Device and process for recovering yellow phosphorus in phosphorus sludge based on multistage flash evaporation and continuous evaporation

Abstract

The invention discloses a device and a process for recovering yellow phosphorus in phosphorus sludge based on multistage flash evaporation continuous evaporation. The device comprises a pretreatment system, a drying-pyrolysis-evaporation integrated system and a product recovery and treatment system, phosphorus slurry is pretreated in the pretreatment system in a steam crushing and mixing mode and then enters the drying-pyrolysis-evaporation integrated system for precise temperature control through gradient electromagnetic heating, and the product recovery and treatment system is used for recycling the phosphorus slurry. And finally, the yellow phosphorus enters a product recovery and treatment system, so that the yellow phosphorus and phosphorus-free residues are recovered. According to the device and the process, phosphorus slurry can be uniformly fed in the whole process, phosphorus is evaporated thoroughly, and the yellow phosphorus recovery rate reaches 95% or above; the equipment sealing performance is good, and the risk of ignition caused by spontaneous combustion of yellow phosphorus is effectively avoided; the phosphorus sludge processing capacity reaches 0.5-1.0 ton per hour, continuous and stable operation can be performed for more than 720 hours, and the recycled residues are uniform in granularity and can be used for production of phosphate fertilizers, cement and the like, so that resource recycling is realized.

Description

Technical Field

[0001] This invention belongs to the field of phosphorus recovery and treatment technology, specifically relating to a device and process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash evaporation. Background Technology

[0002] Phosphorus mud is one of the main byproducts of yellow phosphorus production via the electric furnace process. Its phosphorus content varies depending on the degree of refining during production, generally ranging from 5% to 40%. The generation of phosphorus mud not only increases production costs for yellow phosphorus producers but also causes serious environmental pollution. Statistics show that approximately 0.1 to 0.2 tons of phosphorus mud are generated for every ton of yellow phosphorus produced. The main impurities are SiO2, CaO, Fe2O3, Al2O3, mineral powder, and coke dust, with the remainder being water. The hydrophilic SiO2 partially forms silica gel and adsorbs impurities such as yellow phosphorus, mineral powder, and coke dust, forming a viscous and stable slurry. This slurry contains some yellow phosphorus, forming a relatively stable and difficult-to-separate gel.

[0003] Currently, the main processes for recovering yellow phosphorus from phosphorus mud include high-temperature distillation, solvent extraction, and mechanical pressure filtration, and are mainly based on traditional rotary kiln evaporation equipment. The technology is relatively backward, and the prominent technical defects are: (1) Existing equipment (such as rotary kilns) mostly adopts overall heating or intermittent temperature control, which makes it difficult to achieve precise control of gradient temperature field, resulting in incomplete removal of water, low yellow phosphorus evaporation efficiency, low phosphorus recovery rate, and temperature fluctuations are prone to phosphorus vapor flash fire or local high-temperature leakage of equipment, which poses a huge safety hazard; (2) Due to the high viscosity and uneven solid-liquid composition of phosphorus mud, the existing feeding system is prone to blockage and pulse flow, resulting in uneven material distribution in the evaporator and heat and mass transfer. (2) Efficiency declines, batch processing capacity is limited, equipment stability is insufficient, and continuous production is difficult to achieve; (3) Traditional static seals or packing seals are prone to failure in high-temperature, phosphorus-containing media, air infiltration leads to spontaneous combustion of yellow phosphorus, causing safety accidents, and phosphorus vapor leakage causes environmental pollution and product loss; (4) Existing condensation processes mostly use direct water cooling or simple indirect cooling. Yellow phosphorus is prone to generate phosphoric acid or hypophosphite after contact with water, which adheres to the pipe wall to form scale. Residual phosphorus components in the uncondensed gas phase precipitate in the low-temperature zone, causing blockage of pipelines and equipment; (5) Traditional discharge methods rely on manual slag discharge or intermittent discharge, the system has poor sealing performance, and the labor intensity is high, with a high risk of secondary pollution. Therefore, it is urgent to develop an efficient, safe, continuous, and environmentally friendly phosphorus mud recovery process and device.

[0004] In existing processes, to improve the uniformity of phosphorus sludge feeding and phosphorus evaporation efficiency, the phosphorus stripping device is modified. This involves using mechanical stirring to disrupt the colloidal structure of the phosphorus sludge, leveraging the physical and chemical properties of the material to promote the aggregation and contact between yellow phosphorus particles. However, the existing stirring process is highly susceptible to ignition of yellow phosphorus due to friction and air leakage, and the separation of phosphorus from other impurities is not thorough enough, resulting in low subsequent phosphorus recovery efficiency. Summary of the Invention

[0005] To address the problems of low recovery rates, frequent downtime for maintenance due to scaling and blockage of furnace tubes, lack of inertial protection and poor equipment sealing leading to phosphorus combustion risks, and condensation blockage in traditional phosphorus mud recovery equipment, this invention, targeting the inherent physicochemical characteristics of phosphorus mud, combines the principles of evaporation, drying, and pyrolysis to provide a device and process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash continuous evaporation. By integrating a pretreatment system, an integrated system, and a product recovery and processing system, a phosphorus evaporation process integrating gradient temperature-controlled thin-layer evaporation, flash explosion, and automatic discharge with mechanical seal is formed. This meets the requirements of precise temperature control, uniform feeding and stable mass transfer, full-process airtight leak prevention, and prevention of coking and blockage as well as efficient condensation in the phosphorus mud recovery process. It achieves efficient, safe, and environmentally friendly recovery of yellow phosphorus from phosphorus mud, and has good phosphorus recovery efficiency for phosphorus mud slurry under different operating conditions.

