Wet-process phosphoric acid defluorination residue recycling coupling device and production method

Abstract

The invention discloses a wet-process phosphoric acid defluorination residue recycling coupling device and a production method, the coupling device is arranged in a wet-process phosphoric acid production system, and the coupling device comprises a spiral mixing reactor (1), a mixing reactor (2) and a fluorine-containing gas washing and recycling device (3) which are sequentially arranged and connected; the production method comprises the following steps: adding concentrated sulfuric acid with the temperature of 80-90 DEG C into the wet-process phosphoric acid defluorination residues and silica fume in a spiral mixing reactor according to the mass ratio of 100: (5-10), reacting for 40-60 minutes, controlling the reaction temperature to be 90-100 DEG C, returning slurry B to a wet-process phosphoric acid production pre-extraction system, and separating and purifying the slurry B to obtain the wet-process phosphoric acid defluorination residues. Fluorine-containing gases SiF and HF generated by the mixing reaction are sent to a fluorine-containing gas washing and recycling device through a waste gas main pipe to be washed to obtain a 8-15% fluosilicic acid solution. The coupling device is coupled with an existing wet-process phosphoric acid production system, a large number of newly-added equipment and procedures are reduced, the whole process is free of three-waste emission, the method is simple in process, the fluorine recovery rate is larger than or equal to 83%, meanwhile, phosphorus is efficiently recovered, and pollution of fluorine resources to the environment is reduced.

Description

Technical Field

[0001] This invention relates to the field of fluorine resource recovery and utilization in the phosphorus chemical industry, specifically to a coupling device and production method for the recovery and utilization of wet phosphoric acid defluorination residue. Background Technology

[0002] The defluorination residue produced during the wet-process phosphoric acid production contains complex salts such as phosphoric acid, calcium sulfate, sodium (potassium) fluorosilicate, and calcium fluoride. In existing technologies, defluorination residue is mostly used to produce low-value fertilizers. For example, patents 201210457927.9 (a method for producing superphosphate from phosphoric acid residue), 201410263949.0 (a comprehensive utilization method for wet-process phosphoric acid residue), and 201510530452.5 (a method for producing phosphate-magnesium fertilizer from wet-process phosphoric acid residue) use defluorinated phosphoric acid residue as raw material to produce low-value fertilizers (such as superphosphate and phosphate-magnesium fertilizer). However, the fluorine resource recovery rate is low, and the fluorine-containing compounds (valuable fertilizers) cause environmental pollution.

[0003] Although some technologies attempt to recover fluorine resources, such as the patent with patent number 202111591552.0, entitled "A Method for Resource Utilization of White Fertilizer," the calcination method for recovering fluorine resources is costly, complex, and has a low fluorine recovery rate. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies and provide a simple coupling device for the recycling of wet phosphoric acid defluorination residue, as well as a production method thereof, which efficiently recovers fluorine resources through wet mixing reaction and simultaneously achieves phosphorus recycling.

[0005] The technical solution adopted in this invention is as follows: A coupling device for recycling wet-process phosphoric acid defluorination residue is provided. The coupling device is installed in a wet-process phosphoric acid production system. The coupling device includes a spiral mixing reactor (1), a mixing reactor (2), and a fluorine-containing gas scrubbing and recovery device (3) connected in sequence by pipelines. The mixing reactor and the fluorine-containing gas scrubbing and recovery device are connected through a waste gas main pipe. The outlet of the mixing reactor is connected to the wet-process phosphoric acid production pre-extraction system. The fluorine-containing gas scrubbing and recovery device is connected to the fluoride salt recovery workshop. The wet-process phosphoric acid defluorination residue enters the spiral mixing reactor.

[0006] Furthermore, a vertical stirred reactor is connected to the outlet of the mixing reactor, and the outlet of the vertical stirred reactor is connected to a wet phosphoric acid production pre-extraction system.

[0007] The present invention discloses a production method for a coupling device for recycling and utilizing wet-process phosphoric acid defluorination residue, comprising the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:(5-10) to obtain mixed solids A; (2) Mixing reaction: Transfer the mixed solid A into the mixing reactor, add concentrated sulfuric acid at 80-90℃, and control the temperature at 90-100℃ for 40-60 min. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain an 8-15% fluorosilicic acid solution, which is then sent to the fluoride workshop for the production of sodium fluorosilicate or sodium fluoride.

