A method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater

Abstract

The present invention provides a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater, belonging to the technical field of sewage treatment, wherein the cyanide copper plating wastewater is located in the anode chamber of a diaphragm electrolytic cell, and the acidic chromium plating wastewater is located in the cathode chamber of the diaphragm electrolytic cell, and electrolysis is performed with an inert material as an anode and copper as a cathode; the diaphragm of the diaphragm electrolytic cell is a cation exchange membrane. The method provided by the present invention can simultaneously treat cyanide copper plating wastewater and acidic chromium plating wastewater, and can also recover copper in the wastewater, the recovered copper metal purity reaches more than 98%, the hexavalent chromium conversion rate in the wastewater is more than 90%, the copper removal rate is more than 80%, and cyanide is completely converted into nitrogen and carbon dioxide, which is suitable for industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, in particular to a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater. Background Art

[0002] Copper plating is the most widely used pre-plating in the electroplating industry. It is used to improve the bonding strength of the coating before plating nickel, gold and silver on soldered parts, lead-tin alloys and zinc die-castings. Copper plating is an important component of the protective decorative copper / nickel / chromium system. The flexible and low-porosity copper plating plays an important role in improving the bonding strength and corrosion resistance between the coatings. Electroplating chromium is generally applied to the surface of the product position of the mold. After electroplating chromium, the mold and workpiece will have the advantages of smooth and bright surface, easy demoulding and no rust.

[0003] Since the two types of electroplating wastewater have different compositions, the treatment methods for the two types of wastewater are also different. The conventional treatment method for cyanide copper wastewater is oxidation, and the oxidant is usually sodium hypochlorite or bleaching powder. Under alkaline conditions, cyanide is broken and the complex copper ions in the wastewater are converted into insoluble copper hydroxide precipitates; the commonly used treatment method for chromium-containing wastewater is reduction, and the reducing agents include sodium thiosulfate, sodium pyrosulfite, ferrous sulfate, sulfur dioxide, etc. However, the efficiency of treating cyanide copper plating wastewater and acidic chromium plating wastewater separately in the prior art is low. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater. The method provided by the present invention can simultaneously treat cyanide copper plating wastewater and acidic chromium plating wastewater, and the recovery rate of copper obtained by electrolysis is high.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The invention provides a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater. The cyanide copper plating wastewater is located in the anode chamber of a diaphragm electrolytic cell, and the acidic chromium plating wastewater is located in the cathode chamber of the diaphragm electrolytic cell. Electrolysis is performed with an inert material as an anode and copper as a cathode. The diaphragm of the diaphragm electrolytic cell is a cation exchange membrane.

[0007] Preferably, the pH value of the cyanide copper plating wastewater is 9.0-13.0, the copper ion concentration is 0.5-2.0 g / L, and the cyanide ion concentration is 0.5-2.5 g / L.

[0008] Preferably, the pH value of the acidic chromium plating wastewater is 1.0-3.0, the copper ion concentration is 0.2-0.5 g / L, and the hexavalent chromium ion concentration is 0.5-2.0 g / L.

[0009] Preferably, the inert material includes titanium coated with lead dioxide, titanium coated with ruthenium iridium, titanium coated with tantalum iridium or graphite; and the copper is a copper plate or a copper mesh.

[0010] Preferably, the current density of the cathode and anode during the electrolysis process is 50-500 A / m 2 .

[0011] Preferably, the time for electrolysis of cyanide copper plating wastewater in the anode chamber during the electrolysis process is calculated according to Formula I:

[0012] t 1 =C 1 V 1 / k 1 I Formula I

[0013] In the formula I, C 1 Represents the concentration of cyanide ions in wastewater, in g / L; V 1 represents the volume of cyanide copper plating wastewater, in L; k 1 represents the electrolysis constant of cyanide ion, k 1 The value is 0.12~0.24g / Ah; I represents the operating current during electrolysis, the unit is A.

