A low-grade phosphate ore calcination process system

Abstract

The utility model discloses a kind of low-grade phosphate rock calcination process systems, including feed system, preheating system and calcining system connected in sequence by pipeline, the preheating system includes first cyclone recovery and first cloth bag dust collector, the gas outlet of the first cyclone recovery is connected with the material inlet of the first cloth bag dust collector by pipeline;The low-grade phosphate rock calcination process system further includes magnesium oxide dry desulfurization system and urea denitration system, the calcining system includes rotary kiln, the material outlet of the preheating system is connected with the material inlet of the rotary kiln by pipeline, the material outlet of the magnesium oxide dry desulfurization system is connected with the material inlet of the first cyclone recovery by pipeline, the material outlet of the urea denitration system is connected with the rotary kiln by pipeline.The low-grade phosphate rock calcination process system of the utility model, solve a series of problems such as equipment wear, particle sensitive, overburning, green burning, agglomeration wall sticking, desulfurization, out-of-stock, quick calcination decomposition can also obtain superhigh-activity magnesium oxide, calcium oxide product.

Description

Technical Field

[0001] This utility model relates to the field of phosphate rock calcination technology, specifically to a calcination process system for low-grade phosphate rock. Background Technology

[0002] Low-grade phosphate rock contains some dolomite (a mixture of calcium carbonate and magnesium carbonate in a certain proportion). Burning the dolomite in low-grade phosphate rock yields highly active magnesium oxide and calcium oxide, which is extremely needed in the phosphate rock fertilizer industry.

[0003] In existing technologies, rotary kilns or traditional fluidized bed kilns are used for calcination. In rotary kiln calcination, the rotation of the kiln body drives the material movement, resulting in significant wear and tear on the mechanical equipment and high maintenance costs. Furthermore, when the material or finished product contains fine particles, the long calcination time (3-4 hours) can lead to over-burning and low activity. The slow material movement also makes it prone to agglomeration and adhesion to the walls. Fluidized bed kiln calcination is extremely sensitive to the particle size of the material. The working principle of a fluidized bed kiln is to achieve a balance between gas buoyancy and material weight (fluidization), causing the material to fluidize (briefly suspended) and complete calcination during this fluidization process. If the particle size is uneven or changes, fluidization will be disrupted, leading to material spillage (under-burning) or over-burning.

[0004] In addition, the above two calcination technologies for calcining phosphate rock also require addressing the sulfides (desulfurization) and nitrogen oxides (denitrification) in the tail gas. However, when performing desulfurization or denitrification, traditional desulfurization and denitrification can only be carried out in the tail gas at the end of the calcination process. Utility Model Content

[0005] Therefore, this utility model provides a low-grade phosphate rock calcination process system to solve one or more of the technical problems in the prior art, such as incomplete decomposition or over-calcination of dolomite, poor activity of magnesium oxide and calcium oxide, sensitivity to material particle size, high energy consumption, material sticking to the wall, and desulfurization and denitrification of tail gas.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A low-grade phosphate rock calcination process system includes a feeding system, a preheating system, and a calcination system connected in sequence by pipelines. The preheating system includes a first cyclone collector and a first bag filter. The gas outlet of the first cyclone collector is connected to the material inlet of the first bag filter through a pipeline.

[0008] The low-grade phosphate rock calcination process system also includes a magnesium oxide dry desulfurization system and a urea denitrification system. The calcination system includes a cyclone kiln. The material outlet of the preheating system is connected to the material inlet of the cyclone kiln through a pipeline. The material outlet of the magnesium oxide dry desulfurization system is connected to the material inlet of the first cyclone recoverer through a pipeline. The material outlet of the urea denitrification system is connected to the cyclone kiln through a pipeline.

[0009] Furthermore, the feeding system includes a raw material silo and a rotor scale. The material outlet of the raw material silo is connected to the material inlet of the rotor scale via a pipeline, and the material outlet of the rotor scale is connected to the material inlet of the first cyclone recoverer via a pipeline.

