Refined utilization method and system for waste silicon powder of chassis of reduction furnace

Abstract

The invention discloses a method and a system for fine utilization of waste silicon powder of a chassis of a reduction furnace, and the method comprises the following steps: adding a certain proportion of polyphosphazene powder into the waste silicon powder of the chassis of the reduction furnace, fully mixing, and uniformly covering the surface of the waste silicon powder of the chassis of the reduction furnace with the polyphosphazene powder to obtain mixed powder; carrying out ashing treatment on the mixed powder under a high-temperature condition, and cooling to obtain carbonized blocks; the carbonized blocks are ground and screened, and oversize powder and undersize powder are obtained; and loading an active substance on the surface of the oversize powder to prepare a silicon-carbon catalyst, soaking the undersize powder in a solvent, cleaning, and drying to prepare the silicon-carbon adsorbent. According to the method, spontaneous combustion prevention and refined utilization of the waste silicon powder of the reduction furnace chassis can be achieved, the safety risk in the polycrystalline silicon production process is reduced, the waste silicon powder of the reduction furnace chassis is converted into a material with certain value and application, resource waste is avoided, cyclic utilization and sustainable development of resources are achieved, and the resource utilization efficiency and economic benefits are improved; and the influence on the environment is reduced.

Description

Technical Field

[0001] This invention belongs to the field of polycrystalline silicon technology, specifically relating to a method and system for the refined utilization of waste silicon powder from a reduction furnace chassis. Background Technology

[0002] Polysilicon is an important semiconductor material, widely used in industries such as solar cells and integrated circuits. During the production of polysilicon, a large amount of waste silicon powder is generated. If this waste silicon powder is not handled properly, it may spontaneously combust, causing safety accidents. Among these waste silicon powders, the waste silicon powder from the bottom of the reduction furnace is the most flammable. The main reasons for its spontaneous combustion are: (1) The waste silicon powder from the bottom of the reduction furnace has a small particle size and a large specific surface area, making it easier to react with water and oxygen in the air to generate silicon dioxide, and this reaction is an exothermic reaction;

[0003] (2) The waste silicon powder in the reduction furnace chassis contains a small amount of chlorosilane (such as monochlorotrihydrosilane, dichlorodihydrosilane, trichlorosilane, silicon tetrachloride, etc.), and the chlorosilane hydrolysis degenerates heat; (3) The waste silicon powder in the reduction furnace chassis has a large specific surface area and easily adsorbs hydrogen. The hydrogen reacts with oxygen at high temperature, causing severe heat accumulation in the silicon powder, which leads to spontaneous combustion of the silicon powder.

[0004] The silicon content of the waste silicon powder in the reduction furnace chassis is high, reaching over 99%. However, due to its flammability and excessive reactivity, it cannot be transported and is difficult to utilize effectively.

[0005] Currently, waste silicon powder from reduction furnace chassis is typically disposed of through landfill or solidification, fixing it in a specific matrix to prevent spontaneous combustion. While this landfill or solidification method reduces environmental pollution to some extent, its efficiency and economic viability are low due to a lack of refined processing and comprehensive utilization, resulting in significant silicon waste and continued environmental impact. Summary of the Invention

[0006] The technical problem to be solved by this invention is to address the above-mentioned shortcomings of the existing technology by providing a method and system for the refined utilization of waste silicon powder from the reduction furnace chassis. This method and system can prevent spontaneous combustion and achieve refined utilization of waste silicon powder from the reduction furnace chassis, reduce the safety risks in the polysilicon production process, transform the waste silicon powder from the reduction furnace chassis into materials with certain value and uses, avoid resource waste, realize resource recycling and sustainable development, improve resource utilization efficiency and economic benefits, and reduce environmental impact.

[0007] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0008] According to a first aspect of the present invention, a method for the refined utilization of waste silicon powder from a reduction furnace chassis is provided, comprising:

[0009] A certain proportion of polyphosphazene powder is added to the waste silicon powder in the reduction furnace chassis and mixed thoroughly so that the polyphosphazene powder evenly covers the surface of the waste silicon powder in the reduction furnace chassis, thus obtaining a mixed powder.

[0010] The mixed powder was ashed at high temperature and then cooled to obtain carbonized lumps.

[0011] The carbonized lumps are ground and sieved to obtain powder that is sieved over the sieve and powder that is sieved under the sieve.

[0012] The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in a solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0013] Optionally, the waste silicon powder in the reduction furnace chassis accounts for 20% to 80% of the total mass of the mixed powder.

[0014] Optionally, the polyphosphononitrile is one or more of polyphenoxyphosphononitrile (PPPh), poly(p-methylphenoxyphosphononitrile) (PMPPh), and poly(trifluoroethoxyphosphononitrile) (PTFEPh).

[0015] Optionally, the particle size of the polyphosphonic acrylonitrile powder is 10–100 nm.

[0016] Optionally, the ashing treatment temperature is 800℃~1400℃, the pressure is atmospheric pressure, and the ashing treatment time is 12~24h.

[0017] Optionally, the ashing process is carried out in a nitrogen or inert gas atmosphere.

[0018] Optionally, the grinding refers to grinding the carbonized blocky material to 20-160 mesh;

[0019] Optionally, the sieving refers to passing the ground carbonized lumps through an 80-mesh sieve to obtain powder larger than 80 mesh and powder smaller than or equal to 80 mesh.