[0008] Furthermore, the mass ratio of concentrated sulfuric acid to mixed solid A in this invention is (2-2.5):1.

[0009] Furthermore, the SiO2 content of the microsilica powder described in this invention is ≥96%, and the particle size is less than 400 mesh.

[0010] Furthermore, the wet phosphoric acid defluorination residue of the present invention contains 20-25% P2O5 and 12-20% F.

[0011] This invention mainly involves the following chemical reaction processes: H2SO4+Ca(H2PO4)2.H20+H20=CaSO4.2H20+2H3PO4 (1) H2SO4+CaHPO4.2H20=CaSO4.2H20+H3PO4 (2) H2SO4+CaF=CaSO4.2H20+HF (3) 6HF + SiO2 = H2SiF6 + 2H2O (4) The beneficial effects of this invention are: 1) The method of the present invention has a fluorine recovery rate of ≥83% and also efficiently recovers phosphorus; 2) The present invention couples the spiral mixing reactor, the mixing reactor, and the fluorine-containing gas washing and recovery device with the existing wet-process phosphoric acid production system, resulting in zero emissions of waste gas, wastewater, and solid waste. 3) This invention reduces the environmental pollution caused by fluorine resources; 4) This invention uses a wet mixing reaction at a temperature of 90-100℃ to replace the traditional calcination method. The wet phosphoric acid defluorination residue and microsilica powder are premixed and then mixed with industrial concentrated sulfuric acid at 80-90℃ at a temperature of 90-100℃. Microsilica powder (SiO2≥96%) is used as an additive to promote the release of fluorine. The reaction process is coupled with the wet phosphoric acid production system and integrated through pipeline connection, reducing the need for new equipment and processes. The fluorine-containing gas released from the mixing reaction is circulated, washed, and absorbed to obtain a fluorine-containing solution, which is sent to the fluoride salt workshop for the production of sodium fluorosilicate or sodium fluoride. The mixing reaction slurry B is returned to the wet phosphoric acid production pre-extraction system to recover excess sulfuric acid and phosphorus, significantly improving the resource recovery value. This invention realizes the organic combination of defluorination residue resource treatment and wet phosphoric acid production. The coupled device and production method are simple, and the entire process has no waste discharge. Attached Figure Description

[0012] Figure 1 This is a process flow diagram of the present invention; Figure 2 This is a diagram showing the combination of the coupling device of the present invention with the wet-process phosphoric acid production system. Detailed Implementation

[0013] The following description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. Example 1

[0014] like Figure 1 , Figure 2 As shown, a production method for a wet-process phosphoric acid defluorination residue recycling coupling device includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:7 to obtain mixed solids A; (2) Mixing reaction: The mixed solid A is transferred into the mixing reactor, and concentrated sulfuric acid at 80°C is added and reacted for 40 min. The reaction temperature is controlled at 90°C. The mass ratio of the concentrated sulfuric acid to the mixed solid A is 2:1. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain an 8.6% fluorosilicic acid solution with a fluorine recovery rate of 83.3%, which is then used to further process sodium fluorosilicate, sodium fluoride and other products. Example 2

[0015] like Figure 1 , Figure 2As shown, a production method for a wet-process phosphoric acid defluorination residue recycling coupling device includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:7 to obtain mixed solids A; (2) Mixing reaction: The mixed solid A is transferred into the mixing reactor, and concentrated sulfuric acid at 85°C is added and reacted for 50 min. The reaction temperature is controlled at 95°C. The mass ratio of the concentrated sulfuric acid to the mixed solid A is 2:1. After the reaction in the mixing reactor is completed, the slurry B is transferred into the vertical stirred reactor and stirred before being sent to the wet phosphoric acid production pre-extraction system.

