Atomization synthesizer for synthesizing silicon nitride micropowder by using crystal silicon slice waste mortar

Abstract

The invention relates to an atomization synthesizer for synthesizing silicon nitride micro powder by using crystal silicon slice waste mortar, which consists of an atomization reaction furnace 1, a quench cooler 2 and a gas-solid separator 3 which are fastened and connected into a whole device through flanges, gaskets and bolts, the atomization reaction furnace 1 consists of a pressure-bearing shell 1.1, a hearth 1.2 and a thermal insulation layer 1.3, and the gas-solid separator 3 consists of a gas-solid separator 2 and a gas-solid separator 3. The quench cooler is composed of a jacket quench cooler 2.1, a supporting tower section 2.2, a concave flange plate 3.3, an aggregate ceramic taper pipe 2.4, a pressure-bearing taper shell 2.5, a thermal insulation material 2.6 and a convex flange 2.7; the gas-solid separator 3 is composed of a stock bin 3.1, a filter 3.2, a water cooling jacket 3.3 and a tower base 3.4. The method comprises the following steps: atomizing and spraying Si and N2 into a reaction furnace according to a molecular ratio of 1: 1-1: 2, reacting under the conditions of 1000-1450 DEG C and 0.1-0.6 MPa to synthesize silicon nitride, feeding the silicon nitride and residual reaction nitrogen into a quench cooler 2, exchanging heat with raw material nitrogen, quenching and cooling, simultaneously preheating the raw material nitrogen, feeding a quenched reaction product into a gas-solid separator 3, naturally settling, and filtering by a filter element 3.2 to realize gas-solid separation, nitrogen is discharged, and the solid silicon nitride micro powder is left in the stock bin 3.1.

Description

Technical Field

[0001] The invention relates to an atomizing synthesizer for synthesizing silicon nitride micropowder by using waste mortar of crystalline silicon slices, and belongs to the field of comprehensive utilization of photovoltaic crystalline silicon slice waste and silicon nitride powder production equipment. Background Art

[0002] Silicon nitride is an advanced engineering ceramic material with high room temperature and high temperature strength, high hardness, abrasion resistance, oxidation resistance, and good resistance to thermal shock and mechanical shock. It is considered by the materials science community to be a new material with excellent comprehensive performance in the field of structural ceramics and the most promising alternative to nickel-based alloys for wide application in high-tech and high-temperature fields.

[0003] The synthesis process of silicon nitride powder is generally:

[0004] Silicon powder direct nitridation 3Si(s)+2N2(g)=Si3N4(s)

[0005] Silicylimine gas phase reaction 3SiCl4(g)+4NH3(g)=Si3N4(s)+12HCl(g)

[0006] Carbon thermal reduction nitridation 3SiO2(s)+6C(s)+2N2(g)=Si3N4(s)+6CO(g)

[0007] Among them, direct nitridation of silicon powder is the earliest developed process for preparing silicon nitride powder and is also the most widely used method at present. This method is to load the raw silicon powder into a sagger and place it in a reaction furnace. First, the gas in the furnace is replaced, nitrogen is introduced to heat it, and argon is added to control the reaction rate to prevent the silicon powder from reacting rapidly and overheating to melt and form balls, causing the reaction to terminate. Until the silicon powder no longer absorbs nitrogen, the furnace is stopped to cool down and the furnace is taken out. The production cycle of a single furnace is about one week, and the output is 80-200kg / furnace. The product is in granular form and must undergo subsequent processing to obtain silicon nitride powder material. It is an intermittent production process with a long reaction cycle, high energy consumption, and poor quality reliability.

