Device and method for removing fluosilicate solid impurities in phosphoric acid reaction tank

Abstract

The invention discloses a device and method for removing fluosilicate solid impurities in a phosphoric acid reaction tank, the device comprises a slurry pipeline connected with a rear reaction chamber of the phosphoric acid reaction tank and a backflow pipeline connected with a front reaction chamber of the phosphoric acid reaction tank, the slurry pipeline is connected with an inlet of a low-position flash cooler, and a circulating pump is arranged on the slurry pipeline; an outlet of the low-position flash cooler is connected with a backflow pipeline, the backflow pipeline is communicated with the top of the vertical deslagging pipeline, an inlet valve is arranged on the upper side of the vertical deslagging pipeline, and an outlet valve is arranged on the lower side of the vertical deslagging pipeline; according to the invention, the vertical deslagging pipeline is arranged, and the continuous opening and closing switching process of the inlet valve and the outlet valve is carried out, so that the fluosilicate solid impurity removal process can be continuously carried out, and meanwhile, the normal operation of a reaction system in the phosphoric acid reaction tank can be ensured.

Description

Technical Field

[0001] The invention relates to the technical field of phosphoric acid production, in particular to a device and a method for removing fluorosilicate solid impurities in a phosphoric acid reaction tank. Background Art

[0002] At present, the company's wet phosphoric acid device uses medium and low-grade phosphate ore for production. As the grade of phosphate ore decreases, the impurity content in the ore increases, especially the content of magnesium, sodium and potassium in the impurities. Sodium fluorosilicate and other fluorosilicate solid impurities are easily generated during the reaction, resulting in an increase in the impurity content in the slurry of the phosphoric acid reaction tank. During the operation of the device, the slurry in the reaction tank is discharged in the form of feeding, but because the fluorosilicate solid impurities are easily precipitated at the bottom of the reaction tank, it is difficult to overflow into the next reaction chamber and be discharged by feeding. Since the increase of fluorosilicate solid impurities in the reaction tank cannot be discharged, it will cause the following problems: First, the accumulation of fluorosilicate solid impurities will affect the operating state of the agitator, resulting in a decrease in the reaction volume, affecting the flow of the slurry and forcing the device to be frequently shut down for cleaning and maintenance, thereby significantly shortening the normal operating cycle of the device; this not only reduces the effective production time, but also increases the non-productive downtime costs, resulting in a significant decline in the overall economic benefits; second, the presence of fluorosilicate solid impurities in the reaction tank will interfere with the effective contact and mixing between the reactants, resulting in insufficient reaction, which in turn affects the generation efficiency and quality of the phosphoric acid product, and the stability of product quality will be seriously challenged; third, fluorosilicate solid impurities cause additional wear on the blades and shaft of the agitator, increasing the risk of failure of the agitator. Once the agitator fails, it will not only require shutdown for maintenance, but also incur high costs for replacement of parts and repair services. Summary of the invention

[0003] The object of the present invention is to overcome the above-mentioned shortcomings and provide a device and method for removing fluorosilicate solid impurities in a phosphoric acid reaction tank to solve the problems raised in the background technology.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank, comprising a slurry pipeline connected to the rear reaction chamber of the phosphoric acid reaction tank and a reflux pipeline connected to the front reaction chamber of the phosphoric acid reaction tank, the slurry pipeline is connected to the inlet of a low-level flash cooler, a circulation pump is provided on the slurry pipeline, the outlet of the low-level flash cooler is connected to the reflux pipeline, the reflux pipeline is connected to the top of a vertical slag discharge pipeline, an inlet valve is provided on the upper side of the vertical slag discharge pipeline, and an outlet valve is provided on the lower side.

[0005] Preferably, the low-level flash cooler comprises a tank body, the bottom of the tank body is provided with an inclined surface, and the top of the tank body is connected to the vacuum pump through a pipeline.

[0006] Preferably, a rotatable filter screen is also provided on the downstream side of the return line connected to the vertical slag discharge pipe.

[0007] Preferably, the filter is a vertically arranged circular filter structure, whose outer edge cooperates with the circular pipe wall of the return pipeline, and the top of the filter is connected to the rotating handle through a rotating shaft, and the rotating shaft is sealed with the pipe wall of the return pipeline.

[0008] Preferably, an external thread is provided on the upper surface of the rotating shaft, which cooperates with the thread of the locking nut.

[0009] Preferably, the top of the vertical slag discharge pipe is in the shape of a trumpet which is wide at the top and narrow at the bottom.

