Method and system for treating spent tin stripping solution with component qualification recovery

Abstract

The present application relates to the technical field of industrial wastewater recycling treatment, solves the problem of low resource utilization efficiency and difficulty in directional recovery of multiple components in the existing technology of tin stripping waste liquid, and provides a tin stripping waste liquid treatment method and system for component qualitative recovery. The method comprises: carrying out aeration treatment on the tin stripping waste liquid to be treated and controlling the pH within a preset pH range; adding liquid alkali and mixing with a flocculating agent and pressure filtration to obtain tin hydroxide precipitate and first pressure filtrate; introducing the first pressure filtrate meeting the preset condition into a second reaction tank, adding liquid alkali and activated carbon to the second reaction tank for neutralization and primary copper precipitation treatment, obtaining copper hydroxide precipitate and collecting primary copper precipitation filtrate; introducing the primary copper precipitation filtrate into a third reaction tank for secondary copper precipitation treatment and then pressure filtration to obtain copper sulfide precipitate and sodium salt raw liquid; and distilling and centrifuging the sodium salt raw liquid to obtain sodium nitrate product. The present application realizes the qualitative recovery of multiple components in the tin stripping waste liquid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial wastewater recycling and treatment, and particularly relates to a tin stripping waste liquid treatment method and system for component qualitative recovery. BACKGROUND

[0002] The tin stripping process is widely used in metal surface treatment, electroplating and electronic manufacturing fields. A large amount of tin stripping waste liquid is generated in the tin stripping process. The tin stripping waste liquid is usually strongly acidic and complex in composition, containing not only a high concentration of tin ions but also copper and other heavy metal ions and a large amount of soluble salts. If directly discharged, it can cause serious pollution to water bodies and soil environments. Therefore, the tin stripping waste liquid needs to be effectively treated.

[0003] The treatment of tin stripping waste liquid is mainly based on neutralization and precipitation. By adding an alkaline agent to the waste liquid, metal ions are precipitated, and then solid-liquid separation is performed to reduce the content of heavy metals in the waste liquid. However, this treatment method usually only coarsely removes a single metal, and in actual application, problems such as co-precipitation of multiple metals, incomplete precipitation, and large fluctuations in filtrate indicators often occur, resulting in an increased burden on subsequent treatment. At the same time, due to uneven mixing of the waste liquid into the reaction system, local pH fluctuates significantly, often affecting the stability of the precipitation reaction and the filtration performance.

[0004] For tin-containing tin stripping waste liquid, if the tin precipitation stage is not properly controlled, tin can be easily entrained into the subsequent treatment process, reducing the recovery rate of tin and interfering with the removal of copper in the subsequent process, making the copper precipitation unstable. Some processes use a one-time copper precipitation method to remove copper ions, but when the copper content fluctuates or the system conditions change, it is often difficult to achieve deep removal, and residual copper entering the subsequent salt system can significantly affect the purity and crystallization performance of the final salt product.

[0005] For example, the existing patent CN108070720B provides a comprehensive recovery method for tin stripping waste liquid, which recovers nitric acid by vacuum distillation, removes organic matter in the waste liquid by Fenton reagent, and then recovers copper and tin by extraction, electrolysis, evaporation and other processes. This method recovers metals in multiple steps, but still faces problems such as low recovery efficiency of tin, copper and other metals, complex process, secondary pollution, etc. Especially in terms of metal separation precision, existing methods cannot achieve complete step-by-step recovery, which can easily lead to mutual interference of different metals in the recovery process, affecting the purity and recovery rate of the product.

[0006] Therefore, how to achieve step-by-step and directional removal of tin, copper and other heavy metals in tin stripping waste liquid while ensuring system stability, and further recover the sodium salt system after treatment, so as to build a tin stripping waste liquid treatment process that takes into account treatment effect, resource utilization and environmental friendliness, is still a technical problem that needs to be solved in the field. SUMMARY

[0007] Therefore, the application provides a tin stripping waste liquid treatment method and system for component qualitative recovery to solve the problem that components such as tin, copper and sodium salt in the tin stripping waste liquid are difficult to realize directional recovery and resource utilization efficiency is low in the prior art.

[0008] In a first aspect, the application provides a tin stripping waste liquid treatment method for component qualitative recovery, which comprises the following steps:

[0009] The tin stripping waste liquid to be treated is introduced into a first reaction tank and subjected to aeration treatment at the same time, and the pH in the first reaction tank is controlled to be within a first preset pH range;

[0010] After the aeration reaction is completed, liquid alkali and a flocculating agent are added for mixing treatment, and the mixed system is sent into a tin stripping water filter press for pressure filtration to obtain tin hydroxide precipitate and a first pressure filtrate;

[0011] The first pressure filtrate meeting a preset condition is introduced into a second reaction tank, and liquid alkali and activated carbon are added to the second reaction tank for neutralization and primary copper precipitation treatment, to obtain copper hydroxide precipitate and a primary copper precipitation filtrate;

[0012] The primary copper precipitation filtrate is introduced into a third reaction tank, and liquid alkali and a copper precipitation reagent are sequentially added to the third reaction tank for secondary copper precipitation treatment, and then pressure filtration is performed to obtain copper sulfide precipitate and a sodium salt stock solution;

[0013] The sodium salt stock solution is subjected to distillation and centrifugal treatment to obtain a sodium nitrate product.

[0014] Preferably, the step of introducing the tin stripping waste liquid to be treated into the first reaction tank and simultaneously performing aeration treatment, and controlling the pH in the first reaction tank to be within the first preset pH range comprises the following steps:

[0015] A preset volume of the tin stripping waste liquid is delivered to the first reaction tank by aeration gas, and the tin stripping waste liquid is subjected to aeration treatment at the same time;

[0016] The pH of the system in the first reaction tank is monitored during the process of introducing the tin stripping waste liquid into the first reaction tank, to obtain a first pH detection result;

[0017] The pH in the first reaction tank is adjusted according to the first pH detection result and the first preset pH range, wherein the first preset pH range is 1.0-2.0;

[0018] When the tin stripping waste liquid is completely introduced into the first reaction tank, the aeration is stopped.

[0019] Preferably, the liquid caustic and flocculant are added after the completion of the aeration reaction for mixing treatment, and the mixed system is sent to a tin stripping water filter press for pressure filtration to obtain tin hydroxide precipitate and first pressure filtrate, including:

[0020] The liquid caustic is added to the system after the completion of the aeration reaction for neutralization to obtain a first mixed system for tin precipitation;

[0021] According to the incoming condition of the tin stripping waste liquid to be treated, a flocculant is added to the first mixed system for mixing treatment to obtain a second mixed system, wherein the flocculant includes a PAM reagent;

[0022] The second mixed system is subjected to pressure filtration separation treatment to obtain tin hydroxide precipitate and initial pressure filtrate;

[0023] The initial pressure filtrate is detected to obtain a detection result, wherein the detection result includes pH value and tin content;

[0024] According to the detection result, it is judged whether the initial pressure filtrate meets the preset condition, wherein the preset condition includes that the pH value of the initial pressure filtrate is less than 2.5 and the tin content of the initial pressure filtrate is lower than 6 mg / L;

[0025] If yes, the initial pressure filtrate is used as the first pressure filtrate.

[0026] Preferably, according to the incoming condition of the tin stripping waste liquid to be treated, a flocculant is added to the first mixed system for mixing treatment to obtain a second mixed system, including:

[0027] The incoming condition of the tin stripping waste liquid is obtained, including the addition volume of the tin stripping waste liquid, waste liquid composition and suspended matter state;

[0028] According to the incoming condition and flocculant addition range, the addition parameters of the flocculant are determined, including at least the addition amount of the flocculant, and the flocculant addition range is 20-60 kg;

[0029] According to the addition parameters, the flocculant is added to the first mixed system for mixing treatment to obtain the second mixed system.

[0030] Preferably, the first pressure filtrate meeting the preset condition is introduced into a second reaction tank, and liquid caustic and activated carbon are added for neutralization and primary copper precipitation treatment to obtain copper hydroxide precipitate and collect primary copper precipitation filtrate, including:

[0031] The first pressure filtrate meeting the preset condition is introduced into a second reaction tank, and the pH of the second reaction tank is monitored to obtain a second pH detection result;

[0032] adding liquid caustic into the second reaction tank according to the second pH detection result, so as to adjust the pH in the second reaction tank to be in a second preset pH range, wherein the second preset pH range is 6.0-10.0;

[0033] adding activated carbon into the second reaction tank when the pH is in the second preset pH range to carry out primary copper precipitation treatment, so as to obtain a primary copper precipitation product;

[0034] carrying out pressure filtration separation on the primary copper precipitation product, so as to obtain copper hydroxide precipitate and a primary copper precipitation filtrate.

[0035] Preferably, the primary copper precipitation filtrate is introduced into a third reaction tank, and liquid caustic and copper precipitation reagent are sequentially added into the third reaction tank to carry out secondary copper precipitation treatment, and then pressure filtration is carried out, so as to obtain copper sulfide precipitate and sodium salt stock solution, including:

[0036] introducing the primary copper precipitation filtrate into a third reaction tank;

[0037] monitoring the pH of the system in the third reaction tank to obtain a third pH detection result;

[0038] adding liquid caustic into the third reaction tank according to the third pH detection result, so as to adjust the pH of the system in the third reaction tank to be in a third preset pH range, wherein the third preset pH range is 7.0-8.0;

[0039] adding copper precipitation reagent into the third reaction tank to carry out secondary copper precipitation treatment, wherein the copper precipitation reagent includes sodium sulfide;

[0040] sending the system after the secondary copper precipitation treatment into a pressure filter to carry out pressure filtration separation, so as to obtain copper sulfide precipitate and sodium salt stock solution.

