Device and method for filtering particle impurities in phosphoric acid slurry

Abstract

The invention discloses a filtering device and method for phosphoric acid slurry particle impurities, the filtering device comprises a filter, the filter is mainly composed of an outer pipe and an inner pipe, a discharge port is formed in the position, close to the top, of the filter, a feed port is formed in the middle of the filter, and a slag discharge port and a pulse pipeline are arranged at the bottom of the filter; 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 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 is effectively solved, the content of part of impurities in the reaction slurry is effectively reduced, and meanwhile blockage and abrasion of particles to a conveying pump, the pipeline and equipment are avoided; the service life of equipment is greatly prolonged; and the production efficiency of the device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wet-process phosphoric acid and relates to a filtering device and method for filtering particulate impurities in phosphoric acid slurry. Background Art

[0002] In the existing wet phosphoric acid production process, as the quality of phosphate ore decreases, the types and contents of impurities entering phosphoric acid and phosphogypsum will increase accordingly. During the acid hydrolysis of phosphate ore, feldspar, calcite, dolomite and other associated minerals will be partially decomposed under the action of phosphoric acid, sulfuric acid and hydrofluoric acid. Among them, feldspar is easily decomposed by the hydrofluoric acid generated during the acid hydrolysis of phosphate ore to form sodium fluorosilicate and potassium fluorosilicate. At the same time, since the process temperature of dihydrate wet phosphoric acid is required to be in the range of 75~80℃, a flash cooler is usually used to cool the reaction slurry, resulting in the precipitation of a large number of fine-grained fluorosilicate crystals. Such granular crystals continue to circulate and grow in the reaction tank, which not only causes wear of the agitator and centrifugal delivery pump, but also is mixed in the phosphogypsum, which is easy to cause pipeline blockage during transportation and affects the gypsum washing and filtration performance and system phosphorus yield.

[0003] The results of long-term industrial production and sampling analysis show that the appearance of this type of fluorosilicate crystals is due to the generally high feldspar content in medium and low-grade phosphate ore. Therefore, without changing the wet-process phosphoric acid production process, the physical properties of the granular impurities precipitated by crystallization are used to solve the problem of impurities and solid particles entrained in the wet-process phosphoric acid reaction slurry. Summary of the invention

[0004] The present invention aims to provide a filtering device and method for particulate impurities in phosphoric acid slurry, and solves the problem of particulate impurities generated by a flash cooler during the reaction of phosphoric acid slurry by designing a continuous particulate impurity processing device. The present invention utilizes the physical properties of particulate impurities crystallized during the wet phosphoric acid reaction to solve the problem of impurities entrained in the wet phosphoric acid reaction slurry, thereby reducing the impurity content of the reaction slurry and avoiding the wear and blockage of equipment and pipelines by particulate matter.

[0005] The technical solution of the present invention is as follows: A filter for particulate impurities in phosphoric acid slurry, the filter comprising an outer tube and an inner tube, the filter being provided with a discharge port near the top, a feed port being provided in the middle of the filter, a slag discharge port being provided at the bottom of the filter and being connected to a pulse pipeline, the discharge port being directly connected to the outer tube of the filter, the feed port being connected to the inner tube of the filter, a tapered convex opening on the side of the inner tube of the filter being aligned with the center of the feed port, the feed port being connected to an outer feed tube, the outer feed tube being connected to a condenser, the slag discharge port being aligned with the center of the bottom opening of the inner tube, the blind plate at the top of the inner tube of the filter being fixedly connected to the top flange of the outer tube by bolts, and phosphoric acid slurry and an impurity remover being mixed in a certain proportion and then entering the filter through the condenser along with the feed port.

[0006] Preferably, the filter height is positively correlated with the feed flow rate at the feed inlet, and the filter height (m) is the feed flow rate (m 3 / h) 1 / 15~1 / 25; The inner diameter of the inner tube is 1 / 5 to 1 / 10 of the height of the filter, for example, it can be 1 / 5, 1 / 6, 1 / 8, 1 / 9, or 1 / 10; 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; The inner tube is evenly distributed with circular holes of diameter 1-5 mm, and the spacing between each circular hole and the surrounding circular holes is 3-5 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, and the margin between each circular hole and the surrounding circular holes is controlled to be 3-5 mm, for example, it can be 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm. Preferably, the filter outlet and feed inlet are distributed on both sides of the filter; The distance between the filter outlet and 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 between the filter feed port and 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.