[0008] Since 2006, the applicant has been concerned about the treatment of waste mortar from crystalline silicon processing for photovoltaic cells. On April 22, 2011, an invention patent application for "New Method for Comprehensive Treatment of Waste Mortar from Crystalline Silicon Processing for Photovoltaic Cells" with application number 201110101064.7 was filed. On August 12, 2011, an invention patent application for "Comprehensive Treatment Technology for Waste Mortar from Photovoltaic Crystalline Silicon Processing" with application number 201110238197.9 was filed; on June 26, 2012, an invention patent application for "Comprehensive Treatment Technology for Waste Mortar from Crystalline Silicon Processing without Sewage and Solid Waste Discharge" with application number 201210207989.4 was filed with the priority of the application number 201110238197.9 "Comprehensive Treatment Technology for Waste Mortar from Photovoltaic Crystalline Silicon Processing", and the patent right was obtained on May 20, 2015. On January 23, 2013, a patent application for "Entrained Flow Reactor for Recycling Silicon Powder from Waste Mortar of Crystalline Silicon Processing to Prepare Silicon Nitride Powder" with application number 201310024132.3 was filed, and the patent right was obtained on November 19, 2014.

[0009] When the above patent applications were initially filed, the multi-wire cutting process was commonly used in the field of photovoltaic crystalline silicon slicing. The waste mortar generated during the crystalline silicon slicing process was a mixed slurry of four systems: silicon material chips - Si, cutting wire abrasion debris - Fe, ineffective abrasives - SiC, and cutting fluid - polyethylene glycol; now, solar photovoltaic crystalline silicon slicing has been completely replaced by the new diamond wire cutting process, and the waste mortar generated during the crystalline silicon slicing process has become a mixed slurry of three systems: silicon material chips - Si, coolant high-purity water, and trace diamond chips. After dehydration and drying, high-purity ultrafine silicon powder with a particle size of 0 - 8 μm and a silicon content of more than 99.5% can be obtained, which is used as a raw material for producing silicon nitride powder. However, this silicon powder is too fine to produce silicon nitride by traditional nitriding processes, and a new method must be used. Summary of the Invention

[0010] The object of the present invention is to adapt to the new process and new problems of current photovoltaic crystalline silicon slicing, and provide an atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slicing.

[0011] The object of the present invention is achieved as follows: The atomization synthesizer consists of an atomization reaction furnace (1), a quench cooler (2), and a gas-solid separator (3), which are connected into one body by flanges and bolts; the housing (1.1) of the atomization reaction furnace (1) is a pressure-bearing component, the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, and it is lined with silicon nitride-bonded silicon carbide refractory material, and the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing housing (1.1); the quench cooler (2) consists of a jacket quench cooler (2.1), tower sections (2.2), concave flange plates (2.3), convex flanges (2.4), pressure-bearing conical housings (2.5), aggregate ceramic cone tubes (2.6), and insulation materials (2.7). The tower sections do not bear pressure. The concave flange plates are bolted to the convex flanges of the atomization reaction furnace housing. The aggregate ceramic cone tube (2.6) is installed at the center of the concave flange plate of the tower section to receive the reaction products coming down from the furnace chamber and introduce them into the inner cavity of the jacket quench cooler (2.1) to exchange heat with the raw material nitrogen in the jacket; the gas-solid separator (3) consists of a silo (3.1), a filter (microporous ceramic filter element or dust removal cloth bag) (3.2), and a tower base (3.4). When the raw material nitrogen is self-made nitrogen, due to its insufficient heat exchange capacity, a water-cooled jacket (3.3) is added inside the gas-solid separator to further reduce the temperature of the reaction products. When liquid nitrogen is used, the temperature of the reaction products in the quench cooler can be reduced to below 150°C, and the gas-solid separator does not have a water-cooled jacket; at the top of the atomization synthesizer, there is a plasma spray gun installation flange A, at the bottom there is a product (Si3N4) outlet B, on the body there are raw material (Si + N2) inlets C, observation sight glasses D, pressure measurement and explosion-proof interfaces F, temperature measurement holes E1 - E6, a quench cooler nitrogen inlet N1, a preheated nitrogen outlet N2, a gas-solid separator discharged nitrogen outlet N3, a cooling water inlet S1, and a cooling water outlet S2; its working principle is: The (N2 + Si) atomized fluid output from the silicon powder preheating atomizer is sprayed into the atomization reaction furnace along the raw material inlet C. The raw material inlet pipe is sprayed upward at 45°. The atomized fluid reaches the center position of the nitrogen plasma flame ejected by the plasma spray gun inserted from the top A of the atomization synthesizer to trigger the reaction. Under the conditions of a pressure of 0 - 0.5 MPa, a temperature of 1000 - 1450°C, and an excess of N2, nano-silicon nitride (Si3N4) is continuously generated by reaction in the atomized state. Together with the remaining nitrogen, it forms a high-temperature (Si3N4 + N2) mixed mist fluid, which enters the inner cavity of the quench cooler and exchanges heat with the raw material nitrogen entering from the quench cooler nitrogen inlet N1 of the jacket, and is quickly cooled to below 400°C to solidify the silicon nitride crystal phase and particle size, eliminating the crystal phase change and particle growth caused by high temperature, and generating nano-silicon nitride micropowder. At the same time, the raw material nitrogen exchanges heat and heats up to above 600°C and is discharged from the N2 pipe orifice; the temperature of the reaction product (Si3N4 + N2) mixed mist fluid after being quenched by self-made nitrogen is close to 400°C, which is connected to the gas-solid separator (3) and enters the water-cooled jacket (3.3). After further cooling and temperature reduction, the temperature of the (Si3N4 + N2) mixture drops to about 150°C, and N2 passes through the filter (3.2) It is discharged from N3. Si3N4 settles and is filtered, staying in the silo, and then transferred to metering and packaging for storage as finished silicon nitride products; the temperature of the (Si3N4 + N2) mixture after being rapidly cooled by liquid nitrogen is about 150°C. It is inserted into the gas-solid separator (3), and N2 passes through the filter (3.2) and is discharged from N3. Si3N4 settles and is filtered, staying in the silo, and then transferred to metering and packaging for storage as finished silicon nitride products; the process temperature during production is measured and controlled through the temperature measurement holes E1 - E6. The silicon nitride reaction situation in the atomization reaction furnace is observed through the observation mirror D. The furnace pressure and safety discharge are measured and controlled through the pressure measurement and explosion-proof interface F, pipeline, pressure gauge, and safety valve.

