Process for producing copper oxide by using copper-containing waste liquid

Abstract

The invention discloses a process for producing copper oxide by using copper-containing waste liquid. The process comprises the following steps: S1, waste liquid feeding and metering regulation and control; s2, echelon neutralization coupling thermal decomposition; s3, carrying out two-stage dynamic washing enhanced solid-liquid separation; s4, forming a low-water-content copper oxide product; according to the method, the gradient neutralization and constant-temperature thermal decomposition synergistic mechanism is adopted, so that the directional conversion of the hydroxide (Cu (OH) 2) to the target oxide (CuO) is accurately regulated and controlled, the formation of colloidal basic salt impurities is effectively avoided, the chemical composition uniformity of a copper oxide product is ensured from a reaction source, and meanwhile, the residue of unconverted hydroxide is completely eradicated; the two-stage dynamic washing process is combined with double effects of physical destruction and hydraulic penetration, so that a crystal wrapping structure in a filter cake is thoroughly disintegrated, soluble salts such as chlorides and the like are efficiently removed, and the moisture absorption and corrosion risk of a product are remarkably reduced, so that the product can directly meet strict industrial application standards.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper oxides, and particularly relates to a process for producing copper oxide by using copper-containing waste liquid. BACKGROUND

[0002] Currently, the conventional process for producing copper oxide by treating acid copper-containing waste liquid, such as etching waste liquid and electroplating waste liquid, mainly includes four basic steps of waste liquid collection, chemical neutralization and precipitation, solid-liquid separation and drying. In the neutralization and precipitation stage, an alkaline substance such as sodium hydroxide or sodium carbonate is generally used to directly neutralize the acid in the waste liquid to make copper ions generate copper hydroxide precipitate. Subsequently, filter cake is obtained by pressure filtration or centrifugal separation, and then copper hydroxide is converted into copper oxide by high-temperature calcination. However, in the prior art, one-time addition of alkali liquid is easy to cause local over-alkalization or incomplete reaction, resulting in the existence of colloidal basic salt impurities or unconverted hydroxide in the copper precipitate, which not only reduces the purity of the product, but also hinders the complete conversion of the hydroxide to the oxide. Secondly, the filter cake after traditional single pressure filtration is wrapped with a large amount of chloride crystals, and conventional water washing is difficult to penetrate the dense filter cake structure, causing excessive residual chloride ions, which leads to product moisture absorption and caking and downstream application corrosion risk. SUMMARY

[0003] The purpose of the present application is to provide a process for producing copper oxide by using copper-containing waste liquid and a preparation method thereof, which takes stepwise neutralization and directional decomposition as the core, cooperates with a two-stage dynamic washing to strengthen the mass transfer mechanism, realizes the non-calcination in-situ conversion from waste liquid to high-purity copper oxide, completely avoids the particle activity deterioration caused by high-temperature phase transition, breaks the filter cake capillary crystal blockade, achieves the industrial-grade deep desalination target, and makes the copper oxide product have excellent storage stability.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A process for producing copper oxide by using copper-containing waste liquid, comprising the following steps: S1, waste liquid feeding and metering control, transferring the acid waste liquid containing hydrogen chloride and copper ions to a neutralization tank, and real-time detecting the HCl concentration and Cu 2+ content in the waste liquid, and calculating the required amount of 32% sodium hydroxide solution accordingly; S2, stepwise neutralization coupled with thermal decomposition, injecting 32% sodium hydroxide solution into the neutralization tank in stages, synchronously stirring and maintaining the system temperature at 60±2℃ under constant temperature heating conditions, and controlling the final pH value to be 8.5-9; making the waste liquid sequentially undergo neutralization reaction (HCl→NaCl) and copper precipitation reaction (Cu 2+ →Cu(OH)2), and promoting the in-situ decomposition of copper hydroxide into copper oxide (Cu(OH)2→CuO); S3, two-stage dynamic washing and strengthening solid-liquid separation, the slurry containing copper oxide solids is pumped into a plate and frame filter press, and sequentially subjected to: (a) in-situ washing of the plate and frame, washing water is introduced into the closed filter press environment to penetrate the filter cake; (b) dispersed slurry re-washing, the filter cake obtained from the first filtration is crushed and then dispersed with water to form a slurry, which is then subjected to secondary filtration to remove residual salt; S4, low-moisture copper oxide product forming, the filter cake obtained from the secondary filtration is collected, and the moisture content is controlled to be ≤30wt%, thereby obtaining a solid product mainly composed of copper oxide.

