A silver powder production mother liquor resource separation and recovery system and method

Abstract

The application belongs to the technical field of wastewater treatment and secondary resource recovery, and particularly relates to a silver powder production mother liquor resource separation and recovery system and method. The system comprises a silver recovery device, a desalination device, an organic matter membrane sorting device, a reverse osmosis device and a concentration device. The desalination device comprises a pH adjusting tank and an electrodialysis device. The electrodialysis device is provided with a pure water inlet, a raw material liquid inlet, a desalination liquid outlet and a nitrate concentrate outlet. The raw material liquid inlet of the electrodialysis device is in communication with the outlet of the pH adjusting tank. The organic matter membrane sorting device is used for separating the desalination liquid to obtain a large-molecule organic matter solution and a small-molecule organic matter solution. The silver powder production mother liquor resource separation and recovery system provided by the application can comprehensively recover and utilize silver resources, nitrate resources, dispersant resources and small-molecule reducing agent resources in the silver powder production mother liquor, thereby reducing environmental protection treatment costs and creating economic value.

Description

Technical Field

[0001] This application belongs to the field of wastewater treatment and secondary resource recycling technology, specifically relating to a resource separation and recycling system and method for silver powder production mother liquor. Background Technology

[0002] Silver powder is a major component of battery slurry, and many companies are committed to building new silver powder production projects. Currently, silver powder is mainly prepared using the liquid-phase reduction method. Silver nitrate is reduced to ultrafine silver powder by reducing agents (VC (vitamin C or ascorbic acid), ethanol, glucose, etc.). After separating and recovering the silver powder, a silver powder production mother liquor is generated. Its components include trace amounts of residual silver powder, dispersants (polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), etc.), reducing agents (VC, ethanol, glucose, etc.), and nitric acid. Therefore, this silver powder production mother liquor is characterized by high COD and high total nitrogen, an imbalanced carbon-nitrogen ratio, and very poor biochemical properties of the dispersants (PVP, PVA, etc.). Thus, it can only be treated using a high-energy-consuming evaporation process. Furthermore, the mother liquor containing impurities produced after evaporation needs to be sent out as hazardous waste for further treatment. The treatment cost per ton of water is estimated to exceed 400 yuan. Not only is the treatment cost high, but it also fails to effectively recover the various components to improve economic value.

[0003] This application content

[0004] The purpose of this application is to address the problems of high cost and low efficiency in the separation and recovery of various valuable components when using existing treatment systems and methods to process silver powder production mother liquor. The system provided by this application can achieve comprehensive recovery and utilization of small molecule organic resources such as silver resources, nitrate resources, dispersant resources, and reducing agents in silver powder production mother liquor, which can not only reduce environmental treatment costs, but also create economic value.

[0005] In a first aspect, this application provides a resource-based separation and recovery system for silver powder production mother liquor. The system includes: a silver recovery unit, a desalination unit, an organic membrane separation unit, a reverse osmosis unit, and a concentration unit;

[0006] The silver recovery device includes a concentration tank, an ultrafiltration device I, and a centrifuge. The concentration tank is equipped with a silver powder production mother liquor inlet, a first outlet, and a second outlet. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration device I. The ultrafiltration device I is used to intercept and separate silver powder from the water. The concentrated liquid outlet of the ultrafiltration device I is connected to the inlet of the concentration tank. The second outlet of the concentration tank is connected to the inlet of the centrifuge.

[0007] The desalination device includes a pH adjustment tank and an electrodialysis device. The inlet of the pH adjustment tank is connected to the permeate outlet of the ultrafiltration device I. The electrodialysis device is equipped with a pure water inlet, a raw material liquid inlet, a desalination material liquid outlet, and a nitrate concentrate outlet. The raw material liquid inlet of the electrodialysis device is connected to the outlet of the pH adjustment tank.

[0008] The organic membrane separation device is used to separate the desalination liquid into a solution rich in macromolecular organic matter and a solution rich in small molecule organic matter;

[0009] The reverse osmosis device is provided with an inlet and a composite carbon source concentrate outlet on the interception side. The inlet of the reverse osmosis device on the interception side is connected to the outlet of the small molecule organic solution of the organic membrane separation device.

[0010] The concentration device is a nanofiltration device II or an ultrafiltration device III, with an inlet and a dispersant concentrate outlet on its interception side. The inlet on the interception side of the concentration device is connected to the outlet of the macromolecular organic solution of the organic membrane separation device.

[0011] Secondly, this application provides a method for the resource-based separation and recovery of silver powder production mother liquor. The method is carried out in the aforementioned silver powder production mother liquor resource-based separation and recovery system, and includes the following steps:

[0012] S1. The silver powder production mother liquor is subjected to a first ultrafiltration treatment to obtain a silver-rich powder concentrate and an ultrafiltration permeate. The silver-rich powder concentrate is then centrifuged to obtain solid silver powder.

[0013] S2. The ultrafiltration permeate obtained in step S1 is adjusted to pH 6.5-7.5 by adding alkali, and then subjected to electrodialysis to obtain desalination solution and nitrate concentrate.

[0014] S3. The desalination solution obtained in step S2 is subjected to a first nanofiltration treatment or a second ultrafiltration treatment to obtain a solution rich in macromolecular organic matter and a solution rich in small molecule organic matter.

[0015] S4. The resulting macromolecular-rich organic solution is subjected to a second nanofiltration or a third ultrafiltration treatment to obtain a dispersant concentrate and nanofiltration or ultrafiltration permeate. The resulting small-molecule-rich organic solution is subjected to reverse osmosis treatment to obtain a composite carbon source concentrate and reverse osmosis permeate.

[0016] Beneficial effects: In the silver powder production mother liquor resource recovery and separation system provided in this application, the silver powder production mother liquor in the concentration tank is circulated through ultrafiltration device I. The concentration of silver powder in the concentration tank gradually increases. When it reaches a certain level, the concentrated slurry in the concentration tank enters a centrifuge to separate and recover silver powder resources. The permeate from ultrafiltration device I enters an adjustment tank to adjust the pH to 6.5-7.5 to convert nitric acid in the water into nitrate. The water after pH adjustment enters an electrodialysis device for treatment to obtain desalination feed and nitrate-rich concentrate. At this time, nitrate resources can be recovered. The desalination feed enters an organic membrane separation device to separate macromolecular organic matter (dispersant) solution and small molecule organic matter (reducing agent) solution. The macromolecular organic matter solution is concentrated by nanofiltration device II or ultrafiltration device III to obtain dispersant concentrate. At this time, macromolecular dispersant resources can be recovered. The small molecule organic matter concentrate obtained by reverse osmosis can be used as a composite carbon source for recovery. This completes the treatment of the mother liquor from silver powder production, enabling the comprehensive recovery and utilization of silver, nitrate, dispersant, and small molecule reducing agent resources in the mother liquor. This not only reduces environmental treatment costs but also creates economic value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the silver powder production mother liquor resource separation and recovery system provided in this application.

