] 200 kg of 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor at a temperature between 70-80°C was added to a cooling kettle, the seed crystal addition process was omitted, 200 g of 3853 organic polymer flocculant was added, and stirring was started at the same time. After cooling to 40°C for 4 hours, a mixture A with flocculent material was obtained. The mixture A was a mixed system of phthalic acid, water, 1,4-dihydroxyanthraquinone, and boric acid.

[0073] The mixed substance A was put into a secondary water-cooled kettle, cooled to 25°C after 20 minutes, and put into a filter press. 2.43 kg of filter cake A was obtained by filtration, which was a mixed system of phthalic acid and 1,4-dihydroxyanthraquinone, and a filtrate A of a mixed solution of sulfuric acid and boric acid with a total acid content of 18% to 20%.

[0074] Water and 20% ammonia water were added to filter cake A to adjust the pH to 6.5 to obtain liquid B. In this process, the ammonia water not only adjusted the pH value but also dissolved the filter cake A. The main component of liquid B was ammonium phthalate solution.

[0075] Liquid B is subjected to filter press to separate the solid and liquid to obtain a 1,4-dihydroxyanthraquinone solid filter cake and an ammonium phthalate solution.

[0076] Water and dilute sulfuric acid were added to the obtained ammonium phthalate solution to adjust the pH value to 1, and then cooled to 25° C. and subjected to solid-liquid separation by filter press again to obtain 1.56 kg of phthalic acid filter cake, and the filtrate was transferred to the subsequent step.

[0077] In this process, the water added can be the filtrate obtained during the second filter press.

[0078] The phthalic acid mixture was heated and dried to crack it, and finally 1.21 kg of phthalic anhydride was obtained.

[0079] The waste liquid generated during the first filter press was evaporated and concentrated to an acid content of 35%, and then cooled to 10°C, at which time a solid was crystallized and 0.72 kg of boric acid was obtained after solid-liquid separation.

[0080] Powdered activated carbon was added to the waste liquid after the precipitation of boric acid as a decolorizing agent. After decolorization and adsorption, the waste liquid from the precipitation of phthalic acid was added, and quicklime was added to adjust the pH value to 6. Then, solid-liquid separation and evaporation drying were carried out to obtain 5.28 kg of calcium sulfate dihydrate.

[0081] Although phthalic acid solid was obtained in this comparative example, no seed crystals were added, resulting in a long crystallization time and a low amount of solid obtained.

[0082] Table 2 is the data analysis of Examples 1, 2, 3 and Comparative Examples

[0083] Table 1 Data analysis of Examples 1, 2, 3 and Comparative Examples

[0084]

[0085] The color of the mother liquor is orange-red. After ordinary precipitation treatment, the color of the mother liquor is orange. After treatment by this method, the final liquid color is colorless.

[0086] It should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions to the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be encompassed by the scope of the claims of the present invention.

Claims

1. A method for cleaning a 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor, characterized by: The following steps are involved: Step ①: adding a decolorizing flocculant to the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone and adding seed crystals for crystallization, wherein the seed crystals are wet phthalic acid, stirring at the same time, and cooling for a period of time to a temperature of 40 to 50° C. to obtain a mixture A; Step ②: cooling the mixture A to 25-30° C. and filtering the mixture A to obtain filtrate A and filter cake A; Step ③: adding water to the filter cake A, and then adding 20% ​​ammonia water to adjust the pH value. After the pH value reaches 6.5-7.5, the material is heated to 95° C. to obtain liquid B, and the temperature is kept for a period of time; Step ④: Liquid B is filtered, the filter cake is a 1,4-dihydroxyanthraquinone solid filter cake, and the filtrate is an ammonium phthalate solution; Step 5: adding dilute sulfuric acid and water to the filtrate obtained in step 4, adjusting the pH value to 1-2, and cooling to 25-30° C. to obtain a slurry; Step ⑥: The slurry obtained in step ⑤ is subjected to filter pressing, the filter cake is phthalic acid, and the filtrate is ammonium sulfate; Step 7: vacuum drying the phthalic acid filter cake obtained in step 6 to obtain phthalic anhydride; Step ⑧: The filtrate A obtained in step ② is evaporated and concentrated to an acid content of 35-40%, and then cooled to 10-20° C., at which time boric acid is crystallized and the remaining liquid is a 40% sulfuric acid solution; Step ⑨: adding activated carbon to the sulfuric acid solution in step ⑧ for decolorization and adsorption, and adding ammonium sulfate solution to the solution after decolorization and adsorption to obtain liquid C; Step (10): mixing quicklime with the liquid C, adjusting the pH value to 6-7.5, and drying to obtain calcium sulfate dihydrate crystals.

2. The method for cleaning the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone according to claim 1, characterized in that: The cooling time in step ① is within 4 hours.

3. The method for cleaning the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone according to claim 1, characterized in that: In the step ①, the decolorizing flocculant is 3853 organic polymer flocculant, and the dosage of the decolorizing flocculant is 1‰ to 2‰ of the total amount of the 1,4-dihydroxyanthraquinone diluted hydrolysis mother liquor.

4. The method for cleaning the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone according to claim 1, characterized in that: In step ③, the insulation time is 15 minutes.

5. The method for cleaning the mother liquor of 1,4-dihydroxyanthraquinone diluted hydrolysis according to claim 1, characterized in that: In step ⑦, the drying temperature is 160-200°C.

6. The method for cleaning the diluted hydrolysis mother liquor of 1,4-dihydroxyanthraquinone according to claim 1, characterized in that: The activated carbon in step ⑨ is powdered activated carbon.

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