Device for preparing high-quality crude phosphoric acid through groove type multi-stage sedimentation

Abstract

The utility model discloses a device for preparing high-quality crude phosphoric acid through groove type multi-stage sedimentation. A first bottom overflow port A and a first bottom overflow port B are formed in a first clarifying groove; a second top overflow port A and a second top overflow port B are formed in the second clarifying tank; an overflow pipe is communicated between the second top overflow port A and the first bottom overflow port B; a third bottom overflow port A, a third bottom overflow port B, a third top overflow port A and a third top overflow port B are formed in the third clarifying tank, an overflow pipe is communicated between the third bottom overflow port A and the second top overflow port B, and an overflow pipe is communicated between the third top overflow port A and the first bottom overflow port A; a fourth top overflow port and a fourth bottom overflow port are formed in the fourth clarifying tank, an overflow pipe is communicated between the fourth top overflow port and the third bottom overflow port B, and an overflow pipe is communicated between the fourth bottom overflow port and the third top overflow port B. The quality of finished acid is improved, and unqualified products are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of multi-stage sedimentation equipment, in particular to a device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation. Background Technique

[0002] With the increasing depletion of phosphate rock quality and the continuous rise of mining costs, the dihydrate process phosphoric acid production process and the two-stage forced phosphoric acid concentration process are used to produce phosphoric acid with W(P2O5) of 46-48%. For phosphoric acid sedimentation and separation, the method of adding organic polymer flocculants is adopted, with single-stage dosing and two-tank cascade sedimentation process. After clarification, the clarified acid is used for producing DAP, and the separated slag acid is used for producing MAP. At present, phosphate rock resources are widely distributed but in limited supply, resulting in multiple sources and varieties of incoming ore. Some phosphate rocks are directly ground into phosphate rock slurry without pretreatment for the production of wet-process phosphoric acid, and a large amount of impurities are brought into the wet-process phosphoric acid with the phosphate rock, forming a large amount of secondary precipitate salts during the concentration process, which brings difficulties to the sedimentation and separation of phosphoric acid. The existence of secondary precipitate salts makes the solid content in wet-process phosphoric acid remain high, which has a negative impact on the production of DAP and even produces unqualified DAP products.

[0003] In the prior art, most of the concentrated phosphoric acid sedimentation equipment is two-tank high-level cascade sedimentation. When sedimentation difficulties occur or the acid tank leaks, it can be switched to another mode of operation in time, and the solid content in the phosphoric acid after cascade sedimentation can be effectively controlled. If a certain concentrated acid tank fails (such as a hole in the tank or a failure of the tank rake), the concentrated acid cannot achieve cascade sedimentation, seriously affecting the sedimentation of the concentrated acid, resulting in difficulties in product qualification and the entire production organization. Content of the Utility Model

[0004] The purpose of the utility model is to provide a device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation, so as to solve the problems existing in the above-mentioned prior art, effectively extend the sedimentation time of concentrated acid, improve the quality of the finished acid, and reduce the production of unqualified products.

[0005] To achieve the above purpose, the utility model provides the following scheme: The utility model provides a device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation, which includes a first clarification tank, a second clarification tank, a third clarification tank and a fourth clarification tank that are all installed on the same platform and at the same height;

[0006] The first clarification tank is provided with a first bottom overflow port A and a first bottom overflow port B that are both close to the bottom end thereof;

[0007] The second clarification tank is provided with a second top overflow port A and a second top overflow port B that are both close to the top end thereof. The second top overflow port A is located above the first bottom overflow port B and is communicated with the first bottom overflow port B through an overflow pipe;

[0008] The third clarification tank is provided with a third bottom overflow port A and a third bottom overflow port B both near its bottom end, and a third top overflow port A and a third top overflow port B both near its top end. The third bottom overflow port A is located below the second top overflow port B, and an overflow pipe is connected between the third bottom overflow port A and the second top overflow port B. The third top overflow port A is located above the first bottom overflow port A, and an overflow pipe is connected between the third top overflow port A and the first bottom overflow port A;

[0009] The fourth clarification tank is provided with a fourth top overflow port and a fourth bottom overflow port respectively near its top end and bottom end. The fourth top overflow port is located above the third bottom overflow port B, and an overflow pipe is connected between the fourth top overflow port and the third bottom overflow port B. The fourth bottom overflow port is located below the third top overflow port B, and an overflow pipe is connected between the fourth bottom overflow port and the third top overflow port B.

