Metal chloride removal device and method thereof, polycrystalline silicon residual liquid treatment system and method thereof, and polycrystalline silicon preparation system

Abstract

The embodiment of the invention provides a metal chloride removal device and method, a polycrystalline silicon residual liquid treatment system and method and a polycrystalline silicon preparation system. The device comprises a reaction precipitation unit and a solid-liquid separation unit, wherein the reaction precipitation unit is connected with the solid-liquid separation unit through a pipeline; a first cooling subunit and a second cooling subunit are arranged on the reaction precipitation unit; the reaction precipitation unit is used for reacting the added oxygen-containing compounding agent with the metal chloride in the residual liquid to generate a solid metal chloride complex; the first cooling subunit is used for cooling materials in the reaction precipitation unit to a preset temperature; the second cooling subunit is used for condensing and refluxing gas generated by material flash evaporation; and the solid-liquid separation unit is used for receiving the materials conveyed by the reaction precipitation unit and separating solids in the materials. The device can effectively reduce the condition that the device is easy to block when metal chloride in the residual liquid is removed, and the continuous service life of the device is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of chemical separation, and in particular to a device for removing metal chlorides and its method, a polysilicon residue treatment system and its method, and a polysilicon preparation system. Background Art

[0002] In the production process of Siemens polysilicon materials, about 0.1 - 0.12 tons of residue will be generated for every 1 ton of high-purity polysilicon produced. The residue mainly comes from the hydrogenation unit, the reduction unit, and the rectification unit. The main components of the residue are chlorosilanes (trichlorosilane, tetrachlorosilane, pentachlorodisilane, hexachlorodisilane, etc.), siloxanes (hexachlorodisiloxane, etc.), silicon powder, metal chlorides (aluminum trichloride, titanium tetrachloride, etc.), and other impurities.

[0003] Currently, the residue is mainly subjected to heating and flash evaporation for solid-liquid separation. After removing the solid residue, the clear liquid is then rectified and other steps are carried out to separate chlorosilanes and metal chlorides in sequence.

[0004] However, during the process of treating the residue, the treatment device or system is prone to blockage, resulting in frequent maintenance and inability to operate in a long cycle. Summary of the Invention

[0005] The present application provides a device for removing metal chlorides and its method, a polysilicon residue treatment system and its method, and a polysilicon preparation system to solve the technical problem that the residue treatment device or system is prone to blockage.

[0006] In the first aspect of the present application, a device for removing metal chlorides is provided. The device includes: a reaction precipitation unit and a solid-liquid separation unit, and the reaction precipitation unit is connected to the solid-liquid separation unit by a pipeline; a first cooling sub-unit and a second cooling sub-unit are provided on the reaction precipitation unit;

[0007] The reaction precipitation unit is used to react the added oxygen-containing complexing agent with the metal chlorides in the residue to form solid metal chloride complexes;

[0008] The first cooling sub-unit is used to cool the materials in the reaction precipitation unit to a preset temperature;

[0009] The second cooling sub-unit is used to condense and reflux the gas generated by the flash evaporation of the materials;

[0010] The solid-liquid separation unit is used to receive the materials transported by the reaction precipitation unit and separate the solids in the materials.

[0011] For the device as described above, the reaction precipitation unit includes a reaction precipitation tank, the first cooling sub-unit is a jacket, and the second cooling sub-unit is a cooler;

[0012] The jacket is arranged on the periphery of the reaction precipitation tank, and the jacket is provided with a cooling medium inlet and a cooling medium outlet; the cooler is arranged on the upper part of the reaction precipitation tank and is communicated with the reaction precipitation tank through a gas phase pipeline and a liquid phase pipeline;

[0013] The jacket is used to introduce a cooling medium through the cooling medium inlet and discharge the cooling medium through the cooling medium outlet, so as to cool the material in the reaction precipitation tank to a preset temperature;

[0014] The cooler is used to input the gas generated in the material into the cooler through the gas phase pipeline, and condense the gas into a liquid by the cooler and then return it to the reaction precipitation tank through the liquid phase pipeline.

[0015] The device as described above, wherein the solid-liquid separation unit is a drum filter, and the top of the drum filter is connected to the bottom pipeline of the reaction precipitation unit;

[0016] The drum filter is used to convey the solid-containing material in the material to the solid treatment unit and convey the clear liquid in the material to the clear liquid treatment unit.

[0017] The device as described above, wherein the oxygen-containing complexing agent is in a liquid state and the normal boiling point range is 80-120 °C or 160-300 °C.

[0018] The second aspect of the present application provides a polysilicon residue treatment system, which includes a solid treatment unit, a clear liquid treatment unit, and a metal chloride removal device as described in the first aspect;

[0019] The device is respectively connected to the solid treatment unit and the clear liquid treatment unit through pipelines;

[0020] The device is used to remove silicon powder in solid form and metal chloride complexes generated by reaction in the polysilicon residue;

[0021] The solid treatment unit is used to treat the solid-containing material received from the device;

[0022] The clear liquid treatment unit is used to treat the clear liquid received from the device.

[0023] The polysilicon residue treatment system as described above, wherein the clear liquid treatment unit includes: a clear liquid primary rectification unit, a clear liquid secondary rectification unit, and a cracking and rectification unit connected in sequence;

[0024] The first-stage rectification unit for the clear liquid is connected to the solid-liquid separation unit through a clear liquid buffer tank to receive the clear liquid conveyed by the solid-liquid separation unit and convey the clear liquid to the first-stage rectification unit for the clear liquid through a feed pump. The first-stage rectification unit for the clear liquid is used to convey the treated clear liquid to the second-stage rectification unit for the clear liquid; the second-stage rectification unit for the clear liquid is connected to the reaction precipitation tank through a circulation pipeline to convey the substance containing the oxygen-containing complexing agent into the reaction precipitation tank.

[0025] The polysilicon residual liquid treatment system as described above, wherein the second-stage rectification unit for the clear liquid includes a second-stage rectification tower for the clear liquid, and a first interface connecting the circulation pipeline is provided at the bottom of the second-stage rectification tower for the clear liquid; the normal boiling point range of the oxygen-containing complexing agent is 160-300 °C.

