Method for producing industrial silicon and industrial silicon production system

Abstract

The application discloses a method for producing industrial silicon and an industrial silicon production system, and the method comprises the following steps: 1) hydrogen is introduced into silicon dioxide, and heating reaction is carried out to generate silicon monoxide and water; and 2) hydrogen plasma is formed by ionizing hydrogen through a plasma generator, and the silicon monoxide reacts with the hydrogen plasma to generate silicon. The method uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in the prior art, and the tail gas of the reaction is basically free of other components except hydrogen and water vapor, and the hydrogen and water vapor can be recycled, so that the greenhouse gas emission amount in the industrial silicon production process is significantly reduced, and the method is a green and environment-friendly industrial silicon production process. Gaseous silicon monoxide is generated by the reaction of silica and hydrogen, and the reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid reaction. In the production of elemental silicon, the hydrogen is converted into hydrogen plasma by using a plasma process, so that the reducing property of the hydrogen is further improved, and the silicon element can be obtained without being in a high-temperature and high-pressure environment.

Description

Technical Field

[0001] This invention belongs to the field of industrial silicon production technology, specifically relating to a method and system for producing industrial silicon. Background Technology

[0002] Industrial silicon, as a core raw material in fields such as organosilicon, photovoltaics, and silicon alloys, plays a vital role in my country's economic and social development. Currently, industrial silicon production involves heating silica and a carbon-based reducing agent in an electric arc furnace. The silica is reduced by the carbon-based reducing agent to produce liquid industrial silicon and carbon monoxide (CO) gas, with the CO gas escaping through the material layer. Simultaneously, a mixture of oxygen and air is introduced at the bottom of the silicon bath to remove other impurities such as calcium and aluminum. The liquid industrial silicon is then cast into ingots, crushed, and graded to obtain the finished product.

[0003] Producing one ton of industrial silicon requires approximately 2.7-3 tons of silica, 2-2.5 tons of carbon-based reducing agent, and 0.08-0.13 tons of graphite electrodes, consuming 12,000-15,000 kilowatt-hours of electricity. Therefore, industrial silicon is a high-energy-consuming and high-carbon-emission industry. When industrial silicon production uses hydropower as its energy source, the carbon emission per ton is 5.32 tons of CO2 equivalent, while when using thermal power as its energy source, the carbon emission per ton reaches 15.91 tons of CO2 equivalent.

[0004] The pressure to control carbon dioxide emissions during industrial silicon production is increasing year by year. Currently, industrial silicon production is heavily reliant on carbon-based reducing agents, making it difficult to achieve emission reduction targets. The steel industry faces similar challenges, and using hydrogen instead of carbon-based reducing agents to reduce carbon dioxide emissions has become a new development direction in the steel metallurgy sector. However, compared to metal oxides, silicon dioxide is more stable. At high temperatures (>1200℃), the reaction product of hydrogen reducing silicon dioxide is silicon monoxide. The conditions for direct reduction to elemental silicon are extremely demanding, with a theoretical reaction temperature exceeding 4500℃, making it difficult to achieve in industrial applications. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the above-mentioned shortcomings of the prior art by providing a method and system for producing industrial silicon. In view of the disadvantages of high energy consumption and large carbon emissions in the existing industrial silicon production technology, the method of the present invention can significantly reduce carbon dioxide emissions in the production process. At the same time, the present invention produces no other by-products except water, and the water can be used for electrolysis to produce hydrogen and recycled, which is a near-zero emission industrial silicon production method.

[0006] The technical solution adopted to solve the technical problem of this invention is to provide a method for producing industrial silicon, comprising the following steps:

[0007] 1) Hydrogen gas is introduced into silicon dioxide and heated to react, producing silicon suboxide and water;

[0008] 2) Hydrogen gas is ionized by a plasma generator to form hydrogen plasma, and silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0009] Preferably, the heating temperature in step 1) is 1200–1700°C.

[0010] Preferably, the particle size of silica in step 1) does not exceed 10 mm.

[0011] Preferably, the flow rate of hydrogen gas introduced in step 1) is 1-100000 Nm³. 3 / h.

[0012] Preferably, the power of the plasma generator in step 2) is 0.1-4MW.

