A continuous fluorine-containing silicon slag recovery system and a recovery method

Abstract

This invention relates to the field of chemical production technology, and particularly to a continuous recovery system for fluorinated silicon slag. The continuous reaction module, from front to back, includes a preliminary digestion device, a multi-stage reaction device, and a circulating sedimentation device. The preliminary digestion device is used to hydrothermally treat the fluorinated silicon slag with sodium carbonate to obtain a mixed solution. The multi-stage reaction device is located at the rear of the preliminary digestion device and has multiple overflow chambers, ultimately generating overflow liquid and sodium fluoride solid phase. The circulating sedimentation device is located at the rear of the multi-stage reaction device to receive the overflow liquid from the multi-stage reaction device. A filtration module is located at the slag outlets of both the multi-stage reaction device and the circulating sedimentation device to filter and separate the solid phases discharged from both devices. The continuous recovery system for fluorinated silicon slag provided by this invention converts fluorinated silicon slag into high-value-added silica and sodium fluoride products, achieving dual recovery of silicon and fluorine resources, and has significant industrial value.

Description

Technical Field

[0001] This invention relates to the field of chemical production technology, and in particular to a continuous recovery system and method for fluorine-containing silicon slag. Background Technology

[0002] In the efficient utilization of associated fluorine resources from phosphate rock to produce anhydrous fluoride, silica and fluorosilicic acid are generated in the concentration system. The total fluorine content is approximately 10%, the silica content is approximately 30%, and a small amount of free SO4 is included. 2- Cl - It contains impurities such as fluorine-containing silicon slag, hence it is called fluorine-containing silicon slag.

[0003] In recent years, the promotion of industrial technology for the efficient utilization of associated fluorine resources from phosphate rock to produce anhydrous hydrogen fluoride by Wengfu Lantian Company has led to technological upgrades and capacity expansions at its various subsidiaries, reaching a capacity of 200,000 tons of anhydrous hydrogen fluoride and 300,000 tons of fluorinated silicon slag. The increasing stock of by-product fluorinated silicon slag has exacerbated the contradiction between its resource utilization and its potential for value creation. However, due to a lack of market for its application, the by-product fluorinated silicon slag has virtually no sales channel. Currently, a small amount of silicon slag can only be sold at low prices, while the majority is simply stockpiled due to a lack of high-value utilization technologies. This not only wastes resources but also impacts the production and operation of anhydrous hydrogen fluoride.

[0004] Fluorosilica slag has a simple main chemical composition and high chemical reactivity. At room temperature, it can react with NaOH aqueous solution to produce water glass (sodium silicate) and sodium fluoride. The generated water glass can react with CO2 to precipitate silica. The mother liquor, mainly composed of Na2CO3, can be recycled back to the upstream stage after treatment. Therefore, using fluorosilica slag, CO2, and NaOH as raw materials, and preparing water glass from the fluorosilica slag through CO2 decomposition to precipitate silica, can realize the industrialization and high-value utilization of silica slag.

[0005] Current processes for recovering fluorinated silica slag primarily utilize simple chemical equipment. The slag is dissolved in caustic soda, and sodium fluoride is recovered through filtration or crystallization. However, some sodium fluoride remains in the residual liquid. This leads to sodium fluoride contamination during subsequent CO2 precipitation due to the encapsulation, adsorption, or localized supersaturation of the silica precipitate. Consequently, the final product contains excessive fluorine, limiting its applications and relegating it to low-end filler or even waste disposal. Furthermore, the fluorine encapsulation not only wastes associated fluorine resources but also poses an environmental hazard of fluorine release during subsequent use.

[0006] Therefore, how to improve the equipment and process for recycling fluorine-containing silicon slag in order to obtain precipitated silica products with low fluorine content has become an urgent problem to be solved. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a continuous recycling system and method for fluorinated silicon slag, which solves the problem that existing fluorinated silicon slag recycling processes cannot obtain products such as precipitated silica with low fluorine content.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a continuous recycling system for fluorinated silicon slag, comprising: The continuous reaction module, from front to back, includes a preliminary digestion unit, a multi-stage reaction unit, and a circulating sedimentation unit. The preliminary digestion unit is used to hydrothermally treat fluorinated silica slag and sodium carbonate to obtain a mixed solution. The multi-stage reaction unit is located at the rear of the preliminary digestion unit and has multiple overflow chambers inside. It is used to dissolve the solid phase slag and separate fluorine from the mixed solution delivered from the preliminary digestion unit, ultimately generating overflow clear liquid and sodium fluoride solid phase. The circulating sedimentation unit is located at the rear of the multi-stage reaction unit and is used to receive the overflow clear liquid delivered from the multi-stage reaction unit. The filtration modules are respectively installed at the slag outlets of the multi-stage reaction device and the circulating sedimentation device, and are used to filter and separate the solid phase discharged from the multi-stage reaction device and the circulating sedimentation device.

