Filtering device for particle impurities in phosphoric acid slurry

Abstract

The utility model discloses a filtering device for particle impurities in phosphoric acid slurry, which comprises a filter, the filter mainly comprises an outer pipe and an inner pipe, a discharge port is arranged at the position close to the top of the filter, a feed port is arranged at the middle position of the filter, a slag discharge port and a pulse pipeline are arranged at the bottom of the filter, and the pulse pipeline is communicated with the discharge port. The discharge port is directly connected with the filter outer pipe, the feed port is connected with a conical convex opening in the side surface of the filter inner pipe, the feed port outer pipe is connected with the condensation pipe, and phosphoric acid slurry and an impurity removal agent are mixed according to a certain proportion and then enter the filter along with the feed port through the condensation pipe. The device effectively solves the problem that particle impurities are generated due to temperature reduction in the conveying process of a flash cooler or a pipeline in the phosphoric acid slurry reaction process, effectively reduces the content of part of impurities in the reaction slurry, and meanwhile prevents particles from blocking and abrading a conveying pump, the pipeline and equipment. The service life of equipment is greatly prolonged; and the production efficiency of the device is improved.

Description

Technical Field

[0001] This utility model belongs to the field of wet-process phosphoric acid technology and relates to a filtration device for particulate impurities in phosphoric acid slurry. Background Technology

[0002] In existing wet-process phosphoric acid production, as the quality of phosphate rock declines, the types and contents of impurities entering the phosphoric acid and phosphogypsum increase accordingly. During the acidolysis of phosphate rock, associated minerals such as feldspar, calcite, and dolomite are partially decomposed under the action of phosphoric acid, sulfuric acid, and hydrofluoric acid. Feldspar is particularly susceptible to decomposition by the hydrofluoric acid generated during phosphate rock acidolysis, forming sodium fluorosilicate and potassium fluorosilicate. Simultaneously, because the dihydrate wet-process phosphoric acid production requires a temperature range of 75-80℃, flash coolers are typically used to cool the reaction slurry, leading to the precipitation of a large amount of fine-particle fluorosilicate crystals. These crystals continuously grow and circulate in the reaction tank, causing wear on the agitator and centrifugal pump. Furthermore, they become trapped in the phosphogypsum, easily causing pipe blockages during transport and affecting the gypsum washing and filtration performance and the system's phosphorus yield.

[0003] Long-term industrial production and sampling analysis results show that the appearance of such fluorosilicate crystals is due to the generally high feldspar content in low- and medium-grade phosphate rock. Therefore, without changing the wet-process phosphoric acid production process, the physical properties of the crystalline particulate impurities can be utilized to solve the problem of impurities and solid particles entrained in the wet-process phosphoric acid reaction slurry. Utility Model Content

[0004] This invention aims to provide a filtration device for particulate impurities in phosphoric acid slurry. By designing a continuous particulate impurity treatment device, it solves the problem of particulate impurities generated by the flash cooler during the phosphoric acid slurry reaction. This invention utilizes the physical properties of particulate impurities that crystallize out during the wet-process phosphoric acid reaction to solve the problem of impurity entrainment in the wet-process phosphoric acid reaction slurry, thereby reducing the impurity content of the reaction slurry and avoiding wear and blockage of equipment and pipelines caused by particulate matter.

[0005] The technical solution of this utility model is as follows:

[0006] A filter for removing particulate impurities from phosphoric acid slurry, the filter comprising an outer tube and an inner tube, an outlet near the top of the filter, an inlet in the middle of the filter, a slag discharge port at the bottom of the filter connected to a pulse pipe, the outlet directly connected to the outer tube of the filter, the inlet connected to the inner tube of the filter, a conical protrusion on the side of the inner tube aligned with the center of the inlet, the inlet connected to the outer feed pipe, the outer feed pipe connected to a condenser pipe, the slag discharge port aligned with the center of the bottom opening of the inner tube, and a blind flange at the top of the inner tube and a flange at the top of the outer tube fixedly connected by bolts, wherein the phosphoric acid slurry and a scavenging agent are mixed in a certain proportion and then enter the filter through the condenser pipe and the inlet.

