A method for efficiently separating copper from ammonia-alkaline etching waste liquid
Through two-step ammonia vaporization and hydrazine reduction, efficiently separated copper from ammonia alkaline etching waste liquid, solving the problems of low copper recovery and high cost in the prior art, and realizing the production of high-purity copper powder and solid waste resources. Safe disposal.
Patent Information
- Application Number
- CN202210585931.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-05-27
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2042-05-27
AI Technical Summary
When the prior art is separated from ammonia alkaline etching waste liquid, the copper recovery rate is not high and the cost is high. The single ammonia vaporization process cannot completely remove ammonia, resulting in a lot of impurities in the product, affecting the efficient value-added utilization of solid waste resources.
The ammonia vaporization process is used to reduce the free ammonia concentration, precipitation filtration obtains Cu2(OH)3Cl, which is converted into Cu(OH)2 through alkali washing, and then hydrazine hydrate is added to the hydrazine reduction reactor, nitrogen is used to remove dissolved oxygen, and copper ions are realized. The efficient reduction of the copper powder is made into elemental copper powder, and finally returned to the etching production line through filtrate preparation.
The production of high-purity copper powder is achieved, the process cost is reduced, the copper recovery rate is improved, and the copper removal liquid is not polluted, which is suitable for the recycling of solid waste resources.
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Figure CN114908255B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of solid waste disposal and resource utilization, and in particular to a method for efficiently separating copper from ammonia alkaline etching waste liquid. Background Art
[0002] With the rapid development of the electronic information industry, the demand for printed circuit boards as its pillar industry is increasing. This process uses chemical etching liquid to etch the copper foil covered on the substrate to form a printed circuit. Due to the refinement of the production process of the electronic industry and the gradual improvement of environmental protection requirements, the composition and formula of chemical etching liquid has gradually developed from extensive to refined. Ammonia alkaline etching liquid has the advantages of stable solution, low operating temperature, fast etching rate, and long service life. It has gradually become the mainstream in the field of printed circuit board etching.
[0003] The main methods for separating copper from ammonia alkaline etching solutions are: acidification, alkalization, solution extraction, electrolysis, chemical precipitation, liquid membrane separation, and liquid phase reduction. At present, the industrial disposal and recovery products of etching waste liquid usually contain more impurities and have lower quality. They are mainly supplied to the upstream or midstream of the product chain, and the recovery profit is not high. Producing high-quality copper products through economical and efficient process routes and supplying them to the downstream of the copper industry chain, such as the power, electronics industry, and high-tech fields, is a way to achieve efficient and value-added utilization of solid waste resources.
[0004] Ammonia alkaline etching solution has the characteristics of high concentration of copper, ammonia and chlorine, and low content of other impurities. After evaporating ammonia, copper salt precipitation can be obtained to separate copper ions. This process is low in cost and the copper product obtained has few impurities. However, copper ions react with NH 3 OH - , Cl - They combine to form a variety of complexes, so a single ammonia evaporation process cannot completely evaporate the ammonia, and the copper recovery rate is not high.
[0005] Chinese patent 201210023824.1 discloses a method and device for producing nano copper powder with alkaline etching waste liquid and the waste liquid can be regenerated. Hydrazine is used as a reducing agent, and the reduction products are nitrogen and water that do not cause environmental pollution. No new impurities are introduced during etching, so the copper removal liquid can be returned to the etching process to achieve waste liquid regeneration and recycling, and achieve the purpose of harmless disposal of solid waste. This method has a simple process, no secondary pollution, and high product purity. However, the amount of hydrazine used is large, and the molar ratio of hydrazine to copper ion is (0.8~1):1, and the complete recovery of copper cannot be achieved. The process cost is high, which is not conducive to engineering implementation. Summary of the invention
[0006] In view of the above technical problems existing in the prior art, the purpose of the present invention is to provide a method for efficiently separating copper from ammonia-alkaline etching waste liquid. The present invention provides an economical and efficient method for separating copper from ammonia-alkaline etching liquid, realizing waste liquid regeneration and recycling, while reducing costs, obtaining high-quality copper products, and efficiently increasing the value of solid waste resources.
[0007] The purpose of the present invention is achieved through the following technical solutions:
[0008] A method for efficiently separating copper from an ammonia alkaline etching solution, comprising first evaporating ammonia to reduce the concentration of free ammonia in the etching solution, and then precipitating and filtering to obtain Cu 2 (OH) 3 Cl, after alkali washing, is converted into Cu(OH) with a purity of >99.9% 2 The product is then added to the filtrate containing a small amount of copper into the hydrazine reduction reactor, nitrogen is introduced to remove dissolved oxygen, and hydrazine hydrate is added at a molar ratio of (0.55-0.65) to copper ions:1 to reduce the remaining copper ions to elemental copper powder. Finally, the copper powder product (purity>99.95%) and the copper removal solution (containing only chlorine and ammonia) are obtained by filtration. The copper removal solution is prepared and returned to the etching production line.
