Method for preparing micro-nano magnesium hydride powder

Abstract

The invention discloses a method for preparing micro-nano magnesium hydride powder, which comprises the following steps: in a vacuum environment I, heating a magnesium raw material to form magnesium steam, and simultaneously introducing trace carrier gas I; in the vacuum environment II, magnesium steam is conveyed through the trace carrier gas I to be mixed with the carrier gas II to form mixed gas, meanwhile, the mixed gas is made to rapidly flow through the injection evacuator, the magnesium steam is cooled and hydrogenated, and the micro-nano magnesium hydride powder is formed. Compared with the prior art, the gasification efficiency of magnesium is higher, the magnesium is taken away by airflow, residues in an evaporation chamber are less, the utilization rate of the magnesium is high, produced magnesium powder is directly brought into the next link through hydrogen carrier gas, the processes of passivation, bin opening, powder taking and the like are omitted, magnesium powder conveying is more efficient and safer, and the production cost is reduced. Through the pre-hydrogenation of the magnesium powder and the shearing action of the carrier gas of the high-speed hydrogen, the generated magnesium powder particles are smaller, the magnesium hydride powder particles generated after hydrogenation are smaller, the activity is better, and the technical process is easier to realize large-scale amplification and automatic control.

Description

Technical Field

[0001] The present application relates to a method for preparing micro-nano magnesium hydride powder, belonging to the field of chemical technology. Background Art

[0002] Magnesium hydride (MgH2), also known as magnesium dihydride, is an inorganic compound with the appearance of off-white crystalline powder and a density of 1.45g / cm 3 Due to its unique physical and chemical properties, it has a wide range of applications in many fields. It has a high volumetric hydrogen storage density (110g / L) and mass hydrogen storage density (7.6%), releases high-purity hydrogen, and is highly stable at room temperature and pressure. It is an important solid hydrogen storage material that can be used for the storage and transportation of hydrogen energy.

[0003] Common preparation methods include thermal decomposition of magnesium alkyls to produce magnesium hydride, catalytic magnesium powder under normal pressure, and magnesium powder heated and pressurized to produce magnesium hydride. Existing preparation technologies suffer from lengthy processes, prolonged hydrogenation times, uneven particle size, and large magnesium hydride size, making them unsuitable for large-scale production and expensive, limiting their widespread use as a hydrogen storage material.

[0004] Magnesium hydride is used as a hydrogen storage material mainly through pyrolysis and hydrolysis. The particle size of magnesium hydride significantly affects its activity: the smaller the particle size, the higher its activity. Conventional methods of preparing magnesium hydride by direct hydrogenation of magnesium require first converting a magnesium ingot into magnesium powder and then hydrogenating it. The preparation process of the magnesium powder limits the particle size of the magnesium powder, which in turn indirectly limits the particle size of the magnesium hydride powder. Magnesium hydride with smaller particle sizes is generally around ten or even dozens of microns. Moreover, many magnesium powder preparation and hydrogenation processes are not performed continuously, resulting in surface oxidation of the magnesium powder, further increasing the difficulty of hydrogenation. If nanoscale magnesium hydride powder is to be prepared, it is usually necessary to further refine the prepared magnesium hydride powder using ball milling. In the prior art, the patent with publication number CN107585742A discloses a magnesium hydride preparation device that combines magnesium powder preparation and hydrogenation reaction into one device, and the magnesium hydride preparation method using the magnesium hydride preparation device has simple steps, and the particle size of the prepared magnesium hydride particles can be controlled within the range of 1-60 μm by controlling conditions such as temperature and pressure. The invention uses magnesium evaporation and condensation to prepare magnesium powder, and then hydrogenates to prepare magnesium hydride powder. Although the size of the prepared magnesium powder is relatively uniform, the prepared magnesium powder is directly hydrogenated, and the hydrogenation process will not be affected by the production of magnesium oxide on the surface of the magnesium powder. However, the magnesium vapor is transported by the pressure difference of the magnesium vapor, which is slow and inefficient, and will affect the evaporation rate of magnesium, and has high energy consumption. It is also difficult to transport magnesium powder by cooling water. The inter-row wall cooling magnesium vapor heat exchange efficiency is low, the produced magnesium powder particle size is large, the efficiency of collecting magnesium powder by electric powder brush is low, and due to the large magnesium powder particle size, the subsequent hydrogenation time is long; the patent with publication number CN101117211A discloses a method of preparing nano-scale magnesium powder by electric arc heating, and then hydrogenating to obtain MgH2 particle products with a particle size of 50-600nm, but this invention technology has certain problems. First, the magnesium powder is statically heated in a closed space, and the gasification efficiency is not high. Second, the generated magnesium powder cannot automatically enter the hydrogenation link and needs to be passivated and then manually removed, which poses certain safety risks. After passivation, magnesium oxide will be produced on the surface of the magnesium powder, and hydrogenation will be more difficult. Finally, this process is difficult to achieve large-scale, continuous, and automated operation. In summary, the existing magnesium hydride preparation process has the following problems: 1) The magnesium vaporization process is generally static heating and vaporization under low pressure or vacuum, relying on the pressure difference of the magnesium vapor pressure for diffusion, which is inefficient; 2) The magnesium vapor is cooled using a cold wall type of partition heat exchange, which has low heat exchange efficiency; 3) The generated magnesium powder cannot be efficiently and automatically transported continuously; 4) The generated magnesium powder has a large particle size and few control methods.

