A method and device for preparing pure alumina porous ceramics

Abstract

The present invention discloses a method and equipment for preparing pure alumina porous ceramics, belonging to the technical field of porous ceramic preparation. The preparation method adopts unique atomization and fluffing, pressing and high-temperature sintering technology to prepare lightweight and energy-saving pure alumina porous ceramics with high temperature resistance. The present invention provides pure alumina porous ceramics, which do not contain silicon dioxide materials in the raw materials and are formed by high-temperature calcination. When used as furnace lining, they can be used in a high-temperature pure hydrogen calcining furnace, and will not react with hydrogen at high temperatures, thereby avoiding problems such as powder loss and crispness caused by silicon dioxide reduction, avoiding damage to the furnace lining, and eliminating safety hazards when the furnace is used; the centrifugal equipment provided by the present invention can realize drying, crushing, screening and mixing of materials while centrifugally separating the materials, thereby increasing the function of the equipment, improving the practicability of the equipment, and having good promotion value.

Description

Technical Field

[0001] The invention belongs to the technical field of porous ceramic preparation, and specifically relates to a method and equipment for preparing pure alumina porous ceramic. Background Art

[0002] Porous ceramics are a new type of ceramic material with pore wall structure and three-dimensional interconnected channels in the matrix. It is a multifunctional material that integrates high porosity, high specific surface area, low volume density, low thermal conductivity and other properties. It also has the inherent properties of ceramic materials such as high temperature resistance, acid and alkali resistance, long life, and high strength. Based on the excellent properties of porous ceramics, they have been widely used in thermal insulation materials, catalyst carriers, filter materials, sound absorption materials, energy storage and conversion materials, etc.

[0003] In the field of thermal insulation, one of the major applications of porous ceramics is as thermal insulation lining materials for industrial kilns. Kiln linings are generally made up of insulation layers and working layers. The working layer is made of heavy refractory bricks or heavy castables, because heavy refractory bricks and castables have high volume density and fast heat dissipation. Therefore, most furnace linings will use insulation layers on the inner wall of the furnace shell to strengthen the heat dissipation speed of the lining.

[0004] When porous ceramic materials are used as furnace linings in a pure hydrogen calcining furnace, since the porous ceramic materials contain silicon dioxide, hydrogen will react with silicon dioxide at high temperatures to reduce the silicon dioxide, causing the furnace lining materials to lose powder, become brittle, and other problems, causing the furnace lining to be damaged, posing a huge safety hazard; at the same time, centrifugal equipment is required when preparing porous ceramic materials, but the existing centrifugal equipment has a single function, and the materials after centrifugal separation will have micro-agglomeration problems, resulting in uneven mixing of the materials, affecting the preparation effect of porous ceramics. Since the ceramic material needs to withstand high temperatures when used as a furnace lining in a pure hydrogen calcining furnace, there are safety hazards when the ceramic material prepared with uneven mixing of the materials is used as a furnace lining.

[0005] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a method and equipment for preparing pure alumina porous ceramics, which can solve the problem that porous ceramics can be reduced when used as furnace lining in a pure hydrogen calcining furnace and the problem that centrifugal equipment has a single function in preparing porous ceramics.

[0007] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0008] A method for preparing pure alumina porous ceramics, the preparation method comprising:

[0009] S1. Take the raw materials according to the mass ratio: high-purity low-sodium α-alumina, gelatinized starch, ammonium bicarbonate, phenolic resin, water and polyaluminium chloride sol for later use;

[0010] S2, putting each raw material into a ball mill mixer for grinding and mixing to obtain a liquid slurry; putting the raw materials taken according to the mass ratio into the ball mill mixer in sequence, and grinding and mixing in the ball mill mixer;

[0011] S3. The liquid slurry is put into a centrifugal device, and the liquid slurry is dried, crushed and screened by the centrifugal components in the centrifugal device to obtain fluffy spherical particles. The centrifugal device uses the centrifugal principle to centrifugally separate the liquid slurry, and the liquid slurry is dried, crushed and screened by the centrifugal components during screening. Specifically, the atomization fluffing technology is used to input the liquid slurry into a high-speed rotating centrifugal device, and the liquid material is thrown out at high speed from the through holes on the centrifugal components in the form of mist droplets, and is expanded and dried under the action of hot air spray to obtain fluffy spherical particles.

[0012] S4. Add the fluffy spherical pellets into a calcining furnace, heat and calcine them in the calcining furnace to obtain fluffy spherical powder; burn off most of the organic matter, crystal water and other decomposable substances by calcination to obtain fluffy spherical powder; specifically, the decomposition of gelatinized starch and ammonium bicarbonate and the expansion of gas give the spherical powder a fluffy porous structure, the carbonization residue of phenolic resin and the solidification of aluminum sol give the spherical powder a skeleton supporting force to prevent it from collapsing into a compact and dense body.

[0013] S5. Put the fluffy spherical powder, high-purity alumina chopped fibers and high-purity low-sodium α-alumina micropowder into a stirring device according to the mass ratio to obtain a mixture, add polyvinyl alcohol aqueous solution into the mixture to obtain a molding solid, and then add the molding solid to a metal mold and press to obtain a porous ceramic embryo; wherein the purity of the high-purity alumina chopped fibers is as high as 99.7%.

