A nitric acid stripping solution recycling system and method

Abstract

The present invention provides a nitric acid deplating solution recycling and reuse system and method, comprising a deplating trough; a deplating solution storage tank; a concentrated sulfuric acid storage tank; a freeze crystallization device; a first solid-liquid separation device; a distillation device; a condenser; a distillate storage tank; a dissolution tank; a first electrolysis device; a displacement device; a second solid-liquid separation device; and a second electrolysis device. In the present invention, concentrated sulfuric acid is first added to the deplating solution to convert the nitrate therein into sulfate, and then the temperature is lowered to precipitate the sulfate, thereby achieving solid-liquid separation. The separated solution is distilled and cooled to obtain a pure nitric acid solution. The crystals obtained by the solid-liquid separation are dissolved and then electrolyzed to precipitate elemental copper. Impurity metal ions in the solution are then removed by a nickel displacement method, and then a secondary electrolysis is performed to obtain elemental nickel. Thus, the nitric acid, copper, and nickel in the deplating solution are recycled and reused, and the deplating solution is harmlessly treated.

Description

Technical Field

[0001] The invention relates to the technical field of nitric acid deplating solution circulation equipment, in particular to a nitric acid deplating solution recycling system and method. Background Art

[0002] Nitric acid stripping solution is mainly found in the PCB and electroplating industries. Nitric acid stripping solution refers to the stripping waste liquid generated by using nitric acid to dissolve the plating on the electroplating rack, and using nitric acid to dissolve the plating on defective electroplated products.

[0003] Electroplating racks are mounting and conductive tools used for electroplating. During immersion in various electroplating and chemical plating solutions, metal coatings such as copper and nickel are deposited. When a certain thickness is reached, stripping is required. When defective coatings are produced, the plated parts are scrapped, and the coating often needs to be stripped off first, known as stripping, before returning them for secondary processing. Electroplating racks and substrates are generally made of iron, stainless steel, or aluminum. Nitric acid can be used to strip the copper and nickel layers from the rack or defective surfaces of the parts in a single operation. Nitric acid also passivates the surfaces of iron, stainless steel, and aluminum without damaging them, making it a widely used method for stripping. After a period of frequent use, the concentrations of copper and nickel nitrate in the nitric acid stripping solution gradually increase, inhibiting the dissolution rate of copper and nickel in the nitric acid. When the dissolution rate is insufficient for production, fresh nitric acid stripping solution is replaced. The stripping wastewater generated during the stripping process contains significant amounts of heavy metals (copper and nickel) and total nitrogen (nitrate). If not properly handled, it can seriously harm the ecological environment.

[0004] Currently, the main methods for treating nitric acid stripping waste liquid include acid-base neutralization precipitation and electrolysis. The acid-base neutralization precipitation method can only remove heavy metals from the waste liquid. The disadvantage is that the wastewater contains high concentrations of nitrate ions that cannot be removed, and the total nitrogen content still exceeds the standard. The electrolysis method can precipitate the copper in the stripping waste liquid on the surface of the cathode plate of the electrolytic cell and recover the copper plate. The disadvantage is that nickel and other impurity metals in the waste liquid cannot be electrolytically precipitated under acid precipitation conditions. When the nitric acid stripping solution after electrolysis is reused, the nickel stripping effect is poor, the reuse rate is not high, and the reuse is not meaningful.

[0005] Method content

[0006] In view of the above deficiencies in the prior art, the present invention proposes a vacuum distillation device and method for treating waste nitric acid, which can realize the recovery and reuse of copper, nickel and nitric acid in the deplating solution.

