Phosphogypsum dehydration device

Abstract

The invention discloses a dehydration device for phosphogypsum, belonging to the technical field of phosphorus chemical industry. It includes a vacuum filtration mechanism, a gravity concentration mechanism, a vacuum pressing mechanism and a filter belt. The vacuum filtration mechanism includes a main frame, a first active roller, a first driven roller and a driving belt. The gravity concentration mechanism includes a gravity frame, a front driven roller, a rear driven roller, a gravity belt and a gravity belt cleaning structure. The vacuum pressing mechanism includes a pressing frame, an upper driving roller, a lower driving roller, a second driven roller, a pressing belt, a pressing belt cleaning structure and a filter belt cleaning structure; the gravity belt cleaning structure includes a brush roller, and the rear driven roller is an air blowing roller; the pressing belt cleaning structure includes a second scraper, a second water tank and two second spray pipes; the filter belt cleaning structure includes a first scraper, a first water tank, a first air blowing roller and two first spray pipes; the first air blowing roller and the rear driven roller are connected to a compressed air supply device through a pipeline. This patent adopts different cleaning methods for the gravity belt, the filter belt and the pressing belt.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphorus chemical industry, and in particular relates to a dehydration device for phosphogypsum. Background Art

[0002] Phosphogypsum is an industrial by-product gypsum produced when producing high-concentration phosphate compound fertilizers. Its main component is calcium sulfate dihydrate (CaSO4·2H2O). The production of 1 ton of phosphoric acid (based on 100% P2O5) produces 4.8-5.0 tons of phosphogypsum. The solid waste pressure is very huge, so phosphogypsum needs to be treated in a timely manner.

[0003] In the prior art, lime can be used to neutralize and clean phosphogypsum. A belt filter is used in the treatment of phosphogypsum. For example, patent application number CN202210980036.5 discloses a comprehensive treatment method for phosphogypsum, which includes: (1) collecting phosphogypsum and concentrating it through a concentrator, the clear liquid obtained through concentrating is used as phosphogypsum return water, and the mud obtained through concentrating is sent to a primary belt filter for treatment; (2) filtering the slurry obtained in step (1) with a primary belt filter, wherein the filtrate is used as phosphogypsum return water, and the filter residue is sent to step (3) for treatment; (3) re-slurrying the filter residue, re-slurry water and quicklime or lime milk obtained in step (2) to obtain phosphogypsum slurry, wherein the re-slurry water includes filter press filtrate and secondary filter washing drainage; (4) A secondary belt filter is used to filter the phosphogypsum slurry obtained in step (3); the filtrate, first wash drainage, second wash drainage and third wash drainage of the secondary belt filter are combined as the secondary filter drainage, and the filter residue is dry gypsum.

[0004] For example, the patent with application number CN202221398159.X discloses a vacuum belt filter, comprising: A vacuum filtration mechanism, the vacuum filtration mechanism includes a main frame, a main drive roller and a driven roller connected to the main frame, and a drive belt, the outer surface of the drive belt is covered with a filter belt, the vacuum filtration mechanism also includes a vacuum filtration component connected to the main frame, the vacuum filtration component is connected to the drive belt, and is used to vacuum deliquate the slurry on the filter belt.

[0005] The gravity thickening mechanism includes a gravity frame connected to the upper end of the main frame, a feeder connected to the upper end of the gravity frame, a gravity drive roller and a circularly rotating gravity belt, the lower end of the gravity belt cooperates with the upper end of the filter belt to extrude the slurry. And a vacuum pressing mechanism, the vacuum pressing mechanism includes a pressing frame connected to the side end of the main frame, a pressing rotating roller, a vacuum pressing roller and a pressing belt connected to the pressing frame, the pressing belt is wound in an S shape between the pressing rotating roller and the vacuum pressing roller, and the filter belt is wound in an S shape between the pressing rotating roller and the vacuum pressing roller.

