Disclosure of Invention
The invention aims to provide a high-porosity ceramic filter material, a preparation method and application thereof. The high-porosity ceramic filter material is prepared by using ceramic fibers as main raw materials through plastic molding, drying and sintering, and the raw materials are fibrous and replace the traditional granular raw materials, so that the final ceramic product produced by the high-porosity ceramic filter material has a three-dimensional network structure, and is high in porosity, low in filter resistance, high in breaking strength, high in high temperature resistance and good in corrosion resistance.
Another object of the present invention is to provide a method for preparing a high porosity ceramic filter material, comprising the steps of:
(1) raw material selection
The ceramic fiber is selected as a framework material of the high-porosity ceramic filter material as a raw material, and comprises one or a mixture of more than two of mullite fiber, alumina fiber and aluminum silicate fiber, and a three-dimensional network structure is formed by the cross combination of the ceramic fiber to form a multi-channel coherent air hole; silica powder is selected as a bonding agent, and the ceramic fiber is firmly bonded through reaction with the surface of the ceramic fiber at high temperature, so that the strength of the filter material is improved; the method is characterized in that a carbonaceous material, such as activated carbon, starch or wood dust, especially the activated carbon is selected as a pore-forming agent, and gas generated by oxidizing and burning the pore-forming agent overflows at high temperature, so that pores and continuous through pores are formed in the material, and the porosity of the material is further improved.
(2) Raw material preparation and shaping
Mixing and uniformly stirring ceramic fiber, silicon oxide powder, pore-forming agent and water according to the mass ratio of 30-80: 70-20: 10-50: 30-50, refining the mixture by a pug mill to prepare plastic pug, putting the plastic pug into a closed container for ageing, and forming the mixture by vacuum extrusion forming equipment to obtain hollow tubular and flat blank bodies.
(3) Drying and firing
And (3) placing the extruded blank body in a drying device for drying for 24-48 hours, and firing at 1000-1200 ℃ for 1-3 hours.
In the preparation method of the high-porosity ceramic filter material, the ceramic fiber is one or a mixture of more than two of mullite fiber, alumina fiber and aluminum silicate fiber. Before mixing the materials, the ceramic fibers are firstly subjected to deslagging by a water washing method and then to chopping homogenization treatment, wherein the aspect ratio of the size of the treated fibers is 5-40: 1, preferably 20-40: 1, and most preferably 20-35: 1.
The pore-forming agent is a carbon material, particularly active carbon, and higher porosity can be obtained by oxidizing the pore-forming agent at high temperature and overflowing gas generated by combustion.
The plastic pug is refined by a pug mill, and the ageing time is 24-72 hours, preferably 30-60 hours, so as to obtain the plastic pug with good homogenization.
The drying temperature of the green body is 30-60 ℃, and the drying time is 24-48 hours, preferably 30-40 hours.
The firing temperature is 1000-1200 ℃, and the high-porosity ceramic filter material obtained at the firing temperature has high breaking strength.
By the preparation method, the high-porosity ceramic filter material can be obtained.
The invention also provides a high-porosity ceramic filter material prepared by the method, the aperture of the material is 10-21 mu m, the porosity is 51-89%, the filter resistance at the wind speed of 1 m/min is within the range of 79-162Pa, and the high-porosity ceramic filter material has the characteristics of low filter capacity and high filter efficiency.
The high-porosity ceramic filter material has the flexural strength of 1.2-17.2MPa, can ensure that the filter material does not deform during working, has good durability particularly when used in a high-temperature environment, and can obtain good and stable filtering effect.
The high-porosity ceramic filter material can resist the high temperature of 600 ℃, has good durability and good corrosion resistance, and is particularly suitable for severe working environments, such as industries of smelting, cement, chemical engineering, power plants and the like.
The invention has the beneficial effects that: compared with the porous ceramic produced by the traditional particle raw material, the resistance of the high-porosity ceramic filter material prepared by the method is reduced by hundreds of times; compared with a vacuum filtration molding method, the production process is simple and convenient, and the production efficiency is high; compared with the millimeter-scale porous material prepared by a precursor organic foam method, the pore diameter of the material can reach micron-scale. According to the invention, the silica powder is used as a binding agent, and the ceramic fiber is firmly bound through reaction with the surface of the ceramic fiber at high temperature, so that the strength of the filter material is obviously improved, the service life of the filter material is prolonged, and the use cost is correspondingly reduced; the ceramic fibers are combined in a cross way to form a high-porosity three-dimensional network structure, and the porosity of the ceramic fibers is far higher than that of a traditional porous ceramic filter material prepared from granular raw materials; under the condition of the same filtering precision, the filtering resistance is greatly lower than that of the traditional porous ceramic filtering material. The high-porosity ceramic filter material prepared by the invention does not contain alkali metal and alkaline earth metal ions, has better corrosion resistance, can resist the high temperature of 600 ℃, and can be widely applied to the fields of high-temperature flue gas dust removal, liquid filtration and the like.
