A method and system for treating silver reduction post-liquor

Abstract

This application discloses a method and system for treating silver reduction solution, belonging to the field of environmental protection technology. The treatment method includes the following steps: subjecting the silver reduction solution to a first-stage oxidative stripping process to obtain a first silver reduction solution; and subjecting the first silver reduction solution to a second-stage oxidative stripping process to obtain a treated silver reduction solution. This application employs a two-stage oxidative stripping method. The first-stage stripping oxidation focuses on the oxidation of sodium sulfite in the silver reduction solution, while the second-stage oxidative stripping focuses on the stripping of formaldehyde. Appropriate parameters such as pH, temperature, and gas-liquid ratio are used for each stage, achieving effective removal of sodium sulfite and formaldehyde from the silver reduction solution. Compared to traditional methods using oxidants to remove sodium sulfite and formaldehyde, this process is simpler, more effective, and has lower treatment costs, resulting in good economic and environmental benefits.

Description

Technical Field

[0001] This application belongs to the field of environmental protection technology, specifically relating to a method and system for treating silver reduction solution. Background Technology

[0002] In the non-ferrous smelting industry, especially in copper smelting, the hydrometallurgical silver extraction process generates a high-concentration organic-inorganic mixed waste liquid—silver reduction solution. This type of wastewater has significant compositional specificity: pH=8~9, sodium sulfite concentration as high as 15% or above, and formaldehyde concentration reaching 2000mg / L~4000mg / L, belonging to typical high-salt, high-COD wastewater.

[0003] If the silver reduction solution is directly mixed with other hydrometallurgical wastewater for treatment, although it will not cause significant interference to the heavy metal removal unit, it will bring a series of difficult-to-solve technical problems to the subsequent wastewater resource recycling system and zero-emission evaporation process: 1) Sodium sulfite is prone to decomposition during high-temperature evaporation, producing sulfur dioxide, which causes serious corrosion to equipment; its crystallization product, sodium sulfite, will form mixed crystals with other sodium sulfate, reducing the purity of sodium sulfate products and hindering the utilization of salt resources.

[0004] 2) Formaldehyde will volatilize in large quantities during the evaporation process and form polyoxymethylene polymers in the condensation system, which will cause the COD of the condensate to exceed the standard and cannot be directly reused in the production process, thus destroying the zero-discharge water circulation system for wastewater.

[0005] 3) Impact on direct wastewater reuse: Conventional heavy metal removal processes have extremely low removal efficiency for sodium sulfite and formaldehyde (usually less than 30%). Even if the heavy metal indicators meet the standards, the high concentration of sodium sulfite and formaldehyde remaining in the wastewater will still affect the quality of the reused water, resulting in high COD concentration in the reused water and making it impossible to reuse the wastewater.

[0006] 4) If traditional processes such as aeration oxidation of sodium sulfite and removal of formaldehyde by oxidants are used, the wastewater treatment cost increases due to the low oxidation utilization rate and high reagent cost.

[0007] Therefore, source treatment of silver reduction solution has become a key pre-treatment technology for achieving zero discharge and resource reuse of hydrometallurgical wastewater. Summary of the Invention

[0008] This application aims to at least partially solve one of the technical problems in the related art. Therefore, the purpose of this application is to provide a method and system for processing silver reduction solution.

[0009] In a first aspect, this application proposes a method for treating a silver reduction solution, the method comprising the following steps: The silver-reduced solution to be treated is subjected to a first-stage oxidative stripping to obtain the first silver-reduced solution. The first silver reduction solution was subjected to a two-stage oxidative stripping process to obtain the treated silver reduction solution. The operating conditions for the primary oxidation stripping include: air as the oxidant, a gas-liquid ratio of 350:1-450:1, a pH of 6-7, and a temperature of 50℃-60℃. The operating conditions for the secondary oxidation stripping include: the oxidant is air, the gas-liquid ratio is 400:1-500:1; the pH is 10.5-11.5; and the temperature is 50℃-60℃.

[0010] This application provides a method for treating a silver reduction solution. The method employs a two-stage oxidative stripping process: the first-stage stripping oxidation focuses on the oxidation of sodium sulfite in the silver reduction solution, while the second-stage oxidative stripping focuses on the stripping of formaldehyde. Each stage utilizes suitable parameters such as pH, temperature, and gas-liquid ratio to achieve the removal of sodium sulfite and the effective recovery and utilization of formaldehyde from the silver reduction solution. Compared to traditional methods using oxidants to remove sodium sulfite and formaldehyde, this process is simpler, more effective, and has lower processing costs, resulting in significant economic and environmental benefits.

