CN105603434A - Method for recycling PCB (printed circuit board) acidic etching solution under photocatalytic actions - Google Patents

Abstract

The invention discloses a method for recycling and utilizing photocatalyzed PCB acidic etching liquid. The steps are as follows: firstly, the etching waste liquid overflowing from the etching tank on the production line flows into the waste liquid collection tank; The collection tank flows into the oxidation reaction tank, and reacts under the conditions of adding photocatalyst and light; then, the oxidized waste liquid flows into the precipitation reaction tank with a cation exchange membrane, and a precipitant is added at the same time to form a mixed solution containing sediment ; Then the mixed solution is subjected to solid-liquid separation; then, a part of the filter residue is refined and purified, and sold in the form of copper oxalate; the other part is decomposed into activated copper oxide for sale. The filtrate flows into the water removal system after adding hydrochloric acid to remove excess water. Finally, the filtrate flows into the storage tank and becomes reused liquid for etching. Copper is reused during the process, and copper is properly extracted according to a balanced operation, and part of the copper is recycled. Only a certain amount of clean water is discharged, but no waste liquid is discharged, so that closed-circuit production can be achieved. The process has simple equipment, convenient control, broad prospects for promotion, and significant economic value and social and environmental benefits.

Description

A kind of photocatalytic PCB acidic etchant recycling method

technical field

The invention relates to the field of recycling and utilization of circuit board etching waste liquid, in particular to a method for recycling and utilizing photocatalytic PCB acidic etching liquid.

Background technique

The printed circuit board (PCB) industry is one of the most important components in the electronic industry, and plays a pivotal role in the electronic information industry. In recent years, with the rapid development of the electronic industry, the demand for PCB is increasing day by day. Acid etching is an important process in the manufacture of printed circuit boards (PCB). A large amount of high-copper etching waste liquid is produced during the production process. The etching waste liquid is a hazardous liquid waste and contains a large amount of polluting components such as copper and chlorine. If it is not treated strictly If it is directly discharged into the environment, it will not only cause waste and loss of resources, but also cause great harm to human beings and the natural environment. In addition, the copper ions and chloride ions in the etching waste liquid also have a high recovery value. In today's environment where resources are increasingly scarce and the environmental situation is increasingly severe, how to strictly and properly handle such a large amount of waste liquid is a very important issue. .

Acidic etching waste liquid is a kind of industrial wastewater with high copper content and high acidity produced in the process of etching copper foil. Acidic etching waste liquid seriously pollutes the environment, affects the survival of microorganisms in water, destroys the structure of soil aggregates, and affects the growth of crops. The existing recycling technologies for acid etching solutions have obvious defects. Due to the limitations of recycling costs, regeneration solution quality, control difficulty, process continuity, etc., as well as the lack of equipment investment capabilities of small and medium-sized enterprises, most of them use The acid etching factory does not use the recycling process, but transfers the waste liquid to the environmental protection company for treatment.

Although in accordance with the relevant regulations, the relevant departments require the centralized treatment of industrial wastewater, but the centralized treatment of PCB etching liquid wastewater inevitably has the following problems: First, the operating cost of sewage treatment is relatively high, because the wastewater comes from different production processes, Therefore, the quality of wastewater is very complex, and a single treatment process cannot solve all the problems. Therefore, to achieve standard discharge of wastewater in industrial parks that are difficult to treat, a combined process of physics-chemistry-biology is used, and chemical methods such as dosing chemicals are usually used. It will greatly increase the operating cost; second, the investment requirements for sewage treatment equipment are high. According to national requirements, manufacturers with an investment of more than 10 million in waste water treatment equipment are qualified to treat PCB waste water, and small and medium-sized enterprises are unable to complete this project. Investment; Third, the recycling rate of etching solution is low. At present, my country usually only recycles copper with relatively high value in waste liquid in the process of PCB etching solution wastewater treatment in China, while ignoring the treatment and reuse of polluting components such as chlorine, so there is no Can thoroughly achieve "full recovery as much as possible, with little or no emissions". Chloride ions are accelerators in the acid etching process. PCB companies need to add a large amount of additional chloride ions in the etching process. If they cannot be recycled, it will lead to a large waste of resources. At the same time, since it is difficult for sewage treatment plants to ensure that the effluent is stably discharged up to the standard for a long time, it will inevitably cause certain damage to the environment and increase the cost of production and environmental protection. Therefore, the development of a complete recycling technology for acidic etching waste has great economic and social environmental value.

