Method for treating acid copper chloride etching waste liquid and fully recycling acid copper chloride etching waste liquid by using thermal precipitation method
阅读说明：本技术 一种热析法处理酸性氯化铜蚀刻废液全回收的方法 (Method for treating acid copper chloride etching waste liquid and fully recycling acid copper chloride etching waste liquid by using thermal precipitation method ) 是由 叶自洁 宋传京 杨江丽 邹毅芳 陆严宏 乔贞 田洋 刘鹏 于 2021-07-02 设计创作，主要内容包括：本发明公开了一种热析法处理酸性氯化铜蚀刻废液全回收的方法,包括如下步骤：向氯化铜蚀刻废液中加入氧化剂进行预处理,搅拌反应5～10min；将S1中氧化预处理后的氯化铜蚀刻废液进行蒸发处理,当蚀刻废液的液量为原液量的60％～80％时停止蒸发处理,蒸发过程产生的蒸气进行冷却回收,得到盐酸；将S2中蒸发处理后的氯化铜蚀刻废液进行热析处理,通过冷凝水将该氯化铜蚀刻废液交换冷却至40～50℃,析出氯化钠晶体,并进行固液分离,回收氯化钠晶体；将S3中固液分离后得到的溶液继续冷却至室温,析出二水氯化铜晶体,并进行固液分离,回收二水氯化铜。本发明技术方案改善现有的蚀刻废液处理工艺,实现蚀刻废液的全回收利用。(The invention discloses a method for treating acid copper chloride etching waste liquid and fully recovering the acid copper chloride etching waste liquid by a thermal precipitation method, which comprises the following steps: adding an oxidant into the copper chloride etching waste liquid for pretreatment, and stirring and reacting for 5-10 min; evaporating the copper chloride etching waste liquid subjected to oxidation pretreatment in the step S1, stopping evaporation when the liquid amount of the etching waste liquid is 60-80% of the original liquid amount, and cooling and recovering steam generated in the evaporation process to obtain hydrochloric acid; carrying out heat precipitation treatment on the copper chloride etching waste liquid subjected to evaporation treatment in the step S2, carrying out exchange cooling on the copper chloride etching waste liquid to 40-50 ℃ through condensed water, precipitating sodium chloride crystals, carrying out solid-liquid separation, and recovering the sodium chloride crystals; and (4) continuously cooling the solution obtained after the solid-liquid separation in the step (S3) to room temperature, precipitating copper chloride dihydrate crystals, carrying out solid-liquid separation, and recovering the copper chloride dihydrate. The technical scheme of the invention improves the existing etching waste liquid treatment process and realizes the full recycling of the etching waste liquid.)
1. A method for treating acid copper chloride etching waste liquid and fully recovering the acid copper chloride etching waste liquid by a thermal precipitation method is characterized by comprising the following steps:
s1: adding an oxidant into the copper chloride etching waste liquid for pretreatment, and stirring and reacting for 5-10 min;
s2: evaporating the copper chloride etching waste liquid subjected to oxidation pretreatment in the step S1, stopping evaporation when the liquid amount of the etching waste liquid is 60-80% of the original liquid amount, and cooling and recovering steam generated in the evaporation process to obtain hydrochloric acid;
s3: carrying out heat precipitation treatment on the copper chloride etching waste liquid subjected to evaporation treatment in the step S2, carrying out exchange cooling on the copper chloride etching waste liquid to 40-50 ℃ through condensed water, precipitating sodium chloride crystals, carrying out solid-liquid separation, and recovering the sodium chloride crystals;
s4: and (4) continuously cooling the solution obtained after the solid-liquid separation in the step (S3) to room temperature, precipitating copper chloride dihydrate crystals, carrying out solid-liquid separation, and recovering the copper chloride dihydrate.
2. The method for treating and recycling the acidic copper chloride etching waste liquid by a thermal precipitation method according to claim 1, wherein the oxidant in the step S1 comprises hydrogen peroxide or sodium chlorate or oxygen or air.
