Acid mixer for phosphoric acid production based on wet process

Abstract

The invention belongs to the technical field of wet-process phosphoric acid production equipment, and discloses an acid mixer based on wet-process phosphoric acid production, the acid mixer comprises a mother pipe and an extraction tank body, the lower end part of the mother pipe is fixedly connected with a son pipe through a flange bolt, the son pipe is sleeved with a sleeve pipe II, the sleeve pipe II is sleeved with a sleeve pipe I, and the sleeve pipe I is sleeved with a sleeve pipe II; the upper end part of the sleeve II is fixedly connected with the upper end part of the sleeve I through a flange bolt, the sleeve I is arranged on the extraction tank body in a penetrating manner, and the sleeve I is fixedly connected with the extraction tank body; the main pipe is located above the extraction tank body, an ore pulp pipe communicated with the main pipe is arranged on the outer side of the main pipe, and the lower ends of the sub pipe and the second sleeve pipe extend into the extraction tank body. According to the scheme, a unique structural design is adopted, so that sulfuric acid is output in a spraying manner and is quickly dispersed in phosphoric ore pulp, the phenomenon of local over-concentration is avoided, centralized release of heat is effectively reduced, the local overheating risk of the device is reduced, the service life is prolonged, and the operation stability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wet process phosphoric acid production equipment, and more specifically to an acid mixer used in wet process phosphoric acid production. Background Art

[0002] The phosphoric acid extraction reaction tank is a key equipment in the production of wet phosphoric acid. The process involves a complex chemical reaction between phosphate slurry and sulfuric acid, dilute phosphoric acid and other substances in the tank to generate phosphoric acid and dihydrate calcium sulfate (CaSO4.2H2O) crystals. This reaction process has a crucial impact on the production efficiency, product quality and production cost of phosphoric acid.

[0003] The common phosphoric acid extraction reaction tank process includes the following steps (taking dihydrate wet phosphoric acid extraction as an example): the flow rate of phosphate slurry and sulfuric acid is set at a certain ratio, and the sulfuric acid enters the acid mixer and the outlet pipe of the axial flow pump after metering, and is pre-mixed with the slurry from the filtered dilute phosphoric acid and the outlet pipe of the axial flow pump, and added to the first chamber, second chamber, and third chamber of the reaction tank for sufficient reaction. The reaction slurry is flash-cooled by the low-level flash cooling circulation pump located in the sixth chamber of the reaction tank, and the cooled slurry is returned to the first chamber of the reaction tank from the low-level flash cooler by gravity.

[0004] The overall reaction is expressed as follows: Ca5F(PO4)3+ 5H2SO4+ 10H2O = 3H3PO4+ 5CaSO4·2H2O + HF↑ In actual production, the reaction is carried out in two steps: 1) The phosphate rock particles are first decomposed by dilute phosphoric acid to produce monocalcium phosphate Ca5F(PO4)3+ 10H3PO4= 3H3PO4+ 5Ca(H2PO4)2+ HF↑; 2) Monocalcium phosphate continues to react with sulfuric acid to form phosphoric acid and calcium sulfate dihydrate crystals 5Ca(H2PO4)2 + 5H2SO4+10H2O = 10H3PO4+ 5CaSO4·2H2O↓. Factors affecting reaction rate: The reaction process of phosphate rock decomposition by sulfuric acid is a liquid-solid phase reaction, and its reaction rate is mainly related to factors such as reaction temperature, hydrogen ion concentration, effective surface area of ​​ore particles and diffusion of liquid film.

[0005] Side reaction problem: During the slurry reaction process, especially when the slurry grade is low and the impurity content is high, the side reaction is more intense.

