Method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure. The method for removing the metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure comprises the following steps: S1, adding an oxidizing agent into the acidic copper-containing etching wastewater to carry out oxidation-reduction reaction to obtain a pretreatment solution; and S2, phosphoric acid or soluble phosphate is added into the pretreatment solution, the pH is adjusted to 1.3-1.7 through a pH adjusting agent, stirring and filtering are conducted, and the purified copper-containing solution is obtained. According to the method, the removal rate of Fe, Ni, Zn, Ca and Mg is high, high-content copper ions can be kept, a high-purity copper salt product can be recycled and regenerated to be applied to the fields of food, cosmetics, medical treatment, electroplating and the like, hazardous waste can be reduced, economic benefits are improved, and cost is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure. Background Technology

[0002] Chemical etching is an important process in the manufacture of printed circuit boards. In recent years, with the rapid development of the electronics industry, a large amount of etching wastewater has been generated. Commonly used acidic etching wastewater includes copper chloride etching solution and ferric chloride etching solution. If discharged directly without treatment, it will not only lead to the waste and loss of copper resources, but also cause harm to humans and the environment.

[0003] Currently, the method for removing impurities from acidic etching wastewater generally involves adding specific ion exchange resins to adsorb metal impurities and then adding alkali to precipitate and prepare low-purity products. However, ion exchange resins have limited selectivity, generate a large amount of sludge, and due to the solubility product of hydroxides, problems such as incomplete precipitation of metal impurities and enrichment of metal impurities may occur.

[0004] Chinese Patent CN107662988A discloses a method for treating copper-containing acidic etching waste liquid. First, copper oxide is obtained through acid-base neutralization. After washing to remove impurities, the copper oxide is added to the copper-containing micro-etching waste liquid to obtain a copper sulfate electrolyte. The copper sulfate electrolyte is then subjected to secondary electrolysis, completing the waste liquid treatment. However, this technical solution requires electrolysis, making the process complex. Chinese Patent CN104556467B discloses a method and equipment for treating etching waste liquid. The method includes: mixing acidic and alkaline etching waste liquids; adjusting the pH of the mixed etching waste liquid and heating it to cause a neutralization reaction; separating the precipitate and filtrate; and adding a flocculant to the filtrate to flocculate suspended particles and suspended colloidal arsenic. However, this technical solution only removes arsenic impurities. Summary of the Invention

[0005] The objective of this invention is to solve one or more technical problems existing in the prior art and to provide at least one beneficial alternative. Specifically, this invention provides a method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure. The method provided by this invention has high removal rates for Fe, Ni, Zn, Ca, and Mg, and can also maintain a high content of copper ions.

[0006] To achieve the above-mentioned objective, the present invention provides a method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure, comprising the following steps:

[0007] S1. Add an oxidant to the acidic copper-containing etching wastewater to carry out an oxidation-reduction reaction and obtain a pretreatment solution;

[0008] S2. Add phosphoric acid or soluble phosphate to the pretreatment solution, and adjust the pH to 1.3-1.7 using a pH adjuster. Stir, filter, and the purified copper-containing solution is obtained.

[0009] Optionally, the copper concentration in the acidic copper-containing etching wastewater in step S1 is 8-11 wt%, and the acidity is 2-4 mol / L.

[0010] Optionally, the oxidant in step S1 is selected from at least one of sodium chlorate, hydrogen peroxide, potassium chlorate, sodium hypochlorite, and potassium hypochlorite.

[0011] Optionally, the amount of oxidant added in step S1 is 4-6 kg / m³. 3 Acidic copper-containing etching wastewater.

[0012] Optionally, the redox reaction in step S1 takes 20-40 minutes.

[0013] Optionally, the soluble phosphate in step S2 is selected from at least one of sodium phosphate and ammonium phosphate.

[0014] Optionally, the amount of phosphoric acid or soluble phosphate added in step S2 is 1.5-2 times the content of metal impurities in the acidic copper-containing etching wastewater.

[0015] Optionally, the metallic impurities include Fe, Ni, Zn, Ca, and Mg.

[0016] Optionally, the pH adjuster mentioned in step S2 is selected from at least one of ammonia and liquid alkali.

[0017] Optionally, the stirring time in step S2 is 20-40 minutes.

