Slag slurry treatment system

Abstract

The utility model discloses a slag slurry treatment system, which belongs to the technical field of slag slurry treatment in polycrystalline silicon production and comprises a transfer tank, a cryogenic stirring tank I, a coarse filter I, a fine filter I and a high-boiling-off tower which are sequentially connected, and the top of the high-boiling-off tower is connected with a cooler and then connected with a product liquid storage tank; the bottom of the high-boiling removal tower is sequentially connected with a cooling stirring tank, a cryogenic stirring tank II, a coarse filter II and a fine filter II through pipelines, a clear liquid outlet of the fine filter II is connected with a feeding hole of the high-boiling cracking device through a pipeline, and a light component outlet in the top of the high-boiling cracking device is connected with a material inlet of the high-boiling removal tower through a pipeline I; a slag discharging opening I in the bottom of the fine filter I is connected with a feeding opening I of the cryogenic stirring tank I through a pipeline II. The problems that in the prior art, when an evaporator or / and rotary drum equipment is / are adopted for treating slag generated in the cold hydrogenation process, the number of related equipment is large, pipelines are complex, the overhaul difficulty is large, and the silane recovery rate is low are solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of slag slurry treatment in polysilicon production, and in particular relates to a slag slurry treatment system. Background Art

[0002] In the production of polysilicon, the slag sent from the cold hydrogenation process first enters the settling tank of the slag slurry treatment process, and is then divided into two process technology routes. The first process is that after settling in the settling tank for a period of time, the side-collected clear liquid is directly sent to the rear-end high-boiling tower for treatment, and the material at the bottom of the settling tank is sent to the evaporator for treatment. The chlorosilane gas discharged from the top of the evaporator is condensed and the product liquid is sent to the high-boiling tower for further purification. The high-boiling substances and metal chlorides at the bottom of the evaporator are sent to the hydrolysis tank for treatment, and the process gas discharged from the top of the high-boiling tower is condensed and sent out as the product liquid. The slag discharged from the bottom of the high-boiling tower is stirred and cooled and then sent to the evaporator for treatment.

[0003] The second process is to send the gas directly to the drum for treatment without sedimentation in the settling tank, the clear liquid sent out from the drum is sent to the high boiling tower for treatment, the slag from the drum is sent to the evaporator for treatment, the chlorosilane gas discharged from the top of the evaporator is condensed and the product liquid is sent to the high boiling tower for further purification, the high boiling substances and metal chlorides at the bottom of the slurry evaporator are sent to the hydrolysis tank for treatment, the process gas discharged from the top of the high boiling tower is condensed and sent out as the product liquid, the slag discharged from the bottom of the high boiling tower is stirred and cooled and then sent to the evaporator for treatment, such as the invention patent application with the publication number of "CN115650241A" and the name of "A Polysilicon Production Slurry Treatment Process", in which a rotary drum filter is used to treat the material.

[0004] The above-mentioned prior art often uses evaporators and / or drums. Such processes involve a large number of equipment, complex pipelines, and a short service life of the drum and evaporator. The on-site maintenance workload is large, and the maintenance process is prone to corrosion around the on-site device. In particular, the longest operation cycle of the drum is only about 70 days, which makes the operation difficult. In addition, the recovery rate of silane is not high, part of the slag needs to be hydrolyzed, and wastewater treatment is difficult. For the first solution, if the sedimentation time is not long enough, there is a problem of bringing a large amount of metal chloride into the high-boiling tower to cause scaling of the reboiler, which reduces the operation cycle. Utility Model Content

[0005] The utility model aims to solve the problems in the prior art that when the slag delivered from the cold hydrogenation process is treated with a traditional evaporator and / or a rotary drum device, there are a large number of equipment involved, complex pipelines, a short service life of the rotary drum and the evaporator, a large amount of on-site maintenance work, corrosion around the on-site device is easily caused during the maintenance process, and the recovery rate of silane is not high.

[0006] In order to achieve the above-mentioned invention object, the technical solution of the utility model is as follows:

[0007] A slurry treatment system comprises a transfer tank, a cryogenic stirring tank I, a coarse filter I, a fine filter I and a high boiling tower connected in sequence, wherein the top of the high boiling tower is connected to a cooler and then to a product liquid storage tank;

[0008] The bottom of the high boiling tower is connected to the cooling stirring tank, the deep freezing stirring tank II, the coarse filter II, and the fine filter II in sequence through pipelines. The clear liquid outlet of the fine filter II is connected to the feed inlet of the high boiling cracking device through a pipeline. The light component outlet at the top of the high boiling cracking device is connected to the material inlet of the high boiling tower through pipeline I.

