A device and method for recycling nitric acid type tin stripping waste liquid

Abstract

The present invention discloses a method and device for recycling nitric acid type tin stripping waste liquid, the method comprising: step S1: subjecting the tin stripping waste liquid to electrodialysis treatment to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid enriched liquid; step S2: adding a strong electrolyte to the metastannic acid enriched liquid to flocculate the metastannic acid; step S3: recovering the metastannic acid obtained by flocculation; step S4: recovering the metals and / or nitrates in the filtrate from step S1 to step S3. In the present invention, the method uses electrodialysis technology to separate metastannic acid from other ions in the waste liquid, and at the same time, under the action of a strong electric field, the metastannic acid colloid migrates toward the electrode direction opposite to its own charge, and moves relative to the liquid phase, so that the metastannic acid is enriched and purified, and then the enriched metastannic acid concentrated solution is collected separately, and a strong electrolyte is added at the same time, so that the metastannic acid is more effectively flocculated, thereby realizing the recovery of the metastannic acid.

Description

Technical Field

[0001] The invention relates to the field of comprehensive waste liquid treatment, and in particular to a device and method for recycling nitric acid type tin stripping waste liquid. Background Art

[0002] The PCB (printed circuit board) industry is an industry that produces a large amount of industrial waste. The waste liquid pollutants produced are of high concentration, multiple types, and complex composition. Tin stripping is the process that produces the largest amount of wastewater in PCB companies. The tin stripping liquid produced has a high content of heavy metals, a high pollution index, and high free acid acidity. The composition is complex and contains certain promoters, surfactants, nitrogen oxide inhibitors, heavy metal chelating agents, copper corrosion inhibitors and other ingredients. It is difficult to treat it with conventional methods. How to effectively treat waste tin stripping liquid has become a difficult problem faced by hazardous waste companies. Summary of the invention

[0003] In order to solve the existing problems, the present invention provides a device and method for recycling nitric acid type tin stripping waste liquid, the method comprising:

[0004] Step S1: subjecting the tin stripping waste liquid to electrodialysis treatment to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched solution;

[0005] Step S2: adding a strong electrolyte to the metastannic acid enriched solution to cause the metastannic acid to precipitate;

[0006] Step S3: recovering the metastannic acid obtained by coagulation;

[0007] Step S4: recovering the metals and / or nitrates in the filtrate from step S1 to step S3.

[0008] Optionally, in step S1, the DC voltage of the electrodialysis treatment is 0V-60V.

[0009] Optionally, in step S1, after the metastannic acid in the tin stripping waste liquid is separated from other ions in the tin stripping waste liquid, the DC voltage is controlled at 100V-200V.

[0010] Optionally, in step S2, the strong electrolyte includes a nitrate solution.

[0011] Optionally, in step S2, the strong electrolyte is a solution of nitrate recovered in step S4.

[0012] Optionally, in step S2, the added mass of the strong electrolyte is 20%-30% of the mass of the metastannic acid enriched solution.

[0013] Optionally, in step S4, the pH of the filtrate obtained from steps S1 to S3 is adjusted to neutral to recover heavy metals in the filtrate.

[0014] Optionally, an impurity remover is added to the filtrate obtained by recovering heavy metals to remove heavy metals and organic matter, and at the same time, the nitrate filtrate is recovered and nitrate is obtained by evaporation and crystallization.

[0015] Optionally, the impurity remover is activated carbon.

[0016] The present application also provides a device for recycling nitric acid type tin stripping waste liquid, the device comprising:

[0017] An electrodialysis device, wherein the electrodialysis device is used to perform electrodialysis treatment on the tin stripping waste liquid to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched solution;

[0018] A coagulation reactor, the coagulation reactor is connected to the electrodialysis device, and is used to receive the metastannic acid enriched solution, and a strong electrolyte is added to the coagulation reactor to coagulate the metastannic acid;

[0019] A centrifugal device for recovering the metastannic acid after flocculation;

[0020] A recovery device is used to recover metals and / or nitrates in the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device.

