A self-propagating tunnel kiln device and method for preparing amorphous boron powder

Abstract

The present invention provides a self-propagating tunnel kiln device and a method for preparing amorphous boron powder thereof, the self-propagating tunnel kiln device comprising: an automatic feeding system, a self-propagating reaction section, a cooling section, a ventilation system, a pneumatic separation pressure relief valve, a multi-electrode igniter, a strong convection inert gas injection system and a circulating cooling system; the automatic feeding system is connected to the feeding end of the self-propagating reaction section; the discharging end of the self-propagating reaction section is connected to the feeding end of the cooling section; the ventilation system is arranged in the self-propagating reaction section and is connected to the self-propagating reaction section; the pneumatic separation pressure relief valve is arranged on one side of the discharging end of the self-propagating reaction section, and the pneumatic separation pressure relief valve connects the self-propagating reaction section with the external environment; the multi-electrode igniter is arranged on the inner side of the bottom of the self-propagating reaction section; the strong convection inert gas injection system is arranged around the outside of the cooling section and is connected to the cooling section; the circulating cooling system is arranged inside the cooling section. The process of producing amorphous boron powder according to the present invention has strong continuity and low energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of amorphous boron powder preparation, and in particular to a self-propagating tunnel kiln device and a method for preparing amorphous boron powder. Background Art

[0002] Amorphous boron powder, also known as amorphous boron powder, has become one of the most promising fuel-rich solid additives due to its high mass calorific value and volume calorific value. The improvement of its performance depends not only on the material composition, structure and defects, but also on the preparation process. Mechanical alloying (MA) is a powder metallurgy process that uses the mechanochemical effect between elemental powders to synthesize compounds. Powder metallurgy technology combining mechanical alloying with high-temperature synthesis in a self-propagating tunnel kiln is an important method for preparing materials. This method is simple and efficient, and can introduce nanostructures and defects. However, the traditional mechanical alloying combined with the self-propagating tunnel kiln method is highly intermittent and energy-intensive, making it impossible to achieve continuous industrial production and the cost is also high. Summary of the Invention

[0003] The embodiment of the present invention provides a self-propagating tunnel kiln device, which aims to solve the problems of strong intermittency and high energy consumption of traditional mechanical alloying combined with self-propagating tunnel kiln means.

[0004] In a first aspect, an embodiment of the present invention provides a self-propagating tunnel kiln device, comprising: an automatic feeding system, a self-propagating reaction section, a cooling section, a ventilation system, a pneumatic separation pressure relief valve, a multi-electrode igniter, a strong convection inert gas injection system, and a circulating cooling system;

[0005] The automatic feeding system is connected to the feeding end of the self-propagating reaction section;

[0006] The discharge end of the self-propagating reaction section is connected to the feed end of the cooling section;

[0007] The ventilation system is arranged in the self-propagating reaction section and is in communication with the self-propagating reaction section;

[0008] The pneumatic separation pressure relief valve is arranged on one side of the discharge end of the self-propagating reaction section, and the pneumatic separation pressure relief valve connects the self-propagating reaction section with the external environment;

[0009] The multi-electrode igniter is arranged on the inner side of the bottom of the propagation reaction section;

[0010] The strong convection inert gas injection system is arranged around the outside of the cooling section and is in communication with the cooling section;

[0011] The circulating cooling system is arranged inside the cooling section;

[0012] The inert gas includes one of argon and helium. Valves are provided at both ends of the self-propagating reaction section and both ends of the cooling section.

[0013] Furthermore, the ventilation system includes: a vacuum pumping device and an inert gas filling device, the vacuum pumping device is arranged on the feed end side of the self-propagating reaction section and is connected to the self-propagating reaction section; the inert gas filling device is arranged on the outside of the self-propagating reaction section and is connected to the self-propagating reaction section.

[0014] Furthermore, the automatic feeding system includes a starting feeding device and a plurality of feeding trays.

