A hydrothermal reaction method for preparing high-purity aluminum oxide

Abstract

A hydrothermal reaction method for preparing high-purity aluminum oxide specifically comprises the following steps: (1) assembling a hydrothermal reaction device for preparing high-purity aluminum oxide, which comprises a fluidized bed, a water vapor generator, a pressure fan, a quantitative feeder, a heat exchanger and a high-pressure hydrogen storage tank; (2) starting the water vapor generator and the pressure fan, filling the fluidized bed with water vapor, and then adding high-purity aluminum powder into the fluidized bed through the quantitative feeder; (3) setting the reaction temperature and reaction time in the fluidized bed so that the high-purity aluminum powder reacts with the water vapor to obtain aluminum hydroxide, collecting hydrogen into a high-pressure gas storage tank, and the water vapor is condensed by the heat exchanger and then refluxed into the water vapor generator; (4) drying and calcining the aluminum hydroxide prepared in step (3) to obtain high-purity aluminum oxide. The present invention has simple process, convenient operation, high efficiency, high safety performance, and can also prepare byproduct hydrogen, low cost, green and pollution-free, energy-saving and consumption-reducing, and good economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of high-purity aluminum oxide preparation, and in particular to a hydrothermal reaction method for preparing high-purity aluminum oxide. Background Art

[0002] High-purity alumina is a powder material with a purity of ≥99.99%. It has the advantages of high purity, small particle size, narrow particle size distribution range and good sintering activity. It is widely used in many fields such as optics, chemical industry and special ceramics. At present, the methods for preparing high-purity alumina mainly include: ammonium aluminum sulfate pyrolysis preparation method, ammonium aluminum carbonate pyrolysis preparation method, alcohol aluminum hydrolysis preparation method, sol-gel method, high-purity alumina modified Bayer preparation method, plasma method, high-purity aluminum hydrolysis method, etc. Among them, the ammonium aluminum sulfate pyrolysis preparation method, ammonium aluminum carbonate pyrolysis preparation method and alcohol aluminum hydrolysis preparation method have achieved industrial production, but the above methods still have problems such as complex process, high cost, low output, high pollution and high energy consumption.

[0003] The patent (CN204588720U) discloses a method for preparing high-purity alumina by self-absorption hydrolysis. The method uses the negative pressure generated by the rotation of the stirring rod to allow air to enter the liquid through the ventilation pipe, increase the oxygen content of the system, reduce the agglomeration of aluminum powder, promote the reaction of 2H2O+O2→4OH-, increase the pH value of the system, destroy the oxide layer on the metal surface, and then promote the hydrolysis reaction of aluminum. The process of this method is simple, but a large amount of oxygen is introduced into the reaction system, which is prone to explosion when mixed with hydrogen, posing a great safety hazard. The domestic patent (CN103803619A) discloses a method for preparing high-purity alumina powder from fine metal aluminum powder. The method mixes aluminum powder with an aluminum content of more than 99.99% and oxygen with a purity of more than 99.999% and heats it to more than 600°C. The aluminum powder reacts with oxygen to produce high-purity alumina with a purity of more than 99.999%. However, this method is costly, and the reaction is too intense, posing a safety hazard of explosion. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a hydrothermal reaction method for preparing high-purity alumina. The present invention has simple process, convenient operation, high efficiency, high safety performance, can also prepare by-product hydrogen, has low cost, is green and pollution-free, saves energy and reduces consumption, and has good economic benefits.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A hydrothermal reaction method for preparing high-purity aluminum oxide specifically comprises the following steps:

[0007] (1) Assembling a hydrothermal reaction device for preparing high-purity alumina, the hydrothermal reaction device for preparing high-purity alumina comprising a fluidized bed, a steam generator, a pressurized blower, a quantitative feeder, a heat exchanger and a high-pressure hydrogen storage tank;

[0008] (2) Start the steam generator and the pressure fan to fill the fluidized bed with steam, and then add high-purity aluminum powder into the fluidized bed through a quantitative feeder;

[0009] (3) Setting the reaction temperature and reaction time in the fluidized bed to react the high-purity aluminum powder with water vapor to obtain aluminum hydroxide as a reaction product, and collecting the by-reaction product hydrogen into a high-pressure gas storage tank. The water vapor is condensed by a heat exchanger and then refluxed into the water vapor generator;

[0010] (4) The aluminum hydroxide prepared in step (3) is dried and calcined to obtain high-purity aluminum oxide.

