Purification method for anhydrous aluminum chloride, and gas-phase nano-alumina preparation device and method therefor

Abstract

A purification method for anhydrous aluminum chloride, and a gas-phase nano-alumina preparation device and a method therefor, belonging to the field of inorganic chemistry. Said purification method comprises the following steps: pulverizing an anhydrous aluminum chloride raw material into a powder, introducing the powder obtained by the pulverization and hot air into a sublimator, such that the powder is heated by the hot air so as to obtain an aluminum chloride sublimation gas, the temperature in the sublimator being 250-350 ℃, and the temperature of the hot air being 250-500 ℃; and introducing the aluminum chloride sublimation gas into a cyclone separation mechanism to perform cyclone separation, so as to obtain an aluminum chloride gas, the temperature in the cyclone separation mechanism being 200-300 ℃. Said purification method can completely remove hygroscopic solid impurities, such as hydrated aluminum chloride and ferric trichloride, in the anhydrous aluminum chloride raw material, so that the iron content of the obtained aluminum trichloride finished product is reduced to 72 ppm or below, and the content of water-insoluble substances is reduced to 0.03%.

Description

A method for purifying anhydrous aluminum chloride, a device for preparing nano-alumina by vapor phase method and a method thereof

[0001] The present invention claims priority to the Chinese patent application filed with the Patent Office of China on November 9, 2023, with application number 202311489381X, entitled “A method for purifying anhydrous aluminum chloride”, and the Chinese patent application filed with the Patent Office of China on November 9, 2023, with application number 2023114893805, entitled “Device for preparing low-iron content gas-phase nano-alumina and its preparation method”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] The present invention belongs to the technical field of inorganic chemistry, and in particular relates to a method for purifying anhydrous aluminum chloride, a device for preparing nano-aluminum oxide using a vapor phase method and a method thereof. Background Art

[0003] As a high-end nano-chemical raw material, fumed alumina nanoparticles are widely used in powder coatings, lithium batteries, thermal insulation materials, catalysis, and other industries. Different application areas place different technical requirements on fumed alumina. In the field of powder coatings, fumed alumina primarily serves to improve the fluidity of powder coatings, electrostatic spraying performance, and coating optical properties. Therefore, high requirements are placed on the particle fineness and uniformity of fumed alumina products. In the lithium battery industry, fumed alumina is primarily used to modify battery positive electrode materials and diaphragm materials. These industries have high requirements for the purity of fumed alumina, especially for the content of magnetic substances such as iron and nickel. Impurities in fumed alumina products are primarily introduced by the raw material, anhydrous aluminum chloride. Currently, the majority of raw materials used in fumed alumina production are industrial anhydrous aluminum chloride. Due to limitations in domestic anhydrous aluminum chloride production processes, a small amount of aluminum chlorohydrate is generated during normal production due to hydrolysis from the absorption of moisture from the air. This hydrated aluminum chlorohydrate, upon entering the production system, is heated to form large white particles, which can easily form white spots in powder coating applications, affecting product quality. Furthermore, the production equipment currently used for anhydrous aluminum chloride in China is primarily carbon steel, which introduces iron into the raw material during production, resulting in high iron content in the resulting anhydrous aluminum chloride products. The national standard for "Industrial Anhydrous Aluminum Chloride" (GB / T3959-2008) stipulates that the iron content (calculated as FeCl3) of qualified, first-grade, and superior-grade industrial anhydrous aluminum chloride products is 0.08%, 0.05%, and 0.04%, respectively. In addition, some water-insoluble matter and other heavy metals are also present. Typically, in fumed alumina production, raw material vaporization and slag removal can remove some impurities, meeting most application requirements. However, this approach struggles to meet the increasingly demanding performance requirements of lithium batteries. While high-purity fumed alumina products can be produced using high-purity aluminum chloride as raw material, this significantly increases costs, limiting its application.

[0004] Summary of the Invention

[0005] The object of the present invention is to provide a purification method for anhydrous aluminum chloride, which can purify industrial anhydrous aluminum chloride and effectively remove impurities in industrial anhydrous aluminum chloride.

[0006] The above-mentioned objectives are achieved by the following technical solutions.

[0007] A first aspect of the present invention provides a method for purifying anhydrous aluminum chloride, the method comprising the following steps:

[0008] Grinding anhydrous aluminum chloride raw material into powder, passing the ground powder and hot air into a sublimator, wherein the hot air heats the powder to obtain aluminum chloride sublimation gas, wherein the temperature in the sublimator is 250° C. to 350° C., and the temperature of the hot air is 250° C. to 500° C.;

[0009] The sublimated aluminum chloride gas is introduced into a cyclone separation mechanism for cyclone separation to obtain aluminum chloride gas; the temperature in the cyclone separation mechanism is 200° C. to 300° C.

[0010] In some embodiments, the temperature of the sublimator is 280°C to 300°C, and the temperature of the hot air is 280°C to 350°C.

[0011] In some embodiments, the temperature of the sublimator is 290°C to 300°C, and the temperature of the hot air is 300°C to 320°C.

[0012] In some embodiments, the cyclone separation mechanism includes a first cyclone separator and a second cyclone separator connected in series, the aluminum chloride sublimation gas is passed into the first cyclone separator for cyclone separation at 200°C to 300°C, and the obtained gaseous product is passed into the second cyclone separator for cyclone separation at 200°C to 280°C.

[0013] In some embodiments, the temperature in the first cyclone separator is 250°C to 300°C, and the temperature in the second cyclone separator is 220°C to 260°C.

[0014] In some embodiments, the temperature in the first cyclone separator is 260°C to 280°C, and the temperature in the second cyclone separator is 240°C to 250°C.

