阅读说明：本技术 一种硝酸退镀液循环再利用系统及方法 (Nitric acid deplating liquid recycling system and method ) 是由 颜运能 司波 于 2019-08-30 设计创作，主要内容包括：本发明提供了一种硝酸退镀液循环再利用系统及方法,包括退渡槽；退镀液储罐；浓硫酸储罐；冷冻结晶装置；第一固液分离装置；蒸馏装置；冷凝器；馏出液存储罐；溶解槽；第一电解装置；置换装置；第二固液分离装置；第二电解装置。本发明中,首先通过向退镀液中加入浓硫酸,使得其中的硝酸盐转化为硫酸盐,然后降温使硫酸盐析出,实现固液分离,分离后的溶液经过蒸馏与冷却,获得纯净的硝酸溶液,固液分离得到的晶体溶解后进行电解,使单质铜析出,再通过镍置换法出去溶液中的杂质金属离子,然后进行二次电解,获得单质镍,从而实现了退镀液中的硝酸、铜与镍的回收利用,实现了对退镀液的无害化处理。(The invention provides a nitric acid deplating liquid recycling system and a nitric acid deplating liquid recycling method, wherein the nitric acid deplating liquid recycling system comprises a deplating groove; a deplating liquid storage tank; a concentrated sulfuric acid storage tank; a freezing and crystallizing device; a first solid-liquid separation device; a distillation apparatus; a condenser; a distillate storage tank; a dissolving tank; a first electrolysis device; a displacement device; a second solid-liquid separation device; a second electrolysis device. According to the invention, concentrated sulfuric acid is added into the stripping solution to convert nitrate in the stripping solution into sulfate, then the temperature is reduced to separate out the sulfate, solid-liquid separation is realized, the separated solution is distilled and cooled to obtain a pure nitric acid solution, crystals obtained by solid-liquid separation are dissolved and then are electrolyzed to separate out elemental copper, impurity metal ions in the solution are removed by a nickel replacement method, and then secondary electrolysis is carried out to obtain elemental nickel, so that the recycling of nitric acid, copper and nickel in the stripping solution is realized, and the harmless treatment of the stripping solution is realized.)

1. A nitric acid deplating liquid recycling system is characterized in that: comprises that

A transition groove is withdrawn;

the deplating liquid storage tank is used for receiving the deplating liquid output by the deplating groove;

the concentrated sulfuric acid storage tank is used for providing a preset amount of concentrated sulfuric acid into the deplating solution storage tank so as to convert nitrate in the deplating solution into sulfate and free nitric acid;

the freezing and crystallizing device is used for cooling the deplating liquid added with the concentrated sulfuric acid so as to separate out sulfate crystals;

the first solid-liquid separation device is used for separating sulfate crystals from free nitric acid to obtain sulfate crystals and a nitric acid solution;

the distillation device is used for distilling the nitric acid solution obtained by the first solid-liquid separation device;

the inlet of the condenser is connected to the outlet of the distillation device and is used for collecting nitric acid steam output by the distillation device;

the distillate storage tank is used for collecting the distillate output by the condenser;

the dissolving tank is used for dissolving the sulfate crystals obtained by the first solid-liquid separation device to obtain a sulfate solution;

the first electrolysis device is used for electrolyzing copper sulfate in the sulfate solution output by the dissolving tank;

the replacement device is used for adding solid nickel into the solution output by the first electrolysis device to replace impurity metal ions in the solution and obtain a nickel sulfate solution and impurity solid metal;

the second solid-liquid separation device is used for separating the nickel sulfate solution from impurity solid metal;

and the second electrolysis device is used for electrolyzing the nickel sulfate solution.

2. A nitric acid deplating solution recycling system according to claim 1, wherein: the concentration adjusting device is used for adjusting the nitric acid distillate stored in the distillate storage tank and the concentrated nitric acid output by the concentrated nitric acid storage tank according to a preset proportion, and inputting the nitric acid distillate and the concentrated nitric acid into the transition groove.