[0007] The present invention solves the technical problem by adopting the following technical solutions:

[0008] As a first aspect of the present invention, a nitric acid stripping solution recycling system is provided, comprising

[0009] retreat aqueduct;

[0010] A deplating liquid storage tank, used to receive the deplating liquid output from the deplating trough;

[0011] A concentrated sulfuric acid storage tank is used to provide a preset amount of concentrated sulfuric acid to the deplating solution storage tank to convert nitrate in the deplating solution into sulfate and free nitric acid;

[0012] The freezing crystallization device is used to cool the stripping solution after adding concentrated sulfuric acid to allow sulfate crystals to precipitate;

[0013] a first solid-liquid separation device, for separating sulfate crystals from free nitric acid to obtain sulfate crystals and nitric acid solution;

[0014] a distillation device, used for distilling the nitric acid solution obtained by the first solid-liquid separation device;

[0015] a condenser, the inlet of the condenser being connected to the outlet of the distillation apparatus and being used to collect nitric acid vapor outputted by the distillation apparatus;

[0016] a distillate storage tank, used to collect the distillate output by the condenser;

[0017] a dissolving tank, used to dissolve the sulfate crystals obtained by the first solid-liquid separation device to obtain a sulfate solution;

[0018] a first electrolysis device, for electrolyzing copper sulfate in the sulfate solution output from the dissolution tank;

[0019] a replacement device for adding solid nickel to the solution output from the first electrolysis device to replace the impurity metal ions in the solution and obtain a nickel sulfate solution and impurity solid metal;

[0020] a second solid-liquid separation device for separating the nickel sulfate solution from the impurity solid metal;

[0021] The second electrolysis device is used to electrolyze the nickel sulfate solution.

[0022] As an optional embodiment, it also includes a concentration adjustment device and a concentrated nitric acid storage tank, wherein the concentration adjustment device is used to adjust the nitric acid distillate stored in the distillate storage tank and the concentrated nitric acid output from the concentrated nitric acid storage tank in a preset ratio, and input them into the withdrawal trough.

[0023] As an optional embodiment, the distillation device is also used to output the distilled concentrated liquid to the freezing crystallization device.

[0024] As an optional embodiment, it also includes a regenerated sulfuric acid storage tank, which is used to store the solution output by the first electrolysis device. The regenerated sulfuric acid storage tank is also used to mix the solution with the concentrated sulfuric acid in the concentrated sulfuric acid storage tank in a preset ratio and then output it to the deplating solution storage tank.

[0025] As an optional implementation, the solid nickel is nickel powder.

[0026] As a second aspect of the present invention, a method for recycling a nitric acid stripping solution is provided, comprising:

[0027] adding sulfuric acid of a preset concentration to the deplating solution in a preset ratio to convert nitrate in the deplating solution into sulfate and free nitric acid to obtain a nitric acid solution containing sulfate;

[0028] Sulfate crystallization is precipitated by cooling and freezing;

[0029] Solid-liquid separation of sulfate crystals and nitric acid solution;

[0030] Distilling and condensing the nitric acid solution to obtain pure nitric acid distillate;

[0031] Using a dilute sulfuric acid electrolyte to electrolyze the sulfate crystals to obtain elemental copper and sulfuric acid solution;

[0032] After the concentration of nickel ions in the sulfuric acid solution reaches a predetermined concentration, a predetermined amount of elemental nickel is added thereto to displace the impurity metal ions in the sulfuric acid solution, thereby obtaining sulfuric acid containing nickel sulfate and impurity solid metal;

[0033] Solid-liquid separation of sulfuric acid solution and impure solid metal;

[0034] Electrolysis of sulfuric acid solution to obtain elemental nickel.

[0035] As an optional embodiment, the method further includes mixing the nitric acid distillate with concentrated nitric acid in a preset ratio to obtain nitric acid of a preset concentration and then inputting the obtained nitric acid into a withdrawal tank.

[0036] As an optional embodiment, after distilling and condensing the nitric acid solution to obtain pure nitric acid distillate, the method further includes cooling and freezing the concentrated solution remaining after the distillation to crystallize the sulfate therein.

[0037] As an optional embodiment, after electrolyzing the sulfate crystals using a dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, the method further includes mixing the sulfuric acid solution with sulfuric acid of a preset concentration in a preset ratio, and adding a stripping solution.

[0038] As an optional embodiment, before distilling and condensing the nitric acid solution to obtain pure nitric acid distillate, the process further includes adding a preset amount of sulfuric acid to the nitric acid solution.