[0011] The hydrothermal reaction device for preparing high-purity alumina also includes a centrifugal fan. The fluidized bed is tilted so that it is higher on the left and lower on the right. A feed port is provided on the left side of the top of the fluidized bed. A breathable layer is provided on the inner bottom of the fluidized bed, which is located above the bottom plate of the fluidized bed and parallel to the bottom plate of the fluidized bed. A discharge port which is higher than the breathable layer and obliquely downward is provided on the lower right side of the fluidized bed. A hand valve is provided on the discharge port. The discharge end of the quantitative feeder is connected with the feed port. A steam inlet is provided on the bottom plate of the fluidized bed. A reaction gas outlet is provided on the top of the fluidized bed. The steam outlet of the water vapor generator is connected with the steam inlet through a steam pipe. A pressurized fan is provided on the steam pipe. The reaction gas outlet is connected with the bottom air inlet of the heat exchanger through an air outlet pipe. The top air outlet of the heat exchanger is connected with the air inlet of the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The centrifugal fan is provided on the hydrogen delivery pipe. The bottom condensate outlet of the heat exchanger is connected with the water inlet of the water vapor generator through a condensate reflux pipe. A check valve is provided on the condensate reflux pipe at the water inlet of the water vapor generator.

[0012] A safety valve, a pressure transmitter and a temperature transmitter are also provided on the top of the fluidized bed.

[0013] The inclination angle of the fluidized bed compared to the horizontal plane is 5-30°, and the inclination angle of the discharge port compared to the horizontal plane is 50-80°.

[0014] The breathable layer is made of heat-resistant stainless steel metal woven cloth.

[0015] Step (2) is specifically as follows: start the steam generator and the pressure fan, the pressure fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 100g / m 3The high-purity aluminum powder with a particle size of 10-50 μm and a purity of ≥99.99% is added to the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; step (3) is specifically: setting the reaction temperature in the fluidized bed to 110°C and the reaction time to 1 hour, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter, and the hydrogen The hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through the outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through the centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through the hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxes to the water vapor generator through the condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port;

[0016] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0017] Step (2) is specifically as follows: start the steam generator and the pressure fan, the pressure fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 100g / m 3 The high-purity aluminum powder with a particle size of 1000μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer;

[0018] Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 110°C and the reaction time to 2 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port;

[0019] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0020] Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 300g / m 3 The high-purity aluminum powder with a particle size of 10-100μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer;

[0021] Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 120°C and the reaction time to 2 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port.

[0022] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0023] Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 300g / m 3 The high-purity aluminum powder with a particle size of 1000μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer;

[0024] Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 120°C and the reaction time to 3 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port;

[0025] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0026] Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 600g / m 3 The high-purity aluminum powder with a particle size of 500μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer;

[0027] Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 130°C and the reaction time to 3 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port;

[0028] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0029] The present invention has outstanding substantive features and significant progress compared to the prior art. Specifically, the present invention has the following technical effects:

[0030] (1) The present invention adopts a hydrothermal reaction to prepare high-purity alumina. The hydrothermal reaction rate of high-purity aluminum powder is fast and the stability is high, which reduces the formation of an oxide layer on the surface of the aluminum powder and reduces the agglomeration of the high-purity aluminum powder, making the hydrothermal reaction more complete and preparing high-purity aluminum hydroxide. The aluminum hydroxide is then dried and calcined to prepare high-purity alumina.