[0010] Furthermore, the preheating system also includes a second cyclone collector, a third cyclone collector, a fourth cyclone collector, and a dust collection powder silo. The material outlet of the first cyclone collector is connected to the material inlet of the second cyclone collector via a pipeline. The material outlet of the second cyclone collector is connected to the material inlet of the third cyclone collector via a pipeline. The material outlet of the third cyclone collector is connected to the material inlet of the fourth cyclone collector via a pipeline. The material outlet of the fourth cyclone collector is connected to the material inlet of the third cyclone collector via a pipeline. The gas outlet of the third cyclone collector is connected to the material inlet of the second cyclone collector via a pipeline. The gas outlet of the second cyclone collector is connected to the material inlet of the first cyclone collector via a pipeline. The material outlet of the first bag filter is connected to the material inlet of the dust collection powder silo via a pipeline. The material outlet of the dust collection powder silo is connected to the material inlet of the third cyclone collector via a pipeline.

[0011] Furthermore, the cyclone kiln includes a high-temperature combustion chamber, a first cyclone furnace section connected to the high-temperature combustion chamber, and a second cyclone furnace section connected to the first cyclone furnace section. The first and second cyclone furnace sections are vertically arranged, and their tops are connected. The first cyclone furnace section is equipped with a guide screw for guiding the material in a spiral centrifugal curve motion. The material outlet of the preheating system is connected to the material inlet at the lower end of the first cyclone furnace section via a pipeline. The material outlet of the urea denitrification system is connected to the upper urea inlet of the first cyclone furnace section. A denitrification agent spray gun is installed in the upper urea inlet of the first cyclone furnace section. The low-grade phosphate rock calcination process system also includes a high-temperature finished product cyclone recovery unit. The material inlet of the high-temperature finished product cyclone recovery unit is connected to the lower material outlet of the second cyclone furnace section via a pipeline. The gas outlet of the high-temperature finished product cyclone recovery unit is connected to the material inlet of the fourth cyclone recovery unit via a pipeline.

[0012] Furthermore, the low-grade phosphate rock calcination process system also includes a first cooling system, a second cooling system, and a finished product silo;

[0013] The first cooling system includes a first cyclone cooler, a second cyclone cooler, and a second bag filter. The material outlet of the high-temperature finished product cyclone collector is connected to the material inlet of the first cyclone cooler via a pipeline. The material outlet of the first cyclone cooler is connected to the material inlet of the second cyclone cooler via a pipeline. The gas outlet of the second cyclone cooler is connected to the material inlet of the first cyclone cooler via a pipeline. The gas outlet of the first cyclone cooler is connected to the material inlet of the second bag filter via a pipeline.

[0014] The second cooling system includes a third cyclone cooler and a third bag filter. The material outlets of the second cyclone cooler and the second bag filter are connected to the material inlet of the third cyclone cooler via pipelines. The gas outlet of the third cyclone cooler is connected to the material inlet of the third bag filter via pipelines. The material outlets of the third cyclone cooler and the third bag filter are connected to the finished product silo via pipelines.

[0015] Furthermore, the magnesium oxide dry desulfurization system includes a desulfurizing agent silo, a desulfurization conveying screw, a desulfurization conveying fan, and a desulfurizing agent spray gun. The material outlet of the desulfurizing agent silo is connected to the material inlet of the desulfurization conveying screw. The material outlet of the desulfurization conveying screw is connected to the material inlet of the desulfurization conveying fan via a pipeline. The material outlet of the desulfurization conveying fan is connected to the material inlet of the desulfurizing agent spray gun via a pipeline. The desulfurizing agent spray gun is installed in the conveying pipeline between the gas outlet of the second cyclone recoverer and the material inlet of the first cyclone recoverer.

[0016] Furthermore, the urea denitrification system includes a denitrification agent silo, a denitrification conveying screw, a denitrification conveying blower, and the denitrification agent spray gun. The material outlet of the denitrification agent silo is connected to the material inlet of the denitrification conveying screw, the material outlet of the denitrification conveying screw is connected to the material inlet of the denitrification conveying blower through a pipeline, and the material outlet of the denitrification conveying blower is connected to the material inlet of the denitrification agent spray gun through a pipeline.