[0009] In one embodiment, the multi-stage reaction apparatus includes: The main body has multiple overflow cavities inside; An overflow heat exchange assembly includes a first partition wall and a second partition wall extending upward from the bottom of the main body and spaced apart within a multi-stage overflow cavity. The first partition wall and the second partition wall sequentially divide the multi-stage overflow cavity from the center to the outer edge into a central cavity, a first annular cavity, and a second annular cavity. The first partition wall is located between the central cavity and the first annular cavity, and the second partition wall is located between the first annular cavity and the second annular cavity. The first partition wall and the second partition wall are respectively provided with a first flow channel and a second flow channel. The bottom of the central cavity is provided with a liquid inlet pipe assembly, the bottom of the first annular cavity is provided with a secondary slag outlet, the bottom of the second annular cavity is provided with a main slag outlet, and the top of the second annular cavity is provided with a liquid outlet. The planetary mixing assembly includes a planetary drive mechanism, a main mixing paddle assembly, and a planetary mixing paddle assembly. The planetary drive mechanism is located on the top of the main body. The main mixing paddle assembly is connected to the main drive end of the planetary drive mechanism and extends into the central cavity. The planetary mixing paddle assembly is connected to the planetary drive end of the planetary drive mechanism and extends into the first annular cavity. The planetary mixing paddle assembly rotates within the first annular cavity and revolves around the center of the main body along the first annular cavity. The sealing assembly is located between the planetary stirring assembly and the overflow heat exchange assembly. The stirring paddle assembly and the planetary stirring paddle assembly pass through the sealing assembly and enter the central cavity and the first annular cavity. The sealing assembly completely seals the multi-stage overflow cavity.

[0010] In one embodiment, the top of the main body is provided with a running cavity, and the planetary drive mechanism is disposed in the running cavity. The planetary drive mechanism includes a drive motor, a central gear, planetary gears, a fixed gear ring, and a planetary truss. The fixed gear ring is connected to the wall of the running cavity. The central gear is connected to the output end of the drive motor and is located at the center of the running cavity. The center of the central gear extends downward to the main drive end. The planetary gears mesh with both the fixed gear ring and the central gear. The center of the planetary gears extends downward to the planetary drive end. At least two planetary gears are provided. The planetary truss is connected to the top of the planetary gears.

[0011] In one embodiment, the planetary agitator assembly includes a planetary rod, a fixed frame, and a swing plate; one end of the planetary rod is connected to the planetary drive end, multiple fixed frames are arranged at intervals around the planetary rod, the fixed frames extend from the planetary rod away from the planetary rod, and the swing plate is embedded in the fixed frame.

[0012] In one embodiment, the swing plate is rotatably connected to the side of the fixed frame away from the planetary rod via a swing pivot. The fixed frame is provided with a blocking inclined wall, which is arranged on both sides of the swing pivot. The blocking inclined wall is used to limit the rotation angle of the swing plate.

[0013] In one embodiment, the sealing assembly includes a central plate, a rotating ring plate, and an outer ring plate. The rotating ring plate is disposed between the central plate and the outer ring plate, corresponding to the planetary stirring paddle assembly. The rotating ring plate is rotatably connected to the central plate and the outer ring plate. The planetary rod passes through the rotating ring plate and enters the first ring cavity. When the planetary rod revolves around the first ring cavity, it drives the rotating ring plate to rotate.

[0014] In one embodiment, the liquid inlet pipe assembly includes, from bottom to top, a contraction section, an adsorption section, and a diffusion section. The sidewall of the adsorption section is provided with an absorption channel, which connects the adsorption section to the bottom of the central cavity.

[0015] In one embodiment, a third partition wall is provided along the outer edge of the first partition wall, the bottom of the third partition wall is connected to the outer surface of the first partition wall, the highest point of the third partition wall is higher than the highest point of the first partition wall, an overflow annular cavity is formed between the first partition wall and the third partition wall, and an outflow gate is provided at the bottom of the third partition wall.

[0016] The present invention also provides a method for recovering fluorinated silicon slag using any of the methods described above, the steps of which are as follows: S1. Fluorosilicone slag and sodium carbonate solution are added to a preliminary digestion device and subjected to hydrothermal treatment at 140-180℃ and 0.4-1.0MPa for 30-240 min to obtain a mixed solution of sodium fluorosilicate. S2. The mixed solution obtained in step S1 is transported to the multi-stage overflow chamber of the multi-stage reaction device, and a sodium hydroxide solution with a concentration of 15% to 20% is added. A two-stage temperature gradient reaction is carried out in the multi-stage overflow chamber. The reaction solution overflows step by step along the multi-stage overflow chamber under continuous stirring, and the sodium fluoride solid phase and the overflow clear liquid are output separately. S3. The overflow clear liquid obtained in step S2 is transported to the circulating sedimentation device. CO2 gas is introduced into the circulating sedimentation device to carry out carbonization reaction. The pH value at the end of the reaction is controlled to be 8-10, so that sodium silicate is converted into silica precipitate. At the same time, the sodium carbonate solution is regenerated. After the reaction is completed, silica slurry and sodium carbonate mother liquor are obtained. S4. The sodium fluoride solid phase discharged from S2 and the silica slurry obtained from S3 are respectively sent to the filtration module for solid-liquid separation. The sodium fluoride solid phase is washed and dried to obtain sodium fluoride product, and the silica precipitate is washed and dried to obtain white carbon black product. The mother liquor containing sodium carbonate is sent back to the preliminary digestion unit for recycling.