[0005] In summary, there is an urgent need for a micro-nanoscale magnesium hydride preparation process that can efficiently gasify magnesium blocks, efficiently cool magnesium vapor to make powder, and automatically transport magnesium powder, and is easy to scale up, continuously, and automatically operate. Summary of the Invention

[0006] To address the problems of existing production technologies, namely, the inability to achieve efficient gasification of magnesium, efficient cooling of magnesium vapor, micro-nano control of magnesium powder generation, automatic conveying and separation of magnesium powder, and efficient hydrogenation of magnesium powder to produce micro-nano magnesium hydride powder, a method for preparing micro-nano magnesium hydride powder is provided according to one aspect of the present application.

[0007] This application adopts the following technical solutions:

[0008] A method for preparing micro-nano magnesium hydride powder comprises the following steps:

[0009] S1. In a vacuum environment I, a magnesium raw material is heated to form magnesium vapor while introducing a trace amount of carrier gas I;

[0010] S2. In a vacuum environment II, the magnesium vapor is transported by the trace carrier gas I in step S1 and mixed with the carrier gas II to form a mixed gas. At the same time, the mixed gas is rapidly flowed by a jet evacuator to cool and hydrogenate the magnesium vapor to form the micro-nano magnesium hydride powder.

[0011] In the present application, the magnesium raw material is heated in an evaporation chamber of a magnesium vapor generator to form magnesium vapor.

[0012] The present application utilizes the Venturi effect of the jet evacuator to inhale the mixed gas and rapidly flow it along with the carrier gas II, thereby cooling the magnesium vapor in the mixed gas.

[0013] Optionally, after the trace carrier gas I is introduced, the pressure increase of the vacuum environment I is less than 300 Pa.

[0014] The purpose of introducing a trace amount of carrier gas I in this application is to utilize a low-pressure flowing carrier gas I to transport magnesium vapor. The prior art utilizes magnesium vapor to prepare small-sized magnesium powder by heating, melting, and vaporizing magnesium in a vacuum-evacuated container. The resulting magnesium vapor diffuses under a magnesium vapor pressure differential into a condensation section to prepare magnesium powder. This method is not only very inefficient and directly affects the gasification efficiency of magnesium, but also results in residual magnesium vapor remaining in the heating chamber and condensing after evaporation. This application introduces a trace amount of carrier gas I into the evaporation chamber without significantly affecting the vacuum level of the evaporation chamber. Under the action of an evacuator at the top of the evaporation chamber, a small airflow is formed to carry the generated magnesium vapor out of the evaporation chamber. This process reduces the magnesium vapor pressure above the magnesium liquid level, promotes magnesium evaporation, thereby improving evaporation efficiency and saving energy.

[0015] In the present application, the purpose of making the mixed gas of magnesium vapor and carrier gas II flow rapidly by jet evacuator is to simultaneously form and maintain vacuum and magnesium powder transportation, the high-speed airflow of jet evacuator will quickly carry away the carrier gas containing micro-nano magnesium powder, enter the separation tank, complete the automated transportation process, separate by filtration in the separation tank, and carrier gas II enters the carrier gas II circulation system through the filter module. In the prior art, magnesium vaporization and magnesium powder production technology not only requires a vacuum environment to facilitate the evaporation and gasification of magnesium, but also requires the generated magnesium vapor to be cooled to form magnesium powder and transported to the next unit. In the prior art, the gasification, transmission and condensation units of the magnesium vaporization and magnesium powder production process are in a vacuum system. The magnesium vapor is cooled by contacting the cold wall to form magnesium powder, and then collected by an electric brush. This transmission by magnesium vapor pressure difference is very slow and inefficient. The cooling belongs to inter-wall heat transfer, which is inefficient and energy-consuming. In addition, the magnesium powder particles produced are large, and the magnesium powder is difficult to collect and inefficient. The present application adopts a jet evacuator to perfectly solve the above problems. First, when the jet evacuator is used to generate vacuum, there is a high-speed airflow in the evacuator, which can not only quickly carry away the magnesium vapor, but also cool the magnesium vapor to generate magnesium powder. The cooling rate and efficiency of this direct contact type are much higher than those of the partition-type heat exchange. Since the air flow speed in the evacuator is very high, the magnesium crystal particles will not be large like the static condensation process. The magnesium vapor can generate smaller micro-nano-level magnesium powder under various comprehensive factors such as shear in the high-speed cooling airflow. The carrier gas containing the magnesium powder is directly filtered and separated through the separation tank, which is more efficient.

[0016] Optionally, the vacuum degree of the vacuum environment I is less than the vacuum degree of the vacuum environment II;

[0017] Optionally, the vacuum degree of the vacuum environment I is 10 -4 ~10 3 Pa.

[0018] Optionally, the vacuum degree of the vacuum environment II is 10 -4 ~10 -2 Pa.

[0019] Optionally, the magnesium raw material is magnesium or a magnesium-based metal;

[0020] The magnesium content in the magnesium-based metal is 60-99.99%.

[0021] Optionally, the micro-nano magnesium hydride powder is at least one of magnesium hydride particles and magnesium particles wrapped in a magnesium hydride shell.

[0022] Optionally, the particle size of the micro-nano magnesium hydride powder is 0.01-10 μm.

[0023] The carrier gas I and carrier gas II are independently selected from at least one of hydrogen and argon.

