Precoat filtration after-filter aid recovery system

Abstract

The utility model discloses a precoat filtration postfilter aid recovery system belongs to precoat filtration's filter aid recovery field. Precoat filtration postfilter aid recovery system includes: ultrasonic dispersion equipment, including stirring chamber, be equipped with agitator in the stirring chamber, the stirring chamber connects ultrasonic vibrator, the stirring chamber side wall is equipped with clear water inlet, and the multi -specific gravity suspension liquid separation device is connected with ultrasonic dispersion equipment, and the suspension liquid is separated initially, and the coarse separation pool is connected with the multi -specific gravity suspension liquid separation device, is used for storing the liquid containing small specific gravity particle liquid that is introduced from the multi -specific gravity suspension liquid separation device, and the centrifugal equipment is connected with the coarse separation pool. The utility model provides precoat filtration postfilter aid recovery system, can separate filter aid with the particle, and through the multi -specific gravity suspension liquid separation device carries out the initial separation, and further separates again through the centrifugal equipment, and removes the oil part in the coarse separation pool, makes the filter aid purity higher finally, and the reuse rate is high.

Description

Technical Field

[0001] This utility model relates to the field of pre-coated filters and filter aid recycling, and particularly to the field of filter aid recovery after pre-coated filtration. Background Technology

[0002] In semiconductor manufacturing, the demand for the recycling of fluids such as cutting fluids and polishing fluids is increasing. The key to recycling these fluids lies in filtering out fine particulate matter such as silicon, silicon carbide, alumina, and aluminum nitride generated during processing, ensuring the purity of the working fluid. Most of these particles are smaller than 10 micrometers. While methods such as cake filtration can achieve high filtration throughput and efficiency initially, the small particle size quickly clogs the filter cake and the filter pores on the substrate, causing a rapid decrease in throughput and necessitating more frequent cake removal and substrate surface cleaning. Furthermore, in typical operating environments, the used fluid may contain oils such as guide rail oil. Although the concentration is low, these oils adhere to the surface of the particles, increasing their viscosity and making them difficult to remove completely from the substrate during cleaning. This directly reduces the filterable area and increases the frequency of substrate replacement. Using filter aids can solve these problems. Using diatomaceous earth, cellulose, and other similar materials as filter aids can effectively improve the filtration accuracy and throughput of the filtration system, and is a widely used process. Before filtration, the filter aid forms a filter cake with a small and uniform filter diameter, making it difficult for fine particles to enter the filter pores and clog them. In addition, diatomaceous earth and cellulose are more likely to adsorb oils, which reduces the oil content of the substrate and prevents it from adhering to the substrate.

[0003] Filter aids offer numerous advantages in semiconductor waste recycling, but several issues remain to be addressed. A certain dosage is required to ensure optimal performance; typically, a 3-5 mm pre-coating is needed on the substrate to maintain a filter aid to waste particle ratio of 2:1 to 5:1 in the discharged filter cake. This significantly increases the amount of filter cake and consequently, subsequent treatment costs. This is difficult to achieve under the current context of emission reduction and energy conservation efforts. Furthermore, the cost of filter aids is 4000-4500 RMB / ton, and using them directly as filter cake further increases processing costs.

[0004] To solve the above problems, it is necessary to recycle the filter aid in the filter cake. On the one hand, this reduces the amount of filter cake, and on the other hand, the recycled filter aid can be reused in filtration, reducing the amount of filter aid to be purchased and saving filtration process costs.

[0005] Existing filter aid recycling technologies are mostly used for the reuse of filter aids in wine filtration. This process does not involve oil removal or separating impurities from the filter aid; it is basically a simple solid-liquid separation followed by filtration and drying. However, it cannot completely remove impurities to obtain a relatively pure filter aid. Summary of the Invention

[0006] To address the issue of waste filter aids generated during the filtration of silicon powder and ceramic powder in the semiconductor industry using pre-coated filter aids, this invention provides a pre-coated filter aid recovery system. This system can separate the filter aid from the filtered particles, perform initial separation using a multi-density suspension separator, further separate the particles using a centrifuge, and remove oil in a coarse separation tank, resulting in a higher purity and higher reuse rate of the final filter aid.