[0006] For example, carbonates in the slurry are easily decomposed by sulfuric acid to produce sulfates, and decomposed by phosphoric acid to produce phosphates and release CO2: CaCO3+H2SO4+H2O=CaSO4.2HO2+CO2 MgCO3+H2SO4=MgSO4+CO2+H2O MgCO3+H3PO4=Mg(H2PO4)2+CO2+H2O+CO2 Disadvantages of traditional mixed acid method: 1. Insufficient mixing: In the sulfuric acid addition area of ​​the reaction tank, sulfuric acid needs to be quickly dispersed in the slurry, but the traditional ordinary acid mixer only combines the main pipe and the sub-pipe at the outlet to achieve mixing. This method is difficult to ensure that sulfuric acid and phosphate slurry are fully mixed, and it is easy to produce local over-concentration, affecting the uniformity and efficiency of the reaction.

[0007] 2. Large heat release: During the mixing process, ordinary acid mixers release a lot of heat due to the combination of flow rate and area. This has many impacts on the device, such as causing local overheating of the device, affecting the service life and operating stability of the equipment, and also increasing energy consumption.

[0008] 3. Foam problem: Rapid dilution of sulfuric acid by the slurry will release a large amount of heat, resulting in an increase in the foam volume ratio in the circulating slurry, thinning of the foam wall, and poor stability. It is necessary to add a defoaming agent to eliminate the foam, which not only increases production costs, but may also have a certain impact on product quality.

[0009] 4. Pipeline blockage: Problems such as insufficient mixing and large heat release may also cause pipeline blockage, affecting the normal operation of the device, increasing maintenance costs and downtime, and reducing production efficiency. Summary of the invention

[0010] The purpose of the present invention is to solve the shortcomings in the prior art and to propose an acid mixer for wet process phosphoric acid production.

[0011] To solve the above problems, the present invention adopts the following technical solutions: A mixing acid device for wet-process phosphoric acid production comprises a main tube and an extraction tank body, wherein the lower end of the main tube is fixedly connected with a sub-tube via a flange bolt, a sleeve 2 is sleeved on the sub-tube, a sleeve 1 is sleeved on the sleeve 2, an upper end of the sleeve 2 is fixedly connected with an upper end of the sleeve 1 via a flange bolt, the sleeve 1 is inserted into the extraction tank body, and the sleeve 1 is fixedly connected with the extraction tank body; The main pipe is located above the extraction tank body, a slurry pipe connected to the main pipe is arranged on the outside of the main pipe, and the lower ends of the sub-pipe and the second sleeve extend to the inside of the extraction tank body; A spray pipe is inserted into the main pipe, the upper end of the spray pipe is fixedly connected to the main pipe by a flange bolt, the bottom end of the spray pipe extends into the sub-pipe, and a spray structure is provided at the bottom end of the spray pipe, and the spray structure is close to the lower end of the sub-pipe.

[0012] As a further solution of the present invention: the spray structure includes a transition joint connected to the lower end of the spray pipe, the lower end of the transition joint is connected to a spray head, and the pipe wall of the spray head is evenly distributed with spray holes.

[0013] As a further solution of the present invention: the distance between the lower end of the sleeve 2 and the bottom of the top plate of the extraction tank body is 1500 mm, and the distance between the lower end of the sub-tube and the bottom of the top plate of the extraction tank body is 3000 mm.

[0014] As a further solution of the present invention: the size of the spray pipe is ∅133×12mm, and the size of the sleeve 2 is ∅426×8mm.

[0015] As a further solution of the present invention: the size of the slurry pipe is ∅219×6mm.

[0016] As a further solution of the present invention: the size of the main tube is ∅325×6mm, and the size of the sub-tube is ∅325×20mm.