[0041] Preferably, the sodium salt stock solution is subjected to distillation and centrifugal treatment, so as to obtain sodium nitrate product, including:

[0042] introducing the sodium salt stock solution into a sodium salt evaporation unit and carrying out distillation treatment according to a preset number of distillation times, so as to obtain sodium nitrate mother liquor;

[0043] carrying out second distillation treatment on the sodium nitrate mother liquor, so as to obtain secondary distillation material;

[0044] sending the secondary distillation material into a centrifugal device to carry out centrifugal separation, and collecting the obtained sodium nitrate product, wherein the mass fraction of sodium nitrate in the sodium nitrate product is not less than 93 wt%.

[0045] Preferably, the preset number of distillation times is 1 or 2.

[0046] Preferably, after the secondary distillation material is sent into the centrifugal device for centrifugal separation and the sodium nitrate product obtained by centrifugal separation is collected, the method further comprises:

[0047] collecting the residual liquid generated in the distillation and / or centrifugal process;

[0048] transporting the residual liquid to a physicochemical workshop, and performing physicochemical treatment on the residual liquid in the physicochemical workshop;

[0049] after the physicochemical treatment is completed, discharging or recycling the treated liquid.

[0050] In a second aspect, the embodiments of the present application also provide a desmear waste liquid treatment system, characterized in that the system comprises a first reaction tank, a desmear water filter press, a second reaction tank, a primary copper precipitation filter press, a third reaction tank, a secondary copper precipitation filter press, a sodium salt evaporation unit, a centrifugal device and a controller; wherein the first reaction tank is in communication with the desmear water filter press, the second reaction tank, the primary copper precipitation filter press, the third reaction tank, the secondary copper precipitation filter press, the sodium salt evaporation unit and the centrifugal device in sequence, the physicochemical treatment unit is in communication with the sodium salt evaporation unit and / or the centrifugal device, and the controller is in signal connection with the first reaction tank, the desmear water filter press, the second reaction tank, the primary copper precipitation filter press, the third reaction tank, the secondary copper precipitation filter press, the sodium salt evaporation unit and the centrifugal device respectively, and is used for controlling the system to perform the desmear waste liquid treatment method for qualitative recovery of components as described in the first aspect.

[0051] In summary, the beneficial effects of the present application are as follows:

[0052] The desmear waste liquid treatment method and system for qualitative recovery of components provided by the embodiments of the present application realize the orderly separation and directional recovery of multiple components in the desmear waste liquid by constructing a treatment process taking tin precipitation, step-by-step copper precipitation and sodium salt recovery as the core. Specifically, by setting a tin precipitation section with controlled aeration and pH adjustment at the front end, tin is preferentially precipitated from the system in the form of hydroxide and stably separated, effectively reducing the interference of tin on subsequent treatment links; on this basis, by combining the step-by-step treatment mode of primary copper precipitation and secondary copper precipitation, the copper component is gradually enriched under different reaction conditions and forms a precipitate, respectively, which not only improves the thoroughness of copper removal, but also avoids the separation instability problem caused by the co-precipitation of multiple metals.

[0053] Meanwhile, after the directional removal of heavy metals is completed, the present application further distills and centrifugally recovers the treated sodium salt system, converts the sodium salt raw liquid originally required to be disposed as high-salt waste liquid into sodium nitrate product with utilization value, and significantly improves the overall resource utilization degree of the tin stripping waste liquid. Through the above step-by-step and directional processing path, the system operation is more stable, the filtration and separation process is more controllable, and the operation risk caused by the index fluctuation of the filtrate is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced as follows, and other drawings can also be obtained by those of ordinary skill in the art without creative labor on the premise that these drawings are within the protection scope of the present application.

[0055] Figure 1 is a flowchart of the tin stripping waste liquid treatment method of the component qualitative recovery embodiment of the present application.

[0056] Figure 2 is another flowchart of the tin stripping waste liquid treatment method of the component qualitative recovery embodiment of the present application.

[0057] Figure 3 is another flowchart of the tin stripping waste liquid treatment method of the component qualitative recovery embodiment of the present application.

[0058] Figure 4 is another flowchart of the tin stripping waste liquid treatment method of the component qualitative recovery embodiment of the present application.

[0059] Figure 5 is another flowchart of the tin stripping waste liquid treatment method of the component qualitative recovery embodiment of the present application. DETAILED DESCRIPTION

[0060] The features and exemplary embodiments of various aspects of the present application will be described in detail below, in order to make the purposes, technical solutions and advantages of the present application more clear and apparent, the present application will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are configured only to explain the present application, and are not configured to limit the present application. The present application can be implemented without some of these specific details by those skilled in the art. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0061] It is to be noted that the relative terms such as first and second and the like are used herein solely to distinguish one entity or action from another, not necessarily in an actual chronological or spatial relationship. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element preceded by "comprises... " does not, without more constraints, foreclose the existence of additional identical elements in the process, method, article, or apparatus that comprises the recited element.

[0062] Embodiment 1

[0063] Referring to Figures 1-5 The embodiment of the present application provides a tin stripping waste liquid treatment method for component qualitative recovery, and the method comprises the following steps:

[0064] S1, the tin stripping waste liquid to be treated is introduced into a first reaction tank and subjected to aeration treatment at the same time, and the pH in the first reaction tank is controlled to be within a first preset pH range;

[0065] The first reaction tank is used for receiving the tin stripping waste liquid to be treated, and the aeration treatment is simultaneously performed in the process of introducing the tin stripping waste liquid. The aeration mainly plays a role of gas stirring and mixing, so that the tin stripping waste liquid can be fully mixed and uniform in the process of entering the reaction tank, and local acidity or alkalinity or component distribution is avoided to cause subsequent precipitation fluctuation. Moreover, the aeration can not only accelerate the oxidation reaction of the metal, but also help to remove the dissolved organic matter in the waste liquid, especially some difficult-to-dissolve or insoluble organic pollutants. For example, the introduction of oxygen can promote the decomposition of the organic matter in the waste liquid, reduce the pollutants of the waste liquid, and especially for the metal which needs to be further precipitated, the removal of the organic matter helps to improve the precipitation efficiency and the purity of the metal.

[0066] The first preset pH range is a control window of this section of process. Through the monitoring and adjustment of the pH in the system in the reaction tank, the pH in the system is stabilized in the target interval, so that consistent initial conditions are created for the subsequent directional precipitation of tin and solid-liquid separation, the uniformity of the system and the controllability of the process are improved, the batch fluctuation is reduced, the tin precipitate obtained through subsequent pressure filtration is more stable, and the filtrate index is more likely to meet the standard.

[0067] S2, after the aeration reaction is completed, liquid alkali and a flocculating agent are added and mixed, and the mixed system is sent into a tin stripping water pressure filter for pressure filtration, so as to obtain a tin hydroxide precipitate and a first pressure filtrate;

[0068] Specifically, liquid caustic is used to neutralize the system after S1, prompting tin to precipitate from the liquid phase in the form of hydroxide; the flocculating agent is used to promote the agglomeration of fine precipitated particles, improve the filterability of the precipitate and the efficiency of solid-liquid separation. After adding liquid caustic and flocculating agent, the system is thoroughly mixed to make the precipitation reaction and flocculation process occur uniformly in the system, and then the mixed system is sent to the tin removal water filter press for pressure filtration. The solid phase obtained by pressure filtration is tin hydroxide precipitate, and the liquid phase is the first filtrate. This step realizes the effective separation of tin and liquid phase, and enhances the pressure filtration performance with the help of flocculation, reduces the entrainment of filtrate tin caused by fine mud penetration, and provides cleaner feed conditions for the subsequent copper precipitation section.

[0069] S3, the first filtrate meeting the preset condition is introduced into a second reaction tank, and liquid caustic and activated carbon are added to neutralize and carry out primary copper precipitation treatment, to obtain copper hydroxide precipitate and collect the primary copper precipitation filtrate;

[0070] The second reaction tank is used to receive the first filtrate meeting the preset condition and complete the primary copper precipitation treatment. Primary copper precipitation refers to the conversion of copper components in the solution into solid phase precipitate by adjusting the pH and cooperating with activated carbon, so as to separate from the liquid phase. The role of liquid caustic is to adjust the pH of the system to the control range of primary copper precipitation, so that the copper precipitation reaction can proceed under suitable conditions; activated carbon as an auxiliary medium is beneficial to improve the removal efficiency of the copper precipitation process and the stability of the precipitate formation, and then copper hydroxide precipitate is obtained by pressure filtration separation, and the primary copper precipitation filtrate is collected as the feed of the next secondary copper precipitation. The beneficial effect of this step is to realize the first stage enrichment of copper, reduce the copper residue in the subsequent system, avoid the interference of copper on the subsequent sodium salt recovery section, and at the same time form the copper precipitate which can be recycled, thereby improving the degree of resource utilization.

