Method and system for fluidized roasting of ground phosphate rock

Abstract

Aiming at the problem of low product strength caused by large porosity in a phosphorite pellet roasting method, the invention discloses a method and a system for fluidized roasting of powdered rock phosphate, and utilizes the technical characteristics that low-grade high-calcium phosphorite pellets are easy to generate pores in the roasting process and the pores can be filled with powdered rock phosphate. Phosphorite micro-powder is added in the middle and later periods of fluidized roasting of the phosphorite pellets for mixed roasting, so that the phosphorite micro-powder is filled into pores of the phosphorite pellets and is fused and attached with the phosphorite pellets into a whole, and the compressive strength of the roasted phosphorite pellets can be remarkably improved; accurate and efficient roasting of low-grade high-calcium phosphate rock powder is met, and the requirement for subsequent pyrogenic process smelting of phosphate rock can be met. The method and the system have the advantages of simple overall process flow, low production cost, compact equipment structure, easiness in control, high production efficiency, stable product quality, high resource utilization rate, convenience in popularization and application and the like.

Description

Technical Field

[0001] The present invention relates to a roasting process of phosphate rock powder, in particular to a method and system for fluidized roasting of phosphate rock powder, belonging to the technical field of phosphate rock powder roasting. Background Art

[0002] While my country boasts abundant phosphate rock reserves, high-grade phosphate rock reserves are relatively low. 70% of the phosphate rock is of medium- to low-grade (W(P2O5) <20%), making it difficult to directly utilize. While these vast phosphate rock reserves have enabled the rapid development of phosphorus chemical companies, production process limitations have resulted in significant amounts of low-grade phosphorus-containing solid waste. Currently, there are no adequate disposal methods for these two types of phosphorus-containing materials, requiring only stockpiling. This not only consumes significant land resources but also poses significant safety risks due to their acid solubility.

[0003] Fluidized bed roasting is a suitable process for processing low-grade phosphate rock. Compared to bulk roasting, its high-temperature reaction rate constant can increase by approximately 80 to 330 times, or even more. However, low-grade phosphate rock typically has not only a low phosphorus grade but also a high calcium carbonate content (W(CaCO3)>30%). High-temperature roasting is often used to remove the calcium carbonate and thus improve the phosphorus grade. Fluidized bed roasting is a suitable method for processing low-grade phosphate rock. During the high-temperature fluidized bed roasting process, the decomposition rate and activity of carbonates are significantly improved, and the phosphorus grade of the phosphate rock is also improved to a certain extent. However, the carbonate decomposition process also easily creates porosity in the phosphate rock pellets, which reduces the compressive strength and makes them unsuitable for subsequent phosphate pyrometallurgical refining. Summary of the Invention

[0004] In view of the problem in the prior art that the phosphate ore pellet roasting method has a large porosity and leads to low product strength, the present invention provides a method and system for fluidized roasting of phosphate rock powder. By adding phosphate rock powder in the middle and late stages of fluidized roasting of phosphate rock pellets for mixed roasting, the phosphate rock powder is filled into the pores of the phosphate rock pellets and fused with the phosphate rock pellets, thereby significantly improving the compressive strength of the phosphate rock pellets after roasting, thereby meeting the requirements of subsequent phosphate rock pyrometallurgy.

[0005] In order to achieve the above technical objectives, the technical solutions adopted by the present invention are as follows:

[0006] According to a first embodiment of the present invention, a method for fluidized roasting of phosphate rock powder is provided:

[0007] A method for fluidizing and roasting phosphate rock powder, comprising the following steps:

[0008] 1) The phosphate rock powder is divided into two parts, one of which is granulated to obtain phosphate rock pellets, and the other is ground to obtain phosphate rock fine powder.

[0009] 2) Fluidized roasting of the phosphate rock pellets, and adding phosphate rock powder in the middle and late stages of roasting for fluidized mixed roasting, to obtain phosphate rock pellets after roasting.

[0010] Preferably, the phosphate rock powder is calcium carbonate-containing phosphate rock powder. Preferably, the calcium carbonate content in the phosphate rock powder is not less than 20% by weight, more preferably not less than 30% by weight. Preferably, the phosphorus grade (calculated as phosphorus pentoxide by weight) of the phosphate rock powder is not more than 25%, more preferably not more than 20%.

[0011] Preferably, the particle size of the phosphate rock pellets is 1 to 5 mm, preferably 1.5 to 4.5 mm, and more preferably 2 to 4 mm.

[0012] Preferably, the particle size of the phosphate rock powder is ≤0.05 mm, preferably ≤0.045 mm, and more preferably ≤0.037 mm.

[0013] Preferably, the temperature during fluidized roasting of the phosphate ore pellets is 600-1400°C, preferably 800-1300°C, and more preferably 900-1200°C. The duration of fluidized roasting of the phosphate ore pellets is 10-200 minutes, preferably 20-80 minutes. Preferably, the gas fluidization velocity during fluidized roasting of the phosphate ore pellets is 0.5-5 m / s.

[0014] Preferably, the temperature during fluidized mixed roasting with the addition of phosphate rock powder is 400-1200°C, preferably 600-1000°C. The duration of the fluidized mixed roasting with the addition of phosphate rock powder is 5-100 minutes, preferably 10-50 minutes. Preferably, the gas fluidization velocity during the fluidized mixed roasting with the addition of phosphate rock powder is 0.2-3 m / s. It should be noted that the fluidizing gas used in the fluidized roasting and fluidized mixed roasting is oxygen and / or air, preferably air.

