A method and apparatus for producing high purity aluminum

Abstract

The application belongs to the technical field of high-purity aluminum preparation, and particularly relates to a method and device for preparing high-purity aluminum. The method is that hydrogen, dilution gas and metal aluminum precursor are mixed, and then subjected to primary reduction under the action of a Co-Ni catalyst, and then the product obtained by the primary reduction is subjected to secondary reduction, and finally the product is subjected to high-temperature blowing and replacement treatment to obtain high-purity aluminum. The device comprises a mixer, a reduction furnace one, a reduction furnace two, a collector and a vacuum pump which are sequentially communicated. The application effectively improves the purity of high-purity aluminum, and the purity of the product aluminum can reach 99.999%.

Description

Technical Field

[0001] This application belongs to the technical field of high-purity aluminum preparation, specifically relating to a method and apparatus for preparing high-purity aluminum. Background Technology

[0002] Aluminum is an important industrial material, widely used in construction, transportation, electronics, and other fields. Traditional aluminum production methods, such as electrolysis, while low-cost, suffer from high energy consumption and low production efficiency. In recent years, the reduction method for aluminum production has gained increasing attention because it can produce aluminum by reducing alumina (Al₂O₃), offering higher production efficiency and environmental friendliness. However, existing reduction methods face certain technical bottlenecks in the preparation of high-purity aluminum, mainly in terms of raw material purity, reaction temperature control, and equipment efficiency.

[0003] Currently, the preparation of industrial aluminum is relatively mature. The main production methods for aluminum include reduction, hydroxyl thermal decomposition, and aluminum chloride vapor process, with reduction being the most commonly used method in industrial production. The industrial production process for high-purity aluminum uses ammonium aluminate as a raw material, which is calcined to produce light yellow or pale green high-purity alumina. This alumina is then reduced by high-temperature hydrogen to produce aluminum powder. Finally, the powder is sieved, mixed, and then sintered and pressed into aluminum plates and other products. However, the purity of aluminum powder prepared by traditional processes is only 3N to 4N5, therefore the resulting aluminum plates and other products cannot reach a purity of 5N.

[0004] Chinese Patent Publication No. CN120666404A discloses a method for preparing high-purity aluminum powder, specifically a method for preparing nano-aluminum powder by electrolysis based on ionic liquid. The method involves mixing ionic liquid, additives, and AlCl3 to obtain an electrolyte, using aluminum as the cathode and an inert electrode as the anode, to perform an electrolytic reaction and prepare nano-aluminum powder. The additive is specifically a halide salt. This application, by adding a halide salt as an additive, can partially replace the ionic liquid, reducing the preparation cost of nano-aluminum powder. Furthermore, the halide salt can prevent aluminum powder from adhering to the cathode, resulting in smaller and more uniform nano-aluminum powder particles with a narrower particle size distribution, thus improving related performance in applications. The disclosed preparation method also has the advantages of low electrolysis temperature and low energy consumption, and the electrolysis process can be protected by a protective atmosphere, greatly improving the safety of aluminum powder preparation. However, this method has extremely high energy consumption, with a huge power consumption per ton, and generates waste gas during production, putting pressure on the environment. In addition, the operation is complex, requiring manual cleaning of anode mud, posing safety hazards. In summary, the currently known methods for preparing high-purity aluminum are mainly characterized by relatively complex processes and the purity being limited by the purity of the metal powder, which restricts the industrialization of high-purity aluminum. Summary of the Invention

[0005] Existing methods for preparing high-purity aluminum are characterized by relatively complex processes and purity limitations imposed by the purity of the metal powder, hindering the industrialization of high-purity aluminum. This application proposes a method and apparatus for preparing high-purity aluminum. The technical solution of this application is as follows: On the one hand, this application provides a method for preparing high-purity aluminum, the method being: mixing hydrogen, dilution gas and metallic aluminum precursor and then performing a first-stage reduction under the action of a Co-Ni catalyst, then performing a second-stage reduction on the product obtained from the first-stage reduction, and finally performing high-temperature purging and displacement treatment on the product to obtain high-purity aluminum; The temperature for the first-stage reduction is 1300-1500℃, and the temperature for the second-stage reduction is 900-1100℃.