[0007] Preferably, the filter height is positively correlated with the feed flow rate at the inlet, and the filter height (m) is equal to the feed flow rate (m³ / h). 3 1 / 15 to 1 / 25 of ( / h);

[0008] The inner diameter of the inner tube is 1 / 5 to 1 / 10 of the filter height, for example, it can be 1 / 5, 1 / 6, 1 / 8, 1 / 9, or 1 / 10.

[0009] The inner diameter of the outer tube is 1.5 to 5 times the inner diameter of the inner tube, for example, it can be 1.5 times, 2.5 times, 3 times, 4 times, or 5 times.

[0010] The inner tube has evenly distributed circular holes with a diameter of 1 to 5 mm. The distance between each circular hole and the surrounding circular holes is 3 to 5 mm, for example, 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm. The edge distance between each circular hole and the surrounding circular holes is controlled at 3 to 5 mm, for example, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm.

[0011] Preferably, the filter outlet and the filter inlet are located on both sides of the filter;

[0012] The distance from the filter outlet to the top is 1 / 6 to 1 / 4 of the total height of the filter, for example, it can be 1 / 6, 3 / 19, 5 / 24, 11 / 48, or 1 / 4; the distance from the filter inlet to the top is 1 / 2 to 3 / 4 of the total height of the filter, for example, it can be 1 / 2, 9 / 16, 5 / 8, 11 / 16, or 3 / 4.

[0013] Preferably, the filter is provided with a slag discharge port and a pulse pipe at the bottom.

[0014] Preferably, the bottom pulse pipe of the filter is connected to an external pulse pump, and the pulse pump frequency is 5~45Hz, for example, 5Hz, 20Hz, 35Hz, 40Hz, or 45Hz.

[0015] Preferably, the discharge port is directly connected to the outer tube of the filter.

[0016] Preferably, the feed inlet is connected to the inner tube of the filter, and the outer tube of the feed inlet is connected to the condenser tube.

[0017] Preferably, a pressure gauge is installed on the outer pipe of the filter inlet, and the pressure of the slurry entering the filter is 0.2~0.7MPa, for example, 0.2MPa, 0.3MPa, 0.5MPa, 0.6MPa, or 0.7MPa.

[0018] Preferably, the protrusion on the side of the inner tube of the filter is aligned with the center of the feed inlet of the outer tube, and the gap at the connection does not exceed 5mm, for example, it can be 1mm, 2mm, 3mm, 4mm, or 5mm.

[0019] The filter discharge port is aligned with the center of the bottom opening of the inner tube, and the gap at the connection point does not exceed 5mm, for example, it can be 1mm, 2mm, 3mm, 4mm, or 5mm.

[0020] The method for filtering particulate impurities from phosphoric acid slurry, wherein the phosphoric acid slurry is a wet-process dihydrate phosphoric acid reaction slurry with a phosphoric acid P2O5 concentration of 24-28%; the phosphoric acid slurry and a decontamination agent are mixed at a mass ratio of 100:(0.5-2) and then fed into the filter through a condenser inlet. The phosphoric acid P2O5 concentration in the slurry can be, for example, 24%, 25%, 26%, 27%, or 28%. The mixing ratio of the phosphoric acid slurry and the decontamination agent can be, for example, 100:0.5, 100:0.8, 100:1, 100:1.5, or 100:2.

[0021] Preferably, the impurity remover includes one or more of sodium salts, potassium salts, carbonates, calcium salts, and inorganic silicon compounds, acetylacetone, 2-octanol, n-octanol, polyethyleneimine, polyethylene oxide, and sodium borate decahydrate. The molar ratio of Si to F in the phosphoric acid slurry with the impurity remover is 1:(1~8), and the silicon activity of the compounded agent is greater than 54~61%. For example, the Si / F molar ratio can be 1:1, 1:2, 1:3, 1:4, or 1:6, and the silicon activity can be 55%, 65%, 75%, 85%, or 100%. The inorganic silicon compounds include one or more of diatomaceous earth, silica, silicon slag, sodium aluminosilicate, or sodium silicate.

[0022] More preferably, the impurity remover is prepared by mixing sodium fluoride, silicon slag, acetylacetone, polyethylene oxide, and polyacrylic acid in a mass ratio of (1.5-2.5):(2.5-4):(0.05-0.2):(0.01-0.5):(0.01-0.5); the silicon slag is waste silicon slag produced from the refining of blocky industrial silicon.