[0013] The present invention also provides a system for the above-described method for producing industrial silicon, comprising:

[0014] The reactor includes: a reactor body, a gas distribution plate disposed within the reactor body, the gas distribution plate dividing the reactor body into a reaction chamber and a gas distribution chamber, the gas distribution plate being provided with gas distribution holes for distributing gas, the reaction chamber being provided with a reactor inlet for introducing silica and a reactor outlet, the gas distribution chamber being provided with a gas distribution chamber inlet for introducing hydrogen, and in the reaction chamber, silica reacts with hydrogen under heating to produce silicon dioxide and water;

[0015] A plasma generator is located in the reaction chamber. The plasma generator is used to ionize hydrogen gas to form hydrogen plasma. In the reaction chamber, silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0016] Preferably, the plasma generator includes an inner electrode and an outer electrode. The outer electrode is disposed on the inner wall of the reaction chamber, and the outer wall of the outer electrode is attached to the inner wall of the reaction chamber. The inner electrode is disposed in the area within the inner wall of the outer electrode.

[0017] Preferably, the internal electrode is cylindrical;

[0018] The cross-section of the outer electrode along the direction perpendicular to its axis is a closed ring; or, the outer electrode includes at least two sub-outer electrodes, the cross-section of the outer electrode along the direction perpendicular to its axis is a ring formed by the sub-outer electrodes, and the distance between the docking points of any two sub-outer electrodes is a preset distance.

[0019] Preferably, the external electrode includes an open end, a middle section, and an outlet end connected in sequence. The reactor feed inlet and the air distribution chamber air inlet are on the open end side, and the reactor discharge outlet is on the outlet end side. The cross-sectional area of ​​the open end is larger than the cross-sectional area of ​​the middle section, and the cross-sectional area of ​​the outlet end is larger than the cross-sectional area of ​​the middle section.

[0020] Preferably, the reactor is a fluidized bed reactor.

[0021] Preferably, the industrial silicon production system further includes:

[0022] The collector, connected to the reactor, is a cartridge dust collector used to collect reaction products and obtain silicon through filtration.

[0023] The receiving hopper, connected to the collector, is used to collect silicon.

[0024] Preferably, the industrial silicon production system further includes:

[0025] A hydrogen production unit, connected to a distribution chamber, is used to produce hydrogen gas.

[0026] A heat exchange device includes: a tube side and a shell. The tube side is disposed inside the shell and exchanges heat with the shell. The shell is provided with a first air inlet and a first air outlet. The tube side is provided with a second air inlet and a second air outlet. The first air inlet is connected to the air outlet of the collector, the first air outlet is connected to the mixing tank, the second air inlet is connected to the hydrogen production device, and the second air outlet is connected to the mixing tank.

[0027] The mixing tank is connected to the heat exchange device;

[0028] A gas heater, connected to a mixing tank, is used to heat the gas and is also connected to a distribution chamber.

[0029] Preferably, the industrial silicon production system further includes:

[0030] Storage silos are used to store raw material silicon dioxide.

[0031] The raw material buffer tank has its inlet connected to the storage silo and its outlet connected to the reactor inlet. The raw material buffer tank is used to buffer the raw material silica.

[0032] Compared with existing technologies, the method and system for producing industrial silicon in this invention have the following advantages:

[0033] (1) This process uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in existing technologies. The reaction tail gas contains almost no other components except hydrogen and water vapor. Furthermore, hydrogen and water vapor can be recycled, which significantly reduces greenhouse gas emissions in the industrial silicon production process. It is a green and environmentally friendly industrial silicon production process.

[0034] (2) The industrial silicon production system designed in this invention adopts a new industrial silicon generation reaction path. In the initial stage, electric heating or microwave heating is used to react silica with hydrogen to generate gaseous silicon monoxide. The reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid (silicon-carbon) reaction. In the stage of producing elemental silicon, plasma technology is used to generate hydrogen plasma from hydrogen, which further improves the reducing power of hydrogen. Elemental silicon can be obtained without high temperature and high pressure, reducing equipment requirements and improving system safety.

[0035] (3) The industrial silicon production system designed in this invention produces industrial silicon in powder form, which does not require secondary crushing, thus reducing production energy consumption and avoiding the introduction of impurities during the crushing process. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the system used in the method for producing industrial silicon in Embodiment 2 of the present invention;

[0037] Figure 2 This is a schematic diagram of the plasma generator structure in Embodiment 2 of the present invention;

[0038] Figure 3 This is a schematic diagram of the plasma generator structure in Embodiment 3 of the present invention.

