KR20240047904A - Process for preparation of porous ceramic filter - Google Patents

Abstract

The present invention includes a raw material preparation step; A slurry manufacturing step of manufacturing a slurry by applying ball milling; A drying step of drying and producing granules by adding the slurry to a spray dryer equipped with a rotary atomizer; A blending step of mixing the granules in a V-mixer; A molding step of producing a molded product in a filter shape from the granules that have undergone the blending step; and a firing step of processing the molded product by applying heat to it. It provides a porous ceramic filter manufacturing room in which the raw materials include inorganic substances, dispersants, water and organic substances, thereby reducing input energy and ensuring uniform distribution of granules, preventing uneven distribution of granules. It is possible to improve the physical properties of the ceramic filter by preventing non-uniform composition of the fired body and difficulties in controlling diffusion.

Description

Porous ceramic filter manufacturing method {PROCESS FOR PREPARATION OF POROUS CERAMIC FILTER}

The present invention relates to a method of manufacturing a porous ceramic filter used for removing dust, soot, waste gas, fume, VOC dust, etc. generated in industrial processes.

As damage from harmful substances such as various dusts, exhaust fumes, and waste gases occurs due to the industrialization era, filtering technology to filter out these harmful substances before they are discharged to the outside is also developing day by day.

Filters are typically divided into organic filters and inorganic filters depending on the material, and the most common types of filters currently used are polymer filters and ceramic filters.

Compared to ceramic filters, polymer filters are easier to control large-area pores and have lower product costs. Using these characteristics, stability can be achieved in the manufacturing process and it has significant economic advantages. However, organic filters have problems with heat resistance, chemical resistance, abrasion resistance, and flame retardancy.

On the other hand, ceramic filters have much better heat resistance, chemical resistance, and wear resistance than polymer filters, and in particular, they have excellent heat resistance. In general, alumina is applied to the ceramic filter substrate. It has the advantage of being able to easily control the pores of the filter as the particle size is relatively fine and uniform quality can be obtained, and the physical strength of the substrate is strong, ensuring reliability of filtration. There is an advantage to having it. However, since high temperatures are used for a certain period of time during the drying and sintering processes, a large amount of energy is required, and when using fine-grained alumina ceramic substrates, if proper dispersion is not achieved, the ceramic physical properties become poor. Accordingly, there is a need for a method of manufacturing a ceramic filter that is easy to manufacture and can ensure appropriate dispersion of ceramic particles.

The present invention was developed to solve the above-mentioned problems, and its purpose is to provide a ceramic filter manufacturing method that can secure ceramic physical properties by reducing the energy input in the manufacturing process and ensuring appropriate dispersion of ceramic particles. there is.

The present invention includes a raw material preparation step; A slurry manufacturing step of manufacturing a slurry by applying ball milling; A drying step of drying and producing granules by adding the slurry to a spray dryer equipped with a rotary atomizer; A blending step of mixing the granules in a V-mixer; A molding step of producing a molded product in a filter shape from the granules that have undergone the blending step; and a firing step of treating the molded product by applying heat, wherein the raw materials include an inorganic material, a dispersant, water, and an organic material.

According to one embodiment of the present invention, the energy input into the sintering process can be reduced by applying calcined alumina to the raw materials of the present invention to shorten the sintering time and lower the sintering temperature.

Additionally, according to an embodiment of the present invention, the time and energy required for drying can be reduced by applying a spray dryer.

In addition, according to an embodiment of the present invention, in the production of a ceramic filter using granules, uniform distribution of the granules can be secured through a blending step using a V-mixer, so that the fired body due to uneven granule distribution By preventing compositional heterogeneity and difficulty in controlling diffusion, the physical properties of the ceramic filter can be improved.

Figure 1 shows a flow chart of a method for manufacturing a ceramic filter according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention are described in detail. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. The present embodiments only serve to ensure that the disclosure of the present invention is complete and to convey the content of the present invention to those skilled in the art. It is provided for more complete information.

The terms used herein are used to describe specific embodiments and are not intended to limit the invention.