[0023] The numerical range described in this utility model includes not only the point values ​​listed above, but also any point values ​​within the numerical range that are not listed. Due to space limitations and for the sake of brevity, this utility model will not exhaustively list all the specific point values ​​included in the range.

[0024] The beneficial effects of this utility model are as follows:

[0025] This invention mixes phosphoric acid slurry with a purification agent in a certain proportion, then passes it through a condenser tube and into the inner tube of the filter from the inlet in the middle of the filter. After passing through the conical protrusion of the inner tube, the slurry inflow pressure is increased. Heavy particles in the slurry settle downwards to the slag discharge port at the bottom of the filter due to gravity. The remaining slurry is physically separated through the round hole of the inner tube. At the same time, solid particles and impurities at the slag discharge port are kept loose under the action of the pulse pump, avoiding filter blockage caused by accumulation. This invention solves the problem of particulate impurities generated during the flash cooling process of phosphoric acid slurry, effectively reducing the impurity content in the slurry at the source of the phosphoric acid reaction slurry, extending the service life of the equipment, and improving production efficiency. It has certain reference value for improving the stability of existing wet phosphoric acid processes and equipment. Attached Figure Description

[0026] Figure 1 A schematic diagram of a filtration device for particulate impurities in phosphate slurry;

[0027] Figure 2 A cross-sectional schematic diagram of a filtration device for particulate impurities in phosphate slurry;

[0028] Figure 3 A schematic diagram of the internal tube of a filtration device for particulate impurities in phosphate slurry;

[0029] In the diagram: outer pipe 1, inner pipe 2, discharge port 3, inlet port 4, slag discharge port 5, blind flange 6, condenser pipe 7, pressure gauge 8, pulse pump 9. Detailed Implementation

[0030] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. These embodiments are merely some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0031] Example 1

[0032] A filter for removing particulate impurities from phosphate slurry, the filter comprising an outer tube 1 and an inner tube 2, an outlet 3 near the top of the filter, an inlet 4 in the middle of the filter, a slag discharge port 5 at the bottom of the filter connected to a pulse pipe, the outlet 3 being directly connected to the outer tube 1, the inlet 4 being connected to the inner tube 2, the conical protrusion on the side of the inner tube 2 being aligned with the center of the inlet 4, the inlet 4 being connected to the outer feed tube 1, the outer feed tube 1 being connected to a condenser pipe 7, the slag discharge port 5 being aligned with the center of the bottom opening of the inner tube 2, and a blind plate 6 at the top of the inner tube being bolted to the top flange of the outer tube. Phosphate slurry and impurity removal agent are mixed in a certain proportion and then enter the filter through the condenser pipe 7 and the inlet 4.

[0033] Phosphoric acid slurry and impurity remover are mixed at a mass ratio of 500:1 and then sprayed at 10m 3 A flow rate of / h enters the filter, and a filter with a height of 1 / 15 of the phosphoric acid slurry flow rate is selected. The inner diameter of the filter inner tube is 1 / 5 of the filter height, and the inner diameter of the filter outer tube is twice the inner diameter of the inner tube. Small circular holes with a diameter of 5mm are evenly distributed on the filter inner tube, and the distance between each hole and the edge of the surrounding holes is controlled at 5mm. The filter has a discharge port and a feed port distributed on both sides of the filter. The discharge port near the top is 1 / 6 of the total height of the filter and is directly connected to the filter outer tube. The feed port located in the middle is 1 / 2 of the total height of the filter and is connected to the filter inner tube. The protrusion on the side of the filter inner tube is aligned with the center of the feed port of the outer tube, and the maximum gap at the connection is 5mm. The slag discharge port of the filter is aligned with the center of the bottom opening of the inner tube, and the maximum gap at the connection is 3mm. A slag discharge port is set at the bottom of the filter and aligned with the center of the bottom opening of the inner tube. The blind plate at the top of the inner tube and the flange at the top of the outer tube are fixed with bolts.

[0034] Preferably, the phosphoric acid slurry (25% P2O5 concentration of phosphoric acid) and the impurity remover (sodium fluoride, silicon slag, acetylacetone, polyethyleneimine, and carboxymethyl chitosan prepared in a mass ratio of 2:3:0.1:0.03:0.01, with a Si / F molar ratio of 1:2 and a silicon activity of 59%) are mixed in a mass ratio of 100:0.8. The Si / F ratio is the ratio of Si to F in the phosphoric acid slurry with the impurity remover added.