[0026] The polysilicon residual liquid treatment system as described above, wherein the second-stage rectification unit for the clear liquid includes a second-stage rectification tower for the clear liquid, and a second interface connecting the circulation pipeline is provided at the top of the second-stage rectification tower for the clear liquid; the normal boiling point range of the oxygen-containing complexing agent is 80-120 °C.

[0027] The third aspect of the present application provides a polysilicon preparation system, including a polysilicon preparation system and the polysilicon residual liquid treatment system as described in the second aspect.

[0028] The fourth aspect of the present application provides a method for removing metal chlorides. The method is applied to the metal chloride removal device as described above, and the method includes:

[0029] Using a reaction precipitation unit to react the added oxygen-containing complexing agent with the residual liquid to generate a solid metal chloride complex;

[0030] Using a first cooling sub-unit to cool the material in the reaction precipitation unit to a preset temperature;

[0031] Using a second cooling sub-unit to condense and reflux the gas generated by the flashing of the material;

[0032] Using a solid-liquid separation unit to receive the material conveyed by the reaction precipitation unit and separate the solid in the material.

[0033] The fifth aspect of the present application provides a method for treating polysilicon residual liquid. The method is applied to the polysilicon residual liquid treatment system as described above, and the method includes:

[0034] Using a metal chloride removal device to remove the silicon powder in solid form and the metal chloride complex generated by reaction in the polysilicon residual liquid;

[0035] Using a solid treatment unit to treat the solid-containing material received from the metal chloride removal device;

[0036] The clarified liquid received from the metal chloride removal device is processed by a clarified liquid treatment unit.

[0037] This application provides a metal chloride removal device and its method, a polysilicon residue treatment system and its method, and a polysilicon preparation system. By adding an oxygen-containing complexing agent to the reaction precipitation unit of the device, the metal chlorides in the residue are precipitated in solid form. At the same time, a first cooling sub-unit and a second cooling sub-unit are set to cool the materials in the reaction precipitation unit and condense the gas for reflux, avoiding the increase in viscosity caused by flash evaporation and concentration of the materials, effectively reducing the blockage of the device when removing metal chlorides from the residue, and extending the continuous use period of the device; the polysilicon residue treatment system can remove substances that are likely to cause system blockage from the source, thus ensuring the long-term operation of the treatment system. A solid treatment unit and a clarified liquid treatment unit are set to process the solids and liquids in the residue respectively, so as to realize the recovery of available components in the residue and the removal of impurities; the polysilicon preparation system connects the polysilicon residue treatment system with the polysilicon preparation system, and can directly process the residue after polysilicon preparation is completed, improving the efficiency of polysilicon preparation and effectively reducing the situation of system blockage; the metal chloride removal method uses the reaction precipitation unit to add an oxygen-containing complexing agent to precipitate the metal chlorides in the residue in solid form. At the same time, the first cooling sub-unit and the second cooling sub-unit are used to cool the materials in the reaction precipitation unit and condense the gas for reflux, avoiding the increase in viscosity caused by flash evaporation and concentration of the materials, efficiently removing the metal chlorides in the residue, and effectively reducing the blockage during the treatment process, extending the continuous use period of the device; the polysilicon residue treatment method uses the metal chloride removal device as described above to remove substances that are likely to cause system blockage from the source, thus ensuring the long-term operation of the treatment system, and then uses the solid treatment unit and the clarified liquid treatment unit to process the solids and liquids in the residue respectively, so as to realize the recovery of available components in the residue and the removal of impurities, improving the treatment efficiency of polysilicon residue. Brief Description of the Drawings

[0038] The drawings here are incorporated into the specification and constitute a part of this specification, showing embodiments in line with this application, and are used together with the specification to explain the principles of this application.

[0039] Figure 1 Schematic diagram of the metal chloride removal device provided by an embodiment of this application;

[0040] Figure 2 Schematic diagram of the metal chloride removal device provided by another embodiment of this application;

[0041] Figure 3 Schematic diagram of the polysilicon residue treatment system provided by an embodiment of this application;

[0042] Figure 4 Schematic diagram of a polysilicon residual liquid treatment system provided by another embodiment of the present application;

[0043] Figure 5 Schematic diagram of a polysilicon preparation system provided by an embodiment of the present application;

[0044] Figure 6 Flow chart of a method for removing metal chlorides provided by an embodiment of the present application;

[0045] Figure 7 Flow chart of a polysilicon residual liquid treatment method provided by an embodiment of the present application;

[0046] Figure 8 Schematic diagram of a polysilicon residual liquid treatment system provided by an embodiment of the present application;

[0047] Figure 9 Schematic diagram of a polysilicon residual liquid treatment system provided by another embodiment of the present application;

[0048] Figure 10 Schematic diagram of a polysilicon residual liquid treatment system provided by yet another embodiment of the present application.

[0049] Reference numerals

[0050] 101 - Reaction precipitation unit; 102 - Solid - liquid separation unit; 101a - First cooling sub - unit; 101b - Second cooling sub - unit;

[0051] 201 - Reaction precipitation tank; 202 - Jacket; 202a - Cooling medium inlet; 202b - Cooling medium outlet; 203 - Cooler; 203a - Gas - phase pipeline; 203b - Liquid - phase pipeline; 204 - Rotary drum filter; 205 - Solid treatment unit; 206 - Clear liquid treatment unit;

[0052] 301 - Metal chloride removal device;

[0053] 401 - First - stage rectification unit for clear liquid; 402 - Second - stage rectification unit for clear liquid; 403 - Pyrolysis and rectification unit; 405 - Clear liquid buffer tank;

[0054] 501 - Polysilicon preparation system; 502 - Polysilicon residual liquid treatment system;

[0055] 803 - Hydrolysis tank; 805 - First - stage rectification tower for clear liquid; 806 - Second - stage rectification tower for clear liquid; 807 - Pyrolysis kettle; 808 - Pyrolysis kettle rectification tower; 809 - Hydrolysis kettle;

[0056] 903 - Dryer;

[0057] 1001 - Flash evaporation unit; 1002 - Settling unit; 1003 - Slurry drying unit; 1004 - Condensation unit; 1005 - Clear liquid rectification unit; 1006 - Aluminum removal unit; 1007 - Titanium removal unit.