[0021] Optionally, the electrodialysis device comprises a semipermeable membrane, and the semipermeable membrane is used to isolate the tin stripping waste liquid and process water located on both sides of the semipermeable membrane.

[0022] Optionally, a partition plate is provided at the bottom of the electrodialysis device to separate the metastannic acid-enriched liquid from the residual liquid.

[0023] Optionally, the recovery device comprises a neutralization reactor, which receives the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device, and adjusts the pH of the filtrate to neutral.

[0024] Optionally, the recovery device includes a solid-liquid separator, which receives the filtrate whose pH is adjusted to neutral, and is used to perform solid-liquid separation on the filtrate to obtain heavy metals.

[0025] Optionally, the recovery device includes an impurity removal reactor, which is used to add an impurity remover to the filtrate obtained from the solid-liquid separator to remove heavy metals and organic matter.

[0026] Optionally, the recovery device includes a filter press for separating heavy metals and organic matter in the impurity removal reactor.

[0027] Optionally, the recovery device includes an evaporation crystallizer for receiving the filtrate produced by the filter press and performing evaporation and crystallization to obtain distilled water and nitrate.

[0028] Optionally, the strong electrolyte is the nitrate obtained in the evaporative crystallizer.

[0029] Optionally, the device further comprises a cooling system, and the distilled water obtained in the evaporation crystallizer passes through the cooling system and is then recycled to the electrodialysis device as the process water.

[0030] Optionally, the impurity remover is activated carbon.

[0031] The method described in the present invention uses electrodialysis technology to separate metastannic acid from other ions in the waste liquid. At the same time, under the action of a strong electric field, the metastannic acid colloid migrates toward the electrode direction opposite to its own charge and moves relative to the liquid phase, so that the metastannic acid is enriched and purified, and the enriched metastannic acid concentrate is collected separately. At the same time, a strong electrolyte is added to make the metastannic acid more effectively precipitated, thereby realizing the recovery of the metastannic acid.

[0032] The advantages of the present invention are:

[0033] 1. Effective separation of tin from other components in the tin stripping waste liquid. Existing methods such as direct neutralization precipitation, heating tin precipitation, adding electrolytes or simple polymer coagulation to precipitate tin either fail to effectively separate tin, have high energy efficiency and low efficiency, or introduce impurities during the treatment process. The present invention uses a strong nitrate electrolyte added on the basis of electrodialysis to effectively separate and enrich metastannic acid from other components in the waste liquid.

[0034] 2. High product quality, comprehensive recycling and utilization. Nitrate of the same system as the tin stripping waste liquid is used as a strong electrolyte, and the copper precipitation neutralizer is selected to correspond to the strong electrolyte system. No other impurity ions are introduced during the treatment process, which greatly improves the quality of nitrate products.

[0035] 3. Realize the reuse of products and water, greatly reducing costs. Part of the nitrate product is reused in the coagulation process as a strong electrolyte, and the distilled water is reused as process water for electrodialysis, realizing the reuse within the system and greatly reducing production costs.

[0036] 4. Environmentally friendly and easy to promote. Compared with the heating tinning method, it does not have environmental problems such as low efficiency, energy consumption, and waste gas, and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following drawings of the present invention are used to understand the present invention as part of the present invention. The embodiments of the present invention are shown in the drawings and the description thereof is used to explain the principle of the present invention.

[0038] In the attached figure:

[0039] Figure 1 A schematic flow chart of a method for recycling nitric acid type tin stripping waste liquid of the present invention;

[0040] Figure 2 It is a schematic structural diagram of the device for recycling nitric acid type tin stripping waste liquid of the present invention.

