A method for producing ammonium salt from calcined phosphate tailings and a high-intensity stirring and filtration device

Abstract

This invention discloses a method for producing ammonium salts from calcined phosphate tailings, comprising the following steps: S1, calcination of phosphate tailings; S2, stirring leaching; S3, high-intensity stirring filtration; The mixed solution in step S2 is subjected to high-intensity stirring to address the problem of increased material viscosity caused by magnesium dissolution, and pressure is applied to improve the filtration effect and productivity, forming filtrate and filter residue; S4, classification and treatment of filtrate and filter residue; Ammonia and carbon dioxide are added to the filtrate for stirring and mixing, followed by precipitation, filtration, washing, and drying to obtain light calcium carbonate; Ammonium sulfate solution is added to the filter residue for stirring leaching, followed by decantation and filtration to obtain solution, phosphate concentrate, and waste residue. By utilizing the selectivity of ammonium salts for calcium and magnesium leaching, calcium and magnesium are separated, resulting in a high-purity magnesium product and a low-magnesium, high-phosphate concentrate. This decomposes phosphate tailings into different products, achieving full utilization of phosphate tailings and improving productivity.

Description

Technical Field

[0001] This invention relates to the field of phosphate concentrate production and preparation, specifically to a method for producing ammonium salt from calcined phosphate tailings and a high-intensity stirring and filtration device. Background Technology

[0002] As a non-renewable resource, phosphate rock resources have gradually become depleted after extensive mining. As a result, people have had to actively explore ways to utilize low- and medium-grade phosphate rock, and the comprehensive utilization of low- and medium-grade phosphate rock has been put on the research agenda.

[0003] In phosphate rock, carbonates (mainly dolomite, followed by calcite) coexist with phosphate minerals to varying degrees, resulting in shared cations between phosphate rock and carbonate minerals. This weakens the differences in surface properties between minerals, and the extremely fine particle size makes beneficiation difficult. Among various impurities, magnesium is one of the main impurity elements, and its content is usually calculated as MgO. Industrial use of phosphate rock requires certain requirements on the content of the useful component P2O5, and also limits on major harmful impurities. In the acid process of phosphate rock processing, magnesium is a major harmful impurity, and its content is strictly limited. This is because MgO has the following adverse effects during acid processing: First, the high solubility of magnesium reduces the activity of hydrogen ions in the liquid phase, thus reducing the phosphate rock decomposition rate; second, the dissolution of magnesium increases the viscosity of the material, affecting product filtration and productivity; third, the hygroscopicity of the product affects its physical properties. Therefore, traditional acid processing methods for improving phosphate rock grade lead to low productivity. Furthermore, addressing the impact of solution viscosity on filtration is also a key issue that needs to be considered. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for producing ammonium salt from calcined phosphorus tailings and a high-intensity stirring and filtration device. By utilizing the selectivity of ammonium salt for calcium and magnesium leaching, calcium and magnesium can be separated, resulting in a magnesium product with high purity. Furthermore, the high-intensity stirring method solves the problem of the effect of solution viscosity on filtration, thereby improving productivity.

[0005] The objective of this invention is achieved through the following technical solution: a method for producing ammonium salt from calcined phosphate tailings, comprising the following steps:

[0006] S1. Calcination of phosphorus tailings: The phosphorus tailings are placed in a high-temperature box-type resistance furnace and calcined for a period of time, then sealed and cooled for later use.

[0007] S2. Stirring and leaching: Add the calcined clinker to the ammonium nitrate solution and mix and stir.

[0008] S3. High-intensity stirring and filtration: The mixed solution in step S2 is stirred with high intensity to solve the problem of increased material viscosity caused by magnesium dissolution, and the material filtration effect and productivity are improved by pressurization to form filtrate and filter residue.

[0009] S4. Classify and process the filtrate and filter residue;

[0010] In this process, ammonia and carbon dioxide are added to the filtrate and stirred and mixed. Then, light calcium carbonate is obtained by precipitation, filtration, washing and drying.

[0011] In this process, ammonium sulfate solution is added to the filter residue for stirring and leaching, followed by decantation and filtration to obtain the solution, phosphate concentrate, and waste residue.

