Treatment method of copper ammonia wastewater

Abstract

The invention relates to a copper ammonia wastewater treatment method, which comprises: pumping copper ammonia wastewater into a one-step copper removal reaction kettle, adding hydrochloric acid while stirring until a set pH value is reached, stopping adding hydrochloric acid, continuously stirring, and filtering to obtain a filter cake, i.e., copper hydroxide; transferring the filtrate to a two-step copper removal reaction kettle, slowly adding a diluent of sulfide or organic sulfide, and continuously stirring when the pH value is set and the sulfide or organic sulfide added after filtration does not change color any more; adding hydrochloric acid to adjust the pH value, and filtering to obtain a filter cake, namely copper sulfide or organic copper sulfide; evaporating and concentrating the filtrate in a distillation kettle until ammonium chloride begins to be separated out from the system, cooling, adding hydrochloric acid until organic matters are completely dissolved, filtering in a two-in-one manner, washing a filter cake with a saturated ammonium chloride solution containing dilute ammonia water, filtering to obtain an ammonium chloride wet product, drying to obtain an ammonium chloride byproduct, and applying the two-in-one filtered acidic filtrate to the one-step copper removal system. According to the method, copper and ammonia are effectively separated, resource waste is avoided, and the comprehensive utilization rate is high.

Description

Technical Field

[0001] The invention relates to a method for treating copper-ammonia waste water, and belongs to the technical field of industrial waste water treatment. Background Art

[0002] Copper ammonia wastewater comes from the process of preparing 4,4 aminosulfone by ammoniation of 4,4 chlorophenylsulfone. The general process in the workshop is: a large amount of ammonia water is dissolved in a solution containing cuprous chloride to prepare a copper ammonia ion solution containing a large amount of free ammonia as a catalyst; then 4,4 chlorophenylsulfone is added to the copper ammonia ion solution to react and generate 4,4 aminosulfone. After the reaction is completed, the system evaporates part of the ammonia water with a content of 10-20% at high temperature, and the remaining system is filtered to obtain a crude 4,4 aminosulfone, which is refined to obtain a finished product, and the filtered filtrate is the copper ammonia wastewater.

[0003] The copper ammonia wastewater in the workshop has a pH of 7-10, and the system is a dark blue solution with a specific gravity of 1.01-1.05 g / mL. The main substances in the system are: NH 4 + , Cu 2+ , Cl - NH 3 NH 3 ·H 2 O, [Cu(NH 3 ) 4 ] 2+ OH - 、Residual aminosulfone (Ar-NH 2 )wait.

[0004] Conventional treatment methods for copper-ammonia wastewater are: direct copper-ammonia wastewater into a three-effect evaporation system, direct distilled water into a biochemical system, and direct spray drying of concentrated water. The distilled water obtained by this treatment method generally has a high ammonia nitrogen value, which will cause great pressure on the biochemical system and high treatment costs; after the concentrated water is spray-dried, the solid obtained contains a large amount of copper salts and ammonium salts, which are difficult to separate and can only be treated as industrial solid waste, resulting in serious waste. Summary of the invention

[0005] In order to overcome the drawbacks of the prior art, the present invention provides a method for treating copper ammonia wastewater. After one-step copper removal and two-step copper removal, two by-products, copper hydroxide and copper sulfide (or organic sulfur copper), are obtained, and the separation of metallic copper is achieved. After concentration, hydrochloric acid is added to achieve the separation of organic matter and ammonium chloride. The distilled water has the characteristics of low COD and low ammonia nitrogen, can be directly used for biochemical treatment or used in a workshop, and the treatment cost is low.