[0006] The technical solution of the present invention is as follows:

[0007] The device for recovering yellow phosphorus from phosphorus mud based on multi-stage flash continuous evaporation consists of a pretreatment system, an integrated drying-pyrolysis-evaporation system, and a product recovery and processing system. The pretreatment system comprises a phosphorus mud slurry storage tank, a phosphorus mud homogenizing mixing tank, and a dosing tank. The integrated drying-pyrolysis-evaporation system consists of a primary material drying unit, a secondary material drying and primary pyrolysis synchronous unit, a secondary material pyrolysis and primary evaporation synchronous unit, and a secondary high-efficiency evaporation unit connected in sequence. Each unit includes furnace tubes and a rotating conveyor belt installed inside the furnace tubes. The product recovery and processing system consists of a residue collection bin, a residue crushing and moisture-proof sealing unit, a phosphorus vapor condensation and collection device, and a multi-stage spray tower. The phosphorus mud homogenizing mixing tank is equipped with an inlet, a reagent dosing port, a discharge port, and a steam inlet. The phosphorus mud slurry storage tank is connected to the inlet of the phosphorus mud homogenizing mixing tank via a pneumatic pump. The reagent dosing port at the top of the phosphorus mud homogenizing mixing tank is connected to a dosing tank, and the discharge port at the bottom is connected to the primary material drying unit via a screw pump. The furnace tubes in the primary material drying unit are equipped with a material inlet, a material outlet, and a steam outlet. The steam outlet is connected to the steam inlet at the bottom of the homogenized mixing tank of phosphorus mud via a steam transfer pump. The material outlet is connected to the material secondary drying and primary pyrolysis synchronous unit via a screw pump. The furnace tubes in the material secondary drying and primary pyrolysis synchronous unit are equipped with a material inlet, a material outlet, and a steam outlet. The steam outlet is connected to the phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is connected to the material secondary pyrolysis and primary evaporation synchronous unit via a screw pump. The furnace tubes in the material secondary pyrolysis and primary evaporation synchronous unit are equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to the phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is connected to the material secondary high-efficiency evaporation unit via a screw pump. The furnace tubes in the material secondary high-efficiency evaporation unit are equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to the phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is sequentially connected to the residue collection bin and the residue crushing and moisture-proof sealing treatment unit. The phosphorus vapor condensation and collection device is equipped with a phosphorus vapor inlet and a material outlet. The material outlet is sequentially connected to the multi-stage spray tower, the yellow phosphorus receiving tank, and the tail gas purification system.

[0008] Furthermore, the reagent in the dosing tank is ammonia water or sodium carbonate solution.

[0009] Furthermore, the homogenizing tank for phosphorus mud is equipped with a spiral stirring device, the spiral stirring arm is equipped with a spiral spray head, and the spray head is connected to a steam delivery pump.

[0010] Furthermore, the furnace tubes in the primary drying unit, the secondary drying and primary pyrolysis synchronous unit, the secondary pyrolysis and primary evaporation synchronous unit, and the secondary high-efficiency evaporation unit are electrically heated.

[0011] Furthermore, in the primary drying unit and the secondary drying and primary pyrolysis synchronous unit, a material inlet is opened at the top of the front end of the furnace tube, a material outlet is opened at the bottom of the rear end, and a steam outlet is opened in the middle of the top. In the secondary pyrolysis and primary evaporation synchronous unit and the secondary high-efficiency evaporation unit, a material inlet is opened at the top of the front end of the furnace tube, a material outlet is opened at the bottom of the rear end, and a phosphorus steam outlet is opened in the middle of the top.

[0012] Furthermore, in the integrated drying-pyrolysis-evaporation system, the outer side of the front and rear end covers of each unit furnace tube is provided with sealing components that cooperate with the conveying shaft. The sealing components include seal I and seal II, which are respectively set on the outer side of the front end cover and the rear end cover of the furnace tube. The sealing components are made of high temperature resistant and corrosion resistant materials and are tightly fitted with the surface of the conveying shaft to form a double sealing structure.

[0013] Furthermore, in the integrated drying-pyrolysis-evaporation system, the supporting and fixing components for each unit furnace tube include bearing seat I, bearing seat II, bracket I, bracket II, front support frame, rear support frame, and support base I and support base II. Bearing seat I and bearing seat II respectively support the front and rear ends of the conveying shaft. Bracket I and bracket II are fixedly connected to the front and rear end covers of the furnace tube, respectively. The front support frame and rear support frame are symmetrically arranged below the furnace tube and fixed to the bottom of the frame through support base I and support base II.

[0014] The process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash evaporation and continuous evaporation utilizes the aforementioned equipment, including material pretreatment, primary drying, simultaneous secondary drying and primary pyrolysis, simultaneous secondary pyrolysis and primary evaporation, secondary high-efficiency evaporation, phosphorus vapor condensation, multi-stage spray recovery, and residue recovery steps, as detailed below:

[0015] S1. Material pretreatment:

[0016] The phosphorus mud slurry in the storage tank is pumped into the phosphorus mud homogenizing mixing tank under closed and inert gas protection conditions via a pneumatic pump. Ammonia water or sodium carbonate solution is added to the phosphorus mud homogenizing mixing tank through a dosing tank. The phosphorus mud slurry is crushed, dispersed and mixed by a combination of steam injection at a pressure of 0.5~1.0 MPa and 90~120℃ and mechanical crushing to form a uniform and continuously transportable homogenized phosphorus mud at a temperature of 60~90℃.

[0017] S2, Primary Drying:

[0018] The pretreated homogeneous phosphorus mud is continuously fed into the primary material drying unit. The homogeneous phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. It is dried at low temperature of 120~170℃ under closed conditions to remove free water. The generated water vapor is circulated to the phosphorus mud homogenizing mixing tank for phosphorus mud crushing, dispersion and mixing.

[0019] S3. Simultaneous secondary drying and primary pyrolysis:

[0020] The primary dried phosphorus mud is fed into the material secondary drying and primary pyrolysis synchronous unit. The semi-dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The bound water is removed under closed conditions and at 180~220℃. The generated water vapor is transported to the phosphorus vapor condensation and collection device for phosphorus vapor fractionation.

[0021] S4. Simultaneous processing of secondary pyrolysis and primary evaporation:

[0022] The dried phosphorus mud obtained from S3 is fed into the material secondary pyrolysis and primary evaporation synchronous unit. The dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. Under closed conditions and at 220~350℃, it undergoes medium-temperature evaporation pretreatment, which causes the surface yellow phosphorus in the phosphorus mud to begin to vaporize and form phosphorus vapor. The generated phosphorus vapor enters the phosphorus vapor condensation and collection device.

[0023] S5, Two-stage high-efficiency evaporation:

[0024] The primary dephosphorized phosphorus mud obtained from S4 is fed into the secondary high-efficiency evaporation unit of the material. The primary dephosphorized phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. Under closed conditions and at 300~480℃, it undergoes a stepped high-temperature evaporation process to achieve efficient evaporation of yellow phosphorus to generate phosphorus vapor. The resulting phosphorus-free residue is sent to the residue collection bin.