[0015] The second aspect of the present invention provides a device for preparing nano-alumina by a vapor phase method, the device comprising a conveying and processing mechanism, a sublimator, a gas heating mechanism, a cyclone separation mechanism, a reactor, a deacidification furnace, and a magnetic deironing mechanism;

[0016] The conveying and processing mechanism is used to crush and convey the aluminum chloride raw material;

[0017] The sublimator has a feed port, a first air inlet, and a first air outlet; the conveying and processing mechanism is connected to the feed port of the sublimator and is used to feed the crushed aluminum chloride powder into the sublimator; the gas heating mechanism is connected to the first air inlet and is used to feed heated gas into the sublimator to heat the aluminum chloride powder;

[0018] The cyclone separation mechanism has a second air inlet and a second air outlet, the second air inlet is connected to the first air outlet, and the second air outlet is connected to the reactor, the deacidification furnace and the magnetic deironing mechanism in sequence.

[0019] In some embodiments, the magnetic iron removal mechanism includes at least two magnetic parts connected in sequence, the deacidified nano-alumina enters the magnetic parts in sequence, and a storage bin is provided between two adjacent magnetic parts. The magnetic part is a tubular structure, and the inner wall of the tubular structure is provided with a magnetic layer.

[0020] In some embodiments, the magnetic attraction layer includes a plurality of magnetic bodies, each of which is arranged at intervals along the circumferential direction and the axial direction of the tube structure, and along the axial direction of the tube structure, two adjacent magnetic bodies are staggered.

[0021] In some embodiments, the magnetic iron removal mechanism includes two magnetic components, and the two magnetic components cooperate to form a two-stage magnetic structure.

[0022] In some embodiments, the cyclone separation mechanism includes two cyclone separators connected in series, the two cyclone separators being a first cyclone separator and a second cyclone separator;

[0023] The first cyclone separator and the second cyclone separator both include a separator body, which is provided with the second air inlet and the second air outlet. The second air inlet is opened on the side wall of the separator body along the transverse cross-section direction of the separator body, and the second air inlet is located below the second air outlet.

[0024] In some embodiments, a first heating body is provided on the outer wall of the separator body, and a first heat-insulating layer is provided on the outer side of the separator body.

[0025] In some embodiments, a guide is provided in the sublimator, and the guide is provided between the feed port and the first air inlet, and the guide is used to guide the raw material powder entering from the feed port to the first air inlet to offset the hot air entering from the first air inlet.

[0026] In some embodiments, a second heating body is provided on the outer wall of the sublimator, and a second heat-insulating layer is provided on the outer side of the second heating body of the sublimator.

[0027] In some embodiments, the first gas outlet is opened on one side of the sublimator, and a gas outlet baffle is provided in the sublimator, the gas outlet baffle and the inner wall of the sublimator are enclosed to form a guide cavity with one end open, and the first gas outlet is connected to the guide cavity.

[0028] The third aspect of the present invention provides a method for preparing nano-alumina by a vapor phase method, the method comprising the following steps:

[0029] The aluminum chloride reaction raw materials are crushed by the conveying and processing mechanism and then conveyed to the sublimator. The gas heating mechanism heats the air and then conveys it to the sublimator. The hot air heats the aluminum chloride powder to obtain aluminum chloride sublimation gas.

[0030] The aluminum chloride sublimed gas is passed into a cyclone separation mechanism for cyclone separation to obtain aluminum chloride gas;

[0031] The obtained aluminum chloride gas is introduced into a reactor to react and generate nano-aluminum oxide;

[0032] The nano-alumina is sent into a deacidification furnace for deacidification;

[0033] The deacidified nano-alumina is sent to a magnetic de-ironing mechanism for magnetic de-ironing to obtain nano-alumina.

[0034] In the purification method of anhydrous aluminum chloride of the present invention, hot air at a specific temperature (250°C to 500°C) and industrial anhydrous aluminum chloride powder raw material are introduced into a sublimator at a specific temperature (250°C to 350°C). The aluminum chloride in the raw material is separated from the ferric chloride by gas-solid separation under the action of the hot air, wherein the aluminum chloride is gasified and sublimated. During the sublimation process, the hydrated aluminum chloride in the anhydrous aluminum chloride raw material is dehydrated to form aluminum oxide particles. In the subsequent cyclone separation process of the cyclone separation mechanism, the specific temperature of the cyclone separation mechanism is controlled (200°C to 300°C) so that the solid particles are separated in the cyclone. The centrifugal motion captures the gas, while the sublimed aluminum chloride gas remains in a gaseous state and is separated from the solid particles, thereby achieving the purification of the anhydrous aluminum chloride raw material. The water-absorbing solid impurities such as hydrated aluminum chloride and ferric chloride in the raw anhydrous aluminum chloride can be fully removed. The iron content of the obtained aluminum chloride product is reduced to below 72 ppm, and the content of water-insoluble matter is reduced to 0.03%. When the aluminum chloride is used in the preparation of aluminum oxide, the particulate matter in the finished aluminum oxide can be reduced by 99% on the original basis, and the iron content of the finished aluminum oxide can be reduced from the original above 400 ppm to below 200 ppm.

