Pre-oxidation treatment device for spent electroless nickel plating bath and process control method

Abstract

The present application relates to the field of the treatment of waste liquids, and specifically discloses a pre-oxidation treatment device for a spent electroless nickel plating bath and a process control method. The pre-oxidation treatment device comprises: a reaction kettle; a waste liquid storage tank, a temporary storage tank, an acid liquid storage tank, and an oxygen storage tank, which are arranged around the reaction kettle and connected by means of pipelines; and a valve body assembly. A first pump body and a first Venturi mixer are arranged in a first circulation loop, and the acid liquid storage tank and the oxygen storage tank are both connected to a low-pressure port pipeline of the first Venturi mixer; and a second pump body and a second Venturi mixer are arranged in a second circulation loop, and the top of the reaction kettle is connected to a low-pressure port pipeline of the second Venturi mixer. The device and the control method can realize automatic acid supplementing and automatic oxygen supplementing during an oxidation reaction, so that the oxidation reaction is more thorough; in addition, the arrangement of the valve body assembly and the pump body assembly facilitates accurate control, and realizes a high degree of automation.

Description

Pre-oxidation treatment equipment and process control method for chemical nickel plating waste liquid Technical Field

[0001] The present application relates to the field of waste liquid treatment, and more specifically, to a pre-oxidation treatment device and process control method for chemical nickel plating waste liquid. Background Art

[0002] There are three main types of reducing agents used in chemical nickel plating: (1) hypophosphite; (2) sodium borohydride-type boron-containing reducing agents; and (3) hydrazine. Among them, acidic chemical nickel plating using sodium hypophosphite as the reducing agent is the most widely used. During the nickel plating process, as the deposition reaction continues, sodium hypophosphite is continuously consumed and phosphite is continuously generated. At present, industrial chemical nickel plating is carried out in an acidic system with sodium hypophosphite as the reducing agent. In order to ensure the stability, service life and coating quality of the plating solution, complexing agents, stabilizers, accelerators, pH buffers and nickel plating brighteners need to be added to the plating solution. These substances are all organic substances, such as citric acid, tartaric acid, malic acid, glycolic acid, succinic acid, succinic acid, acetic acid, etc. The amount of complexing agents added to the chemical plating solution is relatively large. The presence of these substances has a strong complexing property with nickel and easily forms a stable complex with nickel, which brings difficulties to the treatment of the plating solution.

[0003] For example, in the electroless nickel plating carried out in an acidic system with sodium hypophosphite solution as a reducing agent, the characteristic pollutants of the electroplating waste liquid are mainly heavy metal nickel, total phosphorus, ammonia nitrogen, total nitrogen, COD and organic matter. Specifically, the main components are: total phosphorus 30-34g / l, hypophosphite and phosphite, chemical oxygen demand (COD) 60-77.5g / l, ammonia nitrogen 3.3-4.7g / l, total nitrogen 5.1-6.2g / l, nickel 6.8-8.7g / l, pH=4-6, specific gravity 1.10-1.20. The significant characteristics of the electroless nickel plating waste liquid are high salt content of the solution, nickel ions exist in the solution as stable complexes, and total phosphorus and total nitrogen are high. The existing technology adopts The oxidation and decomposition of complexes, followed by neutralization and precipitation, remove most of the phosphates and nickel ions in the solution. Calcium hydroxide or sodium hydroxide is often used as the precipitant. The treatment effect is acceptable, but the treatment cost is relatively high.

[0004] The chemical reaction equation for oxidation and complex breaking using hydrogen peroxide is as follows: Where, Represents a complex of nickel ions.