3. A nitric acid deplating solution recycling system according to claim 1, wherein: the distillation device is also used for outputting the distilled concentrated solution to the freezing and crystallizing device.

4. A nitric acid deplating solution recycling system according to claim 1, wherein: still include regeneration sulphuric acid storage jar, regeneration sulphuric acid storage jar is used for the storage the solution of first electrolytic device output, regeneration sulphuric acid storage jar still is used for exporting to the deplating liquid storage tank after the concentrated sulfuric acid in solution and the concentrated sulfuric acid storage tank mixes with preset proportion.

5. A nitric acid deplating solution recycling system according to claim 1, wherein: the solid nickel is nickel powder.

6. A nitric acid deplating liquid recycling method is characterized in that: comprises that

Adding sulfuric acid with preset concentration into the deplating solution according to a preset proportion so as to convert nitrate in the deplating solution into sulfate and free nitric acid and obtain a nitric acid solution containing sulfate;

crystallizing and separating out sulfate by cooling and freezing;

carrying out solid-liquid separation on the sulfate crystal and the nitric acid solution;

distilling and condensing the nitric acid solution to obtain pure nitric acid distillate;

electrolyzing the sulfate crystal by using dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution;

after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration, adding a preset amount of simple substance nickel into the sulfuric acid solution to replace impurity metal ions in the sulfuric acid solution, and obtaining sulfuric acid containing nickel sulfate and impurity solid metal;

carrying out solid-liquid separation on the sulfuric acid solution and impurity solid metal;

and electrolyzing the sulfuric acid solution to obtain the simple substance nickel.

7. A method of recycling a nitric acid deplating solution according to claim 6, wherein: and the method also comprises the step of blending the nitric acid distillate and the concentrated nitric acid according to a preset proportion to obtain nitric acid with a preset concentration and then inputting the nitric acid into a reduction tank.

8. A method of recycling a nitric acid deplating solution according to claim 6, wherein: after the nitric acid solution is distilled and condensed to obtain pure nitric acid distillate, the method also comprises the step of cooling and freezing the residual concentrated solution after distillation to separate out sulfate crystals.

9. A method of recycling a nitric acid deplating solution according to claim 6, wherein: the method comprises the steps of electrolyzing sulfate crystals by using dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, mixing the sulfuric acid solution and sulfuric acid with a preset concentration according to a preset proportion, and adding deplating liquid.

10. A method of recycling a nitric acid deplating solution according to claim 6, wherein: the method comprises the step of adding a preset amount of sulfuric acid into the nitric acid solution before distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate.

Technical Field

The invention relates to the technical field of nitric acid deplating liquid circulating equipment, in particular to a nitric acid deplating liquid recycling system and a nitric acid deplating liquid recycling method.

Background

The nitric acid stripping solution mainly exists in PCB and electroplating industries, and is a stripping waste liquid generated by dissolving a plating layer on an electroplating hanger by nitric acid and dissolving a plating layer on an electroplated defective product by nitric acid.

The electroplating rack is a hanging tool and a conductive tool for electroplating, metal coatings such as copper, nickel and the like are deposited in the process of immersing various electroplating solutions and chemical plating solutions, and when the thicknesses reach a certain value, deplating is needed. When a poor plating layer is generated, the plated piece is scrapped, and the plating layer on the poor plated piece is usually stripped, namely deplating, and then returning to the secondary processing. The electroplating hanger and the base material are also mainly made of iron, stainless steel and aluminum materials, a copper layer and a nickel layer on the surface of the hanger or a poor plated part can be stripped at one time by using nitric acid, and the hanger or the base material cannot be damaged due to passivation of the nitric acid on the surface of the iron, stainless steel and aluminum materials, so that the nitric acid is widely used for deplating at present. When the nitric acid stripping solution is used for a period of time, the concentrations of copper nitrate and nickel nitrate are gradually increased, so that the dissolving speeds of copper and nickel in nitric acid are inhibited, and when the speeds cannot meet the production requirement, the fresh nitric acid stripping solution is replaced. The deplating waste liquid generated in the deplating process contains a large amount of heavy metals (copper and nickel) and total nitrogen (nitrate radical), and if the deplating waste liquid is not properly treated, the ecological environment can be seriously damaged.