[0039] The beneficial effects of the present invention are:

[0040] In the present invention, concentrated sulfuric acid is first added to the deplating solution to convert nitrate therein into sulfate, and then the temperature is lowered to precipitate the sulfate to achieve solid-liquid separation. The separated solution is distilled and cooled to obtain a pure nitric acid solution. Crystals obtained by solid-liquid separation are dissolved and then electrolyzed to precipitate elemental copper. Impurity metal ions in the solution are then removed by a nickel replacement method, and then secondary electrolysis is performed to obtain elemental nickel, thereby achieving the recovery and utilization of nitric acid, copper and nickel in the deplating solution and achieving harmless treatment of the deplating solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The present invention will be further described below with reference to the accompanying drawings and examples.

[0042] Figure 1 It is a front view of the system of this specific embodiment;

[0043] Figure 2 Flowchart of the method of this specific embodiment.

[0044] In the figure, 1-deplating trough, 2-deplating liquid storage tank, 3-concentrated sulfuric acid storage tank, 4-freezing crystallization device, 5-first solid-liquid separation device, 6-distillation device, 7-condenser, 8-distillate storage tank, 9-dissolution tank, 10-first electrolysis device, 11-replacement device, 12-second solid-liquid separation device, 13-second electrolysis device, 14-concentration adjustment device, 15-concentrated nitric acid storage tank, 16-regenerated sulfuric acid storage tank. DETAILED DESCRIPTION

[0045] The following description of the embodiments will further illustrate the specific implementation methods of the present invention, such as the shape, structure, relative position and connection relationship between the various components involved, the function and working principle of each part, the manufacturing process and operation method, etc., to help those skilled in the art to have a more complete, accurate and in-depth understanding of the method concept and technical solution of the present invention.

[0046] As a first aspect of the present invention, Figure 1 As shown, a nitric acid stripping solution recycling system is provided, comprising

[0047] Retreat aqueduct 1;

[0048] The deplating liquid storage tank 2 is used to receive the deplating liquid output from the deplating trough 1;

[0049] A concentrated sulfuric acid storage tank 3 is used to provide a preset amount of concentrated sulfuric acid to the deplating solution storage tank 2 to convert nitrate in the deplating solution into sulfate and free nitric acid;

[0050] The freezing crystallization device 4 is used to cool the deplating solution after adding concentrated sulfuric acid to allow sulfate crystals to precipitate;

[0051] A first solid-liquid separation device 5 is used to separate sulfate crystals from free nitric acid to obtain sulfate crystals and nitric acid solution;

[0052] A distillation device 6, used for distilling the nitric acid solution obtained by the first solid-liquid separation device 5;

[0053] a condenser 7, the inlet of the condenser 7 being connected to the outlet of the distillation device 6, for collecting nitric acid vapor output by the distillation device 6;

[0054] a distillate storage tank 8 for collecting the distillate outputted from the condenser 7;

[0055] a dissolving tank 9 containing a dilute sulfuric acid electrolyte for dissolving the sulfate crystals obtained by the first solid-liquid separation device 5 to obtain a sulfate solution;

[0056] A first electrolysis device 10 is used to electrolyze the copper sulfate in the sulfate solution output from the dissolution tank 9;

[0057] a replacement device 11 for adding solid nickel to the solution outputted from the first electrolysis device 10 to replace impure metal ions, such as copper ions, in the solution, and obtaining a nickel sulfate solution and impure solid metal;

[0058] The second solid-liquid separation device 12 is used to separate the nickel sulfate solution from the impurity solid metal;

[0059] The second electrolysis device 13 is used to electrolyze the nickel sulfate solution.