As used herein, the singular forms include the plural forms unless the context clearly indicates otherwise. Additionally, when used herein, “comprises” and/or “comprising” specifies the presence of the mentioned features, numbers, steps, operations, members, elements and/or groups thereof, and one or more other features. , does not exclude the presence or addition of numbers, operations, members, elements and/or groups. As used herein, the term “and/or” includes any one and all combinations of one or more of the listed items.

Hereinafter, it will be described in detail with reference to the drawings.

1 is a flowchart illustrating a method of manufacturing a ceramic filter according to an embodiment of the present invention.

Referring to FIG. 1, the ceramic filter manufacturing method may include raw material preparation (101), slurry production (102), drying (103), blending (104), molding (105), and firing (106) steps.

In the raw material preparation step (101), the raw materials necessary for manufacturing a ceramic filter can be prepared. The raw materials may include inorganic substances, dispersants, water, and organic substances. At this time, 60.6 to 62.9 parts by weight of the inorganic material, 0.8 to 1.0 parts by weight of the dispersant, 30.0 to 31.5 parts by weight of the water, and 6.3 to 6.9 parts by weight of the organic material can be prepared and then added to the subsequent process.

The inorganic material may be composed of a mixture of main raw materials and inorganic additives, and may be formed in a weight-based ratio of main raw materials: inorganic additives = 80:20.

The main raw material may include alumina (Al ₂ O ₃ ). The alumina may be calcined alumina. The calcined alumina can be fired at a relatively low temperature compared to sintered alumina or fused alumina, so processability can be improved when applied to the formulation of the present invention, for example, sintering time can be shortened and sintering temperature can be lowered. . The particle size of the calcined alumina may be 1 to 5 μm. When the particle size of the calcined alumina is within the above range, pore formation and mechanical strength of the ceramic filter can be improved. By applying the calcined alumina to the raw materials of the present invention to shorten the sintering time and lower the sintering temperature, the energy input into the sintering process can be reduced.

The inorganic additive is used as a source of MgO, CaO, and SiO ₂ . The inorganic additive may include talc, clay, and limestone, and may be composed of talc:clay:limestone by weight in a ratio of 5:13:2. By adding an inorganic additive composed of the above ratio to the mixing of the raw materials of the present invention, it can help form a liquid phase during firing.

The dispersant may be an anionic aqueous dispersant. For example, ammonium salts of polycarboxylic acids may be included. When the polycarboxylic acid ammonium salt dispersant is applied to the mixing of the raw materials of the present invention, the inorganic material can be evenly dispersed in the slurry preparation step (102).

The water can be distilled water or ID-Water.

The organic material may be composed of a mixture of a binder, a plasticizer, a mold release agent, and an antifoamer, and may be composed of a weight-based ratio of binder: plasticizer: mold release agent: defoamer = 7: 1.5: 2.0: 0.2. When the above-described organic components, which will be described later, are included in the mixing ratio of the raw materials of the present invention, shape retention and strength are provided to maintain the shape during molding, and the occurrence of bending and cracking due to shrinkage or warping during drying is prevented. This can be prevented and productivity during molding can be improved.

For example, the binder may include one or more of PVA, PVB, MC, EC, and CMC, and for example, may include PVA. The plasticizer may include glycerin or PEG, and for example, may include PEG. The mold release agent may include stearic acid, a synthetic polymer, and a fluorinated compound. For example, it may include stearic acid. The antifoaming agent may include one or more of polyether-based, alcohol-based, metallic soap-based, and amide-based agents. For example, it may include polyether-based.

When applying the above-mentioned organic substances in the mixing of the raw materials of the present invention, alkalis such as Na, K, Li, and residual heavy metals such as Fe, Ni, Co, and Cr are not contained, and the decomposed gas is toxic and strong acid. · As it is not strongly alkaline, the organic material does not react with the inorganic material, is easily soluble in water, and can be completely decomposed and volatilized at low temperature (300-400°C) in an oxidizing or non-oxidizing atmosphere.

The slurry production step (102) prepares a slurry from the raw material using a mill, and may include a primary milling step and a secondary milling step. When milling is performed in the step of producing a slurry by mixing the raw materials of the present invention, uniform distribution of the formed granules can be secured, preventing uneven composition of the fired body and difficulties in diffusion control due to uneven distribution of the granules, thereby producing ceramic The physical properties of the filter can be improved. The specific method is described below.