[0006] Phosphogypsum contains a lot of impurities. In order to ensure the filtering effect, the filter belt, gravity belt and press belt need to be cleaned in time to ensure the cleaning effect. Summary of the invention

[0007] In order to solve the above problems, the embodiment of the present invention provides a dehydration device for phosphogypsum. This patent adopts different cleaning methods for the gravity belt, the filter belt and the press belt. The technical solution is as follows: The embodiment of the present invention provides a dehydration device for phosphogypsum, which includes a vacuum filtration mechanism 1, a gravity concentration mechanism 2, a vacuum pressing mechanism 3 and a filter belt 4, wherein the vacuum pressing mechanism 3 is located directly behind the gravity concentration mechanism 2, the vacuum filtration mechanism 1 includes a main frame 11, a first active roller 12, a first driven roller 13 and a driving belt 14, the gravity concentration mechanism 2 includes a gravity frame 21, a front driven roller 22, a rear driven roller 23 and a gravity belt 24, the vacuum pressing mechanism 3 includes a pressing frame 31, an upper driving roller 32, a lower driving roller 33, a second driven roller 34 and a pressing belt 35 ; The filter belt 4 is arranged in the front-to-back direction, the front part of which passes between the drive belt 14 and the gravity belt 24, and the rear part of which forms a pressing structure with the pressing belt 35; the upper drive roller 32 and the lower drive roller 33 are arranged side by side up and down, the pressing belt 35 bypasses the lower side of the upper drive roller 32 backward and upward, and the filter belt 4 bypasses the upper side of the lower drive roller 33 backward and downward; the gravity concentration mechanism 2 also includes a gravity belt cleaning structure 25, and the vacuum pressing mechanism 3 also includes a pressing belt cleaning structure 36 and a filter belt cleaning structure 37; the gravity belt cleaning structure 25 is located at the rear of the gravity frame 21 and includes a brush roller 5 1, the rear driven roller 23 is a blowing roller, the brush roller 51 is located directly behind the rear driven roller 23 and is against the gravity belt 24; the pressing belt cleaning structure 36 includes a second scraper 61, a second water tank 62 and two second spray pipes 63 directly above the second water tank 62; the second scraper 61 is located directly behind the upper drive roller 32 and is against the pressing belt 35, the second water tank 62 is located at the front upper part of the pressing frame 31, and the two second spray pipes 63 spray toward both sides of the pressing belt 35 respectively; the filter belt cleaning structure 37 includes a first scraper 71, a first water tank 72, a first Two first spray pipes 74 are located directly above the blowing roller 73 and the first water trough 72; the first scraper 71 is located directly behind the lower drive roller 33 and is against the filter belt 4, the first water trough 72 is located in the front and lower part of the lower drive roller 33, the lower part of the first blowing roller 73 is located in the first water trough 72, the filter belt 4 passes around the lower side of the first blowing roller 73 and is immersed in the cleaning liquid in the first water trough 72, and the two first spray pipes 74 spray toward both sides of the filter belt 4 respectively; the first blowing roller 73 and the rear driven roller 23 are evenly provided with blowing holes on their circumferential surfaces and are connected to the compressed air supply device through pipelines.

[0008] Among them, the first spray pipe 74 and the second spray pipe 63 in the embodiment of the present invention are both arranged in the left and right directions, and a plurality of spray holes or nozzles are arranged side by side on the left and right sides, which are connected to the washing liquid supply device through pipelines; the two second spray pipes 63 are respectively located in front and rear of the pressing belt 35; one first spray pipe 74 is located behind the first blowing roller 73, which is located above the filter belt 4, and it sprays downward; the other first spray pipe 74 is located in front of the first blowing roller 73, which is located in front of the filter belt 4, and it sprays backward.

[0009] Furthermore, in the embodiment of the present invention, the water inlet of the first water tank 72 is connected to the washing liquid supply device through a pipeline, and the drain outlets of the first water tank 72 and the second water tank 62 are connected to the wastewater collection device through pipelines.

[0010] Furthermore, the first water trough 72 in the embodiment of the present invention is arranged at the lower rear part of the press frame 31, and a redirecting roller 75 is provided on the press frame 31 and located in front and above the first blowing roller 73; the filter belt 4 bypasses the rear side of the lower drive roller 33, obliquely moves forward and downward to the first blowing roller 73, bypasses the lower side of the first blowing roller 73, and then obliquely moves forward and upward to the upper side of the redirecting roller 75.

