A system for fluidized roasting of phosphate rock fines

Abstract

The utility model discloses a kind of phosphorite powder fluidized roasting systems, two chambers are divided into by hole partition plate to flow state furnace tube, the early-stage roasting of phosphorite pellet is realized separately in lower chamber, mixed roasting of phosphorite pellet and phosphorite micro powder is realized in upper chamber, that is, mixed roasting in middle and late period of phosphorite pellet roasting and phosphorite micro powder, phosphorite micro powder can be filled into the porosity of phosphorite pellet and fused with phosphorite pellet, can significantly improve the compressive strength of phosphorite pellet after roasting, meet the accurate, efficient roasting of low-grade high-calcium phosphorite powder and can meet the requirement of subsequent phosphorite pyrometallurgy.The system of the utility model has the advantages of simple overall structure, low production cost, compact equipment structure, easy to control, high production efficiency, stable product quality, high resource utilization rate and easy to popularize and apply.

Description

Technical Field

[0001] This utility model relates to the roasting process of phosphate rock powder, specifically to a fluidized bed roasting system for phosphate rock powder, and belongs to the field of phosphate rock powder roasting technology. Background Technology

[0002] Although my country has abundant phosphate rock reserves, high-grade phosphate rock reserves are relatively low, with 70% being medium- to low-grade (W(P2O5) < 20%) phosphate rock that is difficult to utilize directly. The vast phosphate rock reserves have ensured the rapid development of phosphate chemical enterprises, but due to limitations in production processes, a large amount of low-grade phosphorus-containing solid waste is generated. There are currently no proper disposal processes for these two types of phosphorus-containing materials, and they are currently mainly stored, which not only occupies a large amount of land resources but also poses significant safety hazards due to the soluble nature of phosphorus-containing materials in acids.

[0003] Fluidized bed roasting is one of the suitable processes for processing low-grade phosphate rock powder. Compared with packed bed roasting, its reaction rate constant can increase by about 80 to 330 times, or even more, at high temperatures. However, low-grade phosphate rock powder generally 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 calcium carbonate, thereby improving the phosphorus grade. Fluidized bed microsphere roasting is a suitable approach for processing low-grade phosphate rock powder. 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 powder is also improved to a certain extent. However, during the carbonate decomposition process, the phosphate rock microspheres are also prone to porosity, which reduces the compressive strength of the microspheres and does not meet the requirements of subsequent pyrometallurgical phosphate rock processing. Utility Model Content

[0004] To address the problem of low product strength due to high porosity in existing phosphate rock pellet roasting methods, this invention provides a fluidized bed roasting system for phosphate rock powder. This system divides the fluidized bed furnace tube into upper and lower chambers using a perforated partition. The lower chamber alone performs the initial roasting of the phosphate rock pellets, while the upper chamber performs the mixed roasting of the phosphate rock pellets and phosphate rock powder. Specifically, by adding phosphate rock powder during the middle and later stages of fluidized bed roasting, the phosphate rock powder fills the pores of the phosphate rock pellets and fuses with them, significantly improving the compressive strength of the roasted phosphate rock pellets and thus meeting the requirements of subsequent pyrometallurgical phosphate rock processing.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by this utility model is as follows: A system for fluidized bed roasting of phosphate rock powder includes a fluidized bed furnace tube and a baffle plate. The baffle plate is disposed within the cavity of the fluidized bed furnace tube, dividing the cavity into an upper chamber and a lower chamber, wherein the diameter of the upper chamber is larger than the diameter of the lower chamber. A material inlet is provided in either the upper or lower chamber. A fluidizing gas inlet and a fluidizing gas outlet are respectively provided at the bottom and top of the lower chamber. Through holes are formed in the baffle plate.

[0006] 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 its middle. The movable plate is movably installed in the opening, and the through hole is formed on the movable plate.

[0007] Preferably, multiple openings are provided on the fixed plate, and a movable plate is independently installed in each opening.

[0008] Preferably, the multiple openings are symmetrically distributed on both sides of the fixed plate or evenly distributed around the center of the fixed plate along the circumference of the fixed plate. Preferably, when the multiple openings are evenly distributed around the center of the fixed plate along the circumference of the fixed plate, the area of ​​the fixed plate reserved between any two adjacent openings in the circumferential direction of the fixed plate surface is not less than the opening area of ​​the opening.

