System and method for producing aluminum nitride from aluminum oxide

Abstract

The application discloses a system and method for preparing aluminum nitride from aluminum oxide. First, carbon tetrachloride is used to chlorinate aluminum oxide fine powder into aluminum chloride in a fluidized bed of an external force field, and then, the aluminum chloride is nitrided into aluminum nitride product in a fluidized bed with the addition of seed powder and ammonia. The application uses carbon tetrachloride as a chlorinating agent for the chlorination reaction of aluminum oxide, and does not need to prepare carbon and ball, and is simple to operate, and the product is easy to separate and purify. The fluidized bed is used as a chlorination and nitridation reactor, the mass and heat transfer rate between gas and solid phases is fast, and the reaction efficiency is high. The external force field arranged in the chlorination reactor can significantly improve the fluidization quality and the gas-solid contact efficiency. The seed powder added in the nitridation reactor can provide nucleation sites and matrix, promote the occurrence of the nitridation reaction, and facilitate the collection of the product, and meanwhile, the system has high energy utilization rate, can realize large-scale and efficient preparation of aluminum nitride from aluminum oxide, and has good economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of non-ferrous metallurgy and environmental protection, and particularly relates to a system and method for preparing aluminum nitride from aluminum oxide. BACKGROUND

[0002] Aluminum nitride ceramic has good heat conduction performance, a linear expansion coefficient close to that of silicon, high volume resistivity, small dielectric constant and dielectric loss, high temperature resistance and corrosion resistance, good mechanical properties, and better comprehensive performance than aluminum oxide and beryllium oxide. It is an ideal material for new-generation semiconductor substrates and electronic device packaging, and has a very broad application prospect in the electronic industry.

[0003] There are mainly carbon thermal reduction method, metal direct nitriding method, self-propagating high-temperature synthesis method, and chemical vapor deposition method for preparing aluminum nitride powder, among which the carbon thermal reduction method is the most widely used. Chinese Patent Application CN102249689A discloses a method for preparing aluminum nitride powder. First, phenolic resin and aluminum oxide powder are mixed into a mud, which is then subjected to heat curing, powdering, and briquetting, and then placed in a nitrogen atmosphere at 1300-2000℃ for 6-8h. Then, the nitrided product is decarburized in an oxidizing atmosphere at 350-550℃ for 6-12h, and then pulverized to obtain aluminum nitride powder. Although this method can obtain ultra-fine aluminum nitride powder with high purity, the nitriding reaction temperature is high, the energy consumption is large, and the subsequent decarburization process is long, resulting in low production efficiency. Chinese Patent Application CN106082149A discloses a method for preparing aluminum nitride powder. First, pseudo-boehmite gel, inorganic carbon source, water-soluble organic carbon source, and additives are mixed, and then placed in a nitrogen atmosphere at 1600℃ for 10h. Then, the nitrided product is decarburized in air at 660℃ for 3h to obtain aluminum nitride powder with high purity. The use of pseudo-boehmite gel and water-soluble carbon source in this method can effectively improve the contact efficiency between aluminum oxide and the reducing agent carbon, and strengthen the carbon thermal reduction reaction. However, the preparation process of pseudo-boehmite gel is complex and costly, and there are also problems such as high energy consumption and long decarburization period. Chinese Patent Application CN109437130A discloses a method for preparing aluminum nitride powder. First, aluminum hydroxide powder and carbon powder are mixed and dispersed, and then added to an aqueous solution containing acetic acid and citric acid. The mixture is granulated and dried, and then calcined in an inert atmosphere at 350-600℃. The calcined product is then impregnated with a sucrose or glucose solution, dried, and inertly calcined to obtain a carbon-containing aluminum oxide composite powder with high dispersion and close contact. The composite powder is then placed in a nitrogen atmosphere at 1400-1600℃ for 2-10h, and the obtained nitrided product is decarburized at 500℃ for more than 8h to obtain aluminum nitride powder. Although this method can obtain aluminum nitride powder with low oxygen and carbon content, the process flow is long, the operation is complex, the energy consumption is high, the decarburization period is long, and it is difficult to realize large-scale production.