[0009] The slag discharge port I at the bottom of the fine filter I is connected to the feed port I of the deep-cold stirring tank I through a pipeline II.

[0010] Furthermore, the product liquid storage tank is connected to the steam heater I through the pipeline III and then connected to the fine filter I.

[0011] Furthermore, the light component outlet at the top of the high boiling cracking unit is connected to the steam heater II through pipeline IV and then to the fine filter II.

[0012] Furthermore, the outer sides of the cryogenic stirring tank I and the cryogenic stirring tank II are provided with a jacket through which a -10~-40°C Freon medium passes.

[0013] Furthermore, the coarse filter I and the coarse filter II are both basket filters, and a 40-mesh screen is provided in the basket filter, and the screen is connected and fixed to the main structure of the basket filter through a flange.

[0014] Furthermore, the coarse filter I and the coarse filter II are both connected to a nitrogen replacement pipeline.

[0015] Furthermore, the coarse filter I is connected in parallel with a plurality of coarse filters I with the same structure, and the coarse filter II is connected in parallel with a plurality of coarse filters II with the same structure.

[0016] Furthermore, the fine filter I and the fine filter II are ceramic or metal sintered filter element filters with a filtration accuracy of 1 μm.

[0017] Furthermore, the slag discharge port II of the fine filter II is connected to the feed port II of the cryogenic stirring tank II through the pipeline V.

[0018] Beneficial effects of the utility model:

[0019] 1. In the utility model, the slurry treatment system is used to remove metal chlorides (mainly aluminum chloride) in the slurry transported from the cold hydrogenation section as much as possible without using an evaporator and a rotary drum, and then crack high-boiling substances as much as possible, and finally obtain relatively pure chlorosilane to achieve the recovery of chlorosilane. Compared with the prior art, the system involves relatively fewer equipment and pipelines, and the equipment maintenance is relatively easier. In addition, the metal impurity content in the logistics after filtration by the fine filter I is less than 10ppbw, which can greatly extend the operation cycle of the high-boiling tower reboiler.

[0020] 2. In the utility model, part of the relatively pure product liquid obtained after treatment in the high boiling tower of the slurry treatment system is used to backwash the fine filter I after heating, without introducing other equipment or new backwashing liquid, thereby realizing the recycling of materials, reducing the use of pipes and reducing the equipment investment cost.

[0021] 3. In the utility model, the light components obtained after treatment by the high-boiling cracking device of the slurry treatment system are utilized, and part of the flow is diverted and heated by the steam heater II to backwash the fine filter II, without introducing other equipment or new backwashing liquid, thereby realizing the recycling of materials, reducing the use of pipes, and reducing the equipment investment cost.

[0022] 4. In the utility model, the jackets outside the deep-cold stirring tank I and the deep-cold stirring tank II are filled with -10~-40℃ Freon medium, which deep-cools the materials in the tanks and, under stirring conditions, precipitates aluminum chloride to form a suspension. Under this condition, most metal chlorides can be separated well.

[0023] 5. In the present invention, both coarse filter I and coarse filter II are basket filters, and a 40-mesh screen is provided in the basket filter. The screen is connected and fixed to the main structure of the basket filter through a flange, and most of the slag can be intercepted. Both coarse filter I and coarse filter II are connected to a nitrogen replacement pipeline, and 6 kg of nitrogen can be used to purge coarse filter I and coarse filter II online, that is, to achieve online replacement of the intercepted metal chloride. The metal chloride after complete replacement is in solid powder form, which can be directly bagged and treated as solid waste.

[0024] 6. In the utility model, the slag discharge port II of the fine filter II is connected to the feed port II of the cryogenic stirring tank II through the pipeline V. The fine filter II needs to discharge slag regularly, and the slag is sent back to the front cryogenic stirring tank II. The logistics enriched with metal chlorides are cryogenically treated in the cryogenic stirring tank II, and finally the metal chlorides are removed by the coarse filter II. This system can avoid introducing too many equipment (such as discharging slag into the evaporator), increase the complexity of the system, realize the recycling of materials, reduce the use of pipes, and reduce the equipment investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of an implementation method of Example 1.

[0026] Figure 2 It is a structural schematic diagram of an implementation method of Example 2.