[0006] Preferably, the purity of the hydrogen gas is 5N.

[0007] Preferably, the diluting gas is any one or more of nitrogen, helium, and argon.

[0008] Preferably, the aluminum precursor is either aluminum trichloride or aluminum trifluoride.

[0009] Preferably, the flow rate of hydrogen is 0.2-5 L / min; the flow rate of aluminum precursor is 0.05-0.5 L / min; and the flow rate of dilution gas is 0.5-5 L / min.

[0010] Preferably, the hydrogen flow rate is 0.3-3 L / min; the aluminum precursor flow rate is 0.1-0.2 L / min; and the dilution gas flow rate is 0.5-2.5 L / min.

[0011] Preferably, the first-stage reduction pressure is -0.1~0.1MPa and the second-stage reduction pressure is -0.07~0.03MPa.

[0012] Preferably, the high-temperature purging uses hydrogen purging at 500-850℃, a pressure of -0.1~0.1MPa, and a hydrogen flow rate of 0.3-3L / min; the replacement treatment uses dilution gas at a temperature of 200-350℃, a pressure of -0.1~0.1MPa, and a dilution gas flow rate of 0.5-5L / min.

[0013] Preferably, the high-temperature purging is performed using hydrogen purging at 600-750℃ and a pressure of -0.07~0.03MPa, with a hydrogen flow rate of 0.3-2.5L / min; the replacement treatment uses dilution gas at a temperature of 300-350℃ and a pressure of -0.07~0.03MPa, with a dilution gas flow rate of 0.5-2.5L / min.

[0014] On the other hand, this application provides an apparatus for preparing high-purity aluminum, characterized in that it includes a mixer, a first reduction furnace, a second reduction furnace, a collector, and a vacuum pump connected in sequence. The mixer is provided with an air inlet pipe; the air inlet pipe includes a hydrogen pipe, a dilution gas pipe, and a metallic aluminum precursor pipe; The mixer is connected to the reduction furnace via a mixing inlet pipe; The first reduction furnace is connected to the second reduction furnace via a first connecting pipe; The reduction furnace 2 is also equipped with a hydrogen supply pipeline; The second reduction furnace is connected to the collector via a second connecting pipe; The collector is also equipped with a vacuum pipe and an emptying pipe, with the outlet end of the vacuum pipe connected to a vacuum pump. Both reduction furnace one and reduction furnace two are made of one of nickel, Monel alloy, or stainless steel; both reduction furnace one and reduction furnace two are vertical tube deposition furnaces. The collectors are all made of one of the following materials: stainless steel, carbon steel, copper, nickel, and Monel alloy; The first connecting pipe, the second connecting pipe, the vacuum pipe, the mixing intake pipe, and the hydrogen replenishment pipe are all made of either stainless steel or carbon steel.

[0015] The beneficial effects of this application are as follows: This application effectively improves the purity of high-purity aluminum, and the purity of the aluminum in the product can reach 99.999%.

[0016] This application effectively controls the reaction rate, avoiding uneven deposition of high-purity aluminum due to temperature inconsistencies, and simplifies the production process of high-purity aluminum. Furthermore, the use of a two-stage reduction furnace in series for deposition improves the reaction yield of high-purity aluminum.

[0017] This application first uses a vacuum pump to pre-evacuate all components of the device; then, dilution gas is used to purge and replace residual moisture and air in the system; next, hydrogen is introduced into the reduction furnace for heating; after the temperature reaches the set temperature, the hydrogen, dilution gas, and aluminum precursor are mixed and then introduced into a secondary reduction furnace for reaction, with the temperature and pressure of the reduction furnace controlled; the reacted gas enters a collector, where the aluminum precursor and reaction products are collected by cryogenic liquefaction; unliquefied gaseous impurities enter the tail gas treatment system through a discharge pipeline, and are vented after harmless treatment. The aluminum precursor is stored in the cryogenic collector.