[0006] The technical solution adopted by the present invention to solve its technical problem is: A method for treating copper ammonia wastewater, the method comprising the following steps: a. One-step copper removal: Put the copper ammonia wastewater into the one-step copper removal reactor, add hydrochloric acid under stirring, and stop adding hydrochloric acid after the system reaches the set pH value, continue stirring, filter, and the filter cake is copper hydroxide. The main reaction formula for one-step copper removal is as follows: NH 3 ·H 2 O + HCl = NH 4 Cl + H 2 O (one) [Cu(NH 3 ) 4 ] 2+ + 2Cl - + 2HCl + 2H 2 O = Cu(OH) 2 ↓ + 4NH 4 Cl (II) [Cu(NH 3 ) 4 ] 2+ + 4HCl = Cu 2+ + 4NH 4 Cl (III); b. Two-step copper removal: The filtrate after the first-step copper removal is transferred to the second-step copper removal reactor, and the diluent prepared with sulfide or organic sulfide is slowly added to the system until the system reaches the set pH value and the system does not change color after adding sulfide or organic sulfide after filtration, and then continue stirring; then hydrochloric acid is added to further adjust the pH of the system to a certain range, and the filtrate is transferred to the distillation kettle after filtration. The filter cake is copper sulfide or organic copper sulfide. The main reaction formula is as follows: [Cu(NH 3 ) 4 ] 2+ + S 2- = CuS↓+4NH 3 ↑ (IV) NH 3 + H 2 O = NH 3 ·H 2 O (Five) Cu 2+ + S 2- = CuS↓ (six) S 2- +2 H + = H 2 S↑ (VII) NH 3 + H + = NH 4 + (eight); c. Ammonium chloride recovery: The filtrate system after the two-step copper removal is evaporated and concentrated in a distillation kettle until ammonium chloride begins to precipitate out of the system, the temperature is lowered, hydrochloric acid is added to the system until all the black organic matter in the system is dissolved, and a two-in-one filter is used. The filtrate is strongly acidic, and the filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia water to a certain pH. After filtering, wet ammonium chloride is obtained, and after drying, ammonium chloride by-product is obtained. The main reaction formula is as follows: After concentration and cooling, add acid: Ar-NH 2 + H + = Ar-NH 3 + Washing filter cake: NH 3 + H + = NH 4 + NH 3 ·H 2 O + H + = NH 4 + + H 2 O; d. The water distilled from the distillation kettle is directly subjected to biochemical treatment or used within the workshop. The acidic filtrate from the two-in-one filtration is applied to the one-step copper removal system, and the obtained washing liquid is repeatedly applied after adding ammonia water.

[0007] In the above-mentioned method for treating copper ammonia wastewater, in step a, the hydrochloric acid is industrial hydrochloric acid or an applied acidic filtrate, the acid value of the industrial hydrochloric acid is 25-35%, and the acid value of the applied acidic filtrate is 2-8%.

[0008] In the above-mentioned method for treating copper ammonia wastewater, after adding hydrochloric acid, the pH value of the system is 4-6. After stopping the addition of acid, stirring is continued for 1-2 hours, and the pH value of the system is kept unchanged at 4-6 before filtration.

[0009] In the above-mentioned method for treating copper ammonia wastewater, in the step b, the sulfide is sodium sulfide or potassium sulfide inorganic sulfide, the organic sulfide is mercaptan or thiophenol organic sulfide, and the concentration of the dilution prepared with the sulfide or organic sulfide is 5-30%.

[0010] In the above-mentioned method for treating copper ammonia wastewater, in the step b, after adding sulfide, the pH value is adjusted to 7-9, the stirring time is continued for 1-3 hours, and hydrochloric acid is added to adjust the pH value to 4-6.

[0011] In the above-mentioned method for treating copper ammonia wastewater, in step c, distillation and concentration adopts normal pressure or slightly negative pressure distillation, the vacuum degree is 0~-0.05MPa, and the concentration ratio is 2:1~5:1.

[0012] In the above-mentioned method for treating copper ammonia wastewater, in step c, the temperature is lowered to 10-30°C after crystallization, and after hydrochloric acid is added, the acid value of the system is 2-8%.

[0013] In the above-mentioned method for treating copper ammonia wastewater, the ammonia content in the saturated ammonium chloride solution of dilute ammonia water is 1-5%, and the pH value of the filtrate after washing is 4-6.

[0014] The beneficial effects of the present invention are: In the method for treating copper-ammonia wastewater of the present invention, after one-step copper removal and two-step copper removal, two by-products, copper hydroxide and copper sulfide (or organic copper sulfide), can be obtained, thereby realizing the separation of metallic copper; the system after copper removal is distilled and concentrated, and the COD and ammonia nitrogen values ​​of the distilled water are both low, which can greatly reduce the water treatment cost or can be directly used in the workshop. By adding hydrochloric acid after concentration, the separation of organic matter and ammonium chloride is realized, and the extracted ammonium chloride has a high yield and high purity. The treatment process is simple and easy, the production cost is low, the conditions are mild, the effective separation of copper and ammonia is realized, waste is turned into treasure, the waste of resources is avoided, and the comprehensive utilization rate is high. DETAILED DESCRIPTION

