Preparation method of calcium-magnesium phosphate fertilizer and cooling system

Abstract

The application discloses a preparation method of calcium-magnesium phosphate fertilizer, which only comprises the following steps: mixing 60%-65% phosphogypsum filter residue, 15%-20% phosphorus tailings and 15%-20% yellow phosphorus slag to obtain a mixture, calcining the mixture at 600±10 DEG C for 1.5-2.5 hours to obtain a calcined product, and cooling the calcined product to below 40 DEG C, wherein the calcined product is gradually ground to a particle size of less than or equal to 0.25 mm during the cooling process, and then the calcium-magnesium phosphate fertilizer is obtained. The application solves the problem of high energy consumption in the processing of calcium-magnesium phosphate fertilizer in the prior art. Meanwhile, a cooling system for cooling the aforementioned calcined product is also provided.

Description

Technical Field

[0001] This invention relates to the field of calcium magnesium phosphate fertilizer processing technology, and in particular to a method for preparing calcium magnesium phosphate fertilizer and a cooling system. Background Technology

[0002] In existing technologies, phosphogypsum water treatment typically produces a large amount of filter press residue. This residue can be mixed with other waste materials and calcined, then processed into mineral fertilizer through water quenching and other methods. Alternatively, using a blast furnace method, the phosphogypsum filter press residue, phosphorus tailings, and yellow phosphorus slag are mixed, calcined at 1450℃, water-quenched, cooled, and then pulverized to obtain calcium magnesium phosphate fertilizer. This process requires a large amount of heat energy, resulting in high energy consumption. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing calcium magnesium phosphate fertilizer, which solves the problem of high energy consumption in the processing of calcium magnesium phosphate fertilizer in the existing technology.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for preparing calcium magnesium phosphate fertilizer includes only the following steps: mixing 60%-65% phosphogypsum filter residue, 15%-20% phosphate tailings, and 15%-20% yellow phosphorus slag to obtain a mixture; calcining the mixture at 600±10℃ for 1.5h-2.5h to obtain a calcined product; cooling the calcined product to below 40℃, during which the calcined product gradually becomes finer to a particle size of less than or equal to 0.25mm, thus obtaining calcium magnesium phosphate fertilizer. This method effectively reduces energy consumption by calcining the mixture at a lower temperature, and the pulverization during cooling further reduces overall energy consumption. Therefore, compared with existing technologies, it significantly saves energy consumption and solves the problem of high energy consumption in the processing of calcium magnesium phosphate fertilizer in existing technologies.

[0006] Furthermore, the phosphogypsum filter press residue contains P2O5 ≥ 6%, the phosphorus tailings contain SiO2 ≥ 50%, and the yellow phosphorus slag contains CaO ≥ 40%.

[0007] A cooling system is also provided for cooling the calcined product in the aforementioned method for preparing calcium magnesium phosphate fertilizer. The cooling system includes:

[0008] The first cold section includes a housing and a conveyor belt disposed therein extending from one end to the other. The housing is provided with a feed hopper having an orthographic projection at one end of the conveyor belt, and the other end of the conveyor belt extends outside the housing.

[0009] The second cooling section includes a fixed cylinder and a rotating cylinder that is rotatably disposed inside the fixed cylinder and extends to the outside of the fixed cylinder at one end. A spiral plate extending from one end to the other end is also fixed inside the rotating cylinder.

[0010] The material guiding assembly is located between the end of the conveyor belt located outside the outer casing and the end of the rotating drum located inside the fixed drum, so that the material on the conveyor belt is conveyed into the rotating drum.

[0011] The air inlet pipe is fixed relative to the fixed cylinder, and the end of the rotating cylinder located outside the fixed cylinder rotates around the air inlet pipe. Several discharge holes are provided on the outer wall of the end of the rotating cylinder located outside the fixed cylinder.

[0012] An air outlet pipe is fixed to one end of the fixed cylinder near the outer shell, and several air outlet holes are also provided at the end of the rotating cylinder located inside the fixed cylinder;

[0013] The air inlet duct is connected to a blower, and the air outlet duct is connected to an exhaust fan.

[0014] Furthermore, the material guiding assembly includes a fixedly mounted material guide hopper for receiving material from the conveyor belt and a material guide pipe fixed to the material guide hopper and extending into the rotating cylinder.

[0015] Furthermore, an outer ring shell is fixedly surrounding the fixed cylinder, and the fixed cylinder is also provided with several connecting holes that connect its interior to the outer ring shell. The air outlet pipe is fixed above the outer ring shell and connects to the interior of the outer ring shell, and the air outlet is set directly opposite the outer ring shell.