[0027] Figure 3 It is a structural diagram of an implementation method of Example 3.

[0028] Figure 4 It is a schematic diagram of the structure of coarse filter I and coarse filter II.

[0029] Figure 5 It is a structural diagram of an implementation method of Example 4.

[0030] Figure 6 It is a structural diagram of an implementation method of Example 6.

[0031] Among them, 1. transfer tank; 2. cryogenic stirring tank I; 3. coarse filter I; 4. fine filter I; 5. high boiling tower; 6. cooler; 7. product liquid storage tank; 8. cooling stirring tank; 9. cryogenic stirring tank II; 10. coarse filter II; 11. fine filter II; 12. high boiling cracking unit; 13. pipeline I; 14. pipeline II; 15. pipeline III; 16. steam heater I; 17. pipeline IV; 18. steam heater II; 19. jacket; 20. screen; 21. nitrogen replacement pipeline; 22. pipeline V; 23. Freon medium pipeline; 24. cooling water inlet pipeline; 2.1. feed port I; 4.1. slag discharge port I; 5.1. material inlet; 9.1. feed port II; 11.1. clear liquid outlet; 11.2. slag discharge port II; 12.1. feed port; 12.2. light component outlet. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below in conjunction with the embodiments, but the implementation manner of the present invention is not limited thereto.

[0033] Example 1

[0034] This embodiment is the most basic implementation method, a slurry processing system, which belongs to the technical field of slurry processing in polysilicon production. Figure 1 , including a transfer tank 1, a deep-cold stirring tank Ⅰ2, a coarse filter Ⅰ3, a fine filter Ⅰ4 and a high-boiling tower 5 connected in sequence, and the top of the high-boiling tower 5 is connected to a cooler 6 and then to a product liquid storage tank 7.

[0035] The bottom of the high boiling tower 5 is connected to the cooling stirring tank 8, the deep freezing stirring tank II9, the coarse filter II10, and the fine filter II11 in sequence through pipelines. The clear liquid outlet 11.1 of the fine filter II11 is connected to the feed inlet 12.1 of the high boiling cracking device 12 through a pipeline. The light component outlet 12.2 at the top of the high boiling cracking device 12 is connected to the material inlet 5.1 of the high boiling tower 5 through a pipeline I13.

[0036] The slag discharge port Ⅰ4.1 at the bottom of the fine filter Ⅰ4 is connected to the feed port Ⅰ2.1 of the deep-cooling stirring tank Ⅰ2 through a pipeline Ⅱ14.

[0037] Preferably, the jacket of the cooling stirring tank 8 is connected to the cooling water inlet pipeline 24, and the cooling water is used to preliminarily cool the material in the tank. The outer sides of the deep-cold stirring tank I2 and the deep-cold stirring tank II9 are provided with a jacket 19 through which a -10~-40℃ Freon medium is passed. Figure 1 In this embodiment, -20°C Freon medium is introduced into the jacket 19 of the cryogenic stirring tank II 9 through the Freon medium pipeline 23 to be cryogenically cooled.

[0038] When in use, the slag sent from the cold hydrogenation section after being cooled by circulating water is temporarily stored in the transfer tank 1, and then sent to the deep-cold stirring tank Ⅰ2 with a stirring mechanism. Under the stirring and deep-cold temperature conditions of the deep-cold stirring tank Ⅰ2, suspended matter is precipitated in the material, and then the mixed material is continuously transported to the coarse filter Ⅰ3 to filter and remove the metal chloride in the logistics, which can significantly reduce the load of the rear-end precision filtration. Then it is sent to the fine filter Ⅰ4 for re-filtration to further ensure that the precipitated metal chloride can be intercepted.

[0039] The fine filter Ⅰ4 needs to be discharged regularly, and the slag is returned to the front-end deep-cold mixing tank Ⅰ2 through pipeline Ⅰ13 to achieve recycling, avoiding the introduction of too many equipment (such as discharging slag into the evaporator) to increase the complexity of the system.

[0040] The recombinant fraction discharged from the bottom of the high-boiling tower 5 is a slag material containing about 80% of the high-boiling content, and the rest is chlorosilane and metal chloride. It is then initially water-cooled in the cooling and stirring tank 8, further deep-cooled in the deep-cooling stirring tank II9, and then filtered in two stages by the coarse filter II10 and the fine filter II11. After filtration, the material with less metal impurities is obtained, and then sent to the high-boiling cracking device 12 for cracking treatment. The cracking product is then sent to the front-end high-boiling tower 5 through the pipeline I13. The high-boiling tower 5 is used to separate the chlorosilane produced by cracking and the uncracked high-boiling. The cycle is repeated to ensure that all high-boiling substances can be cracked and the high-boiling substances can be fully recovered.