[0058] Through the above - mentioned drawings, specific embodiments of the present application have been shown, and more detailed descriptions will be provided hereinafter. These drawings and written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0059] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0060] Figure 1 A schematic diagram of a metal chloride removal device provided for an embodiment of the present application, as Figure 1 shown, a first aspect of the present application provides a metal chloride removal device, which includes a reaction precipitation unit 101 and a solid - liquid separation unit 102. The reaction precipitation unit 101 is connected to the solid - liquid separation unit 102 through a pipeline. A first cooling sub - unit 101a and a second cooling sub - unit 101b are further provided on the reaction precipitation unit 101;

[0061] The reaction precipitation unit 101 is used to react the added oxygen - containing complexing agent with the metal chloride in the residual liquid to generate a solid metal chloride complex;

[0062] The first cooling sub - unit 101a is used to cool the material in the reaction precipitation unit 101 to a preset temperature;

[0063] The second cooling sub - unit 101b is used to condense and reflux the gas generated by the flash evaporation of the material;

[0064] The solid - liquid separation unit 102 is used to receive the material transported by the reaction precipitation unit and separate the solid in the material.

[0065] Among them, the oxygen - containing complexing agent is a pure substance or mixture containing oxygen that can undergo a complexing reaction with the metal chloride, such as phosphorus oxychloride, etc. This embodiment does not make any limitations in this regard.

[0066] Optionally, the first cooling subunit 101a may be a jacket disposed around the reaction precipitation unit for introducing circulating water to cool the material, or a cooling component disposed inside the reaction precipitation unit 101, such as an internal coil, an internal plate heat exchanger, etc., which can adjust the temperature inside the reaction precipitation unit 101, or other devices that can reduce the material to a preset temperature. This embodiment does not limit this.

[0067] Among them, the preset temperature is the temperature to which the material is pre-set to be reduced, such as -15°C, -10°C, 0°C, 25°C, 35°C, 45°C, etc., which can be adjusted according to the actual production situation. This embodiment does not limit this.

[0068] Optionally, the second cooling subunit 101b may be a cooler disposed at the upper end of the reaction precipitation unit 101, connected to the reaction precipitation unit 101 through two pipelines. One pipeline is used to receive the gas generated by the material. After passing through the cooler, it returns to the reaction precipitation unit 101 in liquid form through the other pipeline, or other devices such as a condenser tube that can condense and reflux the gas generated in the material. This embodiment does not limit this.

[0069] It should be noted that the second cooling subunit 101b can be disposed at any position of the reaction precipitation unit 101, as long as it can condense and reflux the gas generated in the material. This embodiment does not limit this.

[0070] In a specific implementation manner, an excessive amount of oxygen-containing complexing agent and residual liquid can be added to the reaction precipitation unit 101, so that the metal chloride in the residual liquid can fully react and precipitate in the form of a solid. At the same time, the first cooling subunit 101a disposed on the reaction precipitation unit 101 will cool the material to reach the preset temperature, and the second cooling subunit 101b will condense and reflux the gas generated by the material in the reaction precipitation unit 101. After the reaction, the material is transported to the solid-liquid separation unit 102 to separate the solid in the material, thereby removing the metal chloride in the residual liquid.

[0071] Among them, the reaction precipitation unit 101 includes a container for containing the residual liquid and the oxygen-containing complexing agent, such as a reaction precipitation tank, etc. This embodiment does not limit this.

[0072] Optionally, the solid-liquid separation unit 102 may include a drum filter or a metal sintered filter, etc., which are devices for separating solids and liquids in the material. This embodiment does not limit this.

[0073] It should be noted that the reaction precipitation unit 101 and the solid-liquid separation unit 102 are connected by pipelines. The solid-liquid separation unit 102 can be arranged below the reaction precipitation unit 101 to receive the transported materials, or the solid-liquid separation unit 102 can be arranged at other positions such as the left / right side of the reaction precipitation unit 101. It only needs to ensure that the solid-liquid separation unit 102 can receive the materials transported by the reaction precipitation unit 101, and this embodiment does not limit this.

[0074] The metal chloride removal device provided in this embodiment can remove metal chlorides in the residual liquid through an oxygen-containing complexing agent in the form of solid precipitation at the source, reducing the situation of device blockage caused by removal in subsequent steps. The first cooling sub-unit 101a is set to cool the materials in the reaction precipitation unit 101 to a preset temperature, and the second cooling sub-unit 101b is set to condense and reflux the gas generated in the materials, avoiding blockage caused by the increase in viscosity of the residual liquid due to flash evaporation and concentration, so as to ensure the long-term operation of the device.

[0075] In some embodiments of the present application, as Figure 2 shown, the reaction precipitation unit includes a reaction precipitation tank 201, the first cooling sub-unit is a jacket 202, and the second cooling sub-unit is a cooler 203;

[0076] The jacket 202 is arranged on the periphery of the reaction precipitation tank 201, and the jacket is provided with a cooling medium inlet 202a and a cooling medium outlet 202b; the cooler 203 is arranged on the upper part of the reaction precipitation tank 201 and is communicated with the reaction precipitation tank 201 through a gas pipeline and a liquid pipeline;

[0077] The jacket 202 is used to introduce a cooling medium through the cooling medium inlet 202a and flow out the cooling medium through the cooling medium outlet 202b, so as to cool the materials in the reaction precipitation tank 201 to a preset temperature;

[0078] The cooler 203 is used to input the gas generated in the materials into the cooler 203 through the gas pipeline 203a, and condense the gas into a liquid by using the cooler 203 and then reflux it to the reaction precipitation tank 201 through the liquid pipeline 203b.

[0079] It can be understood that a stirring paddle can also be arranged in the reaction precipitation tank 201, which can stir the materials evenly to make them react fully and avoid blockage of the pipeline by solid precipitation.

