A method for removing metallic impurities from acidic copper-containing etching wastewater at room temperature and pressure

Abstract

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. The method includes the following steps: S1, adding an oxidant to the acidic copper-containing etching wastewater to conduct an oxidation-reduction reaction, obtaining a pretreatment solution; S2, adding phosphoric acid or soluble phosphate to the pretreatment solution, adjusting the pH to 1.3-1.7 using a pH adjuster, stirring, and filtering to obtain a purified copper-containing solution. The method provided by this invention achieves high removal rates for Fe, Ni, Zn, Ca, and Mg, while maintaining a high copper ion content. It 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.

Description

TECHNICAL FIELD

[0001] The application 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. BACKGROUND

[0002] Chemical etching is an important process for manufacturing printed circuit boards. In recent years, with the rapid development of the electronic industry, a large amount of etching wastewater is also generated. The commonly used acidic etching wastewater includes copper chloride etching solution and ferric chloride etching solution. If the etching wastewater is directly discharged without treatment, not only the copper resources will be wasted and lost, but also harm will be caused to human beings and the environment.

[0003] At present, the method for removing impurities from acidic etching solution wastewater generally is to add specific ion exchange resins for metal impurity adsorption and to add alkali for precipitation to prepare low-purity products. However, the ion exchange resins have limited selectivity, a large amount of sludge is generated, and due to the solubility product of hydroxide, the problems of incomplete precipitation of metal impurities and enrichment of metal impurities occur.

[0004] A patent with the publication number CN107662988A disclosed in the prior art discloses a treatment method of copper-containing acidic etching wastewater. First, copper oxide is obtained by acid-base neutralization. After the copper oxide is washed and impurities are removed, the copper-containing micro-etching wastewater is added to obtain copper sulfate electrolyte. The copper sulfate electrolyte is subjected to secondary electrolysis, and the wastewater treatment is completed. However, the technical scheme needs to be electrolyzed, and the process is complex. A patent with the publication number CN104556467B discloses a method for treating etching wastewater and a treatment device thereof. The method for treating etching wastewater comprises: mixing acidic etching wastewater and alkaline etching wastewater; adjusting the pH value of the mixed etching wastewater and heating to cause a neutralization reaction; separating the precipitate and the filtrate; and adding a flocculating agent to the filtrate to flocculate the suspended particles and the suspended gel-like arsenic in the filtrate. However, the technical scheme only removes arsenic impurities. SUMMARY

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

[0006] In order to achieve the above-mentioned application purpose, the application provides a method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure, comprising the following steps:

[0007] S1, adding an oxidizing agent to the acidic copper-containing etching wastewater to perform an oxidation-reduction reaction to obtain a pretreated solution;

[0008] S2, adding phosphoric acid or soluble phosphate into the pretreated solution, adjusting pH to 1.3-1.7 by using pH regulator, stirring, filtering, and obtaining the purified copper-containing solution.

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

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

[0011] Optionally, the amount of the oxidizing agent added in step S1 is 4-6kg / m 3 acidic copper-containing etching wastewater.

[0012] Optionally, the time of the oxidation-reduction reaction in step S1 is 20-40min.

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

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

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

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

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

[0018] Optionally, the temperature of the whole process of step S1 and step S2 is 20-30℃, and the pressure is 0.1013MPa.

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

[0020] The method for removing metal impurities from the copper-containing etching wastewater at normal temperature and pressure provided by the application combines the redox treatment by using an oxidizing agent with the impurity removal treatment by using phosphoric acid or soluble phosphate, and by strictly controlling the adding amount of the phosphoric acid or the soluble phosphate and the pH of the solution, the metal impurities Fe, Ni, Zn, Ca and Mg in the copper-containing etching wastewater can be effectively removed while avoiding the loss of copper ions, and through detection, the removal rate of Fe in the 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 loss rate of copper ions is < 0.5%; that is, the method can recover and regenerate high-purity copper salt products and be applied to the fields of food, cosmetics, medical treatment and electroplating, can also reduce the generation of hazardous waste, improve economic benefits and greatly reduce costs. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The flow chart of the method for removing metal impurities from the copper-containing etching wastewater at normal temperature and pressure. DETAILED DESCRIPTION

[0022] In order to make the skilled in the art more clearly understand the technical solutions described in the application, the following examples are used for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the application. The raw materials, reagents or devices used in the following examples and comparative examples are commercially available or can be obtained by known methods unless otherwise specified.

