A fluidized bed and a method for improving fluidization and inhibiting adhesion during reduction

Abstract

The present invention discloses a fluidized bed and a method for improving fluidization and inhibiting adhesion during the reduction process, belonging to the technical field of fluidized reduction of iron ore powder. The fluidized bed includes a reaction vessel, wherein a stirring rod is provided in the reaction vessel, and both ends of the stirring rod are respectively connected to the inner wall of the reaction vessel, and the stirring rod includes a shaft mounted on a base and N rings sleeved on the shaft, and the rings are independent of each other. The inner wall of the reaction vessel is provided with two opposite grooves for accommodating a bottom support, and the bottom support is adapted to the shape of the groove and is embedded in the groove. In order to adapt to the different height requirements of the stirring rod, the bottom support is a retractable bottom support. According to the actual situation and in combination with the distribution of iron ore powder, the present invention designs the specifications and placement height of the stirring rod to improve the degree of fluidization and inhibit adhesion.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluidized reduction of iron ore powder, and more particularly relates to a fluidized bed and a method for improving fluidization and inhibiting adhesion during the reduction process. Background Art

[0002] To overcome the constraints on the development of the steel industry caused by increasing environmental pollution from blast furnace ironmaking, the dwindling scarcity of coking coal resources, and the decline in iron ore quality, metallurgists are diligently exploring new technologies to reduce the coke ratio in blast furnace ironmaking and new non-blast furnace ironmaking processes. Fluidized bed ironmaking has been developed precisely to meet this trend. Fluidized beds, which can directly process fine ore without relying on coking coal, have attracted considerable attention. They can be combined with other molten reduction furnaces, such as iron bath furnaces, electric furnaces, and gasifiers, leveraging their excellent gas-solid phase contact to pre-reduce fine ore. They are widely used in the direct reduction step of the reduction process.

[0003] The fluidized bed direct reduction ironmaking process uses gas to reduce fine iron ore in a fluidized bed. It boasts a large gas-solid contact area, uniform temperature and concentration, excellent heat and mass transfer conditions, and high operating efficiency, making it the most efficient gas-based process. However, in addition to iron oxides, iron ore also contains refractory gangue, including SiO₂, Al₂O₃, CaO, MgO, and silicates formed by various metal oxides combined with SiO₂. The temperature required to reduce this gangue is generally very high. Under the fluidized bed reduction ironmaking temperatures of 600-1000°C, the gangue cannot be fully reduced, and the iron ore fines remain solid during the reduction process, making separation of the gangue from the fine iron ore difficult. Therefore, a high gangue content in the fluidized bed reduction product can compromise the purity of the low-temperature fluidized bed reduction product of the iron ore fines.

[0004] Among them, the adhesion / loss of fluid is the core problem of the fluidized direct reduction process. One solution is to coat the surface of iron ore powder with carbon powder for fluidized reduction reaction, such as patent CN107130076A. The coated carbon powder inhibits the active points of small iron grain growth. The metallic iron precipitated on the particle surface exists in the form of porous sponge iron, which prolongs the fluidization time, improves the fluidization effect, and inhibits adhesion and loss of fluid. However, coating the surface of iron ore powder with carbon powder for fluidized reduction will result in excessively high carbon content in the reduction product, which does not meet the furnace entry standards of the electric furnace. Long-term smelting will affect the service life of the electric furnace. To solve the problems caused by carbon powder coating, the internal structure of the fluidized bed can be improved to reduce the adhesion ratio.

[0005] Patent CN114410872A discloses a method for inhibiting cohesion loss during the fluidized reduction of iron ore powder. The method involves adding the iron ore powder to a double-tube reaction unit for fluidized reduction. During the reaction, an ultrasonic field is applied to the outside of the reaction unit. The ultrasonic generator includes first, second, and third ultrasonic generators spaced evenly counterclockwise around the periphery of the double-tube reaction unit. This invention applies an ultrasonic field during the pressurized fluidized reduction process, but this field imparts sonic forces on the reacting particles, further complicating the forces acting on the particles.

