CN-121974538-A - Device and process for recovering yellow phosphorus in phosphorus mud based on multistage flash evaporation continuous evaporation

CN121974538ACN 121974538 ACN121974538 ACN 121974538ACN-121974538-A

Abstract

The invention discloses a device and a process for continuously evaporating and recovering yellow phosphorus in phosphorus mud based on multistage flash evaporation. The device comprises a pretreatment system, a drying-pyrolysis-evaporation integrated system and a product recovery and treatment system, wherein phosphorus mud slurry is pretreated in the pretreatment system in a steam crushing and mixing mode, then enters the drying-pyrolysis-evaporation integrated system, and is subjected to precise temperature control through gradient electromagnetic heating, so that the recycling of water vapor and the efficient evaporation of phosphorus are realized, and finally enters the product recovery and treatment system, so that the recovery of yellow phosphorus and phosphorus-free residues is realized. The device and the process can realize the whole-course uniform feeding of the phosphorus slurry, thoroughly evaporate phosphorus, realize the recovery rate of yellow phosphorus of more than 95%, have good equipment tightness, effectively avoid the risk of spontaneous combustion and ignition of yellow phosphorus, realize the processing capacity of the phosphorus slurry of 0.5-1.0 ton per hour, continuously and stably operate for more than 720 hours, realize the uniform granularity of the recovered residues, be used for the production of phosphate fertilizers, cement and the like, and realize the recycling of resources.

Inventors

ZHA XIAOFENG
WANG WEIWEI
Zha Qinchen
WANG TINGHUI
Qiang Xuebin
YANG WENLONG
NIE GUANGZE
SHEN JUNLIANG

Assignees

江苏金陵环保科技有限公司
南京工业大学
安徽远海科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260206

Claims (10)