At present, the main component of acidic etching waste liquid is H ₂ CuCl ₄ or CuCl ₂ , and the treatment technologies mainly include neutralization with sodium hydroxide solution, chemical precipitation, solvent extraction, ion exchange, flotation, adsorption, electrolysis law etc. However, it is difficult to achieve the best of both worlds in the treatment of PCB waste liquid by completely recovering copper and completely solving environmental problems. Relying on various PCB manufacturers to dispose of waste liquid by themselves often only focuses on recycling copper and fails to completely solve environmental protection problems. Therefore, the state stipulates that PCB waste liquid should be treated centrally. Due to the good economic benefits of recycling copper in the treatment of PCB waste, many businesses have applied for the establishment of environmental protection companies to deal with PCB waste. Some companies are small in scale and poor in equipment, but fail to meet the standard discharge of waste liquid. In this regard, governments in developed regions of the electronics industry have issued policies to strengthen management. For example, Jiangsu Province issued a document in October 2014 to improve copper recovery and waste water discharge. Standards, and stipulates that the PCB waste liquid treatment plant must have a certain scale, and the investment in equipment construction must be more than 10 million yuan before the plant is allowed to be built.

Although the document stipulates that the discharge standard of PCB waste liquid after treatment is that the copper content is less than 5ppm, due to the large amount of PCB waste water discharge in my country, tens of thousands of tons of copper are still lost every year.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art, and to provide a closed-circuit recycling system for acidic etching solution by using catalytic oxidation of air with only a small investment in equipment, and the system can realize the avoidance of etching solution wastewater emission. And the precipitation method is used to recycle the copper ions in the etching solution, which avoids the problem of centralized treatment of wastewater. Since the state stipulates that the copper ion content after wastewater treatment is 5ppm, although it is very small, there is still copper loss. Since the system of this project is a closed system, nearly 100% copper recovery can be realized after multiple cycles of etching solution. In this way, the loss of copper in the waste liquid obtained after centralized treatment can be avoided, and the economic and environmental benefits can be maximized. And under the normal operating conditions of the PCB production plant, only two devices of catalytic oxidation and water reverse osmosis are added. The former introduces oxygen in the air, and the latter leads out the water produced by the reaction, so that the normal PCB pickling operation can be realized, that is, a closed cycle Production. The realization of this process not only completely solves the existing PCB wastewater treatment problem (zero discharge), but also has no loss of copper. This technology requires less investment and has significant social and economic benefits. Adding two low-priced devices to each PCB production plant can solve the PCB waste liquid treatment problem that has plagued the PCB industry for many years.

The purpose of the present invention is achieved through the following technical solutions: by using the photocatalyst/non-metallic conductor compound as the photocatalyst, the air is passed into the system under light conditions to catalyze the oxidation of monovalent copper ions, and then add the precipitant to Copper is precipitated and recovered from the etching waste solution, the amount of precipitant is controlled, the acidity is retained, and it is re-used as an etchant after deployment, thereby realizing recycling. The copper oxalate extracted by precipitation can be purified and sold as refined copper oxalate to maximize economic benefits and further increase the added value of copper in waste liquid.

A method for recycling circuit board etching waste liquid and recovering copper, the specific steps are as follows:

1) The etching waste liquid flows out from the etching cylinder of the etching production line into the waste liquid collection tank. Since no oxidant is added, the etching waste liquid contains a large amount of Cu ⁺ ;

2) The etching waste liquid flows into the oxidation reaction tank from the waste liquid collection tank, the air is compressed into the system, and Cu ⁺ ions are oxidized under the action of porous photocatalyst and light;

3) The oxidized waste liquid flows into the sedimentation tank, and at the same time, a precipitant is added according to the tolerance of the solution, and a precipitation reaction occurs under stirring to form a mixed solution containing sediment;

4) The mixed liquid enters the three-legged centrifuge for solid-liquid separation. The solid filter residue is mainly copper precipitates. The filter residue is discharged and collected for processing, and the copper content in the filtrate will be reduced to about 80~160g/L;

5) According to the market demand value, a part of the filter residue is refined and purified and sold in the form of copper oxalate; the other part is decomposed into activated copper oxide for sale.