[0009] Preferably, the opening is one of a circular opening, a rectangular opening, a polygonal opening, or a fan-shaped opening, with a fan-shaped opening being the most preferred.

[0010] Preferably, one end of the movable plate is hinged to the fixed plate at the edge of the opening via a hinge. The movable plate rotates via the hinge to open and close the opening.

[0011] Preferably, the movable plate rotates in the vertical direction or along the circumferential direction of the fixed plate surface via the hinge.

[0012] Preferably, the hinge includes a shaft and a tube. The tube is horizontally fixed to a fixed plate at the edge of the opening, and an arc-shaped notch communicating with its cavity is formed in the middle of the tube wall. The shaft is sleeved in the tube and can rotate freely within it. Both ends of the shaft extend horizontally through the tube wall of the fluidized bed furnace tube and then outwards. The end of the movable plate is connected to the shaft body protruding from the arc-shaped notch. By rotating the shaft, the movable plate rotates vertically with its end closest to the shaft as the center of rotation, thereby achieving the opening and closing operation of the opening.

[0013] Preferably, the hinge includes a shaft and a tube. The tube is vertically fixed to a fixed plate at the edge of the opening, and an arc-shaped notch communicating with its cavity is formed at the bottom of the tube wall. The bottom end of the shaft extends into the tube and can rotate freely within it, while the top of the shaft extends upward to the top wall of the fluidized bed furnace tube and then outward. The end of the movable plate is connected to the shaft protruding from the arc-shaped notch. By rotating the shaft, the movable plate rotates circumferentially around the fixed plate with its end closest to the shaft as the center of rotation, thereby achieving the opening and closing operation of the opening. Preferably, the fixed plate is a convex plate structure with a high center and low periphery.

[0014] Preferably, an air-powder inlet is provided in the middle or lower part of the upper chamber. Preferably, the air-powder inlet is tangentially connected to the upper chamber. Preferably, the air-powder inlet is oriented horizontally or inclined upwards. Preferably, a plurality of air-powder inlets are evenly distributed along the circumference and / or axial direction of the upper chamber.

[0015] Preferably, a heating device is also provided on the upper chamber and / or lower chamber, wherein the heating device is an electric heater (e.g., an electric heating rod, an electric heating plate, an electric heating tube, an electric heating wire, etc.) or a microwave heater.

[0016] The process of fluidized bed roasting of phosphate rock powder using the system described in this invention is as follows: 1) Divide the phosphate rock powder into two parts. One part is granulated to obtain phosphate rock pellets, and the other part is ground to obtain phosphate rock micro powder.

[0017] 2) Fluidized roasting of phosphate rock pellets, and adding phosphate rock powder in the middle and late stages of roasting for fluidized mixing and roasting, resulting in phosphate rock pellets after roasting.

[0018] 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 mass, more preferably not less than 30%. Preferably, the phosphorus grade (referring to the mass content calculated as phosphorus pentoxide) of the phosphate rock powder is not higher than 25%, more preferably not higher than 20%.

[0019] Preferably, the particle size of the phosphate rock pellets is 1-5 mm, more preferably 1.5-4.5 mm, and even more preferably 2-4 mm.

[0020] Preferably, the particle size of the phosphate rock powder is ≤0.05mm, more preferably ≤0.045mm, and even more preferably ≤0.037mm.

[0021] Preferably, the temperature for fluidized bed roasting of the phosphate rock pellets is 600~1400℃, more preferably 800~1300℃, and even more preferably 900~1200℃. The duration of fluidized bed roasting of the phosphate rock pellets is 10~200 min, preferably 20~80 min. Preferably, the gas fluidization velocity during fluidized bed roasting of the phosphate rock pellets is 0.5~5 m / s.

[0022] Preferably, the temperature for fluidized bed roasting with added phosphate rock powder is 400~1200℃, more preferably 600~1000℃. The duration of fluidized bed roasting with added phosphate rock powder is 5~100 min, more preferably 10~50 min. Preferably, the gas fluidization velocity during fluidized bed roasting with added phosphate rock powder is 0.2~3 m / s. It should be noted that the fluidizing gas used in fluidized bed roasting and fluidized bed roasting is oxygen and / or air, preferably air.