[0009] Furthermore, the present invention provides a method for efficiently separating copper from ammonia-alkaline etching waste liquid, which specifically comprises the following steps:
[0010] 1) Ammonia evaporation: the alkaline etching waste liquid has a copper ion content of 150-170 g / L, an ammonia content of 130-170 g / L and a chloride ion content of 170-180 g / L. The alkaline etching waste liquid is added into an ammonia evaporation kettle, and free ammonia is evaporated by heating. The evaporated free ammonia is passed into an ammonia absorption tower, and ammonia is recovered by absorption using circulating water spraying;
[0011] 2) Precipitation and filtration: The mother liquor after ammonia evaporation in step 1) is cooled and allowed to stand for 2 to 4 hours to precipitate copper salt, and the copper salt precipitate is separated by plate and frame filter pressing to obtain a filtrate;
[0012] 3) Alkaline washing conversion: The copper salt precipitate obtained in step 2) is dechlorinated by an alkaline washing process, and then washed with water and dried to obtain a copper hydroxide product;
[0013] 4) Hydrazine reduction: Add hydrazine hydrate to the filtrate obtained in step 2) for reduction reaction, and reduce the remaining copper ions in the filtrate to elemental copper powder. Finally, after filtration and precipitation, copper powder and a copper removal solution containing high concentrations of chlorine and ammonia are obtained. The copper removal solution can be returned to the etching production line after preparation.
[0014] Preferably, the free ammonia evaporated in step 1) is passed into an ammonia absorption tower, and ammonia is recovered by spraying with circulating water to absorb the ammonia. The concentration of absorbed liquid ammonia is <3 mol / L, and no ammonia nitrogen waste gas is discharged.
[0015] Preferably, in step 1), the evaporation temperature is 105-115° C., and the evaporation time is 60-80 min.
[0016] Preferably, in step 1), after the ammonia evaporation is completed, the volume of the solution is 1 / (2.5-3) of the original volume.
[0017] Preferably, the copper ions filtered into the filtrate in step 2) account for 13-18% of the total copper.
[0018] Preferably, in step 3), the alkaline washing process is to use NaOH solution to carry out alkaline washing conversion reaction on the copper salt precipitate, and the concentration of NaOH solution is 0.5-1.5 mol / L, and more preferably 1.0 mol / L.
[0019] Preferably, in step 3), the alkali washing conversion reaction time is 5 to 20 minutes.
[0020] Preferably, before the reduction reaction in step 4), nitrogen is introduced into the filtrate to remove dissolved oxygen (oxygen content < 0.1%), and the entire reaction process is carried out under a nitrogen atmosphere.
[0021] Preferably, in step 4), the reduction temperature is 70-90° C., the reduction time is 15-30 min, and the addition rate of hydrazine hydrate to the filtrate is 8-25 g / L.min, that is, the addition rate of hydrazine hydrate to 1 L of filtrate is 8-25 g / min.
[0022] Preferably, the molar ratio of hydrazine hydrate added in step 4) to copper ions is (0.5-0.65):1.
[0023] The above scheme of the present invention has the following beneficial effects:
[0024] 1. The present invention uses an ammonia evaporation process to separate most of the copper ions in the etching solution to obtain a copper hydroxide product, and then uses a hydrazine reduction method to separate the remaining copper ions in the etching solution to obtain a high-purity copper powder. The product obtained by this method has high added value.
[0025] 2. The present invention adopts a two-step method of ammonia evaporation and hydrazine reduction to separate copper ions in the etching solution, which greatly reduces the cost and has a high copper recovery rate.
[0026] 3. The final decoppering solution of the present invention contains only ammonia and chlorine, which can be returned to the etching production line without generating secondary pollution, which is beneficial to the safe disposal of solid waste.
[0027] 4. The present invention adopts hydrazine reduction in a nitrogen atmosphere to prepare copper powder, which greatly improves the utilization rate of hydrazine and further reduces the cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1The copper salt precipitate (Cu 2 (OH) 3 Cl precipitation) XRD pattern;
[0029] Figure 2 Cu(OH) prepared in Example 1 of the present invention 2 XRD pattern of the product;
[0030] Figure 3 The XRD pattern of Cu powder prepared in Example 1 of the present invention;
[0031] Figure 4 The copper recovery results of the overall process under different influencing conditions under the single factor influence investigation of the hydrazine reduction step in Example 1 of the present invention are compared. DETAILED DESCRIPTION
[0032] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.