[0017] This utility model has the following advantages:

[0018] This embodiment provides a low-grade phosphate rock calcination process system that utilizes a vortex kiln instead of the rotary kiln or fluidized bed kiln in existing technologies. The vortex kiln is stationary; the high-temperature flue gas inside the kiln drives the material in a spiral centrifugal motion. During this motion, the material decomposes. Fine particles, due to lower centrifugal force, move further away from the kiln wall, while larger particles, under the influence of gravity and centrifugal force, move closer to the kiln wall at a slower speed than smaller particles. This relative speed difference and trajectory perfectly solve the problem of agglomeration and adhesion to the wall. In addition to the effect of the hot flue gas, the large particles are also subjected to radiant heat from the high-temperature kiln wall, ensuring complete decomposition. The decomposed coarse particles undergo an explosion phenomenon, resulting in smaller particles after the explosion. The material is rapidly carried away by hot air, coarse particles continue to decompose and explode until they are completely decomposed, small particles decompose rapidly in a short stroke, and large particles decompose slowly by adhering to the wall. The above-mentioned decomposition process is completed rapidly in 5-12 seconds. Overall, it solves a series of problems in the existing technology, such as equipment wear, particle sensitivity, over-burning, under-burning, and agglomeration and wall adhesion. The rapid calcination and decomposition can also produce ultra-high activity magnesium oxide and calcium oxide products. Through the added magnesium oxide dry desulfurization system, magnesium oxide dry powder is injected into the preheating system to eliminate sulfides in the low-temperature flue gas to be discharged, thus completing desulfurization. Through the added urea denitrification system, urea is injected during calcination and decomposition to eliminate nitrogen oxides produced by combustion of fuel gas, thus completing denitrification.

[0019] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of this application will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0022] Figure 1 A schematic diagram of a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0023] Figure 2 A schematic diagram of the feeding system of a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0024] Figure 3 A schematic diagram of the preheating system of a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0025] Figure 4 A schematic diagram of the calcination system of a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0026] Figure 5 A schematic diagram of the structure of a magnesium oxide dry desulfurization system in a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0027] Figure 6 A schematic diagram of the structure of a urea denitrification system in a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0028] Figure 7 A schematic diagram of the structure of the first cooling system of a low-grade phosphate rock calcination process system provided for an embodiment of this utility model;

[0029] Figure 8 This is a schematic diagram of the structure of the second cooling system of a low-grade phosphate rock calcination process system provided in an embodiment of the present invention.

[0030] In the diagram: 1. Feeding system; 11. Raw material silo; 12. Rotary scale; 2. Preheating system; 21. First cyclone collector; 22. Second cyclone collector; 23. Third cyclone collector; 24. Fourth cyclone collector; 25. First bag filter; 26. Dust collection powder silo; 3. Calcination system; 31. Cyclone flotation kiln; 311. High-temperature combustion chamber; 312. First stage of cyclone flotation furnace; 313. Second stage of cyclone flotation furnace; 32. High-temperature finished product cyclone collector; 4. Magnesium oxide dry desulfurization system; 41. Desulfurizing agent silo; 42. Desulfurization conveying screw; 43. Desulfurization conveying fan; 44. Desulfurizing agent spray gun; 5. Urea denitrification system; 51. Denitrification agent silo; 52. Denitrification conveying screw; 53. Denitrification conveying fan; 54. Denitrification agent spray gun; 6. First cooling system; 61. First cyclone cooler; 62. Second cyclone cooler; 63. Second bag filter; 7. Second cooling system; 71. Third cyclone cooler; 72. Third bag filter; 8. Finished product silo. Detailed Implementation

[0031] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This embodiment provides a low-grade phosphate rock calcination process system to solve the following problems: 1. Incomplete decomposition or over-calcination of dolomite; 2. Poor activity of magnesium oxide and calcium oxide; 3. Sensitivity to material particle size; 4. High energy consumption; 5. Material sticking to the wall; 6. Desulfurization and denitrification of tail gas.