[0080] Specifically, the oxygen-containing complexing agent and the residual liquid are respectively added into the reaction precipitation tank 201 through pipelines for reaction therein; the cooling medium enters from the cooling medium inlet 202a and flows out from the cooling medium outlet 202b, and the cooling medium circulates in the jacket 202, so that the material is cooled to a preset temperature; the gas generated in the reaction precipitation tank 201 is input into the cooler 203 through the gas-phase pipeline 203a, and after being cooled by the cooler 203, it flows back to the reaction precipitation tank 201 through the liquid-phase pipeline 203b.

[0081] It can be understood that the gas flows into the gas-phase pipeline, and the liquid flows into the liquid-phase pipeline.

[0082] Among them, the type of the cooling medium can be selected according to the actual situation, such as chilled water, circulating water, Freon refrigerant, etc., and this embodiment does not limit this.

[0083] In the metal chloride removal device provided in this embodiment, a jacket 202 is arranged outside the reaction precipitation tank 201 to cool the material to a preset temperature, and the purpose of cooling is achieved through a simple circulation of the cooling medium, avoiding blockage caused by the increase in viscosity due to flash evaporation and concentration of the material; the cooler 203 is arranged at the upper part of the reaction precipitation tank 201, and the gas generated in the material naturally enters the cooler 203 for condensation and reflux due to the density difference, so as to increase the fluidity of the material and reduce the probability of blockage.

[0084] Further, as Figure 2 shown, the solid-liquid separation unit is a drum filter 204, and the top of the drum filter 204 is connected to the bottom pipeline of the reaction precipitation unit;

[0085] The drum filter 204 is used to convey the solids in the material to the solid treatment unit 205 and convey the clear liquid in the material to the clear liquid treatment unit 206.

[0086] Specifically, the drum filter 204 is arranged below the reaction precipitation unit and is connected by pipelines to receive the material conveyed by the reaction precipitation unit. For the solid-containing material entering the drum filter 204, under the action of the pressure difference, the liquid flows out through the filter layer and is conveyed to the clear liquid treatment unit 206. The solids are intercepted on the surface of the filter layer and are conveyed to the solid treatment unit 205 under the action of the scraper.

[0087] In the metal chloride removal device provided in this embodiment, the drum filter 204 is used for solid-liquid separation, which can make the solid-liquid separation more thorough and reduce the blockage phenomenon of the device; connecting the top of the drum filter to the bottom pipeline of the reaction precipitation unit enables the material to be conveyed by gravity, which is simple and convenient.

[0088] In some embodiments, the phase state of the oxygen-containing complexing agent is liquid, and the normal boiling point range is 80 - 120 °C or 160 - 300 °C.

[0089] It should be noted that in addition to metal chlorides, the residual liquid also contains other components. To completely remove the metal chlorides, an excessive amount of oxygen-containing complexing agent is added. In subsequent steps, to separate the excessive oxygen-containing complexing agent from other components in the residual liquid, the difference in the boiling points of the oxygen-containing complexing agent and other components is utilized for separation.

[0090] Specifically, the normal boiling point of the oxygen-containing complexing agent can be 80°C, 90°C, 100°C, 110°C, 120°C, and any range composed of any two of the above values; or 160°C, 180°C, 200°C, 240°C, 260°C, 300°C, and any range composed of any two of the above values.

[0091] In the metal chloride removal device provided in this embodiment, a liquid oxygen-containing complexing agent is used, which can not only reduce the difficulty of feeding, but also prevent blockage of the liquid material. By controlling the boiling point of the oxygen-containing complexing agent within the above range, not only can the metal chlorides be removed, but also the excess oxygen-containing complexing agent can be separated from other components in the residual liquid.

[0092] Figure 3 It is a schematic diagram of a polysilicon residual liquid treatment system provided in an embodiment of the present application. As Figure 3 shown, in the second aspect of the present application, a polysilicon residual liquid treatment system is provided, which includes a metal chloride removal device 301 of the first aspect, a solid treatment unit 205, and a clear liquid treatment unit 206;

[0093] The metal chloride removal device 301 is connected to the solid treatment unit 205 and the clear liquid treatment unit 206 through pipelines respectively;

[0094] The metal chloride removal device 301 is used to remove silicon powder in solid form and metal chloride complexes generated by reaction in the polysilicon residual liquid;

[0095] The solid treatment unit 205 is used to process the solid-containing material received from the device;

[0096] The clear liquid treatment unit 206 is used to process the clear liquid received from the device.

[0097] Specifically, when treating the polysilicon residual liquid, first, the metal chloride removal device 301 as in the first aspect is used to remove silicon powder, metal chloride complexes, etc. in the residual liquid, and then the solid treatment unit 205 is used to process the solids transported from the metal chloride removal device 301, and the clear liquid treatment unit 206 is used to process the liquid transported from the metal chloride removal device 301 to complete the treatment of the polysilicon residual liquid.

[0098] Optionally, the solid processing unit 205 may be a hydrolysis tank, a dryer, or other equipment that can be used to process the solids separated from the polysilicon residual liquid. This embodiment does not limit this.

[0099] Optionally, the clear liquid processing unit 206 may include a rectification column, a cracking kettle, and other equipment used to process the liquid separated from the polysilicon residual liquid. This embodiment does not limit this.

[0100] It should be noted that in addition to the metal chloride device 301 being connected to the solid processing unit 205 and the clear liquid processing unit 206 through pipelines respectively, the placement positions of each unit can be adjusted according to the actual situation. For example, the solid processing unit 205 is connected through a pipeline on the left side of the metal chloride device 301, and the clear liquid processing unit 206 is connected through a pipeline on the right side of the metal chloride device 301. It can also be other placement positions. This embodiment does not limit this.

[0101] In the polysilicon residual liquid processing system provided in this embodiment, the metal chloride that is likely to cause system blockage in the residual liquid is removed at the very beginning, greatly reducing the occurrence of blockage during the processing of polysilicon residual liquid and extending the operation cycle of the system; and since the metal chloride is removed at the beginning of the residual liquid processing, the dosage of the subsequent catalyst is also reduced.