[0018] Optionally, the temperature for both steps S1 and S2 is 20-30°C and the pressure is 0.1013 MPa.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure provided by this invention combines oxidation-reduction treatment with phosphoric acid or soluble phosphate precipitation. By strictly controlling the amount of phosphoric acid or soluble phosphate added and the pH of the solution, it can effectively remove metallic impurities Fe, Ni, Zn, Ca, and Mg from copper-containing etching wastewater while avoiding the loss of copper ions. Testing shows that the removal rate of Fe in copper-containing etching wastewater is >95%, the removal rate of Ni is 100%, the removal rate of Zn is >93%, the removal rate of Ca is >98%, the removal rate of Mg is >98%, and the copper ion loss rate is <0.5%. Therefore, the method of this invention can recycle and regenerate high-purity copper salt products for application in food, cosmetics, medical, electroplating, and other fields, while also reducing hazardous waste generation, improving economic efficiency, and significantly reducing costs. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to the present invention. Detailed Implementation

[0022] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0023] This invention provides a method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure, comprising the following steps:

[0024] S1. Add an oxidant to the acidic copper-containing etching wastewater to carry out an oxidation-reduction reaction and obtain a pretreatment solution;

[0025] S2. Add phosphoric acid or soluble phosphate to the pretreatment solution, and adjust the pH to 1.3-1.7 using a pH adjuster. Stir, filter, and the purified copper-containing solution is obtained.

[0026] The mechanism by which the present invention removes metallic impurities is as follows: First, an oxidant is added to the acidic copper-containing etching wastewater to carry out an oxidation-reduction reaction, oxidizing the ferrous and cuprous ions in the acidic copper-containing etching wastewater into ferric and copper ions, as shown in the following reaction formula: ; Next, phosphoric acid or soluble phosphate is added, and the pH is controlled to allow the metal impurities to react with phosphate ions to form phosphate precipitates, selectively precipitating the metal impurities while minimizing copper loss. The reaction formula is as follows: .

[0027] The pH in step S2 can be 1.3, 1.4, 1.5, 1.6, 1.7, or any combination of two of these. The inventors have discovered that the pH in step S2 needs to be strictly controlled between 1.3 and 1.7. When the pH is below 1.3, the removal rate of metal impurities will decrease, and when the pH is above 1.7, the copper loss rate will increase.

[0028] In some preferred embodiments, the copper concentration in the acidic copper-containing etching wastewater in step S1 is 8-11 wt%, and the acidity is 2-4 mol / L.

[0029] If the concentration and acidity of the acidic copper-containing etching wastewater exceed the above range, sodium chlorate or hydrogen peroxide, ferrous oxide, cuprous ions, and water can be added to adjust the concentration, and ammonia or liquid alkali can be added to adjust the acidity.

[0030] In some preferred embodiments, the oxidant in step S1 is selected from at least one of sodium chlorate, hydrogen peroxide, potassium chlorate, sodium hypochlorite, and potassium hypochlorite.

[0031] More preferably, the oxidant in step S1 is at least one of sodium chlorate and hydrogen peroxide.

[0032] In some preferred embodiments, the amount of oxidant added in step S1 is 4-6 kg / m³. 3 Acidic copper-containing etching wastewater.

[0033] In some preferred embodiments, the redox reaction in step S1 takes 20-40 minutes.

[0034] In some preferred embodiments, the soluble phosphate in step S2 is selected from at least one of sodium phosphate and ammonium phosphate.

[0035] In some preferred embodiments, the amount of phosphoric acid or soluble phosphate added in step S2 is 1.5-2 times the content of metal impurities in the acidic copper-containing etching wastewater.

[0036] Preferably, the metallic impurities include Fe, Ni, Zn, Ca, and Mg.

[0037] The amount of phosphoric acid or soluble phosphate added in step S2 can be 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, or 2 times the metal impurity content in the acidic copper-containing etching wastewater, or any combination thereof. The inventors have discovered that the amount of phosphoric acid or soluble phosphate added in step S2 needs to be strictly controlled. When the amount of phosphoric acid or soluble phosphate added is less than 1.5 times the metal impurity content in the acidic copper-containing etching wastewater, the removal rate of metal impurities will decrease. When the amount of phosphoric acid or soluble phosphate added is greater than 2 times the metal impurity content in the acidic copper-containing etching wastewater, the copper loss rate will increase.

[0038] In some preferred embodiments, the pH adjuster in step S2 is selected from at least one of ammonia and liquid alkali.

[0039] More preferably, the liquid alkali is selected from at least one of sodium hydroxide solution and potassium hydroxide solution.

