Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/02—Loose filtering material, e.g. loose fibres
  • B01D39/06—Inorganic material, e.g. asbestos fibres, glass beads or fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/14—Other self-supporting filtering material ; Other filtering material
  • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
  • B01D39/2068—Other inorganic materials, e.g. ceramics
  • B01D39/2093—Ceramic foam
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  • C04B33/00—Clay-wares
  • C04B33/02—Preparing or treating the raw materials individually or as batches
  • C04B33/04—Clay; Kaolin
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  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
• • C—CHEMISTRY; METALLURGY
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  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/14—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silica
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/16—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay
  • C04B35/18—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on silicates other than clay rich in aluminium oxide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
  • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
  • C04B35/56—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides
  • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/0022—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors
  • C04B38/0032—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof obtained by a chemical conversion or reaction other than those relating to the setting or hardening of cement-like material or to the formation of a sol or a gel, e.g. by carbonising or pyrolysing preformed cellular materials based on polymers, organo-metallic or organo-silicon precursors one of the precursor materials being a monolithic element having approximately the same dimensions as the final article, e.g. a paper sheet which after carbonisation will react with silicon to form a porous silicon carbide porous body
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  • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
  • C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
  • C04B38/0615—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
  • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
  • C04B2111/00793—Uses not provided for elsewhere in C04B2111/00 as filters or diaphragms

Definitions

• the present invention relates to a method for preparing a multi- layered ceramic filter and a ceramic filter prepared by the method. More particularly, according to the method of the present invention, production cost can be reduced, preparation is easy, modification of a shape and preparation of a large-sized filter are easy, abrasion resistance and heat resistance are remarkably improved, porosity control range is comparatively improved, light- weighted construction is possible through a different shaped cross sections, and eye-blocking is minimized.
• VOC's VOC's
• a polymer filter is used.
• the polymer filter has problems of inferior heat resistance, chemical resistance, abrasion resistance and flame retardation.
• polyester shrinks at 150 ° C, and even PTFE (Teflon) has maximum heat resistance of approximately 250 ° C . Since various waste gases and moisture are simultaneously generated under conditions for process using an industrial filter, if the surface of a non-woven fabric filter made of polymers such as polyester, polypropylene, acryl, polyamide, polyimide, glass fiber, etc. is dust off, dust falls down to seriously abrade a filter surface, thereby damaging a filter and shortening life cycle of a filter.
• sparks generated during firing process may be attached to a filter to cause fire or make a hole in the filter, which may expose waste gas in the air in case filters are used for a waste incinerator, a boiler, a coal steam power plant, a coal gasification complex plant, and this is against recent environmental regulation. Therefore, in order to solve these problems, a ceramic filter has been developed, which has superior heat resistance, chemical resistance, abrasion resistance to a polymer filter, and does not require a separate cooling apparatus in an exhauster due to superior heat resistance to reduce installation and maintenance costs.
• the existing ceramic filters are generally prepared by vacuum molding or extrusion molding of ceramic fiber into a tube shape.
• the present invention provides a method for preparing a multi-layered ceramic filter, which comprises the steps of: a) mixing i) 25 to 60 parts by weight of ceramic powder selected from the group consisting of silicon carbide, alumina, sillimanite, kaolin, silica, titania, and siliceous earth; ii) 10 to 40 parts by weight of clay; iii) 5 to 40 parts by weight of pore-forming material; iv) 1 to 20 parts by weight of a binder; and v) 20 to 60 parts by weight of a dispersion to prepare a slurry; b) supporting the slurry prepared in step a) on a support to prepare a molded article; c) drying the molded article prepared in step b); d) further coating inside or outside of the molded article dried in step c) a slurry comprising i) 40 to 80 parts by weight of ceramic powder selected from the group consisting of silicon carbide, alumina, sillima
• the present invention also provides a method for preparing a multi- layered ceramic filter, which comprises the steps of: a) mixing i) 25 to 60 parts by weight of ceramic powder selected from the group consisting of silicon carbide, alumina, sillimanite, kaolin, silica, titania, and siliceous earth; ii) 10 to 40 parts by weight of clay; iii) 5 to 40 parts by weight of pore-forming material; iv) 1 to 20 parts by weight of a binder; and v) 20 to 60 parts by weight of a dispersion to prepare a slurry; b) supporting the slurry prepared in step a) on a support to prepare a molded article; c) drying the molded article prepared in step b); d) sintering the molded article dried in step c); e) further coating inside or outside of the molded article sintered in step d) a slurry comprising i) 40 to 80 parts by weight of ceramic powder selected from the group consist
• Fig. 1 shows a cross-sectional view of one embodiment of a mold used in the preparation method of a multi-layered ceramic filter of the present invention.