[0041] Figure ID

[0042] 1. Electrodialysis device

[0043] 2. Coagulation reactor

[0044] 3. The first mortar pump

[0045] 4. The first centrifuge

[0046] 5. Neutralization Reactor

[0047] 6. Second mortar pump

[0048] 7. The first filter press

[0049] 8. Impurity removal reactor

[0050] 9. The third mortar pump

[0051] 10. Second filter press

[0052] 11. Evaporation crystallizer

[0053] 12. Fourth mortar pump

[0054] 13. Vacuum pump

[0055] 14. Second centrifuge DETAILED DESCRIPTION

[0056] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0057] It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0058] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0059] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0060] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0061] Embodiments of the invention are described herein with reference to cross-sectional views that are schematic diagrams of ideal embodiments (and intermediate structures) of the invention. Thus, variations from the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the invention should not be limited to the specific shapes of the zones shown herein, but include shape deviations due to, for example, manufacturing. Therefore, the zones shown in the figures are schematic in nature, and their shapes are not intended to display the actual shapes of the zones of the device and are not intended to limit the scope of the invention.

[0062] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0063] In the tin stripping process, the main metal component in the tin stripping waste liquid is tin, which is also the main object of recycling. In the PCB tin stripping process, the principle of tin being "stripped" by nitric acid-type tin stripping water is mainly the oxidation of metallic tin by dilute nitric acid under the condition of an oxidant to produce Sn 2+It is the initial form of tin ions after tin stripping. At the same time, there are some pairs of electrodes in the tin stripping waste liquid system whose electrode potentials are relatively high. 4+ / Sn 2+ So Sn 2+ Easily oxidized to Sn 4+ When the acidity of the system decreases, it hydrolyzes into Sn(H 2 O) 2 (OH) 4 (White orthostannic acid precipitate, amphoteric, soluble in acid or alkali). Orthostannic acid becomes metastannic acid after being left to lose water. Metastannic acid has two types, α and β. Among them, α-type metastannic acid is amorphous, soluble in acid and alkali, but insoluble in water. β-type metastannic acid has a crystalline structure, which is difficult to dissolve in acid and alkali, and insoluble in water. α-stannic acid belongs to the thermodynamic metastable phase and can be easily transformed into β-stannic acid.

[0064] As the tin stripping water is used for a longer time, tin (β-stannic acid) and other heavy metals, impurities, etc. are enriched, affecting the tin stripping effect. It needs to be replaced with new liquid, and the generated tin stripping waste liquid needs to be sent to a hazardous waste disposal company for comprehensive recycling and disposal.

[0065] From the above, we can see that the tin-stripping waste liquid in the comprehensive disposal of hazardous waste is mainly the waste liquid that has become ineffective and cannot be reused after long-term use in circuit board factories. A large amount of valuable metal tin exists in the form of parastannic acid (β-stannic acid).

[0066] In the research on the treatment of waste tin stripping water, direct neutralization precipitation, heating precipitation, electrolyte addition or simple polymer coagulation are generally used to precipitate tin. The heating precipitation method has a relatively narrow application range, and the separation rate is low for colloid particles that are not obvious; adding electrolytes, currently mostly sulfates, phosphates, etc., not only introduces impurity ions, affecting the quality of subsequent products, but also increases the processing cost; simple polymer flocculation method has poor precipitation effect for precipitates without obvious particle distribution; centrifugal separation has a certain effect on wastewater with large colloidal particles and obvious floccules, but it is very poor for other wastewaters with more uniform colloidal distribution.

[0067] How to avoid adding additional chemicals during the disposal of tin stripping waste liquid, how to achieve effective separation of tin in the tin stripping waste liquid and comprehensive recycling of other wastes, and ensure the quality of recycled products have become the key to achieving comprehensive recycling of tin stripping waste liquid.

[0068] In order to solve the problems existing in the prior art, the present invention provides a method for recycling nitric acid type tin stripping waste liquid, such as Figure 1 As shown, the method includes:

[0069] Step S1: subjecting the tin stripping waste liquid to electrodialysis treatment to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched solution;

[0070] Step S2: adding a strong electrolyte to the metastannic acid enriched solution to cause the metastannic acid to precipitate;

[0071] Step S3: recovering the metastannic acid obtained by coagulation;

[0072] Step S4: recovering the metals and / or nitrates in the filtrate from step S1 to step S3.