[0020] Optionally, the active substance is a transition metal chloride or a transition metal oxide.

[0021] Optionally, the solvent is ethanol, acetone, or deionized water.

[0022] According to a second aspect of the present invention, a system for the refined utilization of waste silicon powder from a reduction furnace chassis is provided, comprising a silicon powder flame retardant device, an ashing treatment device, and a product preparation device, wherein:

[0023] The silicon powder flame retardant device is used to fully mix the waste silicon powder from the reduction furnace chassis with a certain proportion of polyphosphazene powder, so that the polyphosphazene powder is evenly covered on the surface of the waste silicon powder from the reduction furnace chassis to obtain mixed powder.

[0024] The ashing treatment device is connected to the silicon powder flame retardant device, and is used to receive the mixed powder obtained by the silicon powder flame retardant device, and to ashing the powder under high temperature conditions, and to obtain carbonized blocky material after cooling.

[0025] The product preparation device is connected to the ashing treatment device and is used to grind and sieve the carbonized block to obtain powder on the sieve and powder under the sieve. The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0026] Optionally, the silicon powder flame retardant device includes a waste silicon powder tank, a feeding device, and a mixing device, wherein:

[0027] The waste silicon powder tank is used to connect to the reduction furnace in the cold hydrogenation production process to receive waste silicon powder from the bottom of the reduction furnace.

[0028] The feeding device is connected to the waste silicon powder tank and is used to add a certain proportion of polyphosphazene powder to the waste silicon powder tank.

[0029] The mixing device is connected to the waste silicon powder tank and is used to fully mix the waste silicon powder from the reduction furnace chassis in the waste silicon powder tank with the polyphosphazene powder to obtain mixed powder.

[0030] Optionally, the ashing treatment apparatus includes heating equipment, an ashing chamber, and atmosphere control equipment, wherein:

[0031] The ashing chamber is connected to the silicon powder flame retardant device and is used to receive the mixed powder output by the silicon powder flame retardant device and provide an ashing treatment site.

[0032] The heating equipment is connected to the ashing chamber and is used to heat the ashing chamber to reach the high temperature conditions required for the ashing process.

[0033] The atmosphere control device is connected to the ashing chamber and is used to introduce nitrogen or inert gas into the ashing chamber to adjust the atmosphere inside the ashing chamber to the atmospheric conditions required for the ashing process.

[0034] Optionally, the product preparation apparatus includes grinding equipment, sieving equipment, a first surface treatment equipment, and a second surface treatment equipment, wherein:

[0035] The grinding equipment is connected to the discharge port of the ashing chamber in the ashing treatment device and is used to grind the carbonized blocky material.

[0036] The screening equipment is connected to the grinding device and is used to screen the ground carbonized lumps to obtain powder on the sieve and powder under the sieve.

[0037] The first surface treatment equipment is used to load active materials onto the surface of powder on a sieve to obtain a silicon-carbon catalyst;

[0038] The second surface treatment equipment is used to soak the sieved powder in a solvent, then wash and dry it to obtain a silicon-carbon adsorbent.

[0039] Optionally, the system also includes a safety device, which includes a temperature sensor located inside the ashing device to monitor the internal temperature of the ashing device and to issue an alarm when the temperature exceeds a preset temperature threshold, so as to ensure that the ashing temperature is not too high.

[0040] The method and system for the refined utilization of waste silicon powder from the reduction furnace chassis of the present invention have the following beneficial effects:

[0041] (1) It can prevent spontaneous combustion and make refined use of waste silicon powder from the reduction furnace chassis, reduce the safety risks in the polysilicon production process, transform the waste silicon powder from the reduction furnace chassis into materials with certain value and uses, avoid the waste of resources, realize the recycling and sustainable development of resources, improve resource utilization efficiency and economic benefits, reduce the impact on the environment, reduce the processing cost, and thus solve a major problem faced by polysilicon production enterprises.

[0042] (2) Polyphosphazene can improve the surface area and pore structure of waste silicon powder in the reducing furnace chassis. Compared with traditional fire retardant additives, polyphosphazene will not reduce the mechanical properties of the material after treatment, such as strength and durability, thus improving its performance as an adsorbent or catalyst carrier.

[0043] (3) Polyphosphazene can increase the number and distribution of active sites in the waste silicon powder in the reduction furnace chassis, thereby improving its efficiency and selectivity in catalytic reactions.

[0044] (4) The waste silicon powder from the reduction furnace bottom after polyphosphazene treatment has higher chemical stability and can cope with complex industrial environments and reaction conditions. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of a method for the refined utilization of waste silicon powder from a reduction furnace chassis in an embodiment of the present invention;

[0046] Figure 2 This is a diagram showing the changes in impurities before and after ashing in the method described in this embodiment of the invention;

[0047] Figure 3 This is a particle size distribution diagram of the silicon-carbon catalyst in the embodiments of the present invention;

[0048] Figure 4 This is a particle size distribution diagram of the silicon-carbon adsorbent in the embodiments of the present invention;

[0049] Figure 5 This is a graph showing the quantitative analysis data of the silicon powder recovery effect of the method in the embodiments of the present invention.