[0018] Figure 2 This is a schematic diagram of the silver powder production mother liquor resource separation and recovery system provided in Embodiment 1 of this application.

[0019] Figure 3 This is a schematic diagram of the silver powder production mother liquor resource separation and recovery system provided in Embodiment 2 of this application.

[0020] Figure 4 This is a schematic diagram of the electrodialysis device provided in this application.

[0021] Figure reference numerals: 10. Silver recovery device; 11. Concentration tank; 12. Ultrafiltration device I; 13. Centrifuge; 20. Desalination device; 21. pH adjustment tank; 22. Electrodialysis device; 221. Pure water inlet; 222. Feed liquid inlet; 223. Desalinated feed liquid outlet; 224. Nitrate concentrate outlet; 30. Organic matter membrane sorting device; 31. Nanofiltration device I; 32. Ultrafiltration device II; 40. Reverse osmosis device; 41. First-stage reverse osmosis unit; 42. Second-stage reverse osmosis unit; 50. Concentration device; 51. Nanofiltration device II; 511. First-stage nanofiltration unit; 512. Second-stage nanofiltration unit; 52. Ultrafiltration device III; 521. First-stage ultrafiltration unit; 522. Second-stage ultrafiltration unit; 60. Evaporator; 70. Biochemical treatment device. Detailed Implementation

[0022] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Furthermore, unless otherwise specified, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0023] Please see Figure 1 The silver powder production mother liquor resource recovery and separation system provided in this application includes: a silver recovery device, a desalination device, an organic membrane separation device, a reverse osmosis device, and a concentration device.

[0024] A silver recovery device includes a concentration tank, an ultrafiltration unit I, and a centrifuge. The concentration tank is equipped with an inlet for silver powder production mother liquor, a first outlet, and a second outlet. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration unit I, which is used to retain and separate silver powder from the water. The outlet of the concentrated liquid from the ultrafiltration unit I is connected to the inlet of the concentration tank, and the second outlet of the concentration tank is connected to the inlet of the centrifuge.

[0025] In some specific embodiments, the concentration of the dispersant (macromolecule organic matter, such as PVP, PVA, etc.) in the silver powder production mother liquor is 5000-10000 ppm, such as 5000 ppm, 6000 ppm, 7000 ppm, 8000 ppm, 9000 ppm, 10000 ppm or any value between them, and the concentration of the reducing agent (small molecule organic matter, such as dehydrogenated VC, ethanol, glucose, etc.) is 20000-40000 ppm, such as 20000 ppm, 25000 ppm, etc. 30,000 ppm, 35,000 ppm, 40,000 ppm or any value between them; nitric acid concentration of 10,000 to 20,000 ppm, such as 10,000 ppm, 12,000 ppm, 15,000 ppm, 18,000 ppm, 20,000 ppm or any value between them; silver powder concentration of 5 to 20 ppm, such as 5 ppm, 8 ppm, 10 ppm, 12 ppm, 15 ppm, 18 ppm, 20 ppm or any value between them.

[0026] In some specific embodiments, the silver recovery device may include a homogenization tank, which is used to collect the mother liquor from silver powder production and can regulate the water volume and quality of the treatment system. For example... Figure 2 and Figure 3 As shown, the outlet of the homogenizing tank is connected to the inlet of the thickening tank, and the outlet of the centrifuge's clear liquid is connected to the inlet of the homogenizing tank.

[0027] In some specific embodiments, a circulation pump is installed on the pipeline connecting the first outlet of the concentration tank and the inlet of the ultrafiltration device I. The circulation pump controls the flow velocity of water across the membrane surface in the ultrafiltration device I. The preferred flow velocity is 2 to 5 m / s, such as 2 m / s, 3 m / s, 4 m / s, 5 m / s, or any value between them. This is more conducive to preventing silver powder from depositing on the membrane surface and improving the silver powder recovery efficiency.

[0028] In some specific embodiments, the ultrafiltration membrane used in the ultrafiltration device I is a tubular ultrafiltration membrane, which is less prone to fouling and has higher efficiency. The material of the ultrafiltration membrane in the ultrafiltration device I is preferably at least one of ceramic membrane, polyvinylidene fluoride, and polytetrafluoroethylene. The molecular weight cutoff of the ultrafiltration membrane in the ultrafiltration device I is preferably 100,000 to 200,000 Da, such as 100,000 Da, 120,000 Da, 150,000 Da, 180,000 Da, 200,000 Da, or any value between them. This allows for good retention of silver powder while allowing the permeation of large molecular weight dispersants, thereby improving the recovery rate and purity of the silver powder. The operating pressure is preferably 1 to 5 bar, such as 1 bar, 2 bar, 3 bar, 4 bar, 5 bar, or any value between them.

[0029] The desalination unit includes a pH adjustment tank and an electrodialysis unit. The pH adjustment tank is used to convert nitric acid in water into nitrate by adding alkali. The pH adjustment tank is equipped with an alkali dosing component. The inlet of the pH adjustment tank is connected to the permeate outlet of the ultrafiltration unit I. The electrodialysis unit is equipped with a pure water inlet, a feed liquid inlet, a desalination feed liquid outlet, and a nitrate concentrate outlet. The feed liquid inlet of the electrodialysis unit is connected to the outlet of the pH adjustment tank. In this process, nitric acid in the water is first converted into nitrate by pH adjustment, and then the nitrate is separated from the organic matter in the water by the electrodialysis unit, thereby obtaining a desalination feed liquid and a nitrate concentrate, achieving the recovery of nitric acid resources from the silver powder production mother liquor.

[0030] In some specific embodiments, the electrodialysis device includes an anode, a cathode, and a membrane assembly disposed between the anode and the cathode. The membrane assembly includes M cation exchange membranes and M anion exchange membranes arranged alternately along the direction from the anode to the cathode, where M is an integer greater than or equal to 4, and M can be 4, 6, 8, 10, 12, etc. Membrane channels are formed between adjacent cation exchange membranes and anion exchange membranes. The membrane channel with a cation exchange membrane near the anode and an anion exchange membrane near the cathode is used to transport pure water, while the membrane channel with an anion exchange membrane near the anode and a cation exchange membrane near the cathode is used to transport feed solution. Specifically, when M is 6, such as... Figure 4As shown, one end of the membrane channel used for conveying pure water is connected to the pure water inlet and the other end is connected to the nitrate concentrate outlet. One end of the membrane channel used for conveying the feed liquid is connected to the feed liquid inlet and the other end is connected to the desalination feed liquid outlet.

[0031] Organic membrane separation devices are used to separate desalination liquid into solutions rich in macromolecular organic matter and solutions rich in small molecule organic matter.

[0032] In some specific embodiments, the organic membrane separation device is provided with a desalination liquid inlet and a macromolecular organic matter-rich solution outlet on the interception side, and a small molecule organic matter-rich solution outlet on the permeation side.