[0025] S6. Phosphorus vapor condensation and multi-stage spray recovery:

[0026] The phosphorus vapors generated by S4 and S5 are sequentially fed into the phosphorus vapor condensation and collection device and the multi-stage spray tower, so that the phosphorus vapors are condensed and recovered in stages to form liquid yellow phosphorus, which is sent into the yellow phosphorus receiving tank and the excess condensate generated in the yellow phosphorus receiving tank is collected. The tail gas generated by the spray tower is purified by the tail gas purification system and then discharged in compliance with the standards.

[0027] S7. Residue Recycling:

[0028] The phosphorus-free residue is fed into the residue crushing and moisture-proof packaging unit under inert or oxygen-free conditions for crushing, moisture-proof packaging and recycling.

[0029] Furthermore, in step S1, the solid content of the phosphorus mud slurry is 50-80%; the concentration of the ammonia or sodium carbonate solution is 1-5 wt.%.

[0030] Further, in step S1, the mixing time is 3-15 minutes; in step S2, the low-temperature drying time is 3-5 minutes; in step S3, the running time is 5-15 minutes; in step S4, the running time is 5-15 minutes; and in step S5, the running time is 5-15 minutes.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] (1) During the homogenization and mixing process of phosphorus mud, superheated steam at a pressure of 0.5~1.0 MPa and a temperature of 90~120℃ is used to pre-treat the phosphorus mud by bubbling, so as to destroy the solvation film protective layer formed on the phosphorus surface and promote the mutual contact and aggregation between yellow phosphorus particles. Then, with the assistance of ammonia or sodium carbonate, the colloidal structure of the phosphorus mud is further destroyed, so that solid impurities are dispersed in the water layer, which helps the subsequent vaporization of elemental phosphorus.

[0033] (2) Each unit in the drying-pyrolysis-evaporation integrated system is equipped with a furnace tube. The low temperature drying section (100~150℃), medium temperature evaporation section (280~320℃), and high temperature anti-coking section (>350℃) are independently and precisely controlled by gradient electromagnetic heating, while ensuring efficient heat transfer and local overheat protection.

[0034] (3) The combination of multi-stage evaporation process and steam flash evaporation technology enables continuous homogeneous feeding of high-viscosity non-Newtonian fluid (phosphorus mud), while ensuring that the material forms a stable thin layer on the evaporation surface, thereby improving evaporation efficiency.

[0035] (4) High-temperature wear-resistant mechanical seals are used for key dynamic sealing parts between multi-stage evaporation processes, realizing a full-process inert atmosphere protection system from feeding, evaporation, condensation to discharge, eliminating air infiltration and reducing the risk of fire.

[0036] (5) The multi-stage flash evaporation process has achieved efficient recovery of yellow phosphorus in phosphorus mud. The equipment has high operational stability and significant anti-scaling effect. The recovery rate of elemental phosphorus can reach more than 95%, and the purity of the recovered yellow phosphorus is ≥99.95%. The residue can be directly used as raw material for phosphate fertilizer production or cement production, realizing the recycling of phosphorus resources and zero pollution discharge of waste. Attached Figure Description

[0037] The accompanying drawings are used to further illustrate the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation on the present invention.

[0038] Figure 1 This is a flowchart of the device and process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash continuous evaporation. The flowchart shows: 1. Pretreatment system; 2. Integrated drying-pyrolysis-evaporation system; 3. Product recovery and treatment system; 11. Phosphorus mud slurry storage tank; 12. Phosphorus mud homogenizing mixing tank; 21. Primary drying unit; 22. Synchronous unit for secondary drying and primary pyrolysis; 23. Synchronous unit for secondary pyrolysis and primary evaporation; 24. High-efficiency secondary evaporation unit; 31. Residue collection bin; 32. Residue crushing and moisture-proof sealing treatment unit; 33. Phosphorus vapor condensation and collection device; 34. Multi-stage spray tower; 35. Yellow phosphorus receiving tank; 36. Tail gas purification system.

[0039] Figure 2 This is a schematic diagram of the structure of a two-stage high-efficiency evaporation unit for materials; in the diagram: 241, furnace tube; 242, conveyor shaft; 243, material inlet; 244, phosphorus vapor outlet; 245, material outlet; 246, insulation layer; 247, tiered heating unit; 248, front cover; 249, rear cover; 2410, seal I; 2411, seal II; 2412, bearing seat I; 2413, bearing seat II; 2414, support I; 2415, support II; 2416, front support frame; 2417, support seat I; 2418, rear support frame; 2419, support seat II; 2420, reducer; 2421, motor; 2422, conveyor blades; 2423, frame; 2424, multi-stage arc-shaped coil structure.

[0040] The technical solution and embodiments of the present invention can be clearly understood from the above accompanying drawings. Those skilled in the art, based on these drawings and the description in the specification, can implement the technical solution of the present invention and understand its innovative points and beneficial effects. Detailed Implementation