6) After the solid-liquid separation of the mixed liquid, the liquid is mainly the acid etching liquid body. During the oxygen oxidation process, it reacts with the hydrogen ions in the system to form water. Compared with the original etching liquid, the amount of water has increased. Moreover, during the reaction process, hydrochloric acid will inevitably volatilize, resulting in a decrease in acid equivalent. Therefore, it is necessary to supplement hydrochloric acid during the process of entering the etching working solution to ensure that the acid equivalent remains unchanged. This leads to an increase in water volume. Therefore, the filtrate flows into the reverse osmosis membrane water removal device to remove excess water.

7) The filtrate flows into the storage tank and becomes the reuse liquid for etching, and the reuse liquid pipe is connected to the original water supply pipe of the etching cylinder, and the reuse liquid is added to the etching cylinder through specific gravity control, and some additives are still Etching production is carried out according to the controlled addition of acid equivalent.

Further, the flow rate of the etching waste liquid flowing out from the etching cylinder of the etching production line into the waste liquid collection tank in step 1) is 2-6 m ³ /h.

Further, the flow rate of the air in step 2) is 10-20m ³ /h, and the intensity of light is 400-1000W.

Further, the porous photocatalyst in step 2) is a composite material of photocatalyst/non-metal conductor.

Further, the photocatalyst is titanium dioxide or carbon nitride; the non-metallic conductor is graphene, graphene oxide, reduced graphene oxide or silane, which is insoluble in strong acid.

Further, the oxidation process in step 2) takes 1-2 hours.

Further, the flow rate of the waste liquid in step 3) is 2~6m ³ /h.

Further, the precipitation agent described in step 3) is oxalic acid.

Further, the sedimentation tank described in step 3) is a cation exchange membrane sedimentation tank.

Further, the activated copper oxide described in step 5) is obtained by calcining and precipitating high-purity copper oxalate.

Compared with the prior art, the present invention has the following advantages and technical effects:

1) In the pickling process, the present invention uses air oxygen to replace the traditional chlorine-containing oxidant to avoid chlorine gas escaping during the production process.

2) The present invention can realize the reuse of copper in the process, properly extract copper according to the balanced operation, and recycle part of the copper.

3) In the whole process of the present invention, only a small amount of clean water is discharged, and no waste liquid is discharged, so that closed-circuit production can be achieved.

4) The process equipment of the present invention is simple, easy to control, has broad prospects for popularization, and has significant economic value and social and environmental benefits.

Description of drawings .

Fig. 1 is a process flow diagram of the present invention.

detailed description

Example 1

The preparation method of the composite material of photocatalyst/non-metallic conductor (reduced graphene oxide RGO/C ₃ N ₄ composite) is as follows:

(1) Preparation of carbon nitride (C ₃ N ₄ ): melamine was calcined and then ground to obtain carbon nitride (C ₃ N ₄ ) light yellow powder. The calcination temperature was 550° C. and the calcination time was 4 h.

(2) Preparation of GO:

(a) Dissolve 2.5g of graphite powder and 1.25g of sodium nitrate in 60ml of concentrated sulfuric acid with a mass concentration of 95%, and place it in an ice bath for 30min.

(b) Add 7.5g of potassium permanganate and stir at room temperature for 12 hours.

(c) Add 75ml of deionized water, stir at high temperature, the temperature is 90°C, and the stirring time is 24h.

(d) adding 25 ml of hydrogen peroxide solution with a mass concentration of 30% while stirring to obtain a mixture.

(e) The mixture was centrifuged, and the product was washed with dilute hydrochloric acid solution and deionized water and then dried to obtain GO. The drying temperature was 60°C. The mass concentration of dilute hydrochloric acid is 5%.

(3) Preparation of RGO/C ₃ N ₄ composite

(a) Add the GO prepared above into 60ml of deionized water, and sonicate for 1h.

(b) Add 0.5 g of C ₃ N ₄ powder, continue ultrasonication for 30 min, and then stir the mixture at room temperature for 12 h.

(c) 10ml of methanol was added to the mixture, and under stirring, irradiated with a 500W xenon lamp for 3h to prepare a reduced graphene oxide RGO/C ₃ N ₄ composite.