[0005] In use During the oxidation process, sodium hypophosphite and sodium phosphite will consume a lot of Normally, in nickel plating wastewater, hypophosphite accounts for 40% and phosphite accounts for 60%. It takes 4 molecules of hydrogen peroxide to oxidize one molecule of sodium hypophosphite into orthophosphate, and 2 molecules of hydrogen peroxide to oxidize one molecule of sodium phosphite into orthophosphate. Oxidation and complex destruction require a high volume of hydrogen peroxide. The 35% concentration of industrial hydrogen peroxide introduces significant water into the reaction system, increasing steam consumption for subsequent evaporation and desalination, leading to high wastewater treatment costs. Using hydrogen peroxide alone to oxidize chemical nickel plating wastewater requires 200-400 kg of 35% industrial hydrogen peroxide per ton of wastewater to oxidize phosphite. This high wastewater treatment cost makes it difficult to promote in chemical nickel plating plants. Summary of the Invention

[0006] In order to solve the above problems, the present application provides a pre-oxidation treatment device and process control method for chemical nickel plating waste liquid.

[0007] This application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a pre-oxidation treatment device for chemical nickel plating waste liquid, comprising a reactor, a waste liquid storage tank, a temporary storage tank, an acid storage tank, and an oxygen storage tank arranged around the reactor and connected by pipelines, and a valve body assembly for controlling the flow of the pipeline; the reactor has a liquid outlet, a first liquid inlet, and a second liquid inlet; a first circulation loop is formed between the liquid outlet and the first liquid inlet of the reactor, a first pump body and a first venturi mixer are provided in the first circulation loop, and the acid storage tank and the oxygen storage tank are both connected to the low-pressure port pipeline of the first venturi mixer;

[0009] A second circulation loop is formed between the liquid outlet of the reactor and the second liquid inlet. A second pump body and a second venturi mixer are provided in the second circulation loop. The air outlet at the top of the reactor is connected to the low-pressure port pipeline of the second venturi mixer.

[0010] Furthermore, the first venturi mixer is arranged between the waste liquid storage tank and the liquid inlet of the reactor, and the second pump body is arranged between the temporary storage tank and the liquid inlet of the reactor.

[0011] Furthermore, in the above-mentioned first circulation loop, a first valve body is provided between the liquid outlet of the reactor and the first pump body, and a second valve body is provided between the first pump body and the first Venturi mixer.

[0012] Furthermore, in the above-mentioned second circulation loop, a third valve body is provided between the liquid outlet of the reactor and the second pump body, and a fourth valve body is provided between the second pump body and the second venturi mixer.

[0013] Furthermore, the reactor is equipped with a safety valve, a temperature sensor, a pressure sensor, a liquid level gauge and a pH meter.

[0014] Furthermore, the above-mentioned valve body assembly also includes a fifth valve body for controlling the flow of the waste liquid storage tank; a sixth valve body for controlling the flow of the oxygen storage tank; a seventh valve body for controlling the flow of the acid storage tank; an eighth valve body for controlling the flow entering the temporary storage tank; and an exhaust valve located at the top of the reactor.

[0015] In a second aspect, the present application provides a method for controlling a pre-oxidation process of chemical nickel plating waste liquid, which controls the above-mentioned pre-oxidation treatment equipment through a PLC chip; the pre-oxidation process control method comprises:

[0016] The nickel plating waste liquid in the waste liquid storage tank is passed into the reactor and the liquid level is stopped when the level reaches a preset level; the oxygen in the oxygen storage tank is transported to the reactor, the air in the reactor is evacuated, and the oxygen supply is stopped after the air pressure in the reactor reaches a preset value; the valve body and the pump body on the second circulation loop are controlled to open to carry out the oxidation reaction. When the oxygen pressure remains unchanged, the reaction is completed, and the valve body and the pump body connected to the temporary storage tank are controlled to open to discharge the liquid;

[0017] The oxidation reaction process also includes continuously detecting the pH value and oxygen pressure of the reaction system, and performing a control process of automatically replenishing acid and oxygen at the right time.

[0018] Furthermore, the above-mentioned automatic acid replenishment control process includes: when the pH value of the reaction system is higher than the preset upper limit value, controlling the flow path of the acid liquid storage tank and the valve body and pump body on the first circulation loop to perform automatic acid replenishment until the pH value of the reaction system reaches the preset lower limit value and then stops acid replenishment, thereby performing cyclic detection.

[0019] Furthermore, the above-mentioned automatic oxygen replenishment control process includes: when the oxygen pressure of the reaction system is lower than the preset lower limit value, controlling the flow path of the oxygen storage tank to perform automatic oxygen replenishment until the oxygen pressure of the reaction system reaches the preset upper limit value and then stopping replenishment, thereby cyclically detecting.

