A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid

Abstract

The present invention provides a method for preparing electronic-grade copper oxide from waste acidic etching liquid from circuit boards, belonging to the field of copper resource recovery. The method comprises: sequentially subjecting the waste acidic etching liquid from circuit boards to impurities removal, concentration and crystallization, and salt-alkali reaction, followed by cleaning and collection to obtain crude copper hydroxide; dissolution and recrystallization to obtain refined copper hydroxide; addition of a carbonized ammonia solution to the refined copper hydroxide for reaction, adsorption and purification to obtain ammoniacal copper carbonate; addition of a surfactant and a zinc salt additive for stirring; drying to obtain modified basic copper carbonate; selective etching of the modified basic copper carbonate with dilute acid to obtain basic copper carbonate particles; and calcination of the basic copper carbonate particles at 300°C to 500°C to obtain copper oxide powder with a honeycomb structure. This method enhances the basic steps of copper resource recovery from waste acidic etching liquid from circuit boards by adding purification, grain refinement, and porous etching to improve the purity and activity of the final copper oxide product, thereby producing electronic-grade copper oxide.

Description

Technical Field

[0001] The invention belongs to the technical field of copper resource recovery, and in particular relates to a method for preparing electronic-grade copper oxide by utilizing circuit board acid etching waste liquid. Background Art

[0002] Circuit board etching utilizes an oxidation reaction between metal and etching solution to remove the copper foil covering the circuit board surface. Currently, acidic solutions are commonly used in etching single-sided and multi-layer circuit boards. This process generates a large amount of acidic etching waste liquid. Due to its high copper content, this waste liquid is classified as a hazardous waste by the government. If discharged without treatment, it poses a serious threat to the environment.

[0003] At present, the treatment of circuit board acid etching waste liquid is mainly based on resource recovery, and its mainstream methods include: impurity removal, evaporation concentration, chemical reaction + electroosmosis to produce copper salt precipitation, and high-temperature calcination to obtain copper oxide.

[0004] Although the above method produces copper oxide with a purity greater than 98%, it still suffers from defects such as high impurity content and slow acid dissolution rate. This makes it suitable only as a conventional copper oxide for use in less demanding industries, and it cannot be used as the electronic-grade copper oxide required in electronics industries such as printed circuit boards, semiconductors, photovoltaics, electronic packaging, and lithium-ion batteries. In the electronics industry, copper oxide with low purity and slow acid dissolution rate can lead to low process efficiency, unstable plating solutions, and low product quality. Summary of the Invention

[0005] In view of this, the object of the present invention is to provide a method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, aiming to solve at least one technical problem among the background technology.

[0006] The present invention is achieved in that:

[0007] The present invention provides a method for preparing electronic-grade copper oxide by utilizing circuit board acid etching waste liquid, which comprises the following steps:

[0008] The circuit board acid etching waste liquid is sequentially subjected to impurity removal, concentration crystallization, and salt-alkali reaction, and then cleaned and collected to obtain a crude copper hydroxide product;

[0009] Dissolving and recrystallizing the crude copper hydroxide product using dilute acid and strong base to obtain refined copper hydroxide;

[0010] Adding a carbonized ammonia solution to react with the copper hydroxide product, adsorbing and purifying the reaction product to obtain ammoniacal copper carbonate; adding a surfactant and a zinc salt additive, stirring to perform grain control treatment; and then drying to obtain modified basic copper carbonate with a high specific surface area;

[0011] Selectively etching the modified basic copper carbonate with dilute acid to obtain basic copper carbonate particles with a porous structure;

[0012] Basic copper carbonate particles are calcined at 300°C to 500°C to obtain copper oxide powder with a honeycomb structure.

[0013] Preferably, the specific steps of preparing modified basic copper carbonate from the refined copper hydroxide include:

[0014] Add the fine copper hydroxide to the carbonized ammonia solution and stir evenly until it is completely converted into ammoniacal copper carbonate solution;

[0015] Adsorbents are used to purify ammoniacal copper carbonate solutions;

[0016] Simultaneously add a preset amount of surfactant and zinc salt additive and stir to perform grain control treatment;

[0017] The modified basic copper carbonate powder is obtained by treating the ammoniacal copper carbonate solution with controlled crystal grains through a spray drying method.

