CN108529789B - Method for treating copper-containing electroplating wastewater and recovering copper by using sulfide precipitation method - Google Patents
Method for treating copper-containing electroplating wastewater and recovering copper by using sulfide precipitation method Download PDFInfo
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Abstract
The invention belongs to the technical field of environmental engineering, and particularly relates to a method for treating copper-containing electroplating wastewater and recovering copper by using a sulfide precipitation method. Firstly, adjusting the pH value of copper-containing electroplating wastewater to 1.5-3.0, then adding a sulfide solution, stirring for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain pretreated wastewater and copper sulfide precipitate; adding part of solid sulfide into the pretreated wastewater, and carrying out primary stirring reaction; then adding the residual solid sulfide, and carrying out secondary stirring reaction; adding a flocculating agent after the secondary stirring reaction is finished, and stirring for reaction; and after the reaction is finished, adjusting the pH value of the system to 7.0-8.0, and performing solid-liquid separation to obtain the supernatant and the mixed heavy metal sulfide which reach the discharge standard. The method utilizes the sulfide to efficiently separate and recover copper from the copper-containing electroplating wastewater, realizes the harmlessness of the electroplating wastewater, and has the advantages of simple operation, stable operation, low cost, high resource degree and no secondary pollution.
Description
Technical Field
The invention belongs to the technical field of environmental engineering, and particularly relates to a method for treating copper-containing electroplating wastewater and recovering copper by using a sulfide precipitation method.
Background
In the electroplating process, the copper plating layer is usually used as a bottom layer for nickel plating, tin plating, chromium plating, silver plating and gold plating, and the bonding force between matrix metal and a surface plating layer and the corrosion resistance of the plating layer are improved, so that the copper-containing electroplating wastewater is very common in the electroplating industry, and the industrial wastewater usually contains a plurality of heavy metals. The waste water is discharged without proper treatment, which not only causes environmental pollution, but also causes resource waste, and is not beneficial to green sustainable development of the industry.
At present, the treatment of copper-containing electroplating wastewater mainly adopts a neutralization precipitation method, an ion exchange method, an electrolysis method, a membrane separation method, an adsorption method, a biological method and the like. The ion exchange method can effectively remove metal ions in the wastewater, and simultaneously, the water can be recycled, but the method has large resin consumption, difficult treatment of regenerated liquid and high treatment cost; and during the regeneration process, the resin may shrink or expand to cause cracking, and the economy is not high. The treatment process of the electrolytic method is mature and stable in operation, but because the content of controlled substances specified by the discharge standard is extremely low, the treatment method has the disadvantages of high power consumption and high treatment cost during the electrolysis of wastewater, is easy to generate toxic gas, and is difficult to treat until the wastewater reaches the standard and is discharged. The membrane separation method has the advantages of phase change free, high energy conversion efficiency, no consumption of chemical reagents and the like, but has low treatment economy due to high equipment cost. The adsorption method for treating the electroplating heavy metal wastewater is simple to operate and low in investment, but the main problem is that the effluent treated by the pure adsorption method is difficult to reach the standard and can only be used as a pretreatment means. The biological method for treating the electroplating wastewater has strong adaptability, simple equipment, no secondary pollution and low treatment cost, but has the main problems of low propagation speed of functional bacteria, low reaction efficiency and difficult achievement of treated effluent to the recycling standard.