[0023] The application provides a method for removing metal impurities from copper-containing etching wastewater at normal temperature and pressure, comprising the following steps:

[0024] S1, adding an oxidizing agent to the acid copper-containing etching wastewater to perform an oxidation-reduction reaction to obtain a pretreated solution;

[0025] S2, adding phosphoric acid or soluble phosphate to the pretreated solution, adjusting the pH to 1.3-1.7 by using a pH adjuster, stirring and filtering to obtain a purified copper-containing solution.

[0026] The mechanism of the technical solutions of the application for removing metal impurities is as follows: first, an oxidizing agent is added to the acid copper-containing etching wastewater to perform an oxidation-reduction reaction, and the ferrous and cuprous ions in the acid copper-containing etching wastewater are oxidized into ferric ions and copper ions, and the reaction formula is as follows: ; Then, phosphoric acid or soluble phosphate is added, and the pH is controlled to make the metal impurities and phosphate generate phosphate precipitate, and the metal impurities are selectively precipitated while the loss of copper is as low as possible, and 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 a range consisting of any two of them; the inventors have found through exploration that the pH in step S2 needs to be strictly controlled to be 1.3-1.7, when the pH is lower than 1.3, it will lead to a decrease in the removal rate of metal impurities, and when the pH is higher than 1.7, it will lead to an increase in the loss rate of copper.

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

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

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

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

[0032] In some preferred embodiments, the amount of the oxidizing agent added in step S1 is 4-6kg / m 3 acidic copper-containing etching wastewater.

[0033] In some preferred embodiments, the time of the oxidation-reduction reaction in step S1 is 20-40min.

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

[0035] In some preferred embodiments, the amount of the phosphoric acid or the 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 metal impurities include Fe, Ni, Zn, Ca, and Mg.

[0037] The amount of the phosphoric acid or the soluble phosphate added in step S2 can be 1.5 times, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, or a range formed by any two of them, of the content of the metal impurities in the acidic copper-containing etching wastewater. The inventors have found through exploration that the amount of the phosphoric acid or the soluble phosphate added in step S2 needs to be strictly controlled. When the amount of the phosphoric acid or the soluble phosphate is less than 1.5 times of the content of the metal impurities in the acidic copper-containing etching wastewater, the removal rate of the metal impurities will be reduced. When the amount of the phosphoric acid or the soluble phosphate is greater than 2 times of the content of the metal impurities in the acidic copper-containing etching wastewater, the loss rate of copper will be increased.

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

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

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

[0041] In some preferred embodiments, the temperature of the whole process of step S1 and step S2 is 20-30℃, and the pressure is 0.1013 MPa.

[0042] Example 1

[0043] The acidic copper-containing etching wastewater used in this example is the copper etching wastewater of a certain circuit board factory, and the components are as follows: 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 of the method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure are as follows:

[0045] S1, sodium chlorate is added to the acidic copper-containing etching wastewater (the amount added is 5 kg / m 3 The acidic copper-containing etching wastewater) for redox reaction for 30 min to obtain a pretreated liquid;

[0046] S2, phosphoric acid is added to the pretreated liquid (the amount added is 1.5 times of the content of the metal impurities in the acidic copper-containing etching wastewater), and 20 wt% ammonia water is used to adjust the pH to 1.5, and stirring is performed for 30 min, and then filtration is performed to obtain a purified copper-containing solution.

[0047] The temperature of the whole process of step S1 and step S2 is 25℃, and the pressure is 0.1013 MPa.

[0048] The detection result is: w(Cu) in the purified copper chloride solution is 9.89%, and the loss rate of copper ions is 0.5%. 2+ ) : 9.89%, and the loss rate of copper ions is 0.5%;

[0049] Fe: 0.9 mg / L, and the removal rate of Fe is 95.8%;

[0050] Ni: not detected, and the removal rate of Ni is 100%;

[0051] Zn: 2.7 mg / L, and the removal rate of Zn is 93.4%;

[0052] Ca: 0.02 mg / L, and the removal rate of Ca is 99.9%;

[0053] Mg: 0.9 mg / L, and the removal rate of Mg is 98.5%.

[0054] Note: the calculation method of the loss rate of copper ions is as follows:

[0055]

[0056] wherein 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 of the removal rate of Fe, Ni, Zn, Ca and Mg impurities is as follows:

[0058]

[0059] wherein 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; C1 is the mass concentration of metal impurities in the solution after treatment, V1 is the volume of the solution after treatment, and ρ1 is the density of the solution after treatment. M M M

[0060] Example 2

[0061] The acid copper-containing etching wastewater used in this example is iron-based copper-containing etching wastewater, and the components are as follows: 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; and acidity: 4.61 mol / L.