[0014] Preferably, during the electrolysis process, the anode is electrolyzed under the conditions of a first pH value and a second pH value in sequence, the first pH value is 10-13, and the second pH value is 6.5-8.

[0015] Preferably, the electrolysis time of the acidic chromium plating wastewater in the cathode chamber during the electrolysis process is calculated according to Formula II:

[0016] t 2 =C 2 V 2 / k 2 I Formula II

[0017] In Formula II, C 2 Represents the concentration of chromium ions in wastewater, in g / L; V 2 Represents the volume of acidic chromium plating wastewater, in L; k 2 represents the electrolysis constant of chromium ion, k 2 The value is 0.10~0.30g / Ah; I represents the operating current during electrolysis, the unit is A.

[0018] Preferably, the method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater further comprises the following steps:

[0019] 1) mixing the anode solution and the cathode solution after the electrolysis is completed, and adjusting the pH value to obtain a mixed solution;

[0020] 2) mixing the mixed solution obtained in step 1) with a reducing agent to carry out a reduction reaction to obtain a chromium-breaking solution;

[0021] 3) mixing the chromium-breaking solution in step 2) with an alkali for neutralization reaction to obtain a neutralization reaction solution;

[0022] 4) The neutralization reaction liquid in step 3) is mixed with a flocculant to perform flocculation and precipitation, and then solid-liquid separation is performed to obtain liquid and sludge.

[0023] Preferably, in step 1), the pH value is adjusted to 1.2-3.0.

[0024] Beneficial technical effects: The present invention provides a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater, wherein the cyanide copper plating wastewater is located in the anode chamber of a diaphragm electrolytic cell, and the acidic chromium plating wastewater is located in the cathode chamber of a diaphragm electrolytic cell, and electrolysis is performed with an inert material as an anode and copper as a cathode; the diaphragm of the diaphragm electrolytic cell is a cation exchange membrane. The method provided by the present invention can simultaneously treat cyanide copper plating wastewater and acidic chromium plating wastewater, and can also recover copper in the wastewater, and the recovered copper metal purity reaches more than 98%, the hexavalent chromium conversion rate in the wastewater is more than 90%, the copper removal rate is more than 80%, and cyanide is completely converted into nitrogen and carbon dioxide, which is suitable for industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the device for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater in Examples 1 to 3;

[0026] Among them, 1-sodium hydroxide solution storage tank, 2-cyanide copper plating wastewater storage tank, 3-anode, 4-cathode, 5-anode chamber, 6-cathode chamber, 7-acidic chromium plating waste liquid storage tank, 8-sulfuric acid solution storage tank, 9-pH meter, 10-pH meter, 11-DC power supply, 12-cation exchange membrane. DETAILED DESCRIPTION

[0027] The invention provides a method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater. The cyanide copper plating wastewater is located in the anode chamber of a diaphragm electrolytic cell, and the acidic chromium plating wastewater is located in the cathode chamber of the diaphragm electrolytic cell. Electrolysis is performed with an inert material as an anode and copper as a cathode. The diaphragm of the diaphragm electrolytic cell is a cation exchange membrane.

[0028] In the present invention, the cyanide copper plating wastewater preferably includes cyanide copper plating wastewater generated in an electroplating production workshop; the pH value of the cyanide copper plating wastewater is preferably 9.0-13.0, and more preferably 10.5-11.5; the copper ion concentration in the cyanide copper plating wastewater is preferably 0.5-2.0 g / L, and more preferably 1-1.5 g / L; the cyanide ion concentration in the cyanide copper plating wastewater is preferably 0.5-2.5 g / L, and more preferably 1-2 g / L.

[0029] In the present invention, the acidic chromium-plating wastewater preferably includes acidic chromium-plating wastewater generated in an electroplating production workshop; the copper ion concentration in the acidic chromium-plating wastewater is preferably 0.2-0.5 g / L, more preferably 0.3-0.4 g / L; the hexavalent chromium ion concentration in the acidic chromium-plating wastewater is preferably 0.5-1.5 g / L, more preferably 1 g / L.

