A method for treating copper ammonia wastewater

Abstract

A copper ammonia wastewater treatment method, comprising: the copper ammonia wastewater is punched into a one-step copper removal reaction kettle, hydrochloric acid is added under stirring, after reaching a set pH value, the addition of hydrochloric acid is stopped, stirring is continued, filtration is performed, and the filter cake is copper hydroxide; the filtrate is transferred to a two-step copper removal reaction kettle, a dilute solution of sulfide or organic sulfide is slowly added, after reaching a set pH value and filtration, when the sulfide or organic sulfide no longer changes color, stirring is continued; hydrochloric acid is added to adjust the pH, filtration is performed, and the filter cake is copper sulfide or organic copper sulfide; the filtrate is concentrated by evaporation in a distillation kettle, until the system starts to precipitate ammonium chloride, cooling is performed, hydrochloric acid is added, until all the organic matter is dissolved, two-in-one filtration is performed, the filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia water, filtration is performed to obtain ammonium chloride wet products, drying is performed to obtain ammonium chloride by-products, and the acidic filtrate of the two-in-one filtration is used in the one-step copper removal system. The method realizes effective separation of copper and ammonia, avoids waste of resources, and has high comprehensive utilization rate.

Description

Technical Field

[0001] This invention relates to a method for treating copper ammonia wastewater, belonging to the field of industrial wastewater treatment technology. Background Technology

[0002] The copper-ammonia wastewater originates from the process of preparing 4,4-aminosulfone by ammoniation of 4,4-chlorophenyl sulfone. The general process in the workshop is as follows: a large amount of ammonia is dissolved in a solution containing cuprous chloride to prepare a copper-ammonia ion solution containing a large amount of free ammonia, which serves as a catalyst. Then, 4,4-chlorophenyl sulfone is added to the copper-ammonia ion solution, reacting to generate 4,4-aminosulfone. After the reaction is complete, a portion of the ammonia solution (10-20% concentration) is distilled off at high temperature. The remaining system is filtered to obtain crude 4,4-aminosulfone, which is then refined to obtain the final product. The filtrate is the copper-ammonia wastewater.

[0003] The workshop's copper-ammonia wastewater has a pH of 7-10, is a dark blue solution, and has a specific gravity of 1.01-1.05 g / mL. The main substance in the system is NH4+. + Cu 2+ Cl - , NH3, NH3·H2O, [Cu(NH3)4] 2+ OH - Residual amino sulfones (Ar-NH2), etc.

[0004] The conventional treatment method for copper-ammonia wastewater involves directly feeding the wastewater into a triple-effect evaporation system, with the effluent flowing directly into a biological treatment system, and the concentrated wastewater undergoing spray drying. This method typically results in effluent with high ammonia nitrogen levels, placing significant pressure on the biological treatment system and incurring high treatment costs. Furthermore, the solids obtained after spray drying contain large amounts of copper and ammonium salts, which are difficult to separate and can only be treated as industrial solid waste, leading to substantial waste. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a method for treating copper-ammonia wastewater. Through one-step and two-step copper removal, two byproducts, copper hydroxide and copper sulfide (or organic copper sulfide), are obtained, achieving the separation of metallic copper. After concentration, hydrochloric acid is added to separate organic matter and ammonium chloride. The distillate has the characteristics of low COD and low ammonia nitrogen, and can be directly used for biological treatment or internal use in the workshop, with low treatment costs.

[0006] The technical solution adopted by this 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: The copper-ammonia wastewater is pumped into a one-step copper removal reactor. Hydrochloric acid is added while stirring until the system reaches the set pH value. Then, the addition of hydrochloric acid is stopped, stirring continues, and the mixture is filtered. 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 (II) [Cu(NH3)4] 2+ + 4HCl = Cu 2+ + 4NH4Cl (III); b. Two-step copper removal: Transfer the filtrate from the first-step copper removal to the two-step copper removal reactor. Slowly add a diluted solution of sulfide or organic sulfide to the system until the system reaches the set pH value and the system no longer changes color after filtration when sulfide or organic sulfide is added. Continue stirring. Then add hydrochloric acid to further adjust the pH of the system to a certain range. After filtration, transfer the filtrate to a distillation vessel. 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. The system is then cooled, and hydrochloric acid is added until all the black organic matter dissolves. The mixture is then filtered using a two-in-one filter. The filtrate is strongly acidic. The filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia to a specific pH. After filtration, wet ammonium chloride is obtained. After drying, ammonium chloride is obtained as a byproduct. The main reaction formulas are as follows: After concentration and cooling, acid is added: 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 in the workshop. The acidic filtrate from the two-in-one filtration is reused in the one-step copper removal system. The resulting washing solution is repeatedly reused after adding ammonia.