[0015] After the copper is removed in one step, a green to yellow-green copper hydroxide solid is obtained, and the yield is greater than 90%. Sulfide is added to carry out the second-step copper removal, and the second-step copper removal needs to meet the following conditions: (1) the system filtrate is a colorless to light yellow liquid; (2) the pH value of the system filtrate is 6-9; (3) after the system filtrate is added with sulfide or organic sulfide, no black matter is generated, indicating that the second-step copper removal is qualified. After the second-step copper removal is qualified, hydrochloric acid is added to the system to adjust the pH value of the system. This is because in the second-step copper removal, the amount of sulfide or organic sulfide added is slightly excessive, and the pH value of the system is alkaline or neutral (pH ≥ 7). At this time, if the alkaline system is filtered, the filtrate is directly concentrated, and ammonia enters the distilled water, and ammonium sulfide will accelerate the hydrolysis; with high-temperature distillation, ammonium chloride in the neutral system will also hydrolyze. The hydrolysis of ammonium sulfide or ammonium chloride will cause the ammonia nitrogen value in the distilled water to be high. Therefore, before entering the distillation stage, hydrochloric acid is added to the system to adjust the system to acidity, inhibit the hydrolysis of ammonium sulfide and ammonium chloride in the system, reduce the ammonia nitrogen value of the effluent, and increase the recovery rate of ammonium chloride in the next step. Control the amount of acid added so that the pH value of the system is 4~6, inhibit the hydrolysis of ammonium chloride, minimize its hydrolysis degree, and the lower the ammonia nitrogen in the distilled water.

[0016] After the two-step copper removal is completed, the present invention performs evaporation concentration, the atmospheric distillation temperature is 105-115°C, the temperature of the micro-negative pressure distillation is about 100°C, the concentration ratio is controlled to be 2:1-5:1, low COD and low ammonia nitrogen water is evaporated, the ammonium chloride in the system is concentrated to a saturated state and precipitated, the temperature is lowered, black organic matter (mainly organic matter containing amino groups) in the system is precipitated, and then hydrochloric acid is added to the concentration system to make the organic matter completely dissolved in the system again, filtering is performed, the filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia water to a pH of 4-6, wet ammonium chloride is obtained after filtering, and ammonium chloride byproduct is obtained after drying, the recovery and extraction of ammonium chloride is completed, and the organic matter enters the one-step copper removal process with the acidic filtrate for application.

[0017] The present invention will be further described below in conjunction with the embodiments.

[0018] The method of this application is used to treat production wastewater. The copper ion content in the copper ammonia wastewater system is 0.1-1.0%. The total NH 3 The content is 1-10%, and the COD of the system is 1000-10000 mg / L.

[0019] In each embodiment, the yield of copper refers to the mass percentage of the amount of copper in the obtained products (copper hydroxide and copper sulfide) to the amount of copper ions in the initial copper ammonia wastewater. Example 1

[0020] The copper-ammonia wastewater before treatment was dark blue, with a COD of 3500 mg / L, a pH of 7.5, a copper ion content of 0.38%, and a total NH 3 The content is 6.38%.

[0021] S1: Put the copper ammonia wastewater into the first-step copper removal reactor, add hydrochloric acid under stirring, stop adding hydrochloric acid when the system pH is 5.5, continue stirring for 2 hours, and the system pH remains unchanged; filter the system and transfer it to the second-step copper removal reactor. The filtrate after the first-step copper removal is light green; the filter cake is copper hydroxide, blue-green, and the test copper yield is 94.20%.

[0022] S2: Slowly add 10% sodium sulfide solution to the system until the pH of the system reaches 8.0. The system is colorless and transparent. After filtering, the system does not change color when sodium sulfide is added. The two-step copper removal is completed and stirring is continued for 2 hours. Then add hydrochloric acid to adjust the pH of the system to 5. After filtering, transfer to the distillation kettle. The treated filtrate is light yellow and transparent, without ammonia odor, and the COD is 1020 mg / L; the filter cake is black copper sulfide, and the test copper yield is 5.81%.