[0071] S4, the primary copper precipitation filtrate is introduced into a third reaction tank, and liquid caustic and copper precipitation reagent are sequentially added to carry out secondary copper precipitation treatment, and then pressure filtration is carried out to obtain copper sulfide precipitate and sodium salt raw liquid;

[0072] The third reaction tank is used for secondary copper precipitation treatment of the primary copper precipitation filtrate. In this step, liquid caustic is first added to adjust the pH of the system again, so that it meets the conditions required by the secondary copper precipitation reaction, and then copper precipitation reagent is added to further convert the residual copper from the liquid phase into the solid phase. The copper precipitation reagent is usually a sulfide such as sodium sulfide, which precipitates copper in the form of copper sulfide. After secondary copper precipitation, copper sulfide precipitate is obtained by pressure filtration separation, and sodium salt raw liquid is obtained. This step realizes the deep removal and staged enrichment of copper, and compared with only one copper precipitation, it is easier to obtain sodium salt raw liquid with lower copper residue, thereby improving the purity and crystallization stability of the subsequent sodium nitrate product, and further improving the recovery rate of copper resources in the waste liquid.

[0073] S5, distillation and centrifugal treatment are carried out on the sodium salt raw liquid to obtain sodium nitrate product.

[0074] Specifically, the sodium salt stock solution enters the sodium salt evaporation unit for distillation treatment. The distillation can be performed for a preset number of times to obtain a sodium nitrate mother liquor. Then, the sodium nitrate mother liquor is subjected to secondary distillation, and the obtained material is sent into a centrifugal device for centrifugal separation to obtain a sodium nitrate product. The sodium nitrate mother liquor here refers to a mother liquor enriched with sodium nitrate after distillation and concentration. The centrifugal separation is used to separate the crystalline or solid sodium nitrate from the residual liquid. The beneficial effect is that the sodium salt system is further resourceized to form a sodium nitrate product, reducing the external discharge volume of high-salt waste liquid, and realizing the closed-loop treatment of reduction, resourceization and harmlessness by combining the physicochemical treatment of the residual liquid at the end, thereby reducing the environmental emission risk and improving the overall economic value.

[0075] Preferably, the step S1 comprises:

[0076] S11, delivering a preset volume of the tin stripping waste liquid into a first reaction tank by aeration gas while performing aeration treatment on the tin stripping waste liquid;

[0077] Specifically, the tin stripping waste liquid is delivered into the first reaction tank by aeration gas while performing aeration treatment on the tin stripping waste liquid. The aeration gas can be understood as a gas medium introduced in the delivery pipeline, which functions to assist the tin stripping waste liquid to enter the first reaction tank and to form a continuous gas disturbance in the process of the tin stripping waste liquid entering the reaction tank, so that the tin stripping waste liquid can be fully mixed in the feeding stage. The purpose of this step is to avoid the stratification of the tin stripping waste liquid caused by the fluctuation of the incoming composition or the local concentration difference in the reaction tank, thereby reducing the fluctuation caused by uneven mixing in the subsequent precipitation reaction from the source. The beneficial effect is to improve the uniformity of the system, make the subsequent pH monitoring and adjustment more representative, and reduce the risk of abnormal precipitation or entrainment caused by local acid or alkali. In an embodiment, the preset volume is 7 m 3 .

[0078] S12, monitoring the pH of the system in the first reaction tank in the process of the tin stripping waste liquid entering the first reaction tank to obtain a first pH detection result;

[0079] The pH of the system in the first reaction tank is monitored in the process of the tin stripping waste liquid entering the first reaction tank to obtain a first pH detection result. The pH monitoring here is the real-time acquisition of the acidity and alkalinity state in the reaction tank, and the first pH detection result is used to represent whether the current system is within the target control window. The purpose of this step is to change the pH control from after-treatment adjustment to process control, so that the system can timely find the pH deviation in the feeding stage and take adjustment measures, avoiding the repeated dosing or system fluctuation caused by the correction after the deviation accumulation. The beneficial effect is to improve the timeliness and controllability of pH control, and to provide a stable and repeatable acidic environment for the subsequent directional precipitation of tin.

[0080] S13. Adjust the pH in the first reaction vessel according to the first pH detection result and the first preset pH range, wherein the first preset pH range is 1.0~2.0;

[0081] pH adjustment refers to correcting the system's acidity or alkalinity based on monitoring results, bringing it back to or maintaining it within a preset range. This preset range reflects the acidic environment requirements of this process before tin immersion. The purpose of this step is to stabilize the system in the reaction tank within a suitable acidity range, preventing excessively high pH from causing premature hydrolysis of tin into colloids or fine precipitates in the initial stage, thus affecting subsequent separation. It also prevents excessively low pH from causing abnormal reaction conditions and increasing the burden of subsequent neutralization. This makes it easier to obtain a filterable precipitate when adding liquid alkali and flocculants for tin immersion, and improves the stability of the first filtrate.

[0082] In one embodiment, step S13 includes:

[0083] S131. Based on the preset volume of the tin stripping waste liquid and the first pH detection result, obtain the initial dosage of liquid alkali;

[0084] In this step, the initial dosage of caustic soda is first calculated based on the preset volume of the tin stripping waste liquid (e.g., 7 m³) and the initial pH test results. The volume of the waste liquid is a crucial factor in determining the initial caustic soda dosage, directly affecting the scale of the required acid-base adjustment. The pH value of the waste liquid reflects the required pH adjustment; lower or higher pH values ​​necessitate the addition of more or less caustic soda. Therefore, the calculation of the initial dosage combines the volume and pH value of the waste liquid, ensuring that the dosage is neither too much nor too little, providing a reasonable starting point for subsequent fine-tuning. This approach avoids the empirical estimation errors found in traditional methods, ensuring the accuracy of the initial adjustment stage.

[0085] S132. Based on the initial dosage, obtain the stage dosage of the preset dosage stage, wherein the preset dosage stage includes at least three dosage stages, and the stage dosage of the different dosage stages is different;

[0086] The dosage at each stage is determined by both the reaction progress and the initial dosage. The pre-set dosing stages include at least three phases: a coarse adjustment phase, an accelerated adjustment phase, and a fine adjustment phase, each with a different dosage. In the coarse adjustment phase, a relatively large flow rate of liquid alkali is added to quickly adjust the pH of the waste liquid towards the target range. As the reaction progresses, the dosage gradually decreases. During the accelerated adjustment phase, the dosage is moderately increased to quickly approach the target pH value. Finally, in the fine adjustment phase, the dosage of liquid alkali is gradually reduced to ensure the pH remains stable within the target range, avoiding over-adjustment. The dosage of liquid alkali at each stage is dynamically adjusted based on the actual reaction conditions of the waste liquid and the initial dosage to ensure the accuracy of the dosage at each stage.

[0087] S133. According to the preset addition stage and the stage addition amount, add liquid alkali to the first reaction tank;

[0088] After determining the dosage for each stage, liquid alkali is added to the first reaction tank according to the pre-set dosage stages and dosages. In this step, the liquid alkali is added according to a phased plan to ensure that the addition is not only orderly but also responds in real-time to the reaction progress. The dosage of liquid alkali is adjusted as needed according to the requirements of different stages. The dosage is larger in the first stage, and gradually decreases in the second and third stages to avoid over-dosing.

[0089] S134. Monitor the pH of the system in the first reaction vessel in real time and obtain the pH change rate;

[0090] Simultaneously with the addition of liquid alkali, the pH value of the system in the first reaction vessel is monitored in real time, and the rate of pH change is recorded. The rate of pH change reflects the progress of the reaction; a faster rate may indicate that the reaction is nearing completion, while a slower rate may indicate that the reaction has not yet achieved the expected results. By monitoring the rate of pH change in real time, it is possible to determine whether the reaction is proceeding smoothly, thus providing a basis for adjusting the addition in subsequent stages. The feedback from real-time monitoring can help the system dynamically optimize subsequent addition schemes, avoiding over- or under-addition due to mismatched reaction rates.

[0091] S135. When the addition of a certain addition stage is completed, after a preset reaction time, obtain the stage pH detection result of the current stage.

[0092] After completing one stage of caustic soda dosing, the pH value of that stage is obtained after a preset reaction time (e.g., 10 minutes). This result reflects the actual effect of each stage of caustic soda dosing. If the pH value of a certain stage is close to the target range, the system prepares to proceed to the next stage. If the stage pH value deviates from the target range, the system will adjust the subsequent dosing amount based on feedback to ensure further pH stability. The stage pH value is crucial for judging the accuracy of caustic soda dosing; it is the key basis for deciding whether to proceed to the next stage or adjust the dosing amount.

[0093] S136. Adjust the dosage for the next stage based on the real-time pH change rate and the pH detection results of the stage.

[0094] Based on the real-time pH change rate and the results of stage pH monitoring, the dosage for the next stage is adjusted. If the pH change rate is rapid, it indicates that the reaction may be nearing completion, and the system will reduce the dosage for the next stage; conversely, if the pH change is slow, the system will increase the dosage for the next stage to accelerate the reaction process. Through this adjustment, the system can precisely adjust the dosage of liquid alkali at each stage according to the reaction conditions, ensuring a smoother adjustment process and avoiding over- or under-adjustment.

[0095] In one embodiment, step S136 includes:

[0096] S1361. Determine the target pH range for the current stage based on the dosage for each stage.

[0097] Specifically, in each dosing stage, the target pH range is first determined based on the previously set reaction target and the stage dosage. This step reasonably estimates the target pH range to be achieved in the current stage by referring to the actual amount of liquid alkali added and the initial pH value of the waste liquid, ensuring that the pH value in the waste liquid can change stably within the predetermined range. This target range provides a benchmark for the next step of pH detection and deviation calculation, and serves as the control basis for the entire pH adjustment process.

[0098] S1362. Based on the pH test results of each stage, assess the stage deviation between the current pH value and the target pH range of the stage.