[0050] In the diagram: 1. Feeding equipment; 2. Silicon powder flame retardant device; 3. Mixing equipment; 4. Mixed powder inlet; 5. Ashing chamber; 6. Ashing treatment device; 7. Heating equipment; 8. Grinding equipment; 9. Quality inspection equipment; 10. Product preparation device; 11. Waste silicon powder tank outlet; 12. Atmosphere control equipment; 13. Ashing chamber outlet; 14. Safety device; 15. Screening equipment; 16. Surface treatment equipment. Detailed Implementation

[0051] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0052] To address the problems of low resource utilization efficiency and economic benefits, as well as environmental impact, of waste silicon powder from reduction furnace chassis in existing technologies, this invention provides a method for the refined utilization of waste silicon powder from reduction furnace chassis, comprising:

[0053] A certain proportion of polyphosphazene powder is added to the waste silicon powder in the reduction furnace chassis and mixed thoroughly so that the polyphosphazene powder evenly covers the surface of the waste silicon powder in the reduction furnace chassis, thus obtaining a mixed powder.

[0054] The mixed powder was ashed at high temperature and then cooled to obtain carbonized lumps.

[0055] The carbonized lumps are ground and sieved to obtain powder that is sieved over the sieve and powder that is sieved under the sieve.

[0056] The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in a solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0057] Accordingly, the present invention also discloses a system for the refined utilization of waste silicon powder from a reduction furnace chassis, comprising a silicon powder flame retardant device, an ashing treatment device, and a product preparation device, wherein:

[0058] The silicon powder flame retardant device is used to fully mix the waste silicon powder from the reduction furnace chassis with a certain proportion of polyphosphazene powder, so that the polyphosphazene powder is evenly covered on the surface of the waste silicon powder from the reduction furnace chassis to obtain mixed powder.

[0059] The ashing treatment device is connected to the silicon powder flame retardant device, and is used to receive the mixed powder obtained by the silicon powder flame retardant device, and to ashing the powder under high temperature conditions, and to obtain carbonized blocky material after cooling.

[0060] The product preparation device is connected to the ashing treatment device and is used to grind and sieve the carbonized block to obtain powder on the sieve and powder under the sieve. The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0061] Example 1

[0062] like Figure 1 As shown, a method for the refined utilization of waste silicon powder from a reduction furnace chassis includes:

[0063] A certain proportion of polyphosphazene powder is added to the waste silicon powder in the reduction furnace chassis and mixed thoroughly so that the polyphosphazene powder evenly covers the surface of the waste silicon powder in the reduction furnace chassis, thus obtaining a mixed powder.

[0064] The mixed powder was ashed at high temperature and then cooled to obtain carbonized lumps.

[0065] The carbonized lumps are ground and sieved to obtain powder that is sieved over the sieve and powder that is sieved under the sieve.

[0066] The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in a solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0067] Polyphosphononitrile possesses excellent high-temperature resistance, maintaining stability under high-temperature conditions and being non-flammable. Through extensive experimentation, the inventors discovered that adding a certain proportion of polyphosphononitrile powder as a fire retardant can effectively prevent spontaneous combustion of waste silicon powder from the reduction furnace chassis, thereby reducing safety risks in the polysilicon production process. Furthermore, by ashing the mixed powder, silicon-carbon catalysts and adsorbents can be further prepared, enabling the refined utilization of waste silicon powder from the reduction furnace chassis. This transforms the waste silicon powder into materials with certain value and uses, avoiding resource waste, achieving resource recycling and sustainable development, improving resource utilization efficiency and economic benefits, and reducing environmental impact.

[0068] Furthermore, compared to traditional fire retardant additives, polyphosphononitrile does not reduce the mechanical properties of materials (silicon-carbon catalysts and silicon-carbon adsorbents) such as strength and durability after treatment. At the same time, the waste silicon powder from the reduction furnace chassis treated with polyphosphononitrile shows significant improvements in surface area and pore structure, enhancing its performance as an adsorbent or catalyst carrier. Polyphosphononitrile can increase the number and distribution of active sites in the waste silicon powder from the reduction furnace chassis, improving its efficiency and selectivity in catalytic reactions. The waste silicon powder from the reduction furnace chassis treated with polyphosphononitrile also exhibits higher chemical stability, enabling it to withstand complex industrial environments and reaction conditions.

[0069] In some embodiments, the waste silicon powder from the reduction furnace chassis accounts for 20% to 80% of the total mass of the mixed powder. That is, the mass mixing ratio of polyphosphazene powder to waste silicon powder from the reduction furnace chassis is 1:4 to 4:1. Precise mixing of the waste silicon powder and polyphosphazene powder from the reduction furnace chassis is ensured by using a powder conveying system and accurate weighing devices. Furthermore, the inventors have discovered that when the proportion of polyphosphazene powder is high, the resulting materials (silicon-carbon catalyst and silicon-carbon adsorbent) have stronger performance and higher stability, but the cost is also higher; when the proportion of polyphosphazene powder is low, the cost is lower, but the performance of the resulting silicon-carbon catalyst and silicon-carbon adsorbent decreases significantly.

[0070] In this embodiment, the preferred mass mixing ratio of polyphosphazene powder to waste silicon powder from the reduction furnace chassis is 1:3. At this ratio, the performance of the prepared silicon-carbon catalyst and silicon-carbon adsorbent is moderate, and the cost-effectiveness is significant.

[0071] In some embodiments, the polyphosphononitrile is one or more of polyphenoxyphosphononitrile (PPPh), poly(p-methylphenoxyphosphononitrile) (PMPPh), and polytrifluoroethoxyphosphononitrile (PTFEPh), but is not limited thereto.