[0041] Example 2

[0042] This embodiment is a further optimization of the embodiment 1, the difference being that the product liquid storage tank 7 is connected to the steam heater Ⅰ16 through the pipeline Ⅲ15 and then connected to the fine filter Ⅰ4. Figure 2 Part of the product liquid in the product liquid storage tank 7 is heated by the steam heater Ⅰ16 and used as high-temperature backwash liquid for the fine filter Ⅰ4 to wash it.

[0043] Example 3

[0044] Compared with Example 1-2, the difference between this embodiment and Example 1-2 is that the light component outlet 12.2 at the top of the high boiling cracking unit 12 is connected to the steam heater II 18 through the pipeline IV 17 and then connected to the fine filter II 11. Figure 3 The fractional flow in the cracking liquid obtained after being treated by the high-boiling cracking device 12 is heated by the steam heater II 18 and used as the high-temperature backwash liquid of the fine filter II 11 to wash it.

[0045] Example 4

[0046] The present embodiment is different from the embodiment 1-3 in that the coarse filter Ⅰ3 and the coarse filter Ⅱ10 are basket filters, and the basket filter is provided with a 40-mesh screen 20. Figure 4 , the screen 20 is connected and fixed to the main structure of the basket filter through the flange. The upper and lower ends of the screen 20 of the basket filter are fixed by flanges. The chlorosilane liquid containing slag enters the screen 20 from the top of the basket filter, and the clean chlorosilane liquid filtered by the screen 20 enters the rear-end fine filter Ⅰ4 or fine filter Ⅱ11. The slag intercepted by the screen 20 is stored in the screen 20. When the slag accumulates to a certain amount, there will be a problem of slow pressing speed of the deep-cold stirring tank Ⅰ2 and the deep-cold stirring tank Ⅱ9. At this time, the spare blue filter can be opened, and the nitrogen replacement pipeline 21 of the basket filter cut out of the system is opened for pressure replacement. After the replacement is completed, the slag discharge valve at the bottom of the basket filter is opened to bag the discharged slag.

[0047] Preferably, the coarse filter I3 and the coarse filter II10 are both connected to a nitrogen replacement pipeline 21, and 6 kg of nitrogen can be used to perform online replacement of the coarse filter I3, that is, to achieve online replacement of the intercepted metal chloride. The metal chloride after complete replacement is in the form of solid powder and can be directly bagged and treated as solid waste.

[0048] Preferably, the coarse filter I3 may be connected in parallel with a plurality of coarse filters I3 having the same structure as the coarse filter I3, and the coarse filter II10 may be connected in parallel with a plurality of coarse filters II10 having the same structure as the coarse filter II10. The switching use of multiple filters in parallel may extend the continuous operation time of the system.

[0049] Preferably, the fine filter I4 and the fine filter II11 are ceramic or metal sintered filter element filters with a filtration accuracy of 1 μm.

[0050] Example 5

[0051] The difference between this embodiment and the embodiments 1-4 is that the slag discharge port II11.2 of the fine filter II11 is connected to the feed port II9.1 of the cryogenic stirring tank II9 through the pipeline V22. Figure 5 As shown, the slag obtained after treatment by the fine filter II 11 contains some chlorosilanes and high boiling substances, which are sent to the deep-cooling stirring tank II 9 through pipeline V22 for further treatment, so that the chlorosilanes and high boiling substances can be fully recovered.

[0052] Example 6

[0053] To facilitate the public to understand the present solution, this embodiment takes a preferred slurry treatment system as an example to further illustrate the present solution.

[0054] During the production of polysilicon, the slag sent from the cold hydrogenation section mainly contains three substances: chlorosilane, metal chloride, and high-boiling substances. The main purpose of treating the slag is to remove the metal chloride and recover the chlorosilane as much as possible. The high-boiling substances can be cracked and recovered. 95% of the metal chloride in the slag is aluminum chloride. According to the characteristics of aluminum chloride materials, when the temperature is reduced, it can precipitate in the material and form suspended matter. In this scheme, it is considered to first perform deep cold treatment on the material and then remove the metal chloride. If the metal chloride is removed, only chlorosilane and high-boiling substances are left in the slag. Both of these substances are liquids, and the boiling point difference is large. Chlorosilane and high-boiling substances can be easily separated by a distillation tower.

