Automatic pH control method in cyclic regeneration reaction process of etching waste liquid

Abstract

The invention discloses an automatic pH control method in a cyclic regeneration reaction process of etching waste liquid. The automatic pH control method comprises two steps of preparing a reaction buffer solution and preparing basic copper chloride, and in the basic copper chloride preparation step, the pH value of a reaction system can be read in real time through a pH sensor and is fed back to a controller; the controller controls the peristaltic pump to adjust the adding volume of the acid etching waste liquid and the alkaline etching waste liquid in real time according to the pH value of the system to prepare the granular basic copper chloride, the pH value of the whole technological process can be strictly controlled to ensure the quality of the basic copper chloride, manual pH detection is not needed, the production efficiency is high, and the production cost is low. The feeding amount is accurately controlled, cost increase caused by excessive addition of materials is avoided, in addition, the response speed is also improved, and once the pH value of a reaction system abnormally fluctuates, the system can quickly make adjustment.

Description

Technical Field

[0001] The invention relates to the technical field of recycling and regenerating etching waste liquid, in particular to a method for automatically controlling pH value in a recycling and regenerating reaction process of etching waste liquid. Background Art

[0002] Circuit board factories often produce a large amount of acidic etching wastewater and alkaline etching wastewater during etching. These wastewaters contain a large amount of metal ions (such as copper, nickel, and lead), among which the concentration of copper ions is relatively high. In order to recover copper, the acidic and alkaline etching waste liquid is usually made into basic copper chloride before subsequent treatment. Basic copper chloride is sensitive to reaction conditions. The color and particle size of basic copper chloride generated under different reaction temperatures, pH values ​​and other conditions will vary greatly. Usually, granular basic copper chloride is better than slurry basic copper chloride for external sales or subsequent processing. The production of granular basic copper chloride requires strict control of the pH value of the entire process to ensure its quality. However, the production of granular basic copper chloride currently relies mainly on manual pH detection. In order to ensure safety during detection, the production line needs to be suspended, resulting in reduced production efficiency. In addition, manual detection is easily affected by subjective factors and there are operational errors, resulting in inaccurate detection results. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a method for automatically controlling pH in a recycling reaction process of an etching waste liquid, comprising the following steps:

[0004] Prepare reaction buffer: add ammonium chloride and water into a container according to a solid-liquid ratio of 1 g: (7.5-20) ml, heat to 55-65° C. and stir at 350-400 r / min to obtain reaction buffer;

[0005] Preparation of basic copper chloride:

[0006] The temperature of the container is maintained at 55-65°C and stirring is continued at 350-400 r / min. At the same time, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is used to read the pH value of the reaction system in real time and feed it back to the controller. The controller controls the peristaltic pump to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid in real time according to the pH value of the system. The pH sensor, the controller and the peristaltic pump are electrically connected, wherein the pH sensor is detachably connected in the container. In addition, one end of the first hose is connected to the Insert the first peristaltic pump into the pump head inlet, and the other end is inserted into the acidic etching waste liquid. One end of the second hose is pulled out through the pump head outlet of the first peristaltic pump, and the other end is placed in the container; one end of the third hose is inserted into the pump head inlet of the second peristaltic pump, and the other end is inserted into the alkaline etching waste liquid. One end of the fourth hose is pulled out through the pump head outlet of the first peristaltic pump, and the other end is placed in the container. The first hose, the second hose, the third hose and the fourth hose are all made of polytetrafluoroethylene. The whole process of preparing basic copper chloride is divided into three stages including the early stage, the middle stage and the late stage;

[0007] In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a through a peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid accounts for 1 / 40 to 1 / 20 of the water volume, and the pH value of the reaction system is read by a pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, ensuring that the pH value of the reaction system is always maintained in the range of 4.3 to 4.7;

[0008] In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3.5 to 5.4 times the volume of water, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b at the same time. When the pH value of the reaction system is less than 4.5, the speed of adding the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continuously added at a speed b. When the pH value of the reaction system is greater than 5, the speed of adding the alkaline etching waste liquid is reduced and the acidic etching waste liquid is continuously added at a speed b.

