A method for preparing a foam ceramic filter based on flocking technology

Abstract

The present invention relates to the technical field of foam ceramic filters, and proposes a preparation method of a foam ceramic filter based on a flocking process, comprising the following steps: S1, flocking cotton wool onto the sponge to obtain a flocked sponge; S2, first coating the main slurry onto the flocked sponge, air-drying to obtain a primary slurry sponge, then spraying the slurry onto the primary slurry sponge, and finally air-drying to obtain the filter sponge; S3, sintering the filter sponge in a staged heating manner to obtain a foam ceramic filter. The present invention first flocks cotton wool onto the sponge, and then performs slurry coating and sintering operations on the sponge, which not only makes it easier for the slurry to be hung on the flocking sponge, thereby improving the processing efficiency of the foam ceramic filter and reducing the processing cost of the foam ceramic filter, but also makes the connecting ribs of the flocking sponge uniform in thickness, and creates fine pores on the surface of the foam ceramic filter, thereby improving the through-porosity and overall performance of the foam ceramic filter.

Description

Technical Field

[0001] The invention relates to the technical field of foam ceramic filters, and in particular to a preparation method of a foam ceramic filter based on a flocking process. Background Art

[0002] Foam ceramic filters are commonly used filtering equipment in the casting process. Their main function is to filter impurities in molten aluminum, molten iron, and molten steel. At the same time, the molten metal encounters resistance when passing through the foam ceramic filter, so that the flow rate of the molten metal is more evenly distributed over the entire filter cross-section, avoiding the turbulent flow caused by the molten metal directly impacting the mold cavity or excessive local flow rate.

[0003] Foam ceramic filters can be prepared using a variety of methods, including organic foam impregnation, foaming, sol-gel, pore-forming agent addition, and 3D printing. The organic foam impregnation method, which does not require complex equipment and process conditions, is highly feasible for both large-scale production and laboratory research. Furthermore, the entire preparation process consumes relatively low energy and does not require extreme conditions such as high temperature and high pressure, thereby reducing production costs and improving the product's market competitiveness.

[0004] For example, patent publication CN118993763A discloses a method for recycling waste chromium corundum to produce a multi-layered ceramic foam filter. This method involves sequentially impregnating soft polyurethane foam with a first slurry and a second slurry, followed by sintering and cooling to produce the ceramic foam filter. However, polyurethane foam is first foamed longitudinally in a long foaming tank, and then blasted with hydrogen and oxygen to create a three-dimensional, porous sponge. Due to limitations in the foaming and blasting processes, achieving uniform thickness in the sponge's connecting ribs is difficult, resulting in difficulty in slurry attachment and affecting the filtration performance of the ceramic foam filter. Summary of the Invention

[0005] In view of this, the present invention proposes a preparation method of a foam ceramic filter based on a flocking process, which can improve the uniformity of the sponge connecting ribs and ensure the overall performance of the foam ceramic filter.

[0006] The technical solution of the present invention is implemented as follows: The present invention provides a preparation method of a foam ceramic filter based on a flocking process, comprising the following steps: S1, spraying flocking glue on a sponge, flocking cotton wool onto the sponge, and obtaining a flocked sponge after drying and cutting; S2, first coating the main slurry on the flocking sponge, air-drying to obtain a primary slurry sponge, then spraying the spray slurry on the primary slurry sponge, and allowing the spray slurry to cover the primary slurry sponge, and finally air-drying to obtain the filter sponge, wherein the components of the main slurry include magnesium-stabilized zirconia, zirconium oxide, polyvinyl alcohol, alumina, preservatives, defoaming agents, dispersants and microsilica powder, and the components of the spray slurry include polyvinyl alcohol, monoclinic zirconia, mullite, alumina and microsilica powder; S3, first drying the filter sponge at a constant temperature, and then sintering the filter sponge by a staged heating method to obtain a foam ceramic filter.

[0007] Based on the above technical solution, preferably, the main slurry is composed of 280-320 parts of magnesium-stabilized zirconia, 180-220 parts of 140-160 mesh zirconia, 90-110 parts of 90-110 mesh zirconia, 110-130 parts of polyvinyl alcohol, 16-24 parts of 90-110 mesh alumina, 2-4 parts of preservative, 2-4 parts of defoaming agent, 4-8 parts of dispersant and 16-24 parts of microsilica powder.