[0012] In some embodiments, magnesium oxide is prepared using the solution obtained by decantation and filtration of filter residue, comprising the following steps:

[0013] S11. Pass the solution through ammonia gas to induce precipitation;

[0014] S21. Filter the solution containing the precipitate;

[0015] S31. Washing and drying: The filtered solid is washed and then dried to obtain magnesium hydroxide.

[0016] S41, Calcination treatment; magnesium hydroxide is calcined to obtain magnesium oxide.

[0017] In some embodiments, the liquid filtered in step S21 is passed into the filter residue in step S4 for recycling.

[0018] The effect of adopting the above technical solution is that by utilizing the selectivity of ammonium salt for calcium and magnesium leaching, calcium and magnesium can be separated, resulting in a magnesium product with high purity, while calcium can also be utilized. More importantly, it can also successfully obtain a low-magnesium, high-phosphorus concentrate, thereby decomposing phosphorus tailings into different products, realizing the full utilization of phosphorus tailings, and improving productivity.

[0019] A high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings includes a stirring tank and a stirring support. A filter screen is installed inside the stirring tank. The stirring support is located on the outside of the stirring tank and has a multi-directional stirring mechanism. The multi-directional stirring mechanism moves along the height direction of the stirring tank. The multi-directional stirring mechanism includes several concentrically arranged annular disks with decreasing outer diameters. The outer walls of adjacent annular disks with smaller outer diameters are rotatably mounted on the inner walls of adjacent annular disks with larger outer diameters. Several stirring shafts are installed on the annular disks and are evenly distributed circumferentially around the center of the annular disks. The end of each stirring shaft away from the center of the annular disk is inclined.

[0020] In some embodiments, a cylinder is vertically mounted on the stirring bracket, the cylinder body is mounted on the stirring bracket, the telescopic shaft of the cylinder is connected to a connecting rod, and the end of the connecting rod away from the cylinder is connected to a drive box. The outer wall of the outermost annular disk of the multi-directional stirring mechanism is rotatably mounted at the bottom of the drive box. The drive box has a drive cavity. A hollow column is fixed to the top of the annular disk. The inner diameter of the hollow column is connected to the inner diameter of the corresponding annular disk, and the outer diameter of the hollow column is smaller than the outer diameter of the corresponding annular disk. The hollow column on the annular disk closer to the center of the multi-directional stirring mechanism is taller. A drive mechanism for rotating the hollow column is provided in the drive cavity.

[0021] In some embodiments, the drive mechanism includes a motor and a drive shaft. One end of the drive shaft is rotatably connected to the drive housing, and the other end of the drive shaft is drive-connected to the output shaft of the motor. A first gear is provided on the hollow column, and a second gear is drive-connected to the first gear. The second gear is keyed to the drive shaft. In this embodiment, at least one of the first gears on the hollow column has a different number of teeth than the other first gears.

[0022] In some embodiments, an intermediate gear is rotatably disposed within the drive cavity, a first gear on the innermost annular disk of the multi-directional stirring mechanism meshes with the intermediate gear, the intermediate gear meshes with a second gear at a corresponding height, and the first gears on the remaining annular disks directly mesh with the second gears at corresponding heights.

[0023] In some embodiments, an elastic sealing ring is fixed to the inner wall of the hollow column, and the elastic sealing ring is adapted to the outer wall of the adjacent hollow column.

[0024] In some embodiments, the top of the mixing tank is provided with a tank cover, the multi-directional stirring mechanism and the drive box are both located inside the mixing tank, the tank cover has a through hole for the connecting rod to pass through, the tank cover is provided with a pressurization port, the stirring bracket is provided with a pressurization pump, and the pressurization port of the pressurization pump is connected to the pressurization port through a pressurization pipe.

[0025] In some embodiments, the side wall of the mixing tank is provided with a feed pipe and a discharge pipe, and both the feed pipe and the discharge pipe are provided with valves. The feed pipe and the discharge pipe are located above and below the filter screen, respectively.

[0026] The beneficial effects of this invention are:

[0027] 1. By utilizing the selectivity of ammonium salts in leaching calcium and magnesium, calcium and magnesium can be separated, resulting in magnesium products with higher purity. At the same time, calcium can also be utilized. More importantly, low-magnesium, high-phosphorus concentrate can also be successfully obtained, thereby decomposing phosphorus tailings into different products, making full use of phosphorus tailings and improving productivity.

