Etching waste liquid treatment method and system based on by-product recycling

Abstract

This invention discloses a method and system for treating etching waste liquid based on by-product recycling, relating to the field of industrial waste liquid treatment technology. The method sequentially pretreats, neutralizes, converts to ammonia, pulps, acidifies, and thermally filters the etching waste liquid. Addressing the characteristics of etching waste liquid—numerous suspended impurities, insoluble impurities, complex composition, and large system fluctuations—it progressively removes impurities, converts copper components, and regulates the system before crystallization. This allows for more complete and stable separation and recovery of the effective copper components in the etching waste liquid. This not only reduces the adverse effects of impurities in the waste liquid on the subsequent crystallization process and improves the continuity and stability of subsequent treatment processes, but also transforms non-crystalline powder with acceptable purity but unqualified morphology into a usable seed source for the crystallization process, reducing waste generation, improving raw material utilization efficiency, and alleviating waste disposal pressure.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment technology, and in particular to a method and system for treating etching wastewater based on the reuse of by-products. Background Technology

[0002] In electronic manufacturing, printed circuit board processing, electroplating, and related chemical production processes, etching processes generate large amounts of copper-containing etching wastewater. This type of wastewater typically contains high concentrations of copper ions, along with acids, alkalis, complexing agents, and other impurities, making it complex in composition, difficult to treat, and posing a high environmental risk. Improper disposal of this etching wastewater can easily lead to heavy metal pollution and aquatic environmental burden, as well as the waste of recoverable copper resources. Therefore, how to effectively treat etching wastewater and simultaneously recover and reuse its copper resources has become a crucial technical issue of concern in this field.

[0003] In existing technologies, copper-containing etching wastewater typically involves separating, converting, and recovering the copper components to reduce the risk of wastewater discharge and achieve resource utilization. In some treatment processes, the recovered copper components can be further processed into usable products such as copper sulfate, thereby increasing the economic value of wastewater treatment. While these methods can achieve a certain degree of reduction, harmlessness, and resource recovery of etching wastewater, in actual operation, they are still easily affected by factors such as fluctuations in the source of the wastewater, differences in impurity composition, equipment operating status, and the precision of process parameter control, resulting in less than ideal overall treatment effects and resource recovery efficiency.

[0004] Especially in the subsequent separation, crystallization, centrifugation, and drying stages after etching wastewater treatment, a certain proportion of process byproducts are often generated, such as non-crystalline powders or other intermediate products that are difficult to use directly as qualified products. These substances usually still contain a high proportion of copper components and have reuse value. However, due to their fine particle size, irregular morphology, poor stability, or inconvenience for direct reuse in existing processes, they are often sold, downgraded, or even treated as waste in current production. This not only increases treatment costs but also means that the copper resources that could have been recycled in the etching wastewater are not fully utilized, thus affecting the overall recycling rate of the etching wastewater treatment process.

[0005] Furthermore, existing etching wastewater treatment processes typically focus more on the recovery and conversion of copper ions in the main process during the recycling stage. They lack a coordinated reuse mechanism for byproducts, scrap materials, or copper-containing substances that have not yet formed stable product forms generated during the treatment process. This results in two problems: firstly, while the wastewater treatment system achieves some copper resource recovery, overall resource utilization remains insufficient; secondly, byproduct disposal adds extra material management and environmental burdens, hindering the improvement of the overall efficiency of etching wastewater treatment processes.

[0006] Therefore, how to further improve the recycling level of various copper-containing products, especially process by-products, in the existing etching waste liquid treatment process, thereby improving the overall resource utilization rate and economic efficiency of etching waste liquid treatment, remains a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, embodiments of the present invention provide a method and system for treating etching waste liquid based on the reuse of by-products, in order to solve the problem of low recycling and conversion rate of etching waste liquid in the prior art.

[0008] In a first aspect, embodiments of the present invention provide a method for treating etching waste liquid based on byproduct recycling, the method comprising: The etching waste liquid is pretreated to remove suspended and insoluble impurities. The pretreated etching waste liquid is subjected to composition regulation treatment to obtain the copper sulfate acidified filtrate that meets the crystallization requirements. The composition regulation treatment includes neutralization treatment, ammonia conversion treatment, pulping treatment, acidification treatment and thermal filtration treatment. Based on the copper sulfate acidification filtrate, copper sulfate finished product and copper sulfate non-crystalline powder are obtained, and a seed suspension is obtained based on the copper sulfate non-crystalline powder; The seed crystal suspension is added to the subsequent etching waste liquid composition control process and participates in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products.

[0009] Preferably, the component regulation treatment of the pretreated etching waste liquid to obtain the copper sulfate acidified filtrate that meets the crystallization requirements includes neutralization treatment, ammonia conversion treatment, pulping treatment, acidification treatment, and thermal filtration treatment. The pretreated etching waste liquid is neutralized to adjust its pH. An ammonia-containing reagent was added to the neutralized etching waste liquid to perform ammonia conversion treatment, so that the copper ions in the etching waste liquid were converted into an ammonia complex state. The etching waste liquid after ammonia conversion is pulped to promote the full dispersion of impurity particles in the etching waste liquid and form a separable solid phase. The etching waste liquid after pulping is acidified to convert ammonia-complexed copper ions into copper sulfate. The etching waste liquid after acidification is subjected to thermal filtration to separate solid phase impurities and obtain the copper sulfate acidified filtrate that meets the crystallization requirements.

[0010] Preferably, the step of obtaining copper sulfate finished product and copper sulfate amorphous powder based on the copper sulfate acidification filtrate, and obtaining seed crystal suspension based on the copper sulfate amorphous powder, includes: The copper sulfate acidified filtrate is subjected to crystallization treatment to form a slurry containing copper sulfate crystals and copper sulfate mother liquor; The slurry is centrifuged to obtain copper sulfate crystals and copper sulfate mother liquor. The copper sulfate crystals are then dried to obtain the finished copper sulfate product. Obtain amorphous copper sulfate powder generated during centrifugation and / or drying, and add the amorphous copper sulfate powder to the copper sulfate mother liquor after seed pretreatment and stirring to form a uniform seed suspension.

[0011] Preferably, the purity of the copper sulfate acidified filtrate that meets the crystallization requirements is greater than or equal to 99.5%, and the Baume degree is 40±3°Bé.

[0012] Preferably, the purity of the copper sulfate amorphous powder is greater than or equal to 99.5%, and the particle size is less than or equal to 100 μm.

[0013] Preferably, the step of obtaining amorphous copper sulfate powder generated during centrifugation and / or drying, and then adding the amorphous copper sulfate powder to the copper sulfate mother liquor after seed crystal pretreatment and stirring to form a uniform seed crystal suspension includes: Collect the non-crystalline copper sulfate powder produced during the centrifugation and / or drying process; The amorphous copper sulfate powder is transported to the seed crystal pretreatment tank via a closed negative pressure conveying device. The copper sulfate amorphous powder is subjected to seed pretreatment in the seed pretreatment tank. The seed pretreatment includes particle size control and dispersion treatment of the copper sulfate amorphous powder. The copper sulfate mother liquor is added to the copper sulfate amorphous powder that has undergone seed crystal pretreatment, and the mixture is stirred to form a uniform seed crystal suspension.

[0014] Preferably, the step of adding the copper sulfate mother liquor to the amorphous copper sulfate powder after seed crystal pretreatment and stirring to form a uniform seed crystal suspension includes: Establish a circulation path for returning the copper sulfate mother liquor generated during the centrifugal separation of crystal slurry to the seed crystal pretreatment tank; The total amount of copper sulfate mother liquor to be added is determined based on the amount of non-crystalline copper sulfate powder after seed crystal pretreatment. Based on the total amount added and the preset stage allocation rules, the stage addition amount for each mother liquor addition stage is determined, wherein the mother liquor addition stage includes at least a wetting stage and a dispersion stage. The copper sulfate mother liquor is added to the copper sulfate amorphous powder that has undergone seed crystal pretreatment according to the stage addition amounts corresponding to the wetting stage and the dispersion stage, and the mixture is stirred accordingly to obtain the seed crystal suspension.