[0030] In the present invention, the inert material preferably includes titanium coated with lead dioxide, titanium coated with ruthenium iridium, titanium coated with tantalum iridium or graphite, more preferably graphite; the copper is preferably a copper plate or a copper mesh.

[0031] In the present invention, the current density of the cathode and anode during the electrolysis process is preferably 50 to 500 A / m 2 , more preferably 150 to 300 A / m 2 , the most preferred is 200~250A / m 2 .

[0032] In the present invention, the time for electrolysis of cyanide copper plating wastewater in the anode chamber during the electrolysis process is preferably calculated according to Formula I:

[0033] t 1 =C 1 V 1 / k 1 I Formula I

[0034] In the formula I, C 1 Represents the concentration of cyanide ions in wastewater, in g / L; V 1 represents the volume of cyanide copper plating wastewater, in L; k 1 represents the electrolysis constant of cyanide ion, k 1 The value is 0.12~0.24g / Ah; I represents the operating current during electrolysis, the unit is A.

[0035] In the present invention, when the electrolysis time of the copper cyanide plating wastewater reaches the specified time, the copper cyanide plating wastewater after electrolysis is discharged and the copper cyanide plating wastewater that has not been electrolyzed is injected. In a specific embodiment of the present invention, the anode chamber of the diaphragm electrolytic cell is connected to the copper cyanide plating wastewater storage tank, and the copper cyanide plating wastewater in the anode chamber of the diaphragm electrolytic cell and the copper cyanide plating wastewater in the copper cyanide plating wastewater storage tank can circulate during the electrolysis process.1 is the sum of the volumes of the cyanide copper plating wastewater in the anode chamber of the diaphragm electrolyzer and the cyanide copper plating wastewater in the cyanide copper plating wastewater storage tank.

[0036] In the present invention, the anode is preferably electrolyzed under the conditions of a first pH value and a second pH value in sequence during the electrolysis process, the first pH value is preferably 10.0-13.0, more preferably 10.5-11.5, the second pH value is preferably 6.5-8.0, more preferably 7.0-7.5; the first pH value regulator is preferably sodium hydroxide or ammonia water; the second pH value regulator is preferably sulfuric acid or hydrochloric acid. In the present invention, the anode is electrolyzed under two different conditions, the first step is to electrolyze cyanide ions into cyanide oxide ions, and potassium iodide test paper is used to determine whether the reaction is completed; the second step is to electrolyze cyanide oxide ions into carbon dioxide and nitrogen.

[0037] In the present invention, the time for electrolysis of the acidic chromium plating wastewater in the cathode chamber during the electrolysis process is preferably calculated according to Formula II:

[0038] t 2 =C 2 V 2 / k 2 I Formula II

[0039] In Formula II, C 2 Represents the concentration of chromium ions in wastewater, in g / L; V 2 Represents the volume of acidic chromium plating wastewater, in L; k 2 represents the electrolysis constant of chromium ion, k 2 The value is 0.10~0.30g / Ah; I represents the operating current during electrolysis, the unit is A.

[0040] When the circulating electrolysis time of the acidic chromium-plating wastewater reaches the specified time, the electrolyzed acidic chromium-plating wastewater is discharged and un-electrolyzed acidic chromium-plating wastewater is injected. In a specific embodiment of the present invention, the cathode chamber of the diaphragm electrolyzer is connected to the acidic chromium-plating wastewater storage tank, and the acidic chromium-plating wastewater in the cathode chamber of the diaphragm electrolyzer and the acidic chromium-plating wastewater in the acidic chromium-plating wastewater storage tank can circulate during the electrolysis process. 2 It is the sum of the volumes of the acidic chromium-plating wastewater in the cathode chamber of the diaphragm electrolytic cell and the acidic chromium-plating wastewater in the acidic chromium-plating wastewater storage tank.