[0010] Preferably, the fourth top overflow port is located at the 95% liquid level of the fourth clarification tank, and the third bottom overflow port B is located at the 25% liquid level of the third clarification tank.

[0011] Preferably, the third top overflow port B is located at the 95% liquid level of the third clarification tank, and the fourth bottom overflow port is located at the 25% liquid level of the fourth clarification tank.

[0012] Preferably, the third top overflow port A is located at the 95% liquid level of the third clarification tank, and the first bottom overflow port A is located at the 25% liquid level of the first clarification tank.

[0013] Preferably, the first bottom overflow port B is located at the 25% liquid level of the first clarification tank, and the second top overflow port A is located at the 95% liquid level of the second overflow tank.

[0014] Preferably, the second top overflow port B is located at the 95% liquid level of the second overflow tank, and the third bottom overflow port A is located at the 25% liquid level of the third overflow tank.

[0015] Preferably, the first clarification tank, the second clarification tank, the third clarification tank and the fourth clarification tank are all provided with a plurality of acid feeding ports arranged at intervals in the vertical direction, and are all equipped with an acid feeding main pipe. The inlet of the acid feeding main pipe is connected to an acid supply mechanism, and the outlets of the acid feeding main pipe are connected in parallel with a plurality of acid feeding branch pipes respectively corresponding to and communicating with each acid feeding port. Connecting valves are provided on both the acid feeding main pipe and the acid feeding branch pipes.

[0016] Preferably, each acid feeding port is respectively located at the 25%, 45%, 65% and 85% liquid levels of each clarification tank.

[0017] Preferably, the axes of the bottom overflow ports all extend horizontally, and the liquid outlet directions of the bottom overflow ports are respectively the tangential directions of the corresponding clarification tanks.

[0018] Preferably, drain valves are provided at the low positions of the overflow pipes.

[0019] The utility model has achieved the following technical effects compared with the prior art:

[0020] The entire device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation can achieve two-tank high-level cascade sedimentation, namely: from the second clarification tank to the first clarification tank, from the second clarification tank to the third clarification tank, from the third clarification tank to the first clarification tank, from the third clarification tank to the fourth clarification tank, from the fourth clarification tank to the third clarification tank; it can achieve three-tank high-level cascade sedimentation, namely: from the second clarification tank to the third clarification tank to the fourth clarification tank, from the second clarification tank to the third clarification tank to the first clarification tank, from the fourth clarification tank to the third clarification tank to the first clarification tank, which can extend the sedimentation time to more than 60 hours and reduce unqualified products; and in case of emergencies (such as acid tank leakage, rake failure, raw material change), production can be effectively organized, reducing the phenomenon of acid quality decline due to insufficient acid tank treatment capacity, and even the occurrence of acid mixing, resulting in frequent acid inventory increases and phosphate fertilizer waiting for acid in production; and it reduces the acid unqualified due to problems with the cascade sedimentation pipeline and reduces the safety risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings based on these drawings without creative efforts.

[0022] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 is a schematic diagram of the connection relationship between the first clarification tank and the third clarification tank of the present invention;

[0024] Wherein, 1 - first clarification tank, 2 - second clarification tank, 3 - third clarification tank, 4 - fourth clarification tank, 5 - first bottom overflow port A, 6 - first bottom overflow port B, 7 - second top overflow port A, 8 - second top overflow port B, 9 - third bottom overflow port A, 10 - third bottom overflow port B, 11 - third top overflow port B, 12 - third top overflow port A, 13 - fourth top overflow port, 14 - fourth bottom overflow port, 15 - acid delivery port. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] Please write the specific implementation mode. The following will combine the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The purpose of the present invention is to provide a device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation, so as to solve the problems existing in the above-mentioned prior art, effectively extend the thick acid sedimentation time, improve the quality of the finished acid, and reduce the generation of unqualified products.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific implementation modes.