[0024] After leaving the evaporation chamber, the magnesium vapor is rapidly drawn in by the jet evacuator and mixed with the cooler carrier gas II. This cooling and heat exchange process occurs in a fluidized state, allowing the magnesium vapor / magnesium powder to efficiently exchange heat with carrier gas II, generating micro-nanoscale magnesium powder from the magnesium vapor. The generated magnesium powder and carrier gas heat exchange then reach a homogenized state. The magnesium vapor remains in a carrier gas atmosphere during generation, cooling, and transportation. The choice of carrier gas I and carrier gas II can be controlled during the magnesium vapor cooling process. When both carrier gas I and carrier gas II are argon, the product is magnesium powder particles. When both carrier gas I and carrier gas II are hydrogen, varying degrees of magnesium hydride can be generated on the surface of the magnesium powder, ranging from a few thin layers of magnesium hydride shell to complete hydrogenation. This allows for controllable micro-nanoscale size of the magnesium powder or magnesium hydride, preventing the aggregation and growth of magnesium particles during the cooling of pure magnesium vapor.

[0025] Optionally, the pressure of the carrier gas II in the vacuum environment II is 0.5-4 MPa.

[0026] When one or both of carrier gases I and II are hydrogen, the magnesium vapor is cooled by mixing with cold hydrogen carrier gas to produce micro-nano magnesium powder wrapped in a magnesium hydride shell. When both carrier gases I and II are argon, the magnesium vapor is cooled by mixing with cold argon carrier gas to produce micro-nano magnesium powder.

[0027] In the present application, when at least one of carrier gas I and carrier gas II is selected as hydrogen, the use of hydrogen can be used for the pre-hydrogenation of magnesium vapor. During the cooling process, magnesium vapor can exist in solid or liquid form under different temperature and pressure conditions. Both forms exist and continue to grow in size as the cooling process progresses, such as the merging of liquid phase droplets or the growth of crystals. The present application carries out the process of pre-hydrogenation by the selection of carrier gas, which is divided into two parts. First, a trace amount of hydrogen carrier gas is introduced when magnesium vapor is generated. While carrying magnesium vapor, a hydrogen atmosphere is given to magnesium vapor. Secondly, when magnesium vapor leaves the steam generation site and enters the conveying section, a jet evacuator is used at this position. The working gas is also hydrogen, which cools the magnesium vapor. Thereby ensuring that magnesium is always in a hydrogen atmosphere in vapor, liquid phase or solid phase, a layer of magnesium hydride shell will be generated on the magnesium solid surface during the magnesium vapor cooling process. This will prevent the further growth of the generated magnesium particles. The high-speed airflow in the jet evacuator can produce a shearing effect in the magnesium vapor condensation process, preventing the generation of large-sized magnesium powder.

[0028] Optionally, the hydrogenation comprises hydrogenation I and / or hydrogenation II;

[0029] The hydrogenation I comprises: the carrier gas II is hydrogen, and the cooled powder product is continuously hydrogenated at a temperature of 150 to 350° C. and then further cooled;

[0030] The hydrogenation II comprises: placing the cooled powder product or the powder product after hydrogenation I into a hydrogenation reactor, injecting hydrogen into the hydrogenation reactor, heating to 150-350° C., and hydrogenating until the powder product is entirely micro-nano magnesium hydride powder;

[0031] Optionally, the hydrogenation is hydrogenation I and / or hydrogenation II.

[0032] Optionally, after the hydrogenation I or before the hydrogenation II, the powder product is further separated and filtered.

[0033] Optionally, the hydrogenation I comprises: the carrier gas II is hydrogen, and the cooled powder product is continuously hydrogenated at a temperature of 320-350° C. and then further cooled;

[0034] Optionally, the hydrogenation II includes: placing the cooled powder product or the powder product after hydrogenation I into a hydrogenation reactor, injecting hydrogen into the hydrogenation reactor, heating to 320-350° C., and hydrogenating until the powder product is entirely micro-nano magnesium hydride powder.

[0035] Optionally, the method for preparing micro-nano magnesium hydride powder is carried out using the following apparatus:

[0036] The device comprises a magnesium vapor generator (1), a jet evacuator (2), a powder separation tank (3), a filter (5), a cooler (6), and a circulating carrier gas compressor (7);

[0037] The jet evacuator (2), the filter (5), the cooler (6), and the circulating carrier gas compressor (7) are connected in sequence through pipelines to form a circulation path;

[0038] The magnesium vapor generator (1) is connected and arranged outside the inlet end of the jet evacuator (2);

[0039] The upper outlet end of the powder separation tank (3) is provided with at least one filter module (4);

[0040] An isolation valve (10) is provided on a pipeline for discharging the powder product, which is connected to the lower outlet end of the powder separation tank (3);

[0041] The magnesium vapor generator (1) is also provided with a gas injection pipeline (11) for injecting carrier gas I;

[0042] The circulating carrier gas compressor (7) is also provided with a gas injection pipeline (11) for injecting carrier gas II;

[0043] The device further comprises a vacuum pump (9) arranged on a branch of the circulation path.

[0044] Optionally, the device further comprises a hydrogenation reactor (8);

[0045] The hydrogenation reactor (8) is arranged between the isolation valve (10) and the pipeline for discharging the powder product;

[0046] The hydrogenation reactor (8) is provided with a gas injection pipeline (11) for injecting hydrogen.