[0041] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Example 1

[0043] like Figure 1As shown, the device for recovering yellow phosphorus from phosphorus mud based on multi-stage flash continuous evaporation consists of a pretreatment system 1, a drying-pyrolysis-evaporation integrated system 2, and a product recovery and treatment system 3. The pretreatment system 1 consists of a phosphorus mud slurry storage tank 11, a phosphorus mud homogenizing mixing tank 12, and a dosing tank 13. The drying-pyrolysis-evaporation integrated system 2 consists of a primary material drying unit 21, a secondary material drying and primary pyrolysis synchronous unit 22, a secondary material pyrolysis and primary evaporation synchronous unit 23, and a secondary high-efficiency material evaporation unit 24 connected in sequence. Each unit includes a furnace tube and a rotating part installed inside the furnace tube. The rotating conveyor shaft; the product recovery and processing system 3 consists of a residue collection bin 31, a residue crushing and moisture-proof sealing processing unit 32, a phosphorus vapor condensation and collection device 33, and a multi-stage spray tower 34; the phosphorus mud homogenizing mixing tank 12 is equipped with an inlet, a reagent dosing port, a discharge port, and a steam inlet; the phosphorus mud slurry storage tank 11 is connected to the inlet of the phosphorus mud homogenizing mixing tank 12 via a pneumatic pump; the reagent dosing port at the top of the phosphorus mud homogenizing mixing tank 12 is connected to a dosing tank 13; and the discharge port at the bottom is connected to the primary material drying unit 21 via a screw pump; the furnace tube in the primary material drying unit 21 is equipped with a material inlet, a material outlet, and a... A steam outlet is connected to the steam inlet at the bottom of the phosphorus mud homogenizing mixing tank 12 via a steam transfer pump. A material outlet is connected to the material secondary drying and primary pyrolysis synchronous unit 22 via a screw pump. The furnace tubes in the material secondary drying and primary pyrolysis synchronous unit 22 are equipped with a material inlet, a material outlet, and a steam outlet. The steam outlet is connected to the phosphorus vapor condensation and collection device 33 via a steam transfer pump. The material outlet is connected to the material secondary pyrolysis and primary evaporation synchronous unit 23 via a screw pump. The furnace tubes in the material secondary pyrolysis and primary evaporation synchronous unit 23 are equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to the phosphorus vapor condensation and collection device 33 via a steam transfer pump, and the material outlet is connected to the secondary high-efficiency evaporation unit 24 via a screw pump. The furnace tube in the secondary high-efficiency evaporation unit 24 is equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to the phosphorus vapor condensation and collection device 33 via a steam transfer pump, and the material outlet is sequentially connected to the residue collection bin 31 and the residue crushing, moisture-proof sealing treatment unit 32. The phosphorus vapor condensation and collection device 33 is equipped with a phosphorus vapor inlet and a material outlet, and the material outlet is sequentially connected to the multi-stage spray tower 34, the yellow phosphorus receiving tank 35, and the tail gas purification system 36.

[0044] Furthermore, the phosphorus mud slurry storage tank 11 is used to store phosphorus mud slurry.

[0045] Furthermore, the reagent in the dosing tank 13 is ammonia water or sodium carbonate solution.

[0046] Furthermore, the homogenizing tank 12 for phosphorus mud is equipped with a spiral stirring device, the spiral stirring arm is equipped with a spiral spray head, and the spray head is connected to a steam delivery pump.

[0047] Furthermore, the furnace tubes in the primary drying unit 21, the secondary drying and primary pyrolysis synchronous unit 22, the secondary pyrolysis and primary evaporation synchronous unit 23, and the secondary high-efficiency evaporation unit 24 are electrically heated.

[0048] Furthermore, in the primary drying unit 21 and the secondary drying and primary pyrolysis synchronous unit 22, a material inlet is provided at the top of the front end of the furnace tube, a material outlet is provided at the bottom of the rear end, and a steam outlet is provided in the middle of the top.

[0049] Furthermore, in the material secondary pyrolysis and primary evaporation synchronous unit 23 and the material secondary high-efficiency evaporation unit 24, a material inlet is opened at the top of the front end of the furnace tube, a material outlet is opened at the bottom of the rear end, and a phosphorus vapor outlet is opened in the middle of the top.

[0050] Furthermore, the multi-stage spray tower 34 includes a medium-temperature water tower, a quench water tower, and a process water recovery device. The recovered yellow phosphorus liquid enters the yellow phosphorus receiving tank 35. The tail gas generated by the spray tower 34 enters the tail gas purification system 36 and is discharged after treatment to meet the standards. The excess condensate generated by the yellow phosphorus receiving tank 35 is collected as tailwater.

[0051] Furthermore, in the integrated drying-pyrolysis-evaporation system 2, each unit includes a furnace tube and a rotatable conveyor shaft installed inside the furnace tube. Sealing components that cooperate with the conveyor shaft are installed on the outer sides of the front and rear end covers of the furnace tube. The sealing components include Seal I and Seal II, respectively located on the outer sides of the front and rear end covers of the furnace tube, forming a double-sealing structure that tightly adheres to the surface of the conveyor shaft. This structure, in conjunction with the nitrogen purging device of the core processing unit, effectively maintains an inert atmosphere inside the furnace tube, preventing air from entering the furnace tube and contacting phosphorus vapor, thus preventing safety accidents caused by phosphorus combustion. Simultaneously, it avoids the leakage of harmful gases that could cause environmental pollution, improving the safety and environmental friendliness of the equipment operation. The supporting and fixing components for each unit furnace tube include bearing housing I, bearing housing II, bracket I, bracket II, front support frame, rear support frame, and support seat I and support seat II. Bearing housing I and bearing housing II support the front and rear ends of the conveyor shaft, respectively, ensuring that the conveyor shaft rotates at high speed without deviation or vibration. Bracket I and bracket II are fixedly connected to the front and rear end covers of the furnace tube, respectively, to achieve integrated fixing of the end cover and the bearing housing. The front support frame and the rear support frame are symmetrically arranged below the furnace tube and fixed to the bottom of the frame by support seat I and support seat II, forming a multi-point balanced support structure to improve the overall operational stability of the equipment.

[0052] Specifically, taking the secondary high-efficiency evaporation unit 24 as an example, such as Figure 2As shown, the secondary high-efficiency evaporation unit 24 includes a furnace tube 241 and a rotatable conveyor shaft 242 disposed inside the furnace tube 241; the front end of the conveyor shaft 242 extends from the inside of the furnace tube front end cover 248; a seal I 2410 is provided on the outside of the furnace tube front end cover 248 to cooperate with the conveyor shaft 242; the rear end of the conveyor shaft 242 extends from the inside of the furnace tube rear end cover 249; a seal II 2411 is provided on the outside of the furnace tube rear end cover 249 to cooperate with the conveyor shaft 242; the front end of the conveyor shaft 242 is mounted on a bearing seat I 2412 located in front of the seal I 2410, and the rear end of the conveyor shaft 242 is mounted on a bearing seat II 2413 located behind the seal II 2411; the bearing seat I 2412 is mounted on a bracket I 2414, and the rear end of the bracket I 2414 is connected to the furnace tube front end cover 248; the bearing seat II 2413 is mounted on a bracket II 2415, and the bracket II 2415 is connected to the furnace tube front end cover 248. The front end of 2415 is connected to the rear end cover 249 of the furnace tube; a front support frame 2416 and a rear support frame 2418 are provided below the furnace tube 241. The front support frame 2416 is fixed on the support seat I 2417, and the rear support frame 2418 is fixed on the support seat II 2419; a reducer 2420 is installed at the front end of the bracket I 2414 and is connected to the front end of the conveyor shaft 242. The reducer 2420 is connected to the motor 2421; a conveyor blade 2422 is provided on the conveyor shaft 242; the furnace tube 241 is horizontally fixed inside the frame 2423; the furnace tube 241 is wrapped with an insulation layer 246, and a stepped heating unit 247 is provided outside the insulation layer 246; the stepped heating unit 247 is a cable structure wrapped around the insulation layer 246.