[0035] In the present invention, the gas phase method nano-alumina preparation device is provided with a conveying and processing mechanism, a sublimator and a cyclone separation mechanism at the front end of the reactor, and a deacidification furnace and a magnetic deironing mechanism at the rear end of the reactor. Before the aluminum chloride raw material is put into the reactor for reaction, the conveying and processing mechanism, the sublimator and the cyclone separation mechanism are used to cooperate to achieve the deironing and purification operation of the raw aluminum chloride. After the aluminum chloride gas after deironing and purification is sent into the reactor for reaction, the obtained nano-alumina product is deacidified by the deacidification furnace, and then the magnetic deironing mechanism is used to capture the magnetic iron substances in the nano-alumina product by adsorption, thereby achieving the deironing operation of the nano-alumina product. The iron content in the nano-alumina product can be reduced to below 150ppm, which well meets the application requirements in the lithium battery field. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG1 is a schematic diagram of the overall structure of a device for preparing nano-alumina by a vapor phase method according to an embodiment of the present invention;

[0037] FIG2 is a schematic diagram of a partial structure of the device for preparing nano-alumina by a vapor phase method in FIG1 ;

[0038] FIG3 is a schematic diagram of the longitudinal cross-section structure of the magnetic attraction component in FIG1 .

[0039] Explanation of the accompanying symbols: 100. Device for preparing nano-alumina by the vapor phase method; 1. Conveying and processing mechanism; 2. Sublimator; 21. Feed port; 22. First air inlet; 23. First air outlet; 24. Guide member; 25. Air outlet baffle; 26. Second heating body; 27. Second thermal insulation layer; 28. Second slag discharge valve; 3. Gas heating mechanism; 4. Cyclone separation mechanism; 40. Cyclone separator; 41. Separator body; 42. Second air inlet; 43. Second air outlet; 44. First heating body; 45. First thermal insulation layer; 46. First slag discharge valve; 5. Reactor; 6. Deacidification furnace; 7. Magnetic iron removal mechanism; 71. Magnetic member; 72. Storage bin; 73. Magnetic body. DETAILED DESCRIPTION

[0040] To facilitate understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the present disclosure more thorough and comprehensive.

[0041] In the following examples, the experimental methods without specific conditions are generally carried out under conventional conditions or conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification are for the purpose of describing specific embodiments only and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] An embodiment of the present invention provides a method for purifying anhydrous aluminum chloride, the method comprising the following steps:

[0044] The anhydrous aluminum chloride raw material is crushed into powder, and the crushed powder and hot air are introduced into a sublimator 2. The hot air heats the powder to produce aluminum chloride sublimation gas. The temperature in the sublimator 2 is 250°C to 350°C, and the temperature of the hot air is 250°C to 500°C.

[0045] The sublimated aluminum chloride gas is introduced into the cyclone separation mechanism 4 for cyclone separation to obtain aluminum chloride gas; the temperature in the cyclone separation mechanism 4 is 200°C to 300°C.

[0046] The present invention has found that in the purification process of anhydrous aluminum chloride, by introducing hot air at a specific temperature (250°C to 500°C) and industrial anhydrous aluminum chloride powder raw material into a sublimator 2 at a specific temperature (250°C to 350°C), aluminum chloride in the raw material is separated from ferric chloride by the action of the hot air. The aluminum chloride is vaporized and sublimated. During the sublimation process, the hydrated aluminum chloride in the anhydrous aluminum chloride raw material is dehydrated to form aluminum oxide particles. In the subsequent cyclone separation process in the cyclone separation mechanism 4, the specific temperature of the cyclone separation mechanism 4 is controlled (200°C to 300°C) so that the solid particles are centrifugally captured in the cyclone, while the sublimated aluminum chloride gas remains in a gaseous state and is separated from the solid particles, thereby achieving the purification of the anhydrous aluminum chloride raw material. The hydrated aluminum chloride, ferric chloride and other solid impurities in the anhydrous aluminum chloride raw material can be fully removed, and the iron content of the obtained aluminum chloride product is reduced to below 72 ppm, and the content of water-insoluble matter is reduced to 0.03%. Applying this aluminum chloride to the preparation of alumina can reduce the particulate matter in the finished alumina by 99% compared to the original level, and can reduce the iron content of the finished product from more than 400 ppm to less than 200 ppm, which well meets the requirements for use in the lithium battery field.

[0047] Preferably, the temperature of the sublimator 2 is 280°C to 300°C, and the temperature of the hot air is 280°C to 350°C. Controlling the temperature of the sublimator 2 and the hot air within this preferred range can better achieve gas-solid separation of anhydrous aluminum chloride and ferric chloride, thereby improving the purity of anhydrous aluminum chloride. Further preferably, the temperature of the sublimator 2 is 290°C to 300°C, and the temperature of the hot air is 300°C to 320°C.

[0048] In some embodiments, the cyclone separation mechanism 4 includes a first cyclone separator and a second cyclone separator connected in series, the aluminum chloride sublimation gas is passed into the first cyclone separator for cyclone separation at 200°C to 300°C, and the obtained gaseous product is passed into the second cyclone separator for cyclone separation at 200°C to 280°C.

[0049] Preferably, the temperature in the first cyclone separator is 250°C to 300°C, and the temperature in the second cyclone separator is 220°C to 260°C. Further preferably, the temperature in the first cyclone separator is 260°C to 280°C, and the temperature in the second cyclone separator is 240°C to 250°C.

[0050] It can be understood that by arranging the first cyclone separator and the second cyclone separator to cooperate to form a two-stage cyclone separator in series, controlling the aluminum chloride sublimation gas to sequentially pass through the two cyclone separators in series for cyclone separation, and controlling the temperatures of the two cyclone separators to be within this preferred range, the aluminum chloride gas can be better kept in a gaseous state and separated from the solid particles in the cyclone, thereby effectively removing solid impurities such as aluminum chloride hydrate and ferric chloride.

[0051] The present invention provides a device 100 for preparing nano-alumina by a vapor phase method. As shown in Figures 1 to 3, the device 100 for preparing nano-alumina by a vapor phase method includes a conveying and processing mechanism 1, a sublimator 2, a gas heating mechanism 3, a cyclone separation mechanism 4, a reactor 5, a deacidification furnace 6 and a magnetic iron removal mechanism 7.