[0007] Based on the above problems, the proposed solution is as follows:

[0008] A pre-coated filter aid recovery system, the system comprising:

[0009] An ultrasonic dispersion device includes a stirring chamber, in which a stirrer is provided; the stirring chamber is connected to an ultrasonic vibrator; and a clean water inlet is provided on the side wall of the stirring chamber.

[0010] A multi-density suspension separation device is connected to the ultrasonic dispersion device to perform preliminary separation of the suspension;

[0011] The coarse separation tank, connected to the multi-density suspension separation device, is used to store liquid containing low-density particles introduced from the multi-density suspension separation device.

[0012] A centrifuge is connected to the coarse separation tank.

[0013] Preferably, the stirring chamber is provided with a receiving hopper and a suspension outlet at the bottom; the stirrer is provided with a rotating shaft and stirring teeth on the rotating shaft.

[0014] Preferably, a rotating blade is provided in the stirring chamber relative to the clean water inlet, and the rotating blade is located below the receiving hopper; a support frame is provided on the side wall of the stirring chamber, and the rotating blade is rotatably connected to the support frame.

[0015] Preferably, the multi-specific-gravity suspension separation device includes:

[0016] The inner swirling chamber is equipped with a first inlet pipe; a first outlet pipe is provided at the top; and a high-density particle limiting device is provided at the bottom of the inner swirling chamber.

[0017] The outer swirling cavity is provided with a second liquid inlet pipe; the upper end of the inner swirling cavity extends out of the outer swirling cavity;

[0018] The bottom of the outer swirling cavity is provided with a second liquid outlet pipe; the first liquid inlet pipe is connected to an ultrasonic dispersion device; a first pump and a first valve are connected between the first liquid inlet pipe and the ultrasonic dispersion device.

[0019] Preferably, the high-density particle limiting device is a perforated plate filter screen, which is disc-shaped and connected to a shaft at one end. An elastic element is sleeved on the shaft. A guide seat is provided at the bottom of the outer swirling cavity. The shaft passes through the guide seat, slides relative to the guide seat, and is sealed together.

[0020] Preferably, the centrifuge includes a rotating drum and a scraper, the rotating drum being connected to a liquid inlet and the liquid inlet being connected to a coarse separation tank; the centrifuge also includes a liquid outlet connected to the coarse separation tank; and the centrifuge also includes a discharge outlet.

[0021] Preferably, the coarse separation tank is connected to a multi-density suspension separation device; a second pump and a second valve are provided between the coarse separation tank and the multi-density suspension separation device.

[0022] A pre-coated filter aid recovery system, the system comprising:

[0023] An ultrasonic dispersion device includes a stirring chamber, in which a stirrer is provided; the stirring chamber is connected to an ultrasonic vibrator; and a clean water inlet is provided on the side wall of the stirring chamber.

[0024] A density gravity separator, connected to the ultrasonic dispersion device, performs preliminary separation of the suspension;

[0025] The coarse separation tank, connected to the multi-density suspension separation device, is used to store liquid containing low-density particles introduced from the multi-density suspension separation device.

[0026] Centrifuge equipment is connected to the coarse separation tank;

[0027] The density gravity separator includes:

[0028] The tank body has a height-to-diameter ratio of not less than 3.5 and is equipped with internal baffles, the baffles being filter screens;

[0029] The tank has a third inlet pipe on its side wall, a third outlet pipe at the top of the tank, and a fourth inlet pipe at the bottom of the tank; located on the filter screen, the tank has a concentrated liquid discharge pipe on its side wall.

[0030] The third inlet pipe is connected to the ultrasonic dispersion device; the third outlet pipe is connected to the coarse separation tank.

[0031] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0032] 1. First, the filter residue is dispersed by an ultrasonic dispersion device, then preliminarily separated by a multi-density suspension separator, further separated by a centrifuge, and the oil is removed in a coarse separation tank, so that the final filter aid has higher purity and higher reuse rate.