[0031] (2) Before the hydrothermal reaction, the present invention first introduces water vapor into the fluidized bed and fills the fluidized bed, and then exhausts the air in the fluidized bed. During the reaction, a centrifugal fan is used to extract hydrogen and excess water vapor. No oxygen is present during the entire hydrothermal reaction process, thereby avoiding the potential safety hazard of explosion caused by the mixture of hydrogen and oxygen encountering an open flame, thereby greatly improving the safety of the hydrothermal reaction.

[0032] (3) The present invention prepares hydrogen as a byproduct while preparing high-purity alumina, and separates water vapor and hydrogen through a heat exchanger. Compared with conventional hydrogen production processes, the hydrothermal reaction for preparing hydrogen has significant advantages such as being simple and fast, low cost, green and pollution-free, and energy-saving and consumption-reducing.

[0033] The invention has the advantages of simple structure, convenient operation, high efficiency, energy saving and environmental protection, high safety performance, and can also prepare by-product hydrogen, thus having good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a hydrothermal reaction device for preparing high-purity alumina according to the present invention. DETAILED DESCRIPTION

[0035] The embodiments of the present invention are further described below with reference to the accompanying drawings. Embodiment 1

[0036] like Figure 1 As shown, a hydrothermal reaction method for preparing high-purity aluminum oxide specifically comprises the following steps:

[0037] (1) Assembling a hydrothermal reaction device for preparing high-purity alumina, the hydrothermal reaction device for preparing high-purity alumina comprising a fluidized bed 1, a steam generator 2, a pressurized fan 3, a quantitative feeder 4, a heat exchanger 5 and a high-pressure hydrogen storage tank 6;

[0038] (2) Start the steam generator 2 and the pressure fan 3, fill the fluidized bed 1 with steam, and then add high-purity aluminum powder into the fluidized bed 1 through the quantitative feeder 4;

[0039] (3) Setting the reaction temperature and reaction time in the fluidized bed 1 so that the high-purity aluminum powder reacts with the water vapor to obtain aluminum hydroxide as a reaction product, and collecting the by-reaction product hydrogen into a high-pressure gas storage tank. The water vapor is condensed by the heat exchanger 5 and then refluxed into the water vapor generator 2;

[0040] (4) The aluminum hydroxide prepared in step (3) is dried and calcined to obtain high-purity aluminum oxide.

[0041] The hydrothermal reaction device for preparing high-purity alumina also includes a centrifugal fan 7. The fluidized bed 1 is tilted so that it is higher on the left and lower on the right. A feed port 8 is provided on the left side of the top of the fluidized bed 1. A breathable layer 9 is provided on the inner bottom of the fluidized bed 1, which is located above the bottom plate of the fluidized bed 1 and parallel to the bottom plate of the fluidized bed 1. A discharge port 10 is provided on the lower right side of the fluidized bed 1, which is higher than the breathable layer 9 and obliquely downward. A hand valve 11 is provided on the discharge port 10. The discharge end of the quantitative feeder 4 is connected to the feed port 8. A steam inlet 12 is provided on the bottom plate of the fluidized bed 1. A reaction gas outlet 13 is provided on the top of the fluidized bed 1. The water vapor The steam outlet of the generator 2 is connected to the steam inlet 12 through a steam pipe 14, the booster fan 3 is arranged on the steam pipe 14, the reaction gas outlet 13 is connected to the bottom air inlet of the heat exchanger 5 through an outlet pipe 15, the top air outlet of the heat exchanger 5 is connected to the air inlet of the high-pressure hydrogen storage tank 6 through a hydrogen delivery pipe 16, the centrifugal fan 7 is arranged on the hydrogen delivery pipe 16, the bottom condensate outlet of the heat exchanger 5 is connected to the water inlet of the steam generator 2 through a condensate reflux pipe 17, and a check valve 18 is provided on the condensate reflux pipe 17 at the water inlet of the steam generator 2.