[0011] Furthermore, the second water trough 62 in the embodiment of the present invention is located at the upper rear part of the gravity belt cleaning structure 25, and a traction roller 64 is provided on the front side of the pressing frame 31 and below the second driven roller 34, and the traction roller 64 is located directly above the second water trough 62; the pressing belt 35 is wound downward from the front side of the second driven roller 34, bypasses the front side of the traction roller 64 and winds obliquely downward and rearward; the second spray pipe 63 is located between the second driven roller 34 and the traction roller 64.

[0012] Among them, the first scraper 71 and the second scraper 61 in the embodiment of the present invention are both arranged in the left and right directions; the first scraper 71 is located directly behind the lower part of the lower drive roller 33, and is arranged obliquely backward from bottom to top, and its upper end contacts the rear side of the filter belt 4; the second scraper 61 is located directly behind the upper part of the upper drive roller 32, and is arranged obliquely backward from top to bottom, and its lower end contacts the rear side of the pressing belt 35.

[0013] Furthermore, the first scraper 71 in the embodiment of the present invention is adjustably disposed at the middle of the first adjustment frame 76, and the second scraper 61 is adjustably disposed at the middle of the second adjustment frame 65; a fixed bracket 38 is provided in the vertical direction directly behind the press frame 31; the first adjustment frame 76 and the second adjustment frame 65 are both arranged in the front-to-back direction, their front ends are hinged to the rear side of the press frame 31, and their rear ends are adjustably disposed on the fixed bracket 38.

[0014] Furthermore, the brush roller 51 in the embodiment of the present invention is located directly behind the rear driven roller 23 and is arranged at the lower end of the swing arm 52; the swing arm 52 is arranged obliquely forward from top to bottom, and its middle part is hinged to the rear end of the gravity frame 21, and a tension spring 53 is provided between the rear side of its upper end and the gravity frame 21.

[0015] The air supply pressure of the compressed air supply device in the embodiment of the present invention is 0.5-0.7 Mpa; the water supply pressure of the first spray pipe 74 and the second spray pipe 63 is 0.5-0.6 Mpa.

[0016] Among them, the upper drive roller 32 and the lower drive roller 33 in the embodiment of the present invention are synchronously driven by the gears thereon, the front driven roller 22 can be adjusted forward and backward and is arranged at the front of the gravity frame 21, the second driven roller 34 can be adjusted forward and backward and is arranged at the front of the pressing frame 31, and the first driven roller 13 can be adjusted forward and backward and is arranged at the front of the main frame 11. The beneficial effects brought about by the technical solution provided by the embodiment of the present invention are as follows: this patent adopts different cleaning methods for the gravity belt, filter belt and press belt. Specifically, the gravity belt is the cleanest and has a small space at the rear. The gravity belt cleaning structure will not introduce water and let water drip onto the material; the filter belt is the dirtiest, and the filter belt cleaning structure is cleaned later. The filter belt has a long conveying distance and is located at the bottom, which is convenient for water to drain and drip; it has been dehydrated in the front and is cleaner than the filter belt. The processing method is simpler than that of the filter belt. The press belt cleaning structure adopts front cleaning, and is not afraid of introducing water. The water is squeezed dry and no water drips. This patent not only has a simple cleaning method and can ensure the dehydration effect, but also can ensure the consistency of the cleaning cycle of the gravity belt, filter belt and press belt. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a dehydration device for phosphogypsum provided in an embodiment of the present invention; Figure 2 yes Figure 1 A partial enlarged view of .

[0018] In the figure: 1 vacuum filtration mechanism, 2 gravity concentration mechanism, 3 vacuum pressing mechanism, 4 filter belt; 11 main machine frame, 12 first active roller, 13 first driven roller, 14 driving belt; 21 gravity frame, 22 front driven roller, 23 rear driven roller, 24 gravity belt, 25 gravity belt cleaning structure; 31 press frame, 32 upper drive roller, 33 lower drive roller, 34 second driven roller, 35 press belt, 36 press belt cleaning structure, 37 filter belt cleaning structure, 38 fixed bracket; 51 brush roller, 52 swing arm, 53 tension spring; 61 second scraper, 62 second water tank, 63 second spray pipe, 64 traction roller, 65 second adjustment frame; 71 first scraper, 72 first water tank, 73 first blowing roller, 74 first spray pipe, 75 redirecting roller, 76 first adjustment frame. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0020] Example 1 See also Figure 1-2Embodiment 1 provides a dehydration device for phosphogypsum, which includes a vacuum filtration mechanism 1, a gravity concentration mechanism 2, a vacuum pressing mechanism 3, and a filter belt 4. The vacuum filtration mechanism 1 and the gravity concentration mechanism 2 can reduce the water content of phosphogypsum to 18-20%, and the vacuum pressing mechanism 3 can reduce the water content of phosphogypsum to about 15%. The vacuum filtration mechanism 1, the gravity concentration mechanism 2, the vacuum pressing mechanism 3, and the filter belt 4 are all arranged in the front-to-back direction, and the vacuum pressing mechanism 3 is located directly behind the gravity concentration mechanism 2.

