Extraction and filtration system for wet-process phosphoric acid production

Abstract

The utility model provides an extraction and filtration system for wet-process phosphoric acid production, relates to the technical field of phosphoric acid production, and solves the technical problem that small particles in a liquid phase are carried by flushing water of the conventional wet-process phosphoric acid production and filtration system and are gradually accumulated to easily cause blockage. The rotary table filter comprises a filtering area used for filtering phosphoric acid extracted by an extraction tank, a first washing area used for primarily washing filter residues, a second washing area used for secondarily washing the filter residues, a residue removing area used for removing the filter residues and a disc flushing area used for flushing a disc surface, and the first washing area is communicated with a dosing hopper used for adding a scale inhibitor; the dosing hopper is communicated with the extraction tank. The scaling speed of the system is further reduced, the capacity of the filtering system is effectively improved, and the cleaning labor intensity of workers and the labor cost are reduced; and the second washing water is reused for washing or used for flushing the disc, so that the consumption of the washing water is reduced, and the accumulated fine filter residues can be accumulated and are settled and discharged through the collecting hopper, so that the structural speed in the system is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of phosphoric acid production, in particular to an extraction and filtration system for wet-process phosphoric acid production. Background Art

[0002] The wet phosphoric acid production process is the main way to supply phosphoric acid at present. In the process of wet phosphoric acid production, it is often necessary to filter the phosphate slurry to remove solid matter before it can be obtained. The logistics medium of wet phosphoric acid production mainly exists in liquid and solid phases. Since the phosphate ore used in production varies with geological formation conditions and locations, the impurity content in the phosphate ore is complex and diverse, which brings serious volatility, complexity and difficulty to the production of wet phosphoric acid. Especially when the phosphate ore contains high sodium and potassium salts, the temperature change of the production reaction will cause salt precipitation scaling, precipitation scaling and sedimentation blockage, which seriously hinders the normal production.

[0003] The extraction and filtration system is a key equipment that affects the production of dilute phosphoric acid. During the production process, the slurry sent from the extraction reaction tank is separated into solid and liquid by a filter to obtain dilute phosphoric acid semi-products. As the quality of phosphate ore decreases, the scaling and clogging rate of the medium pipeline and equipment is accelerated, the cleaning frequency of the device increases, the system operation cycle is shorter, the device operation rate decreases, and the production cannot continue. It can only be stopped for cleaning, which seriously affects the continuous and normal operation of production, and then affects the production of extracted dilute phosphoric acid.

[0004] Therefore, a filter cloth washing water filtration system for wet phosphoric acid production proposed in the patent with publication number CN103520993A adopts a rotary filter and cooperates with a filter cloth washing punch to extend the operation cycle of the rotary filter and shorten the downtime. However, when the existing rotary filter is in use, the washing water carries tiny particles in the liquid phase and gradually accumulates. Although the reused washing water is filtered through the basket filter, it is still easy to clog in the solid-liquid separator after washing the rotary filter, and the filter residue is difficult to discharge. Utility Model Content

[0005] The utility model aims to provide a wet-process phosphoric acid production extraction and filtration system to solve the technical problem that the washing water of the existing wet-process phosphoric acid production filtration system carries tiny particles in the liquid phase and gradually accumulates to easily cause blockage.

[0006] The embodiments of the present invention are implemented by the following technical solutions:

[0007] A wet-process phosphoric acid production extraction and filtration system comprises a rotary filter for filtering, an extraction tank for extracting phosphoric acid, a product intermediate tank for collecting phosphoric acid and a collection bucket for collecting flushing water. The rotary filter comprises a filtration area for filtering the phosphoric acid extracted by the extraction tank, a first washing area for preliminarily washing filter residues, a second washing area for secondary washing of filter residues, a slag removal area for removing filter residues and a flushing area for flushing the disk surface. The first washing area is connected to a dosing hopper for adding a scale inhibitor, and the dosing hopper is connected to the extraction tank.

[0008] Preferably, the rotary filter is further provided with a first gas-liquid separator and a second gas-liquid separator for separating gas in the washing water, and the first gas-liquid separator and the second gas-liquid separator are connected to the first washing zone and the second washing zone respectively.

[0009] Preferably, it also includes a condenser and a vacuum pump for accelerating the extraction of washing water, and a first settling tank and a second settling tank for respectively causing washing water sedimentation in the first washing area and the second washing area; the second settling tank is connected to the collecting hopper, and the first settling tank is connected to the dosing hopper.