[0020] Furthermore, during the oxidation reaction, the step of heating the reactor until the temperature of the reaction system reaches 55-65° C. is included and then stopping the heating.

[0021] In summary, this application has the following beneficial effects:

[0022] 1. The pre-oxidation treatment equipment and process control method for chemical nickel plating waste liquid provided by the present application can pre-oxidize conventional chemical nickel plating waste liquid, use oxygen to oxidize hypophosphite and phosphite in the nickel plating waste liquid into phosphate, and by continuously adding part of the acid solution during the oxidation process, keep the pH of the reaction system less than 6, so that the pre-oxidation reaction is carried out more thoroughly, thereby further reducing the subsequent The consumption of industrial hydrogen peroxide in the oxidation and decomposition process can reduce the treatment cost of nickel plating waste liquid.

[0023] 2. In the pre-oxidation treatment equipment and control method for chemical nickel plating waste liquid provided in the present application, by setting a first circulation loop and a second circulation loop, automatic acid replenishment and automatic oxygen replenishment can be achieved during the oxidation reaction, so that the oxidation reaction can proceed more thoroughly; at the same time, through the setting of the valve body assembly and the pump body assembly, precise control is facilitated and the degree of automation is high.

[0024] 3. A first venturi mixing reactor is set in the first circulation loop. Oxygen and acid are mixed with the reaction liquid through the first venturi mixing reactor and enter the reactor, which is beneficial to increase the contact area between the reaction liquid and the newly added oxygen or acid.

[0025] 4. A second Venturi mixing reactor is installed in the second circulation loop. The low-pressure port of the Venturi is connected to the pipe at the top of the reactor to re-introduce unreacted oxygen above the reactor liquid surface into the reactor, forming an oxygen circulation loop for recycling oxygen. During the jet flow process, the Venturi mixing reactor converts oxygen and liquid into mist-like particles, increasing the contact surface between oxygen and liquid and improving the oxidation reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic diagram of a pre-oxidation treatment device for chemical nickel plating waste liquid provided by the present application;

[0027] FIG2 is a flow chart of a method for controlling a pre-oxidation process of chemical nickel plating waste liquid provided in the present application.

[0028] Reference numerals:

[0029] Reactor 100; safety valve 101; liquid level gauge 102; pressure sensor 103; temperature sensor 104; pH meter 105; first liquid inlet 106; second liquid inlet 107; liquid outlet 108; ninth valve body 109; aeration plate 110; waste liquid storage tank 200; fifth valve body 201; oxygen storage tank 300; sixth valve body 301; acid storage tank 400; seventh valve body 401; temporary storage tank 500; eighth valve body 501;

[0030] First circulation loop 600 ; first valve body 601 ; first pump body 602 ; second valve body 603 ; first venturi mixer 604 ; second circulation loop 700 ; third valve body 701 ; second pump body 702 ; fourth valve body 703 ; second venturi mixer 704 .

[0031] DETAILED DESCRIPTION

[0032] The embodiments of the present invention will be described in detail below with reference to the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Specific conditions not specified in the examples are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used without indicating the manufacturer are all conventional products that can be purchased commercially.

[0033] Example 1

[0034] This embodiment provides a pre-oxidation treatment device for chemical nickel plating waste liquid, which is used to treat chemical nickel plating waste liquid in the Before the oxidation and decomposition, pre-oxidation treatment is carried out to use oxygen to oxidize the hypophosphite and phosphite in the nickel plating wastewater into phosphate, thereby reducing The amount of industrial hydrogen peroxide used in the oxidation and network breaking process.

[0035] The pre-oxidation treatment equipment includes a reactor 100, surrounded by a waste liquid storage tank 200, an oxygen storage tank 300, an acid storage tank 400, and a temporary storage tank 500. Each tank is connected to the reactor 100 by pipelines, and valve assemblies are installed on the pipelines to control the flow in and out of each tank. The valve assemblies are electric or pneumatic control valves. The valve assemblies, instruments, valves, pipelines, and pumps used in this embodiment are all resistant to acid and alkali corrosion, temperature, and pressure.