Detailed Description
As shown in FIG. 1, the filtration direction of the filter medium is from the outside (10) of the tube to the inside (20) of the tube.
As shown in FIG. 2, the filtration direction of the filter medium is from the outer side (10) of the plate to the inner side (20) of the plate.
The invention is illustrated in further detail by the following examples:
example 1
Mullite fiber with the length-diameter ratio of 10: 1, silicon oxide powder, activated carbon and water are mixed according to the mass ratio of 80: 20: 10: 50 and are uniformly stirred to prepare plastic pug, the plastic pug is aged for 48 hours, extruded and molded, dried for 48 hours at the temperature of 60 ℃, and sintered at the temperature of 1200 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 10 mu m, the porosity is 51 percent, and the breaking strength of a sample is 19.8 MPa. The filtration resistance was 140Pa at a wind speed of 1 m/min.
Example 2
Mixing mullite fiber with the length-diameter ratio of 20: 1, silicon oxide powder, activated carbon and water according to the mass ratio of 70: 30: 10: 35, uniformly stirring to prepare plastic pug, ageing for 60 hours, extruding and molding, drying for 24 hours at 50 ℃, and firing at 1180 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 15 mu m, the porosity is 53%, and the breaking strength of a sample is 17.1 MPa. The filtration resistance was 115Pa at a wind speed of 1 m/min.
Example 3
Mixing and uniformly stirring alumina fiber with the length-diameter ratio of 5: 1, silica powder, activated carbon and water according to the mass ratio of 60: 40: 10: 35 to prepare plastic pug, ageing for 50 hours, extruding and molding, drying for 24 hours at 40 ℃, and sintering at 1150 ℃ to obtain the high-porosity ceramic filter material finished product, wherein the aperture of the high-porosity ceramic filter material is 13 mu m, the porosity is 56%, and the breaking strength of the sample is 15.3 MPa. The filtration resistance was 155Pa at a wind speed of 1 m/min.
Example 4
Mullite fiber with the length-diameter ratio of 5: 1, aluminum silicate fiber, silicon oxide powder, activated carbon and water are mixed and uniformly stirred according to the mass ratio of 40: 10: 50: 10: 35 to prepare plastic pug, the plastic pug is aged for 30 hours, extruded and molded, dried for 30 hours at the temperature of 60 ℃, and sintered at the temperature of 1150 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 12 mu m, the porosity is 54%, and the breaking strength of a sample is 16.9 MPa. The filtration resistance was 162Pa at a wind speed of 1 m/min.
Example 5
Mixing mullite fiber with the length-diameter ratio of 20: 1, silicon oxide powder, activated carbon and water according to the mass ratio of 40: 60: 10: 35, uniformly stirring to prepare plastic pug, ageing for 24 hours, extruding and molding, drying for 40 hours at the temperature of 60 ℃, and sintering at the temperature of 1100 ℃ to obtain the finished product of the high-porosity ceramic filter material, wherein the aperture of the high-porosity ceramic filter material is 21 mu m, the porosity is 53 percent, and the breaking strength of a sample is 17.2 MPa. The filtration resistance 116Pa was at a wind speed of 1 m/min.
Example 6
Mixing and uniformly stirring alumina fiber with the length-diameter ratio of 30: 1, silica powder, activated carbon and water according to the mass ratio of 30: 70: 10: 35 to prepare a plastic pug, ageing for 65 hours, extruding and molding, drying for 35 hours at 55 ℃, and firing at 1000 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the aperture of the high-porosity ceramic filter material is 13 mu m, the porosity is 51%, and the breaking strength of a sample is 15.6 MPa. The filtration resistance was 89Pa at a wind speed of 1 m/min.
Example 7
Mixing and uniformly stirring aluminum silicate fibers with the length-diameter ratio of 35: 1, silicon dioxide, activated carbon and water according to the mass ratio of 30: 70: 30: 41 to prepare plastic pug, ageing for 35 hours, extruding and molding, drying for 72 hours at the temperature of 30 ℃, and sintering at the temperature of 1000 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 16 mu m, the porosity is 72%, and the flexural strength of a sample is 6.1 MPa. The filtration resistance was 82Pa at a wind speed of 1 m/min.