[0018] Preferably, the surfactant is polyvinyl alcohol; the amount of the surfactant used is 1 wt% to 2 wt% of ammoniacal copper carbonate.

[0019] Preferably, the zinc salt additive is zinc acetate, and the amount of the zinc salt additive is 0.05wt% to 0.1wt% of the ammoniacal copper carbonate.

[0020] Preferably, the steps of sequentially performing impurity removal, concentration crystallization, and salt-alkali reaction on the circuit board acid etching waste liquid, and collecting the crude copper hydroxide after cleaning, specifically include:

[0021] Filtering circuit board acid etching waste liquid to remove insoluble impurities;

[0022] The filtered acidic etching waste liquid is evaporated and concentrated to obtain a high-concentration copper chloride solution;

[0023] Slowly add an appropriate amount of sodium hydroxide solution to adjust the pH to 8-9 to generate copper hydroxide precipitate;

[0024] The copper hydroxide precipitate was filtered and washed with deionized water to obtain crude copper hydroxide.

[0025] Preferably, the specific steps of dissolving and recrystallizing the crude copper hydroxide product using dilute acid and strong base to obtain fine copper hydroxide are:

[0026] First, dilute acetic acid is used to dissolve the crude copper hydroxide, and then sodium hydroxide is added for recrystallization to obtain fine copper hydroxide.

[0027] Preferably, the calcination is specifically as follows: placing the basic copper carbonate particles in an oxygen environment, heating the temperature to 300° C. to 500° C. at a rate of 1° C. / min to 5° C. / min, and keeping the temperature for 2 h to 4 h.

[0028] Preferably, the step of selectively etching the modified basic copper carbonate with dilute acid specifically comprises:

[0029] A preset amount of modified basic copper carbonate is added to a dilute acetic acid solution, stirred rapidly for several minutes, and then quickly washed by centrifugation with deionized water to obtain porous basic copper carbonate powder.

[0030] Preferably, the molar ratio of modified basic copper carbonate to dilute acetic acid is 15-25:1.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. In addition to the basic steps of recovering copper resources from acidic etching waste liquid of circuit boards, the present invention adds purification, recrystallization, grain refinement and porous structure etching to improve the purity and performance of the final copper oxide product and produce electronic grade copper oxide.

[0033] 2. The present invention adds a surfactant in the copper resource recovery step, which is adsorbed on the particle surface to inhibit excessive aggregation and promote crystal refinement and uniform growth.

[0034] 3. The present invention adds a trace amount of zinc acetate to the ammoniacal copper carbonate solution, which changes the growth environment of the basic copper carbonate crystals, further refines the crystal size and promotes their uniform growth.

[0035] 4. The present invention obtains a modified basic copper carbonate intermediate with a high specific surface area from an ammonia copper carbonate solution after purification and grain control treatment by spray drying.

[0036] 5. The process route of the present invention not only improves the purity and specific surface area of ​​the final copper oxide product, but also particularly emphasizes the importance of environmental protection and resource recycling. The entire process does not release chlorine gas or discharge high-salt wastewater, and is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flow chart of a method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid;

[0038] Figure 2 This is a scanning electron microscope image of the copper oxide prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] like Figure 1 As shown, a method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, the steps are as follows:

[0041] S1, pretreatment and impurity removal: filter the circuit board acid etching waste liquid to remove insoluble impurities.

[0042] S2, evaporation and concentration: evaporating and concentrating the filtered acidic etching waste liquid to obtain a high-concentration copper chloride solution.

[0043] S3, preparation of copper hydroxide by salt-alkali reaction: slowly adding an appropriate amount of sodium hydroxide solution to a high-concentration copper chloride solution to adjust the pH to 8-9 to generate copper hydroxide precipitate; filtering and washing the copper hydroxide powder with deionized water to remove residual chloride and other impurities to obtain crude copper hydroxide.