[0042] A safety valve 19, a pressure transmitter 20 and a temperature transmitter 21 are also provided on the top of the fluidized bed 1. The safety valve 19 prevents the pressure in the fluidized bed 1 from being too high and causing danger. When the reaction gas outlet 13 is blocked, the safety valve 19 opens after the pressure in the fluidized bed 1 reaches the limit, so that the fluidized bed 1 can be depressurized, thereby protecting the fluidized bed 1 and improving safety.

[0043] The inclination angle of the fluidized bed 1 compared to the horizontal plane is 5-30°, and the inclination angle of the discharge port 10 compared to the horizontal plane is 50-80°.

[0044] The air permeable layer 9 is made of heat-resistant stainless steel metal woven cloth.

[0045] Step (2) is specifically as follows: start the steam generator 2 and the pressure fan 3, the pressure fan 3 passes the steam generated by the steam generator 2 into the fluidized bed 1 through the steam pipe 14, and when the steam fills the fluidized bed 1 and there is no air in the fluidized bed 1, the content of aluminum powder in the steam is 100g / m 3 The ratio of high-purity aluminum powder with a particle size of 10-50 μm and a purity of ≥99.99% is added to the fluidized bed 1 through the quantitative feeder 4, and the high-purity aluminum powder falls on the air permeable layer 9; step (3) is specifically: the reaction temperature in the fluidized bed 1 is set to 110°C, the reaction time is 1 hour, and the centrifugal fan 7 is started at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed 1 are respectively monitored in real time by the pressure transmitter 20 and the temperature transmitter 21. Hydrogen and water vapor are generated from the reaction The gas flows out from the gas outlet 13 and enters the heat exchanger 5 through the gas outlet pipe 15. After the hydrogen and water vapor are cooled by the heat exchanger 5, the temperature of the hydrogen is reduced and is extracted from the top gas outlet of the heat exchanger 5 through the centrifugal fan 7. The hydrogen then enters the high-pressure hydrogen storage tank 6 through the hydrogen delivery pipe 16. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger 5 and refluxes to the water vapor generator 2 through the condensed water reflux pipe 17. After the reaction is completed, the water vapor generator 2, the pressure fan 3 and the centrifugal fan 7 are turned off, the hand valve 11 is loosened to open the discharge port 10, and the aluminum hydroxide is discharged from the discharge port 10;

[0046] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder. Embodiment 2

[0047] The difference from the first embodiment is that step (2) is specifically as follows: starting the water vapor generator 2 and the pressure fan 3, the pressure fan 3 passes the water vapor generated by the water vapor generator 2 into the fluidized bed 1 through the steam pipe 14, and after the water vapor fills the fluidized bed 1 and there is no air in the fluidized bed 1, the content of aluminum powder in the water vapor is 100g / m 3 The high-purity aluminum powder with a particle size of 1000 μm and a purity of ≥99.99% is added to the fluidized bed 1 through the quantitative feeder 4, and the high-purity aluminum powder falls on the air permeable layer 9;

[0048] Step (3) is specifically as follows: the reaction temperature in the fluidized bed 1 is set to 110°C, the reaction time is set to 2 hours, and the centrifugal fan 7 is started at the same time, so that the high-purity aluminum powder and the water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed 1 are respectively monitored in real time by the pressure transmitter 20 and the temperature transmitter 21. The hydrogen and water vapor flow out from the reaction gas outlet 13 and enter the heat exchanger 5 through the outlet pipe 15. The hydrogen and water vapor are After cooling through the heat exchanger 5, the temperature of the hydrogen is reduced and the hydrogen is extracted from the top outlet of the heat exchanger 5 through the centrifugal fan 7. The hydrogen then enters the high-pressure hydrogen storage tank 6 through the hydrogen delivery pipe 16. The water vapor is condensed into condensed water and discharged from the bottom condensed water outlet of the heat exchanger 5 and refluxed into the water vapor generator 2 through the condensed water reflux pipe 17. After the reaction is completed, the water vapor generator 2, the booster fan 3 and the centrifugal fan 7 are turned off, the hand valve 11 is loosened to open the discharge port 10, and the aluminum hydroxide is discharged from the discharge port 10;