[0033] In some specific embodiments, the organic membrane separation device can be any membrane device capable of separating large-molecule organic matter (dispersant) and small-molecule organic matter (reducing agent; the molecular weight of the reducing agent used in the liquid-phase reduction process for producing silver powder is generally below 500 Da) in the desalination solution, preferably nanofiltration device I or ultrafiltration device II. Specifically, the molecular weight cutoff of the nanofiltration membrane in nanofiltration device I is preferably 1000–3000 Da, such as 1000 Da, 1500 Da, 2000 Da, 2500 Da, 3000 Da, or any value between them. The molecular weight cutoff of the ultrafiltration membrane in ultrafiltration device II is preferably 5000–10000 Da, such as 5000 Da, 6000 Da, 7000 Da, 8000 Da, 9000 Da, 10000 Da, or any value between them.

[0034] The reverse osmosis unit has an inlet and a composite carbon source concentrate outlet on its intercept side. The inlet on the intercept side of the reverse osmosis unit is connected to the outlet of the small-molecule organic solution from the organic membrane separation unit. The small-molecule organic solution obtained from the organic membrane separation unit is further concentrated by the reverse osmosis unit, thereby recovering the reducing agent in the silver powder production mother liquor in the form of a low-grade composite carbon source.

[0035] In some specific embodiments, the reverse osmosis device includes N stages of reverse osmosis units, where N can be one, two, or three. The inlet of the first-stage reverse osmosis unit is connected to the outlet of the small-molecule organic solution of the organic membrane separation device. The concentrate outlet of the first-stage reverse osmosis unit is a composite carbon source concentrate outlet. The product water outlet of the first or second-stage reverse osmosis unit is connected to the inlet of the next-stage reverse osmosis unit. The concentrate outlet of the second or third-stage reverse osmosis unit is connected to the inlet of the previous or first-stage reverse osmosis unit.

[0036] Specifically, when N is two, such as Figure 2 and Figure 3As shown, the reverse osmosis unit includes a primary reverse osmosis unit and a secondary reverse osmosis unit. The inlet of the primary reverse osmosis unit is connected to the outlet of the small molecule organic solution of nanofiltration unit I or ultrafiltration unit II. The concentrate outlet of the primary reverse osmosis unit is a composite carbon source concentrate outlet. The product water outlet of the primary reverse osmosis unit is connected to the inlet of the secondary reverse osmosis unit. The concentrate outlet of the secondary reverse osmosis unit is connected to the inlet of the primary reverse osmosis unit. The product water outlet of the secondary reverse osmosis unit collects the product water for further treatment.

[0037] The concentration unit is either nanofiltration unit II or ultrafiltration unit III, with an inlet and a dispersant concentrate outlet on its filtration side. The inlet on the filtration side of the concentration unit is connected to the outlet of the macromolecular organic solution from the organic membrane separation unit. The macromolecular organic solution obtained from the organic membrane separation unit is further concentrated by nanofiltration unit II or ultrafiltration unit III, thereby recovering the dispersant from the silver powder production mother liquor. Since the dispersant does not participate in the reaction during silver powder production, it can be downgraded and sold externally for the production of disinfectants and coatings, thus possessing economic value.

[0038] In some specific embodiments, the nanofiltration device II includes P-stage nanofiltration units, where P can be one, two, or three. The inlet of the first-stage nanofiltration unit is connected to the outlet of the macromolecular organic solution rich in organic matter from the organic membrane separation device. The concentrate outlet of the first-stage nanofiltration unit is the dispersant concentrate outlet. The product water outlet of the first or second-stage nanofiltration unit is connected to the inlet of the next-stage nanofiltration unit. The concentrate outlet of the second or third-stage nanofiltration unit is connected to the inlet of the previous or first-stage nanofiltration unit. The product water outlet of the final-stage nanofiltration unit is connected to the inlet of the reverse osmosis device.

[0039] Specifically, when P is two, such as Figure 2 As shown, nanofiltration unit II includes a primary nanofiltration unit and a secondary nanofiltration unit. The inlet of the primary nanofiltration unit is connected to the outlet of the macromolecular organic solution of nanofiltration unit I. The concentrate outlet of the primary nanofiltration unit is the dispersant concentrate outlet. The product water outlet of the primary nanofiltration unit is connected to the inlet of the secondary nanofiltration unit. The concentrate outlet of the secondary nanofiltration unit is connected to the inlet of the primary nanofiltration unit. The product water outlet of the secondary nanofiltration unit is connected to the inlet of the reverse osmosis unit (primary reverse osmosis unit).

[0040] In some specific embodiments, the molecular weight cutoff of each of the P-level nanofiltration units is preferably 1000 to 3000 Da, such as 1000 Da, 1500 Da, 2000 Da, 2500 Da, 3000 Da or any value between them.

[0041] In some specific embodiments, the ultrafiltration device III includes Q-stage ultrafiltration units, where Q can be one, two, or three. The inlet of the first-stage ultrafiltration unit is connected to the outlet of the macromolecular organic solution of the organic membrane separation device; the concentrate outlet of the first-stage ultrafiltration unit is the dispersant concentrate outlet; the product water outlet of the first or second-stage ultrafiltration unit is connected to the inlet of the next-stage ultrafiltration unit; the concentrate outlet of the second or third-stage ultrafiltration unit is connected to the inlet of the previous or first-stage ultrafiltration unit; and the product water outlet of the final-stage ultrafiltration unit is connected to the inlet of the reverse osmosis device.

[0042] Specifically, when Q is two, such as Figure 3 As shown, the ultrafiltration unit III includes a primary ultrafiltration unit and a secondary ultrafiltration unit. The inlet of the primary ultrafiltration unit is connected to the outlet of the macromolecular organic solution of the ultrafiltration unit II. The concentrate outlet of the primary ultrafiltration unit is the dispersant concentrate outlet. The product water outlet of the primary ultrafiltration unit is connected to the inlet of the secondary ultrafiltration unit. The ultrafiltrate outlet of the secondary nanofiltration unit is connected to the inlet of the primary ultrafiltration unit. The product water outlet of the secondary ultrafiltration unit is connected to the inlet of the reverse osmosis unit (primary reverse osmosis unit).

[0043] In some specific embodiments, the molecular weight cutoff of each Q-stage ultrafiltration unit is independently 5000 to 10000 Da, such as 5000 Da, 6000 Da, 7000 Da, 8000 Da, 9000 Da, 10000 Da or any value between them.

[0044] In some specific embodiments, the system may also include an evaporator and / or a biochemical treatment device. For example... Figure 2 and Figure 3 As shown, the inlet of the evaporator is connected to the outlet of the nitrate concentrate from the electrodialysis unit. Figure 2 and Figure 3 As shown, the inlet of the biochemical treatment device is connected to the condensate outlet of the evaporator and the product water outlet on the permeate side of the reverse osmosis device.