[0099] This step assesses the deviation between the current waste liquid pH value and the set target pH range based on the actual pH test results at each stage. This deviation is a key factor in determining whether the current pH value is close to the target range. If the deviation is large, it indicates that the pH value is still far from the target value, and further adjustments to the dosage of liquid alkali may be needed; conversely, if the deviation is small, it indicates that the reaction is close to expectations, and the dosage can be reduced accordingly. By quantifying the stage deviation, the reaction progress and the required adjustment amount can be clearly determined.

[0100] S1363. Based on the difference between the pH detection result of the current stage and the pH detection result of the previous stage, obtain the pH change amount of the current stage.

[0101] In this step, the pH change at each stage is calculated by comparing the current pH reading with that of the previous stage. This change directly reflects the rate of pH change during the reaction. A larger change usually indicates a faster reaction, while a smaller change may indicate a slower reaction. By calculating the pH change at each stage, the dynamic trend of pH at each stage can be clearly understood, thus providing a real-time basis for subsequent dosage adjustments.

[0102] S1364. Based on the pH change amount, the stage deviation, and the pH change rate, determine the dosage adjustment coefficient for the next stage.

[0103] This step involves combining three factors—the amount of pH change in the stage, the stage deviation, and the rate of pH change—to obtain the dosage adjustment coefficient for the next stage. The stage deviation and the rate of pH change determine whether the amount of liquid alkali to be added or reduced, while the amount of pH change in the stage determines the magnitude of the adjustment.

[0104] The stage deviation reflects the difference between the current pH value and the target pH value. A larger deviation indicates that the current pH value is far from the target pH value, requiring more liquid alkali to be added to bring it closer to the target range. If the deviation is small, it indicates that the pH value is close to the target value, and the dosage should be reduced accordingly.

[0105] The rate of pH change indicates how quickly the pH value changes, reflecting the speed of the reaction process. A faster rate of change indicates that the reaction is nearing completion, and the dosage can be reduced to avoid over-adjustment; while a slower rate of change indicates that the reaction is progressing slowly, and the dosage needs to be increased to accelerate the reaction.

[0106] The pH change at each stage provides specific information about the reaction progress, indicating the magnitude of pH change during that stage. A larger pH change at a stage indicates a faster reaction progress, allowing for a reduction in the dosage; while a smaller pH change indicates a slower reaction progress, requiring an increase in the dosage to accelerate the reaction.

[0107] By combining stage deviation, pH change rate, and stage pH change amount, the system can accurately determine the dosage adjustment coefficient for the next stage.

[0108] S1365. Adjust the dosage for the next stage according to the dosage adjustment coefficient.

[0109] Finally, based on the calculated dosage adjustment coefficient, the dosage for the next stage is adjusted accordingly. Specifically, if the adjustment coefficient indicates that the reaction has not yet approached the target pH, the system will increase the amount of liquid alkali added; if the adjustment coefficient indicates that the reaction has approached the target pH, the dosage will be reduced. In this way, the reaction can be effectively and precisely controlled, avoiding excessive or insufficient liquid alkali dosage during the reaction.

[0110] S137. Add liquid alkali to the first reaction tank according to the adjusted stage dosage to adjust the pH of the first reaction tank.

[0111] After adjustment, the system will continue to add liquid alkali to the first reaction tank according to the adjusted stage dosage, and further adjust the pH in the reaction tank. During this stage, the system optimizes the dosage and reaction time to ensure the pH value of the waste liquid remains stable within the target range (1.0~2.0). If the pH value continues to deviate from the target range, it will be fine-tuned again until the pH value is completely stable within the target range. This step ensures precise addition of liquid alkali and fine control of the reaction, keeping the pH value of the waste liquid consistently within the required stable range.

[0112] By precisely controlling the pH value in the tin stripping waste liquid, the precipitation reaction process of metal ions in the waste liquid is optimized. Specifically, a staged liquid alkali addition method is adopted, and the addition amount is dynamically adjusted according to the reaction progress. The pH value of the waste liquid is precisely controlled by combining real-time monitoring of the pH change rate, stage deviation, and pH change amount. This method ensures a more stable precipitation reaction for metals such as tin and copper, thus avoiding the problems of incomplete precipitation and filtrate fluctuations in traditional methods, effectively improving metal recovery rate and removal efficiency. S14. After the tin stripping waste liquid is completely introduced into the first reaction tank, aeration is stopped.

[0113] Aeration is stopped after the tin stripping waste liquid is completely introduced into the first reaction tank. This step demonstrates the synchronized start and stop of aeration and the introduction process. The trigger condition for stopping aeration is the completion of the tin stripping waste liquid introduction, thus avoiding unnecessary energy consumption or system disturbance caused by continuing aeration after the liquid introduction is completed. The purpose of this step is to ensure that aeration only serves the conveying and mixing of the introduction stage, making the process action boundaries clear, facilitating the connection with the subsequent tin immersion chemical addition step, reducing operating costs and operational complexity, and avoiding additional disturbance to the system state caused by continuous aeration, thereby enabling the subsequent tin immersion stage to proceed under relatively stable initial conditions.

[0114] Preferably, S2 includes:

[0115] S21. Add liquid alkali to the system after the aeration reaction is completed to neutralize it, and obtain the first mixed system for tin precipitation;

[0116] Here, "liquid alkali" refers to an alkaline agent used to adjust the pH of the system. Neutralization involves adjusting the acidic system formed in the preceding steps to a pH range more suitable for tin hydrolysis and precipitation, allowing tin ions to gradually transform into tin hydroxide precipitate. The purpose of this step is to create reaction conditions for the directional precipitation of tin and to ensure that small precipitate nuclei that can be aggregated are formed in the system when flocculants are subsequently added. The beneficial effects are to improve the efficiency of tin transfer from the liquid phase to the solid phase, reduce the probability of tin remaining in the filtrate in a dissolved or colloidal state, and improve the stability and filtrate compliance rate of subsequent pressure filtration separation from the source.

[0117] S22. Based on the incoming conditions of the tin stripping waste liquid to be treated, a flocculant is added to the first mixing system for mixing treatment to obtain a second mixing system, wherein the flocculant includes PAM reagent;

[0118] The incoming material condition can be understood as the differences in turbidity, suspended solids state, and system viscosity of the tin stripping waste liquid across different batches. These differences directly affect the particle size distribution and agglomeration difficulty of the precipitated particles. PAM reagent, as a commonly used polymeric flocculant, can form a bridging effect between precipitated particles, causing fine particles to quickly aggregate into larger flocs. The purpose of this step is to adjust the dosage of flocculant to create a more easily press-filterable flocculated structure in the second mixed system, avoiding insufficient flocculation leading to a loose filter cake and turbid filtrate, or excessive flocculation leading to increased system viscosity and increased pressure filtration resistance. The beneficial effects are improved solid-liquid separation efficiency and filtrate clarity, making it easier for tin hydroxide precipitates to form a stable filter cake, thereby reducing tin entrainment and lowering the load on subsequent processes.

[0119] S23. The second mixture system is subjected to pressure filtration separation treatment to obtain tin hydroxide precipitate and initial pressure filtrate;

[0120] Filtration separation utilizes the filter medium and pressure difference of a filter press to separate solid-phase precipitation from liquid-phase filtrate. Tin hydroxide precipitate is the filter residue obtained from the filter press, and the initial filtrate is the liquid phase passing through the filter cloth. The purpose of this step is to effectively remove tin from the system in solid form and obtain a liquid phase that can enter the subsequent copper plating process. Its beneficial effects include achieving targeted tin recovery and reducing the metal load in the liquid phase. Simultaneously, by forming a filter cake, it further traps fine particles, improving the quality of the filtrate and the stability of subsequent treatments.

[0121] S24. The initial filtrate is tested to obtain test results, wherein the test results include pH value and tin content;

[0122] The H value is used to characterize whether the acidity or alkalinity of the filtrate is within the acceptable range for subsequent processes, while the tin content is used to characterize the thoroughness of tin immersion and pressure filtration separation. The purpose of this step is to confirm the treatment effects of S21 to S23 with quantifiable indicators, preventing unverified filtrate from directly entering the subsequent copper immersion stage, which could lead to deviations in copper immersion conditions or metal co-precipitation. The beneficial effect is the establishment of quality control points, enabling the entire process to have a traceable and adjustable process loop, thereby improving the controllability and consistency of the treatment process.

[0123] S25. Based on the test results, determine whether the initial filtrate meets the preset conditions, wherein the preset conditions include the pH value of the initial filtrate being less than 2.5 and the tin content of the initial filtrate being less than 6 mg / L;

[0124] These preset conditions essentially set a threshold for the filtrate to be used as feed for subsequent processes. A pH less than 2.5 ensures the system remains acidic, preventing abnormal hydrolysis or scaling upon entering subsequent stages. A tin content below 6 mg / L limits residual tin, preventing it from interfering with subsequent copper plating processes or causing product impurity accumulation. The purpose of this step is to solidify the treatment effect with a defined threshold as the judgment logic, ensuring stable output under varying incoming material fluctuations. The benefits include improved predictability of subsequent primary copper plating, reduced cross-process interference, and fewer rework or system fluctuations caused by substandard filtrate.

[0125] S26. If the conditions are met, the initial filtrate shall be used as the first filtrate.