[0060] In the present invention, first, by setting the concentrated sulfuric acid storage tank 3, it is possible to output concentrated sulfuric acid (or sulfuric acid with a preset concentration after dilution) into the deplating liquid storage tank 2, and the nitrate (mainly copper nitrate and nickel nitrate) in the deplating liquid is converted into sulfate and free nitric acid. Then, by setting the freezing crystallization device 4, the solubility of the sulfate is reduced by cooling and freezing to precipitate it, and then the first solid-liquid separation device 5 is used to precipitate the sulfate. The nitric acid solution after sulfate precipitation is distilled and purified by the distillation device 6 and the condenser 7, and the obtained distillate (i.e., pure nitric acid solution) is stored in the distillate storage tank 8, thereby realizing the recovery of nitric acid. In addition, the sulfate crystals output by the first solid-liquid separation device 5 are dissolved using a dilute sulfuric acid electrolyte to obtain a sulfate solution, and then the dissolved sulfate solution is electrolyzed by the first electrolysis device 10 to obtain elemental copper and sulfuric acid solution; after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration (close to saturation), it is placed in the replacement device 11, and metallic nickel is added thereto, and the impurity metal ions in the sulfuric acid solution are removed by the replacement method to obtain a sulfuric acid solution containing only nickel ions and impure solid metals, and then the second solid-liquid separation device 12 is used to remove the impurity solid metals, and then the sulfuric acid solution after the impurity metal ions are removed is placed in the second electrolysis device 13 for electrolysis to obtain elemental nickel. In the present invention, concentrated sulfuric acid is first added to the deplating solution to convert nitrate therein into sulfate, and then the temperature is lowered to precipitate the sulfate to achieve solid-liquid separation. The separated solution is distilled and cooled to obtain a pure nitric acid solution. Crystals obtained by solid-liquid separation are dissolved and then electrolyzed to precipitate elemental copper. Impurity metal ions in the solution are then removed by a nickel replacement method, and then secondary electrolysis is performed to obtain elemental nickel, thereby achieving the recovery and utilization of nitric acid, copper and nickel in the deplating solution and achieving harmless treatment of the deplating solution.

[0061] The freezing crystallization device 4 is used to cool and freeze the nitric acid solution containing sulfates to achieve the purpose of phase separation between nitric acid and sulfates such as copper ions and nickel ions. Under low temperature conditions, the solubility of copper sulfate and nickel sulfate is greatly reduced. When supersaturation is reached, crystals are formed and precipitated; while the solubility of copper nitrate and nickel nitrate is much greater than that of copper sulfate and nickel sulfate, nitric acid still remains in the solution.

[0062] The distillation device 6 adopts low-temperature vacuum distillation to reduce nitrogen oxides produced by decomposition of nitric acid and reduce air pollution.

[0063] Before the distillation apparatus 6 is operated, a predetermined amount of sulfuric acid of a predetermined concentration, such as 98% sulfuric acid or a predetermined amount of sulfuric acid solution produced by the first electrolysis apparatus 10, needs to be added to the distillation apparatus 6. The principle of operation is as follows: nitric acid solution contains nitrates (primarily copper nitrate and nickel nitrate) and nitric acid. If distillation is performed directly without the addition of sulfuric acid, the nitric acid reaches its boiling point during distillation heating, forming vapor and condensing into dilute nitric acid. However, the nitrates have a high boiling point and cannot be evaporated and recovered in the distillate, resulting in a small amount of nitric acid and a low concentration. Adding sulfuric acid replaces the nitrates with nitric acid and sulfate, resulting in a large amount of nitric acid with a high concentration, thereby improving the yield of nitric acid.

[0064] The dissolving tank 9 is filled with a dilute sulfuric acid solution for dissolving the crystals separated by the solid-liquid separation device to obtain a strong acid electrolyte containing copper sulfate, nickel sulfate and dilute sulfuric acid.

[0065] The first electrolysis device 10 includes cathode and anode electrode plates, which are used to electrolyze the strongly acidic electrolyte obtained by stirring and dissolving the solution in the dissolution tank 9 to produce copper plates and a sulfuric acid solution containing sulfate. (The sulfuric acid solution produced by the electrolytic regeneration device is a mixed dilute sulfuric acid solution containing nickel sulfate, sulfuric acid, and a small amount of copper sulfate.)