[0016] (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain a 9.2% fluorosilicic acid solution with a fluorine recovery rate of 85.4%, which is then used to further process sodium fluorosilicate, sodium fluoride and other products. Example 3

[0017] like Figure 1 , Figure 2 As shown, a production method for a wet-process phosphoric acid defluorination residue recycling coupling device includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:7 to obtain mixed solids A; (2) Mixing reaction: The mixed solid A is transferred into the mixing reactor, and concentrated sulfuric acid at 90°C is added and reacted for 60 min. The reaction temperature is controlled at 100°C. The mass ratio of the concentrated sulfuric acid to the mixed solid A is 2.5:1. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain a 12.4% fluorosilicic acid solution with a fluorine recovery rate of 88.6%, which is then used to further process sodium fluorosilicate, sodium fluoride and other products. Example 4

[0018] like Figure 1 , Figure 2 As shown, a production method for a wet-process phosphoric acid defluorination residue recycling coupling device includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:7 to obtain mixed solids A; (2) Mixing reaction: The mixed solid A is transferred into the mixing reactor, and concentrated sulfuric acid at 80°C is added and reacted for 60 min. The reaction temperature is controlled at 90°C. The mass ratio of the concentrated sulfuric acid to the mixed solid A is 2:1. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain a 13.1% fluorosilicic acid solution with a fluorine recovery rate of 86.2%, which is used to further process sodium fluorosilicate, sodium fluoride and other products. Example 5

[0019] like Figure 1 , Figure 2 As shown, a production method for a wet-process phosphoric acid defluorination residue recycling coupling device includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:7 to obtain mixed solids A; (2) Mixing reaction: The mixed solid A is transferred into the mixing reactor, and concentrated sulfuric acid at 90°C is added and reacted for 60 min. The reaction temperature is controlled at 100°C. The mass ratio of the concentrated sulfuric acid to the mixed solid A is 2.5:1. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The fluorine-containing gases SiF4 and HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain a 14.4% fluorosilicic acid solution with a fluorine recovery rate of 88.7%, which is then used to further process sodium fluorosilicate, sodium fluoride and other products.

[0020] The present invention uses concentrated sulfuric acid to defluorinate the slag, and adds active microsilica powder to promote the release of fluorine. The fluorine recovery rate after acid decomposition reaches more than 83%.

[0021] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A coupling device for recycling wet-process phosphoric acid defluorination residue, characterized in that, The coupling device is installed in the wet phosphoric acid production system. The coupling device includes a spiral mixing reactor (1), a mixing reactor (2), and a fluorine-containing gas washing and recovery device (3) connected by pipelines in sequence. The mixing reactor and the fluorine-containing gas washing and recovery device are connected through a waste gas main pipe. The outlet of the mixing reactor is connected to the wet phosphoric acid production pre-extraction system. The fluorine-containing gas washing and recovery device is connected to the fluoride recovery workshop. The wet phosphoric acid defluorination residue enters the spiral mixing reactor.

2. The wet-process phosphoric acid defluorination residue recycling coupling device as described in claim 1, characterized in that: A vertical stirred reactor (4) is connected to the outlet of the mixed reactor, and the outlet of the vertical stirred reactor is connected to the wet phosphoric acid production pre-extraction system.

3. The production method of the wet-process phosphoric acid defluorination residue recycling coupling device as described in claim 1 or 2, characterized in that: Includes the following steps: (1) Mixing: The wet phosphoric acid defluorination residue and microsilica powder are mixed in a spiral mixing reactor at a mass ratio of 100:(5-10) to obtain mixed solids A; (2) Mixing reaction: Transfer the mixed solid A into the mixing reactor, add concentrated sulfuric acid at 80-90℃, and control the temperature at 90-100℃ for 40-60 min. The slurry B is returned to the wet phosphoric acid production pre-extraction system. (3) Fluorine-containing gas circulation washing: The large amount of fluorine-containing gas SiF4 and a very small amount of HF generated in step (2) are sent to the fluorine-containing gas washing and recovery device through the exhaust gas main pipe to obtain an 8-15% fluorosilicic acid solution.

4. The production method as described in claim 3, characterized in that: The mass ratio of concentrated sulfuric acid to mixed solid A in step (2) is (2-2.5):

1.

5. The production method as described in claim 3, characterized in that: The microsilica powder has a SiO2 content of ≥96% and a particle size of less than 400 mesh.

6. The production method according to any one of claims 3 to 5, characterized in that: The wet-process phosphoric acid defluorination residue contains 20-25% P2O5 and 12-20% F.

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