[0021] The vacuum filtration mechanism 1 includes a main frame 11, a first active roller 12, a first driven roller 13, a driving belt 14, etc. The main frame 11 is arranged in the front-to-back direction. The driving belt 14 is arranged in the front-to-back direction, and its front and rear ends are respectively wound around the first active roller 12 and the first driven roller 13. The first active roller 12 and the first driven roller 13 are both arranged on the main frame 11 in the left-right direction, and the first active roller 12 is driven by a corresponding motor.

[0022] The gravity concentration mechanism 2 includes a gravity frame 21, a front driven roller 22, a rear driven roller 23, a gravity belt 24, and a gravity belt cleaning structure 25. The gravity frame 21 is arranged in the front-to-back direction and is located directly above the main frame 11. The gravity belt 24 is arranged in the front-to-back direction and is located directly above the driving belt 14. Its front and rear ends are respectively wound around the front driven roller 22 and the rear driven roller 23.

[0023] The gravity belt cleaning structure 25 is located at the rear of the gravity frame 21 and includes a brush roller 51. The rear driven roller 23 is an air blowing roller, and air blowing holes are evenly distributed on its circumference, and it is connected to the compressed air supply device through a pipeline. The brush roller 51 is located directly behind the rear driven roller 23, and it rests on the gravity belt 24 (specifically the rear end), and is arranged in the left and right directions.

[0024] The vacuum pressing mechanism 3 includes a pressing frame 31, an upper driving roller 32, a lower driving roller 33, a second driven roller 34, a pressing belt 35, a pressing belt cleaning structure 36, and a filter belt cleaning structure 37. The pressing frame 31 is arranged in the front-to-back direction. The second driven roller 34 is arranged in the left-right direction, and the front end of the pressing belt 35 bypasses the second driven roller 34. The upper driving roller 32 and the lower driving roller 33 are arranged side by side up and down, and they are both arranged in the left-right direction. The pressing belt 35 bypasses the lower side of the upper driving roller 32 backward and upward. Specifically, the upper driving roller 32 and the lower driving roller 33 are synchronously driven by the gears thereon (driven by corresponding motors).

[0025] The pressing belt cleaning structure 36 includes a second scraper 61, a second water tank 62, and two second spray pipes 63 directly above the second water tank 62. The second scraper 61 is located directly behind the upper drive roller 32, and it rests on the pressing belt 35, and it is arranged in the left-right direction. The second water tank 62 is located at the upper front part of the pressing machine frame 31, and it is arranged in the left-right direction, and it can be a tapered tank with a larger top and a smaller bottom. The two second spray pipes 63 spray toward both sides of the pressing belt 35, and they are both arranged in the left-right direction.

[0026] Among them, the filter belt cleaning structure 37 includes a first scraper 71, a first water tank 72, a first air blowing roller 73 and two first spray pipes 74 directly above the first water tank 72. The first scraper 71 is located directly behind the lower drive roller 33, and it rests on the filter belt 4 (specifically the rear end), and it is arranged in the left and right directions. The first water tank 72 is located in the front and lower part of the lower drive roller 33, and it is arranged in the left and right directions. It can be specifically a rectangular tank. The lower part of the first air blowing roller 73 is located in the first water tank 72, and it is arranged in the left and right directions. There are air blowing holes evenly distributed on its circumference, and it is connected to the compressed air supply device through a pipeline. The filter belt 4 bypasses the lower side of the first air blowing roller 73 and is immersed in the cleaning liquid in the first water tank 72. The two first spray pipes 74 spray toward both sides of the filter belt 4 respectively, and they are both arranged in the left and right directions.