[0015] According to a second embodiment of the present invention, a system for fluidized roasting of phosphate rock powder is provided:

[0016] A system for fluidized roasting of phosphate rock powder or a system used in the method described in the first embodiment comprises a fluidized furnace tube and a partition. The partition is disposed within the lumen of the fluidized furnace tube and divides the lumen into an upper chamber and a lower chamber, wherein the diameter of the upper chamber is larger than that of the lower chamber. A material inlet is provided in the upper chamber or the lower chamber. A fluidizing gas inlet and a fluidizing gas outlet are provided at the bottom and top of the lower chamber, respectively. The partition is provided with a through hole.

[0017] Preferably, the partition includes a fixed plate and a movable plate. The fixed plate is fixedly installed between the upper chamber and the lower chamber and has an opening in the middle thereof. The movable plate is movably installed in the opening, and the through hole is provided on the movable plate.

[0018] Preferably, a plurality of openings are provided on the fixed plate, and a movable plate is independently installed in each opening.

[0019] Preferably, the plurality of openings are symmetrically distributed on both sides of the fixed plate surface or are evenly distributed along the circumference of the fixed plate surface with the center of the fixed plate as the center of the circle. Preferably, when the plurality of openings are evenly distributed along the circumference of the fixed plate surface with the center of the fixed plate as the center of the circle, the area of ​​the fixed plate body reserved between any two adjacent openings in the circumferential direction of the fixed plate surface is not less than the opening area of ​​the openings.

[0020] Preferably, the opening is one of a circular opening, a rectangular opening, a polygonal opening, and a fan-shaped opening, preferably a fan-shaped opening.

[0021] Preferably, one end of the movable plate is hinged to the fixed plate at the edge of the opening through a hinge, and the movable plate rotates through the hinge to open and close the opening.

[0022] Preferably, the direction in which the movable plate rotates through the hinge is a vertical direction or a circumferential direction along the surface of the fixed plate.

[0023] Preferably, the hinge comprises a shaft and a shaft tube. The shaft tube is fixed horizontally on a fixed plate at the edge of the opening, and an arc-shaped notch is provided in the middle of the shaft tube wall to communicate with the tube cavity thereof. The shaft is sleeved in the shaft tube and can rotate freely in the shaft tube. The two ends of the shaft extend horizontally through the tube wall of the fluidized bed furnace tube and then extend to the outside. The end of the movable plate is connected to the shaft rod body that leaks out of the arc-shaped notch. By rotating the shaft, the movable plate is rotated in the vertical direction with its end close to the shaft as the rotation center, thereby realizing the opening and closing operation of the opening.

[0024] Preferably, the hinge comprises a shaft and a shaft tube. The shaft tube is fixed vertically on the fixed plate at the edge of the opening, and an arc-shaped notch connected to its lumen is provided at the bottom of the tube wall of the shaft tube. The bottom end of the shaft rod extends into the shaft tube and can rotate freely in the shaft tube. The top of the shaft rod extends upward to the top wall of the fluidized bed furnace tube and then extends to the outside. The end of the movable plate is connected to the shaft rod body leaking out of the arc-shaped notch. By rotating the shaft rod, the movable plate is rotated along the circumference of the plate surface of the fixed plate with its end close to the shaft rod as the rotation center, thereby realizing the opening and closing operation of the opening. Preferably, the fixed plate is a convex plate-like structure with a high center and low surroundings.

[0025] Preferably, a gas-powder inlet is provided in the middle or lower portion of the upper chamber. Preferably, the gas-powder inlet is tangentially connected to the upper chamber. Preferably, the gas-powder inlet is oriented horizontally or obliquely upward. Preferably, multiple gas-powder inlets are evenly distributed circumferentially and / or axially around the upper chamber.

[0026] Preferably, a supplementary heating device is provided on the upper chamber and / or the lower chamber, and the supplementary heating device is an electric heater (such as an electric heating rod, an electric heating plate, an electric heating tube, an electric heating wire, etc.) or a microwave heater.

[0027] The present invention addresses the drawback of fluidized roasting of low-grade, high-calcium phosphate rock pellets, which can easily generate pores and result in low product strength. The low-grade, high-calcium phosphate rock is split, with the majority of the phosphate rock powder being prepared into pellets and a smaller portion being prepared into -0.045mm phosphate rock fine powder. During the roasting process, the phosphate rock pellets develop pores as carbonates decompose. The fine phosphate rock is then sprayed into the pellets under the influence of an airflow and attached to them, filling the pores. The pellets, now filled with the fine phosphate rock, continue to roast in a furnace tube. Because the fine phosphate rock easily forms a liquid phase at high temperatures, it fuses well with the pellets, significantly improving the compressive strength of the pellets and meeting the requirements of subsequent phosphate rock pyrometallurgy.