At present, the treatment method of nitric acid deplating waste liquor mainly comprises an acid-base neutralization precipitation method and an electrolysis method. The acid-base neutralization precipitation method can only remove heavy metals in the waste liquid, and has the defects that the generated waste water contains high-concentration nitrate ions and cannot be removed, and the total nitrogen still exceeds the standard. The electrolytic method can separate out copper in the deplating waste liquid on the surface of the cathode plate of the electrolytic bath and recover the copper plate. The method has the disadvantages that nickel and other impurity metals in the waste liquid can not be electrolytically separated out under the acid separation condition, the nickel stripping effect is poor when the electrolyzed nitric acid stripping liquid is recycled, the recycling rate is not high, and the recycling significance is not great.

Method content

According to the defects of the prior art, the invention provides vacuum distillation equipment and a method for treating waste nitric acid, which can realize the recycling of copper, nickel and nitric acid in deplating liquid.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

as a first aspect of the invention, a nitric acid deplating solution recycling system is provided, which comprises

A transition groove is withdrawn;

the deplating liquid storage tank is used for receiving the deplating liquid output by the deplating groove;

the concentrated sulfuric acid storage tank is used for providing a preset amount of concentrated sulfuric acid into the deplating solution storage tank so as to convert nitrate in the deplating solution into sulfate and free nitric acid;

the freezing and crystallizing device is used for cooling the deplating liquid added with the concentrated sulfuric acid so as to separate out sulfate crystals;

the first solid-liquid separation device is used for separating sulfate crystals from free nitric acid to obtain sulfate crystals and a nitric acid solution;

the distillation device is used for distilling the nitric acid solution obtained by the first solid-liquid separation device;

the inlet of the condenser is connected to the outlet of the distillation device and is used for collecting nitric acid steam output by the distillation device;

the distillate storage tank is used for collecting the distillate output by the condenser;

the dissolving tank is used for dissolving the sulfate crystals obtained by the first solid-liquid separation device to obtain a sulfate solution;

the first electrolysis device is used for electrolyzing copper sulfate in the sulfate solution output by the dissolving tank;

the replacement device is used for adding solid nickel into the solution output by the first electrolysis device to replace impurity metal ions in the solution and obtain a nickel sulfate solution and impurity solid metal;

the second solid-liquid separation device is used for separating the nickel sulfate solution from impurity solid metal;

and the second electrolysis device is used for electrolyzing the nickel sulfate solution.

As an optional implementation manner, the system further comprises a concentration adjusting device and a concentrated nitric acid storage tank, wherein the concentration adjusting device is used for adjusting the nitric acid distillate stored in the distillate storage tank and the concentrated nitric acid output by the concentrated nitric acid storage tank according to a preset proportion, and inputting the nitric acid distillate and the concentrated nitric acid into the annealing tank.

As an optional embodiment, the distillation device is further configured to output the distilled concentrated solution to the freezing and crystallizing device.

As an optional implementation manner, the system further comprises a regenerated sulfuric acid storage tank, wherein the regenerated sulfuric acid storage tank is used for storing the solution output by the first electrolysis device, and the regenerated sulfuric acid storage tank is further used for mixing the solution with the concentrated sulfuric acid in the concentrated sulfuric acid storage tank according to a preset proportion and outputting the mixed solution to the deplating solution storage tank.

As an alternative embodiment, the solid nickel is nickel powder.

