阅读说明：本技术 一种退镀废液回收硝酸与硫酸铜的方法及系统 (Method and system for recovering nitric acid and copper sulfate from deplating waste liquid ) 是由 庄仓宏 于 2021-08-04 设计创作，主要内容包括：本发明提供了一种退镀废液回收硝酸与硫酸铜的方法及系统,所述的方法包括：电路板退镀废液与浓硫酸混合后经蒸馏获得硝酸和蒸馏余液,将蒸馏余液进行冷却结晶得到硫酸铜晶体并进行回收。本发明提供的一种退镀废液回收硝酸与硫酸铜的方法及系统,依据体系内铜离子转化为硫酸铜所消耗的硫酸的量,补充额外的浓硫酸以维持体系内硫酸浓度的平衡,将退镀废液中的硝酸及铜离子均进行了资源化回收利用,并得到相应的产品,资源化利用率高,提高了硝酸回用价值,整个系统密闭循环,能够实现零排放。(The invention provides a method and a system for recovering nitric acid and copper sulfate from deplating waste liquid, wherein the method comprises the following steps: mixing the circuit board deplating waste liquid with concentrated sulfuric acid, distilling to obtain nitric acid and distillation residual liquid, cooling and crystallizing the distillation residual liquid to obtain copper sulfate crystals, and recovering. According to the method and the system for recovering nitric acid and copper sulfate from the deplating waste liquid, provided by the invention, according to the amount of sulfuric acid consumed by converting copper ions in a system into copper sulfate, additional concentrated sulfuric acid is supplemented to maintain the balance of the concentration of the sulfuric acid in the system, the nitric acid and the copper ions in the deplating waste liquid are recycled as resources, corresponding products are obtained, the utilization rate of the resources is high, the recycling value of the nitric acid is improved, the whole system is in closed circulation, and zero emission can be realized.)

1. A method for recovering nitric acid and copper sulfate from deplating waste liquid is characterized by comprising the following steps:

mixing the circuit board deplating waste liquid with concentrated sulfuric acid, distilling to obtain nitric acid and distillation residual liquid, cooling and crystallizing the distillation residual liquid to obtain copper sulfate crystals, and recovering.

2. The method according to claim 1, characterized in that it comprises in particular the steps of:

mixing the circuit board deplating waste liquid with concentrated sulfuric acid to generate a mixed liquid, distilling the mixed liquid to generate nitric acid steam and distilled residual liquid, and condensing and recovering the nitric acid steam;

(II) cooling and crystallizing the distillation residual liquid in the step (I) to separate out copper sulfate crystals, and then carrying out solid-liquid separation to separate out mother liquid;

and (III) mixing the mother liquor obtained in the step (II) with supplemented concentrated sulfuric acid, adding the mixed mother liquor into the circuit board deplating waste liquor, repeating the steps (I) to (III), and finally drying and recovering the obtained copper sulfate crystals.

3. The process of claim 1 or 2, wherein the concentration of concentrated sulfuric acid in step (i) is 98 wt.%;

preferably, the molar concentration of the sulfate ions in the concentrated sulfuric acid is 1.6-2.5 times of that of the copper ions;

preferably, the mixing time of the circuit board deplating waste liquid and concentrated sulfuric acid is 20-45 min;

preferably, the step (I) comprises mixing the circuit board deplating waste liquid with concentrated sulfuric acid and then carrying out stirring reaction;

preferably, the temperature of the mixed solution after the stirring reaction is increased to 53-65 ℃.

4. The method as claimed in claim 2, wherein the step (I) further comprises adjusting the concentration of the condensed nitric acid solution and then refluxing the nitric acid solution to a circuit board deplating section;

preferably, the condensation temperature is 10-25 ℃;

preferably, the mass fraction of the nitric acid solution after concentration adjustment is 40-55%.

5. The process of claim 2, wherein said cooling crystallization in step (ii) comprises stirring crystallization;

preferably, the temperature of the cooling crystallization is 10-25 ℃;

preferably, the cooling crystallization time is 2-4 h;

preferably, the solid-liquid separation is centrifugal separation;

preferably, in the step (iii), after the mother liquor is mixed with the supplemented concentrated sulfuric acid, the molar concentration of the sulfuric acid ions in the mixed liquor is 1.6 to 2.5 times of the molar concentration of the total copper ions;

preferably, the total molar concentration of copper ions includes the molar concentration of copper ions in the circuit board deplating waste liquid and the molar concentration of copper ions in the mother liquid.