[0023] In this invention, the drawback of low-grade, high-calcium phosphate rock powder pellets, which tend to generate pores and result in low product strength, is addressed by dividing the low-grade, high-calcium phosphate rock powder. Most of the powder is prepared into pellets, while a smaller portion is prepared into 0.045mm micro-powder. During roasting, the phosphate rock pellets generate pores due to the decomposition of carbonates. The micro-powder is then sprayed into the pellets under airflow, filling the pores. The pellets, now filled with micro-powder, continue roasting in the furnace tube. Because the micro-powder readily forms a liquid phase at high temperatures, it integrates well with the pellets, significantly improving the compressive strength of the pellets and meeting the requirements of subsequent pyrometallurgical phosphate rock processing.

[0024] In this invention, a portion of the phosphate rock powder is made into phosphate rock pellets (e.g., by strong mixing and granulation with a binder such as bentonite or water, preferably using a liquid-to-solid ratio of 7~12:1 (e.g., 9:1) to mix the phosphate rock powder and water for strong mixing and granulation, followed by drying at 80~200℃ (e.g., 120℃) for 0.5~2h (e.g., 40min) to obtain dried phosphate rock pellets). This satisfies the requirements of the fluidized bed granulation process for low-grade phosphate rock powder. Further grinding another portion of the phosphate rock powder into phosphate rock micropowder increases the specific gravity difference between the micropowder and the phosphate rock pellets, facilitating the micropowder's adhesion and filling of the pores created by carbonate decomposition during subsequent mixing and calcination. Simultaneously, the finer particle size of the micropowder allows it to easily transform into a liquid phase at high temperatures, thus improving the filling rate of the pores and enabling better integration with the phosphate rock pellets, thereby significantly improving the compressive strength of the calcined phosphate rock pellets. Research has shown that when using the process of this invention for fluidized bed roasting of phosphate rock pellets, a particle size of phosphate rock powder ≤0.05mm (preferably ≤0.045mm, more preferably ≤0.037mm) has a better effect on enhancing the strength of the roasted phosphate rock pellets.

[0025] In this invention, the fluidized bed roasting of phosphate rock pellets and phosphate rock powder is carried out using a specially designed fluidized bed roasting system. This system is mainly obtained by modifying existing fluidized bed roasting furnace tubes: a perforated baffle is installed in the cavity of the fluidized bed furnace tube, dividing the tube into different zones from top to bottom. During the roasting process of the phosphate rock pellets, due to the weight of the pellets and the effect of the baffle, the fluidized bed roasting of the pellets mainly occurs in the lower part of the fluidized bed furnace tube. After the carbonates in the pellets are basically decomposed, the baffle is opened to allow the pellets to enter the upper part of the furnace tube to mix and roast with the phosphate rock powder.

[0026] In this invention, both phosphate rock pellets and phosphate rock powder are simultaneously introduced into the roasting system from the top of the furnace tube. Fluidized gas enters from the bottom of the furnace tube. Due to the larger upper cavity and smaller lower cavity of the fluidized furnace tube, the heavier phosphate rock pellets are suspended in the lower part of the tube where the gas fluidization velocity is high, while the lighter phosphate rock powder remains in the upper part where the gas fluidization velocity is low. The phosphate rock pellets undergo a roasting reaction in the lower part of the furnace tube, where carbonates decompose to create pores, thus improving the phosphorus grade and strength of the pellets. After complete carbonate decomposition, the baffle in the middle of the furnace tube is opened, and the gas fluidization velocity is increased, blowing the phosphate rock pellets to the upper part of the furnace tube. (During the roasting process, the top outlet of the furnace is closed, so the phosphate rock pellets are suspended in the upper part of the furnace tube, while the phosphate rock powder is tumbling, ensuring full contact between the powder and pellets without being blown out of the furnace.) In the upper part of the furnace tube filled with phosphate rock powder, the pores of the phosphate rock pellets are fully filled by the fine powder, which then fuses tightly with the pellets under high temperature, solving the strength defects caused by the presence of pores. This method utilizes the technical characteristic that low-grade, high-calcium phosphate rock pellets are prone to pore formation during roasting, which can be filled by phosphate rock powder. By diverting the material and modifying the furnace tube, the problem of insufficient compressive strength of the phosphate rock pellets after roasting is solved, achieving precise and efficient roasting of low-grade, high-calcium phosphate rock powder and significantly improving resource utilization.

[0027] In this invention, fluidized gas is introduced from the bottom of the furnace tube, and phosphate rock pellets are added into the fluidized furnace tube. Under their own gravity and the action of the baffles, the phosphate rock pellets undergo fluidized roasting in the lower part of the furnace tube. By setting perforated baffles, the flow of fluidized gas can be restricted while the phosphate rock pellets are kept within the confines. Furthermore, this effectively prevents the phosphate rock pellets from entering the upper low-temperature zone due to the decrease in specific gravity caused by carbonate decomposition, thus affecting the roasting effect and efficiency.

