Method, device and system for purifying regenerated silicon material

Abstract

The invention discloses a regenerated silicon material purification method, device and system, and the method comprises the steps: obtaining a silicon material-container unit, the silicon material-container unit comprises a sealed container and a regenerated silicon material placed in the sealed container, and the bottom of the sealed container is provided with a microporous sieve plate unit; continuously heating the regenerated silicon material in the silicon material-container unit to obtain molten silicon liquid; blowing preparatory gas into the molten silicon liquid through a microporous sieve plate unit; and judging whether the duration of blowing the preparatory gas meets a first preset condition or not, and if so, ending blowing and heating to solidify the silicon liquid to obtain purified polycrystalline silicon. The method for purifying the regenerated silicon material can realize full contact between the reaction gas and the silicon liquid, so that the impurity removal effect is effectively improved.

Description

Technical Field

[0001] The present invention specifically relates to a method, device and system for purifying recycled silicon material. Background Art

[0002] Considering production cost, energy consumption, environmental protection and safety, physical methods for purifying silicon materials have more advantages than chemical methods. At present, the physical methods for purifying silicon materials mainly include pickling, vacuum melting, electron beam refining, ion beam refining, air blowing refining, slag refining, directional solidification, etc. The usual physical method is to use a combination of the above methods to achieve the purpose of purifying silicon materials. Among them, the air blowing method uses argon as a carrier gas, and passes a certain type and amount of reaction gas and reaction material powder into the purification furnace at a certain flow rate and pressure. By strictly controlling the reaction gas composition, air blowing speed and thermal field distribution, the purpose of removing impurities in the silicon material is achieved. However, this method has the problem that the reaction gas is not in sufficient contact with liquid silicon (i.e., silicon liquid in a molten state), resulting in incomplete impurity removal. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method, device and system for purifying regenerated silicon material in view of the above-mentioned deficiencies in the prior art. The method for purifying regenerated silicon material can achieve sufficient contact between the reaction gas and the silicon liquid, thereby effectively improving the impurity removal effect.

[0004] According to an embodiment of the first aspect of the present invention, there is provided a method for purifying regenerated silicon material, comprising: obtaining a silicon material-container unit, the silicon material-container unit comprising a sealed container and regenerated silicon material placed in the sealed container, the sealed container being provided with a microporous sieve plate unit at the bottom; continuously heating the regenerated silicon material in the silicon material-container unit to obtain molten silicon liquid; blowing a preliminary gas into the molten silicon liquid through the microporous sieve plate unit; judging whether the duration of blowing the preliminary gas meets a first preset condition, and if so, terminating the blowing and heating to solidify the silicon liquid to obtain purified polycrystalline silicon.

[0005] Preferably, the obtaining of the silicon material-container unit comprises: cleaning the waste silicon material to obtain preliminarily cleaned silicon material; placing the preliminarily cleaned silicon material into a sealed container and performing aeration purification to obtain the silicon material-container unit.

[0006] Preferably, the silicon material after preliminary cleaning is placed in a sealed container and aerated and purified to obtain a silicon material-container unit, comprising:

[0007] Place the preliminarily cleaned silicon material into a sealed container;

[0008] The inside of the sealed container is vacuumed and inflated;

[0009] Determine whether the number of vacuuming-inflating operations meets a second preset condition, and if so, end the vacuuming-inflating operation to obtain a silicon material-container unit;

[0010] The vacuuming and inflating operation is performed on the inside of the sealed container, specifically:

[0011] Vacuuming the interior of the sealed container to obtain a vacuumed sealed container;

[0012] Argon gas is filled into the vacuum-evacuated sealed container, and the vacuum-evacuation-filling operation is completed.

[0013] Preferably, the first preset condition is that the duration of blowing the preparatory gas reaches 1-3 hours; the second preset condition is that the number of vacuuming-inflation operations is greater than or equal to 5 times.

[0014] Preferably, the regenerated silicon material in the silicon material-container unit is continuously heated to obtain molten silicon liquid, specifically: the regenerated silicon material is heated to a preset temperature range, and the regenerated silicon material is maintained within the preset temperature range to obtain molten silicon liquid.

[0015] Preferably, the microporous sieve plate unit includes an air inlet and a microporous sieve plate installed on the air inlet, the microporous sieve plate is provided with a plurality of micropores, the micropores extend in a vertical direction and penetrate the microporous sieve plate body; the step of blowing the prepared gas into the molten silicon liquid through the microporous sieve plate unit includes: heating the mixed gas to a preset temperature and keeping it warm to obtain the prepared gas, wherein the mixed gas is a mixed gas of argon and oxygen; blowing the prepared gas into the molten silicon liquid through the air inlet and the micropores on the microporous sieve plate; the method also includes: while blowing the prepared gas into the molten silicon liquid through the air inlet and the micropores on the microporous sieve plate, evacuating the inner cavity of the sealed container.

[0016] According to an embodiment of the second aspect of the present invention, a regenerated silicon material purification device is provided, comprising: a first execution device, a second execution device, a third execution device and a judgment unit. The first execution device is used to obtain a silicon material-container unit. The silicon material-container unit comprises a sealed container and a regenerated silicon material placed in the sealed container, and a microporous sieve plate unit is provided at the bottom of the sealed container, and the microporous sieve plate unit comprises an air inlet and a microporous sieve plate installed on the air inlet. The second execution device is used to continuously heat the regenerated silicon material in the silicon material-container unit to obtain a molten silicon liquid. The third execution device is used to blow a preliminary gas into the molten silicon liquid through the microporous sieve plate unit. The judgment unit is electrically connected to the second execution device and the third execution device, and is used to judge whether the duration of blowing the preliminary gas meets the first preset condition. If so, the second execution device and the third execution device are respectively controlled to end the blowing and heating, so that the silicon liquid solidifies to obtain the purified polysilicon.

[0017] According to an embodiment of the third aspect of the present invention, a system for purifying recycled silicon material is provided, comprising: a sealed container, a microporous sieve plate and the above-mentioned device for purifying recycled silicon material. The internal cavity of the sealed container is used to accommodate recycled silicon material, the bottom of the sealed container is opened at the air inlet, and the microporous sieve plate is installed on the air inlet. The microporous sieve plate is provided with a plurality of micropores, and the micropores extend in the vertical direction and penetrate the body of the microporous sieve plate. The device for purifying recycled silicon material is used to perform the above-mentioned method for purifying recycled silicon material.

[0018] Preferably, the micropore diameter of the microporous sieve plate is 0.1-50 μm, and the pore sizes of the multiple micropores on the microporous sieve plate are coupled to the thermal field distribution in the sealed container.

[0019] Preferably, both ends of the plurality of micropores on the microporous sieve plate are provided with protrusions.