[0073] The method described in the present invention uses electrodialysis technology to separate metastannic acid from other ions in the waste liquid. At the same time, under the action of a strong electric field, the metastannic acid colloid migrates toward the electrode direction opposite to its own charge and moves relative to the liquid phase, so that the metastannic acid is enriched and purified, and the enriched metastannic acid concentrate is collected separately. At the same time, a strong electrolyte is added to make the metastannic acid more effectively precipitated, thereby realizing the recovery of the metastannic acid.

[0074] The advantages of the present invention are:

[0075] 1. Effective separation of tin from other components in the tin stripping waste liquid. Existing methods such as direct neutralization precipitation, heating tin precipitation, adding electrolytes or simple polymer coagulation to precipitate tin either fail to effectively separate tin, have high energy efficiency and low efficiency, or introduce impurities during the treatment process. The present invention uses a strong nitrate electrolyte added on the basis of electrodialysis to effectively separate and enrich metastannic acid from other components in the waste liquid.

[0076] 2. High product quality, comprehensive recycling and utilization. Nitrate of the same system as the tin stripping waste liquid is used as a strong electrolyte, and the copper precipitation neutralizer is selected to correspond to the strong electrolyte system. No other impurity ions are introduced during the treatment process, which greatly improves the quality of nitrate products.

[0077] 3. Realize the reuse of products and water, greatly reducing costs. Part of the nitrate product is reused in the coagulation process as a strong electrolyte, and the distilled water is reused as process water for electrodialysis, realizing the reuse within the system and greatly reducing production costs.

[0078] 4. Environmentally friendly and easy to promote. Compared with the heating tinning method, it does not have environmental problems such as low efficiency, energy consumption, and waste gas, and is easy to promote.

[0079] The following is a detailed description of the method for recycling the nitric acid type tin stripping waste liquid of the present invention. In the method for recycling the nitric acid type tin stripping waste liquid, Figure 1 As shown, in step S1, the tin stripping waste liquid is first added to the electrodialysis device 1, and the electrodialysis technology is used to separate the metastannic acid from other ions in the waste liquid, and then the voltage is increased.

[0080] For example, in this step, a semipermeable membrane is provided in the electrodialysis device 1 , and after the tin stripping waste liquid is pumped into the electrodialysis reactor, the semipermeable membrane separates the waste liquid from the process water.

[0081] Then pass direct current and control the voltage to 10-60V. When direct current is passed, ions migrate in the direction opposite to the charge and pass through the semipermeable membrane to both sides. At this time, water should be changed continuously to improve dialysis efficiency. After 120 minutes of reaction, increase the voltage to 100V. Under the action of a higher voltage electric field, the positively charged metastannic acid quickly moves to the cathode and is enriched.

[0082] After 10 minutes of reaction, the metastannic acid enriched liquid is collected and sampled separately to detect the content of each ion in the tin stripping waste liquid. After achieving the expected effect, step S2 is executed to transfer the metastannic acid refined enriched liquid separately to the coagulation reactor 2, and a strong electrolyte is added to the metastannic acid enriched liquid to coagulate the metastannic acid.

[0083] Specifically, in this step, a strong electrolyte is added under stirring conditions, and the amount of the strong electrolyte added is about 20%-30% of the refined metastannic acid solution. After stirring and reacting for a while, the metastannic acid quickly precipitates, and after standing and stratifying for 30 minutes, centrifugal separation and washing are performed to obtain high-quality metastannic acid.

[0084] In step S2, the strong electrolyte includes a nitrate solution, wherein the nitrate obtained in step S4 is reused as the strong electrolyte.

[0085] In step S4, the centrifugal filtrate and the electrodialysis liquid are combined into a tin precipitation liquid, sodium hydroxide is added to the tin precipitation liquid to produce a neutralization reaction, and the valuable metal copper in the waste liquid is filtered and recovered; activated carbon is added to the copper precipitation liquid to adsorb impurities such as organic matter in the waste liquid, and the refined sodium nitrate liquid is obtained by filtration. After evaporation, concentration and crystallization, a sodium nitrate product is obtained, and the distilled water is reused as process water in the electrodialysis process.