[0039] In the diagram: 1-Hydrogen production unit; 2-Heat exchanger; 3-Mixing tank; 4-Gas heater; 5-Storage silo; 6-Raw material buffer tank; 7-Reactor; 8-Collector; 9-Receiving silo; 101-Hydrogen outlet; 201-First inlet; 202-First outlet; 203-Condensate outlet; 204-Second inlet; 205-Second outlet; 301-Mixing tank inlet; 302-Mixing tank outlet; 401-Gas heater inlet; 402-Gas... 601 - Gas outlet of the heater; 602 - Inlet of the raw material buffer tank; 701 - Outlet of the raw material buffer tank; 702 - Air distribution chamber; 703 - First reaction section; 704 - Air inlet of the air distribution chamber; 705 - Gas distribution plate; 706 - Inlet of the reactor; 707 - External electrode; 7071 - External electrode; 708 - Internal electrode; 709 - Outlet of the reactor; 801 - Inlet of the collector; 802 - Outlet of the collector; 803 - Bottom receiving port. Detailed Implementation

[0040] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] The embodiments of this patent are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this patent, and should not be construed as limiting this patent.

[0042] In the description of this patent, it should be understood that the terms “center,” “upper,” “lower,” “front,” “back,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the system or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this patent.

[0043] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0044] Example 1

[0045] This embodiment provides a method for producing industrial silicon, including the following steps:

[0046] 1) Hydrogen gas is introduced into silicon dioxide and heated to react, producing silicon suboxide and water;

[0047] 2) Hydrogen gas is ionized by a plasma generator to form hydrogen plasma, and silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0048] This embodiment also provides a system used in the above-described method for producing industrial silicon, comprising:

[0049] The reactor includes: a reactor body, a gas distribution plate disposed within the reactor body, the gas distribution plate dividing the reactor body into a reaction chamber and a gas distribution chamber, the gas distribution plate being provided with gas distribution holes for distributing gas, the reaction chamber being provided with a reactor inlet for introducing silica and a reactor outlet, the gas distribution chamber being provided with a gas distribution chamber inlet for introducing hydrogen, and in the reaction chamber, silica reacts with hydrogen under heating to produce silicon dioxide and water;

[0050] A plasma generator is located in the reaction chamber. The plasma generator is used to ionize hydrogen gas to form hydrogen plasma. In the reaction chamber, silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0051] Compared with existing technologies, the method and system for producing industrial silicon in this embodiment have the following advantages:

[0052] (1) This process uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in existing technologies. The reaction tail gas contains almost no other components except hydrogen and water vapor. Furthermore, hydrogen and water vapor can be recycled, which significantly reduces greenhouse gas emissions in the industrial silicon production process. It is a green and environmentally friendly industrial silicon production process.

[0053] (2) The industrial silicon production system designed in this embodiment adopts a new industrial silicon generation reaction path. In the initial stage, electric heating or microwave heating is used to react silicon with hydrogen to generate gaseous silicon monoxide. The reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid (silicon-carbon) reaction. In the stage of producing elemental silicon, plasma technology is used to generate hydrogen plasma from hydrogen, which further improves the reducing power of hydrogen. Elemental silicon can be obtained without high temperature and high pressure, reducing equipment requirements and improving system safety.

[0054] (3) The industrial silicon production system designed in this embodiment produces industrial silicon in powder form, which does not require secondary crushing, thus reducing production energy consumption and avoiding the introduction of impurities during the crushing process.

[0055] Example 2

[0056] like Figure 1 As shown, this embodiment provides an industrial silicon production system, including:

[0057] Reactor 7 includes: a reactor body, a gas distribution plate 705 disposed within the reactor body, the gas distribution plate 705 dividing the reactor body into a reaction chamber and a gas distribution chamber 701, the gas distribution plate 705 being provided with gas distribution holes for distributing gas, the reaction chamber being provided with a reactor inlet 706 for introducing silica and a reactor outlet 709, and the gas distribution chamber 701 being provided with a gas distribution chamber inlet 704 for introducing hydrogen. In the reaction chamber, silica reacts with hydrogen under heating to produce silicon dioxide and water.

[0058] A plasma generator is located in the reaction chamber. The plasma generator is used to ionize hydrogen gas to form hydrogen plasma. In the reaction chamber, silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0059] like Figure 2 As shown, preferably, the plasma generator includes: an inner electrode 708 and an outer electrode 707. The outer electrode 707 is disposed on the inner wall of the reaction chamber, and the outer wall of the outer electrode 707 is attached to the inner wall of the reaction chamber. The inner electrode 708 is disposed in the area within the inner wall of the outer electrode 707.