[0006] Patent CN103438669A discloses a fluidized bed dryer that prevents material from sticking. The dryer comprises a boiling chamber, a distribution plate located within the boiling chamber, a feed port located above the boiling chamber, an air outlet located at the top of the boiling chamber, and an air inlet and discharge port located below the boiling chamber. The air inlet is connected to a fan, is equipped with a filter and a heater, and is connected to the distribution plate via an air guide channel. The distribution plate is provided with dispersion columns, which effectively prevent the material from sticking together due to its own weight. Combined with the wind force of the guide, this further helps prevent material from sticking. Patent CN204285951U discloses a fluidized bed dryer that prevents material from sticking. The dryer comprises a boiling chamber, the top of which is connected to an air outlet chamber, the top of which has an air outlet, which is connected to the air inlet of a cyclone separator via a pipe. The inner cavity of the boiling chamber contains horizontally arranged air inlet plates, each of which is uniformly distributed with through holes. Patent CN216432259U discloses a fluidized bed drying device, comprising a shell and an air distribution plate. A feed port is provided on one side wall of the shell, and a discharge port is provided on the other side wall of the shell opposite to the feed port. The air distribution plate is horizontally arranged in the inner cavity of the shell, and the four sides of the air distribution plate are sealed with the inner cavity of the shell. A conical hopper is provided at the feed port in the drying chamber, and the large-diameter end of the conical hopper is fixedly connected to the bottom end of the feed port, and the small-diameter end of the conical hopper faces the air distribution plate. An inclined baffle is also provided below the conical hopper. There are multiple baffles, which are arranged in a cross-spaced manner from top to bottom, forming a gap for material to pass between adjacent baffles. The baffles are all fixed on the side walls of the shell. The above patents all have a barrier device for separating particles in the vertical direction. Its main purpose is to dry the fluidized bed particles, but iron ore powder is difficult to mix evenly at different heights. Summary of the Invention

[0007] 1. Problem to be solved

[0008] In response to the problem that existing iron ore powder is difficult to mix evenly at different heights, the present invention provides a fluidized bed and a method for improving fluidization and inhibiting agglomeration during the reduction process. The fluidized bed can effectively improve the mixing degree of iron ore powder in the vertical direction, thereby improving the fluidization degree and inhibiting agglomeration.

[0009] 2. Technical solution

[0010] In order to solve the above problems, the technical solutions adopted by the present invention are as follows:

[0011] During the fluidized reduction process of iron ore fines, the degree of fluidization is a key factor influencing the final metallization rate and bonding ratio. Iron ore fines are fluidized by the reducing gas under high-temperature conditions. This fluidization is related to factors such as the gas linear velocity and particle size. During the aeration process, gravity causes the iron ore fines to be distributed differently at different heights, exposing them to varying areas of reducing gas. This results in better fluidization for iron ore fines located at higher elevations and poorer fluidization for iron ore fines located at lower elevations. Poor fluidization leads to a high bonding ratio during the reduction process, severe particle aggregation, and a poor reduction state. This poor reduction state indicates a low reduction rate, resulting in a low metallization rate. Due to the high specific gravity of iron ore fines located at lower elevations, this significantly impacts the reduction state. While fluidization can be improved by increasing the gas linear velocity or reducing the particle size, both methods have limitations. In practice, increasing the gas linear velocity or reducing the particle size to improve fluidization increases the likelihood that the iron ore fines will be blown out of the reaction vessel.

[0012] The present invention discloses a process for improving fluidization and inhibiting adhesion in a fluidized bed reduction process. A stirring rod is added inside the fluidized bed reaction vessel to assist in the experiment. When the gas blows the iron ore powder on the baffle, it will also blow the stirring rod to rotate, so that the gas and solid are mixed evenly. The stirring can generate shear force and turbulence, mixing different components together. Specifically, the force applied during stirring can, on the one hand, cause the gas and solid to deform, thereby generating shear force. The shear force causes the gas and the components inside the solid to slide relative to each other, thereby achieving a mixing effect. At the same time, this part of the shear force acts on the particles that are adhered during the fluidization process, causing the adhered particles to break up and continue to fully fluidize. On the other hand, stirring can generate turbulence, causing the speed and direction of the fluid to change, thereby increasing the degree of mixing of the fluid and making the different components more evenly mixed together. In addition, the use of the stirring rod can also break up some of the gas in the form of bubbles, releasing reaction gases such as hydrogen, which continue to react with the iron ore powder, increase the reaction contact area, and increase the reaction rate.