[0033] like Figures 1 to 8 As shown, the low-grade phosphate rock calcination process system includes a feeding system 1, a preheating system 2, and a calcination system 3 connected in sequence by pipelines. The preheating system 2 includes a first cyclone collector 21 and a first bag filter 25. The gas outlet of the first cyclone collector 21 is connected to the material inlet of the first bag filter 25 by pipelines. The low-grade phosphate rock calcination process system also includes a magnesium oxide dry desulfurization system 4 and a urea denitrification system 5. The calcination system 3 includes a cyclone flotation kiln 31. The material outlet of the preheating system 2 is connected to the material inlet of the cyclone flotation kiln 31 by pipelines. The material outlet of the magnesium oxide dry desulfurization system 4 is connected to the material inlet of the first cyclone collector 21 by pipelines. The material outlet of the urea denitrification system 5 is connected to the cyclone flotation kiln 31 by pipelines.

[0034] The feeding system 1 includes a raw material silo 11 and a rotor scale 12. The material outlet of the raw material silo 11 is connected to the material inlet of the rotor scale 12 through a pipeline, and the material outlet of the rotor scale 12 is connected to the material inlet of the first cyclone recovery unit 21 through a pipeline.

[0035] The preheating system 2 also includes a second cyclone collector 22, a third cyclone collector 23, a fourth cyclone collector 24, and a dust collection powder silo 26. The material outlet of the first cyclone collector 21 is connected to the material inlet of the second cyclone collector 22 via a pipeline; the material outlet of the second cyclone collector 22 is connected to the material inlet of the third cyclone collector 23 via a pipeline; the material outlet of the third cyclone collector 23 is connected to the material inlet of the fourth cyclone collector 24 via a pipeline; and the material outlet of the fourth cyclone collector 24 is connected to the material inlet of the first cyclone collector 21 via a pipeline. The gas outlet of the fourth cyclone collector 24 is connected to the material inlet of the third cyclone collector 23 via a pipeline. The gas outlet of the third cyclone collector 23 is connected to the material inlet of the second cyclone collector 22 via a pipeline. The gas outlet of the second cyclone collector 22 is connected to the material inlet of the first cyclone collector 21 via a pipeline. The material outlet of the first bag filter 25 is connected to the material inlet of the dust collection powder silo 26 via a pipeline. The material outlet of the dust collection powder silo 26 is connected to the material inlet of the third cyclone collector 23 via a pipeline.

[0036] The cyclone kiln 31 includes a high-temperature combustion chamber 311, a first section 312 of the cyclone furnace connected to the high-temperature combustion chamber 311, and a second section 313 of the cyclone furnace connected to the first section 312. The first section 312 and the second section 313 of the cyclone furnace are arranged vertically, and their tops are connected. The first section 312 of the cyclone furnace is equipped with a guide screw for guiding the material to undergo a spiral centrifugal curve motion. The material outlet of the preheating system 2 is connected to the material inlet at the lower end of the first section 312 of the cyclone furnace through a pipe. The material outlet of the urea denitrification system 5 is connected to the upper urea inlet of the first stage 312 of the cyclone furnace. A denitrification agent spray gun 54 is installed in the upper urea inlet of the first stage 312 of the cyclone furnace. The low-grade phosphate rock calcination process system also includes a high-temperature finished product cyclone recovery unit 32. The material inlet of the high-temperature finished product cyclone recovery unit 32 is connected to the lower material outlet of the second stage 313 of the cyclone furnace through a pipeline. The gas outlet of the high-temperature finished product cyclone recovery unit 32 is connected to the material inlet of the fourth cyclone recovery unit 24 through a pipeline.

[0037] The low-grade phosphate rock calcination process system also includes a first cooling system 6, a second cooling system 7, and a finished product silo 8;

[0038] The first cooling system 6 includes a first cyclone cooler 61, a second cyclone cooler 62, and a second bag filter 63. The material outlet of the high-temperature finished product cyclone recoverer 32 is connected to the material inlet of the first cyclone cooler 61 through a pipeline. The material outlet of the first cyclone cooler 61 is connected to the material inlet of the second cyclone cooler 62 through a pipeline. The gas outlet of the second cyclone cooler 62 is connected to the material inlet of the first cyclone cooler 61 through a pipeline. The gas outlet of the first cyclone cooler 61 is connected to the material inlet of the second bag filter 63 through a pipeline.