[0009] In the later stage, according to the pH value of the reaction system, the acidic etching waste liquid and the alkaline etching waste liquid are continued to be added to the reaction buffer at a speed c, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid accounts for 1 / 40 to 1 / 20 of the water volume, until the pH value is stabilized in the range of 4.3 to 4.7 and is maintained for 15 to 30 minutes without any change, the peristaltic pump is stopped to obtain a basic copper chloride slurry, and the speed a=c≤b.

[0010] Preferably, during the preparation of the reaction buffer, the heating temperature is 60°C.

[0011] Preferably, during the preparation of the reaction buffer, the stirring speed is 375 r / min.

[0012] Preferably, the speed a is 1 ml / s.

[0013] Preferably, the speed b is 1 to 5 ml / s.

[0014] Preferably, the speed c is 1 ml / s.

[0015] Preferably, speed a is 2 ml / s, speed b is 4 ml / s, and speed c is 1 ml / s.

[0016] Preferably, in the middle stage of the reaction of the alkaline chlorination process, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 4 times the volume of water.

[0017] Preferably, in the middle stage of the reaction of the alkaline chlorination process, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 5 times the volume of water.

[0018] Preferably, in the middle stage of the preparation of basic cupric chloride reaction, once the pH value is less than 3.5, the controller immediately controls the peristaltic pump to stop adding acidic etching waste liquid, and once the pH value is greater than 6, the controller immediately controls the peristaltic pump to stop adding alkaline etching waste liquid.

[0019] The beneficial effect is that the present application uses a pH sensor to read the pH value of the reaction system in real time and feeds it back to the controller, and the controller controls the peristaltic pump in real time according to the pH value of the system to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid to prepare granular basic copper chloride, which can strictly control the pH value of the entire process to ensure the quality of the basic copper chloride, without relying on manual pH detection, with high production efficiency, and can achieve precise control of the amount of feed added to avoid excessive addition of materials leading to increased costs. In addition, the response speed is also improved. Once the pH value of the reaction system fluctuates abnormally, the system can quickly make adjustments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0023] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0024] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0025] Source of raw materials:

[0026] Acidic etching waste liquid and alkaline etching waste liquid were purchased from Jiangmen Sunda Circuit Technology Co., Ltd.

[0027] Equipment source:

[0028] Peristaltic pump, model KPHM100-HBB10, purchased from Hefei Wuya Technology Co., Ltd.;

[0029] pH sensor, model Ruixin Hengchuang RXHC, purchased from Shenzhen Ruixin Hengchuang Electronics Co., Ltd.;

[0030] The first hose, the second hose, the third hose and the fourth hose were all purchased from Shenzhen Nuorui Hose Co., Ltd.;

[0031] The remaining reagents and equipment are commercially available.

[0032] Example 1

[0033] A method for automatically controlling pH in a recycling reaction process of etching waste liquid, comprising the following steps:

[0034] Prepare reaction buffer: add 50 g ammonium chloride and 1000 ml water into a container, heat to 55 °C and stir at 350 r / min to obtain reaction buffer;

[0035] Preparation of basic copper chloride:

[0036] The temperature of the container is maintained at 55°C and stirring is continued at 350 r / min. At the same time, acidic etching waste liquid and alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is required to read the pH value of the reaction system in real time and feed it back to the controller. The controller controls the peristaltic pump in real time to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid according to the pH value of the system. The whole process of preparing basic copper chloride is divided into three stages including the early stage, the middle stage and the late stage;

[0037] In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a through a peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 50-100 ml, and the pH value of the reaction system is read by a pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, ensuring that the pH value of the reaction system is always maintained in the range of 4.3-4.7;