[0017] In one embodiment, step S2, the secondary temperature gradient reaction includes: fully dissolving silicon dioxide in the central cavity at 85°C to 95°C to generate sodium silicate, and precipitating sodium fluoride as a solid phase in the first annular cavity at 45°C to 55°C.

[0018] The beneficial effects of this invention are as follows: 1. The fluorinated silicon slag continuous recycling system provided by this invention organically integrates key processes such as preliminary digestion, multi-stage reaction and cyclic sedimentation through special equipment, realizing continuous production from feeding to discharging, and effectively solving the problems of low efficiency caused by the dispersed equipment and intermittent operation of traditional processes.

[0019] 2. The fluorinated silicon slag continuous recycling system provided by the present invention adopts a multi-stage reaction device with multiple overflow chambers and planetary stirring components. Combined with two-stage temperature gradient control, high-temperature dissolution and low-temperature crystallization are continuously completed in the same device, ensuring that sodium fluoride is fully extracted and sodium silicate is efficiently converted, which greatly improves the fluorine-silicon separation efficiency and product purity.

[0020] 3. The fluorinated silicon slag recycling method provided by this invention efficiently converts waste fluorinated silicon slag into high-value-added silica and sodium fluoride products, realizing the dual recovery of silicon and fluorine resources. At the same time, the recycling of sodium carbonate in the carbonization mother liquor reduces alkali consumption, realizing "turning waste into treasure", and achieving both economic and environmental benefits.

[0021] 4. The low-fluorine silica product prepared by this invention has low fluorine content and high purity, which can meet the application needs of high-end fields such as rubber and coatings. It solves the problem of fluorine-containing silicon slag storage. At the same time, the by-product sodium fluoride can be reused as a fluorine resource. The processing is stable and reliable and has good prospects for promotion.

[0022] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects of the invention and other beneficial effects may be realized and obtained by means of the structures and / or components pointed out in the description and claims. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of an embodiment of the present invention; Figure 2 This is a three-dimensional schematic diagram of a multi-stage reaction device in one embodiment of the present invention; Figure 3 This is a top view of a multi-stage reaction apparatus according to an embodiment of the present invention; Figure 4 for Figure 3 Cross-sectional view at point AA; Figure 5 for Figure 4 A magnified view of a section at point B in the middle; Figure 6 for Figure 4 A magnified view of a section at point C; Figure 7 This is a schematic diagram of the internal structure of a multi-stage reaction device in one embodiment of the present invention.

[0024] Label Explanation: 1. Preliminary digestion device; 2. Multi-stage reaction device; 21. Main body; 211. Multi-stage overflow chamber; 2111. Central chamber; 2112. First annular chamber; 2113. Second annular chamber; 2114. Overflow annular chamber; 2115. Operating cavity; 22. Overflow heat exchange assembly; 221. First partition wall; 222. Second partition wall; 223. Third partition wall; 2231. Outflow gate; 24. Inlet pipe assembly; 241. Contraction section; 242. Adsorption section; 243. Diffusion section; 244. Absorption... 25. Receiving channel; 25. Planetary stirring assembly; 251. Planetary drive mechanism; 2511. Drive motor; 2512. Central wheel; 2513. Planetary gears; 2514. Fixed gear ring; 2515. Planetary truss; 252. Main stirring paddle assembly; 253. Planetary stirring paddle assembly; 2531. Planetary rod; 2532. Fixed frame; 2533. Swing plate; 26. Sealing assembly; 261. Central plate; 262. Rotating ring plate; 263. Outer ring plate; 3. Circulating sedimentation device; 4. Filter module. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0027] A continuous recycling system for fluorinated silicon slag includes: The continuous reaction module, from front to back, includes a preliminary digestion device 1, a multi-stage reaction device 2, and a circulating sedimentation device 3. The preliminary digestion device 1 is used to hydrothermally treat fluorinated silica slag and sodium carbonate to obtain a mixed solution. The multi-stage reaction device 2 is located at the rear of the preliminary digestion device 1 and has multiple overflow chambers 211 inside. It is used to dissolve the solid phase slag and separate fluorine from the mixed solution delivered by the preliminary digestion device 1, and finally generate overflow clear liquid and sodium fluoride solid phase. The circulating sedimentation device 3 is located at the rear of the multi-stage reaction device 2 and is used to receive the overflow clear liquid delivered by the multi-stage reaction device 2. The filter module 4 is installed at the slag outlet of the multi-stage reaction device 2 and the circulating sedimentation device 3, respectively, and is used to filter and separate the solid phase discharged from the multi-stage reaction device 2 and the circulating sedimentation device 3.