[0014] S6. Add the porous ceramic body into the calcining furnace and obtain pure alumina porous ceramics by calcining. The prepared pure alumina porous ceramic material has an Al2O3 content of ≥99.7%, a corundum phase, a porosity of 80-87%, a volume density of 0.5-0.8 g / cm3, and a permanent linear change of ≤0.5% at 1700℃×12h. It is used as a furnace material for pure hydrogen calcining furnaces above 1700℃ and has a long-term temperature resistance of above 1700℃.

[0015] In one or more embodiments of the present invention, the mass ratio of the raw materials in S1 is 100:5~10:2~5:3~6:30~50:5~10, and the Al2O3 content of the high-purity low-sodium α-alumina micropowder is ≥99.7%, the Na2O content is ≤0.08%, and the D50 is 1~5 microns.

[0016] In one or more embodiments of the present invention, when the centrifugal assembly dries the liquid slurry, the temperature of the hot air used is controlled at 60-80°C.

[0017] In one or more embodiments of the present invention, the temperature of the calcining furnace in S4 is controlled at 600-800°C, so as to burn off most of the organic matter, crystal water and other decomposable substances to obtain fluffy spherical powder; the temperature of the calcining furnace in S6 is controlled at 1700-1800°C, so that it can be used as a furnace material for a pure hydrogen calcining furnace above 1700°C and can withstand temperatures above 1700°C for a long time.

[0018] In one or more embodiments of the present invention, the mass ratio of the fluffy spherical powder, the high-purity alumina chopped fibers and the high-purity low-sodium α-alumina micropowder in S5 is 100:10~30:10~30.

[0019] A pure alumina porous ceramic preparation device, applied to a pure alumina porous ceramic preparation method, the device comprises a ball mill mixer, a centrifugal device, a calcining furnace, a metal mold and a stirring device;

[0020] Wherein, the centrifugal device comprises:

[0021] The centrifugal device body comprises an outer shell, the inner side wall of which is fixedly connected with a partition plate, which divides the outer shell into two parts, the upper part is used for screening and mixing materials, and the lower part is a power component for driving the device to rotate.

[0022] A centrifugal assembly comprises a first centrifugal cylinder and a second centrifugal cylinder, wherein the first centrifugal cylinder and the second centrifugal cylinder are used to perform multiple centrifugal separations on materials so as to improve the effect of centrifugal separations on materials; the first centrifugal cylinder and the second centrifugal cylinder are rotatably mounted in an outer shell, and the first centrifugal cylinder and the second centrifugal cylinder perform centrifugal separations on materials by rotation; the second centrifugal cylinder is arranged on the outer side of the first centrifugal cylinder, and the materials are centrifugally separated once by the first centrifugal cylinder, and the materials are centrifugally separated twice by the second centrifugal cylinder; a plurality of first sieve holes are arranged in an annular manner from top to bottom on the side wall of the first centrifugal cylinder, and a plurality of second sieve holes are arranged in an annular manner from top to bottom on the second centrifugal cylinder;

[0023] The accessory component comprises a mounting shell, wherein the mounting shell is rotatably mounted on the second centrifugal cylinder, so that the installation of the mounting shell will not affect the rotation of the second centrifugal cylinder.

[0024] In one or more embodiments of the present invention, a motor is installed on the bottom wall plate of the outer shell, a driving shaft is installed on the output end of the motor, a first bearing is installed on the partition plate, the driving shaft is sleeved in the first bearing, and the upper end of the first bearing is fixedly connected to the bottom of the first centrifugal cylinder. The motor drives the driving shaft to rotate, and the rotation of the driving shaft drives the first centrifugal cylinder to rotate, so that the first centrifugal cylinder and the second centrifugal cylinder rotate to centrifuge the material.

[0025] In one or more embodiments of the present invention, a return port is provided on the bottom wall plate of the first centrifugal cylinder. When the first centrifugal cylinder rotates at high speed to screen the material, negative pressure is generated in the first centrifugal cylinder, so that the material after centrifugal separation in the second centrifugal cylinder can re-enter the first centrifugal cylinder through the return port, so as to re-centrifuge the material in the first centrifugal cylinder; the aperture sizes of the first sieve holes on the same ring are the same, and the aperture sizes of the first sieve holes on different rings are arranged in a manner that gradually decreases from top to bottom, thereby improving the efficiency and effect of the first centrifugal cylinder in centrifuging the material.