[0015] The step of adding the copper sulfate mother liquor to the copper sulfate amorphous powder pretreated with seed crystals according to the stage corresponding to the wetting stage and the dispersion stage, and then stirring accordingly to obtain the seed crystal suspension includes: Add the copper sulfate mother liquor refluxed through the circulation path to the copper sulfate amorphous powder after seed crystal pretreatment according to the stage addition amount corresponding to the wetting stage, and stir to change the copper sulfate amorphous powder from a dry powder state to a wet state. After the wetting stage is completed, the copper sulfate mother liquor is added according to the stage addition amount corresponding to the dispersion stage, and the mixture is stirred to obtain the initial seed crystal suspension. The initial seed crystal suspension was tested to obtain test results, wherein the test results included the Baumé degree of the liquid phase and the dispersion state of the non-crystalline copper sulfate powder; When the test results do not meet the preset conditions, the amount of mother liquor added in the matching stage is determined based on the test results; According to the amount of mother liquor added in the matching stage, the copper sulfate mother liquor is added and stirred until the liquid phase Baume degree of the initial seed suspension reaches the preset range that matches the subsequent acidification reaction system, and the non-crystalline copper sulfate powder forms a uniform suspension state, thus obtaining the seed suspension.

[0016] Preferably, the step of adding the seed crystal suspension to the subsequent etching waste liquid composition control treatment process and participating in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products includes: In the subsequent acidification treatment stage of etching waste liquid composition control, the seed crystal suspension is introduced into the acidification reaction system; The acidification reaction system in which the seed crystal suspension was added was stirred to ensure that the seed crystal particles of the seed crystal suspension were evenly distributed in the acidification reaction system. The acidification reaction system was subjected to thermal filtration to separate solid impurities and obtain copper sulfate acidification filtrate containing the seed crystal particles. The copper sulfate acidification filtrate is subjected to crystallization, centrifugation, and drying to obtain the subsequent batches of finished copper sulfate product.

[0017] Secondly, embodiments of the present invention provide an etching waste liquid treatment system based on by-product recycling, the system comprising: A pretreatment device is used to pretreat etching waste liquid to remove suspended and insoluble impurities. A component control device is used to control the composition of pretreated etching waste liquid to obtain copper sulfate acidified filtrate that meets crystallization requirements. The component control device includes a neutralization device, an ammonia conversion device, a pulping device, an acidification device, and a thermal filtration device. A crystallization processing device for obtaining copper sulfate finished product and copper sulfate non-crystalline powder based on the copper sulfate acidification filtrate; A seed suspension preparation apparatus for obtaining a seed suspension based on the copper sulfate amorphous powder; A reflux device is used to feed the seed crystal suspension into the subsequent etching waste liquid composition control process and to participate in the formation of copper sulfate crystals.

[0018] In summary, the beneficial effects of the present invention are as follows: Firstly, by sequentially pretreating, neutralizing, converting to ammonia, pulping, acidifying, and thermally filtering the etching waste liquid, the system addresses the characteristics of the etching waste liquid, such as numerous suspended impurities, numerous insoluble impurities, complex composition, and large system fluctuations. This process gradually removes impurities, converts copper components, and adjusts the system before crystallization, allowing for more complete and stable separation and recovery of the effective copper components in the etching waste liquid. This not only helps reduce the adverse effects of impurities in the waste liquid on the subsequent crystallization process and improves the continuity and stability of subsequent treatment processes, but also helps reduce resource losses and environmental burden during the etching waste liquid treatment process, thereby enhancing the overall resource utilization level and economic value of etching waste liquid treatment.

[0019] Furthermore, the amorphous copper sulfate powder generated during crystallization, centrifugation, and drying is not sold as a low-value byproduct or disposed of as waste. Instead, it is further prepared into a seed suspension and reintroduced into the subsequent etching waste liquid composition control process and copper sulfate crystallization process. This allows copper-containing byproducts that were originally outside the main process to be reintroduced into the treatment system, transforming byproducts from end-of-pipe disposal targets into usable upstream materials. This significantly improves the overall copper resource recovery rate in the entire etching waste liquid treatment process and reduces the cost burden of byproduct storage, transportation, and disposal. In addition, the seed suspension obtained from the amorphous copper sulfate powder originates from the process system itself, and its compositional properties are highly consistent with the subsequent treatment system. Using it in subsequent batches of composition control and crystallization processes further enhances the induced stability and batch consistency of the crystallization process, thereby improving the etching waste liquid treatment efficiency while ensuring the stability and controllability of the subsequent product formation process. Therefore, the method of this invention not only strengthens the copper resource recovery effect in the etching waste liquid treatment process but also further improves the overall recovery rate through byproduct reuse. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, and these are all within the protection scope of the present invention.

[0021] Figure 1 This is a schematic flowchart of an etching waste liquid treatment method based on by-product recycling according to an embodiment of the present invention.

[0022] Figure 2 This is a schematic diagram of the process for controlling the composition of etching waste liquid according to an embodiment of the present invention.

[0023] Figure 3 A schematic diagram of the process for obtaining crystalline and non-crystalline powders according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the process for obtaining seed crystal suspension according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the process of obtaining a seed crystal suspension by adding copper sulfate mother liquor in stages according to an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of the process for modifying the amount of copper sulfate mother liquor added according to an embodiment of the present invention.

[0027] Figure 7This is a schematic diagram of the process for obtaining subsequent batches of copper sulfate finished products according to an embodiment of the present invention.

[0028] Figure 8 This is a schematic diagram of the finished copper sulfate product according to an embodiment of the present invention. Detailed Implementation

[0029] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0030] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0031] Example 1 Please see Figure 1 This invention provides a method for treating etching waste liquid based on byproduct recycling. This method is applicable to production applications such as the resource-based treatment of etching waste liquid and the production of copper sulfate crystals. The method specifically includes the following steps: S1: Pre-treat the etching waste liquid to remove suspended and insoluble impurities; S2: The pretreated etching waste liquid is subjected to composition regulation treatment to obtain the copper sulfate acidified filtrate that meets the crystallization requirements, wherein the composition regulation treatment includes neutralization treatment, ammonia conversion treatment, pulping treatment, acidification treatment and thermal filtration treatment. S3: Based on the copper sulfate acidification filtrate, copper sulfate finished product and copper sulfate non-crystalline powder are obtained, and a seed suspension is obtained based on the copper sulfate non-crystalline powder; S4: The seed suspension is added to the subsequent etching waste liquid composition control process and participates in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products.

[0032] Specifically, etching wastewater refers to the process wastewater generated during the removal and etching of metal materials using acidic or alkaline etching solutions in processes such as electronics manufacturing, printed circuit board processing, or metal surface treatment. This type of etching wastewater typically contains high concentrations of metal ions, especially copper ions, and may also contain residual etchants, complexing agents, modifiers, and impurities introduced during the reaction. Because the etching process selectively removes metal materials, copper ions in the etching wastewater mostly exist in free or complexed states, and their concentration and chemical state vary depending on process conditions, etching time, and raw material composition. Without treatment, etching wastewater is complex in composition and highly corrosive; direct discharge not only wastes metal resources but may also have adverse environmental impacts. Therefore, it is usually necessary to treat the etching wastewater for impurity removal and composition regulation to remove suspended and insoluble impurities and to adjust the chemical state of metal ions in the solution, transforming them into forms suitable for subsequent recycling. In the method described in this invention, the etching waste liquid is used as a raw material for the preparation of copper sulfate. After proper treatment, it can be converted into copper sulfate acidified filtrate that meets the crystallization requirements, thereby realizing the resource utilization of the etching waste liquid.