[0011] In addition, the method for treating the silver reduction solution provided in this application may also have the following additional technical features: In some specific embodiments of this application, the operating conditions parameters of the primary oxidation stripping include: the oxidant is air, the gas-liquid ratio is 355:1-365:1; the pH is 6-7; and the temperature is 53℃-58℃.

[0012] In some specific embodiments of this application, the operating conditions parameters of the secondary oxidation stripping include: the oxidant is air, the gas-liquid ratio is 420:1-460:1; the pH is 10.5-11.5; and the temperature is 53℃-58℃.

[0013] In some specific embodiments of this application, the gas-liquid contact method in the primary oxidation stripping and the secondary oxidation stripping includes countercurrent contact, and the mass transfer packing for gas-liquid contact includes ceramic packing.

[0014] In some specific embodiments of this application, the silver reduction solution to be treated contains sodium sulfite with a mass percentage of ≥15% and formaldehyde with a concentration of ≥1500 mg / L; After the primary and secondary oxidative stripping processes, the sodium sulfite oxidation rate and formaldehyde removal rate in the silver reduction solution to be treated are not less than 98%.

[0015] In some specific embodiments of this application, it also includes: The formaldehyde removed by the first-stage and second-stage oxidative stripping is absorbed in water to obtain a formaldehyde solution. The operating conditions parameters of the absorption treatment include: the gas-liquid contact method includes countercurrent contact and the mass transfer packing for gas-liquid contact includes ceramic packing; the gas-liquid ratio is 200:1-300:1; and the temperature is 15℃-25℃.

[0016] Secondly, this application proposes a treatment system for silver reduction solution. This system, used to implement the silver reduction solution treatment method described in the first aspect, includes a primary packed oxidation-stripping tower and a secondary packed oxidation-stripping tower. The top of the primary packed oxidation-stripping tower is connected to a first circulating pump, and the bottoms of both the primary and secondary packed oxidation-stripping towers are connected to blowers. The top of the secondary packed oxidation-stripping tower is connected to both the first and second circulating pumps. Therefore, this treatment system can effectively remove sodium sulfite and formaldehyde from the silver reduction solution. Compared to the traditional method of using oxidants to remove sodium sulfite and formaldehyde, this process is simpler, more effective, and has lower processing costs, resulting in good economic and environmental benefits.

[0017] In addition, the silver reduction solution treatment system provided in this application may also have the following additional technical features: In some specific embodiments of this application, an adjustment tank is also included, which is connected in sequence to a filter and a first heat exchanger, and the first heat exchanger is connected to the primary packing oxidation stripping tower.

[0018] In some specific embodiments of this application, a packed absorption tower is also included, which is connected to a second heat exchanger via the second circulating pump.

[0019] In some specific embodiments of this application, the packed absorber is also connected to a third circulating pump.

[0020] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0021] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the technical solutions in conjunction with the following drawings, wherein: Figure 1 A schematic diagram of the process for the silver reduction solution provided in this application.

[0022] Explanation of reference numerals in the attached figures: Figure 1 middle: 1-Equalization tank, 2-Water pump, 3-Filter, 4-Blower, 5-First heat exchanger, 6-First-stage packed oxidation stripping tower, 7-First circulation pump, 8-Second-stage packed oxidation stripping tower, 9-Second circulation pump, 10-Packed absorption tower, 11-Third circulation pump, 12-Second heat exchanger. Detailed Implementation

[0023] The specific embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The specific embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0024] In a first aspect, this application proposes a method for treating a silver reduction solution, the method comprising the following steps: The silver-reduced solution to be treated is subjected to a first-stage oxidative stripping to obtain the first silver-reduced solution. The first silver reduction solution was subjected to a two-stage oxidative stripping process to obtain the treated silver reduction solution. The operating conditions for the primary oxidation stripping include: oxidant is air, 350:1-450:1; pH is 6-7; temperature is 50℃-60℃. The operating conditions for the secondary oxidation stripping include: the oxidant is air, the gas-liquid ratio is 400:1-500:1; the pH is 10.5-11.5; and the temperature is 50℃-60℃.