[0007] In the above-mentioned method for treating copper ammonia wastewater, in step a, the hydrochloric acid is industrial hydrochloric acid or a modified acidic filtrate, the acid value of industrial hydrochloric acid is 25-35%, and the acid value of the modified 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. Before filtration, the pH value of the system remains unchanged at 4-6.

[0009] In the above-mentioned method for treating copper ammonia wastewater, in step b, the sulfide is an inorganic sulfide such as sodium sulfide or potassium sulfide, the organic sulfide is an organic sulfide such as thiol or thiophenol, and the concentration of the diluted solution prepared from the sulfide or organic sulfide is 5-30%.

[0010] In the above-mentioned method for treating copper ammonia wastewater, in step b, after adding sulfide to bring the pH value to 7-9, stirring 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, step c involves distillation and concentration using atmospheric or slightly negative pressure distillation, with a vacuum degree of 0 to -0.05 MPa and a concentration ratio of 2:1 to 5:1.

[0012] In the above-mentioned method for treating copper ammonia wastewater, in step c, after crystallization, the temperature is lowered to 10~30℃, and after adding hydrochloric acid, 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 the dilute ammonia water is 1-5%, and the pH value of the filtrate after washing is 4-6.

[0014] The beneficial effects of this invention are: In this invention's copper-ammonia wastewater treatment method, after one-step and two-step copper removal, two byproducts, copper hydroxide and copper sulfide (or organic copper sulfide), are obtained, achieving the separation of metallic copper. The copper-removed system is then concentrated by distillation, resulting in low COD and ammonia nitrogen values ​​in the distillate, significantly reducing water treatment costs or allowing for direct use within the workshop. After concentration, hydrochloric acid is added to separate organic matter and ammonium chloride, yielding high-quality, high-purity ammonium chloride. The treatment process is simple and easy to implement, with low production costs and mild conditions, achieving effective separation of copper and ammonia, turning waste into treasure, avoiding resource waste, and demonstrating high comprehensive utilization. Detailed Implementation

[0015] After copper removal in one step, a green to yellowish-green copper hydroxide solid is obtained with a yield greater than 90%. A two-step copper removal is performed by adding sulfides. The two-step copper removal must meet the following conditions: (1) the system filtrate is a colorless to light yellow liquid; (2) the pH of the system filtrate is 6-9; (3) no black substance is generated after adding sulfides or organic sulfides to the system filtrate, indicating that the two-step copper removal is qualified. After the two-step copper removal process is successful, hydrochloric acid is added to the system to adjust the pH value. This is because during the two-step copper removal, the amount of sulfides or organic sulfides added is slightly excessive, resulting in an alkaline or neutral pH (pH≥7). If the alkaline system is filtered and the filtrate is directly concentrated, ammonia will enter the distilled water, accelerating the hydrolysis of ammonium sulfide. During high-temperature distillation, ammonium chloride in the neutral system will also hydrolyze. Both ammonium sulfide and ammonium chloride hydrolysis will cause a high ammonia nitrogen value in the distilled water. Therefore, before entering the distillation stage, hydrochloric acid is added to adjust the system to acidity, inhibiting the hydrolysis of ammonium sulfide and ammonium chloride, reducing the ammonia nitrogen value in the effluent, and increasing the recovery rate of ammonium chloride in the next step. Controlling the amount of acid added to maintain a pH of 4-6 minimizes the hydrolysis of ammonium chloride, resulting in lower ammonia nitrogen levels in the distilled water.

[0016] This invention involves evaporation and concentration after the two-step copper removal process. The atmospheric distillation temperature is 105-115℃, and the micro-negative pressure distillation temperature is around 100℃. The concentration ratio is controlled at 2:1-5:1. Water with low COD and low ammonia nitrogen is distilled off. Ammonium chloride in the system is concentrated to saturation and precipitates. After cooling, black organic matter (mainly amino-containing organic matter) in the system precipitates out. Then, hydrochloric acid is added to the concentrated system to dissolve all the organic matter back into the system. The system is then filtered, and the filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia until the pH reaches 4-6. After filtration, wet ammonium chloride is obtained. After drying, ammonium chloride byproduct is obtained, completing the recovery and extraction of ammonium chloride. The organic matter is carried into the first-step copper removal process along with the acidic filtrate for reuse.

[0017] The present invention will be further described below with reference to the embodiments.

[0018] The method described in this application is used to treat industrial wastewater. The copper ion content in the copper-ammonia wastewater system is 0.1-1.0%, the total NH3 content in the system is 1-10%, and the COD of the system is 1000-10000 mg / L.

