An extraction tank for wet-process phosphoric acid extraction

Abstract

The utility model discloses a kind of extraction tank for wet-process phosphoric acid extraction, it is related to wet-process phosphoric acid production equipment technical field, including including jar body, top cover and stirring assembly;Jar body is the structure of upper portion cylinder, lower portion cone, and multiple ultrasonic transducers are arrayed and embedded and installed on the inner wall of jar body upper and lower end, the inner wall of jar body is also circumferentially arranged with guide vane, the inner bottom of jar body is also installed with gas distributor, the jar body is made of inner layer and outer layer, inner layer adopts tantalum metal lining layer, outer layer adopts fluorine plastic coating layer.The design is formed by tantalum metal lining layer and fluorine plastic coating layer Composite anticorrosion structure, make tank body corrosion resistance greatly enhance, reduce the replacement frequency of shutdown, further improve the service life of equipment, and adopt radial flow type paddle and turbine type paddle and the cooperation of guide vane and gas distributor, form multistage mixing system, eliminate stirring dead angle, and cooperate the cavitation effect of ultrasonic transducer, can effectively strip solid phase deposition, reduce cleaning cost.

Description

Technical Field

[0001] This utility model relates to the technical field of wet-process phosphoric acid production equipment, and in particular to an extraction tank for wet-process phosphoric acid extraction. Background Technology

[0002] In the wet-process phosphoric acid production process, the extraction tank is the core equipment for realizing the reaction between phosphate rock and acid solution and completing the extraction of P2O5. However, existing wet-process phosphoric acid extraction tanks generally have the following key defects, which seriously restrict production efficiency and safety:

[0003] First, phosphoric acid and fluorine-containing impurities (such as HF) in the system are extremely corrosive. Traditional extraction tanks mostly use stainless steel or rubber linings as anti-corrosion layers. The former is easily damaged by hydrofluoric acid, which can lead to perforation, while the latter is easily penetrated and aged by phosphoric acid. The equipment lifespan is usually less than 2 years, and frequent shutdowns are required to replace the tank, which not only increases the operation and maintenance costs but also interrupts continuous production.

[0004] Secondly, the extraction process involves a three-phase mixture of "solid (phosphate rock particles) - liquid (acid) - liquid (extractant)". Existing equipment relies too much on mechanical stirring alone, which easily creates vortex dead zones in the tank, causing phosphate rock particles to settle or local concentrations to be too high. The P2O5 extraction rate is generally reduced by 3-5% (only 92%-95%), and the energy consumption of mechanical stirring remains high.

[0005] To address the above problems, this utility model provides an extraction tank for wet phosphoric acid extraction. Utility Model Content

[0006] To address the shortcomings of existing technologies, this invention provides an extraction tank for wet phosphoric acid extraction, which solves the problems mentioned in the background section.

[0007] To achieve the above objectives, this utility model is implemented through the following technical solution: an extraction tank for wet phosphoric acid extraction, comprising a tank body, a top cover installed on the top of the tank body, and a stirring assembly installed inside the tank body;

[0008] The tank has a cylindrical upper part and a conical lower part structure, and multiple ultrasonic transducers are embedded in an array at both the upper and lower ends of the inner wall of the tank. The inner wall of the tank is also circumferentially arranged with guide plates.

[0009] A gas distributor is also installed at the bottom of the tank, and the tank is composed of an inner layer and an outer layer.

[0010] As a further technical solution of this utility model, the inner layer of the tank is made of tantalum metal lining, and its outer layer is made of fluoroplastic coating.

[0011] As a further technical solution of this utility model, the stirring assembly includes a drive motor mounted on the top center of the top cover via a bracket, the output end of the drive motor is connected to a stirring rod that penetrates into the tank body, the stirring rod and the top cover are rotatably connected, and a sealing assembly is provided between the stirring rod and the top cover;

[0012] The upper surface of the stirring rod is equipped with radial impeller blades, and the lower surface of the stirring rod is equipped with turbine impeller blades.

[0013] As a further technical solution of this utility model, the bottom end of the stirring rod is rotatably connected to a bracket, which is fixed to the tank wall at the bottom of the tank body.

[0014] As a further technical solution of this utility model, the gas distributor is fixed to the outside of the bottom end of the stirring rod, and the bottom end of the tank is also equipped with an air inlet pipe extending into its interior. One end of the air inlet pipe is connected to the air inlet end of the gas distributor, and the other end of the air inlet pipe is connected to an external gas source.

[0015] As a further technical solution of this utility model, the top of the top cover is also provided with a feed inlet, the bottom of the tank is rectangular and is equipped with support legs, the bottom of the tank is also connected to a discharge pipe, and a valve is provided on the discharge pipe.

[0016] As a further technical solution of this utility model, the sealing assembly includes a nitrogen pressurization chamber provided on the top cover corresponding to the connection between the stirring rod and the top cover, and a gas supply pipe and a pressure gauge extending to the nitrogen pressurization chamber are also provided on the top cover.