[0008] More preferably, the composition of the spraying is 140-180 parts of polyvinyl alcohol, 180-220 parts of 280-320 mesh monoclinic zirconia, 25-35 parts of 180-220 mesh mullite sand, 35-45 parts of 90-110 mesh alumina and 16-24 parts of microsilica powder.

[0009] On the basis of the above technical solution, preferably, the viscosity of the main slurry is 2200-2400 MPa·s, and the viscosity of the spraying is 80-120 MPa·s.

[0010] On the basis of the above technical solution, preferably, the bulk density difference between the primary sponge and the flocking sponge is 0.25-0.35 g / cm 3 .

[0011] On the basis of the above technical solution, preferably, in step S2, the main slurry is coated on the flocking sponge by roller pressing.

[0012] On the basis of the above technical solution, preferably, in step S1, the amount of the flocking glue is 40-60 g / cm 2 , the length of the cotton wool is 0.3mm-0.8mm.

[0013] On the basis of the above technical solution, preferably, in step S3, the drying temperature of the filter sponge is 130-150°C.

[0014] More preferably, in step S3, the temperature range of the stage heating is 0-1650° C., and the sintering time is 20-22 hours.

[0015] On the basis of the above technical solution, preferably, the method further includes S4, performing an appearance inspection on the foam ceramic filter and removing defective products.

[0016] The method for preparing a foam ceramic filter based on flocking technology of the present invention has the following beneficial effects compared with the prior art:

[0017] (1) By first flocking cotton wool onto the sponge and then performing slurry coating and sintering operations on the sponge, not only can the slurry be more easily coated on the flocked sponge, thereby improving the processing efficiency of the foam ceramic filter and reducing the processing cost of the foam ceramic filter, but also the thickness of the connecting ribs of the flocked sponge can be made uniform, and fine pores can be created on the surface of the foam ceramic filter, thereby improving the through-porosity and overall performance of the foam ceramic filter.

[0018] (2) By setting the slurry to include main slurry and spray slurry, the uneven position of sponge slurry can be repaired and the slag shedding rate of the foam filter can be reduced. By adding monoclinic zirconia and mullite sand to the spray slurry and adjusting the amount of dispersant, the processing quality and efficiency of the foam ceramic filter can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 The present invention discloses a surface morphology of a sponge in a method for preparing a foam ceramic filter based on a flocking process.

[0021] Figure 2 The present invention discloses a surface morphology of a flocking sponge in a method for preparing a foam ceramic filter based on a flocking process.

[0022] Figure 3 The present invention discloses a surface morphology of a disc-shaped foam ceramic filter prepared by a method for preparing a foam ceramic filter based on a flocking process.

[0023] Figure 4The present invention discloses a surface morphology of a square sheet-shaped foam ceramic filter prepared by a method for preparing a foam ceramic filter based on a flocking process.

[0024] Figure 5 This is the surface morphology of the disc-shaped foam ceramic filter prepared in the prior art.

[0025] Figure 6 This is the surface morphology of the square sheet-shaped foam ceramic filter prepared in the prior art. DETAILED DESCRIPTION

[0026] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Ceramic foam filters are commonly used in the casting process, primarily for filtering impurities from molten aluminum, molten iron, and molten steel, and ensuring a steady flow of the cast metal. Ceramic foam filters primarily utilize two filtration mechanisms: adsorption and physical barrier. In the steel casting industry, since the casting temperature of molten steel typically ranges from 1500-1750°C, filters with high heat resistance and the ability to withstand high thermal pressure are required. Zirconia filters are commonly used in the industry.

[0028] The present invention provides a method for preparing a foam ceramic filter based on a flocking process, comprising the following steps:

[0029] S1. Material Preparation: Select a polyurethane sponge with appropriate pore size and porosity as the base material based on the desired specifications and porosity of the foam ceramic filter. The sponge should have between 10 and 100 pores per inch and a porosity above 90%, ensuring high filtration efficiency and throughput.