[0013] A fluidized bed for improving fluidization and inhibiting adhesion during a reduction process includes a reaction vessel and a stirring rod disposed in the reaction vessel, wherein a baffle is disposed at the bottom of the reaction vessel, the stirring rod is located above the baffle, and the inner wall of the reaction vessel is provided with two opposing grooves for accommodating a base for the stirring rod, the base matching the shape of the groove and being embedded in the groove, the two ends of the stirring rod being respectively mounted on the base, and the two pairs of bases clamping the stirring rod in a certain position to prevent the position of the stirring rod from changing due to excessive gas velocity. To accommodate different height requirements of the stirring rod, the base is a retractable base, comprising an inner layer and an outer layer, the inner layer being slidably connected in the outer layer, the inner layer having two symmetrical slits formed at the bottom, each of which is provided with an elastic sheet, the elastic sheet being pressed against the gap between the inner layer and the outer layer, pulling and adjusting the position of the inner layer, and utilizing the elastic force of the elastic sheet on the inner and outer tube walls to increase friction and fix the position of the inner layer.

[0014] The base may also be a trapezoidal column. When the height of the stirring rod needs to be adjusted, a base of matching height is replaced and the base is cut.

[0015] The height of the stirring rod is adjusted according to the bed height L during the fluidization process. The stirring rod comprises a shaft mounted on a base and N rings mounted on the shaft, each of which is independent of one another. The rings can be elliptical or circular. A rod connects several circular rings, each of which is equipped with a longitudinal rod passing through the center. The ends of the longitudinal rod are fixedly connected to the ring to increase the force-bearing area of ​​the ring, making it easier to blow the ring and achieving more uniform stirring. During the reduction process, gas enters from the air inlet, passes through the fluidized bed baffle, and blows the iron ore powder up. At the same time, the gas blows the stirring rod, causing it to rotate. During the rotation, the iron ore powder is stirred, so that the iron ore powder within the stirring rod's rotation range is in a balanced fluidized state. By using the stirring rod, the fluidized state within the region is balanced, increasing the average fluidized state; at the same time, the interaction force between particles within the region is increased, making it less likely to cause a bonding effect, thereby improving the reaction metallization rate and reducing the bonding ratio.

[0016] Furthermore, the specifications of the stirring rod must also take into account the iron ore fines particle size, specifically the cross-sectional area of ​​the stirring rod. This is because, if a stirring rod with a larger cross-sectional area is used with a smaller iron ore fines particle size, the shear force distribution during stirring will be insufficient, and the turbulence effect will not be effectively generated. Conversely, a stirring rod with a smaller cross-sectional area will result in insufficient stirring and will not effectively break up the clumping parts of the iron ore fines. Therefore, stirring rods with different cross-sectional areas should be used for iron ore fines of different particle sizes.

[0017] Therefore, according to the actual situation and the distribution of iron ore powder, the present invention first designs the specifications of the stirring rod. According to the radius of the annular section in the stirring rod, the stirring rod is divided into four specifications, namely r1 = 1.5mm, 1.25mm, 1mm, and 0.5mm. The particle size of the ore powder used in each experiment is within a certain range, and the difference in particle size is not large. Therefore, three samples were randomly selected from the iron ore powder used in the experiment and their particle sizes were measured under an optical microscope. The results were d p1 , d p2 , d p3 , Substitute into formula (1) to obtain the stirring rod specification parameter F, and select the stirring rod specification:

[0018]

[0019] Where, F: stirring rod specification parameter; d p1 , d p2 , d p3 : particle size; r1: radius of the annular section (mm);

[0020] Then the placement height of the stirring rod is designed. The calculation process of the fluidization height L during the fluidization process is as follows:

[0021] The total mass M of solid particles in the fluidized bed is a constant

[0022] M=AL mf (1-ε mf )ρ s =AL(1-ε)ρ s (2)

[0023] Convert

[0024]

[0025] Where M is the total mass of solid particles; A is the cross-sectional area of ​​the fluidized bed (mm). 2 ;L mf : Bed height at the start of fluidization (mm); ε mf : bed voidage at the start of fluidization; L: bed height during the reaction (mm); ε: bed voidage during the reaction; ρ s : Density of particles g / mm 3 ;

[0026] Bed voidage ε during the reaction process:

[0027] ε=(VV S ) / V (4)

[0028] Where V: bed volume during fluidization, mm 3 ; V S :Iron ore powder volume mm3 ;

[0029] Here, the association

[0030] ε=Ar -0.21 (18Re+0.36Re 2 ) 0.21 (5)

[0031] Where Ar: Archimedean number Re:Reynolds numberRe=du f ρ g / μ g ; g: acceleration due to gravity m / s 2 ;d: reaction tube diameter mm; d p : Iron ore powder particle size (mm); ρ g : Density of gas g / mm 3 ρ s : Density of particles g / mm 3 ;μ g : Viscosity of reaction gas Pa·s; u f : gas linear velocity m / s;

[0032] Substituting formula (5) into formula (3), the calculation formula of L is:

[0033]

[0034] The above formula is the calculation formula for the bed height without adding a stirring rod. However, after adding a stirring rod, the bed height is affected to a certain extent. Therefore, the above formula needs to be modified according to the actual situation. The final calculation formula for L is

[0035]

[0036] Where, M: total mass of solid particles; ρ s : Density of particles g / mm 3 ; A: cross-sectional area of ​​fluidized bed (mm) 2 ; l0: circumference of the ring (mm); N: number of rings; r1: radius of the ring section (mm); r2: radius of the axis (mm); l: length of the axis (mm); Ar: Archimedean number; Re: Reynolds number.

[0037] When the ring is an elliptical ring, the height of the stirring rod is:

[0038]

[0039] Where, a is the semi-major axis of the elliptical ring in mm; b is the semi-minor axis of the elliptical ring in mm.

[0040] When the ring is a circular ring, the height of the stirring rod is:

[0041]

[0042] Where, a: the radius of the ring in mm.

[0043] The addition of a stirring rod affects the fluidization height of the fluidized bed. Therefore, the present invention incorporates the influence of the stirring rod, taking into account factors such as the shape, cross-sectional area, and number of the stirring rods. This factor, along with the increased height of the fluidized bed, corrects the fluidized bed height. This addition of height allows the resulting fluidized bed height L to more accurately match the fluidization height in actual experiments, reducing errors and ensuring greater compliance with experimental standards.

[0044] After calculating the fluidization height L, the stirring rod is positioned according to this height. L represents the bed height in the dense phase, with the dilute phase located above the dense phase. At this height, L is the stirring rod's placement height. This allows the stirring rod to fully mix the iron ore fines in the dense and dilute phases, increasing the fluidization level in the stirring zone and the bed height in the dense phase. This improves the overall fluidization level, facilitates the reduction reaction, and increases the metallization rate. Experiments can also be conducted at multiple locations below L to determine the optimal stirring position.

[0045] The process for improving fluidization and inhibiting adhesion using the aforementioned fluidized bed includes the following steps: heating the fluidized bed to 600-800°C, introducing H2 as an experimental gas, and maintaining the temperature for 30-50 minutes. After the reduction reaction is complete, N2 is introduced again for 5 minutes to protect the iron ore fines from oxidation, and then the temperature is cooled to room temperature. During the reaction, the gas velocity is 0.1-0.6 m / s, and the pressure is 0-0.5 MPa. The specific experimental values ​​are determined based on experimental requirements. During the experiment, after the gas passes through the fluidized bed baffle, it blows up the iron ore fines and reacts with them, while simultaneously blowing on the stirring rod, causing it to rotate.