[0044] S4, Dissolution + Recrystallization: Dissolve and recrystallize the crude copper hydroxide using dilute acid and strong base to obtain fine copper hydroxide. Specifically, add a sufficient amount of dilute acid (e.g., dilute acetic acid at a concentration of approximately 10%) to the crude copper hydroxide to redissolve the crude copper hydroxide to obtain a copper salt solution (e.g., copper acetate solution). A strong base (e.g., sodium hydroxide at a concentration of approximately 35%) is added to adjust the pH of the solution to regenerate a copper hydroxide precipitate. The precipitate is further purified by dissolution + recrystallization, followed by filtration, washing, and drying to obtain fine copper hydroxide.

[0045] S5, synthesis of ammonia copper carbonate: carbon dioxide gas is introduced into an ammonia solution to generate a carbonized ammonia solution, and the fine copper hydroxide prepared in S4 is added and stirred evenly until it is completely converted into ammonia copper carbonate.

[0046] S6, adsorption purification: Use adsorbents (such as activated carbon, silica gel, molecular sieve, etc.) for adsorption or other purification methods to further purify the ammoniacal copper carbonate solution, remove organic impurities, and purify the color.

[0047] S7, grain control treatment: adding a preset amount of surfactant and zinc salt additive to the ammoniacal copper carbonate solution after adsorption purification in S6, and stirring to perform grain control treatment.

[0048] Surfactant: Add an appropriate amount of surfactant (such as polyvinyl alcohol (PVA)) to the ammoniacal copper carbonate solution. This surfactant can be adsorbed on the surface of the particles, preventing them from excessive aggregation and facilitating the growth of small and uniform crystals. The amount of surfactant used is 1wt%~2wt% of the ammoniacal copper carbonate.

[0049] Zinc salt additive: Adding a trace amount of zinc salt (such as zinc acetate) to the ammoniacal copper carbonate solution can change the growth environment of the crystal, help refine the basic copper carbonate grain size and promote uniform growth; the dosage of the zinc salt additive is 0.05wt%~0.1wt% of the ammoniacal copper carbonate.

[0050] S8, spray drying: obtaining modified basic copper carbonate with high specific surface area from the ammonia copper carbonate solution after purification and grain control treatment by spray drying.

[0051] S9, Selective Etching: Selectively etching the modified basic copper carbonate using a specific chemical reagent (e.g., a dilute acid solution) to remove some of the material, thereby forming a porous basic copper carbonate powder. Specifically, a predetermined amount of modified basic copper carbonate is added to a dilute acetic acid solution, rapidly stirred for 5 minutes, and then quickly washed with deionized water by centrifugation to obtain a porous basic copper carbonate powder. The molar ratio of modified basic copper carbonate to dilute acetic acid is 15-25:1, preferably 20:1.

[0052] S10, high-temperature calcination in air: calcining the basic copper carbonate powder treated in S9 under precisely controlled conditions, and obtaining high-purity copper oxide powder with a honeycomb structure after cooling; wherein the calcination conditions are specifically as follows: placing the basic copper carbonate particles in air or oxygen environment, heating to 300°C~500°C at a rate of 1°C / min~5°C / min, and keeping the temperature for 2h~4h.

[0053] Example 1

[0054] A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, comprising the following steps:

[0055] S1, pretreatment and impurity removal: filter the circuit board acid etching waste liquid to remove insoluble impurities.

[0056] S2, evaporation and concentration: evaporating and concentrating the filtered acidic etching waste liquid to obtain a high-concentration copper chloride solution.

[0057] S3, preparing copper hydroxide by salt-alkali reaction: slowly adding an appropriate amount of sodium hydroxide solution to a high-concentration copper chloride solution to adjust the pH value to 8 to generate copper hydroxide precipitate; filtering and washing the copper hydroxide powder with deionized water to obtain a crude copper hydroxide product.