[0026] In one or more embodiments of the present invention, a plurality of hot air conveying grooves and a plurality of negative pressure grooves are arranged in the second centrifugal cylinder, and the plurality of hot air conveying grooves and the plurality of negative pressure grooves are respectively arranged above the second sieve holes on the same ring, and hot air is provided to the second sieve holes through the hot air conveying grooves, and negative pressure is provided to the second sieve holes through the negative pressure grooves; a pair of hot air nozzles are arranged on the inner side walls of the second sieve holes in an up-and-down staggered manner, and the pair of hot air nozzles are respectively connected to the hot air conveying grooves above and below the corresponding second sieve holes, so that the hot air in the hot air conveying grooves can be conveyed to the second sieve holes through the hot air nozzles, and at the same time, a pair of hot air nozzles are arranged in the second sieve holes. The hot air nozzles are arranged in a staggered manner so that the hot air can be ejected into the second sieve holes to form a wind wall, which can crush and dry the material passing through the second sieve holes; a pair of suction nozzles are arranged on the inner wall of the second sieve holes in a staggered manner, and the pair of suction nozzles are respectively connected to the negative pressure grooves above and below the corresponding second sieve holes, so that the negative pressure in the negative pressure groove will absorb the air outside the suction nozzle, and the pair of hot air nozzles and the pair of suction nozzles are staggered with each other, so that the hot air ejected from the relative hot air nozzles can be sucked in through the suction nozzles, so as to absorb the hot air and the moisture generated by the hot air drying, and the suction nozzles will not absorb the material. The upper and lower sides of the inner wall of the second sieve hole are fixedly connected with a shielding plate, and the hot air nozzle and the suction nozzle on the same side are shielded by the shielding plate to prevent the suction nozzle from adsorbing the hot air ejected from the hot air nozzle and affecting the formation of the wind wall; the suction nozzle is tilted away from the hot air nozzle on the same side, and the suction nozzle is tilted to further reduce the suction nozzle's adsorption of the hot air ejected from the hot air nozzle on the same side, and the hot air nozzle is arranged in a vertical direction, and the inclination angle of the suction nozzle is 45 to 60 degrees, preferably 45 degrees. A plurality of hot air inlet grooves are arranged between the plurality of hot air conveying grooves, and the hot air outside is conveyed into the hot air conveying groove through the hot air inlet groove, so as to provide hot air to the second sieve hole through the hot air nozzle; a plurality of vacuum connecting grooves are arranged between the plurality of negative pressure grooves, and the negative pressure outside is conveyed into the hot air conveying groove through the vacuum connecting groove, so as to provide negative pressure to the second sieve hole through the negative pressure groove.

[0027] In one or more embodiments of the present invention, a second bearing is installed on the outer wall of the upper end of the second centrifugal cylinder, and the inner side of one side wall plate of the mounting shell is installed on the outer wall of the second bearing. Under the action of the second bearing, the mounting shell is installed on the second centrifugal cylinder without affecting the rotation of the second centrifugal cylinder; the other side wall plate of the mounting shell is installed on the inner wall of the second centrifugal cylinder, and the inner side of the wall plate of the mounting shell installed on the inner wall of the second centrifugal cylinder is provided with a polishing plate, and the polishing plate makes the rotation of the second centrifugal cylinder not affected by the side wall of the mounting shell, and the second bearing can also be installed on the side wall provided with the polishing plate to achieve this function. A chamber is formed between the upper end wall plate of the mounting shell and the upper side wall of the second centrifugal cylinder, and a blocking plate is fixedly connected in the chamber, and the blocking plate divides the chamber into a hot air chamber and a vacuum chamber, and the hot air chamber is used to provide hot air to the second centrifugal cylinder to form a wind wall to crush and dry the material, and the vacuum chamber is used to provide negative pressure to the second centrifugal cylinder, and the hot air after the wind wall is formed and the water vapor evaporated by the hot air are sucked out by the negative pressure. The upper end of the hot air chamber is equipped with a plurality of hot air delivery pipes, and a hot air blower is installed at the air inlet of the plurality of hot air delivery pipes. The hot air generated by the hot air blower is delivered to the hot air chamber through the plurality of hot air delivery pipes; the upper end of the vacuum chamber is equipped with a plurality of negative pressure pipes, and a vacuum device is installed at the entrance of the plurality of negative pressure pipes. The vacuum device forms a negative pressure in the vacuum chamber through the plurality of negative pressure pipes. The plurality of hot air inlet grooves are all connected to the hot air chamber, and the hot air in the hot air chamber is delivered to the hot air delivery groove through the hot air inlet groove; the plurality of vacuum connecting grooves are all connected to the vacuum chamber, and the negative pressure in the vacuum chamber is formed in the negative pressure groove through the vacuum connecting groove.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] The present invention provides a pure alumina porous ceramic. Since the raw material does not contain silicon dioxide and is formed by high-temperature calcination, when used as a furnace lining, it can be used in a high-temperature pure hydrogen calcining furnace. It will not undergo a reduction reaction with hydrogen at high temperatures, thereby avoiding problems such as powder loss and crispness caused by silicon dioxide reduction, avoiding damage to the furnace lining, and eliminating potential safety hazards when the furnace is used.