[0028] 2. By concentrically overlapping multiple annular discs, multiple sets of stirring shafts are arranged radially along the mixing tank, forming different stirring layers and expanding the stirring range. Secondly, since at least one of the first gears has a different number of teeth than the others, different stirring speeds are generated between the stirring shafts, breaking the stirring pattern and allowing the solution in the mixing tank to collide with each other to enhance the stirring intensity. At the same time, the setting of the intermediate gear makes the rotation direction of the innermost annular disc different from the rotation direction of the other annular discs, thereby achieving stirring from two opposite directions, causing the solution in the mixing tank to ripple, greatly improving the stirring intensity, effectively separating high-viscosity solutions from the filter residue, solving the impact of high solution viscosity on filtration, improving filtration efficiency and effect, and also increasing productivity. Attached Figure Description

[0029] Figure 1 This is a production flow diagram of a method for producing ammonium salt from calcined phosphorus tailings according to the present invention.

[0030] Figure 2 This is a schematic diagram of the internal structure of a high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to the present invention.

[0031] Figure 3 This is a partial internal view of a high-intensity stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to the present invention.

[0032] Figure 4 This is a schematic diagram of the internal structure of the multi-directional stirring mechanism in a high-intensity stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to the present invention.

[0033] Figure 5 for Figure 4 Enlarged view of point A in the middle;

[0034] In the diagram, 1-mixing tank, 2-mixing support, 3-ring disc, 4-filter screen, 5-mixing shaft, 6-cylinder, 7-connecting rod, 8-drive box, 9-drive chamber, 10-hollow column, 11-motor, 12-drive shaft, 13-first gear, 14-second gear, 15-intermediate gear, 16-elastic sealing ring, 17-bucket lid, 18-pressurization port, 19-pressurization pump, 20-pressurization pipe, 21-feed pipe, 22-discharge pipe. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0036] like Figure 1 As shown, a method for producing ammonium salt from calcined phosphate tailings includes the following steps:

[0037] S1. Calcination of phosphorus tailings: Place the phosphorus tailings in a high-temperature box-type resistance furnace, calcine for a period of time, and then cool in a sealed manner for later use.

[0038] S2. Stirring and leaching: Add the calcined clinker to the ammonium nitrate solution and mix and stir.

[0039] S3. High-intensity stirring and filtration: The mixed solution in step S2 is stirred with high intensity to solve the problem of increased material viscosity caused by magnesium dissolution, and the material filtration effect and productivity are improved by pressurization to form filtrate and filter residue.

[0040] S4. Classify and process the filtrate and filter residue;

[0041] In this process, ammonia and carbon dioxide are added to the filtrate and stirred and mixed. Then, light calcium carbonate is obtained by precipitation, filtration, washing and drying.

[0042] In this process, ammonium sulfate solution is added to the filter residue for stirring and leaching, followed by decantation and filtration to obtain the solution, phosphate concentrate, and waste residue.

[0043] By utilizing the selectivity of ammonium salts in leaching calcium and magnesium, calcium and magnesium can be separated, resulting in a high-purity magnesium product. At the same time, calcium can also be utilized. More importantly, a low-magnesium, high-phosphorus concentrate can be successfully obtained, thereby decomposing phosphorus tailings into different products, making full use of phosphorus tailings, and improving productivity.

[0044] Magnesium oxide is prepared from the solution obtained by decantation and filtration of filter residue, including the following steps:

[0045] S11. Pass the solution through ammonia gas to induce precipitation;

[0046] S21. Filter the solution containing the precipitate;

[0047] S31. Washing and drying: The filtered solid is washed and then dried to obtain magnesium hydroxide.

[0048] S41, Calcination treatment; magnesium hydroxide is calcined to obtain magnesium oxide.

[0049] The liquid filtered in step S21 is passed into the filter residue in step S4 for recycling.

[0050] This process decomposes phosphorus tailings into calcium carbonate, magnesium oxide, and phosphate concentrate, enabling the production of multiple products and significantly improving the utilization rate of phosphorus tailings. Specifically, the carbon dioxide required for the filtrate in step S4 can be obtained by calcining the phosphorus tailings. Carbon dioxide is generated during the calcination of phosphorus tailings, and this carbon dioxide is passed into the filtrate to produce calcium carbonate, ensuring full utilization of the material. The filtered liquid is returned to step S2, achieving liquid recycling and greatly improving the production rate of calcium carbonate. At the same time, ammonia gas is generated in step S2 and during the stirring and leaching process of the filter residue and ammonium sulfate. This ammonia gas is used in step S11. Furthermore, the filtrate is purified before adding ammonia and carbon dioxide to remove harmful gases. Simultaneously, the solution is also purified before step S11 to remove harmful gases.