[0028] Specifically, the preliminary digestion device 1 can be made of high-temperature and high-pressure resistant titanium or fluoropolymer-lined high-temperature reactors, equipped with a heat exchange system and pressure adjustment device to meet the hydrothermal reaction conditions; the circulating sedimentation device 3 can be a stirred tank with pH monitoring or a continuous carbonization tower; the filtration module 4 can be a combination of a vacuum drum filter and an automatic chamber filter press, wherein the solid phase separation of sodium fluoride uses a vacuum drum filter to achieve continuous filtration, multi-stage countercurrent washing, and low moisture content slag discharge, and the separation of silica slurry uses an automatic chamber filter press or belt filter press, which is suitable for the fine particles and high specific surface area characteristics of silica, ensuring high solid content filter cake production and clear mother liquor reflux; all parts in contact with materials are made of 316L stainless steel, titanium, or fluoropolymer / plastic-lined for corrosion protection to meet the corrosion resistance requirements of fluorine-containing alkaline media and ensure long-term stable operation of the system. Those skilled in the art can select appropriate preliminary digestion device 1, circulating sedimentation device 3, and filtration module 4 as needed, without specific limitations.

[0029] Because the dissolution of silica and the precipitation of sodium fluoride in fluorosilicone slag have different requirements for reaction temperature and stirring intensity, and traditional single-chamber reactors are difficult to achieve continuous temperature gradient control and solid-liquid separation within the same device, the fluorosilicone separation efficiency is low and the energy consumption is high. Therefore, in this embodiment, the multi-stage reaction device 2 includes: The main body 21 has a multi-stage overflow cavity 211 inside; The overflow heat exchange assembly 22 includes a first partition wall 221 and a second partition wall 222 extending upward from the bottom of the main body 21 and spaced apart within a multi-stage overflow cavity 211. The first partition wall 221 and the second partition wall 222 divide the multi-stage overflow cavity 211 from the center to the outer edge into a central cavity 2111, a first annular cavity 2112, and a second annular cavity 2113. The first partition wall 221 is located between the central cavity 2111 and the first annular cavity 2112, and the second partition wall 222 is located between the first annular cavity 2112 and the second annular cavity 2113. The first partition wall 221 and the second partition wall 222 are respectively provided with a first flow channel and a second flow channel. The bottom of the central cavity 2111 is provided with a liquid inlet pipe assembly 24, the bottom of the first annular cavity 2112 is provided with a secondary slag outlet, the bottom of the second annular cavity 2113 is provided with a main slag outlet, and the top of the second annular cavity 2113 is provided with a liquid outlet. The planetary stirring assembly 25 includes a planetary drive mechanism 251, a main stirring paddle assembly 252, and a planetary stirring paddle assembly 253. The planetary drive mechanism 251 is disposed on the top of the main body 21. The main driving end of the main stirring paddle assembly 252 is connected to and extends into the central cavity 2111. The planetary stirring paddle assembly 253 is connected to the planetary drive end of the planetary drive mechanism 251 and extends into the first annular cavity 2112. The planetary stirring paddle assembly 253 rotates within the first annular cavity 2112 and revolves around the center of the main body 21 along the first annular cavity 2112. A sealing assembly 26 is positioned between the planetary stirring assembly 25 and the overflow heat exchange assembly 22. The stirring paddle assembly and planetary stirring paddle assembly 253 pass through the sealing assembly 26 and enter the central cavity 2111 and the first annular cavity 2112. The sealing assembly 26 completely seals the multi-stage overflow cavity 211. This configuration allows the material to rapidly dissolve silica at the high temperature in the central cavity 2111, then overflow into the first annular cavity 2112 at a low temperature to promote selective crystallization of sodium fluoride, and finally settle and separate in the second annular cavity 2113, achieving integrated continuous operation of dissolution-crystallization-separation. The planetary stirring assembly 25 eliminates mixing dead zones and protects the crystal structure, while the overflow heat exchange assembly 22 achieves precise temperature control and heat recovery, significantly improving the fluorosilicon separation efficiency and product purity, and reducing operating energy consumption.