[0030] The centrifugal device provided by the present invention centrifuges materials by arranging a double-layer centrifugal cylinder, and the sieve holes of the outer centrifugal cylinder are provided with hot air nozzles and air suction nozzles, and a high-temperature wind wall is formed in the sieve holes by the hot air nozzle, and the centrifugally separated materials are crushed and dried by the wind wall, and the materials are centrifugally separated for many times in the centrifugal device, so that the materials are dried, crushed and screened thoroughly, thereby avoiding the problem of micro-agglomeration of the materials after centrifugation, and making the materials thoroughly mixed and uniform, thereby improving the preparation effect of porous ceramics, and making the prepared ceramic material have excellent performance when used as a furnace lining;

[0031] The centrifugal equipment provided by the present invention can realize drying, crushing, screening and mixing of materials while centrifuging the materials, thereby increasing the functions of the equipment and improving the practicability of the equipment. At the same time, the preparation process of pure alumina porous ceramics is reduced through the centrifugal equipment, thereby greatly shortening the preparation time and further shortening the preparation cost, and has good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 This is a flow chart of a method for preparing pure alumina porous ceramics in one embodiment of the present invention;

[0034] Figure 2 It is a front view of a pure alumina porous ceramic preparation device in one embodiment of the present invention;

[0035] Figure 3 A three-dimensional diagram of a pure alumina porous ceramic preparation device in one embodiment of the present invention;

[0036] Figure 4 A cross-sectional view of a pure alumina porous ceramic preparation device according to an embodiment of the present invention;

[0037] Figure 5 A cross-sectional view of a pure alumina porous ceramic preparation device according to an embodiment of the present invention;

[0038] Figure 6 In one embodiment of the present invention Figure 5 The enlarged view of point A in the middle;

[0039] Figure 7 An exploded view of the centrifugal assembly and the mounting shell in one embodiment of the present invention;

[0040] Figure 8 Schematic diagram of the structure of the second sieve hole in one embodiment of the present invention.

[0041] Description of main reference numerals:

[0042] 1-centrifugal equipment body, 11-outer shell, 12-partition plate, 13-motor, 14-drive shaft, 15-first bearing, 2-centrifugal assembly, 21-first centrifugal cylinder, 2101-first sieve hole, 22-second centrifugal cylinder, 2201-second sieve hole, 2202-hot air conveying trough, 2203-hot air nozzle, 2204-negative pressure trough, 2205-suction nozzle, 2206-shielding plate, 2207-hot air inlet trough, 2208-vacuum connecting trough, 23-return port, 3-accessory assembly, 31-mounting shell, 32-second bearing, 33-chamber, 34-blocking plate, 35-polishing plate, 36-hot air conveying pipe, 37-hot air blower, 38-negative pressure pipe, 39-vacuum device. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments 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 creative work should fall within the scope of protection of the present invention.

[0044] like Figure 1 As shown, a method for preparing a pure alumina porous ceramic in one embodiment of the present invention includes:

[0045] S1. Take the raw materials according to the mass ratio: high-purity low-sodium α-alumina, gelatinized starch, ammonium bicarbonate, phenolic resin, water and polyaluminium chloride sol for later use;

[0046] Specifically, the mass ratio of the raw materials in S1 is 100:5~10:2~5:3~6:30~50:5~10: high-purity low-sodium α-alumina: gelatinized starch: ammonium bicarbonate: phenolic resin: water: polyaluminum chloride sol.

[0047] At the same time, the Al2O3 content in the high-purity low-sodium α-alumina micropowder is ≥99.7%, the Na2O content is ≤0.08%, and the D50 is 1~5 microns.

[0048] S2, putting each raw material into a ball mill mixer for grinding and mixing to obtain a liquid slurry; putting the raw materials taken according to the mass ratio into the ball mill mixer in sequence, and grinding and mixing in the ball mill mixer;

[0049] Specifically, when the ball mill mixer is in use, its speed should be set to be greater than 85% of the rated speed, so that the ball mill mixer can achieve better mixing and grinding effects on the raw materials.

[0050] S3. The liquid slurry is put into a centrifugal device, and the liquid slurry is dried, crushed and screened by the centrifugal components in the centrifugal device to obtain fluffy spherical particles. The centrifugal device uses the centrifugal principle to centrifugally separate the liquid slurry, and the liquid slurry is dried, crushed and screened by the centrifugal components during screening. Specifically, the atomization fluffing technology is used to input the liquid slurry into a high-speed rotating centrifugal device, and the liquid material is thrown out at high speed from the through holes on the centrifugal components in the form of mist droplets, and is expanded and dried under the action of hot air spray to obtain fluffy spherical particles.

[0051] Preferably, when the centrifugal assembly dries the liquid slurry, the temperature of the hot air used is controlled at 60-80°C; at the same time, when the centrifugal equipment centrifuges the liquid slurry, the speed is set to 85%-90% of the rated speed, and the time is set to 2-3 hours.

[0052] S4. Add the fluffy spherical pellets into a calcining furnace, heat and calcine them in the calcining furnace to obtain fluffy spherical powder; burn off most of the organic matter, crystal water and other decomposable substances by calcination to obtain fluffy spherical powder; specifically, the decomposition of gelatinized starch and ammonium bicarbonate and the expansion of gas give the spherical powder a fluffy porous structure, the carbonization residue of phenolic resin and the solidification of aluminum sol give the spherical powder a skeleton supporting force to prevent it from collapsing into a compact and dense body.

[0053] Furthermore, the temperature of the calcining furnace in S4 is controlled at 600-800° C., thereby burning off most of the organic matter, crystal water and other decomposable substances to obtain fluffy spherical powder.