[0053] Specifically, the furnace tube 241 is made of 304 stainless steel; the insulation layer 246 is made of high-density aluminum silicate cotton; the stepped heating units 247 are equidistantly arranged along the outer axis of the insulation layer 246; the cable structure is a multi-stage arc-shaped coil structure 2424, which realizes precise stepped temperature control of the furnace tube.

[0054] Specifically, a front cover 248 made of carbon steel is fixed to the front end of the furnace tube 241 by bolts, and a rear cover 249 is installed at the rear end. A material inlet 243 with a diameter of 100-120 mm is opened at the top of the front cover 248, which is connected to the material outlet of the material secondary pyrolysis and primary evaporation synchronous unit 23. A material outlet 245 with a diameter of 80-100 mm is opened at the bottom of the rear cover 249, which is connected to the residue collection bin 31. A phosphorus vapor outlet 244 with a diameter of 150-180 mm is opened in the middle section of the top of the furnace tube 241, which is connected to the phosphorus vapor inlet of the phosphorus vapor condensation and collection device 33.

[0055] Specifically, the conveyor shaft 242 is made of 45 steel with heat treatment. Its length is adapted to the furnace tube 241 and it is coaxially set inside the furnace tube 241 to push the dried phosphate mud to evaporate inside the tube. The front end of the conveyor shaft 242 extends from the inside of the center hole of the front end cover 248, and the rear end extends from the inside of the center hole of the rear end cover 249. The shaft body is welded with spiral conveyor blades 2422. The spiral conveyor blades 2422 are made of the same material as the conveyor shaft 242. The gap between the edge and the inner wall of the furnace tube 241 is controlled at 5-8 mm, which avoids scraping the furnace tube and prevents the phosphate mud from adhering and scaling through rotation and scraping.

[0056] Specifically, the front end of the conveyor shaft 242 is assembled into bearing housing I 2412 via a deep groove ball bearing, and the rear end is assembled into bearing housing II 2413 via a bearing of the same type. Bearing housing I 2412 is bolted to bracket I 2414, and the rear end of bracket I 2414 is sealed to the front end cover 248 of the furnace tube via a flange. Bearing housing II 2413 is correspondingly installed on bracket II 2415, and the front end of bracket II 2415 is connected to the flange of the rear end cover 249 of the furnace tube, ensuring that the coaxiality error of the conveyor shaft 242 is ≤0.1 mm and that there is no radial offset during rotation. Both bracket I 2414 and bracket II 2415 are welded carbon steel structures. The front end of bracket I 2414 is fixed with a hardened gear reducer 2420 via a motor mount. The input end of reducer 2420 is connected to a three-phase asynchronous motor 2421 via a coupling. Motor 2421 can be driven at an adjustable speed of 10-30 r / min via a frequency converter. It can adjust the conveying rate according to the viscosity of phosphorus mud to ensure the residence time of the material in the furnace tube 241 and precisely match the heating requirements of the multi-stage evaporation device.

[0057] Specifically, both Seal I 2410 and Seal II 2411 are made of high-temperature and corrosion-resistant materials and are respectively embedded in the U-shaped sealing grooves on the outside of the front end cover 248 and the rear end cover 249 of the furnace tube, forming a double sealing structure by tightly fitting with the outer circle of the conveyor shaft 242; the sealing grooves are filled with high-temperature sealing grease to further prevent air from entering the interior of the furnace tube 241, which can control the phosphorus vapor leakage to ≤5 mg / m³. 3 This not only prevents phosphorus vapor from coming into contact with air and causing safety risks, but also avoids harmful gases polluting the environment, thus improving the safety and environmental friendliness of equipment operation.

[0058] Specifically, two sets of front support frames 2416 and rear support frames 2418 are symmetrically arranged below the furnace tube 241. Both are carbon steel welded triangular frames. The front support frame 2416 is fixed to support seat I 2417 by expansion bolts, and the rear support frame 2418 is fixed to support seat II 2419. Support seat I 2417 and support seat II 2419 are both fixed to the bottom of frame 2423 by pre-embedded bolts, forming a four-point balanced support. Support seat I 2417 and support seat II 2419 are both made of cast iron. Frame 2423 is made of carbon steel welded and equipped with guardrails. The vibration amplitude during equipment operation is ≤0.2 mm, ensuring continuous and stable operation.

[0059] like Figure 1 As shown, the process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash evaporation of the present invention includes the following steps:

[0060] S1. Material pretreatment:

[0061] Phosphate mud slurry with a solid content of 50-80% is pumped into a homogenizing mixing tank under sealed and inert gas protection conditions via a pneumatic pump. Ammonia water or sodium carbonate solution of 1-5 wt.% is added to the homogenizing mixing tank via a dosing tank. The slurry is then crushed, dispersed and mixed for 3-15 minutes by a combination of steam injection at a pressure of 0.5-1.0 MPa and a temperature of 90-120℃ and mechanical crushing, forming a uniform, continuously transportable homogenized phosphate mud at a temperature of 60-90℃.

[0062] S2, Primary Drying:

[0063] The pretreated homogeneous phosphorus mud is continuously fed into the primary material drying unit. The homogeneous phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The conveying shaft inside the furnace tube drives the conveying blades to push the phosphorus mud to be dried at a low temperature of 120~170℃ for 3~5 minutes under closed conditions to remove free water. The generated water vapor is circulated to the phosphorus mud homogenizing mixing tank for phosphorus mud crushing, dispersion and mixing treatment.