[0015] Furthermore, the multi-electrode igniter includes: a first ignition electrode and a second ignition electrode, the first ignition electrode and the second ignition electrode are both arranged on the inner side of the bottom of the self-propagating reaction section, and the first ignition electrode and the second ignition electrode are arranged side by side.

[0016] Furthermore, the circulating cooling system is an ice-brine circulating system.

[0017] Furthermore, it also includes a waste gas collection device, which is connected to the self-propagating reaction section.

[0018] The present invention also provides a method for preparing amorphous boron powder. The method is applied to the self-propagating tunnel kiln device provided in the above embodiment, and the method comprises the steps of:

[0019] S1. Mixing raw materials of boron oxide and magnesium powder in a mass ratio of 1:1.2-1:3.0 in a grinding device under an inert gas protection state for 5-10 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium;

[0020] S2. After the mixing is completed, the obtained mixture is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple material trays of the automatic feeding system for multiple ventilation reactions;

[0021] S3. Start the multi-electrode igniter to ignite each material tray. The reaction lasts for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, the pneumatic separation pressure relief valve is started to release the pressure.

[0022] S4, filling with inert gas, closing the pneumatic separation pressure relief valve after the smoke disappears, opening the cooling section feed valve connected to the self-propagating reaction stage, starting the feeding device, controlling the material tray to enter the cooling section, closing the cooling section feed valve, starting the strong convection inert gas injection system, and rapidly cooling the material for 10 minutes, opening the cooling section discharge valve, starting the automatic feeding device, and pushing the cooled material out of the cooling section;

[0023] S5. The cooled material is subjected to a first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 3 mol / L-12 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. The mixture is stirred for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed.

[0024] S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

[0025] Furthermore, in S1, the mass ratio of the raw materials boron oxide and magnesium powder is 1.5:1.1, and the mixing time is 10 hours.

[0026] Furthermore, in S2, the mixing height of the material tray is 2 cm.

[0027] Furthermore, in S5, the concentration of diluted hydrochloric acid added is 6 mol / L.

[0028] In an embodiment of the present invention, the batch mixture is transported to the self-propagating reaction section for reduction reaction by an automatic feeding system. During the reduction reaction, the batch mixture is ignited by a multi-electrode igniter (no external heating device is required, energy saving), and ventilation is performed by a ventilation system so that the self-propagating reaction section is in an inert gas protection state. The self-propagating reaction section is then controlled to be in a set air pressure by a pneumatic separation pressure relief valve. Finally, the reacted material is transported to a cooling section, cooled by a strong convection inert gas injection system and a circulating cooling system, and the cooling section is output. The process of producing amorphous boron powder in the self-propagating tunnel kiln device of the present invention is strong in continuity and low in energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 This is a structural diagram of a self-propagating tunnel kiln device provided by an embodiment of the present invention;

[0031] Figure 2 This is a scanning electron microscope photograph of 1 μm amorphous boron powder prepared in Example 2 of the present invention;

[0032] Figure 3 This is a scanning electron microscope photograph of 2 μm amorphous boron powder prepared in Example 2 of the present invention;

[0033] Figure 4 This is a scanning electron microscope photograph of 200 nm amorphous boron powder prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] Example 1:

[0036] See Figure 1 , Figure 1 This is a structural diagram of a self-propagating tunnel kiln device provided by an embodiment of the present invention. Figure 1 As shown, the self-propagating tunnel kiln device includes: an automatic feeding system 1, a self-propagating reaction section 2, a cooling section 3, a ventilation system, a pneumatic separation pressure relief valve 4, a multi-electrode igniter, a strong convection inert gas injection system 5 and a circulating cooling system 6. The automatic feeding system 1 is connected to the feeding end of the self-propagating reaction section 2. The discharge end of the self-propagating reaction section 2 is connected to the feeding end of the cooling section 3. The ventilation system is arranged in the self-propagating reaction section 2 and is connected to the self-propagating reaction section 2. The pneumatic separation pressure relief valve 4 is arranged on one side of the discharge end of the self-propagating reaction section 2, and the pneumatic separation pressure relief valve 4 connects the self-propagating reaction section 2 with the external environment. The multi-electrode igniter is arranged on the inner side of the bottom of the self-propagating reaction section. The strong convection inert gas injection system 5 is arranged around the outside of the cooling section 3 and is connected to the cooling section 3. The circulating cooling system 6 is arranged inside the cooling section 3. The inert gas includes one of argon and helium. Valves are provided at both ends of the self-propagating reaction section 2 and both ends of the cooling section 3.