[0066] The principle of electrolysis to produce copper plates and sulfuric acid: Copper sulfate in solution ionizes into sulfate ions (SO42-) and copper ions (Cu2+), while water ionizes into hydroxide ions (OH-) and acid ions (H+), where C(SO42-) + C(OH-) = C(Cu2+) + C(H+). When direct current is applied, the copper ions (Cu2+) in nickel sulfate migrate toward the cathode and are reduced and consumed on the cathode surface, producing metallic copper plates. The hydroxide ions (OH-) in water migrate toward the anode and are oxidized to oxygen (O2) on the anode surface. The copper ions (Cu2+) and hydroxide ions (OH-) are consumed, significantly decreasing their concentrations. The concentrations of acid ions (H+) and sulfate ions (SO42-) remain unchanged, and the acid ions (H+) and sulfate ions (SO42-) combine to produce sulfuric acid. Nickel ions do not react at the cathode or anode under strongly acidic conditions.

[0067] Specifically, the nickel powder content in the replacement device 11 is 10 g / L, the nickel powder particle size is 50 mesh, and the reaction time is 24 hours, which can reduce the copper in the electrolyte to 10 ppm.

[0068] As an optional embodiment, it also includes a concentration adjustment device 14 and a concentrated nitric acid storage tank 15, wherein the concentration adjustment device 14 is used to adjust 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 in a preset ratio, and input them into the withdrawal trough 1.

[0069] In this way, by adding a blending device and a concentrated nitric acid storage tank 15 and using them in conjunction with the distillate storage tank 8, the recovered nitric acid can be reintroduced into the withdrawal trough 1 for use, thereby realizing the recovery and reuse of nitric acid.

[0070] As an optional embodiment, the distillation device 6 is also used to output the distilled concentrate to the freeze crystallization device 4. During the operation of the distillation device 6, a portion of the concentrate rich in various metal impurities, including copper ions and nickel ions, is often left over. By adding the concentrate to the freeze crystallization device 4, the yield of the elemental metal can be increased and environmental pollution can be avoided.

[0071] As an optional embodiment, a regenerated sulfuric acid storage tank 16 is further included. The regenerated sulfuric acid storage tank 16 is used to store the solution output by the first electrolysis device 10. The regenerated sulfuric acid storage tank 16 is also used to mix the solution with concentrated sulfuric acid in the concentrated sulfuric acid storage tank 3 in a preset ratio before outputting the mixture to the stripping solution storage tank 2, thereby reducing the amount of pure concentrated sulfuric acid used. According to calculations, the amount of pure concentrated sulfuric acid used can be reduced by approximately 90%.

[0072] The concentration of nickel ions in the solution initially obtained by the first electrolysis device 10 is limited. Direct replacement and secondary electrolysis to recover elemental nickel are inefficient. Therefore, the solution obtained by the first electrolysis device 10 can be first placed in the regenerated sulfuric acid storage tank 16, and then mixed with the concentrated sulfuric acid in the concentrated sulfuric acid storage tank 3 according to a preset ratio and passed into the deplating solution storage tank 2 to carry out the process of converting nitrate into sulfate. On the one hand, the amount of concentrated sulfuric acid is reduced, and on the other hand, the content of nickel ions in the solution is increased by recycling. After it reaches a preset concentration (for example, close to saturation), secondary electrolysis is carried out to obtain elemental nickel, thereby improving the recovery efficiency of elemental nickel.

[0073] Specifically, the solid nickel is nickel powder, which can undergo a replacement reaction with copper ions in the regenerated sulfuric acid to replace the copper ions with copper powder (elemental copper), which can be filtered and separated from the solution.

[0074] In the present invention, concentrated sulfuric acid is first added to the deplating solution to convert nitrate therein into sulfate, and then the temperature is lowered to precipitate the sulfate to achieve solid-liquid separation. The separated solution is distilled and cooled to obtain a pure nitric acid solution. Crystals obtained by solid-liquid separation are dissolved and then electrolyzed to precipitate elemental copper. Impurity metal ions in the solution are then removed by a nickel replacement method, and then secondary electrolysis is performed to obtain elemental nickel, thereby achieving the recovery and utilization of nitric acid, copper and nickel in the deplating solution and achieving harmless treatment of the deplating solution.