[0045] The method for resource separation and recovery of silver powder production mother liquor provided in this application is carried out in the above-mentioned silver powder production mother liquor resource separation and recovery system, and the method includes the following steps:

[0046] S1. The silver powder production mother liquor is subjected to a first ultrafiltration treatment to obtain a silver-rich powder concentrate and an ultrafiltration permeate. The silver-rich powder concentrate is then centrifuged to obtain solid silver powder.

[0047] S2. The ultrafiltration permeate obtained in step S1 is adjusted to pH 6.5-7.5 by adding alkali, and then subjected to electrodialysis to obtain desalination solution and nitrate concentrate.

[0048] S3. The desalination solution obtained in step S2 is subjected to a first nanofiltration treatment or a second ultrafiltration treatment to obtain a solution rich in macromolecular organic matter and a solution rich in small molecule organic matter.

[0049] S4. The resulting macromolecular-rich organic solution is subjected to a second nanofiltration or a third ultrafiltration treatment to obtain a dispersant concentrate and nanofiltration or ultrafiltration permeate. The resulting small-molecule-rich organic solution is subjected to reverse osmosis treatment to obtain a composite carbon source concentrate and reverse osmosis permeate.

[0050] In some specific embodiments, in step S1, the preferred operating conditions for the first ultrafiltration treatment include: a membrane surface flow rate of 2 to 5 m / s, such as 2 m / s, 3 m / s, 4 m / s, 5 m / s or any value between them; an operating pressure of 1 to 5 bar, such as 1 bar, 2 bar, 3 bar, 4 bar, 5 bar or any value between them; a permeate flux of 100 to 150 LMH, such as 100 LMH, 110 LMH, 120 LMH, 130 LMH, 140 LMH, 150 LMH or any value between them; and a temperature of 25 to 40°C, such as 25°C, 30°C, 35°C, 40°C or any value between them.

[0051] In some specific embodiments, in step S1, the molecular weight cutoff of the ultrafiltration membrane used in the first ultrafiltration treatment is preferably 100,000 to 200,000 Da, such as 100,000 Da, 120,000 Da, 150,000 Da, 180,000 Da, 200,000 Da or any value between them.

[0052] In some specific embodiments, in step S1, the silver powder concentration of the silver-rich concentrate is preferably 150 mg / L or higher, such as 150 mg / L, 200 mg / L, 400 mg / L, 500 mg / L, etc. The silver powder concentration of the ultrafiltration permeate is ≤0.5 mg / L.

[0053] In some specific embodiments, in step S2, the alkali added to adjust the pH can be sodium hydroxide and / or potassium hydroxide.

[0054] In some specific embodiments, in step S2, the nitrate concentration in the desalination solution is preferably below 300 mg / L. The COD concentration in the nitrate concentrate is preferably below 300 mg / L.

[0055] In some specific embodiments, in step S3, the rejection rate of the first nanofiltration treatment or the second ultrafiltration treatment for macromolecular organic matter (dispersant) is ≥99%. The concentration of the dispersant in the resulting solution rich in small molecule organic matter is preferably below 100 ppm.

[0056] In some specific embodiments, in step S3, the operating conditions of the first nanofiltration treatment preferably include: an operating pressure of 10–20 bar, such as 10 bar, 12 bar, 15 bar, 18 bar, 20 bar, or any value between them; a water flux of 15–20 LMH, such as 15 LMH, 16 LMH, 17 LMH, 18 LMH, 19 LMH, 20 LMH, or any value between them; and a temperature of 25–40°C, such as 25°C, 30°C, 35°C, 40°C, or any value between them. In the first nanofiltration treatment, the molecular weight cutoff of the nanofiltration membrane is preferably 1000–3000 Da, such as 1000 Da, 1500 Da, 2000 Da, 2500 Da, 3000 Da, or any value between them.

[0057] In some specific embodiments, in step S3, the operating conditions of the second ultrafiltration treatment preferably include: an operating pressure of 10–20 bar, such as 10 bar, 12 bar, 15 bar, 18 bar, 20 bar, or any value between them; a water flux of 10–30 LMH, such as 10 LMH, 15 LMH, 18 LMH, 20 LMH, 22 LMH, 25 LMH, 30 LMH, or any value between them; and a temperature of 25–40°C, such as 25°C, 30°C, 35°C, 40°C, or any value between them. In the second ultrafiltration treatment, the molecular weight cutoff of the ultrafiltration membrane used is preferably 5000–10000 Da, such as 5000 Da, 6000 Da, 7000 Da, 8000 Da, 9000 Da, 10000 Da, or any value between them.

[0058] In some specific embodiments, step S4 preferably includes a first-stage nanofiltration process and a second-stage nanofiltration process. Specifically, the macromolecular-rich organic solution undergoes a first-stage nanofiltration process to obtain first-stage nanofiltration permeate and a dispersant concentrate; the first-stage nanofiltration permeate undergoes a second-stage nanofiltration process to obtain second-stage nanofiltration permeate and a second-stage nanofiltration concentrate; the second-stage nanofiltration concentrate is refluxed for further first-stage nanofiltration; and the second-stage nanofiltration permeate is used as a stream of water in the reverse osmosis process.

[0059] In some specific embodiments, the operating conditions of the primary nanofiltration treatment in step S4 preferably include: an operating pressure of 20 to 30 bar, such as 20 bar, 22 bar, 25 bar, 28 bar, 30 bar or any value between them; a water flux of 10 to 20 LMH, such as 10 LMH, 12 LMH, 15 LMH, 18 LMH, 20 LMH or any value between them; and a temperature of 25 to 40°C, such as 25°C, 30°C, 35°C, 40°C or any value between them. The preferred operating conditions for the secondary nanofiltration treatment include: an operating pressure of 5–15 bar, such as 5 bar, 8 bar, 10 bar, 12 bar, 15 bar, or any value between them; a water flux of 20–30 LMH, such as 20 LMH, 22 LMH, 25 LMH, 28 LMH, 30 LMH, or any value between them; and a temperature of 25–40°C, such as 25°C, 30°C, 35°C, 40°C, or any value between them. In both the primary and secondary nanofiltration treatments, the molecular weight cutoff of the nanofiltration membranes used is preferably 1000–3000 Da, such as 1000 Da, 1500 Da, 2000 Da, 2500 Da, 3000 Da, or any value between them.

[0060] In some specific embodiments, step S4 preferably includes a first-stage ultrafiltration process and a second-stage ultrafiltration process. Specifically, the macromolecular-rich organic solution undergoes a first-stage ultrafiltration process to obtain first-stage ultrafiltration permeate and a dispersant concentrate; the first-stage ultrafiltration permeate undergoes a second-stage ultrafiltration process to obtain second-stage ultrafiltration permeate and a second-stage ultrafiltration concentrate; the second-stage ultrafiltration concentrate is refluxed for further first-stage ultrafiltration; and the second-stage ultrafiltration permeate is used as a stream of water in the reverse osmosis process.