[0033] This invention uses etching waste liquid as raw material. The waste liquid is pretreated by sedimentation, filtration, or equivalent methods to remove suspended and insoluble impurities, thereby reducing the impact of impurities on the stability of the reaction system during subsequent chemical treatment and minimizing interference from solid particles on equipment and processes. After impurity removal, composition control is performed to effectively convert copper ions in the etching waste liquid into a copper sulfate system suitable for crystallization, resulting in a copper sulfate acidified filtrate that meets crystallization requirements. This copper sulfate acidified filtrate serves as feed to the crystallization process, forming a slurry containing copper sulfate crystals and copper sulfate mother liquor under crystallization conditions, thus achieving the precipitation and enrichment of copper sulfate from the solution system. Subsequently, the slurry is centrifuged to separate the copper sulfate crystals from the copper sulfate mother liquor, and the separated copper sulfate crystals are dried to obtain a finished copper sulfate product. During the centrifugation, drying, and packaging processes described above, a certain amount of amorphous copper sulfate powder is often generated due to fluctuations in crystal morphology, particle breakage, and fine powder entrainment. This amorphous copper sulfate powder is a process byproduct, which typically has high purity but whose morphology or particle size does not meet the requirements of the finished product. To improve resource utilization and stabilize the crystallization process, this invention further obtains the amorphous copper sulfate powder and pre-treats it with crystal seeds to make it suitable for use as a seed carrier in terms of particle size and dispersion. Then, the pre-treated amorphous copper sulfate powder is added to the copper sulfate mother liquor obtained from the aforementioned centrifugation and stirred, allowing the amorphous copper sulfate powder to gradually complete wetting, deagglomeration, and dispersion in the mother liquor environment, forming a uniform and stable seed suspension. The seed suspension is no longer disposed of as waste but is used in the subsequent batch of etching waste liquid composition control treatment process, ensuring that the seed particles remain homologous and compatible in the solution system of subsequent batches and providing a basis for heterogeneous nucleation in the subsequent crystallization stage, thereby promoting controllable nucleation and crystal growth in the copper sulfate crystallization process, and finally obtaining the finished copper sulfate product in subsequent batches. This invention, on the one hand, realizes the recycling and reuse of copper-containing byproducts in the etching waste liquid treatment process, reducing resource loss and additional disposal costs, and improving the overall copper resource recovery rate. On the other hand, the seed suspension formed by the conversion of non-crystalline powder generated by this process system itself has higher consistency with the subsequent treatment system in terms of material source and composition properties, which is more conducive to improving the stability of crystallization induction, improving the controllability of the crystallization process, and increasing the yield and batch consistency of subsequent batches of copper sulfate products. Therefore, it can effectively solve the problems of insufficient utilization of byproducts, low resource utilization, and poor crystallization stability in the existing etching waste liquid treatment process. In one embodiment, the purity of the copper sulfate acidification filtrate that meets the crystallization requirements is greater than or equal to 99.5%, and the Baume degree is 40±3°Bé.The copper sulfate acidification filtrate is obtained after impurity removal and composition control of etching waste liquid. Its copper salt component is mainly in the form of copper sulfate, with low impurity content and an overall purity of ≥99.5%. By controlling the purity of the copper sulfate acidification filtrate within the above range, the interference of impurity ions on crystal nucleation and growth during crystallization can be effectively reduced, decreasing the generation of impurity crystals or abnormal crystal shapes, thus facilitating the acquisition of copper sulfate crystals with stable morphology and concentrated particle size distribution. Simultaneously, controlling the Baume degree of the copper sulfate acidification filtrate within the range of 40±3°Bé helps to keep the solution system in a suitable supersaturated range, ensuring the crystallization driving force while avoiding runaway crystallization or crystal agglomeration due to excessively high solution concentration. Through the synergistic control of the purity and Baume degree of the copper sulfate acidification filtrate, stable and consistent feed conditions are provided for subsequent crystallization processes, thereby improving the controllability of the copper sulfate crystallization process and the stability of product quality.

[0034] In one embodiment, the copper sulfate amorphous powder has a purity of ≥99.5% and a particle size of ≤100μm. The copper sulfate amorphous powder is a fine powder or irregular particle produced during copper sulfate crystallization, centrifugation, and / or drying. Its main component is still copper sulfate, with a chemical purity of ≥99.5%, but it does not meet the finished product requirements in terms of physical morphology or particle size. By controlling the purity of this type of amorphous powder within the above range, it can be ensured that it will not introduce new impurity ions into the system during subsequent reuse, thereby avoiding adverse effects on the crystallization environment and product quality. Simultaneously, limiting the particle size of the amorphous powder to ≤100μm facilitates rapid wetting and dispersion in the mother liquor, reducing the risk of forming large agglomerates and making it more suitable as a seed crystal for subsequent crystallization processes. These purity and particle size conditions ensure that the copper sulfate amorphous powder maintains chemical properties consistent with the finished copper sulfate while possessing good physical controllability.

[0035] Please see Figure 2 In one embodiment, the step of adjusting the composition of the pretreated etching waste liquid to obtain the copper sulfate acidified filtrate that meets the crystallization requirements includes: S11: Neutralize the pretreated etching waste liquid to adjust its pH. S12: Add an ammonia-containing reagent to the neutralized etching waste liquid to perform ammonia conversion treatment, so that the copper ions in the etching waste liquid are converted into an ammonia complex state. S13: The etching waste liquid after ammonia conversion is pulped to promote the full dispersion of impurity particles in the etching waste liquid and form a separable solid phase. S14: Acidify the etching waste liquid after pulping to convert the ammonia complexed copper ions into copper sulfate. S15: The etching waste liquid after acidification is subjected to thermal filtration to separate solid impurities and obtain the copper sulfate acidified filtrate that meets the crystallization requirements.

[0036] Specifically, the pretreated etching waste liquid undergoes neutralization treatment. By adjusting its pH, the solution system is transformed from a strongly acidic or strongly alkaline state to a range suitable for subsequent complexation reactions, thus creating conditions for the transformation of copper ion forms. After neutralization, an ammonia-containing reagent is added to the etching waste liquid for ammonia conversion treatment, transforming the copper ions in the solution from their original form into a stable ammonia-complexed state. Ammonia conversion treatment effectively improves the selective existence of copper ions in the solution and causes some associated impurities to exhibit different chemical behaviors from copper ions, providing a basis for subsequent impurity separation. Subsequently, the etching waste liquid after ammonia conversion treatment undergoes pulping treatment, which fully disperses the impurity particles in the system under mechanical action and promotes the formation of a separable solid phase with more distinct particle size and density characteristics, thereby improving the efficiency and reliability of subsequent separation steps. After pulping treatment, the etching waste liquid is acidified by adding an acidic medium, causing the ammonia-complexed copper ions to disintegrate and transform into copper sulfate, thus gradually making copper sulfate the main solute component in the solution system. This acidification process not only achieves the transformation of the chemical form of copper ions but also provides the necessary solution composition conditions for the subsequent crystallization process. Finally, the etching waste liquid after acidification is subjected to thermal filtration to separate solid impurities in the system under heating conditions, further reducing the residual level of impurities, thereby obtaining copper sulfate acidified filtrate with purity and concentration meeting the requirements for crystallization. Through the above multi-step process, the copper resources in the etching waste liquid are effectively converted and purified, providing stable and reliable feed conditions for the subsequent copper sulfate crystallization process.

[0037] Please see Figure 3 In one embodiment, the process of obtaining copper sulfate finished product and copper sulfate amorphous powder based on the copper sulfate acidification filtrate, and obtaining seed crystal suspension based on the copper sulfate amorphous powder, includes: S21: The copper sulfate acidified filtrate is subjected to crystallization treatment to form a slurry containing copper sulfate crystals and copper sulfate mother liquor; S22: The slurry is centrifuged to obtain copper sulfate crystals and copper sulfate mother liquor, and the copper sulfate crystals are dried to obtain the finished copper sulfate product; S23: Obtain amorphous copper sulfate powder generated during centrifugation and / or drying, and add the amorphous copper sulfate powder to the copper sulfate mother liquor after seed pretreatment and stirring to form a uniform seed suspension.