[0012] The shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing part and is designed and manufactured in accordance with the relevant standards and specifications of pressure vessels; the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, and the working temperature is 1000 - 1450°C. It is lined with silicon nitride-bonded silicon carbide refractory material added with 0.01 - 0.5% rare earth material, which has a nitrogen catalytic effect; the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1) to make the surface temperature of the shell (1.1) lower than 60°C; at the top of the atomization synthesizer, there are installed a plasma spray gun mounting flange A, an inlet C for the atomization nozzle of the raw material (Si + N2), an observation mirror D, a pressure measurement and explosion-proof interface F, and temperature measurement holes E1 - E3. Among them, the atomization holes C are evenly distributed along the furnace body according to production requirements at 2 - 8 holes, inclined upward at 10 - 45°, so that the sprayed atomized raw materials have an upward inclined trend and intersect with 1 / 2 of the length of the nitrogen plasma flame sprayed from the furnace top to optimize the reaction conditions and extend the residence time of silicon powder in the atomization reaction furnace.

[0013] In the jacketed quencher (2.1) of the quencher (2), the high-temperature reaction product (Si3N4 + N2) mixture passes through the center, and the raw material nitrogen passes through the jacket layer. Spiral guide plates are arranged in the jacket to enhance heat transfer.

[0014] The filter (3.2) of the gas-solid separator (3) is a titanium alloy microporous sintered filter element.

[0015] The filter (3.2) of the gas-solid separator (3) is a nylon filter cloth filter.

[0016] When using self-made nitrogen as the atomization synthesis nitrogen raw material, a water-cooled jacket (3.3) is added inside the gas-solid separator (3) to solve the problem of poor heat exchange in the rapid cooling of normal-temperature nitrogen.

[0017] When using liquid nitrogen as the atomization synthesis nitrogen raw material, no water-cooled jacket is provided inside the gas-solid separator (3).