[0046] 3. Beneficial effects

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention designs the specifications and placement height of the stirring rod based on the actual situation and the distribution of the iron ore powder, thereby promoting the full mixing of the iron ore powder at different heights, improving the fluidization degree, and inhibiting adhesion;

[0049] (2) The present invention adds a stirring rod inside the fluidized bed reaction vessel to assist the experiment. When the gas blows the iron ore powder, it also blows the stirring rod to rotate, so that the gas and solid are mixed evenly, the sticky particles are broken, the reaction contact area is increased, and the reaction rate is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise specified, these drawings are intended only to conceptually illustrate the structures described herein and are not necessarily drawn to scale.

[0051] Figure 1 Schematic diagram of the fluidized bed structure;

[0052] Figure 2 Schematic diagram of the stirring rod structure;

[0053] Figure 3 Schematic diagram of the inner wall structure of the reaction vessel;

[0054] Figure 4 is a top-down cross-sectional view of a reaction vessel;

[0055] Figure 5 Schematic diagram of the bottom support structure;

[0056] Figure 6 This is a top view cross-section of the base;

[0057] Figure 7 Schematic diagram of the base;

[0058] In the figure: 1. reaction vessel; 11. groove; 2. stirring rod; 21. shaft; 22. ring; 221. longitudinal rod; 3. bottom support; 31. inner layer; 32. outer layer; 33. elastic sheet; 4. air inlet; 5. air outlet; 6. baffle. DETAILED DESCRIPTION

[0059] The following detailed description of exemplary embodiments of the present invention refers to the accompanying drawings, which form a part of the description, and in which exemplary embodiments of the present invention that can be implemented are shown as examples. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to implement the present invention, it should be understood that other embodiments can be implemented and various changes can be made to the present invention without departing from the spirit and scope of the present invention. The following more detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but is merely for illustration and does not limit the description of the features and characteristics of the present invention, so as to propose the best way to perform the present invention and be sufficient to enable those skilled in the art to implement the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

[0060] A method for improving fluidization and inhibiting adhesion during a fluidized bed reduction process includes the following steps: heating the temperature to 800°C, introducing H2 as an experimental gas, and maintaining the temperature for 50 minutes. After the reduction reaction is complete, introducing N2 for another 5 minutes to protect the iron ore fines from oxidation, and then cooling the temperature to room temperature. During the reaction, the gas velocity was 0.6 m / s and the pressure was 0.5 MPa. During the experiment, after the gas passed through baffle 6, it lifted the iron ore fines and reacted with them, while simultaneously blowing on the stirring rod 2, causing it to rotate.

[0061] The specific process is as follows: Before commencing the fluidized reduction experiment of iron ore fines, close the outlet valve and introduce nitrogen into the fluidized bed. The pressure inside the fluidized bed will rise. Once it reaches 0.4 MPa, close the nitrogen valve and stop introducing nitrogen into the fluidized bed. If the pressure gauge reading remains stable for an extended period, the entire apparatus is airtight.

[0062] Weigh 20.0g of iron ore powder with a particle size of 50-80 mesh, calculate the particle size range of the ore powder, and randomly select three particle sizes d p1 , d p2 , d p3 , consult the data to obtain the parameters such as the gas viscosity of the reaction gas. Substitute the parameters into equations (1) and (7) to obtain the specifications r1 of the stirring rod 2 and the bed height L. According to the obtained fluidization height, the bottom bracket 3 is extended to the corresponding length, and then the stirring rod 2 is fixed inside the fluidized bed through the bottom bracket 3. Taking the height L as an example: at this time, the position above the stirring rod 2 is the dilute phase area, and the position below is the dense phase area. The weighed iron ore powder is placed in the reaction vessel 1, and the fluidized bed is heated by a resistance heating furnace. When the temperature in the fluidized bed rises to the target temperature, N2 is first introduced from the air inlet 4 for 5 minutes to discharge the air inside the fluidized bed from the air outlet 5 to prevent residual gas from affecting the experiment. Then, the experimental gas H2 is introduced, and the fluidized bed temperature is kept stable at 800℃ within the reduction time of 50 minutes. During this period, the gas linear velocity is adjusted to 0.6m / s and the pressure value is 0.5MPa through the data measurement software. In this process, after the gas passes through the baffle 6, it blows up the iron ore powder and reacts with it, and at the same time blows the stirring rod 2, causing it to rotate. This not only breaks up any agglomerated particles within the stirring range but also refluidizes the iron ore fines in the area. After the reduction reaction is complete, N2 is introduced again for 5 minutes to protect the iron ore fines from oxidation, followed by cooling. After the fluidized bed cools to room temperature, the reduction product is removed and analyzed using potassium dichromate volumetry and ferric chloride titration. The mass fractions of TFe (total iron) and MFe (metallic iron) are measured, and the metallization rate and bonding ratio of the iron ore fines are calculated. The results are compared with those obtained without stirring rod 2.