[0028] Furthermore, this invention designs the fluidized bed furnace tube with a structure that is larger at the top and smaller at the bottom. This allows for the natural formation of an upper low-velocity roasting zone and a lower high-velocity roasting zone within the furnace tube without altering 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-velocity zone, resulting in near-complete decomposition of the carbonates, their reduced mass allows them to pass through the opening in the baffle and enter the upper low-velocity roasting zone, where they remain suspended. This facilitates rapid and efficient fusion with the phosphate ore powder in the upper region. Since separate velocity control is not required for the upper and lower regions of the furnace tube, the process complexity is significantly reduced, leading to improved production efficiency.

[0029] In this invention, the partition includes a fixed plate and a movable plate. Taking a furnace tube with a circular cross-section as an example, the partition is generally a disc-shaped structure. The fixed plate is a disc-shaped structure with multiple openings in the center, while the movable plate is a plate-shaped structure that matches the opening structure. The movable plate is movably installed (generally hinged) in the opening, meaning that the opening and closing of the opening is controlled by the relative rotation of the movable plate. Small-diameter through holes are formed on the surface of the movable plate to allow airflow.

[0030] In this invention, the multiple openings can be evenly distributed on both sides of the fixed plate with the diameter of the fixed plate as the dividing line, or they can be evenly distributed along the horizontal circumference. Preferably, the fixed plate is a convex plate structure with a high center and low periphery. This concave flow guiding design allows the phosphate ore balls at the bottom of the furnace tube to smoothly pass through the openings and enter the upper part of the furnace tube when the movable plate rotates to open the openings.

[0031] In this invention, the movable plate is hinged to the fixed plate at the edge of the opening via a hinge. The hinge allows the movable plate to flip vertically or rotate in a staggered manner around the fixed plate, thus controlling the opening and closing of the opening. The hinge includes a shaft and a tube. The tube is fixed to the fixed plate, and the shaft is movably fitted into the tube's cavity. An arc-shaped notch is provided on the tube wall, exposing the shaft and fixing it to the end of the movable plate. Rotating the shaft synchronously rotates the movable plate, opening and closing the opening. Generally, when multiple openings are evenly distributed on both sides of the fixed plate with its diameter as the dividing line, both the tube and shaft are horizontally positioned, with both ends of the shaft penetrating the wall of the fluidized bed furnace tube and extending to the outside. Rotating the shaft causes the movable plate to flip vertically relative to the opening. When multiple openings are evenly distributed along the circumference of the fixed plate, both the shaft tube and the shaft rod are vertically set, and the top of the shaft rod extends upward to the outside of the fluidized furnace tube. By rotating the shaft rod, the movable plate can be rotated in a staggered manner relative to the openings in the circumference of the fixed plate.

[0032] In this invention, a gas-powder inlet is provided in the middle of the fluidized bed furnace tube (i.e., the middle or lower part of the upper chamber). Phosphate rock powder is introduced into the fluidized bed furnace tube through the gas-powder inlet to facilitate mixing and roasting with the phosphate rock pellets entering the upper region of the furnace tube. Preferably, the gas-powder inlet is oriented tangentially horizontally or inclined upwards to connect with the inner cavity of the furnace tube, thereby enabling the phosphate rock powder introduced by the gas flow to form a swirling flow, which in turn improves the collision and adhesion efficiency between the phosphate rock powder and the phosphate rock pellets.

[0033] Furthermore, in this invention, a heating device is also provided on the upper part (upper chamber) and / or the lower part (lower chamber) of the fluidized furnace tube. The heating device (such as an electric heating rod, electric heating plate, electric heating tube, electric heating wire or microwave heater, etc.) is mainly provided in the middle of the upper chamber. Since the heat carried by the airflow in the lower part of the fluidized furnace tube is mainly used for the roasting of the lower phosphate ore pellets, the temperature will drop after the fluidized gas enters the upper part of the furnace tube, which is not conducive to the liquefaction of phosphate ore powder. Therefore, by adding a heating device, the liquefaction efficiency of phosphate ore powder can be improved.