[0072] In some embodiments, the particle size of polyphosphononitrile powder is 10-100 nm. At this size, the specific surface area of ​​polyphosphononitrile powder is relatively high. The high specific surface area enables it to perform well in fields such as catalysis and adsorption. Furthermore, under this particle size condition, polyphosphononitrile has high strength and rigidity, giving it excellent mechanical properties, and is more suitable as a skeleton in composite materials.

[0073] In some implementations, due to the high melting point of silicon powder and the fact that polyphosphononitrile itself is a fire-retardant material, a temperature of over 800 degrees Celsius is required to ensure successful ashing. However, if the temperature is too high, it will cause the silicon powder and polyphosphononitrile to eutectic (the reaction between polyphosphononitrile and silicon powder at high temperatures is very complex, with many side reactions; the main reaction can be represented by the following equation: Si + (R₂N - P = NR). n →Si-N + polyphosphazene carbonized framework + unreacted silicon, where: Si represents silicon powder, (R2N-P=NR) n The structure of polyphosphononitrile (R represents a substituent containing carbon), Si-N represents the generated nitrogen-silicon compound, and unreacted silicon is adsorbed on the polyphosphononitrile framework, thus preventing ashing. This affects the formation of silicon-carbon adsorbents and catalysts. The ashing temperature increases with the polyphosphononitrile content, which is detrimental to production. Therefore, the preferred ashing temperature is 800℃~1400℃, the ashing pressure is atmospheric pressure, and the ashing time is 12~24h.

[0074] Compared to traditional fire retardant additives, this application uses polyphosphononitrile, which can also promote the high-temperature ashing process of waste silicon powder (hereinafter referred to as silicon powder) in the reduction furnace chassis, accelerate the chemical reaction of silicon powder at high temperatures, thereby reducing the ashing temperature and ashing time. In addition, during the high-temperature ashing process, polyphosphononitrile can also improve the structural stability of silicon powder and reduce the bonding force between particles, which is beneficial to subsequent powder processing and utilization.

[0075] In some embodiments, the ashing process is carried out under a nitrogen or inert gas (such as argon) atmosphere to prevent oxidation reactions, thereby maintaining the chemical purity and stability of the product.

[0076] In some implementations, the cooling conditions are 25°C and atmospheric pressure cooling for 8-12 hours, which is easy to operate.

[0077] In some embodiments, grinding refers to grinding the carbonized lumps to 20-160 mesh; sieving refers to passing the ground 20-160 mesh carbonized lumps through an 80 mesh sieve to obtain powder larger than 80 mesh and powder smaller than or equal to 80 mesh. Such powder typically has a larger pore size and higher specific surface area, which helps to achieve uniform distribution and higher loading of subsequent active materials. At the same time, due to the larger particle size of the powder, it has more robust physical properties and can maintain structural stability under high temperature and pressure conditions. It is not easily worn or deformed and is suitable for applications that require larger particles, such as certain fillers or reinforcing materials. In this method, it is used as a catalyst carrier.

[0078] In some embodiments, the active material is a transition metal chloride, but it is not limited to this; it can also be a transition metal oxide. The active material can increase the density of active sites and the surface reactivity.

[0079] In this embodiment, the transition metal chloride can specifically be ferric chloride, calcium chloride, copper chloride, aluminum chloride, etc.

[0080] In this embodiment, the transition metal oxide can specifically be aluminum oxide, copper oxide, cuprous oxide, etc.

[0081] In some embodiments, the solvent is ethanol, acetone or deionized water. The sieved powder is soaked in the solvent, washed, and then dried in a vacuum drying oven to obtain a silicon-carbon adsorbent.

[0082] The method for the refined utilization of waste silicon powder from the reduction furnace chassis in this embodiment has the following advantages:

[0083] (1) It can prevent spontaneous combustion and make refined use of waste silicon powder from the reduction furnace chassis, reduce the safety risks in the polysilicon production process, transform the waste silicon powder from the reduction furnace chassis into materials with certain value and uses, avoid the waste of resources, realize the recycling and sustainable development of resources, improve resource utilization efficiency and economic benefits, reduce the impact on the environment, reduce the processing cost, and thus solve a major problem faced by polysilicon production enterprises.

[0084] (2) Polyphosphazene can improve the surface area and pore structure of waste silicon powder in the reducing furnace chassis. Compared with traditional fire retardant additives, polyphosphazene will not reduce the mechanical properties of the material after treatment, such as strength and durability, thus improving its performance as an adsorbent or catalyst carrier.

[0085] (3) Polyphosphazene can increase the number and distribution of active sites in the waste silicon powder in the reduction furnace chassis, thereby improving its efficiency and selectivity in catalytic reactions.

[0086] (4) The waste silicon powder from the reduction furnace bottom after polyphosphazene treatment has higher chemical stability and can cope with complex industrial environments and reaction conditions.

[0087] Example 2

[0088] This embodiment discloses a system for the refined utilization of waste silicon powder from a reduction furnace chassis, which can be used in the method described in Embodiment 1. The system includes a silicon powder flame retardant device, an ashing treatment device, and a product preparation device, wherein:

[0089] The silicon powder flame retardant device is used to fully mix the waste silicon powder from the reduction furnace chassis with a certain proportion of polyphosphazene powder, so that the polyphosphazene powder is evenly covered on the surface of the waste silicon powder from the reduction furnace chassis to obtain mixed powder.