[0033] Example 1
[0034] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0035] (2) After evaporating ammonia for 60 minutes, heating was stopped to obtain 1.2L of recovered ammonia water with a concentration of 5.4mol / L. The mother liquor after evaporation was cooled and allowed to stand for 4 hours. After precipitation was complete, it was filtered to obtain Cu 2 (OH) 3 Cl precipitation and 350ml filtrate 1. Among them, the Cu 2 (OH) 3 The XRD pattern of Cl precipitation is shown in Figure 1 shown.
[0036] (3) Cu 2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was placed in an oven at 60°C for drying. 2 The XRD pattern of the product is as follows Figure 2 shown.
[0037] (4) The filtrate 1 contained 25 g of copper ions, 60 g of ammonia, and 141 g of chloride ions. 350 ml of the filtrate 1 was added to a hydrazine reduction reactor and heated to 90°C. Nitrogen was passed through the reactor to drive out oxygen for 15 min before the reaction. Then 12 g of hydrazine hydrate (the molar ratio of hydrazine to copper ions was 0.6:1) was added at a rate of 3 g / min (hydrazine hydrate was added within 4 min). Nitrogen was continuously passed through the reactor to keep the entire reaction process under a nitrogen atmosphere. The reaction was stopped after 20 min.
[0038] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product. The XRD pattern of the copper powder product is as follows: Figure 3 shown.
[0039] (6) Determine the residual copper ion concentration in filtrate 2 and calculate the copper recovery rate of the overall process to be above 99.8%. The copper recovery rate of the overall process is calculated as follows: (copper content in ammonia-alkaline etching solution - copper content in filtrate 2) / copper content in ammonia-alkaline etching solution * 100%.
[0040] (7) Filtrate 2 is mixed with recovered ammonia and returned to the etching process.
[0041] From Example 1 Figure 1-3 It can be seen that the product has few impurities and high purity, so the product quality is good.
[0042] The experimental method of Example 1 was repeated to investigate the single factor effect of the reaction conditions of hydrazine reduction in step 4). Under the conditions of keeping the heating temperature at 90°C and the hydrazine hydrate feed amount at 12 g (i.e., the molar ratio of hydrazine to copper ion was 0.6:1), the copper recovery rate of the overall process was changed to 10, 20, 30, and 40 min. Figure 4 (A). Under the conditions of keeping the reaction time at 20 min and the amount of hydrazine hydrate at 12 g (i.e. the molar ratio of hydrazine to copper ion is 0.6:1), the copper recovery rate of the overall process at the reaction temperature of 70, 80, 90, and 100 °C is shown in Figure 4 (B). Under the conditions of keeping the heating temperature at 90°C and the reaction time at 20 min, the copper recovery rate of the overall process was shown in Figure 2. Figure 4 (C) in.
[0043] from Figure 4It can be seen that in the hydrazine reduction reaction process, when the reaction temperature is 70-90°C, the reaction time is 20-30min, and the molar ratio of hydrazine to copper ions is 0.6-0.8:1, the copper recovery rate of the overall process can basically achieve a beneficial effect of more than 99.8%.
[0044] Example 2
[0045] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0046] (2) After evaporating ammonia for 70 minutes, heating was stopped to obtain 1.26L of recovered ammonia water with a concentration of 5.5mol / L. The mother liquor after evaporation was cooled and allowed to stand for 4 hours. After precipitation was complete, it was filtered to obtain Cu 2 (OH) 3 Cl precipitate and 300 ml of filtrate 1.
[0047] (3) Cu 2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was dried in an oven at 60°C.
[0048] (4) The filtrate 1 was determined to contain 21 g of copper ions, 52 g of ammonia, and 139 g of chloride ions. 300 ml of the filtrate 1 was added to a hydrazine reduction reactor and heated to 90°C. Nitrogen was passed through the reactor for 15 min to drive out oxygen before the reaction. Then 10 g of hydrazine hydrate (the molar ratio of hydrazine to copper ions was 0.6:1) was added at a rate of 2.5 g / min. Nitrogen was continuously passed through the reactor to keep the entire reaction process under a nitrogen atmosphere. The reaction was stopped after 20 min.
[0049] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product.
[0050] (6) The residual copper ion concentration in filtrate 2 was determined, and the copper recovery rate of the overall process was calculated to be above 99.8%.
[0051] (7) Filtrate 2 is mixed with recovered ammonia and returned to the etching process.