[0049] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder. Embodiment 3

[0050] The difference from the first and second embodiments is that step (2) is specifically as follows: starting the water vapor generator 2 and the pressure fan 3, the pressure fan 3 passes the water vapor generated by the water vapor generator 2 into the fluidized bed 1 through the steam pipe 14, and after the water vapor fills the fluidized bed 1 and there is no air in the fluidized bed 1, the content of aluminum powder in the water vapor is 300g / m 3 The high-purity aluminum powder with a particle size of 10-100 μm and a purity of ≥99.99% is added to the fluidized bed 1 through the quantitative feeder 4, and the high-purity aluminum powder falls on the air permeable layer 9;

[0051] Step (3) is specifically as follows: the reaction temperature in the fluidized bed 1 is set to 120°C, the reaction time is set to 2 hours, and the centrifugal fan 7 is started at the same time, so that the high-purity aluminum powder and the water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed 1 are respectively monitored in real time by the pressure transmitter 20 and the temperature transmitter 21. The hydrogen and water vapor flow out from the reaction gas outlet 13 and enter the heat exchanger 5 through the outlet pipe 15. The hydrogen and water vapor are After cooling through the heat exchanger 5, the temperature of the hydrogen is reduced and the hydrogen is extracted from the top outlet of the heat exchanger 5 through the centrifugal fan 7. The hydrogen then enters the high-pressure hydrogen storage tank 6 through the hydrogen delivery pipe 16. The water vapor is condensed into condensed water and discharged from the bottom condensed water outlet of the heat exchanger 5 and refluxed into the water vapor generator 2 through the condensed water reflux pipe 17. After the reaction is completed, the water vapor generator 2, the booster fan 3 and the centrifugal fan 7 are turned off, the hand valve 11 is loosened to open the discharge port 10, and the aluminum hydroxide is discharged from the discharge port 10;

[0052] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder. Embodiment 4

[0053] The difference from the first, second and third embodiments is that step (2) is specifically as follows: starting the water vapor generator 2 and the pressure fan 3, the pressure fan 3 passes the water vapor generated by the water vapor generator 2 into the fluidized bed 1 through the steam pipe 14, and when the water vapor fills the fluidized bed 1 and there is no air in the fluidized bed 1, the content of aluminum powder in the water vapor is 300g / m 3 The high-purity aluminum powder with a particle size of 1000 μm and a purity of ≥99.99% is added to the fluidized bed 1 through the quantitative feeder 4, and the high-purity aluminum powder falls on the air permeable layer 9;

[0054] Step (3) is specifically as follows: the reaction temperature in the fluidized bed 1 is set to 120°C, the reaction time is 3 hours, and the centrifugal fan 7 is started at the same time, so that the high-purity aluminum powder and the water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed 1 are respectively monitored in real time by the pressure transmitter 20 and the temperature transmitter 21. Hydrogen and water vapor flow out from the reaction gas outlet 13 and enter the heat exchanger 5 through the outlet pipe 15. The hydrogen and water vapor are After cooling through the heat exchanger 5, the temperature of the hydrogen is reduced and the hydrogen is extracted from the top outlet of the heat exchanger 5 through the centrifugal fan 7. The hydrogen then enters the high-pressure hydrogen storage tank 6 through the hydrogen delivery pipe 16. The water vapor is condensed into condensed water and discharged from the bottom condensed water outlet of the heat exchanger 5 and refluxed into the water vapor generator 2 through the condensed water reflux pipe 17. After the reaction is completed, the water vapor generator 2, the booster fan 3 and the centrifugal fan 7 are turned off, the hand valve 11 is loosened to open the discharge port 10, and the aluminum hydroxide is discharged from the discharge port 10;