[0039] The second cooling system 7 includes a third cyclone cooler 71 and a third bag filter 72. The material outlet of the second cyclone cooler 72 and the material outlet of the second bag filter 73 are connected to the material inlet of the third cyclone cooler 71 through pipelines. The gas outlet of the third cyclone cooler 71 is connected to the material inlet of the third bag filter 72 through pipelines. The material outlet of the third cyclone cooler 71 and the material outlet of the third bag filter 72 are connected to the finished product silo 8 through pipelines.

[0040] The magnesium oxide dry desulfurization system 4 includes a desulfurizing agent silo 41, a desulfurization conveying screw 42, a desulfurization conveying fan 43, and a desulfurizing agent spray gun 44. The material outlet of the desulfurizing agent silo 41 is connected to the material inlet of the desulfurization conveying screw 42. The material outlet of the desulfurization conveying screw 42 is connected to the material inlet of the desulfurization conveying fan 43 through a pipeline. The material outlet of the desulfurization conveying fan 43 is connected to the material inlet of the desulfurizing agent spray gun 44 through a pipeline. The desulfurizing agent spray gun 44 is installed in the conveying pipeline between the gas outlet of the second cyclone recoverer 22 and the material inlet of the first cyclone recoverer 21.

[0041] The urea denitrification system 5 includes a denitrification agent silo 51, a denitrification conveying screw 52, ​​a denitrification conveying blower 53, and a denitrification agent spray gun 54. The material outlet of the denitrification agent silo 51 is connected to the material inlet of the denitrification conveying screw 52. The material outlet of the denitrification conveying screw 52 is connected to the material inlet of the denitrification conveying blower 53 through a pipeline. The material outlet of the denitrification conveying blower 53 is connected to the material inlet of the denitrification agent spray gun 54 through a pipeline.

[0042] This embodiment provides a working principle for a low-grade phosphate rock calcination process system as follows:

[0043] 1. Phosphate ore containing dolomite is preheated upon feeding. Raw materials with a particle size of 0-30mm enter a preheating system consisting of four cyclone separators and one baghouse dust collector. In the preheating system, the material is preheated from room temperature to approximately 650℃, simultaneously evaporating trace amounts of moisture. The heat source for preheating comes from a portion of the hot flue gas generated by the calcination system. Before the flue gas enters the baghouse dust collector, dry magnesium oxide powder is sprayed at a temperature of 200-250℃. The magnesium oxide reacts chemically with sulfides in the flue gas, thereby eliminating sulfides in the tail gas. The product formed after the sulfides are absorbed by the magnesium oxide is magnesium sulfate. Magnesium sulfate is recovered by the baghouse dust collector and mixed into the final product, which can be used to prepare fertilizer. The flue gas after passing through the baghouse dust collector is discharged into the atmosphere or used for other heat utilization.

[0044] 2. Low-grade phosphate rock containing dolomite, preheated to about 650℃, enters a cyclone flotation kiln to decompose the dolomite. The kiln body is stationary, and the movement of high-temperature flue gas inside the kiln drives the movement of materials. The decomposition reaction temperature is controlled by controlling the temperature of the high-temperature flue gas. When the decomposition temperature is not greater than 1050℃, the phosphate rock will not decompose, but the dolomite (a mixture of calcium carbonate and magnesium carbonate in a certain proportion) will decompose. During decomposition, the material moves in a spiral centrifugal curve within the kiln. The material decomposes during this motion. Specifically, fine particles, due to their lower centrifugal force, move further away from the kiln wall (i.e., closer to the center), while larger particles, under the influence of gravity and centrifugal force, move closer to the kiln wall at a slower speed. This relative speed difference and trajectory perfectly solves the problem of agglomeration and adhesion to the wall. In addition to being affected by the hot flue gas, the large particles are also subjected to radiant heat from the high-temperature kiln wall. Under the combined effect of these two types of heat, the large particles will completely decompose (the decomposed coarse particles will explode, and the small particles after the explosion will be quickly carried away by the hot air, while the coarse particles continue to decompose and explode until complete decomposition). Small particles decompose rapidly over a short stroke, while large particles decompose slowly against the wall. This entire decomposition process is completed rapidly within 5-12 seconds. Thus, it perfectly solves a series of problems in existing technologies, such as equipment wear, particle sensitivity, over-burning, under-burning, and agglomeration and adhesion to the wall. Rapid calcination and decomposition also yields ultra-high activity magnesium oxide and calcium oxide products. Highly active calcium oxide and magnesium oxide are extremely needed in the production of fertilizer from phosphate rock.