[0051] like Figures 2 to 4 As shown, a high-strength stirring and filtering device for the production of ammonium salt from calcined phosphate tailings includes a stirring tank 1 and a stirring support 2. A filter screen 4 is installed inside the stirring tank 1. The stirring support 2 is located on the outside of the stirring tank 1 and is equipped with a multi-directional stirring mechanism. The multi-directional stirring mechanism moves along the height direction of the stirring tank 1. The multi-directional stirring mechanism includes several concentrically arranged annular disks 3. The outer diameters of the annular disks 3 are arranged in descending order. The outer walls of adjacent smaller outer diameter annular disks 3 are rotatably mounted on the inner walls of adjacent larger outer diameter annular disks 3. Several... A plurality of stirring shafts 5 are evenly distributed around the center of the annular disk 3. The end of the stirring shaft 5 away from the center of the annular disk 3 is inclined. By concentrically overlapping multiple annular disks 3, multiple sets of stirring shafts 5 are arranged in sequence along the radial direction of the mixing tank 1, thereby forming different stirring layers and expanding the stirring range. In use, the multi-directional stirring mechanism is inserted into the mixing tank 1 for high-intensity stirring, so that the filtrate with high viscosity is effectively separated from the filter residue. The separated filtrate is collected through the filter screen 4 and enters the production process of calcium carbonate preparation.

[0052] In some embodiments, such as Figure 3 and Figure 4As shown, a cylinder 6 is vertically mounted on the stirring support 2. The cylinder body of the cylinder 6 is mounted on the stirring support 2. The telescopic shaft of the cylinder 6 is connected to a connecting rod 7. The end of the connecting rod 7 away from the cylinder 6 is connected to a drive box 8. The outermost annular disk 3 of the multi-directional stirring mechanism is rotatably mounted at the bottom of the drive box 8. The drive box 8 has a drive cavity 9. A hollow column 10 is fixed to the top of the annular disk 3. The inner diameter of the hollow column 10 is connected to the inner diameter of the corresponding annular disk 3, and the outer diameter of the hollow column 10 is smaller than the outer diameter of the corresponding annular disk 3. The hollow column 10 on the annular disk 3 closer to the center of the multi-directional stirring mechanism is taller. The drive cavity 9 is equipped with a mechanism for driving the hollow column 10. The rotating drive mechanism includes a motor 11 and a drive shaft 12. One end of the drive shaft 12 is rotatably connected to the drive housing 8, and the other end of the drive shaft 12 is drive-connected to the output shaft of the motor 11. A first gear 13 is provided on the hollow column 10, and a second gear 14 is drive-connected to the first gear 13. The second gear 14 is keyed to the drive shaft 12. At least one of the first gears 13 on the hollow column 10 has a different number of teeth than the other first gears 13. An intermediate gear 15 is rotatably provided in the drive cavity 9. The first gear 13 on the innermost annular disk 3 of the multi-directional stirring mechanism meshes with the intermediate gear 15. The intermediate gear 15 and its corresponding... The second gear 14 at the corresponding height meshes with the first gear 13 on the remaining annular disks 3. The motor 11 drives the hollow column 10 to rotate through the transmission connection between the first gear 13 and the second gear 14. The hollow column 10 drives the corresponding annular disk 3 to rotate, and the annular disk 3 drives the stirring shaft 5 on it to rotate. Since at least one of the first gears 13 has a different number of teeth than the other first gears 13, different stirring speeds are generated between the stirring shafts 5, breaking the stirring pattern and allowing the solution in the stirring tank 1 to collide with each other to enhance the stirring intensity. At the same time, the first gear 13 on the innermost annular plate meshes with the second gear 14 at the corresponding height. The intermediate gear 15 is connected to the second gear 14, so that the rotation direction of the innermost annular disk 3 is different from that of the other annular disks 3, thereby achieving stirring from two opposite directions. This causes the solution in the stirring tank 1 to ripple, greatly improving the stirring intensity and effectively separating the high viscosity solution from the filter residue. This solves the problem of high solution viscosity affecting filtration, improves filtration efficiency and effect, and also increases productivity. In specific implementation, the cylinder 6 drives the multi-directional stirring mechanism to move up and down along the axial direction of the stirring tank 1, thereby increasing the stirring range in the axial direction of the stirring tank 1 and greatly expanding the stirring range so that high-intensity stirring can be carried out within the stirring range.