[0086] An impurity remover is added to the filtrate obtained by recovering heavy metals to remove heavy metals and organic matter, and the nitrate filtrate is recovered at the same time, and nitrate is obtained by evaporation and crystallization. The impurity remover is activated carbon.

[0087] The method for comprehensive recycling of nitric acid type tin stripping waste liquid, through electrodialysis, to achieve effective separation and enrichment of metastannic acid and other ions in the waste liquid, to obtain metastannic acid enriched refined liquid; metastannic acid refined enriched liquid adds the nitrate product recovered from the waste liquid as a strong electrolyte, metastannic acid is effectively flocculated, thereby obtaining high-grade metastannic acid, and tin is effectively recycled; the liquid after tin precipitation is neutralized and recovered by a neutralizer consistent with the system, and activated carbon is removed, and then the nitrate product is recovered from the refined liquid, and the nitrate is resourced, realizing the comprehensive recycling of tin stripping waste liquid. In addition, the method is environmentally friendly, and the same system materials are used during the treatment process, no impurities are introduced, and the product quality is high. At the same time, distilled water and nitrate are recycled, which greatly reduces the processing cost, so the method is suitable for large-scale production.

[0088] The present invention also provides a device for recycling nitric acid type tin stripping waste liquid, the device comprising:

[0089] An electrodialysis device, wherein the electrodialysis device is used to perform electrodialysis treatment on the tin stripping waste liquid to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched solution;

[0090] A coagulation reactor, the coagulation reactor is connected to the electrodialysis device, and is used to receive the metastannic acid enriched solution, and a strong electrolyte is added to the coagulation reactor to coagulate the metastannic acid;

[0091] A centrifugal device for recovering the metastannic acid after coagulation;

[0092] A recovery device is used to recover metals and / or nitrates in the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device.

[0093] The electrodialysis device comprises a semipermeable membrane, and the semipermeable membrane is used to isolate the tin stripping waste liquid and process water located on both sides of the semipermeable membrane.

[0094] Optionally, a partition plate is provided at the bottom of the electrodialysis device to separate the metastannic acid enriched liquid from the residual liquid. The recovery device includes a neutralization reactor, which receives the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device, and adjusts the pH of the filtrate to neutral. The recovery device includes a solid-liquid separator, which receives the filtrate whose pH is adjusted to neutral, and is used to perform solid-liquid separation on the filtrate to obtain heavy metals. The recovery device includes an impurity removal reactor, which is used to add an impurity remover to the filtrate obtained by the solid-liquid separator to remove heavy metals and organic matter. The recovery device includes a filter press, which is used to separate the heavy metals and organic matter removed in the impurity removal reactor. The recovery device includes an evaporation crystallizer, which is used to receive the filtrate produced by the filter press and evaporate and crystallize to obtain distilled water and nitrates.

[0095] Optionally, the device further comprises a cooling system, and the distilled water obtained in the evaporation crystallizer passes through the cooling system and is then recycled to the electrodialysis device as the process water. The impurity remover is activated carbon.

[0096] Specifically, Figure 1 As shown, in the device, the tin stripping waste liquid is added to the electrodialysis device 1, and the electrodialysis technology is used to separate the metastannic acid from other ions in the waste liquid. Then, the voltage is increased and a strong electrolyte is added to make the metastannic acid more effectively precipitated in the precipitator reactor 2. The metastannic acid is recovered by the first mortar pump 3 in the first centrifuge 4. The centrifugal filtrate, the electrodialysis liquid, and the electrophoresis residual liquid are collected in the neutralization reactor 5. The pH is controlled to be neutral to recover heavy metals such as copper. The metal copper is recovered by the solid-liquid separation of the first filter press 7 through the second mortar pump 6. The filtrate is transferred to the impurity removal reactor 8, and an impurity remover is added to remove heavy metals and organic matter. The filtrate is pumped to the second filter press 10 through the third mortar pump 9 to separate and recover the nitrate filtrate, which is transferred to the evaporation crystallizer 11, evaporated and concentrated until nitrate crystals are precipitated. After cooling, it is transferred to the second centrifuge 14 through the fourth mortar pump 12 to separate and recover the nitrate product. The distilled water is pumped to the cooling system through the vacuum pump 13 and then reused in the electrodialysis system.