[0005] Preferably, the step S2 includes: In the first stage, 32% sodium hydroxide solution is added at a flow rate of 1.5-2.5 L / min to pH 4.0-5.0, so that more than 90% of the hydrogen chloride in the waste liquid is preferentially reacted to form sodium chloride; In the second stage, sodium hydroxide solution is added at a flow rate of 0.8-1.2 L / min to pH 8.5-9.0, so that copper ions are stepwise converted into copper hydroxide and decomposed into copper oxide; The switching trigger condition for the two stages is the real-time feedback signal of the online pH sensor, which avoids local over-alkalization leading to the formation of colloidal basic salt of copper ions.

[0006] Preferably, the constant temperature heating condition is achieved by the following method: A spiral titanium alloy heat exchange pipe is arranged in the neutralization tank, wherein the heat transfer medium is reinforced heat conducting oil with a temperature resistance ≥120℃, and a PID temperature control system and a distributed thermocouple in the tank form a closed loop control to ensure that the temperature gradient of the slurry is ≤3℃.

[0007] Preferably, the in-situ washing parameters in step S3 are: The mass ratio of washing water to primary copper oxide filter cake is 0.6:1-0.8:1; The washing water flow rate is 1.0-1.5 m 3 / h, and the pressure is maintained at 0.4-0.6 MPa; The washing water is 40-50℃ softened water, which is circulated through the filter cake for more than 3 times.

[0008] Preferably, in the dispersed slurry re-washing, a shear-type turbine disperser is used for crushing the filter cake, the rotation speed is ≥2800 rpm, the solid-liquid mass ratio of the slurry is 1:4-1:6, and the dispersion time is 8-12 min until the slurry viscosity is 100-180 mPa·s.

[0009] Preferably, the copper oxide filter cake obtained in step S4 is subjected to particle size regulation by a crusher and then enters a fluidized bed dryer, the inlet air temperature is 95-105℃, and the treatment time is 10-15 min, and the specific surface area of the final product is ≥25 m 2 / g, particle size is 15-35 μm.

[0010] Preferably, the sodium hydroxide solution in step S1 is added in an amount calculated as follows: , wherein, is the concentration of waste liquid hydrogen chloride (g / L), is the concentration of copper ions (g / L), is the volume of waste liquid (m 3 ), is the density of 32% sodium hydroxide solution (1.35 g / cm 3 ), is the safety factor (1.05-1.15).

[0011] Preferably, the filter plate material of the plate and frame filter press in step S3 is ultra-high molecular weight polyethylene coating, the filter cloth is double-layer structure, the outer layer is polyester and the inner layer is polypropylene, the hydraulic system pressure is set to 12-15 MPa, and the pressure holding time is 20-30 min.

[0012] Preferably, the salt-containing wastewater generated by the plate and frame in-situ washing and dispersion pulping is recovered sodium chloride crystals through an evaporation crystallization system, and the evaporation condensate water is used as washing water for plate and frame in-situ washing.

[0013] Technical effects and advantages of the present application: The gradient neutralization and constant temperature thermal decomposition synergistic mechanism precisely regulates the directional conversion of hydroxide (Cu(OH)2) to target oxide (CuO), effectively avoids the formation of colloidal basic salt impurities, guarantees the chemical composition uniformity of copper oxide product from the reaction source, and eliminates the residual unconverted hydroxide; The double-stage dynamic washing process combines the dual effects of physical destruction and hydraulic penetration, completely breaks down the crystalline encapsulation structure inside the filter cake, efficiently removes soluble salts such as chlorides, significantly reduces the hygroscopicity and corrosion risk of the product, and directly meets the strict industrial application standards; The core path innovation of low-temperature in-situ decomposition instead of high-temperature calcination eliminates the energy-intensive thermal conversion link of traditional processes, saves equipment investment, avoids particle sintering and agglomeration, guarantees the high specific surface activity of copper oxide product, and simultaneously reduces carbon dioxide emissions. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present application will be described below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of the present application.

[0015] The application discloses a process for producing copper oxide by using copper-containing waste liquid, and the process flow is as follows: The waste liquid is collected into the plant from a hazardous waste producing enterprise, and is transferred into a waste liquid storage pool after being brought into the plant.