3. The method for treating the acidic copper chloride etching waste liquid and fully recycling the acidic copper chloride etching waste liquid by the thermoeutectoid method as claimed in claim 2, wherein the oxidant is 27.5% of hydrogen peroxide, and the addition amount of the hydrogen peroxide is 0.1-1.0% of the mass of the copper chloride etching waste liquid.
4. The method for treating the acidic copper chloride etching waste liquid by the thermal precipitation method for full recovery according to claim 1, wherein in the step S2, the vapor generated by evaporation is cooled by a graphite cooler and then enters a multi-stage circulating falling film absorption device for absorption so as to recover hydrochloric acid.
5. The method for treating the acidic copper chloride etching waste liquid by the thermal precipitation method for full recovery according to claim 1 or 4, wherein the hydrochloric acid can be used for producing high-concentration hydrochloric acid or a backwash liquid for a copper ion exchange column.
6. The method for treating and fully recovering the acidic copper chloride etching waste liquid by the thermoeduction method according to claim 1, wherein the sodium chloride crystals are crude sodium chloride, the crude sodium chloride can be used for preparing etching sub-liquid and returning to an etching section for use, or a saturated sodium chloride solution is adopted for washing and solid-liquid separation to prepare an industrial-grade sodium chloride product meeting national standards, wherein a washing liquid can be periodically opened for recycling after copper precipitation through acidity adjustment, and copper sludge generated by washing can be dissolved in the acidic etching liquid to prepare copper chloride dihydrate.
7. The method for treating acidic copper chloride etching waste liquid and fully recovering the etching waste liquid by a thermal precipitation method according to claim 1, wherein the solid-liquid separation method in the steps S3 and S4 comprises a centrifugal or filter-pressing solid-liquid separation mode.
Technical Field
The invention relates to the technical field of waste liquid treatment, in particular to a method for treating acid copper chloride etching waste liquid and fully recycling the acid copper chloride etching waste liquid by a thermal precipitation method.
Background
The acidic etching waste liquid is generated in an etching working section of a PCB production enterprise, along with the continuous etching, the etching speed of copper ions in the etching liquid is greatly reduced after the copper ions reach a certain concentration, the stability of the etching liquid is reduced, the etching effect is interfered, and the etching liquid is discharged from an etching system to form the etching waste liquid. The main components of the waste liquid generated by the hydrochloric acid-sodium chlorate system etching liquid are copper chloride, hydrochloric acid, sodium chloride and the like, the content of copper is about 10%, the content of hydrochloric acid is 1.5-2.5mol/L, and the content of sodium is 2-6%. The existing treatment technology mainly focuses on the recovery of copper resources, such as copper extraction regeneration by an electrolytic method, copper salt product preparation by acid-base neutralization precipitation, and copper extraction treatment by active metal replacement, and other resources are separated out in the form of miscellaneous salts and cannot be effectively utilized.
Patent CN 106587105B describes a method for recovering acidic etching solution of copper chloride in printed circuit board, which comprises adding sodium chloride solution into acidic etching waste solution, recovering hydrochloric acid by evaporation and condensation, diluting with water, neutralizing with alkali to recover copper hydroxide to prepare copper sulfate, and finally evaporating to recover sodium chloride. The method can effectively recover copper, hydrochloric acid and sodium chloride, but the water amount for dilution is 4-6 times of the volume of the solution after distillation, 1-2mol/L of liquid alkali is adopted for neutralization after evaporation, and copper hydroxide is subjected to twice countercurrent washing, so that the water amount is extremely large, the subsequent evaporation amount is large, and the energy consumption is high; the process of copper recovery adopts alkali liquor, the treatment cost is high, and the additionally introduced sodium chloride still needs to be recovered in an evaporation mode finally.