[0063] A fluidized bed for improving fluidization and inhibiting adhesion during a reduction process comprises a reaction vessel 1, a baffle 6 and a stirring rod 2, wherein the baffle 6 is located at the bottom of the reaction vessel 1, and the stirring rod 2 is located above the baffle 6. The inner wall of the reaction vessel 1 is provided with two opposite grooves 11 for accommodating a bottom support 3 of the stirring rod 2. The bottom support 3 is adapted to the shape of the groove 11 and is embedded in the groove 11. The two ends of the stirring rod 2 are respectively mounted on the bottom support 3. In order to adapt to the different height requirements of the stirring rod 2, the bottom support 3 is a retractable bottom support 3. In Example 1, the bottom support 3 is a retractable trapezoidal column. Figure 5 As shown, the telescopic structure includes an inner layer 31 and an outer layer 32. The inner layer 31 is a cylinder and the outer layer 32 is a trapezoidal column. Two slits 311 are symmetrically provided at the bottom of the inner layer 31. An elastic sheet 33 is inserted into each slit 311. The elastic sheet 33 is a tile-shaped copper sheet. The elastic sheet 33 is pressed against the gap between the inner layer 31 and the outer layer 32 to pull and adjust the position of the inner layer 31. The elastic force between the inner and outer layer walls of the elastic sheet 33 is used to increase friction and fix the position of the inner layer 31.

[0064] The stirring rod 2 includes a shaft 21 mounted on a base and N rings 22 sleeved on the shaft 21 . The rings 22 are independent of each other. A longitudinal rod 221 passing through the center is provided on the ring 22 . Both ends of the longitudinal rod 221 are fixedly connected to the ring 22 .

[0065] The specifications of the groove 11 are as follows: the total length of the groove 11 is 120 mm, the upper base of the trapezoidal cross section is 2 mm, the lower base is 3.5 mm, and the height is 1.2 mm;

[0066] Specifications of the stirring rod 2: The stirring rod 2 shaft 21 is 22 mm long, has a circular cross section, and a cross-sectional diameter of 2 mm;

[0067] Specifications of the ring 22: The radius of the ring 22 is 4 mm;

[0068] Specifications of the elliptical ring 22: the semi-major axis 21 is 7.5 mm, and the semi-minor axis 21 is 4 mm;

[0069] Specifications of bottom bracket 3: bottom bracket 3 is a trapezoidal column with side dimensions of: upper bottom 2mm, lower bottom 3.5mm, and height 1.2mm. Both are stretchable, with lengths of 40mm and 30mm respectively when not stretched, and can be stretched to a maximum length of 80mm and 60mm.

[0070] Example 1

[0071] First, select the parameters of stirring rod 2 according to the specification parameter F of stirring rod 2.

[0072]

[0073] The three randomly selected particle sizes d in Example 1 p1, d p2 , d p3 They are 1.30mm, 1.18mm, and 1.42mm respectively. The calculated F is 19.53, r1 is 1.50mm, and the gas linear velocity here is 0.3m / s.