[0018] This application provides a high-purity aluminum preparation apparatus. The reduction furnace is designed as a vertical tube furnace with a mixed gas inlet, which reduces the mixing process of hydrogen, dilution gas and aluminum precursor in the reduction furnace, making the reaction to generate high-purity aluminum in the deposition furnace safer and more stable. At the same time, the two-stage reduction furnaces connected in series further improve the yield of high-purity aluminum. Attached Figure Description

[0019] Figure 1 This is a diagram of the apparatus used to prepare high-purity aluminum according to this application.

[0020] Attached image labels: 1. Aluminum precursor pipeline; 2. Dilute gas pipeline; 3. Hydrogen pipeline; 4. Mixer; 5. Reduction furnace one; 6. First connecting pipeline; 7. Reduction furnace two; 8. Second connecting pipeline; 9. Collector; 10. Vacuum manifold; 11. Vacuum pump; 12. Exhaust pipeline; 13. Mixing gas inlet pipeline; 14. Hydrogen replenishment pipeline. Detailed Implementation

[0021] To further illustrate the technical means and effects adopted by this application in order to achieve the intended purpose of the invention, the following detailed description of the specific implementation methods, structures, features and effects of this application is provided in conjunction with the accompanying drawings and preferred embodiments.

[0022] Device Examples An apparatus for preparing high-purity aluminum, such as Figure 1 As shown, the device includes a mixer 4, a reduction furnace 5, a reduction furnace 7, a collector 9, and a vacuum pump 11 connected in sequence. The mixer 4 is equipped with an air intake pipe, which includes a hydrogen pipe 3, a dilution gas pipe 2, and a metallic aluminum precursor pipe 1. The reduction furnace 1 5 is equipped with a mixing gas inlet pipe 13; the reduction furnace 2 7 is equipped with a connecting pipe 8 and a hydrogen replenishment pipe 14; the collector 9 is equipped with a vacuum pipe 10, and a vacuum pump 11 is installed at the outlet end of the vacuum pipe 10. Mixer 4 is connected to reduction furnace 1 5 via mixing air inlet pipe 13; reduction furnace 1 5 is connected to reduction furnace 2 7 via first connecting pipe 6; reduction furnace 2 7 and collector 9 are connected via second connecting pipe 8.

[0023] The materials of reduction furnace 1 (5) and reduction furnace 2 (7) are both nickel, Monel alloy, and stainless steel; both reduction furnace 1 (5) and reduction furnace 2 (7) are vertical tube deposition furnaces.

[0024] Collector 9 is made of one of the following materials: stainless steel, carbon steel, copper, nickel, or Monel alloy; The first connecting pipe 6, the second connecting pipe 8, the vacuum pipe 10, the mixing intake pipe 13, and the hydrogen replenishment pipe 14 are all made of either stainless steel or carbon steel.

[0025] Implementation principle of the device: During use, the vacuum pump 11 first performs vacuum pretreatment on each component of the device, and then the diluent gas is used to purge and replace the residual air and moisture in the system to provide a clean environment for the reaction.