[0018] The invention will be further described below in conjunction with the drawings and embodiments. Description of the Drawings

[0019] The numbers in the figure represent the processing of equipment components, and the letters represent the process pipe openings.

[0020] Figure 1 It is the structure diagram of the atomization synthesizer.

[0021] Figure 2 It is the external view of the atomization synthesizer.

[0022] Figure 3 It is the structure diagram of the reaction furnace of the atomization synthesizer.

[0023] Figure 4 It is the top view of the reaction furnace cover of the atomization synthesizer.

[0024] Figure 5 It is the structure diagram of the observation hole D, temperature measurement hole E, and safety valve interface F of the reaction furnace of the atomization synthesizer

[0025] Figure 6 It is the cross-sectional view of the raw material atomization nozzle of the reaction furnace of the atomization synthesizer.

[0026] Figure 7 It is the structure diagram of the quench cooler of the atomization synthesizer.

[0027] Figure 8 It is the top view of the quench cooler of the atomization synthesizer.

[0028] Figure 9 It is the cross-sectional view of the quench cooler of the atomization synthesizer.

[0029] Figure 10 It is the structure diagram of the gas-solid separator of the atomization synthesizer using self-made nitrogen as the nitrogen source.

[0030] Figure 11 It is the half cross-sectional view of the gas-solid separator using self-made nitrogen as the nitrogen source.

[0031] Figure 12 It is the cross-sectional view of the gas-solid separator using self-made nitrogen as the nitrogen source.

[0032] Figure 13 It is the structure diagram of the gas-solid separator of the atomization synthesizer using liquid nitrogen as the nitrogen source.

[0033] Figure 14 It is the half cross-sectional view of the gas-solid separator using liquid nitrogen as the nitrogen source.

[0034] Figure 15 It is the cross-sectional view of the gas-solid separator using liquid nitrogen as the nitrogen source.

[0035] The numbers in the figure represent the structure of the atomization synthesizer: 1 - atomization reaction furnace, 2 - quench cooler, 3 - gas-solid separator; 1.1 - atomization reaction furnace shell, 1.2 - atomization reaction furnace hearth, 1.3 - atomization reaction furnace insulation layer; 2.1 - jacketed quench cooler, 2.2 - quench cooler tower base, 2.3 - concave flange plate, 2.4 - convex flange, 2.5 pressure-bearing conical shell, 2.6 aggregate ceramic conical tube, 2.7 thermal insulation material; 3.1 - bin, 3.2 - filter (microporous ceramic filter element or dust removal cloth bag), 3.3 - water-cooled jacket, 3.4 - tower base.

[0036] The letters in the figure represent the process hole numbers: A - plasma spray gun installation flange, B - product (Si3N4) outlet, C - raw material (Si + N2) inlet, D - observation sight glass, F - pressure measurement and explosion-proof safety valve interface, E1 - E6 - temperature measurement holes, N1 - quench nitrogen interface, N2 - preheated nitrogen outlet, N3 - gas-solid separation nitrogen outlet, S1 - cooling water inlet, S2 - cooling water outlet, G1 - reaction furnace reaction product (Si3N4 + N2), G2 - quench cooler (Si3N4 + N2) inlet, G3 - quench cooler (Si3N4 + N2) outlet, G4 - gas-solid separator (Si3N4 + N2) inlet, G1 / G2 are paired, G3 / G4 are paired, which are the equipment installation socket and spigot. Specific embodiments

[0037] The following are specific embodiments of the present invention, but the method of the present invention is not completely limited thereto, and those skilled in the art can change or adjust the structure therein as needed.