The current common treatment method is hydroxide neutralization and precipitation, namely lime or alkali is used for adjusting the pH value of the wastewater, and metal ion trapping agents and the like are added for neutralization, coagulation, flocculation and precipitation, but the method has the defects of large dosage of the chemical agent, large sludge amount, serious secondary pollution, poor treatment effect and the like, and can not effectively separate and recycle heavy metals in the wastewater. Compared with a hydroxide precipitation method, the heavy metal sulfide produced by the sulfide precipitation method has smaller solubility product and is easier to generate precipitate, and meanwhile, the pH value of effluent is 7-9, so that the effluent can be discharged without being neutralized again. However, sulfide precipitate particles are fine and are easy to form colloid, a flocculating agent needs to be added for auxiliary precipitation, and the treatment cost is high. Meanwhile, the sulfide precipitator is remained in water, and generates hydrogen sulfide gas when meeting acid, so that secondary pollution is generated, and the method is not wide in practical application.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention aims to provide a method for treating copper-containing electroplating wastewater and recovering copper by using a sulfide precipitation method, the method utilizes sulfide to efficiently separate and recover copper from the copper-containing electroplating wastewater and realizes harmlessness of the copper-containing electroplating wastewater, the method is simple to operate, stable to operate, low in cost, high in resource degree and free of secondary pollution, high-purity separation and recovery of copper in the wastewater and recovery of other metal ions with higher purity are realized, zero discharge or low discharge of the copper-containing electroplating wastewater in electroplating production is realized, the production cost can be effectively reduced, the resource recycling is realized, and energy conservation, emission reduction and clean production of the electroplating industry are promoted and promoted.
The purpose of the invention is realized by the following technical scheme:
a method for treating copper-containing electroplating wastewater and recovering copper by using a sulfide precipitation method comprises the following steps:
(1) adjusting the pH value of the copper-containing electroplating wastewater to 1.5-3.0, then adding a sulfide solution with the initial concentration of 0.5-1.5 mol/L, stirring for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain pretreated wastewater and copper sulfide precipitate;
(2) adding part of solid sulfide into the pretreated wastewater prepared in the step (1) for primary stirring reaction; then adding the residual solid sulfide, and carrying out secondary stirring reaction; adding a flocculating agent after the secondary stirring reaction is finished, and stirring for reaction; after the reaction is finished, adjusting the pH value of the system to 7.0-8.0, and carrying out solid-liquid separation to obtain a supernatant and a mixed heavy metal sulfide, wherein the supernatant is discharged after reaching the standard;
the sulfide in the step (1) is preferably at least one of sodium sulfide, potassium sulfide and high-concentration sulfate biological reduction wastewater;
the amount of the sulfide solution used in step (1) is preferably: the adding amount of the sulfide is 80-95% of the amount of copper element substances in the copper-containing electroplating wastewater;
the reaction condition in the step (1) is preferably that the stirring reaction is carried out for 10-30 min under the condition that the pH value is 1.5-3.5;
the specific operation of the solid-liquid separation in the step (1) is preferably:
after the reaction is finished, naturally precipitating to obtain supernatant 1 and copper sulfide slurry, and centrifuging the copper sulfide slurry to obtain supernatant 2 and copper sulfide; mixing the supernatant 1 and the supernatant 2 to obtain pretreated wastewater;
the time for natural precipitation is preferably 3-8 h;
the purity of the copper sulfide is preferably not less than 50%;
the total usage amount of the partial solid sulfides and the residual solid sulfides in the step (2) is preferably 110-130% of the total amount of the residual heavy metal substances in the wastewater;
the dosage of the partial solid sulfide in the step (2) is preferably 60-80% of the total dosage of the partial solid sulfide and the residual solid sulfide;
the time for the first stirring reaction in the step (2) is preferably 10-30 min;
the time of the secondary stirring reaction in the step (2) is preferably 2-4 min;
the flocculating agent in the step (2) is preferably a mixture of polyacrylamide and ferrous sulfate;
the mass ratio of the polyacrylamide to the ferrous sulfate is preferably (2-4) to 1;
the addition amount of the flocculant in the step (2) is preferably per m310-60 g of wastewater;
the stirring reaction time in the step (2) is preferably 10-30 min;
the pH is preferably adjusted by sodium hydroxide in the step (2);
the specific operation of the solid-liquid separation in the step (2) is preferably:
adjusting the pH value of the system to 7.0-8.0, naturally precipitating to obtain supernatant 3 and mixed heavy metal sulfide slurry, and centrifuging the mixed heavy metal sulfide slurry to obtain supernatant 4 and mixed heavy metal sulfide (high purity); mixing the supernatant 3 and the supernatant 4 to obtain a supernatant which can reach the standard;
the time for natural precipitation is preferably 1-4 h;
the method for treating the copper-containing electroplating wastewater and recovering copper by using the sulfide precipitation method preferably comprises the following steps of:
(1) collecting waste water in a reservoir
The water storage tank collects copper-containing electroplating wastewater discharged from an electroplating workshop, and the pH value of the copper-containing electroplating wastewater is adjusted to 1.5-3.0;
(2) copper sulfide precipitate
Enabling copper-containing electroplating wastewater in a water storage tank to enter a sulfide reaction tank I, adding a sulfide solution with the initial concentration of 0.5-1.5 mol/L into the reaction tank, wherein the adding amount of sulfide is 80-95% of the amount of copper element substances in the copper-containing electroplating wastewater, then controlling the pH value of a system to be 1.5-3.5, and stirring and reacting for 10-30 min; discharging the wastewater into a sedimentation tank after the reaction is finished, naturally settling for 3-8 hours to obtain supernatant fluid 1 and copper sulfide slurry, and centrifugally dewatering the copper sulfide slurry to obtain supernatant fluid 2 and copper sulfide (high purity); mixing the supernatant 1 and the supernatant 2 to obtain pretreated wastewater;
(3) precipitation of other heavy metals by sulfides
Enabling the pretreated wastewater prepared in the step (2) to enter a sulfide reaction tank II, adding part of solid sulfides into the reaction tank, carrying out primary stirring reaction for 10-30 min, then adding the rest of solid sulfides, and carrying out secondary stirring reaction for 2-4 min, wherein the total addition amount of the sulfides is 110-130% of the total amount of the rest of heavy metal substances in the pretreated wastewater, and the use amount of the part of solid sulfides is 60-80% of the total addition amount of the sulfides; adding a flocculating agent after the secondary stirring reaction is finished, and stirring for reaction for 10-30 min; after the reaction is finished, adding sodium hydroxide to adjust the pH value to 7.0-8.0, discharging the wastewater into a sedimentation tank, naturally settling for 1-4 hours to obtain supernatant 3 and mixed heavy metal sulfide slurry, and centrifugally dewatering the mixed heavy metal sulfide slurry to obtain supernatant 4 and mixed heavy metal sulfide (high purity); (ii) a Mixing the supernatant 3 and the supernatant 4 to obtain a supernatant which can reach the standard;
the flocculating agent in the step (3) is preferably a mixture of polyacrylamide and ferrous sulfate according to a mass ratio of (2-4): 1, and the addition amount of the flocculating agent is preferably per m310-60 g of wastewater;
the principle of the invention is as follows:
adding a sulfide solution with the initial concentration of 0.5-1.5 mol/L into the acidic copper-containing electroplating wastewater, ensuring that the addition amount of sulfides is 80-95% of the amount of copper element substances in the copper-containing electroplating wastewater, ensuring the uniformity of the sulfide concentration in the wastewater after stirring easily by adding the sulfide solution, and controlling the initial concentration and the use amount of the sulfide to ensure that under the condition of pH 1.5-3.5, the sulfide and copper ions in the copper-containing electroplating wastewater form copper sulfide precipitates, but do not form precipitates with other heavy metal ions, and the sulfide with insufficient amount can avoid sulfide residues and gaseous hydrogen sulfide loss, and because the copper sulfide precipitate particles are large, the high-purity copper sulfide precipitate can be recovered and the pretreated copper-containing electroplating wastewater can be obtained after simple solid-liquid separation;
after copper ions are removed, excessive solid sulfide is added into the pretreated copper-containing electroplating wastewater twice, so that heavy metal sulfide precipitate can be formed by the sulfide and other residual heavy metal ions in the wastewater, meanwhile, the sulfide neutralizes the wastewater to be nearly neutral, a flocculating agent is continuously added to flocculate and precipitate the heavy metal sulfide, the heavy metal sulfide reacts with the residual sulfide to form precipitate, finally, alkali liquor is added to precipitate to remove the excessive metal in the flocculating agent, the wastewater is neutralized to be neutral, the heavy metal sulfide precipitate with higher purity is obtained through solid-liquid separation, and the wastewater can be discharged according to the standard. Solid sulfide is selected in the link, so that the preparation of sulfide solution is omitted, and the operation flow is simplified; the solid sulfide is added in two times, insufficient solid sulfide is added for the first time, loss of gaseous hydrogen sulfide is avoided, excessive sulfide is added for the second time, total precipitation of residual heavy metals is guaranteed, and loss of excessive gaseous hydrogen sulfide is avoided to a great extent due to short reaction time.