[0064] S3. Simultaneous secondary drying and primary pyrolysis:

[0065] The primary dried phosphorus mud is transported to the material secondary drying and primary pyrolysis synchronous unit. The semi-dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The conveying shaft inside the furnace tube drives the conveying blades to push the phosphorus mud to complete the removal of bound water under closed conditions and 180~220℃. The running time is 5~15 minutes. The generated water vapor is transported to the phosphorus vapor condensation and collection device for phosphorus vapor fractionation.

[0066] S4. Simultaneous processing of secondary pyrolysis and primary evaporation:

[0067] The above-mentioned dried phosphorus mud material is fed into the material secondary pyrolysis and primary evaporation synchronous unit. The dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The conveying shaft inside the furnace tube drives the conveying blades to push the phosphorus mud for medium-temperature evaporation pretreatment under closed conditions and at 220~350℃ for 5~15 minutes, so that the surface yellow phosphorus in the phosphorus mud begins to vaporize and form phosphorus vapor. The generated phosphorus vapor enters the phosphorus vapor condensation and collection device.

[0068] S5, Two-stage high-efficiency evaporation:

[0069] The dried phosphorus mud after S4 treatment is fed into the secondary high-efficiency evaporation unit. The dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The conveyor shaft inside the furnace tube drives the conveyor blades to push the phosphorus mud for staged high-temperature evaporation treatment under closed conditions and at 300~480℃. The operation time is 5~15 minutes, realizing the high-efficiency evaporation of yellow phosphorus. The generated phosphorus vapor enters the phosphorus vapor condensation and collection device, and the phosphorus-free residue is sent to the residue collection bin.

[0070] S6. Phosphorus vapor condensation and multi-stage spray recovery:

[0071] The phosphorus vapors generated by S4 and S5 are sequentially fed into a phosphorus vapor condensation and collection device and a multi-stage spray tower, so that the phosphorus vapors are condensed and recovered step by step to form liquid yellow phosphorus, which is then sent into a yellow phosphorus receiving tank. Excess condensate generated in the yellow phosphorus receiving tank is collected, and the exhaust gas is purified by a purification system to meet emission standards.

[0072] S7. Residue Recycling:

[0073] The phosphorus-free residue is fed into a residue crushing and moisture-proof packaging unit under inert or oxygen-free conditions for crushing, moisture-proof packaging and recycling. The collected residue can be used for phosphate fertilizer production, cement raw materials, etc.

[0074] The device of this invention has a phosphorus mud processing capacity of 0.5 to 1.0 tons per hour, a single phosphorus recovery rate of over 95%, and a yellow phosphorus purity of ≥99.95%. It can operate continuously and stably for over 720 hours.

[0075] The working principle of this invention is as follows: First, during the homogenization and mixing process of phosphorus mud, superheated steam is used to pre-treat the phosphorus mud by bubbling, thereby breaking down the solvation film protective layer formed on the phosphorus surface and promoting the contact and aggregation between yellow phosphorus particles. Next, with the assistance of ammonia or sodium carbonate, the colloidal structure of the phosphorus mud is further disrupted, allowing solid impurities to disperse in the water layer, which facilitates the subsequent vaporization of elemental phosphorus. Then, a multi-stage evaporation process is combined with steam flash evaporation technology, employing gradient electromagnetic heating to achieve independent and precise control of the low-temperature drying section (100~150℃), the medium-temperature evaporation section (280~320℃), and the high-temperature anti-coking section (>350℃). This ensures efficient heat transfer and protection against localized overheating, enabling continuous homogenized feeding of high-viscosity non-Newtonian fluid (phosphorus mud) while ensuring the formation of a stable thin layer on the evaporation surface, thus improving evaporation efficiency. By precisely controlling the temperature of the integrated drying-pyrolysis-evaporation system, and utilizing the thin-layer evaporation drying technology principle, effective moisture removal is achieved to obtain dry phosphorus mud. The principle of flash evaporation and explosion is used to achieve efficient evaporation of phosphorus from the phosphorus mud. Rapid cooling, fractionation, and dehydration methods are employed to prevent coking and equipment blockage of the yellow phosphorus washing solution. Finally, the entire unit uses mechanical seals and automatic discharge to prevent air leakage and potential spontaneous combustion of yellow phosphorus.

[0076] To verify the technical effect of the present invention, the following comparative examples were set up for performance comparison:

[0077] Comparative Example 1

[0078] The apparatus of Comparative Example 1 is largely the same as that of Example 1, except that the pretreatment system is only equipped with a phosphorus mud storage tank and does not have a phosphorus mud homogenizing mixing tank and a dosing tank. The phosphorus mud slurry in the phosphorus mud storage tank is directly and continuously fed into the primary material drying unit by a pneumatic pump under closed and inert gas protection conditions. The results of its phosphorus recovery rate, yellow phosphorus purity and P2O5 content are shown in Table 1.

[0079] Comparative Example 2

[0080] The apparatus of Comparative Example 1 is largely the same as that of Example 1, except that the integrated drying-pyrolysis-evaporation system is only equipped with a primary drying unit, a secondary drying and primary pyrolysis synchronous unit, and a secondary pyrolysis and primary evaporation synchronous unit, and does not have a secondary high-efficiency evaporation unit. The results of its phosphorus recovery rate, yellow phosphorus purity and P2O5 content are shown in Table 1.

[0081] Comparative Example 3

[0082] The apparatus of Comparative Example 1 is largely the same as that of Example 1, except that the product recovery and treatment system does not have a phosphorus vapor condensation and collection device. The generated phosphorus vapor directly enters the multi-stage spray tower. The results of its phosphorus recovery rate, yellow phosphorus purity and P2O5 content are shown in Table 1.

[0083] Table 1. Results of phosphorus recovery rate, yellow phosphorus purity, and P2O5 content in the examples and comparative examples.