[0102] In some embodiments, as Figure 4 shown, the clear liquid processing unit includes: a clear liquid primary rectification unit 401, a clear liquid secondary rectification unit 402, and a cracking and rectification unit 403 that are connected in sequence;

[0103] The clear liquid primary rectification unit 401 is connected to the solid-liquid separation unit 102 through a clear liquid buffer tank 405 to receive the clear liquid conveyed by the solid-liquid separation unit 102 and convey the clear liquid to the clear liquid primary rectification unit 401 through a feed pump. The clear liquid primary rectification unit 401 is used to convey the processed clear liquid to the clear liquid secondary rectification unit 402; the clear liquid secondary rectification unit 402 is connected to the reaction precipitation tank 201 through a circulation pipeline to convey the substance containing the oxygen-containing complexing agent to the reaction precipitation tank 201.

[0104] Specifically, the clear liquid coming out of the solid-liquid separation unit 102 first enters the clear liquid buffer tank 405, and then is conveyed to the clear liquid primary rectification unit 401 through a feed pump. After certain processing, trichlorosilane and silicon tetrachloride are separated out, and the remaining clear liquid is conveyed to the clear liquid secondary rectification unit 402 for further processing to separate out the excessive oxygen-containing complexing agent and convey it to the reaction precipitation tank 201 through a circulation pipeline. Finally, the clear liquid containing components such as pentachlorodisilane and hexachlorodisilane is conveyed to the cracking kettle for cracking and processing in the cracking and rectification unit 403.

[0105] Among them, the first-stage rectification unit 401 for clear liquid can include a rectification column, which is used to separate trichlorosilane and silicon tetrachloride from the residual liquid. Since the boiling points of trichlorosilane and silicon tetrachloride are relatively low, averaging at 50-60 °C, equipment for collecting trichlorosilane and silicon tetrachloride is provided at the top of the rectification column, and a pipeline is provided at the bottom of the rectification column for connecting to the second-stage rectification unit 402 for clear liquid.

[0106] Optionally, in the second-stage rectification unit 402 for clear liquid, pentachlorodisilane, hexachlorodisilane, and oxygen-containing complexes are mainly separated. The cracking and rectification unit 403 can be connected to the top of the rectification column in the second-stage rectification unit 402 for clear liquid through a pipeline, or can be connected to the bottom of the rectification column through a pipeline. The specific connection position can be determined according to the actual processing temperature, and this embodiment does not limit it.

[0107] Optionally, the second-stage rectification unit 402 for clear liquid is connected to the reaction precipitation tank 201 through a circulation pipeline. The reaction precipitation tank 201 can be connected to the top of the rectification column in the second-stage rectification unit 402 for clear liquid through a pipeline, or can be connected to the bottom of the rectification column through a pipeline. The specific connection position can be determined according to the boiling point of the selected oxygen-containing complex, and this embodiment does not limit it.

[0108] Among them, the cracking and rectification unit 403 can include equipment such as a cracking kettle, a rectification column, and a conversion kettle to perform subsequent processing on pentachlorodisilane and hexachlorodisilane.

[0109] The polysilicon residual liquid treatment system provided in this embodiment can effectively separate the components in the clear liquid through the first-stage rectification unit 401 for clear liquid, the second-stage rectification unit 402 for clear liquid, and the cracking and rectification unit 403 connected in sequence. The second-stage rectification unit 402 for clear liquid is connected to the reaction precipitation tank 201 through a circulation pipeline to transport the substance containing the oxygen-containing complexing agent to the reaction precipitation tank 201, which can not only separate the excess oxygen-containing complex and improve the purity of chlorosilane, but also recycle the oxygen-containing complex and reduce the cost of residual liquid treatment.

[0110] In some embodiments, the second-stage rectification unit for clear liquid includes a second-stage rectification column for clear liquid, and a first interface for connecting the circulation pipeline is provided at the bottom of the second-stage rectification column for clear liquid; the normal boiling point range of the oxygen-containing complexing agent is 160-300 °C.

[0111] Specifically, after the clear liquid enters the second-stage rectification column for clear liquid, since the boiling points of pentachlorodisilane and hexachlorodisilane average at 130-140 °C, when the rectification temperature is between 140-160 °C, pentachlorodisilane and hexachlorodisilane will enter the cracking and rectification unit in the form of gas from the top of the second-stage rectification column for clear liquid, and the oxygen-containing complex with a boiling point between 160-300 °C is transported to the reaction precipitation tank through the first interface provided at the bottom of the second-stage rectification column for clear liquid via the circulation pipeline.

[0112] In some other embodiments, the secondary rectification unit for the supernatant includes a secondary rectification tower for the supernatant. A second interface connecting to a circulation pipeline is provided at the top of the secondary rectification tower for the supernatant; the normal boiling point range of the oxygen-containing complexing agent is 80-120 °C.

[0113] Specifically, after the supernatant enters the secondary rectification tower for the supernatant, since the boiling points of pentachlorodisilane and hexachlorodisilane are on average 130-140 °C, when the rectification temperature is higher than the boiling point of the selected oxygen-containing complexing agent, the oxygen-containing complexing agent with a boiling point between 80-120 °C passes through the second interface provided at the top of the secondary rectification tower for the supernatant and is transported to the reaction precipitation tank through the circulation pipeline. Pentachlorodisilane and hexachlorodisilane enter the cracking and rectification unit from the bottom of the secondary rectification tower for the supernatant.

[0114] For the polysilicon residue treatment system provided in this embodiment, the connection interface between the secondary rectification tower for the supernatant and the reaction precipitation tank can be set at the top or the bottom according to the actual situation. By selecting oxygen-containing complexing agents with different boiling points to adapt to the interface positions of different secondary rectification towers for the supernatant, the excessive oxygen-containing complexing agent can be separated and transported to the reaction precipitation tank for recycling.

[0115] Figure 5 Schematic diagram of a polysilicon preparation system provided in an embodiment of the present application, as Figure 5 shown, a third aspect of the present application provides a polysilicon preparation system, which includes a polysilicon preparation system 501 and a polysilicon residue treatment system 502 as in the second aspect.