[0036] The reactor 100 is the main place where the pre-oxidation reaction is carried out. A liquid outlet 108 is provided at the bottom of the reactor 100, and a first liquid inlet 106 and a second liquid inlet 107 are provided on the side wall of the reactor 100. The waste liquid storage tank 200 is connected to the first liquid inlet 106 of the reactor 100. The waste liquid storage tank 200 stores nickel plating waste liquid that has been acidified and filtered to remove impurities, and is used to input waste liquid to be treated into the reactor 100. The temporary storage tank 500 is connected to the liquid outlet 108 of the reactor 100. The waste liquid that has undergone pre-oxidation treatment in the reactor 100 is transported to the temporary storage tank 500 for buffering, and is used as the raw waste liquid for the next step of H2O2 oxidation and decomposition treatment. The pre-oxidation treatment equipment is also provided with a first circulation loop 600 and a second circulation loop 700 around the reactor 100:

[0037] (1) The first circulation loop 600 is disposed between the liquid outlet 108 and the first liquid inlet 106 of the reactor 100. A first valve body 601, a first pump body 602, a second valve body 603, and a first venturi mixer 604 are sequentially disposed in the first circulation loop 600 along the liquid flow direction. Specifically, the first valve body 601 is disposed between the liquid outlet 108 and the first pump body 602 of the reactor 100, and the first venturi mixer 604 is disposed between the second valve body 603 and the first liquid inlet 106.

[0038] At the same time, to save on pump and pipeline design, in a preferred embodiment, the first pump body 602, the second valve body 603, and the first venturi mixer 604 are disposed on the pipeline connecting the waste liquid storage tank 200 and the first liquid inlet 106. To facilitate flow control of the waste liquid storage tank 200, a fifth valve body 201 is disposed between the waste liquid storage tank 200 and the first pump body 602, and the fifth valve body 201 is not within the first circulation loop 600.

[0039] The oxygen storage tank 300 is connected to the low-pressure port pipeline of the first venturi mixer 604 for supplying oxygen to the reactor 100. The oxygen storage tank 300 is provided with a sixth valve body 301 for controlling the oxygen flow rate on the pipeline connected to the first venturi mixer 604. By controlling the opening and closing of the sixth valve body 301, the oxygen in the oxygen storage tank 300 can be automatically delivered to the first venturi mixer 604 because the pressure is greater than the pressure inside the reactor 100. During the jet process, the first venturi mixing reactor converts the oxygen and the reaction liquid into mist-like particles, increasing the contact surface between the oxygen and the reaction liquid and improving the oxidation reaction rate. The pressure reducing valve (not shown) of the oxygen storage tank is set to a pressure value greater than the maximum pressure required for the reaction set in the reactor 100 so that oxygen can be automatically delivered to the reactor 100.

[0040] The acid storage tank 400 is connected to the low-pressure port of the first venturi mixer 604 through a pipeline for replenishing the acid in the reactor 100. The acid storage tank 400 is provided with a seventh valve body 401 for controlling the flow rate of the acid on the pipeline connected to the first venturi mixer 604. When the reaction solution passes through the first circulation loop 600, by controlling the opening and closing of the seventh valve body 401, the first venturi mixer 604 can absorb the acid from the acid storage tank 400 to timely regulate the pH value of the reaction system.

[0041] (2) The second circulation loop 700 is disposed between the liquid outlet 108 and the second liquid inlet 107 of the reactor 100. The second circulation loop 700 is sequentially provided with a third valve body 701, a second pump body 702, a fourth valve body 703, and a second venturi mixer 704 along the liquid flow direction. Specifically, the third valve body 701 is disposed between the liquid outlet 108 and the second pump body 702, and the second venturi mixer 704 is disposed between the fourth valve body 703 and the second liquid inlet 107.