[0041] In the present invention, the anode reaction during the electrolysis process is:

[0042] CN - +2OH - -2e - =CNO - +H 2 O

[0043] 2CN - +8OH - -10e - =2CO 2 +N 2 +4H 2 O

[0044] 2CNO - +4OH - -6e=2CO 2 +N 2 +2H 2 O

[0045] 4OH - -4e - =2H 2 O+O 2

[0046] Cu + -e - =Cu 2+

[0047] The cathode reaction is:

[0048] Cu + +2e - =Cu

[0049] 2H + +2e - =H 2

[0050] Cr 2 O 7 2- +6e - +14H + =2Cr 3+ +7H 2 O

[0051] CrO 4 2- +3e - +8H + =Cr 3+ +4H 2 O

[0052] The present invention utilizes the property that the cathode and cathode undergo reduction and oxidation reactions respectively in the electrochemical process, and treats acidic chromium plating and cyanide copper plating wastewater in the cathode and cathode regions of the electrolytic cell respectively. During the electrolysis process, chromium, copper ions and cyanide are reduced and oxidized at the cathode and cathode respectively, and metallic copper is obtained at the cathode, so that the copper ions in the wastewater are utilized as resources. The present invention also utilizes the selectivity of the cationic membrane. During the electrolysis process, cyanide ions in the anode liquid are converted into nitrogen and carbon dioxide, and copper migrates to the cathode liquid to form copper element on the cathode plate; during the electrolysis process, chromate and dichromate in the cathode liquid are mostly converted into trivalent chromium at the cathode. After the electrolysis is completed, the difficulty of treating cyanide-containing and chromium-containing wastewater is greatly reduced, and only subsequent sedimentation treatment after deep chromium breaking is required to meet the discharge or reuse standards.

[0053] In the present invention, the method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater further comprises the following steps:

[0054] 1) mixing the anode solution and the cathode solution after the electrolysis is completed, and adjusting the pH value to obtain a mixed solution;

[0055] 2) mixing the mixed solution obtained in step 1) with a reducing agent to carry out a reduction reaction to obtain a chromium-breaking solution;

[0056] 3) mixing the chromium-breaking solution in step 2) with an alkali for neutralization reaction to obtain a neutralization reaction solution;

[0057] 4) The neutralization reaction liquid in step 3) is mixed with a flocculant to perform flocculation and precipitation, and then solid-liquid separation is performed to obtain liquid and sludge.

[0058] The present invention mixes the anode solution and the cathode solution after electrolysis and adjusts the pH value to obtain a mixed solution.

[0059] In the present invention, the pH value of the mixed solution is preferably 1.2 to 3.0, more preferably 1.2 to 1.8; the pH adjuster is preferably sulfuric acid or hydrochloric acid, more preferably sulfuric acid.

[0060] After the mixed solution is obtained, the present invention mixes the mixed solution with a reducing agent to carry out a reduction reaction to obtain a chromium-breaking solution.

[0061] In the present invention, the reducing agent is preferably at least one of sodium thiosulfate, sodium pyrosulfite, ferrous sulfate and sulfur dioxide, more preferably sodium pyrosulfite; the potential of the chromium-breaking solution is preferably 80-320 mv, more preferably 200-250 mv; the amount of the reducing agent is preferably such that the hexavalent chromium content in the obtained chromium-breaking solution is ≤0.01 ppm

[0062] After the chromium-breaking solution is obtained, the present invention mixes the chromium-breaking solution with an alkali for neutralization reaction to obtain a neutralization reaction solution.

[0063] In the present invention, the pH value of the neutralization reaction solution is preferably 7 to 9, more preferably 7.5 to 8.5; the alkali is preferably sodium hydroxide or lime water, more preferably sodium hydroxide.

[0064] After the neutralization reaction liquid is obtained, the present invention mixes the neutralization reaction liquid with a flocculant to carry out flocculation precipitation and then separates the solid and the liquid to obtain the liquid and the sludge.