[0053] In some embodiments, such as Figure 5As shown, an elastic sealing ring 16 is fixed to the inner wall of the hollow column 10. The elastic sealing ring 16 is adapted to the outer wall of the adjacent hollow column 10. The annular disks 3 are connected to each other by bearings. Due to the bearings, there is a gap between the adjacent annular disks 3, which can easily cause the solution to enter the drive box 8 and cause problems. The elastic sealing ring 16 generates a high-strength sealing surface between the annular disks 3, which improves the sealing strength and ensures that the parts in the drive box 8 are not affected. Secondly, the inner ring of the innermost annular disk 3 is sealed by a plug to prevent the solution from entering the drive box 8 through the inner ring of the innermost annular disk 3.

[0054] In some embodiments, such as Figure 1 As shown, the top of the mixing tank 1 is provided with a tank cover 17. The multi-directional stirring mechanism and the drive box 8 are both located inside the mixing tank 1. The tank cover 17 has a through hole for the connecting rod 7 to pass through. The tank cover 17 is provided with a pressure port 18. The stirring support 2 is provided with a pressure pump 19. The pressure port of the pressure pump 19 is connected to the pressure port 18 through a pressure pipe 20. The side wall of the mixing tank 1 is provided with a feed pipe 21 and a discharge pipe 22. Both the feed pipe 21 and the discharge pipe 22 are provided with valves. The feed pipe 21 and the discharge pipe 22 are located above and below the filter screen 4, respectively. Phosphate tailings are introduced through the feed pipe 21. During the stirring reaction, the pressure pump 19 provides pressure to the mixing tank 1, so that the mixing tank 1 has a high pressure, which accelerates the separation of the filtrate and also accelerates the passage of the filtrate through the filter screen 4 to improve the filtration efficiency. The decomposed filtrate is discharged through the discharge pipe 22.

[0055] In summary, on the one hand, the selective leaching of calcium and magnesium by ammonium salts is utilized to achieve the separation of calcium and magnesium, resulting in magnesium products with higher purity. On the other hand, the stirring separation device is improved to increase the stirring intensity and range, thereby increasing the decomposition rate of the filtrate. This allows both the method and the device to be implemented simultaneously, greatly improving the productivity and utilization rate of the product.

[0056] In the description of this invention, it should be understood that the terms "coaxial," "bottom," "one end," "top," "middle," "other end," "upper," "side," "top," "inner," "front," "center," and "both ends," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. Furthermore, those skilled in the art will understand that the beneficial effects to be achieved by this invention are merely to achieve better beneficial effects compared with the current embodiments in the prior art under specific conditions, rather than to directly achieve the best use effect in the industry.

[0057] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings, characterized in that, The apparatus includes a mixing tank (1) and a mixing support (2). A filter screen (4) is provided inside the mixing tank (1). The mixing support (2) is located on the outside of the mixing tank (1). A multi-directional mixing mechanism is provided on the mixing support (2). The multi-directional mixing mechanism moves along the height direction of the mixing tank (1). The multi-directional mixing mechanism includes several concentrically arranged annular disks (3). The outer diameters of the several annular disks (3) are arranged in descending order. The outer wall of the adjacent annular disk (3) with a smaller outer diameter is rotatably arranged on the inner wall of the adjacent annular disk (3) with a larger outer diameter. Several mixing shafts (5) are provided on the annular disks (3). The several mixing shafts (5) are evenly distributed around the center of the annular disks (3). The end of the mixing shaft (5) away from the annular disk (3) is inclined away from the center of the annular disk (3). The outermost annular disk (3) of the multi-directional stirring mechanism is rotatably mounted on the bottom of the drive box (8). The drive box (8) is provided with a drive cavity (9). A hollow column (10) is fixed on the top of the annular disk (3). A first gear (13) is provided on the hollow column (10). The first gear (13) is driven by a second gear (14). The second gear (14) is keyed to the drive shaft (12). An intermediate gear (15) is rotatably mounted in the drive cavity (9). The first gear (13) on the innermost annular disk (3) of the multi-directional stirring mechanism meshes with the intermediate gear (15). The intermediate gear (15) meshes with the second gear (14) at the corresponding height. The first gear (13) on the remaining annular disks (3) directly meshes with the second gear (14) at the corresponding height.