[0126] This final step formally defines the qualified liquid phase as the first filtrate and sends it to the next stage of processing, forming a staged output in the process flow. Its purpose is to clarify the material state and flow boundaries, ensuring that the subsequent copper plating process in the second reaction tank is carried out based on qualified feed, thereby guaranteeing consistent input conditions for subsequent stages, improving the continuity and stability of the entire process, and establishing closed-loop control at the process level for tin precipitation recovery and filtrate compliance.

[0127] Preferably, step S22 includes:

[0128] S221. Obtain the incoming material information of the tin stripping waste liquid, including the added volume of the tin stripping waste liquid, the composition of the waste liquid, and the state of suspended solids;

[0129] Specifically, in this step, the added volume characterizes the scale of materials entering the reaction system in this batch, the waste liquid composition characterizes the differences in dissolved salts and metal ions in the tin stripping waste liquid, and the suspended solids state characterizes the system's turbidity, fine particle content, and dispersion. The purpose of this step is to solidify the key input conditions affecting flocculation before adding flocculant, so that subsequent addition is no longer based on empirical estimation but on adaptation to the characteristics of the incoming material. The beneficial effect is to improve the consistency of treatment across different batches of tin stripping waste liquid, avoid insufficient or excessive flocculation due to fluctuations in incoming material, and thus reduce the risks of fluctuations in the pressure filtration process and entrainment in the filtrate.

[0130] S222. Based on the incoming material conditions and the flocculant addition range, determine the flocculant addition parameters, wherein the addition parameters include at least the amount of flocculant added, and the flocculant addition range is 20~60kg;

[0131] Specifically, the flocculant dosage range can be understood as the empirically feasible interval applicable to this type of tin stripping waste liquid, used to constrain the upper and lower limits of the dosage and avoid process instability caused by significant deviations. When determining the dosage, the added volume can be used as the baseline, and the waste liquid composition and suspended solids state can be used as correction criteria, so that the final determined dosage can meet the particle agglomeration requirements without increasing the system viscosity or causing abnormal filter cake moisture content. The purpose of this step is to transform the flocculant dosage from a fixed amount or a single condition trigger to a comprehensive determination based on the incoming material conditions, making the dosage interpretable and repeatable. The beneficial effects are improved stability of flocculated flocs, reduced turbidity of the filtrate caused by fine particles penetrating the filter cloth, and improved filtration efficiency and precipitate recyclability.

[0132] S2221. Based on the incoming material situation, obtain characterization information for flocculation adaptation to obtain an incoming material feature set;

[0133] The incoming material feature set includes at least information on metal ion concentration ranges, suspended solids concentration ranges, particulate matter distribution, and the real-time pH value of the tin stripping waste liquid after pH adjustment. This step transforms the compositional fluctuations from abstract waste liquid components into characterizing quantities that can be used for dosing decisions. Metal ion concentration determines the number of precipitate nuclei that can be formed and the colloidal stability; suspended solids concentration and particulate matter distribution determine the ease of bridging and aggregation; and real-time pH is used to determine whether the system is within the suitable acidic window for PAM to function, thereby avoiding excessive differences in performance of the same amount of PAM under different incoming materials.

[0134] S2222. Based on the incoming material feature set, classify the flocculation difficulty of the tin stripping waste liquid to obtain the flocculation level;

[0135] Specifically, particulate matter distribution can be classified into levels based on factors such as high proportion of fine particles, concentrated distribution, or dispersed distribution; suspended solids concentration can be classified into low, medium, and high levels; and metal ion concentration can be classified into low, medium, and high levels. The contribution of this classification is that it transforms component fluctuations into stable decision inputs, so that the dosage is no longer a single-point estimate, but falls on an interpretable level mapping, which facilitates repeated implementation and process traceability.

[0136] S2223. Determine the basic addition range corresponding to the flocculation level based on the flocculation level and the flocculant addition range;

[0137] The basic dosage range is between 20 and 60 kg, and corresponds one-to-one with the flocculation level. This basic dosage range is equivalent to further refining the 20-60 kg range into several usable sub-ranges that match the characteristics of the incoming material. For example, low flocculation difficulty corresponds to the range close to the lower limit, and high flocculation difficulty corresponds to the range close to the upper limit. This mechanism avoids significant under-flocculation or over-flocculation when the composition fluctuates.

[0138] S2224. Based on the metal ion concentration range information and the suspended matter concentration range information, determine the initial addition amount within the basic addition range;

[0139] Specifically, the higher the metal ion concentration range or the higher the suspended solids concentration range, the closer the initial addition amount is to the upper boundary of the basic addition range. This step reflects the direct increase in bridging demand caused by the two main driving factors. High metal ion concentration usually corresponds to more precipitate nuclei and easier formation of fine particle clusters, while high suspended solids concentration means that more polymer chains are needed to complete effective bridging. Therefore, the initial addition amount is closer to the upper boundary, which is more in line with the flocculation principle.

[0140] S2225. Correct the initial addition amount based on the particulate matter distribution information to obtain the corrected addition amount;

[0141] Specifically, when the particulate matter distribution is characterized by a high proportion of fine particles or a dispersed distribution, the amount of corrective additive will be adjusted upwards; when the particulate matter distribution is characterized by coarse particles or a concentrated distribution, the amount of corrective additive will be adjusted downwards.

[0142] This calibration is more critical than the conventional approach because concentration alone often fails to reflect the differences in flocculation difficulty caused by different particle size distributions at the same concentration. When there are many fine particles, PAM requires more effective chain segments to achieve multi-point bridging, while when there are many coarse particles, a small amount of PAM can form compressible filter flocs. Calibration can directly correspond to filtration rate, filtrate clarity, and the stability of filter cake structure.

[0143] S2226. The corrective addition amount is adjusted according to the real-time pH value of the tin stripping waste liquid after pH adjustment to obtain the target addition amount;

[0144] Specifically, when the real-time pH value deviates from the median of the first preset pH range, the target dosage is adjusted upward to offset the impact of the acid window deviation on flocculation effectiveness. When the real-time pH value is close to the median, the target dosage is maintained or adjusted downward to avoid an increase in system viscosity leading to increased pressure filtration resistance.

[0145] The real-time pH used here is not for further feedback adjustment, but to determine whether the current batch of system is in an acidic state that is more conducive to PAM expansion and adsorption bridging. The further the pH deviates from the fit point, the greater the risk of flocs becoming loose or fine particles penetrating the filter cloth. Fit correction can improve the consistency of solid-liquid separation under different incoming material fluctuations.

[0146] In summary, through the processing steps S2221 to S2226, the fluctuations in incoming volume, metal ion concentration, suspended solids concentration, particulate matter distribution, and pH state of the tin stripping waste liquid can be transformed into a set of incoming material characteristics that can be used for flocculation control. Based on this, the flocculation difficulty classification, basic addition range limitation, and selection and adaptation correction of the addition amount within the range are completed, thereby determining the target addition amount that matches the characteristics of this batch of tin stripping waste liquid within the flocculant addition range.

[0147] This scheme eliminates the reliance on fixed empirical values ​​for flocculant addition. Instead, it dynamically matches the actual composition and physical properties of the tin stripping waste liquid, effectively improving the consistency of flocculation effects under different batches of incoming materials and reducing the risk of insufficient or excessive flocculation due to composition fluctuations.

[0148] Based on this, to further improve the applicability and stability of the determined dosage in the subsequent filter press stage, and to avoid situations such as turbid filtrate, decreased filtration rate, or unstable filter cake structure in individual batches of incoming material with special composition or abnormal particle state, in a preferred embodiment, after completing S2226, a filterability verification step based on bypass rapid flocculation is introduced to further verify and correct the target dosage, specifically including:

[0149] Obtain a bypass sample solution of a preset volume from the first mixing system, and add the PAM reagent corresponding to the target dosage to the bypass sample solution for rapid flocculation treatment;

[0150] Specifically, a bypass sample of a predetermined volume is obtained from the first mixing system, and PAM reagent corresponding to the target dosage is added to the bypass sample for rapid flocculation. The bypass sample can be understood as a representative small sample taken from the main system, with its volume predetermined and kept consistent to ensure comparability of verification results from different batches of incoming materials. The first mixing system is chosen as the sampling object because it has already undergone liquid alkali neutralization and formed fine precipitate nuclei and suspended particles for tin precipitation, which are the direct targets for subsequent pressure filtration separation. Bypass verification can more accurately reflect the response of this batch of material in the flocculation stage. Rapid flocculation treatment refers to adding PAM to the bypass sample in a predetermined manner without changing the main process or adding any reagents, followed by short-term mixing and settling, allowing the bridging and agglomeration effect of PAM to quickly manifest within the small system. The purpose of this step is to verify, using low-cost small-scale samples, whether the target dosage can form a floc structure conducive to filter press under current feed conditions. This reduces the risk of filtrate turbidity or filter cake failure caused by discovering incompatibility with flocculation only after direct addition to the main system. The PAM addition amount in the bypass sample is calculated based on the target dosage of the main system, ensuring that the bypass sample maintains a consistent dosage intensity with the main system. This guarantees that the bypass determination results reflect the flocculation performance of the main system under the same dosage conditions.

[0151] The bypass sample after rapid flocculation treatment was evaluated to obtain the filterability criterion.

[0152] Specifically, the filterability criterion is used to characterize whether the system possesses the a priori characteristics for successful filter pressing after treatment with the target dosage. Its content can be based on repeatable observation rules without relying on complex detection methods. For example, the clarity of the supernatant can reflect whether fine particles are effectively captured; the integrity and morphology of the flocs can reflect the sufficiency of flocculation bridging and the ability of the flocs to support the filter cake skeleton; and, if necessary, the floc settling characteristics can be combined to reflect the density and dewatering ease of the flocs. This criterion is introduced because the filter pressing effect is usually not determined by a single concentration parameter, but by the combined structure, density, and distribution of the aggregated particles. Establishing a filterability criterion directly in the bypass sample solution allows for a direct correlation between the flocculation dosage and the actual achievability of subsequent filter pressing.