[0033] 2. The multi-density suspension separation device introduces multi-density suspension through the first inlet pipe and leads out liquid with low particulate matter content through the second inlet pipe. They are introduced by swirling flow and collide at the bottom of the inner swirling chamber. The continuous introduction of liquid containing low-density particles repeatedly washes the high-density particles, allowing the waste residue to further separate from the pores of the filter aid.

[0034] 3. The liquid flow entering from the outer vortex chamber first spirals down to the bottom, where the liquid flow velocity is the largest. When it passes through the aperture of the perforated plate filter screen, cavitation occurs, breaking out the oil in the filter residue. Subsequently, the liquid flow decelerates and rises, carrying oil and low-density particles out of the inner vortex chamber. In the coarse separation tank, the floating oil is removed by the overflow tank or oil removal equipment. The filter aid oil and impurities finally collected by the centrifuge equipment are reduced to a minimum.

[0035] 4. Using a density-gravity separator, liquid containing high-density particles is introduced through the third inlet pipe, while liquid with relatively low particle content is introduced through the fourth inlet pipe at the bottom. The two liquid flows converge tangentially, and the particles are lifted by the impact water flow. The particles with lower density are lifted a greater distance and flow out of the outlet with the water flow, while the particles with higher density cannot flow out due to the smaller lifting distance and remain in the tank. This method can effectively remove waste residue from the filter aid and recover the filter aid to a minimum. Attached Figure Description

[0036] Figure 1 This is a system flow diagram for the filter aid recovery system.

[0037] Figure 2 This is a structural flow diagram of the filter aid recovery system in Example 1.

[0038] Figure 3 To Figure 2 A magnified view of part P.

[0039] Figure 4 This is a structural flow diagram of the filter aid recovery system in Example 2.

[0040] In the diagram: Ultrasonic dispersion device 1, stirring chamber 10, receiving hopper 100, clear water inlet 101, suspension outlet 102, support frame 103, stirrer 11, power unit 110, rotating shaft 111, ultrasonic transducer 12, rotating blade 13, rotating shaft 130; Multi-density suspension separation device 2, inner vortex chamber 20, first inlet pipe 200, first outlet pipe 201, outer vortex chamber 21, second inlet pipe 210, second outlet pipe 211, guide seat 212, large... Specific gravity particle limiting device 22, perforated plate filter screen 220, elastic element 221, shaft 222, third liquid inlet pipe 23, concentrated liquid discharge pipe 24, partition plate 25, third liquid outlet pipe 26, fourth liquid inlet pipe 27, centrifuge equipment 3, liquid inlet 30, liquid outlet 31, rotating drum 32, scraper device 33, coarse separation tank 4, overflow tank 40, first pump 50, second pump 51, first valve 60, second valve 61, jet ejector 7, filter 8, slag receiving car 9, filtrate tank 90, slag receiving trough 91. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0042] Example:

[0043] like Figure 4 The filter equipment includes a filter 8 and a slag receiving cart 9. The slag receiving cart includes a slag receiving trough 91 and a filtrate tank 90. ​​The filtrate tank 90 is located below the slag receiving trough 91. The slag receiving trough 91 has a bucket-shaped structure that tapers from top to bottom. Hooks are provided around the slag receiving ton bag for fixing the slag receiving ton bag. The slag receiving ton bag filters the liquid-containing filter residue discharged from the filter. The filtrate enters the filtrate tank 90, and the residue remaining above the ton bag is relatively dry filter residue.

[0044] In this application, a high-density suspension refers to a suspension containing solid particles of two or more densities; a high-density suspension refers to a suspension containing particles of high density; a low-density suspension refers to a suspension containing particles of low density; high-density particles refer to particles of high density; and low-density particles refer to particles of low density.

[0045] like Figure 1 As shown, a filter aid recovery system includes, in sequence, an ultrasonic dispersion device, a multi-density suspension separation device, a coarse separation tank, and a centrifuge device; the centrifuge device is connected to the coarse separation tank; the multi-density suspension separation device is provided with a concentrated liquid discharge port for discharging high-density particulate slag; the centrifuge device is provided with a light material discharge port for discharging the filter aid and drying and recovering the filter aid.

