A treatment system for recovering ultrafine metal powder from a liquid phase

Abstract

The utility model belongs to nanometer material recovery technical field, concretely relates to a kind of processing system of superfine metal powder from liquid phase recovery. The processing system includes homogeneous pool, concentration tank, ultrafiltration filtering device, centrifugal device. In the processing system provided in the utility model, mother liquor enters concentration tank after being pumped into ultrafiltration filtering device by first circulating pump and is treated, and concentrated solution containing metal powder is returned to concentration tank, so the concentration of metal powder in concentration tank is constantly increasing, when reaching a certain degree, liquid in concentration tank enters centrifugal device and is separated to obtain metal powder and centrifugal clear liquid, the recovery rate of superfine metal powder in liquid phase is ≧99%, and only ultrafiltration filtering is discharged in the whole process Permeate, and the total silver content of permeate is ≦0.1mg / L, water recovery rate is ≧99%, compared with natural sedimentation or other filtration+drying recovery method, metal recovery rate is high, and the efficiency of centrifugal separation is higher, and operating cost is lower.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterial recycling technology, specifically relating to a processing system for recovering ultrafine metal powder from a liquid phase. Background Technology

[0002] In industrial production, it is common to recover ultrafine metal powders from the liquid phase. For example, in the process of preparing silver powder by liquid-phase reduction, silver nitrate is reduced by vitamin C to produce ultrafine silver powder. The particle size of the silver powder is usually 500-1000 nm. After centrifugation to recover most of the silver powder, trace amounts of silver powder will still remain in the liquid phase system. This residue will be discharged into the wastewater system with the silver powder mother liquor, resulting in the loss of silver resources and heavy metal pollution issues in downstream environmental protection.

[0003] Common solid-liquid separation processes often suffer from incomplete separation when separating ultrafine metal powders from the liquid phase. The main reasons are as follows: Ultrafine metal powders are usually very light, and their natural sedimentation effect is poor, requiring a very long sedimentation residence time. During this time, metals may dissolve back into the liquid phase, making metal recovery more difficult and resulting in poor recovery efficiency. At the same time, because the particle size of ultrafine metal powders reaches the nanometer scale (e.g., the particle size of silver powder is often below 1μm), while the filtration accuracy of common plate and frame filter cloths and cartridge filters is above 1μm, common filters cannot achieve efficient interception. Moreover, the recovery of precious metals on the filter element is difficult and usually requires calcination for recovery.

[0004] Therefore, there is a need to develop a rapid ultrafine metal powder recovery system to recover residual trace amounts of silver powder, such as from silver powder mother liquor, thereby reducing the pressure on downstream environmental treatment while recovering metal resources. Utility Model Content

[0005] The purpose of this invention is to solve the problem that existing methods for recovering ultrafine metal powder from liquid phases are difficult to achieve efficient metal powder recovery due to the small particle size and low content of the metal powder, resulting in resource waste and heavy metal emissions. The invention provides a rapid treatment system for recovering ultrafine metal powder from liquid phases, with a total silver content in the treated water of ≤0.1 mg / L.

[0006] Specifically, the processing system for recovering ultrafine metal powder from the liquid phase provided by this utility model includes a homogenizing tank, a concentration tank, an ultrafiltration device, and a centrifuge device. The homogenizing tank is provided with an inlet and an outlet for the mother liquor containing ultrafine metal powder. The inlet of the concentration tank is connected to the outlet of the homogenizing tank. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration device via a first circulation pump. The concentrated liquid outlet of the ultrafiltration device is connected to the inlet of the concentration tank. The second outlet of the concentration tank is connected to the inlet of the centrifuge device. The centrifuged clear liquid outlet of the centrifuge device is connected to the inlet of the homogenizing tank.

[0007] In some specific embodiments, the homogenizing tank is provided with an overflow outlet, which is connected to the inlet of the thickening tank.

[0008] In some specific embodiments, the first outlet of the concentration tank is located above the side wall of the concentration tank, and the second outlet of the concentration tank is located at the bottom of the concentration tank.

[0009] In some specific embodiments, the concentration tank is equipped with a metal powder content monitor to monitor the concentration of metal powder in the concentration tank and thereby determine the time point at which the concentrate in the concentration tank enters the centrifuge device.

[0010] In some specific embodiments, the ultrafiltration device employs a tubular ultrafiltration membrane.

[0011] In some specific embodiments, the ultrafiltration membrane in the ultrafiltration device is made of polyvinylidene fluoride or polytetrafluoroethylene.