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

As shown in Figure 1, the technical scheme adopted in the recovery method of copper in the circuit board etching waste liquid of the present invention comprises the following steps:

1. The acidic etching solution flows out from the etching cylinder on the production line at a rate of 6m ³ /h. Since no oxidizing agent is added during this process, the etching solution contains 2g/L of monovalent copper ions. The acid etching solution to be regenerated flows into the waste liquid collection tank.

2. The acidic etching waste liquid flows from the waste liquid collection tank into the light oxidation reaction tank, and the air compressor with a pressure of 5kg is used to press the air from 1000 holes into the system at a rate of 20m ³ /h, and ensure that it is consistent with the Acidic etching waste liquid has a larger contact area. The reduced graphene oxide RGO/C ₃ N ₄ composite was added to the reaction cell in an amount of 1 mg/L, and irradiated with 1000W strong light for 1 hour. During this process, monovalent copper ions are oxidized by oxygen in the air to divalent copper ions, and oxygen reacts with hydrogen ions in the system to form water.

3. The regenerated acidic etching solution has etched copper into the solution, causing the amount of copper in the etching solution to increase compared with the initial concentration. At this time, the oxidized acidic etching solution flows into the cation exchange membrane sedimentation tank at 6m ³ /h, and oxalic acid is added in an amount of 3g/L in the sedimentation tank to obtain a mixed solution; since oxalic acid is solid at normal temperature, it can Dissolve in water to release hydrogen ions and oxalate ions, and the oxalate ions combine with copper ions to form copper oxalate precipitation. Since the amount of copper precipitated in this process is small compared to the original solution, the content of chloride ions in the copper oxalate precipitation is also very high. Small, negligible. The hydrogen ions released during the dissolution of oxalic acid enter the system to supplement the hydrogen ions consumed in the oxidation step and keep the acid equivalent of the acidic etching solution unchanged.

4. The mixed liquid enters the three-legged centrifuge for solid-liquid separation. The solid filter residue is mainly copper oxalate precipitation. The filter residue is discharged and collected for processing, and the copper content in the filtrate will be reduced to 120g/L, that is, in the original acid etching solution concentration of copper ions. The time for mixing and stirring the precipitant and the acidic etching waste solution is controlled within 15 minutes; too short a time will lead to insufficient precipitation and too fine crystallization, and too long treatment time is meaningless.

5. Since there is not much demand for copper oxalate in the market, according to the market demand, dissolve part of the filter residue in water, and then filter to obtain purified copper oxalate. At this time, the copper oxalate content exceeds 99.9%, and with this high It is sold in the form of pure copper oxalate; the other part is decomposed into activated copper oxide for sale. Activated copper oxide is obtained by calcination of high-purity copper oxalate precipitation. The calcination temperature is 400°C and the calcination time is 4h.

6. After the solid-liquid separation of the mixed liquid, the liquid is mainly the acid etching liquid body. Due to the oxygen oxidation process, it reacts with the hydrogen ions in the system to form water. Compared with the original etching liquid, the amount of water has increased. Moreover, during the reaction process, hydrochloric acid will inevitably volatilize, resulting in a decrease in acid equivalent. Therefore, it is necessary to supplement hydrochloric acid during the process of entering the etching working solution to ensure that the acid equivalent remains unchanged. This leads to an increase in water volume. Therefore, the filtrate flows into the reverse osmosis membrane water removal device to remove excess water.

7. The filtrate flows into the storage tank and becomes the reuse liquid for etching, and the reuse liquid pipeline is connected to the original water filling pipe of the etching cylinder, and the reuse liquid is added to the etching cylinder through specific gravity control, and some additives are still Etching production is carried out according to the controlled addition of acid equivalent.

Example 2

The preparation method of the composite material of photocatalyst/non-metallic conductor (gC ₃ N ₄ -TiO ₂ composite material) is as follows:

1. Preparation of carbon nitride (C ₃ N ₄ ): melamine is calcined and then ground to obtain carbon nitride (C ₃ N ₄ ) light yellow powder. The calcination temperature is 450° C. and the calcination time is 4 hours.

2. Weigh 1.0g C ₃ N ₄ powder and 1.0g TiO ₂ powder, mix and grind them evenly in an agate mortar, then put the mixture into a hydrothermal reaction kettle, seal it and react in a muffle furnace at 550°C for 4h (The heating rate is 2.0°C/min); the gC ₃ N ₄ -TiO ₂ composite material is obtained.