[0052] The conveying and processing mechanism 1 is used to crush and convey the aluminum chloride raw material. The conveying and processing mechanism 1 can be a screw conveyor. The screw conveyor can crush the aluminum chloride raw material and simultaneously convey the aluminum chloride powder to the next stage equipment during the crushing process. Here, the crushed aluminum chloride powder is conveyed to the sublimator 2 for further reaction.

[0053] The sublimator 2 has a feed port 21, a first air inlet 22 and a first air outlet 23; the conveying and processing mechanism 1 is connected to the feed port 21 of the sublimator 2 and is used to feed the crushed aluminum chloride powder into the sublimator 2, and the gas heating mechanism 3 is connected to the first air inlet 22 and is used to feed the heated gas into the sublimator 2 to heat the aluminum chloride powder; wherein, the gas, specifically air, is heated to a specific temperature by the gas heating mechanism 3 and fed into the sublimator 2 through the first air inlet 22, and the aluminum chloride powder enters the sublimator 2 through the feed port 21. Under the action of the hot air at a specific temperature, aluminum chloride can be separated from ferric chloride in a gas-solid manner, wherein the aluminum chloride is vaporized and sublimated. During the sublimation process, the hydrated aluminum chloride in the aluminum chloride will be dehydrated to form aluminum oxide particles, and the aluminum chloride sublimation gas carrying the particles is further passed into the next-level cyclone separation mechanism 4 for cyclone separation.

[0054] The cyclone separation mechanism 4 has a second air inlet 42 and a second air outlet 43. The second air inlet 42 is connected to the first air outlet 23, and the second air outlet 43 is connected to the reactor 5, the deacidification furnace 6, and the magnetic iron removal mechanism 7 in sequence. The sublimated aluminum chloride gas in the sublimator 2 enters the cyclone separation mechanism 4 through the first air outlet 23 and the second air inlet 42 in sequence. In the cyclone separation mechanism 4, solid particles are captured by centrifugal motion in the cyclone, while the sublimated aluminum chloride gas remains in a gaseous state and is separated from the solid particles, thereby achieving the sublimation and purification of the raw aluminum chloride, and fully removing the water-absorbing solid impurities such as hydrated aluminum chloride and ferric chloride in the raw aluminum chloride to obtain aluminum chloride gas.

[0055] The obtained aluminum chloride gas is introduced into the reactor 5 to react and generate nano-alumina; the nano-alumina is then sent to the deacidification furnace 6 for deacidification; the deacidified nano-alumina is sent to the magnetic deironing mechanism 7 for deironing to obtain nano-alumina, which can be sent to the product silo for storage.

[0056] In summary, the gas phase method nano-alumina preparation device 100 is provided with a conveying and processing mechanism 1, a sublimator 2 and a cyclone separation mechanism 4 at the front end of the reactor 5, and a deacidification furnace 6 and a magnetic deironing mechanism 7 at the rear end of the reactor 5. Before the aluminum chloride raw material is put into the reactor 5 for reaction, the conveying and processing mechanism 1, the sublimator 2 and the cyclone separation mechanism 4 are first used to cooperate to realize the deironing and purification operation of the raw aluminum chloride. The aluminum chloride gas after deironing and purification is sent to the reactor 5 for reaction to obtain a nano-alumina product. After deacidification by the deacidification furnace 6, the magnetic iron-like substances in the nano-alumina product are captured by adsorption in cooperation with the magnetic deironing mechanism 7, thereby realizing the deironing operation of the nano-alumina product, and can reduce the iron content in the nano-alumina product to below 150ppm, which well meets the application requirements in the lithium battery field.

[0057] In some embodiments, as shown in Figures 1 and 3, the magnetic iron removal mechanism 7 includes at least two magnetic parts 71 connected in sequence. Specifically, the magnetic iron removal mechanism 7 forms a multi-stage magnetic structure by setting multiple magnetic parts 71. Preferably, the magnetic iron removal mechanism 7 includes two magnetic parts 71, and the storage bin 72 is set between the two magnetic parts 71, wherein the two magnetic parts 71 are respectively set before the nano-alumina finished product enters the storage bin 72 and before the nano-alumina finished product enters the packaging machine (packaging bag). The magnetic part 71 is a tubular structure, and the inner wall of the tubular structure is provided with a magnetic layer. The nano-alumina first flows through the tube structure of the first magnetic component 71. During the flow, the magnetic iron substances in the finished nano-alumina are adsorbed by the magnetic layer to be separated from the nano-alumina for the first time. Then, the nano-alumina after the first separation is sent to the storage bin 72 for buffering. After reaching a certain amount, it is sent to the tube structure of the second magnetic component 71. During the flow, the magnetic iron substances in the finished nano-alumina are again adsorbed by the magnetic layer to be separated from the nano-alumina for the second time. The two magnetic components 71 cooperate to perform two-stage magnetic iron substance separation on the nano-alumina, and then enter the packaging machine for product packaging. After the secondary magnetic adsorption impurities are removed, magnetic substances such as iron, zinc, and manganese in the finished product can be well removed, thereby improving the product quality of the nano-alumina. It should be noted that in other embodiments, the number of the magnetic components 71 is not limited to two. Other numbers such as three, four, five, etc. can be adapted to the setting. The specific setting can be made according to the actual iron removal requirements, and no special restrictions are made here. In this embodiment, the magnetic iron removal mechanism 7 is provided with two magnetic members 71 , which can simplify the structure and reduce the cost on the one hand, and can also achieve a good iron removal effect on the other hand.