[0038] Specifically, the copper sulfate acidified filtrate, which meets the crystallization requirements, is first subjected to crystallization treatment, causing the copper sulfate in the filtrate to gradually precipitate in crystal form and form a crystal slurry together with the unprecipitated liquid phase. This crystal slurry can be understood as a mixed system where crystal particles and mother liquor coexist, facilitating subsequent solid-liquid separation. The crystal slurry is then centrifuged to separate the copper sulfate crystals from the copper sulfate mother liquor using centrifugal force. The separated copper sulfate crystals are then dried to remove adhering moisture and obtain finished copper sulfate that can be directly exported as a product. Simultaneously, some non-crystalline copper sulfate powder is usually generated during centrifugation and drying. Although this powder does not form a regular crystal morphology, it still retains a high level of effective copper sulfate content. Therefore, it is not discarded directly but used as a seed source for subsequent crystal production. Specifically, the collected non-crystalline copper sulfate powder undergoes seed pretreatment, which may include sieving, crushing, impurity removal, particle size adjustment, or dispersion treatment to improve its particle size distribution and dispersion stability. The pretreated non-crystalline powder is then added to the copper sulfate mother liquor and stirred to uniformly disperse it in the mother liquor, ultimately forming a seed suspension. This approach allows for the reintroduction of copper-containing byproducts that are often overlooked during centrifugation and drying into the process system, reducing copper resource loss and improving overall recycling rates. Furthermore, since the resulting seed crystal suspension originates directly from the production system, its material composition is more compatible with the subsequent crystallization environment, which is more conducive to improving the stability of subsequent crystallization induction and the consistency of product batches.

[0039] Please see Figure 4 In one embodiment, obtaining the amorphous copper sulfate powder generated during centrifugation and / or drying, and then adding the amorphous copper sulfate powder to the copper sulfate mother liquor after seed pretreatment and stirring to form a uniform seed suspension includes: S31: Collect the non-crystalline copper sulfate powder generated during the centrifugation and / or drying process; S32: The copper sulfate amorphous powder is transported to the seed crystal pretreatment tank through a closed negative pressure conveying device; S33: The copper sulfate amorphous powder is subjected to seed pretreatment in the seed pretreatment tank. The seed pretreatment includes particle size control and dispersion treatment of the copper sulfate amorphous powder. S34: Add the copper sulfate mother liquor to the copper sulfate non-crystalline powder after seed crystal pretreatment, and stir to form a uniform seed crystal suspension.

[0040] Specifically, during the centrifugal separation of copper sulfate slurry and the drying of copper sulfate crystals, a certain amount of non-crystalline copper sulfate powder is generated due to fine particle entrainment, crystal breakage, or irregular crystal morphology. This non-crystalline powder is collected centrally using collection structures located at the corresponding process positions. To prevent secondary contamination or moisture absorption and agglomeration of the non-crystalline powder during transport, a closed negative pressure conveying device is used to transport the non-crystalline copper sulfate powder to a seed pretreatment tank, thereby ensuring cleanliness while improving the safety and stability of the transport process. In the seed pretreatment tank, the non-crystalline copper sulfate powder undergoes seed pretreatment to improve its physical state, making it suitable as a seed source for the crystallization process. The seed pretreatment includes particle size control and dispersion treatment of the non-crystalline copper sulfate powder. By de-agglomerating any agglomerates that may exist in the non-crystalline powder and adjusting the particle size distribution, it achieves good dispersibility and controllability in the subsequent liquid phase system. After the seed crystal pretreatment is completed, the non-crystalline copper sulfate powder is added to the copper sulfate mother liquor obtained by centrifugation, and the powder is gradually wetted and uniformly dispersed in the mother liquor environment through stirring, forming a stable and consistent seed crystal suspension. Through this process, the non-crystalline copper sulfate powder, which originally did not meet the requirements of the finished product, is transformed into a seed carrier suitable for the crystallization process.

[0041] Please see Figure 5 In one embodiment, the step of adding the copper sulfate mother liquor to the pretreated copper sulfate amorphous powder and stirring to form a uniform seed suspension includes: S41: Establish a circulation path for returning the copper sulfate mother liquor generated during the centrifugal separation of crystal slurry to the seed crystal pretreatment tank; S42: Determine the total amount of copper sulfate mother liquor to be added based on the amount of non-crystalline copper sulfate powder after seed crystal pretreatment. S43: Determine the amount of mother liquor added in each stage according to the total amount added and the preset stage allocation rules, wherein the mother liquor added stage includes at least a wetting stage and a dispersion stage. S44: Add the copper sulfate mother liquor to the copper sulfate amorphous powder that has undergone seed crystal pretreatment according to the stage addition amount corresponding to the wetting stage and the dispersion stage, and stir accordingly to obtain the seed crystal suspension.

[0042] Please see Figure 6 In one embodiment, the step of adding the copper sulfate mother liquor to the pretreated copper sulfate amorphous powder according to the stage amounts corresponding to the wetting stage and the dispersion stage, and then stirring accordingly to obtain the seed suspension, includes: S51: Add the copper sulfate mother liquor refluxed through the circulation path to the copper sulfate amorphous powder after seed crystal pretreatment according to the stage addition amount corresponding to the wetting stage, and stir to change the copper sulfate amorphous powder from a dry powder state to a wet state. S52: After the wetting stage is completed, continue to add the copper sulfate mother liquor according to the stage addition amount corresponding to the dispersion stage, and stir to obtain the initial seed crystal suspension; S53: The initial seed crystal suspension is tested to obtain test results, wherein the test results include the Baumé degree of the liquid phase and the dispersion state of the non-crystalline copper sulfate powder; S54: When the test result does not meet the preset conditions, determine the amount of mother liquor to be added in the matching stage based on the test result; S55: According to the amount of mother liquor added in the matching stage, add the copper sulfate mother liquor and stir until the liquid phase Baume degree of the initial seed suspension reaches the preset range that matches the subsequent acidification reaction system, and the copper sulfate non-crystalline powder forms a uniform suspension state to obtain the seed suspension.

[0043] Specifically, the seed crystal pretreatment tank here can be understood as a processing unit that receives amorphous powder and completes its reliquefaction and redispersion. The circulation path is a closed-loop system that transports the copper sulfate mother liquor precipitated after centrifugation of the crystal slurry back to this processing unit. This allows the mother liquor to be used directly as the liquid phase source for the seed crystal suspension, eliminating the need for external discharge or re-preparation. This ensures good continuity in composition between the reused medium and the preceding crystallization system. During implementation, the total amount of mother liquor to be added in this round is determined based on the amount of amorphous copper sulfate powder after seed crystal pretreatment. This ensures that the overall liquid volume matches the powder volume, avoiding insufficient liquid volume which would make the powder difficult to wet and disperse, and avoiding excessive liquid volume which would make the subsequent system too dilute and weaken the seed crystal concentration. Furthermore, according to the preset stage allocation rules, the total amount is divided into at least two parts: a wetting stage and a dispersion stage. The amount of mother liquor added in the wetting stage is mainly used to gradually form a liquid film on the surface of the non-crystalline powder that was originally in a dry powder state, and to gradually occupy the internal voids of the powder with the liquid phase, thereby achieving a smooth transition from loose dry powder to an overall wet state. After this stage is completed, the mother liquor is added again according to the stage addition amount corresponding to the dispersion stage and stirred, so that the already wetted particle clusters are gradually opened up, the adhesion between particles and local agglomeration are weakened, and thus an initial seed suspension with preliminary fluidity and uniformity is formed. Since simply adding liquid in the aforementioned two stages does not necessarily guarantee that the suspension fully meets the requirements for subsequent use, it is also necessary to test the initial seed crystal suspension. The test results should include at least the Baume degree of the liquid phase and the dispersion state of the non-crystalline powder. The Baume degree of the liquid phase reflects whether the current liquid phase concentration is compatible with the subsequent acidification reaction system, while the dispersion state reflects whether the particles still have problems such as agglomeration, sedimentation tendency, or uneven suspension. If the test results show that the preset conditions have not been met, the amount of mother liquor to be added in the matching stage should be determined based on the test results, and then the addition and stirring should be carried out to gradually bring the liquid phase concentration and particle suspension state closer to the target range, until the Baume degree of the initial seed crystal suspension reaches the preset range that is compatible with the subsequent acidification reaction system, and the non-crystalline powder forms a uniform suspension state, finally obtaining a seed crystal suspension that can stably participate in the subsequent crystallization process. This phased organization and feedback-based processing method enables the simultaneous reuse of copper sulfate mother liquor and non-crystalline copper sulfate powder, transforming materials that were originally considered byproduct residues back into seed crystals that promote crystallization. On the other hand, it avoids the problems of local agglomeration, unstable suspension, and liquid phase mismatch caused by uncontrolled direct mixing. This is conducive to improving the recycling rate of byproducts, maintaining the stability of the subsequent crystallization environment, and improving the consistency of the final copper sulfate product and the continuity of the production process.