[0116] Specifically, when preparing polysilicon materials, the polysilicon residue treatment system 502 can be directly connected behind the polysilicon preparation system 501 to receive and process the polysilicon residue.

[0117] The polysilicon preparation system provided in this embodiment can directly process the residue after polysilicon preparation is completed, and can effectively reduce the situation of system blockage.

[0118] Figure 6 Flow chart of a method for removing metal chlorides provided in an embodiment of the present application, as Figure 6 shown, the execution subject of this method is the metal chloride removal device as in the first aspect, and specifically includes the following steps:

[0119] S601. Use the reaction precipitation unit to react the added oxygen-containing complexing agent with the metal chlorides in the residue to form solid metal chloride complexes.

[0120] Specifically, the oxygen-containing complexing agent and the residue are added to the reaction precipitation unit, and the metal chlorides are precipitated in solid form by using the reaction between the oxygen-containing complexing agent and the metal chlorides in the residue.

[0121] S602. Use the first cooling subunit to cool the material in the reaction precipitation unit to a preset temperature.

[0122] Specifically, after the material enters the reaction precipitation unit, flash evaporation may occur. To avoid an increase in viscosity caused by flash evaporation and concentration of the material, a cooling subunit is used to cool the material to a preset temperature.

[0123] S603. Use the second cooling subunit to condense and reflux the gas generated by the flash evaporation of the material.

[0124] Specifically, since the material enters a closed reactor vessel and the pressure increases, causing the material to vaporize, the second cooling subunit is used to condense and reflux the gas generated in the material to ensure a certain fluidity of the material.

[0125] S604. Use the solid-liquid separation unit to receive the material transported from the reaction precipitation unit and separate the solid from the material.

[0126] Specifically, the reacted material is transported to the solid-liquid separation unit, and the solid-liquid separation unit is used to separate the solid from the material to remove metal chlorides in the residual liquid.

[0127] In the method for removing metal chlorides provided in this embodiment, an oxygen-containing complexing agent is added to the reaction precipitation unit to precipitate the metal chlorides in the residual liquid in solid form. At the same time, the first cooling subunit and the second cooling subunit are used to cool the material in the reaction precipitation unit and condense and reflux the gas, avoiding an increase in viscosity caused by flash evaporation and concentration of the material, efficiently removing metal chlorides in the residual liquid, effectively reducing blockage during the treatment process, and extending the continuous use period of the device.

[0128] Figure 7 This is a flowchart of a method for treating polysilicon residual liquid provided in an embodiment of the present application. As Figure 7 shown, the execution subject of this method is the polysilicon residual liquid treatment system as described in the second aspect, and specifically includes the following steps:

[0129] S701. Use a metal chloride removal device to remove solid silicon powder and metal chloride complexes generated by reaction in the polysilicon residual liquid.

[0130] Specifically, the polysilicon residual liquid first enters the metal chloride removal device to remove metal chlorides in the polysilicon residual liquid using the metal chloride removal device, avoiding blockage of the system when treating the residual liquid.

[0131] S702. Use the solid treatment unit to treat the solid-containing material received from the metal chloride removal device.

[0132] Specifically, the residual liquid after being treated by the metal chloride removal device includes some solids, and the solids are transported to the solid treatment unit for post-treatment of the solids.

[0133] S703. Use the clear liquid treatment unit to treat the clear liquid received from the metal chloride removal device.

[0134] Specifically, the residual liquid after being treated by the metal chloride removal device also includes clear liquid, and the clear liquid is transported to the clear liquid treatment unit for post-treatment of the clear liquid, thereby completing the treatment of the polysilicon residual liquid.

[0135] The polysilicon residual liquid treatment method provided in this embodiment uses the metal chloride removal device as described above to remove substances that are likely to cause system blockage from the source, thereby ensuring the long-term operation of the treatment system. Then, the solid treatment unit and the clear liquid treatment unit are respectively used to treat the solids and liquids in the residual liquid to recover the available components in the residual liquid and remove impurities, improving the treatment efficiency of the polysilicon residual liquid.

[0136] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0137] Embodiment 1

[0138] The polysilicon residual liquid treatment system of this embodiment is as Figure 8 shown, and includes: a reaction precipitation tank 201, a drum filter 204, a hydrolysis tank 803, a clear liquid buffer tank 405, a first-stage clear liquid rectification tower 805, a second-stage clear liquid rectification tower 806, a cracking kettle 807, a cracking kettle rectification tower 808, and a hydrolysis kettle 809;

[0139] Factory A uses the polysilicon residue treatment system provided by this application for transformation. The polysilicon residue treatment method includes the following steps: The polysilicon residue enters the reaction precipitation tank 201. At the same time, an excessive amount of oxygen-containing complexing agent is also added to the reaction precipitation tank 201. The normal boiling point of the oxygen-containing complexing agent used is 200 °C. After the metal chloride reacts with the oxygen-containing complexing agent, a solid complex precipitate is formed and precipitated. In addition, the reaction precipitation tank 201 is provided with a jacket 202. Chilled water enters from the cooling medium inlet 202a and exits from the cooling medium outlet 202b, so that the chilled water circulates in the jacket 202, reducing the temperature of the material to 45 °C, thereby avoiding flash evaporation and making the residue concentrate and become viscous. At the same time, the gas generated by the material in the reaction precipitation tank 201 enters the cooler 203 through the gas phase pipeline, and after condensation, it flows back to the reaction precipitation tank 201 to ensure the fluidity of the material. Then, the material in the reaction precipitation tank 201 is sent to the drum filter 204 to separate the silicon powder and the solid metal chloride generated by the reaction from the residue. The solid is discharged from the blanking pipeline and enters the hydrolysis tank 803 for treatment. The separated clear liquid enters the clear liquid buffer tank 405. Subsequently, after being pressurized by the clear liquid buffer pump, it enters the first-stage clear liquid rectification tower 805. The operating pressure of the first-stage clear liquid rectification tower 805 is 30 kPaG, the top temperature is 57 °C, and the bottom temperature is 112 °C. Trichlorosilane and silicon tetrachloride are taken out from the top of the tower and sent out of the boundary. The bottom product of the tower, such as pentachlorodisilane, hexachlorodisilane and oxygen-containing complexing agent, enters the second-stage clear liquid rectification tower 806 for further rectification. In the second-stage clear liquid rectification tower 806, the operating pressure is 30 kPaG, the top temperature is 144 °C, and the bottom temperature is 158 °C. Light components such as pentachlorodisilane and hexachlorodisilane are taken out from the top of the tower and enter the cracking kettle 807 for cracking. The material taken out from the bottom of the tower contains the unreacted complexing agent, which is recycled to the reaction precipitation tank 201 for reuse. The material taken out from the top of the second-stage clear liquid rectification tower 806, together with the organic amine catalyst and hydrogen chloride, enters the cracking kettle 807 for reaction. Components such as trichlorosilane and silicon tetrachloride generated by cracking are taken out from the top of the cracking kettle rectification tower 808 and sent out of the boundary, while the non-crackable substances such as siloxane enter the hydrolysis kettle 809 for hydrolysis treatment.