[0010] Preferably, the outlet position of the low-position flash cooler is higher than the reflux port position of the front reaction chamber of the phosphoric acid reaction tank.

[0011] In addition, the present invention discloses a method for removing impurities by using the above-mentioned device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank, which comprises the following steps: S1. After the vacuum pump is turned on, the tank of the low-level flash cooler is kept in a negative pressure state, and the circulation pump is turned on to pump the slurry in the rear reaction chamber of the phosphoric acid reaction tank into the low-level flash cooler through the slurry pipeline; S2, the slurry after being cooled by the low-level flash cooler returns to the front reaction chamber of the phosphoric acid reaction tank through the reflux pipeline; S3. Open the inlet valve and close the outlet valve. At this time, the fluorosilicate solid impurities in the slurry in the reflux pipeline fall into the vertical slag discharge pipe under the action of gravity when passing through the top of the vertical slag discharge pipe. After a period of time, a certain amount of fluorosilicate solid impurities accumulate in the vertical slag discharge pipe. Then, close the inlet valve and open the outlet valve to discharge the fluorosilicate solid impurities accumulated in the vertical slag discharge pipe.

[0012] S4. Repeat the process of S3 to continuously remove the fluorosilicate solid impurities in the slurry in the phosphoric acid reaction tank without causing any loss of the slurry.

[0013] Furthermore, in S3, when the inlet valve is opened and the outlet valve is closed, the fluorosilicate solid impurities in the slurry in the reflux pipeline are blocked by the filter when passing through the top of the vertical slag discharge pipe, and then fall into the vertical slag discharge pipe under the action of gravity, while the slurry can pass through the mesh of the filter.

[0014] Furthermore, S4 also includes: loosening the locking nut regularly, rotating the rotating shaft by rotating the handle, so that the filter screen flips 180°, so that the slurry can flush the fluorosilicate solid impurities attached to one side of the filter screen; after flushing is completed, tightening the locking nut; and repeating the above process regularly to prevent blockage in the filter screen.

[0015] Beneficial effects of the present invention: 1. The present invention realizes efficient discharge of fluorosilicate solid impurities in the reaction tank, prevents the problem of shortened operation cycle due to accumulation of fluorosilicate solid impurities, improves the overall economic benefits, promotes full contact and reaction between reactants by reducing the obstruction of fluorosilicate solid impurities, improves the slurry reaction efficiency, thereby ensuring the production efficiency and quality of the product, and at the same time reduces the additional load and failure risk faced by the agitator due to the accumulation of fluorosilicate solid impurities, further reducing the cost of equipment overhaul and maintenance.

[0016] 2. The present invention can continuously remove fluorosilicate solid impurities by setting a vertical slag discharge pipe and continuously opening and closing the inlet valve and the outlet valve, and at the same time ensure the normal operation of the reaction system in the phosphoric acid reaction tank.

[0017] 3. After the filter screen is provided in the present invention, the fluorosilicate solid impurities in the slurry in the reflux pipeline are blocked by the filter screen when passing through the top of the vertical slag discharge pipe, and then fall into the vertical slag discharge pipe under the action of gravity, while the slurry can pass through the mesh of the filter screen; this can increase the probability of the fluorosilicate solid impurities entering the vertical slag discharge pipe, thereby improving the efficiency of removing impurities.

[0018] 4. The present invention rotates the rotating shaft by rotating the handle to flip the filter screen 180 degrees, so that the slurry can wash the fluorosilicate solid impurities attached to one side of the filter screen to prevent the filter screen from being blocked. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a schematic structural diagram of a device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank; Figure 2 for Figure 1 Schematic diagram of the installation structure of the internal filter screen in the return pipeline. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] like Figure 1-2 As shown, a device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank comprises a slurry pipeline 2 connected to a rear reaction chamber of the phosphoric acid reaction tank 1 and a reflux pipeline 3 connected to a front reaction chamber of the phosphoric acid reaction tank 1, wherein the slurry pipeline 2 is connected to an inlet of a low-position flash cooler 4, a circulation pump 5 is arranged on the slurry pipeline 2, an outlet of the low-position flash cooler 4 is connected to the reflux pipeline 3, the reflux pipeline 3 is communicated with the top of a vertical slag discharge pipeline 6, an inlet valve 7 is arranged on the upper side of the vertical slag discharge pipeline 6, and an outlet valve 8 is arranged on the lower side.

[0022] Preferably, the low-level flash cooler 4 comprises a tank body 4.1, the bottom of which is provided with an inclined surface 4.2, and the top of the tank body 4.1 is connected to a vacuum pump 4.3 through a pipeline. The vacuum pump 4.3 can keep the tank body 4.1 in a negative pressure state, and in this embodiment, the system pressure is controlled at 60-70 kPa.

