Preparation method of alumina fiber with high alumina content

Abstract

The invention discloses a preparation method of alumina fiber with high alumina content, and relates to the field of refractory fiber materials. The invention relates to a preparation method of alumina fiber with high alumina content, which mainly comprises the following steps of: 1, dissolving inorganic aluminum salt, aluminum isopropoxide and aluminum powder in water, and heating and refluxing by taking water as a medium to obtain transparent precursor sol A; 2, dissolving quantitative boehmite in water, then adding dilute acid to adjust the pH value of the solution, and heating and refluxing to obtain sol B; according to the preparation method, alpha-Fe2O3 existing in a ferric nitrate form is introduced into a precursor sol system as a seed crystal, on one hand, nucleation potential energy and activation energy of alpha-Al2O3 phase change are reduced, so that the phase change temperature is reduced, and energy consumption in the production process is reduced; and on the other hand, the nucleation density is improved, the diffusion distance is shortened, the occurrence of a dendritic porous structure is effectively inhibited, and the wormlike morphology after phase change of alpha-Fe2O3 is weakened, so that the fiber can obtain a more uniform and compact tissue structure during later high-temperature sintering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refractory fiber materials, in particular to a preparation method of alumina fiber with high alumina content. BACKGROUND

[0002] Alumina fiber, also known as polycrystalline alumina fiber, is one of the latest ultra-lightweight high-temperature insulation materials at home and abroad, and 95% alumina fiber is one of the important categories.

[0003] 95% alumina fiber is mainly composed of Al2O3, and usually contains about 5% of SiO2, ZrO2 and MgO to stabilize the crystal phase and inhibit the growth of crystal grains at high temperature. The main crystal phase is corundum phase, and the general appearance is white, smooth, soft and elastic, integrating the characteristics of crystal materials and fiber materials. Due to the high alumina content and low impurity content of 95% alumina fiber, it has the characteristics of good heat resistance, low thermal conductivity, low thermal expansion coefficient and excellent high-temperature oxidation resistance, and the use temperature can reach 1400-1600℃.

[0004] As an important variety of polycrystalline refractory fiber, compared with carbon fiber and other non-oxide fibers, alumina fiber has good corrosion resistance and high-temperature oxidation resistance, and does not need to be coated with an anti-oxidation coating for use at high temperatures. It can be used as a high-temperature structural material and a catalyst carrier for chemical reactions, and has good electrical insulation and good heat stability. Compared with metal fibers, alumina fiber has low thermal conductivity and thermal expansion coefficient, and good thermal shock stability, and can be used as a reinforcing body for metal and ceramic matrix composites. In addition, compared with other inorganic fibers with good performance, alumina fiber has a simple preparation process, low cost and high commercial value.

[0005] However, due to the high alumina content and low SiO2 content for stabilizing the crystal phase and inhibiting the growth of crystal grains at high temperature, 95% alumina fiber has the disadvantages of low strength after high-temperature sintering, easy breakage and easy pulverization, which affects its performance and service life in practical applications. Therefore, the present application is proposed. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a preparation method of alumina fiber with high alumina content, which can overcome the above problems or at least partially solve the above problems.

[0007] To solve the above technical problems, the basic idea of the technical solution of the present application is as follows: a preparation method of alumina fiber with high alumina content, mainly comprising the following steps: Step 1: Dissolve inorganic aluminum salt, aluminum isopropoxide and aluminum powder in water as a medium, and reflux at elevated temperature to obtain a transparent precursor sol A; Step two: dissolve a certain amount of boehmite in water, then add dilute acid to adjust the pH value of the solution, and heat to reflux to obtain sol B; Step three: dissolve a certain amount of ferric nitrate in water, add ammonium nitrate to inhibit hydrolysis, and obtain sol C; Step four: add precursor sol A to a heated concentration tank, then sequentially add sol B, sol C and silicon sol as a silicon source to the heated concentration tank, mix with precursor sol A to form a sol mixture, then start the heated concentration tank to heat the sol mixture, after concentration, add a spinning aid to continue heating and concentrating, and 95% alumina gel is obtained; Step five: after a series of processes such as spinning and high temperature sintering, 95% alumina fiber is obtained.

[0008] Further, in step one, the temperature is 90-120℃.

[0009] Further, in step two, the pH value of the solution is adjusted to 3.0-5.0, and the heating temperature is 100-120℃.

[0010] Further, the water used in steps one, two and three is three times distilled water.