[0028] As Figures 1 to 2 shown, this embodiment provides a device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation, including a first clarification tank 1, a second clarification tank 2, a third clarification tank 3 and a fourth clarification tank 4 which are all installed on the same platform and at the same height; preferably, each clarification tank is a vertical circular tank with a conical bottom drain port;

[0029] The first clarification tank 1 is provided with a first bottom overflow port A5 and a first bottom overflow port B6 which are both close to its bottom end;

[0030] The second clarification tank 2 is provided with a second top overflow port A7 and a second top overflow port B8 which are both close to its top end. The second top overflow port A7 is located above the first bottom overflow port B6, and an overflow pipe is connected between the second top overflow port A7 and the first bottom overflow port B6 to realize the cascade sedimentation from the second clarification tank 2 to the first clarification tank 1;

[0031] The third clarification tank 3 is provided with a third bottom overflow port A9 and a third bottom overflow port B10 which are both close to its bottom end, and a third top overflow port A12 and a third top overflow port B11 which are both close to its top end. The third bottom overflow port A9 is located below the second top overflow port B8, and an overflow pipe is connected between the third bottom overflow port A9 and the second top overflow port B8 to realize the cascade sedimentation from the second clarification tank 2 to the third clarification tank 3. The third top overflow port A12 is located above the first bottom overflow port A5, and an overflow pipe is connected between the third top overflow port A12 and the first bottom overflow port A5 to realize the cascade sedimentation from the third clarification tank 3 to the first clarification tank 1;

[0032] The fourth clarification tank 4 is provided with a fourth top overflow port 13 and a fourth bottom overflow port 14 which are respectively arranged near the top and bottom thereof. The fourth top overflow port 13 is located above the third bottom overflow port B10, and an overflow pipe is connected between the fourth top overflow port 13 and the third bottom overflow port B10 to realize the cascade sedimentation from the fourth clarification tank 4 to the third clarification tank 3. The fourth bottom overflow port 14 is located below the third top overflow port B11, and an overflow pipe is connected between the fourth bottom overflow port 14 and the third top overflow port B11 to realize the cascade sedimentation from the third clarification tank 3 to the fourth clarification tank 4. Preferably, each overflow pipe is of an inclined tubular structure.

[0033] The entire device for preparing high-quality crude phosphoric acid by tank-type multi-stage sedimentation can achieve two-tank high-level cascade sedimentation, namely: from the second clarification tank 2 to the first clarification tank 1, from the second clarification tank 2 to the third clarification tank 3, from the third clarification tank 3 to the first clarification tank 1, from the third clarification tank 3 to the fourth clarification tank 4, from the fourth clarification tank 4 to the third clarification tank 3; it can achieve three-tank high-level cascade sedimentation, namely: from the second clarification tank 2 to the third clarification tank 3 to the fourth clarification tank 4, from the second clarification tank 2 to the third clarification tank 3 to the first clarification tank 1, from the fourth clarification tank 4 to the third clarification tank 3 to the first clarification tank 1, which can extend the sedimentation time to more than 60h, reduce unqualified products; and in case of emergencies (such as: acid tank leakage, rake failure, raw material change), production can be effectively organized, reducing the phenomenon of acid quality decline due to insufficient acid tank treatment capacity, and even the occurrence of acid mixing, resulting in frequent acid stockpiling in phosphoric acid and waiting for acid in phosphate fertilizer production; and reducing acid unqualified caused by problems in cascade sedimentation pipelines and reducing safety risks.