[0061] In some specific embodiments, the operating conditions of the primary ultrafiltration treatment in step S4 preferably include: an operating pressure of 20 to 30 bar, such as 20 bar, 22 bar, 25 bar, 28 bar, 30 bar or any value between them; a water flux of 5 to 20 LMH, such as 5 LMH, 8 LMH, 10 LMH, 12 LMH, 15 LMH, 18 LMH, 30 LMH or any value between them; and a temperature of 25 to 40°C, such as 25°C, 30°C, 35°C, 40°C or any value between them. The preferred operating conditions for the secondary ultrafiltration treatment include: an operating pressure of 10–25 bar, such as 10 bar, 12 bar, 15 bar, 18 bar, 20 bar, 22 bar, 25 bar, or any value between them; a water flux of 30–50 LMH, such as 30 LMH, 35 LMH, 40 LMH, 45 LMH, 50 LMH, or any value between them; and a temperature of 25–40 °C, such as 25 °C, 30 °C, 35 °C, 40 °C, or any value between them. In both the primary and secondary ultrafiltration treatments, the molecular weight cutoff of the ultrafiltration membranes used is preferably 3000–10000 Da, such as 3000 Da, 4000 Da, 5000 Da, 6000 Da, 8000 Da, 10000 Da, or any value between them.

[0062] In some specific embodiments, step S4 preferably includes a first-stage reverse osmosis treatment and a second-stage reverse osmosis treatment. Specifically, the small-molecule-rich organic solution undergoes first-stage reverse osmosis treatment to obtain first-stage reverse osmosis permeate and first-stage reverse osmosis concentrate (i.e., a composite carbon source concentrate); the first-stage reverse osmosis permeate undergoes second-stage reverse osmosis treatment to obtain second-stage reverse osmosis permeate and second-stage reverse osmosis concentrate; the second-stage reverse osmosis concentrate is refluxed for further first-stage reverse osmosis treatment; and the second-stage reverse osmosis permeate is collected and undergoes biochemical treatment to meet discharge standards.

[0063] In some specific embodiments, in step S4, the conditions for the first-stage reverse osmosis treatment preferably include: an operating pressure of 45–75 bar, such as 45 bar, 50 bar, 55 bar, 60 bar, 65 bar, 70 bar, 75 bar or any value between them; a water flux of 10–20 LMH, such as 10 LMH, 12 LMH, 15 LMH, 18 LMH, 20 LMH or any value between them; and a temperature of 25–40°C, such as 25°C, 30°C, 35°C, 40°C or any value between them. The preferred conditions for the secondary reverse osmosis treatment include: an operating pressure of 10–20 bar, such as 10 bar, 12 bar, 15 bar, 18 bar, 20 bar, or any value between them; a water flux of 20–40 LMH, such as 20 LMH, 25 LMH, 30 LMH, 35 LMH, 40 LMH, or any value between them; and a temperature of 25–40°C, such as 25°C, 30°C, 35°C, 40°C, or any value between them.

[0064] In some specific embodiments, the method may further include an evaporation and concentration process to further concentrate the nitrate concentrate obtained in step S2, yielding nitrate solids (such as sodium nitrate, potassium nitrate, etc.) and evaporation condensate. The evaporation condensate may contain small amounts of COD and total nitrogen, which are treated biochemically to meet emission standards before being discharged.

[0065] In some specific implementations, the method may also include biochemical treatment to treat the reverse osmosis permeate and evaporation condensate to meet discharge standards.

[0066] Furthermore, the terms "Ⅰ", "Ⅱ", "Ⅲ", "first", "second", and "third" are used only for descriptive purposes and should not be construed as special limitations on the structure, quantity, or other properties of technical features.

[0067] The present application will be described in detail below through specific embodiments. These embodiments are intended to explain the present application and should not be construed as limiting it. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0068] In the following embodiments: the electrodialysis device was purchased from Hangzhou Cree Technology Co., Ltd., model CreaDED-Ⅲ; the nanofiltration membrane used in nanofiltration device I was purchased from Xiamen Jiarong Co., Ltd., model AMS-U301 (molecular weight cutoff of 2500 Da); the nanofiltration membrane used in nanofiltration device II was purchased from Xiamen Jiarong Co., Ltd., model UNF604 (molecular weight cutoff of 1000 Da); the ultrafiltration membrane used in ultrafiltration device I was purchased from Xiamen Jiarong Co., Ltd., model MEMOS-C150-08-3000-15.0-FRP (molecular weight cutoff of 100,000 kDa); the ultrafiltration membrane used in ultrafiltration device II was purchased from Xiamen Jiarong Co., Ltd., model UPS010 (molecular weight cutoff of 10000 Da); the ultrafiltration membrane used in ultrafiltration device III was purchased from Xiamen Jiarong Co., Ltd., model UPS005 (molecular weight cutoff of 5000 Da).

[0069] Example 1

[0070] (1) This embodiment is used to illustrate a resource-based separation and recovery system for silver powder production mother liquor, such as Figure 2 As shown, the system includes: a silver recovery unit 10, a desalination unit 20, a nanofiltration unit I 31, a reverse osmosis unit 40, a nanofiltration unit II 51, an evaporator 60, and a biochemical treatment unit 70.

[0071] The silver recovery device includes a homogenization tank 14, a concentration tank 11, an ultrafiltration unit I 12, and a centrifuge 13. The homogenization tank 14 collects the mother liquor from the silver powder production process, and its overflow outlet is connected to the inlet of the concentration tank 11. The first outlet of the concentration tank 11 is connected to the inlet of the ultrafiltration unit I 12 via a circulation pump, and the second outlet of the concentration tank 11 is connected to the inlet of the centrifuge 13. The centrifuged clarified liquid outlet of the centrifuge 13 is connected to the inlet of the homogenization tank 14. The ultrafiltration membrane used in the ultrafiltration unit I 12 is a tubular ultrafiltration membrane made of polyvinylidene fluoride with a molecular weight cutoff of 100,000 Da.

[0072] The desalination unit 20 includes a pH adjustment tank 21 and an electrodialysis unit 22. The pH adjustment tank 21 is equipped with a sodium hydroxide dosing assembly to convert nitric acid in the water into nitrate by adding alkali. The inlet of the pH adjustment tank 21 is connected to the permeate outlet of the ultrafiltration unit I12. The electrodialysis unit 22 is equipped with a pure water inlet 221, a feed solution inlet 222, a desalination feed solution outlet 223, and a nitrate concentrate outlet 224. The feed solution inlet 222 of the electrodialysis unit 22 is connected to the outlet of the pH adjustment tank 21. The electrodialysis unit 22 includes an anode, a cathode, and a membrane assembly disposed between the anode and cathode. The membrane assembly includes three cation exchange membranes and three anion exchange membranes arranged alternately along the direction from the anode to the cathode. Membrane channels are formed between adjacent cation exchange membranes and anion exchange membranes. The membrane channel with a cation exchange membrane near the anode and an anion exchange membrane near the cathode is used to transport pure water. One end of the membrane channel is connected to the pure water inlet 221 and the other end is connected to the nitrate concentrate outlet 224. The membrane channel with an anion exchange membrane near the anode and a cation exchange membrane near the cathode is used to transport feed liquid. One end of the membrane channel is connected to the feed liquid inlet 222 and the other end is connected to the desalination feed liquid outlet 223.