[0004] Therefore, in view of the current situation that aluminum nitride cannot be efficiently prepared by current process technology, through process and technical innovation, the reaction process is strengthened, the reaction efficiency is improved, and the process energy consumption is reduced, which is the key to realize large-scale and efficient aluminum nitride of aluminum oxide. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application aims to provide a system and method for preparing aluminum nitride from aluminum oxide, which is simple to operate, simple in equipment, low in energy consumption and easy to control, and can be produced in large scale and continuously.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A system for preparing aluminum nitride from aluminum oxide comprises an aluminum oxide bin, an aluminum oxide feeder, a chlorination fluidized bed, a first cyclone separator I, a second cyclone separator I, a return valve I, a heat exchanger I, a gas heater I, an induced draft fan I, a condenser I, a gasifier I, a condenser II, a gas collecting device, a gasifier II, a nitriding fluidized bed, a first cyclone separator II, a second cyclone separator II, a return valve II, a product bin, a heat exchanger II, a gas heater II, a condenser III, a dust collecting device and an induced draft fan II.

[0008] The aluminum oxide bin, the aluminum oxide feeder and the chlorination fluidized bed are connected in sequence along the direction of material flow, the gas inlet and the gas outlet of the chlorination fluidized bed are connected with the gas outlet of the gas heater I and the gas inlet of the first cyclone separator I respectively, and the discharge port of the first cyclone separator I is connected with the feed inlet of the return valve I; the gas inlet, the gas outlet and the discharge port of the second cyclone separator I are connected with the gas outlet of the first cyclone separator I, the hot gas inlet of the heat exchanger I and the feed inlet of the return valve I respectively; the discharge port of the return valve I is connected with the upper return port of the chlorination fluidized bed, the gas inlet of the return valve I is connected with the gas outlet of the gas heater I, the gas inlet of the gas heater I is connected with the hot gas outlet of the heat exchanger I, the cold gas outlet of the heat exchanger I is connected with the gas inlet of the induced draft fan I, the gas outlet of the induced draft fan I is connected with the gas inlet of the condenser I, the gas outlet of the condenser I is connected with the gas inlet of the condenser II, the discharge port of the condenser I is connected with the gas inlet of the gasifier I; the liquid outlet of the condenser II is connected with the liquid inlet of the gasifier II, the gas outlet of the gasifier II is connected with the cold gas inlet of the heat exchanger I, the gas outlet of the condenser II is connected with the gas inlet of the gas collecting device, and the gas outlet of the gasifier I is connected with the feed inlet of the nitriding fluidized bed.

[0009] The gas inlet, gas outlet and material outlet of the nitriding fluidized bed are connected with the gas outlet of the gas heater II, the gas inlet of the primary cyclone separator II and the material inlet of the product bin respectively; the material outlet of the primary cyclone separator II is connected with the material inlet of the back feeding valve II, the gas inlet of the secondary cyclone separator II, the hot gas inlet of the heat exchanger II and the material inlet of the back feeding valve II are connected with the gas outlet of the primary cyclone separator II, the hot gas outlet of the heat exchanger II and the material inlet of the back feeding valve II respectively; the material outlet of the back feeding valve II is connected with the upper back feeding inlet of the nitriding fluidized bed, the gas inlet of the back feeding valve II is connected with the gas outlet of the gas heater II, the gas inlet of the gas heater II is connected with the hot gas outlet of the heat exchanger II, the cold gas outlet of the heat exchanger II is connected with the gas inlet of the condenser III; the dust outlet of the condenser III is connected with the material inlet of the dust collecting device, the gas outlet of the condenser III is connected with the gas inlet of the induced draft fan II, and the gas outlet of the induced draft fan II is connected with the cold gas inlet of the heat exchanger II;

[0010] The room temperature carbon tetrachloride pipeline is connected with the liquid inlet of the gasifier II, and the room temperature ammonia gas pipeline is connected with the cold gas inlet of the heat exchanger II.

[0011] Further, the chlorination fluidized bed is provided with an external force field generating device, which is one or a combination of a sound field generating device or a vibration field generating device.

[0012] Further, the nitriding fluidized bed is provided with seed powder, which is aluminum nitride with a particle size of 0.1-0.5 mm.