[0020] The regenerated silicon material purification method of the present invention is based on the purification of silicon material by air blowing refining method, and adds a micro-nano sieve plate (i.e., microporous sieve plate) structure at the air blowing port to perform micro-nano segmentation of the airflow, so that the gas dissolution rate of the blown gas in the molten silicon liquid is faster and the residence time is longer, which greatly increases the contact area and action time of the gas and liquid, thereby increasing the mass transfer efficiency, and is more conducive to the separation of impurities and silicon materials under the action of the gas, thereby greatly increasing the impurity removal efficiency of the silicon material. In summary, the present regenerated silicon material purification method can achieve full contact between the reaction gas and the silicon liquid, thereby effectively improving the impurity removal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a silicon material-container unit in some embodiments of the present invention;

[0022] Figure 2a is a schematic structural diagram of a microporous sieve plate without protrusions in some embodiments of the present invention;

[0023] Figure 2b Schematic diagram of the structure of a microporous sieve plate with protrusions in some embodiments of the present invention.

[0024] In the figure: 1-air outlet, 2-heating and heat-insulating layer, 3-air inlet, 4-bracket, 5-microporous sieve plate, 51-micropores, 52-protrusions, 6-silicon liquid, 7-stirring paddle. DETAILED DESCRIPTION

[0025] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of the present invention.

[0026] In the description of the present invention, the terms “first” and “second” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0027] In the description of the present invention, each unit and module involved may correspond to only one physical structure, or may be composed of multiple physical structures, or multiple units and modules may be integrated into one physical structure; the units and modules involved may be implemented by software or by hardware, for example, the units and modules may be located in a processor.

[0028] In the description of the present invention, the functions and steps marked in the flowcharts and block diagrams of the present invention may occur in an order different from that marked in the drawings if there is no conflict.

[0029] First, the current status of the development of the purification technology of recycled silicon materials is explained: Solar energy is a widely distributed clean energy. Solar cells are devices that convert solar energy into electrical energy. In recent years, due to the proposal of the "dual carbon strategy", the production and application of polysilicon solar cells have developed rapidly, resulting in a sharp increase in the demand for silicon materials and huge consumption. At present, the production of polysilicon mainly adopts the modified Siemens method, including cold hydrogenation, distillation purification, reduction and other processes. This method is the most mature, widely used and fastest expanding technology. However, in the production process, the cold hydrogenation external cyclone separation device and the reduction finished product dust removal device will produce a large amount of waste silicon powder. Taking the production of 90,000 tons of polysilicon per year as an example, about 3,240 tons of waste silicon powder will be produced per year, which not only pollutes the environment but also causes great waste of resources. In addition, the recycling of waste solar cell modules will also produce a large amount of waste silicon materials. Therefore, it is of great research value to purify and recycle waste silicon materials.

[0030] Considering production cost, energy consumption, environmental protection and safety, physical methods for purifying silicon materials have more advantages than chemical methods. At present, the physical methods for purifying silicon materials mainly include pickling, vacuum melting, electron beam refining, ion beam refining, air blowing refining, slag refining, directional solidification, etc. The usual physical method is to use a combination of the above methods to achieve the purpose of purifying silicon materials. Among them, the air blowing method uses argon as a carrier gas, and a certain type and amount of reaction gas and reaction material powder are passed into the purification furnace at a certain flow rate and pressure. By strictly controlling the reaction gas composition, air blowing speed and thermal field distribution, the purpose of removing impurities in the silicon material is achieved. However, this method (air blowing method) still has the problem of insufficient contact between gas and liquid silicon and incomplete impurity removal.

[0031] Example 1

[0032] See also Figure 1 The present invention discloses a method for purifying recycled silicon material, comprising the following steps:

[0033] A silicon material-container unit is obtained, wherein the silicon material-container unit includes: a sealed container and a recycled silicon material placed in the sealed container, a microporous sieve plate 5 unit is provided at the bottom of the sealed container, and the microporous sieve plate 5 unit includes an air inlet 3 and a microporous sieve plate 5 installed on the air inlet 3.

[0034] The regenerated silicon material in the silicon material-container unit is continuously heated to obtain a molten silicon liquid 6 .

[0035] A preliminary gas is blown into the molten silicon liquid 6 through the microporous sieve plate 5 unit.

[0036] It is determined whether the duration of blowing the preliminary gas meets the first preset condition. If so, the blowing and heating are terminated to solidify the silicon liquid 6 to obtain purified polysilicon. The first preset condition is that the duration of blowing the preliminary gas reaches 1-3 hours.

[0037] It can be seen that the present method for purifying recycled silicon materials is an air blowing refining method that can be used for impurity removal and purification of recycled silicon materials. By providing an air blowing smelting method that can be used for impurity removal and purification of recycled silicon materials and combined with a micro-nano sieve plate structure, it is expected to more thoroughly remove impurities in the molten silicon material, and further improve the impurity removal efficiency of the air blowing method and the purity of the silicon material.

[0038] First, the principle of purifying silicon materials by the air blowing refining method in this method is explained: using argon as a carrier gas, a certain type and amount of reaction gas (oxygen, etc. can be used) or reaction material powder is introduced into the purification furnace at a certain flow rate and pressure, and the reaction gas reacts with the impurities in the molten silicon liquid 6 to generate volatile gas or slag phase. Generally speaking, light impurities are entrained by bubbles and float up, and heavy solid impurities (slag phase) sink, so as to achieve the effect of separating light and heavy impurities. Exemplarily, common impurities in recycled silicon materials mainly include: volatile impurities such as oxygen (O), carbon (C), nitrogen (N), phosphorus (P); and metal impurities such as iron (Fe), nickel (Ni), copper (Cu), aluminum (Al), and calcium (Ca) (metal impurities will generate a heavier solid slag phase through reaction).

[0039] By evacuating the sealed container (i.e. the graphite crucible in the refining furnace), these impurity gases can be discharged from the graphite crucible, thereby completing the removal of the impurity gases. After stopping the heating, directional solidification can be combined at the same time to make most of the impurities gather at both ends of the solidified silicon, forming a separation state of impurities-silicon-impurities, so as to facilitate the next step of impurity separation. In other words, after the polysilicon solidifies into a silicon ingot, there will be some light phase impurities and defects such as pits caused by the precipitation of bubbles on the top of the silicon ingot; while the heavy solid impurities are deposited at the bottom, that is, the slag phase condenses at the bottom of the silicon ingot. After taking out the silicon ingot, remove the head, tail and surrounding areas with high impurity content to obtain high-purity polysilicon.