[0026] Subsequently, hydrogen and dilution gas are introduced into mixer 4 through hydrogen pipeline 3 and dilution gas pipeline 2, respectively. After being mixed evenly, they flow into reduction furnace 5 and reduction furnace 7 for heating. After the temperature stabilizes, aluminum precursor is introduced into mixer 4 through aluminum precursor pipeline 1. After being fully mixed with hydrogen and dilution gas, it enters reduction furnace 5 and reduction furnace 7 through mixing inlet pipeline 13, first connecting pipeline 6 and second connecting pipeline 8 in sequence. Under certain temperature and pressure conditions, with the catalytic effect of the metal catalyst Co-Ni (the metal catalyst Co-Ni is Co-Ni alloy nanoparticles supported on a high-purity graphite carrier, with a loading of 15% and a Co:Ni molar ratio of 1:1, which is reduced in H2 gas stream at 500℃ for 2 hours before use), hydrogen and aluminum precursor undergo a reduction reaction to prepare high-purity aluminum. At the same time, hydrogen can be supplemented through hydrogen replenishment pipeline 14 on reduction furnace 7 to ensure that the reaction proceeds fully.

[0027] The gas after the reaction enters collector 9, where unreacted aluminum precursor and reaction products are collected through low-temperature liquefaction. Unliquefied gaseous impurities are sent to the tail gas treatment system through exhaust pipe 12, where they are vented after being rendered harmless. The aluminum precursor stored in collector 9 can be recycled. The reaction products are purged with hydrogen at high temperature and dehydrated to finally obtain high-purity aluminum. This application employs a mixer combined with a two-stage series reduction furnace structure, which first achieves uniform mixing of the reactants, and then ensures sufficient contact and reaction between hydrogen and the aluminum precursor through a two-stage reduction reaction, effectively improving the reaction conversion rate and ultimately obtaining high-purity aluminum. Furthermore, the second reduction furnace is equipped with an independent hydrogen supply pipeline, which can replenish the hydrogen consumed during the reaction to ensure the full progress of the reduction reaction, and can also be used to purge and dehydrate the reaction products at high temperature, further improving product purity and producing high-purity aluminum. By using a vacuum pump in conjunction with dilution gas purging, residual air and moisture in the system can be effectively removed, preventing impurities from entering the reaction system. This provides a stable and clean reaction environment for the preparation of high-purity aluminum, ensuring the stability of product purity.

[0028] Examples 1-3 are based on the devices provided in the device embodiments, and their specific operations are as follows: Example 1

[0029] This embodiment provides a method for preparing high-purity aluminum. Details are as follows: Hydrogen and nitrogen of 5N purity are introduced into the mixer of the device at a set flow rate and thoroughly mixed. The flow rate of hydrogen is controlled within the range of 2L / min, and the flow rate of nitrogen is controlled within the range of 2L / min. The mixed gas is first introduced into reduction furnace one, which is filled with Co-Ni catalyst. Simultaneously, reduction furnace one and reduction furnace two are heated. After the temperature of reduction furnace one stabilizes at 1350℃ and the temperature of reduction furnace two stabilizes at 1000℃, aluminum trichloride of 4N purity is introduced into the mixer at a flow rate of 0.15L / min. After being thoroughly mixed with hydrogen and nitrogen, it is introduced into reduction furnace one and reduction furnace two in sequence for reduction reaction. During the reaction, the pressure of reduction furnace one is controlled at -0.01MPa and the pressure of reduction furnace two is controlled at -0.07MPa. After two-stage reduction reaction, crude product is obtained.

[0030] After the reduction reaction is complete, the product enters the post-processing stage. First, the crude product obtained from the reduction is subjected to high-temperature purging. 5N hydrogen gas is used as the purging gas, with the purging temperature controlled within 650℃, the purging pressure within 0.02MPa, and the hydrogen purging flow rate within 2.0L / min. This high-temperature purging removes residual volatile impurities and moisture from the crude product. After high-temperature purging, the product undergoes a displacement treatment using nitrogen gas. The displacement temperature is controlled within 320℃, the displacement pressure within 0.02MPa, and the nitrogen flow rate within 2.3L / min, yielding the target high-purity aluminum product. Testing showed that the high-purity aluminum yield was 90.3%, and the purity was 99.9995%. Example 2