[0027] Among them, the filter belt 4 is arranged in the front-to-back direction, its front end bypasses the guide roller on the main frame 11, its front part passes between the driving belt 14 and the gravity belt 24, its rear part forms a pressing structure with the pressing belt 35, and its rear end bypasses the upper side of the lower drive roller 33 backward and downward.

[0028] Among them, see Figure 1 In the embodiment of the present invention, the first spray pipe 74 and the second spray pipe 63 are both provided with a plurality of spray holes or nozzles arranged side by side, and are connected to the washing liquid supply device through a pipeline (the left end or the right end, and the other end is closed). Specifically, the two second spray pipes 63 are respectively located in front of and behind the pressing belt 35. One first spray pipe 74 is located behind the first blowing roller 73, which is located above the filter belt 4, and sprays downward. Another first spray pipe 74 is located in front of the first blowing roller 73, which is located in front of the filter belt 4, and sprays backward.

[0029] Furthermore, the water inlet of the first water tank 72 in the embodiment of the present invention is connected to the washing liquid supply device (for providing clean water or process water) through a pipeline, and the drain outlets (located at the bottom or on the left and right sides) of the first water tank 72 and the second water tank 62 are connected to the wastewater collection device (specifically a drainage ditch) through pipelines.

[0030] Further, see Figure 1-2The brush roller 51 in the embodiment of the present invention is located directly behind the rear driven roller 23 and is arranged at the lower end of the swing arm 52. The swing arm 52 is arranged obliquely forward from top to bottom, and its middle part is hinged (through a left-right rotating shaft) at the rear end of the gravity frame 21, and a tension spring 53 (arranged obliquely upward from back to front) is arranged between the rear side of its upper end and the gravity frame 21.

[0031] The air supply pressure of the compressed air supply device in the embodiment of the present invention is 0.5-0.7 MPa; the water supply pressure of the first spray pipe 74 and the second spray pipe 63 is 0.5-0.6 MPa.

[0032] The cleaning cycle of the dehydration device of the phosphogypsum is shown in Table 1: Table 1

[0033] Among them, the total flow rate of the dehydration device for phosphogypsum in this embodiment is 120,000 kg / h (dry basis), the effective filtration area is 45 m2, the filter cloth width is 4000 mm, the belt speed is 0-18 m / min, and the main engine power is 45 KW.

[0034] As can be seen from Table 1, the cleaning days of the gravity belt, filter belt and press belt are all long (exceeding the maximum cleaning days recommended by the manufacturer) and close. In fact, the gravity belt, filter belt and press belt are cleaned together every 80 days, and the cleaning time is 3-5 hours. The gravity belt, filter belt and press belt can be cleaned at the same time to reduce the downtime of the equipment.