[0074] Then the placement height of the stirring rod 2 is designed. The fluidization height L during the fluidization process is based on:

[0075]

[0076] Where M is the total mass of solid particles, which is 20.00 g; A is the cross-sectional area of ​​the fluidized bed, which is 314.16 mm 2 ;Ar: Archimedean number, 142288.01;Re: Reynolds number, 67.42;N: number of rings, 2;ρ s : The density of the particles is 4.7*10 -3 g / mm 3 ; r1: the radius of the cross section of the ring 22, which is 1.50 mm; r2: the radius of the shaft 21, which is 1.00 mm; a: the major semi-axis of the elliptical ring 22, which is 7.50 mm; b: the minor semi-axis of the elliptical ring 22, which is 4.00 mm; l: the length of the shaft 21, which is 22.00 mm; the height of the stirring rod 2 in Example 1 is calculated to be 26.84 mm.

[0077] After reduction using the fluidized bed of Example 1, the metallization rate of the iron ore powder was 60.21%, and the bonding ratio was 27.41%.

[0078] Example 2

[0079] First, select the parameters of stirring rod 2 according to the specification parameter F of stirring rod 2.

[0080]

[0081] The three randomly selected particle sizes d in Example 1 p1 , d p2 , d p3 They are 0.4265mm, 0.7326mm, and 0.7545mm respectively. The calculated F is 39.82, r1 is 1.25mm, and the gas linear velocity here is 0.2m / s.

[0082] Then the placement height of the stirring rod 2 is designed. The fluidization height L during the fluidization process is based on:

[0083]

[0084] Where M is the total mass of solid particles, which is 20.00 g; A is the cross-sectional area of ​​the fluidized bed, which is 314.16 mm 2;Ar: Archimedean number, 16819.00;Re: Reynolds number, 44.95;N: number of rings 22, 2;ρ s : The density of the particles is 4.7*10 -3 g / mm 3 ; r1: the radius of the cross section of the ring 22, which is 1.25 mm; r2: the axis radius, which is 1.00 mm; a: the major semi-axis of the elliptical ring 22, which is 7.50 mm; b: the minor semi-axis of the elliptical ring 22, which is 4.00 mm; l: the length of the axis 21, which is 22.00 mm; the calculated placement height of the stirring rod 2 in Example 2 is 36.20 mm.

[0085] After reduction using the fluidized bed of Example 2, the metallization rate of the iron ore powder was 64.36%, and the bonding ratio was 26.88%.

[0086] Example 3

[0087] First, select the parameters of stirring rod 2 according to the specification parameter F of stirring rod 2.

[0088]

[0089] The three randomly selected particle sizes d in Example 3 p1 , d p2 , d p3 They are 0.5004mm, 0.7443mm, and 0.6225mm respectively. The calculated F is 40.81, r1 is 1.25mm, and the gas linear velocity here is 0.2m / s.

[0090] Then the placement height of the stirring rod 2 is designed. The fluidization height L during the fluidization process is based on:

[0091]

[0092] Where M is the total mass of solid particles, which is 20.00 g; A is the cross-sectional area of ​​the fluidized bed, which is 314.16 mm 2 ;Ar: Archimedean number, 15615.18;Re: Reynolds number, 44.95;N: number of rings 22, 2;ρ s : The density of the particles is 4.7*10 -3 g / mm 3 ; r1: the radius of the cross section of the ring 22 is 1.25 mm; r2: the radius of the shaft 21 is 1.00 mm; a: the major semi-axis of the elliptical ring 22 is 7.50 mm; b: the minor semi-axis of the elliptical ring 22 is 4.00 mm; l: the length of the shaft 21 is 22.00 mm; the height of the stirring rod 2 in Example 3 is calculated to be 37.05 mm.

[0093] After reduction using the fluidized bed of Example 3, the metallization rate of the iron ore powder was 62.79% and the bonding ratio was 28.77%.