[0013] The application also provides a working method of the above-mentioned system for preparing aluminum nitride from aluminum oxide, and the specific process is as follows:

[0014] The aluminum oxide fine powder is stored in the aluminum oxide bin and enters the chlorination fluidized bed through the aluminum oxide feeder;

[0015] The room temperature carbon tetrachloride enters the gasifier II from the room temperature carbon tetrachloride pipeline and is gasified into gaseous carbon tetrachloride, the gaseous carbon tetrachloride enters the gas heater I through the heat exchanger I and is heated into high-temperature carbon tetrachloride, and the high-temperature carbon tetrachloride is sent into the chlorination fluidized bed;

[0016] In the chlorination fluidized bed, the aluminum oxide fine powder and the high-temperature carbon tetrachloride perform chlorination reaction to obtain mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride, and the mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride enters the heat exchanger I after being dusted by the primary cyclone separator I and the secondary cyclone separator I under the action of the induced draft fan I; the dust recovered by the primary cyclone separator I and the secondary cyclone separator I returns to the chlorination fluidized bed in a fluidized state in the back feeding valve I under the action of the high-temperature carbon tetrachloride.

[0017] The mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust removal is cooled by heat exchange in the heat exchanger I, and then enters the condenser I to be condensed to obtain mixed gas of carbon dioxide and carbon tetrachloride and solid-phase aluminum chloride, the mixed gas of carbon dioxide and carbon tetrachloride is sent into the condenser II to be further condensed to obtain carbon dioxide and liquid-phase carbon tetrachloride, the carbon dioxide is sent into the gas collecting device, the liquid-phase carbon tetrachloride is sent into the gasifier II to be gasified to obtain gas-phase carbon tetrachloride, and the gas-phase carbon tetrachloride is sent into the heat exchanger I to be heated by heat exchange with the mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust removal to become hot carbon tetrachloride, and the hot carbon tetrachloride is sent into the gas heater I to be further heated to become high-temperature carbon tetrachloride;

[0018] The solid-phase aluminum chloride enters the gasifier I to be gasified to obtain gas-phase aluminum chloride, and then enters the nitriding fluidized bed;

[0019] The room-temperature ammonia gas is heated into high-temperature ammonia gas in the heat exchanger II and the gas heater II, and the high-temperature ammonia gas is sent into the nitriding fluidized bed;

[0020] In the nitriding fluidized bed, the gas-phase aluminum chloride is reacted with the high-temperature ammonia gas to obtain mixed flue gas of ammonia gas and hydrogen chloride and aluminum nitride, the aluminum nitride enters the product bin, the mixed flue gas of ammonia gas and hydrogen chloride is collected after dust removal by the first cyclone separator II and the second cyclone separator II under the action of the induced draft fan II, and then enters the heat exchanger II, the dust collected by the first cyclone separator II and the second cyclone separator II is returned to the nitriding fluidized bed in a fluidized state under the action of the high-temperature ammonia gas, the mixed flue gas of ammonia gas and hydrogen chloride after dust removal is cooled by heat exchange in the heat exchanger II, and then enters the condenser III to be further condensed to obtain ammonia gas and solid-phase ammonium chloride, the solid-phase ammonium chloride is sent into the dust collecting device, and the ammonia gas is heated by heat exchange with the mixed flue gas of ammonia gas and hydrogen chloride after dust removal in the heat exchanger II to become hot ammonia gas, and the hot ammonia gas is sent into the gas heater II to be further heated to become high-temperature ammonia gas.

[0021] Further, the particle size of the alumina fine powder is less than 1 μm.

[0022] Further, the temperature of the chlorination reaction is 500-700 ℃, and the time is 0.5-1 h.

[0023] Further, the temperature of the nitriding reaction is 700-900 ℃, and the time is 0.5-1 h.

[0024] Further, the condensing temperature in the condenser I is 90-170 ℃, the condensing temperature in the condenser II is 20-60 ℃, and the condensing temperature in the condenser III is 20-200 ℃.

[0025] The beneficial effects of the present application are as follows:

[0026] 1. This invention uses carbon tetrachloride, a byproduct of the chloroalkane industry, as the chlorinating agent in the chlorination reaction of alumina. It eliminates the need for carbon preparation and pelletizing, making the operation simple and the process straightforward. Furthermore, the product is easy to separate and purify, resulting in significant economic and social benefits.

[0027] 2. This invention uses ammonia as a nitriding agent to react with gaseous aluminum chloride to prepare aluminum nitride. The gas-gas reaction is highly efficient and rapid, with low production cost and high efficiency.

[0028] 3. This invention uses a gas-solid fluidized bed as a chlorination and nitridation reactor, which has good gas-solid phase mixing and contact, fast mass and heat transfer rates, high reaction efficiency, and is convenient for continuous operation and large-scale processing.