[0030] Because the fluorinated silica slag reaction system contains a solid-liquid two-phase flow and its viscosity changes significantly with temperature, traditional stirring methods cannot simultaneously meet the requirements of efficient dissolution in the central cavity 2111 and uniform crystal precipitation in the annular cavity, and the driving components are susceptible to corrosion. Therefore, in this embodiment, the top of the main body 21 is provided with a running cavity 2115, and the planetary drive mechanism 251 is disposed in the running cavity 2115. The planetary drive mechanism 251 includes a drive motor 2511, a central wheel 2512, planetary gears 2513, a fixed gear ring 2514, and a planetary truss 2515. The fixed gear ring 2514 is connected to the wall of the running cavity 2115. The central wheel 2512 is connected to the output end of the drive motor 2511 and is located at the center of the running cavity 2115. The center of the central wheel 2512 extends downward to the main drive end. The planetary gears 2513 mesh with both the fixed gear ring 2514 and the central wheel 2512. The center of the planetary gears 2513 extends downward to the planetary drive end. The planetary gears 2513 are provided with at least 2 The planetary truss 2515 is connected to the top of the planetary gear 2513. The planetary stirring assembly 25 includes a planetary drive mechanism 251, a main stirring paddle assembly 252, and a planetary stirring paddle assembly 253. The planetary drive mechanism 251 is located on the top of the main body 21. The main stirring paddle assembly 252 is connected to the main drive end of the planetary drive mechanism 251 and extends into the central cavity 2111. The planetary stirring paddle assembly 253 is connected to the planetary drive end of the planetary drive mechanism 251 and extends into the first annular cavity 2112. The planetary stirring paddle assembly 253 rotates in the first annular cavity 2112 and revolves around the center of the main body 21 along the first annular cavity 2112. The sealing assembly 26 is located between the planetary stirring assembly 25 and the overflow heat exchange assembly 22. The stirring paddle assembly and the planetary stirring paddle assembly 253 pass through the sealing assembly 26 and enter the central cavity 2111 and the first annular cavity 2112. The sealing assembly 26 completely seals the multi-stage overflow cavity 211. This configuration places the drive mechanism within the enclosed operating cavity 2115, effectively preventing corrosion from the solution. The planetary drive mechanism 251 ensures efficient mixing in the central cavity 2111 while its planetary drive end's trajectory covers the first annular cavity 2112. This allows the planetary drive end to rotate and revolve slowly within the first annular cavity 2112, providing gentle stirring and guidance for the continuously generated sodium fluoride crystals and ensuring a suitable growth environment.

[0031] In this embodiment, the planetary stirring paddle assembly 253 includes a planetary rod 2531, a fixed frame 2532, and a swing plate 2533. One end of the planetary rod 2531 is connected to the planetary drive end. Multiple fixed frames 2532 are spaced around the planetary rod 2531 and extend from the planetary rod 2531 away from it. The swing plate 2533 is embedded within the fixed frame 2532. This configuration allows the planetary stirring paddle assembly 253 to adaptively swing according to the slurry resistance during its rotation and revolution, effectively buffering the stirring impact, reducing shear damage to the sodium fluoride crystals, and promoting orderly crystal growth and aggregation. The fixed frame 2532 ensures the overall structural strength of the planetary stirring paddle assembly 253 and can effectively guide the overall flow of the slurry in the first annular cavity 2112. Combined with the dynamically adaptable swing plate 2533, it can significantly reduce the impact of shear on the growth of sodium fluoride crystals while ensuring the stirring effect, effectively ensuring the separation effect of dissolved fluorine.

[0032] In this embodiment, the swing plate 2533 is rotatably connected to the side of the fixed frame 2532 away from the planetary rod 2531 via a swing shaft. The fixed frame 2532 has obstruction walls on both sides of the swing shaft, which limit the rotation angle of the swing plate 2533. By setting the obstruction walls, the swing range of the swing plate 2533 is limited, ensuring the guiding and stirring effect of the planetary stirring paddle assembly 253 on the solution.

[0033] In this embodiment, the sealing assembly 26 includes a central plate 261, a rotating ring plate 262, and an outer ring plate 263. The rotating ring plate 262 is positioned between the central plate 261 and the outer ring plate 263, corresponding to the planetary agitator assembly 253. The rotating ring plate 262 is rotatably connected to the central plate 261 and the outer ring plate 263. The planetary rod 2531 passes through the rotating ring plate 262 and enters the first annular cavity 2112. When the planetary rod 2531 revolves around the first annular cavity 2112, it drives the rotating ring plate 262 to rotate. This arrangement allows the rotating ring plate 262 to rotate synchronously with the planetary rod 2531. While ensuring that the operation of the planetary agitator assembly 253 is not affected, it effectively reduces the relative friction and wear between the sealing surfaces, achieves reliable sealing under dynamic conditions, effectively prevents leakage of high-temperature alkaline fluorine-containing media, and ensures the airtightness and pressure stability of the multi-stage overflow cavity 211. Specifically, the rotating ring plate 262 adopts a stepped structure, and rotating bearings are provided on the contact surfaces of the center plate 261, the outer ring plate 263, and the rotating ring plate 262.