[0028] In the present invention, a portion of the phosphate rock powder is formed into phosphate rock pellets (for example, by forcefully mixing with a binder such as bentonite or water for granulation, preferably at a liquid-to-solid ratio of 7 to 12:1 (for example, 9:1), followed by drying at 80 to 200°C (for example, 120°C) for 0.5 to 2 hours (for example, 40 minutes) to obtain dried phosphate rock pellets). This can meet the requirements of the fluidized pellet roasting process for low-grade phosphate rock powder. Further grinding the remaining portion of the phosphate rock powder into phosphate rock fine powder can increase the specific gravity difference between the phosphate rock powder and the phosphate rock pellets, facilitating the attachment and filling of the phosphate rock fine powder into the pores created by carbonate decomposition in the phosphate rock pellets during subsequent mixing and roasting. Furthermore, the finer particle size of the phosphate rock fine powder is more easily converted to a liquid phase at high temperatures, thereby increasing the filling rate of the phosphate rock pellet pores and better integrating with the phosphate rock pellets, thereby significantly improving the compressive strength of the roasted phosphate rock pellets. After research, it was found that when the process of the present invention is used for fluidized roasting of phosphate ore pellets, a particle size of the phosphate ore powder ≤ 0.05 mm (preferably ≤ 0.045 mm, more preferably ≤ 0.037 mm) has a better effect on enhancing the strength of the roasted phosphate ore pellets.

[0029] In the present invention, phosphate ore pellets and phosphate ore fine powder are fluidized and roasted using a specially designed fluidized roasting system. This system is primarily achieved by modifying an existing fluidized roasting furnace tube: a baffle with through holes is installed in the tube lumen of the fluidized furnace tube, dividing the tube into different zones from top to bottom. During the roasting process, due to the weight of the phosphate ore pellets and the effect of the baffle, the fluidized roasting of the phosphate ore pellets primarily occurs in the lower portion of the fluidized furnace tube. Once the carbonates in the phosphate ore pellets are substantially decomposed, the baffle is opened to allow the phosphate ore pellets to enter the upper portion of the tube for mixing and roasting with the phosphate ore fine powder.

[0030] In the present invention, phosphate ore pellets and phosphate ore powder are first introduced simultaneously into the roasting system from the top of a furnace tube. Fluidizing gas enters from the bottom of the furnace tube. Because the inner cavity of the fluidizing furnace tube is larger at the top and smaller at the bottom, the phosphate ore pellets, with their higher specific gravity, are suspended in the lower portion of the furnace tube, where the gas fluidization velocity is higher, while the phosphate ore powder, with its lower specific gravity, remains in the upper portion of the furnace tube, where the gas fluidization velocity is lower. The phosphate ore pellets undergo a roasting reaction in the lower portion of the furnace tube, where the carbonates decompose to create pores, thereby improving the phosphorus grade and strength of the phosphate ore pellets. After the carbonates are completely decomposed, the partition in the middle of the furnace tube is opened, and the gas fluidization velocity is increased to blow the phosphate ore pellets to the upper portion of the furnace tube. (During the roasting process, the top discharge port of the furnace is closed, the phosphate ore pellets are suspended in the upper portion of the furnace tube, while the phosphate ore powder tumbles, ensuring full contact with the phosphate ore pellets without being blown out of the furnace.) In the upper portion of the furnace tube, which is filled with phosphate rock fine powder, the pores of the phosphate rock pellets are fully filled with the fine powder, which fuses tightly with the pellets under high temperature, eliminating the strength defects caused by the presence of pores. This method utilizes the technical characteristics of low-grade, high-calcium phosphate rock pellets, which are prone to pores during the roasting process and can be filled by phosphate rock fine powder. By diverting the material and modifying the furnace tube, this method solves the problem of insufficient compressive strength of the phosphate rock pellets after roasting. It achieves the precise and efficient roasting of low-grade, high-calcium phosphate rock powder, significantly improving resource utilization.

[0031] In this invention, fluidizing gas is introduced from the bottom of the furnace tube, and phosphate ore pellets are added to the fluidized furnace tube. Under the influence of gravity and a baffle, the phosphate ore pellets undergo fluidized roasting in the lower portion of the furnace tube. The perforated baffle not only confines the phosphate ore pellets without hindering the passage of fluidizing gas, but also effectively prevents the phosphate ore pellets from entering the upper low-temperature zone due to the decrease in specific gravity caused by carbonate decomposition, thereby affecting roasting quality and efficiency.

[0032] Furthermore, the present invention designs the fluidized bed furnace tube with a larger upper section and smaller lower section. This allows for the natural formation of an upper low-speed roasting zone and a lower high-speed roasting zone within the fluidized bed furnace tube, without changing the flow rate and velocity of the fluidizing gas at the bottom. After the phosphate ore pellets undergo high-temperature roasting in the lower high-speed roasting zone, which essentially decomposes the carbonates, they are able to pass through the openings in the baffles and remain suspended in the upper low-speed roasting zone due to their reduced mass. This facilitates rapid and efficient fusion with the phosphate ore fine powder in the upper section. By eliminating the need for separate air velocity control in the upper and lower sections of the furnace tube, the process operation is significantly simplified, significantly improving production efficiency.

[0033] In the present invention, the baffles comprise fixed plates and movable plates. For example, in a furnace tube with a circular cross-section, the baffles are generally in the shape of a circular pancake. The fixed plates are pancake-shaped with multiple openings in the middle, while the movable plates are plate-shaped structures that conform to the openings. The movable plates are movably mounted (typically hinged) within the openings, with the openings controlled by relative rotation. The movable plates are provided with smaller through-holes on their surface for airflow.

[0034] In the present invention, the plurality of openings can be evenly distributed on both sides of the fixed plate surface, with the diameter of the fixed plate serving as the dividing line, or can be evenly distributed along the horizontal circumference. Preferably, the fixed plate is a convex plate structure with a higher center and lower peripheries. This upward concave flow guide design facilitates the smooth passage of phosphate ore pellets from the lower portion of the furnace tube into the upper portion of the furnace tube when the movable plate rotates to open the openings.