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

As shown in Figure 1, the technical scheme adopted in the recovery method of copper in the circuit board etching waste liquid of the present invention comprises the following steps:

1. The acidic etching solution flows out from the etching cylinder on the production line at a rate of 2m ³ /h. Since no oxidizing agent is added during this process, the etching solution contains 2g/L of monovalent copper ions. The acid etching solution to be regenerated flows into the waste liquid collection tank.

2. The acidic etching waste liquid flows from the waste liquid collection tank into the light oxidation reaction tank, and the air compressor with a pressure of 5kg is used to press the air from 1000 holes at a total rate of 10m ³ /h into the system to ensure the same Acidic etching waste liquid has a larger contact area. The gC ₃ N ₄ -TiO ₂ composite material was added into the reaction cell in an amount of 2 mg/L, and irradiated with 400W strong light for 2 hours. During this process, monovalent copper ions are oxidized by oxygen in the air to divalent copper ions, and oxygen reacts with hydrogen ions in the system to form water.

3. The regenerated acidic etching solution has etched copper into the solution, causing the amount of copper in the etching solution to increase compared with the initial concentration. At this time, the oxidized acidic etching solution flows into the cation exchange membrane sedimentation tank at 2m ³ /h, and oxalic acid is added in an amount of 3g/L in the sedimentation tank to obtain a mixed solution; since oxalic acid is solid at normal temperature, it can Dissolve in water to release hydrogen ions and oxalate ions, and oxalate ions combine with copper ions to form copper oxalate precipitates. Since the amount of copper precipitated in this process is small compared to the original solution, the content of chloride ions in copper oxalate precipitates is also very high. Small, negligible. The hydrogen ions released during the dissolution of oxalic acid enter the system to supplement the hydrogen ions consumed in the oxidation step and keep the acid equivalent of the acidic etching solution unchanged.

4. The mixed liquid enters the three-legged centrifuge for solid-liquid separation. The solid filter residue is mainly copper oxalate precipitation. The filter residue is discharged and collected for processing, and the copper content in the filtrate will be reduced to 120g/L, that is, in the original acid etching solution concentration of copper ions. The time for mixing and stirring the precipitant and the acidic etching waste solution is controlled within 60 minutes; too short a time will lead to insufficient precipitation and too fine crystallization, and too long treatment time is meaningless.

5. Since there is not much demand for copper oxalate in the market, according to the market demand, dissolve part of the filter residue in water, and then filter to obtain purified copper oxalate. At this time, the copper oxalate content exceeds 99.9%, and with this high It is sold in the form of pure copper oxalate; the other part is decomposed into activated copper oxide for sale. Activated copper oxide is obtained by calcination of high-purity copper oxalate precipitation. The calcination temperature is 500 ° C and the calcination time is 3 hours.

6. After the solid-liquid separation of the mixed liquid, the liquid is mainly the acid etching liquid body. Due to the oxygen oxidation process, it reacts with the hydrogen ions in the system to form water. Compared with the original etching liquid, the amount of water has increased. Moreover, during the reaction process, hydrochloric acid will inevitably volatilize, resulting in a decrease in acid equivalent. Therefore, it is necessary to supplement hydrochloric acid during the process of entering the etching working solution to ensure that the acid equivalent remains unchanged. This leads to an increase in water volume. Therefore, the filtrate flows into the reverse osmosis membrane water removal device to remove excess water.

7. The filtrate flows into the storage tank and becomes the reuse liquid for etching, and the reuse liquid pipeline is connected to the original water filling pipe of the etching cylinder, and the reuse liquid is added to the etching cylinder through specific gravity control, and some additives are still Etching production is carried out according to the controlled addition of acid equivalent.

Example 3

The preparation method of the composite material of photocatalyst/non-metallic conductor (mpg-C ₃ N ₄ /RGO composite material) is as follows:

(1) Preparation of carbon nitride (C ₃ N ₄ ): melamine was calcined and then ground to obtain carbon nitride (C ₃ N ₄ ) light yellow powder. The calcination temperature was 450° C. and the calcination time was 4 h.