[0046] like Figure 2The filter residue is transported to the ultrasonic dispersion device 1 via a slag receiving trolley. The filter residue in the ton bag is poured into the receiving hopper 100 of the ultrasonic dispersion device. The ultrasonic dispersion device 1 includes a stirring chamber 10, a receiving hopper 100 on the stirring chamber 10, and a stirrer 11 inside the stirring chamber 100. The stirrer 11 includes a rotating shaft 111, and a plurality of stirring teeth are provided on the rotating shaft. The stirring teeth have tips that gradually taper outward from the rotating shaft. One end of the central shaft extends out of the stirring chamber 1 and is connected to the power unit 110. The other end is connected to a bushing set on the inner wall of the stirring chamber 1. The stirring chamber is provided with a clean water inlet 101. An ultrasonic transducer 12 is also provided at the bottom of the stirring chamber 10. A suspension outlet 102 is provided at the bottom of the stirring chamber 10.

[0047] like Figure 2 The suspension outlet 102 is connected to the multi-density suspension separation device 2. A first pump 50 and a first valve 60 are connected between the suspension outlet 102 and the multi-density suspension separation device 2. The multi-density suspension separation device 2 includes an inner swirling chamber 20 and an outer swirling chamber 21. The inner swirling chamber 20 is provided with a first inlet pipe 200, and the outer swirling chamber 21 is provided with a second inlet pipe 210. The first inlet pipe 200 is used to introduce a suspension containing high density particles, and the second inlet pipe 210 is used to introduce a liquid with low particle content. The inner swirling chamber 20 is located inside the outer swirling chamber 21, with its upper end extending out of the outer swirling chamber 21. The first inlet pipe 200 is located outside the outer swirling chamber 21. A high-density particle limiting device is provided at the bottom of the inner swirling chamber 20. A second outlet pipe 211 is provided at the bottom of the outer swirling chamber 21 for discharging concentrated liquid containing high-density particles. Figure 3 The high-density particle limiting device is a perforated plate filter screen 220, which is disc-shaped with a threaded connection hole in the middle and a shaft 222 at the end for connection. An elastic element 221 is sleeved on the shaft 222. A guide seat 212 is also provided at the bottom of the outer swirling cavity 21. The shaft 222 passes through the guide seat 212 and slides relative to the guide seat 212 and is sealed. A first outlet pipe 201 is provided above the inner swirling cavity 20 for discharging low-density suspension.

[0048] Low-density suspensions include: diatomaceous earth and cellulose with particle sizes greater than 25 micrometers, and particulate matter with particle sizes less than 5 micrometers. For example... Figure 2The first outlet pipe 201 connects to the coarse separation tank 4, which in turn connects to the centrifuge 3. In this embodiment, the centrifuge 3 is a scraper centrifuge, which contains a rotating drum 32 and a scraper device 33. After the centrifuge reaches its rated speed, the initially separated liquid is fed through the inlet 30. The material passes through the inlet 30 and the distribution pipe to the distribution plate, where it receives sufficient centrifugal force and is thrown to the inner wall of the rotating drum 32. Under the action of centrifugal force, the liquid is filtered out through the filter screen on the inner wall of the rotating drum. The liquid is discharged from the outlet 31 through the bottom collection tank, which connects to the coarse separation tank 4. When the weight (or volume) of the filter cake reaches the rated loading weight (or capacity) of the machine, the feed valve is closed, and the centrifuge continues to run at high speed. When the separation requirements are met, the main unit slows down to 5 rpm. The scraper device 33 operates according to the prescribed procedure to scrape the material. The material passes through the discharge hole of the rotating drum, through the discharge hopper of the bottom plate, and falls onto the receiving plate or conveyor belt, completing one working cycle.