[0097] Embodiment 1

[0098] Using nitric acid type tin stripping waste liquid as raw material, the main component content (g / t) is shown in Table 1; the specific steps are as follows:

[0099] Remove the tin stripping waste liquid 5m 3 Pumped into the electrodialysis reactor, the semipermeable membrane separates the waste liquid from the process water, direct current is passed, and the control voltage is 10V. When direct current is passed, the ions migrate in the opposite direction of charge and pass through the semipermeable membrane to both sides. At this time, the water should be changed continuously to improve the dialysis efficiency. After 120 minutes of reaction, the voltage is increased to 100V. Under the action of a higher voltage electric field, the positively charged metastannic acid quickly moves to the cathode and is enriched. After 10 minutes of reaction, the enriched liquid is separately collected and sampled to detect the content of each ion in the tin-stripping waste liquid. After achieving the expected effect, the metastannic acid refined enriched liquid is separately transferred to the coagulation reactor; A strong electrolyte, sodium nitrate, is added under stirring, and the amount of sodium nitrate added is about 25% of the refined metastannic acid solution. After stirring and reacting for a while, the metastannic acid is rapidly precipitated, and after standing and stratifying for 30 minutes, it is centrifuged and washed to obtain high-quality metastannic acid; the centrifugal filtrate and the electrodialysis liquid are combined into a post-tin precipitation liquid, sodium hydroxide is added to the post-tin precipitation liquid to undergo a neutralization reaction, and the valuable metal copper in the waste liquid is filtered and recovered; activated carbon is added to the post-copper precipitation liquid to adsorb impurities such as organic matter in the waste liquid, and a refined sodium nitrate solution is obtained by filtration. After evaporation, concentration and crystallization, a sodium nitrate product 1 is obtained, and the distilled water is reused as process water in the electrodialysis process.

[0100] Table 1 Electrodialysis treatment test results

[0101]

[0102] It can be seen from Table 1 that after electrodialysis and electrophoresis, tin and waste liquid are effectively separated, and tin is enriched.

[0103] Table 2 Tin precipitation effect of metastannic acid treatment

[0104]

[0105] It can be seen from Table 2 that after strong electrolyte coagulation, tin is effectively precipitated and recovered.

[0106] Embodiment 2

[0107] Using nitric acid type tin stripping waste liquid as raw material, the main component content and its electrodialysis and coagulation treatment effects are shown in Table 3; the specific steps are as follows:

[0108] 5m3 of tin stripping waste liquid is pumped into the electrodialysis reactor. The semipermeable membrane separates the waste liquid from the process water. Direct current is passed with a control voltage of 30V. When direct current is passed, ions migrate in the direction opposite to the charge and pass through the semipermeable membrane to both sides. At this time, the water should be changed continuously to improve the dialysis efficiency. At the same time, under the action of the electric field, the charged metastannic acid moves to the opposite electrode and is enriched. After 60 minutes of reaction, the enriched liquid is collected and sampled separately to detect the content of each ion in the tin stripping waste liquid. After the nitrate ions are reduced to the expected effect, the tin-containing refined enriched liquid is transferred to the coagulation reactor separately; the stirring bar is Electrolyte sodium nitrate is added under the following conditions, and the amount of sodium nitrate added is about 30% of the refined metastannic acid liquid. After stirring and reacting for a while, the metastannic acid quickly precipitates. After standing and stratifying for 30 minutes, it is centrifuged and washed to obtain high-quality metastannic acid; the centrifugal filtrate and the electrodialysis liquid are combined to form a post-tin precipitation liquid, and sodium hydroxide is added to the post-tin precipitation liquid to undergo a neutralization reaction, and at the same time, the valuable metal copper in the waste liquid is filtered and recovered; activated carbon is added to the post-copper precipitation liquid to adsorb impurities such as organic matter in the waste liquid, and the refined sodium nitrate liquid is obtained by filtration. After evaporation, concentration and crystallization, the sodium nitrate product 2 is obtained, and the distilled water is reused as process water in the electrodialysis process.