[0045] The outlet of the cyclone kiln is connected to a high-temperature finished product cyclone recovery unit. The material recovered by the high-temperature finished product cyclone recovery unit is mixed with natural cooling air to complete the material cooling process. The cooling section is divided into two stages. The first stage is the preheating air heating stage, where the non-decomposed phosphate rock and the decomposed high-activity calcium oxide, magnesium oxide, and other high-temperature materials heat the natural air to about 600°C. The air, after being purified by a bag filter, enters the gas combustion system to provide oxygen for gas combustion, resulting in energy savings of over 20%. After the first cooling (heating of natural air), the finished material (about 300°C) exchanges heat with natural air again and is recovered through a cyclone cooler and a bag filter (the recovered product is about 60°C) as raw material for subsequent fertilizer production processes. The exhaust gas can also be used as an auxiliary heat source for fertilizer production heating.

[0046] 3. During the calcination reaction (temperature range 850-1050℃), urea granules are sprayed to eliminate nitrogen oxides produced by the combustion of fuel gas. The sprayed urea and the products of urea and nitrogen oxides can be used as raw materials for phosphate rock fertilizer production.

[0047] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A low-grade phosphate rock calcination process system, comprising a feeding system (1), a preheating system (2), and a calcination system (3) connected sequentially by pipelines, wherein the preheating system (2) comprises a first cyclone separator (21) and a first bag filter (25), the gas outlet of the first cyclone separator (21) being connected to the material inlet of the first bag filter (25) by pipelines, characterized in that, The low-grade phosphate rock calcination process system also includes a magnesium oxide dry desulfurization system (4) and a urea denitrification system (5). The calcination system (3) includes a cyclone kiln (31). The material outlet of the preheating system (2) is connected to the material inlet of the cyclone kiln (31) through a pipeline. The material outlet of the magnesium oxide dry desulfurization system (4) is connected to the material inlet of the first cyclone recovery unit (21) through a pipeline. The material outlet of the urea denitrification system (5) is connected to the cyclone kiln (31) through a pipeline.

2. The low-grade phosphate rock calcination process system according to claim 1, characterized in that, The feeding system (1) includes a raw material bin (11) and a rotor scale (12). The material outlet of the raw material bin (11) is connected to the material inlet of the rotor scale (12) through a pipeline, and the material outlet of the rotor scale (12) is connected to the material inlet of the first cyclone recoverer (21) through a pipeline.

3. The low-grade phosphate rock calcination process system according to claim 1, characterized in that, The preheating system (2) further includes a second cyclone recoverer (22), a third cyclone recoverer (23), a fourth cyclone recoverer (24), and a dust collection powder silo (26). The material outlet of the first cyclone recoverer (21) is connected to the material inlet of the second cyclone recoverer (22) via a pipeline. The material outlet of the second cyclone recoverer (22) is connected to the material inlet of the third cyclone recoverer (23) via a pipeline. The material outlet of the third cyclone recoverer (23) is connected to the material inlet of the fourth cyclone recoverer (24) via a pipeline. The material outlet of the fourth cyclone recoverer (24) is connected to the material inlet of the first cyclone recoverer (21). The inlet is connected by a pipeline. The gas outlet of the fourth cyclone collector (24) is connected to the material inlet of the third cyclone collector (23) by a pipeline. The gas outlet of the third cyclone collector (23) is connected to the material inlet of the second cyclone collector (22) by a pipeline. The gas outlet of the second cyclone collector (22) is connected to the material inlet of the first cyclone collector (21) by a pipeline. The material outlet of the first bag filter (25) is connected to the material inlet of the dust collection powder silo (26) by a pipeline. The material outlet of the dust collection powder silo (26) is connected to the material inlet of the third cyclone collector (23) by a pipeline.