[0035] Preferably, the filter is provided with a slag discharge port and a pulse pipe at the bottom.

[0036] Preferably, the bottom pulse pipe of the filter is connected to an external pulse pump 9, and the pulse pump frequency is 35Hz.

[0037] Preferably, the discharge port 4 is directly connected to the outer tube 1 of the filter.

[0038] Preferably, the feed inlet 3 is connected to the inner tube 2 of the filter, and the outer tube of the feed inlet is connected to the condenser tube.

[0039] Preferably, a pressure gauge 8 is installed on the outer pipe of the filter inlet, and the pressure of the slurry entering the filter is 0.2 MPa.

[0040] After mixing with the impurity removal agent, the phosphoric acid slurry enters the filter through the inlet via the condenser pipe. Upon entering the condenser, particulate impurities precipitate and polymerize in the slurry mixture, settling to the slag outlet under gravity due to the pressure difference of the conical convex opening. The phosphoric acid slurry, free of particulate impurities, passes through the inner tube of the filter and exits from the outlet. This invention effectively solves the problem of particulate impurities generated during the reaction of phosphoric acid slurry due to temperature reduction during flash cooling or pipeline transport, and effectively reduces the content of some impurities in the reaction slurry. It also avoids blockage and wear of the pump, pipelines, and equipment by particulate matter, significantly extending equipment lifespan and improving production efficiency. It has advantages such as good filtration effect, simple structure, and low processing cost.

[0041] Example 2

[0042] This embodiment provides a filtration device for particulate impurities in phosphate slurry. The filter is the same as in Example 1, except that the phosphate slurry (phosphate P2O5 concentration 27%) and the impurity remover (sodium fluoride, calcium carbonate, diatomaceous earth, 2-octanol, sodium borate decahydrate and carboxymethyl chitosan are mixed in a mass ratio of 2:3:5:1:0.2:0.1, and the Si / F molar ratio after compounding is 1:3, and the silicon activity is 59%) are mixed in a mass ratio of 100:1.2, and the filter height is selected to be 1 / 25 of the phosphate slurry flow rate.

[0043] Example 3

[0044] This embodiment provides a filtration device for particulate impurities in phosphate slurry. Except for the uniformly distributed small round holes with a diameter of 2 mm on the inner tube of the filter, the filter is the same as in Embodiment 1.

[0045] Example 4

[0046] Phosphoric acid slurry (25% concentration of phosphoric acid P2O5) and impurity remover (sodium fluoride, calcium bicarbonate, silica, n-octanol, polyethylene oxide, and carboxymethyl chitosan in a mass ratio of 3:1:2:0.7:0.05:0.02, with a Si / F molar ratio of 1:5 and silicon activity of 82%) were mixed at a mass ratio of 100:0.7. All other aspects were the same as in Example 1.

[0047] Example 5

[0048] Carboxymethyl chitosan was replaced with konjac glucan, and everything else was the same as in Example 1.

[0049] Comparative Example 1

[0050] This comparative example provides a filtration device for particulate impurities in phosphate slurry. Except for the uniform distribution of small round holes with a diameter of 8 mm on the inner tube of the filter, the filter is the same as in Example 1.

[0051] Comparative Example 2

[0052] This comparative example provides a filtration device for particulate impurities in phosphate slurry. The filter is the same as in Example 1, except that the distance from the top of the outlet near the top is 2 / 3 of the total height of the filter.

[0053] Comparative Example 3

[0054] The impurity remover does not include polyacrylic acid; all other components are the same as in Example 1.

[0055] Comparative Example 4

[0056] The impurity removal agent does not include sodium fluoride; all other agents are the same as in Example 1.

[0057] Comparative Example 5

[0058] The filter height is positively correlated with the feed flow rate at inlet 4. The filter height (m) is equal to the feed flow rate (m³). 3 1 / 10 of / h);

[0059] The materials of Examples 1-3 and Comparative Examples 1-2 were filtered, and the filtered phosphogypsum was analyzed. The test results are shown in Table 1.