[0040] The problem with the existing air blowing refining method is that the introduced mixed gas (referring to the mixed gas of carrier gas and reaction gas) will be concentrated in the part facing the air blowing port, that is, the distribution of the gas flow beam in the silicon melt is uneven and too concentrated; this easily leads to good refining effect in some areas, while other areas may be insufficiently refined. This unevenness will affect the overall quality of the recycled silicon material and reduce the uniformity and stability of the product.

[0041] Based on the air blowing refining method for purifying silicon materials, this method adds a micro-nano sieve plate (i.e., microporous sieve plate 5) structure at the air blowing port to perform micro-nano segmentation of the airflow, so that the gas dissolved in the molten silicon liquid 6 by the blown gas is faster and the residence time is longer, which greatly increases the contact area and action time of the gas and liquid, thereby increasing the mass transfer efficiency, and is more conducive to the separation of impurities and silicon materials under the action of the gas, thereby greatly increasing the impurity removal efficiency of the silicon material.

[0042] Specifically, in the air blowing refining method, by providing a microporous sieve plate 5 at the air inlet 3, fine segmentation of the air flow can be achieved. The benefits brought by this segmentation are mainly reflected in the following aspects:

[0043] First, the microporous sieve plate 5 can divide the incoming airflow into numerous tiny bubbles. During the rising process, these tiny bubbles have a larger contact area and a longer contact time with the impurity particles in the regenerated silicon material. As the contact area increases, the probability of the impurity particles being captured and carried away by the bubbles also increases, thereby improving the impurity removal efficiency.

[0044] Secondly, due to the effect of surface tension, the tiny bubbles will remain relatively stable during the rising process and are not easy to merge into large bubbles or larger airflow beams. This stability is conducive to the uniform distribution of the reaction gas in the regenerated silicon material, making the airflow distribution more uniform during the entire refining process. The uniform airflow distribution can ensure that each part of the regenerated silicon material can be fully refined, avoiding the problem of insufficient local refining.

[0045] Finally, the use of the microporous sieve plate 5 can also reduce the impact force and turbulence of the airflow to a certain extent. In the absence of a sieve plate, the airflow directly introduced may produce a large impact force and turbulence, causing certain scouring and damage to the recycled silicon material. However, the tiny bubbles separated by the sieve plate are relatively mild, and have less scouring and damage to the material, which is conducive to protecting the integrity and structural stability of the recycled silicon material.

[0046] Specifically, the micro-nano sieve plate (i.e., the microporous sieve plate 5, the micro-nano sieve plate in the following text can be understood as the microporous sieve plate 5) is made of a material that is resistant to high temperatures (above 1410°C) and is not easy to react with silicon. Such materials include but are not limited to quartz, graphite (silicon nitride coating is coated on the outside of the micro-nano sieve plate made of graphite), silicon carbide, etc. The aperture range of the micropores 51 of the micro-nano sieve plate is 0.1 to 50 μm. Within this aperture range, it can be ensured that the blowing airflow is divided into micro-nano-scale airflow and bubbles, greatly increasing the gas-liquid contact area and action time. For example, the apertures of the micropores 51 of the micro-nano sieve plate are 0.1, 20, 30, and 50 μm.

[0047] It is worth noting that Figure 1 As shown, the air inlet 3 is directly opposite to the middle of the sieve plate. Since the sieve plate is a micro-nano hole with a small enough pore size, a certain pressure will be formed between the air inlet and the sieve plate during the blowing process, and the passage of the gas through the sieve plate will be delayed, so that the gas can be discharged evenly from the sieve plate, that is, the prepared gas can pass through the sieve plate evenly, rather than just through the middle of the sieve plate.

[0048] On the one hand, the volatile impurities in the silicon liquid are brought to the outlet for discharge through the air blowing and vacuuming process; on the other hand, the gas blown in the refining furnace is divided by the micro-nano sieve plate to form micro-nano airflow and bubbles, which greatly increase the contact area and action time between the blown gas and the molten liquid silicon, so that more impurities are gathered at the gas-liquid interface and are brought to the surface of the liquid silicon as the bubbles rise, thereby increasing the gas impurity removal efficiency and improving the purity of polysilicon.

[0049] It should be noted that, since the thermal field distribution in the refining furnace (sealed container) is usually not uniform, the apertures of the multiple micropores 51 on the micro-nano sieve plate also need to be adjusted according to the thermal field distribution in the furnace, so not all micropores 51 have the same aperture, that is, the aperture sizes of the multiple micropores 51 on the microporous sieve plate 5 are coupled to the thermal field distribution in the sealed container. The specific aperture distribution principle is: in the area with higher temperature in the furnace, the melting state of the recycled silicon material is better, and the corresponding sieve plate micropore 51 can be set with a larger aperture.

[0050] The larger pore size allows more airflow to pass through, increasing the contact area and contact time between the airflow and the recycled silicon material. In the case of a good molten state, this increased contact opportunity can more effectively remove impurities and improve refining efficiency.

[0051] As an example, Figure 1 As shown, in the refining furnace, an induction coil is used as a heating device, and the heating device surrounds the graphite crucible. When the induction coil heats the regenerated silicon material in the graphite crucible, the temperature of the regenerated silicon material in the middle area of ​​the graphite crucible (set as the first area) is higher, while the temperature of the regenerated silicon material in the area close to the side wall (set as the second area) is lower. According to the thermal field distribution, the microporous sieve plate 5 is divided into a first area and a second area, which correspond to the area with relatively high temperature and the area with relatively low temperature of the thermal field, respectively. The first area is located in the middle of the microporous sieve plate 5, and the second area surrounds the first area. The aperture of the micropores 51 on the first area is larger than the aperture of the micropores 51 on the second area. Specifically, the ratio between the radius of the first area of ​​the microporous sieve plate 5 and the radius of the microporous sieve plate 5 as a whole is 4:10-6:10. At this time, the aperture of the micropores 51 corresponding to the first area is designed to be 50μm; the aperture of the micropores 51 corresponding to the second area is designed to be 20μm.

[0052] In some embodiments, both ends of the micropores 51 of the microporous sieve plate 5 are flush with the surface of the body of the microporous sieve plate 5. In other embodiments, protrusions 52 are provided on both ends of the micropores 51 of the microporous sieve plate 5 to slightly increase the pressure on the divided airflow and bubbles.

[0053] In other words, the micro-nano sieve plate structure (i.e., the microporous sieve plate 5) refers to a detachable sieve plate (realized by the bracket 4) structure including but not limited to quartz, graphite (covered with silicon nitride coating), silicon carbide and other high temperature resistant (above 1410°C) materials that do not react with silicon, with a pore size distribution range of 0.1 to 50 μm, different hole shapes, hole protrusions 52 on both sides of the sieve plate with a height of 30 to 50 μm, and different positions (bottom, lower side wall, etc.) that match the size of the air blowing refining furnace and the thermal field distribution in the furnace.