[0030] Place the sponge in an aqueous solution containing an appropriate amount of surfactant and perform ultrasonic cleaning for 15-30 minutes to remove impurities such as oil, dust, etc. on the surface of the sponge. The surfactant can be sodium dodecylbenzene sulfonate, and its concentration is controlled at 0.5%-1%.

[0031] Rinse the cleaned sponge with deionized water and dry it in an oven at 60-80°C for 2-4 hours until completely dry. Cut the dried sponge into the appropriate size and shape as needed. Ensure the edges of the sponge are neat during cutting to avoid breakage or deformation.

[0032] Spray flocking glue on both sides of the sponge, fix the glue-coated sponge on a mobile tooling, and pass the sponge through the flocking window of the flocking machine; at this time, the cotton wool is charged by the high-voltage electric field of the flocking machine, and is attracted and firmly adhered to the sponge coated with flocking glue, completing the flocking process.

[0033] The flocked sponge is dried to solidify the flocking adhesive. Drying methods include natural drying, hot air drying, and infrared drying. Natural drying takes a long time but is less expensive, while hot air drying and infrared drying are faster and more efficient. The drying temperature and time are determined by the type of flocking adhesive and product requirements. Generally, the drying temperature is between 60-150°C, and the drying time ranges from a few minutes to several dozen minutes.

[0034] The dried sponge is punched and cut to obtain a flocking sponge of fixed size. The size of the flocking sponge is the same as the size of the foam ceramic filter to be processed.

[0035] S2, slurry application: select appropriate slurry according to the working conditions of the foam ceramic filter to be processed, apply the slurry evenly on the flocking sponge, and use an air drying line to air dry the flocking sponge after slurry application to obtain a filter sponge.

[0036] S3, sintering: firstly, the filter sponge is dried at a constant temperature, and then the filter sponge is sintered by increasing the temperature in stages, so that a sintering reaction occurs between the ceramic particles to form a firm structure, thereby obtaining the desired foam ceramic filter.

[0037] S4, Post-Processing: The sintered ceramic foam filters undergo a visual inspection to remove defects such as cracks and deformation. Performance tests, such as porosity, compressive strength, and filtration efficiency, are also conducted to ensure product quality meets requirements. Qualified ceramic foam filters are packaged using plastic film or cartons to prevent damage during transportation and storage.

[0038] Compared with the existing technology, this preparation method adds flocking technology, such as Figure 2 As shown, cotton wool is implanted on the connecting ribs of the flocking sponge, and each cotton wool root stands upright on the surface of the connecting ribs.

[0039] First, the flocking process thickens the originally thin connecting ribs of the sponge, especially the connecting ribs located at the edge of the sponge, which not only strengthens the overall structural strength of the foam ceramic filter, but also improves the porosity and overall quality of the foam ceramic filter.

[0040] Secondly, the flocking sponge has a larger surface area, making it easier for the slurry to hang on the flocking sponge. This not only reduces the slurry's requirements for glue and aggregate particle size, effectively solving problems such as insufficient slurry hanging and high processing costs, but also makes it easier to produce thicker slurry ribs. In scenarios where the molten steel temperature is high and the casting time is long, the foam ceramic filter processed using this preparation method has better filtering effect and filtering strength.

[0041] Finally, the flocking process causes a lot of cotton wool to form on the surface of the foam ceramic filter after sintering. At this time, the foam ceramic filter prepared by this process has three-layer filtering function. The first layer of filtering function is the filtering holes of the foam ceramic filter itself, which can filter impurities with larger particle sizes. The second layer of filtering function is the gaps between the materials accumulated in the filtering holes of the foam ceramic filter, which can filter impurities with smaller particle sizes. The third layer of filtering function is the blind holes on the surface of the foam ceramic filter, which can absorb impurities with extremely small particle sizes in molten steel. The mutual cooperation of the three layers of filtering functions can provide the foam ceramic filter with more reliable filtering performance.

[0042] In some embodiments, the amount of flocking glue used is 40-60 g / cm 2 The length of the cotton wool is 0.3mm-0.8mm, and the bulk density difference between the primary sponge and the flocking sponge is 0.25-0.35g / cm 3 , preferably 0.3 g / cm 3 , in order to prepare foam ceramic filters with better performance.