As a second aspect of the invention, a method for recycling nitric acid deplating solution is provided, which comprises the following steps

Adding sulfuric acid with preset concentration into the deplating solution according to a preset proportion so as to convert nitrate in the deplating solution into sulfate and free nitric acid and obtain a nitric acid solution containing sulfate;

crystallizing and separating out sulfate by cooling and freezing;

carrying out solid-liquid separation on the sulfate crystal and the nitric acid solution;

distilling and condensing the nitric acid solution to obtain pure nitric acid distillate;

electrolyzing the sulfate crystal by using dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution;

after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration, adding a preset amount of simple substance nickel into the sulfuric acid solution to replace impurity metal ions in the sulfuric acid solution, and obtaining sulfuric acid containing nickel sulfate and impurity solid metal;

carrying out solid-liquid separation on the sulfuric acid solution and impurity solid metal;

and electrolyzing the sulfuric acid solution to obtain the simple substance nickel.

As an optional implementation manner, the method further comprises the step of blending the nitric acid distillate and the concentrated nitric acid according to a preset proportion to obtain nitric acid with a preset concentration, and then inputting the nitric acid into the reduction tank.

As an optional implementation manner, after distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate, the method further comprises the step of cooling and freezing the concentrated solution remaining after distillation to crystallize and separate out sulfate therein.

As an optional embodiment, after the sulfate crystal is electrolyzed by using the dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, the method further includes the steps of mixing the sulfuric acid solution and sulfuric acid with a preset concentration according to a preset ratio, and adding the deplating solution.

As an alternative embodiment, before distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate, the method further comprises the step of adding a preset amount of sulfuric acid into the nitric acid solution.

The invention has the beneficial effects that:

according to the invention, concentrated sulfuric acid is added into the stripping solution to convert nitrate in the stripping solution into sulfate, then the temperature is reduced to separate out the sulfate, solid-liquid separation is realized, the separated solution is distilled and cooled to obtain a pure nitric acid solution, crystals obtained by solid-liquid separation are dissolved and then are electrolyzed to separate out elemental copper, impurity metal ions in the solution are removed by a nickel replacement method, and then secondary electrolysis is carried out to obtain elemental nickel, so that the recycling of nitric acid, copper and nickel in the stripping solution is realized, and the harmless treatment of the stripping solution is realized.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a front view of the system of the present embodiment;

FIG. 2 is a flow chart of a method of the present embodiment.

In the figure, 1-a transition tank, 2-a deplating liquid storage tank, 3-a concentrated sulfuric acid storage tank, 4-a freezing and crystallizing device, 5-a first solid-liquid separation device, 6-a distillation device, 7-a condenser, 8-a distillate storage tank, 9-a dissolving tank, 10-a first electrolysis device, 11-a replacement device, 12-a second solid-liquid separation device, 13-a second electrolysis device, 14-a concentration preparation device, 15-a concentrated nitric acid storage tank and 16-a regenerated sulfuric acid storage tank.

Detailed Description

The following description of the embodiments of the present invention provides a more complete, accurate and thorough understanding of the method concept and technical solutions of the present invention by the skilled in the art through the following detailed description of the embodiments, such as the shapes and configurations of the components, the mutual positions and connection relationships of the components, the functions and operating principles of the components, the manufacturing processes and the operation methods.

As a first aspect of the present invention, as shown in FIG. 1, there is provided a nitric acid deplating solution recycling system comprising

A retreat aqueduct 1;

the deplating liquid storage tank 2 is used for receiving the deplating liquid output by the deplating tank 1;

the concentrated sulfuric acid storage tank 3 is used for providing a preset amount of concentrated sulfuric acid into the deplating solution storage tank 2 so as to convert nitrate in the deplating solution into sulfate and free nitric acid;

the freezing and crystallizing device 4 is used for cooling the deplating liquid added with the concentrated sulfuric acid so as to separate out sulfate crystals;

a first solid-liquid separation device 5 for separating sulfate crystals from free nitric acid to obtain sulfate crystals and a nitric acid solution;

a distillation device 6 for distilling the nitric acid solution obtained by the first solid-liquid separation device 5;

a condenser 7, wherein the inlet of the condenser 7 is connected to the outlet of the distillation device 6 and is used for collecting nitric acid steam output by the distillation device 6;