[0054] It is worth noting that by setting the protrusions 52 at both ends of the micropores 51 of the microporous sieve plate 5, the airflow and bubbles after segmentation are slightly pressurized, further promoting the dissolution and impurity removal process of gas and liquid. The specific principle is explained as follows: When the airflow passes through the micropores 51 on the sieve plate, due to the geometric shape of the holes and the design of the protrusions 52, the airflow will shrink at the entrance of the holes, resulting in an increase in the local flow rate. According to the Bernoulli principle, the increase in flow rate will cause the static pressure at that place to decrease, thereby producing a certain negative pressure effect. At the hole outlet, due to the diffusion of the airflow and the slowdown of the flow rate, the static pressure gradually recovers. Therefore, a pressure difference from the entrance to the outlet will be formed inside the hole and near the outlet. This pressure difference will have a certain pressurization effect on the airflow passing through the hole. The design of the hole protrusion 52 can further enhance this pressurization effect. Because the protrusion 52 part can be regarded as a guide device, which guides the airflow through the hole in a more concentrated manner, thereby forming a more obvious pressure gradient inside the hole.

[0055] The following is an explanation of the production process of the micro-nano sieve plate:

[0056] Obtain thermal field distribution information of the substrate and the sealed container.

[0057] According to the thermal field distribution information of the sealed container, the pore size distribution parameters of the microporous sieve plate 5 are obtained.

[0058] The substrate is processed according to the pore size distribution parameters of the microporous sieve plate 5 to obtain the microporous sieve plate 5 .

[0059] It should be noted that the process of obtaining the substrate can adopt the existing mold pressing method. Specifically, the substrate can be made by mixing quartz powder (or graphite, silicon carbide, etc.) with a binder, placing the mixed material in a mold, and pressing to obtain a substrate that can match the size of the inner cavity of the sealed container. Mold pressing is an existing technology and will not be described in detail here.

[0060] Then, according to the thermal field distribution information in the refining furnace, the pore size distribution parameters on the microporous sieve plate 5 are determined. Specifically, the thermal field distribution information can be obtained by existing numerical simulation methods, such as computational fluid dynamics (CFD) or finite element method. Taking the CFD method as an example, the temperature field distribution in the furnace is obtained by establishing a geometric model, calculating initial conditions and boundary conditions, setting a numerical algorithm and solving a set of equations (the existing set of equations and numerical algorithms can be used). The thermal field distribution in the refining furnace can also be obtained by experimental methods, for example, by setting multiple temperature measuring points in the furnace, and measuring the temperature of each point in the graphite crucible of the refining furnace through the temperature measuring points, thereby obtaining the thermal field distribution therein.

[0061] Of course, the thermal field distribution in actual situations is more complicated, but overall, the closer the area to the center, the higher the temperature. In some embodiments, an induction coil is used as a heating device, and the heating device surrounds the graphite crucible. When the induction coil heats the regenerated silicon material in the graphite crucible, the temperature of the regenerated silicon material in the middle area of ​​the graphite crucible (set as the first area) is higher, while the temperature of the regenerated silicon material in the area close to the side wall (set as the second area) is lower. In order to simplify the manufacturing process of the microporous sieve plate 5, the microporous sieve plate 5 is divided into a first area and a second area according to the thermal field distribution information, corresponding to the area with relatively high temperature and the area with relatively low temperature of the thermal field, respectively. The first area is located in the middle of the microporous sieve plate 5, and the second area surrounds the first area. The aperture of the micropores 51 on the first area is larger than the aperture of the micropores 51 on the second area. Specifically, the ratio between the radius of the first area of ​​the microporous sieve plate 5 and the radius of the microporous sieve plate 5 as a whole is 4:10-6:10. The pore size of the micropores 51 corresponding to the first region is designed to be 50 μm; the pore size of the micropores 51 corresponding to the second region is designed to be 20 μm.

[0062] Further, according to the pore size distribution parameters, the substrate is processed to obtain a microporous sieve plate 5 that satisfies the pore size distribution. The existing laser processing technology can be used to process the micropores of the substrate, that is, through holes are processed on the substrate by laser. The processing of the surface protrusions 52 can be processed by the existing gas chemical etching technology, that is, the reserved part is removed by chemical etching technology to obtain the surface protrusion 52 part. Both laser processing technology and gas chemical etching technology belong to the existing technology and will not be repeated here.

[0063] In some embodiments, a layer of outer silicon nitride coating is also plated on the inner and outer sides of the microporous sieve plate 5 (for example, the microporous sieve plate 5 is made of graphite material). The silicon nitride coating can improve the high temperature resistance, hardness and wear resistance of the microporous sieve plate 5 and avoid silicon-carbon reaction.

[0064] So far, the manufacturing process of the microporous sieve plate 5 has been described in detail. Next, the microporous sieve plate 5 is installed on the bottom of the refining furnace.

[0065] Further, the time for blowing the prepared gas through the microporous sieve plate 5 unit needs to reach 1-3 hours. After the set time is reached, the heating and blowing are terminated. A blowing time that is too short may not be able to fully remove impurities, while a blowing time that is too long will increase unnecessary energy consumption and costs. Reasonable blowing time can reduce energy consumption and production costs while ensuring the refining effect, that is, it can ensure that the refining gas (such as oxygen, etc.) is in full contact with the impurity elements in the silicon liquid 6 and undergo a chemical reaction. This sufficient reaction time helps to improve the removal efficiency of impurities and reduce the impurity content in silicon. For example, the blowing time can be selected as 1 hour, 2 hours, or 3 hours. Preferably, the blowing time lasts for 3 hours.

[0066] The purification of the regenerated silicon material in the present invention refers to separating impurities from the regenerated silicon material by a micro-nano sieve plate air blowing refining method.

[0067] Furthermore, the above step of obtaining a silicon material-container unit includes:

[0068] Pretreatment: cleaning the waste silicon material to obtain preliminarily cleaned silicon material;

[0069] Purification: The silicon material after preliminary cleaning is placed in a sealed container and aerated and purified to obtain a silicon material-container unit.

[0070] First, the pretreatment process is to clean the waste silicon material. More specifically, the waste silicon material is cleaned and dried with deionized water. The cleaning process can effectively remove dirt, grease, oxides and other impurities on the surface of the waste silicon material.

[0071] Secondly, the atmosphere in the sealed container is purified. Specifically, the sealed container provides an environment that isolates the outside world from dust, moisture and harmful gases, effectively preventing the silicon material from being re-contaminated during subsequent storage or transportation. This is crucial to maintaining the cleanliness and quality of the silicon material. Furthermore, an inert gas (such as nitrogen, argon, etc.) or other specific gas is introduced to adjust the atmosphere in the container to facilitate the subsequent introduction of the prepared gas (i.e., a mixture of preheated carrier gas and reaction gas).