[0060] Preferably, the internal electrode 708 is cylindrical;

[0061] The cross-section of the outer electrode along the direction perpendicular to its axis is a closed ring. Specifically, in this embodiment, the inner electrode is connected to the positive terminal of the power supply, and the outer electrode is connected to the negative terminal of the power supply.

[0062] Preferably, the external electrode 707 includes an open end, a middle section, and an outlet end connected in sequence. The reactor inlet 706 and the air distribution chamber inlet 704 are on the open end side, and the reactor outlet 709 is on the outlet end side. The cross-sectional area of ​​the open end is larger than the cross-sectional area of ​​the middle section, and the cross-sectional area of ​​the outlet end is larger than the cross-sectional area of ​​the middle section.

[0063] Preferably, reactor 7 is a fluidized bed reactor 7.

[0064] Preferably, the industrial silicon production system further includes:

[0065] Collector 8 is connected to reactor 7. Collector 8 is a cartridge dust collector used to collect reaction products and obtain silicon through filtration.

[0066] The receiving bin 9 is connected to the collector 8 and is used to collect silicon.

[0067] Preferably, the industrial silicon production system further includes:

[0068] Hydrogen production device 1 is connected to air distribution chamber 701 and is used to produce hydrogen.

[0069] The heat exchange device 2 includes: a tube side and a shell. The tube side is disposed inside the shell and exchanges heat with the shell. The shell is provided with a first air inlet 201 and a first air outlet 202. The tube side is provided with a second air inlet 204 and a second air outlet 205. The first air inlet 201 is connected to the collector air outlet 802. The first air outlet 202 is connected to the mixing tank 3. The second air inlet 204 is connected to the hydrogen production device 1. The second air outlet 205 is connected to the mixing tank 3.

[0070] Mixing tank 3 is connected to heat exchange device 2;

[0071] Gas heater 4 is connected to gas mixing tank 3. Gas heater 4 is used to heat gas. Gas heater 4 is also connected to air distribution chamber 701.

[0072] Preferably, the industrial silicon production system further includes:

[0073] Storage silo 5 is used to store raw material silicon dioxide;

[0074] The raw material buffer tank 6 has its inlet connected to the storage silo 5 and its outlet connected to the reactor inlet 706. The raw material buffer tank 6 is used to buffer the raw material silica.

[0075] The industrial silicon production system in this embodiment includes: a hydrogen system, a heat exchange system, a heating system, a feeding system, a reduction system, and a receiving system.

[0076] Specifically, in this embodiment, the hydrogen system is a hydrogen production device 1, which is used to produce hydrogen. The hydrogen production device 1 can be hydrogen produced by electrolysis, hydrogen produced by natural gas cracking, etc. The hydrogen production device 1 is provided with a hydrogen outlet 101.

[0077] Specifically, in this embodiment, the heat exchange system consists of a heat exchange device 2 and a mixing tank 3. The heat exchange device 2 is a tubular heat exchanger, and it is also provided with a condensate outlet 203. The two ends of the tube side are provided with a second air inlet 204 and a second air outlet 205. The mixing tank 3 is provided with a mixing tank inlet 301 and a mixing tank outlet 302. The mixing tank inlet 301 is connected to the first air outlet 202 and the second air outlet 205 of the heat exchange device 2, respectively.

[0078] Specifically, in this embodiment, the heating system is a gas heater 4, which is provided with a gas heater inlet 401 and a gas heater outlet 402. The gas heater inlet 401 is connected to the gas outlet 302 of the mixing tank.

[0079] Specifically, in this embodiment, the feeding system consists of a storage silo 5 and a raw material buffer tank 6. The top of the raw material buffer tank 6 has a raw material buffer tank inlet 601, which connects to the bottom of the storage silo 5. The bottom of the raw material buffer tank 6 has a raw material buffer tank outlet 602, which connects to the reactor 7. Optionally, the feeding system includes a preheating device, which may be located on the raw material buffer tank 6 or independently. An independently installed preheating device refers to a preheating device located between the storage silo 5 and the raw material buffer tank 6, connected to both the storage silo 5 and the raw material buffer tank 6. The heat source for the preheating device is an electric heating device, a microwave heating device, or a tail gas heat exchanger.

[0080] Specifically, the preheating device in this embodiment is a microwave heating device.