[0065] In the present invention, the flocculant is preferably a polyacrylamide solution; the dosage of the flocculant is preferably 1 ml / L; the solid-liquid separation is preferably to stand the reaction solution after flocculation and precipitation to obtain a supernatant and a bottom mud, and to filter the bottom mud to obtain a filtrate and sludge. The supernatant and the filtrate are combined and enter the SCR process of electroplating wastewater.

[0066] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0067] Example 1

[0068] The composition of cyanide copper plating wastewater and acid chromium plating wastewater is as follows:

[0069] Table 1: Composition of cyanide copper plating wastewater and acidic chromium plating wastewater in Example 1

[0070] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 9.68 0.94 1.13 / Acidic chrome plating wastewater 2.35 0.25 / 1.52

[0071] like Figure 1 The cathode and cathode areas (including the anode chamber and the cyanide copper plating wastewater storage tank) of the electrolytic cell shown in the figure are injected with 4L of cyanide copper plating wastewater, and the cathode area (including the cathode chamber and the acid chromium plating wastewater storage tank) is injected with 4L of acid chromium plating wastewater. The effective volumes of the anode chamber and the cathode chamber are 4L respectively. The anode material is titanium coated with ruthenium iridium, the electrode material is 50 mesh copper mesh, and the effective areas of the cathode and cathode are 300cm respectively. 2 ; During electrolysis, the current density of the cathode and anode is controlled to be 250A / m 2 The pH value of the anode liquid was 11.0-11.5. After 4 hours of power-on, the pH value of the anode liquid was adjusted to between 7.0-7.5, and the power was continued for 5 hours. During the power-on process, the pH value of the cathode liquid was always controlled between 1.7-1.9.

[0072] According to formula I, the theoretical time for complete electrolysis of anolyte cyanide ions is:

[0073] t 1 =1.13g / L*4L / (250A / m 2 *0.03m 2 *0.12g / Ah)=5.02h

[0074] t 1=1.13g / L*4L / (250A / m 2 *0.03m 2 *0.24g / Ah)=2.51h

[0075] Theoretically, under the condition of 100% current efficiency, the time required for the cyanide ions in the anode liquid to be completely electrolyzed into nitrogen and carbon dioxide is 2.51 to 5.02 hours.

[0076] According to formula II, the theoretical electrolysis time of hexavalent chromium in the cathode liquid is:

[0077] t 2 =1.52g / L*4L / (250A / m 2 *0.03m 2 *0.10g / Ah)=8.1h

[0078] t 2 =1.52g / L*4L / (250A / m 2 *0.03m 2 *0.30g / Ah)=2.7h

[0079] Theoretically, under the condition of 100% current efficiency, it takes 2.7 to 8.1 hours for the hexavalent chromium ions in the cathode liquid to be completely electrolyzed into trivalent chromium ions.

[0080] In this embodiment, electrolysis is first performed for 4 hours, which is determined by measuring that cyanide ions in the anode liquid are completely converted into cyanide ions. The power is then supplied for 5 hours to ensure that cyanide ions are completely converted into carbon dioxide and nitrogen. The total electrolysis time is 9 hours, which also maximizes the conversion of hexavalent chromium in the cathode liquid into trivalent chromium.

[0081] The composition of cyanide copper plating wastewater and acid chromium plating wastewater after electrolysis is shown in Table 2.

[0082] Table 2 Composition of cyanide copper plating wastewater and acidic chromium plating wastewater after electrolysis of Example 1

[0083] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 7.24 0.17 / / Acidic chrome plating wastewater 1.82 0.05 / 0.42

[0084] After the electrolysis, the removal rate of cyanide in the anolyte was 100%, the recovery rate of copper in the anolyte was 82.0%, and the purity of the metallic copper precipitated on the cathode plate was 99.0%.

[0085] After the mixed electrolysis, the anode and cathode solutions are controlled at pH 1.8-2.2, sodium metabisulfite solution is added to deeply break the chromium, the potential is controlled at 200-250mv, sodium hydroxide solution is added to neutralize and flocculate, the sludge is filtered, and the supernatant and the water produced by the filter press enter the wastewater SCR process for further treatment.