[0035] In the present invention, the movable plate is hinged to the fixed plate at the edge of the opening via a hinge, that is, the hinge allows the movable plate to flip in the vertical direction or rotate in a staggered manner in the circumferential direction of the fixed plate to achieve the opening and closing control of the opening. The hinge includes a shaft and a shaft tube, the shaft tube is fixed to the fixed plate, and the shaft rod is movably sleeved in the tube cavity of the shaft tube. At the same time, an arc-shaped notch is opened on the tube wall of the shaft tube so that the shaft rod body at this location can be exposed and fixedly connected to the end of the movable plate. When the shaft rod is rotated, the movable plate can be rotated synchronously, thereby allowing the movable plate to open and close the opening. Generally, when multiple openings are evenly distributed on both sides of the plate surface of the fixed plate with the diameter of the fixed plate as the dividing line, the shaft tube and the shaft rod are both arranged horizontally, and the two ends of the shaft rod penetrate the tube wall of the fluidized bed furnace tube and extend to the outside. By rotating the shaft rod, the movable plate can be flipped in the vertical direction relative to the opening. When multiple openings are designed to be evenly distributed along the circumferential direction of the fixed plate, the shaft tube and the shaft rod are both vertically arranged, and the top end of the shaft rod extends upward to the outside of the fluidized furnace tube. By rotating the shaft rod, the movable plate can be staggered and rotated relative to the opening in the circumferential direction of the fixed plate.

[0036] In the present invention, a gas-powder inlet is provided in the middle portion of the fluidized furnace tube (i.e., the middle or lower portion of the upper chamber). Phosphate ore powder is introduced into the fluidized furnace tube through the gas-powder inlet for mixing and roasting with the phosphate ore pellets entering the upper region of the tube. Preferably, the gas-powder inlet is oriented horizontally or tangentially upwardly in communication with the inner cavity of the tube. This allows the introduced phosphate ore powder to form a swirling flow, thereby improving the collision and adhesion efficiency between the phosphate ore powder and the phosphate ore pellets.

[0037] Furthermore, in the present invention, a supplementary heating device is provided on the upper part (upper chamber) and / or the lower part (lower chamber) of the fluidized furnace tube, and a supplementary heating device (such as an electric heating rod, an electric heating plate, an electric heating tube, an electric heating wire or a microwave heater, etc.) is mainly provided in the middle part of the upper chamber. Since the heat carried by the airflow in the lower part of the fluidized furnace tube is mainly used for roasting the phosphate ore pellets in the lower part, the temperature of the fluidized gas will decrease after entering the upper part of the furnace tube, which is not conducive to the liquefaction of the phosphate ore powder. Therefore, the liquefaction efficiency of the phosphate ore powder can be improved by adding a supplementary heating device.

[0038] In the present invention, it should be noted that the diameter of the through-hole is smaller than the diameter of the phosphate ore pellets, preferably less than 3 mm, more preferably less than 2 mm, and even more preferably less than 1 mm, for example, 0.1 to 0.9 mm. The diameter of the opening is larger than the diameter of the phosphate ore pellets, preferably 0.1 to 100 cm, more preferably 0.3 to 50 cm, and even more preferably 0.5 to 30 cm. The diameter of the lower chamber is 0.1 to 30 m, preferably 0.2 to 20 m, and even more preferably 0.3 to 10 m. The diameter of the upper chamber is 0.2 to 40 m, preferably 0.3 to 25 m, and even more preferably 0.4 to 15 m. Furthermore, the diameter of the upper chamber gradually increases from bottom to top.

[0039] Compared with the prior art, the present invention has the following beneficial technical effects:

[0040] 1: The present invention utilizes the technical feature that low-grade, high-calcium phosphate ore pellets are prone to generate pores during the roasting process, and phosphate ore fine powder can fill the pores. By mixing and roasting the phosphate ore pellets with phosphate ore fine powder in the middle and late stages of fluidized roasting, the phosphate ore fine powder will be melted and filled in the pores of the phosphate ore pellets, thereby solving the problem of insufficient compressive strength of the pellets after roasting, realizing the precise and efficient roasting of low-grade, high-calcium phosphate rock powder, and greatly improving resource utilization.

[0041] 2: The method and system of the present invention have a simple overall process flow, low production cost, compact equipment structure, easy control, high production efficiency, stable product quality, and are easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the process of the roasting method of the present invention.

[0043] Figure 2 Schematic diagram of the structure of the system of the present invention.

[0044] Figure 3 This is a schematic structural diagram of the system of the present invention when it has a heat supplement device.

[0045] Figure 4 This is a schematic top view of the structure of the movable plates according to the present invention distributed along the circumferential direction of the fixed plate surface.

[0046] Figure 5 It is a schematic diagram of the lateral partial cross-sectional structure of the movable plates of the present invention when distributed circumferentially along the surface of the fixed plate.

[0047] Figure 6 This is a schematic diagram of the lateral structure when the fixing plate of the present invention is a convex plate design.

[0048] Figure 7 This is a schematic top view of the structure in which the movable plates of the present invention are symmetrically distributed on the surface of the fixed plate.

[0049] Figure 8 This is a schematic diagram of the lateral partial structure when the movable plates of the present invention are symmetrically distributed on the surface of the fixed plate.