[0012] In some specific embodiments, the ultrafiltration device has a membrane molecular weight cutoff of 50,000 to 150,000 Da and an operating pressure of 2 to 5 bar.

[0013] In some specific embodiments, a second circulation pump is provided on the pipeline connecting the concentrate outlet of the ultrafiltration device and the inlet of the concentration tank, for returning the concentrate to the concentration tank to increase the content of metal powder in the water.

[0014] In some specific embodiments, a third circulation pump is provided on the pipeline connecting the second outlet of the concentration tank and the inlet of the centrifuge device, for sending the concentrated slurry in the concentration tank into the centrifuge device for separation processing.

[0015] In some specific embodiments, the processing system further includes a clearing tank for collecting the permeate produced by the ultrafiltration device.

[0016] Beneficial Effects: In the treatment system provided by this utility model, the mother liquor containing ultrafine metal powder first enters the homogenization tank, which plays a role in regulating the water volume and water quality of the treatment system. Then, the mother liquor enters the concentration tank and is pumped into the ultrafiltration device by the first circulation pump for treatment. The action of the first circulation pump regulates the cross-flow filtration speed on the membrane surface of the ultrafiltration device, so that the metal powder will not be deposited on the membrane surface, thereby improving the metal recovery rate. Then, the concentrated liquid containing metal powder is returned to the concentration tank, so the concentration of metal powder in the concentration tank continuously increases. When it reaches a certain level, the concentrated slurry in the concentration tank enters the centrifuge device to separate the metal powder and the centrifuged clear liquid. The centrifuged clear liquid has some metal powder residue and is returned to the homogenization tank for further treatment. Thus, the recovery of ultrafine metal powder in the liquid phase is completed, with a metal recovery rate of ≥99%. In the entire process, only the permeate is discharged during ultrafiltration, and the total silver content of the permeate is ≤0.1mg / L. The water recovery rate is ≥99%. Compared with natural sedimentation or other filtration + drying recovery methods, the metal recovery rate is high, and the centrifugal separation efficiency is higher and the operating cost is lower. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a processing system for recovering ultrafine metal powder from a liquid phase, provided in a specific embodiment of this utility model.

[0018] Reference numerals in the attached drawings: 1. Homogenization tank; 2. Concentration tank; 3. Ultrafiltration device; 4. Centrifugation device; 5. Clarified liquid tank; 61. First circulation pump; 62. Second circulation pump; 63. Third circulation pump. Detailed Implementation

[0019] Although this disclosure can readily be embodied in various forms, only some specific embodiments are shown in the accompanying drawings and will be described in detail in this specification. It is also understood that this specification should be regarded as an exemplary illustration of the principles of this disclosure and is not intended to limit the disclosure to what is described herein.

[0020] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of this disclosure, and does not imply that every embodiment of this disclosure must have the described feature. Furthermore, it should be noted that this specification describes many features. While certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0021] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) used to explain the structure and movement of the various elements of this disclosure are relative rather than absolute. These descriptions are appropriate when these elements are in the positions shown in the drawings. If the descriptions of the positions of these elements change, these directional indications also change accordingly.

[0022] The present invention provides a processing system for recovering ultrafine metal powder from a liquid phase, comprising: a homogenizing tank, a concentration tank, an ultrafiltration device, and a centrifuge device. The homogenizing tank is provided with an inlet and an outlet for a mother liquor containing ultrafine metal powder. The inlet of the concentration tank is connected to the outlet of the homogenizing tank. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration device via a first circulating pump. The concentrated liquid outlet of the ultrafiltration device is connected to the inlet of the concentration tank. The permeate outlet of the ultrafiltration device is connected to the inlet of a downstream environmental treatment device. The second outlet of the concentration tank is connected to the inlet of the centrifuge device. The centrifuged clarified liquid outlet of the centrifuge device is connected to the inlet of the homogenizing tank.

[0023] The processing system provided by this utility model is suitable for processing the recovery of different types of ultrafine metal powders, such as recovering high-value metals like silver powder and copper powder from liquid phase reduction production mother liquor. It can even achieve a high metal recovery rate for mother liquor with very low metal powder content or mother liquor with residual trace metal powder that has already been recovered once.