(2) Preparation of mpg-C ₃ N ₄ : 12 g of C ₃ N ₄ powder was dissolved in 30 g of an aqueous silica sol solution with a mass concentration of 40%, and the mixture was evaporated to dryness. The obtained white powder was put into a combustion boat, and then sent into a tube furnace. Under the protection of 300mL/min nitrogen, the temperature was raised to 550°C at 2.3°C/min, maintained at this temperature for 4h, and cooled to room temperature naturally. A brownish-yellow powder was obtained, which was treated with 4mol/L ammonium bifluoride solution for 48h to remove the template agent. After the reaction, the solution was centrifuged to discard the supernatant, washed with deionized water and absolute ethanol to remove possible ion residues, and dried overnight in a vacuum oven at 60°C to obtain a light yellow product, which was ground for later use and marked is mpg-C ₃ N ₄ .

(3) Preparation of GO:

(a) Dissolve 2.5g of graphite powder and 1.25g of sodium nitrate in 60ml of concentrated sulfuric acid with a mass concentration of 95%, and place it in an ice bath for 30min.

(b) Add 7.5g of potassium permanganate and stir at room temperature for 12 hours.

(c) Add 75ml of deionized water, stir at high temperature, the temperature is 90°C, and the stirring time is 24h.

(d) adding 25 ml of hydrogen peroxide solution with a mass concentration of 30% while stirring to obtain a mixture.

(e) The mixture was centrifuged, and the product was washed with dilute hydrochloric acid solution and deionized water and then dried to obtain GO. The drying temperature was 60°C. The mass concentration of dilute hydrochloric acid is 5%.

(4) Preparation of mpg-C ₃ N ₄ /RGO composite material:

(a) Add the GO prepared above into 60ml of deionized water, and sonicate for 1h.

(b) Add 0.5 gmpg-C ₃ N ₄ , continue ultrasonication for 30 min, and then stir the mixture at room temperature for 12 h.

(c) 10ml of methanol was added to the mixed liquid, and under stirring state, 500W xenon light was irradiated for 3h to prepare the mpg-C ₃ N ₄ /RGO composite material.

Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

As shown in Figure 1, the technical scheme adopted in the recovery method of copper in the circuit board etching waste liquid of the present invention comprises the following steps:

1. The acidic etching solution flows out from the etching cylinder on the production line at a rate of 2m ³ /h. Since no oxidizing agent is added during this process, the etching solution contains 2g/L of monovalent copper ions. The acid etching solution to be regenerated flows into the waste liquid collection tank.

2. The acidic etching waste liquid flows from the waste liquid collection tank into the photo-oxidation reaction tank, and an air compressor with a pressure of 5kg is used to press air into the system from 1000 holes at a rate of 10m ³ /h to ensure that it is compatible with acid Etching waste liquid has a larger contact area. The mpg-C ₃ N ₄ /RGO composite material was added into the reaction cell at an amount of 2 mg/L, and irradiated with sunlight for 3 hours. During this process, monovalent copper ions are oxidized by oxygen in the air to divalent copper ions, and oxygen reacts with hydrogen ions in the system to form water.

3. The regenerated acidic etching solution has etched copper into the solution, causing the amount of copper in the etching solution to increase compared with the initial concentration. At this time, the oxidized acidic etching solution flows into the cation exchange membrane sedimentation tank at 2m ³ /h, and oxalic acid is added in an amount of 3g/L in the sedimentation tank to obtain a mixed solution; since oxalic acid is solid at normal temperature, it can Dissolve in water to release hydrogen ions and oxalate ions, and oxalate ions combine with copper ions to form copper oxalate precipitates. Since the amount of copper precipitated in this process is small compared to the original solution, the content of chloride ions in copper oxalate precipitates is also very high. Small, negligible. The hydrogen ions released during the dissolution of oxalic acid enter the system to supplement the hydrogen ions consumed in the oxidation step and keep the acid equivalent of the acidic etching solution unchanged.

4. The mixed liquid enters the three-legged centrifuge for solid-liquid separation. The solid filter residue is mainly copper oxalate precipitation. The filter residue is discharged and collected for processing, and the copper content in the filtrate will be reduced to 120g/L, that is, in the original acid etching solution concentration of copper ions. The time for mixing and stirring the precipitant and the acidic etching waste solution is controlled within 60 minutes; too short a time will lead to insufficient precipitation and too fine crystallization, and too long treatment time is meaningless.

