Preparation method of magnesium hydride powder

Abstract

The invention relates to the field of magnesium-based hydrogen storage materials, and discloses a magnesium hydride powder preparation method which comprises the following steps: S1, material preparation: feeding a hydrogenation powder preparation raw material into a smelting crucible of gas atomization equipment, melting the hydrogenation powder preparation raw material through the smelting crucible, and heating to a hydrogenation powder preparation process temperature to obtain molten metal; and S2, atomization powder preparation and hydrogenation are conducted, specifically, hydrogenated mixed gas meeting technological parameters is supplied through a gas generation mechanism, the hydrogenated mixed gas is guided into gas atomization equipment, and the molten metal obtained in the S1 is converted into magnesium hydride powder through the hydrogenated mixed gas. According to the scheme, magnesium hydride which is stable in property and has a certain hydrogen content is directly prepared through the magnesium ingot, the deep powder hydrogenation process period is shortened, and the process route is safer and more controllable, so that an existing process route is replaced.

Description

Technical Field

[0001] The present invention relates to the field of magnesium-based hydrogen storage materials, and particularly to a method for preparing magnesium hydride powder. Background Art

[0002] Magnesium-based hydrogen storage materials are considered to be one of the most promising metal hydrogen storage materials due to their large hydrogen storage capacity, rich resources, and low cost. They can release and absorb hydrogen under certain conditions and can be applied in new energy, medicine, agriculture and other fields. As a reversible "storage" medium for hydrogen, it has excellent hydrogen absorption and desorption performance, and the advantages of no kinetic attenuation and capacity loss during long-term cycling, enabling large-capacity solid-state hydrogen storage and long-distance transportation at normal temperature and pressure. It can not only reduce the storage and transportation costs and energy consumption of hydrogen, but also be safe and convenient, and is expected to become an important key material in the field of hydrogen storage and transportation, thus promoting the development of the hydrogen energy industry.

[0003] Currently, there are various common methods for preparing magnesium hydride, among which the direct reaction method is particularly prominent. This method directly reacts magnesium-based powder with hydrogen by pressurizing and heating to produce high-purity magnesium hydride and can be recycled. It is regarded as the most potential preparation process in the field of hydrogen storage materials. However, due to the high reactivity of magnesium-based powder, it faces problems of insufficient safety and low production efficiency when directly prepared into powder. In addition, the subsequent hydrogenation process of metal powder takes a long time and the production capacity is limited. These factors significantly hinder the progress of hydrogen storage material technology. Summary of the Invention

[0004] The present invention aims to provide a method for preparing magnesium hydride powder to improve the existing magnesium hydride preparation process and provide a safer and more efficient magnesium hydride preparation technology.

[0005] To achieve the above object, the present invention adopts the following technical scheme: A method for preparing magnesium hydride powder includes the following steps:

[0006] S1 Material Preparation: Put the raw materials for hydrogenation powder preparation into the melting crucible of the gas atomization equipment, and through the melting crucible, the raw materials for hydrogenation powder preparation are melted and heated to the hydrogenation powder preparation process temperature to obtain a metal melt;

[0007] S2 Atomization Powder Preparation and Hydrogenation: Supply a hydrogenation mixed gas that meets the process parameters through a gas generation mechanism, and introduce the hydrogenation mixed gas into the gas atomization equipment, and use the hydrogenation mixed gas to convert the metal melt obtained in S1 into magnesium hydride powder.

[0008] The beneficial effects of this solution are as follows: The existing process route for magnesium hydride powder: It is necessary to first prepare magnesium powder with active properties, and then hydrogenate the magnesium powder to prepare magnesium hydride. When preparing magnesium hydride by hydrogenating magnesium powder, a certain catalyst needs to be added, and the reaction is carried out under medium temperature (200 °C and above) and low pressure (0.5 MPa and above) conditions for a long time (more than 5 h). The entire process cycle is relatively long. This solution directly prepares magnesium hydride with stable properties and a certain hydrogen content from magnesium ingots, reducing the process cycle of deep powder hydrogenation, and the process route is safer and more controllable, thus replacing the existing process route.