[0043] In step S2, the slurry includes main slurry and spray slurry. When the flocking sponge is coated with slurry, it is preferably coated with slurry by rolling, that is, the main slurry is first coated on the roller of the roller press, and then the flocking sponge is rolled by the roller to coat the main slurry on the roller on the flocking sponge, thereby achieving the effect of coating the main slurry on the flocking sponge. The flocking sponge coated with the main slurry can be air-dried to obtain a primary slurry sponge; by using the rolling method to coat the slurry, the amount of main slurry on the primary slurry sponge can be accurately controlled, and the consistency of each primary slurry sponge can be improved, thereby effectively improving the processing accuracy of the foam ceramic filter.

[0044] After the primary slurry sponge is prepared, the slurry is sprayed on the primary slurry sponge and the slurry is covered by the slurry. Finally, the filter sponge is obtained by air drying, and the foam ceramic filter is obtained by subsequent drying and sintering operations.

[0045] There are two layers of slurry on the filter sponge, both of which are melted and boiled with polyvinyl alcohol and water, and transferred to a high-speed disperser for ball milling and uniform dispersion, so that the viscosity of the main slurry is 2200-2400mPa·s and the viscosity of the spray slurry is 80-120mPa·s. The viscosity of the main slurry is higher, and it can be better rolled onto the flocking sponge. The viscosity of the spray slurry is lower, and it can be sprayed on the surface of the primary slurry sponge through a nozzle. When spraying the primary slurry sponge, first spray it back and forth on the front and back of the primary slurry sponge, and then rotate and spray it on the circumference of the primary slurry sponge to improve the uniformity of the spraying.

[0046] The ingredients of the shotcrete are different from those of the main slurry. The main slurry contains 280-320 parts of magnesium-stabilized zirconia, 180-220 parts of 140-160 mesh zirconia, 90-110 parts of 90-110 mesh zirconia, 110-130 parts of polyvinyl alcohol, 16-24 parts of 90-110 mesh alumina, 2-4 parts of preservative, 2-4 parts of defoamer, 4-8 parts of dispersant, and 16-24 parts of microsilica fume. The ingredients of the shotcrete are 140-180 parts of polyvinyl alcohol, 180-220 parts of monoclinic zirconia 280-320 mesh, 25-35 parts of mullite 180-220 mesh, 35-45 parts of 90-110 mesh alumina, and 16-24 parts of microsilica fume. Preservatives include isothiazolinones, and defoamers include mineral oil defoamers.

[0047] Zirconia used in the existing technology is used in the main slurry, while monoclinic zirconia is used in the spraying. Monoclinic zirconia can achieve higher stability in terms of crystal form, is convenient for spraying, and will not clog the nozzle; mullite sand is additionally added to the spraying. Mullite sand is made by high-temperature sintering of kaolin. It is an aluminum silicate refractory material with better heat resistance and strength, which can improve the heat resistance and structural strength of the foam ceramic filter; sodium alkyl sulfonate is preferably used as the dispersant in the slurry to make the viscosity lower and easier to disperse; the silicon micropowder content in the slurry is higher, which facilitates the formation of a significant mullite phase change on the surface of the foam ceramic filter to enhance the surface strength and heat resistance temperature.

[0048] The drying temperature of the filter sponge is preferably 130-150°C. Due to the addition of the flocking process, the slurry is wrapped with flocking glue and cotton wool in addition to the sponge, so a longer debinding period is required; and by introducing silicon micropowder, low-temperature sintering can be achieved.

[0049] The filter sponge is sintered using a staged heating process, with a sintering temperature range of 0-1650°C and a sintering time of 20-22 hours. Specifically, the preferred sintering process parameters are: 0°C-130°C for 60 minutes; 130°C-220°C for 120 minutes; 220°C-550°C for 240 minutes; 550°C-700°C for 180 minutes; 700°C-900°C for 120 minutes; 900°C-1150°C for 90 minutes; 1150°C-1400°C for 180 minutes; and 1400°C-1650°C for 210 minutes. This staged heating process allows organic components such as polyvinyl alcohol, defoamers, dispersants, and preservatives in the sponge and slurry to separate from the filter at different sintering stages, improving the separation efficiency of the sponge and organic components, ensuring color consistency and overall filter performance. Furthermore, this staged heating process mitigates material volume shrinkage during the sintering process, further reducing the risk of filter cracking.