[0007] Preferably, a slag discharge port and a pulse pipe are provided at the bottom of the filter.

[0008] Preferably, the pulse pipe at the bottom of the filter is externally connected to a pulse pump, and the frequency of the pulse pump is 5-45 Hz, for example, 5 Hz, 20 Hz, 35 Hz, 40 Hz, or 45 Hz.

[0009] Preferably, the discharge port is directly connected to the outer tube of the filter.

[0010] Preferably, the feed port is connected to the inner tube of the filter, and the outer tube of the feed port is connected to the condenser.

[0011] Preferably, a pressure gauge is provided on the outer tube of the filter feed port, and the pressure of the slurry entering the filter is 0.2-0.7 MPa, for example, it can be 0.2 MPa, 0.3 MPa, 0.5 MPa, 0.6 MPa, or 0.7 MPa.

[0012] Preferably, the convex opening on the side of the inner tube of the filter is aligned with the center of the feed port of the outer tube, and the gap at the connection does not exceed 5 mm, for example, it can be 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm.

[0013] The filter slag discharge port is aligned with the center of the bottom port of the inner tube, and the gap at the connection does not exceed 5mm, for example, it can be 1mm, 2mm, 3mm, 4mm, or 5mm.

[0014] The phosphoric acid slurry particle impurity filter is used to filter the phosphoric acid slurry particle impurities, wherein the phosphoric acid slurry is a wet phosphoric acid dihydrate reaction slurry, and the phosphoric acid P in the slurry 2 O 5 The concentration is 24~28%; the phosphoric acid slurry and the impurity remover are mixed in a mass ratio of 100: (0.5~2) and then enter the filter through the condenser and the feed port. 2 O 5 The concentration may be, for example, 24%, 25%, 26%, 27%, or 28%. The mixing ratio of the phosphoric acid slurry to the impurity remover may be, for example, 100:0.5, 100:0.8, 100:1, 100:1.5, or 100:2.

[0015] Preferably, the impurity remover includes one or more of sodium salt, potassium salt, carbonate, calcium salt, silicon inorganic matter, acetylacetone, octanol, n-octanol, polyethyleneimine, polyethylene oxide, 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 compound agent is greater than 54-61%; for example, the Si / F molar ratio can be 1: 1, 1: 2, 1: 3, 1: 4, 1: 6, and the silicon activity can be 55%, 65%, 75%, 85%, 100%. The silicon inorganic matter includes one or more of diatomaceous earth, white carbon black, silicon slag, sodium aluminosilicate or sodium silicate; Further preferably, in the impurity remover, sodium fluoride, silicon slag, acetylacetone, polyethylene oxide, and polyacrylic acid are prepared 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 by massive industrial refined silicon.

[0016] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0017] The beneficial effects of the present invention are: The present invention mixes phosphoric acid slurry and an impurity remover in a certain proportion and passes the mixture through a condenser, and then the mixture enters the inner tube of the filter from a feed port in the middle of the filter. After passing through a conical convex port of the inner tube of the filter, the slurry entry pressure is increased, and heavy particles in the slurry settle downward to a slag discharge port at the bottom of the filter due to gravity, and the remaining slurry is physically separated through the circular holes of the inner tube. At the same time, solid particle impurities at the slag discharge port are kept loose under the action of a pulse pump to avoid filter blockage caused by accumulation, thereby solving the problem of particle impurities generated by phosphoric acid slurry during flash cooling, 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. The invention has certain reference significance for improving the existing wet-process phosphoric acid process and equipment stability. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 A schematic diagram of the structure of a filtering device for particulate impurities in phosphoric acid slurry; Figure 2 A schematic cross-sectional view of a filtering device for filtering particulate impurities in phosphoric acid slurry; Figure 3 A schematic diagram of the structure of the inner tube of a filtering device for particulate impurities in phosphoric acid slurry; In the figure: outer tube 1, inner tube 2, discharge port 3, feed port 4, slag discharge port 5, blind plate 6, condenser 7, pressure gauge 8, pulse pump 9. DETAILED DESCRIPTION