[0031] Hydrogen and helium of 5N purity are introduced into the mixer of the device at a set flow rate and thoroughly mixed. The flow rate of hydrogen is controlled within the range of 0.2 L / min, and the flow rate of helium is controlled within the range of 5 L / min. The mixed gas is first introduced into reduction furnace one, which is filled with Co-Ni catalyst. Simultaneously, reduction furnace one and reduction furnace two are heated. After the temperature of reduction furnace one stabilizes at 1300℃ and the temperature of reduction furnace two stabilizes at 1100℃, aluminum trifluoride of 4N purity is introduced into the mixer at a flow rate of 0.05 L / min. After being thoroughly mixed with hydrogen and helium, it is sequentially introduced into reduction furnace one and reduction furnace two for reduction reaction. During the reaction, the pressure of reduction furnace one is controlled at 0.1 MPa, and the pressure of reduction furnace two is controlled at -0.07 MPa. After two-stage reduction reaction, crude product is obtained.

[0032] After the reduction reaction is complete, the product enters the post-processing stage. First, the crude product obtained from the reduction is subjected to high-temperature purging. 5N hydrogen gas is used as the purging gas, with the purging temperature controlled within 850℃, the purging pressure within -0.1MPa, and the hydrogen flow rate within 0.3L / min. This high-temperature purging removes residual volatile impurities and moisture from the crude product. After high-temperature purging, the product undergoes a displacement treatment using helium gas. The displacement temperature is controlled within 350℃, the displacement pressure within 0.1MPa, and the helium flow rate within 0.5L / min, yielding the target high-purity aluminum product. Testing showed that the yield of high-purity aluminum was 89.4%, and the purity was 99.9991%. Example 3

[0033] Hydrogen and argon of 5N purity were introduced into the mixer of the device at a set flow rate and thoroughly mixed. The flow rate of hydrogen was controlled within the range of 5 L / min, and the flow rate of argon was controlled within the range of 0.5 L / min. The mixed gas was first introduced into reduction furnace one, which was filled with Co-Ni catalyst. Simultaneously, reduction furnace one and reduction furnace two were heated. After the temperature of reduction furnace one stabilized at 1500℃ and the temperature of reduction furnace two stabilized at 900℃, aluminum trifluoride of 4N purity was introduced into the mixer at a flow rate of 0.5 L / min. After being thoroughly mixed with hydrogen and argon, it was introduced into reduction furnace one and reduction furnace two in sequence for reduction reaction. During the reaction, the pressure of reduction furnace one was controlled at -0.1 MPa and the pressure of reduction furnace two was controlled at -0.07 MPa. After two-stage reduction reaction, crude product was obtained.

[0034] After the reduction reaction is complete, the product enters the post-processing stage. First, the crude product obtained from the reduction is subjected to high-temperature purging. 5N hydrogen gas is used as the purging gas, with the purging temperature controlled within 500℃, the purging pressure within 0.1MPa, and the hydrogen flow rate within 3L / min. This high-temperature purging removes residual volatile impurities and moisture from the crude product. After high-temperature purging, the product undergoes a displacement treatment using argon gas. The displacement temperature is controlled within 200℃, the displacement pressure within -0.1MPa, and the argon flow rate within 5L / min, yielding the target high-purity aluminum product. Testing showed that the yield of high-purity aluminum was 87.9%, and the purity was 99.9993%.

[0035] Comparative Example 1 The difference between this comparative example and Example 1 is that only reduction furnace one was used, while all other conditions were the same. The purity was only 99.994%, and the yield was 83.1%.

[0036] Comparative Example 2 The difference between this comparative example and Example 1 is that the reduction furnace used was catalyst-free, while all other conditions remained the same. The purity was only 99.8%, and the yield was 79.5%.

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is that the temperature of both reduction furnace one and reduction furnace two was 1350°C. The purity was only 99.98%, and the yield was 80.6%.