[0034] In this invention, it should be noted that the diameter of the through hole is smaller than the diameter of the phosphate rock pellets, preferably less than 3 mm, more preferably less than 2 mm, and even more preferably less than 1 mm, for example, 0.1~0.9 mm. The diameter of the opening is larger than the diameter of the phosphate rock pellets, preferably 0.1~100 cm, more preferably 0.3~50 cm, and even more preferably 0.5~30 cm. The diameter of the lower chamber is 0.1~30 μm, preferably 0.2~20 μm, and even more preferably 0.3~10 μm. The diameter of the upper chamber is 0.2~40 μm, preferably 0.3~25 μm, and even more preferably 0.4~15 μm. Further, the diameter of the upper chamber gradually increases from bottom to top.

[0035] Compared with the prior art, the beneficial technical effects of this utility model are as follows: 1. This utility model achieves independent roasting of phosphate rock pellets and mixed roasting of phosphate rock pellets and phosphate rock powder by partitioning. It makes full use of the technical characteristics that low-grade high-calcium phosphate rock pellets are prone to pores during roasting, and that phosphate rock powder can fill these pores. By mixing and roasting the phosphate rock pellets with phosphate rock powder in the middle and late stages of fluidized bed roasting, the phosphate rock powder will be fused and filled into the pores of the phosphate rock pellets, solving the problem of insufficient compressive strength of the pellets after roasting. This achieves precise and efficient roasting of low-grade high-calcium phosphate rock powder and greatly improves resource utilization.

[0036] 2. The system of this utility model has a simple overall structure, low production cost, compact and easy-to-operate equipment structure, high production efficiency, stable product quality, and is easy to promote and apply. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the system described in this utility model.

[0038] Figure 2 This is a schematic diagram of the system of the present invention when it has a heat replenishment device.

[0039] Figure 3 This is a top view of the structure of the movable plate of the present invention, which is distributed circumferentially along the surface of the fixed plate.

[0040] Figure 4This is a schematic diagram of a partial lateral cross-sectional structure when the movable plate of this utility model is distributed circumferentially along the surface of the fixed plate.

[0041] Figure 5 This is a side structural diagram of the fixing plate of this utility model when it is a convex plate design.

[0042] Figure 6 This is a top view of the structure of the movable plate of this utility model, which is symmetrically distributed on the surface of the fixed plate.

[0043] Figure 7 This is a lateral partial structural diagram of the movable plate of this utility model when it is symmetrically distributed on the surface of the fixed plate.

[0044] Figure 8 This is a schematic diagram of a lateral partial cross-sectional structure of the movable plate of this utility model when it is symmetrically distributed on the surface of the fixed plate.

[0045] Reference numerals in the attached figures: 1: Fluidized bed furnace tube; 101: Upper chamber; 102: Lower chamber; 103: Material inlet; 104: Fluidizing gas inlet; 105: Fluidizing gas outlet; 106: Gas-powder inlet; 2: Baffle plate; 201: Through hole; 202: Fixed plate; 203: Movable plate; 204: Opening; 3: Hinge; 301: Shaft; 302: Shaft tube; 303: Arc-shaped notch; 4: Heating device. Detailed Implementation

[0046] The technical solution of this utility model is illustrated below. The scope of protection of this utility model includes, but is not limited to, the following embodiments.

[0047] A system for fluidized bed roasting of phosphate rock powder includes a fluidized bed furnace tube 1 and a baffle plate 2. The baffle plate 2 is disposed within the cavity of the fluidized bed furnace tube 1, dividing the cavity 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 in either 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. A through hole 201 is formed in the baffle plate 2.

[0048] 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 its middle. The movable plate 203 is movably installed in the opening 204, and the through hole 201 is formed on the movable plate 203.

[0049] 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.

[0050] Preferably, the multiple openings 204 are symmetrically distributed on both sides of the surface of the fixing plate 202 or evenly distributed around the center of the fixing plate 202 along the circumference of the surface of the fixing plate 202. Preferably, when the multiple openings 204 are evenly distributed around the center of the fixing plate 202 along the circumference of the surface of the fixing plate 202, the area of ​​the fixing plate 202 reserved between any two adjacent openings 204 in the circumferential direction of the surface of the fixing plate 202 is not less than the opening area of ​​the opening 204.

[0051] Preferably, the opening 204 is one of a circular opening, a rectangular opening, a polygonal opening, or a fan-shaped opening, and is preferably a fan-shaped opening.

[0052] 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 rotates via the hinge 3 to open and close the opening 204.