[0055] The slurry processing system of this embodiment refers to Figure 6 , specifically including a transfer tank 1, a cryogenic stirring tank Ⅰ2, a coarse filter Ⅰ3, a fine filter Ⅰ4 and a high boiling tower 5 connected in sequence, the top of the high boiling tower 5 is connected to a cooler 6 and then to a product liquid storage tank 7; the bottom of the high boiling tower 5 is connected to a cooling stirring tank 8, a cryogenic stirring tank Ⅱ9, a coarse filter Ⅱ10, and a fine filter Ⅱ11 in sequence through pipelines, the clear liquid outlet 11.1 of the fine filter Ⅱ11 is connected to the feed port 12.1 of the high boiling cracking device 12 through a pipeline, and the light component outlet 12.2 at the top of the high boiling cracking device 12 is connected to the material inlet 5.1 of the high boiling tower 5 through a pipeline Ⅰ13; the slag discharge port Ⅰ4.1 at the bottom of the fine filter Ⅰ4 is connected to the feed port Ⅰ2.1 of the cryogenic stirring tank Ⅰ2 through a pipeline Ⅱ14. The coarse filter Ⅰ3 is also connected in parallel with a coarse filter Ⅰ3 with the same structure, and the coarse filter Ⅱ10 is also connected in parallel with a coarse filter Ⅱ10 with the same structure, one for use and one for standby, which can be switched for use autonomously. The jacket of the cooling and stirring tank 8 is connected to a cooling water inlet pipeline 24, and the cooling water is used to preliminarily cool the material in the tank.

[0056] In this embodiment, the product liquid storage tank 7 is connected to the steam heater I16 through the pipeline III15 and then connected to the fine filter I4.

[0057] In this embodiment, the light component outlet 12.2 at the top of the high boiling cracking unit 12 is connected to the steam heater II18 through the pipeline IV17 and then connected to the fine filter II11.

[0058] In this embodiment, the outer sides of the cryogenic stirring tank I2 and the cryogenic stirring tank II9 are provided with a jacket 19 through which -20°C Freon medium is passed. The -20°C Freon medium is passed into the jacket 19 of the cryogenic stirring tank II9 through the Freon medium pipeline 23 to be cryogenically cooled.

[0059] In this embodiment, the coarse filter I3 and the coarse filter II10 are both basket filters, and the basket filter is provided with a 40-mesh screen 20. Figure 4 The screen 20 is connected and fixed to the main structure of the basket filter through a flange.

[0060] In this embodiment, the coarse filter I3 and the coarse filter II10 are both connected with a nitrogen replacement pipeline 21.

[0061] In this embodiment, the fine filter I4 and the fine filter II11 are ceramic or metal sintered filter element filters with a filtration accuracy of 1 μm.

[0062] In this embodiment, the slag discharge port II11.2 of the fine filter II11 is connected to the feed port II9.1 of the cryogenic stirring tank II9 through the pipeline V22.

[0063] During specific implementation, the valve on the nitrogen replacement pipeline 21 can be a remote valve, which is convenient for remote operation.

[0064] When in use, the slag sent from the cold hydrogenation section after being cooled by circulating water is temporarily stored in the transfer tank 1, and then sent to the deep-cold stirring tank Ⅰ2 with a stirring mechanism, and then the jacket 19 outside the deep-cold stirring tank Ⅰ2 is passed with a Freon medium of about -20°C. Under the action of the deep-cold stirring tank Ⅰ2, suspended matter is precipitated in the material, and then the mixed material is continuously transported to the coarse filter Ⅰ3 to filter and remove the metal chloride in the logistics, which significantly reduces the load of the rear-end precision filtration.

[0065] In addition, the coarse filter Ⅰ3 is connected to a nitrogen replacement pipeline 21, and 6 kg of nitrogen can be used to replace the coarse filter Ⅰ3 online, that is, to achieve online replacement of the intercepted metal chloride. The metal chloride after complete replacement is in the form of solid powder, which can be directly bagged and treated as solid waste. After the logistics is coarsely filtered by the coarse filter Ⅰ3, it is sent to the fine filter Ⅰ4 for re-filtration to further ensure that the precipitated metal chloride can be intercepted. After filtering by the fine filter Ⅰ4, the metal impurity content in the logistics is less than 10ppbw. When the existing evaporator and / or drum equipment is used for treatment, the metal impurities of the material entering the high-boiling tower 5 are generally between 20,000-500,000 ppbw. Therefore, the use of this slurry treatment system can greatly extend the operation cycle of the reboiler of the high-boiling tower 5.