[0052] Example 3
[0053] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0054] (2) After evaporating ammonia for 60 minutes, stop heating, cool, and let stand for 4 hours. After precipitation is complete, filter and obtain Cu 2 (OH) 3 Cl precipitate and 350 ml of filtrate 1.
[0055] (3) Cu 2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was dried in an oven at 60°C.
[0056] (4) The filtrate 1 contained 25 g of copper ions, 60 g of ammonia, and 141 g of chloride ions. 350 ml of the filtrate 1 was added to a hydrazine reduction reactor and heated to 90°C. Nitrogen was passed through the reactor for 15 min to drive out oxygen before the reaction. Then 12 g of hydrazine hydrate (the molar ratio of hydrazine to copper ions was 0.6:1) was added at a rate of 5 g / min. Nitrogen was continuously passed through the reactor to keep the entire reaction process under a nitrogen atmosphere. The reaction was stopped after 20 min.
[0057] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product.
[0058] (6) The residual copper ion concentration in filtrate 2 was determined, and the copper recovery rate of the overall process was calculated to be above 99.5%.
[0059] (7) Filtrate 2 is mixed with recovered ammonia and returned to the etching process.
[0060] Example 4
[0061] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0062] (2) After evaporating ammonia for 60 minutes, stop heating, cool, and let stand for 4 hours. After precipitation is complete, filter and obtain Cu 2 (OH) 3 Cl precipitate and 350 ml of filtrate 1.
[0063] (3) Cu2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was dried in an oven at 60°C.
[0064] (4) The filtrate 1 contained 25 g of copper ions, 60 g of ammonia, and 141 g of chloride ions. 350 ml of the filtrate 1 was added to the hydrazine reduction reactor and heated to 80°C. Nitrogen was passed through the reactor for 15 min to drive out oxygen before the reaction. Then 12 g of hydrazine hydrate (the molar ratio of hydrazine to copper ions was 0.6:1) was added at a rate of 3 g / min. Nitrogen was continuously passed through the reactor to keep the entire reaction process under a nitrogen atmosphere. The reaction was stopped after 20 min.
[0065] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product.
[0066] (6) The residual copper ion concentration in filtrate 2 was determined, and the copper recovery rate of the overall process was calculated to be above 99.5%.
[0067] (7) Filtrate 2 is mixed with recovered ammonia and returned to the etching process.
[0068] Example 5
[0069] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0070] (2) After evaporating ammonia for 60 minutes, stop heating, cool, and let stand for 4 hours. After precipitation is complete, filter and obtain Cu 2 (OH) 3 Cl precipitate and 350 ml of filtrate 1.
[0071] (3) Cu 2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was dried in an oven at 60°C.
[0072] (4) The filtrate 1 contained 25 g of copper ions, 60 g of ammonia, and 141 g of chloride ions. 350 ml of the filtrate 1 was added to a hydrazine reduction reactor and heated to 90°C. Nitrogen was passed through the reactor for 15 min to drive out oxygen before the reaction. Then 12 g of hydrazine hydrate (the molar ratio of hydrazine to copper ions was 0.6:1) was added at a rate of 3 g / min. Nitrogen was continuously passed through the reactor to keep the entire reaction process under a nitrogen atmosphere. The reaction was stopped after 40 min.
[0073] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product.
[0074] (6) The residual copper ion concentration in filtrate 2 was determined, and the copper recovery rate of the overall process was calculated to be above 99.5%.
[0075] (7) Filtrate 2 is mixed with recovered ammonia and returned to the etching process.
[0076] Example 6
[0077] (1) The ammonia alkaline etching solution contains 160 g / L copper, 170 g / L ammonia, and 178 g / L chlorine. Take 1000 ml of the etching solution and add it to the ammonia evaporator. Heat it to 110°C. The distilled ammonia gas is passed into the absorption tower. Circulating water spray is used for secondary absorption and recovery of ammonia.
[0078] (2) After evaporating ammonia for 60 minutes, heating was stopped to obtain 1.2L of recovered ammonia water with a concentration of 5.4mol / L. The mother liquor was cooled and allowed to stand for 4 hours. After precipitation was complete, it was filtered to obtain Cu 2 (OH) 3 Cl precipitate and 350 ml of filtrate 1.
[0079] (3) Cu 2 (OH) 3 The Cl precipitate was placed in a 1.0 mol / L NaOH solution for alkaline washing and conversion. After reacting for 5 min, it was filtered and then washed twice with distilled water to obtain blue Cu(OH) 2 The powder was dried in an oven at 60°C.
