Method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling generated waste residues

Abstract

The invention belongs to the field of environment-friendly water treatment, and particularly relates to a method for neutralizing dilute sulphuric acid wastewater generated in anthraquinone dye production, recycling generated calcium sulfate waste residues and simultaneously producing ammonium sulfate. According to the method, the dilute sulphuric acid wastewater and calcium carbonate are subjected to acid-base neutralization under the aeration condition, generated calcium sulfate waste residues react with ammonium bicarbonate to generate ammonium sulfate and calcium carbonate, the generated ammonium sulfate can be sold as a product, and the calcium carbonate is reused for neutralization of the dilute sulphuric acid wastewater to form cyclic utilization. The method solves the problems of high cost of anthraquinone dye dilute sulphuric acid wastewater neutralization treatment and more calcium sulfate waste residues, and meanwhile, the product ammonium sulfate with certain economic benefits is prepared.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection water treatment, and in particular relates to a method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the generated waste residue. Background Art

[0002] In the production process of anthraquinone dyes, a large amount of waste dilute sulfuric acid and low-concentration acidic wastewater are generated. The waste acid mainly comes from the hydrolysis mother liquor, and the concentration of the waste acid is about 10%. The low-concentration waste acid comes from the washing process. After the two wastewaters are mixed, they are still low-concentration acidic wastewater and cannot be discharged directly. The existing treatment methods all use caustic soda or lime for neutralization. The use of caustic soda for neutralization will produce a large amount of sodium sulfate, which will affect the normal operation of the subsequent biochemical treatment process, and the neutralization cost is high; the use of lime for neutralization will produce a large amount of calcium sulfate waste residue. The amount of this part of waste residue is large, and the treatment cost is very high, which greatly restricts the normal development of the industry. Summary of the invention

[0003] In order to overcome the shortcomings of the existing treatment methods, the present invention provides a method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated. The dilute sulfuric acid wastewater generated in the production process of anthraquinone dyes is neutralized with cheap calcium carbonate, and the calcium sulfate waste residue generated after neutralization is reacted with ammonium bicarbonate to produce calcium carbonate for recycling, and ammonium sulfate product is produced at the same time. The problem of high cost of neutralization treatment of anthraquinone dye dilute sulfuric acid wastewater and large amount of waste residue generated after treatment is solved.

[0004] The technical solution of the present invention is achieved by: a method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated, the specific steps are as follows:

[0005] (1) The acidic wastewater generated by the mixture of waste dilute sulfuric acid and low-concentration acidic wastewater generated in the production process of anthraquinone dyes enters the dilute calcium carbonate neutralizer through the bottom water inlet pipe 1, and at the same time, a mixed solution of calcium carbonate and water is added through the upper pipe 10, and aeration is carried out through the aeration pipe at the bottom of the equipment 2. The mixed solution of calcium sulfate and water generated after neutralization flows from the dilute calcium carbonate neutralizer ① through the upper pipe 3 to the calcium sulfate precipitator ② by gravity. The precipitated water flows from the calcium sulfate precipitator ② through the upper pipe 4 to the sewage treatment station, and the generated calcium sulfate waste residue is precipitated at the bottom of the calcium sulfate precipitator ②.

[0006] (2) The calcium sulfate waste residue precipitated at the bottom of the calcium sulfate precipitator ② is input into the calcium sulfate filter press ④ through the 5th pipeline by the ③ slurry pump for filtration, and the effluent is discharged into the sewage treatment station through the 6th pipeline for treatment. The filter residue is added into the ⑤ calcium sulfate and ammonium bicarbonate reaction tank, and the reaction is carried out after adjusting the pH value to a certain value with ammonia water. The reaction temperature is controlled at 30-40°C and the reaction time is 5 hours.

[0007] (3) After the reaction of calcium sulfate and ammonium bicarbonate in the reaction tank (5) is completed, the material is transported to the calcium carbonate filter press (7) via the slurry pump (6) through the pipeline (7) for filtration. The filtrate is discharged into the ammonium sulfate solution storage tank (9) via the pipeline (8), and the filter residue is placed in the calcium carbonate stirring tank (8).