[0038] The above description is merely a preferred embodiment of this application and is not intended to limit this application in any way. Although this application has been disclosed above with reference to preferred embodiments, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A method for preparing high-purity aluminum, characterized in that, The method is as follows: hydrogen, dilution gas and aluminum precursor are mixed and then subjected to primary reduction under the action of Co-Ni catalyst. The product obtained from the primary reduction is then subjected to secondary reduction. Finally, the product is subjected to high-temperature purging and displacement treatment to obtain high-purity aluminum. The temperature for the first-stage reduction is 1300-1500℃, and the temperature for the second-stage reduction is 900-1100℃.

2. The method for preparing high-purity aluminum according to claim 1, characterized in that, The purity of the hydrogen gas is 5N.

3. The method for preparing high-purity aluminum according to claim 1, characterized in that, The diluting gas is any one or more of nitrogen, helium, and argon.

4. The method for preparing high-purity aluminum according to claim 1, characterized in that, The aluminum precursor is either aluminum trichloride or aluminum trifluoride.

5. The method for preparing high-purity aluminum according to claim 1, characterized in that, The flow rate of hydrogen is 0.2-5 L / min; the flow rate of aluminum precursor is 0.05-0.5 L / min; and the flow rate of dilution gas is 0.5-5 L / min.

6. The method for preparing high-purity aluminum according to claim 5, characterized in that, The hydrogen flow rate is 0.3-3 L / min; the aluminum precursor flow rate is 0.1-0.2 L / min; and the dilution gas flow rate is 0.5-2.5 L / min.

7. The method for preparing high-purity aluminum according to claim 1, characterized in that, The first-stage reduction pressure is -0.1~0.1MPa, and the second-stage reduction pressure is -0.07~0.03MPa.

8. The method for preparing high-purity aluminum according to claim 1, characterized in that, High-temperature purging uses hydrogen purging at 500-850℃ and a pressure of -0.1~0.1MPa, with a hydrogen flow rate of 0.3-3L / min; displacement treatment uses dilution gas at a temperature of 200-350℃ and a pressure of -0.1~0.1MPa, with a dilution gas flow rate of 0.5-5L / min.

9. A method for preparing high-purity aluminum according to claim 8, characterized in that, High-temperature purging uses hydrogen purging at 600-750℃ and a pressure of -0.07~0.03MPa, with a hydrogen flow rate of 0.3-2.5L / min; displacement treatment uses dilution gas at a temperature of 300-350℃ and a pressure of -0.07~0.03MPa, with a dilution gas flow rate of 0.5-2.5L / min.

10. An apparatus for preparing high-purity aluminum, based on the method for preparing high-purity aluminum according to any one of claims 1 to 9, characterized in that, It includes a mixer (4), a reduction furnace one (5), a reduction furnace two (7), a collector (9), and a vacuum pump (11) connected in sequence. The mixer (4) is provided with an air inlet pipe; the air inlet pipe includes a hydrogen pipe (1), a dilution gas pipe (2), and a metallic aluminum precursor pipe (3). The mixer (4) is connected to the reduction furnace (5) through the mixing inlet pipe (13); The first reduction furnace (5) is connected to the second reduction furnace (7) through the first connecting pipe (6); The reduction furnace 2 (7) is also equipped with a hydrogen supply pipe (14); The reduction furnace 2 (7) is connected to the collector (9) through a second connecting pipe (8); The collector (9) is also provided with a vacuum pipe (10) and an empty pipe (12), and the outlet end of the vacuum pipe (10) is connected to a vacuum pump (11). The materials of the first reduction furnace (5) and the second reduction furnace (7) are all nickel, Monel alloy, or stainless steel; the first reduction furnace (5) and the second reduction furnace (7) are both vertical tube deposition furnaces; the materials of the collector (9) are all stainless steel, carbon steel, copper, nickel, or Monel alloy. The first connecting pipe (6), the second connecting pipe (8), the vacuum pipe (10), the mixing gas inlet pipe (13), and the hydrogen replenishment pipe (14) are all made of either stainless steel or carbon steel.

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