In the patent CN 102367179A, the method for preparing copper sulfide, copper chloride and sodium chloride by using waste residue copper sludge indicates that a mixed solution of copper chloride and sodium chloride realizes separation of copper chloride and sodium chloride by utilizing solubility difference, the sodium chloride is recovered at 80 ℃, and the copper chloride is recovered at 0 ℃. The method can realize the separation of partial copper chloride and sodium chloride, but the separation is not complete. In the case of high chloride ion concentrations in the solution, heating promotes the combination of sodium chloride with copper chloride to form sodium tetrachlorocuprate, i.e.Under the condition of 80 ℃, 1mol of copper chloride in the solution subjected to solid-liquid separation is still combined with 2mol of sodium chloride, so that a large amount of sodium chloride still remains in the separated copper chloride solution, and the copper chloride are simultaneously separated out during cooling to directly influence the quality of the copper chloride; the method simultaneously uses a freezing crystallization method to separate out the copper chloride, the method has high energy consumption, and the refrigerant has certain environmental protection risks.
Accordingly, the prior art is deficient and needs improvement.
Disclosure of Invention
The invention mainly aims to provide a method for treating and fully recycling acidic copper chloride etching waste liquid by a thermal precipitation method, aiming at improving the existing etching waste liquid treatment process and realizing the full recycling of the etching waste liquid.
In order to realize the purpose, the invention provides a method for treating acid copper chloride etching waste liquid by a thermal precipitation method and fully recovering the acid copper chloride etching waste liquid, which comprises the following steps:
s1: adding an oxidant into the copper chloride etching waste liquid for pretreatment, and stirring and reacting for 5-10 min;
s2: evaporating the copper chloride etching waste liquid subjected to oxidation pretreatment in the step S1, stopping evaporation when the liquid amount of the etching waste liquid is 60-80% of the original liquid amount, and cooling and recovering steam generated in the evaporation process to obtain hydrochloric acid;
s3: carrying out heat precipitation treatment on the copper chloride etching waste liquid subjected to evaporation treatment in the step S2, carrying out exchange cooling on the copper chloride etching waste liquid to 40-50 ℃ through condensed water, precipitating sodium chloride crystals, carrying out solid-liquid separation, and recovering the sodium chloride crystals;
s4: and (4) continuously cooling the solution obtained after the solid-liquid separation in the step (S3) to room temperature, precipitating copper chloride dihydrate crystals, carrying out solid-liquid separation, and recovering the copper chloride dihydrate.
Preferably, the oxidant in step S1 includes hydrogen peroxide or sodium chlorate or oxygen or air.
Preferably, the oxidant is 27.5% of hydrogen peroxide, and the addition amount of the hydrogen peroxide is 0.1-1.0% of the mass of the copper chloride etching waste liquid.
Preferably, in step S2, the vapor generated by evaporation is cooled by a graphite cooler and then enters a multi-stage circulating falling film absorption device for absorption to recover hydrochloric acid.
Preferably, the hydrochloric acid can be used to produce high concentrations of hydrochloric acid or backwash liquids for copper ion exchange columns.
Preferably, the sodium chloride crystal is crude sodium chloride, the crude sodium chloride can be used for configuring an etching solution and returning to an etching section for use, or a saturated sodium chloride solution is adopted for washing, and solid-liquid separation is carried out to prepare an industrial sodium chloride product meeting the national standard, wherein a washing solution can be periodically opened for recycling after copper deposition through acidity adjustment, and copper sludge generated by washing can be dissolved in an acidic etching solution to prepare copper chloride dihydrate.