1. The device for continuously evaporating and recycling yellow phosphorus in phosphorus mud based on multistage flash evaporation is characterized by comprising a pretreatment system, a drying-pyrolysis-evaporation integrated system and a product recycling and processing system; the pretreatment system consists of a phosphorus mud material storage tank, a phosphorus mud homogenizing and mixing tank and a dosing tank, wherein the drying-pyrolysis-evaporation integrated system consists of a material primary drying unit, a material secondary drying and primary pyrolysis synchronous unit, a material secondary pyrolysis and primary evaporation synchronous unit and a material secondary efficient evaporation unit which are sequentially connected, each unit comprises a furnace tube and a conveying shaft which is arranged in the furnace tube and can rotate, the product recovery and treatment system consists of a residue collection bin, a residue crushing and moisture absorption prevention packaging treatment unit, a phosphorus steam condensation and collection device and a multi-stage spray tower, the phosphorus mud homogenizing and mixing tank is provided with a feed inlet, a medicament feeding port, a discharge port and a water steam inlet, the phosphorus mud material storage tank is connected with the feed inlet of the phosphorus mud homogenizing and mixing tank through a pneumatic pump, the medicament feeding port at the top end of the phosphorus mud homogenizing and mixing tank is connected with the dosing tank, the discharge port at the bottom end of the phosphorus mud homogenizing and mixing tank is connected with the material primary drying unit through a screw pump, the material outlet and the water steam outlet are arranged in the material primary drying unit, the water steam outlet is connected with the water steam inlet at the bottom of the phosphorus mud homogenizing and mixing tank through a steam conveying pump, the material outlet is connected with the water steam inlet at the bottom of the phosphorus mud homogenizing and mixing tank through the primary drying unit through the screw pump, the device comprises a material secondary pyrolysis and primary evaporation synchronous unit, a material outlet, a material secondary evaporation and primary evaporation synchronous unit, a material secondary pyrolysis and primary evaporation synchronous unit, a material outlet and a phosphorus steam outlet, wherein a furnace tube in the material secondary pyrolysis and primary evaporation synchronous unit is provided with a material inlet, a material outlet and a phosphorus steam outlet, the phosphorus steam outlet is connected with a material secondary efficient evaporation unit through a steam delivery pump, the furnace tube in the material secondary efficient evaporation unit is provided with a material inlet, a material outlet and a phosphorus steam outlet, the phosphorus steam outlet is connected with a phosphorus steam condensation collection device through a steam delivery pump, the material outlet is sequentially connected with a residue collection bin and a residue crushing and moisture absorption prevention packaging treatment unit, the phosphorus steam condensation collection device is provided with a phosphorus steam inlet and a material outlet, and the material outlet is sequentially connected with a multi-stage spray tower, a yellow phosphorus receiving phosphorus tank and a tail gas purification system.
2. The device of claim 1, wherein the agent in the agent adding tank is ammonia water or sodium carbonate solution, a spiral stirring device is arranged in the phosphorus mud homogenizing and mixing tank, a spiral stirring arm is provided with a spiral spraying head, the spraying head is connected with a steam conveying pump, 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 evaporation unit are electrically heated, a material inlet is formed in the top of the furnace tube in the primary drying unit and the secondary drying and primary pyrolysis synchronous unit, a material outlet is formed in the bottom of the rear end of the furnace tube, a water vapor outlet is formed in the middle section of the top of the furnace tube, a material inlet is formed in the top of the front end of the furnace tube, a material outlet is formed in the bottom of the rear end of the furnace tube, and a phosphorus vapor outlet is formed in the middle section of the top of the furnace tube.
3. The device of claim 1, wherein in the drying-pyrolysis-evaporation integrated system, sealing assemblies matched with conveying shafts are arranged on the outer sides of front end covers and rear end covers of all unit furnace tubes, the sealing assemblies comprise a seal I and a seal II which are respectively and correspondingly arranged on the outer sides of the front end covers and the rear end covers of the furnace tubes and are tightly attached to the surfaces of the conveying shafts to form a double sealing structure, supporting and fixing assemblies of all unit furnace tubes comprise a bearing seat I, a bearing seat II, a support I, a support II, a front support frame, a rear support frame, a support seat I and a support seat II, wherein the bearing seat I and the bearing seat II are respectively and correspondingly used for supporting the front end and the rear end of the conveying shafts, the support I and the support II are respectively and fixedly connected with the front end covers and the rear end covers of the furnace tubes, and the front support frame and the rear support frame are symmetrically arranged below the furnace tubes and are fixed to the bottom of a frame through the support seat I and the support seat II.
4. The device according to claim 3, wherein the seal I and the seal II are respectively embedded in a U-shaped sealing groove at the outer side of the front end cover and the rear end cover of the furnace tube and are tightly attached to the outer circle of the conveying shaft to form a double sealing structure, the conveying shaft is matched with the furnace tube in length and coaxially arranged in the furnace tube, the front end of the conveying shaft extends out of the inner side of the central hole of the front end cover of the furnace tube, the rear end of the conveying shaft extends out of the central hole of the rear end cover of the furnace tube, the front end of the conveying shaft is arranged on a bearing seat I at the front side of the seal I, the rear end of the conveying shaft is arranged on a bearing seat II at the rear side of the seal II, the bearing seat I is arranged on a support I, the rear end of the support I is connected with the front end cover of the furnace tube, the bearing seat II is arranged on the support II, the front end of the support I is provided with a speed reducer in transmission connection with the front end of the conveying shaft, the conveying shaft is provided with a conveying blade, the furnace tube is horizontally fixed in the frame, the furnace tube is externally wrapped by a step heat insulation layer, the outer part of the furnace tube is wrapped by a heat insulation cable unit and is a heat insulation layer of an external heat insulation cable winding structure.