[0080] (4) The filtrate 1 was found to contain 25 g of copper ions, 60 g of ammonia, and 141 g of chloride ions. 350 ml of the filtrate 1 was added to a hydrazine reduction reactor, heated to 90°C, and then 17.5 g of hydrazine hydrate was added (the molar ratio of hydrazine to copper ions was 0.9:1). The hydrazine hydrate addition rate was 3 g / min. The entire reaction process was carried out under air atmosphere and the reaction was stopped after 20 min.
[0081] (5) After the hydrazine reduction reaction, vacuum filtration is performed to obtain copper powder and colorless filtrate 2. The copper powder is washed twice with distilled water and then vacuum dried to obtain a copper powder product.
[0082] (6) The residual copper ion concentration in filtrate 2 was measured, and the copper recovery rate of the hydrazine reduction reaction step was calculated to be 68%.
[0083] By comparing the experimental results of Examples 1 to 5 with those of Example 6, it can be seen that introducing nitrogen into the filtrate in the hydrazine reduction reaction process to remove dissolved oxygen and improve the utilization rate of the reducing agent is crucial to improving the copper recovery rate.
[0084] The applicant also uses the method disclosed in Chinese Patent No. 201210023824.1 to recover copper from alkaline etching waste liquid. The alkaline etching waste liquid is not treated with ammonia evaporation, but directly undergoes a hydrazine reduction reaction process. The molar ratio of hydrazine hydrate to copper ions in the waste liquid is fixed at 0.8:1. A series of conditions such as the reaction temperature, reaction time, and dripping speed of hydrazine hydrate in the hydrazine reduction reaction process are optimized. After the hydrazine reduction reaction, the residual copper ion concentration in the filtrate is filtered and measured, and the copper recovery rate is calculated to be no more than 65%. The experimental effect is obviously not as good as that of the present invention.
[0085] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be regarded as being limited to the specific forms described in the embodiments.
Claims
1. A method for efficiently separating copper from ammonia-alkaline etching waste liquid, characterized in that: The steps include: 1) Ammonia evaporation: the alkaline etching waste liquid has a copper ion content of 150-170 g / L, an ammonia content of 130-170 g / L and a chloride ion content of 170-180 g / L. The alkaline etching waste liquid is added into an ammonia evaporation kettle, and free ammonia is evaporated by heating. The evaporated free ammonia is passed into an ammonia absorption tower, and ammonia is recovered by absorption using circulating water spraying; 2) Precipitation and filtration: The mother liquor after ammonia evaporation in step 1) is cooled and allowed to stand for 2 to 4 hours to precipitate copper salt, and the copper salt precipitate is separated by plate and frame filter pressing to obtain a filtrate; 3) Alkaline washing conversion: The copper salt precipitate obtained in step 2) is dechlorinated by an alkaline washing process, and then washed with water and dried to obtain a copper hydroxide product; 4) Hydrazine reduction: Add hydrazine hydrate to the filtrate obtained in step 2) for reduction reaction, reduce the remaining copper ions in the filtrate to elemental copper powder, and finally filter and precipitate to obtain copper powder and a copper removal solution containing high concentrations of chlorine and ammonia. The copper removal solution can be returned to the etching production line after preparation; In step 1), the evaporation temperature is 105-115°C, and the evaporation time is 60-80 min; after the ammonia evaporation in step 1), the volume of the solution is 1 / (2.5-3) of the original volume; In step 4), nitrogen is introduced into the filtrate to remove dissolved oxygen before the reduction reaction, and the entire reaction process is carried out under a nitrogen atmosphere; The molar ratio of hydrazine hydrate to copper ions added in step 4) is (0.5-0.65):
1.
2. A method for efficiently separating copper from ammonia-alkaline etching waste liquid as claimed in claim 1, characterized in that: The copper ions filtered into the filtrate in step 2) account for 13-18% of the total copper.
3. A method for efficiently separating copper from ammonia-alkaline etching waste liquid as claimed in claim 1, characterized in that: In step 3), the alkaline washing process uses NaOH solution to carry out alkaline washing conversion reaction on the copper salt precipitate, and the concentration of NaOH solution is 0.5~1.5mol / L.
4. A method for efficiently separating copper from ammonia-alkaline etching waste liquid as claimed in claim 3, characterized in that: The concentration of NaOH solution is 1.0 mol / L, and the alkali washing conversion reaction time is 5 to 20 minutes.
5. A method for efficiently separating copper from ammonia-alkaline etching waste liquid as claimed in claim 1, characterized in that: In step 4), the reduction temperature is 70-90° C., the reduction time is 15-30 min, and the addition rate of hydrazine hydrate to the filtrate is 8-25 g / L.min.