6. A system for recovering nitric acid and copper sulfate from deplating waste liquid used in the method of any one of claims 1 to 5, which is characterized by comprising a deplating device, a reaction vessel, a distilling device, a cooling crystallizing device and a solid-liquid separating device which are sequentially connected, wherein the reaction vessel is externally connected with a concentrated sulfuric acid storage tank, the waste liquid in the deplating device enters the reaction vessel to be mixed with concentrated sulfuric acid, and the generated solution is sequentially distilled, cooled and crystallized to recover nitric acid and copper sulfate.

7. The system according to claim 6, wherein the distillation device is sequentially connected with a condenser, a nitric acid collecting tank and a concentration adjusting device, nitric acid steam generated by distillation is condensed and then enters the nitric acid collecting tank, and then flows into the concentration adjusting device to adjust acidity and then flows back to the deplating device.

8. The system according to claim 6 or 7, wherein the solid-liquid separation device is externally connected with the reaction vessel, and mother liquor generated by solid-liquid separation flows back into the reaction vessel through the connecting pipeline.

9. A system according to any one of claims 6 to 8, wherein the solid-liquid separation device is a centrifuge.

10. The system as claimed in any one of claims 6 to 9, further comprising a drying device and a copper sulfate storage tank, wherein one end of the drying device is connected with the copper sulfate storage tank, the other end of the drying device is connected with the solid-liquid separation device, and the solid generated by cooling crystallization is sent into the drying device for drying and then sent into the copper sulfate storage tank.

Technical Field

The invention belongs to the technical field of waste liquid treatment in a circuit board manufacturing process, relates to treatment of circuit board deplating waste liquid, and particularly relates to a method and a system for recovering nitric acid and copper sulfate from the circuit board deplating waste liquid.

Background

Along with the electroplating process of the circuit board, the hanger used as the support body of the plated part is also plated with various corresponding metal plating layers, for example, ABS plastic electroplating is mainly a copper/nickel/chromium three-layer. Because the hanger needs to be used repeatedly, when one batch of plated parts is plated and the next batch of plated parts is electroplated, the plating layer on the hanger needs to be thoroughly removed, otherwise, the plating solution is polluted. Electrochemical stripping is generally used to remove the coating by anodically passivating certain base metals in alkaline solutions or solutions containing chromium compounds, the conditions of passivation of the solutions or corrosion inhibition to protect the metal substrate from corrosion. Or adding substances such as corrosion inhibitor and the like into the acidic solution to ensure that only the plating metal is dissolved by anodic oxidation.

In the current processes of decorative electroplating and printed circuit board production, copper metal on a hanger is often dissolved by nitric acid, and waste water generated in the deplating process has toxicity and residual nitric acid exists. If the waste liquid is directly neutralized and discharged, heavy metals and total nitrogen in the waste liquid pollute water and the environment, and the human health is influenced.

CN106319563A provides a method for producing electrolytic copper by using concentrated nitric acid copper-containing wastewater, which comprises the following steps: fully mixing concentrated nitric acid copper-containing wastewater with an alkaline solution containing carbonyl for reaction, and separating the mixed solution after the reaction to obtain a solid precipitate and a copper-containing waste solution; then, adsorbing copper ions in the copper-containing waste liquid by using an adsorbent, and backwashing the adsorbent by using a sulfuric acid solution after the adsorption is saturated to obtain a copper sulfate solution; and then, electrolyzing the copper sulfate solution to obtain electrolytic copper, wherein the alkaline solution containing carbonyl is weak amide base, but the amide-containing or nitrogen-containing product needs to be further treated, so that the environmental pollution is avoided, and the engineering cost is increased by electrolyzing the copper sulfate solution.

CN109868476A discloses a method for recycling etching solution containing copper ions and nitrate radicals, wherein the etching solution is subjected to an electrodialysis device to obtain a high-concentration copper-containing solution and a low-concentration copper-containing solution, the high-concentration copper-containing solution enters a copper extraction tank for circular electrolysis, so that copper ions are reduced to generate a copper simple substance and deposit the copper simple substance on a copper electrode as a cathode, the cathode is used as an anode in a refining tank, and the anode in the refining tank is dissolved out onto the cathode to obtain a copper plate; carrying out rotational flow electrolysis on the electrolyte with low copper ion concentration obtained in the copper extraction tank and the low-concentration copper-containing solution generated in the electrodialysis device to obtain copper pipes and/or copper powder; adding concentrated nitric acid into the clear liquid to form etching liquid for recycling. If the etching solution contains nickel ions, adding alkali liquor to adjust the pH value after the electrolysis is finished, and precipitating the nickel ions.