[0017] Compared with the prior art, the advantages of the present invention are: This solution adopts a unique structural design to enable sulfuric acid to be output in the phosphate slurry by spraying and quickly dispersed, avoiding the phenomenon of local overconcentration, effectively reducing the concentrated release of heat, reducing the risk of local overheating of the device, extending the service life, and improving the operation stability. At the same time, the spray pipe is extended to the bottom of the slurry to play the role of secondary sulfuric acid addition, which not only reduces the overflow of fluorine-containing gas, is beneficial to environmental protection, but also improves the speed and efficiency of reaction crystallization. In addition, the flange bolt connection method is easy to disassemble and install, which is convenient for the maintenance and overhaul of the equipment, and has significant economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] Description of the markings in the figure: 1. Casing 1; 2. Mother pipe; 3. Spray pipe; 4. Slurry pipe; 5. Extraction tank body; 6. Casing 2; 7. Transition joint; 8. Sprinkler; 9. Sub-pipe. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0021] See also Figure 1 The mixed acid device for wet phosphoric acid production includes a mother pipe 2 and an extraction tank body 5. The lower end of the mother pipe 2 is fixedly connected with a sub-pipe 9 by flange bolts. The sub-pipe 9 is sleeved with a second sleeve 6. The second sleeve 6 is sleeved with a first sleeve 1. The upper end of the second sleeve 6 is fixedly connected with the upper end of the first sleeve 1 by flange bolts. The first sleeve 1 is inserted into the extraction tank body 5. The first sleeve 1 is fixedly connected with the extraction tank body 5. The mother pipe 2 is located above the extraction tank body 5. The outer side of the mother pipe 2 is provided with a slurry pipe 4 connected thereto. The slurry pipe 4 is used to transport phosphate slurry into the mother pipe. The lower ends of the sub-pipe 9 and the second sleeve 6 are extended to the inside of the extraction tank body 5. The setting of the first sleeve 1 and the second sleeve 6 not only protects the internal sub-pipe 9 and other components, but also helps to maintain the stability of the reaction system to a certain extent. The second sleeve 6 is sleeved on the sub-pipe 9 and connected with the first sleeve 1 to form a relatively stable structural system, which can withstand the pressure and impact force during the reaction process and ensure the structural integrity of the entire acid mixer.

[0022] A spray pipe 3 is inserted into the main pipe 2, and the spray pipe 3 is used to input concentrated sulfuric acid. The upper end of the spray pipe 3 is fixedly connected to the main pipe 2 by a flange bolt, and the bottom end of the spray pipe 3 extends into the sub-pipe 9. A spray structure is provided at the bottom end of the spray pipe 3. The spray structure is close to the lower end of the sub-pipe 9 and outputs sulfuric acid from the bottom.

[0023] When the acid mixer is working, the main pipe 2 is located above the extraction tank body 5, the sub-pipe 9 is located in the extraction tank body 5, the slurry pipe 4 is used to transport phosphate slurry into the main pipe 2 and the sub-pipe 9 into the extraction tank body 5; at the same time, the spray pipe 3 is used to transport concentrated sulfuric acid, and the spray pipe 3 and the spray structure form a dispersion device for sulfuric acid. The spray structure sprays sulfuric acid at the bottom of the sub-pipe 9, so that sulfuric acid is quickly dispersed in the phosphate slurry and fully mixed to avoid the phenomenon of local overconcentration, ensuring that the concentration of sulfuric acid and phosphate slurry at each point in the reaction tank is consistent, making the mixing more complete, which is conducive to improving the production efficiency and quality of phosphoric acid. In addition, the spray mixing method allows sulfuric acid and phosphate slurry to be gradually mixed. After the concentrated sulfuric acid and slurry react, the liquid phase temperature is about 90°C, the slurry temperature is about 80°C, and the gas phase temperature is about 75°C. Compared with the traditional mixing method, it effectively reduces the concentrated release of heat, reduces the risk of local overheating of the device, extends the service life of the device, and improves the operating stability of the device. Heat generation is reduced, thereby reducing the generation of foam. The reduction in the amount of foam generated correspondingly reduces the use of defoaming solvents, reduces production costs, and also reduces the problem of pipeline blockage caused by foam, extends the operating cycle of the device, and improves the production efficiency of the device.