[0037] The circulating cooling system 6 is an ice-brine circulating system, which is used to cool the cooling section 3 .

[0038] Specifically, the mixed material is transported by the automatic feeding system 1 to the SHP reaction section 2 in the SHP tunnel kiln for a SHP reduction reaction. The process is protected by an inert gas (argon, helium, etc.), effectively preventing oxidation of the mixed material. Specifically, the mixed material is ignited by a multi-electrode igniter and transported by the automatic feeding system 1 to the SHP reaction section 2 for a reduction reaction. During the reduction reaction in the SHP reaction section 2, the air pressure continuously increases. When the air pressure in the SHP reaction section 2 reaches a specified pressure, the pneumatic separation pressure relief valve 4 opens to automatically release the pressure.

[0039] In self-propagating reaction section 2, need to carry out gas replacement, specifically by ventilation system to realize.Cooling section 3 needs to carry out temperature treatment to material, specifically realizes (icy brine circulation) cooling by circulating cooling system 6, and adds strong convection inert gas (argon, helium etc.) by strong convection inert gas injection system 5 and carries out cooling atmosphere protection, avoids oxidation reaction.When surface material temperature is reduced to room temperature, release cooling section 3, carry out after-treatment after cooling and obtain amorphous boron powder.90 grades of amorphous boron powder can be obtained by this self-propagating tunnel kiln device.

[0040] The reduction reaction in SHR2 is closed, eliminating the issues of oxidation and pollution associated with open ignition in conventional SHR2. The reduction reaction in SHR2 does not require additional heating equipment; the mixture is ignited directly in SHR2 using a multi-electrode igniter, saving energy.

[0041] In an embodiment of the present invention, the ventilation system includes: a vacuum pumping device 7 and an inert gas charging device 8, wherein the vacuum pumping device 7 is arranged on the feed end side of the self-propagating reaction section 2 and is connected to the self-propagating reaction section 2; the inert gas charging device 8 is arranged on the outside of the self-propagating reaction section 2 and is connected to the self-propagating reaction section 2.

[0042] Specifically, the vacuum pumping device 7 is used to extract air from the SPR reaction section 2, thereby placing the SPR reaction section 2 in a vacuum state. The inert gas charging device 8 is used to charge the SPR reaction section 2 with an inert gas, such as argon or helium, to keep the material in the SPR reaction section 2 under an inert gas protection state throughout the entire process, thereby effectively preventing oxidation of the material.

[0043] In an embodiment of the present invention, the automatic feeding system 1 includes a starting feeding device and a plurality of material trays, and the starting feeding device is connected to the plurality of material trays.

[0044] Specifically, the starting feeding device is used to control the multiple material trays to be transported in the self-propagating reaction section 2 and the cooling section 3, so as to transport the mixed material to the self-propagating reaction section 2 and the cooling section 3. In this way, the mixed material can be automatically transported in the self-propagating reaction section 2 and the cooling section 3, thereby realizing automatic feeding.

[0045] In an embodiment of the present invention, the multi-electrode igniter includes: a first ignition electrode 9 and a second ignition electrode 10, the first ignition electrode 9 and the second ignition electrode 10 are both arranged on the inner side of the bottom of the self-propagating reaction section 2, and the first ignition electrode 9 and the second ignition electrode 10 are arranged side by side.

