Palladium recovery method and palladium recovery system

Abstract

The application provides a palladium recovery method and a palladium recovery system. The application combines a displacement reaction with an adsorption technology, first effectively deposits high-concentration palladium ions into metal palladium, and then uses ion exchange resin to deeply adsorb residual palladium ions, thereby improving the poor treatment effect of zinc displacement method on low-concentration palladium ions, improving the palladium recovery rate, and the palladium recovery rate can reach more than 99.5%. The application optimizes the zinc powder feeding mode (zinc powder suspension), and accurately controls the zinc powder addition amount by monitoring the oxidation-reduction potential, so that the best displacement effect can be achieved, and the excessive use of zinc powder and the generation of residues can be reduced, thereby reducing the material cost and reducing the subsequent waste residue treatment demand.

Description

Technical Field

[0001] This application relates to the field of waste liquid treatment technology, and in particular to a palladium recovery method and palladium recovery system. Background Technology

[0002] Palladium-containing wastewater is mainly found in the palladium plating, nickel-palladium-gold plating, palladium activation, and palladium bath cleaning processes in circuit board or electroplating enterprises. Currently, technologies for recovering palladium from palladium-containing wastewater mainly include solvent extraction, adsorption, ion exchange resins, and metal replacement (e.g., zinc replacement). Zinc replacement has attracted much attention due to its simplicity, low cost, and environmental friendliness. This technology utilizes the potential difference between metals, using zinc as a replacement agent to deposit and recover palladium in the wastewater in metallic form. It not only has a high palladium recovery capacity but also significantly reduces pollutant emissions during the treatment process, contributing to environmental protection.

[0003] However, the traditional zinc displacement method is inefficient in solutions with low palladium concentrations, potentially leading to incomplete palladium ion replacement and its residue remaining in the solution. When using the zinc powder displacement method, improper control can result in excessive zinc powder input, increasing costs, and generating large amounts of residue requiring further treatment, thus increasing operating costs and environmental burden. Summary of the Invention

[0004] In view of this, this application proposes a palladium recovery method and a palladium recovery system to solve at least one of the above problems.

[0005] One embodiment of this application provides a palladium recovery method, comprising the following steps: adjusting the pH of palladium-containing waste liquid to 1-4; adding zinc powder suspension to the palladium-containing waste liquid for a displacement reaction, and monitoring the redox potential of the reaction solution (comprising zinc powder suspension and palladium-containing waste liquid) to maintain the redox potential of the reaction solution within the range of 200 mV-400 mV; filtering the reaction solution after the reaction is completed to obtain a supernatant and palladium sludge; adding the supernatant to an adsorption device to adsorb palladium in the supernatant; wherein the adsorption device includes an adsorption material, and the adsorption material includes resin.

[0006] One embodiment of this application provides a palladium recovery system, comprising a pH control tank, a reaction tank, a filter, and an adsorption device connected in sequence. The pH control tank is equipped with a stirrer and is used to adjust the pH of the palladium-containing waste liquid. The reaction tank is used for a displacement reaction and is equipped with a redox potential monitoring device to monitor the redox potential of the reaction liquid in the reaction tank in real time. The filter is used to filter the reaction liquid after the reaction is completed to obtain a supernatant and palladium sludge. The adsorption device is used to adsorb the supernatant, and the adsorption device includes an adsorption material, which includes resin.

[0007] The palladium recovery method and system of this application combine displacement reaction with adsorption technology. First, high-concentration palladium ions are effectively deposited as metallic palladium. Then, ion exchange resin is used to deeply adsorb the remaining palladium ions, thereby improving the poor treatment effect of the zinc displacement method on low-concentration palladium ions and significantly increasing the palladium recovery rate to over 99.5%. This application optimizes the zinc powder addition method (zinc powder suspension) and precisely controls the amount of zinc powder added by monitoring the redox potential, thus achieving the best displacement effect. Simultaneously, it reduces the excessive use of zinc powder and the generation of residue, lowering material costs and reducing the need for subsequent waste treatment. Attached Figure Description

[0008] Figure 1 A flowchart of a palladium recovery method provided in one embodiment of this application.

[0009] Figure 2 This is a schematic diagram of a palladium recovery system provided in one embodiment of this application.

[0010] Explanation of main component symbols 100: Palladium recovery system; 10: pH control tank; 11: Stirrer; 20: Reaction tank; 30: Filter; 40: Adsorption device; 50: Adjustment tank; 60: Supernatant detection tank; 70: Temporary storage tank.