[0044] In one embodiment, the preset stage allocation rule includes a preset priority allocation rule executed when the total amount of mother liquor added is insufficient and a preset compensation allocation rule executed when the total amount of mother liquor added is sufficient. The step of determining the stage addition amount for each mother liquor addition stage based on the total amount added and the preset stage allocation rule, wherein the mother liquor addition stage includes at least a wetting stage and a dispersion stage, including: Based on the surface wetting amount and pore liquid holding capacity of copper sulfate amorphous powder after seed crystal pretreatment, the first benchmark addition amount in the wetting stage is determined. Based on the amount of continuous liquid phase formation and suspension maintenance required for the copper sulfate amorphous powder to form a uniform suspension, the second benchmark addition amount for the dispersion stage is determined. The sum of the first benchmark addition and the second benchmark addition is used to obtain the total benchmark amount for the stage. Compare the total baseline amount for the stage with the total amount added; When the total amount of the stage reference is greater than the total amount added, the first reference addition amount and the second reference addition amount are compressed and allocated according to the preset priority allocation rule to obtain the stage addition amount of the wetting stage and the stage addition amount of the dispersion stage. When the total amount of the stage baseline is less than or equal to the total amount added, the remaining mother liquor is allocated to the dispersion stage according to the preset compensation allocation rule to obtain the stage addition amount of the wetting stage and the stage addition amount of the dispersion stage.

[0045] Specifically, the preset priority allocation rule applies to situations where the total amount of mother liquor added is insufficient. Its purpose is to prioritize the stages that have a more fundamental and critical impact on subsequent processes when mother liquor resources are limited, so that the system can at least complete the transition from dry powder to treatable wet materials. The preset compensation allocation rule applies to situations where the total amount of mother liquor is sufficient. Its purpose is to, after meeting the basic wetting and basic dispersion requirements, to selectively add the remaining mother liquor to stages that are more conducive to suspension uniformity and stability, so as to further improve the formation quality of the seed crystal suspension. The initial addition amount during the wetting stage is not arbitrarily set, but determined based on the surface wetting amount and pore liquid holding capacity of the copper sulfate amorphous powder after seed crystal pretreatment. The surface wetting amount reflects the basic amount of liquid required for the outer surface of the particles to change from a bare and dry state to being continuously covered by the liquid phase. Only when this level is reached will the powder surface be less prone to localized drainage, floating powder, or dry powder entrainment. The pore liquid holding capacity reflects the ability of the microporous structure, interparticle voids, and loosely packed areas of the powder to absorb the liquid phase. Because amorphous powders often have fine particle sizes and large specific surface areas, a certain internal void network will be formed after the particles are packed. If these voids are not occupied by an appropriate amount of liquid phase, the appearance may seem to be wetted, but there may still be problems such as internal dry cores, localized loose agglomeration, or re-powdering after stirring. Therefore, the amount of mother liquor required in the wetting stage must cover both the particle surface and the particle packing structure. The second baseline addition amount during the dispersion stage is determined by the continuous liquid phase formation amount and the suspension maintenance amount. The continuous liquid phase formation amount refers to the amount of liquid required to form a continuous liquid medium that can transmit shear and flow between the particle clusters and between particles, based on the fact that the powder is already in a generally wet state. If this amount of liquid is insufficient, although the powder will no longer appear as obviously dry powder, the system will be viscous, agglomerated, or semi-fluidized, and the particles will be difficult to further disperse and distribute evenly. The suspension maintenance amount refers to the amount of liquid required to maintain a relatively uniform spatial distribution of the dispersed particles during continuous stirring and subsequent short-term settling, and to reduce the tendency of rapid sedimentation or re-agglomeration. This amount of liquid is directly related to whether the initial seed crystal suspension has sufficient fluidity, uniformity, and adjustability.

[0046] In practice, the first baseline addition amount for the wetting stage and the second baseline addition amount for the dispersion stage are determined separately. These two amounts are then summed to obtain the total baseline amount for each stage. This total baseline amount can be understood as the theoretical total liquid consumption required for the powder to transition from dry powder to a uniform suspension state, without considering the constraints of mother liquor supply. Subsequently, this total baseline amount is compared with the actual determined total mother liquor addition amount. This step is not simply a numerical comparison, but rather an identification of whether the current operating state is characterized by liquid shortage or sufficient liquid supply in the process decision-making. When the total baseline amount for each stage is greater than the total addition amount, it indicates that the existing mother liquor is insufficient to fully meet the ideal baseline liquid requirements for both stages. If the original baseline amounts are still applied, it will lead to excessive mother liquor consumption in one stage and significant liquid shortage in the other stage. Ultimately, this may result in the powder not being adequately wetted and a stable dispersion system not being established. Therefore, it is necessary to activate the preset priority allocation rule to compress and allocate the first and second baseline addition amounts. The essence of compression allocation is to redetermine the proportional relationship between two stages based on the preset importance of each stage, the material transition sequence, and the risk of irreversible processes. Typically, the minimum amount of mother liquor is first ensured in the wetting stage to complete the establishment of a surface liquid film and the filling of pores. If wetting is insufficient, the powder will remain as dry powder cores or loose clumps, making it difficult to efficiently disperse and uniformly suspend even if more mother liquor is added in the dispersion stage. Based on this, the remaining mother liquor is then allocated to the dispersion stage, ensuring the system has at least basic liquid phase continuity and particle loosening conditions. Conversely, when the total baseline amount for each stage is less than or equal to the total amount added, it indicates that the existing mother liquor is not only sufficient to meet the theoretical baseline amounts for both the wetting and dispersion stages, but also has a surplus. In this case, if the excess mother liquor is continued to be added back to each stage evenly, it often fails to fully exert its effect of improving the system state. Therefore, a preset compensation allocation rule is used to preferentially allocate the remaining mother liquor to the dispersion stage. The reason for this setup is that after the first baseline addition amount is reached in the wetting stage, the powder has usually completed the basic transformation from dry powder to a generally wet material. Continuing to add liquid to the wetting stage has a relatively limited marginal effect on improving the state. However, adding the remaining mother liquor to the dispersion stage can further enhance the continuity of the liquid phase between particles, expand the relative movement space of particles under stirring, reduce the adhesion strength of agglomerates, improve the fluidity of the suspension, and enhance the ability of particles to maintain uniform distribution in the liquid phase. This allows subsequent detection and matching adjustments to be based on a more stable and controllable initial suspension system.