[0034] Because the fluorinated silica slurry has a high solids content and is prone to settling, traditional feed pipes are easily clogged and the material distribution is uneven, resulting in a reaction dead zone at the bottom of the central cavity 2111. Therefore, in this embodiment, the liquid inlet pipe assembly 24 includes, from bottom to top, a contraction section 241, an adsorption section 242, and a diffusion section 243. The side wall of the adsorption section 242 is provided with an absorption channel 244, which connects the adsorption section 242 to the bottom of the central cavity 2111. This arrangement makes the liquid inlet pipe assembly 24 form a Venturi structure. When the mixed solution is fed, the high-speed liquid flow creates a negative pressure in the adsorption section 242, attracting the solution at the bottom of the central cavity 2111 to re-enter the liquid inlet pipe assembly 24 and mix and spray out. This effectively prevents scaling and the formation of dead zones at the bottom of the central cavity 2111, improves mixing efficiency and mass transfer effect, and ultimately ensures the reaction effect.

[0035] Specifically, the first and second flow channels enter and exit the first annular cavity 2112 and the second partition wall 222 from the bottom of the main body 21. Both flow channels form a spiral upward structure within the first annular cavity 2112 and the second partition wall 222, followed by a spiral downward structure. This arrangement ensures that the temperatures within the central cavity 2111 and the first annular cavity 2112 are independent and meet the temperature requirements of different reaction stages.

[0036] Because the temperature in the central cavity 2111 is higher than that in the first annular cavity 2112, to prevent the temperature of the central cavity 2111 from being directly conducted into the first annular cavity 2112, and to prevent the solution from flowing directly out from the top of the second partition wall 222 after passing through the top of the first partition wall 221, in this embodiment, a third partition wall 223 is provided along the outer edge of the first partition wall 221. The bottom of the third partition wall 223 is connected to the outer surface of the first partition wall 221, and the highest point of the third partition wall 223 is higher than the highest point of the first partition wall 221. An overflow annular cavity 2114 is formed between the first partition wall 221 and the third partition wall 223, and an outflow gate 2231 is provided at the bottom of the three partition walls. This arrangement ensures that the high-temperature material overflowing from the central cavity 2111 first enters the overflow annular cavity 2114 for buffering, and then enters the first annular cavity 2112 through the bottom outflow gate 2231, effectively preventing the high-temperature material from directly crossing the second partition wall 222 and causing a short circuit, thus ensuring that the flow path of the solution meets the requirements. Furthermore, this design reduces the direct heat transfer from the central cavity 2111 to the first annular cavity 2112, ensuring the stability of the low-temperature crystallization environment in the first annular cavity 2112. At the same time, it forces the material to flow downwards for mixing, extending the effective residence time and promoting the full growth and sedimentation separation of sodium fluoride crystals.

[0037] The present invention also provides a method for recovering fluorinated silicon slag using any of the methods described above, the steps of which are as follows: S1. Fluorosilicone slag and sodium carbonate solution are added to the preliminary digestion device 1 and subjected to hydrothermal treatment at 140-180℃ and 0.4-1.0MPa for 30-240 min to obtain a mixed solution of sodium fluorosilicate. S2. The mixed solution obtained in step S1 is transported to the multi-stage overflow chamber 211 of the multi-stage reaction device 2, and a sodium hydroxide solution with a concentration of 15% to 20% is added. A two-stage temperature gradient reaction is carried out in the multi-stage overflow chamber 211. The reaction solution overflows step by step along the multi-stage overflow chamber 211 under continuous stirring, and the sodium fluoride solid phase and the overflow clear liquid are output respectively. S3. The overflow clear liquid obtained in step S2 is transported to the circulating sedimentation device 3. CO2 gas is introduced into the circulating sedimentation device 3 to carry out carbonization reaction. The pH value at the end of the reaction is controlled to be 8-10, so that sodium silicate is converted into silica precipitate. At the same time, the sodium carbonate solution is regenerated. After the reaction is completed, silica slurry and sodium carbonate mother liquor are obtained. S4. The sodium fluoride solid phase discharged from S2 and the silica slurry obtained from S3 are respectively sent to the filtration module 4 for solid-liquid separation. The sodium fluoride solid phase is washed and dried to obtain sodium fluoride product, and the silica precipitate is washed and dried to obtain white carbon black product. The mother liquor containing sodium carbonate is sent back to the preliminary digestion device 1 for recycling.

[0038] In this embodiment, step S2, the secondary temperature gradient reaction includes: dissolving silicon dioxide at 85°C to 95°C in the central cavity 2111 to generate sodium silicate, and precipitating sodium fluoride as a solid phase at 45°C to 55°C in the first annular cavity 2112.

[0039] Preferably, in step S1, the feed flow rate of fluorinated silicon slag is controlled at 0.5–2.0 t / h, the feed flow rate of sodium carbonate solution is controlled at 2–10 m³ / h, and the liquid-solid ratio is controlled at 4–50 mL:1 g.