[0042] At the same time, in order to improve the utilization rate of oxygen, the top of the reactor 100 is connected to the low-pressure port pipe of the second Venturi mixer 704, so as to re-absorb the oxygen above the liquid surface of the reactor 100 that has not participated in the reaction into the liquid surface of the reactor 100, and generate mist particles in the second Venturi mixer 704, thereby increasing the gas-liquid contact area and improving the oxidation reaction rate.

[0043] To conserve pump and piping space, in a preferred embodiment, the third valve body 701 and the second pump body 702 are disposed on the pipeline connecting the liquid outlet 108 and the temporary storage tank 500. To further facilitate control of the flow rate entering the temporary storage tank 500, an eighth valve body 501 is disposed between the temporary storage tank 500 and the second pump body 702, but is not located within the second circulation loop 700.

[0044] The reactor 100 is equipped with a safety valve 101, a temperature sensor 104, a pressure sensor 103, a liquid level gauge 102, and a pH meter 105. A ninth valve body 109 is also installed on top of the reactor 100 to vent the reactor 100. An aeration plate 110 is installed below the reactor 100. The liquid outlet of the first Venturi mixing reactor 604 is connected to the aeration plate 110 inside the reactor 100 via a pipe. The functions of the various components installed on the reactor 100 are as follows:

[0045] (1) A safety valve 101 is provided. When a device failure occurs and the set pressure is reached, the safety valve 101 is opened immediately to prevent accidents.

[0046] (2) The liquid level meter 102 can be an ultrasonic level meter or a magnetic flap level meter. The amount of waste liquid added to the reactor 100 and the amount of liquid discharged are controlled by the change in the liquid level. The maximum and minimum liquid levels are set in the control. When the maximum liquid level is reached, the addition of the waste liquid to be treated is stopped. When the reaction is completed, the pre-treated waste liquid is discharged into the temporary storage tank 500. When the set minimum control liquid level is reached, the second pump body 702 for liquid discharge is closed and the discharge is stopped.

[0047] (3) The pressure sensor 103 is used to monitor the oxygen pressure within the reactor 100. By adjusting the pressure, the addition of oxygen is controlled or the reaction is terminated. The oxidation reaction speed increases with increasing oxygen partial pressure. The pressure should be within the designed pressure range of the reactor 100. Excessive pressure can easily cause leakage in pumps, valves, and pipelines. Typically, the oxygen partial pressure during the reaction is controlled between 0.1 and 0.5 MPa.

[0048] (4) Temperature sensor 104 is used to record and control the reaction temperature. Although the pre-oxidation reaction can be carried out at room temperature, the reaction speed is slow and the processing time of each batch is long, which affects the efficiency of the equipment. The most suitable temperature for the oxidation reaction is 50-90°C, and the maximum temperature of the reaction system can reach 120°C. When the temperature is heated from room temperature to 60°C, the heating can be stopped and the normal oxidation reaction can be carried out. Under normal circumstances, the reaction can be completed in 2-4 hours.

[0049] (5) During the jetting process, the Venturi mixing reactor converts oxygen and the reaction liquid into mist particles, which increases the contact surface between the oxygen and the reaction liquid and improves the oxidation reaction rate. At the same time, the unreacted oxygen at the top of the reactor 100 can be re-absorbed into the reactor 100 for recycling or absorbed into the acid solution to reduce the acidity of the redox reaction.

[0050] (6) The pH meter 105 is used to monitor the changes in the acidity of the oxidation reaction system. The system can be set up so that when the acidity pH is 4, acid addition is started and sucked through the venturi mixer; when the pH is 0, acid addition is stopped.

[0051] (7) The aeration plate 110 installed at the bottom of the reactor 100 is used to even out the gas and liquid, generate microbubbles or liquid particles, and also play a stirring role.

[0052] Example 2

[0053] This embodiment provides a pre-oxidation process control method for chemical nickel plating waste liquid. All operating programs of the control method are written into a PLC control chip, which is used to control the pre-oxidation treatment equipment provided in Example 1.

[0054] The control method comprises the following steps:

[0055] (1) System startup: Self-check: All valve bodies are in the closed state, and the safety valve 101 is also in the closed state. The first pump body 602 and the second pump body 702 are in the stopped state, and the temperature sensor 104 and the pressure sensor 103 are in normal state.