[0047] This embodiment does not simply divide the amount of liquid added. Instead, it first establishes stage benchmark amounts based on two different process objectives: wetting and dispersion. Then, it selects two types of allocation rules—preferential or compensatory—based on the actual constraints of the total amount of mother liquor, ultimately obtaining more reasonable addition amounts for each of the wetting and dispersion stages. This significantly improves the targeting of mother liquor utilization, ensuring that limited mother liquor is prioritized for use at the critical points that most determine the material's state transformation, avoiding local over-addition, overall under-addition, or inherent distribution imbalance caused by fixed-ratio addition. On the other hand, under sufficient mother liquor conditions, compensatory allocation can further improve the liquid phase environment in the dispersion stage, making the initial seed crystal suspension more uniform and stable. This is more conducive to further matching and adjusting the Baumé degree and dispersion state of the subsequent liquid phase, thereby improving the effectiveness of the synergistic reuse of by-product mother liquor and non-crystalline powder, and enhancing the continuity, stability, and product quality consistency of the entire copper sulfate preparation process.

[0048] In one embodiment, determining the amount of mother liquor to be added in the matching stage based on the test results when the test results do not meet the preset conditions includes: The detection results are decomposed to obtain liquid phase Baume deviation results and dispersion state deviation results. The liquid phase Baume deviation results are used to characterize the degree of deviation between the actual liquid phase Baume degree of the initial seed suspension and the preset range. The dispersion state deviation results are used to characterize the degree of aggregation, sedimentation trend and suspension uniformity of the copper sulfate amorphous powder in the initial seed suspension. Based on the liquid phase Baumé deviation results, determine the liquid phase compensation requirement; based on the dispersion state deviation results, determine the dispersion compensation requirement. The liquid phase compensation requirement and the dispersion compensation requirement are coupled and analyzed to obtain the theoretical total amount of replenishment in the matching stage; Based on the theoretical total replenishment amount, and taking into account the current liquid-solid state of the initial seed crystal suspension, the concentration state of the mother liquor, and the adaptation requirements of the subsequent acidification reaction system, the theoretical total replenishment amount is constrained and corrected to obtain the target total replenishment amount for the matching stage. The number of additions and the amount of each addition are determined based on the target total amount of addition. The amounts of each addition are allocated in the order of first satisfying the dispersion state correction and then satisfying the liquid phase Baume degree correction. After each addition, the initial seed crystal suspension is tested again, and the amount of subsequent additions is adjusted based on the test results.

[0049] Specifically, the deviation decomposition here refers to distinguishing between the liquid phase concentration problem and the particle dispersion problem reflected in the test results, forming two independent but related sources of deviation information. The liquid phase Baume deviation result reflects the difference between the actual liquid phase concentration of the current initial seed suspension and the preset target range. This difference will directly affect the concentration connection of the subsequent acidification reaction system and the environmental stability after the seed is introduced. The dispersion state deviation result reflects the spatial distribution quality of the non-crystalline copper sulfate powder in the liquid phase, including whether there are still obvious agglomerates, whether there are local particles that accelerate to settle, and whether the suspension system is uniform overall. Although this type of deviation is also related to the liquid volume, it focuses more on the liquid absorption, deagglomeration, and suspension maintenance state of the particles in the liquid phase. In practice, after obtaining the initial seed crystal suspension test results, the Baume degree and dispersion state of the liquid phase are analyzed separately. If the Baume degree deviates from the preset range, the liquid phase compensation requirement can be determined, which is the theoretical amount of mother liquor that needs to be added to bring the liquid phase conditions closer to the target range. If agglomeration, sedimentation, or uneven suspension is found in the system, the dispersion compensation requirement is further determined. This part is not simply to increase the liquid volume, but to improve the continuity of the liquid phase between particles, reduce the probability of particle adhesion, and improve the suspension retention capacity. Since these two types of compensation requirements are not isolated from each other, changes in liquid phase concentration will affect the liquid phase environment in which the particles are located, and improvements in particle dispersion state will in turn change the actual acceptance capacity of the system to the mother liquor. Therefore, it is also necessary to perform a coupling analysis of the liquid phase compensation requirement and the dispersion compensation requirement to form the theoretical total amount of addition in the matching stage. This coupling analysis can be understood as a comprehensive balance of the two types of addition targets, avoiding the system becoming too dilute and the dispersion imbalance caused by adding liquid only according to the Baume degree, and also avoiding the liquid phase concentration deviating from the subsequent process requirements due to additional liquid addition only to improve the dispersion state.

[0050] After obtaining the theoretical total replenishment amount, it cannot be directly used as the execution value. Instead, it needs to be further constrained and corrected by combining the current liquid-solid state of the initial seed crystal suspension, the concentration state of the mother liquor, and the adaptation requirements of the subsequent acidification reaction system. The liquid-solid state mainly reflects the relative ratio of liquid phase to particles in the current system, as well as the system's fluidity, viscosity, and response to shear. The concentration state of the mother liquor reflects whether the concentration characteristics of the mother liquor to be replenished will amplify or weaken the replenishment result. The adaptation requirements of the subsequent acidification reaction system limit the replenishment at this stage from only considering the local improvement of the current suspension. It is also necessary to consider whether the replenished seed crystal suspension can be smoothly integrated into the next process. Therefore, the target total replenishment amount obtained after this layer of constraint correction is closer to the executable replenishment amount that satisfies the current correction without disrupting the subsequent connection conditions.

[0051] Furthermore, to avoid sudden changes in local concentration, particle re-agglomeration, or distortion of state judgment caused by a single concentrated replenishment, the number of replenishments and the amount of each replenishment in the matching stage should be determined according to the target total replenishment amount. The total replenishment task is divided into multiple rounds of small adjustments, with the amount of each replenishment allocated in the order of first satisfying the dispersion state correction and then satisfying the liquid phase Baume correction. The reason for this setting is that if the particles in the system are still obviously agglomerated or unevenly suspended, even if the liquid phase Baume is first brought into the target range, the particle state may still cause subsequent detection results to be distorted or the system to deviate again. Improving the dispersion state first helps to form a more realistic and stable distribution basis for the powder in the liquid phase, and then gradually correcting the liquid phase Baume on this basis can make the replenishment effect more stable and reliable. After each addition, the initial seed suspension is re-tested, and the amount of subsequent additions is adjusted based on the re-test results. This constitutes a dynamic feedback process. In other words, each subsequent addition is not a mechanical execution of the previous setting, but rather a readjustment of the remaining addition plan based on the actual changes that have occurred in the system. This avoids problems such as over-filling, under-filling, or inconsistent correction rhythms for different deviations. By decomposing the test results, coupling the addition requirements, correcting the theoretical total amount constraint, and then dynamically executing the process according to multiple amounts, the amount of mother liquor added in the matching stage can be transformed from a rough, empirical addition to a fine-tuning process targeting both liquid concentration and particle dispersion. This not only improves the accuracy and controllability of seed suspension state correction but also reduces mother liquor waste, decreases the number of repeated adjustments, and provides more stable and consistent seed introduction conditions for subsequent acidification and crystallization processes.

[0052] Please see Figure 7 In one embodiment, the step of adding the seed crystal suspension to the subsequent etching waste liquid composition control treatment process and participating in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products includes: In the subsequent acidification treatment stage of etching waste liquid composition control, the seed crystal suspension is introduced into the acidification reaction system; The acidification reaction system in which the seed crystal suspension was added was stirred to ensure that the seed crystal particles of the seed crystal suspension were evenly distributed in the acidification reaction system. The acidification reaction system was subjected to thermal filtration to separate solid impurities and obtain copper sulfate acidification filtrate containing the seed crystal particles. The copper sulfate acidification filtrate is subjected to crystallization, centrifugation, and drying to obtain the subsequent batches of finished copper sulfate product.