[0090] The ashing treatment device is connected to the silicon powder flame retardant device. It is used to receive the mixed powder obtained by the silicon powder flame retardant device and ashing it under high temperature conditions. After cooling, carbonized blocks are obtained.

[0091] The product preparation device is connected to the ashing treatment device and is used to grind and sieve the carbonized block material to obtain powder on the sieve and powder under the sieve. The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in solvent, washed, and dried to obtain a silicon-carbon adsorbent.

[0092] In some embodiments, the silicon powder flame retardant device includes a waste silicon powder tank, a feeding device, and a mixing device, wherein:

[0093] Waste silicon powder tank, used to connect to the reduction furnace in the cold hydrogenation production process to receive waste silicon powder from the furnace chassis;

[0094] The feeding equipment, connected to the waste silicon powder tank, has a powder conveying mechanism and an accurate weighing mechanism, used to add a certain proportion of polyphosphazene powder to the waste silicon powder tank;

[0095] The mixing equipment, connected to the waste silicon powder tank, is used to fully mix the waste silicon powder and polyphosphazene powder in the reduction furnace chassis of the waste silicon powder tank to obtain mixed powder.

[0096] In some embodiments, the ashing treatment apparatus includes heating equipment, an ashing chamber, and atmosphere control equipment, wherein:

[0097] The ashing chamber is connected to the outlet of the waste silicon powder tank in the silicon powder flame retardant device. It is used to receive the mixed powder output by the silicon powder flame retardant device and provide an ashing treatment site.

[0098] Heating equipment, connected to the ashing chamber, is used to heat the ashing chamber to reach the high temperature conditions required for ashing treatment;

[0099] Atmosphere control equipment, connected to the ashing chamber, is used to introduce nitrogen or inert gas into the ashing chamber to adjust the atmosphere inside the ashing chamber to the atmospheric conditions required for the ashing process.

[0100] In some embodiments, the ashing process apparatus further includes a safety device, which includes a temperature sensor located inside the ashing apparatus to monitor the internal temperature of the ashing apparatus and to issue an alarm when the temperature exceeds a preset temperature threshold, so as to ensure that the ashing temperature is not too high.

[0101] In some embodiments, the product preparation apparatus includes grinding equipment, sieving equipment, a first surface treatment device, and a second surface treatment device, wherein:

[0102] The grinding equipment is connected to the discharge port of the ashing chamber in the ashing treatment device and is used to grind carbonized lumps.

[0103] Screening equipment, connected to grinding equipment, is used to screen the ground carbonized lumps to obtain powder over the screen and powder under the screen;

[0104] The first surface treatment equipment is used to load active materials onto the surface of powder on a sieve to prepare a silicon-carbon catalyst.

[0105] The second surface treatment equipment is used to soak the sieved powder in solvent, then wash and dry it to obtain silicon-carbon adsorbent.

[0106] In some embodiments, the product preparation apparatus also includes quality inspection equipment, specifically including laser particle size analyzers, inductively coupled plasma mass spectrometers, etc.

[0107] Example 3

[0108] This embodiment discloses a method for the refined utilization of waste silicon powder from a reduction furnace chassis, which employs the system described in Embodiment 2, and includes the following steps:

[0109] (1) Pass the waste silicon powder from the bottom of the reduction furnace into the waste silicon powder tank. The average particle size of the waste silicon powder is about 20 micrometers. Add 10% of the weight of polyphosphazene powder to the waste silicon powder tank through the feeding device, and mix thoroughly using the mixing device so that the polyphosphazene powder evenly covers the surface of the waste silicon powder from the bottom of the reduction furnace to obtain mixed powder.

[0110] (2) The mixed powder is introduced into the ashing chamber. The ashing chamber is first heated to 800°C using a heating device, and then the ashing chamber is adjusted to a nitrogen atmosphere using an atmosphere control device. The mixture is then heated to the ashing temperature, which is set to 950±10°C and the ashing time is set to 18h. The mixed powder is ashed under pure nitrogen and high temperature conditions to completely remove organic components and residues, improve the purity and crystallinity of the product, and ensure its stability and reliability in subsequent applications. After the ashing process, the mixture is cooled at 25°C and atmospheric pressure for 10 hours to obtain carbonized blocks.

[0111] In this process, elemental composition was analyzed using inductively coupled plasma mass spectrometry before and after ashing to obtain the changes in impurities before and after ashing. Figure 2 As shown.

[0112] Depend on Figure 2 It can be seen that after ashing treatment, the content of metal impurities is significantly reduced, which has the following advantages:

[0113] 1. Improve material purity and quality: The carbonization process can effectively remove metallic impurities such as iron, copper, and aluminum from silicon powder. This purification effect significantly improves the purity of silicon powder, enabling the final product to achieve higher performance and reliability in demanding applications such as chemical and electronic industries.

[0114] 2. Improved physical and chemical properties of materials: By reducing metallic impurities, carbide silicon powder typically exhibits more stable and controllable physical and chemical properties. For example, in electronic devices, reducing impurities can decrease electron migration and loss, and improve the material's electrical conductivity and thermal stability.