[0056] (2) System operation: The fifth valve body 201, the second valve body 603 and the ninth valve body 109 are opened, and the first pump body 602 is started to pump the nickel plating waste liquid to be treated in the waste liquid storage tank 200 into the reactor 100. When the liquid level meter 102 detects that the liquid level reaches the control height, the first pump body 602 stops. The fifth valve body 201 and the second valve body 603 are closed, the sixth valve body 301 is opened, and the oxygen in the oxygen storage tank 300 is

[0057] The oxygen is delivered to the reactor 100 and the air above the liquid level in the reactor 100 is evacuated (the evacuation time can be set according to the flow rate-time function). After the exhaust is completed, the ninth valve body 109 is closed, and oxygen continues to be supplied to the reactor 100. When the pressure sensor 103 detects that the pressure in the reactor 100 has reached the set reaction pressure upper limit, the sixth valve body 301 is closed.

[0058] (3) Reaction stage: The third valve body 701 and the fourth valve body 703 are opened, and the second pump body 702 is started to carry out the oxidation reaction. At this time, the liquid in the reactor 100 can be heated to the set temperature (55-65°C) according to the reaction temperature requirements, and the heating is stopped. As the reaction proceeds, the liquid temperature will slowly rise, and the maximum temperature can reach above 100°C. During the reaction, the acidity in the reaction system will slowly decrease, the pH value will increase, and the oxygen pressure will slowly decrease. When the pH meter 105 detects that the pH value in the reaction system has risen to the set pH upper limit, the first valve body 601, the second valve body 603 and the seventh valve body 401 are opened, the first pump body 602 is turned on, and the acid in the acid storage tank 400 is sucked into the reactor 100 through the Venturi mixing reaction for automatic acid replenishment; when the acidity in the reaction system reaches the pH lower limit (pH=0), the first pump body 602 is stopped, the first valve body 601, the second valve body 603 and the seventh valve body 401 are closed, and the acid addition is stopped. Automatic acid adding program, with this cycle, until the reaction terminates. When the pressure sensor 103 monitors that the oxygen pressure in the reactor 100 is lower than the set value (such as the set value is 0.12MPa), the sixth valve body 301 opens, and the oxygen in the oxygen storage tank 300 is delivered to the reactor 100 by its own pressure. Now, the oxygen partial pressure rises in the reaction system, and when it reaches the set pressure upper limit (such as 0.3MPa), the sixth valve body 301 closes. Automatic oxygen supplement program, with this cycle, until the reaction terminates. When the pH value and oxygen pressure in the reaction system reach the set value simultaneously, the automatic acid adding program is preferentially started. After acid addition terminates, the automatic oxygen supplement program is then carried out.

[0059] (4) End of reaction: When the pressure sensor 103 detects that the change in the system oxygen pressure within 30 minutes is less than 0.01 MPa, the reaction is deemed to be over. When heated to 60°C, the oxidation reaction can be completed in 2-4 hours; if it is at room temperature without heating, the reaction time is 12-18 hours. At this time, the second pump body 702 is shut down, the fourth valve body 703 is closed, the third valve body 701, the eighth valve body 501 and the ninth valve body 109 are opened, and the second pump body 702 is started to pump the liquid in the reactor 100 into the temporary storage tank 500. When the liquid level meter 102 detects that the liquid level in the reactor 100 reaches the set lower limit, the second pump body 702 is shut down, the third valve body 701 and the eighth valve body 501 are closed, and the reaction and control system completes a complete operation cycle and automatically enters the next cycle.

[0060] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. An equipment for pre-oxidation treatment of electroless nickel plating waste liquid, characterized in that It includes a reaction kettle, a waste liquid storage tank, a temporary storage tank, an acid liquid storage tank and an oxygen storage tank which are arranged around the reaction kettle and connected by pipelines, and a valve body assembly for controlling the pipeline flow rate; the reaction kettle has a liquid outlet, a first liquid inlet and a second liquid inlet; a first circulation loop is formed between the liquid outlet and the first liquid inlet of the reaction kettle, and a first pump body and a first Venturi mixer are arranged in the first circulation loop, and both the acid liquid storage tank and the oxygen storage tank are connected to the low-pressure port of the first Venturi mixer by pipelines; a second circulation loop is formed between the liquid outlet and the second liquid inlet of the reaction kettle, and a second pump body and a second Venturi mixer are arranged in the second circulation loop, and the top of the reaction kettle is connected to the low-pressure port of the second Venturi mixer by a pipeline.