[0050] Figure 9 It is a schematic diagram of the lateral partial cross-sectional structure when the movable plates of the present invention are symmetrically distributed on the surface of the fixed plate.

[0051] Figure 10 This is a cross-sectional view of the phosphate rock green pellets obtained in Example 22 of the present invention.

[0052] Figure 11 This is a cross-sectional view of the finished phosphate rock pellets obtained in Example 22 of the present invention.

[0053] Figure 12 This is a microscopic morphology image of the phosphate rock powder obtained in Example 22 of the present invention, magnified 5000 times.

[0054] Figure 13 This is a microscopic morphology image of the phosphate rock powder obtained in Example 22 of the present invention, magnified 15,000 times.

[0055] Figure 14 This is a physical photo of the phosphate rock pellets obtained in Example 22 of the present invention.

[0056] Figure 15 This is a physical photo of the finished phosphate rock pellets obtained in Example 22 of the present invention.

[0057] Figure 16 This is a physical photo of the finished phosphate rock pellets obtained in Comparative Example 1 of the present invention.

[0058] Figure numerals: 1: fluidizing furnace tube; 101: upper chamber; 102: lower chamber; 103: material inlet; 104: fluidizing gas inlet; 105: fluidizing gas outlet; 106: gas powder inlet; 2: partition; 201: through hole; 202: fixed plate; 203: movable plate; 204: opening; 3: hinge; 301: shaft; 302: shaft tube; 303: arc-shaped notch; 4: heat supplement device. DETAILED DESCRIPTION

[0059] The technical solutions of the present invention are illustrated below with examples, and the scope of protection requested by the present invention includes but is not limited to the following embodiments.

[0060] A system for fluidized roasting of phosphate rock powder includes a fluidized furnace tube 1 and a partition 2. The partition 2 is disposed within the lumen of the fluidized furnace tube 1 and divides the lumen into an upper chamber 101 and a lower chamber 102, wherein the diameter of the upper chamber 101 is larger than that of the lower chamber 102. A material inlet 103 is provided in the upper chamber 101 or the lower chamber 102. A fluidizing gas inlet 104 and a fluidizing gas outlet 105 are provided at the bottom and top of the lower chamber 102, respectively. A through hole 201 is formed in the partition 2.

[0061] Preferably, the partition 2 includes a fixed plate 202 and a movable plate 203. The fixed plate 202 is fixedly installed between the upper chamber 101 and the lower chamber 102 and has an opening 204 in the middle. The movable plate 203 is movably installed in the opening 204. The through hole 201 is opened on the movable plate 203.

[0062] Preferably, a plurality of openings 204 are provided on the fixed plate 202 , and a movable plate 203 is independently installed in each opening 204 .

[0063] Preferably, the plurality of openings 204 are symmetrically distributed on both sides of the surface of the fixed plate 202 or are evenly distributed along the circumference of the surface of the fixed plate 202 with the center of the fixed plate 202 as the center. Preferably, when the plurality of openings 204 are evenly distributed along the circumference of the surface of the fixed plate 202 with the center of the fixed plate 202 as the center, the area of ​​the fixed plate 202 reserved between any two adjacent openings 204 along the circumferential direction of the surface of the fixed plate 202 is not less than the opening area of ​​the opening 204.

[0064] Preferably, the opening 204 is a circular opening, a rectangular opening, a polygonal opening, or a fan-shaped opening, preferably a fan-shaped opening.

[0065] Preferably, one end of the movable plate 203 is hinged to the fixed plate 202 at the edge of the opening 204 via a hinge 3 . The movable plate 203 is rotated via the hinge 3 to open and close the opening 204 .

[0066] Preferably, the direction in which the movable plate 203 rotates through the hinge 3 is a vertical direction or a circumferential direction along the surface of the fixed plate 202 .

[0067] Preferably, the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is horizontally fixed to the fixed plate 202 at the edge of the opening 204, and an arc-shaped notch 303 connected to its lumen is provided in the middle of the tube wall of the shaft tube 302. The shaft 301 is sleeved in the shaft tube 302 and can rotate freely in the shaft tube 302. The two ends of the shaft 301 extend horizontally through the tube wall of the fluidized bed furnace tube 1 and then extend to the outside. The end of the movable plate 203 is connected to the shaft body of the shaft 301 that leaks out of the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 is rotated in the vertical direction with its end close to the shaft 301 as the rotation center, thereby realizing the opening and closing operation of the opening 204.

[0068] Preferably, the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is fixed vertically on the fixed plate 202 at the edge of the opening 204, and the bottom of the tube wall of the shaft tube 302 is provided with an arc-shaped notch 303 connected to its tube cavity. The bottom end of the shaft 301 extends into the shaft tube 302 and can rotate freely in the shaft tube 302. The top of the shaft 301 extends upward to the top wall of the fluidized bed furnace tube 1 and then extends to the outside. The end of the movable plate 203 is connected to the shaft body of the shaft 301 that leaks out of the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 is rotated along the circumference of the plate surface of the fixed plate 202 with its end close to the shaft 301 as the rotation center, thereby realizing the opening and closing operation of the opening 204. Preferably, the fixed plate 202 is a convex plate-shaped structure with a high center and low surroundings.

[0069] Preferably, a gas-powder inlet 106 is further provided in the middle or lower portion of the upper chamber 101. Preferably, the gas-powder inlet 106 is tangentially connected to the upper chamber 101. Preferably, the gas-powder inlet 106 is oriented horizontally or obliquely upward. Preferably, multiple gas-powder inlets 106 are evenly distributed along the circumference and / or axial direction of the upper chamber 101.