• Fig. 2 is a photograph of a circular tube shaped ceramic filter prepared by the preparation method of the present invention.
• Fig. 3 is a photograph of a radial curbed tube shaped ceramic filter prepared by the preparation method of the present invention.
• Fig. 4 is a photograph of various kinds of ceramic filters prepared by the preparation methods of the present invention.
• Fig. 5 is a photograph of a ceramic filter in which the upper and the lower caps are assembled, prepared by the preparation method of the present invention.
• Fig. 6 is a Scanning Electron Microscope picture of the further coated area of a ceramic filter prepared by the preparation method of the present invention.
• Fig. 7 is a Scanning Electron Microscope picture of a support containing an area of a ceramic filter prepared by the preparation method of the present invention.
• Fig. 8 is a Scanning Electron Microscope picture of the upper part of a support containing area and further coated area of a ceramic filter prepared by the preparation method of the present invention.
• Fig. 9 is a photograph of an extended ceramic filter prepared by the preparation method of the present invention.
• Fig. 10 is a photograph of a multi-layered ceramic filter installed in a dusting apparatus, prepared by the preparation method of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
• the ceramic filter of the present invention is prepared by a first method comprising the steps of mixing ceramic powder selected from the group consisting of silicon carbide, alumina, sillimanite, kaolin, titania and siliceous earth, clay, pore-forming material, a binder and a dispersion to prepare a slurry; supporting the slurry on a support to prepare a molded article; drying the molded article; further coating inside or outside of the dried molded article ceramic a slurry comprising ceramic powder, a pore-forming material, a binder and a dispersion; drying; and sintering.
• the ceramic filter of the present invention is prepared by a second method comprising the steps of mixing ceramic powder selected from the group consisting of silicon carbide, alumina, sillimanite, kaolin, silica, titania and siliceous earth, clay, a pore-forming material, a binder and a dispersion to prepare a slurry; supporting the slurry on a support to prepare a molded article; drying and sintering the molded article; further coating inside or outside of the sintered molded article a slurry comprising ceramic powder, a pore-forming material, a binder and a dispersion; and drying and sintering.
• a) Preparation of a slurry This step is to mix i) 25 to 60 parts by weight of ceramic powder selected from the group consisting of silicon carbide, alumina, sillimanite, kaolin, silica, titania and siliceous earth, ii) 10 to 40 parts by weight of clay, iii) 5 to 40 parts by weight of a pore-forming material, iv) 1 to 20 parts by weight of a binder, and v) 20 to 60 parts by weight of a dispersion.
• silicon carbide, alumina, sillimanite group (AI 2 O 3 -SiO 2 ), kaolin group (AI 2 O 3 -2SiO 2 -2H 2 O), silica (SiO 2 ), titania or siliceous earth can be used, and more preferably, alumina, silicon carbide or a mixture thereof is used.
• the ceramic powder various kinds of material having various particle sizes, specific kinds of material having the same particle diameter, or one kinds of material having different particle sizes can be used.