[0049] At 2500-3000 rpm, diatomaceous earth and cellulose move to the inner wall of the centrifuge drum and are then discharged as dry material from the outlet. The liquid with low particle content after circulating centrifugation in the coarse separation tank 4 is pressurized by the second pump 51 and reused as an impact water flow.

[0050] Using the multi-density suspension separation device 2, the mixture to be separated is pressurized and introduced through the first inlet pipe 200. The high-density particles sink to the bottom of the inner swirling chamber 20 and are held by the bottom perforated plate filter screen 220. The liquid with low particle content is introduced through the second inlet pipe 210 and enters through the outer swirling chamber 21, reaching the bottom of the chamber and impacting the perforated plate filter screen. Because the perforated plate filter screen has a small pore size, it can generate a certain cavitation effect. The cavitation effect can further separate the light filter aid from the waste residue and maximize the recovery of the filter aid. In addition, the cavitation effect can also demulsify and precipitate the oil in the liquid.

[0051] The low-density particle suspension initially separated by the high-density suspension separator 2 is introduced into the coarse separation tank 4, which is also equipped with an overflow tank 40. Since the liquid containing low-density particles also contains oil, floating oil and some scum are generated on the surface of the liquid in the coarse separation tank 4. The scum and floating oil are collected through the overflow tank 40. The liquid after oil removal is introduced into the centrifuge 3. The filter aid separated by the centrifuge 3 is relatively clean, so subsequent cleaning of the filter aid is unnecessary.

[0052] The operation mode of the filter aid recovery system in Example 1:

[0053] S1. Add the waste residue containing the filter aid to the ultrasonic dispersion equipment, and simultaneously introduce clean water to stir the waste residue. At the same time, use the ultrasonic waves to vibrate and separate the waste residue from the pores of the filter aid. The ultrasonic dispersion equipment is equipped with a stirrer, which uses stirring teeth with pointed tips to break up the filter residue. At the same time, an ultrasonic transducer is provided at the bottom of the stirring chamber to perform ultrasonic vibration treatment on the solid-liquid mixture in the stirring chamber.

[0054] S2. The ultrasonically dispersed multi-density suspension is introduced into the multi-density suspension separation device and is pressurized into the inner vortex chamber from the first inlet pipe. Through vortex separation, the liquid containing small specific gravity particles is discharged to the coarse separation tank. In the coarse separation tank, the oil in the liquid containing small specific gravity particles can be separated and removed from the liquid by surface skimming or oil removal device.

[0055] S3. The oil-removed suspension in the coarse separation tank is introduced into a centrifuge. The centrifuge circulates and centrifuges the coarse separation tank to minimize the solid content. The filter aid forms a filter cake inside the centrifuge drum, which is scraped off by a scraper and collected.

[0056] S4. The liquid with relatively low particle content in the coarse separation tank is reintroduced into the multi-density suspension separation device. It is pressurized and pumped into the outer vortex chamber through the second inlet pipe. The liquid flows down spirally to the bottom of the chamber, impacting the bottom perforated plate filter screen, further washing the high-density particles on the filter screen, and further separating the waste residue from the filter aid pores. The liquid containing low-density particles continues to be discharged from the first outlet pipe. The liquid flow entering from the outer vortex chamber first spirals down to the bottom, where the liquid flow velocity is the maximum. It is guided upward by the guide seat and cavitation occurs when it passes through the small holes of the perforated plate filter screen, breaking the oil in the filter residue and separating it. Then the liquid flow decelerates and rises, carrying oil and low-density particles, and is discharged from the inner vortex chamber.

[0057] S5. The remaining high-density particles in the multi-density suspension separation device are lifted by applying a certain force to the perforated plate filter screen. The high-density particles flow out from the channel between the perforated plate filter screen and the inner swirling chamber and are finally discharged through the second outlet pipe.