[0070] Preferably, a supplementary heating device 4 is further provided on the upper chamber 101 and / or the lower chamber 102 , and the supplementary heating device 4 is an electric heater or a microwave heater.

[0071] Example 1

[0072] like Figure 2-9As shown, a system for fluidized roasting of phosphate rock powder includes a fluidized furnace tube 1 and a partition 2. The partition 2 is disposed within the lumen of the fluidized furnace tube 1 and divides the lumen into an upper chamber 101 and a lower chamber 102, wherein the diameter of the upper chamber 101 is larger than that of the lower chamber 102. A material inlet 103 is provided in the upper chamber 101 or the lower chamber 102. A fluidizing gas inlet 104 and a fluidizing gas outlet 105 are provided at the bottom and top of the lower chamber 102, respectively. A through hole 201 is formed in the partition 2.

[0073] Example 2

[0074] Repeat Example 1, except that the partition plate 2 includes a fixed plate 202 and a movable plate 203. The fixed plate 202 is fixedly installed between the upper chamber 101 and the lower chamber 102 and has an opening 204 in the middle. The movable plate 203 is movably installed in the opening 204, and the through hole 201 is opened on the movable plate 203.

[0075] Example 3

[0076] The second embodiment is repeated, except that a plurality of openings 204 are provided on the fixed plate 202 , and a movable plate 203 is independently installed in each opening 204 .

[0077] Example 4

[0078] Repeat Example 3, as Figure 7-9 As shown, the plurality of openings 204 are symmetrically distributed on both sides of the plate surface of the fixing plate 202 .

[0079] Example 5

[0080] Repeat Example 4, except that one end of the movable plate 203 is hinged to the fixed plate 202 at the edge of the opening 204 via a hinge 3. The movable plate 203 rotates via the hinge 3 to open and close the opening 204. The direction in which the movable plate 203 rotates via the hinge 3 is vertical.

[0081] Example 6

[0082] Repeat Example 5, except that the hinge 3 includes a shaft rod 301 and a shaft tube 302. The shaft tube 302 is fixed horizontally on the fixed plate 202 at the edge of the opening 204, and an arc-shaped notch 303 connected to its tube cavity is provided in the middle of the tube wall of the shaft tube 302. The shaft rod 301 is sleeved in the shaft tube 302 and can rotate freely in the shaft tube 302. The two ends of the shaft rod 301 extend horizontally through the tube wall of the fluidized bed furnace tube 1 and then extend to the outside. The end of the movable plate 203 is connected to the shaft rod 301 that leaks out at the arc-shaped notch 303. By rotating the shaft rod 301, the movable plate 203 is rotated in the vertical direction with its end close to the shaft rod 301 as the rotation center, thereby realizing the opening and closing operation of the opening 204.

[0083] Example 7

[0084] Repeat Example 3, as Figure 4-6 As shown, a plurality of openings 204 are evenly distributed along the circumference of the plate surface of the fixing plate 202 with the center of the fixing plate 202 as the center of the circle.

[0085] Example 8

[0086] Repeat Example 7, except that when multiple openings 204 are evenly distributed along the circumference of the plate surface of the fixed plate 202 with the center of the fixed plate 202 as the center of the circle, in the circumferential direction of the plate surface of the fixed plate 202, the plate area of ​​the fixed plate 202 reserved between any two adjacent openings 204 is not less than the opening area of ​​the opening 204.

[0087] Example 9

[0088] Example 8 is repeated, except that one end of the movable panel 203 is hinged to the fixed panel 202 at the edge of the opening 204 via a hinge 3. The movable panel 203 rotates via the hinge 3 to open and close the opening 204. The direction in which the movable panel 203 rotates via the hinge 3 is along the circumferential direction of the fixed panel 202.

[0089] Example 10

[0090] Repeat Example 9, except that the hinge 3 includes a shaft rod 301 and a shaft tube 302. The shaft tube 302 is fixed in a vertical position on the fixed plate 202 at the edge of the opening 204, and the bottom of the tube wall of the shaft tube 302 is provided with an arc-shaped notch 303 connected to its tube cavity. The bottom end of the shaft rod 301 extends into the shaft tube 302 and can rotate freely in the shaft tube 302. The top of the shaft rod 301 extends upward to the top wall of the fluidized bed furnace tube 1 and then extends to the outside world. The end of the movable plate 203 is connected to the shaft rod 301 that leaks out at the arc-shaped notch 303. By rotating the shaft rod 301, the movable plate 203 is rotated along the circumference of the plate surface of the fixed plate 202 with its end close to the shaft rod 301 as the rotation center, thereby realizing the opening and closing operation of the opening 204.

[0091] Example 11

[0092] Example 10 is repeated, except that the fixing plate 202 is a convex plate-shaped structure with a high center and low surroundings.

[0093] Example 12

[0094] Example 11 is repeated, except that the opening 204 is a rectangular opening.

[0095] Example 13

[0096] Example 11 is repeated, except that the opening 204 is a polygonal opening.

[0097] Example 14

[0098] Example 11 is repeated, except that the opening 204 is a fan-shaped opening.

[0099] Example 15

[0100] Repeat Example 14, as Figure 2 As shown, a gas-powder inlet 106 is provided at the lower portion of the upper chamber 101 .