• the particle size is preferably 0.001 ⁇ m to 1 mm. If the particle size of the ceramic powder falls within the above range, pore formation and mechanical strength of a ceramic filter can be improved.
• the ceramic powder preferably is comprised in the slurry composition in an amount of 25 to 60 parts by weight, more preferably in an amount of 30 to 50 parts by weight. If the content falls within the above range, physical strength, shape of a ceramic filter can be maintained, filtering efficiency can be remarkably improved, twisting and cracks can be prevented during sintering, and abrasion resistance of a ceramic filter can increase.
• the ii) clay which constitutes a basic structure of a ceramic filter after sintering, facilitates bonding between ceramic particles during sintering.
• the clay various kinds of material having various particle sizes, specific kinds of material having the same particle size, or one kind of material having different particle sizes can be used.
• the particle size is preferably 0.001 ⁇ m to 1 mm. If the particle size of the clay falls within the above range, pore formation and mechanical strength of a ceramic filter can be improved.
• the clay is preferably comprised in the slurry composition in an amount of 10 to 40 parts by weight, more preferably in an amount of 15 to 25 parts by weight. If the content falls within the above range, physical strength and shape of a ceramic filter can be maintained, filtering efficiency can be remarkably improved, twisting and cracks can be prevented during sintering, and abrasion resistance of a ceramic filter can increase.
• the iii) pore forming material forms pores in a ceramic filter.
• carbon As the pore forming material, carbon, active carbon, wood-based powder, sawdust, salt, naphthalene or talc can be used.
• the pore forming material those having various particle sizes can be used.
• the particle size is preferably 0.001 ⁇ m to 1 mm. If the particle size of the pore forming material falls within the above range, pores with appropriate size can form and mechanical strength of a ceramic filter can be improved.
• the pore forming material burns to disappear during sintering process thereby forming pores in a ceramic filter.
• the pore forming material is preferably comprised in the slurry composition in an amount of 5 to.40 parts by weight, and more preferably 10 to 25 parts by weight. If the content falls within the above range, the pore forming material completely burns during sintering to efficiently form pores in a ceramic filter.
• the iv) binder functions for binding the slurry with the support.
• an organic binder an inorganic binder, or a mixture thereof can be used, preferably a mixture of an inorganic binder and an organic binder is used.
• the binder includes an inorganic binder such as frit or barium carbonate (BaCOs), and an organic binder such as MAP
• the binder is preferably composed in the slurry composition in an amount of 1 to 20 parts by weight, preferably in an amount of 5 to 10 parts by weight. If the content falls within the above range, the slurry and the support can be efficiently bound.
• the v) dispersion may be varied according to the kinds of the binder, and preferably water or alcohol is used.
• the dispersion is preferably composed in the slurry composition in an amount of 20 to 60 parts by weight, preferably in an amount of 20 to 30 parts by weight. If the content falls within the above range, each component can be efficiently mixed, and the slurry can maintain appropriate viscosity to efficiently bind to the support.
• the ceramic powder, clay, pore-forming material and a binder can be simultaneously introduced into the dispersion, or sequentially separately introduced at a specific interval. It is preferable to mix ceramic powder, clay, pore forming material and an inorganic binder (mixed in case an inorganic binder is used) with the dispersion and then mix an organic binder with the mixture in order for convenience of mixing. The mixing is preferably conducted for 1 to 10 hours.
• the mixed slurry is preferably aged for 1 hour or more.
• This step is to support the slurry prepared in step a) on a support to prepare a molded article.
• the size of the support may be varied according to the size of a ceramic filter to be prepared.
• the support may include those having porous structure capable of supporting a slurry, and preferably non-woven fabric, woven-fabric or sponge, etc. is used in terms of facility of application.
• the non-woven fabric is prepared by binding short staple to a web or sheet type fiber aggregate using an adhesive, adhering fibers using thermoplastic fiber, or entangling fibers by needle punching, sewing, etc.