[0009] Further, the process parameters of the hydrogenation mixed gas are as follows: The gas pressure is 3 - 8 MPa, the mixed gas is hydrogen and argon, the hydrogen content is controlled at 20 - 200 ppm, the temperature is 100 - 400 °C, and the gas flow rate is controlled at 500 - 3000 m 3 / h.

[0010] Beneficial effects: By using argon as the dilution gas for hydrogen, the hydrogen content in the mixed gas is 20 - 200 ppm, thus avoiding the situation that most of the produced powder exists in the form of magnesium powder due to too low hydrogen content. When exposed to the atmospheric environment, since magnesium powder easily reacts with oxygen in the atmosphere, the product has high activity and high danger; when the hydrogen content is too high, the atomizing gas becomes a flammable gas, with high potential safety hazards; when using other inert gases as the dilution gas: taking nitrogen as an example, it easily reacts with magnesium at high temperatures, resulting in an increase in the nitrogen content of the powder, thereby reducing the final hydrogen storage capacity of the powder; the prices of the remaining inert gases are high, and taking helium as an example, due to a certain reaction time for hydrogenation and the relatively good heat transfer effect of helium, the metal powder produced by gas atomization cools down rapidly, resulting in a shortened hydrogenation reaction time, affecting the hydrogenation effect, and increasing the proportion of magnesium powder in the produced powder, affecting the safety of the product.

[0011] Further, the gas atomization equipment is a close-coupled gas atomization structure, the hydrogenation and atomization pressure is controlled at 3 - 8 Mpa, and the process temperature for magnesium melt hydrogenation powder production is 700 - 900 °C.

[0012] Further, the gas generation mechanism includes a gas heating unit and a gas supply unit. The gas heating unit includes a gas heating pipeline and a temperature regulator. Both ends of the gas heating pipeline are respectively connected to the intake controller and the gas atomization equipment, and can control the temperature of the gas introduced into the gas atomization equipment according to the temperature regulator. The gas supply unit includes a high-pressure hydrogen station, a high-pressure argon station, and an intake controller. The high-pressure hydrogen station and the high-pressure argon station are respectively connected to the intake controller, and the intake controller is connected to the gas heating pipeline and can control the proportion of hydrogen and argon entering the gas heating pipeline.

[0013] Furthermore, the gas generation mechanism further includes a gas circulation unit, which includes a filtration section, a detection component, and a pressurization section. The filtration section is connected to the exhaust port of the gas atomization device, the pressurization section is connected to the intake controller, and a deoxidation section is provided between the detection component and the pressurization section. The oxygen content of the recycled gas should be less than 20 ppm. This oxygen content requirement can ensure a very high purity of hydrogen in the gas, preventing explosion, and also ensure a relatively low oxygen content in the hydrogenated powder, further improving the hydrogen storage capacity of magnesium hydride. The collected oxygen content signal is fed back to the deoxidation section. If the oxygen content is higher than 20 ppm, the deoxidation section will be activated to process the unqualified gas until the oxygen content meets the standard.

[0014] Furthermore, it also includes an S3 material circulation: The S3 material circulation includes an S31 gas-solid circulation, and the S31 gas-solid circulation is as follows: The gas discharged and inspected as qualified during S2 atomization powder making and hydrogenation is passed through a gas circulation pressurization device into a gas rapid heating device to form a gas-solid circulation system.

[0015] Furthermore, the S3 material circulation also includes an S32 solid material circulation, and the S32 solid material circulation is as follows: The magnesium hydride powder obtained during S2 atomization powder making and hydrogenation is subjected to powder classification, and the magnesium hydride powder that fails to pass the powder classification is re-introduced as a raw material for hydrogenation powder making into the gas atomization powder making equipment to form a solid material circulation.