[0011] The following detailed description, in conjunction with the accompanying drawings, further illustrates the embodiments of this application. Detailed Implementation

[0012] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the embodiments of this application pertain. The terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the embodiments of this application. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0013] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0014] It will be understood that when a layer is referred to as "on" another layer, it can be directly on that other layer or there can be an intermediate layer in between. Conversely, when a layer is referred to as "directly on" another layer, there is no intermediate layer. When a component is referred to as "fixed to," "mounted to," "set on," or "connected to" another component, it can be directly on the other component or there can be an intermediate component.

[0015] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0016] Please see Figure 1 The first aspect of this application provides a palladium recovery method for recovering palladium from palladium-containing wastewater. The palladium-containing wastewater can be, but is not limited to, wastewater generated in the circuit board industry or electroplating industry, such as palladium-containing wastewater generated during palladium plating, nickel-palladium-gold plating, palladium activation, and palladium bath cleaning processes. The pH value of the palladium-containing wastewater can be 1-12, and the palladium concentration can be 0.01 g / L-0.3 g / L. The palladium recovery method includes steps S10-S60.

[0017] S10 adjusts the pH of the palladium-containing waste liquid to 1-4.

[0018] The purpose of this step is to create an acidic environment suitable for the subsequent displacement reaction, as palladium reacts more readily with zinc under acidic conditions. Too low a pH may lead to excessive consumption of zinc powder (the reactant added in subsequent steps for the displacement reaction), increasing costs; too high a pH may affect the palladium displacement efficiency. Therefore, the pH of the palladium-containing waste liquid needs to be controlled between 1 and 4 to ensure the efficiency of the displacement reaction and to control costs.

[0019] In some embodiments, the pH of palladium-containing waste liquid can be adjusted to 1-4 using solutions such as hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid, but not limited to these.

[0020] In some embodiments, before adjusting the pH of the palladium-containing waste liquid, step S00 can be performed: adding the palladium-containing waste liquid to an equalization tank and allowing it to stand to stabilize the water quality. Stabilizing the water quality can prevent other impurity ions from interfering with the reaction and improve the palladium recovery efficiency.

[0021] S20, add zinc powder suspension to palladium-containing waste liquid (pH adjusted to 1~4) to carry out displacement reaction, and monitor the redox potential of the reaction solution (composed of zinc powder suspension and palladium-containing waste liquid) to keep the redox potential of the reaction solution in the range of 200 mV~400 mV.

[0022] The zinc substitution method is based on the principle of metal substitution reaction. It utilizes the electrochemical potential difference between zinc powder and palladium ions to reduce palladium to metallic palladium. The reaction equation is as follows: Pd2+ +Zn(s)→Pd(s)+Zn 2+ Redox potential (OPR) monitoring is essential to ensure the reaction proceeds under suitable redox conditions, avoiding over-reduction or incomplete reaction. A low ORP value (below 200 mV) requires an increase in the zinc dosage, while a high ORP value may indicate excessive zinc addition, necessitating a reduction in the zinc powder suspension to control costs and prevent side reactions. The zinc powder suspension should be added slowly to avoid zinc powder agglomeration.

[0023] In some embodiments, the concentration of the zinc powder suspension is 2% to 10% (w / w%), and the pH is neutral. The weight ratio of zinc to palladium in the reaction solution can be (1 to 50):1, which can be adjusted according to the ORP value.

[0024] In some embodiments, an aeration and stirring device may be provided in the reaction vessel for the displacement reaction to agitate the reaction liquid, improve reactivity, and introduce air into the reaction vessel, thereby carrying away the generated hydrogen gas (hydrogen gas is generated in the displacement reaction). The hydrogen gas can be released at a rate of 2 m... 3 The discharge rate is / min. The aeration rate of the aeration and stirring device can be more than 10 times the volume of the reaction vessel per minute (for example, the aeration rate can be 0.3 m³ / min). 3 / min~1.5 m 3 ( / min) to prevent hydrogen accumulation. The aeration and stirring device can be placed at the bottom of the reaction vessel to reduce dead zones in the stirring.

[0025] Furthermore, a flow detector can be installed at the top of the reaction vessel to detect the hydrogen concentration. When the hydrogen concentration is detected to be above 2000 mg / L, the flow detector issues an early warning, at which point the aeration rate can be increased by 10% to 20%. When the hydrogen concentration is detected to be above 4000 mg / L, the flow detector issues a warning, and the aeration rate can be increased by 20% to 50%.

[0026] S30, after the reaction is complete, filter the reaction solution to obtain the supernatant and palladium mud.

[0027] The filtration step is to separate the palladium produced in the reaction from the unreacted zinc powder and other impurities. Filtration yields palladium sludge with a high palladium content, which facilitates subsequent purification and processing.

[0028] In some embodiments, the palladium weight percentage in the palladium mud is 50% or more (≥50%).

[0029] In some embodiments, the filtration precision can be 1 µm to 10 µm, that is, the filtration device can intercept particles with a diameter between 1 micrometer and 10 micrometers.