[0140] Example 2

[0141] The polysilicon residue treatment system of this example is as Figure 9 shown, including: reaction precipitation tank 201, drum filter 204, dryer 903, clear liquid buffer tank 405, first-stage clear liquid rectification tower 805, second-stage clear liquid rectification tower 806, cracking kettle 807, cracking kettle rectification tower 808 and hydrolysis kettle 809;

[0142] Factory B uses the polysilicon residue treatment system provided by this application for transformation. Its polysilicon residue treatment method includes the following steps: The polysilicon residue enters the reaction precipitation tank 201. At the same time, an excessive amount of oxygen-containing complexing agent is also added to the reaction precipitation tank 201. The normal boiling point of the oxygen-containing complexing agent used is 105°C. After the metal chloride reacts with the oxygen-containing complexing agent, a solid complex precipitate is formed and precipitated. In addition, the reaction precipitation tank 201 is provided with a jacket 202. Chilled water enters from the cooling medium inlet 202a and exits from the cooling medium outlet 202b, so that the chilled water circulates in the jacket 202, cooling the material to 25°C, thereby avoiding flash evaporation and making the residue concentrate and become viscous. At the same time, the gas generated by the material in the reaction precipitation tank 201 enters the cooler 203 from the gas-phase pipeline, and after condensation, it flows back to the reaction precipitation tank 201 to ensure the fluidity of the material. Then, the liquid in the reaction precipitation tank 201 is sent to the drum filter 204 to separate the silicon powder and the solid metal chloride generated by the reaction from the residue. The solid is discharged from the blanking pipeline and enters the dryer 903 for treatment. In the dryer 903, the temperature is controlled at 105°C to evaporate the residual chlorosilane in the solid. The dried solid material is discharged and bagged for off-site treatment. The gaseous chlorosilane is condensed and sent to the clear liquid buffer tank 405. The clear liquid separated from the drum filter 204 is also sent to the clear liquid buffer tank 405. Subsequently, after being pressurized by the clear liquid buffer pump, it enters the first-stage clear liquid distillation column 805. The operating pressure of the first-stage clear liquid distillation column 905 is 30 kPaG, the top temperature is 57°C, and the bottom temperature is 101°C. Trichlorosilane and silicon tetrachloride are taken out from the top of the column and sent out of the boundary. The bottom product of the column, such as pentachlorodisilane, hexachlorodisilane, and oxygen-containing complexing agent, enters the second-stage clear liquid distillation column 806 for re-distillation. In the second-stage clear liquid distillation column 806, the operating pressure is 80 kPaG, the top temperature is 120°C, and the bottom temperature is 162°C. The top material of the column is mainly silicon tetrachloride, oxygen-containing complexing agent, and a small amount of pentachlorodisilane, hexachlorodisilane, etc. It is thermally coupled with the first-stage clear liquid distillation column 805 as the reboiler heat source. After condensation, a part flows back and a part circulates to the reaction precipitation tank 201. The bottom product of the column is mainly pentachlorodisilane, hexachlorodisilane, etc. It enters the cracking kettle 807 together with an organic amine catalyst, hydrogen chloride, chlorine, and hydrogen for reaction. The components such as dichlorosilane, trichlorosilane, and silicon tetrachloride generated by the cracking are taken out from the top of the cracking kettle distillation column 808 and sent out of the boundary, while the non-crackable substances such as siloxane enter the hydrolysis kettle 809 for hydrolysis treatment.

[0143] Comparative Example 1

[0144] The polysilicon residue treatment system of this comparative example is as Figure 10 shown, including: a flash evaporation unit 1001, a sedimentation unit 1002, a slurry drying unit 1003, a condensation unit 1004, a clear liquid distillation unit 1005, an aluminum removal unit 1006, a titanium removal unit 1007, and a cracking and distillation unit 403;

[0145] The specific method for treating polysilicon residual liquid includes the following steps: After the residual liquid enters the flash evaporation unit 1001, the residual liquid is concentrated, and then the concentrated liquid is successively transported to the sedimentation unit 1002 and the slurry drying unit 1003 to remove solids such as silicon powder. The separated clear liquid and the flashed gas-phase products are condensed by the condensation unit 1004 and then trichlorosilane and tetrachlorosilane are obtained through the clear liquid rectification unit 1005. High-boiling substances such as pentachlorodisilane and hexachlorodisilane are further separated into trichlorosilane and tetrachlorosilane after passing through the aluminum removal unit 1006, the titanium removal unit 1007, and the cracking and rectification unit 403.

[0146] It can be seen that in Comparative Example 1, as the residual liquid is concentrated with the extraction of the condensed gas, the viscosity increases, resulting in frequent blockage of the pipeline from the flash evaporation unit to the sedimentation unit; during the slurry drying process, since aluminum trichloride in the slurry is carried out from the gas phase and crystallizes in the gas-phase pipeline in solid form after the temperature drops, the pipeline is blocked; in the aluminum removal unit and the titanium removal unit, since solid precipitates are generated during the process and the material viscosity is high, it is extremely easy to block the equipment and pipelines, resulting in frequent maintenance, high labor intensity, and the device cannot operate in a long cycle.