CN103979625A discloses a mixed treatment method of acid and alkaline etching waste liquid and nitric acid stripping waste liquid of a printed circuit board, which comprises the following steps: a: adding the acidic etching waste liquid to be treated into quartz evaporation equipment, and electrifying and heating the quartz evaporation equipment to 110 ℃ to collect a first copper ion mixture; b: adding the alkaline etching waste liquid to be treated into the quartz evaporation equipment, and collecting to obtain a second copper ion mixture; c: adding the nitric acid stripping waste liquid to be treated into the quartz evaporation equipment, and collecting to obtain a third copper ion mixture; d: adding a proper amount of dilute sulfuric acid into the storage tank to obtain a copper sulfate solution; e: and d, continuously electrolyzing the copper sulfate solution obtained in the step d to generate high-purity metal copper.

The deplating waste liquid is directly neutralized and discharged, so that the environment is seriously polluted, and the resource waste is caused, therefore, the method for treating the deplating waste liquid can realize zero emission, reduce energy consumption and maximize the resource recycling is very necessary.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the method and the system for recovering the nitric acid and the copper sulfate from the deplating waste liquid, which are economic and environment-friendly and convenient to operate, simultaneously extract and repeatedly utilize the copper and the nitric acid in the deplating waste liquid, reduce the energy consumption and realize zero emission.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a method for recovering nitric acid and copper sulfate from deplating waste liquid, which comprises the following steps:

mixing the circuit board deplating waste liquid with concentrated sulfuric acid, distilling to obtain nitric acid and distillation residual liquid, cooling and crystallizing the distillation residual liquid to obtain copper sulfate crystals, and recovering.

According to the method for recycling nitric acid and copper sulfate from the deplating waste liquid, provided by the invention, nitric acid and copper ions in the deplating waste liquid are recycled and utilized as resources, and corresponding products are obtained, so that the resource utilization rate is high, and the recycling value of nitric acid is improved; high-quality copper sulfate products are crystallized by cooling, which is beneficial to the sale of the products; the generated mother liquor is refluxed to the reaction process of the deplating waste liquid and the sulfuric acid, the required sulfuric acid is supplemented, the process cost is reduced, zero emission is realized, and the environmental pollution is avoided.

As a preferred technical scheme of the invention, the method specifically comprises the following steps:

mixing the circuit board deplating waste liquid with concentrated sulfuric acid to generate a mixed liquid, distilling the mixed liquid to generate nitric acid steam and distilled residual liquid, and condensing and recovering the nitric acid steam;

(II) cooling and crystallizing the distillation residual liquid in the step (I) to separate out copper sulfate crystals, and then carrying out solid-liquid separation to separate out mother liquid;

(III) mixing the mother liquor obtained in the step (II) with supplemented concentrated sulfuric acid, adding the mixed mother liquor into the circuit board deplating waste liquor, repeating the steps (I) to (III), and finally drying and recovering the obtained copper sulfate crystals

It should be noted that the circuit board deplating waste liquid in the invention is a copper plating layer of a circuit board hanger treated by nitric acid acidification, so that the waste liquid contains a large amount of copper nitrate, copper ions and free nitric acid ions, and the reaction mechanism of the waste liquid and concentrated sulfuric acid is as follows:

Cu(NO₃)₂+H₂SO₄＝CuSO₄+2HNO₃

2NO₃ ^-+H₂SO₄＝SO₄ ^2-+2HNO₃

as shown above, the concentrated sulfuric acid is added into the deplating waste liquid, the copper nitrate is replaced by the copper sulfate and the nitric acid, the mixed system of the copper sulfate and the nitric acid is distilled, the nitric acid is vaporized and condensed for recycling, the distilled residual liquid (containing the copper sulfate) is cooled and crystallized, and the water in the mixed system is evaporated while the nitric acid is distilled, so that the crystallization capacity of the copper sulfate in the subsequent distilled residual liquid is improved.