[0017] This invention provides an extraction tank for wet phosphoric acid extraction, which has the following advantages compared with the prior art:

[0018] 1. The extraction tank for wet phosphoric acid extraction designed in this paper has a composite anti-corrosion structure formed by a tantalum metal lining layer and a fluoroplastic coating, which greatly enhances the corrosion resistance of the tank, reduces the number of downtime replacements, and further improves the service life of the equipment. In addition, a nitrogen pressurization chamber is added at the top cover and the stirring rod to achieve zero leakage of acidic media, avoid the leakage of toxic gases such as HF, and eliminate safety hazards.

[0019] 2. The extraction tank for wet phosphoric acid extraction designed in this paper adopts the combination of radial flow impeller and turbine impeller, as well as guide plate and gas distributor to form a multi-stage mixing system, eliminating dead zones of stirring. Moreover, the lower conical structure facilitates material flow. Combined with the cavitation effect of ultrasonic transducer, it can effectively peel off solid phase deposits and reduce cleaning costs. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of an extraction tank used for wet phosphoric acid extraction.

[0021] Figure 2 This is a front view of an extraction tank used for wet phosphoric acid extraction;

[0022] Figure 3 This is a schematic diagram of the internal structure of an extraction tank used for wet phosphoric acid extraction.

[0023] Figure 4 This is an internal front view of an extraction tank used for wet phosphoric acid extraction.

[0024] In the diagram: 1. Tank body; 2. Top cover; 21. Feed inlet; 22. Drive motor; 23. Nitrogen pressurization chamber; 3. Support leg; 4. Air inlet pipe; 5. Discharge pipe; 6. Stirring rod; 61. Radial impeller; 62. Turbine impeller; 63. Support; 7. Gas distributor; 8. Ultrasonic transducer; 9. Guide plate. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the protection scope of the present utility model.

[0026] Please see Figure 1-4 This utility model provides a technical solution for an extraction tank for wet phosphoric acid extraction: an extraction tank for wet phosphoric acid extraction includes a tank body 1, a top cover 2 installed on the top of the tank body 1, and a feed inlet 21 provided on the top of the top cover 2 for introducing phosphate rock slurry, acid solution and extractant. The bottom of the tank body 1 is rectangular and equipped with support legs 3 for supporting the entire equipment. The bottom of the tank body 1 is also connected to a discharge pipe 5, and a valve is provided on the discharge pipe 5 for discharging the mixture after extraction.

[0027] The tank body 1 is also equipped with a stirring assembly, which includes a drive motor 22 mounted on the top center of the top cover 2 via a bracket. The output end of the drive motor 22 is connected to a stirring rod 6 that penetrates into the tank body 1. The stirring rod 6 is rotatably connected to the top cover 2. The speed of the stirring rod 6 can be adjusted to 50-80 rpm.

[0028] The upper surface of the stirring rod 6 is equipped with radial impeller 61 for radial dispersion of materials in the middle, and the lower surface of the stirring rod 6 is equipped with turbine impeller 62 for axial tumbling of materials at the bottom. Through the double-layer stirring of radial and axial directions, the mixing dead zone is eliminated. The bottom end of the stirring rod 6 is also rotatably connected to the bracket 63, which is fixed to the tank wall at the bottom of the tank body 1. The bracket 63 can enhance the stability of the stirring rod 6 and prevent shaking during high-speed stirring. The bracket 63 is a triangular frame structure and is made of Hastelloy.

[0029] Tank 1 has a cylindrical upper section and a conical lower section. The conical lower section has an inclination angle of 60°-75° to facilitate the flow of solid materials and reduce bottom sedimentation. Tank 1 consists of an inner and an outer layer. The inner layer is a 0.5-1mm thick tantalum metal lining, and the outer layer is a 1.0-15mm thick fluoroplastic coating (material PTFE or PFA).

[0030] Multiple ultrasonic transducers 8 are embedded in an array at the upper and lower ends of the inner wall of the tank 1. The ultrasonic transducers 8 operate at a frequency of 20-40kHz. They remove solid impurities attached to the tank wall through ultrasonic cavitation effect, achieving self-cleaning. The inner wall of the tank 1 is also circumferentially arranged with guide plates 9. The angle between the guide plates 9 and the inner wall of the tank 1 is 15°-30°, which can destroy the vortex formed during the stirring process, enhance the turbulence of the material, and further improve the mixing uniformity.

[0031] A gas distributor 7 is also installed at the bottom of the tank body 1. The gas distributor 7 has an annular porous structure with a pore diameter of 2-3 mm. The gas distributor 7 is fixed to the outside of the bottom end of the stirring rod 6. An air inlet pipe 4 extending into the bottom of the tank body 1 is also installed. One end of the air inlet pipe 4 is connected to the air inlet end of the gas distributor 7, and the other end of the air inlet pipe 4 is connected to an external gas source. The gas source is an N2 gas source with a purity of ≥99.9%. The N2 forms microbubbles through the gas distributor 7, which promotes the dispersion of phosphate rock particles and increases the suspension rate to over 98%.