[0153] Determine whether the filterability criterion meets the preset compressibility filterability condition;

[0154] Specifically, the preset filtration conditions can be understood as the minimum input requirements for subsequent filtration stages, ensuring that the filtrate clarity, filtration rate, and filter cake structure are within acceptable ranges. These conditions do not need to be quantitative indicators; thresholds can be used, such as ensuring the supernatant is clear or slightly turbid, the flocs are aggregated and not easily broken, and the flocs do not exhibit obvious viscosity or stringiness. The significance of setting this judgment step is to create a quality gate at the process node, so that the flocculant dosage is no longer solely estimated based on the characteristics of the incoming material, but rather adds a pre-confirmation directly related to filtration performance, thereby improving the stability and repeatability of the process under fluctuations in incoming material.

[0155] If the filterability criterion does not meet the preset compressibility condition, the target dosage is corrected within the flocculant dosage range to obtain the corrected dosage.

[0156] Specifically, when the filterability criterion does not meet the preset pressure-filterable conditions, the target dosage is adjusted within the flocculant dosage range to obtain the corrected dosage. This adjustment is a limited adjustment within the range of 20-60 kg, and its logic is to provide targeted compensation for the unmet criteria, rather than blindly adding chemicals. For example, if the bypass sample liquid shows turbid supernatant, difficulty in fine particle aggregation, and loose and brittle flocs, it usually means insufficient bridging or insufficient effective collision probability. In this case, the dosage can be adjusted upward to increase the effective bridging opportunity, promoting more complete capture of fine particles and the formation of more stable flocs. If the bypass sample liquid shows flocs forming but the system is obviously viscous, with stringing or floc surface adhesion leading to mutual encapsulation of aggregates, it may mean that excessive PAM has caused residual free polymer chains, increasing system viscosity and pressure-filtering resistance. In this case, the dosage can be adjusted downward to reduce viscosity and the risk of filter cloth clogging. By limiting the correction actions to the dosage range and triggering them based on the filterability criterion, the uncertainty brought about by extreme material combinations can be effectively mitigated without introducing new reagents or changing the main process route.

[0157] The corrected dosage is used as the amount of flocculant to be added, and the addition parameters are output.

[0158] Specifically, the results after bypass verification and correction are solidified as the final execution parameters for this batch, providing a clear and traceable basis for the flocculation dosing of the main system. Compared with directly outputting the target dosing amount, using the corrected dosing amount can more reliably match the subsequent filtration requirements, improve the clarity of the filtrate and the stability of the filter cake structure, and reduce the probability of filtration rate fluctuations, rework, or increased load on subsequent processes due to incompatible flocculation. It also avoids operational instability caused by increased system viscosity and filtration resistance due to excessive PAM. Overall, this bypass verification mechanism is equivalent to introducing a pre-confirmation node directly related to the performance of the filtration end in the process of determining the flocculant dosing amount, making the dosing strategy under composition fluctuations more feasible and consistent, thereby better supporting the stepwise, targeted removal and stable recovery goals emphasized in this invention. S223, Add flocculant to the first mixing system according to the dosing parameters and perform mixing treatment to obtain the second mixing system.

[0159] After adding the flocculant, the system is thoroughly mixed to ensure sufficient contact and bridging aggregation of the flocculant with the already formed fine tin hydroxide particles, resulting in larger floc structures that are stably distributed throughout the system. This step aims to ensure the necessary contact and dispersion conditions for the flocculant to function effectively, avoiding uneven flocculation due to localized addition or insufficient mixing, which could negatively impact the filtration rate and filtrate quality in subsequent pressure filtration. The beneficial effects include making the second mixed system more suitable for pressure filtration to form a dense filter cake, improving solid-liquid separation, reducing the probability of tin being carried away with the filtrate, and ensuring the production of a first filtrate that meets the preset conditions.

[0160] Preferably, step S3 includes:

[0161] S31. The first filtrate that meets the preset conditions is introduced into the second reaction tank, and the pH of the second reaction tank is monitored to obtain the second pH detection result;

[0162] The first filtrate refers to the liquid material that has undergone tin immersion and filtration and meets preset conditions. As the feed for the primary copper immersion stage, it reduces the interference of tin on the copper immersion process, making the copper immersion reaction more stable. The second reaction vessel is used to carry this feed and form the primary copper immersion reaction system. pH monitoring is used to obtain the system's acidity and alkalinity status in real time. The second pH detection result is used to characterize whether the current system is within the condition range suitable for primary copper immersion. The purpose of this step is to lock in the system's pH status before adding chemicals, avoiding blind alkali addition that could lead to over-adjustment or repeated corrections. This improves the targeted nature of alkali addition adjustments, making subsequent copper immersion conditions more easily stabilized within the target range, thereby reducing the risk of copper immersion fluctuations and filtration instability.

[0163] S32. Based on the second pH detection result, add liquid alkali into the second reaction vessel to adjust the pH in the second reaction vessel to a second preset pH range, wherein the second preset pH range is 6.0~10.0;

[0164] Liquid alkali acts as a regulator, neutralizing the acidity of the system and raising the pH to a suitable range, providing conditions for copper to precipitate as hydroxide. A second preset pH range defines the operating window for primary copper precipitation, avoiding both excessively low pH (leading to incomplete precipitation) and excessively high pH (causing unstable precipitate morphology or adverse effects on subsequent processes). The purpose of this step is to establish primary copper precipitation on a controllable pH basis through alkali adjustment driven by monitoring results. The beneficial effects include improving the stability of copper's transformation from the liquid to the solid phase, making the precipitate formed during primary precipitation easier to separate by pressure filtration, and reducing the load of residual copper entering the subsequent secondary copper precipitation stage.

[0165] S33. When the pH is within the second preset pH range, activated carbon is added to the second reaction vessel to perform a copper plating process to obtain a copper plating product.

[0166] In this step, activated carbon can be understood as a functional medium to assist in copper precipitation. Its addition promotes copper removal and improves precipitation formation and aggregation, making it easier for copper to transfer from the liquid phase to the solid phase for precipitation. The purpose of this step is to introduce activated carbon only after the pH conditions are met, ensuring that it functions effectively under the target acid-base environment and avoiding low copper precipitation efficiency or unstable precipitation due to insufficient pH. The beneficial effects include improved primary copper removal efficiency and resistance to fluctuations, making the formed solid phase more easily form a pressure-filterable structure, thereby improving the efficiency of subsequent solid-liquid separation and reducing the risk of filtrate entrainment.

[0167] S34. The primary copper precipitation product is separated by pressure filtration to obtain copper hydroxide precipitate and primary copper precipitation filtrate.

[0168] The primary copper precipitation product refers to the reaction system in the second reaction tank after pH adjustment with alkali and treatment with activated carbon, which contains the target solid precipitate and liquid phase. Pressure filtration is used to separate the solid copper hydroxide precipitate from the system, while simultaneously obtaining the liquid primary copper precipitation filtrate as feed for the subsequent secondary copper precipitation stage. The purpose of this step is to achieve phased copper recovery and continuous flow of liquid materials, clearly defining the output boundary of the primary copper precipitation stage. The beneficial effects include obtaining recyclable copper hydroxide precipitate and reducing the copper content in the liquid phase through solid-liquid separation, creating cleaner feed conditions for the subsequent deep removal and sodium salt recovery in secondary copper precipitation, and improving the resource utilization level and operational stability of the entire process.

[0169] Preferably, step S4 includes:

[0170] S41. The primary copper plating filtrate is introduced into the third reaction vessel;

[0171] The primary copper precipitation filtrate refers to the liquid phase obtained after pressure filtration in the primary copper precipitation stage. Its copper content has been reduced, but residual copper ions may still be present. The system also contains sodium salt components that need to be recovered later. The third reaction vessel is used to receive this liquid phase and create the reaction environment for secondary copper precipitation, so that the secondary copper precipitation can be completed in an independent stage and form a clear boundary with the preceding and following stages.

[0172] S42. Monitor the pH of the system inside the third reaction vessel to obtain the third pH detection result;

[0173] The third pH test result is used to characterize the current acidity / alkalinity of the system and serves as the basis for subsequent alkali adjustment and copper precipitation reagent addition. Secondary copper precipitation is typically pH-sensitive; pH deviations can lead to incomplete copper precipitation or unstable precipitate morphology, thus affecting the pressure filtration separation effect and the purity of the sodium salt stock solution. The purpose of this step is to obtain the system state before adding chemicals, achieving process control rather than post-treatment correction. The beneficial effects include improving the timeliness and accuracy of secondary copper precipitation condition control, and reducing the decrease in copper precipitation efficiency and fluctuations in filtrate parameters caused by pH fluctuations.