As a preferred embodiment of the present invention, the concentration of concentrated sulfuric acid in step (I) is 98% by weight.

Preferably, the molar amount of the added sulfate ion is 1.6 to 2.5 times the molar concentration of the copper ion, and may be, for example, 1.6 times, 1.7 times, 1.8 times, 1.9 times, 2 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, or 2.5 times, but is not limited to the enumerated values, and other values not enumerated within the numerical range are also applicable.

Preferably, the mixing time of the circuit board deplating waste liquid and the concentrated sulfuric acid is 20-45 min, for example, 20min, 22min, 24min, 25min, 27min, 28min, 30min, 32min, 35min, 37min, 38min, 40min, 41min, 42min, 43min, 44min or 45min, but is not limited to the enumerated values, and other non-enumerated values in the numerical range are also applicable.

Preferably, the step (I) comprises mixing the circuit board deplating waste liquid with concentrated sulfuric acid and then carrying out stirring reaction.

Preferably, the temperature of the liquid mixture after the stirring reaction is raised to 53 to 65 ℃, for example, 53 ℃, 54 ℃, 55 ℃, 56 ℃, 57 ℃, 58 ℃, 59 ℃, 60 ℃, 61 ℃, 63 ℃, 64 ℃ or 65 ℃, but not limited to the recited values, and other values not recited within the range of the values are also applicable.

As a preferred technical scheme of the invention, the step (I) also comprises the step of regulating the concentration of the condensed nitric acid solution and then refluxing the nitric acid solution to a circuit board deplating working section.

Preferably, the condensation temperature is 10-25 ℃, for example 10 ℃, 11 ℃, 12 ℃, 15 ℃, 16 ℃, 18 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃ or 25 ℃, but not limited to the values listed, and other values not listed in the range of values are also applicable.

Preferably, the concentration of the nitric acid solution is adjusted to 40-55% by weight, for example, 40%, 41%, 42%, 45%, 46%, 48%, 50%, 52%, 53% or 55%, but not limited to the values listed, and other values not listed in the range of values are also applicable.

It should be noted that the concentration of the distilled nitric acid product can be adjusted and then returned to the deplating process, so that alkali neutralization treatment is not needed, the process flow is simplified, and the production cost is reduced.

As a preferred embodiment of the present invention, the cooling in step (II) comprises stirring for crystallization.

Preferably, the cooling crystallization temperature is 10 ~ 25 ℃, for example can be 10 ℃, 11 ℃, 12 ℃, 13 ℃, 14 ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, 20 ℃, 21 ℃, 22 ℃, 23 ℃, 24 ℃ or 25 ℃, but not limited to the number, in the range of other values are also applicable.

Preferably, the cooling crystallization time is 2 to 4 hours, for example, 2 hours, 2.2 hours, 2.5 hours, 3 hours, 3.2 hours, 3.5 hours or 4 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first solid-liquid separation is centrifugal separation.

Preferably, in step (iii), after mixing the mother liquor with additional concentrated sulfuric acid, the molar concentration of sulfate ions in the mixed liquor is 1.6 to 2.5 times of the molar concentration of total copper ions, for example, 1.6 times, 1.7 times, 1.8 times, 2 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times or 2.5 times, but not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the total molar concentration of copper ions includes the molar concentration of copper ions in the circuit board deplating waste liquid and the molar concentration of copper ions in the mother liquid.

In the invention, the distilled residual liquid is cooled and crystallized to separate out crystals, the mother liquid generated by solid-liquid separation contains dilute nitric acid, dilute sulfuric acid and copper salt, the dilute nitric acid, the dilute sulfuric acid and the copper salt are refluxed and mixed with supplemented concentrated sulfuric acid to be added into the deplating waste liquid to be treated in the next batch, and the sulfuric acid required by copper sulfate is supplemented, wherein after the mother liquid is mixed with the supplemented concentrated sulfuric acid, the molar concentration ratio of sulfate ions in the mixed liquid to the total molar concentration of the copper ions in the deplating waste liquid of the next batch is the same as the molar concentration ratio of the copper ions in the initial circuit board to the concentrated sulfuric acid, so as to keep the balance of the sulfuric acid, wherein the total molar concentration of the copper ions refers to the sum of the molar concentration of the copper ions in the deplating waste liquid of the next batch and the molar concentration of the copper ions in the refluxed mother liquid.