[0081] Specifically, in this embodiment, the reduction system includes a reactor 7, which is a fluidized bed reactor 7. The fluidized bed reactor 7 is divided into three areas from bottom to top: an air distribution chamber 701, a first reaction section 702, and a second reaction section 703. The air distribution chamber 701 has an air inlet 704 at its bottom and a gas heater outlet 402 on its gas heater 4. The air inlet 704 is connected to the gas heater outlet 402. The air distribution chamber 701 has a gas distribution plate 705 at its top to support the material layer and ensure uniform gas distribution. The first reaction section 702 is heated by electric heating or microwave heating. At least one reactor feed inlet 706 is located on the side wall of the first reaction section 702, connected to the raw material buffer tank outlet 602 at the bottom of the raw material buffer tank 6. The second reaction section 703 has a plasma generator, consisting of an annular outer electrode 707 and a cylindrical inner electrode 708, with an hourglass-shaped constriction formed between the inner electrode 708 and the outer electrode 707. The second reaction section 703 is equipped with a reactor outlet 709 at its top.

[0082] Specifically, in this embodiment, the heating method of the first reaction section 702 is microwave heating.

[0083] Specifically, in this embodiment, the material receiving system consists of a collector 8 and a receiving hopper 9. The collector inlet 801 of the collector 8 is connected to the reactor outlet 709, the collector outlet 802 of the collector 8 is connected to the first air inlet 201 of the heat exchanger, and the bottom receiving port 803 of the collector 8 is connected to the receiving hopper 9. Optionally, the collector 8 can be one or a combination of a cartridge filter, a cyclone dust collector, an electrostatic precipitator, etc.

[0084] This embodiment provides a method for producing industrial silicon, including the following steps:

[0085] 1) Hydrogen gas is introduced into silicon dioxide and heated to react, producing silicon suboxide and water;

[0086] 2) Hydrogen gas is ionized by a plasma generator to form hydrogen plasma, and silicon suboxide reacts with the hydrogen plasma to generate silicon.

[0087] Preferably, the heating temperature in step 1) is 1200–1700°C.

[0088] Preferably, the particle size of silica in step 1) does not exceed 10 mm.

[0089] Specifically, this embodiment provides a method for producing industrial silicon using the above-described industrial silicon production system, comprising the following steps:

[0090] Ⅰ. Replace the air in the industrial silicon production system with an inert gas. Produce hydrogen using hydrogen production unit 1;

[0091] II. The produced hydrogen is introduced into the tube side of the heat exchanger to exchange heat with the tail gas in the shell side. The water vapor in the tail gas is condensed and discharged. Then, the hydrogen in the tube side and shell side is introduced into the mixing tank 3 for mixing. The mixed hydrogen is then introduced into the gas heater 4, and the heating power is controlled to keep the hydrogen temperature at 900℃. After heating, it is introduced into the fluidized bed reactor 7.

[0092] III. Add silica raw material with a particle size of 100μm-300μm to storage silo 5. Inject the silica raw material into raw material buffer tank 6, and turn on the microwave heating system of raw material buffer tank 6 to preheat the raw material to 800℃. The silica raw material in storage silo 5 enters the first reaction section 702 of fluidized bed reactor 7 through raw material buffer tank 6;

[0093] IV. Turn on the microwave heating system of the first reaction section 702 to heat the raw materials to 1500℃;

[0094] V. The gas in the mixing tank 3 is passed into the gas heater 4, heated, and then passed into the fluidized bed reactor 7. The flow rate of hydrogen gas introduced into the fluidized bed reactor 7 is 80,000 Nm³. 3 / h, hydrogen gas passes through gas distribution plate 705 in air distribution chamber 701 and then enters first reaction section 702 evenly. Hydrogen gas and raw material silicon dioxide undergo a preliminary reduction reaction in first reaction section 702 to generate intermediate products silicon suboxide and water. The intermediate products and hydrogen gas then rise into second reaction section 703.

[0095] VI. Turn on the plasma generator of the second reaction section 703. The plasma generator has a power of 4MW. Hydrogen gas is ionized through the inner and outer electrodes of the plasma generator to form hydrogen plasma. Silicon suboxide reacts with hydrogen plasma to generate silicon. The intermediate product silicon suboxide is further reduced by hydrogen plasma to generate industrial silicon. Industrial silicon is elemental silicon particles.

[0096] VII. The generated industrial silicon and tail gas enter collector 8, where elemental silicon particles are filtered and collected before entering receiving hopper 9. Testing shows that the elemental silicon content is greater than 98 mas% and the particle size is less than 150 μm, resulting in a silicon yield of 98%. The tail gas enters a heat exchanger to exchange heat with hydrogen supplied by hydrogen production unit 1. The hydrogen then circulates within the industrial silicon production system, and the condensed water vapor is collected.