[0053] Preferably, the movable plate 203 rotates in the vertical direction or along the circumferential direction of the fixed plate 202 via the hinge 3.

[0054] Preferably, the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is horizontally fixed to a fixing plate 202 at the edge of the opening 204, and an arc-shaped notch 303 communicating with its cavity is provided in the middle of the tube wall. The shaft 301 is sleeved in the shaft tube 302 and can rotate freely in the shaft tube 302. Both ends of the shaft 301 extend horizontally through the tube wall of the fluidized furnace tube 1 and then extend to the outside. The end of the movable plate 203 is connected to the shaft 301 protruding from the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 rotates vertically with its end near the shaft 301 as the center of rotation, thereby realizing the opening and closing operation of the opening 204.

[0055] Preferably, the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is vertically fixed to a fixed plate 202 at the edge of the opening 204, and an arc-shaped notch 303 communicating with its cavity is provided at the bottom of the tube wall. The bottom end of the shaft 301 extends into the shaft tube 302 and can rotate freely within it, while the top of the shaft 301 extends upward to the top wall of the fluidized furnace tube 1 and then outward. The end of the movable plate 203 is connected to the shaft 301 protruding from the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 rotates circumferentially around the fixed plate 202 with its end near the shaft 301 as the center of rotation, thereby realizing the opening and closing operation of the opening 204. Preferably, the fixed plate 202 is a convex plate structure with a high center and low periphery.

[0056] Preferably, an air / powder inlet 106 is further provided in the middle or lower part of the upper chamber 101. Preferably, the air / powder inlet 106 is tangentially connected to the upper chamber 101. Preferably, the air / powder inlet 106 is oriented horizontally or inclined upward. Preferably, a plurality of air / powder inlets 106 are evenly distributed along the circumference and / or axial direction of the upper chamber 101.

[0057] Preferably, a heating device 4 is also provided on the upper chamber 101 and / or the lower chamber 102, wherein the heating device 4 is an electric heater or a microwave heater. Example 1

[0058] like Figure 1-8 As shown, a fluidized bed roasting system for phosphate rock powder includes a fluidized bed furnace tube 1 and a baffle plate 2. The baffle plate 2 is disposed within the cavity of the fluidized bed furnace tube 1, dividing the cavity 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 in either 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. A through hole 201 is provided in the baffle plate 2. Example 2

[0059] The embodiment 1 is repeated, except that 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 its middle. The movable plate 203 is movably installed in the opening 204, and the through hole 201 is formed on the movable plate 203. Example 3

[0060] The embodiment 2 is repeated, except that multiple openings 204 are provided on the fixed plate 202, and a movable plate 203 is independently installed in each opening 204. Example 4

[0061] Repeat Example 3, as follows Figure 7-8 As shown, multiple openings 204 are symmetrically distributed on both sides of the fixed plate 202. Example 5

[0062] The embodiment 4 is repeated, 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. Example 6

[0063] The embodiment 5 is repeated, except that the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is horizontally fixed to the fixing plate 202 at the edge of the opening 204, and an arc-shaped notch 303 communicating with its cavity is opened 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. Both ends of the shaft 301 extend horizontally through the tube wall of the fluidized furnace tube 1 and then extend to the outside. The end of the movable plate 203 is connected to the shaft 301 exposed at the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 rotates vertically with its end near the shaft 301 as the center of rotation, thereby realizing the opening and closing operation of the opening 204. Example 7

[0064] Repeat Example 3, as follows Figure 4-6 As shown, multiple openings 204 are evenly distributed around the center of the fixing plate 202 along the circumference of the plate surface. Example 8

[0065] Repeat Example 7, except that when multiple openings 204 are evenly distributed around the center of the fixing plate 202 along the circumferential direction of the fixing plate 202, the area of ​​the fixing plate 202 reserved between any two adjacent openings 204 in the circumferential direction of the fixing plate 202 is not less than the opening area of ​​the opening 204. Example 9

[0066] Example 8 is repeated, 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 of rotation of the movable plate 203 via the hinge 3 is along the circumferential direction of the surface of the fixed plate 202. Example 10