[0084] Comparison items Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Phosphorus recovery rate ≥99% ≤95% ≤85% ≥99% Yellow phosphorus purity ≥99.95% ≤95% ≤90% ≥99.95% <![CDATA[P2O5 content]]> 25±5% 15±5% 25±5% 25±5% Phosphate mud processing capacity >0.5 tons / hour <0.5 tons / hour <0.5 tons / hour <0.5 tons / hour Continuous running time >720 hours <360 hours <400 hours <200 hours

[0085] The performance comparison between the embodiments and the comparative examples in Table 1 shows that the present invention, by combining homogeneous mixing pretreatment, drying-pyrolysis-evaporation multi-stage flash evaporation integrated treatment with phosphorus vapor condensation treatment, has developed a phosphorus evaporation process and device that integrates gradient temperature-controlled thin-layer evaporation, flash explosion, and automatic discharge with mechanical seal. This not only improves the feeding uniformity of phosphorus mud and the phosphorus evaporation efficiency, but also meets the requirements of precise temperature control, uniform feeding and stable mass transfer, full-process airtight leakage prevention, coking and blockage prevention, and efficient condensation in the phosphorus mud recovery process. It solves the technical difficulties of traditional phosphorus mud recovery equipment, such as low recovery rate, easy scaling and blockage of furnace tubes leading to frequent downtime maintenance, lack of inertial protection and poor equipment sealing causing phosphorus combustion risk, and condensation blockage. In terms of phosphorus recovery rate, yellow phosphorus purity, anti-scaling effect, operational safety, and resource / environmental benefits, it is significantly better than the comparative example that only retains part of the system.

[0086] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0087] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for recovering yellow phosphorus from phosphorus mud based on multi-stage flash evaporation, characterized in that, It consists of a pretreatment system, an integrated drying-pyrolysis-evaporation system, and a product recovery and processing system; The pretreatment system consists of a phosphorus mud slurry storage tank, a phosphorus mud homogenizing mixing tank, and a dosing tank. The integrated drying-pyrolysis-evaporation system consists of a primary material drying unit, a secondary material drying and primary pyrolysis synchronous unit, a secondary material pyrolysis and primary evaporation synchronous unit, and a secondary high-efficiency material evaporation unit connected in sequence. Each unit includes furnace tubes and a rotating conveyor shaft installed inside the furnace tubes. The product recovery and treatment system consists of a residue collection bin, a residue crushing and moisture-proof sealing treatment unit, a phosphorus vapor condensation and collection device, and a multi-stage spray tower. The phosphorus mud homogenizing mixing tank is equipped with an inlet, a reagent dosing port, a discharge port, and a steam inlet. The phosphorus mud slurry storage tank is connected to the inlet of the phosphorus mud homogenizing mixing tank via a pneumatic pump. The reagent dosing port at the top of the phosphorus mud homogenizing mixing tank is connected to the dosing tank, and the discharge port at the bottom is connected to the primary material drying unit via a screw pump. The furnace tubes in the primary material drying unit are equipped with a material inlet, a material outlet, and a steam outlet. The steam outlet is connected to the steam inlet at the bottom of the phosphorus mud homogenizing mixing tank via a steam transfer pump. The material outlet is connected to the material secondary drying and primary pyrolysis synchronous unit via a screw pump. The furnace tubes in the material secondary drying and primary pyrolysis synchronous unit are equipped with a material inlet, a material outlet, and a steam outlet. The steam outlet is connected to a phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is connected to the material secondary pyrolysis and primary evaporation synchronous unit via a screw pump. The furnace tubes in the material secondary pyrolysis and primary evaporation synchronous unit are equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to a phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is connected to the material secondary high-efficiency evaporation unit via a screw pump. The furnace tubes in the material secondary high-efficiency evaporation unit are equipped with a material inlet, a material outlet, and a phosphorus vapor outlet. The phosphorus vapor outlet is connected to a phosphorus vapor condensation and collection device via a steam transfer pump. The material outlet is sequentially connected to a residue collection bin and a residue crushing and moisture-proof sealing treatment unit. The phosphorus vapor condensation and collection device is equipped with a phosphorus vapor inlet and a material outlet. The material outlet is sequentially connected to a multi-stage spray tower, a yellow phosphorus receiving tank, and a tail gas purification system.

2. The apparatus according to claim 1, characterized in that, The reagent in the dosing tank is ammonia water or sodium carbonate solution; the homogenizing mixing tank for phosphorus mud is equipped with a spiral stirring device, the spiral stirring arm is equipped with a spiral spray head, and the spray head is connected to a steam transfer pump; the furnace tubes in the primary drying unit, the secondary drying and primary pyrolysis synchronous unit, the secondary pyrolysis and primary evaporation synchronous unit, and the secondary high-efficiency evaporation unit are electrically heated; in the primary drying unit and the secondary drying and primary pyrolysis synchronous unit, the furnace tube has a material inlet at the top front end, a material outlet at the bottom rear end, and a steam outlet at the middle top section; in the secondary pyrolysis and primary evaporation synchronous unit and the secondary high-efficiency evaporation unit, the furnace tube has a material inlet at the top front end, a material outlet at the bottom rear end, and a phosphorus vapor outlet at the middle top section.

3. The apparatus according to claim 1, characterized in that, In the integrated drying-pyrolysis-evaporation system, the outer sides of the front and rear end covers of each unit furnace tube are equipped with sealing components that cooperate with the conveyor shaft. The sealing components include seal I and seal II, which are respectively set on the outer sides of the front and rear end covers of the furnace tube, forming a double sealing structure by tightly fitting with the surface of the conveyor shaft. The support and fixing components of each unit furnace tube include bearing seat I, bearing seat II, bracket I, bracket II, front support frame, rear support frame, and support base I and support base II. Bearing seat I and bearing seat II support the front and rear ends of the conveyor shaft, respectively. Bracket I and bracket II are fixedly connected to the front and rear end covers of the furnace tube, respectively. The front support frame and rear support frame are symmetrically arranged below the furnace tube and fixed to the bottom of the frame by support base I and support base II.

4. The apparatus according to claim 3, characterized in that, Seal I and Seal II are respectively embedded in the U-shaped sealing grooves on the outside of the front and rear end covers of the furnace tube, forming a double sealing structure by tightly fitting with the outer circle of the conveyor shaft. The length of the conveyor shaft is adapted to the furnace tube and is coaxially installed inside the furnace tube. The front end extends from the inside of the center hole of the front end cover of the furnace tube, and the rear end extends from the inside of the center hole of the rear end cover of the furnace tube. The front end of the conveyor shaft is mounted on bearing seat I located in front of seal I, and the rear end of the conveyor shaft is mounted on bearing seat II located behind seal II. Bearing seat I is mounted on bracket I, and the rear end of bracket I is connected to the front end cover of the furnace tube. Bearing seat II is mounted on bracket II, and the front end of bracket II is connected to the rear end cover of the furnace tube; a front support frame and a rear support frame are provided below the furnace tube, the front support frame is fixed on support seat I, and the rear support frame is fixed on support seat II; a reducer connected to the front end of the conveyor shaft is installed at the front end of bracket I, and the reducer is connected to the motor; conveyor blades are provided on the conveyor shaft; the furnace tube is horizontally fixed inside the frame; the furnace tube is wrapped with an insulation layer, and a stepped heating unit is provided outside the insulation layer; the stepped heating unit is a cable structure wound around the outside of the insulation layer.