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

[0020] Example 1

[0021] Before treatment, the copper ammonia wastewater 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 NH3 content of 6.38%.

[0022] S1: The copper-ammonia wastewater was pumped into a one-step copper removal reactor. Hydrochloric acid was added while stirring until the system pH reached 5.5. The addition of hydrochloric acid was then stopped, and stirring continued for 2 hours, maintaining a constant system pH. The system was then filtered and transferred to a two-step copper removal reactor. The filtrate after the one-step copper removal was light green; the filter cake was copper hydroxide, which was blue-green. The copper yield was tested to be 94.20%.

[0023] S2: Slowly add 10% sodium sulfide solution to the system until the pH reaches 8.0. The system becomes colorless and transparent. After filtration, adding sodium sulfide again does not change the color, indicating that the two-step copper removal is complete. Continue stirring for 2 hours. Then, add hydrochloric acid to adjust the pH to 5, filter again, and transfer to a distillation vessel. The treated filtrate is pale yellow and transparent, with no ammonia odor, and a COD of 1020 mg / L. The filter cake is black copper sulfide, and the copper yield is tested to be 5.81%.

[0024] S3: The copper-removed system was evaporated and concentrated in a distillation kettle until ammonium chloride began to precipitate. The temperature was then lowered to 20°C. Hydrochloric acid was added to the system until all the black organic matter dissolved. The mixture was then filtered using a two-in-one filter, followed by washing with a saturated ammonium chloride solution containing 2% ammonia until the pH reached 5. After filtration, wet ammonium chloride was obtained, which was dried to obtain ammonium chloride as a byproduct. The concentration ratio was 4.5:1, the COD of the distillate was 120 mg / L, the ammonia nitrogen value of the distillate was 80 mg / L, and the acid value of the acidic filtrate was 3.5%. The yield of ammonium chloride was 62.3%, and the purity was 98.72%.

[0025] Example 2

[0026] Before treatment, the copper ammonia wastewater was dark blue, with a COD of 3600 mg / L, a pH of 8.0, a copper ion content of 0.52%, a total NH3 content of 8.24%, and an ammonium chloride content of 25.6% in the mother liquor.

[0027] S1: The copper-ammonia wastewater was pumped into a one-step copper removal reactor. While stirring, the acidic filtrate from step S3 of Example 1 was added until the system pH reached 6.5. Hydrochloric acid was then added until the system pH reached 5.0, at which point the addition of hydrochloric acid was stopped. Stirring continued for 2 hours, maintaining a constant system pH. The system was then filtered and transferred to a two-step copper removal reactor. The filtrate after the one-step copper removal was light green; the filter cake was green copper hydroxide, with a copper yield of 91.32%.

[0028] S2: Slowly add 8% sodium sulfide solution to the system until the pH reaches 7.0. The system becomes colorless and transparent. After filtration, adding sodium sulfide again does not change the color, indicating that the two-step copper removal is complete. Continue stirring for 2 hours. Then, add hydrochloric acid to adjust the pH to 4.5, filter, and transfer to a distillation vessel. The treated filtrate is colorless and transparent, with no ammonia odor, and a COD of 1050 mg / L. The filter cake is black copper sulfide, and the copper yield is 8.65%.

[0029] S3: The copper-removed system was evaporated and concentrated in a distillation kettle until ammonium chloride began to precipitate. The temperature was then lowered to 18°C. Hydrochloric acid was added to the system until all the black organic matter dissolved. The mixture was then filtered using a two-in-one filter, followed by washing with a saturated ammonium chloride solution containing 2% ammonia until the pH reached 5. After filtration, wet ammonium chloride was obtained, which was dried to obtain ammonium chloride as a byproduct. The concentration ratio was 3.5:1, the COD of the distillate was 110 mg / L, the ammonia nitrogen value of the distillate was 50 mg / L, and the acid value of the acidic filtrate was 4.5%. The yield of ammonium chloride was 85.2%, and the content of ammonium chloride was 99.29%.

[0030] Example 3

[0031] Before treatment, the copper ammonia wastewater 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 content of 6.75%.

[0032] S1: The copper-ammonia wastewater was pumped into a one-step copper removal reactor. Hydrochloric acid was added while stirring until the system pH reached 6.0. The addition of hydrochloric acid was then stopped, and stirring continued for 2 hours, maintaining a constant system pH. The system was then filtered and transferred to a two-step copper removal reactor. The filtrate after the one-step copper removal was light green; the filter cake was green copper hydroxide, with a copper yield of 90.2%.