[0147] When using the polysilicon residual liquid treatment system and the polysilicon residual liquid treatment method provided in this application for treatment, since the solids that are likely to cause pipeline blockage are removed at the source, and the jacket and cooler are used to prevent the residual liquid from concentrating and the viscosity from increasing, the system blockage situation is greatly reduced, and the system operation cycle is extended; and since the metal chlorides are removed at the beginning of the residual liquid treatment, the consumption of subsequent catalysts is also reduced, saving costs. Before the transformation, blockage removal and maintenance had to be carried out every 10 days. In the cracking and rectification unit, the catalyst consumption was 5 kg / ton of high-boiling substances. The transformed residual liquid treatment system can operate continuously for more than 6 months, and the catalyst consumption is reduced to 1 kg / ton of high-boiling substances.

[0148] Each embodiment in this specification is described in a related manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The above is only the preferred embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A metal chloride removal device, characterized in that, The device includes: a reaction precipitation unit and a solid-liquid separation unit, and the reaction precipitation unit is connected to the solid-liquid separation unit through pipelines; a first cooling sub-unit and a second cooling sub-unit are provided on the reaction precipitation unit; The reaction precipitation unit is used to react the added oxygen-containing complexing agent with the metal chloride in the residual liquid to generate a solid metal chloride complex; The first cooling sub-unit is used to cool the material in the reaction precipitation unit to a preset temperature; The second cooling sub-unit is used to condense and reflux the gas generated by the flash evaporation of the material; The solid-liquid separation unit is used to receive the material transported by the reaction precipitation unit and separate the solid in the material.

2. The device according to claim 1, characterized in that The reaction precipitation unit includes a reaction precipitation tank, the first cooling sub-unit is a jacket, and the second cooling sub-unit is a cooler; The jacket is arranged on the periphery of the reaction precipitation tank, and the jacket is provided with a cooling medium inlet and a cooling medium outlet; the cooler is arranged on the upper part of the reaction precipitation tank and is communicated with the reaction precipitation tank through a gas-phase pipeline and a liquid-phase pipeline; The jacket is used to introduce the cooling medium through the cooling medium inlet and flow out the cooling medium through the cooling medium outlet, so as to cool the material in the reaction precipitation tank to a preset temperature; The cooler is used to input the gas generated in the material into the cooler through the gas-phase pipeline, and condense the gas into a liquid by the cooler and then reflux it to the reaction precipitation tank through the liquid-phase pipeline.

3. The device according to claim 1 or 2, characterized in that, The solid-liquid separation unit is a drum filter, and the top of the drum filter is connected to the bottom of the reaction precipitation unit through a pipeline; The drum filter is used to transport the solid-containing material in the material to the solid treatment unit and transport the clear liquid in the material to the clear liquid treatment unit.

4. The device according to claim 1, characterized in that, The oxygen-containing complexing agent is in a liquid phase state, and the normal pressure boiling point range is 80-120 °C or 160-300 °C.

5. A polysilicon residual liquid treatment system, characterized in that The system includes a solid treatment unit, a clear liquid treatment unit, and the device according to any one of claims 1-4; The device is respectively connected to the solid treatment unit and the clear liquid treatment unit through pipelines; The device is used to remove the silicon powder in solid form and the generated metal chloride complex in the polysilicon residual liquid; The solid treatment unit is used to process the solid-containing material received from the device; The clear liquid treatment unit is used to process the clear liquid received from the device.

6. The polysilicon residue treatment system according to claim 5, wherein, The clear liquid treatment unit includes: a clear liquid first rectification unit, a clear liquid second rectification unit, and a cracking and rectification unit connected in sequence; The clear liquid first rectification unit is connected to the solid-liquid separation unit through a clear liquid buffer tank to receive the clear liquid transported by the solid-liquid separation unit, and transport the clear liquid to the clear liquid first rectification unit through a feed pump. The clear liquid first rectification unit is used to transport the processed clear liquid to the clear liquid second rectification unit; the clear liquid second rectification unit is connected to the reaction precipitation tank through a circulation pipeline to transport the substance containing the oxygen-containing complexing agent to the reaction precipitation tank.

7. The polysilicon residual liquid treatment system according to claim 6, wherein, The secondary rectification unit for the clear liquid includes a secondary rectification tower for the clear liquid. A first interface connecting to a circulation pipeline is provided at the bottom of the secondary rectification tower for the clear liquid; the normal pressure boiling point range of the oxygen-containing complexing agent is 160 - 300 °C.

8. The polysilicon residue treatment system according to claim 6, characterized in that, The secondary rectification unit for the clear liquid includes a secondary rectification tower for the clear liquid. A second interface connecting to a circulation pipeline is provided at the top of the secondary rectification tower for the clear liquid; the normal pressure boiling point range of the oxygen-containing complexing agent is 80 - 120 °C.

9. A polysilicon preparation system, characterized in that, It includes a polysilicon preparation system and a polysilicon residue treatment system according to any one of claims 5 - 8.

10. A method for removing metal chlorides, characterized in that, The method is applied to a metal chloride removal device according to any one of claims 1 - 4, and the method includes: Using a reaction precipitation unit to react the added oxygen-containing complexing agent with the metal chloride in the residue to generate a solid metal chloride complex; Using a first cooling sub-unit to cool the material in the reaction precipitation unit to a preset temperature; Using a second cooling sub-unit to condense and reflux the gas generated by the flashing of the material; Using a solid-liquid separation unit to receive the material conveyed by the reaction precipitation unit and separate the solid in the material.

11. A method for treating polysilicon residual liquid, characterized in that, The method is applied to a polysilicon residue treatment system according to any one of claims 5 - 8, and the method includes: Using a metal chloride removal device to remove the silicon powder in solid form and the generated metal chloride complex in the polysilicon residue; Using a solid treatment unit to treat the solid-containing material received from the metal chloride removal device; Using a clear liquid treatment unit to treat the clear liquid received from the metal chloride removal device.

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