The milling machine may be a ball milling machine. At this time, the ball used in the ball mill can be a stainless steel ball with a size of 3 to 5 mm, and the rotation speed of the ball mill can be set to 400 to 700 RPM, but can be set differently depending on facility conditions.

The first milling step can be completed by adding the inorganic material, dispersant, and water into the ball mill and milling for about 1 hour to 1 hour and 30 minutes while checking the particle size.

The secondary milling step may include adding the organic material to the ball mill on which the primary milling has been completed and performing additional milling for about 10 to 15 minutes to prepare a slurry. At this time, bubbles generated during the first milling step may be removed by the antifoaming agent.

Afterwards, the milled slurry is stored with continuous stirring to prevent precipitation.

The drying (103) step is a step of drying the slurry to form granules, and a spray dryer capable of drying the dried particles in a form that is close to spherical and has excellent fluidity can be applied.

The spray dryer may be a spray dryer using a rotary atomizer. By using a spray dryer equipped with the rotary atomizer, the slurry is formed into granules with a particle size of 20 to 200 ㎛, and the spray dryer process conditions are adjusted so that the granules do not have a donut shape to ensure uniformity of the granules. By ensuring a uniform distribution, the physical properties of the ceramic filter can be improved.

The blending (104) step is a step of mixing the granules with various particle sizes in a uniform distribution, and a mixer used in a mechanical mixing method can be applied. For example, one of the V-mixer, Y-mixer, double cone mixer, zero gravity mixer, and three-dimensional mixer can be selected and used, but the mixing of the raw materials of the present invention It is desirable to use a V-mixer.

The rotation speed of the V-mixer may be 10 to 20 times/min, and the operating time may be 20 to 30 minutes. Accordingly, the granules to which the blending (104) step is applied can secure uniform distribution, and prevent unevenness in the composition of the fired body and difficulty in controlling diffusion due to uneven distribution of the granules, thereby improving the physical properties of the ceramic filter. You can.

The molding (105) step is a step of creating a molded product by molding it into a filter shape using the granules that have gone through the blending (104) step, and is a step of dry molding the granules to form a molded product of a certain shape. The dry molding is to manufacture a molded body by charging powder into a mold of a certain shape and applying a certain pressure. For example, a dry press method can be applied.

When molding using the dry press method, the molding pressure is usually 0.7 to 1.0 kgf/cm2. In general molding, the molding pressure is increased so that the granules can be destroyed, but in filter molding, it is desirable to mold at a relatively low pressure to prevent the granules from breaking.

The firing (106) step is a step of imparting mechanical strength to the filter by heat-treating the molded product at a high temperature. First heat treatment is performed in the range of room temperature to 800°C to remove the organic binder remaining after the molding process. After the degreasing process and the degreasing process, a multi-stage process of performing secondary heat treatment at a temperature of 1350 to 1400°C for less than 1 hour and then cooling can be applied. At this time, the maximum temperature can be set to the temperature at which the liquid phase begins to form in the temperature range of 1350°C to 1400°C. The liquid phase can provide a bonding force to the calcined alumina, which is the main raw material. If the maximum temperature for calcination exceeds the above numerical range, the liquid phase is excessively generated, which may adversely affect the formation of pores, which may deteriorate the physical properties of the ceramic filter. If it is below the above numerical range, it may be difficult to obtain sufficient mechanical rigidity.

Example

Raw materials having the composition ratios in Table 1 below were prepared.

division content
[Unit: parts by weight] mineral main ingredient Alumina (LS130 _ Nippon Light Metal Co.) 49.3 weapon
additive Talc (SP3000 _ Dawon Chemical) 3.1 Clay (CL3000) 8.0 Limestone (TL-1000) 1.2 Dispersant (SN5468 _ SAN NOPCO LIMITED) 0.9 Water (distilled water) 30.8 organic matter Binder (PVA 205MB _ KURARAY POVAL) 4.3 Plasticizer (PEG #400) 0.9 Hyungjae Lee (LU6418 _ SAN NOPCO LIMITED) 1.2 Defoamer (SN485 _ SAN NOPCO LIMITED) 0.1 Sum 100.0

Inorganic substances, dispersants, and water were put into a ball mill (BAM-22_NANO IN TECH co.,ltd) according to the composition ratio (here, the unit is parts by weight) as shown in Table 1, and primary milling was performed at 400 RPM for 1 hour. Perform. At this time, the ball used in the ball mill is a stainless steel ball of 5 mm size.