[0109] Table 3 Electrodialysis treatment test results

[0110]

[0111] It can be seen from Table 3 that after electrodialysis and electrophoresis, tin and waste liquid are effectively separated, and tin is enriched.

[0112] Table 4 Tin precipitation effect of metastannic acid treatment

[0113]

[0114] It can be seen from Table 4 that after strong electrolyte coagulation, tin is effectively precipitated and recovered.

[0115] Embodiment 3

[0116] Using nitric acid type tin stripping waste liquid as raw material, the main component content and its electrodialysis and coagulation treatment effects are shown in Table 5. The specific steps are as follows:

[0117] 5m3 of tin stripping waste liquid is pumped into the electrodialysis reactor. The semipermeable membrane separates the waste liquid from the process water. Direct current is passed with a control voltage of 30V. When direct current is passed, ions migrate in the direction opposite to the charge and pass through the semipermeable membrane to both sides. At this time, the water should be changed continuously to improve the dialysis efficiency. At the same time, under the action of the electric field, the charged metastannic acid moves to the opposite pole and is enriched. After 60 minutes of reaction, the enriched liquid is collected and sampled separately to detect the content of each ion in the tin stripping waste liquid. After it drops to the expected effect, the tin-containing refined enriched liquid is transferred to the coagulation reactor separately; add under stirring conditions. Add electrolyte ammonium nitrate, the amount of ammonium nitrate added is about 25% of the refined metastannic acid liquid, stir and react for a while, the metastannic acid quickly precipitates, and after standing and stratifying for 30 minutes, centrifuge and wash to obtain high-quality metastannic acid; the centrifugal filtrate and the electrodialysis liquid are combined into the post-tin precipitation liquid, ammonia water is added to the post-tin precipitation liquid to produce a neutralization reaction, and the valuable metal copper in the waste liquid is filtered and recovered at the same time; activated carbon is added to the post-copper precipitation liquid to adsorb impurities such as organic matter in the waste liquid, and the refined ammonium nitrate liquid is obtained by filtration. After evaporation, concentration and crystallization, the ammonium nitrate product is obtained, and the distilled water is reused as process water in the electrodialysis process.

[0118] Table 5 Electrodialysis treatment test results

[0119]

[0120] It can be seen from Table 5 that after electrodialysis, tin and waste liquid are effectively separated, and tin is enriched at the same time.

[0121] Table 6 Effect of tin precipitation by metastannic acid treatment

[0122]

[0123] It can be seen from Table 6 that after strong electrolyte coagulation, tin is effectively precipitated and recovered.

[0124] Through the above examples, it can be seen that the present invention, on the basis of electrodialysis, adds a strong electrolyte of nitrate, and the metastannic acid and other components in the waste liquid are effectively separated and enriched. Nitrate of the same system as the tin stripping waste liquid is used as a strong electrolyte, and the copper precipitation neutralizer is selected to correspond to the strong electrolyte system. No other impurity ions are introduced during the treatment process, which greatly improves the quality of the nitrate product.

[0125] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for recycling nitric acid type tin stripping waste liquid, It is characterized in that The method comprises: Step S1: subjecting the tin stripping waste liquid to electrodialysis treatment to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched liquid, wherein the DC voltage of the electrodialysis treatment is 0V-60V, and after the metastannic acid in the tin stripping waste liquid is separated from other ions in the tin stripping waste liquid, the DC voltage is controlled at 100V-200V; Step S2: adding a strong electrolyte to the metastannic acid enriched solution under stirring conditions to cause the metastannic acid to precipitate; Step S3: recovering the metastannic acid obtained by precipitating by centrifugal separation and washing; Step S4: recovering the metals and / or nitrates in the filtrate from step S1 to step S3.