[0058] S4, dissolution + recrystallization: First, fully dissolve the crude copper hydroxide in dilute acetic acid with a mass concentration of 10%, slowly add an appropriate amount of sodium hydroxide solution to adjust the pH value to 8.5, and regenerate copper hydroxide precipitate. After standing, filter, wash repeatedly with clean water and dry in turn to obtain fine copper hydroxide.

[0059] S5, synthesis of ammonia copper carbonate: carbon dioxide gas is introduced into an ammonia solution to generate a carbonized ammonia solution, and the fine copper hydroxide prepared in S4 is added and stirred evenly until it is completely converted into ammonia copper carbonate.

[0060] S6, adsorption purification: Use activated carbon adsorption to purify the ammoniacal copper carbonate solution.

[0061] S7, grain control treatment: add surfactant polyvinyl alcohol (polyvinyl alcohol dosage is 1wt% of the ammoniacal copper carbonate) and zinc salt additive zinc acetate (zinc acetate dosage is 0.05wt% of the ammoniacal copper carbonate) to the ammoniacal copper carbonate solution purified by adsorption in S6, and stir evenly.

[0062] S8, spray drying: treating the ammoniacal copper carbonate solution obtained in S7 by spray drying to obtain modified basic copper carbonate powder.

[0063] S9, selective etching: adding the modified basic copper carbonate to a 10% dilute acetic acid solution at a molar ratio of modified basic copper carbonate to dilute acetic acid = 20:1 for selective etching to remove some substances. After rapid stirring for 5 minutes, the solution was quickly centrifuged and washed with deionized water to obtain a porous basic copper carbonate powder.

[0064] S10, high-temperature calcination in air: The basic copper carbonate powder treated in S9 is placed in an air environment, heated to 400°C at a rate of 1°C / min, kept at this temperature for 4 hours, and cooled to obtain high-purity copper oxide powder, the electron microscope scanning image of which is as follows: Figure 2 As shown in Figure 2, copper oxide has a honeycomb structure inside and a large specific surface area.

[0065] Example 2

[0066] A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, comprising the following steps:

[0067] S1, pretreatment: filter the circuit board acid etching waste liquid to remove insoluble impurities.

[0068] S2, evaporation and concentration: evaporating and concentrating the filtered acidic etching waste liquid to obtain a high-concentration copper chloride solution.

[0069] S3, preparing copper hydroxide by salt-alkali reaction: slowly adding an appropriate amount of sodium hydroxide solution to a high-concentration copper chloride solution to adjust the pH to 8.5 to generate copper hydroxide precipitate; filtering and washing the copper hydroxide powder with deionized water to obtain a crude copper hydroxide product.

[0070] S4, dissolution + recrystallization: First, fully dissolve the crude copper hydroxide in dilute acetic acid with a mass concentration of 10%, slowly add an appropriate amount of sodium hydroxide solution to adjust the pH value to 8.5, and regenerate copper hydroxide precipitate. After standing, filter, wash repeatedly with clean water and dry in turn to obtain fine copper hydroxide.

[0071] S5, synthesis of ammonia copper carbonate: carbon dioxide gas is introduced into an ammonia solution to generate a carbonized ammonia solution, and the fine copper hydroxide prepared in S4 is added and stirred evenly until it is completely converted into ammonia copper carbonate.

[0072] S6, adsorption purification: Use activated carbon adsorption to purify the ammoniacal copper carbonate solution.

[0073] S7, grain control treatment: add surfactant polyvinyl alcohol (polyvinyl alcohol dosage is 1.5wt% of the ammoniacal copper carbonate) and zinc salt additive zinc acetate (zinc acetate dosage is 0.1wt% of the ammoniacal copper carbonate) to the ammoniacal copper carbonate solution purified by adsorption in S6, and stir evenly.

[0074] S8, spray drying: treating the ammoniacal copper carbonate solution obtained in S7 by spray drying to obtain modified basic copper carbonate powder.

[0075] S9, selective etching: adding the modified basic copper carbonate to a 10% dilute acetic acid solution at a molar ratio of modified basic copper carbonate to dilute acetic acid = 20:1 for selective etching to remove some substances. After rapid stirring for 5 minutes, the solution was quickly centrifuged and washed with deionized water to obtain a porous basic copper carbonate powder.