[0018] The following will be combined with the specific embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0019] Example 1 A filter for particulate impurities in phosphoric acid slurry, the filter comprising an outer tube 1 and an inner tube 2, the filter is provided with a discharge port 3 near the top, a feed port 4 is provided in the middle of the filter, a slag discharge port 5 is provided at the bottom of the filter and is connected to a pulse pipeline, the discharge port 3 is directly connected to the outer tube 1 of the filter, the feed port 4 is connected to the inner tube 2 of the filter, the tapered convex opening on the side of the inner tube 2 of the filter is aligned with the center of the feed port 4, the feed port 4 is connected to the outer feed tube 5, the outer feed tube 5 is connected to a condenser 7, the slag discharge port 5 is aligned with the center of the bottom of the inner tube 2, a blind plate 8 on the top of the inner tube of the filter is fixedly connected to the top flange of the outer tube by bolts, and phosphoric acid slurry and an impurity remover are mixed in a certain proportion and then enter the filter through the condenser 7 along with the feed port 4.

[0020] Phosphoric acid slurry and impurity remover are mixed in a mass ratio of 500:1 and then 10m 3 / h flow enters the filter, and a filter with a filter height of 1 / 15 of the phosphoric acid slurry flow rate is selected; the inner diameter of the inner tube of the filter is 1 / 5 of the filter height, and the inner diameter of the outer tube of the filter is twice the inner diameter of the inner tube; small circular holes with a diameter of 5mm are evenly distributed on the inner tube of the filter, and the margin between each circular hole and the surrounding circular 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 from the top and is directly connected to the outer tube of the filter; the feed port set in the middle is 1 / 2 of the total height of the filter from the top and is connected to the inner tube of the filter; the convex opening on the side of the inner tube of the filter 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; the slag discharge port is set at the bottom of the filter and is aligned with the center of the bottom opening of the inner tube; the blind plate at the top of the inner tube is fixed to the top flange of the outer tube by bolts.

[0021] Preferably, the phosphoric acid slurry (phosphoric acid P 2 O 5 Concentration 25%) and impurity remover (sodium fluoride, silicon slag, acetylacetone, polyethyleneimine, carboxymethyl chitosan prepared in a mass ratio of 2:3:0.1:0.03:0.01, Si / F molar ratio 1:2 after compounding, silicon activity 59%) were 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 impurity remover added.

[0022] Preferably, a slag discharge port and a pulse pipe are provided at the bottom of the filter.

[0023] Preferably, the pulse pipe at the bottom of the filter is externally connected to a pulse pump 9, and the frequency of the pulse pump is 35 Hz.

[0024] Preferably, the discharge port 4 is directly connected to the filter outer tube 1 .

[0025] Preferably, the feed port 3 is connected to the filter inner tube 2, and the feed port outer tube is connected to the condenser.

[0026] Preferably, a pressure gauge 8 is provided on the outer tube of the filter feed port, and the pressure of the slurry entering the filter is 0.2 MPa.

[0027] After the phosphoric acid slurry is mixed with the impurity remover, it enters the filter through the condenser and the feed port. After entering the condenser, the mixed slurry precipitates and polymerizes to form granular impurities and is discharged from the slag outlet by gravity through the pressure difference of the conical convex mouth. The phosphoric acid slurry without particulate impurities passes through the inner tube of the filter and is discharged from the discharge port. The present invention effectively solves the problem of particulate impurities generated by the temperature reduction during the flash cooler or pipeline transportation during the reaction of the phosphoric acid slurry, and effectively reduces the content of some impurities in the reaction slurry, while avoiding the blockage and wear of the delivery pump, pipeline and equipment by particulate matter, greatly extending the service life of the equipment and improving the production efficiency of the device, and has the advantages of good filtering effect, simple structure, and low processing cost.