2. The method according to claim 1, It is characterized in that In the step S2, the strong electrolyte includes a nitrate solution.

3. The method according to claim 2, It is characterized in that In the step S2, the strong electrolyte is the nitrate solution recovered in the step S4.

4. The method according to claim 2, It is characterized in that In the step S2, the added mass of the strong electrolyte is 20%-30% of the mass of the metastannic acid enriched solution.

5. The method according to claim 1, It is characterized in that In the step S4, the pH of the filtrate obtained from the steps S1 to S3 is adjusted to be neutral to recover the heavy metals in the filtrate.

6. The method according to claim 5, It is characterized in that An impurity remover is added to the filtrate obtained by recovering heavy metals to remove heavy metals and organic matter, and at the same time, the nitrate filtrate is recovered and nitrate is obtained by evaporation and crystallization.

7. The method according to claim 6, It is characterized in that The impurity remover is activated carbon.

8. A device for recycling nitric acid type tin stripping waste liquid, It is characterized in that The device comprises: An electrodialysis device, wherein the electrodialysis device is used to perform electrodialysis treatment on the tin stripping waste liquid to separate the metastannic acid in the tin stripping waste liquid from other ions in the tin stripping waste liquid to obtain a metastannic acid-enriched liquid, wherein the DC voltage of the electrodialysis treatment is 0V-60V, and after the metastannic acid in the tin stripping waste liquid is separated from other ions in the tin stripping waste liquid, the DC voltage is controlled at 100V-200V; A coagulation reactor, the coagulation reactor is connected to the electrodialysis device, and is used to receive the metastannic acid enriched solution, and add a strong electrolyte into the coagulation reactor under stirring conditions to coagulate the metastannic acid; A centrifugal device, used for recovering the metastannic acid after precipitating by centrifugal separation, washing and coagulation; A recovery device is used to recover metals and / or nitrates in the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device.

9. The device according to claim 8, It is characterized in that The electrodialysis device comprises a semipermeable membrane, and the semipermeable membrane is used to isolate the tin stripping waste liquid and process water located on both sides of the semipermeable membrane.

10. The device according to claim 9, It is characterized in that A partition plate is arranged at the bottom of the electrodialysis device to separate the metastannic acid-enriched liquid from the residual liquid.

11. The device according to claim 9, It is characterized in that The recovery device comprises a neutralization reactor, which receives the filtrate produced in the electrodialysis device, the coagulation reactor and the centrifugal device and adjusts the pH of the filtrate to neutral.

12. The device according to claim 11, It is characterized in that The recovery device comprises a solid-liquid separator, which receives the filtrate whose pH is adjusted to neutral and is used to perform solid-liquid separation on the filtrate to obtain heavy metals.

13. The device according to claim 12, It is characterized in that The recovery device comprises an impurity removal reactor, which is used to add an impurity remover to the filtrate obtained from the solid-liquid separator to remove heavy metals and organic matter.

14. The device according to claim 13, It is characterized in that The recovery device comprises a filter press for separating heavy metals and organic matter in the impurity removal reactor.

15. The device according to claim 14, It is characterized in that The recovery device comprises an evaporation crystallizer, which is used for receiving the filtrate produced by the filter press and performing evaporation and crystallization to obtain distilled water and nitrate.

16. The device according to claim 15, It is characterized in that The strong electrolyte is the nitrate obtained in the evaporative crystallizer.

17. The device according to claim 15, It is characterized in that The device also includes a cooling system, and the distilled water obtained in the evaporation crystallizer passes through the cooling system and then is recycled to the electrodialysis device as the process water.

18. The device according to claim 13, It is characterized in that The impurity remover is activated carbon.

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