[0024] In this invention, the homogenizing tank functions to regulate the water volume and quality of the treatment system, ensuring its stable operation. The homogenizing tank is equipped with an overflow outlet, which is connected to the inlet of the concentration tank. The mother liquor containing ultrafine metal powder entering the homogenizing tank flows into the concentration tank through the overflow outlet. In the concentration tank, the ultrafine metal powder also exhibits some natural settling; its entry via overflow has minimal impact on the concentration tank.

[0025] In this utility model, the first outlet of the concentration tank is located above the side wall of the concentration tank, and the second outlet of the concentration tank is located at the bottom of the concentration tank.

[0026] In this invention, the concentration tank is equipped with a metal powder content monitor to monitor the concentration of metal powder in the concentration tank and determine the opening time of the second outlet of the concentration tank accordingly. As the concentrate from the ultrafiltration device continuously returns to the concentration tank for circulation filtration, the concentration of metal powder in the concentration tank continuously increases. When the concentration of metal powder reaches a certain level as monitored by the metal powder content monitor, it can be discharged through the second outlet and enter the centrifuge for separation. Preferably, when the concentration of metal powder in the concentration tank reaches 400-500 mg / L, it can enter the centrifuge for processing. At this point, the recovery efficiency is high. If the metal powder concentration is too low, the separation efficiency is also low. If the metal powder concentration is too high, the metal powder is prone to adhere to the membrane in the ultrafiltration device, reducing the metal recovery rate.

[0027] In this invention, the ultrafiltration device preferably uses a tubular ultrafiltration membrane, which has higher retention efficiency and is less prone to clogging.

[0028] In this invention, the ultrafiltration membrane in the ultrafiltration device is preferably made of polyvinylidene fluoride and / or polytetrafluoroethylene. Compared with ceramic membranes, organic membranes such as polyvinylidene fluoride or polytetrafluoroethylene are less prone to pore clogging and have a higher retention rate.

[0029] In this invention, the molecular weight cutoff of the membrane in the ultrafiltration device is preferably 5 to 150,000 Da, such as 50,000 Da, 60,000 Da, 70,000 Da, 80,000 Da, 90,000 Da, 100,000 Da, 120,000 Da, 150,000 Da or any value between them; the operating pressure is preferably 2 to 5 bar, such as 2 bar, 3 bar, 4 bar, 5 bar or any value between them.

[0030] In this invention, a second circulation pump is provided on the pipeline connecting the concentrated liquid outlet of the ultrafiltration device and the inlet of the concentration tank, which is used to return the concentrated liquid to the concentration tank to increase the content of metal powder in the water.

[0031] In this invention, a third circulation pump is provided on the pipeline connecting the second outlet of the concentration tank and the inlet of the centrifuge device, which is used to send the concentrated slurry in the concentration tank into the centrifuge device for separation processing.

[0032] In this invention, the processing system further includes a clear liquid tank for collecting the permeate produced by the ultrafiltration device. The total silver content of the permeate is ≤0.1 mg / L. In practical applications, subsequent processing can be determined based on the specific conditions of the permeate. For example, after the silver powder mother liquor from the liquid-phase reduction method is processed by the system provided by this invention, the resulting permeate still contains reducing agents, dispersants, and other substances, requiring further processing in a subsequent environmental protection system.

[0033] The present invention will be described in detail below through specific embodiments. These embodiments are intended to explain the present invention and should not be construed as limiting it. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0034] Example 1

[0035] This embodiment illustrates a processing system for recovering ultrafine metal powder from a liquid phase, referring to... Figure 1 The treatment system includes a homogenization tank 1, a concentration tank 2, an ultrafiltration device 3, a centrifuge device 4, and a clarified liquid tank 5. The homogenization tank 1 is equipped with an inlet for the mother liquor containing ultrafine metal powder and an overflow outlet. The overflow outlet is connected to the inlet of the concentration tank 2. The volume of the homogenization tank 1 is 100 m³. 3 The first outlet of the concentration tank 2 is located above the side wall of the concentration tank 2 and is connected to the inlet of the ultrafiltration device 3 via the first circulation pump 61. The second outlet of the concentration tank 2 is located at the bottom of the concentration tank 2 and is connected to the inlet of the centrifugal device via the third circulation pump 63. The volume of the concentration tank 2 is 50m³. 3 The concentration tank 2 is equipped with a metal powder content monitor to monitor the concentration of metal powder in the concentration tank and determine the timing of the concentrated liquid entering the centrifuge. The outlet of the concentrated liquid of the ultrafiltration device 3 is connected to the inlet of the concentration tank 2 via the second circulation pump 62. The outlet of the permeate of the ultrafiltration device 3 is connected to the inlet of the clear liquid tank 5. The membrane module of the ultrafiltration device 3 is a tubular ultrafiltration membrane made of polyvinylidene fluoride (PVDF), with a molecular weight cutoff of 100,000 Da and an operating pressure of 2–5 bar. The outlet of the clear liquid of the centrifuge 4 is connected to the inlet of the homogenization tank 1.