Preferably, the solid-liquid separation method in step S3 and step S4 includes a centrifugal or filter-pressing solid-liquid separation method.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the method for separating sodium salt in the prior art, the method adopts thermal precipitation to remove sodium at the temperature of 35-50 ℃, thereby effectively avoiding the defect of extremely poor separation effect caused by the complex formed by sodium chloride and copper chloride under the conditions of high temperature, high chlorine and high copper content;
2. the treatment in the factory does not need a hazardous waste transfer union, reduces the waste transfer risk, and achieves the recycling and regeneration of resources in the factory;
3. compared with the acid etching waste liquid regenerated by an electrolytic method, the process is simple, the energy consumption is low, and the in-field chemical regeneration of the etching waste liquid is realized;
4. the separation effect of copper chloride and sodium chloride is excellent, the quality of resource recovery products is high, the copper chloride content of the copper chloride products is more than or equal to 98.0 percent, and the sodium content is less than 100 ppm; the sodium chloride product sodium chloride is more than or equal to 93.3 percent, and the product can reach the relevant national standard;
5. the resources are fully recovered, the main components of hydrochloric acid, sodium chloride and copper chloride in the etching waste liquid are effectively recovered, and the zero discharge of the waste water is realized;
6. compared with the traditional production of copper chloride dihydrate, the method directly recovers from the etching waste liquid, does not have the use and storage of extra hydrochloric acid or copper source chemical raw materials, and has short production flow and low cost;
7. fully realizing the full recovery of the etching waste liquid of the hydrochloric acid-sodium chlorate system: recovering hydrochloric acid from the etching waste liquid to prepare a 5-20% hydrochloric acid solution which can be used as a backwashing liquid of a copper ion exchange column or used for preparing an acidic etching solution; the sodium chloride can be recycled to prepare industrial-grade sodium chloride or be reused for preparing etching solution; the copper chloride can be recovered to prepare a copper chloride dihydrate product.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic flow diagram of the process of the present invention;
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The method for treating the acidic copper chloride etching waste liquid by the thermal precipitation method and fully recycling the acidic copper chloride etching waste liquid provided by the embodiment refers to fig. 1, and comprises the following steps:
s1: adding an oxidant into the copper chloride etching waste liquid for pretreatment, and stirring and reacting for 5-10 min; it should be noted that, because the acidic copper chloride etching waste liquid contains cuprous ions, a pretreatment process is required before evaporation, and an oxidant is added into the acidic copper chloride etching waste liquid, where the oxidant includes hydrogen peroxide, sodium chlorate, oxygen or air, in this embodiment, the oxidant is 27.5% hydrogen peroxide, and the addition amount of the hydrogen peroxide is 0.1% -1.0% of the mass of the copper chloride etching waste liquid, and the addition amount of other oxidants is converted according to the oxidation equivalent of the hydrogen peroxide, preferably the hydrogen peroxide, and the stirring reaction is performed for 5-10min to oxidize the cuprous ions into cupric ions, so as to prevent the cuprous ions from forming a complex [ NaH (CuCl) with sodium and chloride ions in the waste liquid system3)]Which prevents subsequent removal of sodium chloride and recovery of copper.
S2: evaporating the copper chloride etching waste liquid subjected to oxidation pretreatment in the step S1, stopping evaporation when the liquid amount of the etching waste liquid is 60-80% of the original liquid amount, and cooling and recovering steam generated in the evaporation process to obtain hydrochloric acid; in this embodiment, the vapor generated by evaporation is cooled by a graphite cooler and then enters a multistage circulating falling film absorption device for absorption to recover hydrochloric acid, the three-stage circulating falling film absorption device is preferred in this embodiment, the concentration of the recovered hydrochloric acid is 10% -20%, and the device can be used in other working sections to produce high-concentration hydrochloric acid or a backwash liquid for a copper ion exchange column, so that the hydrogen chloride resource in the etching waste liquid can be fully recovered and utilized.
S3: carrying out heat precipitation treatment on the copper chloride etching waste liquid subjected to evaporation treatment in the step S2, carrying out exchange cooling on the copper chloride etching waste liquid to 40-50 ℃ through condensed water, precipitating sodium chloride crystals, carrying out solid-liquid separation, and recovering the sodium chloride crystals; it should be noted that as the temperature decreases, the reaction in the system proceeds And (3) moving reversely, gradually releasing sodium chloride and copper chloride from the sodium tetrachlorocuprate, precipitating the sodium chloride as crystals of cubic crystal form when the sodium chloride is saturated, keeping the copper chloride in the solution due to higher solubility, realizing solid-liquid separation in a centrifugal or filter pressing mode, transferring the crystals, namely crude sodium chloride, and transferring the filtrate to a crystallization kettle to continue cooling to room temperature to recover the copper chloride. The crude sodium chloride can be used for preparing etching solution and returning to an etching section for use, or a saturated sodium chloride solution is adopted for washing, and solid-liquid separation is carried out to prepare an industrial-grade sodium chloride product meeting the national standard. The washing liquid is periodically opened for copper deposition through acidity adjustment and is recycled, and the generated extremely small amount of copper mud is dissolved in the acidic etching liquid to prepare the copper chloride dihydrate.