[0058] In some embodiments, as shown in FIG3 , the magnetic layer includes a plurality of magnetic bodies 73 , each of which is arranged at intervals along the circumferential and axial directions of the tubular structure, and along the axial direction of the tubular structure, two adjacent magnetic bodies 73 are staggered. By arranging the magnetic bodies 73 on the inner wall of the tubular structure according to this specific structure, the magnetism can be evenly distributed at various positions on the inner wall of the tubular structure, so that the magnetic iron-like substances flowing through the magnetic attraction member 71 can be better adsorbed by the magnetic bodies 73 on the inner wall of the tubular structure, so as to better remove the magnetic iron-like substances in the finished product. In addition, the shape of the magnetic body 73 can be square or cylindrical, and can be an electromagnet or a permanent magnet. Furthermore, the magnetic body 73 can be detachably mounted on the inner wall of the tubular structure to facilitate disassembly and removal of foreign matter.

[0059] In some embodiments, as shown in Figure 2, the cyclone separation mechanism 4 includes two cyclone separators 40 connected in series, and the two cyclone separators 40 are respectively a first cyclone separator and a second cyclone separator; the first cyclone separator and the second cyclone separator both include a separator body 41, and the separator body 41 is provided with the second air inlet 42 and the second air outlet 43, and the second air inlet 42 is opened on the side wall of the separator body 41 along the transverse cross-section direction of the separator body 41, and the second air inlet 42 is located below the second air outlet 43.

[0060] Among them, the purpose of the first cyclone separator at the top is to introduce the sublimated aluminum chloride sublimation gas into the separator body 41 through the second air inlet 42 along the tangential direction. The solid particles entrained in the gas are separated from the solid due to centrifugal action and adhere to the inner wall of the separator body 41. When the amount is large, it will sink to the bottom of the separator body 41 due to gravity. The separated aluminum chloride gas will be introduced into the second cyclone separator of the next level through the second air outlet 43 for further cyclone separation. The two cyclone separators 40 cooperate to perform two-stage cyclone separation on the sublimated aluminum chloride sublimation gas. On the one hand, it can simplify the structure and reduce costs. On the other hand, it can also achieve a good effect of removing particles. Among them, a pressure measuring point and a temperature measuring point are set on the top of the second cyclone separator, and the pressure and temperature are directly connected to the production DCS control system in real time to monitor the stability of the system.

[0061] In some embodiments, as shown in FIG2 , the outer wall of the separator body 41 is provided with a first heating body 44, and the separator body 41 is provided with a first thermal insulation layer 45 on the outside of the first heating body 44. The first heating body 44 can be a ceramic electric heating plate. The function of the first heating body 44 is to heat and insulate the corresponding cyclone separator 40 to prevent the inner wall temperature of the cyclone separator 40 from being too low, causing aluminum chloride to condense and adsorb on its surface, thereby reducing the sublimation effect of aluminum chloride. The purpose of the first thermal insulation layer 45 is to prevent the heat of the equipment from being lost to the outside. A first slag discharge valve 46 is provided at the bottom of the separator body 41. The purpose of the first slag discharge valve 46 is to regularly discharge the solid particles separated from the separator body 41 to avoid affecting the heating and separation effect of the cyclone separator 40.

[0062] In some embodiments, as shown in FIG2 , a guide 24 is provided in the sublimator 2. The guide 24 is provided between the feed port 21 and the first air inlet 22. The guide 24 is used to guide the raw material powder entering from the feed port 21 to the first air inlet 22 to counteract the hot air entering from the first air inlet 22, thereby increasing the contact degree between the aluminum chloride powder and the hot air, effectively improving the heating efficiency and heating uniformity of the aluminum chloride powder, thereby allowing the aluminum chloride in the raw material to be quickly vaporized and effectively sublimated.

[0063] In some embodiments, as shown in FIG2 , the first gas outlet 23 is provided on one side of the sublimator 2, and a gas outlet baffle 25 is disposed within the sublimator 2. The gas outlet baffle 25 and the inner wall of the sublimator 2 enclose a guide cavity with one end open, and the first gas outlet 23 is in communication with the guide cavity. The gas outlet baffle 25 can divert the sublimated aluminum chloride gas through the baffle 25 before it flows out through the first gas outlet 23, thereby reducing the amount of unsublimated solid particles that flow out of the sublimator 2 with the aluminum chloride gas.

[0064] In some embodiments, as shown in FIG2 , the outer wall of the sublimator 2 is provided with a second heating body 26, and the sublimator 2 is provided with a second insulation layer 27 on the outer side of the second heating body 26. The second heating body 26 can be a ceramic electric heating plate, which is used to heat and insulate the sublimator 2 to prevent the temperature of the sublimator 2 from being too low and reducing the sublimation effect of aluminum chloride. The purpose of the second insulation layer 27 is to prevent the heat of the equipment from being lost to the outside. In addition, a second slag discharge valve 28 is provided at the bottom of the sublimator 2, wherein the purpose of the second slag discharge valve 28 is to regularly discharge the solid particles separated from the sublimator 2, thereby effectively avoiding affecting the heating and separation effect of the sublimator 2.

[0065] In some embodiments, the reactor 5 can specifically process aluminum chloride through conventional reactions to obtain nano-alumina. Specifically in this embodiment, the reactor 5 has hydrogen and air inlets, and nano-alumina native ions are generated by mixing and burning hydrogen, air and the purified aluminum chloride gas introduced from the cyclone separation mechanism 4. Subsequently, the nano-alumina native ions further collide and aggregate in the reactor 5 to obtain nano-alumina.

[0066] In some embodiments, the deacidification furnace 6 uses electric heating to provide heat to increase the temperature of the deacidification furnace 6, and removes the hydrogen chloride gas adsorbed on the surface of the nano-alumina product at high temperature, thereby increasing the pH value of the product.