[0040] Preferably, in step S2, the feed flow rate of the sodium hydroxide solution is controlled to be 0.5–3.0 m³. 3 The total residence time of the material in the multi-stage overflow chamber 211 is 60–120 min / h. Specifically, in the central chamber 2111, the main stirring paddle assembly 252 operates at a stirring speed of 200–300 rpm, with a material residence time of 20–40 min. In the first annular chamber 2112, the planetary gears 2513 of the planetary stirring paddle assembly 253 revolve at a speed of 30–50 rpm and rotate at a speed of 80–120 rpm, with a material residence time of 40–80 min. In the second annular chamber 2113, the material residence time is 20–40 min. The overflow clear liquid output flow rate is 1.0–5.0 m³ / h. 3 / h; In step S3, the CO2 inlet flow rate is controlled to be 50-200 Nm³. 3The material residence time is 60–120 min / h; in step S4, the sodium fluoride solid phase is washed using a three-stage countercurrent washing process, with the washing liquid temperature at 60–80℃. Preferably, the effective volume ratio of the central cavity 2111, the first annular cavity 2112, and the second annular cavity 2113 is 1:(2–2.5):1, and the total effective volume of the three-stage cavities is 2.0–16.0 m³. 3 , Those skilled in the art can control the feed flow rate based on the actual volume of the central cavity 2111, the first annular cavity 2112, and the second annular cavity 2113, thereby controlling the residence time of the material in different cavities, without making specific limitations.

[0041] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0042] Although this document uses terms such as preliminary digestion apparatus and multi-stage reaction apparatus frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any kind of additional limitation would contradict the spirit of the invention. The terms "first," "second," etc. (if present), in the description and claims of the embodiments of the invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A continuous recycling system for fluorinated silicon slag, characterized in that, include: The continuous reaction module includes, from front to back, a preliminary digestion device (1), a multi-stage reaction device (2), and a circulating sedimentation device (3). The preliminary digestion device (1) is used to hydrothermally treat fluorinated silicon slag and sodium carbonate to obtain a mixed solution. The multi-stage reaction device (2) is located at the rear end of the preliminary digestion device (1) and has a multi-stage overflow chamber (211) inside. It is used to dissolve the solid phase slag and separate fluorine elements in the mixed solution delivered by the preliminary digestion device (1) to finally generate overflow clear liquid and sodium fluoride solid phase. The circulating sedimentation device (3) is located at the rear end of the multi-stage reaction device (2) and is used to receive the overflow clear liquid delivered by the multi-stage reaction device (2). The filtration module (4) is respectively installed at the slag outlet of the multi-stage reaction device (2) and the circulating sedimentation device (3) for filtering and separating the solid phase discharged from the multi-stage reaction device (2) and the circulating sedimentation device (3).

2. The continuous recycling system for fluorinated silicon slag according to claim 1, characterized in that, The multi-stage reaction device (2) includes: The main body (21) has the multi-stage overflow cavity (211) inside. An overflow heat exchange assembly (22) includes a first partition wall (221) and a second partition wall (222) extending upward from the bottom of the main body (21) and spaced apart within the multi-stage overflow cavity (211). The first partition wall (221) and the second partition wall (222) divide the multi-stage overflow cavity (211) from the center to the outer edge into a central cavity (2111), a first annular cavity (2112), and a second annular cavity (2113). The first partition wall (221) is located between the central cavity (2111) and the first... Between the annular cavities (2112), the second partition wall (222) is located between the first annular cavity (2112) and the second annular cavity (2113); the first partition wall (221) and the second partition wall (222) are respectively provided with a first flow channel and a second flow channel; the bottom of the central cavity (2111) is provided with a liquid inlet pipe group (24), the bottom of the first annular cavity (2112) is provided with a secondary slag outlet, the bottom of the second annular cavity (2113) is provided with a main slag outlet, and the top of the second annular cavity (2113) is provided with a liquid outlet; The planetary stirring assembly (25) includes a planetary drive mechanism (251), a main stirring paddle assembly (252), and a planetary stirring paddle assembly (253). The planetary drive mechanism (251) is disposed on the top of the main body (21). The main stirring paddle assembly (252) is connected to the main drive end of the planetary drive mechanism (251) and extends into the central cavity (2111). The planetary stirring paddle assembly (253) is connected to the planetary drive end of the planetary drive mechanism (251) and extends into the first annular cavity (2112). The planetary stirring paddle assembly (253) rotates within the first annular cavity (2112) and revolves around the center of the main body (21) along the first annular cavity (2112). A sealing assembly (26) is disposed between the planetary stirring assembly (25) and the overflow heat exchange assembly (22). The stirring paddle assembly and the planetary stirring paddle assembly (253) pass through the sealing assembly (26) and enter the central cavity (2111) and the first annular cavity (2112). The sealing assembly (26) completely seals the multi-stage overflow cavity (211).