[0038] In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3500-4000 ml, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b. When the pH value of the reaction system is less than 4.5, the speed of adding the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continued to be added at a speed b. When the pH value of the reaction system is greater than 5, the speed of adding the alkaline etching waste liquid is reduced. The pH value is changed not immediately after the addition, so when the pH sensor reads that the pH value of the reaction system is less than 4.5, even if the acidic etching waste liquid addition speed is reduced and the alkaline etching waste liquid is continued to be added at speed b, the reaction system will still proceed in the direction of pH reduction. Therefore, once the pH value is less than 3.5, the controller needs to immediately control the peristaltic pump to stop adding the acidic etching waste liquid; similarly, once the pH value is greater than 6, the controller needs to immediately control the peristaltic pump to stop adding the alkaline etching waste liquid.

[0039] At a later stage, according to the pH value of the reaction system, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed of c, and the total volume of the acidic etching waste liquid and the alkaline etching waste liquid added is 50-100 ml, until the pH value is stabilized in the range of 4.3-4.7 and maintained for 15-30 minutes without any change, the peristaltic pump is stopped, and the basic copper chloride slurry is obtained, and the speed a=c≤b, wherein the speed a is 1 ml / s. The speed b is 1-5 ml / s. The speed c is 1 ml / s.

[0040] Example 2

[0041] A method for automatically controlling pH in a recycling reaction process of etching waste liquid, comprising the following steps:

[0042] Prepare reaction buffer: add 100 g ammonium chloride and 750 ml water into a container, heat to 60 °C and stir at 375 r / min to obtain reaction buffer;

[0043] Preparation of basic copper chloride:

[0044] The temperature of the container is maintained at 60°C and stirring is continued at 375 r / min. At the same time, acidic etching waste liquid and alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is required to read the pH value of the reaction system in real time and feed it back to the controller. The controller controls the peristaltic pump in real time to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid according to the pH value of the system. The whole process of preparing basic copper chloride is divided into three stages including the early stage, the middle stage and the late stage;

[0045] In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a through a peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 50-100 ml, and the pH value of the reaction system is read by a pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, ensuring that the pH value of the reaction system is always maintained in the range of 4.3-4.7;

[0046] In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3750-4050 ml, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b. When the pH value of the reaction system is less than 4.5, the speed of adding the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continued to be added at a speed b. When the pH value of the reaction system is greater than 5, the speed of adding the alkaline etching waste liquid is reduced. The pH value is changed not immediately after the addition, so when the pH sensor reads that the pH value of the reaction system is less than 4.5, even if the acidic etching waste liquid addition speed is reduced and the alkaline etching waste liquid is continued to be added at speed b, the reaction system will still proceed in the direction of pH reduction. Therefore, once the pH value is less than 3.5, the controller needs to immediately control the peristaltic pump to stop adding the acidic etching waste liquid; similarly, once the pH value is greater than 6, the controller needs to immediately control the peristaltic pump to stop adding the alkaline etching waste liquid.

[0047] At a later stage, according to the pH value of the reaction system, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed of c, and the total volume of the acidic etching waste liquid and the alkaline etching waste liquid added is 50-100 ml, until the pH value is stabilized in the range of 4.3-4.7 and maintained for 15-30 minutes without any change, the peristaltic pump is stopped, and the basic copper chloride slurry is obtained, and the speed a=c≤b, wherein the speed a is 2 ml / s. The speed b is 4 ml / s. The speed c is 1 ml / s.