[0055] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder. Embodiment 5

[0056] The difference from the first, second, third and fourth embodiments is that step (2) specifically comprises: starting the water vapor generator 2 and the pressure fan 3, the pressure fan 3 passes the water vapor generated by the water vapor generator 2 into the fluidized bed 1 through the steam pipe 14, and when the water vapor fills the fluidized bed 1 and there is no air in the fluidized bed 1, the content of aluminum powder in the water vapor is 600g / m 3 The high-purity aluminum powder with a particle size of 500 μm and a purity of ≥99.99% is added to the fluidized bed 1 through the quantitative feeder 4, and the high-purity aluminum powder falls on the air permeable layer 9;

[0057] Step (3) is specifically as follows: the reaction temperature in the fluidized bed 1 is set to 130°C, the reaction time is set to 3 hours, and the centrifugal fan 7 is started at the same time, so that the high-purity aluminum powder and the water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed 1 are respectively monitored in real time by the pressure transmitter 20 and the temperature transmitter 21. The hydrogen and water vapor flow out from the reaction gas outlet 13 and enter the heat exchanger 5 through the outlet pipe 15. The hydrogen and water vapor are After cooling through the heat exchanger 5, the temperature of the hydrogen is reduced and the hydrogen is extracted from the top outlet of the heat exchanger 5 through the centrifugal fan 7. The hydrogen then enters the high-pressure hydrogen storage tank 6 through the hydrogen delivery pipe 16. The water vapor is condensed into condensed water and discharged from the bottom condensed water outlet of the heat exchanger 5 and refluxed into the water vapor generator 2 through the condensed water reflux pipe 17. After the reaction is completed, the water vapor generator 2, the booster fan 3 and the centrifugal fan 7 are turned off, the hand valve 11 is loosened to open the discharge port 10, and the aluminum hydroxide is discharged from the discharge port 10;

[0058] Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

[0059] The fluidized bed 1, the steam generator 2, the pressurized fan 3, the quantitative feeder 4, the heat exchanger 5, the high-pressure hydrogen storage tank 6, the centrifugal fan 7, the air permeable layer 9, the check valve 18, the safety valve 19, the pressure transmitter 20 and the temperature transmitter 21 are all conventional technologies, and the specific structure and working principle are not repeated here.

[0060] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A hydrothermal reaction method for preparing high-purity aluminum oxide, characterized in that: The specific steps include: (1) Assembling a hydrothermal reaction device for preparing high-purity alumina, the hydrothermal reaction device for preparing high-purity alumina comprising a fluidized bed, a steam generator, a pressurized blower, a quantitative feeder, a heat exchanger and a high-pressure hydrogen storage tank; (2) Start the steam generator and the pressure fan to fill the fluidized bed with steam, then add high-purity aluminum powder into the fluidized bed through a quantitative feeder. The purity of the high-purity aluminum powder is ≥99.99%; (3) Setting the reaction temperature and reaction time in the fluidized bed to react the high-purity aluminum powder with water vapor to obtain aluminum hydroxide as a reaction product, and collecting the by-reaction product hydrogen into a high-pressure gas storage tank. The water vapor is condensed by a heat exchanger and then refluxed into the water vapor generator; (4) The aluminum hydroxide prepared in step (3) is dried and calcined to obtain high-purity aluminum oxide.

2. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 1, characterized in that: The hydrothermal reaction device for preparing high-purity alumina also includes a centrifugal fan. The fluidized bed is tilted so that it is higher on the left and lower on the right. A feed port is provided on the left side of the top of the fluidized bed. A breathable layer is provided on the inner bottom of the fluidized bed, which is located above the bottom plate of the fluidized bed and parallel to the bottom plate of the fluidized bed. A discharge port which is higher than the breathable layer and obliquely downward is provided on the lower right side of the fluidized bed. A hand valve is provided on the discharge port. The discharge end of the quantitative feeder is connected with the feed port. A steam inlet is provided on the bottom plate of the fluidized bed. A reaction gas outlet is provided on the top of the fluidized bed. The steam outlet of the water vapor generator is connected with the steam inlet through a steam pipe. A pressurized fan is provided on the steam pipe. The reaction gas outlet is connected with the bottom air inlet of the heat exchanger through an air outlet pipe. The top air outlet of the heat exchanger is connected with the air inlet of the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The centrifugal fan is provided on the hydrogen delivery pipe. The bottom condensate outlet of the heat exchanger is connected with the water inlet of the water vapor generator through a condensate reflux pipe. A check valve is provided on the condensate reflux pipe at the water inlet of the water vapor generator.

3. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 2, characterized in that: A safety valve, a pressure transmitter and a temperature transmitter are also provided on the top of the fluidized bed.

4. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 3, characterized in that: The inclination angle of the fluidized bed compared to the horizontal plane is 5-30°, and the inclination angle of the discharge port compared to the horizontal plane is 50-80°.

5. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 4, characterized in that: The breathable layer is made of heat-resistant stainless steel metal woven cloth.

6. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 5, characterized in that: Step (2) is specifically as follows: start the steam generator and the pressure fan, the pressure fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 100g / m 3 The high-purity aluminum powder with a particle size of 10-50μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 110°C and the reaction time to 1 hour, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port; Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

7. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 5, characterized in that: Step (2) is specifically as follows: start the steam generator and the pressure fan, the pressure fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 100g / m 3 The high-purity aluminum powder with a particle size of 1000μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 110°C and the reaction time to 2 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port; Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

8. The hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 5, characterized in that: Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 300g / m 3 The high-purity aluminum powder with a particle size of 10-100μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 120°C and the reaction time to 2 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port. Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

9. The hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 5, characterized in that: Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 300g / m 3 The high-purity aluminum powder with a particle size of 1000μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 120°C and the reaction time to 3 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port; Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

10. A hydrothermal reaction method for preparing high-purity aluminum oxide according to claim 5, characterized in that: Step (2) is specifically as follows: start the steam generator and the booster fan, the booster fan passes the steam generated by the steam generator into the fluidized bed through the steam pipe, wait until the steam fills the fluidized bed and there is no air in the fluidized bed, and then calculate the content of aluminum powder in the steam to be 600g / m 3 The high-purity aluminum powder with a particle size of 500μm and a purity of ≥99.99% is added into the fluidized bed through a quantitative feeder, and the high-purity aluminum powder falls on the air permeable layer; Step (3) is specifically as follows: setting the reaction temperature in the fluidized bed to 130°C and the reaction time to 3 hours, and starting the centrifugal fan at the same time, so that the high-purity aluminum powder and water vapor undergo a hydrothermal reaction to obtain a reaction product, aluminum hydroxide, and a side reaction product, hydrogen. During the reaction, the pressure and temperature conditions in the fluidized bed are respectively monitored in real time by a pressure transmitter and a temperature transmitter. Hydrogen and water vapor flow out from the reaction gas outlet and enter the heat exchanger through an outlet pipe. After the hydrogen and water vapor are cooled by the heat exchanger, the hydrogen temperature is reduced and is extracted from the top outlet of the heat exchanger through a centrifugal fan. The hydrogen then enters the high-pressure hydrogen storage tank through a hydrogen delivery pipe. The water vapor condenses into condensed water and is discharged from the bottom condensed water outlet of the heat exchanger and refluxed to the water vapor generator through a condensed water reflux pipe. After the reaction is completed, the water vapor generator, the booster fan and the centrifugal fan are turned off, the hand valve is loosened to open the discharge port, and the aluminum hydroxide is discharged from the discharge port; Step (4) is specifically as follows: drying the aluminum hydroxide in an oven at 110°C for 24 hours, and then placing the dried aluminum hydroxide in a calcining furnace for calcining. The heating rate of the calcining furnace is controlled at 3-8°C / min. After the internal temperature of the calcining furnace is raised to 1250°C, it is kept warm for 3 hours to obtain high-purity aluminum oxide powder.

Images