[0024] Specifically, the spray structure includes a transition joint 7 connected to the lower end of the spray pipe 3, and a nozzle 8 is connected to the lower end of the transition joint 7, and the nozzle 8 has spray holes evenly distributed on the pipe wall. The concentrated sulfuric acid input into the spray pipe 3 is sprayed out through the nozzle 8, and can be mixed with the phosphate slurry from multiple directions, so as to form a better mixed contact. In addition, the flange bolt connection in this embodiment is convenient for disassembly and installation and fixing.

[0025] In addition, the lower end of the sleeve 6 is 1500 mm away from the bottom of the top plate of the extraction tank body 5, and the lower end of the sub-tube 9 is 3000 mm away from the bottom of the top plate of the extraction tank body 5. This design allows the spray pipe 3 to be extended to 200-300 mm below the liquid surface of the slurry, playing the role of adding sulfuric acid twice, so that sulfuric acid can be mixed at the end while reducing the overflow of fluorine-containing gas and improving the speed and efficiency of reaction crystallization.

[0026] The dimensions of the spray pipe 3 are ∅133×12mm, and the dimensions of the casing 2 6 are ∅426×8mm. The dimensions of the slurry pipe 4 are ∅219×6mm. The dimensions of the main pipe 2 are ∅325×6mm, and the dimensions of the sub-pipe 9 are ∅325×20mm. These dimensions are carefully designed and calculated, and they match each other to ensure that the material flows smoothly in the acid mixer without blockage or uneven flow rate.

[0027] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A mixing acid device for wet process phosphoric acid production, characterized in that: It comprises a main tube (2) and an extraction tank body (5), the lower end of the main tube (2) being fixedly connected to a sub-tube (9) by means of flange bolts, a second sleeve (6) being sleeved on the sub-tube (9), a first sleeve (1) being sleeved on the second sleeve (6), an upper end of the second sleeve (6) being fixedly connected to an upper end of the first sleeve (1) by means of flange bolts, the first sleeve (1) being inserted into the extraction tank body (5), and the first sleeve (1) being fixedly connected to the extraction tank body (5); The main pipe (2) is located above the extraction tank body (5), a slurry pipe (4) in communication with the main pipe (2) is arranged on the outside of the main pipe (2), and the lower ends of the sub-pipe (9) and the second sleeve (6) extend into the interior of the extraction tank body (5); A spray pipe (3) is inserted into the mother pipe (2), the upper end of the spray pipe (3) is fixedly connected to the mother pipe (2) by means of flange bolts, the bottom end of the spray pipe (3) extends into the sub-pipe (9), and a spray structure is provided at the bottom end of the spray pipe (3), the spray structure being close to the lower end of the sub-pipe (9).

2. The acid mixer for wet process phosphoric acid production according to claim 1, characterized in that: The spray structure comprises a transition joint (7) connected to the lower end of the spray pipe (3); a spray head (8) is connected to the lower end of the transition joint (7); and spray holes are evenly distributed on the pipe wall of the spray head (8).

3. The acid mixer for wet process phosphoric acid production according to claim 1, characterized in that: The distance between the lower end of the second sleeve (6) and the bottom of the top plate of the extraction tank body (5) is 1500 mm, and the distance between the lower end of the sub-tube (9) and the bottom of the top plate of the extraction tank body (5) is 3000 mm.

4. The acid mixer for wet process phosphoric acid production according to claim 1, characterized in that: The dimensions of the spray pipe (3) are ∅133×12 mm, and the dimensions of the second sleeve (6) are ∅426×8 mm.

5. The acid mixer for wet process phosphoric acid production according to claim 1, characterized in that: The size of the slurry pipe (4) is ∅219×6 mm.

6. The acid mixer for wet process phosphoric acid production according to claim 1, characterized in that: The dimensions of the main tube (2) are ∅325×6 mm, and the dimensions of the sub-tube (9) are ∅325×20 mm.

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