[0048] Example 3

[0049] A method for automatically controlling pH in a recycling reaction process of etching waste liquid, comprising the following steps:

[0050] Prepare reaction buffer: add 50 g ammonium chloride and 750 ml water into a container, heat to 65 °C and stir at 400 r / min to obtain reaction buffer;

[0051] Preparation of basic copper chloride:

[0052] The temperature of the container is maintained at 65°C and stirring is continued at 400 r / min. At the same time, acidic etching waste liquid and alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is required to read the pH value of the reaction system in real time and feed it back to the controller. The controller controls the peristaltic pump in real time according to the pH value of the system to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid. The whole process of preparing basic copper chloride is divided into three stages including the early stage, the middle stage and the late stage;

[0053] In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a through a peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 50-100 ml, and the pH value of the reaction system is read by a pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, ensuring that the pH value of the reaction system is always maintained in the range of 4.3-4.7;

[0054] In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3750-4050 ml, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b. When the pH value of the reaction system is less than 4.5, the speed of adding the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continued to be added at a speed b. When the pH value of the reaction system is greater than 5, the speed of adding the alkaline etching waste liquid is reduced. The pH value is changed not immediately after the addition, so when the pH sensor reads that the pH value of the reaction system is less than 4.5, even if the acidic etching waste liquid addition speed is reduced and the alkaline etching waste liquid is continued to be added at speed b, the reaction system will still proceed in the direction of pH reduction. Therefore, once the pH value is less than 3.5, the controller needs to immediately control the peristaltic pump to stop adding the acidic etching waste liquid; similarly, once the pH value is greater than 6, the controller needs to immediately control the peristaltic pump to stop adding the alkaline etching waste liquid.

[0055] At a later stage, according to the pH value of the reaction system, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed of c, and the total volume of the acidic etching waste liquid and the alkaline etching waste liquid added is 50-100 ml, until the pH value is stabilized in the range of 4.3-4.7 and maintained for 15-30 minutes without any change, the peristaltic pump is stopped, and the basic copper chloride slurry is obtained, and the speed a=c≤b, wherein the speed a is 1 ml / s. The speed b is 1 ml / s. The speed c is 1 ml / s.

[0056] Example 4

[0057] A method for automatically controlling pH in a recycling reaction process of etching waste liquid, comprising the following steps:

[0058] Prepare reaction buffer: add 100 g ammonium chloride and 1000 ml water into a container, heat to 65 °C and stir at 400 r / min to obtain reaction buffer;

[0059] Preparation of basic copper chloride:

[0060] The temperature of the container is maintained at 65°C and stirring is continued at 400 r / min. At the same time, acidic etching waste liquid and alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is required to read the pH value of the reaction system in real time and feed it back to the controller. The controller controls the peristaltic pump in real time according to the pH value of the system to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid. The whole process of preparing basic copper chloride is divided into three stages including the early stage, the middle stage and the late stage;

[0061] In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a through a peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 50-100 ml, and the pH value of the reaction system is read by a pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, ensuring that the pH value of the reaction system is always maintained in the range of 4.3-4.7;

[0062] In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3500-4000 ml, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b. When the pH value of the reaction system is less than 4.5, the speed of adding the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continued to be added at a speed b. When the pH value of the reaction system is greater than 5, the speed of adding the alkaline etching waste liquid is reduced. The pH value is changed not immediately after the addition, so when the pH sensor reads that the pH value of the reaction system is less than 4.5, even if the acidic etching waste liquid addition speed is reduced and the alkaline etching waste liquid is continued to be added at speed b, the reaction system will still proceed in the direction of pH reduction. Therefore, once the pH value is less than 3.5, the controller needs to immediately control the peristaltic pump to stop adding the acidic etching waste liquid; similarly, once the pH value is greater than 6, the controller needs to immediately control the peristaltic pump to stop adding the alkaline etching waste liquid.

[0063] Later, according to the pH value of the reaction system, the acidic etching waste liquid and the alkaline etching waste liquid are continued to be added to the reaction buffer at a speed c, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 50-100 ml, until the pH value is stabilized in the range of 4.3-4.7 and maintained for 15-30 minutes without any change, the peristaltic pump is stopped to obtain a basic copper chloride slurry, the speed a=c≤b, wherein the speed a is 1 ml / s, the speed b is 3 ml / s, and the speed c is 2 ml / s.