[0101] Example 16

[0102] Example 15 was repeated, except that the gas-powder inlet 106 was tangentially connected to the upper chamber 101 .

[0103] Example 17

[0104] Example 16 was repeated, except that the gas-powder inlet 106 was oriented horizontally.

[0105] Example 18

[0106] Example 16 was repeated, except that the gas-powder inlet 106 was oriented obliquely upward.

[0107] Example 19

[0108] Example 18 is repeated, except that the plurality of gas-powder inlets 106 are evenly distributed along the circumference and axial direction of the upper chamber 101 .

[0109] Example 20

[0110] Example 19 is repeated, except that a supplementary heating device 4 is further provided on the upper chamber 101 and the lower chamber 102, and the supplementary heating device 4 is an electric heating plate.

[0111] Example 21

[0112] Example 19 is repeated, except that a supplementary heating device 4 is further provided on the upper chamber 101 and the lower chamber 102, and the supplementary heating device 4 is a microwave heater.

[0113] Example 22

[0114] The system described in Example 21 was used to roast high-calcium phosphate rock powder:

[0115] 80% of the phosphate rock powder with a phosphorus grade of about 19.2% (calculated as P2O5) and a calcium carbonate content of about 33.35% is granulated by a granulator to obtain phosphate rock pellets with a particle size of about 2 mm, and the remaining 20% ​​of the phosphate rock powder is ground by a grinder and passed through a 400-mesh sieve to obtain phosphate rock fine powder (particle size not greater than 0.037 mm).

[0116] Fluidizing gas (air) is introduced into the fluidizing furnace tube 1 through the fluidizing gas inlet 104, and phosphate ore pellets are added from the material inlet 103. The flow rate of the fluidizing gas is adjusted (about 2.5 m / s) so that the phosphate ore pellets are suspended in the lower chamber 102 for oxidation roasting. The oxidation roasting temperature is 900°C and the oxidation roasting time is 21 minutes (during this process, the movable plate 203 is always covered on the opening 204 of the fixed plate 202). The fluidizing gas enters the upper chamber 101 through the through hole 201 and is discharged through the fluidizing gas outlet 105.

[0117] After the oxidation roasting is completed, the shaft 301 of the hinge 3 rotates within the shaft tube 302, thereby rotating the movable plate 203 away from the opening 204, directly connecting the upper chamber 101 and the lower chamber 102 through the opening 204. The fluidizing gas flow rate is increased (approximately 3 m / s), allowing the phosphate ore pellets to enter the upper chamber 101 through the opening 204 and become suspended therein. Phosphate ore fine powder is then added to the upper chamber 101 through the gas-powder inlet 106 for mixed roasting. The mixed roasting temperature is 700°C, and the mixed roasting time is 12 minutes. During the mixed roasting process, the phosphate ore fine powder continuously adheres to and fuses with the phosphate ore pellets, ultimately producing high-grade, high-strength finished phosphate ore pellets. Testing shows that the finished phosphate ore pellets have a phosphorus grade of approximately 28.7%, a uniform morphology free of damage and pores, and an average compressive strength of approximately 2082 N (tested in accordance with GB / T 14201-2018).

[0118] Comparative Example 1

[0119] The phosphate rock powder with a phosphorus grade of about 19.2% (calculated as P2O5) and a calcium carbonate content of about 33.35% is granulated by a granulator to obtain phosphate rock pellets with a particle size of about 2 mm.

[0120] Fluidizing gas (air) is introduced into the fluidizing furnace tube 1 through the fluidizing gas inlet 104. Phosphate ore pellets are added through the material inlet 103. The fluidizing gas flow rate is adjusted (approximately 2.5 m / s) to suspend the phosphate ore pellets in the lower chamber 102 for oxidation roasting. The oxidation roasting temperature is 900°C and the oxidation roasting time is 30 minutes (during this process, the movable plate 203 always covers the opening 204 of the fixed plate 202). The fluidizing gas enters the upper chamber 101 through the through hole 201 and is discharged through the fluidizing gas outlet 105. After oxidation roasting, the finished phosphate ore pellets are obtained. Testing shows that the phosphorus grade of the finished phosphate ore pellets is approximately 29.5%, the morphology is uneven, with obvious damage and a large amount of pores, and the average compressive strength is approximately 2135N.

Claims

1. A method for fluidizing and roasting phosphate rock powder, characterized in that: The method comprises the following steps: 1) Divide the phosphate rock powder into two parts, granulate one part to obtain phosphate rock pellets, and grind the other part to obtain phosphate rock fine powder; 2) Fluidized roasting of the phosphate rock pellets, and adding phosphate rock powder in the middle and late stages of roasting for fluidized mixed roasting, to obtain phosphate rock pellets after roasting.

2. The method according to claim 1, wherein: The phosphate rock powder is phosphate rock powder containing calcium carbonate; preferably, the mass content of calcium carbonate in the phosphate rock powder is not less than 20%, preferably not less than 30%; preferably, the phosphorus grade of the phosphate rock powder is not higher than 25%, preferably not higher than 20%.

3. The method according to claim 1 or 2, characterized in that: The particle size of the phosphate rock pellets is 1 to 5 mm, preferably 1.5 to 4.5 mm, more preferably 2 to 4 mm; and / or The particle size of the phosphate rock powder is ≤0.05 mm, preferably ≤0.045 mm, and more preferably ≤0.037 mm.