[0029] 4. The present invention provides an external force field generating device in the chlorination reactor to break up bubbles, prevent fine particle agglomeration, significantly improve fluidization quality, and increase gas-solid contact efficiency; adding seed powder to the nitriding reactor can provide nucleation sites and matrix for the nitriding reaction, promote the occurrence of the nitriding reaction, and the product obtained from the reaction is easy to collect.

[0030] 5. This invention has a high waste heat recovery and utilization rate, which effectively improves the thermal efficiency of the overall process system. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the system structure in Embodiment 1 of the present invention. Detailed Implementation

[0032] The present invention will be further described below with reference to the accompanying drawings. It should be noted that this embodiment is based on the present technical solution and provides detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to this embodiment.

[0033] Example 1

[0034] This embodiment provides a system for preparing aluminum nitride from alumina, such as... Figure 1 As shown, the system includes an alumina silo 1, an alumina feeder 2, a chlorination fluidized bed 3, an external force field generating device 4, a primary cyclone separator I 5, a secondary cyclone separator I 6, a return valve I 7, a heat exchanger I 8, a gas heater I 9, an induced draft fan I 10, a condenser I 11, a gasifier I 12, a condenser II 13, a gas collection device 14, a gasifier II 15, a nitriding fluidized bed 16, seed powder 17, a primary cyclone separator II 18, a secondary cyclone separator II 19, a return valve II 20, a product silo 21, a heat exchanger II 22, a gas heater II 23, a condenser III 24, a dust collection device 25, and an induced draft fan II 26.

[0035] The alumina bunker 1, the alumina feeder 2 and the chlorination fluidized bed 3 are connected in sequence along the direction of material flow, the gas inlet and the gas outlet of the chlorination fluidized bed 3 are connected with the gas outlet of the gas heater I 9 and the gas inlet of the primary cyclone separator I 5 respectively, the material outlet of the primary cyclone separator I 5 is connected with the material inlet of the back material valve I 7; the gas inlet, the gas outlet and the material outlet of the secondary cyclone separator I 6 are connected with the gas outlet of the primary cyclone separator I 5, the hot gas inlet of the heat exchanger I 8 and the material inlet of the back material valve I 7 respectively; the material outlet of the back material valve I 7 is connected with the upper back material inlet of the chlorination fluidized bed 3, the gas inlet of the back material valve I 7 is connected with the gas outlet of the gas heater I 9, the gas inlet of the gas heater I 9 is connected with the hot gas outlet of the heat exchanger I 8, the gas outlet of the heat exchanger I 8 is connected with the gas inlet of the induced draft fan I 10, the gas outlet of the induced draft fan I 10 is connected with the gas inlet of the condenser I 11, the gas outlet of the condenser I 11 is connected with the gas inlet of the condenser II 13, the material outlet of the condenser I 11 is connected with the gas inlet of the gasifier I 12; the liquid outlet of the condenser II 13 is connected with the liquid inlet of the gasifier II 15, the gas outlet of the gasifier II 15 is connected with the cold gas inlet of the heat exchanger I 8, the gas outlet of the condenser II 13 is connected with the gas inlet of the gas collecting device 14, the gas outlet of the gasifier I 12 is connected with the material inlet of the nitriding fluidized bed 16;

[0036] The gas inlet, gas outlet and material outlet of the nitriding fluidized bed 16 are connected with the gas outlet of the gas heater II 23, the gas inlet of the primary cyclone II 18 and the material inlet of the product bin 21 respectively; the material outlet of the primary cyclone II 18 is connected with the material inlet of the return valve II 20, the gas inlet, gas outlet and material outlet of the secondary cyclone II 19 are connected with the gas outlet of the primary cyclone II 18, the hot gas inlet of the heat exchanger II 22 and the material inlet of the return valve II 20 respectively; the material outlet of the return valve II 20 is connected with the upper material return port of the nitriding fluidized bed 16, the gas inlet of the return valve II 20 is connected with the gas outlet of the gas heater II 23, the gas inlet of the gas heater II 23 is connected with the hot gas outlet of the heat exchanger II 22, the cold gas outlet of the heat exchanger II 22 is connected with the gas inlet of the condenser III 24; the dust outlet of the condenser III 24 is connected with the material inlet of the dust collecting device 25, the gas outlet of the condenser III 24 is connected with the gas inlet of the induced draft fan II 26, the gas outlet of the induced draft fan II 26 is connected with the cold gas inlet of the heat exchanger II 22;

[0037] The room temperature carbon tetrachloride pipeline is connected with the liquid inlet of the gasifier II 15, and the room temperature ammonia gas pipeline is connected with the cold gas inlet of the heat exchanger II 22.