[0035] Example 2 See also Figure 1-2 Embodiment 2 provides a dehydration device for phosphogypsum, which is basically the same as that of Embodiment 1, except that: the first water tank 72 of this embodiment is arranged at the lower rear part of the press frame 31, and a redirecting roller 75 (arranged in the left and right direction) is arranged on the press frame 31 and located in front of and above the first blowing roller 73. The filter belt 4 bypasses the rear side of the lower drive roller 33, obliquely moves forward and downward to the first blowing roller 73, bypasses the lower side of the first blowing roller 73, and then obliquely moves forward and upward to the upper side of the redirecting roller 75. The second water tank 62 is located at the upper rear of the gravity belt cleaning structure 25, and a traction roller 64 (arranged in the left and right direction) is arranged at the front side of the press frame 31 and located below the second driven roller 34, and the traction roller 64 is located directly above the second water tank 62. The press belt 35 is wound downward from the front side of the second driven roller 34, bypasses the front side of the traction roller 64 and is wound obliquely backward and downward. The second spray pipe 63 is located between the second driven roller 34 and the traction roller 64. The first scraper 71 is located directly behind the lower part of the lower drive roller 33, and is arranged obliquely backward from bottom to top, and its upper end contacts the rear side of the filter belt 4. The second scraper 61 is located directly behind the upper part of the upper drive roller 32, and is arranged obliquely backward from top to bottom, and its lower end contacts the rear side of the press belt 35. Example 3 See also Figure 1 Embodiment 3 provides a dehydration device for phosphogypsum, which is basically the same as that of Embodiment 1, except that: the first scraper 71 of this embodiment is adjustably arranged (specifically, front-to-back adjustment (through long round holes and bolts in the front-to-back direction) and angle adjustment (specifically, rotation setting and locking)) in the middle of the first adjustment frame 76, and the second scraper 61 is adjustably arranged (specifically, front-to-back adjustment (through long round holes and bolts in the front-to-back direction) and angle adjustment (specifically, rotation setting and locking)) in the middle of the second adjustment frame 65. A fixed bracket 38 (specifically, two columns arranged side by side on the left and right) is arranged in the vertical direction directly behind the press frame 31. The first adjustment frame 76 and the second adjustment frame 65 are both arranged in the front-to-back direction, with their front ends hinged (through the left-right rotating shaft) on the rear side of the press frame 31, and their rear ends adjustable (specifically, adjustable up and down (through the long round holes and bolts arranged vertically)) arranged on the fixed bracket 38, which includes two adjustment arms arranged side by side (the middle of the two adjustment arms are respectively located on the left and right sides of the corresponding scraper, and their front ends are respectively hinged on the left and right sides of the press frame 31, and their rear ends are respectively arranged on two columns). The front driven roller 22 is adjustable front and back arranged at the front of the gravity frame 21, the second driven roller 34 is adjustable front and back arranged at the front of the press frame 31, and the first driven roller 13 is adjustable front and back arranged at the front of the main frame 11. The “first” and “second” in this embodiment are only used for distinction and have no other special meanings.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A dehydration device for phosphogypsum, comprising a vacuum filtration mechanism (1), a gravity concentration mechanism (2), a vacuum pressing mechanism (3) and a filter belt (4), wherein the vacuum pressing mechanism (3) is located directly behind the gravity concentration mechanism (2), the vacuum filtration mechanism (1) comprises a main frame (11), a first active roller (12), a first driven roller (13) and a drive belt (14), the gravity concentration mechanism (2) comprises a gravity frame (21), a front driven roller (22), a rear driven roller (23) and a gravity belt (24), the vacuum pressing mechanism (3) comprises a filter belt (4), and the filter belt (4) is provided. ) comprises a pressing machine frame (31), an upper driving roller (32), a lower driving roller (33), a second driven roller (34) and a pressing belt (35); the filtering belt (4) is arranged in a front-to-back direction, the front part of which passes between the driving belt (14) and the gravity belt (24), and the rear part of which forms a pressing structure with the pressing belt (35); the upper driving roller (32) and the lower driving roller (33) are arranged side by side in the vertical direction, the pressing belt (35) passes around the lower side of the upper driving roller (32) backwards and upwards, and the filtering belt (4) passes around the upper side of the lower driving roller (33) backwards and downwards; it is characterized in that The gravity concentration mechanism (2) further comprises a gravity belt cleaning structure (25), and the vacuum pressing mechanism (3) further comprises a pressing belt cleaning structure (36) and a filter belt cleaning structure (37); The gravity belt cleaning structure (25) is located at the rear of the gravity frame (21) and comprises a brush roller (51), the rear driven roller (23) is a blowing roller, the brush roller (51) is located directly behind the rear driven roller (23) and rests against the gravity belt (24); The press belt cleaning structure (36) comprises a second scraper (61), a second water tank (62) and two second spray pipes (63) directly above the second water tank (62); the second scraper (61) is located directly behind the upper drive roller (32) and rests against the press belt (35); the second water tank (62) is located at the upper front side of the press frame (31); and the two second spray pipes (63) spray towards both sides of the press belt (35) respectively; The filter belt cleaning structure (37) comprises a first scraper (71), a first water trough (72), a first air blowing roller (73) and two first spray pipes (74) directly above the first water trough (72); the first scraper (71) is located directly behind the lower drive roller (33) and is pressed against the filter belt (4); the first water trough (72) is located in front of and below the lower drive roller (33); the lower part of the first air blowing roller (73) is located in the first water trough (72); the filter belt (4) passes around the lower side of the first air blowing roller (73) and is immersed in the cleaning liquid in the first water trough (72); the two first spray pipes (74) spray towards both sides of the filter belt (4) respectively; Blowing holes are evenly distributed on the circumference of the first blowing roller (73) and the rear driven roller (23), and are connected to a compressed air supply device through pipelines.