• polyester, aramide, polyphenylenesulfide, home-acrylic, polyimide, polytetrafluoroethylene (PTFE), viscose, natural fiber, glass fiber, ceramic fiber or metal fiber, etc. is used.
• the woven-fabric is prepared by spinning, weaving, cotton weaving, etc. Preferably, it is loosely woven to contain sufficient pores for supporting the slurry.
• This step is conducted by coating the slurry on the support, immersing the support in the slurry, or spraying the slurry on the support. And, before supporting the slurry, the support may be made into a shape of a ceramic filter to be prepared by adhesion, fusion, sewing, bonding or molding with a mold.
• a process of immersing the support in a slurry solution and squeezing is repeated 2-3 times so that sufficient amount of a ceramic mixture can be safely arrived on the support. And, it is more preferable to repeat a process of coating or spraying the slurry on the support and squeezing 2 ⁇ 3 times so that sufficient amount of the slurry solution can be supported on the support.
• drying may be immediately conducted.
• a step of molding to a suitable shape can be further conducted to prepare a molded article with a specific shape.
• the support on which the slurry is supported can be molded into various shapes according to its purposes. Specifically, the support is closely adhered and bound to a mold of circular tube shape, radial curved tube shape, or rectangular tube shape, and they are fixed with a clamp, etc. to mold into circular tube, radial tube or rectangular tube shape.
• a ceramic filter of radial curved tube shape is prepared using a mold of radial curved tube shape as shown in Fig. 1 , it can be applied to those that a circular tube is applied to, while maximizing filtering area to increase filtering efficiency.
• a release film can be added between the support and the mold in order to facilitate separation of the mold and the support.
• resin film made of rubber, urethane resin, or epoxy resin, or a paper film such as kraft paper can be used.
• This step is to dry the molded article prepared in step b). It allows safe sintering and prevents modification of a shape of the molded article during sintering preparation process and sintering process.
• drying can be conducted by natural drying, hot wind, sunlight, or shade.
• drying is conducted by infrared rays so as to reduce drying time and prevent modification of a molded article and cracks.
• d) Further coating This step is to further coat inside or outside of the molded article dried in step c) a slurry comprising i) 40 to 80 parts by weight of ceramic powder, ii) 10 to 40 parts by weight of pore forming material, iii) 7 to 30 parts by weight of a binder and iv) 10 to 50 parts by weight of a dispersion.
• the i) ceramic powder may be identical to that used in step a).
• the ceramic powder is preferably comprised in the slurry composition in an amount of 40 to 80 parts by weight. If the content falls within the above range, fine pores form inside or outside of the molded article to prevent eye-blocking and recycling of the filter is easy.
• the ii) pore forming material may be identical to that used in step a).
• the pore forming material is preferably comprised in the slurry composition in an amount of 10 to 40 parts by weight. If the content falls within the above range, the pore forming material completely burns during sintering to efficiently form pores.
• the iii) binder may be identical to that used in step a).
• the binder is preferably comprised in the slurry composition in an amount of 7 o 30 parts by weight. If the content falls within the above range, the slurry can be effectively bound to the molded article.
• the iv) dispersion may be identical to that used in step a).
• the dispersion is preferably comprised in the slurry composition in an amount of 10 to 50 parts by weight. If the content falls within the above range, each component can be effectively mixed and slurry can maintain appropriate viscosity to effectively bind to the molded article.
• the slurry for further coating may, if necessary, further comprise v) clay.
• the clay may be identical to that used in step a), and it is preferably comprised in the slurry in an amount of 10 to 40 parts by weight.
• the slurry is further coated inside or outside of the molded article dried in step c), and the further coating can be repeated twice or more times according to requirements and purposes of a ceramic filter.
• the content and thickness of the slurry may varied in order to differing in porosity, strength and functions of a surface layer according to the purpose of a ceramic filter
• the further coating can be conducted by addition painting with a brush, immersing a molded article in a slurry, or spraying.