[0050] Improvements to the slurry can also reduce sintering time, increasing production while also reducing energy costs. Furthermore, the flocking process can enhance the strength and thermal shock resistance of the foam ceramic filter, while the spraying process can increase the surface heat resistance while reducing the risk of slag and casting defects.

[0051] Example 1

[0052] The sponge is in the shape of a square sheet with a side length of 75 mm and a thickness of 20 mm. The number of pores per inch of the sponge is 15. The flocking amount of the flocking sponge in the flocking process is 10%. The components and proportions of the main slurry include 300 parts of 300-mesh magnesium-stabilized zirconia, 200 parts of 150-mesh zirconia, 100 parts of 100-mesh zirconia, 120 parts of polyvinyl alcohol, 20 parts of 100-mesh alumina, 3 parts of preservative, 3 parts of defoaming agent, 6 parts of dispersant and 20 parts of microsilica powder. The components and proportions of the spraying include 160 parts of polyvinyl alcohol, 200 parts of 300-mesh monoclinic zirconia, 30 parts of 200-mesh mullite, 40 parts of 100-mesh alumina and 20 parts of microsilica powder. The preparation method of the present invention is used to prepare a foam ceramic filter.

[0053] Comparative Example 1

[0054] Compared with Example 1, the difference of this embodiment is that the flocking amount of the flocking sponge in the flocking process is 5%.

[0055] Comparative Example 2

[0056] Compared with Example 1, the difference of this embodiment is that no flocking process is performed.

[0057] Example 2

[0058] Compared with Example 1, the difference of this embodiment is that the number of pores per inch of the sponge is 10.

[0059] Comparative Example 3

[0060] Compared with Example 2, the difference of this embodiment is that the flocking amount of the flocking sponge in the flocking process is 5%.

[0061] Comparative Example 4

[0062] Compared with Example 2, the difference of this embodiment is that no flocking process is performed.

[0063] Example 3

[0064] Compared with Example 1, the difference of this embodiment is that the sponge is in the shape of a disc with a diameter of 90 mm.

[0065] Comparative Example 5

[0066] Compared with Example 3, the difference of this embodiment is that the flocking amount of the flocking sponge in the flocking process is 5%.

[0067] Comparative Example 6

[0068] Compared with Example 3, the difference of this embodiment is that no flocking process is performed.

[0069] Example 4

[0070] Compared with Example 3, the difference of this example is that the number of pores per inch of the sponge is 10.

[0071] Comparative Example 7

[0072] Compared with Example 4, the difference of this embodiment is that the flocking amount of the flocking sponge in the flocking process is 5%.

[0073] Comparative Example 8

[0074] Compared with Example 4, the difference of this embodiment is that no flocking process is performed.

[0075] Experimental Example 1

[0076] Ten foam ceramic filter samples were prepared for Examples 1-4 and Comparative Examples 1-8, and their appearance was observed. Examples 1-4, Comparative Example 1, Comparative Example 3, Comparative Example 5 and Comparative Example 7 all adopted the flocking process, and the foam ceramic filters prepared therefrom, the foam ceramic filters prepared in Example 3 and Example 1, were as follows: Figure 3 and Figure 4 As shown, Comparative Examples 2, 4, 6 and 8 do not use flocking technology, and the foam ceramic filters prepared therefrom are as follows: Figure 5 and Figure 6 As shown, by comparison, it can be seen that the foam ceramic filter made by flocking process has coarser slurry ribs, more uniform through-holes, and a rough and bumpy surface, which has better structural strength and filtering performance; especially the edge position of the foam ceramic filter, the effect is more obvious.

[0077] Experimental Example 2

[0078] Ten foam ceramic filter samples were prepared for Examples 1-4 and Comparative Examples 1-8, respectively. The room-temperature compressive strength, room-temperature shear strength, porosity, slag drop rate, and the number of thermal cycles that the foam ceramic filters could withstand at a high temperature of 1100°C were tested. The test results are shown in Table 1.