2. The dehydration device for phosphogypsum according to claim 1, characterized in that: The first spray pipe (74) and the second spray pipe (63) are both arranged in the left-right direction, and a plurality of spray holes or nozzles are arranged side by side on the left-right direction, and are connected to the washing liquid supply device through pipelines; the two second spray pipes (63) are respectively located in front of and behind the pressing belt (35); one first spray pipe (74) is located behind the first blowing roller (73), which is located above the filter belt (4) and sprays downward; the other first spray pipe (74) is located in front of the first blowing roller (73), which is located in front of the filter belt (4) and sprays backward.

3. The dehydration device for phosphogypsum according to claim 2, characterized in that: The water inlet of the first water tank (72) is connected to the washing liquid supply device through a pipeline, and the drainage outlets of the first water tank (72) and the second water tank (62) are connected to the wastewater collection device through pipelines.

4. The dehydration device for phosphogypsum according to claim 1, characterized in that: The first water tank (72) is arranged at the lower rear part of the press frame (31); a redirecting roller (75) is arranged on the press frame (31) and located in front of and above the first blowing roller (73); the filter belt (4) passes around the rear side of the lower drive roller (33), moves obliquely forward and downward to the first blowing roller (73), passes around the lower side of the first blowing roller (73), and then moves obliquely forward and upward to the upper side of the redirecting roller (75).

5. The dehydration device for phosphogypsum according to claim 1, characterized in that: The second water trough (62) is located at the upper rear of the gravity belt cleaning structure (25); a traction roller (64) is provided at the front side of the press frame (31) and below the second driven roller (34); the traction roller (64) is located directly above the second water trough (62); the press belt (35) is wound downward from the front side of the second driven roller (34), bypasses the front side of the traction roller (64) and is wound obliquely downward and rearward; the second spray pipe (63) is located between the second driven roller (34) and the traction roller (64).

6. The dehydration device for phosphogypsum according to claim 1, characterized in that: The first scraper (71) and the second scraper (61) are both arranged in the left-right direction; the first scraper (71) is located directly behind the lower part of the lower drive roller (33), and is arranged obliquely backward from bottom to top, and its upper end contacts the rear side of the filter belt (4); the second scraper (61) is located directly behind the upper part of the upper drive roller (32), and is arranged obliquely backward from top to bottom, and its lower end contacts the rear side of the pressing belt (35).

7. The dehydration device for phosphogypsum according to claim 6, characterized in that: The first scraper (71) is adjustably arranged at the middle of the first adjustment frame (76), and the second scraper (61) is adjustably arranged at the middle of the second adjustment frame (65); a fixed bracket (38) is arranged in the vertical direction directly behind the press frame (31); the first adjustment frame (76) and the second adjustment frame (65) are both arranged in the front-to-back direction, with their front ends hinged on the rear side of the press frame (31), and their rear ends adjustably arranged on the fixed bracket (38).

8. The dehydration device for phosphogypsum according to claim 1, characterized in that: The brush roller (51) is located directly behind the rear driven roller (23) and is arranged at the lower end of the swing arm (52); the swing arm (52) is arranged obliquely forward from top to bottom, and its middle part is hinged to the rear end of the gravity frame (21), and a tension spring (53) is arranged between the rear side of its upper end and the gravity frame (21).

9. The dehydration device for phosphogypsum according to claim 1, characterized in that: The air supply pressure of the compressed air supply device is 0.5-0.7 Mpa; the water supply pressure of the first spray pipe (74) and the second spray pipe (63) is 0.5-0.6 Mpa.

10. The dehydration device for phosphogypsum according to claim 1, characterized in that: The upper drive roller (32) and the lower drive roller (33) are synchronously driven by the gears thereon; the front driven roller (22) is arranged at the front of the gravity frame (21) so as to be adjustable forward and backward; the second driven roller (34) is arranged at the front of the pressing frame (31) so as to be adjustable forward and backward; and the first driven roller (13) is arranged at the front of the main frame (11) so as to be adjustable forward and backward.

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