[0016] Furthermore, the gas atomization device further includes a diversion pipe, which can withstand the erosion of molten metal at temperatures above 900°C and a mixed gas of high-pressure hydrogen and argon at 8 MPa and below 400°C for 8 hours, and the inner diameter change is less than 2%. Description of the Drawings

[0017] Figure 1 It is a flow chart of the method for preparing magnesium hydride powder in an embodiment of the present invention;

[0018] Figure 2 It is a schematic diagram of the detection result of the powder passing morphology of the magnesium hydride powder obtained in an embodiment of the present invention;

[0019] Figure 3 It is a schematic diagram of the detection result of the powder passing particle size of the magnesium hydride powder obtained in an embodiment of the present invention;

[0020] Figure 4 It is a schematic diagram of the connection relationship between the gas generation mechanism and the gas atomization device in an embodiment of the present invention. Detailed Embodiments

[0021] The following is a further detailed description through specific embodiments:

[0022] Description of the drawings: Heating unit 12, temperature regulator 121, heating pipeline 122, intake controller 111, hydrogen station 112, argon station 113, circulation unit 13, filtration section 131, oxygen content detector 132, deoxygenation section 133, pressurization section 134, hydrogen content detector 135, gas flow detector 136, gas atomization equipment 2.

[0023] Example 1

[0024] Example 1 is basically as shown in the attached Figure 1 figure, as Figure 1 shown, a method for preparing magnesium hydride powder includes the following steps: S1 Material preparation: Put the raw materials for hydrogenation powder making into the melting crucible of the gas atomization equipment 2, and through the melting crucible, the raw materials for hydrogenation powder making are melted and heated to the hydrogenation powder making process temperature to obtain a metal melt.

[0025] S2 Atomization powder making and hydrogenation: Supply hydrogenation mixed gas that meets the process parameters through the gas generating mechanism, and introduce the hydrogenation mixed gas into the gas atomization equipment 2, and use the hydrogenation mixed gas to convert the metal melt obtained in S1 into magnesium hydride powder.

[0026] The specific implementation process is as follows:

[0027] S1 Material preparation: Prepare 20 kg of magnesium ingots with a purity of 99.95% as raw materials; load them into the melting crucible of the gas atomization equipment 2. In this example, the gas atomization equipment 2 is a HER-MIGA type gas atomization powder making equipment. Operate according to the operating procedures, evacuate to 10 -1 Pa, and then start heating and melting the magnesium ingots; wait until the magnesium ingots are completely melted and heated to the powder making process temperature. In this example, the powder making process temperature is 810 °C.

[0028] S2 Atomization powder making and hydrogenation: Let the molten metal magnesium flow into the hydrogenation powder making device, supply hydrogenation mixed gas that meets the process parameters through the gas generating mechanism. The process parameters of the hydrogenation mixed gas are: gas pressure is 5 MPa, the ratio of hydrogen to argon is 15:85 (hydrogen content is about 88 ppm), the temperature is 150 - 180 °C, and the gas flow rate is controlled at 1200 - 1300 m 3 / h, and introduce the hydrogenation mixed gas into the gas atomization equipment 2, and start hydrogenation and atomization powder making. In this example, the hydrogenation and atomization pressure is controlled at 4.9 - 5.1 Mpa, that is, the gas pressure of the hydrogenation mixed gas is 4.9 - 5.1 Mpa; under the action of the high-speed and heated mixed gas flow, the metal liquid flow is broken into fine droplets, and these droplets quickly cool and solidify into micron-sized powder particles during flight, that is, magnesium hydride powder is obtained. The prepared magnesium hydride powder is collected using a powder storage tank, and through powder classification, powders with a particle size of 0 - 150 μm are selected.

[0029] After the hydrogenation powder making is completed, the hydrogen content, powder morphology, and particle size of the selected magnesium hydride powder are detected. The hydrogen content of the magnesium hydride powder is 2.78 - 3.16 wt%. The results of the powder morphology detection are as Figure 2 shown, and the powder particle size detection is as Figure 3 shown.

[0030] Example 2

[0031] Example 2 is basically the same as Example 1, except that it further includes an S3 material cycle. The S3 material cycle includes an S31 gas - material cycle and an S32 solid - material cycle. Among them, the S31 gas - material cycle is as follows: The gas discharged and inspected as qualified during S2 atomization powder making and hydrogenation is introduced into the gas rapid heating device through the gas cycle pressurizing device to form a gas - material cycle system.