[0010] Preferably, the condenser is connected to the first sedimentation tank and the first gas-liquid separator, and is connected to the second sedimentation tank and the second gas-liquid separator.

[0011] Preferably, the second washing zone is connected to the collecting bucket, and the collecting bucket is provided with a flushing water pump for returning the upper clear liquid to the flushing zone for flushing. The collecting bucket is also connected to the first washing zone and the second washing zone for recycling washing water.

[0012] Preferably, it also includes a slag trough for collecting slag discharged from the slag removal area.

[0013] Preferably, the dosing hopper is provided with a feed port for adding antiscalant, a tank body for settling washing water, and a slag discharge port for discharging slag.

[0014] By adopting this technical solution, a scale inhibitor can be added to the phosphoric acid before entering the extraction tank through the dosing hopper. After sedimentation, the clear liquid is sent to the extraction tank for extraction, and then filtered to obtain phosphoric acid, which further reduces the scaling rate of the system, effectively improves the capacity of the filtration system, and reduces the labor intensity and labor cost of workers' cleaning.

[0015] The filter residue and phosphogypsum are fully washed through the first washing zone and the second washing zone of the rotary filter. The first washing water is separated by the gas-liquid separator condenser, enters the sedimentation tank for sedimentation and then goes to extraction; the second washing water is also separated by the gas-liquid separator condenser, enters the sedimentation tank for sedimentation and then goes to the collection bucket, and then reused for washing or for flushing the plate, saving the consumption of washing water, and can accumulate the accumulated fine filter residue and discharge it through the collection bucket, thereby reducing the structural speed in the system.

[0016] The technical solution of the embodiment of the utility model has at least the following advantages and beneficial effects:

[0017] 1. The utility model further reduces the scaling rate of the system, effectively improves the capacity of the filtration system, and reduces the labor intensity and labor costs of workers in cleaning;

[0018] 2. The second washing water of the utility model is reused for washing or for flushing the plate, which saves the consumption of washing water, and can accumulate the accumulated fine filter residues and discharge them through the collection bucket to reduce the structural speed in the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of the wet-process phosphoric acid production extraction and filtration system provided in Example 1 of the utility model;

[0021] Icons: 1. Rotary filter; 11. Filtration area; 12. First washing area; 13. Second washing area; 14. Slag removal area; 15. Flushing tray area; 21. First gas-liquid separator; 22. Second gas-liquid separator; 3. Condenser; 31. Vacuum pump; 4. Dosing hopper; 51. First sedimentation tank; 52. Second sedimentation tank; 6. Product intermediate tank; 7. Slag tank; 8. Collection hopper; 81. Flushing tray water pump; 9. Extraction tank. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Generally, the components of the embodiments of the utility model described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the present invention to be protected, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the present invention, it should be noted that if the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the accompanying drawings, or is the orientation or position relationship in which the product of the application is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0026] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] Example 1

[0028] A wet-process phosphoric acid production extraction and filtration system comprises a rotary filter 1 for filtering, an extraction tank 9 for extracting phosphoric acid, a product intermediate tank 6 for collecting phosphoric acid and a collecting bucket 8 for collecting flushing water. The rotary filter 1 comprises a filtration area 11 for filtering the phosphoric acid extracted by the extraction tank 9, a first washing area 12 for preliminarily washing the filter residue, a second washing area 13 for secondary washing the filter residue, a slag removal area 14 for removing the filter residue and a flushing area 15 for flushing the disk surface. The first washing area 12 is connected to a dosing hopper 4 for adding a scale inhibitor, and the dosing hopper 4 is connected to the extraction tank 9.

[0029] In this embodiment, the rotary filter 1 is further provided with a first gas-liquid separator 21 and a second gas-liquid separator 22 for separating gas in washing water. The first gas-liquid separator 21 and the second gas-liquid separator 22 are connected to the first washing zone 12 and the second washing zone 13 respectively.

[0030] In this embodiment, it also includes a condenser 3 and a vacuum pump 31 for accelerating the extraction of washing water, and a first sedimentation tank 51 and a second sedimentation tank 52 for respectively causing washing water sedimentation in the first washing area 12 and the second washing area 13; the second sedimentation tank 52 is connected to the collecting hopper 8, and the first sedimentation tank 51 is connected to the dosing hopper 4.