[0047] Optionally, the process of preparing micro-nano magnesium hydride powder by using the device and the method comprises: the outlet of the magnesium steam generator (1) is connected to the jet evacuator (2), the jet evacuator can be a single stage or a multi-stage according to actual needs, the outlet of the jet evacuator (2) is connected to the powder separation tank (3) through a pipeline, a filter module (4) is installed at the outlet position of the cavity inside the powder separation tank (3), the filter module can be one or more for switchable use, the filter module is connected to the filter inlet (5) through a pipeline, the powder separation tank (3) is connected to the hydrogenation reactor (8) through a pipeline below, an isolation valve (10) is installed on the connecting pipeline, the outlet of the filter (5) is connected to the inlet of the cooler (6) through a pipeline, the outlet of the cooler (6) is connected to the inlet of the circulating carrier gas compressor (7) through a pipeline, and the outlet of the circulating carrier gas compressor (7) is connected to the jet evacuator (2) through a pipeline.

[0048] First, the entire system is evacuated to a pressure of 10 -4 Pa-10 -2 Pa. Close and isolate the vacuum pump (9), and close the isolation valve (10). The magnesium raw material is transported to the magnesium vapor generator (9) through the continuous feeding pipeline, and the carrier gas I with a pressure of 0.5 to 4 MPa is filled into the system through the pipeline at the inlet of the circulating carrier gas compressor (7). The circulating carrier gas compressor (7) is started, and the carrier gas II passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating carrier gas compressor (7). In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of 10 -4 Pa-10 3 Pa.

[0049] The inductive heating device in the magnesium vapor generator (1) is started to heat the magnesium raw material until the magnesium is vaporized. At the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of carrier gas I, and the internal vacuum is ensured not to be greatly affected. The generated magnesium vapor quickly enters the vacuum evacuator under the dual action of the weak carrier gas I airflow and the suction force of the jet vacuum evacuator, and is mixed with the carrier gas II therein. When the carrier gas II is argon, the magnesium vapor is cooled to magnesium powder. When the carrier gas II is hydrogen, a layer of magnesium hydride is simultaneously produced on the surface of the magnesium powder particles during the process of the magnesium vapor cooling to magnesium powder, thereby preventing the magnesium powder particles from continuing to grow. The generated powder and carrier gas II enter the powder separation tank (3) and their speed decreases, the powder settles, and the carrier gas II containing trace powder passes through the filter module (4). The filter module (4) can filter out the powder. The filter module (4) has a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filtration facility that can remove the powder in the carrier gas II. The gas enters the cooler (6) after filtration to cool the carrier gas II to meet the intake temperature requirements of the selected circulating carrier gas compressor (7). The cooled carrier gas II enters the inlet of the circulating carrier gas compressor (7), completing a cycle.

[0050] Optionally, the process of preparing micro-nano magnesium hydride powder using the device and the method further includes: before the generated powder and the carrier gas II enter the powder separation tank (3), the generated powder enters the conveying pipeline under the action of the carrier gas II, and the magnesium powder continues to be hydrogenated at 150-350° C. and 0.5-4 MPa of the carrier gas II as hydrogen to complete the generation of micro-nano magnesium hydride powder.

[0051] Optionally, the process of preparing micro-nano magnesium hydride powder using the device and the method further includes: when the powder in the powder separation tank (3) is all micro-nano magnesium hydride powder, the isolation valve (10) is started after the powder amount reaches the set requirement, and the powder enters the hydrogenation reactor (8), and a vibration or gas loosening device is installed on the powder separation tank to ensure that the magnesium hydride powder enters the hydrogenation reactor (8) smoothly, and the isolation valve (10) is closed, and the magnesium hydride product (12) is transported to the next unit. Similarly, the hydrogenation reactor (8) is provided with a vibration or gas loosening device.

[0052] Optionally, the process of preparing micro-nano magnesium hydride powder using the device and the method further includes: when the powder in the powder separation tank (3) is not completely micro-nano magnesium hydride powder, the isolation valve (10) is started after the powder amount reaches the set requirement, the magnesium powder enters the hydrogenation reactor (8), the powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium powder enters the hydrogenation reactor (8) smoothly, and the isolation valve (10) is closed. The heating on the hydrogenation reactor (8) is started, and in order to ensure smooth mass and heat transfer of the magnesium powder, a stirring device can be installed in the hydrogenation reactor (8), the temperature of the magnesium powder therein is raised to 150-350°C, hydrogen is injected into the hydrogenation reactor (8) through the gas injection pipeline (11) on the hydrogenation reactor (8), and the pressure is maintained at 0.5-4.0MPa. The magnesium powder begins to absorb hydrogen and releases heat to increase the temperature. The temperature of the hydrogenation reactor (8) is maintained at the set temperature by the cooling system. After the hydrogen absorption is completed, the gas injection pipeline (11) is closed, the temperature is lowered to room temperature, and the magnesium hydride is transported to the next unit from the magnesium hydride product line (12). Similarly, the hydrogenation reactor (8) is provided with a vibration or gas loosening facility.