[0038] In the embodiment, the chlorination fluidized bed 3 is provided with an external force field generating device 4, which is one or a combination of a sound field generating device or a vibration field generating device, for breaking up clusters, eliminating bubbles and strengthening gas-solid contact.

[0039] In the embodiment, seed powder is provided in the nitriding fluidized bed 3, which is aluminum nitride with a particle size of 0.1-0.5 mm, for providing nucleation sites and matrix for the nitriding reaction and promoting the occurrence of the nitriding reaction.

[0040] Embodiment 2

[0041] The embodiment provides a working method of the system for preparing aluminum nitride from aluminum oxide in embodiment 1, and the specific process is as follows:

[0042] The aluminum oxide fine powder is stored in the aluminum oxide bin 1 and enters the chlorination fluidized bed 3 through the aluminum oxide feeder 2.

[0043] The room temperature carbon tetrachloride enters the gasifier II 15 from the room temperature carbon tetrachloride pipeline to be gasified into gaseous carbon tetrachloride, the gaseous carbon tetrachloride enters the gas heater I 9 through the heat exchanger I 8 to be heated into high-temperature carbon tetrachloride, and the high-temperature carbon tetrachloride is sent into the chlorination fluidized bed 3.

[0044] In the chlorination fluidized bed 3, the fine alumina powder is chlorinated with high-temperature carbon tetrachloride under the assistance of the external force field device 4 to obtain a mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride, and the mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride is sequentially collected by a first cyclone separator I 5 and a second cyclone separator I 6 under the action of a draught fan I 10, and then enters a heat exchanger I 8 after dust collection, and the dust recovered by the first cyclone separator I 5 and the second cyclone separator I 6 is returned to the chlorination fluidized bed 3 in a fluidized state under the action of high-temperature carbon tetrachloride in a return valve I 7;

[0045] The mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust collection is cooled after heat exchange in the heat exchanger I 8, and then enters a condenser I 11 to be condensed to obtain a mixed gas of carbon dioxide and carbon tetrachloride and solid-phase aluminum chloride, the mixed gas of carbon dioxide and carbon tetrachloride is sent to a condenser II 13 for further condensation to obtain carbon dioxide and liquid-phase carbon tetrachloride, the carbon dioxide is sent to a gas collecting device 14, the liquid-phase carbon tetrachloride is sent to a gasifier II 15 for gasification to obtain gas-phase carbon tetrachloride, and the gas-phase carbon tetrachloride is sent to the heat exchanger I 8 to exchange heat with the mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust collection to be heated to hot carbon tetrachloride, and the hot carbon tetrachloride is sent to a gas heater I 9 for further heating to high-temperature carbon tetrachloride;

[0046] The solid-phase aluminum chloride enters a gasifier I 12 for gasification to obtain gas-phase aluminum chloride, and then enters a nitriding fluidized bed 16;

[0047] The room-temperature ammonia gas is heated to high-temperature ammonia gas in the gas heater II 23 from the room-temperature ammonia gas pipeline through the heat exchanger II 22, and the high-temperature ammonia gas is sent to the nitriding fluidized bed 16;

[0048] In the nitriding fluidized bed 16, the gas-phase aluminum chloride is nitrided with high-temperature ammonia gas under the action of seed powder to obtain a mixed flue gas of ammonia gas and hydrogen chloride and aluminum nitride, the aluminum nitride enters a product bin 21, the mixed flue gas of ammonia gas and hydrogen chloride is sequentially collected by a first cyclone separator II 18 and a second cyclone separator II 19 under the action of a draught fan II 26, and then enters the heat exchanger II 22 after dust collection, the dust recovered by the first cyclone separator II 18 and the second cyclone separator II 19 is returned to the nitriding fluidized bed 16 in a fluidized state under the action of high-temperature ammonia gas in a return valve II 20, the mixed flue gas of ammonia gas and hydrogen chloride after dust collection is cooled by heat exchange in the heat exchanger II 22, and then enters a condenser III 24, and further condensation obtains ammonia gas and solid-phase ammonium chloride, the solid-phase ammonium chloride is sent to a dust collecting device 25, and the ammonia gas is heated to hot ammonia gas by heat exchange with the mixed flue gas of ammonia gas and hydrogen chloride after dust collection in the heat exchanger II 22, and the hot ammonia gas is further heated to high-temperature ammonia gas in the gas heater II 23.