[0115] 3. Enhanced material processing and application performance: Silicon powder with low impurity content is easier to process and shape, for example, when preparing complex shapes or high-precision parts, it can provide more stable process parameters and finished product quality.

[0116] (3) Use a ball mill to grind the carbonized lumps, and then use a vibrating screen to screen the ground powder to accurately control the particle size and distribution of the powder and ensure that the product meets the precise technical requirements. The particle size of the ground powder is controlled at 5-10 μm, and the mesh size of the vibrating screen is 80 mesh.

[0117] (4) The impregnation method is used to load metal chloride (such as ferric chloride) onto the surface of the powder on the sieve, and then dry it quickly to obtain silicon carbon catalyst. The rapid drying is carried out at a low temperature of no more than 100°C to avoid unnecessary decomposition and failure of the material and to ensure stability. The powder under the sieve is soaked in deionized water, washed, and dried to obtain silicon carbon adsorbent.

[0118] The particle size distribution of the silicon-carbon catalyst was determined using a laser particle size analyzer. Figure 3 As shown, the particle size of silicon-carbon catalysts ranges from 80 to 1500 micrometers, with most particles distributed around 800 micrometers, offering the following advantages:

[0119] 1. High physical stability and durability: Larger particle size usually means higher physical strength and stability. This characteristic allows the catalyst to maintain its shape and activity during long-term operation, reducing problems caused by particle wear or breakage.

[0120] 2. Excellent mass transfer performance: Large-particle-size silicon-carbon catalysts help improve the diffusion and mass transfer performance of fluids on their surface, which is crucial for efficient reaction processes. They can increase the contact area between reactants and catalyst particles, thereby improving reaction rate and selectivity.

[0121] 3. Suitable for industrial-scale applications: The main particle size distribution of around 800 micrometers is suitable for industrial-scale reactor or fixed-bed applications. Particles of this size typically have good hydrodynamic properties and can maintain stable reaction conditions in large-scale production.

[0122] 4. Easy to handle and fill: The larger particle size makes the silicon-carbon catalyst easier and more controllable in the filling and handling process, reducing dust and operational difficulties caused by the small particle size;

[0123] 5. Reduced pressure drop and drag: Relatively large particle size usually means lower pressure drop and drag when liquid or gas flows through, which helps reduce energy consumption and operating costs.

[0124] The particle size distribution of the silicon-carbon adsorbent was determined using a laser particle size analyzer. Figure 4 As shown, the particle size of silicon-carbon adsorbents ranges from 1 to 500 micrometers, with most particles distributed around 50 micrometers, offering the following advantages:

[0125] 1. Good uniformity and dispersibility: The particle size distribution of about 50 micrometers means that the particle size is relatively uniform, which is conducive to obtaining more stable and predictable performance in applications. This uniformity helps to ensure the consistency and repeatability of the adsorbent in industrial production.

[0126] 2. Balance between high surface area and adsorption capacity: Silicon-carbon adsorbents with a particle size distribution of around 50 micrometers typically offer a high surface area while maintaining good diffusion properties. This balance allows the adsorbent to efficiently adsorb target molecules or substances, making it suitable for applications requiring high-efficiency adsorption and regeneration.

[0127] 3. Excellent hydrodynamic properties: Medium-sized silicon-carbon adsorbents typically have good hydrodynamic properties, providing sufficient flowability for transport in reactors or fixed beds without causing excessive pressure drop or resistance.

[0128] 4. Wide range of applications: Due to its medium particle size, this silicon-carbon adsorbent is suitable for various gas and liquid separation, purification and catalytic reaction applications. It can effectively treat various fluids in different industrial processes and improve product purity and yield.

[0129] Example 4

[0130] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0131] Take 10g of the mixed powder (polyphosphazene and silicon powder) mixed in the specified ratio for testing, wherein the ashing temperature is 800℃.

[0132] Example 5

[0133] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0134] Take 10g of the mixed powder (polyphosphazene and silicon powder) blended in the specified ratio for testing, wherein the ashing temperature is 1000℃.

[0135] Example 6

[0136] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0137] Take 10g of the mixed powder (polyphosphazene and silicon powder) blended in the specified ratio for testing, wherein the ashing temperature is 1200℃.

[0138] Example 7

[0139] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0140] Take 10g of the mixed powder (polyphosphazene and silicon powder) blended in the specified ratio for testing, wherein the ashing temperature is 1400℃.

[0141] The silicon powder recovery effect in Examples 4-7 was quantitatively analyzed, as follows:

[0142] The mass of the powder after ashing was measured, and the recovery rate of silicon powder at each temperature was calculated using the following formula:

[0143] Recovery rate (%) = (Final residual amount / Initial sample amount) * 100%;

[0144] The results are as follows Figure 5 As shown, the higher the polyphosphononitrile content, the better the fire retardant effect. When considering the fire retardant effect, it is necessary to select an appropriate ashing temperature and recovery rate to achieve the purpose of producing silicon-carbon catalysts and silicon-carbon adsorbents.

[0145] Example 8

[0146] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0147] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 1:1.

[0148] Example 9

[0149] This embodiment discloses a method for the refined utilization of waste silicon powder from the reduction furnace chassis, which differs from the method described in Embodiment 4 in that:

[0150] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 1:2.

[0151] Example 10

[0152] This embodiment discloses a method for the refined utilization of waste silicon powder from the reduction furnace chassis, which differs from the method described in Embodiment 4 in that:

[0153] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 1:3.