[0038] Example 1:

[0039] Figures 1 - 12The atomization synthesizer shown is an atomization synthesizer using self-made nitrogen as the reaction raw material, which consists of three parts: an atomization reaction furnace (1), a quench cooler (2), and a gas-solid separator (3), and is connected into one body through flanges and bolts; the shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing part, the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, and the heat insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1); the quench cooler (2) consists of a jacket quench cooler (2.1), a tower section (2.2), a concave flange plate (2.3), a convex flange (2.4), a pressure-bearing conical shell (2.5), an aggregate ceramic conical tube (2.6), and a heat insulation material (2.7). The tower section is not pressure-bearing. The concave flange plate is bolted to the convex flange of the atomization reaction furnace shell. The aggregate ceramic conical tube (2.6) is installed at the center of the concave flange plate of the tower section to receive the reaction products coming down from the furnace chamber and introduce them into the inner cavity of the jacket quench cooler (2.1) to exchange heat with the raw material nitrogen in the jacket; the gas-solid separator (3) consists of a bin (3.1), a filter (microporous ceramic filter element or dust removal cloth bag) (3.2), a water-cooled jacket (3.3), and a tower base (3.4). At the top of the atomization synthesizer, there is a plasma spray gun installation flange A, at the bottom there is a product (Si3N4) outlet B, on the body there are a raw material (Si + N2) inlet C, an observation sight glass D, a pressure measurement and explosion-proof interface F, temperature measurement holes E1 - E6, a quench cooler nitrogen interface N1, a preheated nitrogen outlet N2, a gas-solid separator discharged nitrogen outlet N3, a cooling water inlet S1, and a cooling water outlet S2; its working principle is as follows: the (N2 + Si) atomized fluid output from the silicon powder preheating atomizer is sprayed into the atomization reaction furnace along the raw material inlet C. The raw material inlet pipe is sprayed upward at 45°. The atomized flow reaches the center position of the nitrogen plasma flame ejected by the plasma spray gun inserted from the top A of the atomization synthesizer, triggering the reaction. Under the conditions of a pressure of 0 - 0.5 MPa, a temperature of 1000 - 1450 °C, and an excess of N2, nanosilicon nitride (Si3N4) is continuously generated in the atomized state, and together with the remaining nitrogen, it forms a high-temperature (Si3N4 + N2) misty fluid, which enters the inner cavity of the quench cooler and exchanges heat with the raw material nitrogen entering from the quench cooler nitrogen interface N1 of the jacket, and is quickly cooled to below 400 °C to solidify the Si3N4 crystal phase and particle size, eliminating the crystal phase change and particle growth caused by high temperature, generating Si3N4 nanoparticles. At the same time, the raw material nitrogen exchanges heat and heats up to above 600 °C and is discharged from the N2 pipe orifice; it is connected to the gas-solid separator (3) and enters the water-cooled jacket (3.3). After further cooling and temperature reduction, the temperature of the (Si3N4 + N2) mixture drops to about 150 °C. N2 passes through the filter (3.2) and is discharged from N3, and Si3N4 settles and is filtered and retained in the bin, and then is transferred to metering and packaging and stored in the warehouse as the finished silicon nitride product; the process temperature during the production process is measured and controlled through the temperature measurement holes E1 - E6. The silicon-nitrogen reaction situation in the atomization reaction furnace is observed through the observation sight glass D. The pressure in the furnace and the safety discharge are led out through the pressure measurement and explosion-proof interface F to the pipeline, pressure gauge, and safety valve for measurement and control.

[0040] The shell (1.1) of the atomization reaction furnace (1) therein is a pressure-bearing component and is designed and manufactured in accordance with relevant standards and specifications of pressure vessels; the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, and the working temperature is 1000 - 1450 °C. It is lined with silicon nitride bonded silicon carbide refractory material added with 0.01 - 0.5% rare earth material and has a nitrogen catalytic effect; the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1) to make the surface temperature of the shell (1.1) lower than 60 °C; at the top of the atomization synthesizer, there are plasma spray gun mounting flange A, raw material (Si + N2) atomizing nozzle inlet C, observation sight glass D, pressure measurement and explosion-proof interface F, and temperature measurement holes E1 - E3. Among them, according to production requirements, the raw material inlet C is evenly distributed along the furnace body in 4 holes on the atomization reaction furnace, tilted upward at 45°, so that the sprayed atomized raw material has an upward tilt trend and intersects with 1 / 2 of the length of the nitrogen plasma flame sprayed from the furnace top to optimize the reaction conditions and extend the residence time of silicon powder in the atomization reaction furnace.