[0040] In some preferred embodiments, the stirring time in step S2 is 20-40 minutes.

[0041] In some preferred embodiments, the temperature throughout steps S1 and S2 is 20-30°C and the pressure is 0.1013 MPa.

[0042] Example 1

[0043] The acidic copper-containing etching wastewater used in this embodiment is copper etching wastewater from a circuit board factory, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0044] Reference Figure 1 The steps for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure are as follows:

[0045] S1. Add sodium chlorate (addition amount: 5 kg / m³) to the acidic copper-containing etching wastewater. 3 Acidic copper-containing etching wastewater was subjected to an oxidation-reduction reaction for 30 minutes to obtain a pretreated solution.

[0046] S2. Add phosphoric acid (the amount added is 1.5 times the metal impurity content in the acidic copper-containing etching wastewater) to the pretreatment solution, and adjust the pH to 1.5 with 20wt% ammonia water. Stir for 30 minutes, filter, and the purified copper-containing solution is obtained.

[0047] The temperature and pressure throughout steps S1 and S2 are 25°C and 0.1013 MPa.

[0048] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The copper ion loss rate was 0.5%, with a final concentration of 9.89%.

[0049] Fe: 0.9 mg / L, Fe removal rate 95.8%;

[0050] Ni: Not detected, Ni removal rate 100%;

[0051] Zn: 2.7 mg / L, Zn removal rate 93.4%;

[0052] Ca: 0.02 mg / L, Ca removal rate 99.9%;

[0053] Mg: 0.9 mg / L, Mg removal rate 98.5%.

[0054] Note: The calculation method for copper ion loss rate is as follows:

[0055]

[0056] Where C0 is the mass concentration of copper ions in the solution before treatment, V0 is the volume of the solution before treatment, and ρ0 is the density of the solution before treatment; C1 is the mass concentration of copper ions in the solution after treatment, V1 is the volume of the solution after treatment, and ρ1 is the density of the solution after treatment.

[0057] The calculation method for the removal rate of Fe, Ni, Zn, Ca, and Mg impurities is as follows:

[0058]

[0059] Where C0 is the mass concentration of metal impurities in the solution before treatment, V0 is the volume of the solution before treatment, and ρ0 is the density of the solution before treatment; C M V represents the mass concentration of metallic impurities in the treated solution. M ρ is the volume of the solution after treatment. M This represents the density of the solution after treatment.

[0060] Example 2

[0061] The acidic copper-containing etching wastewater used in this embodiment is iron-based copper-containing etching wastewater with the following composition: w(Fe): 3.74%; w(Cu): 8.74%; Ni: 42.2 mg / L; Zn: 65.2 mg / L; Ca: 79.1 mg / L; Mg: 158.8 mg / L; acidity: 4.61 mol / L.

[0062] The steps for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure are as follows:

[0063] S1. Add sodium chlorate (addition amount: 5 kg / m³) to the acidic copper-containing etching wastewater. 3Acidic copper-containing etching wastewater was subjected to an oxidation-reduction reaction for 30 minutes to obtain a pretreated solution.

[0064] S2. Add sodium phosphate to the pretreatment solution (the amount added is twice the metal impurity content in the acidic copper-containing etching wastewater), and adjust the pH to 1.5 with 32wt% sodium hydroxide solution. Stir for 30 minutes, filter, and the purified copper-containing solution is obtained.

[0065] The temperature and pressure throughout steps S1 and S2 are 25°C and 0.1013 MPa.

[0066] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The percentage of copper ions lost was 6.92%, with a copper ion loss rate of 0.36%.

[0067] Fe: 1.6 mg / L, Fe removal rate 99.9%;

[0068] Ni: Not detected, Ni removal rate 100%;

[0069] Zn: 3.4 mg / L, Zn removal rate 94.8%;

[0070] Ca: 0.22 mg / L, Ca removal rate 99.7%;

[0071] Mg: 0.33 mg / L, Mg removal rate 99.8%.

[0072] Example 3

[0073] The acidic copper-containing etching wastewater used in this embodiment is mixed copper sulfate wastewater with the following composition: w(Cu): 8.14%; Fe: 63.3 mg / L; Ni: 23.1 mg / L; Zn: 17.2 mg / L; Ca: 49.1 mg / L; Mg: 58.7 mg / L; acidity: 0.61 mol / L.