[0034] According to the two-tank high-level cascade sedimentation and three-tank high-level cascade sedimentation, during the acid sedimentation process, each clarification tank passed through in sequence can be divided into a primary clarification tank, a secondary clarification tank and a tertiary clarification tank. Furthermore, the entire sedimentation process is as follows: The acid from the second-stage concentration is mixed with the sedimentation agent and then enters the primary clarification tank for flocculation sedimentation. Large particles in the phosphoric acid and large flocs formed by the flocculation of the flocculant gradually sink to the bottom of the clarification tank and are enriched. Under the action of the rotating rake, they are gathered at the bottom of the clarification tank and discharged for the production of MAP after being discharged. The clear liquid overflows from the top overflow port, is mixed with the flocculant, and then enters the lower part of the secondary clarification tank through the overflow pipe to continue flocculation sedimentation. The acid residue is discharged from the bottom of the clarification tank and enters the bottom of the primary clarification tank. The clear liquid overflows from the top overflow port and enters the lower part of the tertiary clarification tank through the overflow pipe for further separation. Among them, a small amount of the remaining flocculant in the phosphoric acid continues to play a role, pulling the suspended particles in the phosphoric acid to form large flocs for sedimentation. The separated acid residue is taken out from the bottom of the tertiary clarification tank for the production of MAP, and the clear liquid is taken out from the high-level overflow port for the production of DAP. After multi-stage sedimentation, the solid content in the phosphoric acid can be effectively controlled within 1.5%. After multi-stage sedimentation of the second-stage phosphoric acid, the solid content control level far exceeds the acid requirement for DAP, and the quality of the clarified acid is excessive. During operation, matching the multi-stage sedimentation treatment capacity and adding low-grade ore to the phosphate rock for wet-process phosphoric acid production is an important manifestation of the benefit of multi-stage sedimentation for phosphoric acid sedimentation.

[0035] As a preferred embodiment of the present utility model, the fourth top overflow port 13 is located at the 495% liquid level of the fourth clarification tank 4, the third bottom overflow port B10 is located at the 325% liquid level of the third clarification tank 3, the third top overflow port B11 is located at the 395% liquid level of the third clarification tank 3, and the fourth bottom overflow port 14 is located at the 425% liquid level of the fourth clarification tank 4. The third top overflow port A12 is located at the 395% liquid level of the third clarification tank 3, the first bottom overflow port A5 is located at the 125% liquid level of the first clarification tank 1, the first bottom overflow port B6 is located at the 125% liquid level of the first clarification tank 1, the second top overflow port A7 is located at the 95% liquid level of the second overflow tank 9, the second top overflow port B8 is located at the 95% liquid level of the second overflow tank 9, and the third bottom overflow port A9 is located at the 25% liquid level of the third overflow tank 2. All of them can achieve high-level cascade sedimentation, three-tank high-level cascade sedimentation, and fully extend the sedimentation time.

[0036] Furthermore, the first clarification tank 1, the second clarification tank 2, the third clarification tank 3, and the fourth clarification tank 4 are all provided with a plurality of acid feeding ports 15 arranged at intervals in the vertical direction. Preferably, the acid feeding ports 15 are respectively located at the 25%, 45%, 65%, and 85% liquid levels of each clarification tank to achieve acid feeding at each liquid level. And each clarification tank is equipped with an acid feeding main pipe. The inlet of the acid feeding main pipe is connected to an acid supply mechanism. The outlet of the acid feeding main pipe is connected in parallel with a plurality of acid feeding branch pipes respectively corresponding to and communicating with the acid feeding ports 15. Connecting valves are provided on both the acid feeding main pipe and the acid feeding branch pipes. Preferably, the acid supply mechanism includes a mixer located above the second clarification tank 2. The outlet end of the mixer is connected in parallel with each acid feeding main pipe. Specifically, the outlet end of the mixer is connected to an acid feeding pipeline, and a plurality of outlets communicating with each acid feeding main pipe are opened on the acid feeding pipeline. And a transfer pump is provided on the acid feeding pipeline.

[0037] Preferably, the axes of each bottom overflow port extend horizontally, and the liquid discharging directions of each bottom overflow port are the tangential directions of the corresponding clarification tank. After the material enters along the tangent, a swirling state can be formed in the next-level clarification tank, making the mixing in the next-level clarification more uniform.

[0038] Furthermore, sewage discharge valves are opened at the low positions of each overflow pipe to be able to discharge the impurities settled in the clarification tank. Preferably, the sewage discharge valves are opened at the positions where the overflow pipes are connected to the corresponding bottom overflow ports to ensure the sewage discharge effect.