S4: and (4) continuously cooling the solution obtained after the solid-liquid separation in the step (S3) to room temperature, precipitating copper chloride dihydrate crystals, carrying out solid-liquid separation, and recovering the copper chloride dihydrate. It should be noted that the solution after thermal precipitation and sodium removal is a saturated solution of copper chloride, and a large amount of copper chloride dihydrate crystals can be precipitated by continuously cooling to room temperature. Along with the cooling process, a large amount of copper chloride crystals are separated out, the same ion effect is weakened, the solubility of residual sodium chloride in the solution is increased, and the influence of the sodium chloride on the quality of the copper chloride dihydrate product is further reduced. The copper content of the copper chloride dihydrate product recovered by centrifugal separation is more than or equal to 98.0 percent, and the sodium content is less than 100 ppm.
The method is illustrated below by means of specific examples:
the first embodiment is as follows:
at 3m3Pumping 2m into the reaction kettle3Adding 7kg of 27.5% hydrogen peroxide into the acidic copper chloride etching waste liquid, stirring and reacting for 8min, starting a steam valve to perform evaporation treatment, cooling water vapor generated by evaporation through a pipeline to a cooler, allowing the cooled water vapor to enter a three-stage circulating absorption system for absorption, obtaining a dilute hydrochloric acid solution with the concentration of 13%, pumping the hydrochloric acid solution to a temporary storage tank for temporary storage after the evaporation is finished, and directly applying the hydrochloric acid solution to copper ionBackwashing of the sub-exchange column or production of high concentration hydrochloric acid. And (3) stopping heating after the liquid level in the kettle is reduced by 1/4 after evaporation, opening a cooling water system to cool the materials to 43 ℃, and then performing filter pressing treatment, wherein filter residues are sodium chloride crystals, the content of sodium chloride (wet basis) is 90.3%, the filtrate is transferred into a crystallization kettle to be continuously cooled to room temperature for crystallization, centrifugal separation is performed to obtain a copper chloride dihydrate product, and the crystallization mother liquor is returned to the front end for evaporation treatment. The content of copper chloride dihydrate was 98.2% and the content of sodium was 53 ppm.
Example two:
at 3m3Pumping 2m into the reaction kettle36.5kg of 27.5% hydrogen peroxide is added into the acidic copper chloride etching waste liquid, after stirring and reacting for 10min, a steam valve is opened to start evaporation treatment, water vapor generated by evaporation is cooled in a cooler through a pipeline and enters a three-stage circulating absorption system to be absorbed, a dilute hydrochloric acid solution with the concentration of 10% can be obtained, and after the evaporation is finished, the hydrochloric acid solution is pumped into a temporary storage tank for temporary storage, so that the method can be directly applied to the backwashing of a copper ion exchange column or the production of high-concentration hydrochloric acid. Evaporating until the liquid level in the kettle drops to 1/4, stopping heating, cooling to 45 ℃, performing filter pressing treatment, wherein filter residues are sodium chloride crystals, the content of sodium chloride (wet basis) is 90.8%, transferring the filtrate into a crystallization kettle, continuously cooling to room temperature for crystallization, performing centrifugal separation to obtain a copper chloride dihydrate product, and returning the crystallization mother liquor to the front end for evaporation treatment. The content of copper chloride dihydrate was 98.5% and the content of sodium was 45 ppm. The crude sodium chloride contains a small amount of copper, is washed for 3 times by adopting a saturated sodium chloride solution, and is centrifugally separated to obtain white crystal sodium chloride, wherein the content of the sodium chloride is 94.4 percent, and the content of the copper is less than 5 ppm. The filtrate is recycled, sodium hydroxide is added after a circuit is opened periodically for acidity adjustment and copper precipitation, and the supernatant or liquid generated by solid-liquid separation is recycled as a saturated sodium chloride solution to be washed by sodium chloride crystals. The generated small amount of copper hydroxide is used for pretreatment of the etching waste liquid, and copper resources are further recovered in the form of copper chloride.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.