[0094] Example 4

[0095] First, select the stirring rod parameters according to the stirring rod 2 specification parameter F, according to

[0096]

[0097] Three particle sizes d randomly selected in the embodiment p1 , d p2 , d p3 They are 0.5471mm, 0.6537mm, and 0.7648mm respectively. The calculated F is 38.77, r1 is 1.25mm, and the gas linear velocity here is 0.2m / s

[0098] Then the placement height of the stirring rod is designed. The fluidization height L during the fluidization process is determined according to:

[0099]

[0100] Where M is the total mass of solid particles, which is 20.00 g; A is the cross-sectional area of ​​the fluidized bed, mm 2 , which is 314.16mm 2 ;Ar: Archimedean number, 18216.29;Re: Reynolds number, 44.95;N: number of rings 22, 2;ρ s : Density of particles g / mm 3 , which is 4.7*10 -3 g / mm 3 ; r1: radius of the ring section in mm, 1.25 mm; r2: radius of the axis 21 in mm, 1.00 mm; a: radius of the ring 22 in mm, 4.00 mm; l: length of the axis 21 in mm, 22.00 mm; The calculated placement height of the stirring rod 2 in the embodiment is 34.70 mm.

[0101] The metallization rate of the iron ore powder in Example 4 is 63.76%, and the bonding ratio is 25.60%.

[0102] Comparative Example 1

[0103] In Comparative Example 1, the fluidized bed was not provided with a stirring rod 2, and the other parameters were the same as those in Examples 1-3. The metallization rate of the iron ore powder finally obtained was 48.30%, and the bonding ratio was 36.30%.

Claims

1. A fluidized bed comprising a reaction vessel (1), wherein a baffle (6) is provided at the bottom of the reaction vessel (1), characterized in that: The reaction container (1) is provided with a stirring rod (2), the stirring rod (2) is located above the baffle (6), and both ends of the stirring rod (2) are respectively connected to the inner wall of the reaction container (1), the stirring rod (2) comprises a shaft (21) mounted on the base (3) and a plurality of rings (22) sleeved on the shaft, and the rings (22) are independent of each other; The ring (22) is provided with a longitudinal rod (221) passing through the center, and both ends of the longitudinal rod (221) are fixedly connected to the ring (22); The placement height of the stirring rod (2) is Where, L: the height of the stirring rod (2), mm; M: the total mass of the solid particles; ρ s : Density of particles g / mm 3 ; A: cross-sectional area of ​​fluidized bed (mm) 2 ; l0: circumference of the ring (mm); N: number of rings; r1: radius of the ring (22) section (mm); r2: radius of the axis (21) (mm); l: length of the axis (21) (mm); Ar: Archimedean number; Re: Reynolds number.

2. The fluidized bed according to claim 1, characterized in that The ring (22) is an elliptical ring, and the placement height of the stirring rod (2) is: Where, a is the semi-major axis of the elliptical ring in mm; b is the semi-minor axis of the elliptical ring in mm.

3. The fluidized bed according to claim 1, characterized in that The ring (22) is a circular ring, and the placement height of the stirring rod (2) is: Where, a: the radius of the ring in mm.

4. The fluidized bed according to claim 1, wherein The selection of the annular section radius r1 is based on: (1) Where, F: Specification of stirring rod (2); d p1 , d p2 , d p3 : The particle size of the particles is randomly selected from the particle size of the iron ore powder.

5. The fluidized bed according to claim 1, characterized in that The inner wall of the reaction container (1) is provided with two opposite grooves (11) for accommodating the base (3). The base (3) is adapted to the shape of the groove (11), and the two ends of the shaft (21) are respectively mounted on the base (3).

6. The fluidized bed according to claim 5, characterized in that The base (3) is a retractable base (3), comprising an inner layer (31) and an outer layer (32), wherein the inner layer (31) is slidably connected in the outer layer (32), and two slits (311) are symmetrically provided at the bottom of the inner layer (31), wherein an elastic sheet (33) is inserted into each of the slits (311), and the elastic sheet (33) abuts against the gap between the inner layer (31) and the outer layer (32).

7. The method for improving fluidization and inhibiting adhesion using the fluidized bed according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: adding iron ore powder; heating to 600-800° C., introducing experimental gas H2, and maintaining the temperature for 30-50 minutes; after the reduction reaction is completed, introducing N2 again for 5-8 minutes, and then cooling to room temperature.

8. The method according to claim 7, wherein During the reaction, the gas linear velocity is 0.1-0.6 m / s and the pressure is 0-0.5 MPa.

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