[0023] S3: The system after copper removal is evaporated and concentrated in a distillation kettle. After the system begins to precipitate ammonium chloride, the temperature is lowered to 20°C. Hydrochloric acid is added to the system until all the black organic matter in the system is dissolved. It is filtered using a two-in-one, and then washed with a saturated ammonium chloride solution containing 2% ammonia water until the pH is 5. After filtering, wet ammonium chloride is obtained, and after drying, ammonium chloride by-product is obtained. The concentration ratio is 4.5:1, the COD of the distilled water is 120 mg / L, the ammonia nitrogen value of the distilled water is 80 mg / L, and the acid value of the acidic filtrate is 3.5%. The yield of ammonium chloride is 62.3%, and the content is 98.72%. Example 2

[0024] The copper-ammonia wastewater before treatment was dark blue, with a COD of 3600 mg / L, a pH of 8.0, a copper ion content of 0.52%, and a total NH 3 The content is 8.24%, and the content of ammonium chloride in the mother liquor is 25.6%.

[0025] S1: Put the copper ammonia wastewater into the one-step copper removal reactor, add the acidic filtrate in step S3 of Example 1 under stirring until the pH of the system reaches 6.5, then continue to add hydrochloric acid, stop adding hydrochloric acid when the pH of the system reaches 5.0, continue stirring for 2 hours, and the pH of the system remains unchanged; filter the system and transfer it to the two-step copper removal reactor. The filtrate after the one-step copper removal is light green; the filter cake is green copper hydroxide, and the copper yield is 91.32%.

[0026] S2: Slowly add 8% sodium sulfide solution to the system until the pH of the system reaches 7.0. The system is colorless and transparent. After filtering, the system does not change color when sodium sulfide is added. The two-step copper removal is completed and stirring is continued for 2 hours. Then add hydrochloric acid to adjust the pH of the system to 4.5. After filtering, transfer to the distillation kettle. The treated filtrate is colorless and transparent, has no ammonia smell, and the COD is 1050 mg / L. The filter cake is black copper sulfide, and the copper yield is 8.65%.

[0027] S3: The system after copper removal is evaporated and concentrated in a distillation kettle. After the system begins to precipitate ammonium chloride, the temperature is lowered to 18°C. Hydrochloric acid is added to the system until all the black organic matter in the system is dissolved. It is filtered using a two-in-one, and then washed with a saturated ammonium chloride solution containing 2% ammonia water until the pH is 5. After filtering, wet ammonium chloride is obtained, and after drying, ammonium chloride by-product is obtained. The concentration ratio is 3.5:1, the COD of the distilled water is 110 mg / L, the ammonia nitrogen value of the distilled water is 50 mg / L, and the acid value of the acidic filtrate is 4.5%. The yield of ammonium chloride is 85.2%, and the content of ammonium chloride is 99.29%. Example 3

[0028] The copper-ammonia wastewater before treatment was dark blue, with a COD of 4200 mg / L, a pH of 8.0, a copper ion content of 0.42%, and a total NH3 The content is 6.75%.

[0029] S1: Put the copper ammonia wastewater into the first-step copper removal reactor, add hydrochloric acid under stirring, stop adding hydrochloric acid when the system pH is 6.0, continue stirring for 2 hours, and the system pH remains unchanged; filter the system and transfer it to the second-step copper removal reactor. The filtrate after the first-step copper removal is light green; the filter cake is green copper hydroxide, and the copper yield is 90.2%.

[0030] S2: Slowly add 6% organic mercaptan solution to the system until the pH of the system reaches 7.0, the system is colorless and transparent, the system does not change color after adding sodium sulfide after filtration, and the two-step copper removal is completed, and continue stirring for 2 hours; then add hydrochloric acid to adjust the pH of the system to 4.5, and transfer to the distillation kettle after filtration. The treated filtrate is colorless and transparent, without ammonia odor, and the COD is 1450mg / L; the filter cake is black organic copper sulfide, and the copper yield is 9.78%.

[0031] S3: The system after copper removal is evaporated and concentrated in a distillation kettle. After the system begins to precipitate ammonium chloride, the temperature is lowered to 20°C. Hydrochloric acid is added to the system until all the black organic matter in the system is dissolved. It is filtered using a two-in-one method, and then washed with a saturated ammonium chloride solution containing 2% ammonia water until the pH is 5. After filtering, wet ammonium chloride is obtained, and after drying, ammonium chloride by-product is obtained. The concentration ratio is 4.5:1, the COD of the distilled water is 100 mg / L, the ammonia nitrogen value of the distilled water is 65 mg / L, and the acid value of the acidic filtrate is 4.8%. The yield of ammonium chloride is 68.2%, and the content is 98.78%.