[0066] Fine filter Ⅰ4 needs to discharge slag regularly, and the slag is returned to the front cryogenic mixing tank Ⅰ2 to achieve recycling, avoiding the introduction of too many equipment (such as discharging slag into the evaporator) to increase the complexity of the system. Two basket filters of the same structure are set at coarse filter Ⅰ3 and coarse filter Ⅱ10 for parallel switching and use to extend the continuous operation time of the system.

[0067] The recombinant fraction discharged from the bottom of the high-boiling tower 5 is a slag material containing about 80% of the high-boiling content, and the rest is chlorosilane and metal chloride. It is then initially water-cooled in the cooling and stirring tank 8, further deep-cooled in the deep-freezing stirring tank II9 with a Freon medium of about -20°C, and then filtered in two stages by a coarse filter II10 and a fine filter II11. After filtration, the material with metal impurities less than 100 bbpw is obtained, and then sent to the high-boiling cracking device 12 for cracking treatment. Since the cracking reaction conversion rate is about 60%-80%, the cracking product is then sent to the front-end high-boiling tower 5 through the pipeline I13. The chlorosilane produced by the cracking and the uncracked high-boiling are separated by the high-boiling tower 5, and the cycle is repeated to ensure that all high-boiling substances can be cracked and the high-boiling substances can be fully recovered.

[0068] The working principle of the coarse filter II 10 is the same as that of the coarse filter I 3. The metal chloride obtained after treatment is in the form of solid powder and is directly bagged and treated as solid waste.

Claims

1. A slurry processing system, characterized in that: It comprises a transfer tank (1), a cryogenic stirring tank I (2), a coarse filter I (3), a fine filter I (4) and a high boiling tower (5) which are connected in sequence, and the top of the high boiling tower (5) is connected to a cooler (6) and then to a product liquid storage tank (7); The bottom of the high boiling tower (5) is connected to the cooling stirring tank (8), the deep freezing stirring tank II (9), the coarse filter II (10), and the fine filter II (11) in sequence through pipelines; the clear liquid outlet (11.1) of the fine filter II (11) is connected to the feed inlet (12.1) of the high boiling cracking device (12) through a pipeline; the light component outlet (12.2) at the top of the high boiling cracking device (12) is connected to the material inlet (5.1) of the high boiling tower (5) through a pipeline I (13); The slag discharge port I (4.1) at the bottom of the fine filter I (4) is connected to the feed port I (2.1) of the cryogenic stirring tank I (2) through a pipeline II (14).

2. A slurry processing system according to claim 1, characterized in that: The product liquid storage tank (7) is connected to the steam heater I (16) through the pipeline III (15) and then connected to the fine filter I (4).

3. A slurry processing system according to claim 1, characterized in that: The light component outlet (12.2) at the top of the high boiling cracking unit (12) is connected to the steam heater II (18) through pipeline IV (17) and then to the fine filter II (11).

4. A slurry processing system according to claim 1, characterized in that: The outer sides of the cryogenic stirring tank I (2) and the cryogenic stirring tank II (9) are provided with a jacket (19) through which a -10 to -40°C Freon medium flows.

5. A slurry processing system according to claim 1, characterized in that: The coarse filter I (3) and the coarse filter II (10) are both basket filters, each of which is provided with a 40-mesh screen (20), which is connected and fixed to the main structure of the basket filter via a flange.

6. A slurry processing system according to claim 5, characterized in that: The coarse filter I (3) and the coarse filter II (10) are both connected to a nitrogen replacement pipeline (21).

7. A slurry processing system according to claim 5, characterized in that: The coarse filter I (3) is connected in parallel with a plurality of coarse filters I (3) having the same structure as the coarse filter I, and the coarse filter II (10) is connected in parallel with a plurality of coarse filters II (10) having the same structure as the coarse filter II.

8. A slurry processing system according to claim 1, characterized in that: The fine filter I (4) and the fine filter II (11) are ceramic or metal sintered filter element filters with a filtration accuracy of 1 μm.

9. A slurry processing system according to claim 1, characterized in that: The slag discharge port II (11.2) of the fine filter II (11) is connected to the feed port II (9.1) of the cryogenic stirring tank II (9) through a pipeline V (22).

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