[0058] Example 2:

[0059] The ultrasonic dispersion device 1 is equipped with a receiving hopper 100, below which is a rotating blade 13. A clean water inlet 101 is positioned opposite the rotating blade 13. The rotating blade is mounted on a rotating shaft 130, and a support frame 103 is located below the clean water inlet 101. The rotating shaft 130 and the support frame 103 are rotatably connected. When filter residue falls from the receiving hopper onto the rotating blade 13, tap water or pure water at a certain pressure is introduced. The water impacts the blade, causing it to rotate and stir, accelerating the mixing of the tap water and filter residue. Simultaneously, an ultrasonic vibration rod 14 is installed in the dispersion chamber. Small clumps of the suspension are further dispersed into small particles under the action of sound waves generated by the ultrasonic generator. Diatomaceous earth, as a pre-coating material, is porous. Under pressure, some of the material to be filtered enters the pores of the diatomaceous earth, making it difficult to separate the diatomaceous earth from the waste. However, the cavitation effect generated by the ultrasonic vibration can detach the waste from the pores of the diatomaceous earth.

[0060] In this embodiment, a density gravity separator replaces the multi-density suspension separation device 2. The density gravity separator includes a tank with a height and diameter of not less than 3.5 mm. A third inlet pipe 23 is provided on the tank. The tank interior contains a baffle 25, which is a filter screen with pores smaller than the particle size of the high-density particles. A concentrate discharge pipe 24 is located on the filter screen. A third outlet pipe 26 is located at the top of the tank, and a fourth inlet pipe 27 is located at the bottom. When the liquid containing multi-density particles enters through the third inlet pipe 23, it tangentially intersects with the impact water flow entering through the fourth inlet pipe 27. The particles are lifted by the impact water flow. The particles with lower density are lifted a greater distance and flow out through the third outlet pipe 26 with the water flow. The particles with higher density cannot flow out due to the smaller lifting distance and remain in the tank. Since the actual density of silicon, silicon carbide, alumina, and aluminum nitride is between 2.3 and 3.3 g / cm³... 3 Diatomaceous earth and cellulose have a concentration of 0.25-0.40 g / cm³. 3 This utilizes the density difference between the filter aid and the filtered particles to initially separate them in the liquid flowing out from the third outlet pipe 26. The heavier particles are ultimately discharged through the concentrate outlet pipe 24.

[0061] The working method of the filter aid recovery system in Example 2.

[0062] S1. Add the waste residue containing the filter aid to the ultrasonic dispersion equipment, stir the waste residue, and at the same time use the ultrasonic vibration to make the waste residue separate from the pores of the filter aid.

[0063] S2. The ultrasonically dispersed multi-density suspension is introduced into the density gravity separator through the third inlet pipe, while a liquid with relatively low particulate matter content is introduced through the fourth inlet pipe at the bottom. The two liquid flows converge tangentially, and the particles are lifted by the impact water flow. The particles with lower specific gravity are lifted a greater distance and are carried out of the outlet with the water flow, while the particles with higher specific gravity cannot flow out due to the smaller lifting distance and remain in the tank. The liquid containing low specific gravity particles is discharged from the third outlet pipe to the coarse separation tank. In the coarse separation tank, the oil in the liquid containing low specific gravity particles is separated and removed by surface skimming or oil removal devices.

[0064] S3. The oil-removed suspension in the coarse separation tank is introduced into a centrifuge. The coarse separation tank is circulated and centrifuged to minimize the solid content. The filter aid forms a filter cake inside the centrifuge drum and is finally scraped off by a scraper and collected.

[0065] S4. The liquid with relatively low particle content in the coarse separation tank is introduced into the density gravity separator again through the fourth inlet pipe. The fourth inlet pipe is connected to the density gravity separator by an ejector to impact the high-density particles in the density gravity separator, further separating the waste residue from the filter aid pores. The liquid containing low-density particles continues to be discharged from the third outlet pipe.

[0066] S5. The liquid containing the remaining high-density particles in the density gravity separator is eventually discharged through the concentrate drain pipe.

[0067] The above are merely specific embodiments of this utility model, but the technical features of this utility model are not limited thereto. Any simple changes, equivalent substitutions, or modifications made based on this utility model to solve essentially the same technical problems and achieve essentially the same technical effects are all covered within the protection scope of this utility model.

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