[0039] Adaptations made according to actual needs are all within the protection scope of the present utility model.

[0040] It should be noted that for those skilled in the art, it is obvious that the present utility model is not limited to the details of the above exemplary embodiments, and the present utility model can be implemented in other specific forms without departing from the spirit or basic characteristics of the present utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present utility model is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present utility model. Any reference signs in the claims should not be construed as limiting the claims involved.

[0041] Specific examples are used in the present utility model to elaborate on the principles and implementation manners of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present utility model.

Claims

1. An apparatus for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation, characterized in that, Including a first clarification tank, a second clarification tank, a third clarification tank, and a fourth clarification tank, all of which are installed on the same platform and at the same height; The first clarification tank is provided with a first bottom overflow port A and a first bottom overflow port B, both of which are close to the bottom end thereof; The second clarification tank is provided with a second top overflow port A and a second top overflow port B, both of which are close to the top end thereof. The second top overflow port A is located above the first bottom overflow port B, and an overflow pipe is connected between the second top overflow port A and the first bottom overflow port B; The third clarification tank is provided with a third bottom overflow port A and a third bottom overflow port B, both of which are close to the bottom end thereof, and a third top overflow port A and a third top overflow port B, both of which are close to the top end thereof. The third bottom overflow port A is located below the second top overflow port B, and an overflow pipe is connected between the third bottom overflow port A and the second top overflow port B. The third top overflow port A is located above the first bottom overflow port A, and an overflow pipe is connected between the third top overflow port A and the first bottom overflow port A; The fourth clarification tank is provided with a fourth top overflow port and a fourth bottom overflow port, which are respectively close to the top end and the bottom end thereof. The fourth top overflow port is located above the third bottom overflow port B, and an overflow pipe is connected between the fourth top overflow port and the third bottom overflow port B. The fourth bottom overflow port is located below the third top overflow port B, and an overflow pipe is connected between the fourth bottom overflow port and the third top overflow port B.

2. The apparatus for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 1, wherein, The fourth top overflow port is located at the 95% liquid level of the fourth clarification tank, and the third bottom overflow port B is located at the 25% liquid level of the third clarification tank.

3. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 2, characterized in that, The third top overflow port B is located at the 95% liquid level of the third clarification tank, and the fourth bottom overflow port is located at the 25% liquid level of the fourth clarification tank.

4. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 3, characterized in that, The third top overflow port A is located at the 95% liquid level of the third clarification tank, and the first bottom overflow port A is located at the 25% liquid level of the first clarification tank.

5. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 4, wherein The first bottom overflow port B is located at the 25% liquid level of the first clarification tank, and the second top overflow port A is located at the 95% liquid level of the second clarification tank.

6. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 5, characterized in that, The second top overflow port B is located at the 95% liquid level of the second clarification tank, and the third bottom overflow port A is located at the 25% liquid level of the third clarification tank.

7. The apparatus for preparing high-quality crude phosphoric acid by trough type multi-stage sedimentation according to any one of claims 2 to 6, characterized in that, The first clarification tank, the second clarification tank, the third clarification tank, and the fourth clarification tank are all provided with a plurality of acid feeding ports arranged at intervals in the vertical direction, and are all equipped with an acid feeding main pipe. The inlet of the acid feeding main pipe is connected to an acid supply mechanism, and the outlets of the acid feeding main pipe are connected in parallel with a plurality of acid feeding branch pipes respectively corresponding to and communicating with the respective acid feeding ports. Connecting valves are provided on both the acid feeding main pipe and the acid feeding branch pipes.

8. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 7, characterized in that, Each of the acid feeding ports is respectively located at the 25%, 45%, 65%, and 85% liquid levels of each clarification tank.

9. The apparatus for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 8, wherein, The axes of each bottom overflow port extend horizontally, and the liquid outlet directions of each bottom overflow port are respectively the tangential directions of the corresponding clarification tank.

10. The device for preparing high-quality crude phosphoric acid by trough-type multi-stage sedimentation according to claim 9, characterized in that, A sewage discharge valve is provided at the low position of each of the overflow pipes.

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