[0054] S5. Put the fluffy spherical powder, high-purity alumina chopped fibers and high-purity low-sodium α-alumina micropowder into a stirring device according to the mass ratio to obtain a mixture, add polyvinyl alcohol aqueous solution into the mixture to obtain a molding solid, and then add the molding solid to a metal mold and press to obtain a porous ceramic embryo; wherein the purity of the high-purity alumina chopped fibers is as high as 99.7%.

[0055] Furthermore, when the stirring device mixes the materials in S5, the speed is set to 75% to 80% of the rated speed and the time is set to 0.5 to 1 hour.

[0056] Preferably, the mass ratio of the fluffy spherical powder, the high-purity alumina chopped fibers and the high-purity low-sodium α-alumina micropowder in S5 is 100:10~30:10~30.

[0057] S6. Add the porous ceramic body into the calcining furnace and obtain pure alumina porous ceramics by calcining. The prepared pure alumina porous ceramic material has an Al2O3 content of ≥99.7%, a corundum phase, a porosity of 80-87%, a volume density of 0.5-0.8 g / cm3, and a permanent linear change of ≤0.5% at 1700℃×12h. It is used as a furnace material for pure hydrogen calcining furnaces above 1700℃ and has a long-term temperature resistance of above 1700℃.

[0058] Specifically, the temperature of the calcining furnace in S6 is controlled at 1700-1800°C, so that it can be used as a furnace material for a pure hydrogen calcining furnace above 1700°C and can withstand temperatures above 1700°C for a long time.

[0059] Preferably, the present invention provides pure alumina porous ceramics. Since the raw materials thereof do not contain silicon dioxide material and the ceramics are formed by high-temperature calcination, the ceramics can be used as furnace linings in high-temperature pure hydrogen calcining furnaces. The ceramics will not undergo reduction reaction with hydrogen at high temperatures, thus avoiding problems such as powdering and crisping caused by silicon dioxide reduction, thus avoiding damage to the furnace lining and eliminating potential safety hazards during furnace use. At the same time, the pure alumina porous ceramics can be used as corrosion-resistant furnace linings due to their good resistance to high-temperature corrosion by chromium oxide and sodium oxide, and are used to calcine ceramic products with high chromium and sodium content.

[0060] like Figure 2~Figure 5 As shown, a pure alumina porous ceramic preparation device in one embodiment of the present invention is applied to a pure alumina porous ceramic preparation method, and the preparation device includes a ball mill mixer, a centrifugal device, a calcining furnace, a metal mold and a stirring device.

[0061] Among them, Figure 2~Figure 5 As shown, the centrifugal device includes a centrifugal device body 1, a centrifugal component 2 and an auxiliary component 3.

[0062] like Figure 4 and Figure 5 As shown, the centrifugal device body 1 includes an outer shell 11, and a partition plate 12 is fixedly connected to the inner wall of the outer shell 11. The partition plate 12 divides the outer shell 11 into two parts, the upper part is used for screening and mixing materials, and the lower part is a power component for driving the device to rotate.

[0063] like Figure 4 and Figure 5As shown, a motor 13 is installed on the bottom wall plate of the outer shell 11, a driving shaft 14 is installed on the output end of the motor 13, a first bearing 15 is installed on the partition plate 12, the driving shaft 14 is sleeved in the first bearing 15, and the upper end of the first bearing 15 is fixedly connected to the bottom of the first centrifugal cylinder 21. The driving shaft 14 is driven to rotate by the motor 13, and the rotation of the driving shaft 14 drives the first centrifugal cylinder 21 to rotate, so that the first centrifugal cylinder 21 and the second centrifugal cylinder 22 rotate to centrifuge the material.

[0064] like Figure 4 , Figure 5 and Figure 7 As shown, the centrifugal assembly 2 includes a first centrifugal cylinder 21 and a second centrifugal cylinder 22, which are used to perform multiple centrifugal separations on the material so as to improve the effect of centrifugal separation of the material; the first centrifugal cylinder 21 and the second centrifugal cylinder 22 are rotatably installed in the outer shell 11, and the first centrifugal cylinder 21 and the second centrifugal cylinder 22 perform centrifugal separations on the material by rotation; the second centrifugal cylinder 22 is arranged on the outer side of the first centrifugal cylinder 21, and the material is centrifuged once by the first centrifugal cylinder 21, and the material is centrifuged twice by the second centrifugal cylinder 22; a plurality of first sieve holes 2101 are arranged in an annular manner from top to bottom on the side wall of the first centrifugal cylinder 21, and the material in the first centrifugal cylinder 21 is thrown out by the first sieve holes 2101, and a plurality of second sieve holes 2201 are arranged in an annular manner from top to bottom on the second centrifugal cylinder 22, and the material in the second centrifugal cylinder 22 is thrown out by the centrifugal force through the second sieve holes 2201.

[0065] like Figure 4 and Figure 5 As shown, a return port 23 is provided on the bottom wall plate of the first centrifugal cylinder 21. When the first centrifugal cylinder 21 rotates at a high speed to screen the material, a negative pressure is generated in the first centrifugal cylinder 21, so that the material after centrifugal separation in the second centrifugal cylinder 22 can re-enter the first centrifugal cylinder 21 through the return port 23, so that the material can be centrifuged again in the first centrifugal cylinder 21.