[0016] Neutralization and precipitation; the acidic copper-containing waste liquid is pumped into the neutralization and precipitation tank through a corrosion-resistant pump, the amount of 32% sodium hydroxide solution required to be added is determined according to the hydrogen chloride content and copper content in the acidic copper-containing waste liquid, the sodium hydroxide solution in the dosing tank is pumped into the neutralization tank through a metering tank, stirring and neutralization are started, copper ions in the copper-containing waste water are precipitated by sodium hydroxide to generate copper hydroxide precipitation, and heating is simultaneously performed, the temperature is kept at 60 DEG C, and finally the pH value of the neutralization and precipitation tank is controlled at 8.5-9; At this time, most of the copper chloride is converted into the precipitated copper hydroxide and then decomposed into copper oxide. The related chemical reaction equations are as follows: HCl + NaOH = NaCl + H2O; CuCl2 + 2NaOH = Cu(OH)2 + 2NaCl; Cu(OH)2 CuO + H2O; Filter pressing and washing; after the precipitation is completed, the slurry pump is started to pump the precipitate and water into the plate and frame filter press, and the plate and frame filter press is started, and after the plate and frame washing and dispersion slurry washing, the filter cake of the filter pressing is the copper oxide product with a water content of 30%, and the filtrate is discharged into a sewage treatment station.

[0017] The above process takes the stepwise neutralization and directional decomposition as the core, couples the two-stage dynamic washing and strengthens the mass transfer mechanism, and achieves a systematic breakthrough in the process of continuously preparing copper oxide from the acidic copper-containing waste liquid: for the first time, the in-situ conversion from the waste liquid to the high-purity copper oxide is realized without calcination, and the particle activity deterioration caused by the high-temperature phase change is completely avoided; by breaking the capillary crystallization blockade of the filter cake, the industrial-grade deep desalination target is achieved, so that the copper oxide product has excellent storage stability; the overall process eliminates the risk of uncontrollable sodium hydroxide addition and the overload of washing water consumption, relies on the resource utilization of waste sodium chloride and the copper loss monitoring, and builds a closed-loop production system with maximized resource efficiency, and finally forms a three-dimensional collaborative optimization in the aspects of product purity, process economy and environmental sustainability.