5. The apparatus according to claim 4, characterized in that, The furnace tube is made of 304 stainless steel, while the front and rear covers are made of carbon steel. The conveyor shaft is made of 45# steel with heat treatment, and the shaft body is welded with spiral conveyor blades of the same material. The gap between the edge and the inner wall of the furnace tube is controlled at 5-8 mm. The insulation layer is made of high-density aluminum silicate cotton. The stepped heating units are equidistantly arranged along the outer axial direction of the insulation layer. The cable structure is a multi-stage arc-shaped coil structure. Support I and support II are both carbon steel welded structures. The front support frame and the rear support frame are both carbon steel welded triangular frames. Support base I and support base II are both made of cast iron. The frame is made of carbon steel welded and equipped with protective railings.

6. The apparatus according to claim 4, characterized in that, A front cover is fixed to the front end of the furnace tube with bolts, and a rear cover is installed at the rear end. A material inlet with a diameter of 100-120 mm is opened at the top of the front cover, which is connected to the material outlet of the material secondary pyrolysis and primary evaporation synchronous unit. A material outlet with a diameter of 80-100 mm is opened at the bottom of the rear cover, which is connected to the residue collection bin. A phosphorus vapor outlet with a diameter of 150-180 mm is opened in the middle section of the top of the furnace tube, which is connected to the phosphorus vapor inlet of the phosphorus vapor condensation and collection device.

7. The apparatus according to claim 4, characterized in that, The front end of the conveyor shaft is assembled in bearing housing I via a deep groove ball bearing, and the rear end is assembled in bearing housing II via a bearing of the same type. Bearing housing I is bolted to bracket I, and the rear end of bracket I is sealed to the front end cover of the furnace tube via a flange. Bearing housing II is installed on bracket II, and the front end of bracket II is connected to the flange of the rear end cover of the furnace tube. A hard-tooth surface reducer is fixed to the front end of bracket I via a motor mount, and the input end of the reducer is connected to a three-phase asynchronous motor via a coupling.

8. The apparatus according to claim 4, characterized in that, Two sets of front and rear support frames are symmetrically installed below the furnace tube. The front support frame is fixed to support seat I by expansion bolts, and the rear support frame is fixed to support seat II. Both support seat I and support seat II are fixed to the bottom of the frame by pre-embedded bolts.

9. A process for recovering yellow phosphorus from phosphorus mud based on multi-stage flash evaporation, characterized in that, The apparatus according to any one of claims 1 to 8 is specifically used as follows: S1. Material pretreatment: The phosphorus mud slurry in the storage tank is pumped into the phosphorus mud homogenizing mixing tank under closed and inert gas protection conditions via a pneumatic pump. Ammonia water or sodium carbonate solution is added to the phosphorus mud homogenizing mixing tank through a dosing tank. The phosphorus mud slurry is crushed, dispersed and mixed by a combination of water vapor injection at a pressure of 0.5~1.0MPa and 90~120℃ and mechanical crushing to form a uniform and continuously transportable homogenized phosphorus mud at a temperature of 60~90℃. S2, Primary Drying: The pretreated homogeneous phosphorus mud is continuously fed into the primary material drying unit. The homogeneous phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. It is dried at low temperature of 120~170℃ under closed conditions to remove free water. The generated water vapor is circulated to the phosphorus mud homogenizing mixing tank for phosphorus mud crushing, dispersion and mixing. S3. Simultaneous secondary drying and primary pyrolysis: The primary dried phosphorus mud is fed into the material secondary drying and primary pyrolysis synchronous unit. The semi-dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. The bound water is removed under closed conditions and at 180~220℃. The generated water vapor is transported to the phosphorus vapor condensation and collection device for phosphorus vapor fractionation. S4. Simultaneous processing of secondary pyrolysis and primary evaporation: The dried phosphorus mud obtained from S3 is fed into the material secondary pyrolysis and primary evaporation synchronous unit. The dried phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. Under closed conditions and at 220~350℃, it undergoes medium-temperature evaporation pretreatment, which causes the surface yellow phosphorus in the phosphorus mud to begin to vaporize and form phosphorus vapor. The generated phosphorus vapor enters the phosphorus vapor condensation and collection device. S5, Two-stage high-efficiency evaporation: The primary dephosphorized phosphorus mud obtained from S4 is fed into the secondary high-efficiency evaporation unit of the material. The primary dephosphorized phosphorus mud is fed into the furnace tube from the material inlet by a screw pump. Under closed conditions and at 300~480℃, it undergoes a stepped high-temperature evaporation process to achieve efficient evaporation of yellow phosphorus to generate phosphorus vapor. The resulting phosphorus-free residue is sent to the residue collection bin. S6. Phosphorus vapor condensation and multi-stage spray recovery: The phosphorus vapors generated by S4 and S5 are sequentially fed into the phosphorus vapor condensation and collection device and the multi-stage spray tower, so that the phosphorus vapors are condensed and recovered in stages to form liquid yellow phosphorus, which is sent into the yellow phosphorus receiving tank and the excess condensate generated in the yellow phosphorus receiving tank is collected. The tail gas generated by the spray tower is purified by the tail gas purification system and then discharged in compliance with the standards. S7. Residue Recycling: The phosphorus-free residue is fed into the residue crushing and moisture-proof packaging unit under inert or oxygen-free conditions for crushing, moisture-proof packaging and recycling.

10. The process according to claim 9, characterized in that, In step S1, the solid content of the phosphorus mud slurry is 50-80%, the concentration of ammonia or sodium carbonate solution is 1-5 wt.%, and the mixing time is 3-15 minutes; in step S2, the low-temperature drying time is 3-5 minutes; in step S3, the running time is 5-15 minutes; in step S4, the running time is 5-15 minutes; in step S5, the running time is 5-15 minutes.

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