[0066] Preferably, in order to increase the effect of the centrifugal equipment on the centrifugal separation of materials, so that the materials can be fully dried, crushed, screened and mixed, so as to avoid the occurrence of micro-agglomeration during the centrifugal separation of the materials, a return port 23 is provided so that the materials after centrifugal separation by the first centrifugal cylinder 21 and the second centrifugal cylinder 22 can re-enter the first centrifugal cylinder 21 for centrifugal separation again.

[0067] Preferably, the apertures of the first sieve holes 2101 on the same ring are the same, and the apertures of the first sieve holes 2101 on different rings are arranged in a manner of gradually decreasing from top to bottom, thereby improving the efficiency and effect of the first centrifugal drum 21 when centrifuging the material. When the first centrifugal drum 21 centrifuges the material, large particles are thrown out through the first sieve holes 2101 above the first centrifugal drum 21, and small particles of the material are thrown out through the first sieve holes 2101 below the first centrifugal drum 21.

[0068] like Figure 5 Combination Figure 6 As shown, a plurality of hot air conveying grooves 2202 and a plurality of negative pressure grooves 2204 are arranged in the second centrifugal cylinder 22. The plurality of hot air conveying grooves 2202 and the plurality of negative pressure grooves 2204 are respectively arranged above the second sieve holes 2201 on the same ring. Hot air is provided to the second sieve holes 2201 through the hot air conveying grooves 2202, and negative pressure is provided to the second sieve holes 2201 through the negative pressure grooves 2204.

[0069] Specifically, Figure 8 As shown, a pair of hot air nozzles 2203 are arranged on the inner wall of the second sieve hole 2201 in an up-and-down staggered manner, and the pair of hot air nozzles 2203 are respectively connected with the hot air conveying grooves 2202 above and below the corresponding second sieve hole 2201, and the hot air in the hot air conveying grooves 2202 can be conveyed to the second sieve hole 2201 through the hot air nozzles 2203. At the same time, a pair of hot air nozzles 2203 are arranged in the second sieve hole 2201 in an up-and-down staggered manner, so that the hot air nozzles 2203 can spray hot air into the second sieve hole 2201 to form a wind wall, so that the material passing through the second sieve hole 2201 can be crushed and dried.

[0070] Further, such as Figure 8 As shown, a pair of suction nozzles 2205 are arranged on the inner side wall of the second sieve hole 2201 in an up-and-down staggered manner, and the pair of suction nozzles 2205 are respectively connected to the negative pressure grooves 2204 above and below the corresponding second sieve hole 2201, so that the negative pressure in the negative pressure groove 2204 will adsorb the air outside the suction nozzle 2205, and the pair of hot air nozzles 2203 and the pair of suction nozzles 2205 are arranged staggered with each other, so that the hot air sprayed by the relative hot air nozzles 2203 can be sucked in through the suction nozzle 2205, so as to adsorb the hot air and the moisture generated by the hot air drying, and the suction nozzle 2205 is provided with a protective component so that it will not adsorb the material. At the same time, the centrifugal force that throws the material out of the second sieve hole 2201 is greater than the gas pressure of the wind wall, so the wind wall will not intercept the material.

[0071] Preferably, when the material is thrown out by the centrifugal force of the second centrifugal cylinder 22, since the liquid slurry added to the centrifugal device needs to be expanded and dried by the action of hot air blowing, a wind wall formed by hot air provided by the hot air nozzle 2203 is provided in the second sieve hole 2201, which can dry the centrifuged material, and the material will be broken by the wind wall, so that the material is dried while avoiding micro-agglomeration. The hot air blower and water vapor after the material is dried will be absorbed by the suction nozzle 2205 to extract the moisture.

[0072] Further, such as Figure 8 As shown, baffle plates 2206 are fixedly connected to the upper and lower sides of the inner wall of the second sieve hole 2201, and the hot air nozzle 2203 and the air suction nozzle 2205 on the same side are shielded by the baffle plates 2206 to prevent the air suction nozzle 2205 from absorbing the hot air ejected from the hot air nozzle 2203 and affecting the formation of the wind wall.

[0073] Preferably, Figure 8 As shown, the air suction nozzle 2205 is tilted away from the hot air nozzle 2203 on the same side, and the air suction nozzle 2205 is tilted to further reduce the suction of the hot air ejected by the hot air nozzle 2203 on the same side by the air suction nozzle 2205, and the hot air nozzle 2203 is arranged in a vertical direction, so that the wind wall formed by the pair of hot air nozzles 2203 fully covers the second sieve hole 2201. Figure 8 shown in , both being located on the upper or lower side.

[0074] Preferably, the suction nozzle 2205 is arranged at an inclination angle of 45 to 60 degrees, preferably 45 degrees.

[0075] like Figure 7 As shown, a plurality of hot air inlet grooves 2207 are arranged between the plurality of hot air conveying grooves 2202, and the external hot air is conveyed into the hot air conveying grooves 2202 through the hot air inlet grooves 2207, so as to provide hot air to the second sieve holes 2201 through the hot air nozzles 2203; a plurality of vacuum connecting grooves 2208 are arranged between the plurality of negative pressure grooves 2204, and the external negative pressure is conveyed into the hot air conveying grooves 2202 through the vacuum connecting grooves 2208, so as to provide negative pressure to the second sieve holes 2201 through the negative pressure grooves 2204.