[0018] The specific steps are as follows: S1, waste liquid feeding and metering control; the acidic waste liquid containing hydrogen chloride and copper ions is transferred to the neutralization tank, the HCl concentration and Cu 2+ content in the waste liquid are detected in real time, and the required amount of 32% sodium hydroxide solution is calculated; the sodium hydroxide solution addition amount in step S1 is calculated according to the formula: , wherein, is the concentration of waste liquid hydrogen chloride (g / L), is the concentration of copper ions (g / L), is the volume of waste liquid (m 3 ), is the density of 32% sodium hydroxide solution (1.35 g / cm 3 ), is the safety factor (1.05-1.15); S2, gradient neutralization coupled with thermal decomposition, 32% sodium hydroxide solution is injected into the neutralization tank in stages, synchronous stirring and maintaining the system temperature at 60±2℃ under constant temperature heating conditions, controlling the final pH value to be 8.5-9; making the waste liquid sequentially undergo neutralization reaction (HCl→NaCl) and copper precipitation reaction (Cu 2+ →Cu(OH)2), and promoting the in-situ decomposition of copper hydroxide into copper oxide (Cu(OH)2→CuO); The gradient neutralization in step S2 includes: In the first stage, 32% sodium hydroxide solution is added at a flow rate of 1.5-2.5 L / min to pH 4.0-5.0, so that more than 90% of hydrogen chloride in the waste liquid is preferentially reacted to generate sodium chloride; In the second stage, sodium hydroxide solution is added at a flow rate of 0.8-1.2 L / min to pH 8.5-9.0, so that copper ions are stepwise converted into copper hydroxide and decomposed into copper oxide; The switching trigger condition of the two stages is the real-time feedback signal of the online pH sensor, which avoids the generation of colloidal basic salt of copper ions caused by local over-alkalization; The constant temperature heating condition is realized by the following way: Helical titanium alloy heat exchange pipes are arranged in the neutralization tank, in which the heat transfer medium is reinforced heat conduction oil with a temperature resistance ≥120℃, and a closed loop control is formed by the PID temperature control system and the distributed thermocouples in the tank to ensure that the slurry temperature gradient is ≤3℃; It should be noted that the stirring system is configured with a variable frequency motor (rotating speed 80-150 rpm adjustable), and its power is linked in real time with the viscosity of the slurry: when the viscosity sensor detects a value ≥500 mPa·s, the stirring power is automatically increased by 20%-30% to avoid the settlement of the precipitate; S3, two-stage dynamic washing to strengthen solid-liquid separation, the slurry containing copper oxide solid is pumped into a plate and frame filter press, and the following is sequentially performed: (a) in-situ washing of the plate and frame, washing water is introduced to penetrate the filter cake in a closed pressure filtration environment; the in-situ washing parameters of the plate and frame are: The mass ratio of washing water to primary copper oxide filter cake is 0.6:1-0.8:1; The washing water flow rate is 1.0-1.5 m 3 / h, and the pressure is maintained at 0.4-0.6 MPa; The washing water is 40-50℃ softened water, which is circulated through the filter cake for more than 3 times; (b) dispersing the slurry again and washing, crushing the filter cake obtained from the first pressure filtration and dispersing it with water to form a slurry again, and then removing the residual salt by pressure filtration again; in the dispersing and washing again, the filter cake is crushed by a shearing type turbine disperser with a rotating speed of ≥2800 rpm, the solid-liquid mass ratio in the slurry preparation is 1:4-1:6, and the dispersing time is 8-12 min until the slurry viscosity is 100-180 mPa·s; Further, the filter plate of the plate-and-frame filter press is made of ultra-high molecular weight polyethylene coating, the filter cloth is a double-layer structure with polyester as the outer layer and polypropylene as the inner layer, the pressure of the hydraulic system is set to 12-15 MPa, and the pressure maintaining time is 20-30 min; The salt-containing wastewater generated from the in-situ washing and dispersing slurry of the frame is used to recover sodium chloride crystals through an evaporation crystallization system, and the evaporation condensate water is used as the washing water for the in-situ washing of the frame. As an option, residual salt detection is performed after the step S3: 5 g of the copper oxide filter cake after the second pressure filtration is prepared into a 10% suspension, and when the conductivity of the filtrate is ≤0.5 mS / cm (25℃), it is determined to be up to standard, and the XRF detection of the residual amount of chlorine element should be ≤500 ppm. S4, molding of the low-moisture copper oxide product, collecting the filter cake obtained from the second pressure filtration, controlling the moisture content to be ≤30 wt%, and obtaining a solid product mainly composed of copper oxide; the copper oxide filter cake obtained in the step S4 is subjected to particle size regulation by a crusher, and then enters a fluidized bed dryer, the inlet air temperature is 95-105℃, and the treatment time is 10-15 min, and the final product has a specific surface area of ≥25 m 2 / g and a particle size of 15-35 μm.

[0019] Example 1 The waste liquid is a waste liquid from integrated circuit etching: Raw material treatment: 1000 L of acid etching waste liquid containing 82 g / L of copper ions and 210 g / L of chloride ions is added into a stepwise neutralization reactor.

[0020] Stepwise neutralization and decomposition: in the first stage, 20% sodium hydroxide solution is slowly added at room temperature until pH=4.2, and basic copper chloride precipitate is generated; In the second stage, the temperature is increased to 60℃, and the alkali is continuously added until pH=6.8, and the solid is converted into dark brown copper oxide slurry after 2 hours of heat preservation and stirring. The filter cake with a moisture content of 32% is obtained by pressure filtration, and the first-stage washing uses pure water to penetrate the filter cake with a cake volume of 0.8 times. In the second stage, the filter cake is dispersed in 3 times the volume of pure water to form a slurry, and the chloride ion content of the filter cake after the second pressure filtration is reduced to 120 ppm.

[0021] Dry activation: fluidized bed drying at 85°C to obtain copper oxide powder.

[0022] Example 2 Waste liquid: electroplating pickling waste liquid: Raw material treatment: 1500 L of electroplating waste liquid containing 35 g / L of copper ions and 80 g / L of sulfate ions was pretreated by ion exchange to remove nickel and zinc impurities.

[0023] Gradient neutralization and decomposition, first stage: add sodium carbonate solution at 40°C until pH = 3.9 to precipitate basic copper carbonate; Second stage: increase the temperature to 60°C, and add sodium hydroxide instead until pH = 7.2, and keep the temperature constant for 3 hours to complete the conversion of copper oxide.