[0053] The beneficial effects of this application include:

[0054] Compared with the prior art, the method for preparing micro-nano magnesium hydride powder provided in the present application has higher gasification efficiency of magnesium, and magnesium is carried away by the airflow, less residue in the evaporation chamber, and high magnesium utilization rate; magnesium is cooled by direct mixing, which is much more efficient than partition-type heat exchange; the produced magnesium powder is directly brought into the next link by hydrogen carrier gas, eliminating the processes of passivation, opening the warehouse, and taking out the powder, making the magnesium powder transportation more efficient and safer, and easier to achieve large-scale and automated production; after the magnesium powder is generated, it is directly collected and entered into the hydrogenation reactor without the passivation process, and no magnesium oxide layer is generated on the surface of the magnesium powder particles, resulting in better activity, and the magnesium powder is micro-nano magnesium powder with smaller particle size, so the hydrogenation speed will be faster, thereby improving the hydrogenation efficiency; the pre-hydrogenation of the magnesium powder and the shearing effect of the high-speed hydrogen carrier gas produce smaller magnesium powder particles, and the magnesium hydride magnesium powder particles generated after hydrogenation are smaller and more active. The above advantages of the present application compared with the existing technology can more efficiently produce micro-nano magnesium hydride powder, which is not only convenient and efficient, but also has the characteristics of automation and continuity. The technical solution of the present application is not only applicable to small-scale production but also to large-scale production. The production scale of magnesium hydride is expanded, so that the large-scale production of magnesium hydride is not limited to the scale of hundreds of tons per year, thousands of tons per year, or tens of thousands of tons per year. The expansion of scale can effectively reduce the production cost of magnesium hydride. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a schematic diagram of the process flow for preparing micro-nanoscale magnesium hydride in Example 1 of the present application.

[0056] Figure ID

[0057] 1. Magnesium vapor generator; 2. Jet evacuator; 3. Powder separation tank; 4. Filtration module; 5. Filter; 6. Cooler; 7. Circulating carrier gas compressor; 8. Hydrogenation reactor; 9. Vacuum pump; 10. Isolation valve; 11. Gas injection pipeline; 12. Magnesium hydride product. DETAILED DESCRIPTION

[0058] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0059] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0060] Unless otherwise specified, conventional methods were used for testing, and instrument settings were those recommended by the manufacturer.

[0061] Example 1

[0062] The main equipment for preparing micro-nano magnesium hydride is as follows: the outlet of a magnesium vapor generator (1) is connected to a jet evacuator (2), the jet evacuator can be single-stage or multi-stage according to actual needs, the outlet of the jet evacuator (2) is connected to a powder separation tank (3) through a pipeline, a filter module (4) is installed at the outlet position of the cavity inside the powder separation tank (3), the filter module can be one or more for switchable use, the filter module is connected to the inlet of a filter (5) through a pipeline, the powder separation tank (3) is connected to a hydrogenation reactor (8) through a pipeline below, an isolation valve (10) is installed on the connecting pipeline, the outlet of the filter (5) is connected to the inlet of a cooler (6) through a pipeline, the outlet of the cooler (6) is connected to the inlet of a circulating carrier gas compressor (7) through a pipeline, and the outlet of the circulating carrier gas compressor (7) is connected to the jet evacuator (2) through a pipeline.

[0063] Preparation of micro-nano magnesium hydride:

[0064] First, the entire system is evacuated to a pressure of 10 -3 Pa. Close and isolate the vacuum pump (9), and close the isolation valve (10). Transport the magnesium raw material to the magnesium vapor generator (9) through the continuous feed pipeline, and fill the system with hydrogen at a pressure of 1 MPa through the gas injection pipeline (11) at the inlet of the circulating carrier gas compressor (7). Start the circulating carrier gas compressor (7), and the hydrogen passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating carrier gas compressor (7). In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of 300 Pa.

[0065] The induction heating device in the magnesium vapor generator (1) is started to heat the magnesium raw material to above 850° C., and at the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of hydrogen gas, and the internal vacuum is ensured not to be greatly affected. The generated magnesium vapor quickly enters the vacuum evacuator under the dual action of the weak hydrogen flow and the suction of the jet vacuum evacuator, and mixes with the hydrogen carrier gas therein. During the process of the magnesium vapor cooling into magnesium powder, a layer of magnesium hydride is simultaneously produced on the surface of the magnesium powder particles, thereby preventing the magnesium powder particles from continuing to grow. After the generated magnesium powder and hydrogen carrier gas enter the powder separation tank, their speed decreases, the powder settles, and the hydrogen carrier gas containing trace powder passes through the filter module (4). The filter module (4) can filter out powders larger than 100nm. The filter module (4) has a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filter facility that can remove powder from the carrier gas and protect the downstream cooler and compressor. The gas enters the cooler (6) after filtration to cool the hydrogen carrier gas to meet the intake temperature requirement (110°C) of the selected circulating carrier gas compressor (7). The cooled hydrogen carrier gas enters the inlet of the circulating carrier gas compressor (7), completing a cycle.

[0066] When the amount of magnesium powder in the powder separation tank (3) reaches the set requirement, the isolation valve (10) is started, and the magnesium powder enters the hydrogenation reactor (8). The powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium powder enters the hydrogenation reactor (8) smoothly, and the isolation valve (10) is closed. The heating on the hydrogenation reactor (8) is started. In order to ensure smooth mass and heat transfer of the magnesium powder, the stirring device installed in the hydrogenation reactor (8) is used to stir the powder, and the temperature of the magnesium powder is raised to 320°C. Hydrogen is injected into the hydrogenation reactor (8) through the gas injection pipeline (11) on the hydrogenation reactor (8), and the pressure is maintained at 3.0MPa. The magnesium powder begins to absorb hydrogen and releases heat to increase the temperature. The temperature of the hydrogenation reactor (8) is maintained at the set temperature by the cooling system. After the hydrogen absorption is completed, the gas injection pipeline (11) is closed, and the temperature is cooled to room temperature. The magnesium hydride is transported from the magnesium hydride product (12) to the next unit. Similarly, the hydrogenation reactor (8) is equipped with a vibration or gas loosening device.