[0073] Evaporator 60 is a double-effect evaporator. Its inlet is connected to the nitrate concentrate outlet 224 of the electrodialysis device 22, and its condensate outlet is connected to the inlet of the biochemical treatment device 70.

[0074] Nanofiltration unit I 31 is used to separate the desalination feed solution into a solution rich in macromolecular organic matter and a solution rich in small molecular weight organic matter. The retrieval side of nanofiltration unit I 31 has a desalination feed solution inlet and a macromolecular organic matter-rich solution outlet, while the permeation side has a small molecular weight organic matter-rich solution outlet. The desalination feed solution inlet on the retrieval side of nanofiltration unit I 31 is connected to the desalination feed solution outlet 223 of electrodialysis unit 22. The nanofiltration membrane in nanofiltration unit I 31 has a molecular weight cutoff of 2500 Da.

[0075] The reverse osmosis unit 40 includes a primary reverse osmosis unit 41 and a secondary reverse osmosis unit 42. The inlet of the primary reverse osmosis unit 41 is connected to the outlet of the small molecule organic solution of the nanofiltration unit I 31. The concentrate outlet of the primary reverse osmosis unit 41 is a composite carbon source concentrate outlet. The product water outlet of the primary reverse osmosis unit 41 is connected to the inlet of the secondary reverse osmosis unit 42. The concentrate outlet of the secondary reverse osmosis unit 42 is connected to the inlet of the primary reverse osmosis unit 41. The product water outlet of the secondary reverse osmosis unit 42 is connected to the inlet of the biochemical treatment unit 70.

[0076] Nanofiltration unit II 51 includes a primary nanofiltration unit 511 and a secondary nanofiltration unit 512. The inlet of the primary nanofiltration unit 511 is connected to the outlet of the macromolecular organic solution of nanofiltration unit I 31. The concentrate outlet of the primary nanofiltration unit 511 is the dispersant concentrate outlet. The product water outlet of the primary nanofiltration unit 511 is connected to the inlet of the secondary nanofiltration unit 512. The concentrate outlet of the secondary nanofiltration unit 512 is connected to the inlet of the primary nanofiltration unit 511. The product water outlet of the secondary nanofiltration unit 512 is connected to the inlet of the reverse osmosis unit 40 (primary reverse osmosis unit 41). The molecular weight cutoff of the nanofiltration membrane in the primary nanofiltration unit 511 is 1000 Da, and the molecular weight cutoff of the nanofiltration membrane in the secondary nanofiltration unit 512 is 1000 Da.

[0077] (2) The method for resource-based separation and recovery of silver powder production mother liquor provided in this embodiment is carried out in the above system. The silver powder production mother liquor has a total silver concentration of 10-15 ppm, a PVP silver powder production mother liquor concentration of 5000 mg / L, a dehydrogenated VC silver powder production mother liquor concentration of 30000 mg / L, and a silver nitrate powder production mother liquor concentration of 15000 mg / L. The specific steps are as follows:

[0078] The 200 t / d silver powder production mother liquor enters the homogenization tank 14 for homogenization and then overflows into the concentration tank 11. It then undergoes a first ultrafiltration treatment (operating temperature 30℃, operating pressure 2 bar, permeate flow rate 120 LMH) to obtain 200 t / d of ultrafiltration permeate (silver powder concentration ≤ 0.5 mg / L). The concentrate is returned to the concentration tank 11 for further first ultrafiltration treatment, thus the theoretical water recovery rate is 100%. When the silver powder concentration in the concentration tank 11 reaches 150 mg / L, the silver-rich concentrate is discharged and centrifuged in the centrifuge 13 to obtain 0.2–0.3 t / d of solid silver powder and centrifuged supernatant. The centrifuged supernatant is returned to the homogenization tank.

[0079] S2. The 200 t / d ultrafiltration permeate obtained in step S1 is adjusted to pH 6.5 with sodium hydroxide, treated by electrodialysis, and then 100 t / d of pure water is added as the draw solution to obtain 275 t / d of desalination feed (sodium nitrate concentration ≦300 mg / L) and 25 t / d of sodium nitrate concentrate (COD ≦300 mg / L). The 25 t / d of sodium nitrate concentrate is then evaporated (first-effect evaporation temperature is 80℃, second-effect evaporation temperature is 90℃) to obtain 3.5 t / d of sodium nitrate solid (water content is about 10%) and 21.5 t / d of evaporation condensate (which is treated by biochemical treatment to meet standards for discharge).

[0080] S3. The 275 t / d desalination solution obtained in step S2 is subjected to the first nanofiltration treatment (operating temperature is 30℃, operating pressure is 20 bar, and permeate flux is 20 LMH) to obtain a 20 t / d solution rich in macromolecular organic matter and a 255 t / d solution rich in small molecule organic matter.

[0081] S4. The resulting 20 t / d high-molecular-weight organic solution is fed into a two-stage DTNF treatment system. First, it undergoes a primary nanofiltration process. The primary nanofiltration permeate is then treated by a secondary nanofiltration process. The secondary nanofiltration concentrate is refluxed back to the primary stage (primary nanofiltration operating temperature: 30℃, operating pressure: 30 bar, permeate flux: 10 LMH; secondary nanofiltration operating temperature: 32℃, operating pressure: 10 bar, permeate flux: 30 LMH). This yields 13.4 t / d of secondary nanofiltration permeate and 6.6 t / d of dispersant concentrate (from the primary nanofiltration concentrate, PVP concentration: 150,000 mg / L, PVP overall recovery rate: greater than 99%). The secondary nanofiltration permeate is then fed into the reverse osmosis system.

[0082] The resulting 255 t / d small molecule organic solution and 13.4 t / d secondary nanofiltration permeate are fed into a two-stage DTRO system for treatment. First, the permeate undergoes primary reverse osmosis treatment, followed by secondary reverse osmosis treatment. The secondary reverse osmosis concentrate is then refluxed for further primary reverse osmosis treatment (primary reverse osmosis operating temperature: 30℃, operating pressure: 65 bar, permeate flux: 15 LMH; secondary reverse osmosis operating temperature: 33℃, operating pressure: 20 bar, permeate flux: 30 LMH). This yields 228.4 t / d of secondary reverse osmosis permeate and 40 t / d of primary reverse osmosis concentrate (i.e., composite carbon source concentrate with a dehydrogenated VC concentration of 150,000 mg / L). The secondary reverse osmosis permeate is collected and undergoes biochemical treatment to meet discharge standards.

[0083] After treatment, 200 t / d of silver powder production mother liquor can yield 0.2-0.3 t / d of solid silver powder, 3.5 t / d of solid sodium nitrate, 6.6 t / d of PVP concentrate (PVP concentration of 150,000 mg / L), 40 t / d of composite carbon source concentrate (dehydrogenated VC concentration of 150,000 mg / L), and 228.4 t / d of treated compliant effluent.