[0032] The S32 solid - material cycle is as follows: The magnesium hydride powder obtained during S2 atomization powder making and hydrogenation is subjected to powder classification, and the magnesium hydride powder that fails to pass the powder classification is re - input into the gas atomization powder making equipment as the raw material for hydrogenation powder making to form a solid - material cycle.

[0033] The specific implementation process is as follows:

[0034] S1 raw material preparation, S2 atomization powder making and hydrogenation are basically the same as in Example 1, except that:

[0035] In S1 raw material preparation, the raw material is magnesium ingot or the magnesium hydride powder obtained during S2 atomization powder making and hydrogenation is subjected to powder classification, and the magnesium hydride powder with a particle size larger than 150 μm is screened out and added as the raw material for hydrogenation powder making to re - make powder, thereby forming the S32 solid - material cycle to improve the utilization rate of solid materials and reduce the treatment cost of waste materials;

[0036] During S2 atomization powder making and hydrogenation, the discharged gas after hydrogenation enters the gas cycle pressurizing device through a pipeline. The powder in the gas is recovered through filtration and purification. After testing, the oxygen content is lower than 20 ppm. The qualified recovered gas is pressurized to 5.5 MPa, the hydrogen content is 75 ppm after testing, and the gas flow rate is 1128 m3 / h. The system feeds back the collected data to the gas rapid heating device. By supplementing hydrogen and argon in a ratio of 15:85 of gas flow rate to 1200 - 1300 m3 / h, and then through heating to a temperature of 150 - 180 °C, the mixed gas is filled into the hydrogenation powder making device again, thereby forming the S31 gas - material cycle, realizing gas - cycle hydrogenation powder making, and further reducing the loss of gas - materials;

[0037] Example 3

[0038] Based on Example 2, as Figure 4As shown in the figure, the gas generation mechanism includes a gas heating unit 12, a gas supply unit, and a gas circulation unit 13. The gas heating unit 12 includes a gas heating pipeline 122 and a temperature regulator 121. Both ends of the gas heating pipeline 122 are respectively connected to the intake controller 111 and the gas atomization device 2, and can control the temperature of the gas introduced into the gas atomization device 2 according to the temperature regulator 121, so that the temperature of the gas entering the gas atomization device 2 meets the temperature requirements for atomization powder making and hydrogenation.

[0039] The gas supply unit includes a high-pressure hydrogen station 112, a high-pressure argon station 113, and an intake controller 111. The high-pressure hydrogen station 112 and the high-pressure argon station 113 are respectively connected to the intake controller 111. The intake controller 111 is connected to the gas heating pipeline 122 and can control the proportion and pressure of hydrogen and argon entering the gas heating pipeline 122, so that the gas proportion and pressure entering the gas heating pipeline 122 meet the process parameters.

[0040] The gas circulation unit 13 includes a filtration part 131, a pressurization part 134, and a detection component. The filtration part 131 is connected to the exhaust port of the gas atomization device 2. The pressurization part 134 is connected to the intake controller 111. The detection component includes an oxygen content detector 132, a hydrogen content detector 135, and a gas flow detector 136. The oxygen content detector 132, the hydrogen content detector 135, and the gas flow detector 136 are sequentially arranged on the inner wall of the connecting pipeline between the filtration part 131 and the intake controller 111. The pressurization part 134 is arranged between the oxygen content detector 132 and the hydrogen content detector 135. An oxygen removal part 133 is arranged between the oxygen content detector 132 and the pressurization part 134. When the oxygen content detector 132 detects that the oxygen content of the gas is unqualified, the oxygen removal part 133 opens to process the unqualified gas and then inputs it to the gas filtration part 131 until the oxygen content reaches the standard. When the oxygen content detector 132 detects that the oxygen content is qualified, the pressurization part 134 starts to pressurize the detected qualified gas so that the pressure of the gas meets the process requirements. Subsequently, the hydrogen content and gas flow of the pressurized gas are detected by the hydrogen content detector 135 and the gas flow detector 136, and the detection results are fed back to the intake controller 111. The intake controller 111 can control the high-pressure hydrogen station 112 and the high-pressure argon station 113 to supplement gas according to the fed-back detection results to ensure that the gas entering the gas heating pipeline 122 meets the process parameters.