[0086] Example 2

[0087] The composition of cyanide copper plating wastewater and acid chromium plating wastewater is as follows:

[0088] Table 3: Composition of cyanide copper plating wastewater and acidic chromium plating wastewater in Example 2

[0089] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 10.1 0.85 1.23 / Acidic chrome plating wastewater 2.03 0.22 / 1.94

[0090] like Figure 1 The cathode and cathode areas (including the anode chamber and the cyanide copper plating wastewater storage tank) of the electrolytic cell shown in the figure are injected with 4L of cyanide copper plating wastewater, and the cathode area (including the cathode chamber and the acid chromium plating wastewater storage tank) is injected with 4L of acid chromium plating wastewater. The effective volumes of the anode chamber and the cathode chamber are 4L respectively. The anode material is titanium coated with ruthenium iridium, the electrode material is 50 mesh copper mesh, and the effective areas of the cathode and cathode are 300cm respectively. 2 ; During electrolysis, the current density of the cathode and anode is controlled to be 250A / m 2 The pH value of the anode liquid was 11.0-11.5. After 5.5 hours of power-on, the pH value of the anode liquid was adjusted to between 7.0-7.5, and the power was continued for 6 hours. During the power-on process, the pH value of the cathode liquid was always controlled between 1.7-1.9.

[0091] The composition of cyanide copper plating wastewater and acid chromium plating wastewater after electrolysis is shown in Table 2.

[0092] Table 4 Composition of cyanide copper plating wastewater and acidic chromium plating wastewater after electrolysis of Example 2

[0093] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 7.13 0.15 / / Acidic chrome plating wastewater 1.78 0.04 / 0.39

[0094] After the electrolysis, the removal rate of cyanide in the anolyte was 100%, the recovery rate of copper in the anolyte was 82.3%, and the purity of the metallic copper precipitated on the cathode plate was 99.0%.

[0095] After the mixed electrolysis, the anode and cathode solutions are controlled at pH 1.8-2.2, sodium metabisulfite solution is added to deeply break the chromium, the potential is controlled at 200-250mv, sodium hydroxide solution is added to neutralize and flocculate, the sludge is filtered, and the supernatant and the water produced by the filter press enter the wastewater SCR process for further treatment.

[0096] Example 3

[0097] The composition of cyanide copper plating wastewater and acid chromium plating wastewater is as follows:

[0098] Table 5: Composition of cyanide copper plating wastewater and acidic chromium plating wastewater in Example 3

[0099] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 9.46 1.24 1.86 / Acidic chrome plating wastewater 2.68 0.31 / 1.51

[0100] like Figure 1The cathode and cathode areas (including the anode chamber and the cyanide copper plating wastewater storage tank) of the electrolytic cell shown in the figure are injected with 4L of cyanide copper plating wastewater, and the cathode area (including the cathode chamber and the acid chromium plating wastewater storage tank) is injected with 4L of acid chromium plating wastewater. The effective volumes of the anode chamber and the cathode chamber are 4L respectively. The anode material is titanium coated with ruthenium iridium, the electrode material is 50 mesh copper mesh, and the effective areas of the cathode and cathode are 300cm respectively. 2 ; During electrolysis, the current density of the cathode and anode is controlled to be 250A / m 2 The pH value of the anode liquid was 11.0-11.5. After 8.5 hours of power-on, the pH value of the anode liquid was adjusted to between 7.0-7.5, and the power was continued for 9 hours. During the power-on process, the pH value of the cathode liquid was always controlled between 1.7-1.9.

[0101] The composition of cyanide copper plating wastewater and acid chromium plating wastewater after electrolysis is shown in Table 2.