Claims

1. A method for treating copper ammonia wastewater, characterized in that: The method comprises the following steps: a. One-step copper removal: Put the copper ammonia wastewater into the one-step copper removal reactor, add hydrochloric acid under stirring, and stop adding hydrochloric acid after the system reaches the set pH value, continue stirring, filter, and the filter cake is copper hydroxide. The main reaction formula for one-step copper removal is as follows: NH3·H2O + HCl = NH4Cl + H2O (I) [Cu(NH₃)₄] 2+ + 2Cl - + 2HCl + 2H₂O = Cu(OH)₂↓ + 4NH₄Cl (Two) [Cu(NH3)4] 2+ + 4HCl = Cu 2+ + 4NH4Cl (III); b. Two-step copper removal: The filtrate after the first-step copper removal is transferred to the second-step copper removal reactor, and the diluent prepared with sulfide or organic sulfide is slowly added to the system until the system reaches the set pH value and the system does not change color after adding sulfide or organic sulfide after filtration, and then continue stirring; then hydrochloric acid is added to further adjust the pH of the system to a certain range, and after filtration, it is transferred to the distillation kettle. The filter cake is copper sulfide or organic copper sulfide. The main reaction formula is as follows: [Cu(NH3)4] 2+ + S 2- = CuS↓+4NH3↑ (IV) NH3 + H2O = NH3·H2O (V) Cu 2+ + S 2- = CuS↓ (Six) S 2- +2 H + = H2S↑ (VII) NH3+H + = NH4 + (eight); c. Ammonium chloride recovery: The filtrate system after the two-step copper removal is evaporated and concentrated in a distillation kettle until ammonium chloride begins to precipitate out of the system, the temperature is lowered, hydrochloric acid is added to the system until all the black organic matter in the system is dissolved, and a two-in-one filter is used. The filtrate is strongly acidic, and the filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia water to a certain pH. After filtering, wet ammonium chloride is obtained, and after drying, ammonium chloride by-product is obtained. The main reaction formula is as follows: After concentration and cooling, add acid: Ar-NH2+ H + = Ar-NH3 + Washing filter cake: NH3+ H + = NH4 + NH3·H2O + H + = NH4 + + H2O; d. The water distilled from the distillation kettle is directly subjected to biochemical treatment or used within the workshop. The acidic filtrate from the two-in-one filtration is applied to the one-step copper removal system, and the obtained washing liquid is repeatedly applied after adding ammonia water.

2. The method for treating copper ammonia wastewater according to claim 1, wherein: In the step a, the hydrochloric acid is industrial hydrochloric acid or applied acidic filtrate, the acid value of industrial hydrochloric acid is 25-35%, and the acid value of applied acidic filtrate is 2-8%.

3. The method for treating copper ammonia wastewater according to claim 1, wherein: After adding hydrochloric acid, the pH value of the system is 4~6. After stopping the addition of acid, continue stirring for 1~2 hours. The pH value of the system remains unchanged at 4~6 before filtration.

4. The method for treating copper ammonia wastewater according to claim 1, wherein: In the step b, the sulfide is sodium sulfide or potassium sulfide inorganic sulfide, the organic sulfide is mercaptan or thiophenol organic sulfide, and the concentration of the dilution prepared by the sulfide or organic sulfide is 5-30%.

5. The method for treating copper ammonia wastewater according to claim 1, wherein: In the step b, after adding sulfide, the pH value is adjusted to 7-9, stirring is continued for 1-3 hours, and hydrochloric acid is added to adjust the pH value to 4-6.

6. The method for treating copper ammonia wastewater according to claim 1, characterized in that: In the step c, the distillation and concentration adopts normal pressure or slightly negative pressure distillation, the vacuum degree is 0~-0.05MPa, and the concentration ratio is 2:1~5:

1.

7. The method for treating copper ammonia wastewater according to claim 1, characterized in that: In the step c, the temperature is lowered to 10-30° C. after crystallization, and after hydrochloric acid is added, the acid value of the system is 2-8%.

8. The method for treating copper ammonia wastewater according to claim 1, characterized in that: The ammonia content in the saturated ammonium chloride solution of the dilute ammonia water is 1-5%, and the pH value of the filtrate after washing is 4-6.