[0053] In this embodiment, to effectively reuse the seed crystal suspension in the production process and ensure its stable participation in the crystallization process of subsequent batches of copper sulfate, the present invention introduces the seed crystal suspension into the subsequent etching waste liquid composition control treatment process, connecting it with acidification, filtration, and crystallization steps. Specifically, after neutralization, ammonia conversion, and pulping treatments, the seed crystal suspension is introduced into the acidification reaction system during the acidification stage of the subsequent etching waste liquid composition control treatment. Since the seed crystal particles in the seed crystal suspension are homologous to the copper sulfate system, and their chemical composition and crystal structure are highly consistent with the target crystallization product, they can fully contact the copper sulfate solute in the system during the acidification reaction, providing a favorable nucleation basis for subsequent crystallization. After the seed crystal suspension is added to the acidification reaction system, the system is stirred to ensure uniform distribution of the seed crystal particles within the reaction system. Stirring prevents seed crystals from agglomerating or settling in localized areas, ensuring they remain dispersed throughout the reaction system. This allows copper sulfate solute in each region to nucleate in an orderly manner under the guidance of the seed crystals. The stirring process also enhances mass transfer, facilitating the full progress of the acidification reaction.

[0054] After the acidification reaction is completed and the seed crystals are uniformly distributed, the acidification reaction system is subjected to hot filtration to separate any solid impurities that may be present. Hot filtration effectively removes incompletely reacted impurity particles or reaction byproducts, and allows the seed crystals to enter subsequent processes along with the filtrate while maintaining the solution temperature and flowability, thus obtaining a copper sulfate acidification filtrate containing the seed crystals. This acidification filtrate meets the crystallization requirements in terms of composition and concentration, and because the seed crystals are already present in the system, the solution has favorable nucleation conditions when entering the crystallization process.

[0055] Subsequently, the copper sulfate acidified filtrate containing seed crystals is subjected to crystallization treatment. Under crystallization conditions, copper sulfate preferentially undergoes heterogeneous nucleation on the surface of the seed crystals and gradually grows into regular crystals, thereby effectively suppressing disordered spontaneous nucleation. After crystallization, the resulting crystal slurry is sequentially centrifuged and dried to finally obtain the subsequent batches of finished copper sulfate products. Through the above process, the seed crystal suspension is reused in a closed loop between different batches, which not only realizes the resource utilization of non-crystalline copper sulfate powder, but also improves the stability of the crystallization process and the consistency of product quality in subsequent batches.

[0056] In summary, compared with the prior art, the solution described in this invention has at least the following beneficial effects: Firstly, by sequentially pretreating, neutralizing, converting to ammonia, pulping, acidifying, and thermally filtering the etching waste liquid, the system addresses the characteristics of the etching waste liquid, such as numerous suspended impurities, numerous insoluble impurities, complex composition, and large system fluctuations. This process gradually removes impurities, converts copper components, and adjusts the system before crystallization, allowing for more complete and stable separation and recovery of the effective copper components in the etching waste liquid. This not only helps reduce the adverse effects of impurities in the waste liquid on the subsequent crystallization process and improves the continuity and stability of subsequent treatment processes, but also helps reduce resource losses and environmental burden during the etching waste liquid treatment process, thereby enhancing the overall resource utilization level and economic value of etching waste liquid treatment.

[0057] Furthermore, the amorphous copper sulfate powder generated during crystallization, centrifugation, and drying was not sold as a low-value byproduct or disposed of as waste. Instead, it was further prepared into a seed suspension and reintroduced into the subsequent etching waste liquid composition control process and copper sulfate crystallization process. This allows copper-containing byproducts that were originally outside the main process to be reintroduced into the treatment system, transforming byproducts from end-of-pipe disposal targets into usable upstream materials. This significantly improves the overall recovery rate of copper resources in the entire etching waste liquid treatment process and reduces the cost burden of byproduct storage, transportation, and disposal. In addition, the seed suspension obtained from the amorphous copper sulfate powder originates from the process system itself, and its compositional properties are highly consistent with the subsequent treatment system. Using it for subsequent batch composition control and crystallization processes is more conducive to improving the induced stability and batch consistency of the crystallization process. Thus, while improving the efficiency of etching waste liquid treatment, it also ensures the stability and controllability of the subsequent product formation process. Therefore, the method of the present invention can not only enhance the copper resource recovery effect in the etching waste liquid treatment process, but also further improve the overall recycling rate through the reuse of by-products, and has good process synergy and practical application value.

[0058] Example 2 Based on the above Embodiment 1, this embodiment of the invention provides a finished copper sulfate product, which is prepared by the etching waste liquid treatment method based on by-product recycling as described in Embodiment 1. Figure 8The diagram illustrates the preparation of copper sulfate product based on the method of this invention. This copper sulfate product uses etching waste liquid as raw material. After impurity removal and composition control, a copper sulfate acidification filtrate meeting crystallization requirements is obtained. This filtrate is then processed through crystallization, centrifugation, and drying. During the preparation process, non-crystalline copper sulfate powder generated during centrifugation and / or drying is recovered and pretreated with seed crystals before being mixed with copper sulfate mother liquor to form a seed crystal suspension. This suspension is then reused in subsequent batches to participate in crystallization, thus creating a closed-loop recycling path for the copper sulfate product. Because the seed crystal source is compatible with the production system, the copper sulfate product exhibits good stability and consistency in different batches. Furthermore, by controlling the purity and Baume degree of the copper sulfate acidification filtrate, the resulting copper sulfate product can meet the requirements for high-purity applications. This copper sulfate product is suitable for industrial applications requiring high-purity copper sulfate, and its preparation process reduces waste disposal pressure and improves raw material utilization efficiency.

[0059] Example 3 Based on the above embodiment one, embodiment three of the present invention provides an etching waste liquid treatment system based on by-product recycling, the system comprising: A pretreatment device is used to pretreat etching waste liquid to remove suspended and insoluble impurities. A component control device is used to control the composition of pretreated etching waste liquid to obtain copper sulfate acidified filtrate that meets crystallization requirements. The component control device includes a neutralization device, an ammonia conversion device, a pulping device, an acidification device, and a thermal filtration device. A crystallization processing device for obtaining copper sulfate finished product and copper sulfate non-crystalline powder based on the copper sulfate acidification filtrate; A seed suspension preparation apparatus for obtaining a seed suspension based on the copper sulfate amorphous powder; A reflux device is used to feed the seed crystal suspension into the subsequent etching waste liquid composition control process and to participate in the formation of copper sulfate crystals.

[0060] The etching waste liquid treatment system based on by-product recycling provided in this invention integrates the various process steps of the aforementioned etching waste liquid treatment methods into a device-based system, forming a closed-loop treatment system capable of continuously completing impurity removal, component regulation, copper sulfate crystallization, by-product reuse, and subsequent batch recirculation for crystallization. The pretreatment device is located at the front end of the system to receive the etching waste liquid and remove suspended and insoluble impurities, reducing the interference of impurities on subsequent chemical transformation, filtration separation, and crystallization purity. The component regulation device is connected to the pretreatment device and is used to neutralize, ammonia-convert, pulp, acidify, and thermally filter the pretreated etching waste liquid, gradually converting the copper element in the waste liquid into an acidified filtrate state suitable for subsequent copper sulfate crystallization. Specifically, the neutralization device adjusts the acid-base conditions of the system, the ammonia-converting device promotes the conversion of the target component, the pulping device improves the uniformity of material mixing and reaction stability, and the acidification device creates an acidic environment suitable for copper sulfate precipitation. A thermal filtration device is used to separate impurities and obtain copper sulfate acidified filtrate that meets crystallization requirements under high-temperature conditions. A crystallization treatment device is used to crystallize and separate the copper sulfate acidified filtrate to obtain finished copper sulfate and non-crystalline copper sulfate powder that has not formed regular crystals. A seed suspension preparation device is used to redisperse the non-crystalline copper sulfate powder to form a seed suspension that can re-participate in the subsequent crystallization process. A reflux device returns the seed suspension to the subsequent etching waste liquid composition control process and copper sulfate crystallization process, transforming the non-crystalline powder, which was originally a byproduct, into effective seed crystals that induce subsequent crystal formation. Through the above structural setup, this system can not only realize the recovery and utilization of copper resources in etching waste liquid, improve the production efficiency and resource utilization rate of finished copper sulfate, but also reduce the waste of non-crystalline powder, improve the stability and consistency of subsequent batch crystallization processes, thereby achieving integrated, continuous, and high-value-added treatment of etching waste liquid and byproduct recycling.