[0025] This application provides a method for treating a silver reduction solution. The method employs a two-stage oxidative stripping process: the first-stage stripping oxidation focuses on the oxidation of sodium sulfite in the silver reduction solution, while the second-stage oxidative stripping focuses on the removal of formaldehyde. Each stage utilizes suitable parameters such as pH, temperature, and gas-liquid ratio to effectively remove sodium sulfite and formaldehyde from the silver reduction solution. Compared to traditional methods using oxidants to remove sodium sulfite and formaldehyde, this process is simpler, more effective, and has lower processing costs, resulting in significant economic and environmental benefits.

[0026] In embodiments of this application, the silver reduction solution may include silver reduction solution generated during processes such as wet smelting of copper anode mud, and its main characteristic is that it is rich in substances such as sodium sulfite and formaldehyde.

[0027] As an example, the gas-liquid ratio of the primary oxidation stripping can be 350:1, 380:1, 400:1, etc.; the pH can be 6, 6.4, 6.8, 7.0, etc.; and the temperature can be 50℃, 53℃, 55℃, 58℃, etc.

[0028] As an example, the gas-liquid ratio of the secondary oxidation stripping can be 400:1, 440:1, 480:1, 500:1, etc.; the pH can be 10.5, 10.8, 11, 11.5, etc.; and the temperature can be 50℃, 53℃, 55℃, 58℃, etc.

[0029] In addition, the method for treating the silver reduction solution provided in this application may also have the following additional technical features: In some specific embodiments of this application, the operating conditions for the primary oxidative stripping include: air as the oxidant, a gas-liquid ratio of 360:1, a pH of 6.4, and a temperature of 55°C. This further improves the removal rate of sodium sulfite from the silver reduction solution.

[0030] In some specific embodiments of this application, the operating conditions for the secondary oxidative stripping include: air as the oxidant, a gas-liquid ratio of 440:1, a pH of 11, and a temperature of 55°C. This further improves the formaldehyde removal rate from the silver-reduced solution.

[0031] In some specific embodiments of this application, the gas-liquid contact method in the primary and secondary oxidative stripping processes includes countercurrent contact, and the mass transfer packing material for the gas-liquid contact includes ceramic packing. Therefore, countercurrent contact can improve the removal rate of sodium sulfite and formaldehyde in the silver reduction solution.

[0032] In some specific embodiments of this application, the silver reduction solution to be treated contains sodium sulfite with a mass percentage ≥15% and formaldehyde with a concentration ≥1500 mg / L; after the first-stage oxidation stripping and the second-stage oxidation stripping, the sodium sulfite oxidation rate and formaldehyde removal rate in the silver reduction solution to be treated are not less than 98% and not less than 98%, respectively. Therefore, this application can effectively remove sodium sulfite and formaldehyde from the silver reduction solution by employing a two-stage temperature-appropriate high-pH stripping oxidation process.

[0033] In some specific embodiments of this application, the method further includes: passing the formaldehyde removed after the primary and secondary oxidative stripping processes into water for absorption treatment to obtain a formaldehyde solution; wherein the operating conditions of the absorption treatment include: the gas-liquid contact method includes countercurrent contact and the mass transfer packing material for gas-liquid contact includes ceramic packing material; the gas-liquid ratio is 200:1-300:1; and the temperature is 15℃-25℃. Therefore, this application employs a low-temperature absorption method to achieve the removal of formaldehyde from the gas by allowing it to enter the liquid phase, with a formaldehyde absorption rate of not less than 95%.

[0034] Secondly, this application proposes a treatment system for the silver reduction solution, such as... Figure 1As shown, the treatment system is used to implement the silver reduction solution treatment method described in the first aspect, including a primary packed oxidation stripping tower 6 and a secondary packed oxidation stripping tower 8. The top of the primary packed oxidation stripping tower 6 is connected to a first circulating pump 7, and the bottoms of both the primary packed oxidation stripping tower 6 and the secondary packed oxidation stripping tower 8 are connected to a blower 4. The top of the secondary packed oxidation stripping tower 8 is connected to both the first circulating pump 7 and a second circulating pump 9. Therefore, this treatment system can effectively remove sodium sulfite and formaldehyde from the silver reduction solution. Compared to the traditional method of using oxidants to remove sodium sulfite and formaldehyde, this process is simpler and more effective, with lower treatment costs, resulting in good economic and environmental benefits.