[0041] In the jacketed quench cooler (2.1) of the quench cooler (2), the high-temperature reaction product (Si3N4 + N2) mixture passes through the center, and raw material nitrogen passes through the jacket layer. Spiral guide plates are arranged in the jacket to strengthen heat transfer.

[0042] The filter (3.2) of the gas-solid separator (3) is a titanium alloy microporous sintered filter element; a water-cooled jacket (3.3) is arranged inside to solve the problem of poor self-made nitrogen quench heat transfer effect.

[0043] Example 2:

[0044] Such as Figures 1 - 9 、 Figures 13 - 15The atomization synthesizer shown is an atomization synthesizer with liquid nitrogen as the reaction nitrogen source, which consists of three parts: an atomization reaction furnace (1), a quench cooler (2), and a gas-solid separator (3), and is connected as a whole by flanges and bolts; the shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing part, and the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, lined with silicon nitride-bonded silicon carbide material, and the thermal insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1); the quench cooler (2) consists of a jacket quench cooler (2.1), a tower section (2.2), a concave flange plate (2.3), a convex flange (2.4), a pressure-bearing conical shell (2.5), an aggregate ceramic cone tube (2.6), and a thermal insulation material (2.7). The tower section is not pressure-bearing. The concave flange plate is bolted to the convex flange of the atomization reaction furnace shell. The aggregate ceramic cone tube (2.6) is installed at the center of the concave flange plate of the tower section to receive the reaction products coming down from the furnace chamber and introduce them into the inner cavity of the jacket quench cooler (2.1) to exchange heat with the raw material nitrogen in the jacket; the gas-solid separator (3) consists of a silo (3.1), a filter (3.2), and a tower base (3.4); at the top of the atomization synthesizer, there are installed a plasma spray gun mounting flange A, a raw material (Si + N2) inlet C, an observation sight glass D, a pressure measurement and explosion-proof interface F, temperature measurement holes E1 - E6, a quench cooler nitrogen inlet N1, a preheated nitrogen outlet N2, a gas-solid separator discharged nitrogen outlet N3, and a product (Si3N4) outlet B; its working principle is: the (N2 + Si) atomized fluid output from the silicon powder preheating atomizer is sprayed into the atomization reaction furnace along the raw material inlet C. The atomized flow sprayed upward at 45° from the raw material inlet pipe reaches the center position of the nitrogen plasma flame ejected by the plasma spray gun inserted from the top A of the atomization synthesizer, triggering the reaction. Under the conditions of a pressure of 0 - 0.5 MPa, a temperature of 1000 - 1450 °C, and an excess of N2, nano-silicon nitride (Si3N4) is continuously generated, and together with the remaining nitrogen, it forms a high-temperature (Si3N4 + N2) mixture, which enters the inner cavity of the quench cooler and exchanges heat with the low-temperature nitrogen gas vaporized from the liquid nitrogen entering the jacket quench cooler (2.1) from the nitrogen inlet N1, and is quenched to below 150 °C to solidify the Si3N4 crystal phase and particle size, eliminating the crystal phase change and particle growth caused by high temperature, generating nano-Si3N4 particles. At the same time, the raw material nitrogen exchanges heat and heats up to above 600 °C and is discharged from the N2 pipe orifice; the temperature of the quenched (Si3N4 + N2) mixture is about 150 °C and is inserted into the gas-solid separator (3). N2 passes through the filter (3.2) and is discharged from N3, and Si3N4 settles and is filtered and retained in the silo, and then is transferred to metering and packaging and stored in the warehouse as the finished silicon nitride product; the process temperature during the production process is measured and controlled through the temperature measurement holes E1 - E6, the silicon-nitrogen reaction situation in the atomization reaction furnace is observed through the observation sight glass D, and the furnace pressure and safety discharge are led out through the pressure measurement and explosion-proof interface F to the pipeline, pressure gauge, and safety valve for measurement and control.