[0076] like Figure 5~Figure 7 As shown, the accessory assembly 3 includes a mounting shell 31 , and the mounting shell 31 is rotatably mounted on the second centrifugal cylinder 22 , so that the installation of the mounting shell 31 does not affect the rotation of the second centrifugal cylinder 22 .

[0077] like Figure 5~Figure 7As shown, a second bearing 32 is installed on the outer side wall of the upper end of the second centrifugal cylinder 22, and the inner side of one side wall plate of the mounting shell 31 is installed on the outer side wall of the second bearing 32. Under the action of the second bearing 32, the mounting shell 31 is installed on the second centrifugal cylinder 22 without affecting the rotation of the second centrifugal cylinder 22; the other side wall plate of the mounting shell 31 is installed on the inner side wall of the second centrifugal cylinder 22, and a polishing plate 35 is provided on the inner side of the wall plate of the mounting shell 31 installed on the inner side wall of the second centrifugal cylinder 22. The polishing plate 35 makes the rotation of the second centrifugal cylinder 22 not affected by the side wall of the mounting shell 31, and the second bearing 32 can also be installed on the side wall where the polishing plate 35 is provided to achieve this function. At the same time, the second bearing 32 and the polishing plate 35 make the mounting shell 31 installed on the second centrifugal cylinder 22 have better sealing performance, so that the pressure of the hot air can reach the set requirements and the vacuum degree can reach the set requirements.

[0078] like Figure 5 Combination Figure 6 As shown, a chamber 33 is formed between the upper end wall plate of the mounting shell 31 and the upper side wall of the second centrifugal cylinder 22, and a baffle plate 34 is fixedly connected to the chamber 33. The baffle plate 34 divides the chamber 33 into a hot air chamber and a vacuum chamber. The hot air chamber is used to provide hot air to the second centrifugal cylinder 22 to form a wind wall to crush and dry the material, and the vacuum chamber is used to provide negative pressure to the second centrifugal cylinder 22 to suck out the hot air after the wind wall is formed and the water vapor evaporated from the hot air through the negative pressure.

[0079] Further, such as Figure 2~Figure 4 As shown, a plurality of hot air delivery pipes 36 are installed at the upper end of the hot air chamber, and a hot air blower 37 is installed at the air inlet of the plurality of hot air delivery pipes 36. The hot air generated by the hot air blower 37 is transported to the hot air chamber through the plurality of hot air delivery pipes 36; a plurality of negative pressure pipes 38 are installed at the upper end of the vacuum chamber, and a vacuum device 39 is installed at the inlet of the plurality of negative pressure pipes 38. The vacuum device 39 forms a negative pressure in the vacuum chamber through the plurality of negative pressure pipes 38.

[0080] like Figure 7 As shown, multiple hot air inlet grooves 2207 are all connected to the hot air chamber, and the hot air in the hot air chamber is transported to the hot air transport groove 2202 through the hot air inlet grooves 2207; multiple vacuum connecting grooves 2208 are all connected to the vacuum chamber, and the negative pressure in the vacuum chamber is formed in the negative pressure groove 2204 through the vacuum connecting grooves 2208.

[0081] It should be understood that a feed port is provided at the upper end of the outer shell 11, and a discharge port is provided on the side wall of the outer shell 11 to facilitate the entry and exit of materials before centrifugal separation. At the same time, a sealing cover is provided on the first centrifugal cylinder 21 and the second centrifugal cylinder 22 to prevent the materials from being thrown out from the upper end during centrifugal separation.

[0082] When in use, the material to be centrifuged is added into the first centrifugal cylinder 21, and the first centrifugal cylinder 21 is driven to rotate at a high speed by the motor 13, and the material will be thrown out through the first sieve hole 2101 under the action of centrifugal force, and the material will be broken when it is thrown out through the first sieve hole 2101; then the material is thrown out through the second sieve hole 2201 by the centrifugal force of the second centrifugal cylinder 22, and when the material passes through the second sieve hole 2201, the hot air nozzle 2203 provides a pressurized high-temperature wind wall, so that the material will be broken and dried when passing through; the material thrown out by the hot air nozzle 2203 will be sucked into the first centrifugal cylinder 21 by negative pressure through the return port 23, so that it can be centrifugally separated again in the first centrifugal cylinder 21, and the material can be centrifugally separated multiple times, so that the material is fully dried, broken and mixed, and micro-agglomeration of the material is avoided while mixing evenly; at the same time, the centrifugal equipment rotates at high speed when centrifuging the material, and rotates at low speed at the end of separation, so as to separate all the materials.