[0067] In some embodiments, the conveying and processing mechanism 1, the sublimator 2, the gas heating mechanism 3, the cyclone separation mechanism 4, the reactor 5, the deacidification furnace 6 and the magnetic deironing mechanism 7 of the gas phase method nano-alumina preparation device 100 are all made of corrosion-resistant titanium.

[0068] The present invention also provides a method for preparing nano-alumina by a vapor phase method, the method comprising the following steps:

[0069] The aluminum chloride reaction raw material is crushed by the conveying and processing mechanism 1 and then conveyed to the sublimator 2. The gas heating mechanism 3 heats the air and then conveys it to the sublimator 2. The hot air heats the aluminum chloride powder to obtain aluminum chloride sublimation gas.

[0070] The aluminum chloride sublimed gas is passed into the cyclone separation mechanism 4 for cyclone separation to obtain aluminum chloride gas;

[0071] The obtained aluminum chloride gas is introduced into the reactor 5 to react and generate nano-aluminum oxide;

[0072] The nano-alumina is sent to the deacidification furnace 6 for deacidification;

[0073] The deacidified nano-alumina is fed into the magnetic de-ironing mechanism 7 for magnetic de-ironing to obtain nano-alumina.

[0074] The present invention is described below with reference to specific embodiments.

[0075] Example 1

[0076] The device 100 for preparing nano-alumina by vapor phase method used in this embodiment is as follows, as shown in FIG1 to FIG3 :

[0077] A vapor phase nano-alumina preparation device 100 comprises a conveying and processing mechanism 1, a sublimator 2, a gas heating mechanism 3, a cyclone separation mechanism 4, a reactor 5, a deacidification furnace 6 and a magnetic deironing mechanism 7 which are connected in sequence.

[0078] The conveying and processing mechanism 1 is a screw conveyor, and a material metering device is provided at the entrance of the screw conveyor.

[0079] The sublimator 2 has a feed port 21, a first air inlet 22 and a first air outlet 23. A guide member 24 is provided in the sublimator 2, and the guide member 24 is provided between the feed port 21 and the first air inlet 22. The first air outlet 23 is opened on one side of the sublimator 2, and an air outlet baffle 25 is provided in the sublimator 2. The air outlet baffle 25 and the inner wall of the sublimator 2 enclose a guide cavity with one end open, and the first air outlet 23 is connected to the guide cavity.

[0080] The cyclone separation mechanism 4 includes two cyclone separators 40 connected in series, namely a first cyclone separator and a second cyclone separator. The first cyclone separator and the second cyclone separator both include a separator body 41. The separator body 41 is provided with the second air inlet 42 and the second air outlet 43. The second air inlet 42 is opened on the side wall of the separator body 41 along the transverse cross-section direction of the separator body 41, and the second air inlet 42 is located below the second air outlet 43.

[0081] The magnetic iron removal mechanism 7 includes two magnetic components 71 connected in sequence, and a storage bin 72 is provided between two adjacent magnetic components 71 .

[0082] Example 2

[0083] This embodiment provides a method for purifying anhydrous aluminum chloride, and the apparatus used is as shown in Example 1.

[0084] The purification method of anhydrous aluminum chloride comprises the following steps:

[0085] First-class anhydrous aluminum chloride was used, and the temperature in sublimator 2 was controlled at 300°C, the hot air temperature was controlled at 320°C, the temperature in the first cyclone separator was controlled at 260°C, and the temperature in the second cyclone separator was controlled at 240°C. The aluminum chloride gas from the first cyclone separator and the second cyclone separator was collected and tested for iron content and water-insoluble matter according to the national standard "Industrial Anhydrous Aluminum Chloride" (GB / T 9592008). The results are shown in Table 1.

[0086] Table 1 Iron content and water-insoluble matter test results of aluminum chloride gas in Example 2

[0087] Example 3

[0088] This embodiment differs from embodiment 2 in that:

[0089] High-quality anhydrous aluminum chloride was used, and the temperature in sublimator 2 was controlled at 300°C, the hot air temperature was 300°C, the temperature of the first cyclone separator was 280°C, and the temperature of the second cyclone separator was 250°C. The aluminum chloride gas from the first cyclone separator and the second cyclone separator was collected and tested for its iron content and water-insoluble matter. The results are shown in Table 2.

[0090] Table 2 Iron content and water-insoluble matter test results of aluminum chloride gas of Example 3

[0091] Example 4

[0092] This embodiment differs from embodiment 2 in that:

[0093] The temperature in the sublimator 2 is controlled to be 350°C and the temperature of the hot air is controlled to be 350°C.

[0094] Aluminum chloride gas was obtained and its iron content and water-insoluble matter were tested. The results are shown in Table 3.

[0095] Table 3 Iron content and water-insoluble matter test results of aluminum chloride gas of Example 4

[0096] Example 5

[0097] This embodiment differs from embodiment 2 in that:

[0098] The temperature of the first cyclone separator was controlled at 300° C., and the temperature of the second cyclone separator was controlled at 300° C. The aluminum chloride gas from the first cyclone separator and the second cyclone separator was collected to obtain aluminum chloride gas. The iron content and water-insoluble matter in the aluminum chloride gas were tested. The results are shown in Table 4.

[0099] Table 4 Iron content and water-insoluble matter test results of aluminum chloride gas in Example 5

[0100] Comparative Example 1

[0101] This comparative example differs from Example 2 in that:

[0102] The temperature in the sublimator 2 is controlled to be 400°C and the temperature of the hot air is controlled to be 600°C.

[0103] Aluminum chloride gas was obtained and its iron content and water-insoluble matter were tested. The results are shown in Table 6.