[0045] The shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing component and is designed and manufactured in accordance with relevant standards and specifications for pressure vessels; the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, and the working temperature is 1000 - 1450 °C. It is lined with silicon nitride bonded silicon carbide refractory material added with 0.01 - 0.5% rare earth material and has a nitrogen catalytic effect; the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1) to keep the surface temperature of the shell (1.1) below 60 °C; at the top of the atomization synthesizer, there are plasma spray gun mounting flange A, raw material (Si + N2) inlet C, observation sight glass D, pressure measurement and explosion-proof interface F, and temperature measurement holes E1 - E3. Among them, the raw material inlet C is evenly distributed along the furnace body in 4 holes according to production requirements and is inclined upward at 45°, so that the sprayed atomized raw material has an upward inclined trend and intersects with 1 / 2 of the length of the nitrogen plasma flame sprayed from the furnace top to optimize the reaction conditions and extend the residence time of the silicon powder in the atomization reaction furnace.

[0046] In the jacketed quench cooler (2.1) of the quench cooler (2), the high-temperature reaction product (Si3N4 + N2) mixture passes through the center, and the raw material nitrogen passes through the jacket layer. Spiral guide plates are arranged in the jacket to strengthen heat transfer.

[0047] The filter (3.2) of the gas-solid separator (3) is a polyamide filter cloth filter.

Claims

1. An atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slices, characterized in that: The atomization synthesizer consists of three parts: an atomization reaction furnace (1), a quencher (2), and a gas-solid separator (3), which are connected into one body by flanges and bolts; the shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing component, and the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, which is lined with silicon nitride-bonded silicon carbide refractory material, and the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1); the quencher (2) consists of a jacket quencher (2.1), a tower section (2.2), a concave flange plate (2.3), a convex flange (2.4), a pressure-bearing conical shell (2.5), an aggregate ceramic cone tube (2.6), and an insulation material (2.7). The tower section is not pressure-bearing. The concave flange plate is bolted to the convex flange of the atomization reaction furnace shell. The aggregate ceramic cone tube (2.6) is installed at the center of the concave flange plate of the tower section to receive the reaction products coming down from the furnace chamber and introduce them into the inner cavity of the jacket quencher (2.1) to exchange heat with the raw material nitrogen in the jacket; the gas-solid separator (3) consists of a bin (3.1), a filter (microporous ceramic filter element or dust removal cloth bag) (3.2), and a tower base (3.4). When the raw material nitrogen is self-made nitrogen, due to its insufficient heat exchange capacity, a water-cooled jacket (3.3) is added inside the gas-solid separator to further reduce the temperature of the reaction products. When liquid nitrogen is used, the temperature of the reaction products in the quencher can be reduced to below 150°C, and the gas-solid separator does not have a water-cooled jacket; at the top of the atomization synthesizer, there is a plasma spray gun mounting flange A, at the bottom there is a product (Si3N4) outlet B, on the body there are a raw material (Si + N2) inlet C, an observation sight glass D, a pressure measurement and explosion-proof interface F, temperature measurement holes E1 - E6, a quencher nitrogen interface N1, a preheated nitrogen outlet N2, a gas-solid separator discharged nitrogen outlet N3, a cooling water inlet S1, and a cooling water outlet S2; its working principle is: the (N2 + Si) atomized fluid output from the silicon powder preheating atomizer is sprayed into the atomization reaction furnace along the raw material inlet C, and the raw material inlet pipe is sprayed upward at 45°. The atomized fluid reaches the center position of the nitrogen plasma flame ejected by the plasma spray gun inserted from the top A of the atomization synthesizer to trigger the reaction. Under the conditions of a pressure of 0 - 0.5 MPa, a temperature of 1000 - 1450°C, and an excess of N2, nano-silicon nitride (Si3N4) is continuously generated by reaction in the atomized state, and together with the remaining nitrogen, it forms a high-temperature (Si3N4 + N2) mixed misty fluid, which enters the inner cavity of the quencher and exchanges heat with the raw material nitrogen entering from the quencher nitrogen interface N1 of the jacket quencher, and is quickly cooled to below 400°C to solidify the silicon nitride crystal phase and particle size, eliminating the crystal phase change and particle growth caused by high temperature, generating nano-silicon nitride micro-powder. At the same time, the raw material nitrogen exchanges heat and warms up to above 600°C and is discharged from the N2 pipe orifice; the temperature of the reaction product (Si3N4 + N2) mixed misty fluid after quenching with self-made nitrogen is close to 400°C, which is connected to the gas-solid separator (3), enters the water-cooled jacket (3.3), and after further cooling and temperature reduction, the temperature of the (Si3N4 + N2) mixture drops to about 150°C, and N2 passes through the filter (3.2) Discharged from N3, Si3N4 settles and is filtered, remaining in the silo, then transferred for metering and packaging and stored in the warehouse as finished silicon nitride products; the temperature of the (Si3N4 + N2) mixture after rapid cooling with liquid nitrogen is around 150 °C. Inserted into the gas-solid separator (3), N2 passes through the filter (3.2) and is discharged from N3, while Si3N4 settles and is filtered, remaining in the silo, then transferred for metering and packaging and stored in the warehouse as finished silicon nitride products; the process temperature during production is measured and controlled through the temperature measurement holes E1 - E6, the silicon nitride reaction situation in the atomization reaction furnace is observed through the observation sight glass D, and the furnace pressure and safety discharge are measured and controlled through the pressure measurement and explosion-proof interface F leading to pipelines, pressure gauges, and safety valves.