• a dense sintered layer that does not comprise a support forms on a surface to improve strength of a ceramic filter.
• This step is to dry the molded article further coated in step d), wherein the drying may be conducted by the same method as in step c). f) sintering
• This step is to sinter the molded article dried in step e).
• the sintering is conducted by removing a mold from the dried molded article and introducing it into a sintering furnace and then elevating the temperature of the furnace to a sintering temperature.
• the sintering may be conducted after further conducting a processing step for cutting the molded article into a size of a ceramic filter to prepare body of the filter; and an assembling step of manufacturing a lower cap fitted to an outer diameter of the body and an upper cap having wings by supporting a slurry on a support and drying, and assembling the upper and lower caps using a ceramic bond so that lower part is closed and an upper part is opened.
• the sintering temperature may be set according to components and compositional ratio of the slurry. In order to prevent modification, shrinkage and damage of the molded article during temperature elevation, it is preferable to elevate temperature at a speed of 0.5-3 °C/min from room temperature to 500 ° C . And, it is more preferable to elevate at a speed of 0.5-1 ⁇ /min between 150 ⁇ 450 ° C, and to finally elevate to 900 ⁇ 1300°C according to composition of a ceramic powder and maintain the temperature for 2-48 hours to complete sintering.
• This step can be conducted by the same method as in step b) of the first method.
• c) drying This step can be conducted by the same method as in step c).
• This step is to further coat inside or outside of the molded article dried in step d) a slurry comprising i) 50 to 80 parts by weight of ceramic powder, ii) 10 to 40 parts by weight of pore forming material, iii) 7 to 30 parts by weight of a binder, and iv) 10 to 30 parts by weight of a dispersion.
• step d) of the first method This step can be conducted by the same method as in step d) of the first method.
• f) Drying This step is to dry the molded article further coated in step d), and can be conducted by the same method as the above step c).
• This step is to sinter the molded article dried in step f), and can be conducted by the same method as in step f) of the first method.
• the second method wherein further coating is conducted after sintering can be applied where further coating is conducted before sintering according to the first method, as well as where further coating is not conducted before sintering.
• the finally prepared ceramic filter can be made into various shapes as shown in Figs. 2 to 5, and it can be manufactured into a structure having high porosity for an area including a support and dense porosity for further coated layer as shown in Figs. 6 to 8. And, as shown in Fig. 9, 2 or more ceramic filters can be adhered using an adhesive to use extended ceramic filter, wherein a pipe with a size smaller than inner diameter of a ceramic filter can be introduced between the ceramic filters.
• the adhesive can be commonly used adhesive, and ceramic adhesive is preferable.
• the method of the present invention in order to improve functionality of a ceramic filter, may further comprise the steps of further coating functional material insider or outside of a ceramic filter dried in step c), one further coated and dried, one sintered in step d), one sintered, and then further coated and dried, one sintered, and then further coated, dried and sintered; and then drying.
• the coating of the functional material can be conducted by known methods capable of appropriately bonding ceramic filter with functional material. And, after coating the functional material and drying, sintering step can be further conducted.
• zeolite platinum, palladium, silver, TiO 2 , or ZnO can be used alone or in combination.
• the inside and outside of the ceramic filter can be coated with the same or different material.
• production cost is low, preparation is easy, modification of a shape and production of a large-sized filter are easy, abrasion resistance and heat resistance are superior, and porosity control range broadens.
• the method of the present invention can form dense sintered layer inside or outside surface to improve strength of a ceramic filter, form a surface layer having fine pores to reduce eye-blocking thus enabling recycling of a filter, prepare ceramic filter applicable at high temperature high pressure, improves roughness thus making further coating easy.
• the present invention also provides a ceramic filter prepared by the above method.