[0072] The purification step is further described as follows: the silicon material after preliminary cleaning is placed in a sealed container and aerated and purified to obtain a silicon material-container unit, including:

[0073] Place the preliminarily cleaned silicon material into a sealed container;

[0074] Perform vacuuming and gas filling operations on the inside of the sealed container;

[0075] It is determined whether the number of vacuuming-inflating operations meets the second preset condition. If so, the vacuuming-inflating operations are terminated to obtain a silicon material-container unit.

[0076] The second preset condition is that the number of vacuuming-inflation operations is greater than or equal to 7 times.

[0077] The inside of the sealed container is vacuumed and inflated, specifically:

[0078] Evacuating the interior of the sealed container to obtain a vacuumized sealed container;

[0079] Argon gas is filled into the vacuum-evacuated sealed container, and the vacuum-evacuation-filling operation is completed.

[0080] The atmosphere inside the sealed container was adjusted by simultaneously evacuating the air and filling it with argon.

[0081] In some embodiments, the regenerated silicon material in the silicon material-container unit is continuously heated to obtain the molten silicon liquid 6, specifically:

[0082] The regenerated silicon material is heated to a preset temperature range, and the regenerated silicon material is maintained within the preset temperature range to obtain a molten silicon liquid 6. The preset stable range needs to be at least higher than the melting temperature of the silicon material (about 1410°C). Therefore, in some embodiments, the preset temperature range is within 1500-1600°C. If the temperature is too low, the silicon material may not be able to maintain a good molten state, and if the temperature is too high, it may cause a waste of resources.

[0083] The above-mentioned step of blowing the preliminary gas into the molten silicon liquid 6 through the microporous sieve plate 5 unit includes:

[0084] The mixed gas is heated to a preset temperature and kept warm to obtain a prepared gas, wherein the mixed gas is a mixed gas of argon and oxygen;

[0085] The preliminary gas is sprayed into the silicon liquid 6 in a molten state through the gas inlet 3 and the micropores 51 on the microporous sieve plate 5 .

[0086] Specifically, the preset temperature is 1600° C. and the prepared gas is kept at this temperature in order to prevent the prepared gas from being too low, which would cause a sudden drop in temperature in the graphite crucible of the refining furnace during the gas intake process.

[0087] The method further comprises: while spraying the prepared gas into the molten silicon liquid 6 through the gas inlet 3 and the micropores 51 on the microporous sieve plate 5, evacuating the inner cavity of the sealed container.

[0088] See also Figure 12 , the present method will be specifically described below in conjunction with a regenerated silicon material purification system, involving an air blowing refining furnace, a micro-nano sieve plate, and silicon material purification, and mainly involves an air blowing refining method for removing impurities and purifying regenerated silicon materials.

[0089] The micro-nano sieve plate structure refers to a detachable sieve plate (realized by the bracket 4) structure including but not limited to quartz, graphite (covered with silicon nitride coating), silicon carbide and other high temperature resistant (above 1410°C) materials that do not react with silicon, with a pore size distribution range of 0.1 to 50 μm, different hole shapes, 30 to 50 μm height of the hole protrusions 52 on both sides of the sieve plate, and different positions (bottom, lower side wall, etc.) that match the size of the air-blowing refining furnace and the thermal field distribution in the furnace; the air-blowing refining furnace refers to but not limited to a tower refining furnace. In other words, in some embodiments, the silicon melt can also be processed by adding a mechanical stirring unit and a magnetic stirring unit.

[0090] The purification of recycled silicon materials refers to the separation of impurities from recycled silicon materials through micro-nano sieve plate air blowing refining method.

[0091] The above-mentioned air blowing refining method and device for removing impurities and purifying recycled silicon materials include the following steps:

[0092] (1) Pretreatment: using deionized water to wash and dry the waste silicon material; step (1) using deionized water to wash and dry the waste silicon material at least three times.

[0093] (2) Purification: Purify the sealed purification furnace; Step (2) purification is to evacuate the purification furnace and introduce argon gas, and then evacuate the furnace and introduce argon gas, and repeat this process at least 5 times to make the purity of argon gas in the purification furnace higher than 99.999%, and then heat the silicon material to keep it in a liquid molten state at a temperature above 1500°C for 1 to 3 hours.

[0094] (3) Melting: Heating and melting the silicon material in the graphite crucible of the sealed purification furnace.

[0095] (4) Blowing: blowing a preheated mixed gas with argon as carrier gas onto the molten silicon liquid through a micro-nano sieve plate; the micro-nano sieve plate in step (4) refers to a micro-nano sieve plate with a pore size range of 0.1 to 50 μm (which may not be uniformly distributed and may have different shapes), which divides the gas into micro-nano gas flows or bubbles and enters the molten liquid silicon in this form, and the preheating temperature of the mixed gas is above 1600° C. The mixed gas with argon as carrier gas refers to a mixed gas with argon (concentration 10% to 100%) as carrier gas, including but not limited to one or more of oxygen, chlorine, hydrogen, water vapor, silicon tetrachloride, silicon tetrafluoride, hydrogen chloride, hydrocyanic acid, nitrogen and helium, and the purity of a single gas is greater than 99.999%.

[0096] (5) Solidification: Stop blowing and heating to solidify the silicone liquid.

[0097] (6) Out of the furnace: The silicon ingot is taken out of the furnace, the head and tail are removed to complete the purification, and high-purity polysilicon is obtained.

[0098] The beneficial effects of each step are described in detail below:

[0099] (1) Pretreatment: Use deionized water to wash and dry the waste silicon material;

[0100] The beneficial effect of adopting the above steps is: cleaning the waste silicon material with deionized water removes dirt and impurities on the surface of the silicon material, reduces the impurity content on the surface of the silicon material, and lays a clean foundation for further melting and impurity removal.

[0101] (2) Purification: Purify the sealed purification furnace;

[0102] The beneficial effect of adopting the above steps is: by repeatedly passing argon gas and evacuating the purification furnace, the purification furnace is kept in a high-purity argon state, thereby avoiding the introduction of impurity particles in the air, and the silicon liquid 6 is removed in a high-purity environment, thereby ensuring the purity of the silicon liquid 6 during the removal process and improving the removal effect.

[0103] (3) Melting: heating and melting the silicon material in the graphite crucible of the sealed purification furnace;

[0104] The beneficial effect of adopting the above steps is: the silicon material in the crucible is melted by heating and maintained in a molten state above 1500°C, which is conducive to the volatilization of impurities with high volatility coefficients and the passage of air bubbles to remove impurities, thereby providing conditions for impurity removal; it is worth noting that the surface of the graphite crucible used needs to be coated with a 2mm layer of silicon nitride to prevent liquid silicon from reacting with graphite to form silicon carbide.