a distillate storage tank 8 for collecting the distillate output by the condenser 7;

a dissolving tank 9 for containing dilute sulfuric acid electrolyte for dissolving the sulfate crystals obtained by the first solid-liquid separation device 5 to obtain a sulfate solution;

a first electrolysis device 10 for electrolyzing copper sulfate in the sulfate solution output from the dissolution tank 9;

a replacement device 11, configured to add solid nickel to the solution output by the first electrolysis device 10 to replace impurity metal ions, such as copper ions, in the solution, and obtain a nickel sulfate solution and impurity solid metal;

a second solid-liquid separation device 12 for separating the nickel sulfate solution from the impurity solid metal;

and a second electrolysis device 13 for electrolyzing the nickel sulfate solution.

In the invention, firstly, concentrated sulfuric acid (which can also be sulfuric acid diluted to have a preset concentration) can be output into a deplating liquid storage tank 2 through the arrangement of a concentrated sulfuric acid storage tank 3, nitrate (mainly copper nitrate and nickel nitrate) in the deplating liquid is converted into sulfate and free nitric acid, then the solubility of the sulfate is reduced through the arrangement of a freezing and crystallizing device 4 by adopting a cooling and freezing mode to precipitate the sulfate, and then the first solid-liquid separation device 5 is matched to precipitate the sulfuric acid. The nitric acid solution after the sulfate precipitation is used by matching a distillation device 6 and a condenser 7, distillation purification is carried out, the obtained distillate (namely, pure nitric acid solution) is stored in a distillate storage tank 8, so that the recovery of nitric acid is realized, in addition, dilute sulfuric acid electrolyte is used for dissolving sulfate crystals output by a first solid-liquid separation device 5 to obtain a sulfate solution, and the dissolved sulfate solution is electrolyzed by a first electrolysis device 10 to obtain elemental copper and a sulfuric acid solution; after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration (close to saturation), the sulfuric acid solution is placed in a replacement device 11, metal nickel is added into the replacement device, impurity metal ions in the sulfuric acid solution are removed by a replacement method, the sulfuric acid solution only containing the nickel ions and impurity solid metal are obtained, the impurity solid metal is removed by using a second solid-liquid separation device 12, and then the sulfuric acid solution with the impurity metal ions removed is placed in a second electrolysis device 13 for electrolysis, so that elemental nickel is obtained. According to the invention, concentrated sulfuric acid is added into the stripping solution to convert nitrate in the stripping solution into sulfate, then the temperature is reduced to separate out the sulfate, solid-liquid separation is realized, the separated solution is distilled and cooled to obtain a pure nitric acid solution, crystals obtained by solid-liquid separation are dissolved and then are electrolyzed to separate out elemental copper, impurity metal ions in the solution are removed by a nickel replacement method, and then secondary electrolysis is carried out to obtain elemental nickel, so that the recycling of nitric acid, copper and nickel in the stripping solution is realized, and the harmless treatment of the stripping solution is realized.

The freezing crystallization device 4 is used for cooling and freezing a nitric acid solution containing sulfate to achieve the purpose of phase separation of nitric acid and sulfate such as copper ions, nickel ions and the like, the solubility of copper sulfate and nickel sulfate is greatly reduced under the condition of low temperature, and crystal precipitation is formed when supersaturation is achieved; the solubility of copper nitrate and nickel nitrate is far higher than that of copper sulfate and nickel sulfate, and the nitric acid still remains in the solution.

The distillation device 6 adopts low-temperature vacuum distillation to reduce nitrogen oxides generated by decomposition of nitric acid and reduce air pollution.