[0011] Further, the heated concentration tank in step four includes a support, a tank body, a drive motor, a drive shaft and a stirring rod, the tank body is installed on the support, the drive motor is fixedly connected to the upper end of the tank body through a support plate, the upper end of the drive shaft is fixedly connected to the output end of the drive motor, the lower end of the drive shaft extends downward into the tank body, the stirring rod is fixedly connected to the drive shaft at a circumferentially equidistant position inside the tank body, a feed valve pipe is fixedly connected to the upper end of one side of the tank body, a discharge valve pipe is fixedly connected to the bottom of the tank body, and an exhaust pipe is fixedly connected to the upper end of one side of the tank body.

[0012] In order to facilitate the upward transport of the sol mixture at the bottom of the tank body to the feed cylinder, and then re-feed back to the upper part of the tank body through multiple discharge pipes distributed at a circumferentially equidistant position, forming an upward and downward circulating material flow, further, a feed cylinder is fixedly connected to the central axis at the lower side of the inside of the tank body through a support rod, the drive shaft vertically penetrates the feed cylinder, and the drive shaft is fixedly connected to a spiral propeller at a position inside the feed cylinder, and multiple discharge pipes are fixedly connected to the upper side of the feed cylinder at a circumferentially equidistant position.

[0013] In order to facilitate the scraping of the sol mixture attached to the inner wall of the tank, avoid the local overheating, dry knot and even the phenomenon of paste bottom of the attached mixture during the heating process, ensure that all the sol mixture in the tank can be uniformly heated, maintain the stable heating concentration state, further, by fixing the scraper at the end of the stirring rod away from the driving shaft rod, and making the scraper slide and attach to the inner wall of the tank, the sol mixture attached to the inner wall of the tank can be scraped.

[0014] In order to facilitate the adsorption of the steam generated during the heating process, avoid the condensation of the steam into water droplets on the top of the tank, and then drop back into the sol mixture, thereby reducing the unnecessary water supplement in the mixture, further, by setting the high-temperature resistant water absorption sponge in the tank, and setting the high-temperature resistant water absorption sponge between the feed valve pipe and the exhaust pipe, the steam generated during heating can be adsorbed.

[0015] In order to facilitate the heating and evaporation of the water adsorbed by the sponge, convert the water into steam and discharge it through the exhaust pipe, remove the water adsorbed by the sponge in time, avoid its loss of the ability to continue to adsorb steam due to adsorption saturation, further, by setting the electric heating ring inside the high-temperature resistant water absorption sponge, the water adsorbed by the high-temperature resistant water absorption sponge can be heated and evaporated.

[0016] In order to facilitate the increase of the flow range and disturbance degree of the sol mixture in the tank, make the components contact more fully, further improve the mixing uniformity, further, by symmetrically fixing the bearing column on the upper end of the two sides of the tank, and making the bearing column rotate and connect on the support, the tank can rotate on the support, one side of the upper end of the tank is fixedly connected with an arc-shaped plate, one side of the arc-shaped plate close to the driving shaft rod is fixedly connected with an air bag, the driving shaft rod is fixedly connected with a mounting seat, the mounting seat is rotatably connected with a roller for extruding the air bag, one side of the support is fixedly connected with a mounting plate, one side of the mounting plate close to the tank is fixedly connected with an air cylinder, a piston rod with a piston is slidably connected in the air cylinder, one end of the piston rod extending out of the air cylinder abuts against the outer wall of the tank, the air bag and the air cylinder are communicated through a connecting air pipe.

[0017] After the above technical scheme is adopted, the present application has the following beneficial effects compared with the prior art: the present application introduces α-Fe2O3 in the form of ferric nitrate as a seed crystal in the precursor sol system, which plays an important role. On the one hand, it reduces the nucleation potential and activation energy of α-Al2O3 phase change, thereby reducing the phase change temperature and reducing the energy consumption in the production process. On the other hand, it improves the nucleation density, shortens the diffusion distance, effectively inhibits the appearance of dendritic porous structure, and weakens the worm-like morphology after α-Fe2O3 phase change, so that the fiber can obtain more uniform and dense microstructure during high-temperature sintering in the later stage.

[0018] The above-mentioned effects significantly improve the low strength and easy breakage and pulverization of the conventional 95% alumina fiber after high-temperature sintering due to the high alumina content and the few stable crystal phase components, so that the prepared 95% alumina fiber has more stable performance when used in a high-temperature environment.