4. The low-grade phosphate rock calcination process system according to claim 3, characterized in that, The cyclone kiln (31) includes a high-temperature combustion chamber (311), a first section (312) of the cyclone furnace connected to the high-temperature combustion chamber (311), and a second section (313) of the cyclone furnace connected to the first section (312). The first section (312) and the second section (313) of the cyclone furnace are arranged vertically, and their tops are connected. The first section (312) of the cyclone furnace is equipped with a guide screw for guiding the material to perform a spiral centrifugal curve motion. The material outlet of the preheating system (2) is connected to the material inlet at the lower end of the first section (312) of the cyclone furnace. The material outlet of the urea denitrification system (5) is connected to the upper urea inlet of the first stage of the cyclone furnace (312) via a pipeline. A denitrification agent spray gun (54) is installed in the upper urea inlet of the first stage of the cyclone furnace (312). The low-grade phosphate rock calcination process system also includes a high-temperature finished product cyclone recovery unit (32). The material inlet of the high-temperature finished product cyclone recovery unit (32) is connected to the lower material outlet of the second stage of the cyclone furnace (313) via a pipeline. The gas outlet of the high-temperature finished product cyclone recovery unit (32) is connected to the material inlet of the fourth cyclone recovery unit (24) via a pipeline.

5. The low-grade phosphate rock calcination process system according to claim 4, characterized in that, The low-grade phosphate rock calcination process system also includes a first cooling system (6), a second cooling system (7), and a finished product silo (8); The first cooling system (6) includes a first cyclone cooler (61), a second cyclone cooler (62), and a second bag filter (63). The material outlet of the high-temperature finished product cyclone recoverer (32) is connected to the material inlet of the first cyclone cooler (61) through a pipeline. The material outlet of the first cyclone cooler (61) is connected to the material inlet of the second cyclone cooler (62) through a pipeline. The gas outlet of the second cyclone cooler (62) is connected to the material inlet of the first cyclone cooler (61) through a pipeline. The gas outlet of the first cyclone cooler (61) is connected to the material inlet of the second bag filter (63) through a pipeline. The second cooling system (7) includes a third cyclone cooler (71) and a third bag filter (72). The material outlet of the second cyclone cooler (62) and the material outlet of the second bag filter (63) are connected to the material inlet of the third cyclone cooler (71) through pipelines. The gas outlet of the third cyclone cooler (71) is connected to the material inlet of the third bag filter (72) through pipelines. The material outlet of the third cyclone cooler (71) and the material outlet of the third bag filter (72) are connected to the finished product silo (8) through pipelines.

6. The low-grade phosphate rock calcination process system according to claim 3, characterized in that, The magnesium oxide dry desulfurization system (4) includes a desulfurizing agent silo (41), a desulfurization conveying screw (42), a desulfurization conveying fan (43), and a desulfurizing agent spray gun (44). The material outlet of the desulfurizing agent silo (41) is connected to the material inlet of the desulfurization conveying screw (42). The material outlet of the desulfurization conveying screw (42) is connected to the material inlet of the desulfurization conveying fan (43) through a pipeline. The material outlet of the desulfurization conveying fan (43) is connected to the material inlet of the desulfurizing agent spray gun (44) through a pipeline. The desulfurizing agent spray gun (44) is installed in the conveying pipeline between the gas outlet of the second cyclone recoverer (22) and the material inlet of the first cyclone recoverer (21).

7. The low-grade phosphate rock calcination process system according to claim 4, characterized in that, The urea denitrification system (5) includes a denitrification agent silo (51), a denitrification conveying screw (52), a denitrification conveying blower (53), and a denitrification agent spray gun (54). The material outlet of the denitrification agent silo (51) is connected to the material inlet of the denitrification conveying screw (52). The material outlet of the denitrification conveying screw (52) is connected to the material inlet of the denitrification conveying blower (53) through a pipeline. The material outlet of the denitrification conveying blower (53) is connected to the material inlet of the denitrification agent spray gun (54) through a pipeline.

Images