3. The continuous recycling system for fluorinated silicon slag according to claim 2, characterized in that: The main body (21) has a rotating cavity (2115) at its top, and the planetary drive mechanism (251) is disposed in the rotating cavity (2115). The planetary drive mechanism (251) includes a drive motor (2511), a central gear (2512), planetary gears (2513), a fixed gear ring (2514), and a planetary truss (2515). The fixed gear ring (2514) is connected to the wall of the rotating cavity (2115), and the central gear (2512) is connected to the drive motor (2511). The output end of 11) is connected to and located at the center of the operating cavity (2115). The main drive end is derived downward from the center of the center wheel (2512). The planetary gear (2513) meshes with both the fixed gear ring (2514) and the center wheel (2512). The planetary drive end is derived downward from the center of the planetary gear (2513). At least two planetary gears (2513) are provided. The planetary truss (2515) is connected to the top of the planetary gear (2513).

4. The continuous recycling system for fluorinated silicon slag according to claim 3, characterized in that: The planetary stirring paddle assembly (253) includes a planetary rod (2531), a fixed frame (2532), and a swing plate (2533); one end of the planetary rod (2531) is connected to the planetary drive end, multiple fixed frames (2532) are arranged around the planetary rod (2531) at intervals, the fixed frames (2532) extend from the planetary rod (2531) in a direction away from the planetary rod (2531), and the swing plate (2533) is embedded in the fixed frame (2532).

5. The continuous recycling system for fluorinated silicon slag according to claim 4, characterized in that: The swing plate (2533) is rotatably connected to the fixed frame (2532) on the side away from the planetary rod (2531) via a swing pivot. The fixed frame (2532) is provided with a blocking inclined wall, which is arranged on both sides of the swing pivot. The blocking inclined wall is used to limit the rotation angle of the swing plate (2533).

6. The continuous recycling system for fluorinated silicon slag according to claim 4, characterized in that: The sealing assembly (26) includes a center plate (261), a rotating ring plate (262), and an outer ring plate (263). The rotating ring plate (262) is disposed between the center plate (261) and the outer ring plate (263) corresponding to the planetary stirring paddle assembly (253). The rotating ring plate (262) is rotatably connected to the center plate (261) and the outer ring plate (263). The planetary rod (2531) passes through the rotating ring plate (262) and enters the first annular cavity (2112). When the planetary rod (2531) revolves around the first annular cavity (2112), it drives the rotating ring plate (262) to rotate.

7. The continuous recycling system for fluorinated silicon slag according to claim 2, characterized in that: The liquid inlet pipe assembly (24) includes, from bottom to top, a contraction section (241), an adsorption section (242), and a diffusion section (243). The side wall of the adsorption section (242) is provided with an absorption channel (244), which connects the adsorption section (242) to the bottom of the central cavity (2111).

8. The continuous recycling system for fluorinated silicon slag according to claim 2, characterized in that: A third partition wall (223) is provided on the outer edge of the first partition wall (221). The bottom of the third partition wall (223) is connected to the outer surface of the first partition wall (221). The highest point of the third partition wall (223) is higher than the highest point of the first partition wall (221). An overflow annular cavity (2114) is formed between the first partition wall (221) and the third partition wall (223). An outflow gate (2231) is provided at the bottom of the third partition wall (223).

9. A method for recovering fluorinated silicon slag as described in any one of claims 1 to 8, characterized in that, The steps are as follows: S1. Fluorosilicone slag and sodium carbonate solution are added to the preliminary digestion device (1) and subjected to hydrothermal treatment at 140-180℃ and 0.4-1.0MPa for 30-240 min to obtain a mixed solution of sodium fluoride silicate. S2. The mixed solution obtained in step S1 is transported to the multi-stage overflow chamber (211) of the multi-stage reaction device (2), and a sodium hydroxide solution with a concentration of 15% to 20% is added. A two-stage temperature gradient reaction is carried out in the multi-stage overflow chamber (211). The reaction liquid overflows step by step along the multi-stage overflow chamber (211) under continuous stirring, and the sodium fluoride solid phase and the overflow clear liquid are output respectively. S3. The overflow clear liquid obtained in step S2 is transported to the circulating sedimentation device (3). CO2 gas is introduced into the circulating sedimentation device (3) to carry out carbonization reaction. The pH value at the end of the reaction is controlled to be 8-10, so that sodium silicate is converted into silica precipitate. At the same time, sodium carbonate solution is regenerated. After the reaction is completed, silica slurry and sodium carbonate mother liquor are obtained. S4. The sodium fluoride solid phase discharged from S2 and the silica slurry obtained from S3 are respectively sent to the filtration module (4) for solid-liquid separation. The sodium fluoride solid phase is washed and dried to obtain sodium fluoride product. The silica precipitate is washed and dried to obtain white carbon black product. The sodium carbonate mother liquor is sent back to the preliminary digestion device (1) for recycling.

10. The method for recovering fluorinated silicon slag according to claim 9, characterized in that, In step S2, the secondary temperature gradient reaction includes: dissolving silicon dioxide at 85℃~95℃ in the central cavity (2111) to generate sodium silicate, and precipitating sodium fluoride as a solid phase at 45℃~55℃ in the first annular cavity (2112).

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