[0028] Example 2 This embodiment provides a filtering device for filtering particulate impurities in phosphoric acid slurry, wherein the filter removes phosphoric acid slurry (phosphoric acid P 2 O 5 The method is the same as Example 1 except that the concentration of the phosphate slurry is 27%) and the impurity remover (sodium fluoride, calcium carbonate, diatomaceous earth, octanol, sodium borate decahydrate, and carboxymethyl chitosan are prepared in a mass ratio of 2:3:5:1:0.2:0.1, with a Si / F molar ratio of 1:3 and a silicon activity of 59% after compounding) are mixed in a mass ratio of 100:1.2, and the filter height is selected to be 1 / 25 of the phosphoric acid slurry flow rate.

[0029] Example 3 This embodiment provides a filtering device for phosphoric acid slurry particulate impurities. The filter is the same as that of Embodiment 1 except that fine circular holes with a diameter of 2 mm are evenly distributed on the inner tube of the filter.

[0030] Example 4 Phosphoric acid slurry (phosphoric acid P 2 O 5 The concentration is 25%) and the impurity remover (sodium fluoride, calcium bicarbonate, white carbon black, n-octanol, polyethylene oxide, carboxymethyl chitosan are configured in a mass ratio of 3:1:2:0.7:0.05:0.02, the Si / F molar ratio after compounding is 1:5, and the silicon activity is 82%) are mixed in a mass ratio of 100:0.7, and the rest are the same as in Example 1.

[0031] Example 5 Carboxymethyl chitosan was replaced by konjac glucan, and the rest was the same as in Example 1.

[0032] Comparative Example 1 This comparative example provides a filtering device for phosphoric acid slurry particulate impurities. The filter is the same as Example 1 except that fine circular holes with a diameter of 8 mm are evenly distributed on the inner tube of the filter.

[0033] Comparative Example 2 This comparative example provides a filtering device for phosphoric acid slurry particulate impurities, the filter is the same as Example 1 except that the distance between the discharge port near the top and the top is 2 / 3 of the total height of the filter.

[0034] Comparative Example 3 The impurity remover does not include polyacrylic acid, and the rest is the same as in Example 1.

[0035] Comparative Example 4 The impurity remover does not include sodium fluoride, and the rest is the same as in Example 1.

[0036] Comparative Example 5 The filter height is positively correlated with the feed flow rate at feed port 4. The filter height (m) is proportional to the feed flow rate (m 3 / h) 1 / 10; 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.

[0037] Table 1

[0038] It can be seen from the comprehensive embodiments and comparative examples that the phosphoric acid slurry after adding the impurity removal agent enters the filter after condensation, and the agent combines with the monovalent metal sodium and potassium ions in the phosphoric acid slurry to precipitate into granular particles of fluorosilicates, and the particulate impurities entrained in the slurry are discharged from the slag discharge port by gravity through the fine circular holes evenly distributed on the inner tube of the filter, and the height difference between the feed port and the discharge port is relied on to realize that the particulate impurities in the slurry are discharged from the slag discharge port by gravity, and the slurry without impurity particles is discharged from the discharge port to enter the next section. After the phosphoric acid slurry is treated by the filter, the impurities such as K, Na, Si, Al, and F in the phosphogypsum decrease to a certain extent after solid-liquid separation. And by controlling the agent composition ratio of the impurity removal agent, strictly controlling the Si / F ratio in the slurry after adding the impurity removal agent, the metal impurities sodium, potassium, silicon, and fluorine in the slurry are crystallized into stable compounds and precipitated, which solves the problem of these impurities entering the phosphogypsum, and solves the high impurity content in the phosphogypsum and the impact of the solid particles of the phosphoric acid slurry on the wall of the equipment and the blockage of the pipeline. It was unexpectedly discovered that the addition of carboxymethyl chitosan can more effectively reduce the wall adhesion and scaling of fluorosilicate substances in the slurry in the filter and pipeline, and can reduce the internal wall adhesion problem of the phosphoric acid slurry delivery pipeline during long-term operation. Since the wall adhesion of fluorosilicate and calcium sulfate is reduced, the scaling problem of the pipeline is prolonged, and the blockage caused by long-term transportation of dilute acid slurry is solved.

[0039] The technical solution of the present invention is explained through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above specific embodiments to be implemented. Any improvements made by technicians in the relevant field based on the present invention, or equivalent replacement of the materials selected by the present invention, etc., fall within the scope of protection of the patent.