[0019] The specific embodiments of the present application will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] In the drawings: Figure 1 The flow chart of the preparation method of the present application is shown in the figure. Figure 2 The structure of the heating and concentrating tank of the present application is shown in the figure. Figure 1 Figure 3 The structure of the heating and concentrating tank of the present application is shown in the figure. Figure 2 Figure 4 The partial cross-sectional structure of the heating and concentrating tank of the present application is shown in the figure. Figure 1 Figure 5 The partial cross-sectional structure of the heating and concentrating tank of the present application is shown in the figure. Figure 2

[0021] In the figure: 1, heating and concentrating tank; 101, bracket; 102, mounting plate; 103, air cylinder; 104, piston top rod; 105, tank body; 106, bearing column; 107, feeding valve pipe; 108, discharging valve pipe; 109, exhaust pipe; 2, high-temperature-resistant water-absorbing sponge; 201, electric heating ring; 3, support plate; 301, driving motor; 302, driving shaft; 303, stirring rod; 304, feeding cylinder; 305, spiral propeller blade; 306, scraper; 307, mounting seat; 308, roller; 4, arc-shaped plate; 401, air bag; 402, connecting air pipe. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments will be described clearly and completely below with reference to the drawings of the embodiments of the present application. The following embodiments are used to illustrate the present application, but not to limit the scope of the present application.

[0023] Embodiment: Referring to Figures 1-5 A preparation method of an alumina fiber with high alumina content, comprising the following steps: Step one, preparation of precursor sol A ​​​​The raw materials used are: inorganic aluminum salt, aluminum isopropyl alcohol, aluminum powder, three times water (high purity after three distillation treatment, which can reduce the interference of impurities on the sol system).

[0024] The specific operation is: the inorganic aluminum salt, aluminum isopropyl alcohol, aluminum powder is dissolved in three times water according to a certain proportion, taking water as the medium, the mixed solution is heated to 90-120℃, and kept in reflux state, under this temperature condition, the raw materials are fully dissolved and reacted, after a period of time, the transparent precursor sol A is obtained.

[0025] Step two, preparation of sol B The raw materials used are: quantitative boehmite, three times water, dilute acid.

[0026] The specific operation is: the quantitative boehmite is dissolved in three times water, then dilute acid is added to the solution, the pH value of the solution is adjusted to 3.0-5.0, then the solution is heated to 100-120℃, and reflux operation is carried out, in this process, the boehmite is fully dispersed and reacts with other substances, finally the sol B is obtained.

[0027] Step three, preparation of sol C The raw materials used are: quantitative iron nitrate, three times water, ammonium nitrate.

[0028] The specific operation is: the quantitative iron nitrate is dissolved in three times water, since the iron nitrate is prone to hydrolysis, in order to inhibit the hydrolysis, appropriate amount of ammonium nitrate is added to the solution, after stirring uniformly, the sol C is obtained.

[0029] Step four, preparation of 95% alumina gel Equipment used: this step is carried out in a heating concentration tank 1, which includes a support 101, a tank body 105, a driving motor 301, a driving shaft 302 and a stirring rod 303, the tank body 105 is installed on the support 101, the driving motor 301 is fixedly connected to the upper end of the tank body 105 through a support plate 3, the upper end of the driving shaft 302 is fixedly connected with the output end of the driving motor 301, the lower end extends into the tank body 105, the stirring rod 303 is fixedly connected on the driving shaft 302 at the position inside the tank body 105, the tank body 105 has a feeding valve pipe 107 on one side of the upper end, a discharging valve pipe 108 at the bottom, and an exhaust pipe 109 on one side of the upper end.

[0030] Specific operation is: first, through the feed valve pipe 107 precursor sol A is added to the tank body 105 of heating concentration tank 1, then in turn through the feed valve pipe 107 to the tank body 105 is added sol B, sol C and silicon sol as silicon source, start drive motor 301, drive motor 301 drive shaft rod 302 rotation, in turn make stirring rod 303 rotation, the mixed liquor of precursor sol A and the mixed liquor of precursor sol A is formed, after mixing uniformly, start heating concentration tank 1 to the mixed liquor of sol, in the process of heating, moisture in solution is discharged through exhaust pipe 109, after heating concentration for a period of time, add spinning aid, continue to heat and concentrate, make the mixed liquor of sol reach appropriate concentration and viscosity, finally get 95% alumina gel, then it can be discharged through the discharge valve pipe 108.

[0031] Step five, preparation of 95% alumina fiber The obtained 95% alumina gel is subjected to spinning operation to form fiber embryo, and then the fiber embryo is subjected to high temperature sintering and a series of processes, and finally 95% alumina fiber is obtained.