[0024] Solid-liquid separation and washing: after centrifugal separation, the filter cake is washed in two stages: the first stage is 0.5% dilute hydrochloric acid to remove surface sulfate (replacement reaction), and the second stage is pure water slurry washing; the final filter cake has a sulfate residue of <200 ppm. Resource recovery: the washing wastewater is evaporated and crystallized to recover industrial-grade sodium chloride, and the copper recovery rate is 98.7%.

[0025] Comparative Example 1 Traditional neutralization-calcination method: The same source waste liquid of Example 1 is added with alkali at one time to generate copper hydroxide precipitate at pH = 7.0; The filter cake after pressure filtration has a chloride ion residue of 4200 ppm; The filter cake is calcined at 300°C for 2 hours to obtain copper oxide with a specific surface area of only 18 m 2 / g and containing 5.2wt% of undecomposed hydroxide (XRD quantification); Comparative Example 2 Single washing process: The gradient neutralization and decomposition process of Example 2 is used, but only a single conventional water washing (2 times the cake volume) is performed; The filter cake has a sulfate residue of up to 2850 ppm, and the dried product absorbs moisture and becomes lumpy after 72 hours of storage in a humidity of 50%.

[0026] Effect comparison table

[0027] Table 1 The above table, the XRD pattern of Example 1 / 2 only shows CuO characteristic peaks (JCPDS #80-1268), while Comparative Example 1 has obvious Cu(OH)2 diffraction peaks (2θ = 16.7°), confirming that the gradient neutralization and thermal decomposition achieves complete conversion of hydroxide to oxide without the generation of basic salt transition phase; Ion chromatography analysis shows that the removal rate of internal chloride ions of the filter cake of Example 1 after the second-stage pulping washing is increased by 97% compared with single washing, proving that the dispersed pulping effectively destroys the crystalline plugging structure of the filter cake, and the salt diffusion channel is fully opened; Based on the operation data of Example 1: The investment of calcination kiln equipment is saved by about 2 million yuan, the steam consumption per ton of copper is reduced from 4.2 tons to 1.1 tons, the wastewater reuse reduces the cost of raw water by 37%, and the comprehensive cost is reduced by 52% (compared with Comparative Example 1).

[0028] The gradient neutralization and constant-temperature thermal decomposition synergistic mechanism of the application accurately regulates the directional conversion of hydroxide (Cu(OH)2) to target oxide (CuO), effectively avoids the formation of colloidal basic salt impurities, ensures the chemical composition uniformity of copper oxide product from the reaction source, and eliminates the residual unconverted hydroxide; The double-stage dynamic washing process combines the dual effects of physical destruction and hydraulic penetration, completely breaks down the crystalline encapsulation structure inside the filter cake, efficiently removes chlorides and other soluble salts, significantly reduces the moisture absorption and corrosion risk of the product, and directly meets the strict industrial application standards; The core path innovation of using low-temperature in-situ decomposition instead of high-temperature calcination eliminates the energy-intensive thermal conversion link of the traditional process, saves equipment investment, avoids particle sintering and agglomeration, guarantees the high specific surface activity of the copper oxide product, and simultaneously reduces carbon dioxide emissions.

[0029] Finally, it should be noted that: the above only describes the preferred embodiments of the application and is not intended to limit the application. Although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features, as long as they are within the spirit and principles of the application. Any modification, equivalent replacement, improvement, etc. shall be included in the protection scope of the application.