[0076] S10, high-temperature calcination in air: placing the basic copper carbonate powder treated in S9 above in an air environment, heating it to 400°C at a rate of 3°C / min, keeping it at that temperature for 3 hours, and obtaining high-purity copper oxide powder with a honeycomb structure after cooling.

[0077] Example 3

[0078] A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, comprising the following steps:

[0079] S1, pretreatment: filter the circuit board acid etching waste liquid to remove insoluble impurities.

[0080] S2, evaporation and concentration: evaporating and concentrating the filtered acidic etching waste liquid to obtain a high-concentration copper chloride solution.

[0081] S3, preparing copper hydroxide by salt-alkali reaction: slowly adding an appropriate amount of sodium hydroxide solution to a high-concentration copper chloride solution to adjust the pH value to 9 to generate copper hydroxide precipitate; filtering and washing the copper hydroxide powder with deionized water to obtain a crude copper hydroxide product.

[0082] S4, dissolution + recrystallization: First, fully dissolve the crude copper hydroxide in dilute acetic acid with a mass concentration of 10%, slowly add an appropriate amount of sodium hydroxide solution to adjust the pH value to 9, regenerate copper hydroxide precipitate, let it stand, filter it, wash it repeatedly with clean water and dry it in turn to obtain the fine copper hydroxide.

[0083] S5, synthesis of ammonia copper carbonate: carbon dioxide gas is introduced into an ammonia solution to generate a carbonized ammonia solution, and the fine copper hydroxide prepared in S4 is added and stirred evenly until it is completely converted into ammonia copper carbonate.

[0084] S6, adsorption purification: Use activated carbon adsorption to purify the ammoniacal copper carbonate solution.

[0085] S7, grain control treatment: add surfactant polyvinyl alcohol (the amount of polyvinyl alcohol is 2wt% of the ammoniacal copper carbonate) and zinc salt additive zinc acetate (the amount of zinc acetate is 0.08wt% of the ammoniacal copper carbonate) to the ammoniacal copper carbonate solution after adsorption purification in S6, and stir evenly.

[0086] S8, spray drying: treating the ammoniacal copper carbonate solution obtained in S7 by spray drying to obtain modified basic copper carbonate powder.

[0087] S9, selective etching: adding the modified basic copper carbonate to a 10% dilute acetic acid solution at a molar ratio of modified basic copper carbonate to dilute acetic acid = 20:1 for selective etching to remove some substances. After rapid stirring for 5 minutes, the solution was quickly centrifuged and washed with deionized water to obtain a porous basic copper carbonate powder.

[0088] S10, high-temperature calcination in air: placing the basic copper carbonate powder treated in S9 above in an air environment, heating it to 500°C at a rate of 5°C / min, keeping it at that temperature for 2 hours, and cooling it to obtain a high-purity copper oxide powder with a honeycomb structure.

[0089] Comparative Example 1

[0090] This comparative example is based on Example 1, except that the surfactant (polyvinyl alcohol PVA) in step S7 is deleted, and the other steps and conditions are the same as those in Example 1.

[0091] Comparative Example 2

[0092] This comparative example is based on Example 1, except that the zinc salt additive (zinc acetate) in step S7 is deleted, and the other steps and conditions are the same as those in Example 1.

[0093] Comparative Example 3

[0094] This comparative example is based on Example 1, except that step S4, dissolution + recrystallization, is deleted, and the other steps and conditions are the same as those in Example 1.

[0095] Comparative Example 4

[0096] This comparative example is based on Example 1, except that step S6 of adsorption purification is deleted, and the other steps and conditions are the same as those in Example 1.

[0097] Comparative Example 5

[0098] This comparative example is based on Example 1, except that step S7 of the grain control process is deleted, and the other steps and conditions are the same as those of Example 1.

[0099] The products obtained in Examples 1 to 3 and Comparative Examples 1 to 5 were tested to determine the CuO purity and acid dissolution rate in the products. The results are shown in Table 1.