[0079] Table 1

[0080]

[0081] The flocking amount in the flocking sponge in Examples 1-4 is 10%, the flocking amount in the flocking sponge in Comparative Example 1, Comparative Example 3, Comparative Example 5 and Comparative Example 7 is 5%, and the flocking amount in the flocking sponge in Comparative Example 2, Comparative Example 4, Comparative Example 6 and Comparative Example 8 is 0%. It can be seen from Table 1 that the samples prepared in Examples 1-4 have the best room-temperature compressive strength, room-temperature shear strength, porosity, thermal shock resistance and slag drop rate. The various performances of the samples prepared in Comparative Example 1, Comparative Example 3, Comparative Example 5 and Comparative Example 7 are all weakened, and the various performances of the samples prepared in Comparative Example 2, Comparative Example 4, Comparative Example 6 and Comparative Example 8 are the worst. Therefore, the flocking process can significantly improve the comprehensive performance of the foam ceramic filter and ensure the effective operation of the foam ceramic filter.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a foam ceramic filter based on flocking technology, characterized in that: The following steps are involved: S1, spraying flocking glue on the sponge, the cotton wool is charged by the high voltage electric field of the flocking machine, is attracted and firmly adheres to the sponge coated with flocking glue, and the cotton wool stands upright on the surface of the connecting ribs. After drying and cutting, the flocked sponge is produced; S2, firstly, applying the main slurry on the flocking sponge, and then air-drying to obtain a primary slurry sponge, and then spraying the spray slurry on the primary slurry sponge, and allowing the spray slurry to cover the primary slurry sponge, and finally air-drying to obtain a filter sponge, wherein, The main slurry comprises magnesium-stabilized zirconia, zirconium oxide, polyvinyl alcohol, alumina, a preservative, a defoamer, a dispersant and microsilica powder, and the spraying slurry comprises polyvinyl alcohol, monoclinic zirconia, mullite sand, alumina and microsilica powder; S3, first drying the filter sponge at a constant temperature, and then sintering the filter sponge by increasing the temperature in stages to produce a foam ceramic filter; After sintering, the cotton wool will create a large number of blind holes with extremely small pore sizes on the surface of the foam ceramic filter, which can absorb impurities with extremely small particle sizes in the molten steel.

2. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, characterized in that: The main slurry is composed of 280-320 parts of magnesium stabilized zirconia, 180-220 parts of 140-160 mesh zirconia, 90-110 parts of 90-110 mesh zirconia, 110-130 parts of polyvinyl alcohol, 16-24 parts of 90-110 mesh alumina, 2-4 parts of preservative, 2-4 parts of defoaming agent, 4-8 parts of dispersant and 16-24 parts of microsilica powder.

3. The method for preparing a foam ceramic filter based on flocking technology according to claim 2, characterized in that: The composition of the spraying is 140-180 parts of polyvinyl alcohol, 180-220 parts of 280-320 mesh monoclinic zirconia, 25-35 parts of 180-220 mesh mullite sand, 35-45 parts of 90-110 mesh aluminum oxide and 16-24 parts of microsilica powder.

4. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, wherein: The viscosity of the main slurry is 2200-2400 MPa·s, and the viscosity of the spraying slurry is 80-120 MPa·s.

5. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, characterized in that: The bulk density difference between the primary sponge and the flocking sponge is 0.25-0.35 g / cm 3 .

6. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, wherein: In step S2, the main slurry is coated on the flocking sponge by roller pressing.

7. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, characterized in that: In step S1, the amount of flocking glue used is 40-60g / cm 2 , the length of the cotton wool is 0.3mm-0.8mm.

8. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, wherein: In step S3, the filter sponge is dried at a temperature of 130-150°C.

9. The method for preparing a foam ceramic filter based on flocking technology according to claim 8, characterized in that: In step S3, the temperature range of the stage heating is 0-1650° C., and the sintering time is 20-22 hours.

10. The method for preparing a foam ceramic filter based on flocking technology according to claim 1, characterized in that: The method further includes S4, performing an appearance inspection on the foam ceramic filter and removing defective products.

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