[0032] A sealing assembly is provided between the stirring rod 6 and the top cover 2. The sealing assembly includes a nitrogen pressurization chamber 23 on the top cover 2 corresponding to the connection between the stirring rod 6 and the top cover 2. The top cover 2 is also provided with a gas supply pipe and a pressure gauge extending to the nitrogen pressurization chamber 23. An inert gas (nitrogen) is used to form a pressurized isolation chamber between the stirring rod 6 and the top cover 2, thereby forming a dynamic sealing structure. The pressure of the nitrogen pressurization chamber 23 is always higher than the working pressure inside the tank 1 (the difference is 0.02-0.05MPa), which can prevent acidic media inside the tank 1 from penetrating to the seal, achieving zero leakage. It can also adapt to a high-temperature environment of 80℃, avoiding long-term contact between the sealing point of the stirring rod 6 and the top cover 2 with high-temperature (about 80℃) acidic media. Traditional sealing structures are easily corroded and fail, leading to the leakage of toxic media (such as HF), which poses a safety hazard.

[0033] The working principle of this utility model is as follows: When in use, phosphate rock slurry, sulfuric acid and extractant are fed into tank 1 in proportion through the feed port 21 on the top cover 2. Then, the drive motor 22 is started by the external controller to drive the stirring rod 6 to rotate. The radial flow blade 61 realizes the radial dispersion of the material in the middle, and the turbine blade 62 realizes the axial turning of the material at the bottom.

[0034] At the same time, the valve of the intake pipe 4 is opened, and N2 forms tiny bubbles through the gas distributor 7, which promotes the suspension of phosphate rock particles; the guide plate 9 disrupts the vortex flow and enhances the degree of turbulence.

[0035] Furthermore, the ultrasonic transducer 8 is activated, and the silicate impurities attached to the tank wall are stripped off through the cavitation effect. With the help of the lower conical structure, the impurities flow with the material towards the discharge pipe 5.

[0036] During use, the nitrogen pressurization chamber 23 maintains pressure to prevent acidic media in tank 1 from penetrating to the mechanical seal on the end face of the stirring rod 6, ensuring zero leakage. After extraction, the valve of the discharge pipe 5 is opened to discharge the mixture to the subsequent separation process.

[0037] The above description is merely a preferred embodiment of this utility model. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this utility model, and these improvements and modifications should also be considered within the scope of protection of this utility model. Structures, devices, and operating methods not specifically described or explained in this utility model are implemented according to conventional methods in the art, unless otherwise specified or limited.

Claims

1. An extraction tank for wet phosphoric acid extraction, characterized in that, Includes a tank (1), the top of which is fitted with a top cover (2), and the tank (1) is also equipped with a stirring assembly inside; The tank (1) has a structure of a cylinder at the top and a cone at the bottom. Multiple ultrasonic transducers (8) are embedded in the upper and lower ends of the inner wall of the tank (1). The inner wall of the tank (1) is also circumferentially arranged with guide plates (9). The bottom of the tank (1) is also equipped with a gas distributor (7), and the tank (1) is composed of an inner layer and an outer layer.

2. The extraction tank for wet phosphoric acid extraction according to claim 1, characterized in that, The inner layer of the tank (1) is made of tantalum metal lining, and its outer layer is made of fluoroplastic coating.

3. The extraction tank for wet phosphoric acid extraction according to claim 1, characterized in that, The stirring assembly includes a drive motor (22) mounted on the top center of the top cover (2) via a bracket. The output end of the drive motor (22) is connected to a stirring rod (6) that penetrates into the tank body (1). The stirring rod (6) is rotatably connected to the top cover (2), and a sealing assembly is provided between the stirring rod (6) and the top cover (2). The upper surface of the stirring rod (6) is equipped with a radial impeller (61), and the lower surface of the stirring rod (6) is equipped with a turbine impeller (62).

4. The extraction tank for wet phosphoric acid extraction according to claim 3, characterized in that, The bottom end of the stirring rod (6) is also rotatably connected to a bracket (63), which is fixed to the tank wall at the bottom of the tank body (1).

5. The extraction tank for wet phosphoric acid extraction according to claim 1, characterized in that, The gas distributor (7) is fixed outside the bottom end of the stirring rod (6). The bottom end of the tank (1) is also equipped with an air inlet pipe (4) extending into it. One end of the air inlet pipe (4) is connected to the air inlet end of the gas distributor (7), and the other end of the air inlet pipe (4) is connected to an external gas source.

6. The extraction tank for wet phosphoric acid extraction according to claim 1, characterized in that, The top of the top cover (2) is also provided with a feed inlet (21), the bottom of the tank (1) is rectangular and is equipped with a support leg (3), the bottom of the tank (1) is also connected to a discharge pipe (5), and a valve is provided on the discharge pipe (5).

7. The extraction tank for wet phosphoric acid extraction according to claim 3, characterized in that, The sealing assembly includes a nitrogen pressurization chamber (23) on the top cover (2) corresponding to the connection between the stirring rod (6) and the top cover (2), and a gas supply pipe and a pressure gauge extending to the nitrogen pressurization chamber (23) are also provided on the top cover (2).

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