[0060] Table 1

[0061]

[0062] As can be seen from the comprehensive examples and comparative examples, after the phosphoric acid slurry with added impurity-removing agent is condensed and enters the filter, the agent combines with the monovalent sodium and potassium ions in the slurry to precipitate as fluorosilicate particles. These particles, along with impurities entrained in the slurry, are discharged through the slag discharge port by gravity due to the height difference between the inlet and outlet, thanks to the evenly distributed fine holes in the filter's inner tube. The slurry without impurities is discharged from the outlet to the next stage. After the slurry is treated by the filter, the impurities such as K, Na, Si, Al, and F in the phosphogypsum are reduced to a certain extent after solid-liquid separation. Furthermore, by controlling the composition ratio of the impurity-removing agent and strictly controlling the Si / F ratio in the slurry after adding the agent, the metallic impurities sodium and potassium in the slurry crystallize with silicon and fluorine to form stable compounds, thus solving the problem of these impurities entering the phosphogypsum and mitigating the impact of high impurity content in phosphogypsum and solid particles from the slurry on equipment wall adhesion and pipe blockage. Furthermore, it was unexpectedly discovered that the addition of carboxymethyl chitosan can more effectively reduce the scaling and fouling of fluorosilicates in the slurry in the filter and pipeline. It can reduce the problem of internal scaling in the phosphate slurry conveying pipeline during long-term operation. By reducing the scaling of fluorosilicates and calcium sulfate, the scaling problem in the pipeline is extended, and the blockage caused by long-term transportation of dilute acid slurry is solved.

[0063] The technical solution of this utility model is explained through the above embodiments, but this utility model is not limited to the above embodiments, that is, it does not mean that this utility model must rely on the above specific embodiments to be implemented. Any improvements made by those skilled in the art based on this utility model, or equivalent substitutions for the materials selected in this utility model, fall within the scope of patent protection.

Claims

1. A filtration device for particulate impurities in phosphoric acid slurry, characterized in that, The filter device includes an outer tube (1) and an inner tube (2). The filter device has an outlet (3) near the top and an inlet (4) in the middle. The filter device has a slag discharge port (5) at the bottom that is connected to the pulse pipe. The outlet (3) is directly connected to the outer tube (1) of the filter device. The inlet (4) is connected to the inner tube (2) of the filter device. The conical protrusion on the side of the inner tube (2) is aligned with the center of the inlet (4). The inlet (4) is connected to the outer feed tube (1). The outer feed tube (1) is connected to the condenser tube (7). The slag discharge port (5) is aligned with the center of the bottom opening of the inner tube (2). The blind plate (6) at the top of the inner tube of the filter device is fixedly connected to the top flange of the outer tube by bolts. The height of the filter device is 1 / 15 to 1 / 25 of the feed flow rate at the feed inlet (4); The inner diameter of the inner tube (2) is 1 / 5 to 1 / 10 of the height of the filter device; The inner diameter of the outer tube (1) is 1.5 to 5 times the inner diameter of the inner tube (2); The inner tube (2) has evenly distributed circular holes with a diameter of 1 to 5 mm, and the distance between each circular hole and the surrounding circular holes is 3 to 5 mm.

2. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The outlet (3) and inlet (4) of the filter device are located on both sides of the filter device.

3. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The distance from the outlet (3) of the filter device to the top is 1 / 6 to 1 / 4 of the total height of the filter device; The distance from the top of the feed inlet (4) of the filter device is 1 / 2 to 3 / 4 of the total height of the filter device.

4. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The filter device is provided with a slag discharge port (5) at the bottom, which is connected to a pulse pipeline. The pulse pipeline at the bottom of the filter device is connected to an external pulse pump (9).

5. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The feed inlet (4) is connected to the inner tube (2) of the filter device, and the outer tube of the feed inlet is connected to the condenser tube (7). A pressure gauge (8) is installed on the outer pipe of the feed inlet of the filter device.

6. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The conical protrusion on the side of the inner tube (2) of the filter device is aligned with the center of the feed inlet of the outer tube (1), and the gap at the connection does not exceed 5mm; The slag discharge port (5) is aligned with the center of the bottom opening of the inner tube (2), and the gap at the connection point does not exceed 5mm.

7. The filtration device for particulate impurities in phosphoric acid slurry according to claim 1, characterized in that, The phosphate slurry, after being mixed with the impurity remover, enters the filtration device through the condenser (7) and the feed inlet (4).

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