[0041] During use, hydrogen and argon with specific ratios and pressures are introduced into the gas heating pipeline 122 through the intake controller 111 according to process requirements. The gas heating pipeline 122 quickly heats the gas to the temperature required by the process. In this embodiment, the temperature required by the process is 150 - 180°C. The temperature detection and regulation instrument is used to detect the temperature of the hydrogenated mixed gas at the outlet of the heating pipeline, and feedback the collected temperature information to the heater of the gas rapid heating pipeline through an electrical signal, so as to adjust the heating power and make the temperature of the output gas meet the process requirements. When performing gas circulation, the intake controller 111 controls the makeup gas flow rates of the high-pressure hydrogen station 112 according to the hydrogen content detected by the hydrogen content detector 135 of the gas circulation unit 13, ensuring that the hydrogen content of the hydrogenated mixed gas is controlled within 20 - 200 ppm.

[0042] Example 4

[0043] The gas atomization device 2 further includes a diversion tube, which can withstand the erosion of molten metal at temperatures above 900°C and a mixed gas of high-pressure hydrogen and argon at 8 MPa and below 400°C for 8 hours, and the inner diameter change is less than 2%.

[0044] The diversion tube is prepared by machining a composite ceramic rod. The preparation process of the composite ceramic rod is as follows:

[0045] S1. Mix the dispersant with deionized water, then add zirconium oxychloride and magnesium chloride to the solution and stir to prepare a dispersion solution until the zirconium ion concentration in the dispersion solution is 0.1 - 0.5 mol / L and the magnesium ion concentration is 0.02 - 0.2 mol / L, and heat the dispersion solution to 40 - 80°C. Specifically, the dispersant is anhydrous ethanol, and the volume of anhydrous ethanol is 8% - 12% of the volume of the dispersion solution;

[0046] S2. Preheat the raw material tank of the centrifugal spray dryer to 40 - 80°C, add the dispersion solution to the raw material tank of the centrifugal spray dryer and stir; add ammonia water to the auxiliary material tank of the centrifugal spray dryer, feed the dispersion solution at a speed of 0.1 - 0.3 L / min and ammonia water at a speed of 0.5 - 2 L / min, and mix before entering the centrifugal atomizer to obtain a mixed solution. During this process, keep the temperature of the raw material tank at 40 - 80°C. In actual implementation, stir the dispersion solution during atomization, and repeat step 1 again, adding the newly prepared dispersion solution and ammonia water to the raw material tank and the auxiliary material tank respectively. Specifically, the ammonia water has a concentration of 25%;

[0047] S3. Use a centrifugal spray dryer to atomize the dispersion solution. When atomizing, the centrifugal spray dryer sprays out the mixed solution at a speed of 12,000 - 18,000 rpm / min to form fine droplets of the mixed solution. Use drying air or inert gas at a temperature of 150 - 300 °C to dry the droplets produced by atomization to obtain mixed powder;

[0048] S4. Spread the ZrO(OH)2 + Mg(OH)2 mixed powder evenly in a zirconia ceramic crucible ark and heat and decompose it in an atmospheric environment using a muffle furnace. The residual solid ammonium chloride completely volatilizes to prepare pure zirconia and magnesia. The principle is: under heating conditions, ZrO(OH)2 → ZrO2 + H2O, Mg(OH)2 → MgO + H2O. Under the action of temperature, zirconia and magnesia will form a mixed powder mass; The heating and decomposition process is: in an atmospheric environment, heat up evenly at a heating rate of 10 - 20 °C / min to the heating and decomposition temperature of 500 - 700 °C, and keep it warm for 1 - 3 h. After the heat preservation ends, cool it naturally to room temperature; Obtain a powder mass;

[0049] S5. Grind and crush the powder mass, and then hot-press and sinter it into a composite ceramic rod. The sintering temperature is 1600 - 1800 °C. Before sintering, first heat it to 600 - 800 °C for pre-sintering and keep it warm for 0.5 - 1 h, and then heat it to the sintering temperature for sintering. During the whole heating process, control the heating rate to 10 - 20 °C / min and control the temperature to rise evenly; After reaching the sintering temperature, apply pressure to the powder, the pressure is 100 - 150 tons, keep it warm and under pressure for 1 - 3 h, and then cool it with the furnace to obtain a composite ceramic rod.