Compared with the prior art, the invention has the following advantages and effects:
(1) the invention provides a low-cost treatment method of copper-containing electroplating wastewater. The method has the advantages of simple treatment process, normal temperature and pressure, low energy consumption and large-scale engineering application potential. Various metal pollutants in the wastewater subjected to sulfide precipitation treatment meet the discharge standard of electroplating pollutants (GB21900-2008), and the wastewater reaches the standard and is safely discharged.
(2) The method for treating the copper-containing electroplating wastewater and recovering the copper by using the sulfide precipitation method has the characteristic of high-efficiency heavy metal recycling. Compared with the traditional hydroxide precipitation method, the sulfide precipitation method has the advantages of small sludge amount, low water content and easy dehydration, and copper in the copper-containing electroplating wastewater is precipitated in a high-purity copper sulfide form independently and can be separated and recovered efficiently; other heavy metals are mixed and precipitated in the form of metal sulfides, so that the grade of the heavy metals is high, and the resource utilization performance is high.
(3) The method for treating the copper-containing electroplating wastewater and recovering the copper by using the sulfide precipitation method provided by the invention overcomes the problems of small sulfide particles, difficult precipitation, easy sulfide residue and secondary pollution. The copper sulfide particles have large particle size and can be naturally settled; other metal sulfide particles are small, and the process is assisted in sedimentation by adding a flocculating agent. When copper is precipitated, the method adds the sulfide with insufficient amount, so as to avoid the residue and the loss of the sulfide; when the residual metal is precipitated, the sulfide is added in two times, and the residual sulfide in the wastewater is precipitated by adding flocculants such as ferrous sulfate and the like, so that the secondary pollution caused by volatilization of the residual sulfide is avoided.
(4) The method for treating the copper-containing electroplating wastewater and recovering the copper by using the sulfide precipitation method provided by the invention has multiple purposes, realizes the high-efficiency separation and recovery of the copper and other heavy metals in the copper-containing electroplating wastewater and the harmless treatment of the wastewater, accords with the green development concept of energy conservation and emission reduction, and has the characteristic of sustainable development.
Drawings
FIG. 1 is a schematic view showing a process flow of treating copper-containing electroplating wastewater in example 1.
Detailed Description
The present invention will be described in further detail with reference to examples and drawings, but the present invention is not limited thereto.
Example 1
The electroplating wastewater is taken from a certain electroplating plant in Shandong and is mainly used for producing copper-zinc-nickel plated parts. The specific treatment steps are as follows:
(1) collecting waste water in a reservoir
The water storage pool collects copper-containing electroplating wastewater discharged from an electroplating workshop, and the initial pH of the wastewater is 1.5; through determination, the main metal content of the waste water is as follows: cu 121mg/L, Zn 64mg/L, Ni 76mg/L, Fe 73mg/L, and the content of other heavy metals is lower than 5 mg/L.