[0023] Preferably, a rotatable filter screen 9 is further provided on the downstream side of the return line 3 connected to the vertical slag discharge pipe 6. After the filter screen 9 is provided, when the fluorosilicate solid impurities in the slurry in the return line 3 pass through the top of the vertical slag discharge pipe 6, the fluorosilicate solid impurities are blocked by the filter screen 9, and then fall into the vertical slag discharge pipe 6 under the action of gravity, while the slurry can pass through the mesh of the filter screen 9. In this way, the probability of the fluorosilicate solid impurities entering the vertical slag discharge pipe 6 can be increased, thereby improving the efficiency of removing impurities.

[0024] Preferably, the filter screen 9 is a vertically arranged circular filter screen structure, the outer edge of which cooperates with the circular pipe wall of the return line 3, and the top of the filter screen 9 is connected to the rotating handle 11 through the rotating shaft 10, and the rotating shaft 10 is sealed with the pipe wall of the return line 3. After such a design, the rotating shaft 10 is rotated by rotating the rotating handle 11 to turn the filter screen 9 180°, so that the slurry can wash the fluorosilicate solid impurities attached to one side of the filter screen 9, and prevent the filter screen 9 from being blocked.

[0025] Preferably, the upper surface of the rotating shaft 10 is provided with an external thread, which is threadedly matched with the locking nut 12. After the filter screen 9 is rotated into place, the locking nut 12 can be tightened to lock the rotating shaft 10 with the pipe wall of the return line 3, so that the filter screen 9 will not rotate, thereby fixing the position of the filter screen 9 and preventing the filter screen 9 from rotating due to the impact of the slurry.

[0026] Preferably, the top of the vertical slag discharge pipe 6 is in the shape of a trumpet with a narrow top. With this design, the probability of the fluorosilicate solid impurities contacting the top of the vertical slag discharge pipe 6 is increased, and the fluorosilicate solid impurities in the slurry in the reflux line 3 can be made to fall into the vertical slag discharge pipe 6 under the action of gravity when passing through the top of the vertical slag discharge pipe 6 to the greatest extent.

[0027] Preferably, the outlet position of the low-level flash cooler 4 is higher than the reflux port position of the front reaction chamber of the phosphoric acid reaction tank 1. With this design, a circulation pump does not need to be provided on the reflux pipeline 3, and the slurry cooled by the low-level flash cooler 4 can be returned to the front reaction chamber of the phosphoric acid reaction tank 1 through the reflux pipeline 3 under the action of the liquid level difference.

[0028] Embodiment 1: The present invention discloses a method for removing impurities by using the above-mentioned device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank, which comprises the following steps: After S1 and the vacuum pump 4.3 are turned on, the tank 4.1 of the low-level flash cooler 4 is kept in a negative pressure state, and the circulation pump 5 is turned on to pump the slurry in the rear reaction chamber of the phosphoric acid reaction tank 1 into the low-level flash cooler 4 through the slurry pipeline 2; S2, the slurry after being cooled by the low-level flash cooler 4 is returned to the front reaction chamber of the phosphoric acid reaction tank 1 through the reflux pipeline 3; S3, open the inlet valve 7, and close the outlet valve 8. At this time, the fluorosilicate solid impurities in the slurry in the reflux pipeline 3 fall into the vertical slag discharge pipe 6 under the action of gravity when passing through the top of the vertical slag discharge pipe 6. After a period of time, a certain amount of fluorosilicate solid impurities accumulate in the vertical slag discharge pipe 6 (in this embodiment, the fluorosilicate solid impurities are accumulated in the vertical slag discharge pipe 6 in 8 hours). Then, close the inlet valve 7, and open the outlet valve 8, so as to discharge the fluorosilicate solid impurities accumulated in the vertical slag discharge pipe 6.

[0029] S4. Repeat the process of S3 to continuously remove the fluorosilicate solid impurities in the slurry in the phosphoric acid reaction tank 1 without causing any loss of the slurry.

[0030] Example 2: The other steps are the same as Example 1, except that a filter screen 9 is installed, as follows: In S3, the inlet valve 7 is opened and the outlet valve 8 is closed. At this time, the fluorosilicate solid impurities in the slurry in the reflux line 3 are blocked by the filter screen 9 when passing through the top of the vertical slag discharge pipe 6, and then fall into the vertical slag discharge pipe 6 under the action of gravity, while the slurry can pass through the mesh of the filter screen 9.