[0064] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for automatically controlling pH in a recycling reaction process of etching waste liquid, characterized in that: The following steps are involved: Prepare reaction buffer: add ammonium chloride and water into a container according to a solid-liquid ratio of 1 g: (7.5-20) ml, heat to 55-65° C. and stir at 350-400 r / min to obtain reaction buffer; Preparation of basic copper chloride: The temperature of the container is maintained at 55-65° C. and stirring is continued at 350-400 r / min. At the same time, acidic etching waste liquid and alkaline etching waste liquid are added to the reaction buffer by a peristaltic pump. During this process, a pH sensor is used to read the pH value of the reaction system in real time and feed it back to a controller. The controller controls the peristaltic pump in real time according to the pH value of the system to adjust the added volume of the acidic etching waste liquid and the alkaline etching waste liquid. The pH sensor, the controller and the peristaltic pump are electrically connected. The whole process of preparing the basic copper chloride is divided into three stages including an early stage, a middle stage and a late stage. In the early stage, the acidic etching waste liquid and the alkaline etching waste liquid are added to the reaction buffer at a speed a by the peristaltic pump, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid accounts for 1 / 40 to 1 / 20 of the volume of the water, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is greater than 4.7, the controller controls the peristaltic pump to stop adding the alkaline etching waste liquid, and when the pH value of the reaction system is greater than 4.3, the controller controls the peristaltic pump to stop adding the acidic etching waste liquid, so as to ensure that the pH value of the reaction system is always maintained in the range of 4.3 to 4.7; In the middle stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added at a speed b, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 3.5 to 5.4 times the volume of the water, and the pH value of the reaction system is read by the pH sensor. When the pH value of the reaction system is between 4.5 and 5, the controller controls the peristaltic pump to continue to add the acidic etching waste liquid and the alkaline etching waste liquid at a speed b at the same time. When the pH value of the reaction system is less than 4.5, the adding speed of the acidic etching waste liquid is reduced and the alkaline etching waste liquid is continuously added at a speed b. When the pH value of the reaction system is greater than 5, the adding speed of the alkaline etching waste liquid is reduced and the acidic etching waste liquid is continuously added at a speed b. At a later stage, the acidic etching waste liquid and the alkaline etching waste liquid are continuously added to the reaction buffer at a speed c according to the pH value of the reaction system, and the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid accounts for 1 / 40 to 1 / 20 of the volume of the water, until the pH value is stabilized in the range of 4.3 to 4.7 and is maintained for 15 to 30 minutes without any change, the peristaltic pump is stopped to obtain a basic copper chloride slurry, and the speed a=c≤b.

2. The method for automatically controlling pH in a recycling reaction process of etching waste liquid according to claim 1, characterized in that: During the preparation of the reaction buffer, the heating temperature was 60°C.

3. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: During the preparation of the reaction buffer, the stirring speed was 375 r / min.

4. The method for automatically controlling pH in a recycling reaction process of etching waste liquid according to claim 1, characterized in that: The speed a is 1 ml / s.

5. The method for automatically controlling pH in a recycling reaction process of etching waste liquid according to claim 1, characterized in that: The speed b is 1-5 ml / s.

6. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: The speed c is 1 ml / s.

7. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: The speed a is 2 ml / s, the speed b is 4 ml / s, and the speed c is 1 ml / s.

8. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: In the middle stage of the reaction of the alkaline chlorination process, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 4 times the volume of the water.

9. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: In the middle stage of the reaction of the alkaline chlorination process, the total added volume of the acidic etching waste liquid and the alkaline etching waste liquid is 5 times the volume of the water.

10. The method for automatically controlling pH value in the recycling reaction process of etching waste liquid according to claim 1, characterized in that: In the middle stage of the preparation of the basic cupric chloride reaction, once the pH value is less than 3.5, the controller immediately controls the peristaltic pump to stop adding the acidic etching waste liquid; once the pH value is greater than 6, the controller immediately controls the peristaltic pump to stop adding the alkaline etching waste liquid.

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