5. Since there is not much demand for copper oxalate in the market, according to the market demand, dissolve part of the filter residue in water, and then filter to obtain purified copper oxalate. At this time, the copper oxalate content exceeds 99.9%, and with this high It is sold in the form of pure copper oxalate; the other part is decomposed into activated copper oxide for sale. Activated copper oxide is obtained by calcination of high-purity copper oxalate precipitation. The calcination temperature is 600°C and the calcination time is 2h.

6. After the solid-liquid separation of the mixed liquid, the liquid is mainly the acid etching liquid body. Due to the oxygen oxidation process, it reacts with the hydrogen ions in the system to form water. Compared with the original etching liquid, the amount of water has increased. Moreover, during the reaction process, hydrochloric acid will inevitably volatilize, resulting in a decrease in acid equivalent. Therefore, it is necessary to supplement hydrochloric acid during the process of entering the etching working solution to ensure that the acid equivalent remains unchanged. This leads to an increase in water volume. Therefore, the filtrate flows into the reverse osmosis membrane water removal device to remove excess water.

7. The filtrate flows into the storage tank and becomes the reuse liquid for etching, and the reuse liquid pipeline is connected to the original water filling pipe of the etching cylinder, and the reuse liquid is added to the etching cylinder through specific gravity control, and some additives are still Etching production is carried out according to the controlled addition of acid equivalent.

The above descriptions are only preferred implementations of the present invention, so all equivalent changes or modifications made according to the structures, features and principles described in the scope of the present invention are included in the scope of the present invention.

Claims (10)

1. a method for photocatalysis PCB acidic etching liquid recycling, is characterized in that, concrete steps are as follows:

1) etching waste liquor overflowing in etching cylinder from production line flow in waste collection tank;

2) etching waste liquor flow into oxidation reaction pond from waste collection tank, the compressed system that enters of air, Cu⁺Ion is oxidized under the effect of porous photocatalytic agent and illumination;

3) oxidized waste liquid flows in sedimentation basin, adds precipitating reagent by the amount of the tolerance of solution simultaneously, under stirring action, precipitation reaction occurs, and forms and contains sedimentary mixed liquor;

4) mixed liquor enters and in tripod pendulum type batch centrifugal, carries out Separation of Solid and Liquid, and filter residue is drawn off and collects pendingly, and copper content in filtrate will be reduced to 80 ~ 160g/L;

5) according to market demand value, purify refining a part of filter residue, sell with the form of cupric oxalate; Another part resolves into active oxidation copper to be sold;

6) after mixed liquor Separation of Solid and Liquid, filtrate after supplementing hydrochloric acid is flowed in reverse osmosis membrane de-watering apparatus, too much water is removed, the amount of described too much water is step 2) in dioxygen oxidation process, the water adding while reacting the amount of the water that generates and supplementary hydrochloric acid with the hydrogen ion in system;

7) filtrate of flowing out in de-watering apparatus is flow in holding vessel, become for etched reuse liquid, and reuse liquid pipeline is linked on the pipeline that etching cylinder added water originally, add this reuse liquid in etching cylinder by proportion management and control, some additives still add and carry out etching production according to acid equivalent management and control.

2. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that, from the etching cylinder of etching production line, to flow out the flow velocity that enters into waste collection tank be 2 ~ 6m to etching waste liquor described in step 1)³/h。

3. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that step 2) flow velocity of described air is 10 ~ 20m³/ h, the intensity of illumination is 400 ~ 1000W.

4. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that step 2) described porous photocatalytic agent is the composite of photochemical catalyst/non-metal kind conductor.

5. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 4 and copper reclaim, is characterized in that, described photochemical catalyst is titanium dioxide or carbonitride; Described non-metal kind conductor is conductor Graphene, graphene oxide, redox graphene or the silane that is insoluble to strong acid.

6. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that step 2) the process spent time of described oxidation is 1 ~ 2h.

7. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that, the flow velocity of waste liquid is 2 ~ 6m described in step 3)³/h。

8. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that, the precipitating reagent described in step 3) is oxalic acid; Described mixing time is 15-90min.

9. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that, the sedimentation basin described in step 3) is cation-exchange membrane sedimentation basin.

10. the method that a kind of circuit board etching waste liquor circulating and recovering according to claim 1 and copper reclaim, is characterized in that, the active oxidation copper described in step 5) is by calcining cupric oxalate precipitation and getting.