(2) Copper sulfide precipitate
The electroplating wastewater in the water storage tank enters a sulfide reaction tank I, and a sodium sulfide solution with the initial concentration of 0.5mol/L is added into the reaction tank, wherein the adding amount of the sodium sulfide is 95 percent of the amount of copper substances in the wastewater; then controlling the pH value of the system to be lower than 2.0 and stirring for reaction for 10 min; discharging the wastewater into a sedimentation tank after the reaction is finished, naturally settling for 3 hours to obtain supernatant fluid 1 and copper sulfide slurry, and centrifugally dewatering the copper sulfide slurry to obtain supernatant fluid 2 and high-purity copper sulfide; mixing the supernatant 1 and the supernatant 2 to obtain pretreated wastewater;
(3) precipitation of other heavy metals by sulfides
Enabling the pretreated wastewater prepared in the step (2) to enter a sulfide reaction tank II, adding part of solid sodium sulfide into the reaction tank, carrying out primary stirring reaction for 30min, then adding the rest solid sulfide, and carrying out secondary stirring reaction for 3min, wherein the total addition amount of the sulfide is 110% of the total amount of the rest heavy metal substances in the pretreated wastewater, and the use amount of the first part of solid sulfide is 60% of the total addition amount of the sulfide; after the secondary stirring reaction is finished, adding a flocculating agent (obtained by mixing polyacrylamide and ferrous sulfate according to the mass ratio of 2: 1), and stirring for reacting for 10min, wherein 10g of flocculating agent is added into each ton of wastewater; after the reaction is finished, adding sodium hydroxide to adjust the pH value to 7.0, discharging the wastewater into a sedimentation tank, naturally settling for 1h to obtain supernatant 3 and mixed heavy metal sulfide slurry, and centrifugally dewatering the mixed heavy metal sulfide slurry to obtain supernatant 4 and high-purity mixed heavy metal sulfide; mixing the supernatant 3 and the supernatant 4 to obtain supernatant which can reach the standard (see the specific flow chart in figure 1);
through detection, the heavy metal content of the treated copper-containing electroplating wastewater (the supernatant which is prepared in the step (3) and can reach the standard discharge) is as follows: cu is 0.2mg/L, Zn 0.8.8 mg/L, Ni 0.4.4 mg/L, Fe 2.1.1 mg/L, and the content of other heavy metals is lower than 0.03mg/L, which meet the discharge Standard of electroplating pollutants (GB21900-2008), and can reach the standard discharge. The purity of the copper sulfide recovered by separation is 59% (purity ═ heavy metal element content in the recovered metal sulfide precipitate/recovered metal sulfide precipitate amount), and the copper recovery rate is 92% (heavy metal recovery rate ═ heavy metal element content in the recovered metal sulfide precipitate/heavy metal element content in the wastewater), and the recovered copper sulfide has high resource potential. The purity of zinc and nickel in the recycled mixed metal sulfide is 5.6 percent and 7.1 percent respectively, and the method has higher resource potential.
Example 2
The electroplating wastewater is taken from a certain electroplating plant in Jiangsu province and mainly used for producing copper-plated parts. The specific treatment steps are as follows:
(1) collecting waste water in a reservoir
The water storage pool collects copper-containing electroplating wastewater discharged from an electroplating workshop, the initial pH of the wastewater is 3.4, and the pH is adjusted to 3.0. Through determination, the main metal content of the waste water is as follows: cu 130mg/L, Zn 34mg/L, Ni 9mg/L, Fe 57mg/L, and the content of other heavy metals is lower than 5 mg/L.