In the second milling step, organic material is added to the ball mill on which the first milling has been completed according to the composition ratio shown in Table 1, and milling is performed at 400 RPM for 10 minutes to prepare a slurry.

The slurry prepared as above is input into a spray dryer (COC-12_Seo gang engineering co., ltd) equipped with a rotary atomizer to generate granules.

Experimental Example 1: Application of blending step

The granules were blended using a V mixer (VM-50_Sungchang Machinery Co., Ltd.) at a rotation speed of 15 times per minute and an operating time of 30 minutes.

Using the blended granules, create a molded product by applying a pressure of 0.8kgf/cm2 using a dry press, then perform a first heat treatment at 800°C, a second heat treatment for 1 hour at a temperature of 1350 to 1400°C, and then cool. A sample was produced.

The strength was measured by measuring the three-point bending strength using a strength tester (DTU-900 MHA, Daekyung tech, Korea), and the porosity was measured using Archimedes' principle, and the results are shown in Table 2 below.

Comparative Example 1: Blending step not applied

Using granules that were not subjected to the above blending step, a molded product was created by applying a pressure of 0.8kgf/cm2 using a dry press, followed by primary heat treatment at 800°C and secondary heat treatment at 1350°C to 1400°C for 1 hour. After processing, the sample was produced by cooling.

The strength was measured by measuring the three-point bending strength using a strength tester (DTU-900 MHA, Daekyung tech, Korea), and the porosity was measured using Archimedes' principle, and the results are shown in Table 2 below.

division robbery Porosity (%) Experiment result Experimental Example 1. Application of blending step 58.9 34.4 Comparative Example 1. Blending step not applied 49.7 40.1

As can be seen from the values shown in Table 2 above, it can be seen that the strength increases and the porosity decreases in the samples to which the blending step was applied. This is interpreted as the fact that through the blending step using the V-mixer of the present invention, the granules were evenly mixed by size and sintered at a high stacking density, thereby increasing strength and decreasing porosity.

As described above, the specific description of the present invention has been made based on examples with reference to the accompanying drawings, but since the above-described embodiments are only explained by referring to preferred examples of the present invention, the present invention is limited to the above embodiments. It should not be understood, and the scope of rights of the present invention should be understood in terms of the claims and equivalent concepts described later.

Claims (4)

Raw material preparation stage;
A slurry manufacturing step of manufacturing a slurry by applying ball milling;
A drying step of drying and producing granules by putting the slurry into a spray dryer equipped with a rotary atomizer;
A blending step of mixing the granules in a V-mixer;
A molding step of producing a molded product in a filter shape from the granules that have undergone the blending step; and
A firing step of processing the molded product by applying heat;
includes
A method of manufacturing a porous ceramic filter, wherein the raw materials include inorganic substances, dispersants, water and organic substances.
In claim 1,
The raw materials are based on 100 parts by weight of the raw materials,
60.6 to 62.9 parts by weight of the inorganic material;
0.8 to 1.0 parts by weight of the dispersant;
30.0 to 31.5 parts by weight of water; and
6.3 to 6.9 parts by weight of the organic material;
Including,
The minerals include alumina, talc, clay, and limestone,
A method of manufacturing a porous ceramic filter, wherein the dispersant includes ammonium polycarboxylic acid salt.
In claim 2,
The blending step is performed under the conditions of a rotation speed of the V-mixer of 10 to 20 times/min and an operation time of 20 to 30 minutes.
In claim 3,
A method of manufacturing a porous ceramic filter in which the ball used for ball milling in the slurry production step is a stainless steel ball with a size of 3 to 5 mm.