Claims

1. A filter for phosphoric acid slurry particulate impurities, characterized in that: The filter mainly comprises an outer tube (1) and an inner tube (2); a discharge port (3) is arranged near the top of the filter, a feed port (4) is arranged in the middle of the filter, a slag discharge port (5) is arranged at the bottom of the filter and is connected to the pulse pipeline, the discharge port (3) is directly connected to the outer tube (1) of the filter, the feed port (4) is connected to the inner tube (2) of the filter, a conical convex opening on the side of the inner tube (2) of the filter is aligned with the center of the feed port (4), the feed port (4) is connected to the outer feed tube (5), the outer feed tube (5) is connected to the condenser (7), the slag discharge port (5) is aligned with the center of the bottom of the inner tube (2), and a blind plate (8) at the top of the inner tube of the filter is fixedly connected to the top flange of the outer tube by bolts.

2. The filter for phosphoric acid slurry particulate impurities according to claim 1, characterized in that: The height of the filter is 1 / 15 to 1 / 25 of the feed flow rate of the feed inlet (4); The inner diameter of the inner tube (2) is 1 / 5 to 1 / 10 of the height of the filter; The inner diameter of the outer tube (1) is 1.5 to 5 times the inner diameter of the inner tube (2); Circular holes with a diameter of 1 to 5 mm are evenly distributed on the inner tube (2), and the distance between each circular hole and surrounding circular holes is 3 to 5 mm.

3. The filter for phosphoric acid slurry particulate impurities according to claims 1-2, characterized in that: The filter outlet (3) and the feed inlet (4) are distributed on both sides of the filter; The distance between the filter outlet (4) and the top is 1 / 6 to 1 / 4 of the total height of the filter; The distance between the filter feed port (3) and the top is 1 / 2 to 3 / 4 of the total height of the filter.

4. The filter for phosphoric acid slurry particulate impurities according to claim 1, characterized in that: The bottom of the filter is provided with a slag discharge port (5) which is in communication with a pulse pipeline. The pulse pipeline at the bottom of the filter is externally connected to a pulse pump (9), and the frequency of the pulse pump is 5-45 Hz.

5. The filter for phosphoric acid slurry particulate impurities according to claim 1, characterized in that: The discharge port (4) is directly connected to the filter outer tube (1).

6. The filter for phosphoric acid slurry particulate impurities according to claim 1, characterized in that: The feed port (3) is connected to the inner tube (2) of the filter, and the outer tube of the feed port is externally connected to the condenser (7); A pressure gauge (8) is provided on the outer tube of the filter feed port, and the pressure of the slurry entering the filter is 0.2-0.7 MPa.

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

8. The filter for phosphoric acid slurry particulate impurities according to claim 1, characterized in that: After being mixed with the impurity remover, the phosphoric acid slurry passes through the condenser (7) and enters the filter through the feed port (4).

9. A method for filtering phosphoric acid slurry particulate impurities according to the filter for phosphoric acid slurry particulate impurities according to any one of claims 1 to 8, characterized in that: The phosphoric acid slurry is a wet process phosphoric acid dihydrate reaction slurry, and the phosphoric acid P2O5 concentration in the slurry is 24-28%; the phosphoric acid slurry and the impurity remover are mixed in a mass ratio of 100:(0.5-2) and then enter the filter through the condenser (7) and the feed port (4).

10. A method for filtering phosphoric acid slurry particulate impurities according to any one of claims 9, characterized in that: The impurity remover includes one or more of sodium salt, potassium salt, carbonate, calcium salt, silicon inorganic matter, acetylacetone, octanol, n-octanol, polyethyleneimine, polyethylene oxide, sodium borate decahydrate, carboxymethyl chitosan, yeast glucan, 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 compound agent is greater than 54-61%; the silicon inorganic matter includes one or more of diatomaceous earth, white carbon black, silicon slag, sodium aluminosilicate or sodium silicate; Preferably, in the impurity remover, sodium fluoride, silicon slag, n-octanol or acetylacetone, polyethyleneimine, carboxymethyl chitosan or yeast beta-glucan are prepared in a mass ratio of (1.5-4): (1.5-5): (0.05-1): (0.01-0.5): (0.01-0.5); Silicon slag is waste silicon slag produced by bulk industrial refining of silicon.

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