[0084] Example 2

[0085] (1) This embodiment is used to illustrate a system and method for the resource-based separation and recovery of silver powder production mother liquor, such as Figure 3 As shown, the system includes: a silver recovery device 10, a desalination device 20, an ultrafiltration device II 32, a reverse osmosis device 40, an ultrafiltration device III 52, an evaporator 60, and a biochemical treatment device 70.

[0086] Ultrafiltration unit II 32 is used to separate the desalination feed solution into a solution rich in macromolecular organic matter and a solution rich in small molecular weight organic matter. The retrieval side of ultrafiltration unit II 32 is equipped with a desalination feed solution inlet and a macromolecular organic matter-rich solution outlet, while the permeation side is equipped with a small molecular weight organic matter-rich solution outlet. The desalination feed solution inlet on the retrieval side of ultrafiltration unit II 32 is connected to the desalination feed solution outlet 223 of electrodialysis unit 22. The molecular weight cutoff of the ultrafiltration membrane in ultrafiltration unit II 32 is 10000 Da.

[0087] Ultrafiltration unit III 52 includes a primary ultrafiltration unit 521 and a secondary ultrafiltration unit 522. The inlet of the primary ultrafiltration unit 521 is connected to the outlet of the macromolecular organic solution of ultrafiltration unit II 32. The concentrate outlet of the primary ultrafiltration unit 521 is the dispersant concentrate outlet. The product water outlet of the primary ultrafiltration unit 521 is connected to the inlet of the secondary ultrafiltration unit 522. The concentrate outlet of the secondary ultrafiltration unit 522 is connected to the inlet of the primary ultrafiltration unit 521. The product water outlet of the secondary ultrafiltration unit 522 is connected to the inlet of the reverse osmosis unit 40 (primary reverse osmosis unit 41). The molecular weight cutoff of the ultrafiltration membrane in the primary ultrafiltration unit 521 is 5000 Da, and the molecular weight cutoff of the ultrafiltration membrane in the secondary ultrafiltration unit 522 is 5000 Da.

[0088] The remaining structure and connections are the same as the system provided in Example 1.

[0089] (2) The method for resource-based separation and recovery of silver powder production mother liquor provided in this embodiment is carried out in the above system. The silver powder production mother liquor has a total silver concentration of 10-15 ppm, a PVP silver powder production mother liquor concentration of 5000 mg / L, a dehydrogenated VC silver powder production mother liquor concentration of 30000 mg / L, and a silver nitrate powder production mother liquor concentration of 15000 mg / L. The specific steps are as follows:

[0090] The 200 t / d silver powder production mother liquor enters the homogenization tank 14 for homogenization and then overflows into the concentration tank 11. It then undergoes a first ultrafiltration treatment (operating temperature 30℃, operating pressure 2 bar, permeate flow rate 120 LMH) to obtain 200 t / d of ultrafiltration permeate (silver powder concentration ≤ 0.5 mg / L). The concentrate is returned to the concentration tank 11 for further first ultrafiltration treatment, thus the theoretical water recovery rate is 100%. When the silver powder concentration in the concentration tank 11 reaches 150 mg / L, the silver-rich concentrate is discharged and centrifuged in the centrifuge 13 to obtain 0.2–0.3 t / d of solid silver powder and centrifuged supernatant. The centrifuged supernatant is returned to the homogenization tank.

[0091] S2. The 200 t / d ultrafiltration permeate obtained in step S1 is adjusted to pH 6.5 with sodium hydroxide, treated by electrodialysis, and then 100 t / d of pure water is added as the draw solution to obtain 275 t / d desalination solution (sodium nitrate concentration ≤300 mg / L) and 25 t / d sodium nitrate concentrate (COD ≤300 mg / L). The 25 t / d sodium nitrate concentrate is then evaporated (first-effect evaporation temperature is 80℃, second-effect evaporation temperature is 90℃) to obtain 3.5 t / d sodium nitrate solid (water content is about 10%) and 21.5 t / d evaporation condensate (which is treated by biochemical treatment to meet the standards for discharge).

[0092] S3. The 275 t / d desalination solution obtained in step S2 is subjected to a second ultrafiltration treatment (operating temperature is 30℃, operating pressure is 15 bar, and permeate flux is 20 LMH) to obtain a 20 t / d solution rich in macromolecular organic matter and a 255 t / d solution rich in small molecule organic matter.

[0093] S4. The resulting 20 t / d high-molecular-weight organic solution is fed into a two-stage DTUF system for treatment. First, it undergoes primary ultrafiltration. The primary ultrafiltration permeate is then treated with secondary ultrafiltration. The secondary ultrafiltration concentrate is refluxed back to the primary ultrafiltration front end (primary ultrafiltration operating temperature: 30℃, operating pressure: 25 bar, permeate flux: 15 LMH; secondary ultrafiltration operating temperature: 32℃, operating pressure: 10 bar, permeate flux: 40 LMH). This yields 14 t / d of secondary ultrafiltration permeate and 6 t / d of dispersant concentrate (from primary ultrafiltration concentrate, PVP concentration: 150,000 mg / L, overall PVP recovery rate: greater than 90%). The secondary ultrafiltration permeate is then fed into reverse osmosis treatment.

[0094] The resulting 255 t / d small molecule organic solution and 14 t / d secondary ultrafiltration permeate are fed into a two-stage DTRO system for treatment. First, the permeate undergoes primary reverse osmosis treatment, followed by secondary reverse osmosis treatment. The secondary reverse osmosis concentrate is then refluxed for further primary reverse osmosis treatment (primary operating temperature: 30℃, operating pressure: 65 bar, permeate flux: 15 LMH; secondary operating temperature: 33℃, operating pressure: 20 bar, permeate flux: 30 LMH). This yields 229 t / d of secondary reverse osmosis permeate and 40 t / d of primary reverse osmosis concentrate (i.e., composite carbon source concentrate with a dehydrogenated VC concentration of 150,000 mg / L). The secondary reverse osmosis permeate is collected and undergoes biochemical treatment to meet discharge standards.

[0095] After treatment, 200 t / d of silver powder production mother liquor can yield 0.2-0.3 t / d of solid silver powder, 3.5 t / d of solid sodium nitrate, 6 t / d of PVP concentrate (PVP concentration of 150,000 mg / L), 40 t / d of composite carbon source concentrate (dehydrogenated VC concentration of 150,000 mg / L), and 229 t / d of treated compliant effluent.

[0096] 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 without departing from the principles and spirit of this application.