2. The atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slicing according to claim 1, characterized in that: The shell (1.1) of the atomization reaction furnace (1) is a pressure-bearing component and is designed and manufactured in accordance with relevant standards and specifications for pressure vessels; the aspect ratio of the furnace chamber (1.2) is 5:1 - 40:1, the working temperature is 1000 - 1450 °C, and it is lined with silicon nitride bonded silicon carbide refractory material added with 0.01 - 0.5% rare earth material, with the catalytic effect of nitrogen; the insulation layer (1.3) is filled between the furnace chamber (1.2) and the pressure-bearing shell (1.1) to make the surface temperature of the shell (1.1) lower than 60 °C; at the top of the atomization synthesizer, there are a plasma spray gun installation flange A, a raw material (Si + N2) atomization nozzle inlet C, an observation sight glass D, a pressure measurement and explosion-proof interface F, and temperature measurement holes E1 - E3. Among them, the atomization nozzle C is evenly distributed along the furnace body with 2 - 8 holes according to production requirements and is inclined upward at 10 - 45°, so that the injected atomized raw material has an upward inclination trend and intersects with 1 / 2 of the length of the nitrogen plasma flame sprayed from the furnace top to optimize the reaction conditions and extend the residence time of the silicon powder in the atomization reaction furnace.

3. The atomization synthesizer for synthesizing silicon nitride micropowder using waste mortar from slicing monocrystalline silicon as claimed in claim 1, characterized in that: In the jacketed quencher (2.1) of the quencher (2), the high-temperature reaction product (Si3N4 + N2) mixture passes through the center, and the raw material nitrogen passes through the jacket layer. A spiral baffle is arranged in the jacket to strengthen heat transfer.

4. The atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slices according to claim 1, characterized in that: The filter (3.2) of the gas-solid separator (3) is a titanium alloy microporous sintered filter element.

5. The atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slices according to claim 1, characterized in that: The filter (3.2) of the gas-solid separator (3) is a nylon filter cloth filter.

6. The atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slicing according to claim 1, characterized in that: When using self-made nitrogen as the atomization synthesis nitrogen raw material, a water-cooled jacket (3.3) is added inside the gas-solid separator (3) to solve the problem of poor quenching heat transfer effect of normal-temperature nitrogen.

7. The atomization synthesizer for synthesizing silicon nitride micropowder from waste mortar of crystalline silicon slicing according to claim 1, characterized in that: When using liquid nitrogen as the atomization synthesis nitrogen raw material, no water-cooled jacket is provided inside the gas-solid separator (3).

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