• the ceramic filter of the present invention can be used for a post treating apparatus in various industries, a dusting filter of various dusting equipment as shown in Fig. 10, an incinerator, a dusting apparatus for a crematory, a dusting apparatus for engine exhaust gas, an air purifier for automobile exhaust gas, or an apparatus for removing volatile organic compounds by photo-catalytic activity in an air purifier.
• the primary slurry solution was coated on non-woven fabric with size of 1000mm x 1500mm x 2 mm so as to be sufficiently supported thereon.
• a mold with a circular tube shape was manufactured from PVC, a release film is bound to the mold surface, and then the non-woven fabric immersed in the slurry solution was wound along with the shape of the mold to prepare a molded article, which was dried by hot wind at 30-90 ° C for 1 hour.
• the mold and the release film were removed from the dried molded article, and then the molded article was put in an electric furnace, which was elevated at a speed of 3 ° C/min from room temperature to 150°C, slowly elevated at a speed of 0.5-1 °C/min from 150 to 450°C , and maintained at
• Fig. 6 is Scan Electronic Microscope (SEM) picture of further coated pore layer
• Fig. 7 is SEM picture of an area including a support
• Example 2 A ceramic filter having 2 layers with pores of different sizes was prepared by the same method as in Example 1 , except that the slurry solution was further coated only inside of the molded article.
• a ceramic filter having 2 layers with pores of different sizes was prepared by the same method as in Example 1 , except that the slurry solution was further coated only outside of the molded article.
• a ceramic filter having 2 layers with pores of different sizes was prepared by the same method as in Example 1 , except that silicon carbide was used instead of alumina in the slurry solution.
• a ceramic filter having 2 layers with pores of different sizes was prepared by the same method as in Example 1 , except that 25 parts by weight of alumina and 25 parts by weight of silicon carbide were used together instead of alumina in the slurry solution.
• Example 6 A ceramic filter having 2 layers with pores of different sizes (Fig. 3) was prepared by the same method as in Example 1 , except that a radial curved tube shaped mold (Fig. 1 ) was used instead of the circular tube shaped mold to mold a non-woven fabric supporting the slurry solution.
• Example 7 A ceramic filter having 2 layers with pores of different sizes (Fig. 3) was prepared by the same method as in Example 1 , except that a radial curved tube shaped mold (Fig. 1 ) was used instead of the circular tube shaped mold to mold a non-woven fabric supporting the slurry solution.
• Example 7 A ceramic filter having 2 layers with pores of different sizes (Fig. 3) was prepared by the same method as in Example 1 , except that a radial curved tube shaped mold (Fig. 1 ) was used instead of the circular tube shaped mold to mold a non-woven fabric supporting the slurry solution.
• a ceramic filter having 2 layers with pores of different sizes was prepared by the same method as in Example 1 , except that a rectangular tube shaped mold was used instead of the circular tube shaped mold to mold a non-woven fabric supporting the slurry solution.
• Example 8
• a non-woven fabric immersed in a slurry solution was molded and dried by hot wind by the same method as in Example 1 , except using a mold of radial curved tube shape.
• a ceramic filter having different pore sizes was prepared by the same method as in Example 1 , except that a slurry solution for further coating was primarily coated and dried, and then secondary coating and drying was conducted on the primarily coated surface.
• Example 10 A ceramic filter having different pore sizes was prepared by the same method as in Example 1 , except that a slurry solution for further coating was primarily coated and dried, and then secondary coating and drying was conducted on the primarily coated surface.
• the primary slurry solution was coated on a non-woven fabric of 1000m x 1500mm x 8mm so as to be sufficiently supported.