Claims

1. A system for the resource-based separation and recovery of mother liquor from silver powder production, characterized in that, The system includes: a silver recovery unit, a desalination unit, an organic matter membrane separation unit, a reverse osmosis unit, and a concentration unit; The silver recovery device includes a concentration tank, an ultrafiltration device I, and a centrifuge. The concentration tank is equipped with an inlet for silver powder production mother liquor, a first outlet, and a second outlet. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration device I. The ultrafiltration device I is used to retain and separate silver powder from the water. The outlet of the concentrated liquid from the ultrafiltration device I is connected to the inlet of the concentration tank. The second outlet of the concentration tank is connected to the inlet of the centrifuge. The ultrafiltration membrane in the ultrafiltration device I has a molecular weight cutoff of 100,000 to 200,000 Da and an operating pressure of 1 to 5 bar. The desalination device includes a pH adjustment tank and an electrodialysis device. The inlet of the pH adjustment tank is connected to the permeate outlet of the ultrafiltration device I. The electrodialysis device is equipped with a pure water inlet, a raw material liquid inlet, a desalination material liquid outlet, and a nitrate concentrate outlet. The raw material liquid inlet of the electrodialysis device is connected to the outlet of the pH adjustment tank. The organic membrane separation device is used to separate the desalination liquid into a solution rich in macromolecular organic matter and a solution rich in small molecule organic matter; the organic membrane separation device is a nanofiltration device I or an ultrafiltration device II, wherein the molecular weight cutoff of the nanofiltration membrane in the nanofiltration device I is 1000~3000 Da, and the molecular weight cutoff of the ultrafiltration membrane in the ultrafiltration device II is 5000~10000 Da. The reverse osmosis device is provided with an inlet and a composite carbon source concentrate outlet on the interception side. The inlet of the reverse osmosis device on the interception side is connected to the outlet of the small molecule organic solution of the organic membrane separation device. The concentration device is a nanofiltration device II or an ultrafiltration device III, with an inlet and a dispersant concentrate outlet on its interception side. The inlet on the interception side of the concentration device is connected to the outlet of the macromolecular organic solution of the organic membrane separation device.

2. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The silver recovery device includes a homogenization tank for collecting mother liquor from silver powder production; the outlet of the homogenization tank is connected to the inlet of the concentration tank, and the centrifugal clarified liquid outlet of the centrifuge is connected to the inlet of the homogenization tank; a circulation pump is installed on the pipeline connecting the first outlet of the concentration tank and the inlet of the ultrafiltration device I.

3. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The ultrafiltration membrane used in the ultrafiltration device I is a tubular ultrafiltration membrane; the material of the ultrafiltration membrane in the ultrafiltration device I is selected from at least one of ceramic membrane, polyvinylidene fluoride, and polytetrafluoroethylene.

4. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The electrodialysis device includes an anode, a cathode, and a membrane assembly disposed between the anode and the cathode. The membrane assembly includes M cation exchange membranes and M anion exchange membranes arranged alternately along the direction from the anode to the cathode, where M is an integer greater than or equal to 4. Membrane channels are formed between adjacent cation exchange membranes and anion exchange membranes, wherein the membrane channel with a cation exchange membrane near the anode side and an anion exchange membrane near the cathode side is used to transport pure water, and the membrane channel with an anion exchange membrane near the anode side and a cation exchange membrane near the cathode side is used to transport feed liquid.

5. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The organic membrane separation device is provided with a desalination liquid inlet and a macromolecular organic matter-rich solution outlet on the interception side, and a small molecule organic matter-rich solution outlet on the permeation side.

6. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The reverse osmosis device includes N stages of reverse osmosis units, where N is any integer from one to three; The inlet of the first-stage reverse osmosis unit is connected to the outlet of the small-molecule organic solution of the organic membrane separation device. The concentrate outlet of the first-stage reverse osmosis unit is the outlet of the composite carbon source concentrate. The product water outlet of the first-stage or second-stage reverse osmosis unit is connected to the inlet of the next-stage reverse osmosis unit. The concentrate outlet of the second-stage or third-stage reverse osmosis unit is connected to the inlet of the previous-stage or first-stage reverse osmosis unit.

7. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The nanofiltration device II includes P-stage nanofiltration units, where P is any integer from one to three; The inlet of the first-stage nanofiltration unit is connected to the outlet of the macromolecular organic solution of the organic membrane separation device. The outlet of the concentrate of the first-stage nanofiltration unit is the outlet of the dispersant concentrate. The outlet of the product water of the first-stage or second-stage nanofiltration unit is connected to the inlet of the next-stage nanofiltration unit. The outlet of the concentrate of the second-stage or third-stage nanofiltration unit is connected to the inlet of the previous-stage or first-stage nanofiltration unit. The outlet of the product water of the final-stage nanofiltration unit is connected to the inlet of the reverse osmosis device. The molecular weight cutoff of each of the P-level nanofiltration units is independently 1000~3000 Da.

8. The silver powder production mother liquor resource recovery and separation system according to claim 1, characterized in that, The ultrafiltration device III includes a Q-stage ultrafiltration unit, where Q is any integer from one to three; The inlet of the first-stage ultrafiltration unit is connected to the outlet of the macromolecular organic solution of the organic membrane separation device. The outlet of the concentrate of the first-stage ultrafiltration unit is the outlet of the dispersant concentrate. The outlet of the product water of the first-stage or second-stage ultrafiltration unit is connected to the inlet of the next-stage ultrafiltration unit. The outlet of the concentrate of the second-stage or third-stage ultrafiltration unit is connected to the inlet of the previous-stage or first-stage ultrafiltration unit. The outlet of the product water of the final-stage ultrafiltration unit is connected to the inlet of the reverse osmosis device. The molecular weight cutoff of each of the Q-stage ultrafiltration units is independently 5000~10000 Da.

9. The silver powder production mother liquor resource separation and recovery system according to claim 1, characterized in that, The system also includes an evaporator and / or a biochemical treatment unit; The inlet of the evaporator is connected to the outlet of the nitrate concentrate of the electrodialysis unit; The inlet of the biochemical treatment device is connected to the condensate outlet of the evaporator and the permeate outlet of the reverse osmosis device.

10. A method for the resource-based separation and recovery of mother liquor from silver powder production, characterized in that, The method is carried out in the silver powder production mother liquor resource recovery and separation system according to any one of claims 1 to 9, and includes the following steps: S1. The silver powder production mother liquor is subjected to a first ultrafiltration treatment to obtain a silver-rich powder concentrate and an ultrafiltration permeate. The silver-rich powder concentrate is then centrifuged to obtain solid silver powder. S2. The ultrafiltration permeate obtained in step S1 is adjusted to pH 6.5-7.5 by adding alkali, and then subjected to electrodialysis to obtain desalination solution and nitrate concentrate. S3. The desalination solution obtained in step S2 is subjected to a first nanofiltration treatment or a second ultrafiltration treatment to obtain a solution rich in macromolecular organic matter and a solution rich in small molecule organic matter. S4. The resulting macromolecular-rich organic solution is subjected to a second nanofiltration or a third ultrafiltration treatment to obtain a dispersant concentrate and nanofiltration permeate or ultrafiltration permeate. The resulting small-molecule-rich organic solution is subjected to reverse osmosis treatment to obtain a composite carbon source concentrate and reverse osmosis permeate.

Images