It should be noted that, in the invention, high-quality copper sulfate crystals are obtained by cooling crystallization, and then drying is carried out to remove moisture, so as to obtain a copper sulfate product with the mass fraction of 98 wt%, and the copper sulfate product is directly recovered, so that the purity of copper sulfate can be improved, and zero emission is realized.

In a second aspect, the invention provides a system for recovering nitric acid and copper sulfate from deplating waste liquid, which is used in the method of the first aspect, and the system comprises a deplating device, a reaction vessel, a distilling device, a cooling and crystallizing device and a solid-liquid separating device which are sequentially connected, wherein the reaction vessel is externally connected with a concentrated sulfuric acid storage tank, the waste liquid in the deplating device enters the reaction vessel to be mixed with concentrated sulfuric acid, and the generated solution is sequentially distilled, cooled and crystallized to recover nitric acid and copper sulfate.

According to the system for recycling nitric acid and copper sulfate from the deplating waste liquid, provided by the invention, nitric acid and copper ions in the deplating waste liquid are recycled, and a corresponding product is obtained, so that the recycling value of nitric acid is improved; the high-quality copper sulfate product is crystallized by cooling twice, which is beneficial to the sale of the product; simple structure, convenient operation, reduced process cost, and zero emission.

It should be noted that the temperature of the deplating waste liquid and the concentrated sulfuric acid in the invention is increased by the dissolution heat after being uniformly stirred in the reaction vessel, so that a reaction vessel with heat resistance and acid corrosion resistance, such as a glass-lined reaction kettle or a distillation flask, is required to be adopted for containing, and it is understood that the reaction vessel with heat resistance and acid corrosion resistance also falls within the protection scope and the disclosure scope of the invention, so that other forms of reaction vessels which are disclosed in the prior art or are not disclosed in the new technology can also be used in the invention.

As a preferable technical scheme of the invention, the distillation device is sequentially connected with a condenser, a nitric acid collecting tank and a concentration adjusting device, nitric acid generated by distillation is condensed and then enters the nitric acid collecting tank, and then flows into the concentration adjusting device to adjust acidity and then flows back to the deplating device.

As a preferable technical scheme of the invention, the solid-liquid separation device is externally connected with a reaction vessel, and mother liquor generated by solid-liquid separation flows back into the reaction vessel through a connecting pipeline.

As a preferable technical scheme of the invention, the solid-liquid separation device is a centrifuge.

As a preferred technical scheme of the invention, the system also comprises a drying device and a copper sulfate storage tank, one end of the drying device is connected with the copper sulfate storage tank, the other end of the drying device is connected with the solid-liquid separation device, and the solid generated by cooling crystallization enters the drying device for drying and then is sent into the copper sulfate storage tank.

Compared with the prior art, the invention has the beneficial effects that:

according to the method and the system for recycling the nitric acid and the copper sulfate from the deplating waste liquid, provided by the invention, the nitric acid and copper ions in the deplating waste liquid are recycled and utilized as resources, corresponding products are obtained, the resource utilization rate is high, and the nitric acid recycling value is improved; 98 wt% of high-quality copper sulfate product is crystallized by cooling, which is beneficial to the sale of the product; the generated mother liquor flows back to the reaction process of the deplating waste liquor and the sulfuric acid, the required sulfuric acid is supplemented, the process cost is reduced, the whole system is in closed circulation, zero emission is realized, and the environmental pollution is avoided.

Drawings

FIG. 1 is a flow chart of a method for recovering nitric acid and copper sulfate from deplating waste liquid according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a system for recovering nitric acid and copper sulfate from deplating waste liquid according to an embodiment of the present invention.

Wherein, 1-deplating device; 2-a reaction vessel; 3-a concentrated sulfuric acid storage tank; 4-a distillation unit; 5-a condenser; a 6-nitric acid collection tank; 7-a concentration regulating device; 8-cooling the crystallization device; 9-a solid-liquid separation device; 10-a drying device; 11-copper sulfate storage tank.

Detailed Description

It is to be understood that in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be taken as limiting the present invention. In the description of the present invention, "a plurality" means two or more unless otherwise specified.