[0032] The preparation method introduces α-Fe2O3 in the form of iron nitrate as seed crystal in the precursor sol system, which plays an important role. On the one hand, it reduces the nucleation potential and activation energy of α-Al2O3 phase transition, thereby reducing the phase transition temperature and reducing the energy consumption in the production process. On the other hand, it increases the nucleation density and shortens the diffusion distance, effectively inhibits the appearance of dendritic porous structure, and weakens the worm-like morphology after α-Fe2O3 phase transition, so that the fiber can obtain more uniform and dense microstructure during high temperature sintering in the later stage.

[0033] The above-mentioned effect significantly improves the shortcomings of traditional 95% alumina fiber, such as low strength after high temperature sintering, easy to break and easy to pulverize, caused by too high alumina content and few stable crystal phase components, so that the prepared 95% alumina fiber has more stable performance when used in high temperature environment.

[0034] The 95% alumina fiber contains about 5% SiO2 and other components to stabilize the crystal phase and inhibit grain growth at high temperature, and the main crystal phase is corundum phase, which is white in appearance, smooth, soft and elastic, and integrates the characteristics of crystal materials and fiber materials.

[0035] Due to its high alumina content, low impurity content, good heat resistance, low thermal conductivity, low thermal expansion coefficient and excellent high temperature oxidation resistance, the use temperature can reach 1400-1600℃, and it can be widely used as heat insulation material in high temperature industrial kiln of metallurgy, machinery, chemical industry and other departments.

[0036] Meanwhile, due to the unique gamma-Al2O3 crystal phase, high specific surface area and porosity, the product can be used as catalyst carrier and filter material, etc., and has high commercial value and wide application prospect.

[0037] The raw materials used in the preparation process are easy to obtain, and the preparation process is relatively simple, facilitating large-scale production.

[0038] The use of the heating and concentrating tank 1 can make the heating and concentrating process of the sol mixture more efficient and uniform, ensuring the quality stability of the 95% alumina gel and providing a good foundation for the subsequent preparation of fibers.

[0039] The process parameters of each step in the entire preparation process are reasonably controlled, such as temperature and pH value, ensuring the smooth progress of the preparation process and the reliability of the product quality.

[0040] Referring to Figures 4-5 As shown in the figure: the inside lower center axis of the tank body 105 is fixedly connected with a feeding cylinder 304 through a support rod, the driving shaft rod 302 vertically penetrates in the feeding cylinder 304, the driving shaft rod 302 is fixedly connected with a spiral propelling blade 305 at the part inside the feeding cylinder 304, and the upper side of the feeding cylinder 304 is fixedly connected with multiple discharge pipes at equal intervals in circumference.

[0041] The feeding cylinder 304 is arranged at the inside lower side of the heating and concentrating tank 1, the spiral propelling blade 305 is fixed at the part of the driving shaft rod 302 inside the feeding cylinder 304, and multiple discharge pipes are connected to the upper side of the feeding cylinder 304, which significantly improves the mixing uniformity. When the driving shaft rod 302 drives the spiral propelling blade 305 to rotate, the sol mixture at the bottom of the tank body 105 can be transported upward into the feeding cylinder 304, and then sent back to the upper part of the tank body 105 through multiple discharge pipes distributed at equal intervals in circumference, forming an upward and downward circulating material flow. This circulation cooperates with the radial stirring of the stirring rod 303, so that the sol A, sol B, sol C and silicon sol and other components can fully contact and mix in a wider range, avoiding the problem of uneven local components, ensuring more uniform reaction of each component in the subsequent heating and concentrating process, and providing a strong guarantee for the performance stability of the final 95% alumina gel and fibers.

[0042] Referring to Figures 4-5 As shown in the figure: the stirring rod 303 is fixedly connected with a scraper 306 at the end away from the driving shaft rod 302, and the scraper 306 is in sliding contact with the inner wall of the tank body 105, which can be used to scrape the sol mixture attached to the inner wall of the tank body 105.

[0043] The scraping plate 306 is fixedly connected to the stirring rod 303 at the end far away from the driving shaft rod 302 and is in sliding contact with the inner wall of the tank body 105, which can effectively scrape the sol mixture attached to the inner wall of the tank body 105, avoid the local retention, dryness or component separation of the sol mixture due to long-time attachment to the tank wall, ensure that all materials in the tank can participate in the stirring and mixing process, further improve the uniformity of the mixed components, guarantee the consistency of the overall components of the sol mixture, and reduce the waste of raw materials and improve the utilization rate of raw materials.