[0074] The steps for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure are as follows:

[0075] S1. Add hydrogen peroxide (5 kg / m³) to the acidic copper-containing etching wastewater. 3 Acidic copper-containing etching wastewater was subjected to an oxidation-reduction reaction for 30 minutes to obtain a pretreated solution.

[0076] S2. Add ammonium phosphate (the amount added is twice the metal impurity content in the acidic copper-containing etching wastewater) to the pretreatment solution, and adjust the pH to 1.8 with 20wt% ammonia water. Stir for 30 minutes, filter, and the purified copper sulfate solution is obtained.

[0077] The temperature and pressure throughout steps S1 and S2 are 25°C and 0.1013 MPa.

[0078] Tests showed that w(Cu) in the purified copper sulfate solution... 2+ The copper ion loss rate was 0.48%, with a final concentration of 7.92%.

[0079] Fe: 1.6 mg / L, Fe removal rate 97.5%;

[0080] Ni: Not detected, Ni removal rate 100%;

[0081] Zn: 2.7 mg / L, Zn removal rate 94.3%;

[0082] Ca: 0.62 mg / L, Ca removal rate 98.7%;

[0083] Mg: 0.89 mg / L, Mg removal rate 98.5%.

[0084] Comparative Example 1

[0085] The acidic copper-containing etching wastewater used in this comparative example is the copper etching wastewater from a circuit board factory in Example 1, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0086] The steps for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure are as follows:

[0087] S1. Add sodium chlorate (addition amount: 5 kg / m³) to the acidic copper-containing etching wastewater. 3 Acidic copper-containing etching wastewater was subjected to an oxidation-reduction reaction for 30 minutes to obtain a pretreated solution.

[0088] S2. Add 20wt% ammonia to the pretreatment solution to adjust the pH to 1.5, stir for 30 minutes, filter, and the purified copper-containing solution is obtained.

[0089] The temperature throughout steps S1 and S2 is 25°C.

[0090] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The percentage of copper ions lost was 8.23%, and the copper ion loss rate was 7.18%.

[0091] Fe: 0.8 mg / L, Fe removal rate 96.1%;

[0092] Ni: Not detected, Ni removal rate 100%;

[0093] Zn: 2.92 mg / L, Zn removal rate 93.3%;

[0094] Ca: 0.02 mg / L, Ca removal rate 99.9%;

[0095] Mg: 0.8 mg / L, Mg removal rate 98.9%.

[0096] As can be seen from the comparison between Comparative Example 1 and Example 1, although phosphoric acid was not added to the pretreatment solution, it could effectively remove metal impurities in acidic copper-containing etching wastewater, but it would lead to a significant increase in the copper ion loss rate.

[0097] Comparative Example 2

[0098] The acidic copper-containing etching wastewater used in this comparative example is the copper etching wastewater from a circuit board factory in Example 1, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0099] The method for removing metal impurities from acidic copper-containing etching wastewater at room temperature and pressure differs from Example 1 only in that the amount of phosphoric acid added in step S2 is 1.2 times the metal impurity content in the acidic copper-containing etching wastewater; all other steps are the same.

[0100] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The copper ion loss rate was 0.35%, with a positive rate of 9.91%.

[0101] Fe: 4.2 mg / L, Fe removal rate 65.2%;

[0102] Ni: 3.3 mg / L, Ni removal rate 53.5%;

[0103] Zn: 14.3 mg / L, Zn removal rate 40.2%;

[0104] Ca: 0.02 mg / L, Ca removal rate 99%;

[0105] Mg: 0.8 mg / L, Mg removal rate 98.9%.

[0106] Comparative Example 3

[0107] The acidic copper-containing etching wastewater used in this comparative example is the copper etching wastewater from a circuit board factory in Example 1, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0108] The method for removing metal impurities from acidic copper-containing etching wastewater at room temperature and pressure differs from Example 1 only in that the amount of sodium phosphate added in step S2 is 2.2 times the metal impurity content in the acidic copper-containing etching wastewater; all other steps are the same.

[0109] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The copper ion loss rate was 1.56%, with a final concentration of 9.72%.

[0110] Fe: 0.6 mg / L, Fe removal rate 97.5%;

[0111] Ni: Not detected, Ni removal rate 100%;

[0112] Zn: 2.7 mg / L, Zn removal rate 94.5%;

[0113] Ca: 0.02 mg / L, Ca removal rate 99%;

[0114] Mg: 0.9 mg / L, Mg removal rate 98.5%.