[0102] Table 6 Composition of cyanide copper plating wastewater and acidic chromium plating wastewater after electrolysis of Example 3

[0103] pH Cu, g / L CN, g / L <![CDATA[Cr 6+ ,g / L]]> Cyanide copper plating wastewater 7.27 0.21 / / Acidic chrome plating wastewater 1.78 0.05 / 0.10

[0104] After the electrolysis, the removal rate of cyanide in the anolyte was 100%, the recovery rate of copper in the anolyte was 83.4%, and the purity of the metallic copper precipitated on the cathode plate was 99.0%.

[0105] After the mixed electrolysis, the anode and cathode solutions are controlled at pH 1.8-2.2, sodium metabisulfite solution is added to deeply break the chromium, the potential is controlled at 200-250mv, sodium hydroxide solution is added to neutralize and flocculate, the sludge is filtered, and the supernatant and the water produced by the filter press enter the wastewater SCR process for further treatment.

[0106] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for jointly treating cyanide copper plating wastewater and acidic chromium plating wastewater, characterized in that: The cyanide copper plating wastewater is located in the anode chamber of the diaphragm electrolytic cell, and the acidic chromium plating wastewater is located in the cathode chamber of the diaphragm electrolytic cell. The inert material is used as the anode and copper is used as the cathode for electrolysis. The diaphragm of the diaphragm electrolytic cell is a cation exchange membrane. The following steps are also included: 1) mixing the anode solution and cathode solution after the electrolysis is completed and adjusting the pH value to obtain a mixed solution; 2) mixing the mixed solution obtained in step 1) with a reducing agent to carry out a reduction reaction to obtain a chromium-breaking solution; 3) mixing the chromium-breaking solution in step 2) with an alkali for neutralization reaction to obtain a neutralization reaction solution; 4) mixing the neutralization reaction liquid in step 3) with a flocculant to perform flocculation precipitation and then separate the solid and liquid to obtain liquid and sludge; In the step 1), the pH value is adjusted to 1.2-3.0; The reducing agent in step 1) is at least one of sodium thiosulfate, sodium pyrosulfite, ferrous sulfate and sulfur dioxide.

2. The method according to claim 1, characterized in that: The pH value of the cyanide copper plating wastewater is 9.0-13.0, the copper ion concentration is 0.5-2.0 g / L, and the cyanide ion concentration is 0.5-2.5 g / L.

3. The method according to claim 1, characterized in that The pH value of the acidic chromium plating wastewater is 1.0-3.0, the copper ion concentration is 0.2-0.5 g / L, and the hexavalent chromium ion concentration is 0.5-2.0 g / L.

4. The method according to claim 1, characterized in that: The inert material includes titanium coated with lead dioxide, titanium coated with ruthenium iridium, titanium coated with tantalum iridium or graphite; the copper is a copper plate or a copper mesh.

5. The method according to claim 1, characterized in that The current density of the cathode and anode during the electrolysis process is 50-500A / m 2 .

6. The method according to claim 1, characterized in that The time for electrolysis of cyanide copper plating wastewater in the anode chamber during the electrolysis process is calculated according to Formula I: t1=C1V1 / k1I formula I In the formula I, C1 represents the concentration of cyanide ions in the wastewater, in g / L; V1 represents the volume of cyanide copper plating wastewater, in L; k1 represents the electrolysis constant of cyanide ions, and the value of k1 is 0.12-0.24 g / Ah; I represents the operating current during electrolysis, in A.

7. The method according to claim 1, characterized in that During the electrolysis process, the anode is electrolyzed under the conditions of a first pH value and a second pH value in sequence, wherein the first pH value is 10-13 and the second pH value is 6.5-8.

8. The method according to claim 1, characterized in that The time for electrolysis of acidic chromium plating wastewater in the cathode chamber during the electrolysis process is calculated according to Formula II: t2=C2V2 / k2I formula II In the formula II, C2 represents the concentration of chromium ions in the wastewater, in g / L; V2 represents the volume of the acidic chromium plating wastewater, in L; k2 represents the electrolysis constant of chromium ions, and the value of k2 is 0.10-0.30 g / Ah; I represents the operating current during electrolysis, in A.

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