[0031] Furthermore, Example 2 also includes a flushing process of the filter screen 9, that is, S4 also includes: regularly loosening the locking nut 12, rotating the rotating shaft 10 by rotating the handle 11, so that the filter screen 9 is flipped 180°, so that the slurry can flush the fluorosilicate solid impurities attached to one side of the filter screen 9; after the flushing is completed, tightening the locking nut 12; and regularly repeating the above process to prevent the filter screen 9 from being blocked.

[0032] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank, comprising a slurry pipeline (2) connected to a rear reaction chamber of the phosphoric acid reaction tank (1) and a reflux pipeline (3) connected to a front reaction chamber of the phosphoric acid reaction tank (1), wherein the slurry pipeline (2) is connected to an inlet of a low-level flash cooler (4), a circulation pump (5) is provided on the slurry pipeline (2), and an outlet of the low-level flash cooler (4) is connected to the reflux pipeline (3), characterized in that: The reflux pipeline (3) is connected to the top of the vertical slag discharge pipeline (6); an inlet valve (7) is provided on the upper side of the vertical slag discharge pipeline (6), and an outlet valve (8) is provided on the lower side.

2. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: The low-level flash cooler (4) comprises a tank body (4.1), the bottom of the tank body (4.1) is provided with an inclined surface (4.2), and the top of the tank body (4.1) is connected to a vacuum pump (4.3) via a pipeline.

3. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: A rotatable filter screen (9) is also provided on the downstream side of the return line (3) which is connected to the vertical slag discharge pipe (6).

4. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: The filter screen (9) is a circular filter screen structure arranged vertically, the outer edge of which cooperates with the circular tube wall of the return pipeline (3), the top of the filter screen (9) is connected to the rotating handle (11) via a rotating shaft (10), and the rotating shaft (10) cooperates with the tube wall of the return pipeline (3) in a sealing manner.

5. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: The upper surface of the rotating shaft (10) is provided with an external thread which is threadably matched with the locking nut (12).

6. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: The top of the vertical slag discharge pipe (6) is in the shape of a trumpet that is wide at the top and narrow at the bottom.

7. The device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 1, characterized in that: The outlet position of the low-position flash cooler (4) is higher than the reflux port position of the front reaction chamber of the phosphoric acid reaction tank (1).

8. A method for removing impurities by using the device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to any one of claims 1 to 7, characterized in that: It includes the following steps: After S1 and the vacuum pump (4.3) are turned on, the tank body (4.1) of the low-level flash cooler (4) is kept in a negative pressure state, and the circulation pump (5) is turned on to pump the slurry in the rear reaction chamber of the phosphoric acid reaction tank (1) into the low-level flash cooler (4) through the slurry pipeline (2); S2, the slurry after being cooled by the low-level flash cooler (4) is returned to the front reaction chamber of the phosphoric acid reaction tank (1) through the reflux pipeline (3); S3, opening the inlet valve (7) and closing the outlet valve (8). At this time, the fluorosilicate solid impurities in the slurry in the reflux pipeline (3) fall into the vertical slag discharge pipeline (6) under the action of gravity when passing through the top of the vertical slag discharge pipeline (6). After a period of time, a certain amount of fluorosilicate solid impurities accumulate in the vertical slag discharge pipeline (6). Then, the inlet valve (7) is closed and the outlet valve (8) is opened, thereby discharging the fluorosilicate solid impurities accumulated in the vertical slag discharge pipeline (6). S4. Repeat the process of S3, thereby continuously removing the fluorosilicate solid impurities in the slurry in the phosphoric acid reaction tank (1) without causing any loss of the slurry.

9. The method for removing impurities by the device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 8, characterized in that: In S3, the inlet valve (7) is opened and the outlet valve (8) is closed. At this time, when the fluorosilicate solid impurities in the slurry in the return line (3) pass through the top of the vertical slag discharge pipe (6), the fluorosilicate solid impurities are blocked by the filter screen (9) and then fall into the vertical slag discharge pipe (6) under the action of gravity, while the slurry can pass through the mesh of the filter screen (9).

10. The method for removing impurities by the device for removing fluorosilicate solid impurities in a phosphoric acid reaction tank according to claim 8, characterized in that: The step S4 further comprises: regularly loosening the locking nut (12), rotating the rotating shaft (10) by rotating the handle (11), and causing the filter screen (9) to flip 180 degrees, so that the slurry can flush out the fluorosilicate solid impurities adhering to one side of the filter screen (9); after flushing is completed, tightening the locking nut (12); and regularly repeating the above process to prevent the filter screen (9) from being blocked.

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