[0100] Acid dissolution rate is determined by measuring the time required for 10g of the test product to completely dissolve in 200mL of 10% dilute sulfuric acid. A longer time indicates a slower acid dissolution rate. The acid dissolution rate directly reflects the activity of the copper oxide: a faster acid dissolution rate indicates higher activity, while a slower acid dissolution rate indicates lower activity.

[0101] Table 1

[0102]

[0103] As can be seen from the data in Table 1, the copper oxide product obtained in the embodiment of the present invention has a purity of >99.5%, an extremely low impurity content, and a specific surface area of ​​>30m 2 / g. In addition, it has been tested that the copper oxide product prepared in the embodiment of the present invention has a fast acid dissolution rate, which meets the performance requirements of high-activity electronic copper oxide used in electronic industries such as PCB electroplating.

[0104] Comparing Comparative Examples 1 and 2 with Example 1, it can be seen that when the surfactant or zinc salt additive is deleted, the specific surface area of ​​the copper oxide product obtained is reduced and the acid dissolution rate is significantly slowed down, which makes it difficult to meet the demand for copper oxide in the electronics industry.

[0105] Comparing Comparative Examples 3 and 4 with Example 1, it can be seen that when the purification steps such as dissolution + recrystallization and adsorption purification are deleted, the purity of the obtained copper oxide product is significantly reduced, and the specific surface area is reduced. It is obvious that the activity performance of the product is lower than that of Example 1.

[0106] Comparing Comparative Example 5 with Example 1, it can be seen that when the grain control treatment step is deleted, the specific surface area of ​​the copper oxide product obtained is reduced and the acid dissolution rate is significantly slowed down. It is obvious that the performance of the product is lower than that of Example 1.

[0107] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid, characterized in that: The method comprises the following steps: Filter the acidic etching waste liquid of the circuit board to remove insoluble impurities; evaporate and concentrate the filtered acidic etching waste liquid to obtain a high-concentration copper chloride solution; slowly add an appropriate amount of sodium hydroxide solution to adjust the pH value to 8-9 to generate copper hydroxide precipitate; Filter and wash the copper hydroxide precipitate with deionized water to obtain crude copper hydroxide; First, dilute acetic acid is used to dissolve the crude copper hydroxide, and then sodium hydroxide is added to regenerate copper hydroxide precipitate to obtain fine copper hydroxide; Add the fine copper hydroxide to the carbonized ammonia solution and stir evenly until it is completely converted into ammoniacal copper carbonate solution; An ammoniacal copper carbonate solution is purified by an adsorbent; a preset amount of a surfactant and a zinc salt additive are added to the ammoniacal copper carbonate solution after adsorption, and the mixture is stirred to perform grain control treatment; the grain-controlled ammoniacal copper carbonate solution is treated by a spray drying method to obtain a modified basic copper carbonate with a high specific surface area; the surfactant is polyvinyl alcohol, and the zinc salt additive is zinc acetate; the amount of the surfactant is 1 wt% to 2 wt% of the ammoniacal copper carbonate; and the amount of the zinc salt additive is 0.05 wt% to 0.1 wt% of the ammoniacal copper carbonate; Selectively etching modified basic copper carbonate with dilute acid to obtain basic copper carbonate particles with a porous structure; specifically, adding a predetermined amount of modified basic copper carbonate to a dilute acetic acid solution, rapidly stirring for several minutes, and then quickly washing with deionized water by centrifugation to obtain porous basic copper carbonate powder; the molar ratio of modified basic copper carbonate to dilute acetic acid is 15-25:1; Basic copper carbonate particles are calcined at 300°C to 400°C to obtain copper oxide powder with a honeycomb structure.

2. A method for preparing electronic-grade copper oxide using circuit board acid etching waste liquid according to claim 1, characterized in that: The calcination is specifically as follows: placing the basic copper carbonate particles in an oxygen environment, heating the temperature to 300° C. to 400° C. at a rate of 1° C. / min to 5° C. / min, and keeping the temperature for 2 h to 4 h.

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