[0097] VIII. Shut down the production system, replace the hydrogen in the receiving hopper 9 with an inert gas, and transport the silicon powder to downstream applications using pneumatic conveying to ensure safety during transportation and downstream use. Specifically, in this embodiment, the inert gas is nitrogen.

[0098] In the above steps, the temperature change caused by the heat exchange between the tail gas and the hydrogen produced by the hydrogen production unit 1 is within 100°C. The condensate outlet 203 is connected to the hydrogen production unit 1. The water vapor in the tail gas is condensed and flows out through the condensate outlet 203 into the hydrogen production unit 1 for recycling.

[0099] In the above steps, the hydrogen gas is heated to 700-1100℃ by gas heater 4. The specific hydrogen flow rate depends on the size of reactor 7, silica particle size, and processing capacity. During operation, the pressure inside the industrial silicon production system is higher than the ambient pressure to prevent air from entering the system and causing safety accidents.

[0100] In the above steps, the heating system of the first reaction section 702 can be microwave heating, electric heating or microwave / electric hybrid heating, and the raw material temperature is heated to 1200-1700℃.

[0101] In the above steps, the silica raw material is quartz, silica, etc., which are formed into particles after beneficiation and crushing, with a particle size of 0-10mm.

[0102] In the above steps, the silica raw material particles can be directly fed into the first reaction section 702, or they can be preheated by a preheating device at a temperature of 500-1000℃.

[0103] In the above steps, within the first reaction section 702, hydrogen reacts with silicon dioxide raw material at 1200-1700℃ to generate gaseous silicon monoxide. The specific reaction equation is as follows:

[0104] H2(g)+SiO2(s)→H2O(g)+SiO(g)(1)

[0105] In the above steps, within the second reaction section 703, hydrogen gas forms hydrogen plasma (H2O) between the inner and outer electrodes. + H 2+ H 3+ The reduction potential of hydrogen plasma is much higher than that of hydrogen molecules, which can further reduce gaseous silicon monoxide to elemental silicon.

[0106] In the above steps, the flow rate of hydrogen gas introduced into reactor 7 is 80,000 Nm³. 3 / h.

[0107] In the above steps, the power of the plasma generator is 4MW.

[0108] In the above steps, the size of the hydrogen plasma formation region can be changed by adjusting the shape of the inner and outer electrodes, thereby controlling the gas flow rate and mixing effect.

[0109] In the above steps, the collector type 8 is selected based on the particle size of the industrial silicon produced by the system.

[0110] In the above steps, the inert gas used to replace hydrogen can be nitrogen, helium, carbon dioxide, etc.

[0111] Compared with existing technologies, the method and system for producing industrial silicon in this embodiment have the following advantages:

[0112] (1) This process uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in existing technologies. The reaction tail gas contains almost no other components except hydrogen and water vapor. Furthermore, hydrogen and water vapor can be recycled, which significantly reduces greenhouse gas emissions in the industrial silicon production process. It is a green and environmentally friendly industrial silicon production process.

[0113] (2) The industrial silicon production system designed in this embodiment adopts a new industrial silicon generation reaction path. In the initial stage, electric heating or microwave heating is used to react silicon with hydrogen to generate gaseous silicon monoxide. The reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid (silicon-carbon) reaction. In the stage of producing elemental silicon, plasma technology is used to generate hydrogen plasma from hydrogen, which further improves the reducing power of hydrogen. Elemental silicon can be obtained without high temperature and high pressure, reducing equipment requirements and improving system safety.

[0114] (3) The industrial silicon production system designed in this embodiment uses a fluidized bed as the main reduction reactor 7. Compared with a high-temperature electric arc furnace, the fluidized bed can continuously feed materials, and the internal heat transfer is efficient.

[0115] A higher mass flow rate can improve production efficiency.

[0116] (4) The industrial silicon production system designed in this embodiment produces industrial silicon in powder form, which does not require secondary crushing, thus reducing production energy consumption and avoiding the introduction of impurities during the crushing process.

[0117] Example 3

[0118] like Figure 3 As shown, this embodiment provides an industrial silicon production system, which differs from the one in Embodiment 2 in that:

[0119] The outer electrode 707 includes at least two sub-outer electrodes 7071. The cross-section of the outer electrode 707 along the direction perpendicular to its axis is an annular shape formed by the sub-outer electrodes 7071. The distance between the docking points of any two sub-outer electrodes 7071 is a preset distance.

[0120] Specifically, in this embodiment, the inner electrode 708 is connected to the positive terminal of the power supply, and each sub-outer electrode 7071 is connected to the negative terminal of the power supply.