[0075] As a second aspect of the present invention, Figure 2 As shown, a method for recycling nitric acid stripping solution is provided, comprising:

[0076] Step S10, adding sulfuric acid of a preset concentration to the deplating solution according to a preset ratio to convert nitrate in the deplating solution into sulfate and free nitric acid to obtain a nitric acid solution containing sulfate;

[0077] Step S20, crystallizing sulfate by cooling and freezing;

[0078] Step S30, performing solid-liquid separation on the sulfate crystals and the nitric acid solution;

[0079] Step S40, distilling and condensing the nitric acid solution to obtain a pure nitric acid distillate;

[0080] Step S50: electrolyzing the sulfate crystals using a dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution;

[0081] Step S60: After the concentration of nickel ions in the sulfuric acid solution reaches a predetermined concentration, a predetermined amount of elemental nickel is added thereto to displace the impurity metal ions in the sulfuric acid solution, thereby obtaining sulfuric acid containing nickel sulfate and impurity solid metal;

[0082] Step S70, performing solid-liquid separation on the sulfuric acid solution and the impure solid metal;

[0083] Step S80: electrolyze the sulfuric acid solution to obtain elemental nickel.

[0084] As an optional embodiment, the method further includes mixing the nitric acid distillate with concentrated nitric acid in a preset ratio to obtain nitric acid of a preset concentration and then inputting the obtained nitric acid into a withdrawal tank.

[0085] As an optional embodiment, after distilling and condensing the nitric acid solution to obtain pure nitric acid distillate, the method further includes cooling and freezing the concentrated solution remaining after the distillation to crystallize the sulfate therein.

[0086] As an optional embodiment, after electrolyzing the sulfate crystals using a dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, the method further includes mixing the sulfuric acid solution with sulfuric acid of a preset concentration in a preset ratio, and adding a stripping solution.

[0087] As an optional embodiment, before distilling and condensing the nitric acid solution to obtain pure nitric acid distillate, the process further includes adding a preset amount of sulfuric acid to the nitric acid solution.

[0088] The above description of the present invention is illustrative. It is clear that the specific implementation of the present invention is not limited to the above-described methods. Any non-substantial improvements made using the method concepts and technical solutions of the present invention, or any direct application of the concepts and technical solutions of the present invention to other situations without modification, are all within the scope of protection of the present invention. The scope of protection of the present invention shall be based on the scope of protection defined in the claims.

Claims

1. A nitric acid stripping solution recycling system, characterized in that: include retreat aqueduct; A deplating liquid storage tank, used to receive the deplating liquid output from the deplating trough; A concentrated sulfuric acid storage tank is used to provide a preset amount of concentrated sulfuric acid to the deplating solution storage tank to convert nitrate in the deplating solution into sulfate and free nitric acid; The freezing crystallization device is used to cool the stripping solution after adding concentrated sulfuric acid to allow sulfate crystals to precipitate; a first solid-liquid separation device, for separating sulfate crystals from free nitric acid to obtain sulfate crystals and nitric acid solution; a distillation device, used for distilling the nitric acid solution obtained by the first solid-liquid separation device; a condenser, the inlet of the condenser being connected to the outlet of the distillation apparatus and being used to collect nitric acid vapor outputted by the distillation apparatus; a distillate storage tank, used to collect the distillate output by the condenser; a dissolving tank, used to dissolve the sulfate crystals obtained by the first solid-liquid separation device to obtain a sulfate solution; a first electrolysis device for electrolyzing the sulfate solution output from the dissolution tank to obtain elemental copper and sulfuric acid solution; a replacement device for adding solid nickel to the sulfuric acid solution to replace the impurity metal ions in the sulfuric acid solution after the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration, thereby obtaining a nickel sulfate solution and impurity solid metal, wherein the solid nickel is nickel powder, the nickel powder addition amount is 10 g / L, the nickel powder particle size is 50 mesh, and the reaction time is 24 hours, so that the copper ion concentration in the sulfuric acid solution is reduced to 10 ppm; a second solid-liquid separation device for separating the nickel sulfate solution from the impurity solid metal; a second electrolysis device for electrolyzing nickel sulfate solution to obtain elemental nickel; The distillation device is used to output the distilled concentrated liquid to the freezing crystallization device. The concentrated liquid includes copper ions and nickel ions. By adding the concentrated liquid to the freezing crystallization device, the yield of the elemental metal is improved.