Before the distillation device 6 works, a preset amount of sulfuric acid with preset concentration, such as 98% sulfuric acid or a preset amount of sulfuric acid solution generated by the first electrolysis device 10, needs to be added into the distillation device 6, and the action principle is as follows: the nitric acid solution contains nitrate (mainly copper nitrate and nickel nitrate) and nitric acid, if the nitric acid is directly distilled without adding sulfuric acid, the nitric acid reaches a boiling point during distillation and heating to form steam and then is condensed into dilute nitric acid, but the nitrate has a high boiling point and cannot be evaporated and recycled into a distillate, and the amount of the nitric acid obtained by distillation is small and the concentration is low. Sulfuric acid is added, the nitrate is replaced by nitric acid and sulfate by the sulfuric acid, and the nitric acid obtained by distillation has high content and high concentration, so that the yield of the nitric acid can be improved.

The dissolving tank 9 is filled with a dilute sulfuric acid solution for dissolving the crystal separated by the solid-liquid separation device to obtain a strong acid electrolyte containing copper sulfate, nickel sulfate and dilute sulfuric acid.

The first electrolysis device 10 comprises a cathode electrode plate and an anode electrode plate, and is used for carrying out electrolysis treatment on the strongly acidic electrolyte obtained by stirring and dissolving in the dissolving tank 9 to generate a copper plate and a sulfuric acid solution containing sulfate. (the sulfuric acid solution generated by the electrolytic regeneration device is a mixed dilute sulfuric acid solution containing nickel sulfate, sulfuric acid and a small amount of copper sulfate)

Copper plate and sulfuric acid production by electrolysis principle: copper sulfate is ionized into sulfate ions (SO42-) and copper ions (Cu2+) in the solution, water is ionized into hydroxide ions (OH-) and acid ions (H +), wherein C (SO42-) + C (OH-) ═ C (Cu2+) + C (H +). Under the condition of introducing direct current, cationic copper ions (Cu2+) in the nickel sulfate migrate to the cathode and are reduced and consumed on the surface of the cathode to obtain a metal copper plate; the anionic hydroxide ions (OH-) in the water migrate to the anode and are oxidized to oxygen (O2) by the anode surface. Copper ions (Cu2+) and hydroxyl ions (OH-) are consumed, the concentration is greatly reduced, the concentration of acid radical ions (H +) and sulfate ions (SO42-) is unchanged, and the acid radical ions (H +) and the sulfate ions (SO42-) are integrated to generate sulfuric acid; the nickel ions do not react with the cathode and the anode under the strong acidic condition.

Specifically, the content of nickel powder in the replacement device 11 is 10g/L, the particle size of the nickel powder is 50 meshes, and the reaction time is 24 hours, so that the copper in the electrolyte can be reduced to 10 ppm.

As an optional implementation manner, the system further comprises a concentration adjusting device 14 and a concentrated nitric acid storage tank 15, wherein the concentration adjusting device 14 is configured to adjust a preset proportion of the nitric acid distillate stored in the distillate storage tank 8 and the concentrated nitric acid output from the concentrated nitric acid storage tank 15, and input the nitric acid distillate and the concentrated nitric acid into the reduction tank 1.

So, through increasing blending device and concentrated nitric acid storage tank 15, the cooperation distillate storage jar 8 uses, can let in the returning ferry 1 again with the nitric acid after retrieving and use, has realized the recovery of nitric acid and has recycled.

As an alternative embodiment, the distillation device 6 is further configured to output the distilled concentrated solution to the freezing and crystallizing device 4. In the operation process of the distillation device 6, the concentrated solution which is rich in various metal impurities is always remained, wherein copper ions and nickel ions are contained, and the concentrated solution is added into the freezing crystallization device 4, so that the yield of the elemental metal can be improved, and the environment pollution is avoided.

As an optional implementation manner, the system further comprises a regenerated sulfuric acid storage tank 16, where the regenerated sulfuric acid storage tank 16 is used for storing the solution output by the first electrolysis device 10, and the regenerated sulfuric acid storage tank 16 is further used for mixing the solution with the concentrated sulfuric acid in the concentrated sulfuric acid storage tank 3 in a preset ratio and outputting the mixture to the deplating solution storage tank 2, so as to reduce the usage amount of pure concentrated sulfuric acid. Through calculation, the consumption of pure concentrated sulfuric acid can be reduced by about 90%.