[0105] (4) Blowing: blowing a preheated mixed gas with argon as carrier gas onto the molten silicon liquid through the micro-nano sieve plate;

[0106] The beneficial effects of adopting the above steps are: on the one hand, the volatile impurities in the silicon liquid are brought to the outlet for discharge through the air blowing and vacuuming process; on the other hand, the gas blown in the refining furnace is divided by the micro-nano sieve plate to form micro-nano airflow and bubbles, which greatly increases the contact area and action time between the blown gas and the molten liquid silicon, so that more impurities are gathered at the gas-liquid interface and are brought to the surface of the liquid silicon as the bubbles rise, thereby increasing the gas impurity removal efficiency and improving the purity of polysilicon.

[0107] It is worth pointing out that the sieve plate aperture distribution range is 0.1 to 50 μm, which can ensure that the blowing airflow is divided into micro-nano-scale airflow and bubbles, greatly increasing the gas-liquid contact area and action time; the hole protrusions 52 on both sides of the sieve plate can play a micro-pressurization role on the airflow bubbles after segmentation, so that they can quickly escape from the holes into the liquid, increasing their solubility in the liquid; in view of the different blowing positions and sizes of different refining furnaces, the position and size of the sieve plate can be adjusted according to the blowing port, and is generally arranged in the lower part (bottom, lower side wall, etc.) to facilitate gas floating; in view of the differences in thermal field distribution in the furnace, the shape and aperture of the sieve plate holes can be designed and combined to produce a coupling effect with the thermal field distribution, thereby improving the gas segmentation efficiency; the sieve plate can be detachable through the bracket 4, which is convenient for cleaning and replacement of the sieve plate.

[0108] (5) Solidification: Stop blowing and heating to solidify the silicone liquid;

[0109] The beneficial effects of adopting the above steps are: stopping heating allows light impurities to be carried up by bubbles and heavy solid impurities to sink, thereby achieving the effect of separating light and heavy impurities; at the same time, during the solidification process, most of the impurities are gathered at both ends of the solidified silicon, forming an impurity-silicon-impurity separation state, which is convenient for the next step of impurity separation.

[0110] (6) Taking out of the furnace: The silicon ingot is taken out of the furnace, the head and tail are removed to complete the purification, and high-purity polysilicon is obtained.

[0111] The beneficial effect of adopting the above steps is: taking out the silicon ingot, removing the head, tail and surrounding parts with high impurity content, and obtaining high-purity polysilicon.

[0112] Example 2

[0113] This embodiment is a specific embodiment of the method for purifying recycled silicon material. Figure 1 and Figure 2a As shown, the microporous sieve plate 5 used in this embodiment is Figure 2a The microporous sieve plate 5 has no protrusions 52 on the surface. The specific purification steps are as follows:

[0114] (1) Pretreatment: The waste silicon material is repeatedly washed 5 times with deionized water and dried to make its surface clean without obvious dirt;

[0115] (2) Purification: Pour 500 kg of the cleaned waste silicon material into the graphite crucible of the purification furnace, and purify the sealed purification furnace by repeatedly evacuating and filling with argon seven times, so that the furnace is filled with high-purity argon;

[0116] (3) Melting: Then, the silicon material in the graphite crucible of the sealed purification furnace is heated and melted to control its temperature within the range of 1500-1600°C;

[0117] (4) Blowing through a circular hole sieve plate: a mixed gas of argon (50%) and oxygen (50%) with a preheating temperature of about 1600° C. is blown onto the molten silicon liquid 6 through a micro-nano sieve plate (circular hole sieve plate in FIG. 2 ) at the bottom, and vacuum is simultaneously drawn for 3 hours;

[0118] (5) Solidification: Stop blowing and heating to allow the silicon liquid to cool and solidify;

[0119] (6) Taking out of the furnace: After the silicon ingot is taken out of the furnace, the head, tail and surrounding parts are removed to obtain high-purity polysilicon. After testing, its phosphorus content is 0.31ppm, the total metal impurity content is 4.3ppm, and the total metal impurity content in the center is 0.37ppm.

[0120] Example 3

[0121] This embodiment is a specific embodiment of the method for purifying recycled silicon material. The difference between the method for purifying recycled silicon material in this embodiment and that in embodiment 2 is that: in this embodiment, a microporous sieve plate 5 having protrusions 52 on the surface is used. Figure 2b The specific purification steps are as follows:

[0122] (1) Pretreatment: The waste silicon material is repeatedly washed 5 times with deionized water and dried to make its surface clean without obvious dirt;

[0123] (2) Purification: Pour 500 kg of the cleaned waste silicon material into the graphite crucible of the purification furnace, and purify the sealed purification furnace by repeatedly evacuating and filling with argon seven times, so that the furnace is filled with high-purity argon;

[0124] (3) Melting: Then, the silicon material in the graphite crucible of the sealed purification furnace is heated and melted to control its temperature within the range of 1500-1600°C;

[0125] (4) Cylindrical hole sieve plate blowing: a mixed gas of argon (50%) and oxygen (50%) with a preheating temperature of about 1600° C. is blown to the molten silicon liquid 6 through a micro-nano sieve plate (the cylindrical hole sieve plate in FIG. 2 ) at the bottom, and a vacuum is simultaneously drawn for 3 hours;

[0126] (5) Solidification: Stop blowing and heating to allow the silicon liquid to cool and solidify;

[0127] (6) Taking out of the furnace: After the silicon ingot is taken out of the furnace, the head, tail and surrounding parts are removed to obtain high-purity polysilicon. After testing, its phosphorus content is 0.25ppm, the total content of metal impurities is 3.9ppm, and the total content of metal impurities in the center is 0.31ppm.

[0128] Example 4

[0129] This embodiment is a specific embodiment of the above-mentioned method for purifying recycled silicon material. The difference between the method for purifying recycled silicon material in this embodiment and that in embodiment 3 is that in this embodiment, the silicon melt is treated by an ultrasonic vibration generator and a mechanical stirrer during the melting process. Figure 2b The specific purification steps are as follows:

[0130] (1) Pretreatment: The waste silicon material is repeatedly washed 5 times with deionized water and dried to make its surface clean without obvious dirt;

[0131] (2) Purification: Pour 500 kg of the cleaned waste silicon material into the graphite crucible of the purification furnace, and purify the sealed purification furnace by repeatedly evacuating and filling with argon seven times, so that the furnace is filled with high-purity argon;

[0132] (3) Melting: Then heat and melt the silicon material in the graphite crucible of the sealed purification furnace to control its temperature within the range of 1500-1600° C., and start the ultrasonic vibration generator and the mechanical stirrer;

[0133] (4) Cylindrical hole sieve plate blowing: a mixed gas of argon (50%) and oxygen (50%) with a preheating temperature of about 1600° C. is blown to the molten silicon liquid 6 through a micro-nano sieve plate (the cylindrical hole sieve plate in FIG. 2 ) at the bottom, and a vacuum is simultaneously drawn for 3 hours;

[0134] (5) Solidification: Stop ultrasonic vibration, mechanical stirring, blowing and heating to cool and solidify the silicon liquid;

[0135] (6) Taking out of the furnace: After the silicon ingot is taken out of the furnace, the head, tail and surrounding parts are removed to obtain high-purity polysilicon. After testing, its phosphorus content is 0.10ppm, the total content of metal impurities is 2.8ppm, and the total content of metal impurities in the center is 0.22ppm.