[0067] Example 2

[0068] First, the entire system is evacuated to a pressure of 10 -3Pa. Close and isolate the vacuum pump (9), and close the isolation valve (10). Transport the magnesium alloy raw material to the magnesium vapor generator (9) through the continuous feed pipeline, and fill the system with hydrogen at a pressure of 1 MPa through the gas injection pipeline (11) at the inlet of the circulating carrier gas compressor (7). Start the circulating carrier gas compressor (7), and the hydrogen passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating carrier gas compressor (7). In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of between 300 Pa.

[0069] The induction heating device in the magnesium vapor generator is started to heat the magnesium alloy raw material to 850°C. At the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of hydrogen gas, and the internal vacuum is ensured not to be greatly affected. The generated magnesium alloy vapor quickly enters the vacuum evacuator under the dual action of the weak hydrogen flow and the suction of the jet vacuum evacuator, and mixes with the hydrogen carrier gas therein. During the process of cooling the magnesium vapor into magnesium alloy powder, a magnesium hydride layer is simultaneously produced on the surface of the magnesium alloy powder particles to prevent the magnesium powder particles from continuing to grow. After the generated magnesium alloy powder and hydrogen carrier gas enter the powder separation tank, their speed decreases, the powder settles, and the hydrogen carrier gas containing trace powder passes through the filter module (4). The filter module (4) can filter out powders larger than 100nm. The filter module (4) has a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filter facility that can remove powder from the carrier gas and protect the downstream cooler and compressor. The gas enters the cooler (6) after filtration to cool the hydrogen carrier gas to meet the intake temperature requirement (110°C) of the selected circulating carrier gas compressor (7). The cooled hydrogen carrier gas enters the inlet of the circulating carrier gas compressor (7), completing a cycle.

[0070] When the amount of magnesium alloy powder in the powder separation tank (3) reaches the set requirement, the isolation valve (10) is started, and the magnesium alloy powder enters the hydrogenation reactor (8). The powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium alloy powder enters the hydrogenation reactor (8) smoothly. The isolation valve (10) is closed. The heating on the hydrogenation reactor (8) is started. In order to ensure smooth mass and heat transfer of the magnesium alloy powder, the stirring device installed in the hydrogenation reactor (8) is started, and the temperature of the magnesium alloy powder is raised to 150°C. Hydrogen is injected into the hydrogenation reactor (8) through the gas injection pipeline (11) on the hydrogenation reactor (8). The pressure is maintained at 1.0MPa. The magnesium alloy powder begins to absorb hydrogen and releases heat to increase the temperature. The temperature of the hydrogenation reactor (8) is maintained at the set temperature through the cooling system. After the hydrogen absorption is completed, the gas injection pipeline (11) is closed, the temperature is lowered to room temperature, and the magnesium hydride is transported to the next unit from the magnesium hydride alloy product line (12). Similarly, the hydrogenation reactor (8) is provided with a vibration or gas loosening facility.

[0071] Example 3

[0072] First, the entire system is evacuated to a pressure of 10 -3 Pa. Close and isolate the vacuum pump (9), and close the isolation valve (10). Transport the magnesium alloy raw material to the magnesium vapor generator (9) through the continuous feed pipeline, and fill the system with hydrogen at a pressure of 1 MPa through the gas injection pipeline (11) at the inlet of the circulating carrier gas compressor (7). Start the circulating carrier gas compressor (7), and the hydrogen passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating carrier gas compressor (7). By adjusting the cooler, the hydrogen temperature at the outlet of the circulating carrier gas compressor (7) is kept at 150°C. In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of between 300 Pa.

[0073] The induction heating device in the magnesium vapor generator is started to heat the magnesium alloy raw material to 850°C. At the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of hydrogen gas, and the internal vacuum is ensured not to be greatly affected. The generated magnesium alloy vapor quickly enters the vacuum evacuator under the dual action of the weak hydrogen flow and the suction of the jet vacuum evacuator, and mixes with the hydrogen carrier gas therein. During the process of cooling the magnesium vapor into magnesium alloy powder, a magnesium hydride layer is simultaneously produced on the surface of the magnesium alloy powder particles to prevent the magnesium powder particles from continuing to grow. The generated micro-nano-particle magnesium powder enters the conveying pipeline under the action of hydrogen carrier gas. Under the action of hydrogen at 150°C and 1MPa, the magnesium powder continues to hydrogenate to complete the generation of micro-nano-grade hydride magnesium powder. The generated hydride magnesium powder and hydrogen carrier gas enter the powder separation tank and the speed is reduced. The powder settles. The hydrogen carrier gas containing trace powder passes through the filter module (4). The filter module (4) can filter out powder above 100nm. The filter module (4) has a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filtering facility that can remove powder in the carrier gas and protect the downstream cooler and compressor. The gas enters the cooler (6) after filtration to cool the hydrogen carrier gas to meet the intake temperature requirement (110°C) of the selected circulating carrier gas compressor (7). The cooled hydrogen carrier gas enters the inlet of the circulating carrier gas compressor (7), completing a cycle.

[0074] When the amount of magnesium hydride powder in the powder separation tank (3) reaches the set requirement, the isolation valve (10) is activated, and the magnesium hydride powder enters the hydrogenation reactor (8). The powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium hydride powder enters the hydrogenation reactor (8) smoothly. The isolation valve (10) is closed. The magnesium hydride is transported from the magnesium hydride product line (12) to the next unit. Similarly, the hydrogenation reactor (8) is equipped with a vibration or gas loosening device.