[0030] S40, the supernatant is added to the adsorption device to adsorb palladium from the supernatant. The adsorption device includes an adsorption material, which includes resin.

[0031] Adsorption technology (ion exchange technology) utilizes the electrostatic interaction between the functional groups on the surface of the adsorbent material and ions in the solution to recover heavy metals, and is suitable for the recovery of low concentrations of palladium.

[0032] In some embodiments, the palladium content in the supernatant can be determined before adding the supernatant to the adsorption device. If the palladium content in the supernatant is less than or equal to 1 mg / L, the supernatant is added to the adsorption device to adsorb the palladium in the supernatant. If the palladium content in the supernatant is greater than 1 mg / L, the supernatant is returned to the initial conditioning tank for another displacement reaction.

[0033] In some embodiments, the adsorbent material includes resin and activated carbon. The resin is a highly selective resin, which enhances the adsorption capacity for palladium ions.

[0034] In some embodiments, the palladium content of the waste liquid obtained after adsorption can also be determined. If the palladium content in the waste liquid is less than or equal to 0.1 mg / L, the waste liquid meets the recycling standard and can be discharged into a temporary storage tank for buffering; if the palladium content in the waste liquid is greater than 0.1 mg / L, the waste liquid is returned to the adsorption device for adsorption again.

[0035] Please see Figure 2 The second aspect of this application provides a palladium recovery system 100, which can recover palladium from palladium-containing waste liquid using the palladium recovery method described above. The palladium recovery system 100 includes a pH control tank 10, a reaction tank 20, a filter 30, and an adsorption device 40 connected in sequence. The pH control tank 10 is equipped with a stirrer 11, which is used to adjust the pH of the palladium-containing waste liquid, and the stirrer 11 helps to achieve uniform mixing. The reaction tank 20 is equipped with a redox potential monitoring device (not shown) to monitor the redox potential of the reaction liquid in the reaction tank 20 in real time. The filter 30 is used to filter the reaction liquid after the reaction is completed to obtain a supernatant and palladium sludge. The supernatant enters the adsorption device 40 for adsorption. The adsorption device 40 includes an adsorption material (not shown), including resin, which can efficiently adsorb palladium (low concentration, e.g., ≤1 mg / L) in the supernatant.

[0036] In some embodiments, such as Figure 2 As shown, the bottom of the reaction tank 20 is conical. The bottom of the reaction tank 20 can be connected to an aeration and stirring device (not shown), which is used to stir the reaction liquid and introduce air into the reaction tank 20, thereby carrying away the generated hydrogen gas (hydrogen gas is generated in the displacement reaction). The hydrogen gas can be released at a rate of 2 m... 3The discharge rate is / min. The aeration rate of the aeration and stirring device can be more than 10 times the volume of the reaction vessel per minute (for example, the aeration rate can be 0.3 m³ / min). 3 / min~1.5 m 3 ( / min) to prevent hydrogen accumulation. The aeration and stirring device can be located at the bottom of the reaction vessel to reduce dead zones. The zinc powder suspension can be introduced from the bottom of the reaction tank 20 and stirred synchronously during aeration, which can improve the reactivity of the displacement reaction.

[0037] Furthermore, a flow detector (not shown) can be installed at the top of the reaction tank 20 to detect the hydrogen concentration. When the detected hydrogen concentration is above 2000 mg / L, the flow detector issues an early warning, at which point the aeration rate can be increased by 10% to 20%. When the detected hydrogen concentration is above 4000 mg / L, the flow detector issues a warning, and the aeration rate can be increased by 20% to 50%.

[0038] In some embodiments, such as Figure 2 As shown, the palladium recovery system 100 also includes an equalization tank 50. The equalization tank 50 is connected to the pH control tank 10. Before the palladium-containing waste liquid enters the pH control tank 10, it can be allowed to settle in the equalization tank 50 to stabilize the water quality. Stabilizing the water quality can prevent other impurity ions from interfering with the reaction and improve the palladium recovery efficiency.

[0039] In some embodiments, such as Figure 2 As shown, the palladium recovery system 100 also includes a supernatant detection tank 60 and a temporary storage tank 70. The supernatant detection tank 60 is connected between the filter 30 and the adsorption device 40, and is also connected to the regulating tank 50. The concentration of palladium in the supernatant can be detected in the supernatant detection tank 60. If the palladium content in the supernatant is less than or equal to 1 mg / L, the supernatant will be added to the adsorption device 40 to adsorb the palladium in the supernatant. If the palladium content in the supernatant is greater than 1 mg / L, the supernatant will be returned to the regulating tank 50 for another displacement reaction. The temporary storage tank 70 is connected to the adsorption device 40 and the supernatant detection tank 60. After the adsorption device 40 completes the adsorption, the palladium content of the waste liquid is determined. If the palladium content in the waste liquid is less than or equal to 0.1 mg / L, the waste liquid meets the recycling standard and can be discharged into the temporary storage tank 70 for buffering. If the palladium content in the waste liquid is greater than 0.1 mg / L, the waste liquid will be returned to the supernatant detection tank 60 and then enter the adsorption device 40 for adsorption again.