[0136] Comparative Example

[0137] The difference between the comparative example and the above-mentioned embodiments 2, 3 and 4 is that the microporous sieve plate 5 is not used to divide the prepared gas, and the silicon melt is not treated by mechanical stirring or ultrasonic vibration. The specific purification steps are as follows:

[0138] (1) Pretreatment: The waste silicon material is repeatedly washed 5 times with deionized water and dried to make its surface clean without obvious dirt;

[0139] (2) Purification: Pour 500 kg of the cleaned waste silicon material into the graphite crucible of the purification furnace, and purify the sealed purification furnace by repeatedly evacuating and filling with argon seven times, so that the furnace is filled with high-purity argon;

[0140] (3) Melting: Then, the silicon material in the graphite crucible of the sealed purification furnace is heated and melted to control its temperature within the range of 1500-1600°C;

[0141] (4) Blowing: A mixture of argon (50%) and oxygen (50%) preheated to about 1600°C is blown from the bottom of the molten silicon liquid 6, and a vacuum is simultaneously drawn for 3 hours;

[0142] (5) Solidification: Stop blowing and heating to allow the silicon liquid to cool and solidify;

[0143] (6) Taking out of the furnace: After the silicon ingot is taken out of the furnace, the head, tail and surrounding parts are removed to obtain high-purity polysilicon. After testing, its phosphorus content is 3.2ppm, the total content of metal impurities is 10.89ppm, and the total content of metal impurities in the center is 4.5ppm.

[0144] By analyzing the metal and phosphorus impurity content in the silicon ingots of Examples 2, 3, and 4, it can be concluded that the cylindrical hole sieve plate combined with mechanical stirring and ultrasonic vibration has the strongest ability to remove impurities from silicon materials. The reason is that the protruding length of the cylindrical holes on both sides of the sieve plate has a micro-pressurization effect on the airflow and bubbles after segmentation, further promoting the dissolution and impurity removal process of the gas and liquid, and the combined mechanical stirring and ultrasonic vibration are more convenient for the mixing of gas and liquid, further enhancing the contact between the airflow bubbles and the liquid. Moreover, compared with the comparative example without the sieve plate, the impurity content of the high-purity polysilicon discharged from the furnace is significantly increased, which shows that the addition of the micro-nano sieve plate structure, combined with mechanical stirring and ultrasonic vibration, has a significant effect on improving the purity of the air-blown refined polysilicon.

[0145] Example 5

[0146] The present invention also discloses a regenerated silicon material purification device, comprising: a first execution device, a second execution device, a third execution device and a judgment unit.

[0147] Among them, the first execution device is used to obtain a silicon material-container unit. The silicon material-container unit includes a sealed container and a regenerated silicon material placed in the sealed container. A microporous sieve plate 5 unit is provided at the bottom of the sealed container. The microporous sieve plate 5 unit includes an air inlet 3 and a microporous sieve plate 5 installed on the air inlet 3. The second execution device is used to continuously heat the regenerated silicon material in the silicon material-container unit to obtain a molten silicon liquid 6. The third execution device is used to blow a preliminary gas into the molten silicon liquid 6 through the microporous sieve plate 5 unit. The judgment unit is electrically connected to the second execution device and the third execution device, and is used to judge whether the duration of blowing the preliminary gas meets the first preset condition. If so, the second execution device and the third execution device are respectively controlled to end the blowing and heating, so that the silicon liquid 6 solidifies, and the purified polysilicon is obtained.

[0148] Specifically, the first execution equipment includes: cleaning components, vacuum-inflation components, transfer components and other equipment. The waste silicon material is transferred to the cleaning component through the transfer component, and then cleaned by the cleaning component. Then, the silicon material after preliminary cleaning is transferred to a sealed container through the transfer component, and the sealed container is repeatedly vacuumed and inflated with argon seven times through the vacuum-inflation component to purify the sealed purification furnace (inside the sealed container) so that the furnace is filled with high-purity argon. The cleaning components, vacuum-inflation components, transfer components and other equipment can be manually operated by the staff, or they can be automatically operated according to the preset program in the controller.

[0149] The second execution device may be a heating device such as an induction coil, which is used to continuously heat the regenerated silicon material in the silicon material-container unit. The third execution device may be a gas pump, which is used to blow the preparatory gas into the molten silicon liquid 6 through the microporous sieve plate 5 unit.

[0150] The regenerated silicon material purification device is used to execute the steps of the regenerated silicon material purification method in Example 1, which can effectively improve the impurity removal effect of polycrystalline silicon and significantly improve the purity of polycrystalline silicon.

[0151] Example 6

[0152] The present invention also discloses a regenerated silicon material purification system, comprising: a sealed container, a microporous sieve plate 5 and the regenerated silicon material purification device in Example 5.

[0153] The inner cavity of the sealed container is used to accommodate the recycled silicon material, the bottom of the sealed container is opened at the air inlet 3, and the microporous sieve plate 5 is installed on the air inlet 3. The microporous sieve plate 5 is provided with a plurality of micropores 51, and the micropores 51 extend in the vertical direction and penetrate the body of the microporous sieve plate 5. The controller is used to execute the recycled silicon material purification method in Example 1.

[0154] Both ends of the plurality of micropores 51 on the microporous sieve plate 5 are provided with protrusions 52 .

[0155] The sealed container (i.e., the refining furnace) includes an outlet 1 and an inlet 3, wherein the outlet 1 is located at the upper part of the furnace body, and the inlet 3 is located at the lower part of the furnace body. The vacuuming-inflating assembly in the regenerated silicon material purification device is connected to the outlet 1 and the inlet 3, and is used to repeatedly vacuumize and inflate the sealed container with argon.