Example 8
Mixing and uniformly stirring aluminum silicate fibers with the length-diameter ratio of 20: 1, silicon dioxide, activated carbon and water according to the mass ratio of 40: 60: 50: 45 to prepare plastic pug, ageing for 42 hours, extruding and molding, drying for 60 hours at 40 ℃, and sintering at 1100 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 18 mu m, the porosity is 89%, and the breaking strength of a sample is 1.2 MPa. The filtration resistance was 79Pa at a wind speed of 1 m/min.
Example 9
Mullite fiber with the length-diameter ratio of 15: 1, alumina fiber, silica powder, activated carbon and water are mixed and uniformly stirred according to the mass ratio of 65: 5: 30: 10: 35 to prepare plastic pug, the plastic pug is aged for 24 hours, extruded and molded, dried for 48 hours at the temperature of 60 ℃, and sintered at the temperature of 1180 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 14 mu m, the porosity is 56%, and the breaking strength of a sample is 17.4 MPa. The filtration resistance at a wind speed of 1 m/min was 118 Pa.
Example 10
Mullite fiber, alumina fiber, aluminum silicate fiber, silicon oxide powder, active carbon and water with the length-diameter ratio of 20: 1 are mixed and evenly stirred according to the mass ratio of 60: 5: 30: 10: 35 to prepare plastic pug, the plastic pug is aged for 36 hours, extruded and molded and dried for 72 hours at the temperature of 35 ℃, and the mixture is sintered at the temperature of 1160 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 15 mu m, the porosity is 55%, and the breaking strength of a sample is 17.4 MPa. The filtration resistance was 121Pa at a wind speed of 1 m/min.
Example 11
Mixing and uniformly stirring aluminum silicate fibers with the length-diameter ratio of 40: 1, silicon dioxide, activated carbon and water according to the mass ratio of 40: 60: 50: 45 to prepare plastic pug, ageing for 40 hours, extruding and molding, drying for 48 hours at 50 ℃, and sintering at 1050 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 18 mu m, the porosity is 85%, and the breaking strength of a sample is 1.5 MPa. The filtration resistance was 87Pa at a wind speed of 1 m/min.
Example 12
Mixing and uniformly stirring aluminum silicate fibers with the length-diameter ratio of 10: 1, silicon dioxide, activated carbon and water according to the mass ratio of 40: 60: 50: 45 to prepare plastic pug, ageing for 32 hours, extruding and molding, drying for 72 hours at 40 ℃, and sintering at 1050 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 19 mu m, the porosity is 82%, and the breaking strength of a sample is 1.7 MPa. The filtration resistance was 101Pa at a wind speed of 1 m/min.
Example 13
Mixing and uniformly stirring alumina fiber with the length-diameter ratio of 5: 1, silica powder, activated carbon and water according to the mass ratio of 60: 40: 10: 30 to prepare plastic pug, ageing for 40 hours, extruding and molding, drying for 48 hours at 50 ℃, and firing at 1180 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the aperture of the high-porosity ceramic filter material is 15 mu m, the porosity is 54%, and the breaking strength of a sample is 15.5 MPa. The filtration resistance was 162Pa at a wind speed of 1 m/min.
Example 14
Mullite fiber with the length-diameter ratio of 10: 1, silicon oxide powder, activated carbon and water are mixed according to the mass ratio of 80: 20: 40 and are uniformly stirred to prepare plastic pug, the plastic pug is aged for 24 hours, extruded and molded, dried for 48 hours at the temperature of 50 ℃, and sintered at the temperature of 1200 ℃ to obtain a high-porosity ceramic filter material finished product, wherein the pore diameter of the high-porosity ceramic filter material is 12 mu m, the porosity is 53 percent, and the breaking strength of a sample is 18.7 MPa. The filtration resistance was 146Pa at a wind speed of 1 m/min.
The method can conveniently produce the porous high-temperature-resistant ceramic filter material, passes the middle-scale test at present, enters the production stage, and can realize industrialization.
The high-temperature ceramic filter tube prepared by the method can be prepared into a required length according to industrial application requirements, the length prepared by other methods in the prior art is generally 1500-plus-2000 mm, the length of the filter tube prepared by the method can reach 5000mm, and the tube diameter can reach 120-plus-150 mm. Due to the transportation constraints, it is typically 2800mm in practice.