[0040] The palladium recovery method and system provided in this application combine displacement reaction with adsorption technology. First, high-concentration palladium ions are effectively deposited as metallic palladium. Then, ion exchange resin is used to deeply adsorb the remaining palladium ions, thereby improving the poor treatment effect of the zinc displacement method on low-concentration palladium ions and significantly increasing the palladium recovery rate to over 99.5%. This application optimizes the zinc powder addition method (zinc powder suspension) and precisely controls the amount of zinc powder added by monitoring the redox potential, thus achieving the best displacement effect. Simultaneously, it reduces the excessive use of zinc powder and the generation of residue, lowering material costs and reducing the need for subsequent waste treatment.

[0041] The above description describes some specific embodiments of this application, but in actual applications, the application should not be limited to these embodiments. For those skilled in the art, other modifications and alterations made based on the technical concept of this application should fall within the protection scope of this application.

Claims

1. A method for palladium recovery, characterized in that, Includes the following steps: Adjust the pH of the palladium-containing waste liquid to 1-4; A zinc powder suspension was added to the palladium-containing waste liquid for a displacement reaction, and the redox potential of the reaction liquid was monitored to keep the redox potential of the reaction liquid in the range of 200 mV to 400 mV. After the reaction is complete, the reaction solution is filtered to obtain the supernatant and palladium mud; The supernatant is added to an adsorption device to adsorb palladium from the supernatant; wherein the adsorption device includes an adsorption material, and the adsorption material includes a resin.

2. The palladium recovery method as described in claim 1, characterized in that, Before the step of "adjusting the pH of the palladium-containing waste liquid to 1-4", the palladium recovery method further includes: adding the palladium-containing waste liquid into an adjustment tank and allowing it to stand.

3. The palladium recovery method as described in claim 2, characterized in that, Prior to the step of "adding the supernatant to the adsorption device", the palladium recovery method further includes: The palladium content in the supernatant was determined; If the palladium content of the supernatant is less than or equal to 1 mg / L, then the supernatant is added to the adsorption device; If the palladium content of the supernatant is greater than 1 mg / L, the supernatant is returned to the conditioning tank.

4. The palladium recovery method as described in claim 1, characterized in that, The palladium recovery method further includes: determining the palladium content in the waste liquid obtained after adsorption; If the palladium content in the waste liquid is less than or equal to 0.1 mg / L, the waste liquid meets the recycling standard; If the palladium content in the waste liquid is greater than 0.1 mg / L, the waste liquid is returned to the adsorption device.

5. The palladium recovery method as described in claim 1, characterized in that, The step of "adding zinc powder suspension to the palladium-containing waste liquid for a displacement reaction" further includes: introducing air into the reaction liquid at a flow rate of 0.3 m / s. 3 / min~1.5m 3 / min.

6. The palladium recovery method as described in claim 1, characterized in that, The palladium mud contains more than 50% palladium by weight.

7. A palladium recovery system for recovering palladium-containing waste liquid, characterized in that, The palladium recovery system includes a pH control tank, a reaction tank, a filter, and an adsorption device connected in sequence. The pH control tank is equipped with a stirrer and is used to adjust the pH of the palladium-containing waste liquid. The reaction tank is used for a displacement reaction and is equipped with a redox potential monitoring device to monitor the redox potential of the reaction liquid in the reaction tank in real time. The filter is used to filter the reaction liquid after the reaction is completed to obtain a supernatant and palladium sludge. The adsorption device is used to adsorb the supernatant and includes an adsorption material, which includes resin.

8. The palladium recovery system as described in claim 7, characterized in that, The bottom of the reaction tank is conical and connected to an aeration and stirring device. The aeration and stirring device is used to stir the reaction liquid and introduce air into the reaction tank. The top of the reaction tank is also equipped with a flow detector, which is used to detect the concentration of hydrogen.

9. The palladium recovery system as described in claim 7, characterized in that, The palladium recovery system also includes an adjustment tank, which is connected to the pH control tank.

10. The palladium recovery system as described in claim 7, characterized in that, The palladium recovery system further includes a supernatant detection tank and a temporary storage tank. The supernatant detection tank is connected between the filter and the adsorption device and is also connected to the regulating tank. The temporary storage tank is connected to the adsorption device and is also connected to the supernatant detection tank.

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