(2) Copper sulfide precipitate
The electroplating wastewater in the water storage tank enters a sulfide reaction tank I, and a sodium sulfide solution with the initial concentration of 1.5mol/L is added into the reaction tank, wherein the adding amount of the sodium sulfide is 90 percent of the amount of copper substances in the wastewater; then controlling the pH value of the system to be lower than 3.5, and stirring and reacting for 30 min; discharging the wastewater into a sedimentation tank after the reaction is finished, naturally settling for 4 hours to obtain supernatant fluid 1 and copper sulfide slurry, and centrifugally dewatering the copper sulfide slurry to obtain supernatant fluid 2 and high-purity copper sulfide; mixing the supernatant 1 and the supernatant 2 to obtain pretreated wastewater;
(3) precipitation of other heavy metals by sulfides
Enabling the pretreated wastewater prepared in the step (2) to enter a sulfide reaction tank II, adding part of solid sodium sulfide into the reaction tank, carrying out primary stirring reaction for 20min, then adding the rest solid sulfide, and carrying out secondary stirring reaction for 4min, wherein the total addition amount of the sulfide is 130% of the total amount of the rest heavy metal substances in the pretreated wastewater, and the use amount of the first part of solid sulfide is 80% of the total addition amount of the sulfide; after the secondary stirring reaction is finished, adding a flocculating agent (obtained by mixing polyacrylamide and ferrous sulfate according to the mass ratio of 4: 1), and stirring for reacting for 30min, wherein 60g of flocculating agent is added into each ton of wastewater; after the reaction is finished, adding sodium hydroxide to adjust the pH value to 8.0, discharging the wastewater into a sedimentation tank, and naturally settling for 4 hours to obtain supernatant liquid 4 and high-purity mixed heavy metal sulfide; mixing the supernatant 3 and the supernatant 4 to obtain a supernatant which can reach the standard;
through detection, the heavy metal content of the treated copper-containing electroplating wastewater (the supernatant which is prepared in the step (3) and can reach the standard discharge) is as follows: cu is 0.1mg/L, Zn 0.3.3 mg/L, Ni 0.3.3 mg/L, Fe 1.7.7 mg/L, and the content of other heavy metals is lower than 0.03mg/L, which meet the discharge Standard of electroplating pollutants (GB21900-2008), and can reach the standard discharge. The purity of the separated and recovered copper sulfide is 61%, the recovery rate of copper is 93%, and the recovered copper sulfide has high recycling potential. The purity of zinc and nickel in the recycled mixed metal sulfide is 3.5 percent and 1.2 percent respectively, and the method has higher resource potential.
Example 3
The electroplating wastewater is taken from a certain electroplating plant in Jiangsu province and mainly used for producing copper-plated parts. The specific treatment steps are as follows:
(1) collecting waste water in a reservoir
The water storage pool collects copper-containing electroplating wastewater discharged from an electroplating workshop, the initial pH of the wastewater is 3.4, and the pH is adjusted to 2.0. Through determination, the main metal content of the waste water is as follows: cu 130mg/L, Zn 34mg/L, Ni 9mg/L, Fe 57mg/L, and the content of other heavy metals is lower than 5 mg/L.
(2) Copper sulfide precipitate
The electroplating wastewater in the water storage tank enters a sulfide reaction tank I, and a sodium sulfide solution with the initial concentration of 1.0mol/L is added into the reaction tank, wherein the adding amount of the sodium sulfide is 80% of the amount of copper substances in the wastewater. Then controlling the pH value of the system to be lower than 3.0, and stirring and reacting for 25 min; discharging the wastewater into a sedimentation tank after the reaction is finished, naturally settling for 8 hours to obtain supernatant fluid 1 and copper sulfide slurry, and centrifugally dewatering the copper sulfide slurry to obtain supernatant fluid 2 and high-purity copper sulfide; mixing the supernatant 1 and the supernatant 2 to obtain pretreated wastewater;
(3) precipitation of other heavy metals by sulfides