[0075] Example 4

[0076] The magnesium vapor generator (1) is a reduction furnace for producing magnesium by the Pidgeon process. First, the entire system is evacuated to a pressure of 10 -3 Pa. Close and isolate the vacuum pump (9), and close the isolation valve (10). Through the gas injection line (11) at the inlet of the circulating carrier gas compressor (7), hydrogen with a pressure of 1 MPa is filled into the system, and the circulating carrier gas compressor (7) is started. The hydrogen passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating carrier gas compressor (7). In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of between 300 Pa.

[0077] The heating device in the magnesium vapor generator (1) is started to heat the raw material to 1200° C. At the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of hydrogen gas, and the internal vacuum is ensured not to be greatly affected. The generated magnesium vapor quickly enters the vacuum evacuator under the dual action of the weak hydrogen flow and the suction of the jet vacuum evacuator, and mixes with the hydrogen carrier gas therein. During the process of the magnesium vapor cooling into magnesium powder, a layer of magnesium hydride is simultaneously produced on the surface of the magnesium powder particles, thereby preventing the magnesium powder particles from continuing to grow. After the generated magnesium powder and hydrogen carrier gas enter the powder separation tank, their speed decreases, the powder settles, and the hydrogen carrier gas containing trace powder passes through the filter module (4). The filter module (4) can filter out powders larger than 100nm. The filter module (4) has a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filter facility that can remove powder from the carrier gas and protect the downstream cooler and compressor. The gas enters the cooler (6) after filtration to cool the hydrogen carrier gas to meet the intake temperature requirement (110°C) of the selected circulating carrier gas compressor (7). The cooled hydrogen carrier gas enters the inlet of the circulating carrier gas compressor (7), completing a cycle.

[0078] When the amount of magnesium powder in the powder separation tank (3) reaches the set requirement, the isolation valve (10) is started, and the magnesium powder enters the hydrogenation reactor (8). The powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium powder enters the hydrogenation reactor (8) smoothly, and the isolation valve (10) is closed. The heating on the hydrogenation reactor (8) is started. In order to ensure smooth mass and heat transfer of the magnesium powder, a stirring device can be installed in the hydrogenation reactor (8). The temperature of the magnesium powder is raised to 320°C. Hydrogen is injected into the hydrogenation reactor (8) through the gas injection pipeline (11) on the hydrogenation reactor (8). The pressure is maintained at 3.0MPa. The magnesium powder begins to absorb hydrogen and releases heat to increase the temperature. The temperature of the hydrogenation reactor (8) is maintained at the set temperature by the cooling system. After the hydrogen absorption is completed, the gas injection pipeline (11) is closed, the temperature is lowered to room temperature, and the magnesium hydride is transported to the next unit from the magnesium hydride product line (12). Similarly, the hydrogenation reactor (8) is equipped with a vibration or gas loosening device.

[0079] Example 5

[0080] The main equipment for preparing micro-nano magnesium hydride is as follows: the outlet of a magnesium vapor generator (1) is connected to a jet evacuator (2), the jet evacuator can be single-stage or multi-stage according to actual needs, the outlet of the jet evacuator (2) is connected to a powder separation tank (3) through a pipeline, a filter module (4) is installed at the outlet position of the cavity inside the powder separation tank (3), the filter module can be one or more for switchable use, the filter module is connected to the inlet of a filter (5) through a pipeline, the powder separation tank (3) is connected to a hydrogenation reactor (8) through a pipeline below, an isolation valve (10) is installed on the connecting pipeline, the outlet of the filter (5) is connected to the inlet of a cooler (6) through a pipeline, the outlet of the cooler (6) is connected to the inlet of a circulating gas compressor (7) through a pipeline, and the outlet of the circulating gas compressor (7) is connected to the jet evacuator (2) through a pipeline.

[0081] Preparation of micro-nano magnesium hydride:

[0082] First, the entire system is evacuated to a pressure of 10 -3 Pa. Turn off and isolate the vacuum pump (9), and close the isolation valve (10). The magnesium raw material is transported to the magnesium vapor generator (9) through the continuous feeding pipeline, and argon gas with a pressure of 1 MPa is filled into the system through the gas injection pipeline (11) at the inlet of the circulating gas compressor (7). The circulating gas compressor (7) is started, and the argon gas passes through the jet evacuator (2), the powder separation tank (3), the filter module (4), the filter (5), the cooler (6) through the pipeline, and finally enters the inlet of the circulating gas compressor (7). In this process, the jet evacuator evacuates the magnesium vapor generator (1) to a pressure of 10 3 Pa.

[0083] The inductive heating device in the magnesium vapor generator (1) is started to heat the magnesium raw material to 850°C. At the same time, the gas injection pipeline (11) of the magnesium vapor generator (1) is opened to introduce a small amount of argon gas to ensure that the internal vacuum is not greatly affected. The generated magnesium vapor quickly enters the evacuator under the dual action of the weak argon flow and the suction of the jet evacuator, and is mixed with the argon carrier gas therein. After the generated magnesium powder and argon carrier gas enter the powder separation tank, the speed is reduced, the powder settles, and the argon carrier gas containing trace powder passes through the filter module (4). The filter module (4) can filter out powder above 100nm. The filter module (4) is provided with a backflush facility to prevent the pressure drop from increasing. The filtered gas enters the filter (5), which is a safety filtering facility that can remove powder in the carrier gas and protect the downstream cooler and compressor. The gas enters the cooler (6) after filtration, and the argon carrier gas is cooled to meet the intake temperature requirement (110°C) of the selected circulating gas compressor (7). The cooled argon carrier gas enters the inlet of the circulating gas compressor (7), completing a cycle.