[0035] In addition, the silver reduction solution treatment system provided in this application may also have the following additional technical features: In some specific embodiments of this application, such as Figure 1 As shown, it also includes an adjustment tank 1, which is connected in sequence to a filter 3 and a first heat exchanger 5. The first heat exchanger 5 is connected to the primary packed oxidation stripping tower 6. This allows for the control of parameters such as pH and temperature in the silver reduction solution to be treated.

[0036] In some specific embodiments of this application, such as Figure 1 As shown, it also includes a packed absorption tower 10, which is connected to a second heat exchanger 12 via a second circulating pump 9. This allows for the absorption and treatment of formaldehyde.

[0037] In some specific embodiments of this application, such as Figure 1 As shown, the packed absorption tower 10 is also connected to a third circulating pump 11.

[0038] In some specific embodiments of this application, such as Figure 1 As shown, the above processing system includes the following processes: S1: After silver reduction, the solution first enters the conditioning tank 1, where the pH is adjusted to 9.5 using liquid alkali. It is then pressurized by pump 2 and passed to filter 3 (e.g., a bag filter) to remove any small amount of suspended solids before entering the first heat exchanger 5 (e.g., a plate heat exchanger). In the first heat exchanger 5 (e.g., a plate heat exchanger), steam and wastewater exchange heat to adjust the water temperature to 50℃ before entering the primary packed oxidation stripping tower 6.

[0039] S2: The liquid in the primary packed oxidation stripping tower 6 is sprayed from the top of the packed tower by the first circulation pump 7. The air is pressurized by the blower 4 and blown from the bottom of the primary packed oxidation stripping tower 6 from bottom to top. The wastewater and air increase the gas-liquid contact area through the packing in the tower. During the process, the formaldehyde in the water enters the gas phase, and the sodium sulfite in the wastewater is oxidized into sodium sulfate by the oxygen in the air.

[0040] After reaching the bottom of the primary packed oxidation stripping tower 6, the waste liquid is pressurized and circulated by the first circulating pump 7. A branch pipe is then connected from the spray pipe and enters the secondary packed oxidation stripping tower 8.

[0041] S3: The liquid inside the secondary packed oxidation stripping tower 8 is sprayed down from the top of the packed tower by the first circulating pump 7. The air is pressurized by the blower 4 and blown in from the bottom of the secondary packed oxidation stripping tower 8. The wastewater and air increase the gas-liquid contact area through the packing inside the secondary packed oxidation stripping tower 8. During the process, residual formaldehyde in the water enters the gas phase, and residual sodium sulfite in the wastewater is oxidized into sodium sulfate by oxygen in the air.

[0042] After the waste liquid reaches the bottom of the secondary packed oxidation stripping tower 8, it is then pressurized and circulated by the second circulation pump 9 and sprayed. The spray pipe is connected to a branch pipe and discharged into the subsequent treatment process.

[0043] After two-stage oxidative stripping, the sodium sulfite oxidation rate is no less than 98%, and the formaldehyde removal rate is no less than 98%.

[0044] S4: Formaldehyde-containing gas is discharged from the top of the primary packed oxidation stripping tower 6 and the secondary packed oxidation stripping tower 8 into the packed absorption tower 10.

[0045] The pure water inside the packed absorption tower 10 is pressurized by the second circulating pump 9 to the second heat exchanger 12 (such as a plate heat exchanger) to adjust the water temperature to 20°C. It is sprayed from the top of the packed absorption tower 10 downwards and passes through the packing inside the tower to increase the gas-liquid contact area with the formaldehyde-containing waste gas coming from the bottom of the packed absorption tower 10 upwards. The formaldehyde in the waste gas enters the liquid phase and is thus removed from the gas. The formaldehyde absorption rate is not less than 95%. The tail gas with a small amount of residual formaldehyde is discharged into the tail gas scrubbing system.

[0046] After the pure water absorbs formaldehyde, it reaches the bottom of the packed absorption tower 10 and is then pressurized and circulated by the third circulation pump 11. The spray pipe is connected to a branch pipe to discharge 1%~5% formaldehyde solution for reuse in the front-end process.

[0047] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.