[0031] In this embodiment, the condenser 3 is connected to the first sedimentation tank 51 and the first gas-liquid separator 21 , and is connected to the second sedimentation tank 52 and the second gas-liquid separator 22 .

[0032] In this embodiment, the second washing zone 13 is connected to the collecting bucket 8, and the collecting bucket 8 is provided with a flushing plate water pump 81 for returning the upper clear liquid to the flushing plate zone 15 for flushing. The collecting bucket 8 is also connected to the first washing zone 12 and the second washing zone 13 for recycling washing water.

[0033] In this embodiment, a slag trough 7 for collecting slag discharged from the slag removal area 14 is also included.

[0034] In this embodiment, the dosing hopper 4 is provided with a feed port for adding antiscalant, a tank body for settling washing water, and a slag discharge port for discharging slag.

[0035] Working principle and usage:

[0036] The scale inhibitor can be added to the phosphoric acid before entering the extraction tank 9 through the dosing hopper 4. After sedimentation, the clear liquid is sent to the extraction tank 9 for extraction, and then filtered to obtain phosphoric acid, which further reduces the scaling rate of the system, effectively improves the capacity of the filtration system, and reduces the labor intensity and labor cost of workers in cleaning;

[0037] The filter residue and phosphogypsum are fully washed by the first washing zone 12 and the second washing zone 13 of the turntable filter 1. The first washing water is separated by the gas-liquid separator condenser 3, enters the sedimentation tank for sedimentation and then goes to extraction; the second washing water is also separated by the gas-liquid separator condenser 3, enters the sedimentation tank for sedimentation and then goes to the collecting bucket 8, and then reused for washing or for flushing the plate, saving the consumption of washing water, and can accumulate the accumulated fine filter residue and discharge it through the collecting bucket 8, thereby reducing the structural speed in the system.

[0038] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may be subject to various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wet-process phosphoric acid production extraction and filtration system, comprising a rotary filter (1) for filtering, an extraction tank (9) for extracting phosphoric acid, a product intermediate tank (6) for collecting phosphoric acid, and a collection bucket (8) for collecting flushing water, characterized in that: The rotary filter (1) comprises a filtering zone (11) for filtering phosphoric acid extracted from the extraction tank (9), a first washing zone (12) for preliminary washing of filter residues, a second washing zone (13) for secondary washing of filter residues, a slag removal zone (14) for removing filter residues, and a disk flushing zone (15) for flushing the disk surface, wherein the first washing zone (12) is connected to a dosing hopper (4) for adding a scale inhibitor, and the dosing hopper (4) is connected to the extraction tank (9).

2. The wet process phosphoric acid production extraction and filtration system according to claim 1, characterized in that: The rotary filter (1) is also provided with a first gas-liquid separator (21) and a second gas-liquid separator (22) for separating gas in washing water; the first gas-liquid separator (21) and the second gas-liquid separator (22) are respectively connected to the first washing area (12) and the second washing area (13).

3. A wet process phosphoric acid production extraction and filtration system according to claim 2, characterized in that: It also includes a condenser (3) and a vacuum pump (31) for accelerating the extraction of washing water, and a first sedimentation tank (51) and a second sedimentation tank (52) for respectively causing the washing water to settle in the first washing zone (12) and the second washing zone (13); the second sedimentation tank (52) is connected to the collecting hopper (8), and the first sedimentation tank (51) is connected to the dosing hopper (4).

4. A wet-process phosphoric acid production extraction and filtration system according to claim 3, characterized in that: The condenser (3) is connected to the first sedimentation tank (51) and the first gas-liquid separator (21), and is connected to the second sedimentation tank (52) and the second gas-liquid separator (22).

5. A wet process phosphoric acid production extraction and filtration system according to any one of claims 1 to 4, characterized in that: The second washing zone (13) is connected to the collecting bucket (8), and the collecting bucket (8) is provided with a flushing water pump (81) for returning the upper clear liquid to the flushing zone (15) for flushing. The collecting bucket (8) is also connected to the first washing zone (12) and the second washing zone (13) for recycling washing water.

6. A wet process phosphoric acid production extraction and filtration system according to any one of claims 1 to 4, characterized in that: It also includes a slag trough (7) for collecting slag discharged from the slag removal area (14).

7. An extraction and filtration system for wet-process phosphoric acid production according to any one of claims 1 to 4, characterized in that: The dosing hopper (4) is provided with a feed port for adding a scale inhibitor, a tank body for settling washing water, and a slag discharge port for discharging slag.

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