[0016] Furthermore, a first rotating ring is fixed inside the fixed cylinder, and the rotating cylinder is rotatably engaged with the first rotating ring. A second rotating ring is also fixed inside the rotating cylinder, and the second rotating ring is rotatably engaged with the fixed cylinder. A driven ring located outside the fixed cylinder is also fixed inside the second rotating ring. A driver that drives the driven ring to rotate is also installed outside the fixed cylinder.

[0017] Furthermore, a connecting ring is fixed between the second rotating ring and the driven ring, and the end of the fixed cylinder is rotatably disposed between the second rotating ring and the driven ring. The driver has an output end and a drive wheel is fixed to the output end, and the drive wheel is meshed with the driven ring.

[0018] Furthermore, a slag guide pipe connected to the outer ring shell is fixed below it.

[0019] Furthermore, a cover is fixed above the outer shell, and an outlet tube is fixed to the top of the cover.

[0020] Furthermore, the housing contains flowing cooling water, and the conveyor belt has an upper belt surface above the water surface and a lower belt surface partially below the water surface.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] Using a lower calcination temperature of 600℃, the material achieves lattice reconstruction and phosphorus-magnesium activation under solid conditions, reducing overall energy consumption by about 58% and CO2 emissions by about 50%. At the same time, water quenching is not performed, and the calcined product is crushed while cooling. Therefore, it saves energy consumption significantly compared to existing technologies and solves the problem of high energy consumption in the processing of calcium-magnesium phosphate fertilizer in existing technologies.

[0023] The provided cooling system is used to cool the calcined products while simultaneously pulverizing them, further reducing the overall energy consumption level, and can pulverize the final product to a level below 0.25mm. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1;

[0025] Figure 2 For this embodiment 1 Figure 1 Enlarged schematic diagram of a partial structure at point A (spiral plate not shown);

[0026] Figure 3 For this embodiment 1 Figure 1 Enlarged schematic diagram of a local structure at point B (spiral plate not shown);

[0027] Figure 4 For this embodiment 1 Figure 1 Enlarged schematic diagram of the local structure at point C (the spiral plate is not shown).

[0028] The reference numerals in the accompanying drawings include:

[0029] 1. Outer shell; 2. Conveyor belt; 3. Cooling water; 4. Water inlet pipe; 5. Overflow pipe; 6. Feed hopper; 7. Fixed cylinder; 8. Rotating cylinder; 9. Guide hopper; 10. Guide pipe; 11. Spiral plate; 12. Discharge hole; 13. Cover; 14. Outlet pipe; 15. Air inlet pipe; 16. Air outlet hole; 17. Outer ring shell; 18. Air outlet pipe; 19. Connecting hole; 20. Slag discharge pipe; 21. First rotating ring; 22. Second rotating ring; 23. Driven ring; 24. Connecting ring; 25. Drive motor; 26. Reducer; 27. Output end; 28. Detailed Implementation

[0030] The present invention will be further described in detail below through specific embodiments:

[0031] Example 1

[0032] like Figure 1-4As shown, this solution provides a cooling system, which includes a housing 1. The housing 1 has an inlet end and an outlet end located at both ends along its length. A conveyor belt 2 extends from the inlet end to the outlet end and passes through to the outside of the outlet end within the housing 1. Cooling water 3 is introduced into the housing 1 in a flowing state (i.e., an inlet pipe 4 and an overflow pipe 5 are provided on it for the cooling water 3 to enter and flow out, respectively). The conveyor belt 2 has an upper belt surface located above the water surface and a lower belt surface partially located below the water surface. Specifically, the end portion of the conveyor belt 2 that passes through the housing 1 is located above the water surface. A feed hopper 6 is fixed on the housing 1. The material (i.e., the calcined product) falls onto the end of the conveyor belt 2 near the feed end, and then is conveyed out of the outer shell 1 along with the conveyor belt 2. Furthermore, a fixed cylinder 7 is fixedly installed outside the outer shell 1, and a rotating cylinder 8 extending out of the fixed cylinder 7 is rotatably installed inside the fixed cylinder 7. A guide hopper 9 is also fixedly installed between the fixed cylinder 7 and the outer shell 1. The end of the conveyor belt 2 located outside the outer shell 1 is positioned above the guide hopper 9 so that the material passing through the outer shell 1 falls into the guide hopper 9. The guide hopper 9 is also fixed with a guide pipe 10 that passes through the fixed cylinder 7 and extends into the rotating cylinder 8, thereby guiding the material... The material is fed into the rotating drum 8, and spiral plates 11 arranged from one end to the other are fixed on the inner wall of the rotating drum 8. These spiral plates 11 push the material from one end to the other during the rotation of the rotating drum 8. During this movement, the material breaks apart due to collision and tumbling. Multiple discharge holes 12 are provided on the outer wall of the end of the rotating drum 8 located outside the fixed drum 7. These discharge holes 12 allow the broken material to be discharged. A collection hopper can be installed below the rotating drum 8 to collect the discharged material. This solution involves two stages of cooling for the material: the first stage occurs inside the outer shell 1. The second stage is carried out inside the fixed cylinder 7. Although water is involved in the first stage, it is not the water quenching treatment in the prior art. The cooling water 3 is used to cool the conveyor belt 2 and clean the residue on the conveyor belt 2. During this process, the cooling water 3 will reduce the temperature inside the overall shell 1. A cover 13 is also fixed on the top of the shell 1. The heat dissipated by the material during the movement on the conveyor belt 2 rises to the cover 13 and is then discharged through the outlet pipe 14 fixed on the top of the cover 13. A fan can be connected to the end of the outlet pipe 14 to improve the efficiency of heat discharge.Before the second stage, the material temperature has been reduced to a relatively low temperature, around 100℃. An air inlet pipe 15 is fixed to one end of the rotating cylinder 8 outside the fixed cylinder 7. That is, the end of the rotating cylinder 8 is rotatably fitted onto the air inlet pipe 15. The air inlet pipe 15 is also connected to a blower, which delivers cold air into the rotating cylinder 8. Multiple air outlets 16 are also provided on the outer wall of the end of the rotating cylinder 8 near the outer shell 1. A corresponding outer ring shell 17 is fixed to the fixed cylinder 7, surrounding all the air outlets 16. An air outlet pipe 18 is also fixed on the top, and the air outlet pipe 18 is connected to an induced draft fan. The fixed cylinder 7 is also provided with multiple connecting holes 19 connecting the outer ring shell 17 and the inside of the fixed cylinder 7. When the induced draft fan is running, it can guide the airflow, allowing it to be introduced from the blower, pass through one end of the rotating cylinder 8, and then exit to the fixed cylinder 7 at the other end. The air then passes through the connecting holes 19 to the outer ring shell 17, and is then carried away by the induced draft fan through the air outlet pipe 18. During this process, the dissipated heat is carried away, thereby achieving the purpose of cooling. Crushing also occurs during the cooling process.

[0033] like Figure 1-4 As shown, in a further embodiment, the air outlet pipe 18 is positioned above the outer ring shell 17, and a slag discharge pipe 20 connected to it is fixed below the outer ring shell 17. Subsequently, some residue can be discharged through the slag discharge pipe 20. Specifically, when the material enters the rotating cylinder 8, its size is relatively large, but the impact of its descent may also generate residue. Therefore, this arrangement allows for the smooth discharge of this residue. Furthermore, a first rotating ring 21 is fixed inside the fixed cylinder 7, and the rotating cylinder 8 rotatably engages with the first rotating ring 21. A second rotating ring 22 is also fixed to the rotating cylinder 8, and the second rotating ring 22 rotatably engages with the fixed cylinder 7. The second rotating ring 22 also has a driven ring 23 fixed outside the fixed cylinder 7. A driver is also installed outside the cylinder 7 to drive the driven ring 23 to rotate. When the driver runs, it can drive the rotating cylinder 8 to rotate. Specifically, a connecting ring 24 is fixed between the second rotating ring 22 and the driven ring 23, and the end of the fixed cylinder 7 is rotatably arranged between the second rotating ring 22 and the driven ring 23. The driver has an output end 28 and a drive wheel 25 is fixed to the output end 28. The drive wheel 25 is meshed with the driven ring 23. The driver may include a drive motor 26 and a reducer 27 connected to it. The output end 28 is connected to the reducer 27. When the drive motor 26 runs, it causes the driven ring 23 to rotate through the reducer 27 and the drive wheel 25, which ultimately causes the rotating cylinder 8 to rotate.

[0034] Example 2

[0035] A method for preparing calcium magnesium phosphate fertilizer is also provided. Compared with the prior art, this method does not involve water quenching and instead performs calcination at a lower temperature, while simultaneously pulverizing during the cooling process. The cooling and pulverizing are carried out using the cooling system provided in Example 1. Specifically, the preparation method includes the following steps:

[0036] A mixture of 60%-65% phosphogypsum filter residue, 15%-20% phosphate tailings, and 15%-20% yellow phosphorus slag is obtained. This mixture is calcined at 600±10℃ for 1.5-2.5 hours to obtain the calcined product. The calcined product is cooled to below 40℃, during which it gradually becomes finer to a particle size of less than or equal to 0.25mm, yielding calcium magnesium phosphate fertilizer. This method effectively reduces energy consumption by calcining the mixture at a lower temperature. Furthermore, the pulverization during cooling further reduces overall energy consumption. Compared to the traditional blast furnace method (1450℃), energy consumption is significantly reduced by 58%, and CO2 emissions are reduced by approximately 50%. Therefore, it significantly saves energy compared to existing technologies, solving the problem of high energy consumption in the processing of calcium magnesium phosphate fertilizer. The grade requirements for each raw material are also correspondingly lower in this method: P2O5 ≥ 6% in the phosphogypsum filter residue, SiO2 ≥ 50% in the phosphate tailings, and CaO ≥ 40% in the yellow phosphorus slag. The crushed calcium magnesium phosphate fertilizer can also be further processed into granular fertilizer as needed.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a calcium magnesium phosphate fertilizer, characterized by, by weight, Includes only the following steps, A mixture of 60%-65% phosphogypsum filter residue, 15%-20% phosphate tailings, and 15%-20% yellow phosphorus slag is obtained. The mixture is then calcined at 600±10℃ for 1.5h-2.5h to obtain the calcined product. The calcined product is cooled to below 40℃. During the cooling process, the calcined product gradually becomes finer until the particle size is less than or equal to 0.25mm, and then calcium magnesium phosphate fertilizer is obtained.

2. The method for preparing calcium magnesium phosphate fertilizer as described in claim 1, characterized in that, The phosphogypsum filter press residue contains P2O5 ≥ 6%, the phosphorus tailings contain SiO2 ≥ 50%, and the yellow phosphorus slag contains CaO ≥ 40%.

3. A cooling system, characterized in that, The cooling system used in the preparation method of calcium magnesium phosphate fertilizer as described in claim 1 or 2 for cooling the calcined product includes: The first cold section includes a housing and a conveyor belt disposed therein extending from one end to the other. The housing is provided with a feed hopper having an orthographic projection at one end of the conveyor belt, and the other end of the conveyor belt extends outside the housing. The second cooling section includes a fixed cylinder and a rotating cylinder that is rotatably disposed inside the fixed cylinder and extends to the outside of the fixed cylinder at one end. A spiral plate extending from one end to the other end is also fixed inside the rotating cylinder. The material guiding assembly is located between the end of the conveyor belt located outside the outer casing and the end of the rotating drum located inside the fixed drum, so that the material on the conveyor belt is conveyed into the rotating drum. The air inlet pipe is fixed relative to the fixed cylinder, and the end of the rotating cylinder located outside the fixed cylinder rotates around the air inlet pipe. Several discharge holes are provided on the outer wall of the end of the rotating cylinder located outside the fixed cylinder. An air outlet pipe is fixed to one end of the fixed cylinder near the outer shell, and several air outlet holes are also provided at the end of the rotating cylinder located inside the fixed cylinder; The air inlet duct is connected to a blower, and the air outlet duct is connected to an exhaust fan.

4. The cooling system as described in claim 3, characterized in that, The material guiding assembly includes a fixed material guide hopper for receiving material from the conveyor belt and a material guide pipe fixed to the material guide hopper and extending into the rotating cylinder.

5. The cooling system as described in claim 4, characterized in that, An outer ring shell is fixedly surrounded by the fixed cylinder. The fixed cylinder is also provided with several connecting holes that connect its interior to the outer ring shell. The air outlet pipe is fixed above the outer ring shell and connects to the interior of the outer ring shell. The air outlet is set directly opposite the outer ring shell.

6. The cooling system as described in claim 5, characterized in that, A first rotating ring is also fixed inside the fixed cylinder, and the rotating cylinder and the first rotating ring are rotatably engaged. A second rotating ring is also fixed inside the rotating cylinder, and the second rotating ring is rotatably engaged with the fixed cylinder. A driven ring located outside the fixed cylinder is also fixed inside the second rotating ring. A driver that drives the driven ring to rotate is also installed outside the fixed cylinder.

7. The cooling system as described in claim 6, characterized in that, A connecting ring is fixed between the second rotating ring and the driven ring, and the end of the fixed cylinder is rotatably disposed between the second rotating ring and the driven ring. The driver has an output end and a drive wheel is fixed to the output end. The drive wheel is meshed with the driven ring.

8. The cooling system as described in claim 5, characterized in that, A slag guide pipe connected to the outer ring shell is also fixed below it.

9. The cooling system as described in claim 3, characterized in that, A cover is fixed on the top of the outer shell, and an outlet tube is fixed on the top of the cover.

10. The cooling system as described in any one of claims 3-9, characterized in that, The housing contains flowing cooling water, and the conveyor belt has an upper belt surface above the water surface and a lower belt surface partially below the water surface.

Images