[0036] The treatment system provided in this embodiment is used to treat silver powder mother liquor with a discharge rate of approximately 200 t / d and a total silver content of 10-15 mg / L. The specific process is as follows:

[0037] 20m 3 A silver powder mother liquor (total silver content of 10-15 mg / L) is pumped into homogenization tank 1 (tank volume of 100 m³ / h) by a feed pump. 3 Then it overflows into thickening tank 2 (tank volume is 50m³). 3 Then, the first circulation pump 61 pumps the material into the ultrafiltration unit 3 (tubular ultrafiltration membrane module, PVDF organic membrane, molecular weight cutoff of 100,000 Da), with an operating pressure of 2-5 Bar, an operating temperature of 30-40℃, a corresponding cross-flow velocity of 3-4 m / s (to delay the deposition of precious metal powder on the membrane surface), and a circulation flow rate of 150-250 m³ / s. 3 / h, permeate production is 20m³ 3 The total silver content of the permeate is ≤0.1 mg / L. The concentrated liquid obtained from ultrafiltration is recycled to the concentration tank, where the silver powder concentration is gradually increased. When the total silver content in the concentration tank reaches 400-500 mg / L, the silver powder slurry discharged from the concentration tank enters the centrifuge device 4 to separate the silver powder. The resulting centrifuged clear liquid contains a certain concentration of silver powder (silver concentration 10-15 mg / L), which can be returned to the homogenization tank 1 to be mixed with the silver powder mother liquor, and then re-enter the concentration tank 2 and ultrafiltration device 3 for recovery. Thus, the silver recovery rate of this system is ≥99%, and the water recovery rate is ≥99%.

[0038] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A processing system for recovering ultrafine metal powders from a liquid phase, characterized by, The processing system includes a homogenizing tank, a concentration tank, an ultrafiltration device, and a centrifuge device. The homogenizing tank is equipped with an inlet and an outlet for a mother liquor containing ultrafine metal powder. The inlet of the concentration tank is connected to the outlet of the homogenizing tank. The first outlet of the concentration tank is connected to the inlet of the ultrafiltration device via a first circulation pump. The concentrated liquid outlet of the ultrafiltration device is connected to the inlet of the concentration tank. The second outlet of the concentration tank is connected to the inlet of the centrifuge device. The centrifuged clear liquid outlet of the centrifuge device is connected to the inlet of the homogenizing tank.

2. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, characterized by, The homogenizing tank is provided with an overflow outlet, which is connected to the inlet of the thickening tank.

3. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein The first outlet of the concentration tank is located above the side wall of the concentration tank, and the second outlet of the concentration tank is located at the bottom of the concentration tank.

4. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein The concentration tank is equipped with a metal powder content monitor, which is used to monitor the concentration of metal powder in the concentration tank and determine the time point when the concentrated liquid in the concentration tank enters the centrifuge device.

5. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein The ultrafiltration device uses a tubular ultrafiltration membrane.

6. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein The ultrafiltration membrane in the ultrafiltration device is made of polyvinylidene fluoride and / or polytetrafluoroethylene.

7. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein The ultrafiltration device has a membrane molecular weight cutoff of 50,000 to 150,000 Da and an operating pressure of 2 to 5 bar.

8. The processing system for recovering ultra-fine metal powders from a liquid phase according to claim 1, wherein A second circulation pump is installed on the pipeline connecting the concentrated liquid outlet of the ultrafiltration device and the inlet of the concentration tank, which is used to return the concentrated liquid to the concentration tank to increase the content of metal powder in the water.

9. The process system for recovering ultrafine metal powder from a liquid phase according to claim 1, wherein A third circulation pump is installed on the pipeline connecting the second outlet of the concentration tank and the inlet of the centrifuge device, which is used to send the concentrated slurry in the concentration tank into the centrifuge device for separation.

10. The processing system for recovering ultra-fine metal powders from a liquid phase according to claim 1, wherein The processing system also includes a clear liquid tank for collecting the permeate produced by the ultrafiltration device.

Images