[0049] In this embodiment, the particle size of the alumina fine powder is less than 1 μm.

[0050] In this embodiment, the temperature of the chlorination reaction is 500°C and the time is 1 h.

[0051] In this embodiment, the temperature of the nitridation reaction is 700°C and the time is 1 h.

[0052] In this embodiment, the condensing temperature in the condenser I is 90°C, the condensing temperature in the condenser II is 20°C, and the condensing temperature in the condenser III is 20°C.

[0053] Example 3

[0054] This embodiment is basically the same as Example 2, and the same parts will not be described again. The difference is that in this embodiment, the temperature of the chlorination reaction is 700°C and the time is 0.5 h. The temperature of the nitridation reaction is 900°C and the time is 0.5 h. The condensing temperature in the condenser I is 170°C, the condensing temperature in the condenser II is 60°C, and the condensing temperature in the condenser III is 200°C.

[0055] Example 4

[0056] This embodiment is basically the same as Example 2, and the same parts will not be described again. The difference is that in this embodiment, the temperature of the chlorination reaction is 600°C and the time is 0.7 h. The temperature of the nitridation reaction is 800°C and the time is 0.8 h. The condensing temperature in the condenser I is 140°C, the condensing temperature in the condenser II is 40°C, and the condensing temperature in the condenser III is 100°C.

[0057] For those skilled in the art, various corresponding changes and modifications can be made according to the above technical solutions and concepts, and all these changes and modifications should be included in the protection scope of the claims of the present application.

Claims

1. A method for producing aluminum nitride from aluminum oxide, characterized by, The specific process is as follows: The alumina fine powder is stored in an alumina bin and enters a chlorination fluidized bed through an alumina feeder; Room temperature carbon tetrachloride enters a vaporizer II from a room temperature carbon tetrachloride pipeline and is vaporized into gaseous carbon tetrachloride, which is heated into high-temperature carbon tetrachloride in a gas heater I through a heat exchanger I, and then is sent into the chlorination fluidized bed; In the chlorination fluidized bed, the alumina fine powder is chlorinated with the high-temperature carbon tetrachloride to obtain a mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride, which is collected by a primary cyclone I and a secondary cyclone I in sequence under the action of an induced draft fan I, and then is sent into the heat exchanger I after dust removal; the dust collected by the primary cyclone I and the secondary cyclone I is returned to the chlorination fluidized bed in a fluidized state in a return valve I under the action of the high-temperature carbon tetrachloride; The mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust removal is cooled by heat exchange in the heat exchanger I, and then is sent into a condenser I to be condensed into a mixed gas of carbon dioxide and carbon tetrachloride and solid-phase aluminum chloride; the mixed gas of carbon dioxide and carbon tetrachloride is sent into a condenser II to be further condensed into carbon dioxide and liquid-phase carbon tetrachloride; the carbon dioxide is sent into a gas collecting device; the liquid-phase carbon tetrachloride is sent into the vaporizer II to be vaporized into gaseous carbon tetrachloride, which is sent into the heat exchanger I to be heated into hot carbon tetrachloride by heat exchange with the mixed flue gas of carbon dioxide, aluminum chloride and carbon tetrachloride after dust removal, and then is sent into the gas heater I to be further heated into high-temperature carbon tetrachloride; The solid-phase aluminum chloride is sent into a vaporizer I to be vaporized into gaseous aluminum chloride, and then is sent into a nitriding fluidized bed; Room temperature ammonia gas is heated into high-temperature ammonia gas in a gas heater II through a heat exchanger II, and then is sent into the nitriding fluidized bed; In the nitriding fluidized bed, the gaseous aluminum chloride is nitrided with the high-temperature ammonia gas to obtain a mixed flue gas of ammonia gas and hydrogen chloride and nitride aluminum; the nitride aluminum is sent into a product bin; the mixed flue gas of ammonia gas and hydrogen chloride is collected by a primary cyclone II and a secondary cyclone II in sequence under the action of an induced draft fan II, and then is sent into the heat exchanger II after dust removal; the dust collected by the primary cyclone II and the secondary cyclone II is returned to the nitriding fluidized bed in a fluidized state in a return valve II under the action of the high-temperature ammonia gas; the mixed flue gas of ammonia gas and hydrogen chloride after dust removal is cooled by heat exchange in the heat exchanger II, and then is sent into a condenser III to be further condensed into ammonia gas and solid-phase ammonium chloride; the solid-phase ammonium chloride is sent into a dust collecting device; the ammonia gas is heated into hot ammonia gas by heat exchange with the mixed flue gas of ammonia gas and hydrogen chloride after dust removal in the heat exchanger II, and then is sent into the gas heater II to be further heated into high-temperature ammonia gas; The chlorination reaction is carried out at a temperature of 500-700℃ for 0.5-1h; the nitriding reaction is carried out at a temperature of 700-900℃ for 0.5-1h.