It should be noted that, in the description of the present invention, unless otherwise explicitly specified or limited, the terms "disposed," "connected" and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

In one embodiment, the invention provides a method for recovering nitric acid and copper sulfate from deplating waste liquid, which specifically comprises the following steps:

mixing the circuit board deplating waste liquid with concentrated sulfuric acid, distilling to obtain nitric acid and distillation residual liquid, cooling and crystallizing the distillation residual liquid to obtain copper sulfate crystals, and recovering the copper sulfate crystals, wherein the method specifically comprises the following steps of:

(1) mixing the circuit board deplating waste liquid with 98 wt% of concentrated sulfuric acid, stirring and reacting for 20-45 min to generate a mixed liquid, adding 1.6-2 times of the molar concentration of copper ions of sulfate ions, raising the temperature of the reacted mixed liquid to 53-65 ℃, distilling the mixed liquid to generate nitric acid steam and distilled residual liquid, condensing and recycling the nitric acid steam at 10-25 ℃, adjusting the concentration of the condensed nitric acid solution to enable the mass fraction of the condensed nitric acid solution to reach 40-55%, and refluxing to a circuit board deplating working section;

(2) stirring the distillation residual liquid in the step (1) for 2-4 hours at the temperature of 10-25 ℃, cooling and crystallizing to separate out copper sulfate crystals, and separating out a mother liquid through solid-liquid separation;

(3) and (3) mixing the mother liquor obtained in the step (2) with supplemented concentrated sulfuric acid, adding the mixed liquor into the circuit board deplating waste liquor, repeating the steps (1) to (3), and finally drying and recovering the obtained copper sulfate crystals, wherein after the mother liquor and the supplemented concentrated sulfuric acid are mixed, the molar ratio of the molar concentration of sulfate ions in the mixed liquor to the molar concentration of total copper ions is kept the same as the molar ratio of the copper ions in the circuit board deplating waste liquor obtained in the step (1) to the concentrated sulfuric acid.

In another embodiment, the invention provides a system for recovering nitric acid and copper sulfate from deplating waste liquid, which is used in one embodiment, and comprises a deplating device 1, a reaction vessel 2, a distilling device 4, a cooling crystallizing device 8 and a solid-liquid separating device 9 which are connected in sequence, as shown in fig. 1, the reaction vessel 2 is externally connected with a concentrated sulfuric acid storage tank 3, the deplating waste liquid in the deplating device 1 enters the reaction vessel 2 to be mixed with concentrated sulfuric acid, and the generated solution is distilled, cooled and crystallized in sequence to recover nitric acid and copper sulfate, and the reaction vessel 2 may be a reaction kettle or a distillation flask, for example.

The distillation device 4 is sequentially connected with a condenser 5, a nitric acid collecting tank 6 and a concentration adjusting device 7, nitric acid steam generated by distillation is condensed and then enters the nitric acid collecting tank 6, and then flows into the concentration adjusting device 7 to be subjected to acidity adjustment and then flows back to the deplating device 1. The solid-liquid separation device 9 is externally connected with the reaction vessel 2, and mother liquor generated by solid-liquid separation flows back into the reaction vessel 2 through a connecting pipeline.

The system also comprises a drying device 11 and a copper sulfate storage tank 12, one end of the drying device 11 is connected with the copper sulfate storage tank 12, the other end of the drying device 11 is connected with the solid-liquid separation device 9, and crystals generated by cooling crystallization enter the drying device 11 to be dried and then are sent into the copper sulfate storage tank 12 to be recovered.

Example 1

In this example, 2L of deplating waste liquid was taken to perform an experiment for recovering nitric acid and copper sulfate, and the specific steps thereof are as follows:

(1) putting 1L of deplating waste liquid into a 2L distillation flask, placing the distillation flask on a magnetic heating stirrer, adding 98 wt% of concentrated sulfuric acid while stirring, ensuring that the mole number of the sulfuric acid in the solution is 2 times of that of copper ions, uniformly stirring and mixing for 30min, raising the temperature of a mixed solution to 58 ℃, heating and distilling, condensing nitric acid after vaporization at 10 ℃, adjusting the concentration of the nitric acid condensate to 45% by mass fraction, then sending the nitric acid condensate to a deplating working section, and collecting a distillation residual liquid;

(2) cooling the distillation residual liquid in the step (1) at 10 ℃ for 2h, stirring and crystallizing to separate out copper sulfate crystals, and separating out a mother liquid through solid-liquid separation;