Enabling the pretreated wastewater prepared in the step (2) to enter a sulfide reaction tank II, adding part of solid sodium sulfide into the reaction tank, carrying out primary stirring reaction for 10min, then adding the rest solid sulfide, and carrying out secondary stirring reaction for 2min, wherein the total addition amount of the sulfide is 120% of the total amount of the rest heavy metal substances in the pretreated wastewater, and the use amount of the first part of solid sulfide is 75% of the total addition amount of the sulfide; after the secondary stirring reaction is finished, adding a flocculating agent (obtained by mixing polyacrylamide and ferrous sulfate according to the mass ratio of 3: 1), and stirring for reacting for 25min, wherein 50g of flocculating agent is added into each ton of wastewater; after the reaction is finished, adding sodium hydroxide to adjust the pH value to 7.5, discharging the wastewater into a sedimentation tank, and naturally settling for 3 hours to obtain a supernatant 4 and a high-purity mixed heavy metal sulfide; mixing the supernatant 3 and the supernatant 4 to obtain a supernatant which can reach the standard;
through detection, the heavy metal content of the treated copper-containing electroplating wastewater (the supernatant which is prepared in the step (3) and can reach the standard discharge) is as follows: cu is 0.15mg/L, Zn 0.4.4 mg/L, Ni 0.3.3 mg/L, Fe 2mg/L, and the content of other heavy metals is lower than 0.03mg/L, which meet the discharge Standard of electroplating pollutants (GB21900-2008), and can reach the standard discharge. The purity of the separated and recovered copper sulfide is 60%, the recovery rate of copper is 92%, and the recovered copper sulfide has high recycling potential. The purity of zinc and nickel in the recycled mixed metal sulfide is 3.4 percent and 1.4 percent respectively, and the method has higher resource potential.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. A method for treating copper-containing electroplating wastewater and recovering copper by using a sulfide precipitation method is characterized by comprising the following steps of:
(1) adjusting the pH value of the copper-containing electroplating wastewater to 1.5-3.0, then adding a sulfide solution with the initial concentration of 0.5-1.5 mol/L, stirring for reaction, and carrying out solid-liquid separation after the reaction is finished to obtain pretreated wastewater and copper sulfide precipitate;
(2) adding part of solid sulfide into the pretreated wastewater prepared in the step (1) for primary stirring reaction; then adding the residual solid sulfide, and carrying out secondary stirring reaction; adding a flocculating agent after the secondary stirring reaction is finished, and stirring for reaction; after the reaction is finished, adjusting the pH value of the system to 7.0-8.0, and carrying out solid-liquid separation to obtain a supernatant and a mixed heavy metal sulfide, wherein the supernatant is discharged after reaching the standard;
the dosage of the sulfide solution in the step (1) is as follows: the adding amount of the sulfide is 80-95% of the amount of copper element substances in the copper-containing electroplating wastewater;
the total consumption of the partial solid sulfide and the residual solid sulfide in the step (2) is 110-130% of the total amount of the residual heavy metal substances in the wastewater;
the dosage of the part of solid sulfide in the step (2) is 60-80% of the total dosage of the part of solid sulfide and the rest of solid sulfide.
2. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
the sulfide in the step (1) is at least one of sodium sulfide, potassium sulfide and high-concentration sulfate biological reduction wastewater.
3. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
the reaction condition in the step (1) is that the stirring reaction is carried out for 10-30 min under the condition that the pH value is 1.5-3.5.
4. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
the time of the first stirring reaction in the step (2) is 10-30 min;
and (3) the time of the secondary stirring reaction in the step (2) is 2-4 min.
5. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
the flocculating agent in the step (2) is a mixture of polyacrylamide and ferrous sulfate;
the mass ratio of the polyacrylamide to the ferrous sulfate is (2-4) to 1.
6. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 5, wherein:
the addition amount of the flocculating agent in the step (2) is every m310-60 g of wastewater.
7. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
and (3) the stirring reaction time in the step (2) is 10-30 min.
8. The method for treating copper-containing electroplating wastewater and recovering copper by sulfide precipitation according to claim 1, wherein:
the solid-liquid separation in the step (2) comprises the following specific operations:
adjusting the pH value of the system to 7.0-8.0, naturally precipitating to obtain supernatant 3 and mixed heavy metal sulfide slurry, and centrifuging the mixed heavy metal sulfide slurry to obtain supernatant 4 and mixed heavy metal sulfide; and combining the supernatant 3 and the supernatant 4 to obtain the supernatant which can be discharged to the standard.
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