[0046] Specifically, the first ignition electrode 9 and the second ignition electrode 10 are used to ignite the mixed material in each tray so that the mixed material can react in the self-propagating reaction section 2 .

[0047] In the embodiment of the present invention, a waste gas collection device is further included, and the waste gas collection device is connected to the self-propagating reaction section 2.

[0048] Specifically, the waste gas collecting device is used to collect the waste gas discharged from the self-propagating reaction section 2 through the pneumatic separation pressure relief valve 4 and discharge it in an organized manner, thereby achieving environmental protection and avoiding environmental pollution.

[0049] In the embodiment of the present invention, the present invention has the following advantages:

[0050] 1. The self-propagating tunnel kiln has strong continuity and is suitable for industrial production. It can be doubled within a reasonable range. It does not use heating equipment, saving energy and solving the problems of easy oxidation and high pollution caused by the traditional self-propagating reduction open ignition.

[0051] 2. Continuous production, short cycle, large output and high quality.

[0052] 3. It works on the counter-current principle, so the heat utilization rate is high and the fuel is economical. Because the heat retention and waste heat utilization are very good, the fuel is very saved. Compared with the downdraft kiln, it can save about 50-60% of fuel.

[0053] 4. The self-propagation time is short, and the tunnel kiln can be completed in 5 minutes.

[0054] 5. Save labor. Not only is the operation simple, but the kiln loading and unloading operations are all carried out outside the kiln, which is also very convenient, improving the working conditions of the operators and reducing labor intensity.

[0055] 6. Improve quality. The temperatures of the preheating zone, firing zone, and cooling zone are usually kept within a certain range, making it easy to control the firing rules. As a result, the quality is better and the breakage rate is less.

[0056] 7. The kiln and kiln tools are durable. Because the kiln is not affected by rapid cooling and heating, the kiln body has a long service life and generally only needs to be repaired every 5-7 years.

[0057] 8. The physical and chemical indicators of the produced 90-grade amorphous boron powder meet the requirements of aerospace-grade amorphous boron powder. After simple modification, its compatibility with HTPB and bulk density are greatly improved, and it can be directly used in boron-rich fuel propellants.

[0058] 9. The produced grade 90 amorphous boron powder can also be used as an intermediate to produce grade 97 amorphous boron powder with higher content through chemical refining method.

[0059] Example 2:

[0060] The embodiment of the present invention provides a method for preparing amorphous boron powder, wherein the method adopts Figure 1 The self-propagating tunnel kiln device shown, the method for preparing amorphous boron powder includes the steps of:

[0061] S1. Mixing raw materials, boron oxide and magnesium powder, at a mass ratio of 1.3:1 in a grinding device under inert gas protection for 6 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium.

[0062] Among them, grinding equipment includes stirring, planetary and vibrating high-energy ball mills.

[0063] S2. After the mixing is completed, the obtained mixed material is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple trays of the automatic feeding system for multiple ventilation reactions. The height of each tray is 2 cm.

[0064] Among them, the automatic feeding system can be started by starting the automatic feeding button.

[0065] S3. Start the multi-electrode igniter to ignite each material tray and react for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, start the pneumatic separation pressure relief valve to release the pressure.

[0066] S4. Fill with inert gas, close the pneumatic separation pressure relief valve after the smoke disappears, open the cooling section feed valve connected to the self-propagating reaction stage, start the feeding device, control the material tray to enter the cooling section, close the cooling section feed valve, start the strong convection inert gas injection system, and quickly cool the material for 10 minutes. Then, open the cooling section discharge valve, start the automatic feeding device, and push the cooled material out of the cooling section.

[0067] S5. The cooled material is subjected to the first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 8 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. The mixture is stirred for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed.

[0068] S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

[0069] Specifically, by the method in Example 2, a total boron content of 91.5%, hydrogen peroxide insoluble matter of 0.31%, water-soluble boron of 0.26%, particle size of 13.69 μm, pH value of 8.1, and moisture of 0.25% can be obtained. The structure of amorphous boron powder is as follows Figure 2-4shown.