[0062] The steps of the method for removing metal impurities from the acid copper-containing etching wastewater at normal temperature and pressure are as follows:

[0063] S1, adding sodium chlorate (the amount of addition is 5 kg / m 3 ​​​The acid copper-containing etching wastewater is added with hydrogen peroxide (the added amount is 5 kg / m

[0064] S2, sodium phosphate is added into the pretreated solution (the added amount is 2 times of the metal impurity content in the acid copper-containing etching wastewater), and 32 wt% sodium hydroxide solution is used to adjust the pH to 1.5, and stirring is performed for 30 min, and then filtration is performed, so that the purified copper-containing solution is obtained.

[0065] The temperature of the whole process of step S1 and step S2 is 25°C, and the pressure is 0.1013 MPa.

[0066] After detection, the w(Cu 2+ ) in the purified copper chloride solution is 6.92%, and the copper ion loss rate is 0.36%;

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

[0068] Ni: not detected, and the Ni removal rate is 100%;

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

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

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

[0072] Example 3

[0073] The acid copper-containing etching wastewater used in the example is mixed copper sulfate wastewater, and the components are as follows: 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; and acidity: 0.61 mol / L.

[0074] The steps of the method for removing metal impurities from the acid copper-containing etching wastewater at normal temperature and pressure are as follows:

[0075] S1, hydrogen peroxide is added into the acid copper-containing etching wastewater (the added amount is 5 kg / m 3 The acid copper-containing etching wastewater is added with hydrogen peroxide (the added amount is 5 kg / m

[0076] S2, ammonium phosphate is added into the pretreated solution (the added amount is 2 times of the metal impurity content in the acid copper-containing etching wastewater), and 20 wt% ammonia water is used to adjust the pH to 1.8, and stirring is performed for 30 min, and then filtration is performed, so that the purified copper sulfate solution is obtained.

[0077] The temperature of the whole process of step S1 and step S2 is 25°C, and the pressure is 0.1013 MPa.

[0078] w(Cu) in the purified copper sulfate solution: 7.92%, copper ion loss rate: 0.48%; 2+

[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 the present comparative example was the copper etching wastewater from a circuit board factory in Example 1, i.e., the components were as follows: 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 of the method for removing metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure were as follows:

[0087] S1, sodium chlorate was added to the acidic copper-containing etching wastewater (the amount of sodium chlorate added was 5 kg / m 3 The acidic copper-containing etching wastewater) to perform a redox reaction for 30 min to obtain a pretreated solution;

[0088] S2, 20 wt% ammonia water was added to the pretreated solution to adjust the pH to 1.5, and stirred for 30 min, and then filtered to obtain a purified copper-containing solution.

[0089] The temperature of the whole process of steps S1 and S2 was 25°C.

[0090] w(Cu) in the purified copper chloride solution: 8.23%, copper ion loss rate: 7.18%; 2+

[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] From the comparison between Comparative Example 1 and Example 1, it can be seen that no phosphoric acid is added in the pretreatment solution, although the metal impurities in the acidic copper-containing etching wastewater can be effectively removed, the copper ion loss rate is significantly increased.

[0097] Comparative Example 2

[0098] The acidic copper-containing etching wastewater used in the present comparative example is the circuit board etching copper wastewater from a circuit board factory in Example 1, i.e. the components are as follows: 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 steps of the method for removing metal impurities from acidic copper-containing etching wastewater at normal temperature and pressure are different from those in Example 1 only in that the amount of phosphoric acid added in step S2 is 1.2 times the content of metal impurities in the acidic copper-containing etching wastewater; the rest are the same.

[0100] After detection: w(Cu 2+ ) in the purified copper chloride solution: 9.91%, copper ion loss rate: 0.35%;

[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 the present comparative example is the circuit board etching copper wastewater from a circuit board factory in Example 1, i.e. the components are as follows: 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 step of the method for removing metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure is different from that of Example 1 only in that the amount of sodium phosphate added in step S2 is 2.2 times the content of metal impurities in the acidic copper-containing etching wastewater; and the rest is the same.

[0109] The detection shows that the w(Cu) in the purified copper chloride solution is 9.72%, and the loss rate of copper ions is 1.56%. 2+

[0110] Fe: 0.6 mg / L, and the removal rate of Fe is 97.5%;

[0111] Ni: not detected, and the removal rate of Ni is 100%;

[0112] Zn: 2.7 mg / L, and the removal rate of Zn is 94.5%;

[0113] Ca: 0.02 mg / L, and the removal rate of Ca is 99%;

[0114] Mg: 0.9 mg / L, and the removal rate of Mg is 98.5%.