[0154] Example 11

[0155] This embodiment discloses a method for the refined utilization of waste silicon powder from the reduction furnace chassis, which differs from the method described in Embodiment 4 in that:

[0156] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 1:4.

[0157] Example 12

[0158] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0159] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 1:5.

[0160] Example 13

[0161] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0162] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 5:1.

[0163] Example 14

[0164] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0165] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 4:1.

[0166] Example 15

[0167] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0168] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 3:1.

[0169] Example 16

[0170] This embodiment discloses a method for the refined utilization of waste silicon powder from the bottom of a reduction furnace, which differs from the method described in Embodiment 3 in that:

[0171] The mass ratio of polyphosphazene powder to waste silicon powder from the reduction furnace is 2:1.

[0172] Comparative Example 1

[0173] The difference between Comparative Example 1 and Example 3 is as follows:

[0174] Silicon powder catalysts and silicon powder adsorbents are prepared directly from waste silicon powder from the reduction furnace chassis without adding polyphosphazene powder.

[0175] The fire-resistant effects of Examples 8-16 are analyzed below, and the analysis method is as follows:

[0176] (1) Data comparison: Compare the recovery rates of different mixing ratios at various temperatures. Higher recovery rates generally result in higher fire resistance ratings;

[0177] (2) Scoring Criteria: Set a standard and score based on the recovery rate. For example... Figure 5 As shown, a recovery rate greater than 70% is rated 4, a recovery rate of 60%-70% is rated 3, and a recovery rate less than 60% is rated 2.

[0178] The advantages and disadvantages of different blending ratios (polyphosphononitrile:silicon powder) were evaluated, and the results are as follows:

[0179] When the mixing ratio is 1:1, the advantages are strong material properties and high stability, while the disadvantage is higher cost.

[0180] When the mixing ratio is 1:2, the cost is controlled and the performance is good, but the disadvantage is that the material stability decreases.

[0181] When the mixing ratio is 1:3, the cost-effectiveness is significant and the performance is moderate.

[0182] When the mixing ratio is 1:4, the cost-effectiveness is high, but the disadvantages are insufficient performance and poor stability.

[0183] When the mixing ratio is 1:5, the processing cost is the lowest, but the disadvantage is that the performance of silicon-carbon adsorbents and silicon-carbon catalysts is greatly reduced.

[0184] When the mixing ratio is 5:1 to 2:1, the fire-retardant properties are excellent and it is easy to transport. However, the amount of polyphosphonic acrylonitrile added is too high at this time, which is not suitable for making silicon-carbon adsorbents and silicon-carbon catalysts. Moreover, the cost is too high. A higher proportion of polyphosphonic acrylonitrile has lower practical value.

[0185] In summary, a high recovery rate indicates good material stability, thereby reducing material waste during the carbonization process. Optimizing the mixing ratio and temperature conditions helps improve the material's utilization efficiency and economy. Considering both performance and cost, a polyphosphazene:silica powder ratio of 1:3 is the optimal mixing ratio.

[0186] Under the same conditions, the performance of the silicon-carbon catalytic activity and silicon-carbon adsorbent prepared in Examples 8-16 and Comparative Example 1 were tested. The tests covered multiple aspects such as catalytic activity and adsorption performance to ensure that the product quality met the standards. The results of the silicon-carbon catalysts prepared in Examples 8-16 reducing carbonyl compounds to alcohols (such as reducing acetaldehyde to ethanol) are shown in Table 1. The results of the silicon-carbon adsorbents prepared in Examples 8-16 adsorbing nitrogen are shown in Table 2.

[0187] Table 1

[0188]

[0189]

[0190] As shown in Table 1, the silicon-carbon catalysts prepared in Examples 3-16 exhibit significantly better performance in terms of conversion rate, selectivity, reusability, and activity than the silicon-carbon catalyst prepared in Comparative Example 1. This demonstrates that the waste silicon powder from the reduction furnace chassis is ineffective when used alone in catalytic reactions. The method of this invention improves the performance of the waste silicon powder from the reduction furnace chassis as a catalyst carrier, enhancing its efficiency and selectivity in catalytic reactions. Furthermore, the silicon-carbon catalysts prepared in Examples 3-16 meet the performance requirements of common activated carbon or silicon-carbon catalysts, further proving the effectiveness of the method of this invention. This method can convert waste silicon powder from the reduction furnace chassis into silicon-carbon catalysts with certain application value and uses, thereby avoiding resource waste, realizing resource recycling and sustainable development, improving resource utilization efficiency and economic benefits, reducing negative environmental impacts, and lowering processing costs. This technology provides a solution for polysilicon production enterprises, helping to address their resource waste problems.

[0191] Table 2

[0192]

[0193]

[0194] As shown in Table 2, the silicon-carbon adsorbents prepared in Examples 3-16 exhibit significantly better performance indicators, such as rate constants, than the silicon-carbon adsorbent prepared in Comparative Example 1. This indicates that the waste silicon powder from the reduction furnace chassis performs poorly in terms of adsorption performance when used alone. The method of this invention improves the performance of the waste silicon powder from the reduction furnace chassis as an adsorbent carrier. Furthermore, the silicon-carbon adsorbents prepared in Examples 3-16 meet the performance requirements of common silicon-carbon adsorbents. Therefore, the method of this invention can convert waste silicon powder from the reduction furnace chassis into silicon-carbon adsorbents with certain application value and uses, thereby avoiding resource waste, realizing resource recycling and sustainable development, improving resource utilization efficiency and economic benefits, reducing environmental impact, and lowering processing costs. This solves a major problem faced by polysilicon production enterprises.