4. The method according to any one of claims 1 to 3, characterized in that: The temperature during fluidized roasting of the phosphate ore pellets is 600-1400° C., preferably 800-1300° C., and more preferably 900-1200° C.; the time for fluidized roasting of the phosphate ore pellets is 10-200 min, preferably 20-80 min; preferably, the gas fluidization velocity during fluidized roasting of the phosphate ore pellets is 0.5-5 m / s.

5. The method according to any one of claims 1 to 4, characterized in that: The temperature when adding phosphate rock fine powder for fluidized mixed roasting is 400~1200℃, preferably 600~1000℃; the time for adding phosphate rock fine powder for fluidized mixed roasting is 5~100min, preferably 10~50min; preferably, the gas fluidization velocity when adding phosphate rock fine powder for fluidized mixed roasting is 0.2~3m / s.

6. A system for fluidized roasting of phosphate rock powder or a system for the method according to any one of claims 1 to 5, characterized in that: The system comprises a fluidizing furnace tube (1) and a partition (2); the partition (2) is arranged in the tube cavity of the fluidizing furnace tube (1) and divides the tube cavity of the fluidizing furnace tube (1) into an upper chamber (101) and a lower chamber (102), wherein the diameter of the upper chamber (101) is larger than the diameter of the lower chamber (102); a material inlet (103) is provided on the upper chamber (101) or the lower chamber (102); a fluidizing gas inlet (104) and a fluidizing gas outlet (105) are respectively provided at the bottom and top of the lower chamber (102); and a through hole (201) is opened on the partition (2).

7. The system according to claim 6, characterized in that: The partition (2) comprises a fixed plate (202) and a movable plate (203); the fixed plate (202) is fixedly installed between the upper chamber (101) and the lower chamber (102), and has an opening (204) in the middle thereof; the movable plate (203) is movably installed in the opening (204); and the through hole (201) is provided on the movable plate (203); Preferably, a plurality of openings (204) are provided on the fixed plate (202), and a movable plate (203) is independently installed in each opening (204); Preferably, the plurality of openings (204) are symmetrically distributed on both sides of the plate surface of the fixed plate (202) or are evenly distributed along the circumference of the plate surface of the fixed plate (202) with the center of the fixed plate (202) as the center of the circle; preferably, when the plurality of openings (204) are evenly distributed along the circumference of the plate surface of the fixed plate (202) with the center of the fixed plate (202) as the center of the circle, in the circumferential direction of the plate surface of the fixed plate (202), the plate body area of ​​the fixed plate (202) reserved between any two adjacent openings (204) is not less than the opening area of ​​the opening (204); Preferably, the opening (204) is one of a circular opening, a rectangular opening, a polygonal opening, and a fan-shaped opening, preferably a fan-shaped opening.

8. The system according to claim 7, characterized in that: One end of the movable plate (203) is hinged to the fixed plate (202) at the edge of the opening (204) through a hinge (3); the movable plate (203) is rotated through the hinge (3) to open and close the opening (204); Preferably, the direction in which the movable plate (203) rotates via the hinge (3) is a vertical direction or a circumferential direction along the surface of the fixed plate (202).

9. The system according to claim 8, characterized in that: The hinge (3) comprises a shaft (301) and a shaft tube (302); the shaft tube (302) is horizontally fixed on a fixed plate (202) at the edge of the opening (204), and an arc-shaped notch (303) communicating with the tube cavity of the shaft tube (302) is provided in the middle of the tube wall of the shaft tube (302); the shaft (301) is sleeved in the shaft tube (302) and can rotate freely in the shaft tube (302), and both ends of the shaft (301) extend horizontally through the tube wall of the fluidized bed furnace tube (1) and then extend to the outside; the end of the movable plate (203) is connected to the shaft (301) body exposed at the arc-shaped notch (303); by rotating the shaft (301), the movable plate (203) is rotated in the vertical direction with its end close to the shaft (301) as the rotation center, thereby realizing the opening and closing operation of the opening (204); and / or The hinge (3) includes a shaft (301) and a shaft tube (302); the shaft tube (302) is fixed vertically on the fixing plate (202) at the edge of the opening (204), and the bottom of the tube wall of the shaft tube (302) is provided with an arc-shaped notch (303) communicating with the tube cavity thereof; the bottom end of the shaft rod (301) extends into the shaft tube (302) and can rotate freely in the shaft tube (302), and the top end of the shaft rod (301) extends upward to the fluidized furnace tube ( 1) extends to the outside; the end of the movable plate (203) is connected to the shaft (301) that leaks out of the arc-shaped notch (303); by rotating the shaft (301), the movable plate (203) is rotated along the circumference of the plate surface of the fixed plate (202) with its end close to the shaft (301) as the rotation center, thereby realizing the opening and closing operation of the opening (204); preferably, the fixed plate (202) is a convex plate-shaped structure with a high center and low surroundings.

10. The system according to any one of claims 6 to 9, characterized in that: A gas-powder inlet (106) is further provided in the middle or lower portion of the upper chamber (101); preferably, the gas-powder inlet (106) is tangentially connected to the upper chamber (101); preferably, the gas-powder inlet (106) is oriented horizontally or obliquely upward; preferably, a plurality of the gas-powder inlets (106) are evenly distributed along the circumference and / or axial direction of the upper chamber (101); Preferably, a supplementary heating device (4) is further provided on the upper chamber (101) and / or the lower chamber (102), and the supplementary heating device (4) is an electric heater or a microwave heater.

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