2. The method of claim 1, wherein, The particle size of the alumina fine powder is less than 1μm.

3. The method of claim 1, wherein, The condensing temperature in the condenser I is 90-170℃, the condensing temperature in the condenser II is 20-60℃, and the condensing temperature in the condenser III is 20-200℃.

4. A system for implementing the method of any one of claims 1 to 3, characterized in that, The alumina bin, the alumina feeder, the chlorination fluidized bed, the first-stage cyclone I, the second-stage cyclone I, the return valve I, the heat exchanger I, the gas heater I, the induced draft fan I, the condenser I, the vaporizer I, the condenser II, the gas collecting device, the vaporizer II, the nitriding fluidized bed, the first-stage cyclone II, the second-stage cyclone II, the return valve II, the product bin, the heat exchanger II, the gas heater II, the condenser III, the dust collecting device and the induced draft fan II are sequentially connected along the direction of material flow. The gas inlet, the gas outlet and the material outlet of the chlorination fluidized bed are connected with the gas outlet of the gas heater I, the gas inlet of the first-stage cyclone I and the material inlet of the return valve I respectively; the gas inlet, the gas outlet and the material outlet of the first-stage cyclone I are connected with the gas outlet of the first-stage cyclone I, the hot gas inlet of the heat exchanger I and the material inlet of the return valve I respectively; the material outlet of the return valve I is connected with the upper material return port of the chlorination fluidized bed, the gas inlet of the return valve I is connected with the gas outlet of the gas heater I, the gas inlet of the gas heater I is connected with the hot gas outlet of the heat exchanger I, the cold gas outlet of the heat exchanger I is connected with the gas inlet of the induced draft fan I, the gas outlet of the induced draft fan I is connected with the gas inlet of the condenser I, the gas outlet of the condenser I is connected with the gas inlet of the condenser II, the material outlet of the condenser I is connected with the gas inlet of the vaporizer I; the liquid outlet of the condenser II is connected with the liquid inlet of the vaporizer II, the gas outlet of the vaporizer II is connected with the cold gas inlet of the heat exchanger I, the gas outlet of the condenser II is connected with the gas inlet of the gas collecting device, the gas outlet of the vaporizer I is connected with the material inlet of the nitriding fluidized bed. The gas inlet, the gas outlet and the material outlet of the nitriding fluidized bed are connected with the gas outlet of the gas heater II, the gas inlet of the first-stage cyclone II and the material inlet of the product bin respectively; the material outlet of the first-stage cyclone II is connected with the material inlet of the return valve II, the gas inlet, the gas outlet and the material outlet of the second-stage cyclone II are connected with the gas outlet of the first-stage cyclone II, the hot gas inlet of the heat exchanger II and the material inlet of the return valve II respectively; the material outlet of the return valve II is connected with the upper material return port of the nitriding fluidized bed, the gas inlet of the return valve II is connected with the gas outlet of the gas heater II, the gas inlet of the gas heater II is connected with the hot gas outlet of the heat exchanger II, the cold gas outlet of the heat exchanger II is connected with the gas inlet of the condenser III; the dust outlet of the condenser III is connected with the material inlet of the dust collecting device, the gas outlet of the condenser III is connected with the gas inlet of the induced draft fan II, the gas outlet of the induced draft fan II is connected with the cold gas inlet of the heat exchanger II. A carbon tetrachloride pipeline at room temperature is connected to the liquid inlet of the vaporizer II, and an ammonia gas pipeline at room temperature is connected to the cold gas inlet of the heat exchanger II.

5. The system of claim 4, wherein, The chlorination fluidized bed is provided with an external force field generating device, which is one or a combination of a sound field generating device or a vibration field generating device.

6. The system of claim 4, wherein, The seed powder in the nitriding fluidized bed is aluminum nitride with a particle size of 0.1-0.5 mm.

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