[0195] It is understood that the above embodiments are merely exemplary embodiments 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 the refined utilization of waste silicon powder from a reduction furnace chassis, characterized in that, include: A certain proportion of polyphosphazene powder is added to the waste silicon powder in the reduction furnace chassis and mixed thoroughly so that the polyphosphazene powder evenly covers the surface of the waste silicon powder in the reduction furnace chassis, thus obtaining a mixed powder. The mixed powder was ashed at high temperature and then cooled to obtain carbonized lumps. The carbonized lumps are ground and sieved to obtain powder that is sieved over the sieve and powder that is sieved under the sieve. The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in a solvent, washed, and dried to obtain a silicon-carbon adsorbent.

2. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The waste silicon powder in the reduction furnace chassis accounts for 20% to 80% of the total mass of the mixed powder.

3. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The polyphosphononitrile is one or more of polyphenoxyphosphononitrile, poly(p-methylphenoxyphosphononitrile), and poly(trifluoroethoxyphosphononitrile).

4. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The particle size of the polyphosphazene powder is 10–100 nm.

5. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The ashing treatment is carried out at a temperature of 800℃ to 1400℃, at a pressure of atmospheric pressure, and for a time of 12 to 24 hours.

6. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The ashing process is carried out in a nitrogen or inert gas atmosphere.

7. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The grinding refers to grinding the carbonized blocky material to 20-160 mesh; The sieving refers to passing the ground carbonized lumps through an 80-mesh sieve to obtain powder larger than 80 mesh and powder smaller than or equal to 80 mesh.

8. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The active substance is a transition metal chloride or a transition metal oxide.

9. The method for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 1, characterized in that, The solvent is ethanol, acetone, or deionized water.

10. A system for the refined utilization of waste silicon powder from a reduction furnace chassis, characterized in that, It includes a silicon powder flame retardant device (2), an ashing treatment device (6), and a product preparation device (10), wherein: The silicon powder flame retardant device is used to fully mix the waste silicon powder from the reduction furnace chassis with a certain proportion of polyphosphazene powder, so that the polyphosphazene powder is evenly covered on the surface of the waste silicon powder from the reduction furnace chassis to obtain mixed powder. The ashing treatment device is connected to the silicon powder flame retardant device, and is used to receive the mixed powder obtained by the silicon powder flame retardant device, and to ashing the powder under high temperature conditions, and to obtain carbonized blocky material after cooling. The product preparation device is connected to the ashing treatment device and is used to grind and sieve the carbonized block to obtain powder on the sieve and powder under the sieve. The active material is loaded onto the surface of the powder on the sieve to obtain a silicon-carbon catalyst. The powder under the sieve is soaked in solvent, washed, and dried to obtain a silicon-carbon adsorbent.

11. The system for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 10, characterized in that, The silicon powder flame retardant device includes a waste silicon powder tank (11), a feeding device (1), and a mixing device (3). The waste silicon powder tank is used to connect to the reduction furnace in the cold hydrogenation production process to receive waste silicon powder from the bottom of the reduction furnace. The feeding device is connected to the waste silicon powder tank and is used to add a certain proportion of polyphosphazene powder to the waste silicon powder tank. The mixing device is connected to the waste silicon powder tank and is used to fully mix the waste silicon powder from the reduction furnace chassis in the waste silicon powder tank with the polyphosphazene powder to obtain mixed powder.

12. The system for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 10, characterized in that, The ashing treatment apparatus includes a heating device (7), an ashing chamber (5), and an atmosphere control device (12). The ashing chamber is connected to the silicon powder flame retardant device and is used to receive the mixed powder output by the silicon powder flame retardant device and provide an ashing treatment site. The heating equipment is connected to the ashing chamber and is used to heat the ashing chamber to reach the high temperature conditions required for the ashing process. The atmosphere control device is connected to the ashing chamber and is used to introduce nitrogen or inert gas into the ashing chamber to adjust the atmosphere inside the ashing chamber to the atmospheric conditions required for the ashing process.

13. The system for the refined utilization of waste silicon powder from the reduction furnace chassis according to claim 10, characterized in that, The product preparation apparatus includes a grinding device (8), a sieving device (15), a first surface treatment device, and a second surface treatment device. The grinding equipment is connected to the discharge port of the ashing chamber in the ashing treatment device and is used to grind the carbonized blocky material. The screening equipment is connected to the grinding device and is used to screen the ground carbonized lumps to obtain powder on the sieve and powder under the sieve. The first surface treatment equipment is used to load active materials onto the surface of powder on a sieve to obtain a silicon-carbon catalyst; The second surface treatment equipment is used to soak the sieved powder in a solvent, then wash and dry it to obtain a silicon-carbon adsorbent.

14. The system for the refined utilization of waste silicon powder from the reduction furnace chassis according to any one of claims 10-13, characterized in that, The system also includes a safety device (14), The safety device includes a temperature sensor located inside the ashing device. It is used to monitor the internal temperature of the ashing device and to issue an alarm when the temperature exceeds a preset temperature threshold, so as to ensure that the ashing temperature is not too high.

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