(3) and (3) refluxing the mother liquor obtained in the step (2) to the distillation flask obtained in the step (1), adding 1L of deplating waste liquor, supplementing 98 wt% of concentrated sulfuric acid, ensuring that the mole number of sulfuric acid in the solution is 2 times of that of copper ions, uniformly stirring and mixing for 30min, raising the temperature of the mixed liquor to 58 ℃, heating to 120 ℃ for distillation, condensing nitric acid after vaporization at 10 ℃, sending the nitric acid condensate into a deplating working section after concentration regulation, collecting distillation residual liquor, and repeating the step (2) to obtain a pure copper sulfate product.

The purity of the copper sulfate crystal prepared in the embodiment is 98.8%, the mass fraction of nitric acid obtained by condensation is 36%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is 49.8mL less than that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 98.3%.

Example 2

In this example, 2L of deplating waste liquid was taken to perform an experiment for recovering nitric acid and copper sulfate, and the specific steps thereof are as follows:

(1) putting 1L of deplating waste liquid into a 2L distillation flask, placing the distillation flask on a magnetic heating stirrer, adding 98 wt% of concentrated sulfuric acid while stirring, ensuring that the mole number of sulfuric acid in the solution is 1.8 times of that of copper ions, uniformly stirring and mixing for 25min, raising the temperature of a mixed solution to 55 ℃, heating to 115 ℃ for distillation, condensing nitric acid at 15 ℃ after vaporization, regulating the concentration of a nitric acid condensate to 40% by mass, sending the nitric acid condensate to a deplating working section, and collecting a distillation residual liquid;

(2) cooling the distillation residual liquid in the step (1) at 15 ℃ for 3h, stirring and crystallizing to separate out copper sulfate crystals, and separating out a mother liquid through solid-liquid separation;

(3) and (3) refluxing the mother liquor obtained in the step (2) into the distillation flask obtained in the step (1), adding 1L of deplating waste liquor, supplementing 98 wt% of concentrated sulfuric acid, ensuring that the mole number of sulfuric acid in the solution is 1.8 times of that of copper ions, uniformly stirring and mixing for 25min, raising the temperature of the mixed liquor to 55 ℃, heating and distilling, condensing the vaporized nitric acid at 15 ℃, adjusting the concentration of the nitric acid condensate, and sending the nitric acid to a deplating working section, collecting distillation residual liquor, and repeating the step (2) to obtain a pure copper sulfate product.

The purity of the copper sulfate crystal prepared in the embodiment is 98.6%, the mass fraction of nitric acid obtained by condensation is 33%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is 47.2mL less than that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 98.2%.

Example 3

In this example, 2L of deplating waste liquid was taken to perform an experiment for recovering nitric acid and copper sulfate, and the specific steps thereof are as follows:

(1) putting 1L of deplating waste liquid into a 2L distillation flask, placing the distillation flask on a magnetic heating stirrer, adding 98 wt% of concentrated sulfuric acid while stirring, ensuring that the mole number of sulfuric acid in the solution is 1.6 times of that of copper ions, uniformly stirring and mixing for 35min, raising the temperature of a mixed solution to 60 ℃, heating and distilling, condensing the vaporized nitric acid at 18 ℃, adjusting the concentration of a nitric acid condensate, sending the nitric acid to a deplating working section, and collecting a distillation residual liquid;

(2) cooling the distillation residual liquid in the step (1) at 10 ℃ for 2h, stirring and crystallizing to separate out copper sulfate crystals, and separating out a mother liquid through solid-liquid separation;

(3) and (3) refluxing the mother liquor obtained in the step (2) into the distillation flask obtained in the step (1), adding 1L of deplating waste liquor, supplementing 98 wt% of concentrated sulfuric acid, ensuring that the mole number of sulfuric acid in the solution is 1.6 times of that of copper ions, uniformly stirring and mixing for 35min, raising the temperature of the mixed liquor to 60 ℃, heating to 120 ℃ for distillation, condensing the vaporized nitric acid at 18 ℃, adjusting the concentration of the nitric acid condensate, sending the nitric acid condensate to a deplating working section, collecting the distilled residual liquor, and repeating the step (2) to obtain a pure copper sulfate product.

The purity of the copper sulfate crystal prepared in the embodiment is 98.4%, the mass fraction of nitric acid obtained by condensation is 30%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is 45.7mL less than that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 97.6%.