[0033] S2: Slowly add a 6% organic thiol solution to the system until the pH reaches 7.0. The system becomes colorless and transparent. After filtration, sodium sulfide is added without discoloration, indicating that the two-step copper removal is complete. Continue stirring for 2 hours. Then, hydrochloric acid is added to adjust the pH to 4.5. After filtration, the solution is transferred to a distillation vessel. The treated filtrate is colorless and transparent, with no ammonia odor, and a COD of 1450 mg / L. The filter cake is black organic copper sulfide, with a copper yield of 9.78%.

[0034] S3: The copper-removed system was evaporated and concentrated in a distillation kettle until ammonium chloride began to precipitate. The temperature was then lowered to 20°C. Hydrochloric acid was added to the system until all the black organic matter dissolved. The mixture was then filtered using a two-in-one filter, followed by washing with a saturated ammonium chloride solution containing 2% ammonia until the pH reached 5. After filtration, wet ammonium chloride was obtained, which was dried to obtain ammonium chloride as a byproduct. The concentration ratio was 4.5:1, the COD of the distillate was 100 mg / L, the ammonia nitrogen value of the distillate was 65 mg / L, and the acid value of the acidic filtrate was 4.8%. The yield of ammonium chloride was 68.2%, and the purity was 98.78%.

Claims

1. A method for treating copper ammonia wastewater, characterized in that: The copper-ammonia wastewater originates from the process of preparing 4,4-aminosulfone by ammoniation of 4,4-chlorophenyl sulfone. The main substances in the copper-ammonia wastewater system are: NH4+. + Cu 2+ Cl - , NH3, NH3·H2O, [Cu(NH3)4] 2+ OH - The method comprises the following steps: a residual amino sulfone containing an Ar-NH2 structural unit. a. One-step copper removal: The copper-ammonia wastewater is pumped into a one-step copper removal reactor. Hydrochloric acid is added while stirring until the system reaches the set pH value. Then, the addition of hydrochloric acid is stopped, stirring continues, and the mixture is filtered. 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 (II) [Cu(NH₃)₄] 2+ + 4HCl = Cu 2+ + 4NH₄Cl (III); b. Two-step copper removal: Transfer the filtrate from the first-step copper removal to the two-step copper removal reactor. Slowly add a diluted solution of inorganic or organic sulfides to the system until the system reaches the set pH value and the system no longer changes color after filtration when inorganic or organic sulfides are added. Continue stirring. Then add hydrochloric acid to further adjust the pH of the system to a certain range. After filtration, transfer the solution to a distillation vessel. 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↓ (VI) 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. The system is then cooled, and hydrochloric acid is added until all the black organic matter dissolves. The solution is filtered using a two-in-one filter. The filtrate is strongly acidic. The filter cake is washed with a saturated ammonium chloride solution containing dilute ammonia to a specific pH. After filtration, wet ammonium chloride is obtained. After drying, ammonium chloride is obtained as a byproduct. The main reaction formulas are as follows: After concentration and cooling, acid is added: 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 in the workshop. The acidic filtrate filtered by the two-in-one filter is reused in the one-step copper removal system. The resulting washing solution is repeatedly reused after adding ammonia. In step a, 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. Before filtration, the pH value of the system remains unchanged at 4-6. In step b, after adding inorganic or organic sulfides until the pH value is 7-9, continue stirring for 1-3 hours, and then add hydrochloric acid to adjust the pH value to 4-6. In step c, the ammonia content in the saturated ammonium chloride solution containing dilute ammonia water is 1-5%, and the pH value of the filtrate after washing and filtration is 4-6.

2. The method for treating copper-ammonia wastewater according to claim 1, characterized in that: In step a, the hydrochloric acid is industrial hydrochloric acid with an acid value of 25-35%, and the acid value of the acidic filtrate used is 2-8%.

3. The method for treating copper-ammonia wastewater according to claim 1, characterized in that: In step b, the inorganic sulfide is sodium sulfide or potassium sulfide, the organic sulfide is thiol or thiophenol organic sulfide, and the concentration of the diluted solution prepared from the inorganic or organic sulfide is 5-30%.

4. The method for treating copper-ammonia wastewater according to claim 1, characterized in that: In step c, the evaporation and concentration are carried out by atmospheric pressure or slightly negative pressure distillation, with a vacuum degree of 0 to -0.05 MPa and a concentration ratio of 2:1 to 5:

1.

5. The method for treating copper-ammonia wastewater according to claim 1, characterized in that: In step c, after ammonium chloride precipitates, the temperature is lowered to 10~30℃, and after hydrochloric acid is added, the acid value of the system is 2~8%.