[0115] It can be seen from the comparison of Comparative Example 2, Comparative Example 3 and Example 1 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 rates of Fe, Ni and Zn in the acidic copper-containing etching wastewater are obviously lower; and when the amount of sodium phosphate added in step S2 is greater than 2 times the content of metal impurities in the acidic copper-containing etching wastewater, the loss rate of copper ions is obviously increased.

[0116] Comparative Example 4

[0117] The acidic copper-containing etching wastewater used in the present comparative example is the copper etching wastewater of a certain circuit board factory in Example 1, that is, the components are as follows: 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; and acidity: 2.61 mol / L.

[0118] The step of the method for removing metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure is different from that of Example 1 only in that 20 wt% ammonia water is used to adjust the pH to 1 in step S2; and the rest is the same.

[0119] The detection shows that the w(Cu) in the purified copper chloride solution is 9.95%, and the loss rate of copper ions is 0%. 2+

[0120] Fe: 19.68 mg / L, and the removal rate of Fe is 0%;

[0121] Ni: 14 mg / L, and the removal rate of Ni is 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 the present comparative example is the copper etching wastewater from a circuit board factory in Example 1, i.e. the components are as follows: 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 steps of the method for removing metal impurities from the acidic copper-containing etching wastewater at normal temperature and pressure are different from those in Example 1 only in that 20 wt% ammonia is used to adjust the pH to 2 in step S2; the rest are the same.

[0128] After detection: w(Cu 2+ ): 9.43% in the purified copper chloride solution, and the loss rate of copper ions is 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] From the comparison of Comparative Example 4, Comparative Example 5 and Example 1, it can be seen that when the pH in step S2 is lower than 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 higher than 1.7, the loss rate of copper ions is obviously increased.

[0135] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A method for removing metal impurities from room temperature and atmospheric pressure acidic copper-containing etching wastewater, characterized in that, The method comprises the following steps: S1, adding an oxidizing agent to the acidic copper-containing etching wastewater to perform a redox reaction to oxidize ferrous ions and cuprous ions in the acidic copper-containing etching wastewater into ferric ions and cupric ions, to obtain a pretreated solution; S2, adding phosphoric acid or a soluble phosphate to the pretreated solution, adjusting the pH to 1.3-1.7 by using a pH adjuster, stirring to make metal impurities and phosphate generate phosphate precipitates, and filtering to obtain a purified copper-containing solution; In step S1, the copper concentration in the acidic copper-containing etching wastewater is 8-11 wt%, and the acidity is 2-4 mol / L; In step S2, the adding amount of the phosphoric acid or the soluble phosphate is 1.5-2 times the content of metal impurities in the acidic copper-containing etching wastewater. The metal impurities include Fe, Ni, Zn, Ca, and Mg.

2. The method of claim 1, wherein the metal impurities are removed from the acidic copper-containing etching wastewater at room temperature and atmospheric pressure. In step S1, the oxidizing agent is at least one selected from sodium chlorate, hydrogen peroxide, potassium chlorate, sodium hypochlorite, and potassium hypochlorite.

3. The method of claim 2, wherein the metal impurities are removed from the room temperature and atmospheric pressure acidic copper-containing etching wastewater. In step S1, the adding amount of the oxidizing agent is 4-6 kg per cubic meter of the acidic copper-containing etching wastewater.

4. The method of claim 3, wherein the metal impurities are removed from the acidic copper-containing etching wastewater at room temperature and normal pressure. In step S1, the time of the redox reaction is 20-40 min, and in step S2, the time of the stirring is 20-40 min.

5. The method of claim 4, wherein the metal impurities are removed from the acidic copper-containing etching wastewater at room temperature and atmospheric pressure. In step S2, the soluble phosphate is at least one selected from sodium phosphate and ammonium phosphate.

6. The method of claim 5, wherein the metal impurities are removed from the acidic copper-containing etching wastewater at room temperature and atmospheric pressure. In step S2, the pH adjuster is at least one selected from ammonia water and liquid alkali.

7. The method of claim 6, wherein the metal impurities are removed from the acidic copper-containing etching wastewater at room temperature and normal pressure. In steps S1 and S2, the temperature is 20-30℃, and the pressure is 0.1013 MPa.

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