[0008] (4) Add a certain amount of water to the calcium carbonate mixing tank (⑧) and the calcium carbonate filtered out from the calcium carbonate filter press (⑦) and stir and mix them, then send them quantitatively to the dilute calcium carbonate sulfate neutralizer (①) through the upper pipeline (10) by the slurry pump (⑩) for recycling.

[0009] (5) The solution in the ammonium sulfate solution storage tank (9) is adjusted to pH=6.5 with 30% sulfuric acid, and then output through pipeline (9) for drying to obtain ammonium sulfate solid.

[0010] Compared with the existing treatment technology, the beneficial effects of the present invention are: solving the problems of high cost of neutralization of dilute sulfuric acid wastewater generated in the production process of anthraquinone dyes and much waste residue generated during neutralization, thoroughly treating the waste residue generated by neutralization of dilute sulfuric acid wastewater generated in the production process of anthraquinone dyes, and obtaining ammonium sulfate, a product with certain economic benefits, which not only realizes the recycling of waste residues, but also generates economic benefits. The comprehensive cost of treating dilute sulfuric acid wastewater of anthraquinone dyes is greatly reduced, and the market competitiveness of anthraquinone dyes is greatly enhanced. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The process flow chart of the method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated includes ① a dilute sulfuric acid calcium carbonate neutralizer; ② a calcium sulfate precipitator; ③ a slurry pump; ④ a calcium sulfate filter press; ⑤ a calcium sulfate and ammonium bicarbonate reaction tank; ⑥ a slurry pump; ⑦ a calcium carbonate filter press; ⑧ a calcium carbonate stirring tank; ⑨ an ammonium sulfate solution storage tank; ⑩ a slurry pump; 1 a bottom water inlet pipe; 2 an aeration pipe at the bottom of the equipment; 3 an upper pipe; 4 an upper pipe; 5 a pipe; 6 a pipe; 7 a pipe; 8 a pipe; 9 a pipe; 10 an upper pipe; DETAILED DESCRIPTION

[0012] This embodiment utilizes the dilute sulfuric acid wastewater generated in the production process of anthraquinone dyes to neutralize the acid and alkali with calcium carbonate, and the generated calcium sulfate waste residue is converted into calcium carbonate for recycling, while producing a method of ammonium sulfate. It includes the following steps:

[0013] (1) Raw material preparation: water, calcium carbonate powder, ammonium bicarbonate, ammonia water, and 30% sulfuric acid.

[0014] (2) Dilute sulfuric acid wastewater is uniformly introduced into the dilute sulfate calcium carbonate neutralizer ① through the bottom water inlet pipe 1, and a mixture of calcium carbonate and water is added through the upper pipe 10, and air is added to the bottom aeration pipe of the equipment 2 for aeration. The flow rate of the dilute sulfuric acid wastewater is controlled, and the amount of the mixture of calcium carbonate and water and the aeration intensity are controlled at the same time, so that the effluent from the upper pipe 3 is maintained at PH4-5, and the effluent flows into the calcium sulfate precipitator ② through the upper pipe 3 by gravity.

[0015] (3) The effluent from the reaction in ① the dilute calcium sulfate carbonate neutralizer flows by gravity into ② the calcium sulfate precipitator. After precipitation, the effluent flows by gravity into the sewage treatment station through 4 upper pipes for treatment. The calcium sulfate precipitated in the lower part is sent by ③ the slurry pump through 5 pipes to ④ the calcium sulfate filter press for filtration. The effluent from the filtration flows by gravity into the sewage treatment station through 6 pipes for treatment. The waste residue from the filtration is calcium sulfate.

[0016] (4) The calcium sulfate waste residue pressed out of the calcium sulfate filter press ④ is added to the calcium sulfate and ammonium bicarbonate reaction tank ⑤, and then water and ammonium bicarbonate are added to stir and react. The material ratio is calcium sulfate: ammonium bicarbonate: water = 350 kg: 350 kg: 1000 kg. An appropriate amount of ammonia water is added to adjust the pH value in the reaction tank to about 8. The reaction temperature is controlled at 30-40° C. and the stirring reaction time is 5 hours.