[0061] 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.

[0062] 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. In the description of this specification, the reference to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., means that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples and the features of different embodiments / modes or examples described in this specification.

[0063] 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 etching waste liquid based on byproduct recycling, characterized in that, The method includes: The etching waste liquid is pretreated to remove suspended and insoluble impurities. The pretreated etching waste liquid is subjected to composition regulation treatment to obtain copper sulfate acidified filtrate that meets the crystallization requirements. The composition regulation treatment includes neutralization treatment, ammonia conversion treatment, pulping treatment, acidification treatment and thermal filtration treatment. Based on the copper sulfate acidification filtrate, copper sulfate finished product and copper sulfate non-crystalline powder are obtained, and a seed suspension is obtained based on the copper sulfate non-crystalline powder; The seed crystal suspension is added to the subsequent etching waste liquid composition control process and participates in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products.

2. The etching waste liquid treatment method based on by-product recycling according to claim 1, characterized in that, The pretreated etching waste liquid undergoes composition regulation treatment to obtain copper sulfate acidified filtrate that meets crystallization requirements. This composition regulation treatment includes neutralization, ammonia conversion, pulping, acidification, and thermal filtration. The pretreated etching waste liquid is neutralized to adjust its pH. An ammonia-containing reagent was added to the neutralized etching waste liquid to perform ammonia conversion treatment, so that the copper ions in the etching waste liquid were converted into an ammonia complex state. The etching waste liquid after ammonia conversion is pulped to promote the full dispersion of impurity particles in the etching waste liquid and form a separable solid phase. The etching waste liquid after pulping is acidified to convert ammonia-complexed copper ions into copper sulfate. The etching waste liquid after acidification is subjected to thermal filtration to separate solid phase impurities and obtain the copper sulfate acidified filtrate that meets the crystallization requirements.

3. The etching waste liquid treatment method based on by-product recycling according to claim 1, characterized in that, The process of obtaining copper sulfate finished product and copper sulfate amorphous powder based on the copper sulfate acidification filtrate, and obtaining a seed suspension based on the copper sulfate amorphous powder includes: The copper sulfate acidified filtrate is subjected to crystallization treatment to form a slurry containing copper sulfate crystals and copper sulfate mother liquor; The slurry is centrifuged to obtain copper sulfate crystals and copper sulfate mother liquor. The copper sulfate crystals are then dried to obtain the finished copper sulfate product. Obtain amorphous copper sulfate powder generated during centrifugation and / or drying, and add the amorphous copper sulfate powder to the copper sulfate mother liquor after seed pretreatment and stirring to form a uniform seed suspension.

4. The etching waste liquid treatment method based on by-product recycling according to claim 2, characterized in that, The copper sulfate acidified filtrate that meets the crystallization requirements has a purity of ≥99.5% and a Baume degree of 40±3°Bé.

5. The etching waste liquid treatment method based on by-product recycling according to claim 1, characterized in that, The purity of the copper sulfate amorphous powder is greater than or equal to 99.5%, and the particle size is less than or equal to 100 μm.

6. The etching waste liquid treatment method based on by-product recycling according to claim 3, characterized in that, The process of obtaining amorphous copper sulfate powder generated during centrifugation and / or drying, and then adding the amorphous copper sulfate powder to the copper sulfate mother liquor after seed pretreatment and stirring to form a uniform seed suspension includes: Collect the non-crystalline copper sulfate powder produced during the centrifugation and / or drying process; The amorphous copper sulfate powder is transported to the seed crystal pretreatment tank via a closed negative pressure conveying device. The copper sulfate amorphous powder is subjected to seed pretreatment in the seed pretreatment tank. The seed pretreatment includes particle size control and dispersion treatment of the copper sulfate amorphous powder. The copper sulfate mother liquor is added to the copper sulfate amorphous powder that has undergone seed crystal pretreatment, and the mixture is stirred to form a uniform seed crystal suspension.

7. The etching waste liquid treatment method based on by-product recycling according to claim 6, characterized in that, The step of adding the copper sulfate mother liquor to the pretreated copper sulfate amorphous powder and stirring to form a uniform seed suspension includes: Establish a circulation path for returning the copper sulfate mother liquor generated during the centrifugal separation of crystal slurry to the seed crystal pretreatment tank; The total amount of copper sulfate mother liquor to be added is determined based on the amount of non-crystalline copper sulfate powder after seed crystal pretreatment. Based on the total amount added and the preset stage allocation rules, the stage addition amount for each mother liquor addition stage is determined, wherein the mother liquor addition stage includes at least a wetting stage and a dispersion stage. The copper sulfate mother liquor is added to the copper sulfate amorphous powder that has undergone seed crystal pretreatment according to the stage addition amounts corresponding to the wetting stage and the dispersion stage, and the mixture is stirred accordingly to obtain the seed crystal suspension.

8. The etching waste liquid treatment method based on by-product recycling according to claim 7, characterized in that, The step of adding the copper sulfate mother liquor to the copper sulfate amorphous powder pretreated with seed crystals according to the stage corresponding to the wetting stage and the dispersion stage, and then stirring accordingly to obtain the seed crystal suspension includes: Add the copper sulfate mother liquor refluxed through the circulation path to the copper sulfate amorphous powder after seed crystal pretreatment according to the stage addition amount corresponding to the wetting stage, and stir to change the copper sulfate amorphous powder from a dry powder state to a wet state. After the wetting stage is completed, the copper sulfate mother liquor is added according to the stage addition amount corresponding to the dispersion stage, and the mixture is stirred to obtain the initial seed crystal suspension. The initial seed crystal suspension was tested to obtain test results, wherein the test results included the Baumé degree of the liquid phase and the dispersion state of the non-crystalline copper sulfate powder; When the test results do not meet the preset conditions, the amount of mother liquor added in the matching stage is determined based on the test results; According to the amount of mother liquor added in the matching stage, the copper sulfate mother liquor is added and stirred until the liquid phase Baume degree of the initial seed suspension reaches the preset range that matches the subsequent acidification reaction system, and the non-crystalline copper sulfate powder forms a uniform suspension state, thus obtaining the seed suspension.

9. The etching waste liquid treatment method based on by-product recycling according to any one of claims 1-8, characterized in that, The step of adding the seed crystal suspension to the subsequent etching waste liquid composition control treatment process and participating in the formation of copper sulfate crystals to obtain subsequent batches of finished copper sulfate products includes: In the subsequent acidification treatment stage of etching waste liquid composition control, the seed crystal suspension is introduced into the acidification reaction system; The acidification reaction system in which the seed crystal suspension was added was stirred to ensure that the seed crystal particles of the seed crystal suspension were evenly distributed in the acidification reaction system. The acidification reaction system was subjected to thermal filtration to separate solid impurities and obtain copper sulfate acidification filtrate containing the seed crystal particles. The copper sulfate acidification filtrate is subjected to crystallization, centrifugation, and drying to obtain the subsequent batches of finished copper sulfate product.

10. An etching waste liquid treatment system based on by-product recycling, characterized in that, The system includes: A pretreatment device is used to pretreat etching waste liquid to remove suspended and insoluble impurities. A component control device is used to control the composition of pretreated etching waste liquid to obtain copper sulfate acidified filtrate that meets crystallization requirements. The component control device includes a neutralization device, an ammonia conversion device, a pulping device, an acidification device, and a thermal filtration device. A crystallization processing device for obtaining copper sulfate finished product and copper sulfate non-crystalline powder based on the copper sulfate acidification filtrate; A seed suspension preparation apparatus for obtaining a seed suspension based on the copper sulfate amorphous powder; A reflux device is used to feed the seed crystal suspension into the subsequent etching waste liquid composition control process and to participate in the formation of copper sulfate crystals.

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