[0070] In an embodiment of the present invention, this method can produce Grade 90 amorphous boron powder. The physical and chemical properties of the Grade 90 amorphous boron powder produced by this method meet the requirements of aerospace-grade amorphous boron powder. After simple modification, its compatibility with HTPB and bulk density are significantly improved, and it can be directly used in boron-rich fuel propellants.

[0071] The 90-grade amorphous boron powder produced by the method can also be used as an intermediate to produce 97-grade amorphous boron powder with a higher content through a chemical refining method.

[0072] Example 3:

[0073] The embodiment of the present invention provides a method for preparing amorphous boron powder, wherein the method adopts Figure 1 The self-propagating tunnel kiln device shown, the method for preparing amorphous boron powder includes the steps of:

[0074] S1. Mixing raw materials, boron oxide and magnesium powder, at a mass ratio of 1.4:1 in a grinding device under an inert gas protection state for 6 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium.

[0075] Among them, grinding equipment includes stirring, planetary and vibrating high-energy ball mills.

[0076] S2. After the mixing is completed, the obtained mixed material is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple trays of the automatic feeding system for multiple ventilation reactions. The height of each tray is 2 cm.

[0077] Among them, the automatic feeding system can be started by starting the automatic feeding button.

[0078] S3. Start the multi-electrode igniter to ignite each material tray and react for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, start the pneumatic separation pressure relief valve to release the pressure.

[0079] S4. Fill with inert gas, close the pneumatic separation pressure relief valve after the smoke disappears, open the cooling section feed valve connected to the self-propagating reaction stage, start the feeding device, control the material tray to enter the cooling section, close the cooling section feed valve, start the strong convection inert gas injection system, and quickly cool the material for 10 minutes. Then, open the cooling section discharge valve, start the automatic feeding device, and push the cooled material out of the cooling section.

[0080] S5. The cooled material is subjected to the first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 6 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. The mixture is stirred for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed.

[0081] S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

[0082] Specifically, by the method in Example 2, a total boron content of 90.9%, a hydrogen peroxide insoluble matter of 0.28%, a water-soluble boron of 0.23%, a particle size of 12.69 μm, a pH value of 8.0, and a moisture content of 0.26% can be obtained.

[0083] In an embodiment of the present invention, this method can produce Grade 90 amorphous boron powder. The physical and chemical properties of the Grade 90 amorphous boron powder produced by this method meet the requirements of aerospace-grade amorphous boron powder. After simple modification, its compatibility with HTPB and bulk density are significantly improved, and it can be directly used in boron-rich fuel propellants.

[0084] The 90-grade amorphous boron powder produced by the method can also be used as an intermediate to produce 97-grade amorphous boron powder with a higher content through a chemical refining method.

[0085] Example 4:

[0086] The embodiment of the present invention provides a method for preparing amorphous boron powder, wherein the method adopts Figure 1 The self-propagating tunnel kiln device shown, the method for preparing amorphous boron powder includes the steps of:

[0087] S1. Mixing raw materials, boron oxide and magnesium powder, at a mass ratio of 1:1.3 in a grinding device under an inert gas protection state for 6 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium.

[0088] Among them, grinding equipment includes stirring, planetary and vibrating high-energy ball mills.

[0089] S2. After the mixing is completed, the obtained mixed material is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple trays of the automatic feeding system for multiple ventilation reactions. The height of each tray is 2 cm.

[0090] Among them, the automatic feeding system can be started by starting the automatic feeding button.

[0091] S3. Start the multi-electrode igniter to ignite each material tray and react for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, start the pneumatic separation pressure relief valve to release the pressure.