[0083] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0084] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing pure alumina porous ceramics, characterized in that: The preparation method comprises: S1. Take the raw materials according to the mass ratio: high-purity low-sodium α-alumina, gelatinized starch, ammonium bicarbonate, phenolic resin, water and polyaluminium chloride sol for later use; S2, putting each raw material into a ball mill for grinding and mixing to obtain a liquid slurry; S3, putting the liquid slurry into a centrifugal device, and drying, crushing and screening the liquid slurry through the centrifugal components in the centrifugal device to obtain fluffy spherical pellets; S4, adding the fluffy spherical pellets into a calcining furnace, heating and calcining in the calcining furnace to obtain a fluffy spherical powder; S5, adding the fluffy spherical powder, high-purity alumina chopped fibers and high-purity low-sodium α-alumina powder into a stirring device according to a mass ratio to obtain a mixture, adding a polyvinyl alcohol aqueous solution into the mixture to obtain a molding solid, and then adding the molding solid into a metal mold to press to obtain a porous ceramic embryo; S6, adding the porous ceramic embryo into a calcining furnace, and obtaining pure alumina porous ceramics by calcining; Wherein, the centrifugal device comprises: The centrifugal device body comprises an outer shell, and a partition plate is fixedly connected to the inner side wall of the outer shell; A centrifugal assembly, comprising a first centrifugal cylinder and a second centrifugal cylinder, wherein the first centrifugal cylinder and the second centrifugal cylinder are rotatably mounted in an outer shell, the second centrifugal cylinder is arranged outside the first centrifugal cylinder, a plurality of first sieve holes are arranged in an annular manner from top to bottom on the side wall of the first centrifugal cylinder, and a plurality of second sieve holes are arranged in an annular manner from top to bottom on the second centrifugal cylinder; An accessory assembly includes a mounting shell, wherein the mounting shell is rotatably mounted on the second centrifugal cylinder; A motor is installed on the bottom wall plate of the outer shell, a driving shaft is installed on the output end of the motor, a first bearing is installed on the partition plate, the driving shaft is sleeved in the first bearing, the upper end of the first bearing is fixedly connected to the bottom of the first centrifugal cylinder, a return port is provided on the bottom wall plate of the first centrifugal cylinder, the apertures of the first sieve holes on the same ring are the same, and the apertures of the first sieve holes on different rings are arranged in a manner of gradually decreasing from top to bottom; The second centrifugal cylinder is provided with a plurality of hot air conveying grooves and a plurality of negative pressure grooves, and the plurality of hot air conveying grooves and the plurality of negative pressure grooves are respectively arranged above the second sieve hole on the same ring; a pair of hot air nozzles are arranged on the inner side wall of the second sieve hole in an up-and-down staggered manner, and the pair of hot air nozzles are respectively connected with the hot air conveying grooves above and below the corresponding second sieve hole; a pair of suction nozzles are arranged on the inner side wall of the second sieve hole in an up-and-down staggered manner, and the pair of suction nozzles are respectively connected with the negative pressure grooves above and below the corresponding second sieve hole, and the pair of hot air nozzles and the pair of suction nozzles are staggered with each other; baffle plates are fixedly connected on the upper and lower sides of the inner side wall of the second sieve hole, and the suction nozzles are inclined in a direction away from the hot air nozzles on the same side; a plurality of hot air conveying grooves are arranged between the plurality of hot air inlet grooves, and the plurality of negative A plurality of vacuum connecting grooves are arranged between the pressure grooves, a second bearing is installed on the outer wall of the upper end of the second centrifugal cylinder, the inner side of one side wall plate of the mounting shell is installed on the outer wall of the second bearing, the other side wall plate of the mounting shell is installed on the inner wall of the second centrifugal cylinder, a polishing plate is arranged on the inner side of the wall plate of the mounting shell mounted on the inner wall of the second centrifugal cylinder, a chamber is formed between the upper end wall plate of the mounting shell and the upper side wall of the second centrifugal cylinder, a blocking plate is fixedly connected in the chamber, the blocking plate divides the chamber into a hot air chamber and a vacuum chamber, a plurality of hot air delivery pipes are installed on the upper end of the hot air chamber, a hot air blower is installed at the air inlet of the plurality of hot air delivery pipes, a plurality of negative pressure pipes are installed on the upper end of the vacuum chamber, a vacuum device is installed at the inlet of the plurality of negative pressure pipes, the plurality of hot air inlet grooves are connected to the hot air chamber, and the plurality of vacuum connecting grooves are connected to the vacuum chamber.

2. The method for preparing pure alumina porous ceramics according to claim 1, characterized in that: The mass ratio of the raw materials in S1 is 100:5-10:2-5:3-6:30-50:5-10, and the Al2O3 content of the high-purity low-sodium α-alumina micropowder is ≥99.7%, the Na2O content is ≤0.08%, and the D50 is 1-5 microns.

3. The method for preparing pure alumina porous ceramics according to claim 1, characterized in that: When the centrifugal assembly dries the liquid slurry, the temperature of the hot air used is controlled at 60-80°C.

4. The method for preparing pure alumina porous ceramics according to claim 1, characterized in that: The temperature of the calcining furnace in S4 is controlled at 600-800°C, and the temperature of the calcining furnace in S6 is controlled at 1700-1800°C.

5. The method for preparing pure alumina porous ceramics according to claim 1, characterized in that: The mass ratio of the fluffy spherical powder, high-purity alumina chopped fibers and high-purity low-sodium α-alumina micropowder in S5 is 100:10~30:10~30.

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