[0044] Meanwhile, in the process of heating and concentrating, the sol mixture attached to the inner wall of the tank body 105 can be scraped in time to avoid local overheating, dryness or even paste bottom phenomenon of the attached mixture due to long-time heating in the heating process, ensure that all sol mixtures in the tank can be uniformly heated, maintain a stable heating and concentrating state, reduce the component change or impurity generation caused by local paste bottom, thereby guaranteeing the preparation quality of 95% alumina gel and providing a stable raw material basis for the subsequent wire making and high-temperature sintering processes.

[0045] Referring to Figures 4-5 As shown in the figure, by setting the high-temperature-resistant water-absorbing sponge 2 in the tank body 105 and arranging the high-temperature-resistant water-absorbing sponge 2 between the feed valve pipe 107 and the exhaust pipe 109, the generated steam can be absorbed. The high-temperature-resistant water-absorbing sponge 2 arranged between the feed valve pipe 107 and the exhaust pipe 109 in the tank body 105 can effectively absorb the steam generated in the heating process, avoid the water droplets formed by the condensation of steam at the top of the tank body 105 from falling back into the sol mixture, thereby reducing the unnecessary water supplement in the mixture, ensuring that the heating and concentrating process can continuously and efficiently remove the solvent in the system, speeding up the process of reaching the target concentration, guaranteeing the stability of the concentration efficiency in the preparation process of 95% alumina gel, and laying a foundation for the smooth progress of the subsequent processes.

[0046] By arranging the electric heating ring 201 inside the high-temperature-resistant water-absorbing sponge 2, the water absorbed by the high-temperature-resistant water-absorbing sponge 2 can be heated and evaporated. The arrangement of the electric heating ring 201 inside the high-temperature-resistant water-absorbing sponge 2 can heat and evaporate the water absorbed by the sponge, convert the water into steam and discharge it through the exhaust pipe 109, timely remove the water absorbed by the sponge, avoid the loss of the ability to continue absorbing steam due to saturation, thereby ensuring the continuous and efficient performance of the high-temperature-resistant water-absorbing sponge 2, stabilizing the steam generated in the absorption and heating process, and maintaining the efficiency and effect of heating and concentrating.

[0047] Referring to Figure 2 , Figure 3 , Figure 5As shown: by the two sides of the tank body 105 upper end symmetrical fixed bearing column 106, and make bearing column 106 rotating connection in support 101, can make tank body 105 rotating in support 101, tank body 105 upper end one side fixed connection has arc plate 4, arc plate 4 close to the side of the drive shaft rod 302 fixed connection has air bag 401, drive shaft rod 302 fixed connection has mounting seat 307, mounting seat 307 rotating connection has for air bag 401 extrusion roller 308, support 101 one side fixed connection has mounting plate 102, mounting plate 102 close to the side of the tank body 105 fixed connection has air cylinder 103, air cylinder 103 sliding connection has piston piston rod 104, piston rod 104 extends out of air cylinder 103 one end and tank body 105 outer wall, air bag 401 and air cylinder 103 between through the connecting pipe 402 intercommunication.

[0048] In tank body 105 both sides upper end through bearing column 106 and support 101 rotating connection, cooperate arc plate 4 on air bag 401, drive shaft rod 302 on roller 308 and air cylinder 103 and piston rod 104 etc. Structure, can drive motor 301 drive shaft rod 302 rotating when, let roller 308 intermittent extrusion air bag 401, air bag 401 in the gas into air cylinder 103, make piston rod 104 jolt tank body 105 produce turn, and when roller 308 and air bag 401 separate, air cylinder 103 in part gas backflow to air bag 401, tank body 105 reverse rotation, form continuous shaking, this tank body 105 reciprocating shaking and stirring bar 303 of the combination of stirring, can greatly increase the sol in the tank flow range and disturbance degree, let each component contact more fully, further improve the mixing uniformity, is beneficial to subsequent preparation of quality more stable 95% alumina gel.

[0049] The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

[0050] The above only describes the preferred embodiments of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above, it is not intended to limit the present application.