[0092] S4. Fill with inert gas, close the pneumatic separation pressure relief valve after the smoke disappears, open the cooling section feed valve connected to the self-propagating reaction stage, start the feeding device, control the material tray to enter the cooling section, close the cooling section feed valve, start the strong convection inert gas injection system, and quickly cool the material for 10 minutes. Then, open the cooling section discharge valve, start the automatic feeding device, and push the cooled material out of the cooling section.

[0093] S5. The cooled material is subjected to the first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 7.5 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. The mixture is stirred for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed.

[0094] S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

[0095] Specifically, by the method in Example 2, a total boron content of 91.3%, a hydrogen peroxide insoluble matter of 0.33%, a water-soluble boron of 0.27%, a particle size of 13.65 μm, a pH value of 8.3, and a moisture content of 0.31% can be obtained.

[0096] In an embodiment of the present invention, this method can produce Grade 90 amorphous boron powder. The physical and chemical properties of the Grade 90 amorphous boron powder produced by this method meet the requirements of aerospace-grade amorphous boron powder. After simple modification, its compatibility with HTPB and bulk density are significantly improved, and it can be directly used in boron-rich fuel propellants.

[0097] The 90-grade amorphous boron powder produced by the method can also be used as an intermediate to produce 97-grade amorphous boron powder with a higher content through a chemical refining method.

[0098] Example 5:

[0099] The embodiment of the present invention provides a method for preparing amorphous boron powder, wherein the method adopts Figure 1 The self-propagating tunnel kiln device shown, the method for preparing amorphous boron powder includes the steps of:

[0100] S1. Mixing raw materials, boron oxide and magnesium powder, at a mass ratio of 1:1.4 in a grinding device under inert gas protection for 6 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium.

[0101] Among them, grinding equipment includes stirring, planetary and vibrating high-energy ball mills.

[0102] S2. After the mixing is completed, the obtained mixed material is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple trays of the automatic feeding system for multiple ventilation reactions. The height of each tray is 2 cm.

[0103] Among them, the automatic feeding system can be started by starting the automatic feeding button.

[0104] S3. Start the multi-electrode igniter to ignite each material tray and react for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, start the pneumatic separation pressure relief valve to release the pressure.

[0105] S4. Fill with inert gas, close the pneumatic separation pressure relief valve after the smoke disappears, open the cooling section feed valve connected to the self-propagating reaction stage, start the feeding device, control the material tray to enter the cooling section, close the cooling section feed valve, start the strong convection inert gas injection system, and quickly cool the material for 10 minutes. Then, open the cooling section discharge valve, start the automatic feeding device, and push the cooled material out of the cooling section.

[0106] S5. The cooled material is subjected to the first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 7 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. Stir for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed.

[0107] S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

[0108] Specifically, by the method in Example 2, a total boron content of 91.1%, a hydrogen peroxide insoluble matter of 0.25%, a water-soluble boron of 0.31%, a particle size of 13.25 μm, a pH value of 8.1, and a moisture content of 0.34% can be obtained.

[0109] In an embodiment of the present invention, this method can produce Grade 90 amorphous boron powder. The physical and chemical properties of the Grade 90 amorphous boron powder produced by this method meet the requirements of aerospace-grade amorphous boron powder. After simple modification, its compatibility with HTPB and bulk density are significantly improved, and it can be directly used in boron-rich fuel propellants.

[0110] The 90-grade amorphous boron powder produced by the method can also be used as an intermediate to produce 97-grade amorphous boron powder with a higher content through a chemical refining method.