5. The device of claim 4, wherein the furnace tube is made of 304 stainless steel, the front end cover and the rear end cover are made of carbon steel, the conveying shaft is made of 45 # steel by thermal refining, the shaft body is welded with spiral conveying blades made of the same material, the gap between the edge and the inner wall of the furnace tube is controlled to be 5-8 mm, the heat insulation layer is made of high-density aluminum silicate cotton, the step heating units are axially and equidistantly distributed along the outer part of the heat insulation layer, the cable structure is of a multi-stage arc wire coil structure, the support I and the support II are both of carbon steel welding structures, the front support frame and the rear support frame are both of carbon steel welding triangular frames, the support seat I and the support seat II are both made of cast iron, and the frame is welded by carbon steel and is provided with a protective rail.
6. The device of claim 4, wherein the front end of the furnace tube is fixedly provided with a front end cover through a bolt, the rear end is correspondingly provided with a rear end cover, the top of the front end cover is provided with a material inlet with the diameter of 100-120 mm and is connected with a material outlet of a material secondary pyrolysis and primary evaporation synchronous unit, the bottom of the rear end cover is provided with a material outlet with the diameter of 80-100 mm and is connected with a residue collection bin, and the middle section of the top of the furnace tube is provided with a phosphorus steam outlet with the diameter of 150-180 mm and is connected with a phosphorus steam inlet of a phosphorus steam condensation collection device.
7. The device of claim 4, wherein the front end of the conveying shaft is assembled in a bearing seat I through a deep groove ball bearing, the rear end of the conveying shaft is assembled in a bearing seat II through a bearing of the same type, the bearing seat I is fixed on a support I through bolts, the rear end of the support I is in sealing connection with a front end cover of a furnace tube through a flange, the bearing seat II is correspondingly arranged on the support II, the front end of the support II is in flange connection with the rear end cover of the furnace tube, the front end of the support I is fixedly provided with a hard tooth surface speed reducer through a motor seat, and the input end of the speed reducer is connected with a three-phase asynchronous motor through a coupling.
8. The device of claim 4, wherein 2 groups of front supporting frames and rear supporting frames are symmetrically arranged below the furnace tube, the front supporting frames are fixed on a supporting seat I through expansion bolts, the rear supporting frames are correspondingly fixed on a supporting seat II, and the supporting seats I and II are fixed on the bottom of the frame through embedded bolts.
9. The process for continuously evaporating and recovering yellow phosphorus in phosphorus mud based on multistage flash evaporation is characterized by utilizing the device of any one of claims 1-8, and comprises the following steps: S1, material pretreatment: Feeding the phosphorus mud slurry in a phosphorus mud slurry storage tank into a phosphorus mud homogenizing and mixing tank through a pneumatic pump under the conditions of sealing and inert gas protection, adding ammonia water or sodium carbonate solution into the phosphorus mud homogenizing and mixing tank through a dosing tank, and crushing, dispersing and mixing the phosphorus mud slurry in a mode of combining steam injection with mechanical crushing at the pressure of 0.5-1.0 MPa and the temperature of 90-120 ℃ to form uniform and continuously-transportable homogeneous phosphorus mud at the temperature of 60-90 ℃; s2, primary drying: Continuously feeding pretreated homogeneous phosphorus mud into a primary material drying unit, feeding the homogeneous phosphorus mud into a furnace tube from a material inlet through a screw pump, drying at a low temperature under a closed condition and at a temperature of 120-170 ℃, removing free water, and circularly conveying generated water vapor into a phosphorus mud homogenizing and mixing tank for crushing, dispersing and mixing the phosphorus mud; s3, synchronous treatment of secondary drying and primary pyrolysis: Feeding the primary dried phosphorus mud into a material secondary drying and primary pyrolysis synchronous unit, feeding the semi-dried phosphorus mud into a furnace tube from a material inlet through a screw pump, completing the removal of bound water under the airtight condition and the condition of 180-220 ℃, and conveying the generated water vapor to a phosphorus vapor condensation and collection device for fractionating phosphorus vapor; s4, synchronous treatment of secondary pyrolysis and primary evaporation: Feeding the dried phosphorus mud material obtained in the step S3 into a material secondary pyrolysis and primary evaporation synchronous unit, feeding the dried phosphorus mud into a furnace tube from a material inlet through a screw pump, performing medium-temperature evaporation pretreatment under a closed condition at 220-350 ℃, enabling surface yellow phosphorus in the phosphorus mud to start to gasify to form phosphorus steam, and enabling the generated phosphorus steam to enter a phosphorus steam condensation collecting device; S5, second-stage efficient evaporation: Delivering the primary dephosphorization mud obtained in the step S4 into a material secondary efficient evaporation unit, delivering the primary dephosphorization mud into a furnace tube from a material inlet through a screw pump, performing gradient high-temperature evaporation treatment under a closed condition at 300-480 ℃, realizing efficient evaporation of yellow phosphorus to generate phosphorus steam, and delivering generated phosphorus-free residues into a residue collection bin; s6, phosphorus steam condensation and multi-stage spray recovery: sequentially feeding the phosphorus steam generated in S4 and S5 into a phosphorus steam condensation collection device and a multi-stage spray tower, condensing and recovering the phosphorus steam step by step to form liquid yellow phosphorus, feeding the liquid yellow phosphorus into a yellow phosphorus receiving tank, collecting excessive condensed water generated in the yellow phosphorus receiving tank, purifying tail gas generated in the spray tower through a tail gas purification system, and discharging the tail gas reaching the standard; s7, recycling residues: And (3) sending the phosphorus-free residues into a residue crushing and moisture absorption preventing packaging treatment unit for crushing, moisture absorption preventing packaging and recycling treatment under the inert or oxygen-isolating condition.
10. The process according to claim 9, wherein in step S1, the solid content of the phosphorus mud slurry is 50-80%, the concentration of the aqueous ammonia or sodium carbonate solution is 1-5 wt.%, the mixing treatment 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.