Claims

1. A method for preparing alumina fibers with high alumina content, characterized in that, The main steps include: Step 1: Dissolve inorganic aluminum salt, aluminum isopropoxide, and aluminum powder in water, and use water as a medium to heat and reflux to obtain a transparent precursor sol A; Step 2: Dissolve a measured amount of boehmite in water, then add dilute acid to adjust the pH of the solution, heat and reflux to obtain sol B; Step 3: Dissolve a measured amount of ferric nitrate in water, add ammonium nitrate to inhibit hydrolysis, and obtain sol C; Step 4: Add precursor sol A to the heating concentration tank (1), then add sol B, sol C and silica sol as silicon source to the heating concentration tank (1) in sequence, mix with precursor sol A to form sol mixture, then start the heating concentration tank (1) to heat the sol mixture, after heating and concentration, add spinning aid and continue heating and concentration to obtain 95% alumina gel; Step 5: After a series of processes such as fiber making and high-temperature sintering, 95% alumina fiber can be obtained.

2. The method for preparing alumina fibers with high alumina content according to claim 1, characterized in that, In step one, the heating temperature is 90-120℃.

3. The method for preparing alumina fibers with high alumina content according to claim 2, characterized in that, In step two, the pH value of the solution is adjusted to 3.0-5.0, and the heating temperature is 100-120℃.

4. The method for preparing alumina fibers with high alumina content according to claim 3, characterized in that, The water used in steps one, two, and three is triple-distilled water.

5. The method for preparing alumina fibers with high alumina content according to claim 1, characterized in that, The heating and concentrating tank (1) in step four includes a support (101), a tank body (105), a drive motor (301), a drive shaft (302), and a stirring rod (303). The tank body (105) is mounted on the support (101). The drive motor (301) is fixedly connected to the upper end of the tank body (105) via a support plate (3). The upper end of the drive shaft (302) is fixedly connected to the output end of the drive motor (301). The lower end of the drive shaft (302) extends downward into the tank (105). The stirring rod (303) is fixedly connected to the drive shaft (302) at a circumferential distance in the part located inside the tank (105). A feed valve pipe (107) is fixedly connected to the upper end of one side of the tank (105). A discharge valve pipe (108) is fixedly connected to the bottom of the tank (105). An exhaust pipe (109) is fixedly connected to one side of the upper end of the tank (105).

6. The method for preparing alumina fibers with high alumina content according to claim 5, characterized in that, A feed cylinder (304) is fixedly connected to the central axis of the lower side of the tank (105) by a support rod. The drive shaft (302) is vertically inserted into the feed cylinder (304). A spiral propulsion blade (305) is fixedly connected to the part of the drive shaft (302) located inside the feed cylinder (304). Multiple discharge pipes are fixedly connected to the upper side of the feed cylinder (304) in a circumferentially equidistant manner.

7. The method for preparing alumina fibers with high alumina content according to claim 5, characterized in that, By fixing a scraper (306) to one end of the stirring rod (303) away from the drive shaft (302) and making the scraper (306) slide against the inner wall of the tank (105), it can be used to scrape the sol mixture adhering to the inner wall of the tank (105).

8. The method for preparing alumina fibers with high alumina content according to claim 5, characterized in that, By setting a high-temperature resistant water-absorbing sponge (2) inside the tank (105) and placing the high-temperature resistant water-absorbing sponge (2) between the feed valve pipe (107) and the exhaust pipe (109), it can be used to absorb the steam generated by heating.

9. The method for preparing alumina fibers with high alumina content according to claim 8, characterized in that, By setting an electric heating ring (201) inside the high-temperature resistant absorbent sponge (2), the water absorbed by the high-temperature resistant absorbent sponge (2) can be heated and evaporated.

10. The method for preparing alumina fibers with high alumina content according to claim 5, characterized in that, By symmetrically fixing bearing columns (106) to the upper ends of both sides of the tank body (105) and rotatably connecting the bearing columns (106) to the bracket (101), the tank body (105) can rotate on the bracket (101). An arc-shaped plate (4) is fixedly connected to one side of the upper end of the tank body (105). An airbag (401) is fixedly connected to the side of the arc-shaped plate (4) near the drive shaft (302). A mounting base (307) is fixedly connected to the drive shaft (302). A device for rotating the mounting base (307) is rotatably connected to the mounting base (307). A roller (308) that squeezes the airbag (401) is fixedly connected to one side of the bracket (101), and an air cylinder (103) is fixedly connected to the side of the mounting plate (102) near the tank (105). A piston rod (104) with a piston is slidably connected inside the air cylinder (103). One end of the piston rod (104) extends out of the air cylinder (103) and abuts against the outer wall of the tank (105). The airbag (401) and the air cylinder (103) are connected to each other through a connecting air pipe (402).

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