[0067] The embodiment 9 is repeated, except that the hinge 3 includes a shaft 301 and a shaft tube 302. The shaft tube 302 is vertically fixed to the fixing plate 202 at the edge of the opening 204, and the bottom of the tube wall of the shaft tube 302 has an arc-shaped notch 303 communicating with its cavity. The bottom end of the shaft 301 extends into the shaft tube 302 and can rotate freely in the shaft tube 302, while the top of the shaft 301 extends upward to the top wall of the fluidized furnace tube 1 and then extends to the outside. The end of the movable plate 203 is connected to the shaft 301 protruding from the arc-shaped notch 303. By rotating the shaft 301, the movable plate 203 rotates around the circumference of the fixed plate 202 with its end near the shaft 301 as the center of rotation, thereby realizing the opening and closing operation of the opening 204. Example 11

[0068] The embodiment 10 is repeated, except that the fixing plate 202 is a convex plate structure with a high center and low periphery. Example 12

[0069] Repeat Example 11, except that the opening 204 is a rectangular opening. Example 13

[0070] Repeat Example 11, except that the opening 204 is a polygonal opening. Example 14

[0071] Repeat Example 11, except that the opening 204 is a fan-shaped opening. Example 15

[0072] Repeat Example 14, as follows Figure 2 As shown, an air powder inlet 106 is also provided in the lower part of the upper chamber 101. Example 16

[0073] Repeat Example 15, except that the gas powder inlet 106 is connected tangentially to the upper chamber 101. Example 17

[0074] Repeat Example 16, except that the orientation of the gas powder inlet 106 is horizontal. Example 18

[0075] Repeat Example 16, except that the air-powder inlet 106 is oriented at an upward angle. Example 19

[0076] 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. Example 20

[0077] The embodiment 19 is repeated, except that a heating device 4 is also provided on the upper chamber 101 and the lower chamber 102, and the heating device 4 is an electric heating plate. Example 21

[0078] The embodiment 19 is repeated, except that a heating device 4 is also provided on the upper chamber 101 and the lower chamber 102, and the heating device 4 is a microwave heater.

[0079] Application Example 1 The high-calcium phosphate rock powder was roasted using the system described in Example 21. 80% of the phosphate rock powder with a phosphorus grade of approximately 19.2% (calculated as P2O5) and a calcium carbonate content of approximately 33.35% was granulated using a granulator to obtain phosphate rock pellets with a particle size of approximately 2 mm. The remaining 20% ​​of the phosphate rock powder was ground using a grinder and passed through a 400-mesh sieve to obtain phosphate rock micro powder (with a particle size not greater than 0.037 mm).

[0080] Fluidized gas (air) is introduced into the fluidized furnace tube 1 through the fluidized gas inlet 104. Phosphate ore pellets are added from the material inlet 103. The flow rate of the fluidized gas is adjusted (approximately 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℃ and the oxidation roasting time is 21 min (during this process, the movable plate 203 is always covered on the opening 204 of the fixed plate 202). The fluidized gas enters the upper chamber 101 through the through hole 201 and is discharged through the fluidized gas outlet 105.

[0081] After oxidative roasting, the rotation of the shaft 301 of the hinge 3 within the shaft tube 302 causes the movable plate 203 to rotate away from the opening 204, directly connecting the upper chamber 101 and the lower chamber 102 through the opening 204. At this time, the flow rate of the fluidized gas is increased (approximately 3 m / s), allowing the phosphate rock pellets to enter the upper chamber 101 through the opening 204 and suspend within it. Then, phosphate rock powder is added to the upper chamber 101 through the gas-powder inlet 106 for mixing and roasting. The mixing and roasting temperature is 700℃, and the mixing and roasting time is 12 minutes. During the mixing and roasting process, the phosphate rock powder continuously adheres to and fuses onto the phosphate rock pellets, ultimately yielding high-grade, high-strength finished phosphate rock pellets. Testing revealed that the finished phosphate rock pellets have a phosphorus content of approximately 28.7%, uniform morphology without damage or porosity, and an average compressive strength of approximately 2082 N (tested according to GB / T 14201-2018).

[0082] Comparative Example 1 Phosphate rock powder with a phosphorus content of approximately 19.2% (calculated as P2O5) and a calcium carbonate content of approximately 33.35% was granulated using a granulator to obtain phosphate rock pellets with a particle size of approximately 2 mm.