[0121] This embodiment provides a method for producing industrial silicon using the industrial silicon production system of Embodiment 2. The difference between this method and the method in Embodiment 2 is as follows:

[0122] In step II, hydrogen gas is preheated to 700°C using a gas heater;

[0123] In step III, silica raw material with a particle size of 3-5 mm is added to the storage silo, and the microwave heating system of the raw material buffer tank is turned on to preheat the raw material to 1000°C.

[0124] In step IV, the microwave heating system of the first reaction section is turned on to heat the raw materials to 1700°C.

[0125] In step V, the flow rate of hydrogen gas introduced into the reactor is 60,000 Nm³. 3 / h.

[0126] In step VI, the power of the plasma generator is 0.5MW.

[0127] In step VII, the generated industrial silicon and tail gas enter the collector, where the elemental silicon particles are filtered and collected before entering the receiving hopper. After testing, the elemental silicon content is greater than 95 mas%, the particle size is less than 160 μm, and the silicon yield is 92%.

[0128] Compared with existing technologies, the method and system for producing industrial silicon in this embodiment have the following advantages:

[0129] (1) This process uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in existing technologies. The reaction tail gas contains almost no other components except hydrogen and water vapor. Furthermore, hydrogen and water vapor can be recycled, which significantly reduces greenhouse gas emissions in the industrial silicon production process. It is a green and environmentally friendly industrial silicon production process.

[0130] (2) The industrial silicon production system designed in this embodiment adopts a new industrial silicon generation reaction path. In the initial stage, electric heating or microwave heating is used to react silicon with hydrogen to generate gaseous silicon monoxide. The reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid (silicon-carbon) reaction. In the stage of producing elemental silicon, plasma technology is used to generate hydrogen plasma from hydrogen, which further improves the reducing power of hydrogen. Elemental silicon can be obtained without high temperature and high pressure, reducing equipment requirements and improving system safety.

[0131] (3) The industrial silicon production system designed in this embodiment uses a fluidized bed as the main reduction reactor. Compared with a high-temperature electric arc furnace, the fluidized bed can be continuously fed and has a higher internal heat and mass transfer rate, which can improve production efficiency.

[0132] (4) The industrial silicon production system designed in this embodiment produces industrial silicon in powder form, which does not require secondary crushing, thus reducing production energy consumption and avoiding the introduction of impurities during the crushing process.

[0133] Example 4

[0134] This embodiment provides a method for producing industrial silicon using the industrial silicon production system of Embodiment 2. The difference between this method and the method in Embodiment 2 is as follows:

[0135] In step II, hydrogen gas is preheated to 1100°C using a gas heater;

[0136] In step III, silica raw material with a particle size of 8-10 mm is added to the storage silo, and the microwave heating system of the raw material buffer tank is turned on to preheat the raw material to 500°C.

[0137] In step IV, the microwave heating system of the first reaction section is turned on to heat the raw materials to 1200°C.

[0138] In step V, the flow rate of hydrogen gas introduced into the reactor is 20000 Nm. 3 / h.

[0139] In step VI, the power of the plasma generator is 1MW.

[0140] In step VII, the generated industrial silicon and tail gas enter the collector, where the elemental silicon particles are filtered and collected before entering the receiving hopper. After testing, the elemental silicon content is greater than 94 mas%, the particle size is less than 180 μm, and the silicon yield is 96%.

[0141] Compared with existing technologies, the method and system for producing industrial silicon in this embodiment have the following advantages:

[0142] (1) This process uses hydrogen instead of carbon-based reducing agents such as petroleum coke and coal in existing technologies. The reaction tail gas contains almost no other components except hydrogen and water vapor. Furthermore, hydrogen and water vapor can be recycled, which significantly reduces greenhouse gas emissions in the industrial silicon production process. It is a green and environmentally friendly industrial silicon production process.

[0143] (2) The industrial silicon production system designed in this embodiment adopts a new industrial silicon generation reaction path. In the initial stage, electric heating or microwave heating is used to react silicon with hydrogen to generate gaseous silicon monoxide. The reaction rate of the gas-solid reaction is much higher than that of the existing solid-solid (silicon-carbon) reaction. In the stage of producing elemental silicon, plasma technology is used to generate hydrogen plasma from hydrogen, which further improves the reducing power of hydrogen. Elemental silicon can be obtained without high temperature and high pressure, reducing equipment requirements and improving system safety.