2. nitric acid decoating solution recycling system according to claim 1, is characterized in that: It also includes a concentration adjusting device and a concentrated nitric acid storage tank. The concentration adjusting device is used to adjust the nitric acid distillate stored in the distillate storage tank and the concentrated nitric acid output from the concentrated nitric acid storage tank in a preset ratio, and input them into the withdrawal trough.

3. nitric acid decoating solution recycling system according to claim 1, is characterized in that: The distillation device is also used to output the distilled concentrated liquid to the freezing crystallization device.

4. nitric acid decoating solution recycling system according to claim 1, is characterized in that: It also includes a regenerated sulfuric acid storage tank, which is used to store the solution output by the first electrolysis device. The regenerated sulfuric acid storage tank is also used to mix the solution with concentrated sulfuric acid in the concentrated sulfuric acid storage tank in a preset ratio and then output it to the deplating solution storage tank.

5. A method for recycling nitric acid stripping solution, characterized in that: The method is applied to a nitric acid deplating solution recycling system, and the method comprises: adding sulfuric acid of a preset concentration to the deplating solution in a preset ratio to convert nitrate in the deplating solution into sulfate and free nitric acid to obtain a nitric acid solution containing sulfate; Sulfate crystallization is precipitated by cooling and freezing; Solid-liquid separation of sulfate crystals and nitric acid solution; Distilling and condensing the nitric acid solution to obtain pure nitric acid distillate and concentrated solution after distillation; Using a dilute sulfuric acid electrolyte to electrolyze the sulfate crystals to obtain elemental copper and sulfuric acid solution; After the concentration of nickel ions in the sulfuric acid solution reaches a preset concentration, a preset amount of solid nickel is added thereto to displace the impurity metal ions in the sulfuric acid solution, thereby obtaining sulfuric acid containing nickel sulfate and impurity solid metals. The solid nickel is nickel powder, the nickel powder addition amount is 10 g / L, and the nickel powder particle size is 50 mesh. The reaction time is 24 hours, and the copper ion concentration in the sulfuric acid solution is reduced to 10 ppm. Solid-liquid separation of sulfuric acid solution and impure solid metal; Electrolyze sulfuric acid solution to obtain elemental nickel; The concentrate is added to improve the recovery rate of elemental metals, wherein the concentrate contains copper ions and nickel ions.

6. nitric acid decoating solution recycling method according to claim 5, is characterized in that: The method further includes the step of mixing the nitric acid distillate with concentrated nitric acid according to a preset ratio to obtain nitric acid of a preset concentration and then inputting the obtained nitric acid into a withdrawal trough.

7. nitric acid decoating solution recycling method according to claim 5, is characterized in that: After the nitric acid solution is distilled and condensed to obtain pure nitric acid distillate, the method further includes cooling and freezing the concentrated solution remaining after the distillation to allow sulfate crystals therein to precipitate.

8. nitric acid decoating solution recycling method according to claim 5, is characterized in that: After electrolyzing the sulfate crystals using a dilute sulfuric acid electrolyte to obtain elemental copper and a sulfuric acid solution, the method further includes mixing the sulfuric acid solution with sulfuric acid of a preset concentration in a preset ratio, and adding a stripping solution.

9. nitric acid decoating solution recycling method according to claim 5, is characterized in that: Before distilling and condensing the nitric acid solution to obtain pure nitric acid distillate, the method further includes adding a preset amount of sulfuric acid to the nitric acid solution.

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