[0048] Example 1 This embodiment provides a method and system for treating silver reduction solution, mainly including: performing a first-stage oxidative stripping on the silver reduction solution to be treated, wherein the working conditions of the first-stage oxidative stripping include: air as the oxidant, a gas-liquid ratio of 360:1; pH of 6.4; and a temperature of 55°C; to obtain a first silver reduction solution; performing a second-stage oxidative stripping on the first silver reduction solution, wherein the working conditions of the second-stage oxidative stripping include: air as the oxidant, a gas-liquid ratio of 440:1; pH of 11; and a temperature of 55°C; to obtain a treated silver reduction solution; specifically, as shown... Figure 1 As shown, it includes the following steps: S1: The silver reduction solution (derived from by-product wastewater from the wet smelting process of extracting silver from copper anode mud) first enters the equalization tank 1, where the pH is adjusted to 9.5 using liquid alkali. It is then pressurized by pump 2 and passed to filter 3 (e.g., a bag filter) to remove small amounts of suspended solids before entering the first heat exchanger 5 (e.g., a plate heat exchanger). In the first heat exchanger 5 (e.g., a plate heat exchanger), steam and wastewater exchange heat to adjust the water temperature to a preset temperature before entering the primary packed oxidation stripping tower 6.

[0049] S2: The liquid in the primary packed oxidation stripping tower 6 is sprayed from the top of the packed tower by the first circulation pump 7. The air is pressurized by the blower 4 and blown from the bottom of the primary packed oxidation stripping tower 6 from bottom to top. The wastewater and air increase the gas-liquid contact area through the packing in the tower. During the process, the formaldehyde in the water enters the gas phase, and the sodium sulfite in the wastewater is oxidized into sodium sulfate by the oxygen in the air.

[0050] After reaching the bottom of the primary packed oxidation stripping tower 6, the waste liquid is pressurized and circulated by the first circulating pump 7. A branch pipe is then connected from the spray pipe and enters the secondary packed oxidation stripping tower 8.

[0051] S3: The liquid inside the secondary packed oxidation stripping tower 8 is sprayed down from the top of the packed tower by the first circulating pump 7. The air is pressurized by the blower 4 and blown in from the bottom of the secondary packed oxidation stripping tower 8. The wastewater and air increase the gas-liquid contact area through the packing inside the secondary packed oxidation stripping tower 8. During the process, residual formaldehyde in the water enters the gas phase, and residual sodium sulfite in the wastewater is oxidized into sodium sulfate by oxygen in the air.

[0052] After the waste liquid reaches the bottom of the secondary packed oxidation stripping tower 8, it is then pressurized and circulated by the second circulation pump 9 and sprayed. The spray pipe is connected to a branch pipe and discharged into the subsequent treatment process.

[0053] S4: Formaldehyde-containing gas is discharged from the top of the primary packed oxidation stripping tower 6 and the secondary packed oxidation stripping tower 8 into the packed absorption tower 10.

[0054] The pure water inside the packed absorption tower 10 is pressurized by the second circulating pump 9 to the second heat exchanger 12 (such as a plate heat exchanger) to adjust the water temperature to 20°C. It is sprayed from the top of the packed absorption tower 10 downwards and passes through the packing inside the tower to increase the gas-liquid contact area with the formaldehyde-containing waste gas coming from the bottom of the packed absorption tower 10 upwards. The formaldehyde in the waste gas enters the liquid phase and is thus removed from the gas. The formaldehyde absorption rate is not less than 95%. The tail gas with a small amount of residual formaldehyde is discharged into the tail gas scrubbing system.

[0055] After the pure water absorbs formaldehyde, it reaches the bottom of the packed absorption tower 10 and is then pressurized and circulated by the third circulation pump 11. The spray pipe is connected to a branch pipe to discharge 1%~5% formaldehyde solution for reuse in the front-end process.

[0056] Comparative Example 1 This comparative example provides a conventional method for removing sodium sulfite and formaldehyde from the silver reduction solution in Example 1 using an oxidant, comprising the following steps: The process employs a combination of direct aeration oxidation and Fenton advanced oxidation: first, sodium sulfite is oxidized to sodium sulfate through microporous aeration; then, the pH is adjusted to around 3, and hydrogen peroxide and ferrous sulfate are added to carry out the Fenton reaction, where formaldehyde is mineralized into carbon dioxide and water by hydroxyl radicals. After the reaction, liquid alkali is added to adjust the pH to 6-7.

[0057] Comparative Example 2 This comparative example provides a method and system for treating the silver reduction solution, which differs from Example 1 only in that: (1) Adjust the working condition parameters of the first-stage oxidation stripping described in Example 1 to be the same as the working condition parameters of the second-stage oxidation stripping described in Example 1 (i.e., both the first-stage oxidation stripping and the second-stage oxidation stripping adopt the working condition parameters of the second-stage oxidation stripping described in Example 1).