[0156] The refining furnace includes a graphite crucible and a heating and heat-insulating layer 2, and the heating and heat-insulating layer 2 is used to heat the regenerated silicon material in the furnace. The graphite crucible is accommodated in the heating and heat-insulating layer 2 and is used to accommodate the regenerated silicon material. The heated and molten silicon liquid 6 is in the graphite crucible. The refining furnace also includes an ultrasonic vibration generator and a stirring paddle 7. The stirring paddle 7 is installed in the furnace body and extends into the molten silicon liquid 6. The ultrasonic vibration generator (not shown in the figure) is connected to the graphite crucible and is used to emit ultrasonic vibrations to the graphite crucible and the regenerated silicon melt therein.

[0157] The system includes a blowing refining furnace (sealed container) with a micro-nano sieve plate structure, which is used to perform a method for purifying recycled silicon materials, including but not limited to refining and removing impurities from recycled silicon materials. During use, the focus will be on the regulation and combination of the material, pore size distribution, hole shape, active area, quantity, position, and detachability of the micro-nano sieve plate, and efforts will be made to improve the matching degree of the sieve plate with the refining furnace's full mixing device, thermal field distribution and other corresponding indicators, maximize the contact area and action time of the blown gas and molten liquid silicon, improve the impurity removal efficiency, and effectively improve the purity of polysilicon.

[0158] like Figure 1 As shown, specifically, the micro-nano sieve plate structure refers to a detachable sieve plate (realized by a bracket 4) structure including but not limited to quartz, graphite (covered with silicon nitride coating), silicon carbide and other high temperature resistant (above 1410°C) materials that do not react with silicon, with a pore size distribution range of 0.1 to 50 μm, different hole shapes, hole protrusions 52 on both sides of the sieve plate with a height of 30 to 50 μm, and different positions (bottom, lower side wall, etc.) that match the size of the air-blowing refining furnace and the thermal field distribution in the furnace. The air-blowing refining furnace refers to a refining furnace equipment including but not limited to a tower refining furnace. The number of micro-nano sieve plates (i.e., microporous sieve plates 5) is one, which is installed at the bottom of the refining furnace, directly opposite to the air inlet.

[0159] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill 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 purifying recycled silicon material, characterized in that: include: Get the silicon material-container unit, The silicon material-container unit comprises a sealed container and a regenerated silicon material placed in the sealed container, and a microporous sieve plate unit is provided at the bottom of the sealed container; Continuously heating the regenerated silicon material in the silicon material-container unit to obtain molten silicon liquid; Blowing the preparatory gas into the molten silicon liquid through the microporous sieve plate unit; It is determined whether the duration of blowing the preliminary gas meets the first preset condition. If so, the blowing and heating are terminated to solidify the silicon liquid to obtain purified polysilicon.

2. The method for purifying recycled silicon material according to claim 1, characterized in that: The step of obtaining a silicon material-container unit comprises: Cleaning the waste silicon material to obtain preliminarily cleaned silicon material; The silicon material after preliminary cleaning is placed in a sealed container and is aerated and purified to obtain a silicon material-container unit.

3. The method for purifying recycled silicon material according to claim 2, characterized in that: The silicon material after preliminary cleaning is placed in a sealed container and aerated and purified to obtain a silicon material-container unit, including: Place the preliminarily cleaned silicon material into a sealed container; The inside of the sealed container is vacuumed and inflated; Determine whether the number of vacuuming-inflating operations meets a second preset condition, and if so, end the vacuuming-inflating operations to obtain a silicon material-container unit; The vacuuming and inflating operation is performed on the inside of the sealed container, specifically: Vacuuming the interior of the sealed container to obtain a vacuumed sealed container; Argon gas is filled into the vacuum-evacuated sealed container, and the vacuum-evacuation-filling operation is completed.

4. The method for purifying recycled silicon material according to claim 3, characterized in that: The first preset condition is that the duration of blowing the preparation gas reaches 1-3 hours; The second preset condition is that the number of vacuuming-inflation operations is greater than or equal to 5 times.

5. The method for purifying recycled silicon material according to any one of claims 1 to 4, characterized in that: The regenerated silicon material in the silicon material-container unit is continuously heated to obtain molten silicon liquid, specifically: The regenerated silicon material is heated to a preset temperature range, and the regenerated silicon material is maintained within the preset temperature range to obtain molten silicon liquid.

6. The method for purifying recycled silicon material according to claim 5, characterized in that: The microporous sieve plate unit comprises an air inlet (3) and a microporous sieve plate (5) mounted on the air inlet, wherein the microporous sieve plate (5) is provided with a plurality of micropores (51), and the micropores (51) extend in a vertical direction and penetrate the microporous sieve plate body; The step of blowing the preparatory gas into the molten silicon liquid through the microporous sieve plate unit comprises: The mixed gas is heated to a preset temperature and kept warm to obtain a prepared gas, wherein the mixed gas is a mixed gas of argon and oxygen; The prepared gas is sprayed into the molten silicon liquid through the gas inlet and the micropores on the microporous sieve plate; The method further comprises: while the prepared gas is sprayed into the molten silicon liquid through the gas inlet and the micropores on the microporous sieve plate, the inner cavity of the sealed container is evacuated.

7. A regenerated silicon material purification device, characterized in that: include: A first execution device, a second execution device, a third execution device and a judgment unit; The first execution device is used to obtain a silicon material-container unit, The silicon material-container unit includes a sealed container and a regenerated silicon material placed in the sealed container, a microporous sieve plate unit is provided at the bottom of the sealed container, and the microporous sieve plate unit includes an air inlet and a microporous sieve plate installed on the air inlet; The second execution device is used to continuously heat the regenerated silicon material in the silicon material-container unit to obtain molten silicon liquid; The third execution device is used to blow the preliminary gas into the molten silicon liquid through the microporous sieve plate unit; The judgment unit is electrically connected to the second execution device and the third execution device, and is used to judge whether the duration of blowing in the preliminary gas meets the first preset condition. If so, the second execution device and the third execution device are controlled to end blowing and heating respectively to solidify the silicon liquid and obtain purified polysilicon.

8. A system for purifying recycled silicon material, characterized in that: include: A sealed container, a microporous sieve plate and the regenerated silicon material purification device according to claim 7; The inner cavity of the sealed container is used to accommodate the recycled silicon material, the bottom of the sealed container is opened at the air inlet, and the microporous sieve plate is installed on the air inlet; The microporous sieve plate is provided with a plurality of micropores, and the micropores extend in a vertical direction and penetrate the microporous sieve plate body; The regenerated silicon material purification device is used to perform the regenerated silicon material purification method described in any one of claims 1-6.

9. The regenerated silicon material purification system according to claim 8, characterized in that: The micropore pore size of the microporous sieve plate is 0.1-50 μm, and the pore sizes of the multiple micropores on the microporous sieve plate are coupled to the thermal field distribution in the sealed container.

10. The regenerated silicon material purification system according to claim 9, characterized in that: Both ends of the plurality of micropores on the micropore sieve plate are provided with protrusions.

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