[0174] S43. Based on the third pH detection result, liquid alkali is added to the third reaction vessel to adjust the pH of the system in the third reaction vessel to a third preset pH range, wherein the third preset pH range is 7.0~8.0;

[0175] Liquid alkali is used to neutralize and adjust the filtrate from the primary copper precipitation process, bringing the system into a pH window suitable for the secondary copper precipitation reaction. The third preset pH range defines the reaction conditions, which is beneficial for the stable occurrence of the subsequent sulfide copper precipitation reaction and helps control the precipitation rate and particle morphology, avoiding insufficient copper precipitation due to excessively low pH or excessively high pH resulting in overly fine precipitates that are difficult to filter. The purpose of this step is to establish controllable reaction conditions for the secondary copper precipitation, allowing the copper precipitation reagent to function effectively under stable conditions. The beneficial effects include improving the thoroughness of residual copper removal and enhancing the separability of the precipitate, thus ensuring a cleaner sodium salt stock solution.

[0176] S44. Add copper plating reagent to the third reaction vessel for a second copper plating treatment, wherein the copper plating reagent includes sodium sulfide.

[0177] The copper precipitation reagent is used to convert residual copper in the system from the liquid phase to a solid precipitate. Sodium sulfide, as the copper precipitation reagent, reacts with copper ions to form copper sulfide precipitate, thereby achieving deep removal of copper. The purpose of this step is to add the copper precipitation reagent after pH adjustment, ensuring the reaction proceeds within the preset pH range, reducing ineffective consumption, and enhancing the selectivity and stability of the copper precipitation. The beneficial effects include further enriching residual copper into copper sulfide precipitate, reducing the accumulation of impurities caused by copper entering the subsequent sodium salt recovery stage, and improving the purity of sodium nitrate product and the stability of the crystallization process.

[0178] S45. The system after the secondary copper precipitation treatment is sent to a filter press for pressure filtration and separation to obtain copper sulfide precipitate and sodium salt stock solution.

[0179] The system following the secondary copper plating treatment comprises the target solid-phase copper sulfide precipitate and a liquid-phase sodium salt system. Pressure filtration is used to achieve rapid solid-liquid separation, allowing the copper sulfide precipitate to be retained and collected as a solid-phase recovery product, while the liquid phase serves as the sodium salt raw solution for subsequent distillation and centrifugal recovery. The purpose of this step is to solidify the treatment effect of the secondary copper plating into a flowable material output, forming a clear outlet for the secondary copper plating process. The beneficial effects include obtaining recyclable copper sulfide precipitate while significantly reducing the copper impurity content in the sodium salt raw solution, making the sodium salt raw solution more suitable for subsequent sodium nitrate recovery, thereby improving the resource utilization level and operational stability of the entire tin stripping wastewater treatment process.

[0180] Preferably, step S5 includes:

[0181] S51. The sodium salt stock solution is introduced into the sodium salt evaporation unit and distilled according to a preset number of distillation cycles to obtain sodium nitrate mother liquor.

[0182] The sodium salt evaporation unit is used to distill and concentrate the liquid phase. A preset number of distillation cycles limits the number of distillation operations, allowing the process to achieve a relatively stable concentration effect under varying feed concentrations by adjusting the number of distillations. Sodium nitrate mother liquor refers to the mother liquor enriched with sodium nitrate after distillation, providing the material basis for further purification and solid-liquid separation. The purpose of this step is to transform the sodium salt system from a dilute solution state into a more suitable enriched mother liquor for subsequent separation, reducing the processing load on subsequent stages. The beneficial effect is improved controllability and adaptability of the sodium nitrate recovery section, making it easier to obtain stable mother liquor quality from different batches of sodium salt stock solution within the same process framework, laying the foundation for subsequent secondary distillation and centrifugation to obtain high-purity products.

[0183] S52. The sodium nitrate mother liquor is subjected to a second distillation to obtain a second-distilled material;

[0184] The second distillation process can be understood as a further concentration and purification of the mother liquor, increasing the enrichment of sodium nitrate and preparing the material for subsequent formation of a separable solid phase or high-salt content. The purpose of this step is to enhance the material's state before centrifugation, making the second-distilled material more suitable for the centrifugation process window and reducing product purity fluctuations caused by entrained liquid or impurities during centrifugation. The beneficial effects include improved separation efficiency and stability in subsequent centrifugation, making it easier for the final sodium nitrate product to meet predetermined purity standards, while reducing residual liquid and easing the burden on end-of-pipe treatment.

[0185] S53. The secondary distilled material is fed into a centrifuge for centrifugal separation, and the sodium nitrate product obtained by centrifugal separation is collected, wherein the mass percentage of sodium nitrate in the sodium nitrate product is not less than 93 wt%.

[0186] Centrifugal separation is a process that uses centrifugal force to separate the solid and liquid phases. It is suitable for rapidly separating the sodium nitrate solid phase formed after secondary distillation from the residual mother liquor. A sodium nitrate mass percentage of at least 93 wt% is used to define the purity level of the resulting product, indicating that the product is primarily composed of sodium nitrate rather than mixed sodium salts or high-water-content materials. The purpose of this step is to obtain directly usable or further refined sodium nitrate products through physical separation, and to clearly separate the residual liquid from the product for subsequent processing or reuse. The beneficial effects include realizing the resource-based output of the sodium salt system, increasing the overall resource recovery value of tin stripping waste liquid, ensuring product quality by setting a purity threshold, reducing the dependence of the sodium salt recovery section on end-of-pipe physicochemical treatment, and improving the environmental friendliness and economy of the entire process.

[0187] Preferably, the preset number of distillations is 1 or 2.

[0188] This setup aims to balance process adaptability and energy consumption control under different feed conditions while ensuring sodium nitrate recovery efficiency. When the initial sodium nitrate concentration and impurity content in the sodium salt stock solution are high, a single distillation can yield a sodium nitrate mother liquor that meets the requirements for subsequent processing, thereby shortening the processing flow and reducing evaporation energy consumption. When the sodium salt stock solution concentration is low or the system fluctuates significantly, a second distillation can further enhance the enrichment of sodium nitrate, creating more stable material conditions for subsequent secondary distillation and centrifugal separation. By limiting the number of distillations to one or two, this step allows for flexible adjustment while ensuring product purity requirements, facilitating a balance between processing efficiency and operating costs under different operating conditions.

[0189] Preferably, after feeding the secondary distilled material into a centrifuge for centrifugal separation and collecting the sodium nitrate product obtained by centrifugation, the method further includes:

[0190] S54. Collect the residual liquid produced during distillation and / or centrifugation;

[0191] The residual liquid refers to the liquid phase that was not converted into sodium nitrate product during the distillation, concentration, secondary distillation, and centrifugation processes. It may include residual mother liquor after distillation and centrifugal mother liquor after centrifugation. The purpose of this step is to centrally collect the liquid phase other than the recovered product, preventing the residual liquid from being dispersed or mixed into upstream processes, causing system fluctuations. Its beneficial effects include clearly defining the liquid phase boundary of the sodium salt recovery section, facilitating centralized management and subsequent treatment of the residual liquid, thereby reducing environmental emission risks and improving the standardization of process operation.

[0192] S55. The remaining liquid is transported to the physicochemical workshop, where it undergoes physicochemical treatment.

[0193] Physicochemical treatment refers to the use of physical or chemical methods to treat waste liquid to reduce pollutant concentrations and improve water quality, making it meet subsequent disposal requirements. This step emphasizes the process path of centralized treatment in the physicochemical workshop, rather than specifying particular treatment methods. The purpose of this step is to provide end-of-pipe treatment for residual liquid that may still contain some salt or trace pollutants, creating a closed loop in the entire tin stripping waste liquid treatment process and preventing the generation of high-volume, difficult-to-dispose-of waste liquid after resource recovery. Its beneficial effects include reducing system discharge pressure, minimizing potential environmental impact, and ensuring the process is both engineering-feasible and environmentally compliant.

[0194] S56. After completing the physical and chemical treatment, the treated liquid is discharged or reused.

[0195] Discharge or reuse defines the output method after physicochemical treatment. Reuse can be understood as reusing the treated liquid as production water or auxiliary water, while discharge refers to entering an external discharge path after meeting the corresponding discharge requirements. The purpose of this step is to provide a clear destination for the physicochemically treated liquid, so that the end-of-pipe treatment results can be linked to actual production management. Its beneficial effects are to further reduce the final discharge of waste liquid, improve water resource utilization efficiency, and enhance the system's ability to adapt to different plant operation modes through selectable discharge or reuse paths, making the whole method more comprehensive in terms of environmental protection and economy.

[0196] Example 2

[0197] This invention also provides a tin stripping waste liquid treatment system, characterized in that the system includes: a first reaction tank, a tin stripping water filter press, a second reaction tank, a primary copper plating filter press, a third reaction tank, a secondary copper plating filter press, a sodium salt evaporation unit, a centrifuge, and a controller; wherein, the first reaction tank is sequentially connected to the tin stripping water filter press, the second reaction tank, the primary copper plating filter press, the third reaction tank, the secondary copper plating filter press, the sodium salt evaporation unit, and the centrifuge; the physicochemical treatment unit is connected to the sodium salt evaporation unit and / or the centrifuge; and the controller is signal-connected to the first reaction tank, the tin stripping water filter press, the second reaction tank, the primary copper plating filter press, the third reaction tank, the secondary copper plating filter press, the sodium salt evaporation unit, and the centrifuge, respectively, for controlling the system to execute the tin stripping waste liquid treatment method for component qualitative recovery described in Embodiment 1.

[0198] In this system, the first reaction tank serves as the front-end processing unit, receiving and treating the tin stripping wastewater. During the wastewater introduction process, aeration and pH adjustment are performed to provide a stable and uniform initial system for the subsequent tin deposition reaction. The tin stripping water filter press is connected to the first reaction tank and is used to perform solid-liquid separation on the system treated with liquid alkali and flocculant, thereby obtaining tin hydroxide precipitate and the first filter liquid, achieving targeted tin recovery.