[0083] Fluidized gas (air) is introduced into the fluidized bed furnace tube 1 through the fluidized gas inlet 104. Phosphate ore pellets are added through the material inlet 103. The flow rate of the fluidized gas is adjusted (approximately 2.5 m / s) to suspend the phosphate ore pellets in the lower chamber 102 for oxidative roasting. The oxidative roasting temperature is 900℃, and the oxidative roasting time is 30 minutes (during which the movable plate 203 remains closed over the opening 204 of the fixed plate 202). The fluidized gas enters the upper chamber 101 through the through hole 201 and exits through the fluidized gas outlet 105. After oxidative roasting, the finished phosphate ore pellets are obtained. Testing shows that the phosphorus content of the finished phosphate ore pellets is approximately 29.5%, with uneven morphology, obvious damage, and numerous pores. Its average compressive strength is approximately 2135 N.

Claims

1. A system for fluidized bed roasting of phosphate rock powder, characterized in that: The system includes a fluidized bed furnace tube (1) and a partition plate (2); the partition plate (2) is disposed in the cavity of the fluidized bed furnace tube (1) and divides the cavity of the fluidized bed 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 provided on the partition plate (2).

2. The system according to claim 1, characterized in that: 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 its middle, the movable plate (203) is movably installed in the opening (204), and the through hole (201) is opened on the movable plate (203).

3. The system according to claim 2, characterized in that: Multiple openings (204) are provided on the fixed plate (202), and each opening (204) has a movable plate (203) installed independently.

4. The system according to claim 3, characterized in that: Multiple openings (204) are symmetrically distributed on both sides of the fixed plate (202) or evenly distributed around the center of the fixed plate (202) along the circumference of the fixed plate (202).

5. The system according to claim 4, characterized in that: When multiple openings (204) are evenly distributed around the center of the fixing plate (202) along the circumferential direction of the fixing plate (202), the area of ​​the fixing plate (202) reserved between any two adjacent openings (204) in the circumferential direction of the fixing plate (202) is not less than the opening area of ​​the opening (204).

6. The system according to claim 5, characterized in that: The opening (204) is one of the following: circular opening, rectangular opening, polygonal opening, or fan-shaped opening.

7. The system according to any one of claims 2-6, characterized in that: One end of the movable plate (203) is hinged to the fixed plate (202) at the edge of the opening (204) via the hinge (3); the movable plate (203) rotates via the hinge (3) to open and close the opening (204).

8. The system according to claim 7, characterized in that: The movable plate (203) rotates in the vertical direction or along the circumferential direction of the fixed plate (202) via the hinge (3).

9. The system according to claim 7, characterized in that: The hinge (3) includes a shaft (301) and a shaft tube (302); the shaft tube (302) is fixed horizontally on the fixing plate (202) at the edge of the opening (204), and the middle part of the tube wall of the shaft tube (302) is provided with an arc-shaped notch (303) that communicates with its tube cavity; the shaft (301) is sleeved in the shaft tube (302) and can rotate freely in the shaft tube (302), and the two ends of the shaft (301) extend horizontally through the tube wall of the fluidized furnace tube (1) and then extend to the outside; the end of the movable plate (203) is connected to the shaft (301) exposed at the arc-shaped notch (303); by rotating the shaft (301), the movable plate (203) rotates vertically with the end near the shaft (301) as the rotation center, thereby realizing the opening and closing operation of the opening (204).

10. The system according to claim 7, characterized in that: 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) that communicates with 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), and the top of the shaft (301) extends upward to the top wall of the fluidized furnace tube (1) and then extends to the outside; the end of the movable plate (203) is connected to the shaft (301) exposed at the arc-shaped notch (303); by rotating the shaft (301), the movable plate (203) rotates around the circumference of the plate surface of the fixing plate (202) with the end near the shaft (301) as the rotation center, thereby realizing the opening and closing operation of the opening (204).

11. The system according to claim 10, characterized in that: The fixing plate (202) is a convex plate-shaped structure with a high center and low periphery.

12. The system according to any one of claims 1-6 and 8-11, characterized in that: An air powder inlet (106) is also provided in the middle or lower part of the upper chamber (101).

13. The system according to claim 12, characterized in that: The gas powder inlet (106) is tangentially connected to the upper chamber (101).

14. The system according to claim 13, characterized in that: The air-powder inlet (106) is oriented horizontally or inclined upward.

15. The system according to claim 14, characterized in that: The plurality of gas powder inlets (106) are uniformly distributed along the circumference and / or axial direction of the upper chamber (101).

16. The system according to any one of claims 1-6, 8-11, and 13-15, characterized in that: A heating device (4) is also provided on the upper chamber (101) and / or the lower chamber (102), wherein the heating device (4) is an electric heater or a microwave heater.

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