[0084] When the amount of magnesium powder in the powder separation tank (3) reaches the set requirement, the isolation valve (10) is started, and the magnesium powder enters the hydrogenation reactor (8). The powder separation tank is equipped with a vibration or gas loosening device to ensure that the magnesium powder enters the hydrogenation reactor (8) smoothly, and the isolation valve (10) is closed. The argon in the hydrogenation reactor (8) is discharged, and the heating on the hydrogenation reactor (8) is started. In order to ensure smooth mass and heat transfer of the magnesium powder, the stirring device installed in the hydrogenation reactor (8) is used to stir the powder, and the temperature of the magnesium powder is raised to 320°C. Hydrogen is injected into the hydrogenation reactor (8) through the gas injection pipeline (11) on the hydrogenation reactor (8), and the pressure is maintained at 3.0MPa. The magnesium powder begins to absorb hydrogen and releases heat to increase the temperature. The temperature of the hydrogenation reactor (8) is maintained at the set temperature by the cooling system. After the hydrogen absorption is completed, the gas injection pipeline (11) is closed, the temperature is lowered to room temperature, and the magnesium hydride is transported to the next unit from the magnesium hydride product (12). Similarly, the hydrogenation reactor (8) is provided with a vibration or gas loosening facility.

[0085] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing micro-nanoscale magnesium hydride powder, characterized in that: The steps include: S1. In a vacuum environment I, a magnesium raw material is heated to form magnesium vapor while introducing a trace amount of carrier gas I; S2. In a vacuum environment II, the magnesium vapor is transported by the trace carrier gas I in step S1 and mixed with the carrier gas II to form a mixed gas. At the same time, the mixed gas is rapidly flowed by a jet evacuator to cool and hydrogenate the magnesium vapor to form the micro-nano magnesium hydride powder.

2. The method according to claim 1, characterized in that After the trace carrier gas I is introduced, the pressure increase of the vacuum environment I is less than 300 Pa.

3. The method according to claim 1, characterized in that The vacuum degree of the vacuum environment I is less than the vacuum degree of the vacuum environment II; Preferably, the vacuum degree of the vacuum environment I is 10 -4 ~10 3 Pa; Preferably, the vacuum degree of the vacuum environment II is 10 -4 ~10 -2 Pa.

4. The method according to claim 1, wherein The magnesium raw material is magnesium or magnesium-based metal; The magnesium content in the magnesium-based metal is 60-99.99%.

5. The method according to claim 1, wherein The micro-nano magnesium hydride powder is at least one of magnesium hydride particles and magnesium particles wrapped in a magnesium hydride shell; Preferably, the particle size of the micro-nano magnesium hydride powder is 0.01-10 μm.

6. The method according to claim 1, characterized in that The pressure of the carrier gas II in the vacuum environment II is 0.5-4 MPa.

7. The method according to claim 1, characterized in that The carrier gas I and carrier gas II are independently selected from at least one of hydrogen and argon.

8. The method according to claim 1, characterized in that The hydrogenation includes hydrogenation I and / or hydrogenation II; The hydrogenation I comprises: the carrier gas II is hydrogen, and the cooled powder product is continuously hydrogenated at a temperature of 150 to 350° C. and then further cooled; The hydrogenation II comprises: placing the cooled powder product or the powder product after hydrogenation I into a hydrogenation reactor, injecting hydrogen into the hydrogenation reactor, heating to 150-350° C., and hydrogenating until the powder product is entirely micro-nano magnesium hydride powder; Preferably, after the hydrogenation I or before the hydrogenation II, the powder product is further separated and filtered; Preferably, the hydrogenation I comprises: the carrier gas II is hydrogen, and the cooled powder product is continuously hydrogenated at a temperature of 320-350° C. and then further cooled; Preferably, the hydrogenation II comprises: introducing the cooled powder product or the powder product after hydrogenation I into a hydrogenation reactor, injecting hydrogen into the hydrogenation reactor, heating to 320-350° C., and hydrogenating until the powder product is entirely micro-nano magnesium hydride powder.

9. The method according to claim 1, characterized in that The method for preparing micro-nano magnesium hydride powder is prepared using the following device: The device comprises a magnesium vapor generator (1), a jet evacuator (2), a powder separation tank (3), a filter (5), a cooler (6), and a circulating carrier gas compressor (7); The jet evacuator (2), the filter (5), the cooler (6), and the circulating carrier gas compressor (7) are connected in sequence through pipelines to form a circulation path; The magnesium vapor generator (1) is connected and arranged outside the inlet end of the jet evacuator (2); The upper outlet end of the powder separation tank (3) is provided with at least one filter module (4); An isolation valve (10) is provided on a pipeline for discharging the powder product, which is connected to the lower outlet end of the powder separation tank (3); The magnesium vapor generator (1) is also provided with a gas injection pipeline (11) for injecting carrier gas I; The circulating carrier gas compressor (7) is also provided with a gas injection pipeline (11) for injecting carrier gas II; The device further comprises a vacuum pump (9) arranged on a branch of the circulation path.

10. The method according to claim 9, characterized in that The device also includes a hydrogenation reactor (8); The hydrogenation reactor (8) is arranged between the isolation valve (10) and the pipeline for discharging the powder product; The hydrogenation reactor (8) is provided with a gas injection pipeline (11) for injecting hydrogen.

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