[0199] The second reaction tank is connected to the tin stripping water filter press, used to receive the first filtrate that meets preset conditions, and to complete the primary copper precipitation treatment with activated carbon under controlled pH conditions. The primary copper precipitation filter press is connected to the second reaction tank, used to perform pressure filtration separation on the system after the primary copper precipitation, obtaining copper hydroxide precipitate and the primary copper precipitation filtrate, thereby achieving staged removal and recovery of copper. The third reaction tank is connected to the primary copper precipitation filter press, used to receive the primary copper precipitation filtrate, and to complete the secondary copper precipitation treatment by adjusting the pH and adding copper precipitation reagent. The secondary copper precipitation filter press is connected to the third reaction tank, used to perform pressure filtration separation on the system after the secondary copper precipitation, obtaining copper sulfide precipitate and sodium salt stock solution, achieving further deep removal of copper.

[0200] The sodium salt evaporation unit is connected to a secondary copper-plating filter press for distilling the sodium salt stock solution to obtain sodium nitrate mother liquor. A centrifuge is connected to the sodium salt evaporation unit for centrifuging the material after secondary distillation to obtain sodium nitrate product, thus achieving resource recovery of the sodium salt system. Simultaneously, a physicochemical treatment unit is connected to the sodium salt evaporation unit and / or the centrifuge for centralized physicochemical treatment of the residual liquid generated during distillation and centrifugation, achieving end-of-pipe volume reduction and harmless disposal.

[0201] The controller is connected to the first reaction tank, the tin stripping water filter press, the second reaction tank, the primary copper plating filter press, the third reaction tank, the secondary copper plating filter press, the sodium salt evaporation unit, and the centrifuge equipment. It coordinates and controls the operating status, process sequence, and key parameters of each processing unit, ensuring that each unit operates sequentially according to the tin stripping waste liquid treatment method described in Example 1, which involves qualitative recovery of components. Through unified scheduling by the controller, orderly connections between different stages can be achieved, avoiding material cross-flow or process condition mismatch.

[0202] Through the above-described system configuration and connection method, the tin stripping waste liquid treatment system provided in this embodiment of the invention can stably and continuously complete the stepwise directional recovery of tin, copper and sodium salts in the tin stripping waste liquid, and transform the process flow in the method embodiment into an engineering-operable system structure, which is conducive to improving the automation level, operational stability and resource utilization level of the treatment process, and is suitable for tin stripping waste liquid treatment applications in actual industrial scenarios.

[0203] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0204] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0205] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0206] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0207] It should also be noted that the exemplary embodiments mentioned in this invention describe methods or systems based on a series of steps or apparatus. However, this invention is not limited to the order of the steps described above; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0208] The above description is merely a specific embodiment of the present invention. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for treating tin stripping waste liquid with qualitative component recovery, characterized in that, The method includes: The process involves introducing the tin stripping waste liquid into a first reaction tank while simultaneously aerating it, controlling the pH within the first reaction tank to be within a first preset pH range. This includes: conveying a preset volume of the tin stripping waste liquid to the first reaction tank using aeration gas while simultaneously aerating the waste liquid; monitoring the pH of the system within the first reaction tank during the introduction of the tin stripping waste liquid into the first reaction tank to obtain a first pH detection result; adjusting the pH within the first reaction tank based on the first pH detection result and the first preset pH range, wherein the first preset pH range is 1.0~2.0; and stopping aeration once the tin stripping waste liquid has completely entered the first reaction tank. After the aeration reaction is completed, liquid alkali and flocculant are added for mixing. The mixed system is then fed into a tin stripping water filter press for filtration to obtain tin hydroxide precipitate and a first filtrate. The process includes: adding liquid alkali to the system after the aeration reaction for neutralization to obtain a first mixed system for tin precipitation; adding flocculant to the first mixed system according to the incoming tin stripping wastewater to obtain a second mixed system, wherein the flocculant includes PAM reagent; filtration separation of the second mixed system to obtain tin hydroxide precipitate and an initial filtrate; testing the initial filtrate to obtain test results, including pH value and tin content; determining whether the initial filtrate meets preset conditions, including a pH value less than 2.5 and a tin content less than 6 mg / L; if these conditions are met, the initial filtrate is used as the first filtrate. The first filtrate that meets the preset conditions is introduced into the second reaction tank, and liquid alkali and activated carbon are added to it for neutralization and primary copper precipitation treatment to obtain copper hydroxide precipitate and collect the primary copper precipitation filtrate. The primary copper precipitation filtrate is introduced into the third reaction tank, and liquid alkali and copper precipitation reagent are added to it in sequence for secondary copper precipitation treatment. After pressure filtration, copper sulfide precipitate and sodium salt stock solution are obtained. The sodium salt stock solution was distilled and centrifuged to obtain sodium nitrate product.

2. The method for treating tin stripping waste liquid by qualitative recovery of components according to claim 1, characterized in that, The process involves adding a flocculant to the first mixing system based on the incoming tin stripping waste liquid to obtain a second mixing system, comprising: The incoming material information of the tin stripping waste liquid is obtained, including the added volume of the tin stripping waste liquid, the composition of the waste liquid, and the state of suspended solids; Based on the incoming material conditions and the flocculant addition range, the flocculant addition parameters are determined. The addition parameters include at least the amount of flocculant added, and the flocculant addition range is 20~60kg. According to the dosage parameters, flocculant is added to the first mixing system and mixed to obtain the second mixing system.

3. The method for treating tin stripping waste liquid by qualitative recovery of components according to claim 1, characterized in that, The process of introducing the first filtrate that meets the preset conditions into the second reaction tank, and adding liquid alkali and activated carbon to neutralize and perform a primary copper precipitation treatment to obtain copper hydroxide precipitate and collect the primary copper precipitation filtrate includes: The first filtrate that meets the preset conditions is introduced into the second reaction tank, and the pH of the second reaction tank is monitored to obtain the second pH detection result; Based on the second pH detection result, liquid alkali is added to the second reaction vessel to adjust the pH in the second reaction vessel to a second preset pH range, wherein the second preset pH range is 6.0~10.0; When the pH is within the second preset pH range, activated carbon is added to the second reaction vessel to perform a first copper precipitation treatment, and a first copper precipitation product is obtained. The primary copper precipitation product was separated by pressure filtration to obtain copper hydroxide precipitate and primary copper precipitation filtrate.

4. The method for treating tin stripping waste liquid by qualitative recovery of components according to claim 1, characterized in that, The process involves introducing the primary copper precipitation filtrate into a third reaction tank, and then sequentially adding liquid alkali and copper precipitation reagent for a secondary copper precipitation treatment, followed by pressure filtration to obtain copper sulfide precipitate and sodium salt stock solution, comprising: The primary copper plating filtrate is then introduced into the third reaction vessel; The pH of the system inside the third reaction vessel was monitored to obtain the third pH detection result; Based on the third pH detection result, liquid alkali is added to the third reaction vessel to adjust the pH of the system in the third reaction vessel to a third preset pH range, wherein the third preset pH range is 7.0~8.0; A copper plating reagent is added to the third reaction vessel for a second copper plating treatment, wherein the copper plating reagent includes sodium sulfide. The system after the secondary copper precipitation treatment was sent to a filter press for pressure filtration and separation to obtain copper sulfide precipitate and sodium salt stock solution.

5. The method for treating tin stripping waste liquid by qualitative recovery of components according to claim 1, characterized in that, The process of distilling and centrifuging the sodium salt stock solution to obtain sodium nitrate product includes: The sodium salt stock solution is introduced into the sodium salt evaporation unit and distilled according to a preset number of distillation cycles to obtain sodium nitrate mother liquor. The sodium nitrate mother liquor was subjected to a second distillation to obtain a double-distilled product. The secondary distilled material is fed into a centrifuge for centrifugal separation, and the sodium nitrate product obtained by centrifugation is collected, wherein the mass percentage of sodium nitrate in the sodium nitrate product is not less than 93 wt%.

6. The method for treating tin stripping waste liquid by qualitative recovery of components according to claim 5, characterized in that, After feeding the secondary distilled material into a centrifuge for centrifugal separation and collecting the sodium nitrate product obtained by centrifugation, the method further includes: Collect the residual liquid produced during distillation and / or centrifugation; The remaining liquid is transported to the physicochemical workshop, where it undergoes physicochemical treatment. After the physical and chemical treatment is completed, the treated liquid is either discharged or reused.

7. A tin stripping waste liquid treatment system, characterized in that, The system comprises: a first reaction tank, a tin stripping water filter press, a second reaction tank, a primary copper plating filter press, a third reaction tank, a secondary copper plating filter press, a sodium salt evaporation unit, a centrifuge, a physicochemical treatment unit, and a controller; wherein, the first reaction tank is sequentially connected to the tin stripping water filter press, the second reaction tank, the primary copper plating filter press, the third reaction tank, the secondary copper plating filter press, the sodium salt evaporation unit, and the centrifuge; the physicochemical treatment unit is connected to the sodium salt evaporation unit and / or the centrifuge; and the controller is signal-connected to the first reaction tank, the tin stripping water filter press, the second reaction tank, the primary copper plating filter press, the third reaction tank, the secondary copper plating filter press, the sodium salt evaporation unit, and the centrifuge, and is used to control the system to perform the tin stripping waste liquid treatment method for qualitative recovery of components as described in any one of claims 1 to 6.

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