[0017] (5) The mixture after the reaction of calcium sulfate and ammonium bicarbonate in the reaction tank ⑤ is transported to the calcium carbonate filter press ⑦ through the pipeline 7 by the slurry pump ⑥ for filtration. The filter residue is calcium carbonate, and the effluent from the filtration is ammonium sulfate solution, which flows into the ammonium sulfate solution storage tank ⑨ through the pipeline 8 by gravity. 30% sulfuric acid is added to adjust the pH to about 6.5, and the product ammonium sulfate is obtained after being discharged through the pipeline 9 for concentration and crystallization.

[0018] (6) Add the filter residue from the calcium carbonate filter press ⑦ into the calcium carbonate mixing tank ⑧, and add a certain amount of water to mix evenly. The mixed solution of calcium carbonate and water is quantitatively input into the dilute calcium carbonate sulfate neutralizer ① through the upper pipeline 10 by the slurry pump ⑩ for recycling.

Claims

1. A method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue produced, characterized in that The dilute sulfuric acid wastewater generated in the production of anthraquinone dyes is neutralized with calcium carbonate, and the resulting calcium sulfate waste residue reacts with ammonium bicarbonate to generate calcium carbonate and ammonium sulfate. The calcium carbonate can be recycled to neutralize the dilute sulfuric acid wastewater, and the ammonium sulfate can be sold as a product.

2. The method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated according to claim 1, characterized in that The dilute sulfuric acid wastewater is uniformly introduced into the ① dilute sulfuric acid calcium carbonate neutralizer from the bottom water inlet pipe 1, and the mixture of calcium carbonate and water is added from the upper pipe 10. At the same time, air is added to the bottom aeration pipe of the equipment 2 for aeration. The flow rate of the dilute sulfuric acid wastewater is controlled, and the amount of the mixture of calcium carbonate and water and the aeration intensity are controlled at the same time. The effluent from the upper pipe 3 is maintained at PH4-5, and the effluent flows into the ② calcium sulfate precipitator through the upper pipe 3 by gravity.

3. The method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated according to claim 1, characterized in that The effluent after the reaction of ① dilute calcium sulfate carbonate neutralizer flows by gravity into ② calcium sulfate precipitator through 3 upper pipe. After precipitation, the effluent flows by gravity into the sewage treatment station through 4 upper pipe for treatment. The calcium sulfate precipitated in the lower part is sent by ③ slurry pump through 5 pipe to ④ calcium sulfate filter press for filtration. The effluent from the filtration flows by gravity into the sewage treatment station through 6 pipe for treatment. The waste residue from the filtration is calcium sulfate.

4. The method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue produced according to claim 1, characterized in that The calcium sulfate waste residue pressed out of the calcium sulfate filter press ④ is added to the calcium sulfate and ammonium bicarbonate reaction tank ⑤, and then water and ammonium bicarbonate are added for stirring reaction. The material ratio is calcium sulfate: ammonium bicarbonate: water = 350 kg: 350 kg: 1000 kg. An appropriate amount of ammonia water is added to adjust the pH value in the reaction tank to about 8, the reaction temperature is controlled at 30-40°C, and the stirring reaction time is 5 hours.

5. The method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue generated according to claim 1, characterized in that The mixture after the reaction in the calcium sulfate and ammonium bicarbonate reaction tank ⑤ is transported to the calcium carbonate filter press ⑦ through the 7th pipeline by the ⑥ slurry pump for filtration. The filter residue is calcium carbonate, and the effluent from the filtration is ammonium sulfate solution, which flows into the ammonium sulfate solution storage tank ⑨ through the 8th pipeline by gravity. 30% sulfuric acid is added to adjust the pH to about 6.5, and then it is output through the 9th pipeline for concentration and crystallization to obtain the product ammonium sulfate.

6. The method for neutralizing anthraquinone dilute sulfuric acid wastewater and recycling the waste residue produced according to claim 1, characterized in that Add the filter residue filtered out by the calcium carbonate filter press ⑦ into the calcium carbonate mixing tank ⑧, and add a certain amount of water to stir evenly. Use the slurry pump ⑩ to quantitatively input the mixed solution of calcium carbonate and water into the dilute calcium carbonate sulfate neutralizer ① through the upper pipeline 10 for recycling.

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