[0050] The above are only embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail here. It should be noted that the technical means for solving problems in the above embodiments of the present invention can be used in combination to solve multiple technical problems at the same time. For those skilled in the art, without departing from the technical solution of the present invention, several deformations and improvements can also be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicability of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing magnesium hydride powder, characterized in that: The steps include: S1 material preparation: putting the raw materials for hydrogenation powder making into the melting crucible of the gas atomization equipment, melting the raw materials for hydrogenation powder making through the melting crucible and heating them to the hydrogenation powder making process temperature to obtain a molten metal; S2 atomization powder making and hydrogenation: The hydrogenation mixed gas that meets the process parameters is supplied through the gas generating mechanism, and the hydrogenation mixed gas is introduced into the gas atomization equipment, and the metal melt obtained in S1 is converted into magnesium hydride powder by using the hydrogenation mixed gas.

2. A method for preparing magnesium hydride powder according to claim 1, characterized in that: The process parameters of hydrogenation gas mixture are as follows: gas pressure is 3-8MPa, the gas mixture is hydrogen and argon, the hydrogen content is controlled at 20-200ppm, the temperature is 100-400℃, and the gas flow rate is controlled at 500-3000m 3 / h.

3. A method for preparing magnesium hydride powder according to claim 1, characterized in that: The gas atomization equipment is a tightly coupled gas atomization structure. The hydrogenation and atomization pressures are controlled at 3-8Mpa. The process temperature of the magnesium melt hydrogenation powder making is 700-900℃.

4. A method for preparing magnesium hydride powder according to claim 1, characterized in that: The gas generating mechanism includes a gas heating unit and a gas supply unit. The gas heating unit includes a gas heating pipeline and a temperature regulator. Both ends of the gas heating pipeline are respectively connected to the gas intake controller and the gas atomization equipment and can control the temperature of the gas introduced into the gas atomization equipment according to the temperature regulator. The gas supply unit includes a high-pressure hydrogen station, a high-pressure argon station and a gas intake controller. The high-pressure hydrogen station and the high-pressure argon station are respectively connected to the gas intake controller. The gas intake controller is connected to the gas heating pipeline and can control the ratio of hydrogen and argon entering the gas heating pipeline.

5. A method for preparing magnesium hydride powder according to claim 4, characterized in that: The gas generating mechanism also includes a gas circulation unit, which includes a filter part, a detection component and a pressurizing part. The filter part is connected to the exhaust port of the atomization equipment, the pressurizing part is connected to the air intake controller, and a deoxygenation part is arranged between the detection component and the pressurizing part.

6. A method for preparing magnesium hydride powder according to claim 1, characterized in that: It also includes S3 material circulation: S3 material circulation includes S31 gas material circulation. S31 gas material circulation is: the gas discharged and qualified in S2 atomization powder making and hydrogenation is passed into the gas rapid heating device through the gas circulation pressurizing device to form a gas material circulation system.

7. A method for preparing magnesium hydride powder according to claim 6, characterized in that: The S3 material cycle also includes the S32 solid material cycle. The S32 solid material cycle is as follows: the magnesium hydride powder obtained in the S2 atomization powder making and hydrogenation is subjected to powder classification, and the magnesium hydride powder with unqualified particle size after the powder classification screening is used as the raw material for hydrogenation powder making and is re-added into the gas atomization powder making equipment to form a solid material cycle.

8. A method for preparing magnesium hydride powder according to claim 1, characterized in that: The gas atomization equipment also includes a flow guide tube, which can withstand the continuous flushing of molten metal above 900°C and high-pressure hydrogen and argon mixed gas of 8MPa and below 400°C for 8 hours with the inner diameter change being less than 2%.

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