The concentration of nickel ions in the solution obtained by the first electrolysis device 10 is limited, and if the nickel ions are directly replaced and the elemental nickel is recycled by secondary electrolysis, the efficiency is not high, so that the solution obtained by the first electrolysis device 10 can be firstly placed in the regenerated sulfuric acid storage tank 16, and then the solution and the concentrated sulfuric acid in the concentrated sulfuric acid storage tank 3 are mixed according to a preset proportion and then introduced into the deplating solution storage tank 2 to perform the process of converting nitrate into sulfate, on one hand, the use amount of the concentrated sulfuric acid is reduced, on the other hand, the content of the nickel ions in the solution is improved by recycling, and after the nickel ions reach a preset concentration (for example, the nickel ions are close to saturation), the secondary electrolysis is performed to obtain the elemental nickel.

Specifically, the solid nickel is nickel powder, the nickel powder can perform a displacement reaction with copper ions in the regenerated sulfuric acid to displace the copper ions into copper powder (copper simple substance), and the copper powder can be filtered and separated from the solution.

According to the invention, concentrated sulfuric acid is added into the stripping solution to convert nitrate in the stripping solution into sulfate, then the temperature is reduced to separate out the sulfate, solid-liquid separation is realized, the separated solution is distilled and cooled to obtain a pure nitric acid solution, crystals obtained by solid-liquid separation are dissolved and then are electrolyzed to separate out elemental copper, impurity metal ions in the solution are removed by a nickel replacement method, and then secondary electrolysis is carried out to obtain elemental nickel, so that the recycling of nitric acid, copper and nickel in the stripping solution is realized, and the harmless treatment of the stripping solution is realized.

As a second aspect of the present invention, as shown in FIG. 2, there is provided a method for recycling nitric acid deplating solution, comprising

Step S10, adding sulfuric acid with preset concentration into the deplating solution according to a preset proportion so as to convert nitrate in the deplating solution into sulfate and free nitric acid and obtain a sulfate-containing nitric acid solution;

step S20, crystallizing and precipitating sulfate by a cooling and freezing mode;

step S30, carrying out solid-liquid separation on the sulfate crystal and the nitric acid solution;

step S40, distilling and condensing the nitric acid solution to obtain pure nitric acid distillate;

step S50, electrolyzing the sulfate crystal by using dilute sulfuric acid electrolyte to obtain elemental copper and sulfuric acid solution;

step S60, after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration, adding a preset amount of simple substance nickel into the sulfuric acid solution to replace impurity metal ions in the sulfuric acid solution, and obtaining sulfuric acid containing nickel sulfate and impurity solid metal;

step S70, carrying out solid-liquid separation on the sulfuric acid solution and impurity solid metal;

and step S80, electrolyzing the sulfuric acid solution to obtain the simple substance nickel.

As an optional implementation manner, the method further comprises the step of blending the nitric acid distillate and the concentrated nitric acid according to a preset proportion to obtain nitric acid with a preset concentration, and then inputting the nitric acid into the reduction tank.

As an optional implementation manner, after distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate, the method further comprises the step of cooling and freezing the concentrated solution remaining after distillation to crystallize and separate out sulfate therein.

As an optional embodiment, after the sulfate crystal is electrolyzed by using the dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, the method further includes the steps of mixing the sulfuric acid solution and sulfuric acid with a preset concentration according to a preset ratio, and adding the deplating solution.

As an alternative embodiment, before distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate, the method further comprises the step of adding a preset amount of sulfuric acid into the nitric acid solution.

The invention has been described in an illustrative manner, and it is to be understood that the invention is not limited to the precise form disclosed, and that various insubstantial modifications of the inventive concepts and solutions, or their direct application to other applications without such modifications, are intended to be covered by the scope of the invention. The protection scope of the present invention shall be subject to the protection scope defined by the claims.