Claims

1. A process for producing copper oxide from copper-containing wastewater, characterized in that, Includes the following steps: S1. Wastewater Feeding and Metering Control: Acidic wastewater containing hydrogen chloride and copper ions is transferred to a neutralization tank, and the concentrations of HCl and Cu in the wastewater are monitored in real time. 2+ The content is determined, and the required dosage of 32% sodium hydroxide solution is calculated accordingly; S2. A phased neutralization coupled with thermal decomposition involves injecting a 32% sodium hydroxide solution into the neutralization tank in stages, simultaneously stirring and maintaining the system temperature at 60±2℃ under constant temperature heating conditions, controlling the final pH value to 8.5–9; this causes the waste liquid to undergo a neutralization reaction (HCl→NaCl) and a copper precipitation reaction (Cu). 2+ →Cu(OH)2), and promotes the in-situ decomposition of copper hydroxide into copper oxide (Cu(OH)2→CuO); S3. Two-stage dynamic washing enhances solid-liquid separation. The slurry containing copper oxide solids is pumped into the plate and frame filter press, and the following processes are performed sequentially: (a) Plate and frame in-situ washing: Washing water is introduced into the filter cake in a closed pressure filtration environment; (b) Dispersed pulping and washing: The filter cake obtained from the first pressing is crushed and pulped with water for a second time, and then pressed again to remove residual salts; S4. The low-moisture copper oxide product is formed, and the filter cake obtained by secondary pressure filtration is collected. Its moisture content is controlled to be ≤30wt% to obtain a solid product with copper oxide as the main component.

2. The process for producing copper oxide from copper-containing wastewater according to claim 1, characterized in that, The tiered neutralization in step S2 includes: In the first stage, 32% sodium hydroxide solution is added at a flow rate of 1.5-2.5 L / min until the pH reaches 4.0-5.0, so that more than 90% of the hydrogen chloride in the waste liquid preferentially reacts to form sodium chloride; In the second stage, sodium hydroxide solution is added at a flow rate of 0.8-1.2 L / min until the pH reaches 8.5-9.0, so that copper ions are converted into copper hydroxide stepwise and decomposed into copper oxide. The two-stage switching is triggered by the real-time feedback signal from the online pH sensor, which avoids local over-alkalinity that could lead to the formation of colloidal basic salts from copper ions.

3. The process for producing copper oxide from copper-containing wastewater according to claim 2, characterized in that, Constant temperature heating conditions are achieved in the following ways: A spiral titanium alloy heat exchange tube is installed in the neutralization tank, wherein the heat transfer medium is enhanced heat transfer oil with a temperature resistance of ≥120℃, and a closed-loop control is formed with the distributed thermocouples in the tank through a PID temperature control system to ensure that the slurry temperature gradient is ≤3℃.

4. The process for producing copper oxide from copper-containing wastewater according to claim 1, characterized in that, The in-situ washing parameters for the plate and frame in step S3 are as follows: The mass ratio of washing water to primary copper oxide filter cake is 0.6:1-0.8:1; The washing water flow rate is 1.0-1.5m. 3 / h, pressure maintained at 0.4-0.6MPa; The washing water is softened water at 40-50℃, which is circulated through the filter cake more than 3 times.

5. The process for producing copper oxide from copper-containing wastewater according to claim 4, characterized in that, In the dispersion pulping and washing process, the filter cake is crushed using a shear turbine disperser with a speed of ≥2800 rpm. The solid-liquid mass ratio of the pulp is 1:4-1:6, and the dispersion time is 8-12 min until the pulp viscosity is 100-180 mPa·s.

6. The process for producing copper oxide from copper-containing wastewater according to claim 1, characterized in that, The copper oxide filter cake obtained in step S4, after being crushed and its particle size adjusted, enters a fluidized bed dryer with an inlet air temperature of 95-105℃ and is processed for 10-15 minutes. The final product has a specific surface area ≥25m². 2 / g, with a particle size of 15-35μm.

7. The process for producing copper oxide from copper-containing wastewater according to claim 1, characterized in that, The amount of sodium hydroxide solution added in step S1 is calculated according to the formula: ,in, The concentration of hydrogen chloride in the waste liquid is (g / L). The concentration of copper ions is expressed in g / L. Waste liquid volume (m 3 ), The density of a 32% sodium hydroxide solution is 1.35 g / cm³. 3 ), The safety factor is (1.05-1.15).

8. The process for producing copper oxide from copper-containing wastewater according to claim 1, characterized in that, The filter plate material of the plate and frame filter press described in step S3 is ultra-high molecular weight polyethylene coating, and the filter cloth has a double-layer structure, with an outer layer of polyester and an inner layer of polypropylene. The hydraulic system pressure is set to 12-15MPa and the pressure holding time is 20-30min.

9. The process for producing copper oxide from copper-containing wastewater according to claim 4, characterized in that, The saline wastewater generated from the in-situ washing and dispersion pulping of the plate and frame is used to recover sodium chloride crystals through an evaporation crystallization system, and the evaporation condensate is reused as washing water for in-situ washing of the plate and frame.

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