Description

Device and process for recovering yellow phosphorus in phosphorus mud based on multistage flash evaporation continuous evaporation Technical Field The invention belongs to the technical field of phosphorus recovery treatment, and particularly relates to a device and a process for continuously evaporating and recovering yellow phosphorus in phosphorus mud based on multistage flash evaporation. Background The phosphorus mud is one of main byproducts generated in the yellow phosphorus production process by an electric furnace method, wherein the phosphorus content is different according to different refining degrees in the yellow phosphorus production process, and the phosphorus content is generally about 5% -40%. The production of phosphorus mud not only increases the production cost of yellow phosphorus production enterprises, but also causes serious pollution to the surrounding environment. It is counted that about 0.1 to 0.2 tons of sludge phosphorus is produced per 1 ton of yellow phosphorus produced. The main components of the impurities are SiO 2、CaO、Fe2O3、Al2O3, mineral powder, coke dust and the like, and the balance is water. The hydrophilic SiO 2 part forms silica gel and adsorbs impurities such as yellow phosphorus, mineral powder, coke dust and the like to form slurry with high viscosity and stability. These slurries are partially coated with yellow phosphorus to form a gel which is difficult to separate and relatively stable. At present, the main process for recovering yellow phosphorus from phosphorus mud comprises a high-temperature distillation method, a solvent extraction method, a mechanical filter pressing method and the like, and mainly uses traditional rotary kiln evaporation equipment, and the technology is relatively backward, and has the outstanding technical defects that (1) the traditional equipment (such as a rotary kiln) is mainly heated or intermittently temperature controlled, so that accurate regulation and control of a gradient temperature field are difficult to realize, the moisture removal is incomplete, the evaporation efficiency of the yellow phosphorus is low, the phosphorus recovery rate is low, the temperature fluctuation is easy to cause phosphorus steam flash or the local height Wen Xielou of the equipment, and huge potential safety hazards exist, (2) the traditional condensation process is mainly cooled by direct water cooling or simple indirect cooling, the phosphorus mud is easy to contact with water, the solid-liquid components are uneven, the blockage and the pulse flow are caused, the material distribution in the evaporator is uneven, the heat transfer and mass transfer efficiency is reduced, the batch processing capacity is limited, the equipment stability is insufficient, the continuous production is difficult to realize, 3) the traditional static sealing or packing sealing is easy to lose efficacy in a high-temperature phosphorus-containing medium, the safety accident is caused, the phosphorus steam leakage causes environmental pollution and the product loss, and the traditional condensation process is mainly cooled by direct water cooling or simple indirect cooling, the phosphorus is easy to contact with water, the pollution and the pollution caused by the phosphorus steam is low in the pipeline wall pollution, and the product loss, the pollution is caused by the traditional condensation process is caused by the pollution, the pollution caused by the pipeline is caused by the pollution, the pollution caused by the pipeline and the pollution is caused by the high and the pollution, the pollution is caused by the high because and the pollution is caused by the high. Therefore, there is a need to develop an efficient, safe, continuous, environmentally friendly phosphorus mud recovery process and apparatus. In the prior art, in order to improve the feeding uniformity and the phosphorus evaporation efficiency of phosphorus mud, a phosphorus evaporation device is modified, and the colloid structure of the phosphorus mud is destroyed by adopting mechanical stirring by means of the physical and chemical characteristics of materials, so that the mutual contact and condensation of yellow phosphorus particles are promoted. However, the existing stirring process is extremely easy to cause yellow phosphorus ignition due to friction and air leakage, and the separation of phosphorus and other impurities is not thorough enough, so that the subsequent phosphorus steaming recovery efficiency is not high. Disclosure of Invention Aiming at the inherent physicochemical characteristics of phosphorus mud, the invention provides a device and a process for continuously evaporating and recycling yellow phosphorus in phosphorus mud based on multistage flash evaporation by combining evaporation, drying and pyrolysis technical principles, and a phosphorus steaming process integrating a pretreatment system, an integrated system and a product recycling and processing system and integrating