2. The pre-oxidation treatment equipment for electroless nickel plating waste liquid according to claim 1, characterized in that The first Venturi mixer is arranged between the waste liquid storage tank and the liquid inlet of the reaction kettle, and the second pump body is arranged between the temporary storage tank and the liquid inlet of the reaction kettle.

3. The pre-oxidation treatment equipment for electroless nickel plating waste liquid according to claim 1, characterized in that In the first circulation loop, a first valve body is arranged between the liquid outlet of the reaction kettle and the first pump body, and a second valve body is arranged between the first pump body and the first Venturi mixer.

4. The pre-oxidation treatment equipment for electroless nickel plating waste liquid according to claim 1, characterized in that In the second circulation loop, a third valve body is arranged between the liquid outlet of the reaction kettle and the second pump body, and a fourth valve body is arranged between the second pump body and the second Venturi mixer.

5. The pre-oxidation treatment equipment for electroless nickel plating waste liquid according to any one of claims 1-4, characterized in that A safety valve, a temperature sensor, a pressure sensor, a liquid level gauge and a pH meter are installed on the reaction kettle.

6. The pre-oxidation treatment equipment for electroless nickel plating waste liquid according to any one of claims 1-4, characterized in that The valve body assembly further includes a fifth valve body for controlling the flow rate of the waste liquid storage tank; a sixth valve body for controlling the flow rate of the oxygen storage tank; a seventh valve body for controlling the flow rate of the acid liquid storage tank; an eighth valve body for controlling the flow rate into the temporary storage tank; and an exhaust valve located at the top of the reaction kettle.

7. A method for controlling the pre-oxidation process of electroless nickel plating waste liquid, characterized in that, It controls the pre-oxidation treatment equipment as described in any one of claims 1-6 through a PLC chip; The pre-oxidation process control method includes: feeding the nickel-plating waste liquid in the waste liquid storage tank into the reaction kettle and stopping when it reaches the preset liquid level; transporting the oxygen in the oxygen storage tank to the reaction kettle, evacuating the air in the reaction kettle and stopping oxygen supply when the air pressure in the reaction kettle reaches the preset value; controlling the opening of the valve bodies and pump bodies on the second circulation loop to carry out the oxidation reaction, and when the oxygen pressure remains unchanged, the reaction ends, controlling the opening of the valve bodies and pump bodies communicated with the temporary storage tank to drain the liquid; during the oxidation reaction, it also includes continuously detecting the pH value and oxygen pressure of the reaction system and carrying out a control process of timely automatic acid supplementation and automatic oxygen supplementation. 8.. The pre-oxidation process control method for electroless nickel plating waste liquid according to claim 7, characterized in that The control process of automatic acid supplementation includes: when the pH value of the reaction system is higher than the preset upper limit value, controlling the flow path of the acid liquid storage tank and the valve bodies and pump bodies on the first circulation loop to perform automatic acid supplementation until the pH value of the reaction system reaches the preset lower limit value and then stopping acid supplementation, and detecting in this cycle.

9. The pre-oxidation process control method for electroless nickel plating waste liquid according to claim 7, characterized in that The control process of the automatic oxygen supply includes: when the oxygen pressure in the reaction system is lower than the preset lower limit value, controlling the flow path of the oxygen storage tank to perform automatic oxygen supply until the oxygen pressure in the reaction system reaches the preset upper limit value and then stopping the oxygen supply, and detecting in this cycle.

10. The pre-oxidation process control method for electroless nickel plating waste liquid according to any one of claims 7-9, characterized in that, During the process of the oxidation reaction, it also includes the step of heating the reaction kettle so that the temperature of the reaction system reaches 55-65 °C and then stopping the heating.

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