Example 4

The difference between this example and example 1 is that 98 wt% concentrated sulfuric acid in step (1) and step (4) is replaced by 90 wt% sulfuric acid, deplating waste liquid is mixed with 90 wt% sulfuric acid, the mixture is stirred and mixed evenly for 30min, the temperature of the mixed liquid is raised to 50 ℃, and other conditions are completely the same as those in example 1.

The purity of the copper sulfate crystal prepared in the embodiment is 97.3%, the mass fraction of nitric acid obtained by condensation is 23%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is 38.7mL less than that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 97.1%.

Example 5

This example is different from example 1 in that the number of moles of sulfuric acid in step (1) is 2.5 times the number of moles of copper ions, and other conditions are completely the same as those in example 1.

The purity of the copper sulfate crystal prepared in the embodiment is 98.1%, the mass fraction of nitric acid obtained by condensation is 33%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is 40.2mL less than that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 83.4%.

Comparative example 1

In this example, 2L of deplating waste liquid was taken to perform an experiment for recovering nitric acid and copper sulfate, and the specific steps thereof are as follows:

(1) putting 1L of deplating waste liquid into a 2L distillation flask, placing the distillation flask on a magnetic heating stirrer, adding 98 wt% of concentrated sulfuric acid while stirring, ensuring that the mole number of the sulfuric acid in the solution is 2 times of that of copper ions, uniformly stirring and mixing for 30min, raising the temperature of a mixed solution to 58 ℃, heating and distilling, condensing the vaporized nitric acid at 10 ℃, adjusting the concentration of the nitric acid condensate, sending the nitric acid to a deplating working section, and collecting a distillation residual liquid;

(2) cooling the distillation residual liquid in the step (1) at 10 ℃ for 2h, stirring and crystallizing to separate out copper sulfate crystals, and separating out the mother liquid through solid-liquid separation.

(3) And (3) adding 1L of deplating waste liquid into the distillation flask, and repeating the steps (1) and (2) without refluxing the mother liquid in the step (2) to obtain a pure copper sulfate product.

The purity of the copper sulfate crystal prepared in the embodiment is 98.7%, the mass fraction of nitric acid obtained by condensation is 36%, the addition amount of concentrated sulfuric acid supplemented in the step (3) is the same as that of concentrated sulfuric acid in the step (1), and the utilization rate of the concentrated sulfuric acid is 98.4%.

In the embodiment 1 of the invention, 98 wt% of concentrated sulfuric acid is mixed with deplating waste liquid, the purity of the prepared copper sulfate crystal is 98.8%, and the mass fraction of nitric acid obtained by condensation is 36%, while in the embodiment 4, when 90% of concentrated sulfuric acid is used, the purity of the prepared copper sulfate crystal and the mass fraction of the recovered nitric acid are obviously reduced, mainly because when the concentration of sulfuric acid is low, a large amount of reaction heat cannot be generated after the copper sulfate crystal is mixed with the waste liquid, the evaporation capacity of the mixed liquid is reduced, so that extra heating quantity needs to be provided, and the energy consumption is increased. And the concentration of the recovered nitric acid is low, and if the prepared nitric acid is recycled to a deplating working section, the addition amount of the nitric acid needs to be increased to reach the recycling standard, so that the recycling value of the nitric acid is reduced. In comparative example 1 of the present invention, the copper sulfate mother liquor was not recovered, and therefore, when the remaining 1L of deplating waste liquor was treated, additional concentrated sulfuric acid was required, which was not favorable for maintaining the balance of the sulfuric acid concentration in the system.

According to the method and the system for recycling the nitric acid and the copper sulfate from the deplating waste liquid, provided by the invention, the nitric acid and copper ions in the deplating waste liquid are recycled and utilized as resources, corresponding products are obtained, the resource utilization rate is high, and the nitric acid recycling value is improved; the high-quality copper sulfate product is crystallized by cooling twice, which is beneficial to the sale of the product; and the generated mother liquor flows back to the reaction process of the deplating waste liquor and the sulfuric acid, the required sulfuric acid is supplemented, the balance of the concentration of the sulfuric acid in the system is kept, the whole system is in closed circulation, zero emission is realized, and the environmental pollution is avoided.

The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are within the scope and disclosure of the present invention.