[0115] Comparing Comparative Examples 2, 3, and 1, it can be seen that when the amount of sodium phosphate added in step S2 is less than 1.5 times the content of metal impurities in the acidic copper-containing etching wastewater, although the loss rate of copper ions can be reduced, the removal rate of Fe, Ni, and Zn in the acidic copper-containing etching wastewater is significantly lower; when the amount of sodium phosphate added in step S2 is more than 2 times the content of metal impurities in the acidic copper-containing etching wastewater, the loss rate of copper ions increases significantly.

[0116] Comparative Example 4

[0117] The acidic copper-containing etching wastewater used in this comparative example is the copper etching wastewater from a circuit board factory in Example 1, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0118] The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure differs from Example 1 only in that 20wt% ammonia is used to adjust the pH to 1 in step S2; all other steps are the same.

[0119] Tests showed that w(Cu) in the purified copper chloride solution... 2+ ): 9.95%, copper ion loss rate 0%;

[0120] Fe: 19.68 mg / L, Fe removal rate 0%;

[0121] Ni: 14 mg / L, Ni removal rate 0%;

[0122] Zn: 37.4 mg / L, Zn removal rate 0%;

[0123] Ca: 13.66 mg / L, Ca removal rate 47.3%;

[0124] Mg: 48.56 mg / L, Mg removal rate 10.11%.

[0125] Comparative Example 5

[0126] The acidic copper-containing etching wastewater used in this comparative example is the copper etching wastewater from a circuit board factory in Example 1, with the following composition: w(Cu): 10.87%; Fe: 21.5 mg / L; Ni: 15.3 mg / L; Zn: 40.9 mg / L; Ca: 28.6 mg / L; Mg: 58.8 mg / L; acidity: 2.61 mol / L.

[0127] The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure differs from Example 1 only in that 20wt% ammonia is used to adjust the pH to 2 in step S2; all other steps are the same.

[0128] Tests showed that w(Cu) in the purified copper chloride solution... 2+ The percentage of copper ions lost was 9.43%, with a copper ion loss rate of 4.3%.

[0129] Fe: 0.4 mg / L, Fe removal rate 97.6%;

[0130] Ni: Not detected, Ni removal rate 100%;

[0131] Zn: 2.1 mg / L, Zn removal rate 93.8%;

[0132] Ca: 0.02 mg / L, Ca removal rate 98.7%;

[0133] Mg: 0.7 mg / L, Mg removal rate 98.2%.

[0134] Comparing Comparative Examples 4, 5 and 1, it can be seen that when the pH in step S2 is below 1.3, although the loss of copper ions can be avoided, the metal impurities in the acidic copper-containing etching wastewater cannot be effectively removed; when the pH in step S2 is above 1.7, the loss rate of copper ions increases significantly.

[0135] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure, characterized in that, Includes the following steps: S1. Add an oxidant to the acidic copper-containing etching wastewater to carry out an oxidation-reduction reaction and obtain a pretreatment solution; S2. Add phosphoric acid or soluble phosphate to the pretreatment solution, and adjust the pH to 1.3-1.7 using a pH adjuster. Stir, filter, and the purified copper-containing solution is obtained.

2. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 1, characterized in that, The copper concentration in the acidic copper-containing etching wastewater in step S1 is 8-11 wt%, and the acidity is 2-4 mol / L.

3. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 2, characterized in that, The oxidant mentioned in step S1 is selected from at least one of sodium chlorate, hydrogen peroxide, potassium chlorate, sodium hypochlorite, and potassium hypochlorite.

4. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 3, characterized in that, The amount of oxidant added in step S1 is 4-6 kg / m³. 3 Acidic copper-containing etching wastewater.

5. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 4, characterized in that, The redox reaction in step S1 takes 20-40 minutes; the stirring in step S2 takes 20-40 minutes.

6. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 5, characterized in that, The soluble phosphate in step S2 is selected from at least one of sodium phosphate and ammonium phosphate.

7. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 6, characterized in that, The amount of phosphoric acid or soluble phosphate added in step S2 is 1.5-2 times the metal impurity content in the acidic copper-containing etching wastewater.

8. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 7, characterized in that, The metallic impurities include Fe, Ni, Zn, Ca, and Mg.

9. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 8, characterized in that, The pH adjuster mentioned in step S2 is selected from at least one of ammonia and liquid alkali.

10. The method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure according to claim 9, characterized in that, The temperature during steps S1 and S2 is 20-30℃ and the pressure is 0.1013MPa.

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