[0104] Table 5 Iron content and water-insoluble test results of aluminum chloride gas in Comparative Example 1

[0105] Comparative Example 2

[0106] This comparative example differs from Example 2 in that:

[0107] The temperature of the first cyclone separator is 350°C, and the temperature of the second cyclone separator is 350°C.

[0108] Aluminum chloride gas was obtained and its iron content and water-insoluble matter were tested. The results are shown in Table 6.

[0109] Table 6 Iron content and water-insoluble test results of aluminum chloride gas in Comparative Example 2

[0110] From the results in Tables 1 to 6, it can be seen that the aluminum chloride obtained in Example 2 and Example 3 has the highest purity. The iron content in the obtained aluminum chloride products is reduced by 112.9 ppm and 103 ppm, respectively, and the iron content in the final products is reduced to 52.6 ppm and 31.3 ppm, respectively. The content of water-insoluble matter is reduced by 0.05% and 0.03%, respectively, and the content of water-insoluble matter in the final products is reduced to 0.03% and 0.01%, respectively.

[0111] In Example 4, compared with Example 2, the temperature of the sublimator 2 was increased to 350°C and the hot air temperature was increased to 350°C. It was found that the iron content of the raw material entering the first-stage cyclone separator increased, but after the second-stage cyclone separation, most of the iron and water-insoluble matter could be removed.

[0112] In Example 5, compared with Example 2, the temperature of the first cyclone separator and the second cyclone separator was increased to 300° C., and it was also found that the removal efficiency of iron and water-insoluble matter was reduced.

[0113] In Comparative Example 1, compared with Example 2, the temperature of the sublimator 2 was increased to 400°C and the hot air temperature was increased to 600°C. It was found that the removal efficiency of iron and water-insoluble matter was reduced, especially in the first-stage separation, the impurity removal efficiency was very low.

[0114] In Comparative Example 2, compared with Example 2, the temperature of the first cyclone separator was increased to 350° C., and the temperature of the second cyclone separator was increased to 350° C., and it was found that the removal efficiency of iron and water-insoluble matter was greatly reduced.

[0115] Example 6

[0116] This embodiment provides a method for preparing nano-alumina by vapor phase method, using the apparatus shown in Example 1, comprising the following steps:

[0117] Anhydrous aluminum chloride (FeCl3 content 143.8ppm) is added to a silo, quantitatively crushed and conveyed by a screw conveyor, and then enters the sublimator 2 along a guide 24. Under the action of hot air input from the first air inlet 22, the anhydrous aluminum chloride sublimes into aluminum chloride gas, which is then discharged from the first air outlet 23 and enters the primary and secondary cyclone separators in sequence. After cyclonic separation, the hydrolyzed aluminum chloride and some ungasified impurities settle to the bottom of the cyclone separators. The aluminum chloride gas is discharged from the top and enters the reactor 5. It mixes with the hydrogen and oxygen input to the reactor 5 and burns, undergoing a high-temperature hydrolysis and condensation reaction according to the conventional reaction, producing aluminum oxide and hydrogen chloride (4AlCl3 + 6H2 + 3O2 = 2Al2O3 + 12HCl). The resulting aluminum oxide is aggregated and then enters the deacidification furnace 6, where the hydrogen chloride adsorbed on the aluminum oxide surface is removed through conventional high-temperature treatment. The deacidified aluminum oxide is transported via a pipeline to the storage silo 72. Before entering the storage bin 72, the magnetic iron removal mechanism 7 performs a primary impurity removal to capture various magnetic substances. When the material in the storage bin 72 reaches a certain amount, the product is packaged. Before the material enters the packaging bag, it passes through the magnetic iron removal mechanism 7 for a secondary impurity removal, and then the finished product is packaged.

[0118] The temperature in the sublimator 2 is controlled at 300°C, the hot air temperature is controlled at 320°C, the temperature of the first-stage cyclone separator is controlled at 260°C, and the temperature of the second-stage cyclone separator is controlled at 240°C.

[0119] The iron content of the prepared nano-alumina product was determined according to GB / T24264-2020, the 325μm sieve residue was determined according to GB / T20020-2013, and the magnetic material was subjected to magnetic absorption and then ICP determination. The results are shown in Table 7:

[0120] Table 7 Iron content and magnetic material test results of nano-alumina finished products

[0121] Note: (1) The control example is the alumina preparation process, in which the aluminum chloride raw material is vaporized and directly enters the reactor for reaction, and the finished product does not undergo the magnetic adsorption impurity removal process.

[0122] (2) The negative value of Ni content is because the content is lower than the detection limit of the instrument.

[0123] As can be seen from the above, Example 6, before the aluminum chloride raw material is put into the reactor 5 for reaction, the aluminum chloride raw material is first transported to the sublimator 2 and heated until the aluminum chloride in the raw material is separated from the ferric chloride gas and solid under the action of hot air, wherein the aluminum chloride is gasified and sublimated, and then the solid particles are captured by the cyclone separation action of the cyclone separation mechanism 4 by centrifugal motion in the cyclone, while the sublimated aluminum chloride gas remains in a gaseous state and is separated from the solid particles, thereby achieving the iron removal and purification operation of the raw aluminum chloride. The finished nano-alumina product after the reaction is further processed by the magnetic iron removal mechanism 7. The two-stage magnetic structure treatment can capture the magnetic iron substances in the nano-alumina product by adsorption, and can reduce the iron content in the nano-alumina product to 93.6ppm, which is much lower than the iron content of the finished product in the control example of 428.7ppm.