[0111] The above disclosure is merely a preferred embodiment of the present invention and certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A self-propagating tunnel kiln device, characterized in that: include: Automatic feeding system, self-propagating reaction section, cooling section, ventilation system, pneumatic separation pressure relief valve, multi-electrode igniter, strong convection inert gas injection system and circulating cooling system; The automatic feeding system is connected to the feeding end of the self-propagating reaction section; The discharge end of the self-propagating reaction section is connected to the feed end of the cooling section; The ventilation system is arranged in the self-propagating reaction section and is in communication with the self-propagating reaction section; The pneumatic separation pressure relief valve is arranged on one side of the discharge end of the self-propagating reaction section, and the pneumatic separation pressure relief valve connects the self-propagating reaction section with the external environment; The multi-electrode igniter is arranged on the inner side of the bottom of the self-propagating reaction section; The strong convection inert gas injection system is arranged around the outside of the cooling section and is in communication with the cooling section; The circulating cooling system is arranged inside the cooling section, and the circulating cooling system is an ice-salt water circulation system; The inert gas includes one of argon and helium, and valves are provided at both ends of the self-propagating reaction section and the cooling section; The multi-electrode igniter includes: a first ignition electrode and a second ignition electrode, wherein the first ignition electrode and the second ignition electrode are both arranged on the inner side of the bottom of the self-propagating reaction section, and the first ignition electrode and the second ignition electrode are arranged side by side; The self-propagating tunnel kiln device further includes a waste gas collecting device, which is communicated with the self-propagating reaction section.

2. The self-propagating tunnel kiln device according to claim 1, characterized in that: The ventilation system includes: a vacuum pumping device and an inert gas filling device, wherein the vacuum pumping device is arranged on the feed end side of the self-propagating reaction section and is connected to the self-propagating reaction section; the inert gas filling device is arranged on the outside of the self-propagating reaction section and is connected to the self-propagating reaction section.

3. The self-propagating tunnel kiln device according to claim 2, characterized in that: The automatic feeding system includes a starting feeding device and a plurality of feeding trays.

4. A method for preparing amorphous boron powder, the method being applied to the self-propagating tunnel kiln device according to any one of claims 1 to 3, characterized in that: The method comprises the steps of: S1. Mixing raw materials of boron oxide and magnesium powder in a mass ratio of 1:1.2-1:3.0 in a grinding device under an inert gas protection state for 5-10 hours to perform a mechanical alloying reaction, wherein the inert gas includes one of argon and helium; S2. After the mixing is completed, the obtained mixture is transported to the self-propagating reaction section of the self-propagating tunnel kiln device through multiple material trays of the automatic feeding system for multiple ventilation reactions; S3. Start the multi-electrode igniter to ignite each material tray. The reaction lasts for 5 seconds. The pressure in the self-propagating reaction section rises. When the pressure in the self-propagating reaction section reaches the set pressure, the pneumatic separation pressure relief valve is started to release the pressure. S4, filling with inert gas, closing the pneumatic separation pressure relief valve after the smoke disappears, opening the cooling section feed valve connected to the self-propagating reaction stage, starting the feeding device, controlling the material tray to enter the cooling section, closing the cooling section feed valve, starting the strong convection inert gas injection system, and rapidly cooling the material for 10 minutes, opening the cooling section discharge valve, starting the automatic feeding device, and pushing the cooled material out of the cooling section; S5. The cooled material is subjected to a first acid wash. For the first acid wash, dilute hydrochloric acid with a concentration of 3 mol / L-12 mol / L is added according to a solid-liquid mass ratio of 1:5 and heated to 90°C. The mixture is stirred for 2 hours. After stirring for 2 hours, deionized water of the same mass as the dilute hydrochloric acid is added dropwise at a uniform speed within 2 hours, and the first filter press is performed. S6. The wet material after the first filter press is subjected to a second acid wash, which is the same as the first acid wash, and then washed twice with deionized water, and then subjected to a second filter press, and vacuum dried at 80° C. to obtain amorphous boron powder.

5. The method for preparing amorphous boron powder according to claim 4, wherein: In S1, the mass ratio of the raw materials boron oxide and magnesium powder is 1.5:1.1, and the mixing time is 10 hours.

6. The method for preparing amorphous boron powder according to claim 5, wherein: In S2, the mixing height of the material tray is 2 cm.

7. The method for preparing amorphous boron powder according to claim 6, wherein: In S5, dilute hydrochloric acid is added at a concentration of 6 mol / L.

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