• a mold of a circular tube shape was manufactured from PVC, a release film was bound to the mold surface, and then the non-woven fabric immersed in the slurry solution was rolled along the shape of the mold, and dried by hot wind at 30-90 ° C for 1 hour. From the dried mold, a mold and a release film were removed, and then the mold was put in an electric furnace, of which temperature was elevated at a speed of 3 ° C/min from room temperature to 150 ° C, slowly elevated at a speed of 0.5-1 ° C/min, and maintained at 900 ⁇ 1300 ° C for 2 hours to complete sintering. Then, 20 parts by weight of water, 70 parts by weight of alumina
• AI 2 O 3 25 parts by weight of active carbon and 5 parts by weight of a binder of frit (VA950, Duklim material) and 10 parts by weight of water binder were uniformly mixed in a mixer to prepare a slurry solution for further coating, which was coated inside and outside of the sintered molded article by painting with a brush.
• a binder of frit VA950, Duklim material
• Drying and sintering were conducted as the above to manufacture a ceramic filter having 2 layers with different pore sizes.
• a ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that a slurry solution for further coating was coated only inside of the mold.
• a ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that the slurry solution for further coating was coated only outside of the mold.
• a ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that silicon carbide (SiC) was used instead of alumina in the primary slurry solution.
• SiC silicon carbide
• Example 14 A ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that 25 parts by weight of alumina and 25 parts by weight of silicon carbide were used instead of alumina (AI 2 U3).
• Example 15 A ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that a mold of a radial curved tube shape (Fig. 1 ) was used instead of the circular tube shaped mold.
• Example 16 A ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that a rectangular tube shaped mold is used instead of the circular tube shaped mold.
• a non-woven fabric immersed in a slurry solution was mold and dried by the same process as described in Example 10, except that a radial curved tube shaped mold was used.
• the dried mold was cut to make a body of a filter, and a lower cap fitted to an outer diameter of a body and an upper cap having wings were manufactured by immersing or coating the non-woven fabric with the slurry solution and drying.
• the body and the lower and upper caps were assembled with a ceramic adhesive so that the lower part is closed and the upper part is opened as a wing shape.
• a ceramic filter having 2 layers with different pore sizes was manufactured by the same method as in Example 10, except that a slurry solution for further coating was primarily coated and then secondary coating was conducted on the primarily coated surface.
• a large-sized ceramic filters having diameter of 100mm or more and length of 1 m or more can be manufactured by Examples 1 to 18, which has high porosity of 40% or more and superior heat resistance up to 1000 ° C.
• a separate preparation of an expensive mold is not required, a pressurizing device or vacuum device is not required, and thus production cost of a ceramic filter is low, preparation is easy, modification of a shape is easy, and a large-sized filter can be produced as long as the size of a sintering furnace allows.
• porosity control range can be comparatively broad because pressurization or vacuum process is not needed, pore size can be selected within the range of 0.001-5 mm according to the density of a support, the size and content of pore forming material to control pore size with small variation, high porosity of 40% or more can be achieved, and a light-weighted porous filter can be prepared.
• the present invention can prepare a ceramic filter that can maximize filtering area within a specific space because modification of a shape and production of a complicated shape are easy.
• the ceramic filter of the present invention has a pore structure wherein surface is dense and inside is sparse, the surface of the ceramic filter has superior heat resistance and abrasion resistance thus can be used at high temperature high pressure. And, total weight is reduced because a filtering layer has dense structure while a back side has sparse structure, dusts are collected at surface to prevent eye-blocking inside of a ceramic filter, the ceramic filter has low pressure loss and high ventilation and dusting efficiency, and the ceramic filter can be easily recycled by heating it at high temperature to burn and remove dusts.
• the ceramic filter of the present invention does not require a heat-exchange device for cooling liquid at high temperature, is very light because of porous structure with pores of 40% or more, dusting efficiency is 99.8% or more, dusting can be conducted with more rapid filtering speed than the existing dusting filter, deterioration or damage of a filter does not occur even at high temperature, high pressure, and it can be easily applied for a waste incinerator, a crematory, a boiler, a cement preparation process, a coal steam power plant, a coal gasification complex power equipment because there is no concern about a fire due to sparks.

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