[0124] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for purifying anhydrous aluminum chloride, characterized in that: The purification method comprises the following steps: The anhydrous aluminum chloride raw material is crushed into powder, and the crushed powder and hot air are introduced into a sublimator, wherein the hot air heats the powder to obtain aluminum chloride sublimation gas, the temperature in the sublimator is 250° C. to 350° C., and the temperature of the hot air is 250° C. to 500° C.; The aluminum chloride sublimation gas is introduced into a cyclone separation mechanism for cyclone separation to obtain aluminum chloride gas; the temperature in the cyclone separation mechanism is 200° C. to 300° C.

2. The method for purifying anhydrous aluminum chloride according to claim 1, characterized in that: The temperature of the sublimator is 280°C to 300°C, and the temperature of the hot air is 280°C to 350°C.

3. The method for purifying anhydrous aluminum chloride as claimed in claim 2, characterized in that: The temperature of the sublimator is 290°C to 300°C, and the temperature of the hot air is 300°C to 320°C.

4. The method for purifying anhydrous aluminum chloride according to any one of claims 1 to 3, characterized in that: The cyclone separation mechanism comprises a first cyclone separator and a second cyclone separator connected in series, the aluminum chloride sublimation gas is introduced into the first cyclone separator for cyclone separation at 200°C to 300°C, and the obtained gas phase product is introduced into the second cyclone separator for cyclone separation at 200°C to 280°C.

5. The method for purifying anhydrous aluminum chloride according to claim 4, characterized in that: The temperature in the first cyclone separator is 250°C to 300°C, and the temperature in the second cyclone separator is 220°C to 260°C.

6. The method for purifying anhydrous aluminum chloride according to claim 5, characterized in that: The temperature in the first cyclone separator is 260°C to 280°C, and the temperature in the second cyclone separator is 240°C to 250°C.

7. A gas phase method nano-alumina preparation device, characterized in that: The gas phase method nano-alumina preparation device comprises a conveying and processing mechanism, a sublimator, a gas heating mechanism, a cyclone separation mechanism, a reactor, a deacidification furnace and a magnetic de-iron removal mechanism; The conveying and processing mechanism is used to crush and convey the aluminum chloride raw material; The sublimator has a feed port, a first air inlet and a first air outlet; the conveying and processing mechanism is connected to the feed port of the sublimator and is used to feed the crushed aluminum chloride powder into the sublimator; the gas heating mechanism is connected to the first air inlet and is used to feed the heated gas into the sublimator to heat the aluminum chloride powder; The cyclone separation mechanism has a second air inlet and a second air outlet, the second air inlet is connected to the first air outlet, and the second air outlet is connected to the reactor, the deacidification furnace and the magnetic deironing mechanism in sequence. Connectivity.

8. The device for preparing nano-alumina by gas phase method according to claim 7, characterized in that: The magnetic iron removal mechanism includes at least two magnetic parts connected in sequence, the deacidified nano-alumina enters the magnetic parts in sequence, and a storage bin is arranged between two adjacent magnetic parts. The magnetic part is a tubular structure, and the inner wall of the tubular structure is provided with a magnetic layer.

9. The device for preparing nano-alumina by gas phase method according to claim 8, characterized in that: The magnetic attraction layer includes a plurality of magnetic bodies, each of which is arranged at intervals along the circumferential direction and the axial direction of the tube structure, and along the axial direction of the tube structure, two adjacent magnetic bodies are staggered.

10. The device for preparing nano-alumina by gas phase method according to claim 8, characterized in that: The magnetic iron removal mechanism comprises two magnetic parts, and the two magnetic parts cooperate to form a two-stage magnetic structure.

11. The device for preparing nano-alumina by vapor phase method according to any one of claims 7 to 10, characterized in that: The cyclone separation mechanism comprises two cyclone separators connected in series, the two cyclone separators being respectively a first cyclone separator and a second cyclone separator; The first cyclone separator and the second cyclone separator both include a separator body, and the separator body is provided with the second air inlet and the second air outlet, the second air inlet is opened on the side wall of the separator body along the transverse section direction of the separator body, and the second air inlet is located below the second air outlet.

12. The device for preparing nano-alumina by gas phase method according to claim 11, characterized in that: A first heating body is arranged on the outer wall of the separator body, and a first heat-insulating layer is arranged on the outer side of the first heating body of the separator body.

13. The device for preparing nano-alumina by vapor phase method according to any one of claims 7 to 10, characterized in that: A guide is provided in the sublimator, and the guide is provided between the feed port and the first air inlet, and the guide is used to guide the raw material powder entering from the feed port to the first air inlet to collide with the hot air entering from the first air inlet.

14. The device for preparing nano-alumina by vapor phase method according to any one of claims 7 to 10, characterized in that: The outer wall of the sublimator is provided with a second heating body, and the sublimator is provided with a second heat-insulating layer on the outer side of the second heating body.

15. The device for preparing nano-alumina by vapor phase method according to any one of claims 7 to 10, characterized in that: The first gas outlet is opened at one side of the sublimator, and a gas outlet baffle is arranged in the sublimator. The gas outlet baffle and the inner wall of the sublimator are enclosed to form a guide cavity with one end open, and the first gas outlet is connected to the guide cavity.

16. A method for preparing nano-alumina by gas phase method, characterized in that: The preparation method comprises the following steps: The aluminum chloride reaction raw material is crushed by the conveying and processing mechanism and then conveyed to the sublimator, the gas heating mechanism heats the air and then conveys it to the sublimator, and the hot air heats the aluminum chloride powder to obtain aluminum chloride sublimation gas; The aluminum chloride sublimation gas is introduced into a cyclone separation mechanism for cyclone separation to obtain aluminum chloride gas; The obtained aluminum chloride gas is introduced into a reactor to react and generate nano aluminum oxide; The nano-alumina is sent into a deacidification furnace for deacidification; The deacidified nano-alumina is sent to a magnetic de-ironing mechanism for magnetic de-ironing to obtain nano-alumina.

Images