[0144] (3) The industrial silicon production system designed in this embodiment uses a fluidized bed as the main reduction reactor. Compared with a high-temperature electric arc furnace, the fluidized bed can be continuously fed and has a higher internal heat and mass transfer rate, which can improve production efficiency.

[0145] (4) The industrial silicon production system designed in this embodiment produces industrial silicon in powder form, which does not require secondary crushing, thus reducing production energy consumption and avoiding the introduction of impurities during the crushing process.

[0146] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for producing industrial silicon, characterized in that, Includes the following steps: 1) In a fluidized bed reactor, hydrogen gas is introduced into silica and heated to react at a temperature of 1200~1700℃, producing silicon suboxide and water; 2) In the same fluidized bed reactor, hydrogen gas is ionized by a plasma generator to form hydrogen plasma, and silicon suboxide reacts with the hydrogen plasma to generate powdered silicon.

2. The method for producing industrial silicon according to claim 1, characterized in that, In step 1), the particle size of silica does not exceed 10 mm.

3. The method for producing industrial silicon according to claim 1, characterized in that, In step 1), the flow rate of hydrogen gas introduced is 1-100000 Nm. 3 / h.

4. The method for producing industrial silicon according to any one of claims 1 to 3, characterized in that, The power of the plasma generator in step 2) is 0.1-4MW.

5. An industrial silicon production system used in the method for producing industrial silicon according to any one of claims 1 to 4, characterized in that, include: The reactor includes: a reactor body, a gas distribution plate disposed within the reactor body, the gas distribution plate dividing the reactor body into a reaction chamber and a gas distribution chamber, the gas distribution plate being provided with gas distribution holes for distributing gas, the reaction chamber being provided with a reactor inlet for introducing silica and a reactor outlet, the gas distribution chamber being provided with a gas distribution chamber inlet for introducing hydrogen, in the reaction chamber, silica and hydrogen are heated and reacted to produce silicon dioxide and water, the reactor is a fluidized bed reactor; A plasma generator is located in the reaction chamber. The plasma generator is used to ionize hydrogen gas to form hydrogen plasma. In the reaction chamber, silicon suboxide reacts with the hydrogen plasma to generate silicon.

6. The industrial silicon production system according to claim 5, characterized in that, The plasma generator includes an inner electrode and an outer electrode. The outer electrode is disposed on the inner wall of the reaction chamber, and the outer wall of the outer electrode is attached to the inner wall of the reaction chamber. The inner electrode is disposed in the area inside the inner wall of the outer electrode.

7. The industrial silicon production system according to claim 6, characterized in that, The internal electrode is cylindrical; The cross-section of the outer electrode along the direction perpendicular to its axis is a closed ring; or, the outer electrode includes at least two sub-outer electrodes, the cross-section of the outer electrode along the direction perpendicular to its axis is a ring formed by the sub-outer electrodes, and the distance between the docking points of any two sub-outer electrodes is a preset distance.

8. The industrial silicon production system according to claim 6 or 7, characterized in that, The external electrode includes an open end, a middle section, and an outlet end connected in sequence. The reactor feed inlet and the air distribution chamber air inlet are on the open end side, and the reactor discharge outlet is on the outlet end side. The cross-sectional area of ​​the open end is larger than that of the middle section, and the cross-sectional area of ​​the outlet end is larger than that of the middle section.

9. The industrial silicon production system according to claim 5, characterized in that, Also includes: The collector, connected to the reactor, is a cartridge dust collector used to collect reaction products and obtain silicon through filtration. The receiving hopper, connected to the collector, is used to collect silicon.

10. The industrial silicon production system according to claim 9, characterized in that, Also includes: A hydrogen production unit, connected to a distribution chamber, is used to produce hydrogen gas. A heat exchange device includes: a tube side and a shell. The tube side is disposed inside the shell and exchanges heat with the shell. The shell is provided with a first air inlet and a first air outlet. The tube side is provided with a second air inlet and a second air outlet. The first air inlet is connected to the air outlet of the collector, the first air outlet is connected to the mixing tank, the second air inlet is connected to the hydrogen production device, and the second air outlet is connected to the mixing tank. The mixing tank is connected to the heat exchange device; A gas heater, connected to a mixing tank, is used to heat the gas and is also connected to a distribution chamber.

11. The industrial silicon production system according to any one of claims 5, 6, 7, 9, and 10, characterized in that, Also includes: Storage silos are used to store raw material silicon dioxide. The raw material buffer tank has its inlet connected to the storage silo and its outlet connected to the reactor inlet. The raw material buffer tank is used to buffer the raw material silica.

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