[0058] Comparative Example 3 This comparative example provides a method and system for treating the silver reduction solution, which differs from Example 1 only in that: (1) Adjust the working condition parameters of the secondary oxidation stripping described in Example 1 to be the same as the working condition parameters of the primary oxidation stripping described in Example 1 (i.e., both primary oxidation stripping and secondary oxidation stripping use the working condition parameters of the primary oxidation stripping described in Example 1).

[0059] The removal rates of sodium sulfite and formaldehyde, as well as the treatment costs, in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are shown in Table 1.

[0060] Table 1

[0061] As shown in Table 1: Compared to the conventional treatment process in Comparative Example 1, the treatment method using the silver reduction solution of this application embodiment can significantly improve the removal rate of sodium sulfite and formaldehyde, and the treatment cost can be significantly reduced due to the good economic benefits of formaldehyde recovery.

[0062] The test results of Comparative Examples 2 and 3 show that adjusting the working conditions of the primary and secondary oxidative stripping processes in this application will significantly reduce the removal rates of sodium sulfite or formaldehyde.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for treating a silver reduction liquor, characterized by, Includes the following steps: The silver-reduced solution to be treated was subjected to a first-stage oxidative stripping to obtain the first silver-reduced solution. The first silver reduction solution was subjected to a two-stage oxidative stripping process to obtain the treated silver reduction solution. The operating conditions for the primary oxidation stripping include: air as the oxidant, a gas-liquid ratio of 350:1-450:1, a pH of 6-7, and a temperature of 50℃-60℃. The operating conditions for the secondary oxidation stripping include: the oxidant is air, the gas-liquid ratio is 400:1-500:1; the pH is 10.5-11.5; and the temperature is 50℃-60℃.

2. The silver reduction liquid treatment method according to claim 1, characterized by, The operating conditions for the primary oxidation stripping include: air as the oxidant, a gas-liquid ratio of 355:1-365:1, a pH of 6-7, and a temperature of 53℃-58℃.

3. The silver reduction liquid treatment method according to claim 1, characterized by, The operating conditions for the secondary oxidation stripping include: air as the oxidant, a gas-liquid ratio of 420:1-460:1, a pH of 10.5-11.5, and a temperature of 53℃-58℃.

4. The silver reduction liquid treatment method according to claim 1, characterized by, In the primary oxidation stripping and the secondary oxidation stripping, the gas-liquid contact method includes countercurrent contact, and the mass transfer packing for gas-liquid contact includes ceramic packing.

5. The silver reduction liquid treatment method according to claim 1, characterized by, The silver reduction solution to be treated contains sodium sulfite with a mass percentage of ≥15% and formaldehyde with a concentration of ≥1500 mg / L; After the primary and secondary oxidative stripping processes, the sodium sulfite oxidation rate and formaldehyde removal rate in the silver reduction solution to be treated are not less than 98%.

6. The method for treating the silver reduction solution according to any one of claims 1-5, characterized in that, Also includes: The formaldehyde removed by the first-stage and second-stage oxidative stripping is absorbed in water to obtain a formaldehyde solution. The operating conditions parameters of the absorption treatment include: the gas-liquid contact method includes countercurrent contact and the mass transfer packing for gas-liquid contact includes ceramic packing; the gas-liquid ratio is 200:1-300:1; and the temperature is 15℃-25℃.

7. A treatment system for silver reduction solution, characterized in that, The method for treating the silver reduction solution according to any one of claims 1-6 includes a primary packed oxidation stripping tower and a secondary packed oxidation stripping tower. The top of the primary packed oxidation stripping tower is connected to the first circulating pump, and the bottoms of both the primary packed oxidation stripping tower and the secondary packed oxidation stripping tower are connected to a blower. The top of the secondary packed oxidation stripping tower is connected to the first circulating pump and the second circulating pump.

8. The silver reduction solution treatment system according to claim 7, characterized in that, It also includes an adjustment tank, which is connected in sequence to a filter and a first heat exchanger, and the first heat exchanger is connected to the primary packed oxidation stripping tower.

9. The silver reduction solution treatment system according to claim 8, characterized in that, It also includes a packed absorption tower, which is connected to a second heat exchanger via the second circulating pump.

10. The silver reduction solution treatment system according to claim 9, characterized in that, The packed absorber is also connected to a third circulating pump.

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