2. The high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to claim 1, characterized in that, A cylinder (6) is vertically mounted on the stirring bracket (2). The cylinder body of the cylinder (6) is mounted on the stirring bracket (2). The telescopic shaft of the cylinder (6) is connected to a connecting rod (7). The end of the connecting rod (7) away from the cylinder (6) is connected to a drive box (8). The inner diameter of the hollow column (10) is connected to the inner diameter of the corresponding annular disk (3). The outer diameter of the hollow column (10) is smaller than the outer diameter of the corresponding annular disk (3). The hollow column (10) on the annular disk (3) closer to the center of the multi-directional stirring mechanism is higher. A drive mechanism for driving the hollow column (10) to rotate is provided in the drive cavity (9).

3. A high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to claim 2, characterized in that, The drive mechanism includes a motor (11) and a drive shaft (12). One end of the drive shaft (12) is rotatably connected to the drive box (8), and the other end of the drive shaft (12) is drive-connected to the output shaft of the motor (11). The number of teeth of the first gear (13) on at least one of the hollow columns (10) is different from the number of teeth of the other first gears (13).

4. A high-strength stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to claim 3, characterized in that, An elastic sealing ring (16) is fixed to the inner wall of the hollow column (10), and the elastic sealing ring (16) is adapted to the outer wall of the adjacent hollow column (10).

5. A high-intensity stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to claim 2, characterized in that, The top of the mixing tank (1) is provided with a lid (17). The multi-directional stirring mechanism and the drive box (8) are both located inside the mixing tank (1). The lid (17) has a through hole for the connecting rod (7) to pass through. The lid (17) is provided with a pressurization port (18). The stirring bracket (2) is provided with a pressurization pump (19). The pressurization port of the pressurization pump (19) is connected to the pressurization port (18) through a pressurization pipe (20).

6. A high-intensity stirring and filtering device for producing ammonium salt from calcined phosphate tailings according to claim 1, characterized in that, The side wall of the mixing tank (1) is provided with a feed pipe (21) and a discharge pipe (22), and valves are provided on both the feed pipe (21) and the discharge pipe (22). The feed pipe (21) and the discharge pipe (22) are located above and below the filter screen (4), respectively.

7. A method for producing ammonium salt from calcined phosphate tailings, using a high-intensity stirring and filtering device for producing ammonium salt from calcined phosphate tailings as described in claim 1, characterized in that... Includes the following steps: S1. Calcination of phosphorus tailings: The phosphorus tailings are placed in a high-temperature box-type resistance furnace and calcined for a period of time, then sealed and cooled for later use. S2. Stirring and leaching: Add the calcined clinker to the ammonium nitrate solution and mix and stir. S3. High-intensity stirring and filtration: The mixed solution in step S2 is stirred with high intensity to solve the problem of increased material viscosity caused by magnesium dissolution, and the material filtration effect and productivity are improved by pressurization to form filtrate and filter residue. S4. Classify and process the filtrate and filter residue; In this process, ammonia and carbon dioxide are added to the filtrate and stirred and mixed. Then, light calcium carbonate is obtained by precipitation, filtration, washing and drying. In this process, ammonium sulfate solution is added to the filter residue for stirring and leaching, followed by decantation and filtration to obtain the solution, phosphate concentrate, and waste residue.

8. The method for producing ammonium salt from calcined phosphorus tailings according to claim 7, characterized in that, Magnesium oxide is prepared from the solution obtained by decantation and filtration of filter residue, including the following steps: S11. Pass the solution through ammonia gas to induce precipitation; S21. Filter the solution containing the precipitate; S31. Washing and drying: The filtered solid is washed and then dried to obtain magnesium hydroxide. S41, Calcination treatment; magnesium hydroxide is calcined to obtain magnesium oxide.

9. A method for producing ammonium salt from calcined phosphorus tailings according to claim 8, characterized in that, The liquid filtered in step S21 is passed into the filter residue in step S4 for recycling.

Images